JP2003109240A - Optical disk drive - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide an optical disk device that can automatically control actual read power, write power, and erase power to desired values. A target value of read power at each write power level such that a read power error when a laser diode emits a pulse with a plurality of different write powers is the same as a read power error when a DC light is emitted. And the target value of the write power at the time of pulse emission at each write power level is acquired so that the error of the write power at the time of pulse emission becomes the same as the error of the write power at the time of DC emission. A relational expression of the target value of the write power and the target value of the read power for each of the actual write power and the read power at the time is created, and the relation between the desired read power and the write power is referred to for the actual recording. By obtaining the target power and target write power, the actual read power -It is possible to automatically control the write power to a desired value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device, and more particularly to an optical disk device for recording a recordable optical disk.

[0002]

2. Description of the Related Art In an optical disk device, the light intensity (power) of laser light is detected by a front monitor, and APC (automatic power control) is performed so that the power of laser light reaches a desired value.

FIG. 1 is a circuit diagram showing an example of a conventional laser power control circuit for performing an APC operation. In the figure, a part of the laser light output from the laser diode 10 is applied to the front monitor (photodiode) 12. The front monitor 12 supplies a detection current according to the light intensity of the laser light. An I / V conversion circuit composed of the operational amplifier 14 and the resistor Rf converts the detected current into a voltage. This voltage is amplified by the amplifier 16, for example, ten times, and then sampled and held by the sample hold circuit 18 at the read power timing by the read power sample pulse. After that, the level shift circuit 20 inverts the polarity and doubles the amplitude, and the differential amplifier including the operational amplifier 22 differentially amplifies the target read power supplied from the D / A converter 24. A digital value of the target read power is supplied from the MPU (not shown) to the D / A converter 24, and the operational amplifier 22 obtains the error voltage Vgr of the detected read power with respect to the target read power and supplies it to the laser driver 26.

On the other hand, the voltage output from the I / V conversion circuit is sampled and held by the sample hold circuit 28 at the write power timing by the write power sample pulse. After that, the polarity is inverted and the amplitude is doubled in the level shift circuit 30, and differential amplification is performed with the target write power supplied from the D / A converter 34 in the differential amplifier configured by the operational amplifier 32. A digital value of the target write power is supplied from the MPU (not shown) to the D / A converter 34, and the operational amplifier 32 obtains the error voltage Vgw of the detected write power with respect to the target write power and supplies it to the laser driver 26.

A laser generation pulse as a recording signal is supplied to the laser driver 26, and the laser diode 10 is driven by each of the error voltages Vgr and Vgw according to the laser generation pulse. Laser beam read power,
The respective write powers are feedback-controlled, that is, APC controlled so as to have the target read power and the target write power.

[0006]

Recordable optical disks capable of recording data include write-once optical disks such as CD-R and DVD-R, and rewritable optical disks such as DVD-RW.

Of these, the EFM modulation signal recorded on the CD-R has the waveform shown in FIG. 2A. The voltage obtained by I / V converting the output of the front monitor 12 is the front monitor 1.
2 and the frequency characteristic of the I / V conversion circuit, FIG.
It becomes as shown in. For this reason, when high-speed recording is performed, there is a problem in that accurate read power and write power cannot be detected due to a delay in response of the front monitor 12 and the I / V conversion circuit.

Further, in the DVD-R, pulse train type recording is performed, and the recording waveform is as shown in FIG. 3A, but the voltage obtained by I / V converting the output of the front monitor 12 is the same as above. The voltage obtained by I / V converting the output of the front monitor 12 becomes as shown in FIG.
For this reason, when high-speed recording is performed, there is a problem in that accurate read power and write power cannot be detected due to a delay in response of the front monitor 12 and the I / V conversion circuit.

Further, in the DVD-RW, pulse train type recording is performed, and the recording waveform is changed in two values of write power and erase power with reference to read power, as shown in FIG. In this case as well, the voltage obtained by I / V converting the front monitor output becomes blunt as in the above case. For this reason, when high-speed recording is performed, there is a problem in that accurate read power and write power cannot be detected due to a delay in response of the front monitor and the I / V conversion circuit.

The present invention has been made in view of the above points, and automatically controls the actual read power, write power, and erase power to desired values regardless of the delay in the response of the front monitor and the I / V conversion circuit. It is an object of the present invention to provide an optical disc device that can be used.

[0011]

According to a first aspect of the invention, recording is performed on an optical disk by alternately switching the laser diode, the light intensity of the laser beam between the read power and the write power higher than the read power. Drive circuit for driving the laser diode, a front monitor for monitoring the light intensity of the laser light, and a laser beam for obtaining an error between a value detected by the front monitor and a target value for each of the read power and the write power. And an automatic power control circuit for controlling the power of the laser diode, wherein the automatic power control circuit causes the error in the read power when the laser diode is pulsed with a plurality of different write powers to emit direct current. The read power error at each write power level should be the same as the read power error. Target power of the pulsed light emission at each write power level so that the error of the write power at the time of pulsed light emission becomes the same as the error of the write power at the time of direct current light emission. Target value acquisition means for acquiring a value, and the target value of the write power for each of the actual write power and the read power at the time of pulse emission from the acquired target values of the plurality of different read powers and the plurality of target values of the different write powers. And a relational expression creating means for creating a relational expression of the target value of the read power, and referring to the relational expression with the desired read power and write power, the target value of the read power and the write power of the read power used for actual recording By obtaining the target value, the desired write power and read power can be matched when recording with actual pulsed light emission. The goal light power that can set a target read power, by this,
It is possible to automatically control the actual read power and write power to desired values.

According to a second aspect of the present invention, the laser diode and the laser diode are arranged so that the light intensity of the laser beam is alternately switched between the erase power and the write power higher than the erase power to perform recording on the optical disk. A drive circuit for driving, a front monitor for monitoring the light intensity of the laser light, an automatic control for controlling the power of the laser light by obtaining an error between a value detected by the front monitor for each of the erase power and the write power and a target value. An optical disc apparatus comprising a power control circuit, wherein the automatic power control circuit is configured to erase the error in the erase power when the laser diode is pulsed with a plurality of different write powers. Erase at each write power level to be the same as the error of Obtains the target value of the word,
Target value acquisition means for acquiring the target value of the write power at the time of pulse emission at each write power level so that the error of the write power at the time of pulse emission becomes the same as the error of the write power at the time of direct current light emission. , The relationship between the target value of the write power and the target value of the erase power with respect to the difference between the actual write power and the erase power at the time of pulse emission from the acquired target values of the plurality of different erase powers and the plurality of target values of the different write powers. A relational expression creating means for creating an expression is provided, and by obtaining the target value of the write power and the target value of the erase power used for actual recording by referring to the relational expression with desired write power and erase power, The target write power and target erase power corresponding to the desired write power and erase power during recording by pulse emission of Can set Zupawa, this makes it possible to automatically control the actual erase power, a write power to a desired value.

[0013]

FIG. 5 is a block diagram of an embodiment of an optical disk device to which the laser power control circuit of the present invention is applied. In the figure, the optical pickup 100 is an optical system,
It has an actuator, a laser diode, a photodetector, a front monitor, etc., and performs recording / reproduction of the optical disc 102.

The laser driver 104 is the optical pickup 1
The laser diode in 00 is caused to emit light, and laser light is output. The front monitor in the optical pickup 100 detects the light intensity of the laser light, and the detection signal is APC (Au
A laser power control circuit 106 controls the laser driver 104 so that the power of the laser light becomes optimum based on the output of the front monitor.

A part of the photodetector output in the optical pickup 100 is supplied to the focus control circuit 108 and the tracking control circuit 110 as a servo signal, and the focus servo signals output from the focus control circuit 108 and the tracking control circuit 110, The tracking servo signal is supplied to the actuator driver 112 to drive the actuator in the optical pickup 100, and focus servo and tracking servo are performed.

The photodetector output (RF signal) in the optical pickup 100 is demodulated by the data demodulation circuit 114 and output. The data encoding circuit 116 encodes the recording data and supplies it to the laser driver 104. M
The PU (microprocessor) 120 is the APC circuit 10.
The control of the entire optical disk device including 6 is performed.

FIG. 6 is a circuit configuration diagram of the first embodiment of the laser power control circuit for performing the APC operation of the present invention. This embodiment is applied to recording on a write-once optical disc such as a CD-R or a DVD-R, and in the figure, the same parts as those in FIG. In FIG. 6, a part of the laser light output from the laser diode 10 is applied to the front monitor (photodiode) 12. The front monitor 12 supplies a detection current according to the light intensity of the laser light. An I / V conversion circuit composed of the operational amplifier 14 and the resistor Rf converts the detected current into a voltage. This voltage is amplified by the amplifier 16 ten times, for example, and then the sample hold circuit 18
Then, the sample is held at the read power timing by the read power sample pulse. After that, the polarity is inverted and the amplitude is doubled in the level shift circuit 20, and the D / A converter 2 in the differential amplifier configured by the operational amplifier 22.
It is differentially amplified with the target read power supplied from No. 4.
The digital value of the target read power is supplied from the MPU 120 to the D / A converter 24, and the operational amplifier 22
The error voltage Vgr of the detected read power with respect to the target read power is obtained and supplied to the A / D converter 42 and also supplied to the laser driver 26 via the switch 46. A /
The D converter 42 digitizes the error voltage Vgr to convert it to an MPU.
Supply to 120.

On the other hand, the voltage output from the I / V conversion circuit is sampled and held by the sample hold circuit 28 at the write power timing by the write power sample pulse. Here, in the case of DVD-R, the recording pulse is as shown in FIG.
As shown in (A), it is composed of a head pulse and a multi-pulse part following it. Since the multi-pulse part has a narrower pulse width than the head pulse, it is difficult to sample and hold, and as shown in FIG. As shown, since the I / V converted voltage is blunted compared to the head pulse, and accurate write power cannot be detected, the comparatively small portion excluding the rising edge of the head pulse is sampled and held.

After that, the level shift circuit 30 inverts the polarity and doubles the amplitude, and the differential amplifier constituted by the operational amplifier 32 differentially amplifies the target write power supplied from the D / A converter 34. . The digital value of the target write power is supplied from the MPU 120 to the D / A converter 34, and the operational amplifier 32 obtains the error voltage Vgw of the detected write power with respect to the target write power to obtain the laser driver 26 and the A / D converter. 42. The A / D converter 42 digitizes the error voltage Vgw to convert it to the MPU 12
Supply to 0.

The MPU 120 supplies the error voltage data to the D / A converter 44, and the error voltage analogized here is supplied to the laser driver 26 via the switch 46. The switch 46 is switched under the control of the MPU 120, and the error voltage output from either the operational amplifier 22 or the D / A converter 44 is supplied to the laser driver 26.

A laser generation pulse as a recording signal is supplied to the laser driver 26, and the laser diode 10 is driven by each of the error voltages Vgr and Vgw according to the laser generation pulse. Laser beam read power,
The respective write powers are feedback-controlled, that is, APC controlled so as to have the target read power and the target write power.

7 to 10 show the MPU 12 in the configuration of FIG.
10 shows a flowchart of a first embodiment of a correction process executed by 0. This processing is performed to optimize the power of the laser light at the time of recording when the optical disk is mounted, and the OPC (Opti
Mum Power Control).

In the figure, the MPU 120 puts the optical pickup 100 into a defocused state in step S10. It should be noted that, at the time of shipment of the optical disc device, the relationship between the laser light power and the front monitor detection level is, for example, 50 mV / mW when the laser diode 10 emits light by direct current drive.
Has been adjusted to.

Next, in step S12, the value _DDR for emitting light with the target read power is set in the D / A converter 24, and in step S14, the read power sample hold circuit 18 is set to the through state and the laser diode 10 is set.
DC light is emitted. Then, in step S18, the error voltage Vgr at this time is fetched from the A / D converter 42,
It is held as voltage data _{R R.} And step S2
Switch the switch 46 to the D / A converter 44 side at 0 to set D
The error voltage Vgr at the time of DC emission is supplied from the / A converter 44 to the laser driver 26.

Next, in step S22, a reference lower limit power P _WL and a reference upper limit power P _WH are set as recording system power. In step S24, the value D _DWL for emitting light at the reference lower limit power P _WL is set in the D / A converter 34, and in step S26, the write power sample hold circuit 28 is set to the through state and the laser diode 10 is set to D.
C emit light. Then, in step S28, the error voltage Vgw at this time is fetched from the A / D converter 42 and held as voltage data W _L.

Next, the value _{D DW H} a D / A converter 3 for light emission in step S30 in the reference upper limit power _{P WH}
Set to 4 and write power sample and hold circuit 2
The laser diode 10 emits DC light in the through state. Then, in step S32, the error voltage V at this time is
gw is fetched from the A / D converter 42 and voltage data _WH
Hold as.

Next, the MPU 10 returns the switch 46 to the operational amplifier 22 side in step S34, sets the value _DDR for causing the target read power to emit light in the D / A converter 24 on the read side, and sets the reference lower limit power P. The value D _DWL for emitting light from _WL is set in the D / A converter 34 on the write side to cause the laser diode 10 to emit pulsed light as in the actual recording. Then, in step S36, the error voltages Vgr and Vgw at this time are fetched from the A / D converter 42 and held as voltage data S _R and S _W.

Next, in step S38, the voltage data R _R during DC light emission is compared with the voltage data S _R, and R _R <S
Digital value to set the case of _R at step S40 to the D / A converter 24 decreases by _1, the digital value set in step S42 if the R R> _{S R} to the D / A converter 24 is increased by 1, When R _R = S _R , the digital value set in the D / A converter 24 is left unchanged in step S44, and the process proceeds to step S46.

In step S46, the voltage data W _L at the time of pulse emission is compared with the voltage data S _W, and W _L <S _W
In case of W _L > S _W , the digital value set in the D / A converter 34 is decreased by 1 in step S 48, and in case of W _L > S _W , step S
At 50, the digital value set in the D / A converter 34 is incremented by 1, and if W _L = S _W , the process proceeds to step S52.

[0030] determines whether the step S52 in _{R R} = _{S R,} the process proceeds to R R = _{S R} Otherwise step _S36, the process proceeds to step S54 if _R R = _S R, in this case Hold the set value of the D / A converter 24 in _DPRL ,
The set value of the D / A converter 34 is held in D _PWL .

As a result, the D / A on the read power side when the reference lower limit power P _WL is reached in a state where the read power and write power during pulsed light emission are the same as during DC light emission.
The setting value of the converter 24 is held in D _PRL, and the setting value of the D / A converter 34 on the write power side at the reference lower limit power P _WL is held in D _PWL .

Next, in step S55, the MPU 10 sets the set value D _{PR L} at the reference lower limit power P _WL to the read side D / _L.
With the A converter 24 set, the reference upper limit power P _WH
The value D _DWH for emitting light is set in the D / A converter 34 on the write side to cause the laser diode 10 to emit pulsed light as in the actual recording. Then, step S56
Then, the error voltages Vgr and Vgw at this time are set to the A / D converter 4
It is taken in from 2 and held as voltage data S _R and S _W.

Next, in step S58, the voltage data R _R during DC light emission is compared with the voltage data S _R, and R _R <S
Digital value to set the case of _R at step S60 to the D / A converter 24 decreases by _1, the digital value set in step S62 if the R R> _{S R} to the D / A converter 24 is increased by 1, When R _R = S _R , the digital value set in the D / A converter 24 is left unchanged in step S64, and the process proceeds to step S66.

[0034] compares the voltage data _{W H} and the voltage data _{S W} at step S66 the pulse _{emission, W} H _<S W
Reducing the digital value to be set to the D / A converter 34 when at step S68 only _{1, W} H> _S W when step S
The digital value set to the D / A converter 34 at 70 is increased by _1, in the case of W H = _{S W} proceeds to step S72.

[0035] determines whether the step S72 in _R R = _{S R,} the process proceeds to R R = _{S R} Otherwise step _S56, the process proceeds to R R = _S if _R step S74, the in this case Hold the set value of the D / A converter 24 in D _PRH ,
The set value of the D / A converter 34 is held in D _PWH .

As a result, the D / A on the read power side when the reference upper limit power P _WH is reached when the read power and write power during pulsed light emission are the same as during DC light emission.
The setting value of the converter 24 is held at D _PRH, and the setting value of the D / A converter 34 on the write power side at the reference upper limit power P _WH is held at D _PWH .

Thereafter, in step S76, the set value D _PWL of the D / A converter 34 on the write power side when the reference lower limit power P _{WL and} the D / A converter 34 on the write power side when the reference upper limit power P _WH are set. From the set value D _PWH of, the relational expression Ia is created by linear approximation between the write power actually output at the time of pulse emission shown in FIG. 11 and the set value (target value) of the D / A converter 34 on the write power side, Along with this, a relational expression Ib for DC emission is also created.

Along with this, the set value D _PRL of the D / A converter 24 on the read power side at the reference lower limit power P _{WL and} the set value D of the D / A converter 24 on the read power side at the reference upper limit power P _{WH The} read power actually output from the _PRH at the time of pulse emission shown in FIG.
A relational expression II is created by linear approximation with the set value (target value) of the A converter 24. The MPU 120 holds these relational expressions in the built-in memory and ends the processing.

It can be seen from FIG. 11 that the target write power for pulsed light emission must be lower than the target write power for DC light emission even if the actual write power is the same. This is because the voltage obtained by I / V converting the front monitor output becomes blunt.

Therefore, at the time of recording by the actual pulse emission, referring to the relational expressions Ia and II with desired write power and read power, the corresponding target write power and target read power are acquired and the D / A converter 34, Set to 24. As a result, the actual read power and write power can be APC controlled to desired values.

FIG. 13 shows a circuit configuration diagram of a second embodiment of the laser power control circuit for performing the APC operation of the present invention. This embodiment is applied to recording on a rewritable optical disc such as a DVD-RW, and the same parts in FIG. 6 as those in FIG. In FIG. 13, a part of the laser light output from the laser diode 10 is applied to the front monitor (photodiode) 12. The front monitor 12 supplies a detection current according to the light intensity of the laser light. An I / V conversion circuit composed of the operational amplifier 14 and the resistor Rf converts the detected current into a voltage. This voltage is amplified by the amplifier 16 ten times, for example, and then the level shift circuit 20
Then, the polarity is inverted and the amplitude is doubled, and the differential amplifier constituted by the operational amplifier 22 is differentially amplified with the target read power supplied from the D / A converter 24. The digital value of the target read power is supplied from the MPU 120 to the D / A converter 24, and the operational amplifier 22 obtains the error voltage Vgr of the detected read power with respect to the target read power and supplies it to the A / D converter 42. It is also supplied to the laser driver 26 via the switch 46. A / D converter 42
Supplies the error voltage Vgr to the MPU 120 after digitizing it.

On the other hand, the voltage output from the I / V conversion circuit is sampled and held by the sample hold circuit 28 at the write power timing by the write power sample pulse. Here, also in the case of the DVD-RW, as in the case of the DVD-R, since the recording pulse is composed of the head pulse and the multi-pulse part following the head pulse, there is little comparative roundness except for the leading edge of the head pulse. Sample hold the part.

After that, the level shift circuit 30 inverts the polarity and doubles the amplitude, and the differential amplifier constituted by the operational amplifier 32 differentially amplifies the target write power supplied from the D / A converter 34. . The digital value of the target write power is supplied from the MPU 120 to the D / A converter 34, and the operational amplifier 32 obtains the error voltage Vgw of the detected write power with respect to the target write power to obtain the laser driver 26 and the A / D converter. 42. The A / D converter 42 digitizes the error voltage Vgw to convert it to the MPU 12
Supply to 0.

The voltage output from the I / V conversion circuit is sampled and held by the sample and hold circuit 48 at the erase power timing by the erase power sample pulse. After that, the polarity is inverted and the amplitude is doubled in the level shift circuit 50, and differential amplification is performed with the target erase power supplied from the D / A converter 54 in the differential amplifier configured by the operational amplifier 52. The digital value of the target erase power is supplied from the MPU 120 to the D / A converter 54, and the operational amplifier 52 obtains the error voltage Vge of the detected erase power with respect to the target erase power to obtain A
The signal is supplied to the / D converter 42 and the laser driver 26 via the switch 56. The A / D converter 42 digitizes the error voltage Vge and supplies it to the MPU 120.

The MPU 120 supplies the error voltage data to the D / A converter 44, and the error voltage analogized here is supplied to the laser driver 26 via the switch 46. The switch 46 is switched under the control of the MPU 120, and the error voltage output from either the operational amplifier 22 or the D / A converter 44 is supplied to the laser driver 26.

A laser generation pulse as a recording signal is supplied to the laser driver 26, and the laser diode 10 is driven by each of the error voltages Vgr, Vgw, and Vge according to the laser generation pulse. The erase power and the write power of the laser light are feedback-controlled, that is, APC controlled so as to be the target erase power and the target write power, respectively.

14 to 16 show the MPU in the configuration of FIG.
10 shows a flowchart of a second embodiment of the correction process executed by 120. This process is executed together with OPC for optimizing the power of the laser light at the time of recording when the optical disc is mounted.

In the figure, the MPU 120 executes step S100.
The optical pickup 100 is brought into a defocused state. It should be noted that, at the time of shipment of the optical disc device, the relationship between the laser light power and the front monitor detection level is, for example, 50 mV / mW when the laser diode 10 emits light by direct current drive.
Has been adjusted to.

Next, in step S102, the value D _R for emitting light with the target read power is set in the D / A converter 24, and in step S104 the laser diode 10 is set to D
C emit light. Then, in step S108, the error voltage Vgr at this time is fetched from the A / D converter 42 and held as voltage data R _R. Then, step S11
Switch the switch 46 to the D / A converter 44 side at 0 to set D
The error voltage Vgr at the time of DC emission is supplied from the / A converter 44 to the laser driver 26.

Next, set the erase reference power _{P E} in Step S112, sets the value _{D DE} for light emission in the erase reference power _{P E} to the D / A converter 54, sample and hold of the erasing power in step S114 The laser diode 10 emits DC light by setting the circuit 48 in the through state. Then, in step S116, the error voltage Vge at this time is fetched from the A / D converter 42 and held as voltage data E _R. Then, in step S118, the switch 56 is switched to the D / A converter 44 side to change the D / A
The converter 44 supplies the laser driver 26 with the error voltage Vge during DC emission.

Next, in step S122, the reference lower limit power P _WL and the reference upper limit power P _WH are set as the recording system power. However, the relationship is P _E <P _WL <P _WH . In step S124, the value D _DWL for emitting light with the reference lower limit power P _WL is set in the D / A converter 34, and in step S126, the write power sample and hold circuit 2 is set.
The laser diode 10 is caused to emit DC light by setting 8 as a through state. Then, in step S128, the error voltage Vgw at this time is fetched from the A / D converter 42 and held as voltage data W _L.

Next, in step S130, the value D _{D WH} for emitting light with the reference lower limit power P _WH is set in the D / A converter 34, and the laser diode 10 is set to DC with the write power sample hold circuit 28 in the through state. Make it glow. Then, in step S132, fetches the error voltage Vgw this time from the A / D converter 42, is held as voltage data _{W H.}

Next, in step S134, the MPU 10 returns the switch 56 to the operational amplifier 22 side, and sets the value D _DE for emitting light with the target erase power to the erase side D / A.
The value is set in the converter 54, and the value D _DWL for emitting light at the reference lower limit power P _WL is set in the D / A converter 34 on the write side to cause the laser diode 10 to emit pulses in the same manner as during actual recording. Then, in step S136, the error voltages Vge and Vgw at this time are fetched from the A / D converter 42 and held as voltage data S _E and S _W.

Next, in step S138, the voltage data E _R during DC light emission is compared with the voltage data S _E, and E _R <
If S _E , the digital value set in the D / A converter 54 is decreased by 1 in step S140, and if E _R > S _E , the digital value set in the D / A converter 54 is increased by 1 in step S142. , E _R = S _E , the digital value set in the D / A converter 54 in step S144 remains unchanged, and the flow advances to step S146.

In step S146, the voltage data W _L at the time of DC light emission is compared with the voltage data S _W, and W _L <S _W
In the case of, the digital value set in the D / A converter 34 in step S148 is decreased by 1, and in the case of W _L > S _W , the digital value set in the D / A converter 34 in step S150 is set to 1
Only, and if W _L = S _W , the process proceeds to step S152.

[0056] determines whether the _E R = _{S E} In step _{S152, E} R = _S E unless step S136
If E _R = S _E , the process proceeds to step S154, where the set value of the D / A converter 54 at this time is held in D _PEL , and the set value of the D / A converter 34 is held in D _PWL . To do.

As a result, the D / A converter on the erase power side when the power difference (reference lower limit power P _WL -erase reference power P _E ) is the same when the power difference during pulsed light emission is the same as during DC light emission. set value of 54 is held in _{D PEL,} the power difference - set value (reference lower limit power _{P WL} erase reference power _{P E)} of the write power side when D / a converter 34 is held in the _{D PWL.}

Next, the MPU 10 keeps the set value D _{P EL} at the reference lower limit power P _{WL in} the D / A converter 54 on the erase side in step S155, while keeping the reference upper limit power P P.
The value D _DWH for emitting light at _WH is set to D / A on the light side.
The laser diode 10 is set in the converter 34 to emit a pulse as in the actual recording. And step S
At 156, the error voltages Vge and Vgw at this time are fetched from the A / D converter 42 and held as voltage data S _E and S _W.

Next, in step S158, the voltage data E _R during DC light emission is compared with the voltage data S _E, and E _R <
In the case of S _E , the digital value set in the D / A converter 54 is decreased by 1 in step S160, and in the case of E _R > S _E , the digital value set in the D / A converter 54 is increased by 1 in step S162. , E _R = S _E , the digital value set in the D / A converter 54 is left unchanged in step S164, and the process proceeds to step S166.

[0060] compares the voltage data _{W H} and the voltage data _{S W} at step S166 DC _{emission, W} H _<S W
When reduced by 1 digital values set in the D / A converter 34 in step _S168, if the W H> _{S W} in step S170 the digital value to be set to the D / A converter 34 1
Increased _by, in the case of W H = _{S W} proceeds to step S172.

[0061] determines whether the step S172 in _{E R = S E, E R} = S E unless step S156
If E _R = S _E , the process proceeds to step S174, where the set value of the D / A converter 24 at this time is held in D _PEH and the set value of the D / A converter 34 is held in D _PWH . To do.

[0062] Thus, in a state where the power difference during the pulse emission is the same as the time of DC light emission, power difference (reference upper limit power P _{WH -} Erase reference power P _E) of the erase power side when D / A converter The set value of 54 is held in D _PEH, and the set value of the D / A converter 34 on the write power side at the power difference (reference upper limit power P _WH -erase reference power P _E ) is held in D _PWH .

Thereafter, in step S176, the set value D _PWL of the D / A converter 34 on the write power side when the power difference (reference lower limit power P _WL -erase reference power P _E ) is _reached.
And the set value D _PWH of the D / A converter 34 on the write power side when the power difference (reference upper limit power P _WH -erasure reference power P _E ) is _reached , the erase power and the write actually output during the pulse emission shown in FIG. A relational expression IIIa is created by linear approximation between the power and the set value (target value) of the D / A converters 54 and 34, and the relational expression IIIb during DC light emission is also created
Also create.

At the same time, the power difference (reference lower limit power P
_WL -Erase reference power P _E ) The set value D _PEL of the erase power side D / A converter 54 and the power difference (reference upper limit power P _WH -Erase reference power P _E ) erase power side D / A From the set value D _{PEH of the} converter 54, a relational expression IV is created by linear approximation between the erase power actually output during the pulse emission shown in FIG. 18 and the set value (target value) of the D / A converter 54. Since the relational expression IV shown in FIG. 18 is the setting at the set value D _DE of the D / A converter 54 when the erase power is P _E , if the erase power is different from this, the relational expression IV is not changed. Since it cannot be used, as shown in FIG. 19, the D / A of the erase power with respect to the difference between the peak power and the erase power.
The relational expression V of the offset of the converter 54 is created and used.

To use the relational expression V, erase power P
_{When E1} is emitted, the offset amount of P _E1 is determined from the value of the difference (P _W1 −P _E1 ) from the peak power P _{W1 at} that time. For example, (P _W1 −P _E1 ) = (P _WL −
P _E ), the D / A converter 54 during DC emission of P _E1
If the set value of D _E1 is set, D /
The set value of the A converter 54 is D _E1 + (D _PEL −
D _DE ). The MPU 120 holds these relational expressions in the built-in memory and ends the processing.

At the time of recording by actual pulsed light emission, referring to the relational expressions IIIa and V with desired write power and erase power, the corresponding target write power and target erase power are acquired, and the D / A converters 34 and 54 are obtained. Set. As a result, it becomes possible to control the actual erase power and write power to desired values by APC. Although the relational expression of the read power is not created in the second embodiment, it may be created similarly to the first embodiment.

Incidentally, steps S10 to S74, S100
˜174 correspond to the target value obtaining means described in the claims, and steps S76 and S176 correspond to the relational expression creating means.

[0068]

As described above, the invention according to claim 1 is
The desired write power at the time of recording by actual pulse emission,
A target write power and a target read power corresponding to the read power can be set, so that the actual read power and write power can be automatically controlled to desired values.

According to the second aspect of the present invention, the target write power and the target erase power corresponding to the desired write power and erase power can be set at the time of recording by the actual pulse emission, whereby the actual erase power and write power can be set. Can be automatically controlled to a desired value.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an example of a conventional laser power control circuit that performs an APC operation.

FIG. 2 is a diagram showing a signal waveform recorded on a CD-R and a converted voltage waveform of a front monitor output.

FIG. 3 is a diagram showing a signal waveform recorded on a DVD-R and a converted voltage waveform of a front monitor output.

FIG. 4 is a diagram showing a signal waveform recorded on a DVD-RW.

FIG. 5 is a block diagram of an embodiment of an optical disc device to which the laser power control circuit of the present invention is applied.

FIG. 6 is a circuit configuration diagram of a first embodiment of a laser power control circuit that performs an APC operation of the present invention.

FIG. 7 is a flowchart of a first embodiment of correction processing.

FIG. 8 is a flowchart of a first embodiment of correction processing.

FIG. 9 is a flowchart of a first embodiment of correction processing.

FIG. 10 is a flowchart of a first embodiment of correction processing.

FIG. 11 is a diagram showing a write power relational expression.

FIG. 12 is a diagram showing a read power relational expression.

FIG. 13 is a circuit configuration diagram of a second embodiment of a laser power control circuit that performs an APC operation of the present invention.

FIG. 14 is a flowchart of a second embodiment of correction processing.

FIG. 15 is a flowchart of a second embodiment of correction processing.

FIG. 16 is a flowchart of a second embodiment of correction processing.

FIG. 17 is a diagram showing a write / erase power relational expression.

FIG. 18 is a diagram showing a write / erase power relational expression.

FIG. 19 is a diagram showing a peak erase power relational expression.

[Explanation of symbols]

10 Laser diode 12 Front monitor 14 Operational amplifier 16 amplifier 18, 28, 48 Sample and hold circuit 20, 30, 50 level shift circuit 22, 32, 52 Operational amplifier 24, 34, 44, 54 D / A converter 42 A / D converter 46,56 switch 100 optical pickup 102 optical disc 104 laser driver 106 APC circuit 108 Focus control circuit 110 Tracking control circuit 112 Actuator driver 114 data demodulation circuit 116 Data Encoding Circuit 120 MPU

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5D090 AA01 BB05 CC01 CC02 DD03                       EE01 EE05 KK03                 5D119 AA23 AA26 BA01 BB04 DA02                       HA03 HA13 HA45 HA52                 5D789 AA23 AA26 BA01 BB04 DA02                       HA03 HA13 HA45 HA52

Claims (2)

[Claims] 1. A laser diode, a drive circuit for driving the laser diode so as to perform recording on an optical disc by alternately switching the light intensity of the laser light between a read power and a write power higher than the read power, A front monitor that monitors the light intensity of the laser light, and an automatic power control circuit that controls the power of the laser light by obtaining an error between the value detected by the front monitor and the target value for each of the read power and the write power are provided. In the optical disc device, the automatic power control circuit is configured so that an error in the read power when the laser diode is pulsed with a plurality of different write powers is the same as an error in the read power when the direct current is emitted. While obtaining the target value of read power at each write power level Target value acquisition means for acquiring the target value of the write power at the time of pulse emission at each write power level so that the error of the write power at the time of pulse emission becomes the same as the error of the write power at the time of direct current light emission. From the acquired target values of the plurality of different read powers and the plurality of target values of the different write powers, the relational expression between the target value of the write power and the target value of the read power for each of the actual write power and the read power at the time of pulse emission And a relational value generating means for generating a target value of read power and a target value of write power used for actual recording by referring to the relational expression with desired read power and write power. Optical disk device. 2. A laser diode, a drive circuit for driving the laser diode so as to perform recording on an optical disc by alternately switching the light intensity of laser light between erase power and write power higher than the erase power, A front monitor for monitoring the light intensity of the laser light, and an automatic power control circuit for controlling the power of the laser light by obtaining the error between the value detected by the front monitor and the target value for each of the erase power and the write power are provided. In the optical disc device, the automatic power control circuit is configured so that the error in the erase power when the laser diode is pulsed with a plurality of different write powers is the same as the error in the erase power when the direct current is emitted. Get the target value of erase power at each write power level A target value for obtaining the target value of the write power at the time of pulse emission at each write power level so that the error of the write power at the time of pulse emission becomes the same as the error of the write power at the time of direct current light emission. From the acquisition means and the acquired target values of the plurality of different erase powers and the different target values of the write powers, the target value of the write power and the target of the erase power with respect to the difference between the actual write power and the erase power at the time of pulse emission A relational expression creating means for creating a relational expression of values, and obtaining a target value of write power and a target value of erase power used for actual recording by referring to the relational expression with desired write power and erase power. An optical disk device characterized by.