JP2000222749A - Optical disk driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute the offset compensation corresponding to each region having respectively different physical characteristics by adjusting the correcting operation of an offset signal of an offset compensating/correcting means when the converging region of an optical beam is changed upon the forced displacement of an objective lens. SOLUTION: By the mechanism for displacing the lens to the outer peripheral, a driving signal Sos is supplied to a tracking actuator 5 to displace the objective lens 4 to the outer peripheral direction. Also by the mechanism for displacing the lens to the inner periphery, a driving signal Sis is supplied to the tracking actuator 5 to displace the objective lens 4 to the inner peripheral direction. The region where the position of the light presently converging on the optical disk belongs to, is discriminated by a region discriminating device 103. By this procedure, even in the case the light is converged on the region having the different material characteristics when the objective lens 4 is displaced, the objective lens 4 is made to displace in the opposite direction, thereby properly corrects the offset compensation factor in accordance with the irradiated region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mini disc (abbreviated as "MD") and a compact disc ("CD").
), A recording device for recording information on an optical disk represented by a magneto-optical disk (abbreviated as “MO”), a phase change disk (abbreviated as “PC”), and reproducing information recorded on the optical disk The present invention relates to a reproducing apparatus and an optical disk drive including a recording and reproducing apparatus for recording and reproducing information on an optical disk. More specifically, the present invention relates to detection and correction of a tracking error in an optical disk drive.

[0002]

2. Description of the Related Art Conventionally, a tracking signal detection method called a far field method (hereinafter abbreviated as "FF method") or a push-pull method (hereinafter abbreviated as "PP method") is used for detecting tracking of an optical disk drive. Widely used. For simplicity, this tracking signal detection method is referred to as a “PP method”. The PP method has a simple configuration of a required device, and has a higher use efficiency of a laser beam than other tracking signal detection methods such as a three-beam method. Suitable for use in possible optical disc drives.

However, in the PP method, when the objective lens is displaced in a direction perpendicular to the recording track of the optical disk, there is a problem that an offset corresponding to the amount of displacement of the objective lens occurs in the tracking error signal.

[0004] Since the optical disk always has eccentricity of the center of rotation, when the optical disk is rotated, the radial position of the recording track on the disk changes at a high speed, and the displacement of the objective lens changes accordingly. The above-described offset of the tracking error signal also changes at a high speed. It goes without saying that tracking cannot be correctly detected under such a high-speed offset fluctuation. Therefore, in general, in the PP method, in order to eliminate the high-speed offset fluctuation, a traverse mechanism capable of a high-speed response that always positions the objective lens at the center of the laser optical axis even when the recording track position changes at a high speed. It is necessary and causes cost increase.

FIG. 10 shows an example of an improved PP method for reducing the offset of a tracking error signal when the objective lens is displaced in the recently proposed PP method, as disclosed in Japanese Patent Laid-Open No. 9-22321 (August 1997). 1 shows an optical disk drive disclosed in U.S. Pat. The optical disk drive ODP1 includes a turntable 2, a motor 3, an objective lens 4, a tracking actuator 5, a tracking controller 6R, a light receiving cell 9, adders 10 and 11, a light spot displacement detector 12, a tracking error detector 13,
An amplifier 14 and an offset corrector 15 are included.

In the optical disk drive ODP1, the optical disk 1 is fixed to a turntable 2, and the turntable 2 is rotated by a motor 3 to rotate the optical disk 1. The objective lens 4 focuses the laser beam Lb emitted from the optical pickup (not shown) on the recording surface of the optical disc 1 and also focuses the laser beam Lb reflected on the recording surface on the light receiving element 9. . The light receiving element 9 is a light spot O of the focused laser beam Lb.
Various electric signals are output according to s.

Referring to FIG. 6, the structure of the light receiving surface of light receiving element 9 generally used in the PP method will be briefly described. The light receiving element 9 shown in FIG.
The light receiving cells ROa, RI, ROb, LOa are formed by a plurality of division lines Lv substantially perpendicular to the direction corresponding to the recording track of the optical disk 1 and the division lines Lp substantially parallel to the direction corresponding to the recording track of the optical disc 1. , LI, and LOb
Is divided into The light spot Os is connected to the light receiving surface thus divided. As shown in FIG. 6B, the light receiving cells ROa, RI, and ROb in the left column receive reflected light from the outer peripheral side of the recording track Tr. On the other hand, the light receiving cells LOa, LI, and LOb in the right column receive reflected light from the inner peripheral side of the recording track Tr.

The light receiving cells ROa and ROb and the light receiving cells LOa and LOb receive light in the end regions with respect to the center of the light spot Os, respectively. Light receiving cell ROa and light receiving cell RO
b, regions AoRa and A of connected light spot Os on b
oRb is a portion irradiated with 0-order diffracted light reflected without diffracting on the recording surface of the optical disc 1. Similarly,
Light receiving cell LOa and light receiving cell LOb of light spot Os
The upper regions AoLa and AoLb are portions where only the 0th-order diffracted light reflected without diffracting on the recording surface of the optical disc 1 is received. Therefore, these areas do not interfere with the diffracted light from the recording surface of the optical disc 1. In this sense, these regions AoLa,
AoLb, AoRa, and AoRb are combined into a non-interference area A
o.

Then, the light receiving cells RI and LI receive light in a middle area with respect to the center of the light spot Os. Spot O
The area AiR occupied by the s on the light receiving cell RI and the area AiL occupied by the light receiving cell LI (shown by hatching in the figure)
(Indicated by diagonal lines in the drawing) are the 0th-order diffracted light reflected without diffracting on the recording surface of the optical disc 1 and ± 1 diffracted and reflected by the shape of the recording track on the recording surface of the optical disc 1. This is the area where the next-order diffracted light overlaps and causes interference. In this sense, the regions AiR and AiL are collectively referred to as an interference region Ai.

As shown in FIG. 10, in the optical disk drive ODP1, the light receiving cell ROa outputs a first outer peripheral side end area signal SROa in accordance with the light spot Os.
The light receiving cell RI outputs the outer peripheral side middle area signal SRI, and the light receiving cell ROb outputs the second outer peripheral side end area signal SROb. Similarly, the light receiving cell LOa outputs a first inner peripheral side end area signal SLOa, and the light receiving cell LI outputs an inner peripheral side middle area signal SLOa.
LI, and the light receiving cell LOb outputs the second inner peripheral side end area signal SLOb.

The adder 10 outputs a first outer peripheral end area signal SROa output from the light receiving cell ROa and a light receiving cell R
Second outer peripheral side end area signal SROb output from Ob
Are added to generate the outer peripheral side end area signal SRO. Similarly, the adder 11 adds the first inner peripheral end area signal SLOa output from the light receiving cell LOa and the second inner peripheral end area signal SLOb output from the light receiving cell LOb. , The inner peripheral side end area signal SLO.

The light spot displacement detector 12 subtracts the inner peripheral edge area signal SLO from the outer peripheral edge area signal SRO,
An end area signal SO which is a difference between the end area signals is generated. The end area signal SO represents an offset amount that is a relative displacement in a direction substantially perpendicular to a recording track of the light spot Os connected on the light receiving element 9. In this sense, the end region signal SO is referred to as a first offset signal.

The amplifier 14 includes a light spot displacement detector 12
Amplifies the first offset signal SO, which is the output of the first offset signal SO, by a predetermined coefficient k to generate a weighted second offset signal SOk.

The tracking error detector 13 subtracts the inner peripheral side middle area signal SLI output from the light receiving cell LI from the outer peripheral side middle area signal SRI output from the light receiving cell RI. A middle area signal SI that is a difference is generated. The middle area signal SI includes an offset amount, which is a displacement in a direction substantially perpendicular to a recording track between the light receiving element 9 and the light spot Os, and a tracking error amount.
In this sense, the middle area signal SI is called an offset tracking error signal.

The offset corrector 15 calculates the second offset signal SOk from the offset tracking error signal SI.
Is subtracted to generate a tracking error signal St that does not include the offset amount.

The tracking controller 6R subjects the tracking error signal St to phase compensation, low-frequency compensation, etc., and generates a tracking control signal Stc. Based on the tracking control signal Stc, the tracking actuator 5 moves the objective lens 4 in a direction perpendicular to the recording track Tr, that is, the optical disc 1 so that the laser beam Lb follows the recording track Tr (not shown) of the optical disc 1.
In the radial direction.

The operation of the above-described optical disk drive ODP1 will be described with reference to FIGS. FIG.
The light reflected from the disk 1 is reflected by the light receiving element 9 shown in FIG.
The relationship between the position of the light spot Os connected above and the displacement of the objective lens 4 is shown. FIG. 7A shows a case where the center of the objective lens 4 coincides with the center of the laser optical axis, that is, the displacement amount is zero. FIG. 7B shows a case where the displacement of the objective lens 4 is shifted from the center of the laser optical axis to the inner peripheral side of the disk 1. FIG. 7C shows a light spot Os formed on the light receiving element 9 when the displacement of the objective lens 4 is shifted from the center of the laser optical axis to the outer peripheral side of the disk 1.

FIG. 8 shows the relationship between the offset tracking error signal SI, the first offset signal SO, the second offset signal SOk, and the tracking error signal St observed by the optical disk drive ODP1 and the displacement of the objective lens 4. Is shown. In the figure, the horizontal axis represents the amount of displacement D in the direction perpendicular to the recording track of the objective lens 4, and the vertical axis represents the amplitude A of each signal.

An offset tracking error signal SI, which is a tracking error signal before offset correction, has a displacement amount D of the objective lens 4 about the origin at which the displacement amount D is zero.
The signal peak changes in proportion to. Note that the offset component included in the offset tracking error signal SI can be represented by a dotted line Da.

The first offset signal SO, which is the difference between the end areas output from the light spot displacement detector 12, changes in accordance with the displacement D of the objective lens 4 about the origin. However, since the first offset signal SO is a signal obtained from the non-interference area Ao due to only the zero-order diffracted light, the magnitude of the amplitude is obtained from the interference area Ai where the zero-order diffracted light and the first-order diffracted light interfere with each other. 1 / k of the offset component Da included in the offset tracking error signal SI. Note that k depends on the introduction of the optical system used in the optical disk drive ODP1 including the objective lens 4 and the state on the recording track surface of the optical disk 1.
This is a coefficient uniquely determined.

The second offset signal SOk is supplied to the amplifier 1
In step 4, the first offset signal SO is generated by amplifying it by k times. As a result, the second offset signal SOk becomes the offset component D included in the offset tracking error signal SI.
has a size equal to a. In the offset corrector 15,
By subtracting the second offset signal SOk from the offset tracking error signal SI, a tracking error signal St from which the offset component Da has been removed is generated.

When the relative position between the laser beam Lb and the recording track Tr changes, the manner of interference between the 0th-order light and the 1st-order light changes in the interference area Ai of the light receiving element 9. It changes sinusoidally as shown in FIG.
A so-called far-field (push-pull) tracking error signal is obtained. Note that the laser beam Lb is 1
After moving by the recording track, the phase difference is 360 °. At this time, since there is no interference between the 0th-order diffracted light and the 1st-order diffracted light in the non-interference area Ao, no far-field tracking error signal is generated in the end area signal SO.

When the center of the objective lens 4 coincides with the center of the optical axis of the laser, the light spot Os is located at the center of the light receiving element 9 as shown in FIG. for that reason,
From the offset tracking error signal SI, a sine-wave-shaped far-field tracking error signal centered on the 0 level is obtained as shown in FIG. In this case, since the displacement amount is zero, the value of the first offset signal SO, which is the end area signal, is also zero. When the displacement of the objective lens 4 is shifted from the center of the optical axis of the laser, FIGS. 7B and 7C
As shown in (1), the relative displacement between the light spot Os and the light receiving element 9 is shifted in a direction perpendicular to the recording track. for that reason,
As shown in FIG. 8, the offset tracking error signal SI which is a difference between the middle area signals is a signal obtained by adding an offset corresponding to the position of the objective lens (horizontal axis) to the far field tracking error signal. As a result, the first offset signal SO, which is the difference between the end regions, indicates an offset level corresponding to the displacement of the objective lens 4.

That is, the second offset signal SOk generated by giving the first offset signal SO an appropriate weighting by the coefficient k by the amplifying means 14 is output to the offset tracking error signal S
When subtracted from I, the tracking error signal S which does not always include the offset component Da regardless of the displacement of the objective lens 4
t can be generated.

Next, a conventional optical disk drive having an automatic tracking offset adjusting function will be described with reference to FIG. Optical disk drive OD described above
In P1, the coefficient k used in the amplifier 14 is a constant value mainly determined by the state on the recording track surface of the optical disc 1. Therefore, the state of the recording track surface is different if the optical disc 1 is different. Therefore, it is necessary to newly set the coefficient k according to the optical disc 1 at least every time the optical disc 1 is replaced.

Optical disk drive ODP2 in this embodiment
Then, each time the optical disk 1 is replaced, an appropriate coefficient k corresponding to the optical disk 1 is automatically obtained once at first. Then, the tracking error signal St is obtained by correcting the offset tracking error signal SI with the first offset signal SO generated based on the obtained coefficient k. That is, the tracking offset value when the objective lens 4 is displaced is corrected by automatically obtaining the optimum coefficient k for each optical disc 1.

The optical disk drive ODP2 is obtained by replacing the tracking controller 6R of the optical disk drive ODP1 shown in FIG. 10 with an initial offset correction coefficient setting unit ACS. The initial offset automatic adjuster ACS includes a tracking control switch 6RR, an offset measuring device 16,
It includes a correction amount calculator 17, a forced lens displacement unit 18, and a switch SW. The forcible lens displacement unit 18 outputs a lens drive signal Stp for displacing the objective lens 4 by a predetermined amount, that is, moving the objective lens 4 by a predetermined distance in the tracking direction.

The tracking control switch 6RR is provided for the tracking controller 6R in the optical disk drive ODP1.
Mode switching that generates a tracking control signal Stc based on the tracking error signal St and generates a mode switching signal Ss that controls the operation of the switch SW in accordance with the operation mode of the initial offset correction coefficient setting unit ACS in the same manner as described above. It is also a vessel.

The switch SW selectively selects one of a lens drive signal Stp output from the forced lens displacement unit 18 and a tracking control signal Stc output from the tracking control switch 6R based on the mode switching signal Ss. Is a selection switch to be supplied to the tracking actuator 5.

The offset measuring device 16 tracks the offset component Da that cannot be removed from the offset tracking error signal SI in the second offset signal SOk obtained by correcting the first offset signal SO by the amplifier 14 based on the current coefficient k. The residual offset amount Of is measured from the error signal St, and the offset amount signal Sof is generated. The correction amount calculator 17 calculates the offset amount signal Sof.
, A coefficient correction signal Sk for obtaining an appropriate coefficient k for setting the value of the residual offset amount Of to zero is generated.

Referring to the flowchart shown in FIG.
The operation of the optical disk drive ODP2 having the above configuration will be described. When the optical disk drive ODP2 is powered on, an initial offset correction operation by the initial offset corrector ACS is started. Step S70
In 1, the tracking control switch 6RR first
The mode switching signal Ss is generated, and the output port of the forced lens displacement unit 18 is connected to the tracking actuator 5 by the switch SW. Then, the process proceeds to the next step S702.

In step S702, the lens drive signal Stp is supplied from the forced lens displacement unit 18 to the tracking actuator 5. The tracking actuator 5 displaces the objective lens 4 by a predetermined distance based on the lens drive signal Stp. Then, the process proceeds to step S703.

In step S703, the correction amount calculator 17
Generates a correction coefficient signal Sk that sets the correction coefficient k to 1 / Ko based on the offset amount signal Sof output from the offset measuring device 16. Ko is a fixed value determined in consideration of the maximum eccentricity and the minimum eccentricity of the optical disc 1 and the maximum offset allowed by the optical disc drive ODP2. Then, the process proceeds to step S704.

In step S704, the amplifier 14 corrects the correction coefficient k (1 / Ko) determined in step S703.
, And corrects the first offset signal SO to generate a second offset signal SOk. Offset compensator 1
5 generates a tracking error signal St by correcting the offset of the offset tracking error signal SI based on the second offset signal SOk. The offset measuring device 16 measures the residual offset amount Of still included in the tracking error signal St over a predetermined time, and also calculates the average value Ofm of the residual offset amount Of measured over the predetermined time (hereinafter, the average offset Off). (Referred to as a value) to generate an offset amount signal Sof.
Then, the process proceeds to step S705.

In step S705, the correction amount calculator 17 determines whether the average offset value Ofm is equal to or less than a predetermined threshold value Oth based on the offset amount signal Sof. This threshold value Oth is determined by the optical disc driving device ODP2
Is a value determined in consideration of the maximum offset amount allowed in the above. If the average offset value Ofm is larger than the threshold value Oth corresponding to the predetermined offset amount, it is determined as NO, and the process proceeds to step S706.

In step S706, the correction amount calculator 17
Calculates the correction coefficient signal S by adding 1 / Ko to the current coefficient k.
Generate k. Then, the process returns to step S704, and after the above-described process is repeated, the processes in step S704 and step S705 are repeated until YES is determined in step S705.

On the other hand, if YES in step S705, that is, if the average offset value Ofm is equal to or smaller than the threshold value Oth, it is determined that the offset component Da in the offset tracking error signal SI has been sufficiently removed with the current coefficient k. You. Therefore, the current coefficient k = n / Ko
(N is the number of times NO is determined in step S705 +
The process ends with 1) set in the amplifier 14.

As described above, the optical disk drive ODP
In No. 2, it is possible to automatically determine the unique offset correction coefficient k for each optical disc 1 by using the initial offset correction function.

[0039]

However, the optical disk drive ODP2 provided with the above-described initial offset correction function.
In this case, it is necessary to forcibly displace the lens when determining the initial offset correction coefficient k. for that reason,
When the lens is forcibly displaced, the laser beam Lb
May protrude from the area of the optical disc 1 that can be automatically adjusted. Hereinafter, the problems in the optical disk drive ODP2 will be described in detail with reference to FIG. 9 showing the recording surface area of various optical disks.

The optical disk 1 is generally composed of a plurality of areas having different physical characteristics. For example, in a read-only disc such as a CD or MD, an information signal is stored in an intermittent groove called a pit formed on the recording surface of the disc 1.
There are two types of information carried by information signals: music information and text information. Character information is stored in a lead-in area Li inside the concentric circle of the optical disc 1, and music information is stored in a recording area Ar outside the lead-in area Li.
Further, outside the recording area Ar, there is a lead-out area Lo where no music information is recorded.

As shown in FIG. 9A, in the case of the read-only optical disk 1o, the optical disk 1 is surrounded by a concentric circle from the center of the optical disk 1, including pits from the start position of the lead-in area Li to the end position of the lead-out area Lo. The obtained donut-shaped area is called a pit area Rp. Also, the optical disk 1
Area from the center of the pit to the pit area Rp and the pit area Rp
No pits for storing information exist in an area on the outer peripheral side. These regions are called mirror surface regions Rm. Information is recorded in a program area Ap provided between the lead-in area Li and the lead-out area Lo in the pit area Rp.

As shown in FIG. 9B, when the optical disk 1 is a recording optical disk 1a such as an MD, the TOC information and the recording information are stored in areas having different physical characteristics. That is, the TOC information is stored in the lead-in area Li of the pit area Rp, as in the read-only optical disk 1o, so that the TOC information cannot be rewritten. On the other hand, music information is stored in the recordable area Ar. Further, there is a lead-out area Lo on the outside of which no recording information is written. These areas Ar and Lo are formed by grooves continuously formed on the recording surface of the disk. This series is called a groove. A donut-shaped area that is located on the outer peripheral side of the pit area and includes a groove from the start position of the recordable area to the end position of the lead-out area is called a groove area Rg. Also, M
Similarly to the read-only disc, the D recording / playback disc also has a mirror surface area Rm in which no information is stored.

In such a plurality of regions having different physical characteristics, the laser beam L serving as a basis for detecting a tracking error is determined.
The characteristic of b also differs for each region to be reflected. As a result, the value of the correction coefficient k of the tracking error signal also differs for each region. Therefore, as in the case where the unique offset correction coefficient k is automatically determined for each optical disc 1, it is necessary to determine the unique offset correction coefficient k in a region having different physical characteristics in one optical disc 1. is there.

However, when the objective lens 4 is displaced, the light condensed on the optical disc 1 may deviate from a target area and move to an area having different physical characteristics. In particular, in the MD recording / reproducing disc, the pit area is 1.5 mm, and the displacement range of the objective lens 4 is as follows.
For example, about 700 μm is required. In particular, as described above, the optical discs 1 have different amounts of eccentricity, and the position of the recording track fluctuates at high speed in accordance with the high-speed rotation of the optical disc 1. Therefore, the displacement of the objective lens 4 is controlled in the target area. As a result, a situation occurs in which the laser beam Lb cannot be focused on the same area. In such a case, correct tracking control cannot be performed because the offset is corrected based on the offset correction coefficient k, which is not suitable for the area irradiated with the laser beam Lb.

In order to avoid such a problem, a high-speed response in which the center of the laser optical axis is always focused on the center of the recording track even when the position of the recording track changes at high speed is possible in order to eliminate the high-speed offset fluctuation. There is a problem that the need for a simple traverse mechanism or an actuator mechanism for the objective lens causes an increase in cost.

The present invention has been made in order to solve the above-mentioned problem, and in a region where a laser beam Lb is irradiated on an optical disk, a unique offset correction coefficient k can be obtained for each region having different physical characteristics. An object of the present invention is to provide an optical disk drive.

[0047]

According to a first aspect of the present invention, a light beam is condensed by an objective lens on a recording surface of an optical disk, which is composed of regions having different physical characteristics, and the light beam reflected from the recording surface is converged. An optical disk drive that receives a light spot as a light spot by a light receiving element and tracks a light beam on a recording track on a recording surface based on the light spot, and shifts an objective lens substantially perpendicularly to a direction corresponding to the recording track. An optical pickup having an objective lens shift unit for causing the optical pickup to detect a relative position between the recording track and the condensed light beam to generate an offset tracking error signal including an offset amount and a tracking error amount; Light spot displacement detection means for detecting an amount of lens shift and generating an offset signal; The offset of the offset tracking signal is corrected based on the offset signal, the offset correction means for generating a first tracking error signal,
A forced lens displacement means for driving the objective lens shift means to displace the objective lens in a direction substantially perpendicular to the recording track, and an offset included in a tracking error signal after the objective lens is displaced by the forced lens displacement means. An offset correction modifying means for modifying the offset signal so as to reduce the offset signal; and an area discriminating means for discriminating, based on the reflected light beam, an area of the recording surface of the optical disk on which the light beam is focused, and an objective lens. As a result of the forced displacement of
When the light beam focusing area changes, the offset signal adjusting operation of the offset correction adjusting means is adjusted.

As described above, in the first aspect, when the objective lens is forcibly displaced and the light beam irradiates different areas on the recording surface of the optical disk, the correction of the offset signal is adjusted. Accordingly, offset correction appropriate for each of the regions having different physical characteristics can be performed.

In a second aspect based on the first aspect, the offset correction adjusting means multiplies the offset signal by multiplying the offset signal by a coefficient having a different value and includes the offset signal in the corrected tracking error signal with a coefficient having a different value. The offset amount is monitored, and a coefficient when the offset amount becomes zero is obtained as a correction coefficient of the offset signal.

As described above, in the second aspect, the optimum correction coefficient for the offset signal can be obtained based on the remaining offset amount when the offset signal is adjusted at predetermined intervals.

According to a third aspect, in the second aspect, when the converging area of the light beam changes as a result of displacing the objective lens, the forcible lens displacement means displaces the objective lens in the opposite direction. It is characterized by.

As described above, in the third invention, when the light beam irradiates a different area due to the forced displacement, the light beam is displaced in a direction opposite to the forced displacement, and then the offset signal correction coefficient is obtained. A correction coefficient in a target area can be obtained.

According to a fourth aspect, in the second aspect, when the converging area of the light beam changes as a result of displacing the objective lens, the forcible lens displacement means changes the displacement amount of the objective lens. Features.

As described above, in the fourth invention, when the light beam irradiates a different area due to the forced displacement, the amount of the forced displacement is reduced so that the light beam does not exceed the target area. Thus, a correction coefficient in the same target area can be obtained.

In a fifth aspect based on the second aspect, when the focusing area of the light beam changes as a result of displacing the objective lens, the optical pickup is moved in a direction corresponding to the recording track. It is characterized by the following.

As described above, in the fifth invention, when the light beam irradiates a different area due to the forced displacement, the optical pickup is moved so that the light beam does not exceed the target area. , The correction coefficient in the target area can be obtained.

According to a sixth aspect of the present invention, in the first aspect, when the converging area of the light beam changes as a result of displacing the objective lens, the offset correction modifying means sets a predetermined value set in advance. The offset signal is modified by multiplying the offset signal.

As described above, in the sixth aspect, when the light beam irradiates a different area due to the forced displacement, a predetermined value is set as a correction coefficient in the target area to speed up the processing. Can be achieved.

According to a seventh aspect based on the first aspect, the area discriminating means is configured such that a portion of the recording surface of the optical disk where the light beam is focused is an area formed by intermittent grooves or an area formed by continuous grooves. It is characterized by determining whether or not there is.

In an eighth aspect based on the first aspect, the area discriminating means determines whether a portion of the recording surface of the optical disc where the light beam is focused is a mirror area where no information signal is recorded. It is characterized in that it is determined whether or not this is an area where is recorded.

According to a ninth aspect, in the first aspect, when the focusing area of the light beam changes as a result of displacing the objective lens in the outer peripheral direction of the optical disk, the objective lens is moved in the inner peripheral direction of the optical disk. It is characterized by being displaced.

According to a tenth aspect, in the first aspect, when the focusing area of the light beam changes as a result of displacing the objective lens in the inner circumferential direction of the optical disc, the objective lens is moved in the outer circumferential direction of the optical disc. It is characterized by being displaced.

In an eleventh aspect based on the first aspect, the light spot obtained by receiving the light beam reflected from the recording surface is divided substantially perpendicularly to a direction corresponding to the recording track, and First dividing means for dividing the center area into an end area and a middle area, and second dividing means for further dividing the end area and the middle area substantially in parallel to a direction corresponding to the recording track. A light receiving element having a plurality of light receiving cells divided by the first dividing means and the second dividing means; and a tracking error detecting means receiving the light of the middle area divided by the second dividing means. The relative position between the recording track and the light beam is detected by performing an operation in accordance with the output of the light receiving cell of the light receiving cell. Light reception And detecting the relative displacement of the light spot on the light receiving element using the calculation according to the output of the LE.

According to a twelfth aspect, in the first aspect, when the converging area of the light beam changes as a result of displacing the objective lens, the forcible lens displacing means displaces the objective lens in the opposite direction. It is characterized by.

As described above, in the twelfth aspect, when the light beam irradiates a different area due to the forced displacement, the light beam is displaced in a direction opposite to the forced displacement, and then the correction of the offset signal is adjusted. In addition, offset correction appropriate for each of the regions having different physical characteristics can be performed.

According to a thirteenth aspect, in the first aspect, when the converging area of the light beam changes as a result of displacing the objective lens, the forcible lens displacement means changes the displacement amount of the objective lens. Features.

As described above, in the thirteenth aspect,
When the light beam irradiates a different area due to the forced displacement, the correction amount of the offset signal in the target area is adjusted by reducing the amount of the forced displacement so that the light beam does not exceed the target area. This makes it possible to perform offset correction appropriate for each of the regions having different physical characteristics.

According to a fourteenth aspect, in the first aspect, when the focusing area of the light beam changes as a result of displacing the objective lens, the optical pickup is moved in a direction corresponding to the recording track. It is characterized by the following.

As described above, in the fourteenth invention,
When the light beam irradiates different areas due to the forced displacement, the optical pickup is moved so that the light beam does not exceed the target area, and the correction of the offset signal is adjusted. Offset correction appropriate for each of the regions having the characteristics can be performed.

[0070]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIGS. 1, 2, 3, 4, and 5. FIG. With reference to FIG. 1, the structure of a PP-type optical disk drive ODDA according to the present embodiment will be described. The optical disk drive ODDA includes a turntable 2, a motor 3, an objective lens 4, a tracking actuator 5, a light receiving cell 9, adders 10 and 11, a light spot displacement detector 1
2. Tracking error detector 13, amplifier 14, offset corrector 15, and area offset corrector ACSR
including.

In the optical disk drive ODDA, the optical disk 1 is fixed to a turntable 2, and the turntable 2 is rotated by a motor 3 to rotate the optical disk 1. The objective lens 4 focuses the laser beam Lb emitted from the optical pickup (not shown) on the recording surface of the optical disc 1 and also focuses the laser beam Lb reflected on the recording surface on the light receiving element 9. . The light receiving element 9 is a light spot O of the focused laser beam Lb.
Various electric signals are output according to s. Light receiving element 9
Is a light receiving element generally used in the PP method, and its structure is as already described in detail with reference to FIG.

Therefore, as shown in FIG. 1, in the optical disk drive ODDA, according to the light spot Os,
The light receiving cell ROa outputs a first outer peripheral end area signal SROa, the light receiving cell RI outputs an outer peripheral middle area signal SRI, and the light receiving cell ROb outputs a second outer peripheral end area signal SROb.
Is output. Similarly, the light receiving cell LOa outputs a first inner peripheral side end area signal SLOa, the light receiving cell LI outputs an inner peripheral side middle area signal SLI, and the light receiving cell LOb outputs a second inner peripheral side end area signal SLOb. Is output.

The adder 10 outputs a first outer peripheral side end area signal SROa output from the light receiving cell ROa and the light receiving cell R
Second outer peripheral side end area signal SROb output from Ob
Are added to generate the outer peripheral side end area signal SRO. Similarly, the adder 11 adds the first inner peripheral end area signal SLOa output from the light receiving cell LOa and the second inner peripheral end area signal SLOb output from the light receiving cell LOb. , The inner peripheral side end area signal SLO.

The light spot displacement detector 12 subtracts the inner peripheral end area signal SLO from the outer peripheral end area signal SRO,
An end area signal SO which is a difference between the end area signals is generated. The end area signal SO represents an offset amount that is a relative displacement in a direction substantially perpendicular to a recording track between the light receiving element 9 and the light spot Os. In this sense, the end region signal SO is referred to as a first offset signal.

The amplifier 14 includes the light spot displacement detector 12
Amplifies the first offset signal SO, which is the output of the first offset signal SO, by a predetermined coefficient k to generate a weighted second offset signal SOk.

The tracking error detector 13 subtracts the inner peripheral side middle area signal SLI output from the light receiving cell LI from the outer peripheral side middle area signal SRI output from the light receiving cell RI to obtain the middle area signal. A middle area signal SI that is a difference is generated. The middle area signal SI includes an offset amount, which is a displacement in a direction substantially perpendicular to a recording track between the light receiving element 9 and the light spot Os, and a tracking error amount.
In this sense, the middle area signal SI is called an offset tracking error signal.

The offset corrector 15 calculates the second offset signal SOk from the offset tracking error signal SI.
Is subtracted to generate a tracking error signal St that does not include the offset amount.

The area offset corrector ACSR includes a tracking controller 6, an offset measuring device 16, a correction amount calculator 17, an outer lens displacement device 101, and an inner lens displacement device 10.
2. Area discriminator 103 and switches SW1 and S
W2. The tracking controller 6 is connected to the offset corrector 15, performs phase compensation, low-frequency compensation, and the like on the tracking error signal St input from the offset corrector 15, generates a tracking control signal Stc, and Selection signal Ss1 and second selection signal Ss2
Generate

The first selection signal Ss1 is supplied to the switch SW1
Is a drive signal for connecting either the output port of the outer lens displacement unit 101 or the output port of the inner lens displacement unit 102 to the output port of the switch SW1. Similarly, the second selection signal Ss2 is supplied to the switch SW
2 is a drive signal for selectively driving either the output port of the switch SW1 or the output port of the tracking controller 6 to the output port of the switch SW2.

That is, the switch SW1 is connected to the tracking controller 6, and the input first selection signal Ss1
, The outer peripheral lens drive signal Sos, which is an output from the outer lens displacer 101, and the inner lens displacer 1
The lens driving signal Sis in the inner peripheral direction, which is an output from the second lens 02, is selectively supplied to the switch SW2. Then, the switch SW2 is connected to the tracking controller 6, and based on the input second selection signal Ss2, the switch SW1
The lens driving signal Sos or the lens driving signal Sis in the inner peripheral direction input from the
Is selectively supplied to the tracking actuator 5.

The area discriminator 103 outputs the laser beam Lb
The area of the optical disk 1 to which the is irradiated is determined. Such a determination of the irradiation area of the optical disk 1 can use, for example, a method described in Japanese Patent Application No. 07-171843 “optical disk device”. In this method, it is determined whether the irradiation area of the laser beam Lb on the optical disc 1 is the pit area Rp, the groove area Rg, or the mirror area Rm where no recording is performed, using the difference between the RF signals. Specifically, the RF signal in the pit region contains a high-frequency component, but the RF signal in the groove region Rg
The region is determined by performing signal processing focusing on the fact that the F signal does not include a high frequency component.

The tracking actuator 5 applies the laser beam Lb to the optical disk based on one of the tracking control signal Stc, the outer lens driving signal Sos, and the inner lens driving signal Sis, which are selectively supplied from the switch SW2. The objective lens 4 is moved to the recording track T so as to follow the first recording track Tr (not shown).
r, that is, in the radial direction of the optical disc 1. More specifically, the tracking actuator 5 displaces the laser beam Lb in the outer peripheral direction of the optical disc 1 based on the outer peripheral lens drive signal Sos, and converts the laser beam Lb into the inner optical disc 1 based on the inner peripheral lens drive signal Sis. Displace in the circumferential direction.

The offset measuring device 16 tracks the offset component Da that cannot be removed from the offset tracking error signal SI in the second offset signal SOk obtained by correcting the first offset signal SO by the amplifier 14 based on the current coefficient k. The residual offset amount Of is measured from the error signal St, and the offset amount signal Sof is generated. The correction amount calculator 17 calculates the offset amount signal Sof.
, A coefficient correction signal Sk for obtaining an appropriate coefficient k for setting the value of the residual offset amount Of to zero is generated.

The operation of the optical disk drive ODDA will be described below with reference to the flowchart shown in FIG. In this specification, an example of an area offset correction in a pit area Rp of an MD recording / reproducing disc as the optical disc 1 will be described. Pit area R
In order to perform area offset correction on p, first, the laser beam Lb is initially set in a pit located on the inner peripheral side of the optical disc (MD) 1 using a known means such as a traverse motor and a pit area detection switch. The optical pickup is positioned so as to irradiate the region Rp. For the sake of simplicity, the direction of lens displacement is set to the outer peripheral side, and the displacement is set to ± 350 μm. In such an initial state, the area offset correction operation by the area offset corrector ACSR is started.

In step S201, the tracking controller 6 outputs a first selection signal Ss1 for instructing selection of the outer peripheral lens displacement unit 101 and a second selection signal Ss2 for instructing selection of an output port of the switch SW1. On the basis of these selection signals Ss1 and Ss2, the outer peripheral lens drive signal S output from the outer lens displacement unit 101
os is supplied to the tracking actuator 5 via the switch SW1 and the switch SW2. result,
After the objective lens 4 is displaced by a predetermined amount in the outer peripheral direction,
The process proceeds to the next step S202. In this example,
In this step, the objective lens 4 is displaced to the outer peripheral side in order to perform area offset correction in the pit area Rp of the optical disc (MD) 1. However, it goes without saying that the displacement direction of the objective lens 4 may be either the outer peripheral side or the inner peripheral side depending on the type of the optical disc 1 to be subjected to the area offset correction and the area thereof.

In step S202, the area discriminator 103
Thus, it is determined whether the portion of the optical disc 1 where the laser beam Lb is irradiated is the pit region Rp, the groove region Rg, or the mirror surface region Rm. Thereafter, the process proceeds to step S203.

In step S203, step S201
It is determined whether or not the type of the irradiation area of the optical disc 1 has changed as a result of the displacement in the outer peripheral direction in the step (1). Then, when the irradiation region has been changed to the groove region Rg or the mirror surface region Rm, it is determined as YES, and the processing is performed in step S20.
Proceed to 4. On the other hand, if there is no change in the irradiation area, the process proceeds to step S205.

However, in this example, the laser beam Lb is initially set to irradiate the pit region Rp located on the inner peripheral side of the optical disk (MD) 1 as described above. Therefore, the area that can be changed by displacing the objective lens 4 to the outer peripheral side is, as shown in FIG. 9B, the irradiation area is not the mirror area Rm but the groove area Rm.
g. That is, in this example, when the irradiation area of the optical disc 1 changes from the pit area Rp to the groove area Rg, the processing of step S204 is executed.

In step S204, the switch SW1 generates a first selection signal Ss1 for instructing to select the inner lens driving signal Sis output from the inner lens displacement unit 102. In step S201, since the switch SW2 remains connected to the output of the switch SW1, the inner peripheral direction lens driving signal Sis is output from the inner peripheral lens displacement unit 102 to the tracking actuator 5, and the objective lens 4 In the direction. As a result, the laser beam Lb irradiates the pit region Rp of the optical disc 1. Then, the process proceeds to step S2
Go to 05.

In step S205, FIG. 10 and FIG.
The correction coefficient k of the tracking error signal is determined by the same method as the initial offset correction method performed by the optical disk drive ODP2 described with reference to FIG.
Then, the process ends.

Here, the length of the pit area in the direction perpendicular to the recording track is 1.5 mm, and the area discriminator 103 moves the objective lens 4 in the inner circumferential direction by 3 mm.
Assuming that it is 0.7 mm which is twice as large as 50 μm, it is 0.8 mm beyond the pit region to reach the mirror surface region further on the inner peripheral side.
There is enough room. Here, even if the eccentric amount of the disk is set to, for example, 0.2 mm, it does not reach the mirror surface area.

As described above, in the present embodiment, the outer peripheral lens displacement mechanism (6, 101, SW1, SW2) for supplying the drive signal SoS to the tracking actuator 5 to displace the objective lens 4 in the outer peripheral direction, An inner lens displacement mechanism (6, 102, SW1, SW2) for supplying a drive signal Sis to the tracking actuator 5 to displace the objective lens 4 in the inner peripheral direction; By providing the area discriminator 103 for discriminating the area to which the position belongs, the objective lens 4
Are displaced, the regions having different physical properties (Rp,
Even when light is converged on (Rg, Rm), the offset correction coefficient k can be appropriately corrected according to the irradiation area by displacing the objective lens 4 in the opposite direction. As a result, it is possible to automatically adjust the tracking offset even in a region having severe physical restrictions such as a pit portion of a recording / reproducing disc such as an MD.

In the present embodiment, it has been described that the pit region Rp and the groove region Rg are determined by displacing the objective lens 4 toward the outer periphery. However, the objective lens 4 is displaced toward the inner periphery of the disk. Alternatively, the determination of the mirror surface region Rm on the outer peripheral side may be performed. here,
The determination as to whether the area is the mirror area Rm where no information signal is recorded or the area where the information signal is recorded (Rp or Rg) is based on the fact that no RF signal or tracking error signal is output in the mirror area. Can be easily determined.

Referring to flowcharts shown in FIGS. 3, 4, and 5, a modification of the area offset coefficient correction method described with reference to FIG. 2 in the optical disk drive ODDA according to the present embodiment will be described. .

In the flowchart shown in FIG. 3, step S204 of the flowchart shown in FIG. 2 is replaced with step S904. That is, step S2
01 to the step S203 are performed as described above,
In step S203, it is determined that there is a change in the area, and the process proceeds to step S904.

In step S904, the amount of displacement of the objective lens 4 is set smaller than the predetermined amount of displacement specified in step S201. Then, the objective lens 4 is moved by the newly set smaller displacement amount in step S20.
1 is moved from the initial state position to a position on the outer peripheral side. Then, the process proceeds to step S205.

In step S205, step S201
The correction coefficient k of the tracking error signal is determined at a position on the inner peripheral side of the position in the above. Then, the process ends.

In the method shown in the flowchart of FIG.
Using the area discriminator 103, it is determined whether or not the object lens has moved to an area having physical characteristics different from that before the displacement, and when the object lens has moved to a different area, the objective lens is displaced in a direction opposite to the moving direction. On the other hand, in the present modified example, the correction coefficient k of the tracking error signal is obtained by reducing the displacement of the objective lens so as not to move to a different area.

In the flowchart shown in FIG. 4, step S204 of the flowchart shown in FIG. 2 is replaced with step S1004. That is, the processing from step S201 to step S203 is performed as described above, and it is determined in step S203 that there is a change in the area, and the processing proceeds to step S1004.

In step S1004, the optical pickup is moved substantially perpendicularly to the direction corresponding to the recording track of the optical disk 1, and the same area as that irradiated by the laser beam Lb before the displacement in step S201 is performed. The position of the objective lens 4 is returned so as to irradiate. Then, the process proceeds to step S205.

As described above, in this modified example, when the irradiated portion of the laser beam moves to a region having physical characteristics different from those before the displacement, as shown in FIG. Instead of displacing the objective lens
By moving the optical pickup using an optical pickup moving mechanism for moving the pickup substantially perpendicular to the direction corresponding to the recording track, the objective lens is returned to the area before the displacement, and the correction coefficient k of the tracking error signal is corrected. Can be requested.

Further, in the flowchart shown in FIG. 5, step S204 of the flowchart shown in FIG.
Has been replaced by step S1104. That is, the processing from step S201 to step S203 is performed as described above, and it is determined in step S203 that there is a change in the area, and the processing proceeds to step S1004.

In step S1104, a predetermined value set in advance is set as the correction coefficient k of the tracking error signal, and the process ends.

As described above, in this modification, when the irradiated portion of the laser beam Lb moves to a region having physical characteristics different from those before the displacement, instead of obtaining the correction coefficient k of the tracking error signal, a preset value is set. The predetermined value is used as the correction coefficient k. Accordingly, when the relative eccentricity between the optical disk 1 and the optical disk drive ODDA is large, and it is difficult to obtain the correction coefficient k of the tracking error signal by the method shown in FIGS. 2, 3, and 4, Is an effective solution.

As described above, in this specification,
Although the case where the optical disk 1 is an MD recording / reproducing disk has been described, it is apparent to those skilled in the art from the above description that the present invention can be applied to all optical disks having regions having different physical characteristics. Further, it has been described that the pit region Rp and the groove region Rg are determined by displacing the objective lens 4 to the outer peripheral side. It can also be realized by a method of determining Rm. Here, the mirror area R where no information signal is recorded
m or the area Rp or Rp where the information signal is recorded
The determination as to g can be easily made based on the fact that no RF signal or tracking error signal is output in the mirror region Rm. Further, as described with reference to FIG. 2, FIG. 3, and FIG. 4, when it is determined in step S203 that there is a change in the area, the process proceeds to step S20, respectively.
After the objective lens or the optical pickup is displaced in steps S904, S904, and S1004, the correction coefficient k is determined in step S205. However, this step S
Instead of the correction coefficient k by 205, the processing of step S1104 described with reference to FIG. 5 may be executed to set a predetermined value to the correction coefficient k.

[Brief description of the drawings]

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

FIG. 2 is a flowchart showing an operation of the optical disk drive shown in FIG.

FIG. 3 is a flowchart showing a modified example of the operation of the optical disk drive shown in FIG.

FIG. 4 is a flowchart showing a different operation of the optical disk drive shown in FIGS. 2 and 3;

FIG. 5 is a flowchart showing still another operation of the optical disk drive shown in FIGS. 2, 3, and 4;

FIG. 6 is an explanatory diagram of a structure of a light receiving surface of a light receiving element generally used in a push-pull method.

FIG. 7 is an explanatory diagram of a relationship between a position of a light spot where reflected light from a disc is connected to a light receiving element shown in FIG. 6 and a displacement of an objective lens in a push-pull method.

FIG. 8 is an explanatory diagram showing a relationship between various signals observed by the optical disk drive shown in FIG. 1 and displacement of an objective lens.

FIG. 9 is an explanatory diagram of a recording surface area in various optical disks.

FIG. 10 is a block diagram showing a structure of a conventional optical disk drive based on an improved PP method for reducing an offset of a tracking error signal when an objective lens is displaced in the PP method.

11 has a function of automatically determining a tracking error correction coefficient added to the optical disc drive shown in FIG. 10;
FIG. 9 is a block diagram showing the structure of a conventional optical disk drive.

12 is a flowchart showing the operation of the optical disk drive shown in FIG.

[Explanation of symbols]

ODDA optical disk drive ACSR area offset corrector 1 optical disk 2 turntable 3 motor 4 objective lens 5 tracking actuator 6 tracking controller 9 light receiving element 12 light spot displacement detector 13 tracking error detector 14 amplifier 15 offset corrector 16 offset measurer 16 17 Correction amount calculator 101 Outer lens displacement unit 102 Inner lens displacement unit 103 Area discriminator SW1, SW2 Switch 7 Light spot 9 Light receiving element ROa, ROb, LOa, LOb Light receiving cell RI that receives the end area of the light spot RI, LI Light receiving cell for receiving light in the middle area of the light spot Lv Dividing line for dividing the light receiving element in the vertical direction to the recording track Lp Dividing line for dividing the light receiving element in the horizontal direction to the recording track 1o Read-only optical disc 1a Recording Optical disk Rp pit area Rg groove region Rm mirror surface area Ap program area Ar recordable area Li lead-in area Lo lead-out area

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D117 AA02 BB04 CC01 CC04 CC07 EE18 FF21 FF25 FF28 5D118 AA13 AA21 AA27 BA01 BF02 BF03 CA23 CC05 CD03 CD11 CF08 DA35 DC03

Claims (14)

[Claims] 1. A light beam is condensed by an objective lens on a recording surface formed of regions having different physical characteristics of an optical disk, and the light beam reflected from the recording surface is received as a light spot by a light receiving element and received by the light receiving element. An optical disk drive for tracking the light beam on a recording track on the recording surface based on a spot, comprising: an objective lens shift unit that shifts the objective lens substantially perpendicularly to a direction corresponding to the recording track. A pickup; a tracking error detecting means for detecting a relative position between the recording track and the condensed light beam to generate an offset tracking error signal including an offset amount and a tracking error amount; and a shift amount of the objective lens. Light spot displacement detecting means for detecting and generating an offset signal; An offset correction unit that corrects an offset of the tracking signal based on the offset signal to generate a first tracking error signal; and drives the objective lens shift unit to drive the objective lens shift unit in a direction substantially perpendicular to the recording track. Forced lens displacement means for displacing the objective lens; and offset correction modifying means for modifying the offset signal so that the offset included in the tracking error signal after the objective lens is displaced by the forced lens displacement means is reduced. And, based on the reflected light beam, a region discriminating unit for discriminating a region of the recording surface of the optical disc on which the light beam is focused, and as a result of the forced displacement of the objective lens, When the focusing area changes, the offset signal adjusting operation of the offset correction adjusting means is performed. Optical disk drive, wherein the adjusting. 2. The offset correction and correction means multiplies the offset signal by a coefficient having a different value to correct the offset signal, and monitors an offset amount included in the corrected tracking error signal with a coefficient having a different value. 2. The optical disk drive according to claim 1, wherein a coefficient when the offset amount becomes zero is obtained as a correction coefficient of the offset signal. 3. The method according to claim 2, wherein the displacement of the objective lens results in a displacement of the objective lens in a reverse direction when a focusing area of the light beam changes. 3. The optical disk drive according to 2. 4. The method according to claim 2, wherein the displacement of the objective lens changes the amount of displacement of the objective lens when the focus area of the light beam changes as a result of the displacement of the objective lens. An optical disk drive according to claim 1. 5. The optical pickup according to claim 1, wherein the optical pickup is moved in a direction corresponding to the recording track when a focusing area of the light beam changes as a result of displacing the objective lens. Item 3. An optical disk drive according to item 2. 6. When the converging area of the light beam changes as a result of displacing the objective lens, the offset correction modifying means multiplies the offset signal by a predetermined value set in advance. 2. The optical disk drive according to claim 1, wherein the offset signal is modified. 7. The area discriminating means judges whether a portion of the recording surface of the optical disc where the light beam is focused is a region formed by intermittent grooves or a region formed by continuous grooves. The optical disk drive according to claim 1, wherein: 8. The area discriminating means, wherein a portion of the recording surface of the optical disc where the light beam is focused is a mirror surface area where no information signal is recorded or an area where an information signal is recorded. 2. The optical disk drive according to claim 1, wherein it is determined whether or not there is an optical disk. 9. When the focusing area of the light beam changes as a result of displacing the objective lens in the outer peripheral direction of the optical disc, the objective lens is displaced in the inner peripheral direction of the optical disc. The optical disk drive according to claim 1. 10. When the focusing area of the light beam changes as a result of displacing the objective lens in the inner peripheral direction of the optical disc, the objective lens is displaced in the outer peripheral direction of the optical disc. The optical disk drive according to claim 1. 11. A light spot obtained by receiving a light beam reflected from the recording surface is divided substantially perpendicularly to a direction corresponding to the recording track, and the light spot is divided with respect to a center of the light spot. A first dividing unit that divides the end region and the middle region into a region and a middle region, and a second dividing unit that further divides the end region and the middle region substantially in parallel with a direction corresponding to the recording track; A light receiving element having a plurality of light receiving cells divided by the dividing means and the second dividing means, wherein the tracking error detecting means receives the light of the middle area divided by the second dividing means The relative position between the recording track and the light beam is detected by performing an operation in accordance with the outputs of the plurality of light receiving cells. Optical disk drive according to claim 1, characterized in that for detecting the relative displacement of the light spot on the light receiving element using the operation in accordance with the output of the plurality of light receiving cells for receiving light end regions. 12. When the converging area of the light beam changes as a result of displacing the objective lens, the forcible lens displacing means displaces the objective lens in a reverse direction. 2. The optical disk drive according to 1. 13. The method according to claim 1, wherein when the converging area of the light beam changes as a result of displacing the objective lens, the forcible lens displacement means changes the displacement of the objective lens. An optical disk drive according to claim 1. 14. The optical pickup according to claim 1, wherein when the converging area of the light beam changes as a result of displacing the objective lens, the optical pickup is moved in a direction corresponding to the recording track. Item 2. An optical disk drive according to item 1.