JPH10222860A - Optical disk reproducing method and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably read out information from an optical disk. SOLUTION: An inclination of the optical disk is detected by a tilt sensor 13 provided in an inner circumference and a tilt sensor 14 provided in an outer circumference. An inclination of each part of the optical disk is calculated in direction and degree from a result of detecting this inclination in inner circumferential and outer circumferential positions (addresses) so as to be predictive. Thus, by moving an objective lens 3 for the purpose of reproducing information at an address, and at the same time, by driving a tilt servo motor 10 in accordance with an inclination in the position at these addresses based on the predicted calculation result, a deviation from perpendicularity between an optical axis of the objective lens 3 and a reflecting surface of the optical disk is corrected, and hence the information can stably be read out of the optical disk.

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 for reading information from an optical disk such as a video disk, a compact disk, and a magneto-optical disk or writing information to the optical disk, and an optical axis of an objective lens and a reflection surface of the optical disk. The present invention relates to an optical disk reproducing method and an optical disk device capable of correcting a deviation from verticality of an optical disk.

[0002]

FIG. 8 is a perspective view of a conventional optical disk device. 8, a description will be given of a configuration capable of correcting a deviation between the optical axis of the objective lens and the perpendicularity of the reflection surface of the optical disk.

A conventional optical pickup module has a rotation system and an optical system. The rotation system mounts the optical disk on the turntable 1 and rotates about the shaft 2. A carriage 4 mounted on an optical system to be described later and moved in the radial direction of the optical disk, a feed motor 5 for driving the carriage 4, and a main shaft 6 and a guide shaft 7 as guides for moving the carriage 4 are mounted on a base 8. Attached to.

The optical system has an objective lens 3 for reading information recorded on the optical disk, and a tilt sensor A9 mounted on a carriage 4 for detecting the inclination of the optical disk. Then, the tilt servo motor 1 is used to correct the deviation between the optical axis of the objective lens 3 and the perpendicularity of the reflection surface of the optical disk based on the signal from the tilt sensor A9.
0 is mounted on the base 8.

In order to correct the deviation between the optical axis of the objective lens 3 and the perpendicularity of the reflection surface of the optical disk, the tilt servo motor 10 simultaneously moves the main shaft 6 and the guide shaft 7 to reduce the inclination of the objective lens 3. The rotation may be corrected, or the tilt servo motor 10 may be used to move the turntable 1 to correct the rotation surface of the optical disk.

Next, a description will be given of a process until the tilt of the optical disk is detected, the tilt servomotor 10 is driven, and the information on the optical disk is read. FIG. 9 is a flowchart for reading information by correcting a tilt in the related art. In FIG. 9, first, it is assumed that information is read at a certain position on the optical disk (S1). Therefore, an instruction is given that information can be read at another position (S2). Then
Naturally, the feed motor 5 is moved to move the carriage 4 on which the objective lens 3 for reading information is mounted to a predetermined position (S3).

Next, the tilt sensor A9 on the carriage 4
To detect the inclination of the optical disk at a position near the position from which information is being read (S4). Then, based on the detected inclination, a drive command is given to the tilt servomotor 10 in which direction and how much is to be corrected (S
5). Then, according to the driving instruction, the tilt servo motor 1
Then, the carriage 4 or the turntable 1 is moved to correct the deviation between the optical axis of the objective lens 3 and the perpendicularity of the reflection surface of the optical disk (S6). as a result,
Information can be read from a predetermined position on the optical disk (S
7).

Here, a system for detecting the tilt of an optical disk using a general tilt sensor will be described. 10 is a detection optical path diagram of a conventional tilt sensor, FIG. 11 is a plan view of a lens focal plane of FIG. 10, and FIG. 12 is a side view of FIG. 10 to 12, the light source is an infrared ray L.
ED11 is used. The diffused light emitted from the infrared LED 11 is irradiated on the optical disk via the lens, and the reflected light is condensed again by the lens to form a real image of the infrared LED 11 on the two-divided photodetector 12. The position of the real image changes on the two-split detector 12 due to the tilt of the optical disc, and the tilt of the optical disc is detected as a difference between the outputs of the detection elements of the two-split detector 12. In particular, when the infrared LED 11 and the split photodetector 12 are arranged at the focal position of the lens,
Regardless of the state of the reflection surface of the optical disk, only the inclination of the optical disk can be detected purely.

[0009]

FIG. 13 is a diagram showing a form of "warp" of an optical disk. In general, the form of the warp of the optical disk is as shown in FIG.
Most often, it is warped as in (a). More specifically, the inner peripheral portion is maintained substantially flat, and the inclination of the warp increases toward the outer peripheral portion. Other warping forms are described, for example, in FIG.
As shown in FIG. 6 (b), the one warped in the opposite direction to FIG.
As shown in (C), there is an object which is warped in the opposite direction every half circle.

Therefore, these tilts are detected by one of the tilt sensors A9 provided on the carriage 4, and
It has been difficult to detect warpage up to the outer peripheral portion.

Further, in the above-mentioned conventional optical disk apparatus, since the position of the objective lens and the position of the tilt sensor are the same in the radius of the optical disk, the tilt of the optical disk is instantaneously used by using the tilt sensor in synchronization with the reading of information. Is detected,
It is necessary to instantaneously correct the deviation between the optical axis of the objective lens and the perpendicularity of the reflection surface of the optical disk by the detection signal. For this reason, a tilt sensor and a drive servo having extremely high responsiveness are required, and expensive sensors and servo circuits are required.

In particular, when the recording density of an optical disk increases,
It is necessary to correct the tilt of the optical disc with high precision, and a low-cost and high-precision sensor and servo circuit are required.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an optical disk reproducing method and an optical disk apparatus capable of stably reproducing information from an optical disk.

[0014]

In order to achieve this object, an optical disk apparatus according to the present invention detects the inclination of an optical disk by using a tilt sensor B provided on the inner circumference and a tilt sensor C provided on the outer circumference. . Then, based on the detection result of the inclination at each position (address) on the inner circumference and the outer circumference, the inclination direction and the degree of the inclination of each part of the optical disk are calculated and predicted in advance.

In this way, the objective lens is moved in order to reproduce the information of a certain address, and at the same time, the tilt servomotor is driven in accordance with the inclination of the position of the corresponding address to perform the correction based on the calculation result predicted in advance. As a result, the deviation between the optical axis of the objective lens and the perpendicularity of the reflection surface of the optical disk can be corrected, and information can be stably read from the optical disk without the need for high-speed and high-precision servos. An optical disk device can be provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a first method for detecting a deviation between a vertical axis with respect to a surface of an optical disc and an optical axis of an objective lens in an inner peripheral portion of the optical disc.
Angle detection step, a second inclination detection step for detecting a deviation between a vertical axis with respect to the optical disk surface and an optical axis of the objective lens in an outer peripheral portion of the optical disk, and an inner peripheral portion obtained in the first inclination detection step. Radial position inclination calculating step of calculating the inclination of a plurality of positions in the radial direction based on the inclination of the outer peripheral portion obtained in the second inclination detecting step, and the radial position inclination detecting step while rotating the optical disk And calculating the tilt of the entire circumference of the optical disc. And calculating the tilt of the entire circumference of the optical disc. When the objective lens is moved to reproduce information of a certain position on the optical disc, The tilt of the optical axis of the objective lens is corrected by referring to the tilt of the corresponding position from the obtained tilt of the entire circumference of the optical disk. It is possible to provide an optical disc reproducing method that can be read out al information, and has an effect to say.

According to a second aspect of the present invention, there is provided an optical disk rotation driving means for mounting and rotating an optical disk, forming an image of light irradiated on the optical disk on the optical disk surface, and reflecting the light from the optical disk. Optical reading means for condensing light and converting it to an electric signal; moving means for moving the optical reading means in a radial direction of the optical disc; and First inclination detecting means for detecting a deviation between the vertical axis and the optical axis of the optical reading means; Based on the second tilt detecting means for detecting the deviation from the axis, the rotation driving means, the first tilt detecting means, and the second tilt detecting means, the radial direction of the optical disk and its A tilt storage means for calculating and storing the tilt of each position around the entire circumference, wherein the tilt storage means, when loading the optical disc, first reproduces the TOC area. The optical disc is characterized by calculating and storing a tilt of a position, and further comprising a tilt correcting means for correcting a shift of an optical axis of an optical reading means according to the tilt of the position obtained from the tilt storage means. When reproducing the position information, simultaneously operating the moving means, operating the inclination correction means,
Still further, the above-mentioned inclination correcting means is characterized in that a guide member used for moving the moving means is moved to correct the deviation of the optical axis of the optical reading means. An optical disc device characterized by correcting a shift of an optical axis of an optical reading means by moving a tilt of a rotation axis of a driving means moving means,
An optical disk reproducing method capable of stably reading information from an optical disk can be provided.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment) Next, a specific example of the present invention will be described. FIG. 1 is a perspective view of an optical disk device according to an embodiment of the present invention. In FIG. 1, 1 is a turntable, 2 is a shaft, 3 is an objective lens, 4 is a carriage, 5 is a feed motor, 6 is a main shaft, 7 is a guide shaft, 8
Denotes a base and 10 denotes a tilt servomotor. Since these components are the same as those of the conventional optical disk device shown in FIG. 8, the same reference numerals are given and the description will not be repeated.

As a specific configuration of the present invention, a tilt sensor B13 is arranged on the base 8 at a position on the inner peripheral side of the optical disk, and a tilt sensor C14 is arranged on a position on the outer peripheral side of the optical disk. In order to correct the deviation between the optical axis of the objective lens 3 and the perpendicularity of the reflection surface of the optical disk, the tilt servo motor 10 is operated based on the signals of the tilt sensor B13 and the tilt sensor C14 to move the main shaft 6 and the guide. The tilt of the objective lens 3 may be corrected by moving the shaft 7 at the same time, or the rotation surface of the optical disc may be corrected by moving the turntable 1 by the tilt servomotor 10. Although the description in FIG. 1 is omitted, the calculation of the required control amount and the contents of the correction control for correcting the above-described deviation are stored in an electric circuit (not shown) connected by the signal cable 15. You.

FIG. 2 is a flowchart for reading out information by correcting a tilt in one embodiment of the present invention. Next, the process of reading information by correcting the tilt in the present invention will be described with reference to FIG.

First, an optical disk is mounted on the turntable 1 (S11). Next, a TOC read is performed at the innermost position of the optical disk (S12). At the same time, the tilt sensor B13 and the tilt sensor C arranged on the base 8
Using 14, the inclination of the optical disk is measured in synchronization with the inner and outer circumferences of the optical disk (S13). The tilt of each position (address) of the optical disk is calculated by calculating the measured tilt between the inner circumference and the outer circumference of the optical disk (S
14). The operations from step 11 to step 14 are operations in the preparation stage.

Next, a certain position (address) of the optical disk
In the case where information is currently being read (S1
5) It is assumed that an instruction to read information at another position (address) has been received (S16). Then, the carriage 4 on which the objective lens 3 is mounted is moved to a predetermined position by driving the feed motor 5 (S17).

Since the position (address) of the movement destination is known at the same time as the movement of the carriage, the inclination of the optical disk at the position (address) of the movement destination is known based on the result calculated in steps 11 to 14 ( S1
8). Therefore, a drive command indicating in which direction and how much is to be corrected is given to the tilt servo motor 10 (S1).
9). Then, the tilt servomotor 10 is driven, and the carriage 4 or the turntable 1 is moved in order to correct the deviation between the optical axis of the objective lens 3 and the perpendicularity of the reflection surface of the optical disk (S20). As a result, information is read at a predetermined position on the optical disk (S21).

Here, a method of calculating the tilt of the optical disk at each position (address) of the optical disk by calculating the measured tilt of the inner circumference and the outer circumference of the optical disk in steps 18 and 19 will be described.
FIG. 3 is a diagram showing the relationship between the radial position of the optical disc and the address. In FIG. 3, TO is set at the innermost circumference of the optical disc.
When the C-read is performed, the linear velocity of the optical disk is detected by the linear velocity detecting means. Therefore, the inner circumference (tilt sensor B1
3 can be detected, for example, a1 to a
Assuming that the address is 100, the address on the outer periphery (a place where the tilt sensor C14 can detect) is the address of the tilt sensor B described above.
13 (a1 to a100) at the location where it can be detected
At a location that synchronizes with, for example, (a1000-a2000
0). In this way, the detection is repeated for the entire circumference of the optical disc, and the address on the outer circumference of the optical disc (the place where the tilt sensor C14 can detect) with the address of the inner circumference of the optical disc (the place where the tilt sensor B13 can detect) is synchronized. You will understand. That is, the sheet A (inner / outer peripheral address correspondence table) can be created. FIG. 4 is a diagram showing sheet A (inner / outer peripheral address correspondence table).

Since the degree of inclination of the optical disk is generally small on the inner periphery of the optical disk, information can be read stably. Therefore, the inclination of the optical disk at the inner peripheral addresses (a1 to a100) can be determined using the reading of information from the optical disk and the tilt sensor B13 located at the inner periphery. That is, the sheet B (inner address inclination correspondence table) can be created. FIG. 5 is a diagram illustrating a sheet B (an inner peripheral address inclination correspondence table).

Also, the tilt sensor C1 located on the outer periphery of the optical disk is synchronized with the detection of the inclination on the inner periphery using the tilt sensor B13 located on the inner periphery of the optical disk.
By using 4, the inclination at the outer periphery can be determined. That is, sheet C
(Inner / outer circumference inclination correspondence table) can be created. FIG. 6 shows sheet C
It is a figure showing (inner-outer circumference inclination correspondence table).

Therefore, based on the correspondence tables of sheet A (FIG. 4), sheet B (FIG. 5) and sheet C (FIG. 6), as shown in FIG. The inclination of the optical disk at each of the positions is derived. Similarly, the tilt of the optical disc at each position corresponding to the address of each part on the outer circumference of the optical disc is started in synchronization with the position (address) on the inner circumference. Thus, the sheet D (inner / outer peripheral address inclination correspondence table) can be created. FIG.
7 is a diagram showing a sheet D (correspondence table of inner / outer circumference address inclination).

Therefore, as an example of reading information at a certain address on the optical disk, it is assumed that information is read at an address ax in FIG. First, by performing the TOC read, the address of the optical disc at the physical position where the information of the address ax is described can be known (in the example of FIG. 3, the address on the inner circumference is ay,
The address at the outer periphery is similarly read as az).

Next, with reference to the sheet D (FIG. 7) created in advance, the inclination by of the optical disk at that location with respect to the address ay on the inner circumference can be determined. Also, the inclination b of the optical disc at that point with respect to the address az on one outer circumference
z is known. Therefore, the distance between the address ax and the address ay is c, and the distance between the address ax and the address az is d.
(Distances: c and d are known), the inclination bx of the optical disk at the address ax is expressed as bx = (d × by + c × bz) / (c + d).

Therefore, at the same time as the instruction to read information at the address ax, the tilt servomotor 10 is used to correct the deviation of the perpendicularity between the optical axis of the objective lens 3 and the reflection surface of the optical disk. As a correction method, the main shaft 6 for moving the carriage 4 and the guide shaft 7 are simultaneously moved as in the conventional case. Alternatively, the correction operation is performed on the turntable 1 by the inclination amount bx.

As described in detail above, based on the sheet D (FIG. 7) of the tilt information of the optical disk prepared in advance, the tilt of the optical disk is corrected in synchronization with the reading of the information, thereby stabilizing the information. It is possible to read information from the read optical disk.

[0032]

As described above, according to the present invention, the tilt of the optical disc can be adjusted by using the tilt sensor B provided on the inner circumference and the tilt sensor provided on the outer circumference corresponding to the optical discs having various warp forms. C and detect. Then, based on the detection result of the inclination at each position (address) of the inner circumference and the outer circumference,
The direction and degree of inclination of each part of the optical disk can be calculated and predicted in advance. In this way, by moving the objective lens to reproduce the information of a certain address, at the same time, based on the calculation result predicted in advance, by driving the tilt servo motor according to the inclination of the position of the corresponding address, correction is performed, It is possible to correct the deviation between the optical axis of the objective lens and the perpendicularity of the reflection surface of the optical disk, and to stably read information from the optical disk.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical disk device according to an embodiment of the present invention.

FIG. 2 is a flowchart for reading information by correcting a tilt in one embodiment of the present invention;

FIG. 3 is a diagram showing a relationship between a radial position of an optical disc and an address.

FIG. 4 is a diagram showing a sheet A (inner / outer peripheral address correspondence table);

FIG. 5 is a diagram illustrating a sheet B (correspondence table of inner peripheral address inclination).

FIG. 6 is a diagram illustrating a sheet C (correspondence table of inclination between inner and outer circumferences).

FIG. 7 is a diagram showing a sheet D (correspondence table of inner and outer peripheral address inclinations).

FIG. 8 is a perspective view of a conventional optical disk device.

FIG. 9 is a conventional flowchart for reading information by correcting a tilt.

FIG. 10 is a detection optical path diagram of a conventional tilt sensor.

FIG. 11 is a plan view of the lens focal plane of FIG. 10;

FIG. 12 is a side view of FIG. 10;

FIG. 13 is a view showing a form of warpage of the optical disc.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turntable 2 Shaft 3 Objective lens 4 Carriage 5 Feed motor 6 Main shaft 7 Guide shaft 8 Base 9 Tilt sensor A 10 Tilt servomotor 11 Infrared LED 12 2 split photodetector 13 Tilt sensor B 14 Tilt sensor C 15 Signal cable

Claims (6)

[Claims] A first inclination detecting step for detecting a deviation between a vertical axis with respect to a surface of the optical disk at an inner peripheral portion of the optical disk and an optical axis of the objective lens; A second inclination detecting step for detecting a deviation from the optical axis of the lens, an inner peripheral part obtained in the first inclination detecting step, and an outer peripheral part obtained in the second inclination detecting step. A radial position tilt calculating step of calculating tilts of a plurality of positions in the radial direction based on the tilt, and a radial position tilt detecting step of executing the radial position tilt detecting step while rotating the optical disc to calculate a tilt of the entire circumference of the optical disc. Calculation step, wherein when the objective lens is moved in order to reproduce information at a certain position on the optical disc, the information obtained in the all-around position tilt calculation step is obtained. Optical disc reproducing method characterized by the optical disc from the entire circumference of the inclination with reference to the inclination of the corresponding position to correct the inclination of the optical axis of the objective lens. 2. An optical disk rotation driving means for mounting and rotating an optical disk, and an optical reading means for focusing light irradiated on the optical disk on an optical disk surface, condensing reflected light from the optical disk and converting the reflected light into an electric signal. Moving means for moving the optical reading means in the radial direction of the optical disc, disposed in the inner peripheral portion of the moving range of the moving means, a vertical axis to the surface of the optical disc and the optical axis of the optical reading means. First inclination detecting means for detecting a deviation of the optical disk, and second inclination detecting means for detecting a deviation between a vertical axis with respect to a surface of the optical disk and an optical axis of the optical reading means. Tilt detecting means, the rotation driving means, the first tilt detecting means,
An optical disk device comprising: a tilt storage unit that calculates and stores the tilt of each position in the radial direction of the optical disk and the entire circumference thereof based on the second tilt detection unit. 3. The optical disk apparatus according to claim 2, wherein the inclination storage means calculates and stores the inclination of each position when the TOC area is first reproduced after loading the optical disk. 4. An optical disk according to claim 1, further comprising a tilt correcting means for correcting a shift of an optical axis of said optical reading means in accordance with the tilt of said position obtained from said tilt storage means. 3. The optical disk apparatus according to claim 2, wherein said tilt correcting means is operated simultaneously with operating said moving means. 5. An optical disk apparatus according to claim 4, wherein said tilt correcting means corrects a deviation of an optical axis of said optical reading means by moving a guide member used for moving said moving means. . 6. The apparatus according to claim 4, wherein said inclination correcting means corrects a shift of an optical axis of said optical reading means by moving an inclination of a rotation axis of said optical disk rotation driving means moving means. Optical disk device.