JP2002025090A - Optical disc apparatus and tilt correction method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To perform tilt correction with a simple configuration without using a tilt sensor. A tracking servo by a tracking servo unit is turned off by a switch, a traverse signal is supplied to a level detection unit, and a traverse level from the level detection unit is supplied to a controller. The controller 9 drives the tilt correction device 3 of the optical pickup 2 via the drive unit 14. The inclination correction value is changed by adding or subtracting a predetermined difference value to or from the initial value of the inclination correction value. The level of the traverse signal when the tilt correction value is changed is detected, and a tilt correction value that causes the maximum traverse signal level is obtained. A tilt correction value is obtained at each of a plurality of positions on the optical disc, and a correction value table in which the position and the tilt correction value are associated is created.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical disk apparatus for recording and / or reproducing information by using an optical disk, and more particularly to a tilt correction between a disk and an optical axis of an optical pickup.

[0002]

2. Description of the Related Art As the recording density of an optical disk increases, the diameter of an irradiation light beam on the disk becomes smaller. The spot diameter of a light beam (laser beam) has the following relationship with the wavelength of a light source such as a laser and the NA (aperture ratio) of an objective lens.

Wa∝kλ / NA Wa: spot diameter, λ: light wavelength, k: constant

[0004] The light wavelength λ is determined by the light source, but an arbitrary wavelength cannot be selected by a laser or the like, and it takes time to commercialize a light source of a shorter wavelength required for high density. . For this reason, a light source having a wavelength that is already in practical use is used, and the NA of the objective lens is increased in order to realize a desired spot diameter. However, when the NA of the objective lens is increased and the light beam is irradiated not obliquely to the recording surface of the disk but at an angle, the return light has an aberration and the recording / reproducing characteristics deteriorate. In some cases, recording / reproduction may not be possible. For example, tilt occurs due to the warp of the optical disk. For this reason, an optical disk apparatus using an optical pickup using an objective lens having a large NA is provided with a tilt correction device to correct the tilt (so-called radial skew) between the optical axis of the optical pickup and the recording surface of the disk in the disk radial direction. Is made.

As an example of a tilt correcting device, there is a device which mechanically corrects a relative tilt between an optical block including an optical pickup and a disk rotating unit on which a disk is fixed (chucking). As another example, there is a method in which the movable axis of the objective lens is increased and the objective lens is tilted, thereby controlling the irradiation angle of the beam to the disk and correcting the tilt. As still another example, there is a method of arranging an element capable of correcting optical aberration such as a liquid crystal element in an optical path of an optical pickup and optically correcting aberration.

There are several methods for detecting the inclination required for controlling the inclination correction device. The first detection method is a method of arranging an inclination sensor including a light emitting diode and a light receiving sensor near an optical pickup and detecting the inclination by reflected light. Second
There is a method of detecting the inclination based on the reproduction signal quality such as the reproduction jitter component of the recorded signal.

Further, there is a disk in which grooves (guide grooves) are formed in a concentric or spiral shape in advance. As the groove, there is a double spiral disk such as MD data 2 in which meandering (so-called wobbling) and non- meandering (straight) ones are alternately arranged. In the case of this disc, the level of the wobble reproduction signal on the inner circumference side and the level of the wobble reproduction signal on the outer circumference side change due to the deformation of the irradiated light beam. Therefore, the inclination can be detected from the difference between these wobble signals. (Third detection method).

[0008]

Since the above-mentioned first detection method requires a light emitting diode and a light receiving sensor, it may hinder miniaturization of equipment. The second detection method has a disadvantage that the time required to detect the inclination becomes long, and cannot be applied to a portion where a signal is not recorded. The third detection method complicates the detection circuit, requires a track jump to perform the detection, increases the detection time, and further has the influence of variations in the manufacturing process of the disk, such as the wobble reproduction signal. There are problems such as being affected by S / N.

Further, when the inclination is large, the recording signals cannot be read by the second and third detection methods. For this reason, the level of the inclination detection signal may decrease, and reading of the initial state may be difficult. In the case of a disk in which an address is recorded by wobbling the groove, the destination address cannot be read,
It can also become inoperable.

Accordingly, it is an object of the present invention to provide an optical disk device and a tilt correction method which can solve these problems.

[0011]

According to a first aspect of the present invention, there is provided an optical disk apparatus for recording or reproducing information by irradiating a signal recording surface of an optical disk with a light beam of an optical pickup. Tilt correction means for correcting aberrations caused by the light beam not being irradiated perpendicularly to the surface, tracking servo means for controlling the light beam to trace on the track, and a plurality of tracks with the tracking servo turned off. Or means for detecting the level of the traverse signal generated by the light beam spot crossing the groove,
An optical disc device characterized in that a tilt correction value for a tilt correcting means is obtained based on a level of a detected traverse signal.

According to an eighth aspect of the present invention, there is provided a tilt correction method in an optical disk apparatus for recording or reproducing information by irradiating a signal recording surface of an optical disk with a light beam of an optical pickup. With the tracking servo that controls to trace on the top turned off, the level of the traverse signal generated by the light beam spot crossing multiple tracks or grooves is detected, and based on the detected level of the traverse signal, This is a tilt correction method characterized by obtaining a tilt correction value.

According to the above-described invention, since the inclination is corrected based on the level of the traverse signal, no sensor is required and only a level detection circuit needs to be added. Also,
According to the present invention, inclination correction can be performed regardless of the presence or absence of a recording signal, and can be applied to an unrecorded portion of a disk.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
Hereinafter, description will be made with reference to the drawings. One embodiment is an example in which the present invention is applied to an optical disk reproducing device. However, the present invention can also be applied to an optical disc recording / reproducing apparatus using a recordable optical disc such as a write-once disc or a rewritable disc. More specifically, the present invention relates to a CD (Compact Disc), a CD
-ROM, CD-R (Recordable), CD-RW (ReWrita
ble) and other optical disks of the CD family, DVDs (Digital
Versatile Disc or Digital Video Disc) video,
DVD-ROM, DVD-R (Recordable), DVD-R
Optical disk of DVD family such as AM, MD (Mini Di
sc), MD-DATA, MD-DATA2, etc., which can be applied to optical disks of the MD family.

FIG. 1 shows the overall configuration of one embodiment,
1 is an optical disk. 2 is an optical pickup,
The optical pickup 2 has a laser source and an optical system,
The information recorded on the optical disk 1 is read by irradiating the optical disk 1 with a laser beam and irradiating the light receiving element with the return light. Also,
The optical pickup 2 includes a tilt correction device, for example, a liquid crystal correction plate 3 that is disposed in an optical path and can correct optical aberration. The optical disc 1 is driven to rotate at a constant linear velocity (CLV) or a constant angular velocity (CAV) by a spindle motor (not shown). Further, the optical pickup 2 can be transported in the radial direction of the disk by a thread motor 4.

A reproduction signal from the optical pickup 2 is supplied to an RF amplifier 5. The RF amplifier 5 generates, for example, a tracking error signal and a focus error signal together with the RF signal by calculating the output of the quadrant light receiving element. The tracking error signal and the focus error signal are signals whose levels change in an S-shape according to the amount of error, for example. The reproduction RF signal is supplied to the reproduction signal processing unit 6, and reproduction data is obtained from the reproduction signal processing unit 6. The tracking error signal is supplied to the tracking servo unit 7, and the focus error signal is supplied to the focus servo unit 8.

The tracking servo unit 7 controls the optical pickup 2 so that the spot of the irradiation light from the optical pickup 2 follows the signal track of the optical disk 1. The focus servo unit 8 controls the optical pickup 2 so that the irradiation light is focused on the recording surface of the optical disc 1. The tracking servo unit 7 and the focus servo unit 8 are controlled by a controller 9.

The tracking servo section 7 is provided with a switch 10 for controlling on / off of the tracking servo. The switch 10 is controlled by the controller 9. Reference numeral 11 denotes a level detection unit that detects the level of a traverse signal during tracking servo (a tracking error signal when the tracking servo is turned off). A detection output (traverse level) of the level detector 11 is input to the controller 9.

Reference numeral 12 denotes a thread servo unit for controlling the thread motor 4 so that the irradiation light from the optical pickup 2 follows the signal track of the optical disk 1 or the movement control for access is performed by the thread motor 4. . The thread servo unit 12 is controlled by the controller 9.

The controller 9 controls the entire operation of the optical disk device, and writes necessary information to the memory 13 and reads information from the memory 13. Further, the controller 9 includes the level detector 1
An inclination correction value is acquired from the traverse level received from 1 and the inclination correction value is stored in the memory 13. As will be described later, a tilt correction value is obtained at a plurality of positions on the disk, a table in which the position information and the tilt correction value are associated is created, and the table is stored in the memory 13.
At the time of tilt correction, the tilt correction value read from the memory 13 is supplied from the controller 9 to the drive unit 14. The drive unit 14 converts the tilt correction value into a drive signal corresponding to the tilt correction device 3.

FIG. 2 shows a waveform of a traverse signal obtained from the tracking servo unit 7 when the switch 10 is turned off and the tracking servo is turned off. The traverse signal is a signal generated when an irradiation light beam spot from the optical pickup 2 crosses a track (a guide groove, a pit row, or the like) on the recording surface of the optical disc 1, and is a tracking servo error signal. In general, spots cross 10 to 20 tracks due to eccentricity of the optical disk itself, eccentricity after chucking, and the like, even when the optical pickup 2 is stationary. Generally, the traverse signal is a compression wave synchronized with the rotation cycle of the disk.

For example, the center level of the traverse signal occurs when the center of the spot is located at the center of the track. When the center of the spot is displaced inward from the center of the track, the center level is lower than the center level. When the center of the spot is displaced from the center of the track toward the outer periphery, the level becomes larger than the center level. The level detector 11 detects a peak-to-peak value of the traverse signal as a traverse level, and supplies the detected traverse level to the controller 9. The level detector 11 may detect the average value of the traverse signal. When the tracking servo is turned on, the tracking servo unit 7 controls the position of the objective lens of the optical pickup 2 in the track direction, and performs feedback control so that the center of the beam spot coincides with the center of the track. , The tracking error signal has a value substantially at the center level.

Next, a method of obtaining a tilt correction value performed by the controller 9 will be described with reference to the flowchart of FIG. When obtaining the inclination correction value, the thread servo unit 12 is controlled by the controller 9, and the optical pickup 2 is moved on the optical disk 1 from which the correction value is to be obtained in the radial direction of the disk. The focus servo by the focus servo unit 8 is turned on, and the switch 1
When 0 is turned off, the tracking servo is turned off.

In the first step S1, the controller 9 initializes the correction value Cs to the initial value C0. This inclination correction value C0 is supplied to the inclination correction device 3. In step S2, the controller 9 reads the level (traverse level) of the traverse signal from the level detection unit 11 and stores it in a register. The traverse level read and stored in step S2 is set to L0 = Lr.

In step S3, the inclination correction value supplied to the inclination correction device 3 is changed. A predetermined difference value Cd set in advance is added to the original value (initial value Cs). In step S4, the traverse level from level detector 11 is read. The traverse level read in step S4 is set to Ls = Li.

Next, in step S5, the stored traverse level (ie, previous value) L0 is compared with the read traverse level Ls. L0 <L
When the relationship of s is established, in step S6,
The traverse level Ls is stored in the register. Then, the difference value Cd is added in the correction value change step S7, the traverse level Li is read (step S8), and compared with the previous value L0 in step S9. If it is determined in step S9 that the relationship of L0 ≦ Ls is not established, in step S10, the correction value Cmax (= Cs−Cd) that maximizes the traverse level.
Is obtained.

If the read level Ls is equal to or greater than the previous value L0 in step S9, the process returns to step S6. Then, after step S6 for storing the traverse level as the previous value, step S7 for changing the correction value, and step S8 for reading the traverse level, a level comparison is made in step S9. The process of changing the correction value is performed until the relationship of L0 ≦ Ls does not hold.

If the relationship L0 <Ls is not established in step S5, the traverse level Ls is stored in the register in step S11. Then, in step S12 of the correction value change, the difference value Cd is subtracted, and the traverse level Li is read (step S1).
3) In step S14, it is compared with the previous value L0. If it is determined in step S14 that the relationship of L0 ≦ Ls is not established, in step S15, the correction value Cmax (= Cs + C) at which the traverse level is maximized.
d) is obtained.

If it is determined in step S14 that the read level Ls is equal to or greater than the previous value L0, the process proceeds to step S11.
The process returns to. Then, step S11 of storing the traverse level as the previous value, and step S1 of changing the correction value
2. After step S13 for reading the traverse level, the level is compared in step S14. L0 ≦ L
The process of changing the correction value is performed until the relationship of s does not hold.

Referring to FIG. 4, a method of creating a correction value table when a disc is inserted into the apparatus will be described. The correction value table is stored, for example, on the memory 13. The controller 9 determines in step S21 whether or not the optical disk has been inserted. When the optical disk is inserted, the rotation of the optical disk is started in step S22.
Then, in step S23, the focus servo by the focus servo unit 8 is turned on. Step S2
At 4, the value of the pointer for creating the correction value table is initialized.

In step S25, the tracking servo is turned off, and in step S26, the optical pickup 2 is moved to the approximate position indicated by the correction value acquisition pointer. In step S27, the inclination correction value Cmax is obtained by the method described above with reference to FIG. As an example,
As the value of the correction value acquisition pointer increases, the correction value acquisition point changes from the inner circumference to the outer circumference of the optical disc.

In step S28, the tracking servo is turned on, and the normal operation starts at the correction value acquisition point. In step S29, the disk address Ap
Is read. For example, address information recorded as groove wobble information is read. Address Ap
With the acquired inclination correction value Cp, the controller 9 registers the correction value in the memory (step S30). Then, in step S31, the correction value acquisition pointer is updated, and in step S32, it is determined whether a predetermined end point has been reached. When the end point is reached, the process of creating the correction value table ends. Otherwise, step S2
The process returns to 5 (turning off of tracking servo). Then, the operation after step S26 is repeated.

FIG. 5 shows an example of the inclination correction value table created by the processing of FIG. .., Cn are set corresponding to the addresses A1, A2, A3,..., An on the optical disk. As described above, even with one optical disc, an appropriate tilt correction value is set at a plurality of positions on the optical disc. For example, when n = 4, as shown in FIG. 6, four areas centered on addresses A1, A2, A3, and A4 are set on the program area of the optical disc 1, and in each area, Tilt correction value C
1, C2, C3, and C4 are used, respectively. Increasing the number of areas can improve the accuracy of tilt correction. In addition, other than the address at which the correction value is obtained, a tilt correction value obtained by interpolation such as linear interpolation may be used.

When the disc is inserted, operations such as reading the TOC (Table Of Contents) in the innermost peripheral area are also performed. The normal operation performed when this disc is inserted,
Any of the operations of creating the inclination correction table may be performed first. For example, a tilt correction operation is performed first.

The tilt correction value created as described above is used in operations such as recording / reproduction. In one embodiment, even after the correction value table is once created, a process of acquiring a tilt correction value is performed if necessary. With reference to FIG. 7, the tilt correction operation in the reproduction operation will be described. It is assumed that the inclination correction value table (FIG. 5) has already been created, and the optical pickup 2 is waiting at the reproduction start point. In step S41, the controller 9 waits for reproduction to be started by operating a switch or the like.

When the reproducing operation starts, the tracking servo is turned on in step S42, and the beam spot traces the track of the optical disk 1. Step S
At 43, the controller 9 reads the address recorded on the optical disk 1. In step S44, it is determined whether the correction value needs to be reacquired. If the reproduction address can be read, it is determined in step S44 that re-acquisition is unnecessary, and the process proceeds to step S45.

In step S45, it is determined whether or not the inclination correction value needs to be updated by comparing the address read in step S43 with the address in the correction value table. If no update is necessary, the process returns to step S42. If an update is necessary, in step S46, a new inclination correction value is obtained (read) from the correction value table. Then, in step S47, the read inclination correction value is supplied to the inclination correction device 3 via the drive unit 14. Then, the process proceeds to step S
Return to 42.

The operation from step S42 to step S47 is a normal reproduction operation. If not, step S44
In the case where a problem such as the inability to obtain the reproduction address occurs, it is determined that the correction value needs to be obtained again, and the process branches to step S48. For reacquisition, all the correction values in the table may be reacquired, or an abnormal correction value may be partially reacquired. In step S48, a retry counter is initialized.

Next, in step S49, the tracking servo is turned off, and the traverse level can be read. Then, a new tilt correction value is obtained in step S50. As described above with reference to FIG. 3, the inclination correction value is obtained. Then, the tracking servo is turned on in step S51, and the address is acquired again in step S52.

In step S53, it is determined whether a retry is necessary as in step S44. If it is determined that retry is unnecessary, the correction value table is updated in step S54, and the process returns to step S42. In the subsequent processing, a tilt correction operation is performed based on the updated correction value table. If a problem such as the inability to read the address occurs in step S52, the process proceeds to step S52.
At 53, it is determined that a retry is needed.

If it is determined that a retry is necessary, step S
At 55, the retry counter is updated. Specifically, the counter is incremented or decremented. In step S56, it is determined whether the retry has been completed based on the count value of the retry counter.
That is, if a normal operation cannot be performed even after performing a predetermined number of retries, it is determined that the apparatus is abnormal, an abnormality process is performed in step S57, and the reproduction operation ends. As the abnormal processing, it is possible to forcibly eject the optical disk and notify the user that the abnormal processing has been performed.

FIG. 8 is a flowchart showing a tilt correction operation in the access processing. As described above with reference to FIG. 4, a case will be described in which the inclination correction value table has been created and the access destination address has already been given to the controller 9. First, in step S61, the controller 9 acquires the inclination correction value Ca corresponding to the access destination address from the inclination correction value table.

Next, in step S62, the movement amount of the optical pickup 2 is calculated from the current address and the access destination address. In step S63, the tracking servo is turned off. In step S64, the inclination correction value Ca obtained from the correction value table is supplied to the inclination correction device 3.

In step S65, the optical pickup 2 is moved by the movement amount calculated in step S62. After the movement, the tracking servo is turned on in step S66. In step S67, the moved address Aa is read. In step S68, it is determined whether the correction value needs to be reacquired. If the normal reproduction operation is possible, it is determined that the reacquisition of the correction value is not necessary,
In 69, since the access accuracy is not obtained only by moving the optical pickup, the tracking servo is turned on, the address of the disk traced by the light spot is read, and the position of the light spot is driven into a predetermined access accuracy range. That is, when the value falls within the predetermined access error range, the access operation ends.

In step S68, when an abnormality such as the address cannot be read normally after the movement of the optical pickup 2 occurs, it is determined that the correction value needs to be reacquired. In that case, the process proceeds to initialization of the retry counter in step S70. Step S7 following step S70
1 (tracking servo off), step S72 (tilt correction value acquisition), step S73 (tracking servo on), step S74 (movement destination address acquisition),
Step S75 (determining whether or not retry is necessary) is the same as that in FIG.
, And are the same as steps S48 to S53 of the above-described processing, and the description thereof will be omitted to avoid duplication.

If a new correction value can be normally obtained, the correction value table is updated in step S76. Next, in step S77, access access is performed and the access processing ends. Step S75
In the case where a new correction value cannot be acquired normally, step S78 (update of the retry counter) and step S79 (decision of termination of retry) are performed. If the correction value cannot be obtained even after a predetermined number of retries, step S80 (abnormal termination processing) is performed.

FIG. 9 is a flowchart showing a process for creating a tilt correction value table during the access process. In step S80, the amount of movement of the optical pickup 2 is calculated from the current address and the access destination address, and step S81
To turn off the tracking servo, and move the optical pickup 2 by the movement amount calculated in step S82. After the movement, in step S83, it is determined whether or not there is an access destination correction value in the correction value table.

If there is an access destination correction value in the correction value table, the inclination correction value Ca corresponding to the access destination address is obtained from the inclination correction value table, as in the process of FIG. 8 (step S84), and step S85 is performed. Supplies the inclination correction value Ca obtained from the correction value table to the inclination correction device 3. If it is not in the table, in step S86, FIG.
Is performed with reference to FIG.

In step S87, the tracking servo is turned on. In step S88, the destination address Aa is read. In step S89, it is determined whether it is necessary to acquire the correction value again. If the normal reproduction operation is possible, it is determined that the reacquisition of the correction value is unnecessary. If the Cmax is acquired in step S86 in step S90, the acquired inclination correction value is registered in the table, and In S91, the access destination address is changed. That is, when the value falls within the predetermined access error range, the access operation ends.

If it is determined in step S89 that re-acquisition of the correction value is necessary, step S92 (initialization of the retry counter), step S93 (turn-off of the tracking servo), step S94 (acquisition of the inclination correction value),
Step S95 (tracking servo ON), step S96 (acquisition of destination address), step S97
(Determining if retry is needed). When retry is required, step S100 (update of retry counter), step S101 (judgment of termination of retry), and step S102 (abnormal termination processing) are performed.
If retry is not required in step S97, steps S98 (registering a correction value table) and step S99 (removing access) are performed.

Note that the determination in step S83 and the setting in step S85 may be performed in advance before step S80 (calculation of the access destination address movement amount), or time may be set during movement to the access destination in step S82. It may be performed in parallel with the necessary processing. In particular, step S82
In parallel, the time required for searching the table can be minimized.

As shown in FIG. 9, according to the method of creating a tilt correction value table during access processing, a tilt correction value is obtained as needed during access, and the obtained correction value is registered in the table. Therefore, as shown in FIG. 4, compared to the method of creating a correction value table when a disc is inserted, the waiting time when the disc is inserted can be reduced. Also,
The acquisition of the inclination correction value may be performed as necessary from the data already registered in the correction value table and the access destination, and need not be performed each time the access is performed.

FIG. 10 shows a tilt correction effect when a liquid crystal element is used as a tilt correction element. The tilt angle is 0 degree when the optical axis of the optical pickup is perpendicular to the disk recording surface. Change 16 of traverse level with respect to tilt angle when tilt correction according to the present invention is performed
Indicates that the level change is smaller than the change 17 with respect to the inclination angle of the traverse level when no correction is performed. Thus, the inclination correction is effectively performed.

Further, the rate of the time variation of the edge position of the digital reproduction signal (the signal before demodulation of the digital modulation) of the optical disk obtained from the equalizer is called jitter. In order to reduce errors, it is preferable to reduce jitter. The change 18 of the jitter with respect to the tilt angle when performing the tilt correction according to the present invention is smaller than the change 19 with respect to the tilt angle of the jitter when the correction is not performed. As described above, the level fluctuation of the traverse signal and the time axis fluctuation of the reproduction signal with respect to the inclination can be reduced, and the error of the reproduction signal can be reduced. In other words, according to the present invention, the tolerance to the tilt of the optical axis of the optical pickup and the disk, that is, the so-called skew can be further increased.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications based on the technical idea of the present invention are possible. For example, the tilt correction device is not limited to a liquid crystal element, and a mechanism for mechanically correcting a relative tilt between an optical block including an optical pickup and a disk rotating unit may be used. Increase
The irradiation angle on the disk may be controlled. It is preferable to use a tilt correction device having little residual aberration. Further, the present invention can be applied to an optical disk device that reads information on a disk by fixing the optical pickup and moving the disk.

[0056]

According to the present invention, in order to obtain a correction value for performing tilt correction, it is only necessary to add a traverse signal level detection circuit, and the number of hardware added to a conventional optical disk apparatus is small. Good.

According to the present invention, the inclination can be corrected irrespective of the presence or absence of a recording signal, and the present invention can be applied to an unrecorded portion of a disk in a recordable disk device.

The present invention can be applied to an entire optical disk device regardless of the configuration of the groove (guide groove) of the disk.

According to the present invention, in the case of a disk in which addresses are recorded by wobbling grooves,
The inclination can be corrected before the address is read, and the address can be read immediately.

In the present invention, since a reproduced signal from the optical pickup is used, a special external sensor is not required, and it is not necessary to perform precision adjustment as compared with the case where an external sensor is used.

According to the present invention, feedback can be configured by the tilt detection signal and the tilt correction device, and precise correction can be performed with a simple configuration.

According to the present invention, the inclination detection time can be shortened, so that it is possible to make corrections during normal operation if necessary. It can be adaptively corrected.

[Brief description of the drawings]

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

FIG. 2 is a waveform diagram used for describing a traverse signal.

FIG. 3 is a flowchart used to explain a tilt correction value acquisition operation according to the embodiment of the present invention.

FIG. 4 is a flowchart used to explain a correction value table creation operation according to an embodiment of the present invention.

FIG. 5 is a schematic diagram used for explaining a tilt correction value table.

FIG. 6 is a schematic diagram for explaining range division of tilt correction.

FIG. 7 is a flowchart for explaining tilt correction during a reproducing operation according to an embodiment of the present invention.

FIG. 8 is a flowchart illustrating an example of tilt correction during an access operation according to the embodiment of the present invention.

FIG. 9 is a flowchart illustrating another example of tilt correction during an access operation according to the embodiment of the present invention.

FIG. 10 is a schematic diagram for explaining the effect of tilt correction according to the present invention.

[Explanation of symbols]

1 ... optical disk, 2 ... optical pickup, 3 ...
・ Tilt correction device, 7 ・ ・ ・ Tracking servo unit, 8 ・
..Focus servo section, 9 ... Controller, 11
... Level detector

Claims (8)

[Claims] In an optical disc apparatus for recording or reproducing information by irradiating a light beam of an optical pickup to a signal recording surface of an optical disc, a light beam is not irradiated perpendicularly to the signal recording face. Tilt correcting means for correcting aberrations caused by the light beam; tracking servo means for controlling the light beam to trace on the track; and a spot of the light beam crossing a plurality of tracks or grooves with the tracking servo turned off. Means for detecting a level of a traverse signal generated by the above-mentioned method, and an inclination correction value for the inclination correction means is obtained based on the detected level of the traverse signal. 2. The optical disk apparatus according to claim 1, wherein an inclination correction value at which the level of the traverse signal is maximized is determined, and the correction value is used as an inclination correction value at or near a detection position. 3. The tilt correction value at which the level of the traverse signal is maximized by changing a tilt correction value supplied to the tilt correction means by a predetermined difference value. Optical disk device. 4. The apparatus according to claim 1, wherein when the optical disk is inserted, the inclination correction values are obtained at a plurality of positions on the optical disk, and the positions are associated with the inclination correction values obtained therefrom. A table is created, the created table is stored, and a tilt correction value corresponding to a position on the disk is read from the table during normal operation, and the read tilt correction value is supplied to the tilt correction means. An optical disk device characterized in that: 5. The apparatus according to claim 1, wherein the tilt is corrected by the tilt correcting means at the end of the movement of the optical pickup at the time of access for moving the optical pickup over the disk with the disk inserted. An optical disk device that turns on the tracking servo. 6. The tilt correction value according to claim 5, wherein the tilt correction value is stored in advance together with the position of the disk, and in a subsequent operation, when the tilt correction value is moved to a position near the position where the correction value is already stored, the stored correction value is changed. When using and moving to a position near the position where the correction value is not stored in advance,
An optical disc device that performs an operation of acquiring a tilt correction value. 7. An apparatus according to claim 1, wherein when an abnormality occurs due to the inclination of the optical axis of the optical pickup and the recording surface of the disk, a new inclination correction value is obtained again, and the position on the disk and the correction value are stored. An optical disc device that performs tilt correction using the stored correction values in subsequent operations. 8. A tilt correction method in an optical disk device for recording or reproducing information by irradiating a signal recording surface of an optical disk with a light beam of an optical pickup, wherein the light beam traces on a track. Detects the level of a traverse signal generated by the light beam spot crossing a plurality of tracks or grooves with the tracking servo turned off, and calculates a tilt correction value based on the detected level of the traverse signal. A tilt correction method characterized in that a tilt angle is calculated.