JP2000163856A - Optical disk driving method and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely discriminate the kind of a disk by using the difference of depth from an optical disk surface to a signal recording surface even when sensitivities of focus actuators are widely fluctuated. SOLUTION: The level of a driving signal of a focus actuator is measured when an optical beam is focused on the signal recording surface of an optical disk 1 by a focus drive value detecting means 14, the level is stored in a servo drive value storing means 16 as data intrinsic to the kind of the optical disk, and a threshold value for discriminating a disk based thereon. At the time of operation of discriminating a disk, the drive value of a focus actuator at a focal point is measured, and the kind of a disk is discriminated by being compared with the threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive method and an optical disk apparatus capable of recording / reproducing several types of optical disks, and more particularly to a technique for determining the type of an optical disk.

[0002]

2. Description of the Related Art There are optical disk devices capable of reproducing a plurality of types of optical disks, but these devices generally automatically determine the type of optical disk, and correspond to the determined type of optical disk. It has the function of switching constants such as servos. This operation of discriminating an optical disc is generally called "disc discrimination". When the disc diameter is different, when the track interval is different, when the thickness from the disc surface to the signal recording surface is different, when the signal recording surface is different. Various methods have been devised depending on the case where the number of layers is different. If the thickness from the surface of the disk to the signal recording surface is different, the difference in the thickness is detected from the position of the objective lens in the optical axis direction when the signal recording surface is focused, and Is generally known.

[0003] An example of the prior art is disclosed in
The operation and operation of the disk device disclosed in Japanese Patent Publication No. 245421 will be described. FIG. 7 is a diagram for explaining the operation of an example of the prior art. In FIG. 7 (a), 1 is an optical disk for recording and reproducing information, 2 is a motor for rotating the optical disk 1, and 4 is a recording and reproducing device. An objective lens for focusing the light beam on the signal recording surface of the optical disk 1; 25, a turntable for holding the optical disk 1; 26, a reference reflecting surface for determining a reference position of the objective lens 4 in the optical axis direction;
It is fixed to the turntable 25. First, in the present apparatus, the objective lens 4 is driven to a position where the light beam is focused on the reference reflection surface 26, and that position is set as a reference position X0. Thereafter, the objective lens 4 is moved in the outer peripheral direction of the optical disk, and as shown in FIG.
The objective lens 4 is driven to positions Xa and Xb in the optical axis direction so that the light beam is focused on the signal recording surface of the optical disk 1a or the type B optical disk 1b. At this time, as shown in the figure, since the thickness from the surface of the optical disk to the signal recording surface differs between Ta and Tb in 1a and 1b, the displacements Ha and Hb of the objective lens from the reference position X0 depend on the type of the disk. Is a unique value. Since the position of the objective lens 4 in the optical axis direction is calculated from the drive current supplied to the drive means of the objective lens 4, the drive current at the reference position X0 and the signal recording surface of the optical disk on which the focus of the light beam is loaded are recorded. By detecting the drive currents when they are in focus, the displacement of the objective lens from the reference position when the signal recording surface is in focus can be determined, and whether the loaded optical disk is type A or type B Can be determined.

[0004]

However, in the above-described method, when the sensitivity of the objective lens driving means has a large individual variation, the relationship between the position of the objective lens and the driving current becomes non-uniform, and the detection is performed. A large error occurs in the displacement of the objective lens calculated from the drive current. As a result, there is a problem that the probability that the disk discriminating operation fails is increased.

An object of the present invention is to provide an optical disk drive method and an optical disk apparatus capable of discriminating a disk type with high accuracy without being affected by variations in sensitivity of an objective lens driving means. Aim.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a method for storing the level of a drive signal of a focus actuator when a light beam is focused on a signal recording surface of an optical disk, and discriminating the disk. The discrimination threshold used in the operation is set on the basis of the stored level, so that the discrimination of the type of the optical disc is performed in a state where the sensitivity variation is absorbed in the discrimination threshold. As a result, the disc type can be determined with high accuracy without being affected by the variation in sensitivity of the objective lens driving unit.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is an optical disk drive method for recording or reproducing a plurality of types of optical disks having different thicknesses from the surface to the signal recording surface. A focus servo step of controlling a position of a focus actuator that drives an objective lens that focuses on a signal recording surface of the optical disc in the optical axis direction; and a step of storing a level of a drive signal of the focus actuator generated in the focus servo step. A disc discriminating step of discriminating a type of the optical disc, storing a level of a drive signal of a focus actuator when a light beam is focused on a signal recording surface of the optical disc; Of discriminating the type of optical disc by An optical disc driving method according to the present invention. Even if individual variations in sensitivity of the focus actuator are large, the sensitivity variation is determined based on the level of the drive signal of the focus actuator, because the determination threshold used in the disk determination operation is set. The threshold value is absorbed, and as a result, when discriminating the optical disc after the next time, there is an effect that the discrimination can be performed with high accuracy without being affected by the variation in sensitivity.

According to a second aspect of the present invention, a level of a drive signal of a focus actuator when a light beam is focused on a signal recording surface of the optical disk is stored for each type of optical disk. 2. The optical disc driving method according to claim 1, wherein a threshold value for discriminating the type of the optical disc is set in said disc discriminating step by using them. Since the discrimination threshold is created from the data, since the discrimination threshold is created from the data, the discrimination can be performed with high accuracy without being affected by the amount of individual variation of the focus actuator sensitivity.

According to a third aspect of the present invention, the level of the stored drive signal of the focus actuator is a signal when the light beam is focused on a signal recording surface near the innermost circumference of the optical disk. 3. The optical disk driving method according to claim 1, wherein the disk discriminating step is also performed near the innermost circumference of the optical disk. The effect of improving the accuracy of the disc discrimination operation is obtained by suppressing the effects of surface runout and warpage.

According to a fourth aspect of the present invention, the level of the stored drive signal of the focus actuator is learned and corrected every time an optical disk to be recorded and reproduced is inserted into and removed from the optical disk device. 4. The optical disc driving method according to claim 1, wherein the sensitivity of the focus actuator changes due to aging, or the installation attitude of the apparatus changes, and the drive signal of the focus actuator and the light of the objective lens are changed. Even when the positional relationship in the axial direction changes, the discrimination threshold is reset to an appropriate value, so that a disc discriminating operation with high accuracy is always realized.

The invention according to claim 5 of the present invention is characterized in that the type of the optical disc and the level of the drive signal of the focus actuator are stored in a nonvolatile storage device. The method for driving an optical disk according to any one of claims 1 to 3, wherein the stored information is retained even when the power supply to the apparatus is completely stopped, and the disk does not change even after the apparatus is turned on again. It has the effect of providing discrimination performance.

According to a sixth aspect of the present invention, there is provided an optical disk apparatus for recording or reproducing a plurality of types of optical disks having different thicknesses from a surface to a signal recording surface,
An optical head for recording information on or reproducing information recorded on an optical disk, an objective lens mounted on the optical head for focusing a light beam on a signal recording surface of the optical disk, and moving the objective lens in an optical axis direction. A focus actuator that drives the focus actuator; a focus servo unit that controls the position of the focus actuator so that the light beam focuses on a signal recording surface of the optical disc; and a level of a focus drive signal generated by the focus servo unit. Means, and disc discriminating means for discriminating the type of the optical disc, storing a level of a drive signal of a focus actuator when a light beam is focused on a signal recording surface of the optical disc, and based on this, It is characterized in that the type of the optical disk is determined by the disk determining means. The discrimination threshold used in the disc discrimination operation is set based on the level of the drive signal of the focus actuator even if the individual variation of the sensitivity of the focus actuator is large. As a result, when discriminating an optical disc after the next time, the discrimination can be performed with high accuracy without being affected by sensitivity variations.

According to a seventh aspect of the present invention, a level of a drive signal of a focus actuator when a light beam is focused on a signal recording surface of the optical disk is defined as:
7. The optical disc apparatus according to claim 6, wherein the discs are stored in correspondence with all types of optical discs, and using them, a threshold value for discriminating the type of the optical disc is set in the disc discriminating means. Yes, since the discrimination threshold is created from the measurement data unique to each device, after the discrimination threshold is created from the data, accurate discrimination that is completely unaffected by the amount of individual variation in focus actuator sensitivity is performed. It has the effect that it can be performed.

According to an eighth aspect of the present invention, the level of the drive signal of the focus actuator stored when the light beam is focused on the signal recording surface near the innermost circumference of the optical disk is adjusted. 8. The optical disk device according to claim 6, wherein the signal level is a signal level, and the disk discriminating operation is similarly performed near the innermost circumference of the optical disk. The effect of improving the accuracy of the disc discrimination operation is provided by suppressing the effects of surface runout and warpage.

According to a ninth aspect of the present invention, the level of the stored drive signal of the focus actuator is learned and corrected every time an optical disk to be recorded and reproduced is inserted into and removed from the optical disk device. 9. The optical disk device according to claim 6, wherein a drive signal of the focus actuator and an optical axis of the objective lens change when the sensitivity of the focus actuator changes due to deterioration over time or when the installation posture of the device changes. The discrimination threshold is reset to an appropriate value even in the case where the positional relationship in the direction changes, so that the disc discriminating operation with high accuracy is always realized.

According to a tenth aspect of the present invention, there is provided a nonvolatile storage device, wherein a type of the optical disk and a level of a drive signal of the focus actuator are stored in the nonvolatile storage device. Claims 6 to 9
The optical disk device according to any one of the above, even if the power supply to the device is completely stopped, the stored information is maintained, and even after the power is turned on again, the change is the same as before. There is an effect that the disc discrimination performance can be maintained.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a block diagram according to Embodiment 1 of the present invention. 1 is an optical disk for recording and reproducing information, 2 is a motor for rotating the optical disk 1, and 3 is an optical head for recording information on the optical disk 1 or reproducing information recorded on the optical disk 1. The optical head 3 is equipped with an objective lens 4 for focusing the light beam on the signal recording surface of the optical disk 1 and a focus actuator 5 for driving the objective lens 4 in the optical axis direction of the light beam. L for servo
The SI8 has a function of focusing point drive value detection means 10,
Focus servo means 11, focus drive value detection means 14
Having. The focus servo unit 11 receives a focus error signal 17 from the focus error signal generator 7 in order to focus the light beam on the signal recording surface of the optical disc 1 during information recording and reproduction, and based on the focus error signal 17, a focus actuator driving signal 18. And drives the focus actuator 5 to position the objective lens 4. In the disc discriminating operation, a focus actuator drive signal 18 is output in accordance with a preset drive sequence of the objective lens 4 in the optical axis direction to drive the focus actuator. The focus drive value detection means 14 takes in a signal passed through a low-pass filter into the focus actuator drive signal 18 and converts it into focus drive data 19 of a digital value. The focus in-focus drive value detecting means 10 functions at the time of disc discriminating operation, and simultaneously observes the focus error signal 17 and the focus drive data 19 to detect the focus drive data when the signal recording surface is focused. This is output as the in-focus drive data 20.

The CPU 9 has servo command issuing means 13, servo drive value storage means 16, and disk discriminating means 12 as its functions. The servo command issuing unit 13 has a function of switching the operation of the focus servo unit 11 to the above-described information recording, positioning control of the objective lens 4 at the time of reproduction, or disc discriminating operation. The servo drive value storage means 16 takes in focus drive data 19 when the light beam is focused on the signal recording surface, and stores it as servo drive data 21 together with the type of optical disk loaded in the apparatus.
For example, a nonvolatile storage device such as a flash memory is used as the servo drive value storage means 16 so that the stored contents can be retained even when the power supply to the device is stopped.
The disc discriminating unit 12 creates a discrimination threshold for disc discrimination using the servo drive data 21 and compares the in-focus drive data 20 output from the in-focus drive value detection unit 10 with the discrimination threshold. Then, the type of the optical disc 1 is determined.

The above operation will be described in further detail by taking as an example a case where two types of optical disks of types A and B having different thicknesses from the disk surface to the signal recording surface are determined.
FIG. 2 shows a type A optical disk 1a and a type B optical disk
1b shows the position of the objective lens and the focus drive data when the light beam is focused on the signal recording surface. In the figures (a) and (b), the optical disk 1a
1 and 1b show that the position of the objective lens 4 in the optical axis direction is different because the thickness from the disk surface to the signal recording surface is different. For this reason, if the focus drive data at this time is Fa and Fb, respectively, there is a difference between Fa and Fb as shown in FIG. Therefore, by storing the focus drive data Fa and Fb as the servo drive data Sa and Sb, the discrimination threshold Th used by the disc discrimination means can be set as shown in FIG. it can. After the determination threshold Th is set, the type of the optical disk is determined as described below.

FIGS. 3A and 3B show temporal changes in focus drive data and a focus error signal during a disc discriminating operation. FIG. 3A shows a case of a type A optical disc, and FIG.
Shows the case of type B, the horizontal axis shows time, the upper figure shows focus drive data, and the lower figure shows focus error signals. In the disc discriminating operation, the focus actuator is driven so that the objective lens always passes through the position where the light beam is focused on the signal recording surface of the optical disc. In FIGS. 3A and 3B, the focus drive data is increased with time in both (a) and (b), and the objective lens is driven in a direction approaching the optical disk. By doing this,
As shown in the figure below, an S-shaped waveform indicating that the light beam is focused on the signal recording surface appears in the focus error signal. The focus drive data at this time is
The type of the optical disc is determined as type A or B by detecting it as Da or Db and comparing it with the set discrimination threshold Th.
Can be determined.

As described above, according to the first embodiment, even if the sensitivity of the focus actuator varies from individual to individual, the determination threshold value corresponding to the sensitivity of each focus actuator is set. For,
The effect of the variation is absorbed into the discrimination threshold. As a result, after the discrimination threshold is set by the above-described method, an accurate disc discrimination operation that is not affected by the variation in sensitivity of the focus actuator can be realized.

Further, by storing the above-mentioned servo drive data on which the determination threshold value is set in a nonvolatile storage device, even if the power supply to the device is completely stopped,
It is possible to keep the stored information and maintain the same disc discrimination performance as before even after the power is turned on again.

(Embodiment 2) Embodiment 2 of the present invention
Is the measurement of the servo drive data described in the first embodiment,
The only difference from the first embodiment is that the disc discriminating operation is performed near the innermost circumference of the optical disc, and there is no difference in other respects. FIG. 4 is a block diagram according to the second embodiment of the present invention, and most parts in the figure overlap with those in FIG.

In the optical disk device according to the second embodiment, as shown in FIG. 4, an optical head feed motor 22 for driving the optical head 3 in the radial direction of the optical disk 1 and an optical head drive device 23 for supplying a drive voltage thereto. And an optical head feed control unit 24 for controlling the operation and stop of the optical head feed motor 22 as a function of the servo LSI 8, and the measurement of servo drive data for each disk type described in the first embodiment. , And the disc discriminating operation are performed in a state where the optical head 3 is moved to the vicinity of the innermost circumference of the optical disc 1. Since the optical disc has individual differences in the amount of surface runout and warpage, as a result, even at the same radius of the same type of disc, the position of the objective lens 3 in the optical axis direction when the light beam is in focus Always make a difference. However, since the optical disk is fixed to the optical disk device at the center, the difference in the position of the objective lens 3 due to the individual difference becomes smallest at the innermost circumference, and the servo drive data and the focus drive data are different between the same type of disks. Variation is reduced. Therefore, the type of the optical disk can be accurately determined.

As described above, according to the second embodiment, the accuracy of the disc discriminating operation can be improved by suppressing the influence of the surface deflection or warpage of the optical disc on the level of the drive signal of the focus actuator.

(Embodiment 3) Embodiment 3 of the present invention
Is different from the second embodiment in the method of calculating the discrimination threshold value Th for disc discrimination, but there is no difference in other respects. FIG.
FIG. 8 is a flowchart for explaining a calculation process of a discrimination threshold Th. This process is executed every time an optical disk is exchanged from an optical disk device. First, as in the first and second embodiments, the focus drive data F when the light beam is focused on the signal recording surface of the optical disk is measured. Next, the process is branched according to the type of the optical disk currently loaded in the apparatus, and the servo drive data already stored for each type of the disk is used by using the measured focus drive data F.
Correct Sa and Sb. Using the result, a discrimination threshold value Th is calculated as shown in the flowchart, and used in the disc discrimination operation similar to the first and second embodiments. The correction processing of the servo drive data Sa and Sb using the focus drive data F is configured by, for example, a low-pass filter as shown in FIG. Change of Sa,
Sb is reflected so as to always set an appropriate discrimination threshold Th. As the initial value of Sa in FIG. 6, for example, a value obtained from a theoretical design value of the apparatus is set, or a method of adopting focus drive data measured on the first loaded disc for each disc type is used. be able to.

As described above, according to the third embodiment, the discrimination threshold value Th for disc discrimination always learns the optimal value for discriminating between the type A and B optical discs. The accuracy of the determination is always kept high.

[0028]

As described above, according to the present invention,
The level of the drive signal of the focus actuator when the light beam is focused on the signal recording surface is stored, and the threshold value for discriminating the disc type is set based on this. Even if the optical disc varies, the sensitivity variation is absorbed by the discrimination threshold, and as a result, when discriminating an optical disk from the next time on, the discrimination can be performed accurately without being affected by the sensitivity variation. Is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a principle diagram showing a state at the time of focusing in Embodiment 1 of the present invention;

FIG. 3 is a signal waveform diagram at the time of disc discrimination according to the first embodiment of the present invention.

FIG. 4 is a block diagram of an apparatus according to a second embodiment of the present invention.

FIG. 5 is a flowchart of a process according to the third embodiment of the present invention.

FIG. 6 is a principle diagram for explaining an example of a method of correcting servo drive data according to a third embodiment of the present invention;

FIG. 7 is a principle diagram showing an operation in an example of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Motor 3 Optical head 4 Objective lens 5 Focus actuator 6 Focus actuator drive device 7 Focus error signal generation device 8 LSI for servo 9 CPU 10 Focusing drive blood detecting means 11 Focus servo means 12 Disk discriminating means 13 Servo command issuing means 14 Focus drive value detection means 15 Low pass filter 16 Servo drive value storage means 17 Focus error signal 18 Focus actuator drive signal 19 Focus drive data 20 Focus drive data 21 Servo drive data 22 Optical head feed motor 23 Optical head drive 24 Optical head Feed control means 25 Turntable 26 Reference reflection surface

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D066 HA01 5D090 AA01 CC09 CC18 FF50 JJ11 5D118 AA14 AA15 BA01 BB02 BF16 CB01 CD02 CD14 CD15

Claims (10)

[Claims] 1. An optical disc driving method for recording or reproducing a plurality of types of optical discs having different thicknesses from a surface to a signal recording surface, wherein an objective lens for focusing a light beam on a signal recording surface of the optical disc. A focus servo step of controlling the position of a focus actuator that is driven in the axial direction, a step of storing a level of a drive signal of the focus actuator generated in the focus servo step, and a disk determination step of determining the type of the optical disk, The level of the drive signal of the focus actuator when the light beam is focused on the signal recording surface of the optical disk is stored,
An optical disk driving method, wherein the type of the optical disk is determined in the disk determining step based on the determination. 2. The level of a drive signal of a focus actuator when a light beam is focused on a signal recording surface of the optical disk is stored in correspondence with each of all types of optical disks, and the level of the drive signal is stored using the drive signals. The optical disc driving method according to claim 1, wherein a threshold value for discriminating the type of the optical disc is set in the discriminating step. 3. The stored drive signal level of the focus actuator is a signal level when a light beam is focused on a signal recording surface near an innermost circumference of the optical disk. 4. The optical disk drive method according to claim 2, wherein the step is also performed near the innermost circumference of the optical disk. 4. The method according to claim 1, wherein the stored level of the drive signal of the focus actuator is learned and corrected every time an optical disk to be recorded / reproduced is inserted / removed from the optical disk device. An optical disc driving method according to any one of the above. 5. The optical disk drive method according to claim 1, wherein a type of the optical disk and a level of a drive signal of the focus actuator are stored in a nonvolatile storage device. 6. An optical disk device for recording or reproducing a plurality of types of optical disks having different thicknesses from a surface to a signal recording surface, comprising: an optical head for recording information on the optical disk or reproducing the information recorded on the optical disk; An objective lens mounted on the optical head to focus a light beam on a signal recording surface of the optical disk; a focus actuator for driving the objective lens in an optical axis direction; and Focus servo means for controlling the position to match the signal recording surface of the optical disc, means for storing the level of a focus drive signal generated by the focus servo means, and disc discriminating means for discriminating the type of the optical disc, Focusing when the light beam is focused on the signal recording surface of the optical disc An optical disk device, wherein the level of a drive signal of a cue actuator is stored, and the type of the optical disk is determined by the disk determining means based on the stored level. 7. The level of a drive signal of a focus actuator when a light beam is focused on a signal recording surface of the optical disk is stored for each of all types of optical disks, and the level of the drive signal is stored using the drive signal. 7. The optical disk device according to claim 6, wherein a threshold value for determining the type of the optical disk is set by the determination unit. 8. The stored level of the drive signal of the focus actuator is a signal level when a light beam is focused on a signal recording surface near an innermost circumference of the optical disk, and a disk discriminating operation is performed. 8. The optical disk device according to claim 6, wherein the same is performed near the innermost circumference of the optical disk. 9. A learning correction of the stored level of the drive signal of the focus actuator every time an optical disk to be recorded / reproduced is inserted / removed from the optical disk device. An optical disc device according to any one of the above. 10. The nonvolatile memory device according to claim 6, further comprising a nonvolatile memory device, wherein the type of the optical disk and the level of the drive signal of the focus actuator are stored in the nonvolatile memory device. An optical disk device according to claim 1.