JP2000057606A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the incident angle of a beam without separately providing an optical head with a sensor by respectively detecting reproduction states relating to the inner peripheral side addresses and outer peripheral side addresses of tracks and controlling a tilt in such a manner that the reproduction errors on the inner peripheral side and outer peripheral side within a specified period are made the same number. SOLUTION: A tilt shaft 6 is rotated by a tilt motor 8 and one end of a traversing shaft 4 is moved in a direction perpendicular to the plane of the optical disk 1 by means of a nut piece 7, by which the incident angle of the light beam from the optical head in the radial direction to the optical disk 1 is controlled. A tracking detector 10 sends the detected tracking error signals to a microcomputer 15 via inner peripheral side and outer peripheral side address error detecting circuits 13, 14 by the inner peripheral side and outer peripheral side of the target tracks. This microcomputer 15 counts and compares the inner peripheral side and outer peripheral side address errors respectively by each of three rotation periods of, for example, the optical disk 1 and controls the tilt motor 8 according to the results thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device having tilt control.

[0002]

2. Description of the Related Art In recent years, a digital versatile disk (hereinafter referred to as a DVD) has been proposed as a large-capacity optical disk replacing a compact disk (commonly called a CD). DV
In D, in order to realize a large capacity that is 7 times or more the CD ratio, the wavelength of the light beam to be used is set to 65 nm which is shorter than 780 nm of CD.
A red semiconductor laser of 0 nm is employed, and an objective lens for converging a light beam uses 0.6 which is larger than the numerical aperture of CD of 0.43.

As a result, a light spot obtained by converging a light beam is converged extremely finely with a half value width of about 0.6 μm as compared with a conventional CD. However, assuming that the wavelength of the light beam is generally λ, the tilt margin becomes smaller in inverse proportion to λ / (NA * NA * NA), that is, the cube of NA. Therefore D
In VD, the permissible value for tilt change is smaller than that of CD, and DVD-RAM, which is a DVD medium that can be repeatedly recorded, requires tilt control for detecting and controlling the incident angle of a light beam on a disk.

[0004]

In the tilt control, the detection of the incident angle of the light beam on the optical disk is usually realized by a reflection type photocoupler which is a kind of an optical sensor mounted on an optical head as shown in FIG. ing. The photocoupler includes an LED and a two-part photosensor. For example, as shown in FIG. 2, in the case of an optical disk, when there is a tilt such that the outer peripheral side is lower than the inner peripheral side, the amount of light reflected on the outer peripheral side sensor of the two-segment photosensor increases as compared to the case where there is no tilt. . Conversely, when there is a tilt such that the inner peripheral side is lower than the outer peripheral side, the amount of light reflected on the inner peripheral side sensor of the two-part photosensor increases. Therefore, the incident angle of the light beam on the optical disk has been conventionally detected by taking the differential output of each of the two-divided photosensors.

However, when such a photocoupler is mounted on an optical head, a dead load is mounted on the optical head, so that the mass of the movable portion of the head increases and the search performance decreases. In addition, the number of signal lines to the head movable portion increases for power supply to the photocoupler and signal detection. Furthermore, a malfunction may occur due to adhesion of dust and dust to the photocoupler, and the required performance may not be secured.

[0006]

SUMMARY OF THE INVENTION The present invention detects an incident angle of a light beam required for tilt control, which is essential for a high-density optical disk, on the optical disk without using a separate sensor such as a photocoupler. It is intended to realize an optical disk device. Therefore, in the present invention, a tilt means for changing an incident angle of a light beam applied to an optical disc for recording / reproducing information, and an address for identifying a track on the optical disc for recording information, and reproducing the information. A reproducing state detecting means for detecting and outputting a state, an output of the reproducing state detecting means when the tilting means is set in such a direction that an incident angle of the light beam on the inner peripheral side of the optical disk in the radial direction with respect to the optical disk decreases by a predetermined amount; The tilt means is operated based on the output of the reproduction state detecting means when the tilt means is set so that the incident angle on the outer peripheral side decreases by a predetermined amount. In the present invention, in particular, the DV is composed of at least one set of an inner peripheral address and an outer peripheral address in which the address is shifted inward and outward by a predetermined distance from the center of the track in the radial direction of the optical disk.
In an optical disc such as a D-RAM, the reproduction state detecting means detects the reproduction state of the inner side address and the reproduction state of the outer side address, respectively, and the reproduction error of the inner side address and the outer side address within a predetermined period is substantially reduced. The tilt means are operated so as to have the same number.

Thus, an inexpensive and highly reliable optical disk device is realized by detecting and correcting the incident angle of the light beam on the optical disk without using a separate sensor such as a photocoupler.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 is a tilt means for changing an incident angle of a light beam applied to an optical disk for recording / reproducing information, and a track on the optical disk for recording information. A reproducing state detecting means for reproducing an address for identification and detecting and outputting the reproducing state is provided, and by operating the tilt means in accordance with an output of the reproducing state detecting means, the light beam to the optical disk is This has the effect that the incident angle can be optimally controlled.

According to a second aspect of the present invention, there is provided a disk comprising at least one set of an inner peripheral address and an outer peripheral address in which the address is shifted inward and outward by a predetermined distance in the radial direction of the optical disk from the center of the track. Then
The reproducing state detecting means has an effect that the angle of incidence of the light beam on the optical disk can be optimally controlled by operating the tilt means by detecting the reproducing state of the inner address and the reproducing state of the outer address, respectively. .

In the invention according to claim 3 of the present invention, the address includes a code for reproducing error detection, and the reproducing state detecting means detects a reproducing error of the address based on the reproducing error detecting code and controls the tilt means. The operation has an effect that the incident angle of the light beam to the optical disk can be optimally controlled.

According to a fourth aspect of the present invention, the tilt means is operated so that reproduction errors of the inner peripheral address and the outer peripheral address within a predetermined period are substantially the same.
This has the effect that the angle of incidence of the light beam on the optical disc can be optimally controlled.

According to a fifth aspect of the present invention, the tilting means is operated so that the reproduction errors of the inner peripheral address and the outer peripheral address with respect to a predetermined number of addresses become substantially the same, whereby the light beam is incident on the optical disk. This has the effect that the angle can be optimally controlled.

According to a sixth aspect of the present invention, the output of the reproducing state detecting means when the tilt means is set in such a direction that the incident angle of the light beam on the optical disc radially inner side with respect to the optical disc decreases by a predetermined amount, and By operating the tilt means based on the output of the reproduction state detecting means when the tilt means is set in such a direction that the incident angle on the side decreases by a predetermined amount, the incident angle of the light beam to the optical disc is optimized. It has the effect of being controllable.

According to a seventh aspect of the present invention, an operation value of the tilt means at a plurality of positions in the disk radial direction is stored in advance, and position detecting means for detecting the position of the light beam in the disk radial direction is provided. By operating the tilt means based on the stored operation value corresponding to the position detected by the position detection means, an effect that the incident angle of the light beam on the optical disk can be optimally controlled regardless of the position in the radial direction of the optical disk. Have.

According to an eighth aspect of the present invention, in the track search for moving the light beam to an arbitrary target track, the tilt means is operated based on the output of the reproduction state detecting means after at least reaching the vicinity of the target track. By doing so, there is an effect that the angle of incidence of the light beam on the optical disk at the target track can be optimally controlled irrespective of the position in the radial direction of the optical disk in the track search.

According to a seventh aspect of the present invention, after reaching the target track at least, after operating the tilting means based on the output of the reproduction state detecting means, it is notified to the outside that the track search has been completed. Accordingly, an effect that the incident angle of the light beam on the optical disk at the time of reading or recording information from the optical disk can be controlled optimally regardless of the position in the radial direction of the optical disk.

(Embodiment 1) Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an optical disk drive 1 according to the present invention.
It is a block diagram of an example. In FIG. 1, an optical head 3 equipped with a set of optical systems for reading information from or writing information to an optical disk 1 rotated by a disk motor 2 is mounted on a traverse shaft 4 having a spiral feed groove and a base 9. When the traverse shaft 4 is rotated by a traverse motor 5 fixed to the optical disk 1, the optical disk 1 can move freely in the radial direction. The other end of the traverse shaft 4 is connected via a nut piece 7 to a tilt shaft 6 which also has a spiral feed groove and is installed substantially perpendicular to the disk surface of the optical disk 1. The tilt shaft 7 is configured to be rotatable by a tilt motor 8 fixed to the base 9, and only one end of the traverse shaft moves together with the nut piece 7 in a direction substantially perpendicular to the disk surface by rotation of the tilt motor 8. This makes it possible to freely change the incident angle of the light beam incident on the optical disc 1 from the optical head 3 in the radial direction of the optical disc 1.

On the optical head 3, a semiconductor laser as a light source, an objective lens for converging and irradiating a light beam emitted from the light source onto the disk, and responding to surface deflection and eccentricity of the optical disk 1, 1 is equipped with a detection optical system and an actuator for focus control and tracking control for a light beam to follow a track for recording and reproducing information on the same while always maintaining a predetermined convergence state (not shown). .

The reflected light from the optical disc 1 is incident on a tracking detector 10 for detecting a tracking error signal (hereinafter referred to as a TE signal) not shown. The tracking detector 10 has a two-part structure, and detects a TE signal from a differential output of the two detectors by a push-pull method. Since the push-pull method and the optical system configuration for realizing the push-pull method are generally known, the detailed configuration and description thereof will be omitted. The output of each detector of the tracking detector 10 is input to a differential circuit 11 for detecting a TE signal. The TE signal output from the differential circuit 11 is output to the tracking control circuit / actuator as described above to constitute a tracking control system for following the information track, but the description is omitted in FIG. The TE signal output from the differential circuit 11 is an address reading circuit 1 for reading an address provided for identifying each information track on the optical disc 1 described in detail later.
2. These are also input to an inner address error detecting circuit 13 and an outer address error detecting circuit 14 which detect reading errors of an inner address and an outer address, respectively, which will be described later. The address value read by the address reading circuit 12 and the inner address error detecting circuit 1
3 and the outer-peripheral address error detected by the outer-peripheral address error detection circuit 14, respectively, are output to the microcomputer 15, and the microcomputer 15 determines the address of the information track currently traced by the light beam and the inner-peripheral address. It is configured such that it is possible to know independently that an error has occurred in reading the addresses on the outer and outer peripheral sides.

The traverse motor 5 and the tilt motor 8 are connected to the microcomputer 15 via D / A converters (hereinafter referred to as D / A) 16 and 17.
The optical head 3 drives the traverse motor 5 by outputting an arbitrary digital value to the D / A 16, 17.
Can be arbitrarily moved in the radial direction of the optical disk 1, and the tilt motor 8 can also be driven to freely change the incident angle of the light beam on the optical disk 1 in the radial direction of the optical disk 1. .

FIG. 3 is a schematic configuration diagram of the optical disk 1.
On the optical disk 1, a groove track 18 (shown by hunting in FIG. 3) constituted by a groove having a convex structure having an optical depth of approximately λ / 8 and a land which is a concave portion interposed between the groove tracks. Track 19 (in FIG. 3,
(Shown in white) are alternately connected every turn of the disc. More specifically, a groove track and a land track are connected at a site indicated by a circle in FIG. Both the groove track 18 and the land track 19 are divided into a plurality of sectors which are the minimum units for recording data in one turn of the disk. FIG. 4 shows a structural diagram of the sector. FIG. 4 shows an enlarged portion of about one sector which is a part of a plurality of tracks. In FIG. 4, the vertical direction corresponds to the radial direction of the optical disk 1, and the light beam traces FIG. 4 from left to right by rotating the disk. As in FIG. 3, the groove track 18 is hunted, and the land track 19 is outlined. Each sector includes an address portion for identifying a sector or a track and a data portion for recording data. The address portion is formed by pits which are intermittent grooves of approximately λ / 8 in optical depth, and information is written at the time of molding the disc according to the presence or absence of the pits. The address portion of the optical disc 1 used in the present embodiment includes an inner address 20 and an outer address 2.
1. The inner peripheral address 20 is an address arranged at a position offset to the inner peripheral side of a 1/4 groove pitch with respect to the groove track, and is indicated by hunting with oblique lines rising to the right in FIG. On the other hand, the outer peripheral side address is an address arranged at a position offset to the outer peripheral side by 1/4 groove pitch with respect to the groove track, and is indicated by hunting with a diagonally downward slanted line in FIG. When the light beam traces the groove track 18, the light beam first traces the outer address 21 and then the inner address 20. This is the same when the light beam traces the land track 19. Therefore, the outer address error detection circuit 14 shown in FIG. 1 takes in all preceding addresses on the time axis for each sector and detects an error of the outer address using an error detection code described later. The inner address error detection circuit 13 takes in all subsequent addresses on the time axis for each sector and detects an error in the inner address using an error detection code described later.

However, when viewed from the light beam tracing the land track, the outer address 21 is located on the inner side and the inner address 20 is located on the outer side with respect to the light beam. Further, a unique address number is assigned to each inner side address 20 and each outer side address 21. The address numbers can be read by the address reading circuit 12 shown in FIG. From the combination of the address numbers of the peripheral address and the peripheral address, it is possible to determine not only which sector the microcomputer light beam is currently tracing, but also whether it is tracing a groove track or a land track. It is configured as follows. Further, a CRC (circular redidency c) for detecting a reading error is provided in the inner peripheral address 20 and the outer peripheral address 21.
mode), and the inner address error detecting circuit 13 and the outer address error detecting circuit 14 shown in FIG. 1 calculate the CRC of the inner address 20 and the outer address 21 from the read values, respectively. It is configured to be able to determine whether or not a reading error has occurred.

Next, a tilt correction operation of the optical disk device according to the present invention will be described in detail with reference to the embodiment of FIG. The operation of the optical disk device of this embodiment can be divided into the following steps.

That is, 1) tilt correction operation at an arbitrary position. 2) tilt correction operation in track search.

The above 2) "tilt correction operation in track search" includes a) reception of a track search command b) movement to a target track or its vicinity c) tilt correction operation at a target track or its vicinity d) truck It can be divided into command completion reports for search commands.

In the present embodiment, "tilt correction operation at an arbitrary position" will be described first, and then "tilt correction operation in track search" will be described in this order.

FIG. 5 is a flowchart showing the processing of the tilt correction operation at an arbitrary position in this embodiment.

Prior to the correction operation, the description of the structure is first omitted, but it is assumed that focus control and tracking control for tracing a track on the optical disk 1 with a predetermined focusing state of the light beam are operating. Since the connection is made alternately for each turn, the light beam traces the groove track and the land track alternately for each rotation cycle. However, the jumping operation is performed for each rotation of the optical disc 1, and only the groove track is performed. Or a still jump that always traces only the land track. In this state, the microcomputer 15 reads the address value input from the address reading circuit 12, and determines whether the track performing the still jump is a groove track or a land track. Next, the microcomputer 15 sets the set value A to the D / A 17 to 0, and
Output to A17. Thereby, the microcomputer 15 drives the tilt motor 8 to set the traverse shaft 4 connected via the nut piece 7 at a predetermined angle with respect to the base 9. More specifically, D
The initial value of / A17 is A = 0, and at this time, the tilt motor 8 is rotated and the traverse shaft 4 is stopped at a position where it is horizontal with respect to the base 9.
A set value from the microcomputer 15 for the D / A 17;
When the microcomputer 15 sets a positive value to the D / A 17 from the microcomputer 15, the tilt motor 8 rotates by an amount corresponding to the absolute value of the value set in the direction in which the nut piece 7 rises. The incident angle of the light beam on the inner peripheral side with respect to the optical disc 1 is configured to increase by an amount corresponding to the absolute value of the set value to the D / A 17 (hereinafter, the incident angle of the inner peripheral side of the optical beam with respect to the optical disc 1 is thus set). The increase in the incident angle is also referred to as “increase in the inner peripheral tilt angle”).
When a negative value is set in the D / A 17, the tilt motor 8 rotates in the direction in which the nut piece 7 descends by an amount corresponding to the absolute value of the set value, and the optical disk 1 of the light beam is rotated.
The incident angle on the outer peripheral side with respect to the optical disk 1 is increased (hereinafter, the increase in the incident angle on the outer peripheral side of the light beam with respect to the optical disk 1 is also referred to as “the outer peripheral tilt angle is increased”). Next, the microcomputer 15 is a D / A 17
, A positive predetermined value B is added to the set value A, and A = A + B is output. As a result, the tilt motor 8 rotates before the nut piece 7 rises, and the incident angle of the light beam on the inner peripheral side with respect to the optical disc 1 increases. In this state, the microcomputer 15 separately counts the number of reading errors of the outer address and the number of reading errors of the inner address output from the outer address error detecting circuit 14 and the inner address error detecting circuit 13, respectively. Start operation. The microcomputer 15 performs this counting operation over a predetermined time using a timer (not shown) built in the microcomputer 15. Usually, the period during which this measurement operation is performed is shorter than the disk rotation period, specifically, a period corresponding to a few rotation periods. The purpose of this is to absorb and correct the change in the read state of the address due to the variation or change in the circumferential direction of the optical disc 1, and to measure and compare the read error state of the inner and outer peripheral addresses correctly. The microcomputer 15 stores and holds the number of outer peripheral side address reading errors and the number of inner peripheral side address reading errors measured over the period as N1 and N2, respectively.

Subsequently, the microcomputer 15 subtracts a positive predetermined value 2 * B from the set value A to the D / A 17, and outputs the result as A = A-2 * B. As a result, the tilt motor 8 rotates before the nut piece 7 descends, and the incident angle of the light beam on the outer peripheral side with respect to the optical disk 1 increases. In this state, the microcomputer 15 separates the number of reading errors of the outer address and the number of reading errors of the inner address output from the outer address error detection circuit 14 and the inner address error detection circuit 13 respectively as described above. Starts a counting operation for counting the number. The period during which the counting operation is performed is set to be exactly the same as the case where the incident angle of the light beam to the optical disk 1 on the inner peripheral side is increased, so that the number of addresses through which the light beam has passed during the previous measuring operation period is reduced. It is set to be equal to that of the current measurement operation. The microcomputer 15 stores the number of outer address reading errors and the number of inner address reading errors measured over the above period as T1 and T2, respectively.
At the same time, a predetermined positive value 2 * B is added to the set value A to the D / A 17, and the result is output as A = A + B. Thus, the angle of incidence of the light beam on the optical disk 1 returns to the state before the start of the two counting operations. The reason why the microcomputer 15 measures the difference between the outer-peripheral address and the inner-peripheral address reading error when the tilt angle is increased in the outer peripheral side incident angle and the inner peripheral side incident angle in this manner will be described later. Next, the microcomputer 15 calculates ABS [(T1-T2)-(N2-N1)] <from the stored and held measurement value.
The calculation of E is performed, and when the inequality sign is satisfied, the tilt correction operation ends. Here, ABS [] indicates an absolute value, and E is a positive predetermined value. This is the difference between the number of outer address reading errors and the number of inner address reading errors when the outer tilt angle increases, that is, (T1−T
2) and the difference between the number of inner side address reading errors and the number of outer side address reading errors when the inner side tilt angle increases, that is, when (N2−N1) is substantially equal to or less than a predetermined value E, the light This means that the incident angle of the beam with respect to the optical disc 1, that is, the tilt angle is determined to be set to be substantially appropriate, and the process ends.

If the inequality sign does not hold, the following operation is performed depending on whether the track being traced is a groove track or a land track, and the result is set in the D / A 17. That is, when the light beam traces a groove track, A = A + [(T1-T2)-(N2-N1)] * α. When the light beam traces a land track, A = A-[(T1 −T2) − (N2−N1)] * α where α is a positive correction coefficient.

Thus, when the light beam is tracing the groove track, the difference between the number of outer address reading errors and the number of inner address reading errors when the outer tilt angle is increased is larger than the inner address. If the difference between the number of inner-side address reading errors and the number of outer-side address reading errors when the tilt angle is increasing is larger, it is determined that the outer-side tilt angle is too large, and D / A1 is determined.
By increasing the set value to 7 by a predetermined amount, the tilt angle is increased toward the inner peripheral side and corrected. Conversely, the difference between the number of outer address reading errors and the number of inner address reading errors when the outer tilt angle is increasing is the number of inner address reading errors when the inner tilt angle is increasing. If the difference is smaller than the difference between the number of error readings on the outer peripheral side and the number of addresses on the outer peripheral side, the tilt angle is increased toward the outer peripheral side by reducing the set value to the D / A 17 by a predetermined amount, and the correction is performed. After the above process, the microcomputer 15 returns to the process of adding the positive predetermined value B to the set value A to the D / A 17 again and outputting the result. The microcomputer 15 corrects the tilt angle at an arbitrary position so as to be appropriate by repeating this until the above-mentioned termination condition is satisfied.

Next, in the above-described tilt correction processing, why is the reading error of the outer peripheral side address and the inner peripheral side address when the tilt angle is changed measured, and the correction is performed based on it? Will be described with reference to FIGS. FIG. 6 shows an output waveform of the differential circuit 11 in the address section when the light beam is positioned on the groove track. FIG. 6 (a),
(B) and (c) are plotted when the incident angle of the light beam to the optical disk 1 is appropriate, the inner side is excessive, and the outer side is excessive. In each figure, the lower part of the hunting is the envelope of the outer peripheral address, and the upper right part is the envelope of the inner peripheral address. When the incident angle is proper, the envelope amplitudes of the outer peripheral address and the inner peripheral address are substantially equal, and exist at positions substantially symmetric with respect to the zero level. However, when the incident angle increases, for example, toward the inner circumference, the amplitude of the outer circumference address increases due to aberration caused by tilt, but the amplitude of the inner circumference address rapidly decreases. As a result, in this case, the reading of the inner peripheral address deteriorates, and as a result, many address reading errors occur in the inner peripheral address. Conversely, when the incident angle increases, for example, toward the inner circumference, the amplitude of the inner circumference address increases, but the amplitude of the outer circumference address rapidly decreases, and reading errors of the outer circumference address often occur. Therefore, when the light beam incident angle is changed to the inner side and the outer side,
By comparing the number of read errors between the inner address and the outer address, it is possible to detect whether the incident angle of the light beam is shifted to the inner side or the outer side from the appropriate point. FIG. 7 shows the output waveform of the differential circuit 11 in the address section when the light beam is located on the land track. 7 (a), (b) and (c) show that the incident angle of the light beam to the optical disc 1 is appropriate,
This is plotted when the outer peripheral side is excessive. When the light beam traces the land track, the address waveform is different from the groove track, since the outer address is located on the inner side and the inner address is located on the outer side with respect to the light beam. Reverses the case of the groove.
Therefore, when the incident angle is increased toward the inner side, the inner side address amplitude increases, the outer side address amplitude decreases, and the reading error of the outer side address increases. When the incident angle is increased toward the outer peripheral side, the outer peripheral side address amplitude increases, the inner peripheral side address amplitude decreases, and the reading error of the inner peripheral side address increases. Therefore, when the land track is traced, the polarity of the correction after the measurement operation is reversed as described above.

Next, a tilt correction operation in a track search will be described. The tilt correction operation in the track search is as described above 1) Receiving a track search command 2) Moving to or near the target track 3) Tilt correction operation in or near the target track 4) Command completion report for the track search command Can be divided into

FIG. 8 is a flowchart of tilt correction in the track search operation. At the time of the track search, a search command is issued together with the target track address (ADR1) from the external host personal computer (not shown) to the microcomputer 15. When the search command is issued, the microcomputer 15 reads the address (ADR0) of the track where the light beam is currently located from the address reading circuit 12. Subsequently, the microcomputer 15 calculates the difference between the target track address ADR1 and the current address ADR0, and sets a positive value to the D / A 16 if the calculation result is positive, and a negative value if the calculation result is negative. When a positive value is set in D / A16, D / A
The traverse motor 5 connected to the optical head 16 moves the optical head 3 in the outer circumferential direction by a predetermined distance, and moves the light beam toward and to the target track. Conversely, when a negative value is set in the D / A 16, the traverse motor 5 connected to the D / A 16 moves the optical head 3 in the inner circumferential direction by a predetermined distance, and also shifts the light beam toward the target track. Move closer. The microcomputer 15 executes the above-described “tilt correction operation at an arbitrary position” in a state where tracking control (not shown) is operated at the time of moving to the vicinity of the target track, and as a result, the tilt angle of the light beam becomes It is set almost appropriately in the track to be changed. Thereafter, the microcomputer 15 reads again the address (ADR0) of the track where the light beam is currently located from the address reading circuit 12, and compares it with the target track address. If ADR0 matches the target track address ADR1,
The microcomputer 15 reports the completion of execution of the search command to the host personal computer (not shown), and completes the track search operation. On the other hand, if the target track and the current track address are different, the microcomputer 15 sets a value corresponding to the polarity of the difference between the target track address and the current address in the D / A 16 again, and moves the light beam toward the target track. Perform processing. The microcomputer 15 repeats the above processing until the target track is reached.

[0036]

With this arrangement, even if the disc has a tilted bow, for example, in a bowl shape, the optimum tilt angle on the inner circumference of the disc differs from the optimum tilt angle on the outer circumference. In any case, even when a track search is performed from the inner circumference to the outer circumference or from the outer circumference to the inner circumference, an appropriate tilt angle can be set. Further, since the optimum tilt angle is always set before the search command completion report, there is an advantage that information can be recorded or reproduced on the optical disk immediately after the completion of the search command.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of an optical disk device.

FIG. 2 is a configuration diagram of a conventional tilt detection.

FIG. 3 is a schematic configuration diagram of an optical disc 1;

FIG. 4 is a structural diagram of a sector;

FIG. 5 is a flowchart for tilt correction.

FIG. 6 is a diagram showing an address reproduction waveform (groove track) when a tilt occurs.

FIG. 7 is a diagram showing an address reproduction waveform (land track) when a tilt occurs.

FIG. 8 is a block diagram of a conventional disk motor control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Disk motor 3 Optical head 4 Traverse shaft 5 Traverse motor 6 Tilt shaft 7 Nut piece 8 Tilt motor 9 Base 10 Tracking detector 11 Differential circuit 12 Address reading circuit 13 Inner circumference address error detection circuit 14 Outer circumference address error detection Circuit 15 Microcomputer 16, 17 D / A converter 18 Groove track 19 Land track 20 Inner circumference address 21 Outer circumference address

Claims (8)

[Claims] 1. A tilt means for changing an incident angle of a light beam irradiated on an optical disc for recording / reproducing information,
A reproducing state detecting means for reproducing an address for identifying a track on an optical disk for recording information, detecting and outputting the reproducing state, and operating the tilt means in accordance with an output of the reproducing state detecting means An optical disc device characterized by the above-mentioned. The address is composed of at least one set of an inner peripheral address and an outer peripheral address which are arranged at positions shifted by a predetermined distance in the radial direction of the optical disk from the center of the track to the inner and outer sides. 2. The optical disc apparatus according to claim 1, wherein a reproduction state of the address and a reproduction state of the outer address are detected. 3. The apparatus according to claim 1, wherein the address includes a code for detecting a reproduction error, and the reproduction state detecting means detects a reproduction error of the address based on the code for detecting the reproduction error. Optical disk device. 4. The optical disc apparatus according to claim 3, wherein the tilt means is operated so that the reproduction errors of the inner peripheral address and the outer peripheral address within a predetermined period are substantially the same. 5. The optical disk apparatus according to claim 3, wherein the tilt means is operated such that reproduction errors of the inner peripheral address and the outer peripheral address for a predetermined number of addresses are substantially the same. 6. The output of the reproduction state detecting means when the tilt means is set so that the incident angle of the light beam on the optical disc radially inner side in the radial direction of the optical disc decreases by a predetermined amount, and the incident angle on the outer peripheral side decreases by a predetermined amount. Based on the output of the playback state detection means when the tilt means is set in the direction of
4. The apparatus according to claim 3, wherein the tilt means is operated.
6. The optical disk device according to any one of claims 1 to 5, 7. A track search for moving a light beam to an arbitrary target track, wherein the tilt means is operated based on an output of the reproduction state detecting means after at least reaching the vicinity of the target track. 7. The optical disk device according to any one of 1 to 6. 8. The method according to claim 1, further comprising, after at least reaching the vicinity of the target track, operating the tilt means on the basis of the output of the reproduction state detection means and then notifying the outside that the track search has been completed. 7. The optical disk device according to any one of 6.