JP2611849B2 - Optical disk drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an optical disk device for recording and reproducing information on an optical disk and a magneto-optical disk (hereinafter simply referred to as an optical disk). Then, the present invention relates to an optical disk device provided with means for stably operating the servo circuit.

[Conventional technology]

Since information recording and information reproduction on the optical disk are performed without bringing the optical head into contact with the recording medium, tracking control is necessary, and focus control is required for accurate information recording and reproduction. The servo circuit is also used for the control. It is desirable that this servo circuit performs a stable operation irrespective of not only the drift of the signal processing system but also the stability of the drive system of the recording medium, and further, the individual difference of the recording medium. In order to operate the servo circuit stably in this manner, conventionally, for example, in tracking control, an offset is provided to eliminate individual differences. This is a signal that is applied to electrically adjust the deviation of the optical system that cannot be adjusted mechanically to perform correct tracking, and such correction is indispensable for performing stable control. Yes, for example, determined by the manufacturer's final adjustment process.

[Problems to be solved by the invention]

The optical disk device in which the offset amount is set in this way receives a mechanical shock before it reaches the customer, and also changes due to aging, and furthermore, due to the warpage of the disk due to changes in environmental conditions during use, etc. The set offset amount may not be optimal. Therefore, it is desired to readjust before use by the customer or to adjust the offset regularly or irregularly, but it is often difficult in practice. If the offset amount is not appropriate, a track miss may occur, causing errors in the recorded data and the reproduced data.

Furthermore, even if a uniform offset is applied to the disk, the offset amount is not always the optimum value depending on the position of the disk surface, and in the worst case, the servo is offset even though the offset is applied. Is also conceivable.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem, and an optical disk device capable of always performing stable servo control by providing means for automatically determining an offset amount at each position on a disk surface. The purpose is to provide.

[Means for solving the problem]

The optical disk device according to the present invention according to claim 1, further comprising: a servo circuit that irradiates the optical disk with a beam and controls an irradiation position of the beam based on reflected light of the irradiated beam. Means for dividing the disk into one or a plurality of areas; means for detecting the maximum and minimum values of the signal obtained by traversing a predetermined track in each of the divided areas; It is characterized by comprising means for detecting the amplitude of the signal, and means for changing the sensor gain so as to make the detected amplitude constant, and the servo circuits in each area are controlled by the changed sensor gain.

The optical disk apparatus according to the present invention is for performing tracking control for causing a projection light beam to follow a recording track on the optical disk, and means for dividing the optical disk into one or a plurality of areas. Means for detecting the amplitude of the signal obtained from the reflected light of the beam applied to each area,
Means for offsetting the tracking control, means for calculating a function indicating the relationship between the tracking control and the amplitude from the amplitudes of the signals obtained at at least three different tracking control positions, and a maximum value of the function. There is provided means for calculating an offset value of the tracking control of each area so as to be a relevant tracking control position, and the tracking control of each area is calibrated based on the calculated offset value.

According to a third aspect of the present invention, there is provided an optical disk apparatus for performing focus control for causing a projection light beam to follow a recording track on the optical disk, wherein the optical disk is divided into one or a plurality of areas. Means for detecting the amplitude of the signal obtained from the reflected light of the beam applied to each area,
Means for offsetting the focus control, means for calculating a function indicating the relationship between focus control and amplitude from the amplitudes of the signals obtained at at least three different focus control positions, and a maximum value of the function. There is provided means for calculating an offset value of focus control of each area so as to be a related focus control position, and the focus control of each area is calibrated based on the calculated offset value.

[Action]

In the optical disk device according to the present invention, the calibration value of the servo circuit is stored for each disk area, and the beam irradiation state for each area is controlled based on the stored calibration value.

(Example of the invention)

Hereinafter, examples of the present invention will be described in detail. The present invention provides an offset for servo control at a plurality of positions on an optical disk medium, and divides an optical disk into a plurality of areas in order to change a servo gain, and for each divided area, a calibration value such as an offset value and a servo gain. Is related to mapping for storing Then, the offset value or the servo gain can be detected and adjusted so that this mapping can be appropriately performed for each area when starting up or accessing the optical disk. First, detection of offset in a predetermined area of the optical disk medium will be described.

FIG. 1 is a schematic block diagram of an optical disk device having a servo circuit according to the present invention. FIG. 2 is a flowchart showing the operation of the present invention. Below the optical disk (10), optical heads (101) and (102) each including a fixed light emitting element (1b) and a light receiving element (1e) are arranged.
The light beam emitted by b) is projected on the optical disk (10) via the objective lens (1a) constituting the optical head (102), and the reflected light from this is again passed through the objective lens (1a) to the light receiving element. I am trying to arrive. The optical head (102) is mounted on the carriage (103), and seek operation is performed by driving a linear motor (1c) provided on the carriage (103), that is, the optical disk (10) is roughly moved in a radial direction. The objective lens (1
The electromagnetic actuator (1d) attached to a) causes the optical disk (10) at the light beam projection point to move densely in the radial direction to perform tracking control.

In order to detect the offset of a predetermined area on the optical disk medium, the electromagnetic head drive control circuit (14) is connected to the electromagnetic actuator drive circuit (14) via the adder (12) from the state where the optical head is controlled to track on the predetermined track. A signal is issued to move the track alternately from the inner circumference to the outer circumference and from the outer circumference to the inner circumference. By performing such an operation, the output of the differential amplifier 1g becomes sinusoidal as shown in FIG. The output of the differential amplifier 1g is input to the A / D converter 2, where it is converted into a predetermined bit digital signal.
This digital signal is input to the maximum value register 3, the minimum value register 4, the comparator 6, and the servo off detection circuit 7. The contents of the maximum value register 3 and the minimum value register 4 are alternately supplied to a comparator 6 by a multiplexer 5. The comparator 6 compares the content input from the A / D converter 2 with the input from the multiplexer 5, and according to the comparison result, the maximum value register 3 and the minimum value register 4
Update the contents of

That is, when the content of the maximum value register 3 (or the minimum value register 4) is given to the comparator 6 by a signal from a control circuit (not shown), the multiplexer 5 outputs A /
When the input from the D converter 2 is larger (or smaller) than the input from the multiplexer 5, the output of the A / D converter 2 is taken into the maximum value register 3 (or the minimum value register 4) and the contents thereof are read. To update. Conversely, if the value is small (or large), the contents of the maximum value register 3 (or the minimum value register 4) are not updated. When such processing is repeated, the maximum value register 3
Stores the maximum value of the output of the A / D converter 2 (that is, the maximum value of the sine-wave signal) and the minimum value register 4 stores the same minimum value (that is, the minimum value of the sine-wave signal). become. The microprocessor 8 captures the maximum and minimum values for each one-way movement. In addition, the microprocessor 8
Sends a signal to the electromagnetic actuator 14 for moving the optical head, the maximum value register 3 and the minimum value register 4
By resetting, the maximum value and the minimum value for each one-way movement of the optical head 1 can be obtained. The microprocessor 8 sets the difference between the median value of the maximum value and the minimum value thus obtained and the 0 level as the offset value.

Next, the mapping will be described. In order to perform mapping, such an offset value is divided into a plurality of areas (16 areas in FIG. 4) of the optical disk medium as shown in FIG. 4, for example. Calculate the value and the minimum value. That is, in the area 1, the light beam on the predetermined track is moved one track from the inner circumference side to the outer circumference direction by operating the lens in the optical head, and then one track is moved from the outer circumference side to the inner circumference direction. Move alternately to jump. Thus, as described above, the maximum value and the minimum value for each one-way movement are obtained, and then the average value of the maximum value and the minimum value is calculated, and the average value is set as the maximum value and the minimum value representative of the area 1. The difference between the median of the maximum value and the minimum value and the 0 level is stored in the memory 15 as the offset value of the area 1. In accordance with the rotation of the disk, the offset values of the area 5 → the area 9 → the area 13 are calculated and stored in the same manner as described above. Next, the light spot is moved to a predetermined track in the area 2, and similarly, the offset values of the area 2, the area 6, the area 10, and the area 14 are calculated and stored in the same manner. Hereinafter, this operation is repeated. When the offset values up to the area 16 have been calculated and stored, the assignment of the offset values of each area (hereinafter referred to as optical disk mapping) has been completed. In the above method, any track may be selected as the predetermined track in each area, but selecting the central track (FIG. 5A) in the area is considered to provide a relatively unbiased offset value. . In the above-mentioned method, predetermined tracks in each area are selected in advance. However, as shown in FIG. 6, n consecutive jumps are specified to the optical head, and the maximum value and the minimum value are obtained for each jump. The offset value of each area may be calculated from the average value.

Array of mapping areas on optical disk media (map)
Can be expressed by a matrix of map = (track group NO, sector group NO), where allocation in the track direction (radial direction) is a track group NO and allocation in the sector direction (circumferential direction) is a sector group NO. Here, it is assumed that track group NO ≦ the number of tracks or the maximum scale of the external scale, 1 ≦ sector group NO ≦ the number of sectors in the circumferential direction or the number of rotation pulses of the disk motor. Possible number of track groups and number of sector groups are as follows: number of track groups = 4, 8, 16, 32 sector groups = 4, 8, 16, sector number. If the number of groups is set to an even number, the operation speed of the microcomputer can be increased. If the number is 4 or less, it is insufficient to sufficiently perform the correction which is the object of the present invention. This is because time overhead occurs.

Area allocation in the sector direction is performed by using the method in which the microcomputer detects the circumferential address position, using the boundary point of the sector as the area boundary, and using the method in which the microcomputer detects the rotation pulse of the disk motor. Use values. When using sector boundary points, the current number of sectors on a 130 mm optical disk is 17 sectors (512 bytes per sector) or 31 sectors.
It is a sector (1Kbyte per sector), and 13 for 90mm
For example, if the number of sector loops is 4 for a 13-sector optical disk because it is a sector or 25 sectors, the optical disk is divided into four equal parts as shown in FIG. It is necessary to assign points as boundaries of each area.

In the above-described example (hereinafter referred to as a jumping method), a tracking sensor waveform generated by one or n track jumps is used to obtain an offset value. The waveform generated by such a track jump can obtain a clearer waveform than the waveform detected at the time of seek described later, and the measurement point is very clear because the track address is detected at the time of the jump. For this reason, there is an advantage that it is easy to handle an error generated in map creation. The method of jumping the beam to map the offset value is suitable for starting the optical disk at a stage before recording and reproduction, but can also be performed at the time of data access during recording and reproduction. This case will be described in more detail. In FIG. 8, when the optical spot is moved from the current track a to the target track b by driving the linear motor, the waveform of the tracking sensor is detected as shown in waveform B. In the portion C in this waveform, the tracking sensor signal is not detected because the driving speed of the linear motor is high, but is detected at the start of driving (D) or at the end of driving (E). The maximum value and the minimum value of the sinusoidal waveform are detected by using one or both of the waveforms, and the offset value is calculated. In such a method, the tracking sensor waveform is not clear. In addition, the number of tracks is counted at the time of seeking, but the track point is not detected, so that the measurement point is not clear as compared with the jumping method. However, there is an advantage that mapping can be performed in conjunction with data access. Further, if it is a device that performs a seek operation by jumping, it takes some time, but it is also possible to map the area for each access in conjunction with data access.

In addition, the optical disk device manufactured by the present applicant uses a state observer (observer) based on modern control theory as a speed detection method, and any track can be directly accessed only by coarse movement driven by a linear motor. (Macro seek). By using this system, by driving the linear motor at a low speed and at a constant speed, mapping can be performed faster than the jump seek and more accurately than the access method. The structure of such an observer is disclosed in JP-A-63-271728.
This is described in detail in the official gazette. FIG. 9 is a block diagram of the overall configuration of an optical disk drive using an observer,
FIG. 10 is a block diagram of a speed control system in the optical disk drive of FIG. In order to control the linear motor at low speed and constant speed, a constant speed pattern is set in the target speed generation circuit, and whether or not the speed is controlled along this pattern is detected by the state observer (16). If not, the difference between the pattern and the detected value is fed back to the linear motor drive circuit (13). By controlling the linear motor in this way, it is possible to obtain a clearer waveform than the tracking sensor signal obtained by the access method more quickly than at the time of jumping seek, and mapping with a more accurate area representative value can be achieved. It becomes possible.

As described above, the jumping method is used as a method for performing mapping.
Although the access method, jumping seek method, and macro seek method (observer method) have been described, the mapping may be performed by combining these methods. For example, there is a method of mapping the entire area of the disk allocated by the jumping method when inserting the disk, and then adding a learning function of updating the value of the accessed area by the access method every time there is access. As a specific formula for updating the value of this area, update data = a ₁ × (area representative value calculated at the time of access) + a ₂ × (area representative value calculated at the time of disk insertion) where a ₁ + a ₂ = 1, For example Etc. may be set.

When the mapping is performed, in addition to the above-described disk insertion and disk access, environmental sensors such as a temperature sensor and a humidity sensor are installed in the disk device, and the amount of change of these sensors is constant. It may be performed when it exceeds, or may be performed every predetermined time.

In the above embodiment, the offset value is calculated by using the maximum value and the minimum value of the tracking sensor signal waveform, and the mapping method is described. However, as shown in FIG. 11, detection is performed in the same manner as the normal tracking sensor signal. The difference between the tracking sensor signal at the timing of the maximum value of the tracking crossing signal (TCS signal) and the 0 level of the tracking sensor signal may be used as the offset value.

Further, an offset value may be given so that a reproduced signal in a preformat portion such as a header portion of a sector is maximized. 12, 13, and 14, a method of calculating the offset value by this method will be described. FIG. 12 shows a track (1) in a predetermined area for mapping the optical disc (10).
7) Shows the upper headers (18), (19) and (20). As shown in the flowchart of FIG. 13, a predetermined offset is given to the offset addition gain switching circuit (9) when the header is detected by the microprocessor (8) by the header detecting means (not shown). That is, Hetsuda (18)
Is detected, a predetermined offset amount (offset 0) is given, and the amplitude of the data signal at that time is calculated (FIG. 14). Next, when the header (19) is detected, the offset amount of offset 0 + 20H is given, and the amplitude of the data signal at that time is calculated (FIG. 14). Next, similarly, when the header (20) is detected, the offset amount of offset 0-20H is given, and the amplitude of the data signal at that time is calculated (FIG. 14). Using the information at the three points thus obtained, a function representing the relationship between the offset amount and the amplitude of the signal for tracking control is calculated. This function is a convex 2
Since it can be approximated as a next function, it can be specified by the information at the above three points.

In this way, the function and the offset and the offset amount that takes the maximum value are obtained. The microprocessor 8 calculates the offset amount by using the condition such as “differential value = 0” and calculates the optimum offset. The amount is stored in the memory (15) as an offset value of the area. This embodiment has been described using three headers. However, if there is preformat data longer than the header, the offset is determined by changing the offset amount as described above using the data. Is also good. In addition, the accuracy of add-on data (recorded information data) can be reduced.

Further, when the drive current of the actuator can be controlled by the push-pull sensor method, the offset value can be set to 0 in the following case. The microprocessor 8 gives a track jump command to the adder 12, and obtains the sensor output obtained at that time, that is, the maximum value and the minimum value of the amplitude of the differential amplifier 1g output, that is, the upper and lower amplitudes. This is obtained at least twice by making the drive current different, that is, adding a different DC component to the drive circuit 14 of the actuator 1d of the objective lens 1a. FIG. 15 shows the DC drive current of the actuator on the horizontal axis and the sensor output on the vertical axis, and shows the measurement results as black dots.
(DC component 0) and the drive current 20H are measured at two points. A straight line (solid line) connecting the maximum value and the minimum value thus obtained is obtained, and a straight line (broken line) corresponding to the center value is obtained. The intersection (point X) between this broken line and the sensor output 0 (horizontal coordinate axis) is calculated as the optimum drive current value. That is, when a direct current corresponding to the point X is given to the drive circuit 14, the point X is on the straight line of the center value, so that the upper and lower amplitudes are equal, that is, the offset = 0.
The fact that the upper and lower amplitudes are equal means that the beam accurately traces the center of the track. In this case, the drive current is mapped instead of the offset value. As described above, the offset value when tracking each area of the optical disk is stored in the memory (15).
If it is mapped to the microprocessor (8)
Adjusts the tracking signal at the time of tracking by using a mapped offset value, and inputs the adjusted tracking signal to the phase compensation circuit (11) to perform phase compensation and coupling compensation, thereby driving the electromagnetic actuator (1d). To the adder (12), and to the linear motor drive circuit (1
Give to 3). Thus, the tracking servo control is performed by the calibrated accurate tracking signal.

In FIG. 1, the A / D is provided after the differential amplifier (1g).
The converter (2), the maximum and minimum registers are provided in the subsequent stage, but the peak detection circuit is provided in the subsequent stage of the differential amplifier, and the maximum and minimum are calculated, and then digitized by the A / D converter (2) You may make it.

Although the offset value has been described as the mapping amount, other sensor gains, threshold values, focus offsets, and the like can be considered. Hereinafter, each amount will be described.

Sensor Gain As described above, the maximum value and the minimum value of the tracking sensor signal obtained by crossing the track are determined for each area of the optical disk (for example, for each of FIGS. 4 (1 to 16)).
The microprocessor (8) calculates the amplitude from the maximum value and the minimum value, and stores a sensor gain in the memory 15 so as to keep the amplitude constant. At the time of tracking, the gain is changed according to the sensor gain. For example, FIG. 16 shows the amplitude of the reproduced signal in the large dynamic range on the left, and shows the small dynamic range output after changing the gain on the right. In the figure, -6dB to + 6dB for standard amplitude 1
-6 to 0dB is + 3dB gain, 0dB to +6
When the gain is set to -3 dB for the dB input, the sensor amplitude after the gain switching falls within the range of -3 dB to +3 dB with respect to the standard amplitude 1. For -6 to 0 dB mentioned above, +3 dB gain, 0 dB to +6
In dB, the information to make the gain -3 dB is mapped to each area.

The actual gain switching can be easily performed by providing a plurality of attenuators and switching the attenuators.

When to perform a more precise adjustment is also possible to make adjustments in two ⁸ steps using the 8-bit multiplication type D / A converter, for example.

Threshold As described above, the maximum value and the minimum value of the tracking sensor signal obtained by crossing the track are obtained for each area (for example, FIGS. 4 to 16) of the optical disk, and then the microprocessor ( 8) Calculate the amplitude from the maximum value and the minimum value, determine the threshold Th as K times the amplitude, and store it in the memory 15. At the time of tracking, this is supplied to a servo off detection circuit (7). A / D servo off detection circuit (7)
The output of the converter 2 is compared with a threshold value Th. If the output of the A / D converter 2 exceeds this threshold value, an error processing command signal S is output as occurrence of servo departure. This signal is used, for example, to interrupt the recording operation. A / D if the threshold is not exceeded
The output of the converter 2 is directly input to the offset addition / gain switching circuit 9.

17 (a), (b) and (c) show optical head 1 or A / D
The output of the converter 2 and the threshold value Th used in the circuit of the present invention
And a fixed threshold value Th '.

FIG. 17 (b) shows a threshold set assuming standard conditions.
Th ′ and the threshold value set by the servo circuit according to the present invention
This shows a case in which Th is the same, which indicates a situation in which the output of the A / D converter 2 has exceeded the threshold value and the servo has failed. Thus
When the level of A / D converter 2 output decreases (increases), the first
7 As shown in FIG.
h changes accordingly, but the fixed threshold Th 'does not change.

In FIG. 17 (a), when the fixed threshold value is used, it is detected that the servo is out of position only when the tracking error is larger than the assumed tracking error. If the level drops further, detection becomes impossible. In FIG. 17 (b), with a fixed threshold value, the servo is detected to be out of servo before the expected tracking deviation amount is reached. If the level further rises, it is detected that the servo is off even in the normal tracking error.

However, such a disadvantage does not occur because the threshold value Th according to the present invention changes accordingly.

Focus Offset FIG. 18 shows a configuration diagram necessary for converting the focus offset into a map. To calculate the focus offset, a track jump is made in each area (for example, FIGS. 4 to 16) of the optical disk as shown in a flowchart in FIG. 19, and at the time of the jump, the microprocessor 8 is turned on by the focus. An offset amount of ± 20H and 0 is given to the offset addition / gain switching circuit 29 for control, and the signal amplitude for tracking control at three positions of two positions and offset 0 obtained by this is calculated. I do. A function representing the relationship between the offset amount and the amplitude is calculated using the three points thus obtained. Since this function can be approximated as a quadratic function convex upward as shown in FIG. 20 before and after the in-focus state, it can be specified by the above three points. In this way, the constant of the function and the offset amount that takes the maximum value are obtained. The microprocessor 8 calculates the offset amount using the condition of the differential value = 0, and stores it in the memory 15 as the optimal offset amount. Remember. At the time of focus control on the optical disk, the output of the A / D converter 22 is added with the offset amount as described above in an offset addition / gain switching circuit 29, and the phase compensation circuit 31 is passed through an amplifier whose gain is switched as required. Is input to In this phase compensation circuit 31, phase compensation and coupling compensation are performed, and the electromagnetic actuator 1h
Is output to the electromagnetic actuator drive circuit 34. The drive circuit 34 is thereby provided with the electromagnetic actuator 1h
To control the focusing of the objective lens 1a.

With the above configuration, the offset amount can be mapped and the focus control can be performed using the mapped offset amount.However, since the tracking control signal is a difference signal between the detection signals of the two light receiving elements 1e, for example, When the lens moves in the tracking direction, the light incident on the light receiving element of the optical head also moves, and an error is superimposed on the signal for tracking control, and the amplitude of the signal for tracking control due to focus shift due to astigmatic difference. There is a high possibility that an error occurs in the function value due to the change and an incorrect offset value is set.

Therefore, as described above with respect to the tracking offset value, the optimum offset value may be detected from the relationship between the amplitude of the data signal such as the header and the focus control position, and may be converted into a value. This will be described below.

FIG. 21 is a circuit configuration diagram necessary for using the amplitude of the data signal.

At the time of the jump, the microprocessor 8 gives an offset amount of ± 20H and 0 to the offset addition / gain switching circuit 29 for focus control, thereby obtaining three positions of two positions and offset 0 obtained. The amplitude of the data signal is calculated.

A function representing the relationship between the offset amount and the amplitude of the data signal is calculated using the information obtained at the three points thus obtained. Since this function can be approximated as a quadratic function convex upward as shown in FIG. 22 before and after the in-focus state, it can be specified by the information at the above three points.

In this way, the constant of the function and the offset value having the maximum value are obtained, and the microprocessor 8 calculates the offset amount using the condition such as "differential value = 0" and calculates the optimum offset. The amount is stored in the memory 15 as map data.

FIG. 23 is a flowchart showing the procedure of the control contents of the microprocessor 8 described above.

FIGS. 24 and 25 are graphs showing the relationship between the focus control position and the amplitude of the data signal, respectively, corresponding to FIG. 22 for illustrating the second embodiment, and the microprocessor corresponding to FIG. 8 is a flowchart showing the control contents of FIG.

In the second embodiment, the offset amounts + aH and -bH having the same amplitude C on both sides of the offset amount 0 are given, and the same processing as in the above-described example is performed at three positions with the offset amount 0.

〔The invention's effect〕

As described above, according to the present invention, the calibration value of the servo circuit can be easily calculated from the area on the optical disk,
It is possible to obtain an optimum calibration value at that time and to provide an excellent effect of providing an optical disc apparatus capable of always performing stable and optimum servo control.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an optical disk device having a servo circuit of the present invention, FIG. 2 is a flowchart showing the operation of the present invention, FIG. 3 is a diagram showing the output of a differential amplifier, and FIG. Is an explanatory diagram showing a state in which the optical disk is divided into regions, and FIG.
FIG. 6 is an explanatory view showing the movement of the beam for calculating the offset of the area 1, FIG. 6 is an explanatory view showing another embodiment showing the movement of the beam, and FIG. 7 is an explanatory view for determining the boundary of the area. FIG. 8 is an explanatory diagram showing the signals of the differential amplifier at the time of access, FIG. 9 is a block diagram of the overall configuration of an optical disk drive using an observer, and FIG. 10 is the speed in the optical disk drive of FIG. FIG. 11 is a block diagram of a control system, FIG. 11 is an explanatory diagram showing a relationship between a tracking sensor signal and a tracking crossing signal, FIG. 12 is an explanatory diagram showing a header section of an optical disk, and FIG. 13 is an operation of this system. Showing the flow chart,
FIG. 14 is a relationship diagram showing the relationship between the amplitude of the data signal and the offset amount, FIG. 15 is an explanatory diagram in which the offset value is set to 0 based on the drive current and the sensor output, and FIG. 16 is a diagram illustrating the change in the sensor gain. FIG. 17 is a comparison diagram for comparing a fixed threshold value with a threshold value set in the present invention, FIG. 18 is a configuration diagram for mapping a focus offset, and FIG. 19 is a configuration diagram of FIG. FIG. 20 is an explanatory diagram for explaining an optimal offset, FIG. 21 is a configuration diagram of another embodiment, and FIG.
FIG. 22 is a view for explaining the optimum offset obtained by the configuration of FIG. 21, FIG. 23 is a flowchart for operating the configuration of FIG. 21, and FIG. 24 shows another embodiment of the focus offset. FIG. 25 is a flowchart showing a procedure for obtaining the offset value obtained in FIG. In the figure, (2) is an A / D converter, (3) is a maximum value register,
(4) is a minimum value register, (5) is a multiplexer,
(8) indicates a microprocessor, and (15) indicates a memory. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 1-173344 (32) Priority date Hei 1 (1989) July 4 (33) Priority claim country Japan (JP) (31) Priority Claim No. Hei 1 -189632 (32) Priority Date Hei 1 (1989) July 20 (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 1 -318524 (32) Priority (1) Japan, Japan (JP) (72) Inventor, Yoshiki Nakajima 8-1-1, Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture Mitsubishi Electric Corporation Industrial Systems Research Institute (72) ) Inventor Hidetake Takeda 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture Inside the Central Research Laboratory of Mitsubishi Electric Corporation (56) References JP-A-64-46240 (JP, A) JP-A-63-78386 (JP, A )

Claims (3)

(57) [Claims] 1. An optical disk apparatus comprising: a servo circuit for irradiating an optical disk with a beam and controlling an irradiation position of the beam based on a reflected light of the emitted beam; means for dividing the optical disk into a plurality of areas; Means for detecting the maximum value and the minimum value of the signal obtained by traversing the predetermined track of each of the detected areas, means for detecting the amplitude of the signal from the detected maximum value and the minimum value, and the detected amplitude An optical disk device, comprising: means for changing a sensor gain so as to keep a constant, and controlling a servo circuit in each area by the changed sensor gain. 2. An optical disc apparatus for performing tracking control for causing a projection light beam to follow a recording track on an optical disc, means for dividing the optical disc into a plurality of areas, wherein the reflected light of the light beam applied to each of the divided areas is used. Means for detecting the amplitude of the obtained signal, means for calculating a function indicating the relationship between the tracking control and the amplitude from the amplitude of the signal obtained at at least three different tracking control positions, and a local maximum value of the function An optical disc apparatus, comprising: means for calculating an offset value of tracking control of each area so as to control a tracking position related to (1), and calibrating tracking control of each area by the calculated offset value. 3. An optical disc apparatus for performing focus control for causing a projection light beam to follow a recording track on an optical disc, means for dividing the optical disc into a plurality of areas,
Means for detecting the amplitude of a signal obtained from the reflected light of the light beam applied to each of the divided areas, and the relationship between focus control and amplitude based on the amplitude of the signal obtained at at least three different focus control positions. Means for calculating a function indicating
Means for calculating an offset value of focus control of each area so as to control the focus position related to the local maximum value of the function, and calibrating the focus control of each area by the calculated offset value. Optical disk device.