JP2004171735A - Optical data recording method - Google Patents

Abstract

Provided is a method for optically recording data that can be correctly performed even when recording is performed at a high transfer rate.
An optical data recording method according to the present invention modulates data to be recorded to generate a plurality of recording modulation codes, and irradiates an optical disc with a pulsed light beam to thereby generate the plurality of recording modulation codes. A plurality of recording marks and spaces each having a length corresponding to each of the recording marks are formed on the optical disc. At least two of the plurality of recording marks are arranged at the head, and first pulses 201 and 204 for forming the start end of the recording mark, and arranged at the end, forming the end end of the recording mark. Light emitted based on a recording pulse train including last pulses 203 and 206 for storing the multi-pulse trains 202 and 205 arranged between the first pulse and the last pulse for forming a central portion of the recording mark. When the reference period of the recording modulation code is T, the pulse period with the multi-pulse trains 202 and 205 is longer than T.
[Selection diagram] FIG.

Description

  The present invention relates to a method for optically recording data on a data recording medium such as an optical disk.

  As a medium for recording large-capacity digital data, a data storage medium for optically recording data has attracted attention.

  A phase change optical disk is one of recordable data recording media. A phase-change optical disk has a recording film that is melted by heating, and the light beam of the recording film is irradiated by irradiating the rotating disk with a semiconductor laser light beam modulated based on data to be recorded. A phase change is caused in the part where the change occurred, and the data is recorded.

  When the light beam intensity is high, the portion of the recording film irradiated with the light beam is heated to a high temperature and then rapidly cooled. Therefore, the portion of the recording film irradiated with the light beam becomes amorphous. When the light beam intensity is relatively weak, the portion irradiated with the light beam is heated to a medium high temperature, and then gradually cooled. Therefore, the portion irradiated with the light beam is crystallized. The amorphous portion is called a normal mark, and the crystallized portion between the marks is usually called a space. Binary data is recorded using the mark and the space. Rows of marks and spaces are formed on tracks spirally provided on the optical disc. Generally, the laser power when the light beam intensity is high is called peak power, and the laser power when the light beam intensity is low is called bias power.

  When reading data recorded on a phase change optical disk, a light beam that is weak enough to cause no phase change in the recording film is applied to the optical disk, and the reflected light is detected. Normally, a mark portion that has been made amorphous has a low reflectance, and a crystallized space portion has a high reflectance. Therefore, a difference in the amount of reflected light between the mark portion and the space portion is detected to generate a reproduced signal, the reproduced signal is binarized, and then demodulated to obtain recorded data.

  There are a mark position recording method and a mark edge recording method as a data recording method on a phase change optical disk. Normally, the mark edge recording (mark length recording) method can increase the information recording density. In the mark edge recording method, a longer mark is recorded than in the mark position recording method.

  When a long mark is recorded on a phase change optical disk by irradiating peak power, the width of the mark in the radial direction becomes larger in the latter half of the mark due to heat accumulation in the recording film. For this reason, when performing direct overwrite, there remains a problem that unerased residue occurs or signal crosstalk between tracks occurs, thereby significantly deteriorating the signal quality.

  In order to solve this problem, for example, Patent Document 1 discloses that a mark in a mark edge recording system is divided into a start end, an intermediate portion, and an end, and the start end and the end are each provided with one laser pulse having a fixed length. And forming the intermediate portion with a plurality of laser pulses having a constant period. According to this method, by forming the intermediate portion with a plurality of laser pulses, heat accumulation can be suppressed and the mark width can be prevented from being widened. On the other hand, since the start and end portions of the mark are formed by a laser pulse having a fixed length, sufficient heat energy is given to the recording film. For this reason, even when direct overwriting is performed, it is possible to reduce jitter due to the edge portion of the mark formed.

  1 and 2 show an example of the waveform of a recording pulse train used to form marks of various lengths in the prior art. For example, when a recording modulation code obtained by converting data to be recorded by a Run Length Limited (2, 10) modulation method is recorded by a mark edge recording method, a recording modulation code having a length from the shortest 3T to the longest 11T exists. I do. Here, T represents the reference period of the recording modulation code of the recording mark. Marks and spaces recorded by the mark edge recording method have a continuous length represented by the length of a recording modulation code.

  When forming these marks on the optical disc, a plurality of laser pulses are used as described above. As shown in FIG. 1, in a mark having each length, the first pulse 801 is called a first pulse, and the last pulse 804 is called a last pulse. The pulses 802 and 803 between the first pulse and the last pulse are called a multi-pulse train, and are composed of pulses having a period T.

  The multi-pulse train of the 6T mark includes two pulses, and the multi-pulse train of the 7T mark includes three pulses. The multi-pulse train of the 5T mark is actually composed of one pulse. Each time the mark becomes longer by T, the number of pulses increases by one, and conversely, each time the mark becomes shorter by T, the number of pulses decreases by one. Therefore, a 4T mark is composed of only a first pulse and a last pulse, and has no multi-pulse train. The 3T mark is composed of one pulse. Usually, the width of the first pulse is 0.25T to 1.5T, and the width of the last pulse is 0.25T to 1T. The width of one pulse constituting the multi-pulse train is from 0.25T to 0.75T.

  The waveform of the laser pulse shown in FIG. 2 is different from the waveform of the laser pulse shown in FIG. 1 in the width of the last pulse, but the relationship between the number of multi-pulse trains forming the intermediate portion and the length of the mark is shown in FIG. Same as pulse.

When a mark is formed by such a method, marks of different lengths can be easily formed by changing the number of pulses in the middle part. However, according to this conventional method, when the data recording speed is increased, for example, when data is recorded on an optical disc at a high transfer rate, the response speed of the laser diode is not ideally high enough, so that the light emission is reduced. The rise and fall of the pulse in the waveform become dull, and the set amount of heat cannot be given to the recording film of the optical disk. In particular, since the pulse width of the multi-pulse train is about 0.25T to 0.75T, it is difficult to generate a sinusoidal pulse depending on, for example, the rise time and fall time of the laser, and a problem that a correct mark cannot be formed. Occurs.
JP-A-9-7176

  An object of the present invention is to solve such a conventional problem and to provide a method for optically recording data capable of performing correct recording.

  The optical data recording method of the present invention modulates data to be recorded to generate a plurality of recording modulation codes, and irradiates a pulsed light beam to the optical disc to correspond to each of the plurality of recording modulation codes. A plurality of recording marks and spaces having a length are formed on the optical disc. At least two of the plurality of recording marks are arranged at the beginning, a first pulse for forming a start end of the recording mark, and a last pulse arranged at the end for forming an end end of the recording mark. The recording modulation code formed by a light beam irradiated based on a recording pulse train including a pulse and a multi-pulse train arranged between the first pulse and the last pulse and forming a central portion of the recording mark; Is set to T, the pulse cycle of the multi-pulse train is made longer than T.

  In a preferred embodiment, the plurality of recording marks have different lengths represented by nT (n is an integer of 1 or more), and are included in the recording pulse train in at least two recording marks having different n. The number of pulses is equal.

  In a preferred embodiment, in the at least two recording marks, irradiation power of a light beam generated by at least one of the first pulse, the multi-pulse train, and the last pulse is different.

  In a preferred embodiment, in the plurality of recording marks, the number of pulses included in the recording pulse trains of the 2nT and (2n + 1) T recording marks is equal.

  In a preferred embodiment, in the plurality of recording marks, the number of pulses included in the recording pulse trains of the (2n-1) T and 2nT recording marks is equal.

  In one preferred embodiment, in the plurality of recording marks, the pulse widths of the first pulses are all equal.

  In a preferred embodiment, in the plurality of recording marks, the pulse widths of the last pulses are all equal.

  In a preferred embodiment, in the plurality of recording marks, the pulse width and the pulse interval of the multi-pulse train are all equal.

  In a preferred embodiment, the plurality of recording marks include a recording mark formed by a light beam irradiated based on a recording pulse train including only one pulse, and a recording pulse train including only the first pulse and the last pulse. The recording pulse sequence includes a recording mark formed by a light beam irradiated based on the recording pulse, and a pulse width of any pulse of the recording pulse train is 1T or more.

  In a preferred embodiment, the plurality of recording marks include a recording mark formed by a light beam irradiated based on a recording pulse train including only one pulse, and a recording pulse train including only the first pulse and the last pulse. And a recording mark formed by a light beam irradiated based on the recording pulse train, and an interval between any two adjacent pulses of the recording pulse train is 1T or more.

  In a preferred embodiment, in the recording pulse train, in a multi-pulse region where the multi-pulse train is arranged, a multi-pulse duty obtained by dividing a pulse width of the multi-pulse train by a cycle of the multi-pulse train, or The amplitude and position of at least one pulse of the recording pulse train are set so that a multi-pulse amplitude average value obtained by dividing the amplitude integral value by the time width of the multi-pulse region becomes a predetermined value.

  In a preferred embodiment, the period of the multi-pulse train is set to 2T.

  In a preferred embodiment, the multi-pulse region is defined by a rising timing of a leading pulse of the multi-pulse train and a falling timing of a last pulse.

  In a preferred embodiment, the multi-pulse region is defined by a falling timing of the first pulse and a rising timing of the last pulse.

  In a preferred embodiment, a rising timing of a leading pulse of the recording pulse train and a pulse width of each pulse of the recording pulse train are set.

  In a preferred embodiment, the leading space width sandwiched between the first pulse and the leading pulse of the pulse train is substantially equal to the trailing space width sandwiched between the last pulse and the last pulse of the multi-pulse train. Set to.

  In a preferred embodiment, the plurality of recording modulation codes have different lengths represented by nT (n is an integer of 1 or more), and the amplitude and position of at least one pulse of the set recording pulse train are The value is constant regardless of the length of the recording modulation code.

  In a preferred embodiment, the plurality of recording modulation codes have different lengths represented by nT (n is an integer of 1 or more), and the amplitude and position of at least one pulse of the set recording pulse train are Are set to different values depending on whether the length of the recording modulation code is an odd multiple or an even multiple of T.

  In a preferred embodiment, the plurality of recording modulation codes have different lengths represented by nT (n is an integer of 1 or more), and the amplitude and position of at least one pulse of the set recording pulse train are Is set to a different value for each length of the recording modulation code.

  In a preferred embodiment, the plurality of recording modulation codes have different lengths represented by nT (n is an integer of 1 or more), and the plurality of recording modulation codes are classified into a plurality of code groups, and The amplitude and position of at least one pulse of the set recording pulse train are set to different values for each code group.

  In a preferred embodiment, each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more), and the multi-pulse duty or the average value of the multi-pulse amplitude is represented by the recording modulation code. Set to a constant value regardless of the length of.

  In a preferred embodiment, each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more), and the multi-pulse duty or multi-pulse amplitude average value is determined by the recording modulation code. A different value is set depending on whether the length is an odd multiple or an even multiple of T.

  In a preferred embodiment, each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more), and the multi-pulse duty or the average value of the multi-pulse amplitude is represented by the recording modulation code. Set a different value for each length of.

  In a preferred embodiment, the plurality of recording modulation codes have different lengths represented by nT (n is an integer of 1 or more), and the plurality of recording modulation codes are classified into a plurality of code groups. The multi-pulse duty or multi-pulse amplitude average value is set to a different value for each code group.

  In a preferred embodiment, the multi-pulse duty or multi-pulse amplitude average value is formed near a center of a reproduction signal obtained by forming a recording mark formed using the recording pulse train and reproducing the formed recording mark. It is determined by evaluating the amplitude value.

  The data recording apparatus of the present invention includes a motor for mounting and rotating an optical disk, a light source, an optical head for irradiating a light beam from the light source to the optical disk mounted on the motor, and modulating data to be recorded. A signal processing unit that generates a plurality of recording modulation codes, and irradiating the light beam to form a plurality of recording marks having a length corresponding to the plurality of recording modulation codes on the optical disc. A recording pulse train generation unit that generates a plurality of recording pulse trains for driving the light source based on the plurality of recording modulation codes. At least two of the plurality of recording pulse trains are arranged at the beginning, a first pulse for forming a start end portion of the recording mark, and a last pulse for being arranged at the end and forming an end end portion of the recording mark. A pulse, and a multi-pulse sequence arranged between the first pulse and the last pulse, for forming a central portion of the recording mark, wherein when a reference period of the recording modulation code is T, the multi-pulse sequence Is longer than T.

  In a preferred embodiment, each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more), and the recording pulse train generation unit includes at least two recording modulation codes having different n. , A recording pulse train equal to the number of pulses is generated.

  In a preferred embodiment, in the recording pulse trains corresponding to the at least two recording modulation codes, the irradiation power of the light beam generated by at least one of the first pulse, the multi-pulse train, and the last pulse is different.

  In a preferred embodiment, in the recording pulse train, in a multi-pulse region where the multi-pulse train is arranged, a multi-pulse duty obtained by dividing a pulse width of the multi-pulse train by a cycle of the multi-pulse train, or The recording pulse train generation unit generates a recording pulse train including at least one pulse whose amplitude and position are set so that a multipulse amplitude average value obtained by dividing the amplitude integral value by the time width of the multipulse region becomes a predetermined value. Generate.

  In a preferred embodiment, the recording pulse train generator generates the multi-pulse train having a period of 2T.

  According to the present invention, even when data is recorded at a high transfer rate, a recording mark having a correct shape is hardly affected by a rise time and a fall time of a laser and is formed on a data recording medium such as an optical disk. be able to.

(1st Embodiment)
FIG. 3 is a block diagram showing a first embodiment of the data recording device according to the present invention. As shown in FIG. 3, the data recording apparatus 100 includes a spindle motor 102, an optical head 103, a light beam control unit 104, a servo unit 105, a reproduction binarization unit 106, a digital signal processing unit 107, A recording compensating unit 108 and a CPU 109 are provided.

  The spindle motor 102 places the optical disc 101 and rotates it. The optical disc 101 has one or a plurality of spiral or concentric tracks for recording data. The optical disc 101 has a recording film that is melted by heating, and when irradiated with a light beam of a semiconductor laser modulated based on data to be recorded, a phase change occurs in a portion of the recording film irradiated with the light beam. Occurs.

  The optical head 103 has a laser diode as a light source, and irradiates the optical disc 101 with a light beam for recording data. Further, it converts the light reflected from the optical disc 101 into an electric signal, and outputs the converted signal to the reproduction binarization unit 106 as a reproduction signal.

  The light beam control unit 104 generates a current for driving the laser diode of the optical head 103 and controls the power of the light beam output from the laser diode based on an instruction from the CPU 109.

  The servo unit 105 controls the position of the optical head 103, and performs focus control and tracking control of a light beam emitted from the optical head 103. Further, the rotation of the spindle motor 102 is controlled. The reproduction binarization unit 106 amplifies the reproduction signal obtained from the optical head 103, performs a binarization process, and generates a binarization signal. Further, a clock synchronized with the binarized signal is generated by an internal PLL (not shown).

  The digital signal processing unit 107 performs predetermined demodulation processing and error correction processing on the binary signal. At the time of data recording, an error correction code is added to the recorded data, a predetermined modulation process is performed, and modulated data is generated. The recording compensating unit 108 converts the modulated data into optical modulated data composed of a pulse train, and further stores the pulse width and the like of the optical modulated data in the information obtained from the reproduction signal in the disk information area and in the CPU 109 in advance. The information is adjusted based on the information, converted into a signal of a recording pulse train suitable for forming a mark, and output. The CPU 109 controls the entire data recording device 100.

  The host PC 110 includes a computer (not shown), an application (not shown), and an operating system (not shown), and requests the data recording device 100 to perform recording and reproduction. When the optical disk 101 is inserted into the data recording device 100, the data recording device 100 outputs a light beam having a predetermined irradiation power from the optical head 103, and outputs the light beam to the disk information area of the optical disk 101 (normally provided near the innermost circumference of the disk). The light beam control unit 104 and the servo unit 105 are controlled so as to reproduce the same. As a result, irradiation power information and the like at the time of recording are obtained.

  Next, the operation at the time of recording will be described with reference to FIGS. FIG. 4 shows a specific configuration of the light beam control unit 104.

  The light beam control unit 104 generates a current for driving the laser diode 103a of the optical head 103. To this end, the light beam control unit 104 includes a current source 122 for causing the laser diode 103a to emit light with bias power, a current source 121 for causing the laser diode 103a to emit light with peak power, and switches 123, 124, and 125. including. The current source 121 and the current source 122 are connected in parallel to the laser diode 103a, and the switches 123, 124, and 125 are inserted in parallel between the current source 121 and the laser diode 103a.

  As shown in FIG. 3, at the time of recording, the digital signal processing unit 107 adds an error correction code to data to be recorded, performs a predetermined modulation process, and generates modulated data including a recording modulation code. The recording compensator 108 receives the modulated data and converts the modulated data into light modulated data. The light modulation data includes a recording mark corresponding to a recording modulation code included in the modulation data and a recording pulse train for generating a driving pulse current to be applied to a laser diode in order to form a recording space on the optical disc. At this time, the recording compensating unit 108 finely adjusts the width and timing of each pulse of the recording pulse train based on information obtained by reproducing the disk information area of the optical disk and information stored in the CPU 109 in advance. The recording pulse train is also adjusted so as to obtain an optimal pulse waveform according to the type and the recording speed.

  FIG. 5 schematically shows the light modulation data generated by the recording compensation unit 108. A recording pulse train 130 for forming one recording mark is arranged at the beginning of the recording pulse train 130, and a first pulse 131 for forming the start end of the recording mark and a last pulse of the recording pulse train 130 are arranged. And a multi-pulse train 133 arranged between the first pulse 131 and the last pulse 132 for forming the end portion of the recording mark and for forming an intermediate portion of the recording mark. In FIG. 5, the multi-pulse train 133 includes only one pulse, but the multi-pulse train 133 may include two or more pulses depending on the length of the recording mark. Further, depending on the length of the recording mark, the case where only the first pulse 131 and the last pulse 132 are not included and the multi-pulse train 133 is not included, or only the recording mark having the shortest length includes a pulse having a different length from these pulses There are cases.

  The recording compensator 108 generates signals 111, 112, and 113 including only the first pulse 131, the multi-pulse train 133, and the last pulse 132 of the recording pulse train 130, and outputs the signals to the switches 123, 124, and 125 of the light beam driving unit 104, respectively. I do. The first pulse 131, the multi-pulse train 133, and the last pulse 132 included in the signals 111, 112, and 113 are shifted at predetermined timings.

  The switches 123, 124, and 125 that have received the signals 111, 112, and 113 are ON while the respective signals are at a high level. Therefore, a recording pulse train (drive pulse train) having a waveform equal to that of the recording pulse train 130 and having peak power and bias power at high and low levels is generated. The laser diode 103a is driven by the driving pulse train, and the recording mark is formed on the optical disc by the irradiation of the laser diode.

  Hereinafter, a recording pulse train for forming a recording mark in the present embodiment will be described. In the following specific example, it is assumed that the recording data is modulated by, for example, the Run Length Limited (2, 10) modulation method, and the mark is recorded on the optical disk by the mark edge recording method. This modulation method uses marks and spaces from 3T to 11T, where T is the reference clock cycle.

FIG. 6 shows a recording pulse train according to the first example of the present embodiment, and shows recording pulse trains for forming recording marks of 3T to 11T in order from the top.
I have.

  As shown in FIG. 6, for example, a recording pulse train for forming a 6T recording mark includes a first pulse 201 arranged at the head, a last pulse 203 arranged at the tail, a first pulse 201 and a last pulse 203. And a multi-pulse train 202 disposed therebetween.

  A recording pulse train for forming a 7T recording mark is arranged at a certain first pulse 204 arranged at the head, a last pulse 206 arranged at the tail, and between the first pulse 204 and the last pulse 206. And a multi-pulse train 205.

In these recording pulse trains, each of the multi-pulse trains 202 and 205 is composed of one pulse. In the recording pulse trains of 8T and 9T, the multi-pulse trains 207 and 208 include two pulses. In the recording pulse train of 10T and 11T, the multi-pulse trains 209 and 210 include three pulses.
As described above, in the recording pulse train of the present embodiment, when n is an integer of 2 or more, the number of pulses included in the multi-pulse train is equal in the recording pulse train for forming the 2nT and (2n + 1) T recording marks. .

  Therefore, the number of pulses in the multi-pulse train increases by one each time the mark becomes longer by 2T. At this time, there are two generation timings of the multi-pulse, and even for two recording marks including a multi-pulse train having the same number of pulses, the first pulse of the multi-pulse train for the mark of the even reference period T is an odd number. Of the multi-pulse train for the mark of the reference period T of the reference period T by 0.5T. That is, the interval between the first pulse and the leading pulse of the multi-pulse train is shorter by 0.5T in the even T mark. The interval between the last pulse and the last pulse of the multi-pulse train is shorter by 0.5T in the even-numbered T mark.

  As shown in FIG. 6, in a recording pulse train for forming a recording mark of 3T to 11T, the pulse width of each pulse of the first pulse, the last pulse, and the multi-pulse train is substantially equal and coincides with the reference period T. The pulse interval of the multi-pulse train also matches the reference period T. That is, the pulse period in the multi-pulse train is 2T, which is twice the reference period T.

  Further, as shown in FIG. 6, in the first example, the recording pulse train forming the 4T and 5T marks is composed of only the first pulse and the last pulse, and does not include the multi-pulse train. A recording pulse train forming a 3T mark is composed of one pulse. Therefore, considering the first pulse and the last pulse together, in the recording pulse of the first example, when n is an integer of 2 or more, a recording pulse train for forming recording marks of 2nT and (2n + 1) T is formed. The number of included pulses is equal.

  When a recording mark is formed using such a recording pulse train, the pulse width of the pulse forming the multi-pulse train is substantially equal to the reference period T, which is about twice the pulse width of the pulse forming the conventional multi-pulse train. I have. The influence of the rise and fall times of the laser in one pulse can be relatively reduced, and the recording mark is less likely to be deformed. Further, since the width of the first pulse and the width of the last pulse are equal in each mark, it becomes easy to record the edge position of each mark correctly. In particular, when data is recorded on an optical disk at a high transfer speed, the edge positions of the marks vary and the jitter of the reproduced signal increases, and the recording pulse train of the first example is effective.

  FIG. 7 shows a recording pulse train according to a second example of the present embodiment. As in the first example shown in FIG. 6, in the recording pulse train for forming a recording mark of 3T to 11T, the number of pulses constituting the multi-pulse train is equal in the 2nT and (2n + 1) T marks. Also, the number of pulses in the multi-pulse train increases by one each time the mark becomes longer by 2T.

  A recording pulse train for forming a recording mark of 6T to 11T includes a first pulse, a multi-pulse train, and a last pulse. For example, a recording pulse train for forming a 6T recording mark includes a certain first pulse 301 arranged at the head, a last pulse 303 arranged at the tail, and a space between the first pulse 301 and the last pulse 303. And a multi-pulse train 302. A recording pulse train for forming a 7T recording mark includes a first pulse 304 arranged at the head, a last pulse 306 arranged at the tail, and a multi-pulse train arranged between the first pulse 304 and the last pulse 306. 305. The 3T recording pulse train includes only the first pulse, and the 4T and 5T recording pulse trains include only the first pulse and the last pulse.

  As shown in FIG. 7, in the recording pulse forming each recording mark, the intervals between adjacent pulses in the first pulse, the last pulse, and each pulse of the multi-pulse train are almost equal. The widths of the first pulse and the last pulse in the recording pulse train of the even number T are different from other pulses. For example, about 1.5T. The width of the first pulse and the last pulse in the odd T recording pulse train and the width of the pulse forming the multi-pulse train in all the recording marks are about 1T.

  According to the recording pulse train according to the second example, the interval between two adjacent pulses is almost equal in any of the recording pulse trains. For this reason, the recording marks formed using the recording pulse train according to the second example all have widths substantially equal in the radial direction of the optical disk. For this reason, by appropriately selecting the peak power of the laser diode, it is possible to reduce crosstalk which is a spillover of a reproduction signal from an adjacent track and jitter due to cross erase which is an influence of recording on an adjacent track. .

  FIG. 8 shows a recording pulse train according to a third example of the present embodiment. As in the first example shown in FIG. 6, in the recording pulse train for forming a recording mark of 3T to 11T, the number of pulses constituting the multi-pulse train is equal in the 2nT and (2n + 1) T marks. Also, the number of pulses in the multi-pulse train increases by one each time the mark becomes longer by 2T.

  A recording pulse train for forming a recording mark of 6T to 11T includes a first pulse, a multi-pulse train, and a last pulse. For example, a recording pulse train for forming a 6T recording mark is arranged at a certain first pulse 401 arranged at the head, a last pulse 403 arranged at the tail, and between the first pulse 401 and the last pulse 403. And a multi-pulse train 402. A recording pulse train for forming a 7T recording mark includes a certain first pulse 404 arranged at the head, a last pulse 406 arranged at the tail, and a multi-pulse train arranged between the first pulse 404 and the last pulse 406. 405. The 3T recording pulse train includes only the first pulse, and the 4T and 5T recording pulse trains include only the first pulse and the last pulse.

  In the recording pulse train according to the third example, the width of the leading pulse of the multi-pulse train in the recording pulse train of the odd T mark is different from the widths of the other pulses. For example, about 1.5T. The widths of the pulses other than the first pulse, the last pulse, and the first pulse of the multi-pulse train are approximately equal in all marks, and the width is about 1T. The width between adjacent pulses is such that, at an odd T mark, the interval between the last pulse of the multi-pulse train and the last pulse is longer than the interval between any other adjacent pulses. The interval between the last pulse and the last pulse is about 1.5T, while the interval between any other adjacent pulses is about 1T.

  When the laser power behind the odd T mark is insufficient, the width of the last pulse is made longer than other pulses instead of the first pulse of the multi-pulse train, and the first pulse and the multi-pulse train May be longer than other intervals.

  The recording pulse train according to the third example has the characteristics of the recording pulse train of the first example and the recording pulse train of the second example, and includes variations in edge positions of recording marks, crosstalk of a reproduction signal, and crosstalk during recording. If the recording mark is formed using the recording pulse train according to the third example when the effect of the erasure is large, these effects can be reduced.

  FIG. 9 shows a recording pulse train according to a fourth example of the present embodiment. As in the previous examples, for example, a recording pulse train for forming a 7T recording mark includes a certain first pulse 501 arranged at the head, a last pulse 503 arranged at the tail, a first pulse 501 and a last pulse. 503, and a multi-pulse train 502 disposed between the two. A recording pulse train for forming an 8T recording mark includes a certain first pulse 504 arranged at the head, a last pulse 506 arranged at the tail, and a multi-pulse train arranged between the first pulse 504 and the last pulse 506. 505.

  In these recording pulse trains, each of the multi-pulse trains 502 and 505 is composed of one pulse. In the recording pulse trains of 9T and 10T, the multi-pulse trains 507 and 508 include two pulses. In the 11T recording pulse train, the multi-pulse train 509 includes three pulses.

  As described above, in the recording pulse train according to the fourth example, when n is an integer of 4 or more, in the recording pulse train for forming the recording marks of (2n-1) T and 2nT, the pulses included in the multi-pulse train Are equal.

  Therefore, the number of pulses in the multi-pulse train increases by one each time the mark becomes longer by 2T. At this time, there are two types of multi-pulse generation timings, and even for two recording marks including a multi-pulse train having the same number of pulses, the leading pulse of the multi-pulse train for the mark of the odd reference period T is an even-numbered pulse. Of the multi-pulse train for the mark of the reference period T of the reference period T by 0.5T. In other words, the interval between the first pulse and the first pulse of the multi-pulse train is shorter by 0.5T in the odd-numbered T mark. The interval between the last pulse of the multi-pulse train and the last pulse is shorter by 0.5T in the odd T mark.

  As shown in FIG. 9, in a recording pulse train for forming a recording mark of 3T to 11T, the pulse width of each pulse of the first pulse, the last pulse, and the multi-pulse train is substantially equal and coincides with the reference period T. The pulse interval of the multi-pulse train also matches the reference period T. That is, the pulse period in the multi-pulse train is 2T, which is twice the reference period T.

  In the fourth example, a recording pulse train forming marks of 5T and 6T is composed of only a first pulse and a last pulse, and does not include a multi-pulse train. A recording pulse train for forming 3T and 4T marks is composed of one pulse. However, a 4T recording pulse train uses a first pulse that is 0.5T longer than 3T. Therefore, considering the first pulse and the last pulse together, in the recording pulse of the fourth example, when n is an integer of 1 or more, recording for forming (2n-1) T and 2nT recording marks is performed. The number of pulses included in the pulse train is equal.

  When a recording mark is formed using such a recording pulse train, the pulse width of the pulse forming the multi-pulse train is substantially equal to the reference period T, which is about twice the pulse width of the pulse forming the conventional multi-pulse train. I have. The influence of the rise and fall times of the laser in one pulse can be relatively reduced, and the recording mark is less likely to be deformed. Further, since the width of the first pulse and the width of the last pulse are equal in each mark, it becomes easy to record the edge position of each mark correctly. The recording pulse train of the fourth example is particularly effective when the data is recorded on the optical disk at a high transfer speed, thereby causing variations in the mark edge positions and increasing the jitter of the reproduced signal.

  FIG. 10 shows a recording pulse train according to a fifth example of the present embodiment. As in the fourth example shown in FIG. 9, in the recording pulse train for forming a recording mark of 3T to 11T, the number of pulses constituting the multi-pulse train becomes equal in the (2n-1) T and 2nT marks. I have. Also, the number of pulses in the multi-pulse train increases by one each time the mark becomes longer by 2T.

  A recording pulse train for forming a recording mark of 7T to 11T includes a first pulse, a multi-pulse train, and a last pulse. For example, a recording pulse train for forming a 7T recording mark is arranged at a certain first pulse 601 arranged at the head, a last pulse 603 arranged at the tail, and between the first pulse 601 and the last pulse 603. And a multi-pulse train 602. A recording pulse train for forming a recording mark of 8T includes a certain first pulse 604 arranged at the head, a last pulse 606 arranged at the tail, and a multi-pulse train arranged between the first pulse 604 and the last pulse 606. 605. The 3T and 4T recording pulse trains include only the first pulse, and the 5T and 6T recording pulse trains are composed of only the first pulse and the last pulse.

  As shown in FIG. 10, in the recording pulse forming each recording mark, the intervals between adjacent pulses in the first pulse, the last pulse, and each pulse of the multi-pulse train are almost equal. The widths of the first pulse and the last pulse in the recording pulse train of the even number T are different from other pulses. For example, about 1.5T. The width of the first pulse and the last pulse in the odd T recording pulse train and the width of the pulse forming the multi-pulse train in all the recording marks are about 1T.

  According to the recording pulse train according to the fifth example, the interval between two adjacent pulses is almost equal in any of the recording pulse trains. Therefore, each of the recording marks formed by using the recording pulse train according to the fifth example has substantially the same width in the radial direction of the optical disc. For this reason, by appropriately selecting the peak power of the laser diode, it is possible to reduce crosstalk which is a spillover of a reproduction signal from an adjacent track and jitter due to cross erase which is an influence of recording on an adjacent track. .

  FIG. 11 shows a recording pulse train according to a sixth example of the present embodiment. As in the fourth example shown in FIG. 9, in the recording pulse train for forming a recording mark of 3T to 11T, the number of pulses constituting the multi-pulse train becomes equal in the (2n-1) T and 2nT marks. I have. Also, the number of pulses in the multi-pulse train increases by one each time the mark becomes longer by 2T.

  A recording pulse train for forming a recording mark of 7T to 11T includes a first pulse, a multi-pulse train, and a last pulse. For example, a recording pulse train for forming a 7T recording mark is arranged between a certain first pulse 701 arranged at the head, a last pulse 703 arranged at the tail, and a first pulse 701 and a last pulse 703. And a multi-pulse train 702.

  A recording pulse train for forming a 7T recording mark includes a certain first pulse 704 arranged at the head, a last pulse 706 arranged at the tail, and a multi-pulse train arranged between the first pulse 704 and the last pulse 706. 705. The recording pulse trains of 3T and 4T include only the first pulse, and the recording pulse trains of 7T and 6T include only the first pulse and the last pulse.

  In the recording pulse train according to the sixth example, the width of the leading pulse of the multi-pulse train in the recording pulse train of the even-numbered T mark is different from the widths of the other pulses. For example, about 1.5T. The widths of the pulses other than the first pulse, the last pulse, and the first pulse of the multi-pulse train are approximately equal in all marks, and the width is about 1T. The width between adjacent pulses is such that, in the odd T mark, the interval between the last pulse of the multi-pulse train and the last pulse is longer than the interval between any other adjacent pulses. The interval between the last pulse and the last pulse in the pulse train is about 1.5T, while the interval between any other adjacent pulses is about 1T.

  When the laser power behind the odd T mark is insufficient, the width of the last pulse is made longer than other pulses instead of the first pulse of the multi-pulse train, and the first pulse and the multi-pulse train May be longer than other intervals.

  The recording pulse train according to the sixth example has the features of the recording pulse train of the first example and the recording pulse train of the second example, and includes variations in edge positions of recording marks, crosstalk of a reproduction signal, and crosstalk during recording. If the recording mark is formed by using the recording pulse train according to the sixth example when the influence of the erasure is large, these effects can be reduced.

  As described above, according to the present embodiment, by setting the cycle of the pulse in the multi-pulse train to 2T longer than the reference cycle T of the recording modulation code, even when the recording speed is increased, the rise time and fall time of the laser are increased. Is less likely to be affected, and correct recording can be performed.

  In the example described above, recording is performed on the optical disc 101 with binary power of peak power and bias power, but the type of power is not limited to this, and three or more types of different powers are used. Recording may be performed.

  The recording pulse train according to the seventh example shown in FIG. 12 is different from FIG. 6 in that the amplitude of the first pulse and the last pulse of the odd number T excluding 3T, that is, the laser irradiation power corresponding to the high level is larger than the other pulses. Is different from the recording pulse train of the first example shown in FIG.

  As shown in FIG. 12, when n is an integer of 2 or more, the number of pulses in the 2nT recording pulse train is equal to the number of pulses in the (2n + 1) T recording pulse train. Since the (2n + 1) T recording mark needs to be formed to be longer than the 2nT recording mark by T, the amount of heat generated when forming the (2n + 1) T recording mark is smaller than when forming the 2nT recording mark. May be short. For this reason, the laser irradiation power of the first pulse and the last pulse is made larger than that of the other pulses. For example, the laser power of the first pulse and the last pulse is set to be larger than one time and 1.5 times or less of other pulses. In order to generate such a recording pulse train, for example, a power supply that outputs a current larger than the power supply 121 to the light beam control unit 104 and a pair of power supplies connected in parallel to each other and connected in series to the power supply, respectively. Switch is provided. When generating an even-numbered recording pulse train of 5T or more, the recording compensating unit 108 is adjusted so as to generate a control signal for turning on a newly provided power supply switch.

  By making the powers of the pulses constituting the marks 2T apart equal, the regularity can be used for generating the recording pulse train. Therefore, the configuration of the light beam controller 104 and the recording compensator 108 can be simplified as compared with the case where a recording pulse train is generated so that the power is individually corrected for each mark.

  By doing so, the laser irradiation power is increased between the first pulse and the first pulse of the multi-pulse train, and between the last pulse and the last pulse of the multi-pulse train, where the pulse interval is longer than that of the recording pulse train of 2 nT. It is possible to prevent the recording marks from being thinned due to shortage, and to form the recording marks with a correct mark width.

  Instead of increasing the laser irradiation power of the last pulse of the (2n + 1) T recording pulse train, the laser irradiation power of the last pulse of the multi-pulse train of the (2n + 1) T recording pulse train may be increased. Further, the laser irradiation power may be made different between the 3T recording pulse train and the 4T recording pulse train.

  Similarly, with respect to the recording pulse trains according to the second to sixth examples, the irradiation power of the predetermined pulse is corrected so that the recording pulse trains of 2nT and (2n + 1) T or the recording pulse trains of (2n-1) T and 2nT are obtained. Can be compensated for by making the number of pulses equal to each other.

  FIG. 13 shows a modified example of the recording pulse train according to the second example, in which the amplitude of the first pulse and the last pulse of the 2nT recording pulse train, that is, the laser irradiation power is made larger than the other pulses.

  FIG. 14 shows a modification of the recording pulse train according to the third example, in which the laser irradiation power of the first pulse of the multi-pulse of the (2n + 1) T recording pulse train is reduced and the laser irradiation power of the last pulse is increased. I have.

  FIG. 15 shows a modification of the recording pulse train according to the fourth example, in which the laser irradiation power of the first pulse of the 2nT recording pulse train and the last pulse of the first pulse of the multi-pulse is increased.

  FIG. 16 shows a modification of the recording pulse train according to the fifth example, in which the laser irradiation power of the first pulse and the last pulse of the 2 nT recording pulse train is increased.

  FIG. 17 shows a modification of the recording pulse train according to the sixth example, in which the irradiation power of the multi-pulse of the 2nT recording pulse train is increased.

  In this embodiment, a level for driving the laser diode with a power smaller than the bias power may be provided in the recording pulse train. For example, a rising position of the first pulse, a falling position of the last pulse, a fixed time after the last pulse, or a period in which the power is smaller than the bias power before and after the multi-pulse may be provided. According to the present embodiment, even when the recording speed is increased, the influence of the rise time and fall time of the laser is less likely to be exerted, so that the present invention is also effective when rising from a power smaller than the bias power to the peak power. In this case, the recording compensation unit 108 may finely adjust the end positions of these periods for each mark. Thereby, a mark can be recorded at a more correct position.

  In the example described with reference to FIGS. 12 to 17, the output of the peak power is changed at a predetermined position. However, it is possible to adjust the laser irradiation power even if other powers used for forming a mark such as a bias power are changed, whereby a mark having a more correct shape can be formed on the optical disc.

  In addition, the recording power is applied to the recording power by the recording compensating unit 108 and the light beam controlling unit 104, for example, for part or all of the first pulse, part or all of the multi-pulse, part or all of the last pulse, or for all marks. It may be adjusted commonly. Thereby, a mark can be recorded at a more correct position.

  The irradiation start position information, irradiation width information, irradiation end information, and irradiation power information of the first pulse, the last pulse, and the multi-pulse may be recorded on an optical disc. By recording such information on the optical disk, the optical disk device can support various types of optical disks, and the degree of freedom in designing the disk manufacturing can be increased.

  In addition, a recording method in which the number of pulses in the 2nT and (2n + 1) T recording pulse trains are equal as shown in FIG. 2, or a recording method in which the number of pulses in the (2n-1) T and 2nT recording pulse trains are equal as shown in FIG. A code identifying one of the methods may be recorded on the optical disc. This makes it possible to select a recording method in accordance with the characteristics of the optical disk, thereby increasing the degree of freedom in designing the disk manufacturing.

  Each recording mark such as 3T to 11T is composed of one pulse, only a first pulse, only a first pulse and a last pulse, a first pulse, a multi-pulse, a last pulse. May be recorded on an optical disc.

  When recording such information on an optical disc, for example, record the information in the innermost disc information area of the optical disc and read it at the time of startup immediately after inserting the optical disc into the optical disc device or immediately before recording data. Can be.

  With the pulse waveform configuration as in the present embodiment, the multi-pulse width and the interval between adjacent multi-pulses are about twice as large as in the conventional case where the number of multi-pulses increases by one every 1T, and the recording speed is increased. Even if the speed becomes faster, correct recording can be performed.

  In addition to a multi-pulse, a greater effect can be obtained by setting the pulse width of an arbitrary pulse including a first pulse and a last pulse and the pulse interval of an arbitrary adjacent pulse to about 1T.

  Furthermore, as in the present embodiment, a multi-pulse is generated with a simple configuration as in the case where a multi-pulse is generated every 1T by providing a regularity such that one multi-pulse is added every 2T. be able to.

  In the present embodiment, the phase change disk has been described. However, the present embodiment can be applied to a magneto-optical disk, and the same effects as in the present embodiment can be obtained.

(Second embodiment)
As described in the first embodiment, by equalizing the number of pulses in the multi-pulse train in the 2nT and (2n + 1) T recording pulse trains or the (2n-1) T and 2nT recording pulse trains, There is a possibility that the laser irradiation power of one recording pulse train is different. This is because the duty or average value of the mark / space in the multi-pulse train is different.

  FIGS. 18A and 18B are obtained from the recording mark formed by the recording pulse train 2 for forming the 9T mark and the recording mark formed by the recording pulse train 8 for forming the 10T mark in FIG. Are shown, respectively.

  As shown in FIG. 18A, in the recording pulse train 2, the first pulse 9 and the last pulse 10 have a pulse width of 1T, and give an appropriate mark forming thermal energy to the recording film of the optical disk. For this reason, the width of the formed recording mark 4 is substantially uniform, and the reproduction signal 6 also has a substantially trapezoidal shape in which the mark center is not concave. That is, the reproduced signal 6 is appropriate.

  On the other hand, in the recording pulse train 8, the first pulse 11 and the last pulse 12 have a width of 1.5T, so that the mark forming thermal energy at the start and end of the mark increases. For this reason, the width of the recording mark 13 to be formed becomes large at the beginning and end, and the mark 13 in the form of an array is formed. A reproduction signal 14 obtained from such an array of recording marks 13 has a distorted bimodal waveform in which the amplitudes of the rising and falling portions are increased and distorted. When such a bimodal reproduction signal 14 is converted into a digital signal by binarization or AD conversion, jitter occurs at rising and falling portions of the waveform, which causes a reproduction bit error.

  In the present embodiment, the pulse position and pulse width of the multi-pulse train are set with the target of the duty value or the average amplitude value of the multi-pulse train so that the appropriate mark forming thermal energy can be obtained in any recording pulse train.

  FIG. 19 shows a recording pulse train 16, a recording mark 15 formed by the recording pulse train 16, and a reproduction signal 17 obtained from the recording mark 15 in the present embodiment, in which the recording modulation code length is 10T. Will be described.

  The recording pulse train 16 includes a first pulse 18, a multi-pulse train 19, and a last pulse 20.

  The timing of the first pulse 18 is set by a first pulse rising timing TSFP and a first pulse falling timing TEFP. On the other hand, the timing of the last pulse 20 is set by the last pulse rising timing TSLP and the last pulse falling timing TELP. The arrangement of the multi-pulse train 19 is set by the rising timing TSMP of the multi-pulse train and the pulse width TMP.

  Next, the relationship between the change of the parameters constituting the recording pulse train 16 and the shape of the recording mark 15 and the waveform of the reproduction signal 17 will be described.

  The start position 21 of the recording mark 15 is determined by the first pulse rising timing TSFP. The start end position 21 of the recording mark 15 moves back and forth due to thermal interference from the immediately preceding recording mark, whereby the reproduction signal 17 changes as indicated by an arrow 22 in FIG.

  In order to control the start position 21 of the recording mark 15 to an appropriate position, the first pulse rising timing TSFP is adaptively set according to the length of the immediately preceding space and the length of the recording mark 15 itself. By doing so, the start end position 21 of the recording mark can be controlled to an appropriate position according to the recording modulation code, regardless of the combination of the immediately preceding space and the subsequent recording mark, and the starting end 22 of the reproduced signal waveform can be controlled. Can be reduced. On the other hand, the end position 23 of the recording mark 15 is determined at the last pulse falling timing TELP. The end position 23 of the recording mark 15 moves back and forth due to thermal interference from the immediately following recording mark, whereby the reproduction signal 17 changes as shown by an arrow 24 in FIG.

  In order to control the end position 23 of the recording mark 15 to an appropriate position, the last pulse fall timing TSLP is adaptively set according to the length of the immediately preceding space and the length of the recording mark 15 itself. By doing so, the end position 23 of the recording mark can be controlled to an appropriate position according to the recording modulation code regardless of the combination of the recording mark and the space immediately behind the recording mark, and the end position 24 of the reproduction signal waveform can be controlled. Jitter components can be reduced.

  The start end width 25 of the recording mark 15 is determined at the first pulse falling timing TEFP. Since the first pulse fall timing TEFP determines the width of the first pulse 18 and can control the heat energy applied to the start end of the recording mark, the start end width 25 of the recording mark can be controlled to an appropriate width. The start width 25 of the recording mark, like the start position 21 of the recording mark, is less affected by thermal interference from the immediately preceding recording mark and the code length of the recording mark 15 itself. For this reason, the first pulse falling timing TEFP is generally set to a constant value regardless of the immediately preceding space code length and the code length of the recording mark 15 itself.

  By setting the first pulse fall timing TEFP in this manner, the start width 25 of the recording mark can be controlled to an appropriate width, and the overshoot portion 26 at the start end of the reproduction signal 17 can be reduced. For this reason, in a reproduced signal obtained from a long recording modulation code, a jitter component due to an amplitude fluctuation at the start end is reduced.

  On the other hand, the end width 27 of the recording mark 15 is determined by the last pulse rising timing TSLP. Since the last pulse rising timing TSLP determines the width of the last pulse 20 and can control the heat energy applied to the end of the recording mark, the end 27 of the recording mark can be controlled to an appropriate width. The end width 27 of the recording mark, like the end position 23 of the recording mark, is less affected by thermal interference from the immediately following recording mark and the code length of the recording mark 15 itself. For this purpose, the last pulse rising timing TSLP is set to a constant value irrespective of the next space length and the code length of the recording mark 15 itself.

  By setting the last pulse rising timing TSLP in this manner, the end width 27 of the recording mark 15 can be controlled to an appropriate width, and the overshoot portion 28 at the end of the reproduction signal 17 can be reduced. For this reason, in a reproduced signal obtained from a long recording modulation code, a jitter component due to a fluctuation in the amplitude of the terminal portion is reduced.

  The width 29 near the center of the recording mark 15 is determined by the rising timing TSMP of the multi-pulse train and the multi-pulse train width TMP. As described in the first embodiment, the cycle of the multi-pulse train is set to 2T so that the laser diode can be reliably driven by the multi-pulse train even at a high transfer rate.

  When recording at a high transfer rate and high density, the irradiation time of the laser beam is shorter than at low transfer rates and low density. For this reason, it is necessary to more precisely set the width of the multi-pulse train in order to form an appropriate recording mark width. Further, when the cycle of the multi-pulse train is set to 2T, the width TMP of the multi-pulse train and the space 33 of the multi-pulse train become wider than in the case of the 1T cycle, so that the thermal energy distribution tends to be uneven. Therefore, appropriate setting of the multi-pulse train is important for forming a recording mark having an optimum width.

  In the vicinity of the center of the recording mark 15, a mark is formed by the total heat energy of the multi-pulse train 19. Therefore, the configuration of the multi-pulse train 19 is determined by the rising timing TSMP of the multi-pulse train 19 and the pulse width TMP of the pulses constituting the multi-pulse train 19, and the thermal energy applied to the vicinity of the center of the main body of the recording mark is controlled. be able to. Therefore, the width 29 near the center of the recording mark 15 can be adjusted to an appropriate width.

  By adjusting the width 29 near the center of the recording mark 15 to an appropriate width in this way, it is possible to reduce the fluctuation 30 in the amplitude of the reproduction signal 17 near the center. For this reason, the jitter component due to the amplitude fluctuation in the reproduction signal 17 obtained from the long recording modulation code is reduced.

  As described above, the vicinity of the center of the recording mark 17 is formed by the total heat energy of the multi-pulse train 19. At this time, the area including the multi-pulse train 19 can be defined by two different definitions, and different definitions are used according to the sensitivity of the recording material of the optical disc and the mark recording speed.

  In an optical disk having a recording material having a relatively low mark recording speed and a low recording sensitivity, from the rising timing of the first multipulse 19A arranged first in the multipulse train 19, to the last multi-pulse arranged last in the multipulse train. The range up to the falling timing of the pulse 19C mainly affects and affects the formation of the recording mark 15 near the center of the main body of the recording mark 15. This is called a first multi-pulse region 31.

  On the other hand, in an optical disk having a recording material with a relatively high mark recording speed and high recording sensitivity, the range from the first pulse falling timing TEFP to the last pulse rising timing TSLP constituting the recording pulse train is mainly at the center of the recording mark 15. It affects and affects the formation of nearby marks. This is called a second multi-pulse region 32.

  There are also two types of indices indicating the thermal energy involved in forming the vicinity of the center of the recording mark 15 due to the mark forming process of the recording material of the optical disc.

  In order to form the vicinity of the center of the recording mark 15, a constant cooling time for the light irradiation part in the multi-pulse area, that is, in the case of an optical disc having a recording material in which the space 33 of the multi-pulse train 19 is important, the multi-pulse duty is set to the heat energy. Index. The multi-pulse duty is a value obtained by dividing the multi-pulse width TMP by the period of the multi-pulse train (2T in FIG. 19) in the multi-pulse region.

  On the other hand, in the case of an optical disc having a recording material in which the average light irradiation energy in the multi-pulse area is important (or has a strong correlation) in order to form the vicinity of the center of the recording mark 15, the multi-pulse amplitude average value is calculated as the thermal energy. Make it an indicator. The multi-pulse amplitude average value is a value obtained by dividing the amplitude integral value of the multi-pulse area by the time width of the multi-pulse area.

  As described above, the rising timing TSMP of the multi-pulse train 19 and the multi-pulse train width TMP are adjusted using the multi-pulse duty and the average of the multi-pulse amplitudes as evaluation indexes, and the width 29 near the center of the recording mark 15 is adjusted appropriately. To keep.

  In order to ensure that the width 25 at the start end of the recording mark, the width 29 near the center of the recording mark, and the width 27 at the end of the recording mark are evenly balanced and flat, the following will be described. It is better to perform the setting operation at such a timing.

  That is, the leading space width FSP sandwiched between the first pulse 18A and the leading pulse 19A of the multipulse 19 is equal to the trailing space width LSP sandwiched between the last pulse 19C of the multipulse 19 and the last pulse 20. Set as follows. By performing the setting operation of FSP = LSP in this manner, the energy given by the multi-pulse 19 is applied to the vicinity of the center of the recording mark in a well-balanced manner without being biased toward the beginning or end of the recording mark. Therefore, the widths 25, 29, and 27 of the recording marks are approximately equal, and it is possible to form a recording mark having a uniform width in the length direction.

  As described above, the rising timing TSMP of the multi-pulse train, the width TMP of the multi-pulse train, the head space, and the multi-pulse duty and the multi-pulse amplitude average value are used as indices so that these parameters become predetermined targets. By setting the width FSP and the width LSP of the tail space, a recording mark having an appropriate width can be formed even when recording is performed at a high transfer rate and at a high density. Therefore, it is possible to reduce the decrease 30 in the waveform amplitude near the center of the reproduced signal, and to reduce the jitter component due to the amplitude fluctuation of the reproduced signal waveform in a long recording modulation code.

Next, a specific calculation method of each timing of the recording pulse train 16 in the present embodiment will be described with reference to FIG.
In FIG. 20, a reference clock, a recording modulation code, a recording pulse train for even nT, and a recording pulse train for odd nT are shown in order from the top. In each of these, the horizontal direction is the time axis.

  The recording modulation code 35 has a recording modulation code length that is n times (n is a natural number of 1 or more) a reference clock period T34 that is a reference unit length. When n is an even number, the pulse falls at a position indicated by an even number nT36, and when n is an odd number, the pulse falls at a position indicated by an odd number nT37. When the recording modulation code 35 is modulated by the RLL (2, 10) modulation method as in the first embodiment, the code length is 3T to 11T.

  The recording pulse train 16 is composed of the first pulse 18, the multi-pulse train 19, and the last pulse 20, as described above.

  The timing of the first pulse 18 is determined by the rising timing TSFP of the first pulse 18 and the falling timing TEFP of the first pulse 18. Although the value of TSFP does not affect the calculation result of the multi-pulse train and is not shown for simplicity of description, TSFP = 0 hereafter. As described with reference to FIG. 19, the TSFP is adaptively set according to the immediately preceding space code length and the code length of the recording mark itself. As described above, the TEFP is generally set to a constant value regardless of the immediately preceding space code length and the code length of the recording mark itself.

  On the other hand, the timing of the last pulse 20 is determined by the rising timing TSLP of the last pulse 20 and the falling timing TELP of the last pulse 20. As described above, the TSLP is set to a constant value irrespective of the immediately succeeding space code length and the code length of the recording mark itself. Although not shown, TSLP was set to TSLP = 0, which is a value that reduces the overshoot at the end of the reproduced waveform. Further, as described with reference to FIG. 19, TELP is adaptively set according to the next space code length and the code length of the recording mark itself.

  Next, a timing calculation method of the rising timing TSMP of the multi-pulse train 19 in the multi-pulse region, the width TMP of the multi-pulse train, the width FSP of the head space, and the width LSP of the tail space will be described.

  A first example will be described. In the first example, the range that affects the width near the center of the recording mark is the first multi-pulse region 31, and the index for controlling the timing of the multi-pulse train is the multi-pulse duty.

  First, calculation is performed for 38 where the recording modulation code length is an even number nT. In even nT, the rising timing TSMP of the multi-pulse train 19 is calculated based on the even reference timing TRE delayed by 2T from the rising timing of the recording modulation code 35.

  From FIG. 20, the width FSP of the head space and the width LSP of the tail space are obtained by the following calculation (40).

FSP = 2T-TEFP + TSMP
LSP = 2T-TMP-TSMP (40)

  Further, assuming that FSP = LSP as described above in order to maintain the balance at the start end and the end of the recording mark width, the multipulse train rising timing TSMP is obtained by the following operation (41) from the operation (40).

  TSMP = (TEFP−TMP) / 2 (41)

  Next, calculation is performed for 39 when the recording modulation code length is an odd number nT.

  The TSMP in the case of the odd nT is calculated based on the odd reference timing TRO delayed by 3T from the rising timing of the recording modulation code 35.

  The width FSP of the head space and the width LSP of the tail space can be obtained by the following calculation (42) from FIG.

FSP = 3T-TEFP + TSMP
LSP = 2T-TSMP-TMP (42)

  Assuming that FSP = LSP as described above in order to maintain the balance at the beginning and end of the recording mark width, the multipulse train rising timing TSMP is obtained by the following calculation (43) from the calculation (42).

  TSMP = (TEFP-TMP-1T) / 2 (43)

  On the other hand, the multi-pulse duty MPD, which is the control target, is a value obtained by dividing the width TMP of the multi-pulse train 19 by the period of the multi-pulse train 19 (2T in FIG. 20) in the first multi-pulse region 31. Is determined by

MPD = TMP / 2T
Therefore, TMP = 2T · MPD (44)

  Here, the fall timing TEFP of the first pulse 18 is set to a constant value regardless of the preceding space code length and the code length of the recording mark itself as described above. In this example, the following values are set so that the overshoot at the beginning of the waveform of the reproduced signal is small.

  TEFP = 1.5T

  Also, as the multi-pulse duty MPD necessary for appropriately maintaining the width 29 near the center of the recording mark, a value that causes a small decrease in the waveform amplitude near the center of the reproduced signal is selected. From the result of observing the waveform of the reproduced signal, in this example, the following values of MPD are appropriate values.

  MPD = 0.5

  The values of TEFP and MPD described above are substituted into the arithmetic expressions (40) to (44) to determine the timing values of FSP, LSP, TSMP, and TMP at each recording modulation code length. FIG. 21 shows the recording pulse train thus obtained in this example.

  As shown in FIG. 21, the multi-pulse duty MPD in the first multi-pulse area 31 has the same value as 0.5 for each recording modulation code length. Also, the width FSP of the head space and the width FSP of the tail space are equal within the same recording modulation code.

  As described above, in the present embodiment, the irradiation heat energy and the cooling time near the center of the recording mark are uniform at any recording modulation code length, and the balance of the thermal energy at the beginning and end is not broken between the recording modulation codes. Therefore, no matter what length the recording modulation code is used, a recording mark having a uniform width can be formed stably from the beginning to the end.

  In the case of an optical disc having a relatively slow mark recording speed, a recording material having low sensitivity, and requiring a certain cooling time in a light irradiation part in a multi-pulse area, data should be recorded using a recording pulse train shown in FIG. Thus, the width of the formed recording mark can be controlled uniformly from the start to the end. For this reason, it is possible to perform recording with a small decrease in the waveform amplitude near the center of the reproduced signal without causing the reproduced signal to have a bimodal waveform as shown in FIG.

  Next, a second example according to the present embodiment will be described. In the second example, the range that affects the mark width near the center of the recording mark is the first multi-pulse area 31, and the index for controlling the timing of the multi-pulse train is a multi-pulse amplitude average value. As shown in FIG. 20, in the even nT, the rising timing TSMP of the multi-pulse train 19 is calculated based on the even reference timing TRE delayed by 2T from the rising timing of the recording modulation code 35, and the TSMP in the odd nT is recorded. The calculation is performed based on the odd reference timing TRO delayed by 3T from the rising timing of the modulation code 35.

  The width FSP of the head space and the width LSP of the tail space are obtained by the following calculation (45) from FIG.

FSP = 2T-TEFP + TSMP (for even nT)
FSP = 3T-TEFP + TSMP (for odd nT)
LSP = 2T-TMP-TSMP (45)

  Assuming that FSP = LSP as described above in order to keep the width of the recording mark uniform, the rising timing TSMP of the multi-pulse train 19 is obtained by the following calculation (46) from the calculation (45).

TSMP = (TEFP−TMP) / 2 (for even nT)
TSMP = (TEFP-TMP-1T) / 2 (for odd nT)
... (46)

  On the other hand, the multi-pulse amplitude average value MPM, which is the control target, is a value obtained by dividing the amplitude integrated value of the first multi-pulse area 31 by the time width of the first multi-pulse area. Is determined by Here, INT (X) is a function for calculating the integer part of the value of X.

MPM = TMP · INT {(nT-4T) / 2} /
(NT-2T-TEFP-FSP-LSP) (47)

  When the equation (46) is substituted into the equation (47) and the multi-pulse width TMP is further obtained, the following equation (48) is obtained.

TMP = MPM · (nT-6) / [INT {(nT-4) / 2)}-MPM
(For even nT)
TMP = MPM ・ (nT-7) / [INT {(nT-4) / 2)}-MPM]
(In case of odd nT)
... (48)

  In this example, the fall timing TEFP of the first pulse 18 is set to a constant value regardless of the preceding space code length and the code length of the recording mark itself as described above. In this example, the following values are set so that the waveform overshoot is small at the beginning of the reproduced signal.

  TEFP = 1.5T

  Also, as the multi-pulse amplitude average value MPM necessary for appropriately maintaining the width 29 near the center of the recording mark, a value that causes a small decrease in the waveform amplitude near the center of the reproduced signal is selected. As a result of observing the waveform of the reproduced signal, MPM = 0.5 was an appropriate value in this example.

  The values of TEFP and MPD described above are substituted into the arithmetic expressions (45) to (48), and the timing values of FSP, LSP, TSMP, and TMP for each recording modulation code are obtained. FIG. 22 shows the waveform of the recording pulse train thus obtained in this example.

  As shown in FIG. 22, the average multi-pulse amplitude value MPM in the first multi-pulse area 31 is the same value as 0.5 regardless of the recording modulation code. Also, the width FSP of the head space and the width FSP of the tail space are equal within the same recording modulation code.

  As described above, in this example, the average irradiation energy in the vicinity of the center of the recording mark is uniform for any of the recording modulation codes, and the thermal energy balance between the start and end and the vicinity of the mark center does not break between the recording modulation codes. . Therefore, a recording mark having a uniform width from the start end to the end can be formed stably by each recording modulation code.

  In an optical disk having a relatively slow mark recording speed, a low-sensitivity recording material, and where the average light irradiation energy in the multi-pulse area is important for forming a recording mark, the recording pulse train shown in FIG. A recording mark having a uniform width can be formed. For this reason, it is possible to perform recording with a small decrease in the waveform amplitude near the center of the reproduced signal without causing the reproduced signal to have a bimodal waveform as shown in FIG.

  Next, a third example will be described. In the third example, the range that affects the mark width near the center of the recording mark is the second multi-pulse region 32, and the index for controlling the timing of the multi-pulse train is a multi-pulse amplitude average value.

  As shown in FIG. 20, the width FSP of the head space and the width LSP of the tail space are obtained by the following calculation (49) from FIG. 20, as in the second example.

FSP = 2T-TEFP + TSMP (for even nT)
FSP = 3T-TEFP + TSMP (for odd nT)
LSP = 2T-TMP-TSMP (49)

  Assuming that FSP = LSP as described above in order to keep the width of the recording mark width equal, the multi-pulse train rising timing TSMP is obtained by the following calculation (50) from the calculation (49).

TSMP = (TEFP−TMP) / 2 (for even nT)
TSMP = (TEFP-TMP-1T) / 2 (in case of odd nT) (50)

  On the other hand, the multi-pulse amplitude average value MPM, which is the control target, is a value obtained by dividing the amplitude integrated value of the second multi-pulse area 32 by the time width of the second multi-pulse area 32, and therefore, the following calculation (51) in FIG. ). Here, INT (X) is a function for calculating the integer part of the value of X.

MPM = TMP · INT {(nT-4T) / 2} /
(NT-2T-TEFP) (51)

  When the multi-pulse width TMP is obtained from the equation (51), the following equation (52) is obtained.

TMP = MPM · (nT-2T-TEFP) /
INT {(nT-4) / 2)} ... (52)

  In this example, the fall timing TEFP of the first pulse 18 is set to a constant value regardless of the preceding space code length and the code length of the recording mark itself as described above. In this example, the following values are set so that the overshoot of the waveform at the beginning of the reproduced signal is small.

  TEFP = 1.5T

  Also, in order to keep the width 29 near the center of the recording mark properly, the required multi-pulse amplitude average value MPM is selected so that the waveform amplitude near the center of the reproduced signal decreases little. As a result of observing the waveform of the reproduced signal, in this example, MPM = 0.5 is an appropriate value.

  The values of TEFP and MPD described above are substituted into the arithmetic expressions (49) to (52) to determine the timing values of FSP, LSP, TSMP, and TMP for each recording modulation code. FIG. 23 shows the waveform of the recording pulse train thus obtained in this example.

  As shown in FIG. 23, the average multi-pulse amplitude value MPM in the second multi-pulse area 32 is the same value as 0.5 regardless of each recording modulation code. Also, the width FSP of the head space and the width FSP of the tail space are equal within the same recording modulation code.

  As described above, in this example, the average irradiation energy near the center of the recording mark is uniform for any recording modulation code, and the thermal energy balance between the start and end and the vicinity of the mark center is not broken between the recording modulation codes. Therefore, a recording mark having a uniform width from the start end to the end can be formed stably.

  In an optical disc having a relatively fast mark recording speed, a recording material having high sensitivity, and the average light irradiation energy in the multi-pulse area being important for forming a recording mark, the recording pulse train shown in FIG. A recording mark having a uniform width can be formed. For this reason, it is possible to perform recording with a small decrease in the waveform amplitude near the center of the reproduced signal without causing the reproduced signal to have a bimodal waveform as shown in FIG.

  As described above, in the present embodiment, each timing value (FSP, LSP, TSMP, TMP) of the recording pulse train to be controlled is calculated and set for each recording modulation code. However, in order to shorten the setting time of the recording apparatus, or to reduce the circuit scale of the recording apparatus, or to simplify the circuit, these timing values are set for even nT and odd nT of the recording modulation code length. It is also possible to use two types. For example, in the recording pulse train shown in FIG. 21, an operation is performed for each recording modulation code, and the respective timing values are obtained. The operation results are of two types: an even number nT and an odd number nT. That is, each timing value is as follows.

For even nT:
FSP = LSP = 0.75T
TMP = 1.0T
TSMP = 0.25T
For odd nT:
FSP = LSP = 1.25T
TMP = 1.0T
TSMP = -0.25T

  For the same reason, each recording modulation code is divided into code length groups classified by the code length, and in the code length group, each timing value (FSP, LSP, TSMP, TMP) of the recording pulse is set to the same value. May be set.

  Alternatively, all the timing values (FSP, LSP, TSMP, TMP) of the recording pulse may be set to the same value irrespective of the recording modulation code length for reasons such as reducing the circuit scale.

  On the other hand, in the first to third examples of the present embodiment, one target value of the multi-pulse duty or the multi-pulse amplitude average value is determined from the result of observing the waveform of the reproduction signal, and all the recordings are performed using the target value. Each timing value of the pulse train was determined. However, in order to control the width of the recording mark more precisely, the recording modulation code is divided into a specific code group, and a target value of a multi-pulse duty or a multi-pulse amplitude average value is set for each code group. Each timing value may be determined using a different target value. In order to control the width of the recording mark more precisely, the target value of the index is set by dividing the recording modulation code into two types, an even number nT and an odd number nT, and the target value is individually set for each recording modulation code length. A value may be set.

  Next, with reference to FIG. 24, a description will be given of a method of evaluating a reproduced signal for determining whether the multi-pulse duty and the multi-pulse amplitude average value, which are indicators of the timing values of the recording pulse train, are appropriate.

  If the multi-pulse duty or the average value of the multi-pulse amplitude is not an appropriate value, the energy for irradiating the vicinity of the center of the recording mark is insufficient, and the medium-thin mark 5 in which the width of the mark center is narrow is formed. When the medium thin mark 5 is reproduced, the reproduced signal 7 has a distorted bimodal waveform in which the waveform amplitude value near the center decreases.

  The binarized slice level 57 for converting the reproduction signal 7 into digital data is set to about 1/2 of the maximum amplitude of the waveform of the normal reproduction signal 7. Therefore, if the slice level is appropriate, a binary digital signal 59 can be obtained.

  Here, when the slice level is increased and the binarized slice level 58 is set, the portion where the amplitude near the center of the reproduced signal 7 is reduced is cut out by the binarized slice level 58, and the two pulses are pulsed. A binarized digital signal 60 is generated. Since the low level 61 occurs in the binarized digital signal 60 in the middle, it is not reproduced to a correct recording modulation code.

  Therefore, first, the multi-pulse duty and the multi-pulse amplitude average value in the multi-pulse region are set, and each timing value of the recording pulse train is determined by the above-described method using the set values. A recording mark is formed on the optical disk by using the determined recording pulse train. Next, the reproduction signal obtained from the formed recording mark is binarized using a binarization slice level higher than a normal slice level. A low level is included in the obtained binary signal, and it is determined whether or not two pulses are generated.

  When the binarized signal includes two pulses, it is considered that the width of the central portion of the recording mark is narrow. That is, it is understood that the target value set as the multi-pulse duty or the multi-pulse amplitude average value is not appropriate.

  As described above, according to the present embodiment, the period of the multi-pulse train is set to 1T or more, and the rising timing TSMP of the multi-pulse train in the multi-pulse region is set so that the multi-pulse duty and the multi-pulse amplitude average value become the predetermined target values. , The width TMP of the multi-pulse train, the width FSP of the head space, and the LSP of the tail space width. As a result, a recording pulse train capable of forming a recording mark having an appropriate width can be obtained even when recording is performed at a high transfer rate and at a high density. In the waveform of the reproduced signal obtained from the recording mark thus formed, the decrease in the amplitude near the center is suppressed, and the distortion at the rising and falling portions of the signal is small. Therefore, even when a long recording modulation code is recorded, the influence of jitter can be reduced, and a reproduction bit error can be suppressed.

  Further, according to the present invention, it is possible to detect that the width near the center of the recording mark has become narrow by detecting that the amplitude near the center has decreased in the waveform of the reproduced raw signal. For this reason, it is possible to determine whether the multi-pulse duty or the multi-pulse amplitude average value in the multi-pulse region is an appropriate control target.

  According to the present invention, even when data is recorded at a high transfer rate, a recording mark having a correct shape can be formed on a data recording medium such as an optical disk. Therefore, the recording method of the present invention can be suitably used for an optical disk that performs recording at a high density and a high transfer rate, and an optical disk device corresponding to such an optical disk.

FIG. 11 is a diagram illustrating an example of a conventional recording pulse train. FIG. 11 is a diagram showing another example of a conventional recording pulse train. FIG. 1 is a block diagram illustrating a first embodiment of a recording apparatus according to the present invention. FIG. 4 is a diagram illustrating a configuration of a light beam control unit of the recording apparatus illustrated in FIG. 3. It is a figure which shows the signal input into a light beam control part, and the signal output from a light beam control part. FIG. 3 is a diagram illustrating a first example of a recording pulse train according to the first embodiment. FIG. 5 is a diagram illustrating a second example of the recording pulse train according to the first embodiment. FIG. FIG. 6 is a diagram illustrating a third example of the recording pulse train according to the first embodiment. FIG. 9 is a diagram illustrating a fourth example of the recording pulse train according to the first embodiment. FIG. 11 is a diagram illustrating a fifth example of the recording pulse train according to the first embodiment. FIG. 11 is a diagram illustrating a sixth example of the recording pulse train according to the first embodiment. FIG. 5 is a diagram illustrating a modification of the first example of the recording pulse train according to the first embodiment. FIG. 9 is a diagram illustrating a modification of the second example of the recording pulse train according to the first embodiment. FIG. 9 is a diagram illustrating a modification of the third example of the recording pulse train according to the first embodiment. FIG. 14 is a diagram illustrating a modification of the fourth example of the recording pulse train according to the first embodiment. FIG. 14 is a diagram illustrating a modification of the fifth example of the recording pulse train according to the first embodiment. FIG. 14 is a diagram illustrating a modification of the sixth example of the recording pulse train according to the first embodiment. (A) and (b) respectively show a conventional recording pulse train, a recording mark formed by the recording pulse train, and a waveform of a reproduction signal obtained by reproducing the recording mark. Each shows a recording pulse train according to the second embodiment, a recording mark formed by the recording pulse train, and a waveform of a reproduction signal obtained by reproducing the recording mark. FIG. 11 is a diagram illustrating parameters for determining a recording pulse train according to the second embodiment. FIG. 11 is a diagram illustrating a first example of a recording pulse train according to the second embodiment. FIG. 11 is a diagram illustrating a second example of the recording pulse train according to the second embodiment. FIG. 11 is a diagram illustrating a third example of the recording pulse train according to the second embodiment. FIG. 13 is a diagram illustrating an evaluation method for determining whether a target value for determining a parameter is appropriate in the second embodiment.

Explanation of reference numerals

16 Recording pulse train 18, 201, 301 First pulse 19, 202, 302 Multi pulse 20, 203, 303 Last pulse 34 Reference clock length 100 Data recording device 101 Optical disk 102 Spindle motor 103 Optical head 104 Light beam controller 105 Servo unit 106 Reproduction Binarization unit 107 Digital signal processing unit 108 Recording compensation unit 109 CPU
110 Host PC
TEFP First pulse fall timing TSLP Last pulse rise timing TMP Multi-pulse width TSMP Multi-pulse train rise timing FSP Leading space width LSP Trailing space width

Claims (30)

A plurality of recording modulation codes are generated by modulating data to be recorded, and a plurality of recording marks and spaces each having a length corresponding to each of the plurality of recording modulation codes are generated by irradiating an optical disk with a pulsed light beam. Forming on the optical disc, an optical data recording method,
At least two of the plurality of recording marks are
A first pulse arranged at the beginning and for forming a start end of the recording mark;
A last pulse arranged at the rear end to form a terminal end portion of the recording mark;
A multi-pulse train arranged between the first pulse and the last pulse to form a central portion of the recording mark;
Formed by a light beam emitted based on a recording pulse train including
An optical data recording method, wherein when a reference period of the recording modulation code is T, a pulse period of the multi-pulse train is longer than T.   The plurality of recording marks each have a different length represented by nT (n is an integer of 1 or more), and the number of pulses included in the recording pulse train is equal in at least two different recording marks. Item 2. The optical data recording method according to Item 1.   3. The optical data recording method according to claim 2, wherein the irradiation power of a light beam generated by at least one of the first pulse, the multi-pulse train, and the last pulse is different in the at least two recording marks.   3. The optical data recording method according to claim 2, wherein in the plurality of recording marks, the number of pulses included in the recording pulse train of the 2nT and (2n + 1) T recording marks is equal.   3. The optical data recording method according to claim 2, wherein in the plurality of recording marks, the number of pulses included in the recording pulse trains of the (2n-1) T and 2nT recording marks is equal.   2. The optical data recording method according to claim 1, wherein the pulse widths of the first pulses are all equal in the plurality of recording marks.   2. The optical data recording method according to claim 1, wherein the pulse widths of the last pulses are all equal in the plurality of recording marks.   2. The optical data recording method according to claim 1, wherein, in the plurality of recording marks, a pulse width and a pulse interval of the multi-pulse train are all equal. The plurality of recording marks include a recording mark formed by a light beam irradiated based on a recording pulse train including only one pulse, and a light irradiated based on a recording pulse train including only the first pulse and the last pulse. Including recording marks formed by the beam,
2. The optical data recording method according to claim 1, wherein the pulse width of any one of the recording pulse trains is 1T or more. The plurality of recording marks include a recording mark formed by a light beam irradiated based on a recording pulse train including only one pulse, and a light irradiated based on a recording pulse train including only the first pulse and the last pulse. Including recording marks formed by the beam,
2. The optical data recording method according to claim 1, wherein an interval between any two adjacent pulses in the recording pulse train is 1T or more.   In the recording pulse train, in a multi-pulse region in which the multi-pulse train is arranged, a multi-pulse duty obtained by dividing a pulse width of the multi-pulse train by a cycle of the multi-pulse train, or an integrated value of the amplitude of the multi-pulse train is multiplied by the multi-pulse. 2. The optical data recording method according to claim 1, wherein the amplitude and the position of at least one pulse of the recording pulse train are set such that a multi-pulse amplitude average value obtained by dividing by a time width of a pulse region becomes a predetermined value.   The optical data recording method according to claim 11, wherein a cycle of the multi-pulse train is set to 2T.   12. The optical data recording method according to claim 11, wherein the multi-pulse region is defined by a falling timing of a last pulse from a rising timing of a leading pulse of the multi-pulse train.   12. The optical data recording method according to claim 11, wherein the multi-pulse region is defined by a falling timing of the first pulse and a rising timing of the last pulse.   The optical data recording method according to claim 11, wherein a rising timing of a leading pulse of the recording pulse train and a pulse width of each pulse of the recording pulse train are set.   A setting is made such that a leading space width sandwiched between the first pulse and the leading pulse of the pulse train and a trailing space width sandwiched between the last pulse and the last pulse of the multi-pulse train are substantially equal. 16. The optical data recording method according to 15.   Each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more), and the amplitude and position of at least one pulse of the set recording pulse train is the length of the recording modulation code. The optical data recording method according to claim 11, wherein the optical data recording method has a constant value regardless of the value.   Each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more), and the amplitude and position of at least one pulse of the set recording pulse train is determined by the length of the recording modulation code. 12. The optical data recording method according to claim 11, wherein the value is set to a different value depending on whether the value is an odd multiple or an even multiple of T.   Each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more), and the amplitude and position of at least one pulse of the set recording pulse train is determined by the length of the recording modulation code. The optical data recording method according to claim 11, wherein the optical data recording method is set to a different value each time.   The plurality of recording modulation codes have different lengths each represented by nT (n is an integer of 1 or more), and the plurality of recording modulation codes are classified into a plurality of code groups, and The optical data recording method according to claim 11, wherein the amplitude and the position of at least one pulse are set to different values for each code group.   Each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more), and the multi-pulse duty or multi-pulse amplitude average value is determined regardless of the length of the recording modulation code. The optical data recording method according to claim 11, wherein the optical data recording method is set to a constant value.   Each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more). The optical data recording method according to claim 11, wherein the value is set differently depending on whether the number is a multiple or an even number.   Each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more), and the multi-pulse duty or multi-pulse amplitude average value differs for each length of the recording modulation code. The optical data recording method according to claim 11, wherein the method is set to a value.   The plurality of recording modulation codes have different lengths each represented by nT (n is an integer of 1 or more), and the plurality of recording modulation codes are classified into a plurality of code groups, and the multi-pulse duty or the multi-pulse duty The optical data recording method according to claim 11, wherein the pulse amplitude average value is set to a different value for each code group.   Evaluating an amplitude value near the center of a reproduced signal obtained by forming a recording mark formed using the multi-pulse duty or the multi-pulse amplitude average value by using the recording pulse train and reproducing the formed recording mark. The optical data recording method according to claim 11, which is determined by: A motor for mounting and rotating an optical disc;
An optical head that includes a light source and irradiates a light beam from the light source to an optical disc mounted on the motor,
A signal processing unit that modulates data to be recorded and generates a plurality of recording modulation codes;
By irradiating the light beam, a plurality of recording pulse trains for driving the light source are formed in order to form a plurality of recording marks having lengths respectively corresponding to the plurality of recording modulation codes on the optical disc. A recording pulse train generation unit that generates based on the recording modulation code of
With
At least two of the plurality of recording pulse trains are:
A first pulse arranged at the beginning and for forming a start end of the recording mark;
A last pulse arranged at the rear end to form a terminal end portion of the recording mark;
A multi-pulse train arranged between the first pulse and the last pulse to form a central portion of the recording mark;
Wherein the pulse period of the multi-pulse train is longer than T, where T is a reference period of the recording modulation code. Each of the plurality of recording modulation codes has a different length represented by nT (n is an integer of 1 or more),
27. The data recording apparatus according to claim 26, wherein the recording pulse train generation unit generates a recording pulse train having the same number of pulses for at least two different recording modulation codes of n.   27. The data according to claim 26, wherein irradiation powers of light beams generated by at least one of the first pulse, the multi-pulse train, and the last pulse in recording pulse trains corresponding to the at least two recording modulation codes are different. Recording device.   In the recording pulse train, in a multi-pulse region in which the multi-pulse train is arranged, a multi-pulse duty obtained by dividing a pulse width of the multi-pulse train by a cycle of the multi-pulse train, or an integrated value of the amplitude of the multi-pulse train is multiplied by the multi-pulse. 27. The recording pulse train generation unit according to claim 26, wherein the recording pulse train generation unit generates a recording pulse train including at least one pulse whose amplitude and position are set such that a multi-pulse amplitude average value obtained by dividing by a time width of a pulse region becomes a predetermined value. The data recording device according to the above.   30. The data recording apparatus according to claim 29, wherein the recording pulse train generation unit generates the multi-pulse train having a period of 2T.

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