JP2001357542A - Multilayered optical disk recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely subject on the guide tracks on a servo layer to tracking in a desired recording layer. SOLUTION: The recording and reproducing side TES formed in a first servo signal detector and the servo side TES formed in a second servo signal detector are inputted to a beam deviation value detecting circuit 41 and a servo circuit 42. In the beam deviation value detecting circuit 41, the deviation value within the half track pitch of the optical axis of a laser beam for recording and reproducing and the optical axis of a laser beam for servo is detected by the recording and reproducing side TES and the servo side TES and the results of the detection are outputted to a beam misalignment correction circuit 43. In the beam misalignment correction circuit 43, the correction signal by the track offset signal based on the recording and reproducing side TES and the servo side TES for correcting the deviation value of the optical axis of the laser beam for recording and reproducing and the optical axis of the laser beam for servo is formed and is outputted to servo circuit 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer optical disc recording / reproducing apparatus, and more particularly, to a multi-layer optical disc recording / reproducing apparatus characterized by a tracking control portion in a recording layer.

[0002]

2. Description of the Related Art In recent years, one of the promising next-generation ultra-high-density optical recording media for recording media such as optical disks is a three-dimensional optical recording medium.

While the conventional optical recording medium records information two-dimensionally on a recording layer, the above-described three-dimensional optical recording medium has a recording film having a film thickness larger than the focal depth of a laser used. In addition to two-dimensional (planar) recording on layers,
Information is also recorded in the depth direction of the layer. For example, if 100 layers are recorded in the depth direction, the current 100
Double recording density can be achieved.

Research reports on such a three-dimensional optical recording medium are not intended for recording / reproducing when the recording medium is in a disk state. Proceedings of the Joint Lectures on Applied Physics 29p-B-11, 29p-B-12.

As a conventional three-dimensional optical recording medium, an optical disk has been proposed in which a plurality of recording layers are provided on a servo layer having guide tracks, for example. As described in JP-A-301226, in order to perform tracking with a guide track on a servo layer, a servo beam and a recording / reproducing beam are irradiated on an optical disc along the same optical axis, thereby focusing the servo beam on the servo layer and performing tracking. At the same time, the recording / reproducing beam is focused on the recording layer and the desired track of the recording layer is irradiated with the recording / reproducing beam by the tracking control in the servo layer.

[0006]

However, a desired recording layer of an optical disk having a plurality of recording layers provided on a servo layer having guide tracks by using a servo beam and a recording / reproducing beam having the same optical axis is also required. When the recording / reproducing beam is moved to the track, as shown in FIG. 16, the two optical axes are shifted due to the positional accuracy of the PBS for synthesizing the two laser beams and the wavelength fluctuation of the LD as the light source. In a multi-layer optical disc recording / reproducing apparatus having different optical axis shift amounts, even if tracking is performed with a servo beam, the recording / reproducing beam does not always converge on a guide track.
There is a problem that a desired track cannot be accessed and cannot be reproduced.

The present invention has been made in view of the above circumstances, and provides a multi-layer optical disk recording / reproducing apparatus capable of reliably performing tracking on a desired recording layer on a guide track on a servo layer. It is an object.

[0008]

According to the present invention, there is provided a multi-layer optical disc recording / reproducing apparatus, which comprises: a multi-layer optical disc having at least a guide track on a substrate and a plurality of recording layers for recording and reproducing information; A multi-layer optical disc recording / reproducing apparatus comprising: a servo light source for irradiating a servo light beam to the recording layer; and a recording / reproduction light source for irradiating the recording layer with a recording / reproduction light beam. Optical axis deviation detecting means for detecting the amount of optical axis deviation from the optical axis of the recording / reproducing light beam; and the servo light beam and the recording / reproducing means based on the optical axis deviation detected by the optical axis deviation detecting means. Correction means for correcting the irradiation position of the light beam, wherein the correction means irradiates the recording / reproducing light beam onto the guide track.

Further, in the multi-layer optical disk recording / reproducing apparatus of the present invention, a servo tracking signal generating means for generating a servo tracking signal on the guide track by the servo light beam; Recording / reproducing tracking signal generating means for generating a recording / reproducing tracking signal in the guide track, wherein the optical axis deviation detecting means converts the servo tracking error signal and the recording / reproducing tracking error signal into The correction means detects the optical axis shift amount based on the servo tracking error signal, and after tracking to a desired guide track based on the servo tracking error signal, corrects the servo tracking error signal by the optical axis shift amount to perform the recording / reproducing. A desired light beam onto the desired guide track. It can be configured to.

Further, in the multi-layer optical disk recording / reproducing apparatus of the present invention, the correcting means may be configured to change the polarity of the optical axis shift amount based on the optical axis shift amount.

Further, in the multi-layer optical disk recording / reproducing apparatus of the present invention, a servo address detecting means for detecting a servo side track address of the guide track by the servo light beam; Recording / reproducing address detecting means for detecting a recording / reproducing side track address, wherein the optical axis deviation detecting means detects an address deviation amount between the servo side track address and the recording / reproducing side track address, and The optical axis shift amount including the shift amount may be detected.

[0012]

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

FIGS. 1 to 11 relate to a first embodiment of the present invention. FIG. 1 is a diagram showing a configuration of an optical pickup of a multilayer optical disk recording / reproducing apparatus, and FIG. 2 is a configuration of an optical disk irradiated by the optical pickup. FIG. 3 is a diagram showing a configuration of a servo layer and a recording layer of an optical disk, FIG. 4 is a diagram showing a circuit configuration of a focus and tracking control system of a multilayer optical disk recording / reproducing apparatus, and FIG. 5 is a diagram showing a configuration of a servo circuit. FIG. 6 is a first flowchart illustrating the operation of the multi-layer optical disc recording / reproducing apparatus. FIG. 7 is a second flowchart illustrating the operation of the multi-layer optical disc recording / reproducing apparatus.
FIG. 8 is a third flowchart illustrating the operation of the multilayer optical disk recording / reproducing apparatus, FIG. 9 is a first diagram illustrating the operation of the multilayer optical disk recording / reproducing apparatus, and FIG. FIG. 2 and FIG. 11 are third views for explaining the operation of the multilayer optical disk recording / reproducing apparatus.

As shown in FIG. 2, an optical disk 1 which is a three-dimensional optical recording medium used in the present embodiment has a servo layer 3 provided on a substrate 2 having guide tracks formed in a spiral shape, And a plurality of recording layers 4 comprising n layers (first layer to n-th layer) provided on the servo layer 3.
Is managed by tracks and sectors as shown in FIG. 3, and information recorded on the optical disc 1 includes layer numbers: k,
The address is designated by a track number: 1 and a sector number: m, and a recording / reproducing beam is accessed to a desired area for recording / reproducing.

In this embodiment, as shown in FIG. 1, a laser beam for recording / reproduction for recording / reproducing recording information on the optical disk 1 and a laser beam for servo for performing focus control and tracking control by the optical pickup 11 are provided. To read information recorded on a desired recording layer. The optical pickup 11 is movable from the innermost circumference to the outermost circumference of the optical disk 1, and the optical disk 1 is rotated at a predetermined rotation speed by a spindle motor (not shown).

The recording / reproducing laser beam is supplied to the recording / reproducing LD2.
Emitted from 0. The laser light emitted from the recording / reproducing LD 20 is converted into a parallel light by a first collimator lens 22 via a first polarizing beam splitter 21, and is converted into a parallel light via a beam splitter 23 and a 波長 wavelength plate 24. The light enters the splitter 25, is condensed by the objective lens 26, and is irradiated on the optical disc 1.

Here, the objective lens 26 can irradiate the laser beam by moving it in the radial direction (tracking direction) and the thickness direction (focus direction) of the optical disk 1 by a biaxial objective lens actuator 26a.
Hereinafter, the objective lens actuator 26a for moving in the tracking direction is referred to as an objective TrAct, and the objective lens actuator 26a for moving in the focusing direction is referred to as an objective FoAct.

The return light of the recording / reproducing laser beam from the optical disk 1 is partially reflected at a right angle by the beam splitter 23 via the objective lens 26, the second polarizing beam splitter 25 and the quarter wavelength plate 24, The light enters the first servo signal detector 27 via the lens 29.

The first servo signal detector 27 generates a tracking error signal (hereinafter referred to as a recording / reproducing side TES) and a focus error signal (hereinafter referred to as a recording / reproducing side FES) by a recording / reproducing laser beam by a known method.

The return light of the recording / reproducing laser beam transmitted through the beam splitter 23 is reflected at a right angle by the first polarization beam splitter 21 via the first collimator lens 22.
The light enters the signal detector 28 and the information is reproduced.

On the other hand, the servo laser beam is emitted from the servo LD.
It is emitted from 30. The servo laser light emitted from the servo LD 30 is converted into parallel light by the second collimator lens 31, and is incident on the second polarization beam splitter 25 via the third beam splitter 32 and the half-wave plate 33. The light is reflected at a right angle by the second polarizing beam splitter 25, condensed by the objective lens 26, and irradiated on the optical disc 1.

Here, the second collimator lens 31 is a collimator lens actuator (hereinafter, collimator Fo).
Act 31a) makes it possible to move along the optical axis of the servo laser light.

The return light of the servo laser light from the optical disk 1 is transmitted to the objective lens 26 and the second polarization beam splitter 2.
The light is incident on the third beam splitter 32 via the 5 and 波長 wavelength plates 33, is reflected at a right angle by the third beam splitter 32, and passes through the lens 34 to the second servo signal detector 3.
5 is incident.

The second servo signal detector 35 generates a tracking error signal (hereinafter referred to as servo side TES) and a focus error signal (hereinafter referred to as servo side FES) by a servo laser beam by a known method, and outputs the tracking error signal to a guide track. A servo-side address signal which is a track number pre-formatted is detected.

As shown in FIG. 4, the recording / reproducing TES generated by the first servo signal detector 27 and the servo TES generated by the second servo signal detector 35 have a beam shift amount detection circuit 41 and a servo The servo address signal detected by the second servo signal detector 35 and the recording / reproducing side address signal which is a track number based on the reproduction signal from the signal detector 28 are input to the beam shift amount detection circuit 41. Is done.

As will be described later, the beam shift amount detection circuit 4
In step 1, the recording / reproducing TES and the servo-side TES detect the amount of deviation of the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam within a half-track pitch. 43. The beam deviation correction circuit 43 generates a correction signal based on a track offset signal based on the recording / reproduction side TES and the servo side TES for correcting a deviation amount of the optical axis of the recording / reproduction laser light and the optical axis of the servo laser light, and performs servo control. Output to the circuit 42.

After tracking is performed by the servo side TES using the servo laser beam, this correction signal is added to the servo side TES to move the servo laser beam in the tracking direction (radial direction), The optical axis of the recording / reproducing laser light shifted from the optical axis of the laser light is tracked on the track as desired.

In the servo circuit 42, as shown in FIG.
Recording / reproducing TES, recording / reproducing FES, servo-side TE
In addition to S, the servo-side FES, and the track offset signal from the beam deviation correction circuit 43, the target layer number of the recording layer from the CPU 50 is input.

Then, as shown in FIG.
In 2, in the focus servo circuit 51, the drive current value of the objective FoAct of the objective lens actuator 26a is set according to the recording / reproduction side FES by the recording / reproduction laser beam and the target layer number, and the objective FoAct is driven by driving the objective FoAct. The recording / reproducing laser beam is focused. In the collimator servo circuit 52, the drive current value of the collimator FoAct 31a is set by the servo side FES by the servo laser light and the target layer number, and the servo laser light is focused on the servo layer by driving the collimator FoAct 31a. maintain.

Further, in the servo circuit 42, an adder 53
A track offset signal is added to the servo side TES by using the switch 54.
And outputs it to the track servo circuit 55.
In the track servo circuit 55, the driving current value of the objective TrAct of the objective lens actuator 26a is set by the addition signal or the recording / reproducing TES, and the recording / reproducing laser light is tracked on the guide track by driving the objective TrAct. The switch 54 is a CPU 50
Is switched by. Details will be described later.

In this embodiment, as shown in FIGS. 6 to 8, when confirming insertion of the optical disc 1 in step S1, the CPU 50 loads the optical disc 1 to a predetermined position. Then, the optical pickup is moved to the innermost circumference of the optical disc 1 in step S2, and the rotation of the optical disc 1 is started in step S3.

Next, in step S4, the focus servo circuit 51, the collimator servo circuit 52, and the track servo circuit 55 are controlled, and the collimator lens actuator 3
1a and the objective lens actuator 26a are initialized. Then, the servo LD 30 is turned on in step S5.
Then, the optical disc 1 is irradiated with the servo laser light.

Then, in step S6, based on the servo side FES, the collimator lens actuator 31a and the objective lens actuator 26a start focus search and focus control on the servo layer 3 with the servo laser beam. As shown in FIG. 9, when it is confirmed in step S7 that focus servo by the servo laser beam has been performed, the recording / reproduction LD 20 is turned on in step S8.
Then, the optical disk 1 is irradiated with a recording / reproducing laser beam.

Then, in step S9, the recording / reproducing FES
, The collimator lens actuator 31a and the objective lens actuator 26a start focus search and focus control using the recording / reproducing laser beam on the servo layer 3. When it is confirmed in step S10 that the focus servo by the recording / reproducing laser beam has been performed, the process waits for the rotation of the optical disk 1 to reach a predetermined rotation speed in step S11. When the rotation reaches the predetermined rotation speed, the process proceeds to step S12.

Accordingly, as shown in FIG. 10, both the recording / reproducing laser light and the servo laser light are focused on the servo layer 3.

In step S12, based on the TES on the recording / reproducing side, the objective lens actuator 26a starts tracking focus control on the guide track of the servo layer 3 using the recording / reproducing laser beam. When it is confirmed in step S13 that the tracking servo by the recording / reproducing laser beam has been performed, kickback operation is started in step S14, and the irradiation positions of the recording / reproducing laser beam and the servo laser beam on the spiral guide track are determined. Keep it on the innermost guide track.

Next, in step S15, the control is switched to the tracking control in the servo layer 3 by the servo laser beam. In step S16, it is confirmed that the tracking servo by the servo laser beam is applied. The value of the side TES is determined by the beam shift amount detection circuit 4.
1 is detected and output as a track offset signal to the beam deviation correction circuit 43. In step S18, the beam deviation correction circuit 43 uses the correction signal (T
R) is generated and stored.

Next, in step S19, a seek operation to the recording layer 4 is started. First, in step S20, a target recording layer is determined. In step S21, the drive current value of the objective FoAct of the objective lens actuator 26a is set in the focus servo circuit 51 by the recording / reproducing FES using the recording / reproducing laser beam and the target layer number. , Objective FoAc
By driving t, the recording / reproducing laser beam is focused on the target recording layer. At this time, in the collimator servo circuit 52, the servo side FE by the servo laser beam is used.
Collimator FoAct31a by S and target layer number
Is set, and the collimator FoAct31a is set.
To maintain the focus of the servo laser beam on the servo layer.

Next, when it is confirmed in step S22 that the focus servo has been applied (both on the recording / reproducing side and the servo side), it is determined in step S23 that the movement to the desired recording layer has been completed. Initiate a radial seek operation on the layer.

That is, in step S24, the seek by the servo laser beam is started and the second seek by the servo laser beam is started.
The servo address signal from the servo signal detector 35 is read, and it is determined in step S25 whether the track number indicated by the servo address signal is a desired address. If not, the process returns to step S24 to reach the desired address. If so, the process proceeds to step S26.

In step S26, TR (correction signal) from the beam deviation correction circuit 43 is output to the adder 53.
The adder 53 adds the value to the servo side TES, and performs tracking with the corrected servo laser beam.

As a result, in step S26, as shown in FIG. 11, the servo laser beam deviates from the guide track, but the recording / reproducing laser beam is tracked on the guide track. In step S27, the seek to the desired track is performed. Complete and end the process.

As described above, in the present embodiment, even if the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam are deviated, the servo side TES is corrected and tracking is performed. The laser beam for use can be tracked on the guide track.

FIG. 12 is a flowchart for explaining the operation of the multi-layer optical disc recording / reproducing apparatus according to the second embodiment of the present invention.

Since the second embodiment is almost the same as the first embodiment, only different points will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

In FIG. 4, in the beam shift amount detection circuit 41 of the present embodiment, the recording / reproducing TES and the servo TE
The shift amount between the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam within one track pitch is detected based on S, and this detection result is output to the beam deviation correction circuit 43. The beam deviation correction circuit 43 generates a correction signal based on a track offset signal based on the recording / reproduction side TES and the servo side TES for correcting a deviation amount of the optical axis of the recording / reproduction laser light and the optical axis of the servo laser light, and performs servo control. Output to the circuit 42. Other configurations are the same as those of the first embodiment.

In the present embodiment, as shown in FIG.
In step S15 of the first embodiment, the control is switched to the tracking control in the servo layer 3 by the servo laser light. In step S16, it is confirmed that the tracking servo by the servo laser light is applied. Switching to tracking control in the servo layer 3 by light is performed, and in step S51, the recording / reproducing side T at this time is switched.
It is determined whether or not ES becomes 0. If the deviation between the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam is within a half track pitch, the recording / reproducing side TES becomes 0, so that step S17 is performed. However, if the deviation between the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam exceeds half a track pitch and falls within one track pitch, the recording / reproducing side TES does not become 0. After inverting the polarity of the side TES, the process returns to step S15. Other operations are the same as those of the first embodiment.

As described above, in the present embodiment, in addition to the effect of the first embodiment, the deviation between the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam exceeds the half track pitch and is 1 Even if it is within the track pitch, the servo side T
Since the correction is made after reversing the polarity of the ES, even if the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam deviate more than a half track pitch and within one track pitch, the servo side TES is corrected. Tracking can be performed, and the recording / reproducing laser beam can always be tracked on the guide track.

FIGS. 13 and 14 relate to a third embodiment of the present invention. FIG. 12 is a diagram showing a circuit configuration of a focus and tracking control system of a multilayer optical disk recording / reproducing apparatus. 6 is a flowchart for explaining the operation of FIG.

Since the third embodiment is almost the same as the second embodiment, only different points will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 13, in the beam shift amount detection circuit 41 of this embodiment, the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam are determined by the recording / reproducing TES and the servo TES. The shift amount within one track pitch is detected, and the shift amount of the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam at one track pitch or more based on the recording / reproducing side address signal and the servo side address signal. And outputs the detection result to the beam shift correction circuit 43. The beam shift correction circuit 43 corrects the shift between the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam based on a track offset signal (shift within one track pitch) based on the recording / reproducing TES and the servo TES. Amount) and
A correction signal based on an address offset signal (a shift amount exceeding one track pitch) based on the recording / reproducing side address signal and the servo side address signal and a target track number from the CPU 50 is generated and output to the servo circuit 42.
Other configurations are the same as those of the second embodiment.

In the present embodiment, as shown in FIG.
Between steps S14 and S15, in step S100, the address number (recording / reproducing side address signal) of the guide track by the recording / reproducing laser beam is stored in the read beam deviation correction circuit 43.

Following step S16, step S16
At 101, the address number (servo-side address signal) of the guide track by the servo laser beam is read and stored in the beam deviation correction circuit 43.

Further, in step S102 instead of step S18, the beam deviation correction circuit 43 calculates the difference between the servo side address signal and the recording / reproducing side address signal to obtain an address offset signal. A correction signal (TR) is generated and stored based on the result, and the process proceeds to step S19. Other operations are the same as those of the second embodiment.

As described above, in this embodiment, in addition to the effects of the second embodiment, the deviation between the optical axis of the recording / reproducing laser beam and the optical axis of the servo laser beam exceeds one track pitch. Even in this case, since the correction is performed based on the address offset signal and the track offset signal, the recording / reproducing laser beam can always be tracked on a desired guide track.

Although the configuration of the optical disk in each of the above embodiments is shown in FIG. 2, the present invention is not limited to this. As shown in FIG. 15, a servo layer 3 is provided in the middle layer and a plurality of recording layers are provided in upper and lower layers. Each embodiment can be applied to the optical disk 1 provided with the optical disk 4, and similar effects can be obtained.

[0057]

As described above, according to the present invention, there is an effect that tracking can be reliably performed on a desired recording layer on a guide track on a servo layer.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical pickup of a multilayer optical disc recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an optical disk irradiated by an optical pickup.

FIG. 3 is a diagram showing a configuration of a servo layer and a recording layer of the optical disc.

FIG. 4 is a diagram showing a circuit configuration of a focus and tracking control system of the multilayer optical disc recording / reproducing apparatus.

FIG. 5 is a diagram showing a configuration of a servo circuit.

FIG. 6 is a first flowchart for explaining the operation of the multilayer optical disc recording / reproducing apparatus;

FIG. 7 is a second flowchart for explaining the operation of the multilayer optical disk recording / reproducing apparatus;

FIG. 8 is a third flowchart for explaining the operation of the multi-layer optical disc recording / reproducing apparatus;

FIG. 9 is a first diagram illustrating the operation of the multilayer optical disk recording / reproducing apparatus.

FIG. 10 is a second diagram illustrating the operation of the multi-layer optical disc recording / reproducing apparatus.

FIG. 11 is a second diagram illustrating the operation of the multilayer optical disk recording / reproducing apparatus.

FIG. 12 is a flowchart for explaining the operation of the multi-layer optical disc recording / reproducing apparatus according to the second embodiment of the present invention;

FIG. 13 is a diagram showing a circuit configuration of a focus and tracking control system of a multilayer optical disc recording / reproducing apparatus according to a third embodiment of the present invention.

FIG. 14 is a flowchart for explaining the operation of the multi-layer optical disc recording / reproducing apparatus.

FIG. 15 is a diagram showing a configuration of a modified example of the optical disc.

FIG. 16 is a diagram for explaining a problem of a conventional multilayer optical disk recording / reproducing apparatus.

DESCRIPTION OF SYMBOLS 1 ... Optical disk 11 ... Optical pickup 20 ... Recording / reproducing LD 21 ... First polarizing beam splitter 22 ... First collimator lens 23 ... Beam splitter 24 ... 1/4 wavelength plate 25 ... Second polarizing beam splitter 26 ... Objective lens 26a ... Objective lens actuator 27 ... First servo signal detector 28 ... Signal detector 29,34 ... Lens 30 ... LD for servo 31 ... Second collimator lens 31a ... Collimator lens actuator 32 ... Third beam splitter 33 ... 1/2 wavelength plate 35 ... second servo signal detector 41 ... beam shift amount detection circuit 42 ... servo circuit 43 ... beam shift correction circuit 50 ... CPU 51 ... focus servo circuit 52 ... collimator servo circuit 53 ... adder 54 ... switch 55 ... Track servo circuit

Claims (4)

[Claims] At least a guide track is provided on a substrate.
A servo light source for irradiating the servo layer with a servo light beam and recording for irradiating the recording layer with a recording / reproducing light beam for a multilayer optical disc having a servo layer and a plurality of recording layers for recording and reproducing information. A multi-layer optical disc recording / reproducing apparatus including a reproducing light source; an optical axis deviation detecting means for detecting an optical axis deviation amount between an optical axis of the servo light beam and an optical axis of the recording / reproducing light beam; Correction means for correcting the irradiation position of the servo light beam and the recording / reproduction light beam based on the optical axis deviation detected by the axis deviation detection means, wherein the correction means comprises: the recording / reproduction light beam. A multi-layer optical disc recording / reproducing apparatus for irradiating a desired track on the guide track. 2. A servo tracking signal generating means for generating a servo tracking signal on the guide track by the servo light beam, and a recording / reproducing tracking signal on the guide track by the recording / reproducing light beam. Generating a recording / reproducing tracking signal generating means, wherein the optical axis deviation detecting means detects the optical axis deviation amount based on the servo tracking error signal and the recording / reproducing tracking error signal, The correction means, after tracking to a desired guide track based on the servo tracking error signal,
2. The multi-layer optical disc recording / reproducing apparatus according to claim 1, wherein the servo tracking error signal is corrected by the optical axis shift amount and the recording / reproducing light beam is irradiated onto a desired guide track. 3. The multi-layer optical disc recording / reproducing apparatus according to claim 2, wherein said correcting means changes the polarity of said optical axis shift amount based on said optical axis shift amount. 4. A servo address detecting means for detecting a servo side track address of the guide track by the servo light beam, and a recording / reproducing for detecting a recording / reproducing side track address of the guide track by the recording / reproducing light beam. Address detecting means, the optical axis shift detecting means detects an address shift amount between the servo side track address and the recording / reproducing side track address, and calculates the optical axis shift amount including the address shift amount. The multi-layer optical disk recording / reproducing apparatus according to claim 2, wherein the detection is performed.