JPH10162401A - Optical disc apparatus and method for correcting reference value of emission power of laser diode - Google Patents

Abstract

(57) Abstract: A high-precision APC operation (automatic control of the emission power of a laser diode using an output signal of a monitor diode) even when a monitor diode is arranged behind the laser diode. Operation). SOLUTION: The focus servo means (I / VAMP circuit group 19, S / H circuit group 20, and the like) of the output signal of the quadrant PD 3 for detecting the return light of the laser light from the optical disk.
(Consists of an RFAMP circuit 21, an FEAMP circuit 22, a focus driver 23, a focus servo circuit 25, and the like.)
By comparing the value at the in-focus position with the value at the out-of-focus position,
A laser used by means for performing an APC operation based on the comparison result (consisting of monitor PD2, I / VAMP circuit 6, S / H circuit 7, comparison circuit 8, filter 9, constant current driver 11, switching circuit 15, etc.) The reference value of the light emission power of the diode 1 is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical disk device and a method for correcting a reference value of light emission power of a laser diode thereof.

[0002]

2. Description of the Related Art Conventionally, in an optical disk apparatus, when recording and reproducing information by irradiating a laser beam from a laser diode (semiconductor laser) to an optical disk, the write power and read power of a recording pulse are applied to the rear of the laser diode. The output of the located monitor diode (photodiode) is sampled and held, and the output is controlled to be constant (for example, see Japanese Patent Application No. 61-42182).

[0003]

When such an automatic power control (APC operation) is performed, the emission power of the laser diode must be accurately detected from the output of the monitor diode. Is disposed, the return light from the optical disk is slightly incident on the monitor diode due to the birefringence of the optical disk, so that the emission power of the laser diode decreases near the focus position (for example, the dotted line in FIG. 2). (Corresponding to the portion enclosed by a circle).

[0004] This tendency is remarkable in a region where the emission power of the laser diode is low. Therefore, in order to improve this, it is conceivable to dispose a monitor diode in front of the laser diode, but this causes problems such as a reduction in light use efficiency and an increase in the size of a pickup equipped with the laser diode.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is directed to an optical disc apparatus in which a monitor diode is arranged behind a laser diode.
The purpose is to be able to perform actions.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a recording / reproducing means for recording and reproducing information by irradiating an optical disc with a laser beam from a laser diode, and a monitor located behind the laser diode when the means operates. An auto power control means for automatically controlling the emission power of the laser diode using an output signal of the diode, and an automatic laser beam emitted from the laser diode on an optical disk by moving a pickup lens up and down in a focus direction. In order to achieve the above object, in an optical disc apparatus provided with a focus servo means for automatically focusing and a photodiode for detecting return light of the laser light emitted from the laser diode from the optical disc, the following is provided. OPTICAL DISK DEVICE AND LASER DIO Providing a reference value correction method for de in the light emission power.

The optical disk device according to the first aspect of the present invention
Means for comparing the value of the output signal of the photodiode at the in-focus position by the focus servo means with the value at the out-of-focus position; and the emission power of the laser diode used by the auto power control means based on the comparison result. And a light emission power reference value correcting means for correcting the reference value.

According to a second aspect of the present invention, there is provided a method for correcting a reference value of a light emitting power of a laser diode, wherein a pickup mounted with a laser diode is moved in a radial direction of an optical disk while a pickup lens is moved up and down in a focus direction. The value of the output signal of the diode at the in-focus position is compared with the value at the out-of-focus position, and based on the comparison result, the reference value of the emission power of the laser diode used by the auto power control means is set to the radius of the optical disk. The correction is performed for each laser beam irradiation position in the direction.

According to a third aspect of the present invention, in the method of the second aspect, an operating point current value to an actuator for moving the pickup lens up and down in the focus direction is stored. The pickup lens is moved up and down as much as necessary to detect the return light from the optical disk by the photodiode from the operating point.

According to a fourth aspect of the present invention, there is provided a method for correcting a reference value of light emission power of a laser diode, wherein a pickup having a laser diode mounted thereon is moved to a mirror surface of an optical disk.
The pickup lens is moved up and down in the focus direction, the value of the output signal of the photodiode at the in-focus position is compared with the value at the out-of-focus position, and the auto power control unit uses the output signal based on the comparison result. It is characterized in that the reference value of the emission power of the laser diode is corrected.

According to a fifth aspect of the present invention, there is provided a method for correcting the reference value of the emission power of a laser diode, wherein the value of the output signal of the photodiode at the in-focus position and the offset voltage are applied to the focus servo means while the focus servo means is operated. Is compared with the output signal value of the photodiode at the out-of-focus position when is applied, and based on the comparison result, the reference value of the laser diode emission power used by the auto power control means is corrected. Features.

The method for correcting the reference value of the light emitting power of the laser diode according to the invention of claim 6 is the method of correcting the reference value of the light emission power of the laser diode according to the invention of claim 5, When comparing the value of the output signal of the photodiode, a pickup on which a laser diode is mounted is moved to a mirror portion of an optical disk.

[0013]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing an example of an optical disk device embodying the present invention.

This optical disk apparatus comprises a laser diode (hereinafter, referred to as "LD") 1, a monitor photodiode (hereinafter, referred to as "monitor PD"), a four-division photodiode (hereinafter, referred to as "four-division PD") 3, a focus actuator (hereinafter, referred to as "quadrant PD"). Focus motor) 4, and seek actuator (seek motor) 5, I / VAMP circuit 6, S
/ H circuit 7, comparison circuit 8, filter 9, constant current driver 11, D / A converter 12, and write pulse encoder 13.

A microcomputer (hereinafter referred to as “CP”)
U) 14, switching circuits 15, 16, constant current driver 17, D / A converter 18, I / VAMP
Circuit group 19, S / H circuit group 20, RFAMP circuit 21,
A FEAMP circuit 22, a focus driver 23, a seek driver 24, a focus servo circuit 25, a seek servo circuit 26, a focus up / down circuit 27, a comparator 28, a window comparator 29, an A / D converter 30, and a switch 31 are provided.

Here, each of the above-mentioned units is a recording / reproducing means for recording and reproducing information by irradiating a laser beam from the LD 1 to the optical disk, and a monitor PD (monitor diode) 2 located behind the LD 1 when the means operates. Auto power control (APC) means for automatically controlling the light emission power of the LD1 using the output signal of the LD1, automatically moving the laser light emitted from the LD1 onto the optical disk by moving the pickup lens up and down in the focus direction. It functions as focus servo means for focusing.

The value of the output signal of the 4-division PD (photodiode for detecting the return light of the laser light emitted from the LD 1 from the optical disk) 3 at the in-focus position by the focus servo means and the out-of-focus position Means for comparing the value with the APC, and the LPC used by the APC means based on the comparison result.
It functions as a light emission power reference value correction unit that corrects the light emission power reference value of D1.

Next, the operation according to the present invention by the optical disk apparatus configured as described above will be specifically described with reference to the timing chart of FIG. First, the operation according to the first aspect of the present invention will be described.

Correction of Reference Value of LD1 Read Power (1) The CPU 14 sets data in the D / A converter 12 in order to set the LD1 read power (light emission power during reproduction) to a desired value. (2) The current obtained from the monitor PD2 for monitoring the light emission power of the LD1 is converted into a voltage by the I / VAMP circuit 6,
The D / A converter 1 passes through the S / H circuit 7 and the comparison circuit 8
2 to obtain an error voltage.

(3) The error voltage passes through the filter 9 for stabilizing the APC loop, is current-amplified by the constant current driver 11, and is supplied to the LD1 through the switching circuit 15. Through the operations (1) to (3), the read power of the LD 1 is set to a desired value.

(4) The pickup lens is moved to the recording or reproduction start position of the optical disk. That is, CP
U14 drives the seek actuator 5 via the seek servo circuit 26 and the seek driver 24 to move the pickup lens to the target position. (5) In order to move the pickup lens up and down, the switch 31 is switched to the side where the focus up / down circuit 27 and the focus driver 23 conduct. The current waveform to the focus actuator 4 is as shown in FIG.

(6) When the pickup lens is moved up and down, in a place where the birefringence of the optical disk is large, due to the influence of the return light, the LD near the focal point (focus position) a shown in FIG.
1 is slightly reduced, so that the RFAMP circuit 21
The FEAMP circuit 22 outputs signals RF and FE having waveforms as shown in FIG.

The RFAMP circuit 21 generates the signal RF by summing the values of the output signals of the four-divided PD 3 (A, B, C, and D, respectively). The FEAMP circuit 22 generates a signal FE from the values A, B, C, and D of the output signals of the four-divided PD 3 using the following arithmetic expression. FE = (A + B)-(C + D)

(7) In order to detect the peak voltage Vp obtained at the out-of-focus position of the signal RF and a slight drop (portion surrounded by a dotted line in FIG. 2) obtained at the focal point a, the signal RF
Is high level "H", the output of the comparator 28 for detecting the predetermined value of the signal FE and the output obtained by the window comparator 29 for detecting the substantially focused point a of the signal FE (focus signal).
The peak voltage Vp and the bottom voltage V of the signal RF in the section where
b is detected by the CPU 14 via the A / D converter 30.

(8) The CPU 14 obtains the reference voltage Vc of the light emission power of the LD 1 from the value detected in (7) as follows, and sets it in the D / A converter 12 (L
After correcting the reference value of the light emission power of D1), the optical disk is irradiated with laser light from LD1 to record or reproduce information.

Vc = (Vp / Vb) * Vd Vc: Reference voltage Vd: Default reference voltage Vp: Peak voltage Vb: Bottom voltage

A at the time of recording ( writing) on the optical disc
The laser light emitted from the PC operation LD1 is converted into a current corresponding to the light amount (light emission power) by a monitor PD2 located behind the LD1, and then converted into a voltage by the I / VAMP6. The S / H circuit 7 samples the read power and holds the voltage at the write power output portion. Thereafter, the voltage is compared with the reference voltage by the comparison circuit 8 to obtain an error voltage.

The reference voltage is supplied from the CPU 14 to the D / A converter 12 so that the corrected read power can be obtained.
Is set to The error voltage passes through a filter 9 for stabilizing the APC loop, is current-amplified by a constant current driver 11, and is supplied to a switching circuit 15. The switching circuit 16 is turned on / off by a timing signal output from the write pulse encoder 13, and the switching circuit 15 is turned on at a read timing.

The write current is supplied from the CPU 14 to the D / A
The write power (light emission power during recording) of the LD 11 is set to a desired value in the converter 18, and the current is amplified by the constant current driver 17. The current is output from the write pulse encoder 13 by the switching circuit 16.
Is turned on / off and turned on at the write timing.

A at the time of reproduction (read) from the optical disk
The laser light emitted from the PC operation LD1 is converted into a current corresponding to the light amount (light emission power) by a monitor PD2 located behind the LD1, and then converted into a voltage by the I / VAMP6. The voltage passes through the S / H circuit 7 and is compared with a reference voltage by a comparison circuit 8 to obtain an error voltage. The S / H circuit 7 operates as a buffer amplifier during reading.

The reference voltage is supplied from the CPU 14 to the D / A converter 12 so that the corrected read power can be obtained.
Is set to The error voltage passes through a filter 9 for stabilizing the APC loop, is current-amplified by a constant current driver 11, and is supplied to a switching circuit 15. The switching circuit 15 is always on at the time of reading, and the switching circuit 16 of the write system is always off.

As described above, the value of the output signal of the 4-division PD (photodiode) 3 at the in-focus position is compared with the value at the out-of-focus position, and the APC operation is performed based on the comparison result. By correcting the reference value of the emission power of the LD (laser diode) 1, a monitor PD is provided behind the LD 1.
Even if (monitor diode) 2 is provided, highly accurate APC operation can be performed.

Next, the operation according to the second aspect of the present invention (LD
The operation of correcting the read power reference value (1) will be described. (1) The CPU 14 sets data in the D / A converter 12 to set the read power of the LD 1 (light emission power during reproduction) to a desired value. (2) The current obtained from the monitor PD2 for monitoring the light emission power of the LD1 is I / VA
The signal is converted into a voltage by the MP circuit 6, passes through the S / H circuit 7, is compared with a reference voltage output from the D / A converter 12 by the comparison circuit 8, and an error voltage is obtained.

(3) This error voltage passes through the filter 9 for stabilizing the APC loop, is current-amplified by the constant current driver 11, and is supplied to the LD1 through the switching circuit 15. Through the operations (1) to (3), the read power of the LD 1 is set to a desired value.

(4) The pickup is moved to the innermost position of the optical disk. That is, the CPU 14 drives the seek actuator 5 via the seek servo circuit 26 and the seek driver 24 to move the pickup to the innermost position. (5) In order to move the pickup lens up and down, the switch 31 is switched to the side where the focus up / down circuit 27 and the focus driver 23 conduct. The current waveform to the focus actuator 4 is as shown in FIG.

The operation (4) and the operation (5) are performed in parallel. However, the movement of the pickup in the radial direction of the optical disk is performed at such a slow speed that the time for moving the pickup lens up and down in the focus direction can be ignored.

(6) The CPU 14 calculates the correction of the reference voltage (reference value) of the light emission power (read power) of the LD 1 described in the description of the operation according to the first aspect of the present invention in each laser beam irradiation position in the radial direction of the optical disk. Each reference voltage is stored for each calculated value. Each laser beam irradiation position in the radial direction of the optical disk is obtained from a track error signal obtained from a groove of the optical disk.

(7) When recording and reproducing information by irradiating a laser beam from the LD 1 to the optical disk, an APC is performed for each laser beam irradiation position in the radial direction of the optical disk based on the above stored values (reference voltage). Perform the operation. 2. The method according to claim 1, wherein the APC operation uses the stored values.
This is the same as the operation according to the present invention.

As described above, while moving the pickup on which the LD 1 is mounted in the radial direction of the optical disk, the pickup lens is moved up and down in the focus direction, so
The value of the output signal of D3 at the in-focus position is compared with the value at the out-of-focus position, and based on the comparison result, the reference value of the light emission power of LD1 for performing the APC operation is set in the radial direction of the optical disk. By correcting for each laser beam irradiation position,
Even when the monitor PD2 is disposed behind the LD1 and the emission power of the LD1 fluctuates due to a change in birefringence within the optical disk surface (each laser beam irradiation position in the radial direction), a high-precision APC operation is performed. Can do it.

Next, the operation (LD) according to the third aspect of the present invention (LD
The operation of correcting the read power reference value (1) will be described. When correcting the read power of LD1, CPU 1
4 inputs data (predetermined value) for moving the pickup lens up and down in the focus direction to the focus up / down circuit 27. In this case, the current waveform to the focus actuator 4 becomes a triangular wave as shown in FIG.

In order to detect a peak voltage obtained at the out-of-focus position of the signal RF and a slight drop obtained at the focal point a, a comparator 28 for detecting a predetermined value of the signal RF and a signal FE (focus signal) are substantially combined. The data (operating point current value to the focus actuator 4) to the focus up / down circuit 27 in a section in which both outputs obtained by the window comparator 29 for detecting the focal point a become high level “H” are stored.

When the read power of the LD 1 is to be corrected for the second time or later, the CPU 14 inputs the above stored data to the focus up / down circuit 27, and from the position (operating point) corresponding to that data by the four-divided PD 3 As necessary to detect the return light from the optical disk,
Move the pickup lens up and down. The other operation is the same as the operation according to the second aspect of the present invention.

As described above, the operating point current value to the focus actuator 4 for moving the pickup lens up and down in the focusing direction is stored, and from the operating point, the return light from the optical disk is detected by the four-divided PD 3. However, by moving the pickup lens up and down, its movable range is narrowed, so that the time required for correcting the reference value of the light emission power of the LD 1 can be reduced.

Next, the operation according to the invention of claim 4 (LD)
The operation of correcting the read power reference value (1) will be described. (1) The CPU 14 sets data in the D / A converter 12 to set the read power of the LD 1 (light emission power during reproduction) to a desired value. (2) The current obtained from the monitor PD2 for monitoring the light emission power of the LD1 is converted into a voltage by the I / VAMP circuit 6,
The D / A converter 1 passes through the S / H circuit 7 and the comparison circuit 8
2 to obtain an error voltage.

(3) The error voltage passes through the filter 9 for stabilizing the APC loop, is current-amplified by the constant current driver 11, and is supplied to the LD1 through the switching circuit 15. Through the operations (1) to (3), the read power of the LD 1 is set to a desired value.

(4) The CPU 14 is the seek servo circuit 2
6. The seek actuator 5 is driven via the seek driver 24 to move the pickup to the mirror surface of the optical disk. (5) Then, in order to move the pickup lens up and down, the switch 31 is switched to the side where the focus up / down circuit 27 and the focus driver 23 are conducted. The current waveform to the focus actuator 4 is as shown in FIG.

(6) The CPU 14 performs a correction operation of the reference voltage (reference value) of the light emission power (read power) of the LD 1 described in the operation description of claim 1. At this time, the calculated value (reference voltage) is set in the D / A converter 12. This correction is completed only once. (7) When recording and reproducing information by irradiating the laser beam from the LD 1 to the optical disk, the APC operation is performed based on the reference voltage. The APC operation is the same as the operation according to the first aspect of the present invention.

As described above, the pickup on which the LD 1 is mounted is moved to the mirror portion of the optical disk, the pickup lens is moved up and down in the focus direction, and the value of the output signal of the 4-divided PD 3 at the in-focus position and the out-of-focus position Is compared with the reference value of the LD1, and based on the comparison result, the reference value of the emission power of the LD1 for performing the APC operation is corrected.
Even if the monitor PD2 is disposed behind D1 and the return light changes due to the difference in the reflectance (radial contrast) between the groove and the land of the optical disc, the APC operation can be performed with high accuracy.

Next, the operation (LD) according to the fifth aspect of the present invention (LD
The operation of correcting the read power reference value (1) will be described. (1) The CPU 14 sets data in the D / A converter 12 to set the read power of the LD 1 (light emission power during reproduction) to a desired value. (2) The current obtained from the monitor PD2 for monitoring the light emission power of the LD1 is converted into a voltage by the I / VAMP circuit 6,
The D / A converter 1 passes through the S / H circuit 7 and the comparison circuit 8
2 to obtain an error voltage.

(3) The error voltage passes through the filter 9 for stabilizing the APC loop, is current-amplified by the constant current driver 11, and is supplied to the LD1 through the switching circuit 15. Through the operations (1) to (3), the read power of the LD 1 is set to a desired value.

(4) The CPU 14 controls the seek servo circuit 2
6. The seek actuator 5 is driven via the seek driver 24 to move the pickup to the recording or reproduction start position of the optical disk. (5) Then, in order to move the pickup lens up and down, the switch 31 is switched to the side where the focus up / down circuit 27 and the focus driver 23 are conducted. The current waveform to the focus actuator 4 is as shown in FIG.

(6) The CPU 14 corrects the reference voltage (reference value) of the read power of the LD 1 while keeping the focus servo loop closed (the focus servo circuit 25 and the focus driver 23 are kept conductive by the switch 31). . That is, first, the value of the signal RF (the bottom voltage V) at the in-focus position (the position where the value of the signal FE is substantially “0”).
b) is data (digital value) in the A / D converter 30
And the data (bottom voltage Vb) is stored.

Next, the focus position of the focus servo circuit 25 (comprising a comparison circuit and a servo amplifier), that is, the focus reference voltage applied to one input terminal of the comparison circuit is varied (to the other input terminal). The signal FE is applied), and the value of the signal RF is converted by the A / D converter 3
Monitor via 0. Note that the pickup lens moves up and down in the focus direction by changing the focus reference voltage.

When the peak voltage Vp of the signal RF can be detected, the variable operation of the focus reference voltage is interrupted (the focus reference voltage at this time becomes the offset voltage), and the peak voltage Vp is stored. A ratio with respect to the calculated bottom voltage Vb is obtained, a reference voltage of the light emission power of the LD 1 is calculated from the result, and the calculated reference voltage is set in the D / A converter 12.

(7) When recording and reproducing information by irradiating the optical disk with laser light from the LD 1, the APC operation is performed based on the reference voltage. The APC operation is
The operation is the same as the operation according to the first aspect of the present invention.

As described above, while the focus servo loop is closed (the focus servo circuit 25 constituting the focus servo means is operated), the value of the output signal of the four-divided PD 3 at the in-focus position and the focus servo circuit 25 Comparing the output signal value of the four-divided PD 3 at the out-of-focus position when an offset voltage is applied to the LD, and correcting the reference value of the emission power of the LD 1 for performing the APC operation based on the comparison result. Thereby, the following effects can be obtained.

That is, even when the monitor PD2 is arranged behind the LD1, a highly accurate APC operation can be performed. Further, in order to detect the return light from the optical disk by the four-divided PD3, the pickup lens is moved up and down by the minimum necessary by changing the focus reference voltage. The time required to correct the value can be reduced.

Next, the operation according to the invention of claim 6 (LD)
The operation of correcting the read power reference value (1) will be described. Prior to correcting the read power of LD1,
That is, when comparing the value of the output signal of the 4-split PD 3 at the in-focus position and the in-focus position, the pickup on which the LD 1 is mounted is moved to the mirror surface of the optical disk. The other operation is the same as the operation according to the fifth aspect of the present invention.

As described above, the four positions at the in-focus position and the non-focus position are
When comparing the value of the output signal of the divided PD3, the monitor PD2 is arranged behind the LD1 by moving the pickup mounted with the LD1 to the mirror surface of the optical disk, and the difference in the reflectance between the groove and the land of the optical disk ( Even if the return light changes due to (radial contrast), a highly accurate APC operation can be performed.

As in the case of performing the operation according to the fifth aspect of the present invention, in order to detect the return light from the optical disk by the four-divided PD3, the pickup lens needs to be at least required by varying the focus reference voltage. To move up and down, the movable range becomes the minimum range,
The time required for correcting the reference value of the light emission power of the LD 1 can be reduced.

[0061]

As described above, according to the optical disk apparatus of the present invention, even when a monitor diode is disposed behind a laser diode, a high-precision AP is provided.
C operation can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an optical disk device embodying the present invention.

FIG. 2 is a timing chart showing an operation of correcting a reference value of a light emission power of a laser diode in the optical disk device shown in FIG.

[Explanation of symbols]

 1: laser diode (LD) 2: monitor photodiode (monitor PD) 3: quadrant photodiode (quadrant PD) 4: focus actuator (focus motor) 5: seek actuator (seek motor) 6: I / VAMP circuit 7 : S / H circuit 8: comparison circuit 9: filter 11: constant current driver 12, 18: D / A converter 13: write pulse encoder 14: microcomputer (CPU) 15, 16: switching circuit 17: constant current driver 19: I / VAMP circuit group 20: S / H circuit group 21: RFAMP circuit 22: FEAMP circuit 23: Focus driver 24: Seek driver 25: Focus servo circuit 26: Seek servo circuit 27: Focus up / down circuit 28: Comparator 29: Win Dough comparator 30: A / D converter 31: Switch

Claims (6)

[Claims] 1. A recording / reproducing means for recording and reproducing information by irradiating an optical disc with laser light from a laser diode, and using an output signal of a monitor diode located behind the laser diode when the means operates. Auto power control means for automatically controlling the light emission power of the laser diode, and a focus for automatically focusing a laser beam emitted from the laser diode on an optical disk by moving a pickup lens up and down in a focus direction. In an optical disc apparatus, comprising: a servo unit; and a photodiode for detecting return light of a laser beam emitted from the laser diode from the optical disc, wherein an output signal of the photodiode is focused at a focus position by the focus servo unit. Value and out-of-focus position And a light emission power reference value correction means for correcting a reference value of the light emission power of the laser diode used by the auto power control means based on the comparison result. Optical disk device. 2. A recording / reproducing means for recording and reproducing information by irradiating an optical disk with laser light from a laser diode, and using an output signal of a monitor diode located behind the laser diode when the means operates. Auto power control means for automatically controlling the light emission power of the laser diode, and a focus for automatically focusing a laser beam emitted from the laser diode on an optical disk by moving a pickup lens up and down in a focus direction. In an optical disc apparatus including a servo unit and a photodiode for detecting return light of a laser beam emitted from the laser diode from an optical disc, a pickup mounted with the laser diode is moved in a radial direction of the optical disc. , That pic The pickup lens is moved up and down in the focus direction, the value of the output signal of the photodiode at the in-focus position is compared with the value at the out-of-focus position, and the auto power control means is used based on the comparison result. A method for correcting the reference value of the emission power of the laser diode in the optical disk device, wherein the reference value of the emission power of the laser diode is corrected for each laser beam irradiation position in the radial direction of the optical disk. 3. A method for correcting a reference value of light emission power of a laser diode in an optical disk device according to claim 2, wherein an operating point current value to an actuator for moving the pickup lens up and down in a focus direction is stored. A method of correcting a reference value of a light emitting power of a laser diode in an optical disk device, wherein the pickup lens is moved up and down as necessary to detect return light from the optical disk by the photodiode from a point of view. 4. A recording / reproducing means for recording and reproducing information by irradiating an optical disc with laser light from a laser diode, and using an output signal of a monitor diode located behind the laser diode when the means operates. Auto power control means for automatically controlling the light emission power of the laser diode, and a focus for automatically focusing a laser beam emitted from the laser diode on an optical disk by moving a pickup lens up and down in a focus direction. In an optical disk device including a servo unit and a photodiode for detecting return light of the laser light emitted from the laser diode from the optical disk, a pickup equipped with the laser diode is moved to a mirror surface of the optical disk, That picka The pre-lens is moved up and down in the focus direction, the value of the output signal of the photodiode at the in-focus position is compared with the value at the out-of-focus position, and based on the comparison result, the auto power control means uses A method for correcting a reference value of a light emitting power of a laser diode in an optical disc apparatus, wherein the reference value of a light emitting power of a laser diode is corrected. 5. A recording / reproducing means for recording and reproducing information by irradiating an optical disk with laser light from a laser diode, and using an output signal of a monitor diode located behind the laser diode when the means operates. Auto power control means for automatically controlling the light emission power of the laser diode, and a focus for automatically focusing a laser beam emitted from the laser diode on an optical disk by moving a pickup lens up and down in a focus direction. In an optical disc device including a servo unit and a photodiode for detecting return light of a laser beam emitted from the laser diode from the optical disc, the focus servo unit is operated while the focus servo unit is operated. The output signal of the photodiode And a value of an output signal of the photodiode at an out-of-focus position when an offset voltage is applied to the focus servo unit. Based on the comparison result, the laser diode used by the auto power control unit is used. A method for correcting a reference value of a light emission power of a laser diode in an optical disc device, wherein the reference value of the light emission power is corrected. 6. The method of correcting a reference value of a light emission power of a laser diode in an optical disk device according to claim 5, wherein the value of the output signal of the photodiode at the in-focus position and the value of the output signal of the photodiode at the in-focus position are compared. A method for correcting a reference value of light emission power of a laser diode in an optical disk device, wherein a pickup on which a laser diode is mounted is moved to a mirror portion of the optical disk.