CN100397495C - Data recording method and apparatus for recording medium - Google Patents

Abstract

The present invention is a data recording method for recording data as edge position information of marks and spaces of a plurality of lengths on a recording medium by irradiating the recording medium with a pulse-like energy beam. When the shortest symbol length of a recording symbol sequence generated from data to be recorded is n (n is an integer of 1 or more), a recording waveform having 1 recording pulse is assigned to a recording mark formation period corresponding to a symbol having a symbol length x of n, n +1, or n +2, and a recording waveform having a plurality of recording pulses is assigned to a recording mark formation period corresponding to a symbol having a symbol length x of n +3 or more.

Description

Data recording method and device for recording medium

technical field

The present invention relates to a recording method and apparatus for recording data (information) by irradiating laser light on a recording medium such as an optical disc to form a mark having a physical property different from that of an unrecorded portion.

Background technique

A rewritable optical disk such as DVD-RAM has a phase-change recording film provided on a substrate. When the phase-change recording film is irradiated with laser light having a high energy density, the temperature of the irradiated portion locally reaches a temperature exceeding the melting point and melts. Since the optical disc irradiated with laser light rotates at high speed, the beam spot of the laser light moves at high speed along the track on the phase change recording film. Therefore, the portion of the phase-change recording film that was melted by the passage of the beam spot immediately cools naturally and solidifies. By adjusting the power of the laser light at this time, the melted portion of the phase change recording film is rapidly cooled and becomes amorphous. The region that becomes amorphous in the phase change recording film exhibits a different refractive index and light reflectance from other regions (crystalline regions). The amorphous region thus formed is called "mark". Also, the area between "mark" and "mark" on the track is called "space".

By arranging such marks and spaces on a track, data can be recorded on an optical disc. By irradiating the optical disc with weak laser light for reproduction and measuring the intensity of the reflected light, the boundary between marks and spaces (mark edges) can be detected, and data can be reproduced accordingly. The power of the laser light used for reproduction is kept low so as not to melt the phase change recording film.

With respect to these optical disc media, in order to increase the information transfer speed during data recording and reproduction, the recording linear density is increased, or the scanning speed of the beam spot on the optical disc media is increased.

In order to increase the recording line density, the length of the marks and the length of the space are reduced, or the scale of the change of the length of the mark and the length of the space is shortened, and the time width for detecting the edge position of the mark is shortened.

However, if the recording linear density is increased, the S/N ratio of the reproduced signal will decrease, so a large increase in the recording linear density is not desirable.

In order to form minute marks on an optical disc with high precision, a writing strategy is employed in which each mark is formed on a recording film by continuous irradiation of one or more laser pulses.

According to the first prior art described in JP-A-5-298737, a pulse train of laser light is allocated to a plurality of marks having different lengths. A pulse train of laser light to be irradiated to form each mark, that is, a waveform (recording waveform) indicating a change in intensity of the laser light is determined according to the length of the marks to be formed. The number and amplitude of pulses irradiated in each mark forming period are controlled according to the length of the recording symbol row.

The recording waveform in the mark formation period is divided into two parts: a start part and a subsequent part. The pulse height of each pulse is generally different. In addition, during periods other than the pulse forming period, intervals are arranged to generate recording auxiliary pulses.

According to the technology of JP-A-5-298737, it is possible to compensate the thermal diffusion from the preceding mark to the leading edge of the following mark without being affected by the space length, and to control the mark width and mark edge position with high precision.

In the second conventional technique described in JP-A-8-7277, each recording symbol is decomposed into a plurality of basic elements of different lengths, and each element is associated with one recording pulse. Then, each recording symbol is formed as each independent series of recording marks based on each recording pulse.

In the third conventional technique described in JP-A-9-134525, in a multi-pulse recording system consisting of a first heating pulse, a plurality of subsequent heating pulses, a rear cooling pulse, and a final cooling pulse, it is described when When recording a mark length of either an even length or an odd length for a recording channel and a clock cycle, the pulse widths of the rear heating pulse and the rear cooling pulse are substantially the same as the recording channel and the clock cycle.

In the fourth prior art of JP-A-11-175976, it is described that the injection energy and the number of pulses in the mark formation period are changed according to the mark length in the recording symbol sequence, so that the unit in the mark formation period of an arbitrary length mark A method in which the interval between any two change points of the implanted energy is longer than 1/2 times the width of the detection window.

In the first prior art described above, one recording pulse corresponds to an extension of the mark length of the detection window width. Therefore, when the width of the detection window is shortened, it is necessary to drive the semiconductor laser diode which is the source of recording energy at a higher speed than before. For example, when the general (1,7) modulation method is used to achieve a color burst transmission speed equivalent to 10MBytes/sec of a magnetic disk device, the detection window width of the reproduced signal becomes about 8.3ns (nanoseconds). Therefore, the shortest recording current The pulse width becomes about 4.2 ns which is about 1/2 of the detection window width. However, it takes several ns to rise the semiconductor laser, and it is difficult to generate accurate recording laser pulses. In addition, even if the correct recording laser pulse can be generated, when performing multi-pulse recording on a medium such as a phase change disk that controls the formation of marks according to the cooling rate of the heated part, the next light pulse is irradiated when the heated part is not sufficiently cooled. So normal mark formation becomes impossible. For example, when using the same (1,7) modulation method to achieve a color burst transmission speed of 10MBytes/sec, the cooling time of the recording medium is about 4.2ns equal to the shortest recording current pulse width, so it cannot be corrected according to the characteristics of the recording medium. Form a mark.

In the above-mentioned second prior art, it is described that each recording symbol is decomposed into a plurality of basic elements of different lengths, each element is associated with one recording pulse, and each recording symbol is regarded as a series of independent recording marks based on each recording pulse. method of formation. However, in the prior art, the heat balance among the recording pulses corresponding to each element is not considered, and when the recording line density increases, problems arise in the control of the mark edge position. That is, when a mark corresponding to one recording mark is to be formed, since the amount of heat stored in the recording film is different between the beginning of the recording mark and the rear end of the recording mark, the width of the recording mark varies depending on the position, and accurate edge recording cannot be performed.

In the third prior art described above, a pulse much shorter than the detection window width may be inserted into the recording waveform near the center of the mark formation period, and the pulse width in this vicinity varies greatly compared to other portions. In the description of the prior art, when the edge of the mark is recorded, if the edge position of the mark is correct, there will be no problem of large fluctuations in the frame rate of the signal at the center of the mark. However, in the case of a recording and reproducing device that detects the average level of the reproducing signal and determines the recording and reproducing conditions, such deformation of the reproducing signal adversely affects the operation of the device. For example, in the case of a phase-change recording medium, a signal can be detected using a change in reflectivity, as in a phase-pit type recording medium. Therefore, in the phase-change recording medium, there is an advantage that it is easy to share the reproducing device with the phase-pit type recording medium, but there is no such deformation in the reproduced signal from the phase-pit type recording medium, so based on the phase-pit type recording medium Reproduction with the same device becomes difficult.

In addition, in the above-mentioned fourth conventional technique, since the recording power level of the recording pulse train changes in a stepwise manner, complicated power control is required. In addition, when recording a signal with a symbol length of 4Tw, light is emitted at a power level higher than the average power level of at least 3Tw, and the density becomes high. Disadvantages of required record marking.

According to each of the above-mentioned prior arts, marks cannot be formed with sufficient accuracy at high transfer speeds, and as a result, sufficient recording area density and reliability cannot be achieved.

Contents of the invention

The present invention has been made in view of the above facts, and an object of the present invention is to provide a data recording method and a data recording device capable of forming marks with high precision even during high-speed transfer.

The data recording method of the present invention records data as edge position information of marks and spaces of multiple lengths on the recording medium by irradiating the recording medium with a pulsed energy beam, including: generating recording symbols based on the data to be recorded The step (A) of column; according to the symbol length of each symbol in the record symbol column, the step (B) of determining the recording waveform specifying the power modulation of the energy beam; according to the recording waveform, modulating the energy beam The step (C) of the power; The step (B) when the shortest symbol length of the record symbol column is n (n is an integer greater than 1), and the symbol length x is n, n+1, or n For a recording mark formation period corresponding to a symbol of +2, a recording waveform with one recording pulse is allocated, and for a recording mark formation period corresponding to a symbol with a symbol length x of n+3 or more, a plurality of recording pulses (Pw) are allocated. Record the waveform.

In a preferred embodiment, in the step (B), when the shortest symbol length of the record symbol column is n (n is an integer greater than 1), the symbol length is divided into n, n+1, n+2, n+ At least four of 3 or more, the number of recording pulses (Pw) included in the recording waveform in the recording mark formation period is equal to the symbol length m and the symbol length m+1, and the recording mark formation period of the symbol length m The period of any Kth recording pulse included in is "the recording pulse width of symbol length m", and the period of any Kth recording pulse included in the recording mark formation period of symbol length m+1 is "symbol length m+1 When the recording pulse width of ", the recording waveform is determined so that the relationship of (recording pulse width of symbol length m≤recording pulse width of symbol length m+1) is established.

In the preferred embodiment, the step (B) is concerned with the number of recording pulses (Pw) contained in the recording waveform during the recording mark formation period, the bottom power level (Pb) sandwiched between 2 recording pulses (Pw) ) period number equal to each other symbol length m and symbol length m+1 symbols, the period of any Kth bottom power level (Pb) included in the recording mark formation period of symbol length m is "pulse width of symbol length m ", when the period of any K-th bottom power level (Pb) included in the recording mark formation period of symbol length m+1 is "the pulse width of symbol length m+1", the recording waveform is determined, so that (symbol length m The relationship of pulse width≦pulse width of symbol length m+1) holds true.

In a preferred embodiment, a recording waveform in a recording mark formation period corresponding to a symbol having a symbol length x of n+3 or more includes a recording pulse equal to the quotient of (x-1) divided by 2.

In a preferred embodiment, the period of the erasing power level (Pe) of the recording waveform in the recording mark formation period corresponding to a symbol having a symbol length x of n+3 or greater is set to 1Tw or greater.

In a preferred embodiment, the period of the bottom power level (Pb) in each recording mark forming period is set to 1 Tw or more.

In a preferred embodiment, the period of the cooling power level (Pc) of the recording waveform in each recording mark forming period is set to 1 Tw or more.

In a preferred embodiment, the start position of the start pulse and the end position of the cooling pulse included in the recording waveform in the corresponding recording mark formation period are moved according to the symbol length x.

In a preferred embodiment, the movement is set to different sizes according to at least 4 intervals in which the symbol length x is n, n+1, n+2, n+3 or more.

The data recording device of the present invention records data as edge position information of marks and spaces of multiple lengths on the recording medium by irradiating the recording medium with a pulsed energy beam, including: A modulated laser drive unit; a coding unit that converts data that should be recorded into the recording medium into a recording symbol column; determines and specifies the power of the energy beam according to the symbol length of each symbol contained in the recording symbol column The mark length classification part of the recorded waveform of modulation; When the shortest symbol length of the record symbol column is n (n is an integer greater than 1), the mark length classification part is n, n+1, Or, during the recording mark formation period corresponding to a symbol of n+2, a recording waveform with one recording pulse is allocated, and for a recording mark formation period corresponding to a symbol whose symbol length x is n+3 or more, multiple recording pulses (Pw) are allocated. record waveform.

In the preferred embodiment, the number of recording pulses (Pw) included in the recording waveform in the recording mark forming period and the number of periods of the bottom power level (Pb) sandwiched between two recording pulses (Pw) are equal to each other. The symbol length m of the symbol length m and the symbol length m+1, the period of any Kth bottom power level (Pb) included in the recording mark formation period of the symbol length m is "the pulse width of the symbol length m", and the symbol length m+ When the period of any K-th bottom power level (Pb) included in the recording mark formation period of 1 is "the pulse width of symbol length m + 1", the recording waveform is determined so that (pulse width of symbol length m≤symbol length m +1 pulse width) holds true.

In a preferred embodiment, when the shortest symbol length of the record symbol column is n (n is an integer greater than 1), the symbol length x is divided into at least 4 of n, n+1, n+2, n+3 or more , with respect to the symbols of the symbol length m and the symbol length m+1 equal to the number of recording pulses (Pw) included in the recording waveform in the recording mark formation period, any K-th recording included in the recording mark formation period of the symbol length m When the period of the pulse is "the recording pulse width of the symbol length m", and the period of any K-th recording pulse included in the recording mark formation period of the symbol length m+1 is "the recording pulse width of the symbol length m+1", it is determined A waveform is recorded so that the relationship (recording pulse width of symbol length m≦recording pulse width of symbol length m+1) holds true.

In the preferred embodiment, the number of recording pulses (Pw) included in the recording waveform in the recording mark forming period and the number of periods of the bottom power level (Pb) sandwiched between two recording pulses (Pw) are equal to each other. The symbol length m of the symbol length m and the symbol length m+1, the period of any Kth bottom power level (Pb) included in the recording mark formation period of the symbol length m is "the pulse width of the symbol length m", and the symbol length m+ When the period of any K-th bottom power level (Pb) included in the recording mark formation period of 1 is "the pulse width of symbol length m + 1", the recording waveform is determined so that (pulse width of symbol length m≤symbol length m +1 pulse width) holds true.

In a preferred embodiment, a recording waveform in a recording mark formation period corresponding to a symbol having a symbol length x of n+3 or more includes a recording pulse equal to the quotient of (x-1) divided by 2.

In a preferred embodiment, the recording waveform is determined so that the entire interval between the falling and rising of the basic waveform of the laser pulse in the mark forming period is equal to or greater than the detection window width (Tw).

In a preferred embodiment, there is a pulse shifter for moving the start position of the start pulse and the end position of the cooling pulse included in the recording waveform in the corresponding recording mark formation period according to the symbol length x.

In a preferred embodiment, there is recording compensating means for setting the shift to be different in accordance with at least four intervals in which the symbol length x is n, n+1, n+2, n+3 or more.

Other data recording methods of the present invention record data on the recording medium as edge position information of marks and spaces of a plurality of lengths by irradiating the recording medium with a pulsed energy beam, including: generating a record according to the data to be recorded; The step (A) of the symbol column; according to the symbol length of each symbol in the record symbol column, the step (B) of determining the recording waveform specifying the power modulation of the energy beam; according to the recording waveform, modulating the energy beam The step (C) of the power of the beam; the step (B) sets the number of recording pulses (Pw) contained in the recording waveform during the recording mark formation period corresponding to the symbol length n and the symbol length n+1 to 1 , and the width of the recording pulse (Pw) included in the recording waveform during the recording mark formation period corresponding to the symbol length n is set to the recording pulse (Pw) included in the recording waveform during the recording mark formation period corresponding to the symbol length n+1. The width of the pulse (Pw) or less, the number of recording pulses (Pw) included in the recording waveform in the recording mark formation period corresponding to the symbol length n+2 and the symbol length n+3 is set to 2, and the symbol The width of the first recording pulse (Pw) included in the recording waveform during the recording mark formation period corresponding to the length n+2 is set to the first recording pulse (Pw) included in the recording waveform during the recording mark formation period corresponding to the symbol length n+3. The width of the recording pulse (Pw) or less, and the width of the second recording pulse (Pw) included in the recording waveform in the recording mark formation period corresponding to the symbol length n+2 is set to the recording corresponding to the symbol length n+3. The width of the second recording pulse (Pw) included in the recording waveform in the mark formation period is equal to or less.

Other data recording methods of the present invention record data on the recording medium as edge position information of marks and spaces of a plurality of lengths by irradiating the recording medium with a pulsed energy beam, including: generating a record according to the data to be recorded; The step (A) of the symbol column; according to the symbol length of each symbol in the record symbol column, the step (B) of determining the recording waveform specifying the power modulation of the energy beam; according to the recording waveform, modulating the energy beam The step (C) of the power of beam; The step (B) divides the symbol length x into n, n+1, n when the shortest symbol length of the record symbol column is n (n is an integer greater than 1) At least 4 of +2, n+3 or more, symbols with a symbol length m equal to the number of recording pulses (Pw) included in the recording waveform in the recording mark formation period and a symbol length m+1, the symbol length m The period of any K-th recording pulse included in the recording mark formation period of is "the recording pulse width of symbol length m", and the period of any K-th recording pulse included in the recording mark formation period of symbol length m+1 is " When recording pulse width of symbol length m+1", the recording waveform is determined so that the relationship (recording pulse width of symbol length m≤recording pulse width of symbol length m+1) holds true.

Other data recording methods of the present invention record data on the recording medium as edge position information of marks and spaces of a plurality of lengths by irradiating the recording medium with a pulsed energy beam, including: generating a record according to the data to be recorded; The step (A) of the symbol column; according to the symbol length of each symbol in the record symbol column, the step (B) of determining the recording waveform specifying the power modulation of the energy beam; according to the recording waveform, modulating the energy beam The step (C) of the power of the beam; the step (B) regarding the number of recording pulses (Pw) contained in the recording waveform during the recording mark formation period, the bottom power sandwiched by 2 recording pulses (Pw) In the symbols of the symbol length m and the symbol length m+1 whose number of periods of the level (Pb) is equal to each other, the period of any K-th bottom power level (Pb) included in the recording mark formation period of the symbol length m is "symbol length m When the period of any K-th bottom power level (Pb) included in the recording mark formation period of symbol length m+1 is "the pulse width of symbol length m+1", the recording waveform is determined, thus (symbol The relationship of pulse width of length m≦pulse width of symbol length m+1) holds true.

Another data recording device of the present invention records data on the recording medium as edge position information of marks and spaces of a plurality of lengths by irradiating the recording medium with a pulsed energy beam, including: A laser drive unit for power modulation; a coding unit that converts the data that should be recorded into the recording medium into a recording symbol column; according to the symbol length of each symbol contained in the recording symbol column, determine the energy beam A mark length classifying part of the recording waveform of power modulation; the mark length classifying part sets the number of recording pulses (Pw) contained in the recording waveform during the recording mark formation period corresponding to the symbol length n and the symbol length n+1 is 1, and the width of the recording pulse (Pw) included in the recording waveform during the recording mark formation period corresponding to the symbol length n is set to be included in the recording waveform during the recording mark formation period corresponding to the symbol length n+1. The width of the recording pulse (Pw) or less, the number of recording pulses (Pw) included in the recording waveform in the recording mark formation period corresponding to the symbol length n+2 and the symbol length n+3 is set to 2, and The width of the first recording pulse (Pw) included in the recording waveform during the recording mark formation period corresponding to the symbol length n+2 is set to be 1000 Ω included in the recording waveform during the recording mark formation period corresponding to the symbol length n+3. The width of the first recording pulse (Pw) is equal to or smaller than that, and the width of the second recording pulse (Pw) included in the recording waveform in the recording mark formation period corresponding to the symbol length n+2 is set to correspond to the symbol length n+3 The width of the second recording pulse (Pw) included in the recording waveform during the recording mark formation period is equal to or smaller than the width of the second recording pulse (Pw).

Another data recording device of the present invention records data on the recording medium as edge position information of marks and spaces of a plurality of lengths by irradiating the recording medium with a pulsed energy beam, including: A laser drive unit for power modulation; a coding unit that converts the data that should be recorded into the recording medium into a recording symbol column; according to the symbol length of each symbol contained in the recording symbol column, determine the energy beam A mark length classification unit of a power-modulated recording waveform; the mark length classification unit divides the symbol length x into n, n+1 when the shortest symbol length of the record symbol column is n (n is an integer greater than 1) , n+2, n+3 or more, the number of recording pulses (Pw) included in the recording waveform in the recording mark formation period is equal to the symbol length m and the symbol length m+1, the symbol The period of any K-th recording pulse included in the recording mark formation period of length m is "the recording pulse width of symbol length m", and the period of any K-th recording pulse included in the recording mark formation period of symbol length m+1 In the case of "recording pulse width of symbol length m+1", the recording waveform is determined such that the relationship (recording pulse width of symbol length m≤recording pulse width of symbol length m+1) holds.

Another data recording device of the present invention records data on the recording medium as edge position information of marks and spaces of a plurality of lengths by irradiating the recording medium with a pulsed energy beam, including: A laser drive unit for power modulation; a coding unit that converts the data that should be recorded into the recording medium into a recording symbol column; according to the symbol length of each symbol contained in the recording symbol column, determine the energy beam Mark length classification means for power-modulated recording waveforms; the mark length classification means is sandwiched by two recording pulses (Pw) with respect to the number of recording pulses (Pw) included in the recording waveform during the recording mark formation period For symbols of symbol length m and symbol length m+1 in which the number of periods of the bottom power level (Pb) is equal to each other, the period of any K-th bottom power level (Pb) included in the recording mark formation period of the symbol length m is "symbol When the period of any K-th bottom power level (Pb) included in the recording mark formation period of the symbol length m+1 is the "pulse width of the symbol length m+1", the recording waveform is determined, so that The relationship (pulse width of symbol length m≦pulse width of symbol length m+1) holds true.

Other data recording devices of the present invention record data on the recording medium as edge position information of marks and spaces of a plurality of lengths by irradiating the recording medium with a pulsed energy beam, including: generating a record according to the data to be recorded; The step (A) of the symbol column; according to the symbol length of each symbol in the record symbol column, the step (B) of determining the recording waveform specifying the power modulation of the energy beam; according to the recording waveform, modulating the energy beam The step (C) of the power of the beam; the number of recording pulses (Pw) equal to the number of recording pulses (Pw) contained in the recording waveform in the recording mark formation period and the symbol of the symbol length m+1, the recording mark of the symbol length m The period of any K-th recording pulse included in the formation period is "the recording pulse width of symbol length m", and the period of any K-th recording pulse included in the recording mark formation period of symbol length m+1 is "symbol length m When the recording pulse width is "+1", the recording waveform is determined such that the relationship (recording pulse width of symbol length m≤recording pulse width of symbol length m+1) holds true.

Other data recording devices of the present invention record data on the recording medium as edge position information of marks and spaces of a plurality of lengths by irradiating the recording medium with a pulsed energy beam, including: generating a record according to the data to be recorded; The step (A) of the symbol column; according to the symbol length of each symbol in the record symbol column, the step (B) of determining the recording waveform specifying the power modulation of the energy beam; according to the recording waveform, modulating the energy beam The step (C) of beam power; regarding the number of recording pulses (Pw) included in the recording waveform in the recording mark forming period, the period of the bottom power level (Pb) sandwiched between 2 recording pulses (Pw) Symbols of symbol length m and symbol length m+1 equal to each other, the period of any K-th bottom power level (Pb) included in the recording mark formation period of symbol length m is "pulse width of symbol length m", and symbol When the period of any K-th bottom power level (Pb) included in the recording mark formation period of length m+1 is "the pulse width of symbol length m+1", the recording waveform is determined so that (pulse width of symbol length m≤ The relationship of symbol length m+1 pulse width) holds.

Description of drawings

The accompanying drawings are briefly described below.

FIG. 1 is a diagram showing the overall configuration of a data recording device of the present invention.

FIG. 2 is a diagram illustrating the configuration of the recording processing system shown in FIG. 1 .

3( a ) to ( h ) are diagrams for explaining the operation of the recording processing system based on the present invention and the prior art.

4(a) to (j) are diagrams showing recording waveforms employed in Embodiment 1 of the data recording apparatus of the present invention.

5( a ) to ( i ) are diagrams showing recording waveforms of a recording processing system of a conventional data recording device (comparative example).

6(a) to (j) are diagrams showing recording waveforms employed in Embodiment 2 of the data recording apparatus of the present invention.

7(a) to (j) are diagrams showing recording waveforms employed in Embodiment 3 of the data recording apparatus of the present invention.

Fig. 8 is a diagram illustrating an example of adaptive marker compensation of the present invention.

Fig. 9 is a diagram illustrating an example of adaptive marker compensation of the present invention.

FIG. 10 is a diagram showing the configuration of a recording processing system of a conventional data recording device.

11(a) to (j) are diagrams showing recording waveforms employed in Embodiment 4 of the data recording apparatus of the present invention.

12(a) to (j) are diagrams showing recording waveforms employed in Embodiment 5 of the data recording apparatus of the present invention.

13( a ) and ( b ) show two types of recording waveforms for forming a 4Tw long mark, and FIGS. 13( c ) and ( d ) are diagrams schematically showing the shape of the formed mark, respectively.

Detailed ways

In the write strategy of the conventional optical disc device, as described above, the number of multi-pulses is increased so that the shape of the mark does not expand at the end portion.

The present inventors found that when recording data at a high speed, instead of increasing the number of multi-pulses, the pulse width can be increased to maintain the shape of the mark appropriately, and came up with the present invention. In the future, if the data transfer rate becomes higher than 72 Mbps, it will be necessary to further increase the operating frequency of the semiconductor laser used as the light source of the data recording device in the conventional write strategy with a large number of multi-pulses. However, it is difficult to further increase the operating frequency of semiconductor lasers.

In the preferred embodiment of the present invention, as will be described later, since data is recorded with one pulse for a relatively short mark with a symbol length of 2 to 4Tw, it is not necessary to further improve the characteristics of the semiconductor laser. In addition, the shape of the mark formed is appropriate, so reading errors do not increase.

Embodiments of the present invention will be described below with reference to the drawings.

[Example 1]

First, Embodiment 1 of the data recording device of the present invention will be described.

In this embodiment, a phase-change type optical disk is used as the recording medium, but the recording medium usable in the present invention is not limited to such an optical disk. For example, a recording medium that can locally form "marks" that have physical properties different from other parts by injecting energy other than light such as magnetic energy and electron beams is suitable for use in the present invention.

The present invention is characterized by a write strategy capable of controlling the level of energy irradiated to the recording medium (recording energy) with high precision when recording data on the recording medium. Here, the "level of recording energy" means the average energy level of the laser over a period of about 1/2 of the detection window width (the change unit of the edge positions of marks and spaces). When a frequency component much higher than the frequency corresponding to the period of the detection window width is superimposed on the recording waveform for some reason such as suppressing laser noise, it means that the period over which the influence of the frequency component can be ignored is negligible. average energy level.

First, refer to FIG. 1 . Fig. 1 shows the overall structure of a preferred embodiment of the data recording apparatus of the present invention. As shown in FIG. 1, the apparatus of this embodiment includes an optical pickup, a recording processing system, and a reproduction processing system.

The optical pick-up has: the laser device 110 of emitting laser light 123; The collimating lens 109 of laser light 123 parallelization; Half-transparent mirror 108; A detection lens 106; a photodetector 100 for detecting reflected light; a preamplifier 101 for amplifying the output of the photodetector 100.

The laser 110 in this embodiment is a semiconductor laser oscillating at a wavelength of 405 nm, and the NA of the objective lens 116 is 0.85. In FIG. 1 , only one type of laser 110 and its corresponding optical system are shown, but one optical pickup may have light source modules that emit laser light of different wavelengths and its corresponding optical system.

The recording processing system shown in Fig. 1 has: the encoder 113 that converts recording data 127 into recording symbol sequence (NRZI) 126; The pulse shifting circuit 115 that generates the pulse generating signal 130 from the level generating signal 125 ; and the laser driving circuit 111 that outputs the laser driving current 124 based on the pulse generating signal 130 . A reference time signal 128 is input from a reference signal generator 119 to the encoder 113 and the recording waveform generation circuit 112 . The frequency of the reference time signal 128 in this embodiment is 72MHz, and the detection window width Tw=7.58ns. The recording processing system also has a power setter 114 and a recording compensator 118 .

The reproduction processing system shown in Fig. 1 has: the waveform equalizer 103 that receives the reproduction signal 120 output from the preamplifier 101 of the optical pickup and performs waveform equalization processing; converts the reproduction signal into the binary value of the binary reproduction signal Converter 104; Decoder 105 for decoding the binarized reproduced signal 121 to generate reproduced data 122.

Next, the operation of the data recording device shown in Fig. 1 will be described.

The encoder 113 of the recording processing system receives recording data 127 to be recorded on the optical disc 117 and converts the recording data 127 into a recording symbol sequence (NRZI) 126 corresponding to the mark interval formed on the optical disc 117 . The recording waveform generating circuit 112 receives the recording symbol sequence 126 and converts it into a level generating signal 125 corresponding to the recording waveform. The encoder 113 and the recording waveform generating circuit 112 work synchronously with the reference time signal 128 generated by the reference time generator 119 .

The pulse shifting circuit 115 receives the level generating signal 125 and sends it to the laser driving circuit 111 as a pulse generating signal 130 . At this time, the pulse shifting circuit 115 compensates the pulse waveform of the level generating signal 125 in accordance with the recording compensation table value of the recording compensator 118 on the time axis, and forms the pulse generating signal 130 .

The laser driving circuit 111 generates a laser driving current 124 according to the pulse generation signal 130 . The laser driving current 124 is injected into the laser 110 to drive the laser 110 . The laser 110 emits laser light 123 according to a given recording waveform. The power level of the laser light 123 is varied according to the recording waveform.

The laser light 123 emitted from the laser 110 is converged onto the optical disk 117 through the collimating lens 109 , the half mirror 108 and the objective lens 116 . The focused pulsed laser light 123 locally heats the phase change recording film on the optical disc 117 rotating at high speed, and forms marks and spaces along the track of the optical disc 117 . At this time, when the phase-change recording film is irradiated with pulsed laser light 123 at short intervals, the melted portions of the phase-change recording film are connected to form one long mark. As described above, the power level of the laser light 123 depends on the recording waveform, so if the recording waveform is properly controlled, a long mark can be formed by a plurality of pulses.

When data recorded on the optical disc 117 is reproduced, the laser beam 123 with low power so as not to destroy (melt) the marks formed on the phase-change recording film scans the mark row on the optical disc 117 . The reflected light from the optical disc 117 enters the detection lens 106 through the objective lens 116 and the half mirror 108 .

The laser light reflected by the optical disc 117 is converged onto the photodetector 100 through the detection lens 106 . The photodetector 100 converts the incident light into an electrical signal according to the light intensity distribution of the laser light on the light receiving surface. This electrical signal is amplified by a preamplifier 101 provided in the photodetector 100 to generate a reproduced signal 120 corresponding to the presence or absence of a mark at a scanning position on the optical disc 117 .

The reproduced signal 120 is subjected to waveform equalization processing by the waveform equalizer 103 and converted into a binarized reproduced signal 121 by the binarizer 104 . The decoder 105 performs the inverse transformation of the encoder 113 on the binarized reproduction signal 121 to generate reproduction data 122 .

The optical disc 117 may be either a single-layer disc whose information-recordable recording surface has a single layer or a two-layer disc whose information-recordable recording surface has two layers. In addition, in addition to a rewritable optical disc medium using a phase-change recording material, a one-time writeable optical disc medium in which only one addition can be performed may be used.

In addition to (1,7) modulation, the encoding method can also be 17PP modulation or 8-16 modulation. In the case of 8-16 modulation, the shortest symbol length is 3T, but in this case, it may be an example in which 1 is added to the symbol length in this embodiment using (1,7) modulation.

The configuration example of the recording processing system shown in FIG. 1 will be described in more detail below with reference to FIG. 2 .

The recording data 127 is converted by the encoder 113 into a recording symbol sequence 126 indicating mark lengths, space lengths, and their start position information. The record symbol column 126 is passed to the mark length sorter 201 and the record waveform table 202 . In the mark length classifier 201, the mark lengths of the recording symbol column 126 are classified according to a given rule, and the result is input into the recording waveform table 202 as a mark length classification signal 204.

The counter 200 refers to the recording symbol column 126 and counts the time from the mark start position in units of the reference time signal 128 to generate a count signal 205 . Recorded waveform table 202 sends level generation signal 125 reflecting a predetermined recorded waveform to pulse shifting circuit 115 based on recorded symbol sequence 126 , mark length classification signal 204 , and count signal 205 .

The pulse waveform of the level generation signal 125 is compensated on the time axis according to the recording compensation table value of the recording compensator 118 , and is sent to the laser driving circuit 111 as a pulse generation signal 130 . The pulse generation signal 130 includes a Pc generation signal 206 , a Pb generation signal 207 , a Pe generation signal 208 , and a Pw generation signal 209 indicating a power level of a predetermined recording waveform. The laser driving circuit 111 drives the laser 110 according to the pulse generation signal 130 .

Next, the recording symbol sequence of this embodiment will be described with reference to FIGS. 3(a) to (h). It should be noted that, for arbitrary reasons, the length or level of a part of the recorded waveform may be finely adjusted with reference to the recorded pattern or symbol length lamps before and after. In the description of the recording waveforms below, when such recording compensation is performed, the recording waveforms before fine adjustment are compared. Therefore, in the description of the recording waveforms below, a case where the recording pattern is the same across a sufficiently long distance before and after the formed marks is shown. Here, "a sufficiently long distance" means a distance much longer than the distance on the medium affected by the injection of recording energy over a period of approximately the width of the detection window.

FIG. 3( a ) shows a reference time signal 128 serving as a time reference for the recording operation. "Tw" is 1 cycle of the clock.

FIG. 3(b) shows a recording symbol sequence 126 obtained by performing NRZI conversion on the recording data by the encoder 113. As shown in FIG. The signal waveform representing the recording symbol column 126 transitions between the level of "1" and the level of "0". The detection window width is equal to Tw, which is the minimum unit of the change amount of the mark length and the space length of the recording symbol row 126 .

Fig. 3(c) schematically shows the planar shapes of marks and spaces actually recorded on the optical disc. For data recording, while changing the power level, the beam spot of the laser beam formed on the optical disk is moved from left to right in FIG. 3(c) to form a row of marks as shown in FIG. 3(c). The mark 301 shown in FIG. 3( c ) is formed corresponding to the level of "1" in the recording symbol column 126 . The length of the mark 301 is proportional to the period during which the level of the recording symbol sequence 126 is "1".

FIG. 3( d ) shows the count signal 205 . The time from the beginning of the mark 301 and the interval 302 is counted in units of Tw.

FIG. 3( e ) is a diagram for comparison, showing a mark length classification signal 307 of a conventional device. In this conventional device, the mark lengths are classified into odd multiple lengths and even multiple lengths.

FIG. 3( f ) shows a recording waveform 303 of a conventional device corresponding to the recording symbol sequence 126 in FIG. 3( b ). The recording waveform 303 is generated with reference to the count signal 205 , the recording symbol string 126 , and the mark length classification signal 307 .

FIG. 3(g) shows the mark length classification signal 204 of this embodiment. In this embodiment, the mark length is separated into the shortest symbol length (2T), the second shortest symbol length (3T), the third shortest symbol length (4T), and the fourth shortest symbol length. Shorter or shorter symbol lengths are classified into odd-numbered and even-numbered symbol lengths.

FIG. 3( h ) shows a recording waveform 304 of this embodiment corresponding to the recording symbol sequence 126 in FIG. 3( b ). The recording waveform 304 is generated with reference to the count signal 205 , the recording symbol sequence 126 , and the mark length classification signal 204 .

Next, signal waveforms used for mark formation of the present invention will be described in detail with reference to FIG. 2 and FIGS. 4( a ) to ( j ). 4( a ) to ( j ) show recording waveforms 400 to 407 , respectively.

In addition, in this embodiment, the encoding method of the encoder 113 ( FIG. 3 ) is to perform NRZI modulation after (1, 7) encoding and modulation, so the mark length and space length must be 2 Tw or more and 8 Tw or less. However, it can also be adapted when a signal such as 9Tw is intentionally inserted as a synchronization signal. However, this fact does not limit the encoding rule of the encoder 113, and the present invention can be applied to an encoder 113 having an arbitrary encoding rule (for example, 8-16) modulation.

The mark length classifier 201 of the present embodiment first classifies the mark length n of the marks to be formed into 4 types of 2T, 3T, 4T, or 5T or more. Then, when the symbol length n is 5T or more, division by the divisor 2 (calculation of the remainder) is performed on (n-1) to obtain the quotient. The mark length classifier 201 outputs the quotient as a mark length classification signal. For example, if the symbol length n is 5, the quotient of (5-1)=4 based on the divisor 2 is 2. Furthermore, if the symbol length n is 6, the quotient of (6-1)=5 based on the divisor 2 is also 2. Therefore, the same tag length classification signal is output for both tags of 5Tw and 6Tw lengths.

Based on such a mark length classification signal, it is possible to distinguish when the mark/space of the recording symbol row is an even-number multiple of the detection window width Tw and when it is an odd-number multiple of the length. In this embodiment, the divisor is set to 2 for simplicity, but other divisors of 3 or more may be used. In addition, the token length classifier 201 of this embodiment operates according to the calculation of the remainder, but the present invention is not limited thereto.

Referring to Figure 4(a)-(j) below.

FIG. 4( a ) shows the waveform of the reference time signal 128 . FIG. 4( b ) shows the count signal 205 generated by the counter 200 . The time from the beginning of the mark is counted by the detection window width Tw. The timing at which the count signal transitions to 0 corresponds to the beginning of a mark or a space. 4(c) to (j) show signal waveforms when marks of 2Tw length to 9Tw length are formed.

It should be noted that the "mark formation period" in this specification is defined as the period from the rising position of the start pulse to the falling position of the final pulse, as shown in FIG. 4(j).

As shown in FIG. 4( c ), the recording waveform in the mark formation period when forming a 2Tw long mark is composed of pulses with a length of 0.5Tw to 1Tw and a level of Pw.

As shown in FIG. 4( d ), the recording waveform in the mark formation period when forming a 3Tw long mark is composed of pulses with a length of 1Tw to 2Tw and a level of Pw. However, the mark formation period is 0.5Tw longer than the mark formation period of 2Tw length.

As shown in FIG. 4( e ), the recording waveform in the mark formation period when forming a mark with a length of 4Tw is composed of a pulse with a length of 1.5Tw to 2.5Tw and a level Pw. However, the mark formation period is 0.5Tw longer than the mark formation period of 3Tw length.

In a conventional data recording device such as a DVD player or recorder, a mark with a length of 4Tw is formed according to a recording waveform including two recording pulses (Pw) in one mark forming period as shown in FIG. 13( a ). The wavelength of the recording pulse is about 650 nm in DVD. In such a device, if one recording pulse (Pw) as shown in FIG. 13(b) is used to form a 4Tw long mark, as shown in FIG. 13(c), there is a problem that the width of the mark expands at the end portion. However, in this embodiment, even with one recording pulse as shown in FIG. 13( b ), it is possible to form a mark of an appropriate shape with good reproducibility as shown in FIG. 13( d ).

It should be noted that Blue-ray Disc (BD) is being developed as a next-generation optical disc. However, in BD, the wavelength of laser light used for recording/reproducing is about 400 nm. In addition, the material and composition of the recording layer in BD are also different from the material and composition of the recording layer in DVD. In addition, there are many differences in physical structure between BD and DVD. In BD, compared with DVD, it is necessary to make the recording pulse width and interval narrower than DVD, so if the data transfer speed is increased, even if the recording pulse of the waveform shown in Fig. 13(a) is used, the shape of the 4Tw length mark There is also a possibility of deformation. On the other hand, when a mark of 4 Tw length is formed by one recording pulse as shown in FIG. 13(b), a mark of a desired shape can be obtained also in BD.

The recording waveform of the mark formation period when a 5Tw long mark is formed is shown in FIG.

The recording waveform of the mark forming period when a 6Tw long mark is formed is shown in FIG.

The recording waveforms during the mark formation period when 7Tw and 9Tw length marks (odd length marks with a symbol length of 5Tw or more and a detection window width Tw) are formed are shown in Figures 4(h) and 4(i). In the center, as shown in the figure, a period of length 1Tw of length 2Tw, a period of horizontal Pe, a period of length 1 Tw, and a period of horizontal Pw are added.

The recording waveform during the mark formation period when an 8Tw-length mark (a mark with a symbol length of 5Tw or more and an even-length mark with a detection window width Tw) is formed is shown in Fig. 4(i). Mark length 1Tw of length 2Tw, period of horizontal Pe, length 1Tw, period of horizontal Pw.

It should be noted that the signal waveform in the mark non-forming period does not depend on the space length, and the Pe level is maintained until the next mark forming period. In this embodiment, the shortest Pe level (shortest cooling period) in the mark forming period 305 is set to 1Tw.

According to this embodiment employing the above writing strategy, it is possible to form appropriate marks with good reproducibility without being affected by the rising speed/falling speed of the optical output of the semiconductor laser element. For example, when the data transmission speed is 72 Mbps, Tw becomes 7.6 ns. At this time, since 0.5Tw=3.8ns, if the rising speed and falling speed of the optical output of the semiconductor laser element are 2ns, the peak power and bottom power cannot be reached, and the desired mark shape cannot be formed. On the other hand, if the writing strategy of this embodiment is adopted, even if the rising speed and falling speed of the optical output of the semiconductor laser element are not increased above the current level, faithful modulation of the laser power can be realized in the recording waveform.

In addition, in this embodiment, with regard to the symbols of the symbol length m and the symbol length m+1 equal to the number of recording pulses (Pw) included in the recording waveform in the recording mark forming period, in the recording mark forming period of the symbol length m The period of any Kth recording pulse included is "the recording pulse width of symbol length m", and the period of any Kth recording pulse included in the recording mark formation period of symbol length m+1 is "the recording pulse width of symbol length m+1". In the case of "recording pulse width", the recording waveform is determined so that the relationship of (recording pulse width of symbol length m)≤(recording pulse width of symbol length m+1) holds.

According to this, it is possible to obtain the effect of making the mark shape an appropriate shape.

In this embodiment, the period of the erasing power level (Pe) of the recording waveform in the recording mark formation period corresponding to the symbol whose symbol length x is n+3 or more is set to be 1Tw or more. Accordingly, even if the rise rate and fall rate of the light output of the semiconductor laser element are about 2 ns, the laser can be modulated with the required recording power, so that marks can be formed with good reproducibility.

[Example 2]

Next, Embodiment 2 of the data recording method of the present invention will be described with reference to FIG. 6. FIG.

The data recording method of this embodiment can be executed only by changing the operating program of the data recording device of the first embodiment. Therefore, the structure of the data recording device of this embodiment has substantially the same structure as that shown in FIGS. 1 and 2 , and detailed description thereof will not be repeated.

Referring to FIGS. 6( a ) to ( j ), recording waveforms 600 to 607 of this embodiment are shown.

By comparing Fig. 6(a)~(j) with Fig. 4(a)~(j), it can be seen that the signal waveforms 600~607 used in this embodiment are similar to the signal waveforms 400~407 in Fig. 4 . As shown in FIGS. 6( c ) to ( e ), signal waveforms 600 to 602 are the same as signal waveforms 400 to 402 . The difference between Embodiment 1 and Embodiment 2 lies in the form of the signal waveform whose symbol length n is 5Tw or more.

Refer to Figure 6(f). When the 5Tw length mark is formed, the recording waveform follows a pulse of 1Tw and horizontal Pw, a period of length 1Tw and horizontal Pb, and a period of length 1Tw and horizontal Pw. Here, it should be noted that the level Pb is lower than the level Pe in the period between two pulses.

The recording waveform when forming a 6Tw long mark is shown in FIG.

The recording waveform when the symbol length is 5Tw or more and a mark of an odd multiple of the window width Tw is detected is as shown in Figure 6(h) and (j), and a mark length 1Tw with a mark length of 2Tw is added to the center of the mark forming part as shown in the figure. Horizontal, Pb period, length 1Tw, horizontal Pw period.

The recording waveform when the symbol length is 5Tw or more and an even multiple of the window width Tw is detected is shown in FIG. Period, length 1Tw, period of level Pw.

According to this embodiment, the number of recording pulses (Pw) included in the recording waveform in the recording mark formation period and the number of periods of the bottom power level (Pb) sandwiched between two recording pulses (Pw) are equal to each other in the symbol length m and symbol length m+1, the period of any K-th bottom power level (Pb) included in the recording mark formation period of symbol length m is "pulse width of symbol length m", recording of symbol length m+1 When the period of any K-th bottom power level (Pb) included in the mark forming period is "the pulse width of symbol length m+1", the recording waveform is determined so that (pulse width of symbol length m ≤ pulse width of symbol length m+1 pulse width) relationship is established. The shorter the symbol length is, the easier it is to accumulate heat at the end of the mark, but according to the relationship (pulse width of symbol length m ≤ pulse width of symbol length m+1), it can be achieved to ease the heat accumulation and adjust the mark. shape effect.

In this embodiment, the period of the bottom power level (Pb) of the recording waveform in each recording mark formation period is set to 1 Tw or more. Accordingly, even if the light output of the semiconductor laser element rises and falls at a speed of 2 ns, the laser can be modulated with the required recording power, so that marks can be formed with good reproducibility.

[Example 3]

Next, referring to FIG. 7, Embodiment 3 of the data recording method of the present invention will be described.

The data recording method of this embodiment can be executed only by changing the operating program of the data recording device of the first embodiment. Therefore, the structure of the data recording device of this embodiment has substantially the same structure as that shown in FIGS. 1 and 2 , and detailed description thereof will not be repeated.

Referring to FIGS. 7( a ) to ( j ), recording waveforms 700 to 707 of this embodiment are shown.

By comparing Fig. 7(a)-(j) with Fig. 6(a)-(j), it can be seen that the signal waveforms 700-707 used in this embodiment are similar to the signal waveforms 600-607 in Fig. 6 . The difference between Example 2 and Example 3 is that a period of length 1 Tw to 1.5 Tw and level Pc is placed at the beginning of the mark non-forming period, and then the Pe level is maintained until the next mark forming period. In this embodiment, the level Pc and the level Pb are set to different power levels, but the level Pc and the level Pb may be set to be equal.

[Example 4]

Next, referring to FIG. 11, Embodiment 4 of the data recording method of the present invention will be described.

The data recording method of this embodiment can be executed only by changing the operating program of the data recording device of the first embodiment. Therefore, the structure of the data recording device of this embodiment has substantially the same structure as that shown in FIGS. 1 and 2 , and detailed description thereof will not be repeated.

Referring to FIGS. 11( a ) to ( j ), recording waveforms 1100 to 1107 of this embodiment are shown.

By comparing Fig. 11(c)～(j) with Fig. 4(c)～(j), it can be seen that the signal waveforms 1100, 1101, 1103～1107 adopted in this embodiment are the same as the signal waveforms 400, 401, 403-407 are the same. The characteristic point in this embodiment is shown in FIG. 11(e). After forming a 4Tw long mark, the recording waveform is a pulse of 0.5Tw and horizontal Pw, followed by a period of length 1Tw and horizontal Pe, a length of 0.5Tw, and horizontal Pw. period. Then, the Pe level is maintained until the next mark formation period.

FIG. 11(b1) is a count signal 205 generated by the counter 200, and the time from the head of the mark is counted by the detection window width Tw. The timing at which the count signal transitions to 0 corresponds to the start of a mark or interval.

FIG. 11(b2) is the sub count signal 210 generated by the counter 200, and the phase becomes 180° with respect to the reference signal. The timing at which the count signal transitions to 0 is delayed by a phase of 180° from the beginning of the mark or space.

As shown in FIG. 11( e ), the pulse width of Pw is 0.5Tw, but it may be at least 0.5Tw. Here, either or both of the start end and end end of each pulse are synchronized with the sub count signal.

In this embodiment, the falling portion of the first pulse and the rising portion of the second pulse in the 4Tw long signal waveform 1102 are synchronized with the sub count signal 210 .

[Example 5]

Next, referring to Fig. 12, Embodiment 5 of the data recording method of the present invention will be described.

The data recording method of this embodiment can be executed only by changing the operating program of the data recording device of the first embodiment. Therefore, the structure of the data recording device of this embodiment has substantially the same structure as that shown in FIGS. 1 and 2 , and detailed description thereof will not be repeated.

Referring to FIGS. 12( a ) to ( j ), recording waveforms 1200 to 1207 of this embodiment are shown.

Fig. 12(a) shows the waveform of the reference time signal. FIG. 12(b1) is a count signal 205 generated by the counter 200, and the time from the head of the mark is counted by the detection window width Tw. The timing at which the count signal transitions to 0 corresponds to the start of a mark or interval. Fig. 12(b2) is the sub count signal 210 generated by the counter 200, and the phase becomes 180° with respect to the reference signal. The timing at which the count signal transitions to 0 is delayed by a phase of 180° from the beginning of the mark or space.

The recording waveform at the time of forming a 2Tw long mark is composed of pulses with a length of 1Tw and a horizontal Pw, as shown in FIG. 12(c). In the mark non-forming period, a period of length 1Tw and level Pc is started, and the Pe level is maintained until the next mark forming period.

The recording waveform at the time of forming a 3Tw long mark is composed of pulses with a length of 2Tw and a horizontal Pw, as shown in FIG. 12(d). In the mark non-forming period, a period of length 1Tw and level Pc is started, and the Pe level is maintained until the next mark forming period. However, the mark formation period is longer than the 2Tw mark formation period by 0.5Tw or more.

The recording waveform when forming a 4Tw long mark is as shown in FIG. In the mark non-forming period, a period of length 1Tw and level Pc is placed at the beginning, and then the Pe level is maintained until the next mark forming period.

When detecting a mark of an even multiple of the window width Tw, as shown in Fig. 12(g) and (i), a period of length 1Tw of mark length 2Tw and a period of length 1Tw of horizontal Pb are added to the center of the mark forming part as shown in the figure. , The period of the level Pw. In the mark non-forming period, a period of length 1Tw and level Pc is placed at the beginning, and then the Pe level is maintained until the next mark forming period.

The recording waveform when forming a 5Tw long mark is shown in FIG. 12(f). After a pulse of length 1Tw and horizontal Pw, a period of length 2Tw and horizontal Pb and a period of length 1Tw and horizontal Pw follow. In the mark non-forming period, a period of length 1Tw and level Pc is placed at the beginning, and then the Pe level is maintained until the next mark forming period.

The recording waveform when a 7Tw length mark is formed is shown in Fig. 12(h). After a pulse of length 1Tw and level Pw, a period of length 1.5Tw and level Pb, a period of length 1Tw and level Pw, a period of length 1.5Tw and level Pw Period of Pb. In the mark non-forming period, a period of length 1Tw and level Pc is placed at the beginning, and then the Pe level is maintained until the next mark forming period.

Here, either one or both of the start end and the end end of the intermediate pulse are synchronized with the sub count signal. In the figure, the rise and fall of the second pulse are synchronized with the sub count signal.

Next, as shown in FIG. 12(j), when a mark of an odd multiple of the window width Tw is detected, a period of length 1Tw of mark length 2Tw, a period of horizontal Pb, length 1Tw, Period of level Pw. In the mark non-forming period, a period of length 1Tw and level Pc is placed at the beginning, and then the Pe level is maintained until the next mark forming period.

In some of the present examples, the Pe level and the Pb and Pc levels are the same power level, but the Pe level and the Pb and Pc levels may be different.

An example of adaptive marker compensation will be described below with reference to the drawings. In high-density optical recording, recording interference occurs in which the edge of a mark moves according to recording conditions. In order to prevent the deterioration of the recording signal caused by it, adaptive type mark compensation can be performed.

As shown in Fig. 8, adaptive mark compensation changes the laser irradiation start position and pulse width for 2T marks (2Tm), 3T marks (3Tm), 4T marks (4Tm), and marks over 5T (≥5Tm). compensating action.

FIG. 8 shows an example of adaptive mark compensation when the recording power is binary. According to the symbol length of the recording mark, the position of the start end of the mark in the above parameters can be moved by moving dTtop and Ttop, and the end position of the recording mark can be moved by moving Tlp and dTlp, so that the edge movement of the start end and end of the mark can be suppressed, and a good signal can be obtained. quality.

FIG. 9 shows an example of adaptive mark compensation when the recording power is quaternary. According to the symbol length of the recording mark, by moving dTtop and Ttop at the start position of the mark in the above parameters, and moving dTe at the end position of the recording mark, the edge movement of the start end and end of the mark can be suppressed, and good signal quality can be obtained. Here, the recording power has four values, but when Pb=Pc is three values, the same mark compensation can be applied.

It should be noted that the amount of shift generated by recording compensation can be shifted in units of a minute shift amount from the reference time, for example, Tw/16, using the delay line.

In addition, when recording compensation is performed, compensation may be started from a position synchronized with the count signal or from a position synchronized with the sub count signal according to the basic waveform.

Here, in the basic waveform, each pulse width, the width of the bottom power level in the mark formation period, and the width of the cooling power are 1T or more, but after the recording compensation is performed, each pulse width of each mark length is at least 0.5Tw or more. . In this case, it is less likely to be affected by the response speed of the laser, and recording conditions can be relaxed.

[comparative example]

The patterns of recording waveforms 500 to 506 of the apparatus of the comparative example will be described below with reference to FIGS. 5( a ) to ( i ).

Refer to Figure 10. FIG. 10 is a diagram showing the configuration of the recording processing system of this device.

Encoder 1013 in FIG. 10 receives record data 1027 and converts it into record symbol sequence 1026 . The mark length sorter 1001 performs division by a divisor of 2 (remainder calculation) with respect to the mark length n based on the record code sequence 1025 . The mark length classification signal 1001 identifies the mark/space of the recording symbol row when the length is an even multiple of the detection window width Tw and when the length is an odd multiple.

The counter 1000 instantiates the time from the head of the mark in units of the detection window width Tw, and generates a count signal. FIG. 5( b ) shows the count signal 1005 . The timing at which the count signal transitions to 0 corresponds to the start of a mark or a space.

A reference time signal 1028 is input to the counter 1000 and the encoder 1013 . The count signal 1005 is input to the recorded waveform table 1002 . The recorded waveform table 1002 sends a level generation signal to the laser driving circuit 1011 , and the laser driving circuit 1011 outputs a laser driving current 1024 .

Fig. 5(c) shows a recording waveform when a 2Tw length mark is formed. The mark formation period 305 is composed of pulses with a length of 1Tw and a level of Pw1. In the mark non-forming period, a period of length 1Tw and level Pb is started, and the Pa level is maintained until the next mark forming period.

Fig. 5(d) shows a recording waveform when a 3Tw length mark is formed. The mark forming period 305 is followed by a pulse of length 1Tw and level Pw1 as in FIG. 5( c ), followed by a period of length 1Tw and level Pw2 . The mark non-formation period is the same as the recording waveform shown in FIG. 5( c ), and a period of length 1Tw and level Pb is initially placed, and Pa level is maintained until the next mark formation period. The waveforms in the mark non-forming period are also the same as those shown in FIGS. 5( e ) to ( f ) below. That is, in the mark non-forming period, the Pa level is maintained until the next mark forming period after a period of length 1Tw and level Pb is initially placed, regardless of the space length. The shortest cooling period of the mark forming period 305 becomes 1Tw.

Fig. 5(e) shows a recording waveform when a 4Tw length mark is formed. The mark forming period 305 is followed by a pulse of length 1Tw and level Pw1 as in FIG. 5( c ), followed by a period of length 1Tw and level Pa and a period of length 1Tw and level Pw3 .

5(f) and (h) show recording waveforms when a mark length of 5Tw and a mark length of 7Tw are formed, respectively. When detecting a mark of an odd multiple of the window width Tw, a period of length 1Tw of a mark length of 2Tw, a period of level Pa, a period of length 1Tw, and a period of level Pw3 are added to the rear end of the mark forming portion. In the mark non-forming period, regardless of the space length, the Pa level is maintained until the next mark forming period after the initial placement length 1Tw and the level Pb.

5(g) and (i) respectively show the recording waveforms when the mark length of 6Tw and the mark length of 8Tw are formed. When detecting an even multiple length mark of the window width Tw, a period of length 1Tw of mark length 2Tw, a period of level Pa, and a period of length 1Tw and level Pw3 are added to the rear end of the mark forming portion.

In the comparative example, compared with the example of the present invention, the recording power of the recording pulse example fluctuates in steps, so complicated power control is required. In addition, when recording a mark with a mark length of 4Tw, it is necessary to cause the semiconductor laser element to emit light at a power level higher than the average power level for at least a length of 3Tw. When the recording density of the optical disk is increased and the formation of fine marks is required, in the comparative example, the irradiation time cannot be too long, so there is a disadvantage that the required mark shape cannot be obtained.

According to the present invention, in a data recording apparatus for recording data by injecting energy into a recording medium to form marks having physical properties different from those of unrecorded portions, marks can be formed at high speed and with good accuracy. Accordingly, as a recording method, it is possible to use a mark edge recording method which is advantageous for high recording linear density.

As described above, the recording/reproducing operation can be increased in speed and reliability, and the information recording device and the recording medium can be miniaturized, which is advantageous in terms of cost.

Claims (12)

1. A data recording method, by irradiating the recording medium with a pulsed energy beam, recording data as edge position information of marks and spaces of a plurality of lengths on the recording medium, and the data transmission rate is more than 72Mbps The data logging method, including: Step A of generating a record symbol column according to the data to be recorded; Step B of determining a recording waveform specifying power modulation of said energy beam according to the symbol length of each symbol in the recording symbol column; and a step C of modulating the power of the energy beam according to the recorded waveform; In the step B, when the shortest symbol length of the record symbol column is n, wherein n is an integer greater than 1, for the recording mark formation period corresponding to the symbol whose symbol length x is n, n+1, or n+2 , assigning a recording waveform with one recording pulse, and assigning a plurality of recording pulses (Pw) during the recording mark formation period corresponding to a symbol having a symbol length x of n+3 or more, In the step B, the number of recording pulses (Pw) included in the recording waveform in the recording mark formation period and the number of periods of the bottom power level (Pb) sandwiched between two recording pulses (Pw) are equal to each other. The symbol length m of the symbol length m and the symbol of the symbol length m+1, the period of any Kth bottom power level (Pb) included in the recording mark formation period of the symbol length m is assumed to be "the pulse width of the symbol length m", and the symbol length When the period of any Kth bottom power level (Pb) included in the recording mark formation period of m+1 is "the pulse width of symbol length m+1", it is determined that the recording waveform satisfies the following relationship: (pulse width of symbol length m)≦(pulse width of symbol length m+1). 2. The data recording method according to claim 1, wherein: The recording waveform in the recording mark formation period corresponding to a symbol having a symbol length x of n+3 or more includes a recording pulse equal to the quotient of dividing (x−1) by 2. 3. The data recording method according to claim 1, wherein: The period of the erasing power level (Pe) of the recording waveform in the recording mark formation period corresponding to the symbol whose symbol length x is n+3 or more is set to 1Tw or more. 4. The data recording method according to claim 1, wherein: The period of the bottom power level (Pb) of the recording mark forming period in each recording mark forming period is set to 1 Tw or more. 5. The data recording method according to claim 1, wherein: The period of the cooling power level (Pc) of the recording waveform in each recording mark forming period is set to 1 Tw or more. 6. The data recording method according to claim 1, wherein: The start position of the start pulse and the end position of the cooling pulse included in the recording waveform in the corresponding recording mark formation period are moved according to the symbol length x. 7. The data recording method according to claim 6, wherein: The shift is set to have different sizes for at least four intervals in which the symbol length x is n, n+1, n+2, n+3 or more. 8. A data recording device, by irradiating the recording medium with a pulsed energy beam, data is recorded on the recording medium as edge position information of marks and spaces of a plurality of lengths, and the data transmission rate is more than 72Mbps, Include: laser drive means for power modulation of said energy beam; encoding means for converting data to be recorded into said recording medium into a sequence of recording symbols; and determining a mark length sorting means for specifying a recording waveform of power modulation of the energy beam according to a symbol length x of each symbol included in the recording symbol sequence; The mark length sorting part, when the shortest symbol length of the record symbol column is n, wherein n is an integer greater than or equal to 1, for records corresponding to symbols whose symbol length x is n, n+1, or n+2 During the mark formation period, a recording waveform in which one recording pulse is allocated, and in the recording mark formation period corresponding to a symbol having a symbol length x of n+3 or more, a recording waveform in which a plurality of recording pulses (Pw) are allocated, The symbol lengths m and For a symbol with a symbol length m+1, it is assumed that the period of any K-th bottom power level included in the recording mark formation period of the symbol length m is "the pulse width of the symbol length m", and the recording mark formation period of the symbol length m+1 is assumed to be When the period of any Kth bottom power level contained in is "the pulse width of symbol length m+1", it is determined that the recorded waveform satisfies the following relationship: (pulse width of symbol length m)≦(pulse width of symbol length m+1). 9. The data logging device of claim 8, wherein: The recording waveform in the recording mark formation period corresponding to a symbol having a symbol length x of n+3 or more includes a recording pulse equal to the quotient of dividing (x−1) by 2. 10. The data logging device of claim 8, wherein: The recording waveform is determined such that the entire interval from the falling edge to the rising edge of the basic waveform of the laser pulse in the mark forming period is equal to or greater than the detection window width (Tw). 11. The data logging device of claim 8, wherein: A pulse shifter is provided for moving the start position of the start pulse and the end position of the cooling pulse included in the recording waveform in the corresponding recording mark formation period according to the symbol length x. 12. The data logging device of claim 11, wherein: It has recording compensation means for setting the shift to a different size in accordance with at least four intervals in which the symbol length x is n, n+1, n+2, n+3 or more.

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