JP2001344790A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize tilt detection without using a tilt sensor with an optical disk device because the reduction of the size and cost of the optical disk device is hindered if the optical disk device is provided with the tilt sensor in order to detect the inclination of the disk with respect to an optical head. SOLUTION: The asymmetry Ya and Yb of the groove crossing signals of push-pull tracking error signals with respect to two kinds of lens shift quantities are detected and the tilt of the optical head with respect to the optical disk is detected by utilizing the correspondence relations between values obtained by dividing Ya by Yb, values obtained by dividing Ya previously obtained relating to each of the plural tilts by Yb and the respective tilts. As a result, the tilt detection is made possible without the tilt sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device having an optical head for recording or reproducing data on or from an optical disk, and more particularly to an optical disk having a function for detecting the inclination of the optical head with respect to the optical disk. It concerns the device.

[0002]

2. Description of the Related Art In recent years, as the recording density of an optical disk has increased, it has become necessary to keep the inclination of an optical head with respect to the optical disk as small as possible in order to perform stable recording and reproduction on the optical disk. Conventionally, as a tilt (tilt) detection method, a sensor for detecting the tilt of the optical disk with respect to the optical head is provided, and the output of this sensor is used as a tilt error signal, and control is performed so that the tilt of the optical disk with respect to the optical head is canceled. It has been proposed to adopt a configuration that performs the following.

FIG. 11 is a block diagram schematically showing an example of an optical disk apparatus having a configuration for canceling the inclination of a disk as described above. Disk 1 shown in this figure
112 is driven to rotate by a spindle motor 1103. The optical head 1101 irradiates a laser beam to the disk 1112 that is being driven to rotate, thereby rotating the disk 1112.
112, the information recorded in the reproduction circuit 1 is read out.
Output to 104.

In this case, the optical head 1101 includes driving means for moving a converging lens, which is an example of light converging means, in a disk radial direction (tracking direction) and in a direction (focus direction) in which the converging lens comes into contact with or separates from the disk surface. Optical head 1
A transport means for transporting the disk 101 itself in the radial direction of the disk and a tilt mechanism for driving the optical head 1101 itself in an inclined direction are provided.

Further, for example, a tilt sensor 1102 is provided near the optical head 1101. The tilt sensor 1102 irradiates, for example, LED light onto the light-incident surface of the disk 1112, and detects the degree of tilt of the disk, for example, by measuring the time until the irradiated light is reflected and received. This detection information is output to the control circuit 1105 as a tilt (tilt) error signal.

The reproducing circuit 1104 generates a focus error signal, a tracking error signal, and the like using information read from the disk 1112 supplied from the optical head 1101 and outputs the signal to the control circuit 1105. The reproduction circuit 1104 generates a spindle error signal as an error signal of the rotation speed of the spindle motor 1103 using the clock extracted from the reproduction signal, and
Output to 05.

The generation of the spindle error signal may be performed by the control circuit 1105 using a clock obtained by the reproduction circuit 1104. Also, the reproduction circuit 1
104 is the disk 1 supplied from the optical head 1101
A reproduction data signal is obtained by subjecting the pit signal as read information from 112 to a required decoding process or the like.

A control circuit 1105 shown in FIG. 11 executes necessary control processing relating to a reproducing operation in the optical disk device and also executes required servo control here. As the servo control, the FC / TR driver 1111 is controlled based on the focus error signal and the tracking error signal.
From 11, a drive signal for driving a driving unit that supports the objective lens in the optical head 1101 is output, whereby focus control and tracking control are performed so that focusing and tracking on the disk 1112 are properly performed. Will be.

Further, a transfer error signal is generated using, for example, a tracking error signal, and the transfer driver 1107 is generated.
Is controlled to drive the transfer mechanism, so that the transfer control for transferring the optical head 1101 according to the displacement of the reproduction position in the radial direction of the disc is performed.

In this case, the control circuit 1105 controls the tilt driver 1109 based on the tilt error signal supplied from the tilt sensor 1102 to drive the tilt motor 1110. The tilt motor 1110 is connected to a tilt mechanism of the optical head 1101, and the tilt motor 1110 is driven to rotate, whereby the optical head 1101 is rotated.
The optical head 1101 is configured to move in the tilt direction in the disk radial direction.
The movement is performed so that the inclination with respect to the plane 112 is canceled, and the tilt control is performed.

[0011]

As described above, when the tilt sensor 1102 is used for detecting the tilt of the disk, the tilt sensor 1102 used is relatively large in size and is accordingly expensive. . Therefore, this is a factor that hinders downsizing and cost reduction of the disk drive device.

An object of the present invention is to reduce the size and cost of an optical disk device.

[0013]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides an optical disk drive without providing a tilt sensor, and for reproducing information recorded on the optical disk, a light beam focused on the optical disk. By detecting the reflected light obtained by the reflection, the inclination of the disk with respect to the optical head can be detected (tilt detection).

Thus, it is not necessary to separately provide a tilt sensor, and the size and cost of the optical disk device can be reduced.

According to a first aspect of the present invention (corresponding to claim 1), a light source for emitting light, light converging means for converging light from the light source on an optical disk, and means for detecting reflected light from the optical disk An optical head having at least detection means having a first light receiving area and a second light receiving area substantially divided into two by a dividing line corresponding to a rotation direction of the optical disc; and Transfer means for transferring the optical disk substantially in the radial direction, and when the light converging means is fixed to a predetermined position in the optical head, the optical head transfers substantially in the radial direction of the tilt detection optical disk. A difference between a high output side level and a low output side level of a signal waveform formed by a difference in the amount of light detected between the first light receiving region and the second light receiving region; Storage means for storing in advance a correspondence relationship between the tilt of the optical head or the light converging means with respect to each of the plurality of tilts, and the light source when the light converging means is fixed at the predetermined position. A high output side level and a low output side of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area when the head is moved substantially in the radial direction of the optical disk; A tilt detecting unit that detects a tilt of the optical head or the light converging unit with respect to the optical disk by using a difference between the level and the correspondence stored in the storage unit. Optical disk device.

The first aspect of the present invention has an effect that the tilt can be detected without providing a tilt sensor.

According to a second aspect of the present invention, a light source for emitting light, light converging means for converging light from the light source on an optical disk, and the light converging means are provided substantially on the optical disk. A moving means for moving in a radial direction, and a means for detecting reflected light from the optical disc, wherein the first light receiving area and the second light receiving area substantially divided into two by a dividing line corresponding to a rotation direction of the optical disc. An optical head having at least a detecting means having a light receiving area, a transferring means for transferring the optical head substantially in a radial direction of the optical disk, and the light converging means fixed to a predetermined first position in the optical head When the optical head is moved substantially in the radial direction of the tilt detecting optical disk when the optical head is moved, a signal representing a difference in the amount of light detected between the first light receiving area and the second light receiving area is formed. A first difference between a high output side level and a low output side level of a waveform, and the optical head for tilt detection when the light converging means is fixed at a predetermined second position in the optical head. When the light beam is transferred substantially in the radial direction, the difference between the light amount detected in the first light receiving area and the light amount detected in the second light receiving area is the second of the high output side level and the low output side level of the signal waveform. A storage unit for storing in advance a correspondence relationship between a first ratio with respect to the difference of 2 and the tilt of the optical head or the light converging unit with respect to the tilt detection optical disc for each of the plurality of tilts; When the convergence means is fixed at the first position, the optical head is detected by the first light receiving area and the second light receiving area when the optical head is moved in a substantially radial direction of the optical disk. Light intensity difference A third difference between the high output side level and the low output side level of the signal waveform, and the optical head moving in a substantially radial direction of the optical disk when the light converging means is fixed at the second position. At this time, the second difference between the fourth difference between the high output side level and the low output side level of the signal waveform formed by the difference in the amount of light detected between the first light receiving area and the second light receiving area. An optical disk comprising: a tilt detecting unit configured to detect a tilt of the optical head or the light converging unit with respect to the optical disk using the ratio of the optical head and the correspondence stored in the storage unit. Device.

The second aspect of the present invention has an effect that the tilt can be detected without providing a tilt sensor, similarly to the first aspect of the invention.

According to a third aspect of the present invention, a light source for emitting light, light converging means for converging light from the light source on an optical disk, and the light converging means are substantially provided on the optical disk. A moving means for moving in a radial direction, and a means for detecting reflected light from the optical disc, wherein the first light receiving area and the second light receiving area substantially divided into two by a dividing line corresponding to a rotation direction of the optical disc. An optical head having at least a detecting means having a light receiving area, a transferring means for transferring the optical head substantially in a radial direction of the optical disk, and the light converging means fixed to a predetermined first position in the optical head When the optical head is moved in a substantially radial direction of the tilt detecting optical disk, a signal representing a difference in the amount of light detected between the first light receiving area and the second light receiving area is formed. A first difference between a high output side level A1 and a low output side level B1 of the waveform, and tilt detection of the optical head when the light converging means is fixed at a predetermined second position in the optical head; Output level A2 and low output level of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area when the optical disk is transported substantially in the radial direction of the optical disc. The relationship between the first ratio of the second difference from B2 and the difference between the first difference and the tilt of the optical head or the light converging means with respect to the tilt detection optical disk is represented by a plurality of tilts. Storage means pre-stored for each of the first light receiving means and the first light receiving means when the optical head is moved in a substantially radial direction of the optical disk when the light converging means is fixed at the first position. Region and the second A third difference between the high output side level A′1 and the low output side level B′1 of the signal waveform formed by the difference in the amount of light detected between the light area and the light convergence means in the second position When fixed, when the optical head is moved in a substantially radial direction of the optical disk, a signal waveform of a difference in light amount detected between the first light receiving region and the second light receiving region is formed. The fourth difference between the high output side level A′2, the low output side level and B′2 and the third difference
A tilt detection unit that detects a tilt of the optical head or the light converging unit with respect to the optical disc by using a second ratio of the optical head or the light converging unit to the optical disc by using a second ratio of the optical head or the light converging unit to the optical disc. An optical disc device comprising:

According to a fourth aspect of the present invention (corresponding to claim 4), the first difference is a difference between the high output side level A1 and the low output side level B1, and the high output side level A1 is different from the high output side level A1. The first difference is replaced by a first asymmetry Y1, which is a value divided by the sum of the low output side level B1, and the second difference is a difference between the high output side level A2 and the low output side level B2. The second ratio is replaced by a second asymmetry Y2, which is a value obtained by dividing by a sum of the high output side level A2 and the low output side level B2, and the first ratio is obtained by dividing the first asymmetry Y1 by the first asymmetry Y1. Is replaced by the ratio of the difference between the asymmetry Y1 and the second asymmetry Y2, and the third difference is the high output side level A′1
And a third asymmetry Y3, which is a value obtained by dividing the difference between the low output side level B′1 and the high output side level A′1 by the sum of the high output side level A′1 and the low output side level B′1, The fourth
Is a value obtained by dividing the difference between the high output side level A'2 and the low output side level B'2 by the sum of the high output side level A'2 and the low output side level B'2. And the second ratio is the ratio of the third asymmetry Y3 and the difference between the third asymmetry Y3 and the fourth asymmetry Y4. An optical disc device according to a third aspect of the present invention, which has been replaced.

According to a fifth aspect of the present invention (corresponding to claim 5), a light source for emitting light, light converging means for converging light from the light source on an optical disk, and the light converging means are substantially provided on the optical disk. A moving means for moving in a radial direction, and a means for detecting reflected light from the optical disc, wherein the first light receiving area and the second light receiving area substantially divided into two by a dividing line corresponding to a rotation direction of the optical disc. An optical head having at least a detecting means having a light receiving area, a transferring means for transferring the optical head substantially in a radial direction of the optical disk, and the light converging means fixed to a predetermined first position in the optical head When the optical head is moved in a substantially radial direction of the tilt detecting optical disk, a signal representing a difference in the amount of light detected between the first light receiving area and the second light receiving area is formed. A first difference between a high output side level A1 and a low output side level B1 of the waveform, and tilt detection of the optical head when the light converging means is fixed at a predetermined second position in the optical head; Output level A2 and low output level of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area when the optical disk is transported substantially in the radial direction of the optical disc. A second difference from B2;
When the light converging means is fixed at a predetermined third position in the optical head opposite to the second position with respect to the first position, the optical head is moved to the position of the optical disk for tilt detection. The difference between the high light output level A3 and the low output output level B3 of the signal waveform formed by the difference in the amount of light detected between the first light receiving area and the second light receiving area when the light is transferred substantially in the radial direction. Regarding a third difference, a first ratio of the first difference, a difference between the second difference and the third difference, and the optical head or the light converging unit with respect to the tilt detection optical disk. Storage means for storing in advance the correspondence relationship with the tilt of each of the plurality of tilts,
When the light converging means is fixed at the first position,
When the optical head is moved substantially in the radial direction of the optical disk, a high output side level A 'of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area. 4 and the fourth difference between the low output side level B′1 and
When the light converging means is fixed at the second position,
When the optical head is moved substantially in the radial direction of the optical disk, a high output side level A 'of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area. 5 and the fifth difference between the low output side level B′2 and
When the light converging means is fixed at the third position,
When the optical head is moved substantially in the radial direction of the optical disk, a high output side level A 'of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area. The fourth difference, the second ratio of the difference between the fifth difference and the sixth difference, and the storage means. And a tilt detecting unit that detects a tilt of the optical head or the light converging unit with respect to the optical disk by using the correspondence stored in the optical disk device.

According to a sixth aspect of the present invention (corresponding to claim 6), the first difference is a difference between the high output side level A1 and the low output side level B1 and the high output side level A1 The first difference is replaced by a first asymmetry Y1, which is a value divided by the sum of the low output side level B1, and the second difference is a difference between the high output side level A2 and the low output side level B2. The second difference is replaced by a second asymmetry Y2 which is a value obtained by dividing the sum of the high output side level A2 and the low output side level B2, and the third difference becomes the high output side level A3 and the low output side level. A third asymmetry Y, which is a value obtained by dividing the difference from B3 by the sum of the high output side level A3 and the low output side level B3.
3 and the first ratio is replaced by a ratio of the first asymmetry Y1 and the difference between the second asymmetry Y2 and the third asymmetry Y3, The difference is
The high output side level A'1 and the low output side level B'1
The fourth asymmetry Y4 is a value obtained by dividing a difference between the high output side level A′1 and the low output side level B′1.
And the fifth difference is the difference between the high output level A′2 and the low output level B′2, and the difference between the high output level A′2 and the low output level B′2. With the fifth asymmetry Y5 which is a value obtained by dividing the difference between the high output level A′3 and the low output level B′3 by the high asymmetry Y5. A sixth value which is a value obtained by dividing by the sum of the output side level A′3 and the low output side level B′3.
And the second ratio is replaced by a ratio of the fourth asymmetry Y4 and a difference between the fifth asymmetry Y5 and the sixth asymmetry Y6. An optical disc device according to a fifth aspect of the present invention, characterized in that:

Each of the third to sixth aspects of the present invention has an effect of reducing a tilt detection error caused by a difference in groove specifications of an optical disk.

A seventh aspect of the present invention (corresponding to claim 7) is that the high output side level and the low output side level are average values of the respective output levels detected during the integer rotation of the optical disk. The optical disc device according to any one of the first to sixth aspects of the present invention, wherein the output level is an intermediate value between the maximum value and the minimum value of each output level.

The seventh aspect of the present invention has an operation of detecting a tilt amount from which a component fluctuating during one rotation of the tilt is removed.

According to an eighth aspect of the present invention (corresponding to claim 8), the storage means includes a first detection ratio obtained by raising the first ratio to a power of a constant coefficient n and further multiplying the first ratio by a constant coefficient k. The correspondence between the information and the tilt of the optical head or the light convergence unit with respect to the tilt detection optical disk is stored in advance for each of the plurality of tilts, and the tilt detection unit calculates the second ratio, The power of the coefficient n is multiplied by the coefficient k to obtain second detection information, and the tilt of the optical head or the light converging means with respect to the optical disk is determined using the second detection information and the correspondence. An optical disk device according to any one of the second to seventh aspects of the present invention, characterized in that the optical disk device performs the detection.

The eighth aspect of the present invention has an effect of reducing a tilt detection error caused by a difference in tilt magnitude.

According to a ninth aspect of the present invention (corresponding to claim 9), the difference between the amounts of light detected between the first light receiving region and the second light receiving region is determined by comparing the difference between the first light receiving region and the first light receiving region. The optical disk device according to any one of the first to eighth aspects of the present invention, wherein the optical disk device is replaced with a value obtained by dividing by a sum of light amounts detected by the second light receiving region.

The ninth aspect of the present invention has an effect of removing a tilt detection error due to the influence of the reflectivity difference of the disk.

A tenth aspect of the present invention (corresponding to claim 10) is:
Any one of the first to ninth aspects, further comprising tilt correction means for correcting a tilt of the optical head or the light converging means with respect to the optical disc based on the tilt detected by the tilt detection means. 2 is an optical disk device according to the present invention.

The tenth aspect of the present invention has the function of maintaining a favorable tilt state when recording or reproducing an optical disk.

The eleventh invention (corresponding to claim 11) provides:
The tilt detecting means detects the tilt in the entire radial area of the optical disc from the signal waveforms at two or more points between the substantially innermost circumference and the substantially outermost circumference of the optical disc. An optical disc device according to any one of the first to tenth aspects of the present invention.

The eleventh aspect of the present invention has the function of calculating the amount of tilt over the entire area in the radial direction of the optical disk.

The twelfth invention (corresponding to claim 12) provides:
The transfer means moves the optical head when the light converging means is located at the second position or the third position. The light converging means moves the light head from the first position to the second position or The invention according to any one of the second to eleventh aspects of the present invention, wherein the light converging means is moved in a direction substantially opposite to the moving direction by an amount substantially equal to the amount moved to the third position. Optical disk device.

The twelfth aspect of the present invention has the effect that the radial measurement positions with respect to the optical disk substantially coincide.

According to a thirteenth aspect of the present invention (corresponding to claim 13),
The measurement of the signal waveform is performed by setting a distance substantially twice or more of a difference between the first position and the second position of the light converging means or a difference between the first position and the third position. The tilt is performed at three positions where the optical head is transferred to the separated positions, and the tilt is determined from two adjacent values among the tilts detected based on the signal waveforms at the three positions. An optical disc device according to any one of the first to twelfth aspects of the present invention.

The thirteenth aspect of the present invention has an effect of removing a tilt detection error caused by a case where a tilt detection measurement position is at a boundary between a recorded area and an unrecorded area.

The fourteenth invention (corresponding to claim 14) is:
The first aspect of the present invention is characterized in that the detected tilt amount Tn in the entire radial direction of the optical disk or at each point in the radial direction is replaced with a difference (Tn-T1) from the tilt detected amount T1 at the innermost circumference of the optical disk. An optical disk device according to any one of the first to thirteenth aspects of the present invention.

The fourteenth aspect of the present invention has an effect of removing a tilt detection error caused by the asymmetry of the groove of the disk and the deviation of the optical system of the optical head.

According to a fifteenth aspect of the present invention (corresponding to claim 15),
The tilt detection amount Tn in the entire area in the radial direction or each point in the radial direction of the optical disk is determined by the tilt detection amount T1 at the innermost circumference of the optical disk and the optical head of the optical head with respect to the optical disk in an optimum state for reproducing the inner peripheral emboss signal. The value obtained by subtracting the difference (T1−Te) from the slope Te is ΔTn−
An optical disc device according to any one of the first to thirteenth aspects, wherein the optical disc device is replaced with (T1-Te)｝.

The fifteenth aspect of the present invention eliminates the tilt detection error caused by the asymmetry of the groove of the disk, the deviation of the optical system of the optical head, the offset of the circuit system, and the inclination due to the mounting between the disk and the turntable. It has the effect of doing.

[0042]

Next, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing an example of the configuration of an optical disk device according to Embodiment 1 of the present invention.
The disk 116 is mounted on, for example, a turntable not shown here, and is driven by the spindle motor 114.
For example, it is driven to rotate at a constant linear velocity (CLV).

On the other hand, the laser light emitted from the laser diode 104 is converged on the disk 116 by the converging lens 103 which is an example of the light converging means, and the reflected light information from the disk 116 is detected by the photodetector 105. The detected signal is supplied to the RF amplifier 106 as an electric signal corresponding to the amount of received light. In the RF amplifier 106, after the current-voltage conversion, a matrix operation / amplification process is performed to generate various signals. That is, an RF signal, a focus error signal FE, a tracking error signal TE (a push-pull tracking error signal PPTE and a phase difference tracking error signal DPDTE), and the like are generated.

As described above, of the various signals output from the RF amplifier 106, the RF signal is
7, the focus error signal FE and the tracking error signal TE are supplied to the servo processor 109. RF
After the signal is binarized by the binarization circuit 107, the decoder 10
8 for decoding, and output as reproduction data.

The servo processor 109 also has a function as a signal detecting means. The servo processor 109 uses the focus error signal FE, the tracking error signal TE from the RF amplifier 106, the spindle error signal SPE generated by the decoder 108 or the system controller 115, and the like. It generates various servo drive signals for focus, tracking, transfer motor, and spindle, and executes a servo operation.

That is, the servo processor 109 generates a focus drive signal and a tracking drive signal according to the focus error signal FE and the tracking error signal TE, and supplies them to the FC / TR driver 117. F
The C / TR driver 117 drives the driving device 102 which is an example of a moving unit of the converging lens 103. The driving device 102 includes, for example, a focus coil, a tracking coil, a magnet, and the like.
By controlling the current flowing through the tracking coil,
Convergent lens 10 in focus direction and tracking direction
3 to perform focus control and tracking control.

The servo processor 109 sends a spindle error signal SPE to the spindle driver 113.
The spindle drive signal generated according to is supplied.
The spindle driver 113 applies, for example, a three-phase drive signal to the spindle motor 114 according to the spindle drive signal, and controls the rotation of the spindle motor 114. Further, the servo processor 109 is a system controller 1
15 generates a spindle drive signal in response to the spindle start / stop control signal from
13 to start or stop the spindle motor 114.

The servo processor 109 generates a transfer drive signal based on, for example, a transfer error signal obtained as a low-frequency component of the tracking error signal TE and a search execution control from the system controller 115, and supplies the transfer drive signal to the transfer driver 111. The transfer driver 111 drives a transfer motor 112, which is an example of a transfer unit, in accordance with the transfer drive signal, and slides the optical head 101 in the radial direction of the optical disk 116.

The laser diode 104 is driven to emit light by a laser driver 110. The servo processor 109 generates a laser drive signal based on an instruction from the system controller 115 to execute the light emitting operation of the laser diode 104.

The push-pull tracking error signal PPTE in the tracking servo OFF state becomes a tilt detection signal for detecting the inclination of the disk with respect to the optical head by performing processing described later in detail. Therefore,
The servo processor 109 outputs a tilt drive signal according to the tilt detection signal. The tilt driver 118 rotationally drives the tilt motor 119 in a required rotation direction and rotation angle based on the input tilt drive signal, and rotates the optical head 101 in an inclined direction in the disk radial direction, thereby rotating the optical head 101. Is corrected with respect to the tilt of the disc 116 with respect to the disc, and a favorable tilt condition can be maintained when recording and reproducing the disc.

Next, tilt detection will be described. FIG. 2A shows a push-pull tracking error signal PP.
3 shows a configuration example of a photodetector in which a light receiving region for detecting TE is divided into two. As shown in FIG. 2A, when the light beam spot SP0 of the zero-order light forms an image on the photodetector 201,
Brightness and darkness occur in the imaging light. The light and darkness depends on the optical head 1
Each time 01 crosses the track, it is reversed with a center line parallel to the track (a dividing line between the light receiving area L1 side and the L2 side) interposed therebetween.

In other words, if the driving device 102 is not driven in the tracking direction without performing the tracking control, the converging lens 103 becomes neutral with respect to the disk radial direction.
The difference signal between the L1 side and the L2 side, that is, the push-pull tracking error signal PPTE = L1-L2, is generated every time the light applied to the disk 116 traverses the track of the disk 116 as shown in the waveform diagram of FIG. , An intensity modulation (cross-groove signal) is obtained.

Here, when there is no inclination (hereinafter referred to as tilt) of the disk 116 with respect to the optical system of the optical head 101 and the converging lens 103 is in the neutral position in the disk radial direction, the asymmetry Y = (A-
B) / (A + B) is almost zero.

However, when a tilt occurs, or when the driving device 102 is driven in the tracking direction,
When 03 moves from the neutral position to the optical head 101 in the tracking direction (hereinafter referred to as lens shift), the symmetry of the groove crossing signal is broken as shown in FIG. , The output value corresponding to the magnitude of the tilt or the lens shift.

Therefore, the asymmetry Ya of the groove crossing signal with respect to the tilt Ya = (Aa−Ba) / (Aa + Ba) and the asymmetry Yb = (Ab−B) of the groove crossing signal with respect to the lens shift.
From b) / (Ab + Bb), an output (tilt detection signal) corresponding to the amount of tilt can be obtained by performing the arithmetic processing described later in detail.

Next, a description will be given of a calculation process for obtaining a tilt detection signal. As shown in FIG. 4A, the asymmetry Ya of the groove crossing signal with respect to the tilt is determined by the output with respect to the tilt having a certain magnitude by the disks A and B having different groove specifications such as the groove depth and groove width of the disk. If the Ya is used as it is, an error due to a difference in the groove specifications of the disk becomes large in order to use it as a tilt detection signal.

However, the asymmetry Y of the groove crossing signal shows an output value corresponding to the magnitude of the lens shift, and furthermore, as shown in FIGS. The rate of change of the asymmetry Ya of the crossing signal and the rate of change of the asymmetry Yb of the groove crossing signal with respect to the lens shift generally have a correlation corresponding to the difference in the groove specifications of the disk.

That is, for a groove specification disc in which the output of the asymmetry Ya of the groove crossing signal with respect to the tilt becomes large, the asymmetry Yb of the groove crossing signal with respect to the lens shift is obtained.
Also has a large output. Therefore, the asymmetry Ya of the groove crossing signal with respect to the tilt is calculated as the change amount Yb of the asymmetry of the groove crossing signal with respect to the lens shift amount of, for example, 100 μm (for example, in FIG.
The value Tc = Ya / Yb divided by Yb1−Yb0 or Yb0−yb2) is almost the same for disks having different groove specifications as shown in FIG. That is, the Tc obtained as described above is a tilt detection signal having a small error for various disks having different groove specifications.

In FIG. 4B, the value Yb1 of the asymmetry Yb of the groove crossing signal when the lens is shifted by +100 μm.
And the average value (Yb1-Yb2) / Yb2 of the asymmetry Yb of the groove crossing signal when the lens is shifted by -100 μm.
By using 2 as the asymmetry Yb of the groove crossing signal for a lens shift of 100 μm, errors due to the directionality of the lens shift can be reduced.

Then, the servo processor 109 calculates Tc = Tc obtained in advance for each of the plurality of tilts.
Ya / Yb is compared with Tc = Ya / Yb for the disc for which tilt is to be detected, and the tilt of the disc is detected.

In this example, the method of shifting the lens is +
100 μm and -100 μm, but +50 μm
m and -50 μm lens shift to lens shift 100
The asymmetry Yb of the groove crossing signal with respect to μm is obtained, and the lens crossing signal when a certain amount of lens shift is performed from three or more lens shift amounts in combination with these lens shift amounts and other lens shift amounts. The asymmetry Yb may be obtained.

In the tilt detection, instead of the asymmetry Y of the groove crossing signal Y = (AB) / (A + B),
(AB) may be used. Further, the value of (AB) also shows a value corresponding to the tilt amount.
The value of (AB) may be used as the tilt detection signal. Further, the value of (AB) at the lens shift = 0 (A
1-B1) and a value (A) when the lens is shifted by a certain amount.
From (2-B2), (A1-B1) / (A2-B2) may be calculated and used as the tilt detection signal.

Here, the lens shift amount (for example, +100
μm) is detected by the servo processor 109 required to generate a lens shift of +100 μm.
The command value given to the / TR driver 117 is measured in advance in the manufacturing stage of the drive device, and the value is measured by the servo processor 1.
By outputting the signal from 09, a lens shift of +100 μm can be generated. Also, the optical disk 116
The difference between the positions of the light irradiated on the optical disk 116 before and after the lens shift is detected from the address value read from the CPU, and the lens shift amount is determined from the number of grooves and the groove width corresponding to the address difference of the disk. You can ask.

Next, FIG. 5 shows a conceptual block diagram of an example of generating the asymmetry Y output from the groove crossing signal of the push-pull tracking error signal PPTE, and input / output waveforms of each block in the block diagram. . As shown in this figure, the groove crossing signal a is converted to an upper envelope detection circuit 501,
By inputting to the lower envelope detection circuit 502, the outputs b1 and b2 of the upper envelope detection circuit 501 and the lower envelope detection circuit 502 do not have intensity modulation due to groove traversal, and are synchronized with one rotation of the disk due to disk runout or the like. The signal whose intensity fluctuates in accordance with the fluctuation of the tilt of the disc obtained is obtained. Further, by inputting the outputs b1 and b2 to the operational amplifier 503, the output c of the operational amplifier 503 is obtained as an output indicating the asymmetry of the groove crossing signal a.

However, since the output c of the operational amplifier 503 also includes an AC component synchronized with one rotation of the disk, the output c of the operational amplifier 503 is required to detect the average tilt amount for one rotation at the radial position of the disk. It is necessary to find the average of one rotation of the disk having the output c of FIG. Therefore, for example, one rotation of the disk is detected from the rotation synchronization signal of the spindle motor, and the output d which is the average value of a period of an integral multiple of one rotation of the disk or the intermediate value between the maximum value cmax and the minimum value cmin of the output c Can obtain the asymmetry Y of the groove crossing signal a as an average value for one rotation of the disk. However, if the period of detecting the tilt amount is sufficiently longer than the period of one rotation of the disk, even if the period of detecting the tilt amount is not exactly an integral multiple of one rotation of the disk, the generated tilt detection error can be suppressed to a small value. It does not have to be exactly an integral multiple of one rotation of the disk.

Here, the average value is detected for the added output c of the outputs b1 and b2. However, the same result can be obtained by first calculating the average value for each of the outputs b1 and b2 and then adding them. Alternatively, such a configuration may be adopted. In practice, for example, in the servo processor 109 shown in FIG. 1, a configuration equivalent to that of FIG. 5 may be obtained, and this may be performed by analog processing or digital processing. It doesn't matter.

Next, Tc obtained by the above-described calculation
Is not always linearly related to the magnitude of the tilt, as shown in FIG. Therefore, Tc is raised to the power of a constant coefficient n (for example, n = 0.8), and the value is multiplied by a constant coefficient k (for example, k = 1.33). Td = k × (T
c) As shown in FIG. 4D, ⁿ obtains a tilt detection signal that maintains a linear relationship with the magnitude of tilt and outputs a constant value even for disks with different groove specifications. be able to.

Also in this case, the servo processor 109
T obtained in advance for each of multiple tilts
d and T for the disc for which tilt is to be detected.
Compared with d, the tilt of the disc is detected.

Here, the cross-groove signal as shown in FIGS. 3A and 3B has a difference in amplitude due to the difference in the reflectivity of the disk, and when asymmetry of the cross-groove signal is obtained, The error may be large. Thus, in the outputs L1 and L2 of the respective light receiving areas of the photodetector 201 in FIG. 2A, as shown in FIG. 2B, the difference signal (L
1−L2) divided by the sum signal (L1 + L2) (L1−L2).
L2) / (L1 + L2) is a groove-crossing signal normalized by the amount of light reflected from the disk 116, is a signal having a constant amplitude that is not affected by the difference in the reflectance of the disk, and is used to determine the asymmetry of the groove-crossing signal. Errors can be reduced.

When the eccentricity of the disk is small,
The number of light beams irradiating the optical disk 116 crossing the grooves of the optical disk 116 decreases, and the groove crossing signal as shown in FIGS. 3A and 3B is not output stably, and the asymmetry of the groove crossing signal is obtained. In such a case, the error may be large. Therefore, at the time of measuring the asymmetry of the groove crossing signal, by driving the transfer motor and sliding the optical head 101, the groove crossing signal can be reliably generated.
Tilt detection error can be reduced.

Next, a method of generating tilt data in the entire radial area of the disk will be described with reference to FIG. Here, an example is shown in which the tilt is measured at four points between the inner circumference and the outer circumference of the disk. In FIG. 6, the horizontal axis indicates the radial position from the inner circumference to the outer circumference of the disk, the vertical axis indicates the tilt amount, and T1 to T4 indicate the tilt measurement values at each radial position on the disk. In the area other than the tilt measurement point of the disk, the interpolation between the tilt measurement point and the measurement point is performed by a linear function (straight line) by interpolation and extrapolation in the entire radial area of the disk. The tilt amount is calculated.

As a function used for the interpolation approximation and the extrapolation approximation, a function that can further reduce the error or a simplified function that can shorten the calculation time may be used. Also, if the number of tilt measurement points is reduced, the time required for generating tilt data in the entire radial area of the disc can be shortened. Conversely, if the number of tilt measurement points is increased, the tilt detection error due to approximation can be reduced.

Next, when measuring the asymmetry Yb of the groove crossing signal when the lens is shifted by a certain amount, FIG.
As shown in FIG. 7B, the measurement position when the lens is shifted by a certain amount with respect to the measurement position when there is no lens shift shown in FIG. . Therefore, as shown in FIG. 7C, by moving the optical head 101 in a direction substantially opposite to the direction in which the lens is shifted by the amount of the lens shift, the measurement position is substantially the same as the measurement position when there is no lens shift. Measurement can be performed when the lens is shifted by a certain amount at the measurement position, and a tilt detection error due to a difference in the measurement position can be removed.

In some cases, the groove specifications may be different between the recorded area and the unrecorded area in a pseudo manner, and as shown in FIG. If it is just the boundary between the unrecorded area and the unrecorded area, the tilt amount may not be measured stably. Therefore, FIG.
As shown in (b) and (c), when measuring the asymmetry Yb of the groove crossing signal by shifting the lens by a fixed amount, two points separated by a distance of at least twice the amount of lens shift are included. By measuring the amount of tilt at three locations, it can be expected that at least two or more of the three locations are not boundaries between the recorded area and the unrecorded area.

Therefore, the tilt amount is determined from the two measured tilt values that are close to each other among the three measured tilt values, so that the tilt measurement position is exactly at the boundary between the recording area and the unrecorded area. The tilt detection error can be eliminated.

Next, even if there is no tilt and no lens shift due to the displacement of the optical system of the optical head 101, the asymmetry of the groove of the disk, or the offset of the circuit system such as the detection circuit, the push-pull operation is performed. Pull tracking error signal P
PTE groove crossing signal asymmetry Y = (AB) / (A +
B) is not always zero. In other words, even if the value of the tilt detection amount obtained by the above method is zero, the actual tilt is not always zero.

Therefore, for example, as shown in FIG.
The tilt detection amount at the innermost circumference of the disk, where the actual tilt amount is expected to be the minimum, among the tilt detection amounts in the entire region in the disk radial direction obtained by tilt measurement and approximation, is represented by T
With respect to the tilt detection amount other than the innermost circumference of the disk, a value obtained by subtracting a uniform T1 (for example, T2−T1) is used as the tilt amount at the disk position. Thereby, it is possible to remove a tilt detection error caused by a shift of the optical system, an asymmetry of the groove of the disk, or an offset of a circuit system such as a detection circuit.

Further, the actual tilt may not always be zero even at the innermost circumference of the disk. Therefore,
As shown in FIG. 9B, in a disc having an embossed signal area at the innermost circumference, the embossed signal is reproduced and the tilt correction means is driven, thereby maximizing the signal amplitude or jitter of the embossed signal. The tilt amount Te which is the optimum condition for reproducing the emboss signal is obtained.

Then, the tilt measurement value at the innermost circumference of the disk whose position in the disk radial direction is closest to the embossed area or
A value obtained by subtracting the difference (T1-Te) from the calculated value T1 from the tilt detection amount Tn at each position on the disk (for example, T2-
By using (T1-Te)) as a tilt amount at the disk position, a tilt detection error or a disk error caused by a shift of an optical system or asymmetry of a groove of the disk, an offset of a circuit system such as a detection circuit, or the like is obtained. It is possible to remove a tilt detection error caused by an inclination due to mounting between the device and the turntable.

The above-described calculation of the tilt amount in the entire area of the disc is performed, for example, by inserting the disc into the drive,
It is conceivable to perform this as initial learning when starting up the drive. Also, after the drive is started, during the time of a standby state of the information reproducing operation from the disk or the information recording operation on the disk, the tilt amount at the point of the reproducing or recording operation is detected, and the It is conceivable to correct the tilt calculation amount during learning.

In the first embodiment, the servo processor 109 compares Tc or Td obtained in advance for each of the plurality of tilts with Tc or Td for the disk whose tilt is to be detected.
Although the tilt of the disc is detected, the servo processor 109 compares Ya or Yb obtained in advance for each of the plurality of tilts with Ya or Yb of the disc whose tilt is to be detected, and The tilt may be detected.

In the above description, Yb is a difference between two lens shift positions, but a value at one lens shift position may be used.

In the first embodiment, the servo processor 109 compares the Tc obtained in advance for each of the plurality of tilts with the Tc of the disk whose tilt is to be detected. The reciprocal of Tc for each tilt (Tc) ^-1 =
Yb / Ya is obtained in advance, and its (Tc) ^-1 and
(Tc) for a disc for which tilt is to be detected
The tilt of the disc may be detected by comparing ^-1 = Yb / Ya.

(Embodiment 2) FIG. 10 is a block diagram showing an example of the configuration of a drive device for an optical recording medium according to Embodiment 2 of the present invention. Except for the tilt correction method, the configuration is the same as that of the first embodiment, and the description is omitted. The servo processor 109 that has generated the tilt detection signal outputs the focus offset drive signal corresponding to the tilt detection signal to F
It is supplied to the C driver 117a.

On the other hand, the drive unit 102 moves the convergent lens 103 in the disc radial direction by giving a difference in the amount of current flowing through each of the focus coils provided at both ends of the convergent lens 103 in the focus direction. It is configured to rotate and move in the tilt direction. Therefore, the FC driver 117a rotationally drives the driving device 102 in a required rotation direction and rotation angle based on the input focus offset drive signal, and rotationally moves the converging lens 103 in the disc radial direction.

As a result, the inclination of the disk 116 with respect to the optical head 101 is corrected, and a favorable tilt condition can be maintained when recording and reproducing the disk.

[0088]

As described above, according to the present invention, the inclination of the disk with respect to the optical head can be detected without providing a tilt sensor in the disk drive device, and the size and cost of the optical disk device can be reduced. The advantageous effect that it can be obtained is obtained.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing a structural example of a photodetector as an embodiment of the present invention, and a block diagram conceptually showing a configuration example of an embodiment for generating a difference signal from an output of the photodetector.

FIG. 3 is an explanatory diagram for explaining an influence of a tilt of a push-pull TE signal obtained when the disk crosses a groove in the embodiment of the present invention;

FIG. 4 is a characteristic diagram for explaining a tilt amount detection method according to the embodiment of the present invention;

FIG. 5 is a diagram illustrating a push-pull T according to an embodiment of the present invention.
Block diagram and waveform diagram conceptually showing a configuration example for detecting a tilt amount from an E signal

FIG. 6 is a characteristic diagram for explaining a method of calculating a tilt amount in the embodiment of the present invention.

FIG. 7 is an explanatory diagram for explaining an operation of the optical head when measuring a tilt amount in the embodiment of the present invention.

FIG. 8 is an explanatory diagram for explaining an operation of the optical head at the time of measuring a tilt amount in the embodiment of the present invention.

FIG. 9 is a characteristic diagram for explaining a method of calculating a tilt amount in the embodiment of the present invention.

FIG. 10 is a block diagram illustrating a configuration of an optical disc device according to a second embodiment of the present invention;

FIG. 11 is a block diagram showing a configuration of an embodiment of a conventional optical disk device.

[Description of Signs] 101, 1101 ... Optical head 102 ... Driving device 103 ... Convergent lens 104 ... Laser diode 105, 201 ... Photodetector 106 ... RF amplifier 107 ... Binarization circuit 108 Decoder 109 Servo processor 110 Laser driver 111, 1107 Transfer driver 112, 1108 Transfer motor 113, 1106 Spindle driver 114, 1103 ... · Spindle motor 115 ··· System controllers 116 and 1112 ··· Disks 117 and 1111 ··· Focus / tracking driver 117a ··· Focus driver 117b ··· Tracking driver 118 and 1109 ··· Tilt driver 119 and 1110 · ..Tilt Data 202: Differential amplifier 203: Addition amplifier 204: Divider 501: Upper envelope detection circuit 502: Lower envelope detection circuit 503: Operational amplifier 504: Average value Detection circuit 505: One rotation detection circuit 1102: Tilt sensor 1104: Reproduction circuit 1105: Control circuit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuo Momio 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 5D118 AA03 BA01 CA07 CA22 CB01 CD04 CF03 CG02 DA35

Claims (15)

[Claims] 1. A light source that emits light, light converging means for converging light from the light source on an optical disk, and means for detecting reflected light from the optical disk, the light source corresponding to a rotation direction of the optical disk An optical head having at least a detecting means having a first light receiving area and a second light receiving area substantially divided into two by a dividing line; and a transferring means for transferring the optical head substantially in a radial direction of the optical disc. When the light converging means is fixed at a predetermined position in the optical head, the first light receiving region and the second light receiving region are moved when the optical head is moved substantially in the radial direction of the tilt detection optical disk. A difference between a high output side level and a low output side level of a signal waveform formed by a difference in the amount of light detected between the optical head and the optical head with respect to the tilt detection optical disk. The correspondence between the tilt unit, a storage unit storing in advance for each of a plurality of the tilt, when the light converging means is fixed to the predetermined position,
When the optical head is moved in a substantially radial direction of the optical disk, a high output side level and a low level of a signal waveform formed by a difference in light amount detected between the first light receiving area and the second light receiving area. A tilt detecting unit that detects a tilt of the optical head or the light converging unit with respect to the optical disk by using a difference between the output level and the correspondence stored in the storage unit. Characteristic optical disk device. 2. A light source for emitting light, light converging means for converging light from the light source on an optical disc, moving means for moving the light converging means substantially in a radial direction of the optical disc, A first light receiving area and a second light receiving area substantially divided into two by a dividing line corresponding to a rotation direction of the optical disc.
An optical head having at least a detecting means having a light receiving area, a transferring means for transferring the optical head substantially in a radial direction of the optical disc, and the light converging means at a predetermined first position in the optical head. A signal that forms a difference in the amount of light detected between the first light receiving area and the second light receiving area when the optical head is moved in a substantially radial direction of the tilt detecting optical disk when fixed. A first difference between a high output side level and a low output side level of a waveform, and the optical head for tilt detection when the light converging means is fixed at a predetermined second position in the optical head. When the light beam is transferred substantially in the radial direction, the difference between the light amount detected in the first light receiving area and the light amount detected in the second light receiving area is the second of the high output side level and the low output side level of the signal waveform. A first ratio with a difference of two; Storage means for preliminarily storing a correspondence relationship between the tilt of the optical head or the light converging means with respect to the tilt detection optical disc, and a plurality of the tilts, wherein the light converging means is fixed at the first position. When
When the optical head is moved in a substantially radial direction of the optical disk, a high output side level and a low level of a signal waveform formed by a difference in light amount detected between the first light receiving area and the second light receiving area. A third difference from an output side level, wherein when the light converging means is fixed at the second position, the optical head moves substantially radially of the optical disc;
A second ratio of a fourth difference between a high output side level and a low output side level of a signal waveform formed by a difference in light amount detected between the first light receiving area and the second light receiving area; An optical disc apparatus comprising: a tilt detecting unit that detects a tilt of the optical head or the light converging unit with respect to the optical disc by using the correspondence stored in the storage unit. 3. A light source for emitting light, light converging means for converging light from the light source on the optical disc, moving means for moving the light converging means substantially in a radial direction of the optical disc, A first light receiving area and a second light receiving area substantially divided into two by a dividing line corresponding to a rotation direction of the optical disc.
An optical head having at least a detecting means having a light receiving area, a transferring means for transferring the optical head substantially in a radial direction of the optical disc, and the light converging means at a predetermined first position in the optical head. A signal that forms a difference in the amount of light detected between the first light receiving area and the second light receiving area when the optical head is moved in a substantially radial direction of the tilt detection optical disk when fixed. A first difference between a high output side level A1 and a low output side level B1 of the waveform, and tilt detection of the optical head when the light converging means is fixed at a predetermined second position in the optical head; Output level A2 and low output level of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area when the optical disk is transported substantially in the radial direction of the optical disc. Second difference from B2 The first
Storage means for storing in advance a relationship between a first ratio of the tilt and the tilt of the optical head or the light converging means with respect to the tilt detection optical disc, for each of the plurality of tilts; When the light converging means is fixed at the first position,
When the optical head is moved substantially in the radial direction of the optical disk, a high output side level A 'of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area. 1 and a third difference between the low output side level B′1 and
When the light converging means is fixed at the second position,
When the optical head is moved substantially in the radial direction of the optical disk, a high output side level A 'of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area. Using the second ratio of the second difference between B2, the low output side level and the fourth difference between B'2 and the third difference, and the correspondence stored in the storage means, An optical disc device comprising: a tilt detecting unit that detects a tilt of the optical head or the light converging unit with respect to the optical disc. 4. The high-output-side level A
1 is replaced by a first asymmetry Y1, which is a value obtained by dividing the difference between the low output side level B1 and the high output side level A1 and the low output side level B1, and the second difference Is replaced by a second asymmetry Y2 which is a value obtained by dividing the difference between the high output side level A2 and the low output side level B2 by the sum of the high output side level A2 and the low output side level B2. Wherein the first ratio is equal to the first asymmetry Y1 and the first asymmetry Y1.
Is replaced by the ratio of the difference between the asymmetry Y1 and the second asymmetry Y2, and the third difference is the difference between the high output side level A′1 and the low output side level B′1. , The high output side level A′1
And a third asymmetry Y3 that is a value obtained by dividing the sum by the low output side level B′1 and the low output side level B′1, and the fourth difference is obtained by dividing the high output side level A′2 and the low output side level B ′. The difference with the high output side level A'2
And a fourth asymmetry Y4 that is a value obtained by dividing the sum by the low output side level B′2 and the second ratio is obtained by dividing the third asymmetry Y3 by the third asymmetry Y3.
4. The optical disk device according to claim 3, wherein the ratio is replaced by the ratio of the difference between the third asymmetry Y3 and the fourth asymmetry Y4. 5. A light source for emitting light, light converging means for converging light from the light source on an optical disc, moving means for moving the light converging means substantially in a radial direction of the optical disc, A first light receiving area and a second light receiving area substantially divided into two by a dividing line corresponding to a rotation direction of the optical disc.
An optical head having at least a detecting means having a light receiving area, a transferring means for transferring the optical head substantially in a radial direction of the optical disc, and the light converging means at a predetermined first position in the optical head. A signal that forms a difference in the amount of light detected between the first light receiving area and the second light receiving area when the optical head is moved in a substantially radial direction of the tilt detection optical disk when fixed. A first difference between a high output side level A1 and a low output side level B1 of the waveform, and tilt detection of the optical head when the light converging means is fixed at a predetermined second position in the optical head; Output level A2 and low output level of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area when the optical disk is transported substantially in the radial direction of the optical disc. Second difference from B2 An optical head for tilt detection when the light converging means is fixed to a predetermined third position in the optical head opposite to the first position with respect to the first position; The high output side level A3 and the low output side level B3 of the signal waveform formed by the difference in the amount of light detected between the first light receiving area and the second light receiving area when the light is transferred substantially in the radial direction. The first difference, the first ratio of the difference between the second difference and the third difference, and the optical head or the optical convergence with respect to the tilt detection optical disk. A storage unit that stores in advance a correspondence relationship with the tilt of the unit for each of the plurality of tilts, and when the light converging unit is fixed at the first position,
When the optical head is moved substantially in the radial direction of the optical disk, a high output side level A 'of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area. 4 and the fourth difference between the low output side level B′1 and
When the light converging means is fixed at the second position,
When the optical head is moved substantially in the radial direction of the optical disk, a high output side level A 'of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area. 5 and the fifth difference between the low output side level B′2 and
When the light converging means is fixed at the third position,
When the optical head is moved substantially in the radial direction of the optical disk, a high output side level A 'of a signal waveform formed by a difference in the amount of light detected between the first light receiving area and the second light receiving area. The fourth difference, the second ratio of the difference between the fifth difference and the sixth difference, and the storage means. An optical disk device comprising: a tilt detecting unit configured to detect a tilt of the optical head or the light converging unit with respect to the optical disk using the correspondence stored in the optical disk. 6. The high-output-side level A
1 is replaced by a first asymmetry Y1, which is a value obtained by dividing the difference between the low output side level B1 and the high output side level A1 and the low output side level B1, and the second difference Is replaced by a second asymmetry Y2 which is a value obtained by dividing the difference between the high output side level A2 and the low output side level B2 by the sum of the high output side level A2 and the low output side level B2. The third difference is a value obtained by dividing the difference between the high output side level A3 and the low output side level B3 by the sum of the high output side level A3 and the low output side level B3. 3 wherein the first ratio is equal to the first asymmetry Y1 and the second asymmetry Y3.
Is replaced by the ratio of the difference between the asymmetry Y2 and the third asymmetry Y3, and the fourth difference is the difference between the high output side level A′1 and the low output side level B′1. , The high output side level A′1
And a fourth asymmetry Y4 which is a value obtained by dividing by a sum of the low output side level B′1 and the low output side level B′1. The difference with the high output side level A'2
And a fifth asymmetry Y5 which is a value obtained by dividing the sum by the low output side level B′2 and the low output side level B′2. The sixth difference is obtained by dividing the high output side level A′3 and the low output side level B ′. The difference from the high output side level A'3
And the sixth level of asymmetry Y6, which is a value obtained by dividing by the sum of the low output side level B′3, and the second ratio is obtained by dividing the fourth asymmetry Y4 by the fifth level.
6. The optical disk device according to claim 5, wherein the ratio is replaced by the ratio of the difference between the asymmetry Y5 and the sixth asymmetry Y6. 7. The high-output-side level and the low-output-side level are an average value of each output level detected during an integer rotation of the optical disk, or an intermediate value between a maximum value and a minimum value of each output level. 7. The optical disk device according to claim 1, wherein the value is a value. 8. The optical head for the tilt detection optical disk and first detection information obtained by raising the first ratio to a power of a constant coefficient n and further multiplying the first ratio by a constant coefficient k. Alternatively, the correspondence relationship between the light converging means and the tilt is stored in advance for each of the plurality of tilts. The tilt detecting means raises the second ratio to the power of the coefficient n, and further multiplies the coefficient k times 8. A tilt of the optical head or the light converging means with respect to the optical disc is detected using the second detection information and the correspondence relationship as the second detection information. An optical disc device according to any one of the above. 9. A light amount detected between the first light receiving region and the second light receiving region, and the difference is detected between the first light receiving region and the second light receiving region. 9. The optical disk device according to claim 1, wherein the value is replaced by a value obtained by dividing the sum by 10. The apparatus according to claim 1, further comprising a tilt correcting unit configured to correct a tilt of the optical head or the light converging unit with respect to the optical disk based on the tilt detected by the tilt detecting unit. 10. The optical disk device according to any one of items 9. 11. The tilt detecting means detects the tilt in the entire radial area of the optical disc from the signal waveforms at two or more points between the substantially innermost circumference and the substantially outermost circumference of the optical disc. The optical disk device according to claim 1, wherein the optical disk device detects. 12. The transfer means moves the optical head when the light converging means is located at the second position or the third position. 3. The light beam converging means is moved by an amount substantially equal to the amount moved to the second position or the third position in a direction substantially opposite to the direction in which the light converging means moves.
12. The optical disk device according to any one of items 1 to 11. 13. The measurement of the signal waveform may be substantially the difference between the first position and the second position of the light converging means or the difference between the first position and the third position. It is performed at three positions where the optical head is transferred to a position separated by a distance of at least twice, and two of the tilt values detected based on the signal waveforms at the three positions are determined based on two adjacent values. 13. The optical disk device according to claim 1, wherein the tilt is determined. 14. A difference (T.sub.T) between the tilt detection amount Tn in the entire radial direction of the optical disk or each point in the radial direction and the tilt detection amount T1 in the innermost circumference of the optical disk.
14. The optical disk device according to claim 1, wherein the optical disk device is replaced by (n-T1). 15. The optical disc in which the tilt detection amount Tn in the entire area in the radial direction or each point in the radial direction of the optical disc is set to the tilt detection amount T1 at the innermost circumference of the optical disc and the reproduction state of the inner peripheral emboss signal is optimum. 14. The optical disk device according to claim 1, wherein a value (Tn- (T1-Te)) obtained by subtracting a difference (T1-Te) from the inclination Te of the optical head with respect to the optical head is replaced by {Tn- (T1-Te)}.