JP2003281769A - Optical disc device and method for driving laser diode in the same device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To perform a recording without a setting error when recording power is different without deteriorating recording quality. SOLUTION: A CPU 16 has a recording power (a range of a light emission power of a laser diode at the time of recording, a recording speed,
D / A according to the type of recording medium or recording position)
By changing the maximum value of the set voltage of the converter and changing the parameters of the relational expression between the reference voltage and the power, the optimum power can be obtained efficiently and accurately. Even if any of the above parameters change, the setting error due to the power difference To prevent the recording quality from deteriorating.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to CD-R and CD-R.
The present invention relates to an optical disk device and a method for driving a laser diode in the optical disk device, which records and reproduces information on and from a recordable and reproducible optical disk such as RW and DVD.

[0002]

2. Description of the Related Art For recording data in an optical disk device, for example, in a CD-R, a recording film on the CD-R is irradiated with a strong laser light amount emitted from a laser diode (hereinafter referred to as LD) as a light beam. The thermal reaction
This is done by making holes (pits) in the optical disc. Further, in the CD-RW, recording is performed by changing the crystal state of the recording film.

FIG. 6 shows an example of how a laser beam is emitted during recording on a CD-R. In FIG. 6, time t
The light emission waveform before reproducing the data from the optical disc before the write start and the light emitting waveform after recording the time t when the data is recorded on the optical disc are shown from the LD, and the first power P1 and the first power are used. Higher second power P2 is repeatedly emitted. This P2 is the recording power, and a pit can be opened in the recording film when emitting light at the P2 level.
Also, P1 is the playback power, and the space at the P1 level remains as it is. In addition, a P3 level that satisfies P3> P2 may be provided to generate a recording power waveform with three values of P1, P2, and P3. The pit edge is sharpened by positioning the P3 level at the beginning of the pit. Also, CD-RW
In a phase change type rewritable medium such as the one described above, three values are originally set, and P3 and P1 are repeated at high speed to make them non-crystalline.
Crystallize by sustaining P2.

When the data on the optical disk is reproduced, the power emitted from the LD is low and the light is DC emission.
P1 is about 1 mW. On the other hand, at the time of recording, the power of the laser light emitted from the LD is high, and P2 is generally several mW to several 1
It is 0 mW. For example, in the case of recording at 12 times the speed of a CD-R (12x), the recording power may be about 30 times the reproduction power. For example, when the reproduction power is 1 mW, the recording power may be 30 mW. However, in recent years, both the reproduction speed and the recording speed are increasing, and some recording speeds are 20x and 24x, which are faster than 12x. Therefore, when recording is performed at such a speed, the reproduction power is more than 30 times.

Recently, the recording medium is DVD + RW,
Optical discs such as DVD-RW and DVD-RAM, which have a larger capacity than that of CDs, have come out. Furthermore, these optical discs are not limited to optical disc devices corresponding to the respective optical discs, but can also reproduce CD-ROMs, CD-R and C
Some products have been able to record on the D-RW with a single unit (hereinafter referred to as a combo drive). In such a combo drive, after inserting the medium into the optical disk device, it is determined whether the medium is a CD type or a DVD type, and the LD to be emitted is changed. Furthermore, when the same circuit is used for each of the CD system and the DVD system, the recording speed of the DVD is currently slower than that of the CD. Therefore, at present, the light emission power at the time of recording is significantly lower than that at the time of high speed of CD.

By the way, as the above-mentioned optical drive apparatus has become capable of high-speed recording, a model has come out in which an optical recording medium is compatible with high speed. Even if the manufacturer is the same, the media code is embedded in each of the high-speed compatible and non-compatible recording media in advance, and if there is a mechanism in the optical disk device that can detect this, which manufacturer, what kind of It is possible to judge whether it is media. In addition, although the CD-R has a constant linear density, in such a medium, it is usual to record while rotating at a constant linear velocity (hereinafter referred to as CLV: Constant Linear Velocity). In this case, since the relative speed between the recording medium and the laser beam is always constant, the recording conditions such as the recording power and the recording pulse width do not need to be changed over the entire surface once optimally determined. For this reason, normally, there is no problem in performing test writing by oscillating power in a specific area of the innermost peripheral portion and using the optimum recording power determined by the test writing to perform full-surface recording at the same linear velocity.

However, in the CLV, it is necessary to increase the rotation speed toward the inner peripheral portion, so that it becomes difficult to rotate the CLV at higher speeds. Motor cost is high,
Noise and vibration increase, and the design of other servo systems becomes difficult. Therefore, a method is adopted in which the rotation speed is not so much decreased even when going to the outer circumference, instead of increasing the rotation speed so much at the inner circumference. In this case, the linear velocity becomes higher toward the outer circumference. Completely constant rotation speed (hereinafter CA
V: Constant Angular Velocity), the linear velocity increases in proportion to the radius. Therefore, there is a method called ZCLV (: Zone CLV) in which a zone is divided at an appropriate radial position, the CLV is set in the zone, and the outer peripheral zone has a higher linear velocity.

FIG. 7 shows an example of zone division by ZCLV. In this example, 4 zones are provided according to the address written on the optical disc, and 12x, 16 from the inner circumference.
x, 20x, and 24x are made variable to suppress the rotation speed. Of course, since the recording speed changes, it becomes necessary to change the recording power according to the speed.
By the way, since the light emission power of the LD changes due to temperature rise due to its own oscillation, etc., the light emission power will change over time unless the current for driving the LD is controlled while monitoring the LD output by the light receiving element in the optical disk device or the like. It will change. Therefore, in general, an optical disk device that emits light with high power as during recording requires a circuit for controlling the light emission power of the LD to be constant.

FIG. 8 shows an example of a circuit configuration for controlling the emission power at a constant power. This constant power control (hereinafter APC: Automa
tic Power Control) is performed by digital control. In FIG. 8, the light incident on the PD 81 is output in the form of a current proportional to the amount of light by photoelectric conversion.
However, since the PD 81 monitors a part of the laser light from the LD 82, most of the laser light is applied to the recording film of the optical disc. Next, the current output from the PD 81 is converted into a voltage by the I / V (current / voltage) converter 83 and output as a voltage value. In this output voltage, the one corresponding to P1 is V (P1) and the one corresponding to P2 is V (P2). Since the output during recording is a signal in which V (P1) and V (P2) change alternately unlike during playback, the sample hold (S / H) circuits 84 and 85 allow V (P
1) and V (P2) are separated. Also, the S / H circuit 1 (84)
The sample signal 1 at is always the S / H circuit 1 during reproduction.
This is a signal to turn on the SW in (84).
The SW in the S / H circuit 1 (84) is turned ON only during the period when P1 is emitted or a shorter period, and the SW in the S / H circuit 1 (84) is turned on during the period when P2 is emitted. OFF, S
/ V voltage corresponding to P1 with the capacitor in H circuit 1 (84)
It is controlled so that only s (P1) is taken out.

On the other hand, the sample signal 2 is always S during reproduction.
This is a signal that turns off the SW in the / H circuit 2 (85). During recording, the SW in the S / H circuit 2 (85) is turned on only during the period of emission at P2 or for a period shorter than that. Sometimes the SW in the S / H circuit 2 (85) is turned off during the period of emission at P1.
The signal in the S / H circuit 2 (85) controls so that only the voltage Vs (P2) corresponding to P2 is taken out by the capacitor. Next, S / H circuit 1 (84) and S / H circuit 2 (8
Each of Vs (P1) and Vs (P2) separated from the output voltage of the I / V converter 83 by 5) is compared by the comparator 1 (86).
And to the comparator 2 (87). The comparator 1 (86) compares Vs (P1) with the reference voltage 1 (hereinafter referred to as Vref1), and similarly, the comparator 2 (87) uses Vs (P1)
(P2) is compared with reference voltage 2 (hereinafter referred to as Vref2).
From the comparators 86 and 87, a signal indicating only whether the input signal is larger or smaller than the reference voltage, that is, a binary value (digital value) is output and read by the CPU 88. Further, data is sent from the CPU 88 to the D / A converter 1 (89) that converts a digital value into an analog value, and the D / A converter 1 (89) outputs a voltage proportional to the input data.

Further, the V / I converter 1 (91) outputs a current having a value proportional to this output. Similarly D / A
Data is also sent from the CPU 88 to the converter 2 (90), and current is also output from the V / I converter 2 (92). Further, the output currents of the respective V / I converters 91 and 92 are amplified by the current amplifier 1 (93) or the current amplifier 2 (94). At the time of reproduction, the LDON signal is turned on to turn on the current amplifier 1 ( The output of 93) flows into the LD 82 and is emitted from the LD 82 as P1. Further, at the time of recording, since the write pulse superposition signal is turned on, the output of the current amplifier 2 (94) is added to the output current from the current amplifier 1 (93) by the current adder 95 and flows to the LD 82. The LD 82 emits light as P2.

By the way, at the start of reproduction, the CPU 88
First, "0" is output to the D / A converters 89 and 90.
As a result, the current corresponding to the recording power of the LD 82 starts from "0". Then, the CPU 88 causes the D
The data output to the A / A converters 89 and 90 is gradually increased until the outputs of the comparators 86 and 87 are inverted (that is, until Vs (P1) becomes larger than Vref1). After that, the data output to the D / A converters 89 and 90 is always variable so that the outputs of the comparators 86 and 87 are repeatedly inverted (that is, Vs (P1) = Vref1). As a result, the reproduction power emitted from the LD 82 is maintained at a constant level. This state is shown in FIG. Further, similarly, FIG. 10 shows a state from the start of recording until the recording power level is kept constant.

In FIG. 10, the CPU 88 controls the D
The output of the / A converter 2 (90) is set to "0".
Next, when the recording light emission is started, the CPU 88 causes the D / A
The data to be output to the converter 2 (90) is increased by one or by a predetermined number. Along with this, a current proportional to the output voltage of the D / A converter 2 (90) is superimposed on the current proportional to the output voltage of the D / A converter 1 (89) as a recording power current in the LD 82. The output voltage of the S / H circuit 84 which is monitored and sampled and held is also increased by a predetermined amount. Then, when the output voltage of the S / H circuit 84 exceeds Vref2, the comparator 2 (8
The output of 7) is inverted. When it is inverted, the CPU 88 causes the data moved in the opposite direction to the previous one to be transferred to the D / A converter 2
(90). As a result, the current of the LD 82 decreases and the comparator 87 inverts. When flipped,
The CPU 88 permanently operates in the opposite direction (repeating above), so that the CPU 88 permanently operates the D / A converter 8
9 and 90 are operated so that the output voltage of the S / H circuit 2 (85) and Vref2 always cross each other. This makes LD
A constant P2 is emitted from 82.

With the feedback loop constructed as described above, the LD having a constant power determined by the reference voltage is
Light is emitted from 82. The comparator 8
The relationship between the reference voltages of 6, 87 and P1 or P2 is obtained in advance in the manufacturing process or the like, for example, in the form of a relational expression. This configuration includes the CPU 88 and the D / A converter 8
This is so-called digital control using 9, 90 and the like.
However, the constant power control is not limited to such digital control, and the signals from the S / H circuits 84 and 85 are input to an error amplifier or the like and compared with a reference voltage by the error amplifier or the like, and there is a deviation from the reference voltage. The power can also be controlled by outputting to the V / I converter a voltage for correcting the deviation when the error amplifier is generated. As described above, the same operation is performed in both analog control and digital control in that the LD emission power is monitored, the levels such as P1 and P2 are compared with the reference voltage, and the drive current to the LD 82 is controlled to become the reference voltage. .

By the way, FIG. 11 shows an example of laser drive current vs. emission power characteristics. As can be seen from this figure, the emission power from the LD 82 and the LD drive current are based on a certain threshold value (hereinafter referred to as Ith). Above is a linear function. Also, the LD drive current is the D / A converter 8
Since there is a linear function relationship with the output voltage of 9, 90,
There is a linear function relationship between the set voltage values of the D / A converters 89 and 90 for setting the LD drive current and the light emission power.
It can also be represented by a certain slope and intercept. As described above, the relationship between the reference voltage and the power obtained in the manufacturing process is stored in a memory or the like with the slope or intercept, and is used for power control or the like during actual recording. in this way,
Controlling the light emission power from the LD 82 to be constant is called APC (Auto Power Control). In addition, in FIG.
The APC section 80 includes up to the CPU 88 that controls the voltage to the / I converters 91 and 92. 90 is an LD drive unit.

By the way, when it is desired to change the power emitted from the LD 82, this can be realized by changing the reference voltage, and the setting error in setting the reference voltage is determined by the D / A converters 89 and 90. D / A
If the specifications of the D / A converters 89 and 90 are 8 bits, the voltage that can be set by the converters 89 and 90 can be divided into 2 ⁸ = 256 with respect to the settable voltage width. If there is, it can be divided into 2 ¹⁰ = 1024. Here, the maximum voltage setting value corresponds to the maximum value of the voltage width. Therefore, the larger the number of bits, the finer the resolution becomes. However, the larger the number of bits, the higher the cost becomes. Therefore, there is a possibility that the D / A converters 89 and 90 having a coarse resolution must be used. .

[0017]

By the way, as described above, since it has become possible to record at high speed in recent years, it is necessary to emit light with high power. However, even though the recording speed that can be set with the recording speed of the optical disk device is high, there are users who think that the recording speed is better at low speed, especially when recording with audio etc. Some people try to record. However, when the recording power is high during the actual recording operation, the D / A converter 89,
Since the value of Vref2 set to 90 becomes large, the error of P2 with respect to the set Vref2 becomes small, but when the recording power is particularly lower than the maximum power, the resolutions of the D / A converters 89 and 90 are the same. The error of P2 with respect to the set Vref2 becomes large. That is, it means that the light emission becomes rough.

For example, if the recording power is set to 10 mW when the maximum power is 50 mW,
The error is 5 times as much as when the light is emitted at 50 mW. If the light emission power becomes coarse, it means that the recording quality deteriorates. Therefore, at low power, the recording quality deteriorates. As mentioned above, when the recording speed was low and the maximum emission power was not high as before, there was almost no setting error, and there was no problem that the emission power became rough due to the difference in emission power. It is expected that such issues will increase.

As a conventional technique for solving the above-mentioned problems, there is a technique disclosed in Japanese Patent Laid-Open No. 9-116220. According to this technique, the output gain of the I / V converter is changed during recording and during reproduction. However, this does not have a great influence if the recording power is only low power, but there is a problem that the recording quality is deteriorated when the recording optical disk device may perform low power recording even with high power.

Further, in Japanese Patent Laid-Open No. 2000-20955, in order to accurately set the recording power, the output of the PD when the reflected light from the optical disk is received by the PD is amplified by the head amplifier and amplified. The peak value of the signal is read by the drive controller, compared with a target value suitable for binarizing the detection signal, and the gain of the variable gain amplifier is adjusted to stably binarize in the analog signal processing circuit. It can be processed. Then, there is disclosed a technique in which a recording power calculation circuit determines a test write power for test writing in a test track and calculates a recording power of an optical disk based on the test power under the control of a drive controller.

According to the disclosed technique, the recording power can be set with high accuracy by the information from the reproduced signal. However, the accuracy at the time of actual recording is
When setting with the A converter, a setting error occurs due to the resolution, and in particular, when the resolution is coarse, it differs between high power and low power, and there remains a problem that the power decreases particularly at low power. The present invention has been made in view of the above circumstances, and it is possible to perform recording without loss of setting error and deterioration of recording quality when the powers at the time of recording are different,
An object of the present invention is to provide an optical disk device and a method for driving a laser diode in the device.

[0022]

In order to solve the above-mentioned problems, the invention as set forth in claim 1 monitors the light emission power of a light emitting diode and adjusts the light amount level by comparing with a reference voltage to make it constant. An optical disk device for controlling a drive current so as to obtain a light emission power of 1., a current-voltage conversion means for adjusting the light amount level and converting a current signal for driving the laser diode into a voltage signal, and the current-voltage conversion means. Current amplification means for amplifying the current signal output from the, and the light amplification level is adjusted by the current amplification means,
Control means for changing the set maximum value of the voltage signal supplied to the laser diode.

According to the first aspect of the present invention, the control means adjusts the light amount level by the current amplifying means and changes the set maximum value of the voltage signal supplied to the laser diode so that the recording power can be adjusted. By changing the maximum value of the set voltage by changing the parameter of the relational expression between the reference voltage and the power, a setting error due to the difference in power is eliminated, and it is possible to provide an optical disc device that prevents deterioration of recording quality. it can.

According to a second aspect of the present invention, in the optical disk device according to the first aspect, the control means switches the set maximum value according to the range of the emission power of the laser diode at the time of recording, and further, the current The parameter representing the relationship between the reference voltage to be compared with the voltage signal from the voltage converting means and the light emission power is reset according to the maximum value of the adjustment values.

According to the second aspect of the invention, the control means changes the maximum value of the set voltage of the D / A converter, for example, according to the range of the emission power of the laser diode at the time of recording, and further, the reference voltage and the power. By changing the parameters of the relational expression of, the optimum power can be obtained accurately.

According to a third aspect of the present invention, in the optical disk device according to the first aspect, the control means switches the set maximum value according to a recording speed, and further compares it with the voltage signal from the current-voltage conversion means. The parameter representing the relationship between the reference voltage and the light emission power is reset according to the maximum value of the adjustment values.

According to the third aspect of the present invention, the control means changes, for example, the maximum value of the set voltage of the D / A converter according to the recording speed, and further changes the parameter of the relational expression of the reference voltage and the power. Thus, the optimum power can be obtained with high accuracy, and the deterioration of the recording quality during recording can be prevented.

According to a fourth aspect of the present invention, in the optical disk device according to the first aspect, the control means switches the set maximum value according to a recording medium, and further compares it with a voltage signal from the current-voltage conversion means. The parameter representing the relationship between the reference voltage and the light emission power is reset according to the maximum value of the adjustment values.

According to the invention described in claim 4, the control means changes, for example, the maximum value of the set voltage of the D / A converter according to the type of the recording medium, and further the parameters of the relational expression of the reference voltage and the power. By changing it, the optimum power can be accurately obtained.

According to a fifth aspect of the present invention, in the optical disc apparatus according to the first aspect, the control device switches the set maximum value according to a recording position on a recording medium,
Further, the parameter representing the relationship between the reference voltage to be compared with the voltage signal from the current-voltage converting means and the light emission power is reset according to the maximum value of the adjustment value.

According to the invention of claim 5, the control means changes the maximum value of the set voltage of the D / A converter in accordance with the recording position, and further changes the parameter of the relational expression of the reference voltage and the power. Thus, it is possible to provide an optical disk device capable of preventing the setting error due to the difference in power from being lost even when the recording speed during recording is changed and the recording quality from being deteriorated.

According to a sixth aspect of the present invention, a laser diode drive in an optical disk apparatus for driving the laser diode by detecting the emission power of the laser light output from the laser diode and adjusting the light amount level of the emission power. A method for adjusting the light quantity level, converting a current signal for driving the laser diode into a voltage signal, amplifying a current signal output from the current-voltage converting means, and adjusting the light quantity level by the current amplifying means. It adjusts and changes the setting maximum value of the voltage signal supplied to the said laser diode, It is characterized by the above-mentioned.

According to the sixth aspect of the present invention, by changing the set maximum value of the voltage signal supplied to the laser diode, the maximum value of the set voltage is changed according to the recording power, and the reference voltage is further changed. By changing the parameter of the relational expression of the power and the power, it is possible to prevent the setting error due to the difference in the power from disappearing and the deterioration of the recording quality.

[0034]

1 is a block diagram showing the internal structure of an optical disk device according to the present invention. here,
A CD-R drive for recording and reproducing is illustrated as an optical disc device. In a CD (Compact Disc), a data string is represented on a disc substrate by the presence or absence of holes called pits, laser light is applied to this, and data is read by the change in reflected light. This data string is arranged spirally on the disk substrate like a record. This spirally arranged line is called a track. The distance between adjacent tracks is 1.
6 microns. Now, the optical disc 1 (CD-ROM
And a CD-R disc) are rotationally driven by the spindle motor 2. The spindle motor 2 is controlled by the motor driver 3 and the servo circuit 4 so as to have a constant speed.

The optical pickup unit 5 includes a laser diode (not shown), an optical system (lens, etc.), a focus actuator (a mechanism for moving the lens position in the direction perpendicular to the disc so that the laser beam is focused on the disc), and a track actuator ( The optical disc 1 is irradiated with a laser beam by a mechanism that moves a lens in the radial direction (sledge direction) of the disc so that the focus of the laser beam traces a track, a light receiving element, a position sensor, and the like. The entire optical pickup unit 5 can be moved in the sledge direction by a seek motor (not shown). The focus actuator, the track actuator, and the seek motor are controlled by the motor driver 3 and the servo circuit 4 based on the signals obtained from the light receiving element and the position sensor so that the laser spot is located at a desired position.

In the case of data reading, the reproduction signal obtained by the optical pickup section 5 is amplified by the read amplifier 6, equalized and binarized, and then input to the CD decoder 7 and subjected to EFM (Eight to Fourteen Modulation). It
Data obtained by modulating 8-bit data into 14-bit data is written on the optical disc 1 for easy optical reproduction or recording. The EFM demodulated data is subjected to deinterleaving (reordering) and error correction. After that, this data is temporarily stored in the buffer RAM 9 by the buffer manager 8 and, at the stage when it is prepared as sector data, ATAPI (At Attachment Attachment Packet)
・ Interface) and SCSI (Small ・ Computer ・ System ・ Inte
It is sent to a host computer (not shown) at a time via an interface 10 (I / F) such as rface). In the case of music data, the data output from the CD decoder 7 is
It is input to the D / A converter and an analog audio signal is taken out.

At the time of writing data, ATAPI and SCS
The data sent from the host computer via the I interface 10 is temporarily stored in the buffer RAM 9 by the buffer manager 8 and the writing is started when the data has been stored in the buffer RAM 9 to some extent, but the laser spot writing is started before that. Must be located at the point. This point is obtained from the wobble signal that has been previously engraved on the optical disk due to the meandering of the track. The wobble signal includes absolute time information called ATIP, and the ATIP decoder 12
This information can be retrieved by. Further, the sync signal generated by the ATIP decoder 12 is input to the CD encoder 13 to enable writing of data at an accurate position.

The data stored in the buffer RAM 9 is
After the error correction code is added or interleaved by the CD-ROM encoder 14 or the CD encoder 13, E
It is FM-modulated and recorded on the optical disc 1 via the laser controller 15 and the optical pickup unit 5. 1
Reference numeral 6 denotes a CPU, which controls each of the above blocks using the RAM 18 in accordance with a program recorded in advance in the ROM 17. The details will be described with reference to the flowcharts shown below.

Now, the light emission waveform of the laser driver (LD) will be described. The control signal of each switch, that is,
The sample signal 1, the sample signal 2, and the write pulse superimposed signal shown in FIG. 8 are signals output by the CD encoder 13 shown in FIG. An embodiment of the present invention will be described with reference to the flowchart shown in FIG. The contents described here are realized in the same form as the configuration shown in FIG. 8, but with the D / A converter 1 (89),
The D / A converter 2 (90) can change the maximum value of the voltage that can be set, and the CPU 88 sets the maximum value. Also, D
The A / A converters 89 and 90 are predetermined according to specifications such as 100 LSB and 500 LSB, and the larger the value, the finer the resolution.

In FIG. 8, first, the D / A converter 8
The maximum setting voltage of 9, 90 is set to the maximum (S20
1). Further, the relational expression between the reference voltage and the power is obtained in the manufacturing process (S202). At this time, the maximum value of the set voltage is the largest value. Next, the optimum power is obtained during recording (S203). Here, a power threshold value (hereinafter referred to as Pth) is set as a condition for changing the maximum value of the set voltage. Then, the optimum power is compared with the power threshold (S
204), the CPU 16 does not change the set voltage maximum value when the optimum power is Pth or more, and changes the set voltage maximum value when the optimum power is smaller than Pth (S205). Then, when the maximum value of the set voltage is changed, the parameter expressing the relational expression of the reference voltage and the power which is obtained in advance is also changed (S20).
6). In this state, a desired reference voltage is set and recording is started (S207). After the recording is started, the power is controlled by the APC control, but the output of the D / A converters 89 and 90, that is, the LD drive current value changes depending on the characteristics of the LD, but the maximum set voltage, the reference voltage, and the power. D / A converters 89, 90 by changing the parameters of the relational expression
Since there is no setting error of, the recording can be performed without degrading the recording quality.

Next, another embodiment of the present invention will be described with reference to the flowchart shown in FIG. Here, as in FIG. 2, the maximum set voltage value of the D / A converters 89 and 90 is maximized (S301). Further, the relational expression between the reference voltage and the power is obtained in the manufacturing process (S30
2). At this time, the maximum value of the set voltage is the largest value. By the way, when the user performs recording, the recording speed is selected immediately before the recording, the recording is started after the selection is made, and the actual recording is started by obtaining the optimum power. here,
Change the maximum value of the set voltage according to the recording speed.

For example, a speed threshold value (hereinafter referred to as Sth) is set such that the maximum value of the set voltage remains unchanged at 12x or more and the maximum value of the set voltage is changed when the value is lower than 12x. Next, when the maximum value of the set voltage is changed, the parameter expressing the relational expression of the reference voltage and the power which is obtained in advance is also changed. After this, recording starts and the optimum power is obtained. That is, the set speed and the speed threshold value are compared (S303), and when the set speed becomes larger than the speed threshold value, a desired reference voltage is set (S30).
6) If not, change the maximum value of the set voltage (S30
4) The parameter of the relation between the reference voltage and the power, which is obtained in the manufacturing process, is changed (S305). As described above, when the optimum power is obtained, the maximum value of the set voltage is already changed, and the parameters of the relational expression of the reference voltage and the power are changed to change the D / A
The setting error of converters 89 and 90 is eliminated. Therefore,
The optimum power can be obtained more accurately.

In the above-described embodiment, the set maximum value of the voltage signal for driving the LD (hereinafter referred to as the voltage set maximum value) is changed according to the set power. For example, when the power is low, the voltage setting maximum value is lowered. By doing so, the difference in resolution due to power can be eliminated, and the setting error can be reduced. However, even if the resolution can be made fine, if the voltage values of the D / A converters 89 and 90 are low, the power controlled by the APC will naturally remain low. By the way, as described above, the emission power and D /
The output voltages of the A converters 89 and 90 have a linear function relationship. Therefore, when the voltage setting maximum value is changed, it is necessary to change the relationship between the reference voltage and the power.
Therefore, when changing the maximum voltage setting value, the value of the relational expression between the power and the reference voltage is changed according to a certain calculation rule. In this calculation rule, the slope in the relational expression of the linear function that has been obtained in advance may be constant division, the intercept in the relational expression of the linear function may be constant subtraction, or a more complicated expression may be used.

By changing the voltage setting maximum value according to the power thus set and further changing the relational expression between the power and the reference voltage, it is possible to emit light with a desired power and further reduce the setting error. This makes it possible to prevent the recording power from becoming rough and prevent the recording quality from deteriorating. In addition, the required power changes during high speed recording and during low speed recording. So do you need the power of how much in advance if it is the speed set guideline is examined at the design stage of the optical disk apparatus. Therefore, in the embodiment shown in FIG. 3, by changing the voltage setting maximum value according to the set speed and further changing the relational expression between the power and the reference voltage, it is possible to emit light with a desired power and further reduce the setting error. It is possible to reduce the recording power, so that the recording power has no roughness and it is possible to prevent the deterioration of the recording quality.

Next, still another embodiment of the present invention will be described with reference to the flowchart shown in FIG. Here, as in the embodiment shown in FIGS. 2 and 3, the relational expression between the reference voltage and the power is obtained in the manufacturing process (S
402). At this time, the maximum value of the set voltage is set to the largest value (S401). Next, the user inserts an optical disc into the optical disc device (S403). After the optical disc is loaded, the optical disc device recognizes the optical disc (S404). For example, when the type code of the medium is embedded in the optical disc, the determination is made by reading the type code. Here, the CPU 16 determines that the medium does not support high speed (S405), the maximum set voltage is changed when it is determined that the medium does not support high speed (S406), and the parameter indicating the relational expression between the reference voltage and the power is also set. Change (S407). Further, it is notified that the recording quality may be deteriorated when the user writes at high speed, and the recording speed is not set at high speed. Then, a desired reference voltage is set and recording is started (S408).

By controlling in this way, the optimum power can be obtained with high accuracy, and the recording quality during recording can be prevented from being degraded. However, since some users want to perform high-speed recording even if the recording quality is degraded, use a medium that does not support high-speed so that the above notification can be made, but the high-speed side can also be selected. When the side is selected, the maximum value of the set voltage may be restored, and the relationship between the reference voltage and the power may be restored. Meanwhile, in the case of a CD, there are high-speed compatible optical disks and high-speed non-compatible optical disks in which the sensitivity of the recording film of the optical disk is different for high-speed compatibility. Since old optical discs are not originally compatible with high speed, it is necessary to avoid recording with high power. Also, the smaller the setting error is, the better the optimum power is obtained during recording. Therefore, according to the above-described embodiment, the setting error can be reduced by changing the maximum voltage setting value according to the type of the optical disk and further changing the relational expression between the power and the reference voltage. Can be prevented and deterioration of recording quality can be prevented.

Next, still another embodiment of the present invention will be described with reference to the flowchart shown in FIG. Here, as in FIGS. 2 to 4, the maximum value of the set voltage of the D / A converters 89 and 90 is maximized (S501). Further, the relational expression between the reference voltage and the power is obtained in the manufacturing process (S502). At this time, the maximum value of the set voltage is the largest value. By the way, as described above with reference to FIG. 7, when ZCLV control is performed, the zone in which the recording speed changes changes in advance depending on the address. For example, in FIG. 7, it is assumed that the set maximum value and the parameters of the relational expression of the reference voltage and the power are changed at 12x. Although the state was changed at the start of recording, it should be restored from 16x. However, the speed is changed by the address information being read from the optical disk by the optical disk device during recording. Therefore, the set maximum value and the parameters of the relational expression of the reference voltage and the power are restored to the original values depending on the address position where the speed similarly changes. That is, CPU1
6 changes the maximum value of the set voltage and changes the parameter of the relationship between the reference voltage and the power to start recording (S5
03 to S505), while recording while recognizing the address here (S506). Then, it is detected that the address has changed the recording speed (S507), and the parameter of the relationship between the reference voltage and the power is changed (S508).

By controlling in this way, even if the recording speed changes during recording, the setting error of the D / A converters 89 and 90 is eliminated, and recording can be performed without degrading the recording quality. By setting conditions that change the maximum set voltage value, that is, by changing the recording power, recording speed, and recording position in various cases, the resolution can be set finely and without further deterioration of recording quality. You can record. As described above, when the speed is changed during recording like ZCLV, the recording power also needs to be changed. Therefore, here, even during recording, by changing the voltage setting maximum value according to the power change and further changing the relational expression between the power and the reference voltage, it is possible to reduce the setting error, and the recording power is reduced in roughness. It is possible to prevent deterioration of recording quality.

As described above, according to the present invention, the set maximum value of the voltage signal for driving the laser diode (hereinafter referred to as the voltage set maximum value) is changed according to the set power. For example, when the power is low, the voltage setting maximum value is lowered. By controlling in this way, it is possible to eliminate the difference in resolution due to power and reduce the setting error. However, as described above, even if the resolution can be made fine, if the voltage values of the D / A converters 89 and 90 are low, A
The power controlled by the PC will of course remain low. As described above, the light emission power and the output voltages of the D / A converters 89 and 90 have a linear function relationship. Therefore, when the voltage setting maximum value is changed, it is necessary to change the relationship between the reference voltage and the power. Therefore, when changing the maximum voltage setting value, the value of the relational expression between the power and the reference voltage is changed according to a certain calculation rule. In this calculation rule, the slope in the relational expression of the linear function that is obtained in advance may be constant division, the intercept in the relational expression of the linear function may be constant subtraction, or a more complicated expression may be used. By changing the voltage setting maximum value according to the power thus set and further changing the relational expression between the power and the reference voltage, it is possible to emit light with a desired power and further reduce the setting error. Since the recording power has no roughness, it is possible to prevent the deterioration of recording quality.

Further, the required power changes during high speed recording and during low speed recording. So do you need the power of how much in advance if it is the speed set guideline is examined at the design stage of the optical disk apparatus. Therefore, according to the present invention, by changing the voltage setting maximum value according to the set speed and further changing the relational expression between the power and the reference voltage, it is possible to emit light with a desired power and reduce the setting error. It is possible to prevent the recording power from becoming rough and prevent the deterioration of the recording quality. Taking a CD as an example, there is a high-speed compatible optical disk and a high-speed non-compatible optical disk in which the sensitivity of the recording film of the optical disk is different for high-speed compatibility. Since old optical discs are not originally compatible with high speed, it is necessary to avoid recording with high power. Also, the smaller the setting error is when the optimum power is obtained during recording, the better. Therefore, according to the present invention, by changing the voltage setting maximum value according to the type of the optical disk and further changing the relational expression between the power and the reference voltage, it is possible to reduce the setting error and eliminate the roughness of the recording power. It is possible to prevent deterioration of recording quality.

Further, in the case of changing the speed during recording like ZCLV, it is necessary to change the recording power. Therefore, according to the present invention, the setting error can be reduced by changing the maximum voltage setting value according to the power change even during recording, and further by changing the relational expression between the power and the reference voltage. It is possible to prevent deterioration of recording quality.

[0052]

According to the first aspect of the present invention, the maximum value of the set voltage of the D / A converter is changed according to the recording power, and the parameter of the relational expression of the reference voltage and the power is changed to change the power. It is possible to provide an optical disk device that eliminates the setting error due to the difference and can prevent the deterioration of the recording quality.

According to the second aspect of the invention, D is set in accordance with the range of the emission power of the laser diode at the time of recording.
By changing the maximum value of the set voltage of the / A converter and further changing the parameter of the relational expression between the reference voltage and the power, it is possible to provide an optical disk device capable of accurately obtaining the optimum power.

According to the third aspect of the invention, the optimum power is changed by changing the maximum value of the set voltage of the D / A converter according to the recording speed and changing the parameters of the relational expression of the reference voltage and the power. It is possible to obtain the value with high accuracy, and it is possible to prevent deterioration of the recording quality during recording.

According to the fourth aspect of the present invention, the maximum value of the set voltage of the D / A converter is changed according to the type of the recording medium, and the parameter of the relational expression of the reference voltage and the power is also changed, which is optimum. Power can be obtained with high accuracy.

According to the fifth aspect of the present invention, the maximum value of the set voltage of the D / A converter is changed according to the recording position, and the parameter of the relational expression of the reference voltage and the power is changed, so that the recording is being performed. It is possible to provide an optical disk device capable of preventing a setting error due to a difference in power even when the recording speed changes and preventing the recording quality from deteriorating.

According to the invention described in claim 6, by changing the set maximum value of the voltage signal supplied to the laser diode, the maximum value of the set voltage is changed according to the recording power, and further, the reference voltage is changed. By changing the parameter of the relational expression of the power and the power, it is possible to prevent the setting error due to the difference in the power from disappearing and the deterioration of the recording quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing an internal configuration of an optical disk device according to the present invention.

FIG. 2 is a flowchart showing the operation of one embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of another embodiment of the present invention.

FIG. 4 is a flowchart showing an operation of still another embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of still another embodiment of the present invention.

FIG. 6 is a diagram cited for explaining a state of laser light emitted from an LD in a CD-R drive.

FIG. 7 is a diagram cited for explaining zone division in ZCLV.

FIG. 8 is a block diagram showing an internal configuration of a conventional digital APC circuit.

9 is a diagram cited to explain a relationship between a sample hold 1 output and a comparator 1 during control by digital APC control in FIG. 8. FIG.

FIG. 10 is a diagram cited for explaining the relationship between the sample hold 2 output and the comparator 2 during the control by the digital APC control in FIG.

FIG. 11 is a diagram quoted to explain a laser current vs. power characteristic.

[Explanation of symbols]

1 optical disc 16 (88) CPU 17 ROM 18 RAM 81 PD 82 LD 83 I / V converter 84 (85) S / H circuit 86 (87) Comparator 89 (90) D / A converter 91 (92) V / I converter 93 (94) Current amplifier 95 Current adder

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5D090 AA01 BB03 BB04 CC01 CC16                       CC18 DD03 EE01 HH01 JJ12                       KK04 KK20                 5D119 AA23 BA01 BB02 BB03 DA01                       HA03 HA19 HA21 HA27 HA45                       HA47 HA60 HA68                 5D789 AA23 BA01 BB02 BB03 DA01                       HA03 HA19 HA21 HA27 HA45                       HA47 HA60 HA68

Claims (6)

[Claims] 1. A method for monitoring the light emission power of a light emitting diode,
An optical disk device for controlling a drive current so as to obtain a constant light emission power by comparing the light amount level with a reference voltage, and a current for converting a current signal generated based on the issuing power into a voltage signal. Voltage converting means, current amplifying means for amplifying the current signal output from the current-voltage converting means, and adjusting the light amount level by the current amplifying means to change the set maximum value of the voltage signal supplied to the laser diode. An optical disk device comprising: 2. The control means switches the set maximum value according to the range of the emission power of the laser diode at the time of recording, and further, the reference voltage and the emission power to be compared with the voltage signal from the current-voltage conversion means. The optical disk device according to claim 1, wherein the parameter representing the relationship is reset according to the maximum value of the adjustment values. 3. The control unit switches the set maximum value according to a recording speed, and further sets a parameter representing a relationship between a reference voltage to be compared with a voltage signal from the current-voltage conversion unit and the emission power to the adjustment value. The optical disc device according to claim 1, wherein the optical disc device is reset according to the maximum value of. 4. The control unit switches the set maximum value depending on a recording medium, and further sets a parameter representing a relationship between a reference voltage to be compared with a voltage signal from the current-voltage conversion unit and the emission power to the adjustment value. The optical disc device according to claim 1, wherein the optical disc device is reset according to the maximum value of. 5. The set maximum value is switched according to the recording position on the recording medium, and a parameter representing the relationship between the reference voltage to be compared with the voltage signal from the current-voltage converting means and the emission power is set to the maximum of the adjustment value. The optical disc device according to claim 1, wherein the optical disc device is reset according to a value. 6. The light emission power of the light emitting diode is monitored,
A method of driving a laser diode in an optical disc device, wherein the drive current is controlled by comparing the light amount level with a reference voltage so that a constant light emission power is obtained, wherein the laser diode is adjusted by adjusting the light amount level. The current signal to be driven is converted into a voltage signal, the current signal output from the current-voltage conversion means is amplified, the light intensity level is adjusted by the current amplification means, and the set maximum value of the voltage signal supplied to the laser diode is adjusted. A method for driving a laser diode in an optical disk device, the method comprising: