JPH08167160A - Optical disk device - Google Patents

Abstract

PURPOSE: To provide an optical disk device capable of automatically and accurately adjusting the gain of a servo system and realizing very reliable recording/ reproducing. CONSTITUTION: A digital signal processing circuit 20 controls the level of a disturbance value for measuring the gain of the servo system and frequency. By optimizing the level and measuring on plural frequencies, the gain is adjusted. Then, the gain is set by storing and interpolating the measured address positions on the inner periphery and the outer periphery of an optical disk 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device for recording or reproducing a signal on a record carrier surface by using a converged light spot.

[0002]

2. Description of the Related Art As a technique relating to a device for adjusting the gain of a conventional optical disc device, there is one described in Japanese Patent Publication No. 59-22290.

An optical disk device has an information track of 1.6 μm pitch provided on a record carrier of an optical disk and has a size of about 1 μm.
The optical spot of φ is about ± 0.5μ in the direction perpendicular to the surface of the record carrier.
Performs highly accurate focus control that follows with m accuracy.

Further, high-precision tracking control is performed in which the track deviation between the information track and the light spot follows with an accuracy of about ± 0.1 μm.

If there is a gain variation in the optical head and the actuator, highly accurate control cannot be performed.

For example, if there is a gain variation in the focus system, focus control cannot be performed with an accuracy of about ± 0.5 μm, resulting in a large error, or if the gain is high, oscillation will occur and control will be disturbed.

The same applies to tracking control.
Therefore, conventionally, gain is set by the volume,
It corresponded by switching.

[0008]

However, the above-mentioned structure has a problem in that it cannot be corrected when the gain of the optical head changes from the initial set value due to changes with time or temperature changes.

SUMMARY OF THE INVENTION The present invention solves the above problems, and an object of the present invention is to provide an optical disk apparatus capable of correcting gain and stabilizing recording and reproduction on an optical disk.

[0010]

In order to achieve this object, an optical disk apparatus according to the present invention comprises a disturbance adding means for adding a disturbance to a signal of a focus shift detecting means or a track shift detecting means, and a disturbance and a signal after addition of the disturbance. The gain is adjusted by including a phase calculating means for more calculating the phase, a gain adjusting means for changing the gain of the control means, and a calculating means for controlling the disturbance value and controlling the phase calculating means.

Further, there is provided a calculating means for changing the amplitude of the disturbance value applied to the disturbance adding means to obtain a substantially minimum disturbance value at which the phase values detected by the phase calculating means are substantially equal, and the gain is adjusted.

Further, the frequency of the disturbance value applied to the disturbance adding means is changed to a plurality of values, the gain is changed so that the phase value detected by the phase calculating means becomes a predetermined value, and a predetermined gain is obtained from the plurality of gain change values. And a calculation means for operating the gain adjustment means to adjust the gain.

Further, the gain adjusting means is operated to change the position of the optical disk to be measured, the position and the gain change value are stored, and the calculating means is provided for interpolating the gain value according to the position of the optical disk and operating the gain value. adjust.

Also, the divided partial processing of the gain measurement processing is performed during the period until the optical disk position is moved and the next processing is performed, the divided processing is executed, and the gain is reset when the predetermined processing is completed. And a gain is adjusted.

[0015]

According to the present invention, since the gain is adjusted by the calculating means, the gain changed from the initial set value due to a change over time or a temperature change can be corrected by the above-described structure.

Since the amplitude of the disturbance value applied to the disturbance addition means is changed to a plurality of values to obtain a substantially minimum disturbance value at which the phase values detected by the phase calculation means are substantially equal, the influence of the added disturbance on the control system is small. .

The frequency of the disturbance value applied to the disturbance adding means is changed to a plurality of values, the gain is changed so that the phase value detected by the phase calculating means becomes a predetermined value, and the gain is changed to a predetermined gain from the plurality of gain change values. Since the adjusting means is set by the calculating means, the adjustment can be performed accurately.

The position of the optical disc to be measured is changed by operating the gain adjusting means to store the position and the gain change value,
Since the gain value is interpolated and operated according to the position of the optical disc, it is possible to cope with a change due to the position of the optical disc.

In order to move the position of the optical disk and perform the next processing, the divided processing relating to the measurement of the gain is performed, and when the divided processing is completed and the predetermined processing is completed, the gain is set at almost constant time intervals. Gain adjustment can be performed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk device according to an embodiment of the present invention will be described below with reference to the drawings.

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

The light beam emitted from the semiconductor laser 1 becomes parallel light by the collimator lens 2 and the beam splitter 3,
It is focused on the information track 6 of the optical disk 5 via the aperture lens 4. The optical disk 5 is rotated by the motor 12. Next, the light reflected from the optical disk 5 passes through the aperture lens 4 again to become parallel light, and the beam splitter 3/1 /
After passing through the two-wave plate 7 and the beam splitter 8 and entering the focus shift detector 10 through the cylindrical lens 9, astigmatism type focus shift detection is performed.

The track shift detector 11 constitutes a far-field type track shift detection in which the light beam split by the beam splitter 8 enters.

The signals of the respective detectors are amplified by the amplifier circuit 13,
Amplification or current-voltage conversion is performed at 14, 15, and 16.

Based on the amplified detection signal, the differential amplifier circuit 17 shows the focus error signal indicating the focus shift between the recording surface of the optical disc 5 and the light spot, and the differential amplifier circuit 18 shows the shift between the information track of the optical disc 5 and the light spot. Get the tracking error signal.

The focus error signal is the AD conversion circuit 19
Then, the analog signal is converted into a digital signal and the digital signal processing circuit 20 is entered.

The digital signal processing circuit 20 performs the phase compensation processing of the focus control system, and the focus actuator 2 which is the focus moving means via the drive circuit 21.
3 is moved to converge the light beam on the recording surface of the optical disc 5.

Similarly, the tracking error signal is converted into a digital signal by the AD conversion circuit 19 and enters the digital signal processing circuit 20 to perform phase compensation processing of the track control system, and through the drive circuit 22, a tracking actuator 24 which is a track moving means. Is moved so that the light beam follows the information track of the optical disc 5.

The method of adjusting the loop gain of the focus servo system or the tracking servo system will be described below.

The structure of the servo system is shown in FIG. An optical head system 25 for obtaining a servo signal, a digital signal processing section 26 for applying a disturbance to the servo signal to perform a filter processing 28 and a gain processing 29, and an actuator system 27 for driving an actuator by a drive signal from the digital signal processing section 26.
Consists of

Here, the gain is set so that the phase of the disturbance signal X and the sum of the signal Y1 before the disturbance signal X and the signal Y2 after the disturbance become 90 degrees.

The gain is multiplied by 1 at the frequency of the disturbance signal X, and the gain intersection point can be set. The vector diagram is shown in FIG. When the open loop transfer function is G, when the phase of the sum of Y1 and Y2 and the disturbance signal X is 90 degrees, G is 1 time.

When G is larger than 1 times, the phase is 9
It becomes larger than 0 degrees and becomes smaller than 90 degrees when G is smaller than 1 time.

If the disturbance signal X is a triangular wave signal, it can be detected as shown in FIG. a indicates a signal of Y1 + Y2, and b indicates a signal of X.

Although not shown in the drawing, the a and b signals Vre are detected.
Binarization is performed at the f level, the exclusive OR of the respective binarized signals is obtained, the ratio to one cycle is obtained, and the phase is calculated.

When the transfer function A before the disturbance signal X in FIG. 2 and the transfer function after the disturbance X are B are shown in FIG.

In FIG. 5, when the displacement of the optical disk 5 is R and the deviation from the light spot position C is E, the relationship between the deviation E and the disturbance is E = R / (1 + A * B) + X * B / (1 + A * B)
It is represented by.

When the deviation is made a constant value in order to make the measurement error of the phase value constant, it is not necessary to change the disturbance signal X with respect to the change of A, and to change the disturbance signal X with the change of B so much.

When the gain of the detection system of the optical head changes, the disturbance signal X can be accurately detected by changing it according to its magnitude.

Therefore, in order to accurately detect the phase difference 30 from the triangular wave of Y1 + Y2 as shown in FIG. 4, it is necessary to set the level of X to the optimum value.

As shown in FIG. 6, the level of the disturbance signal X is changed to each value of c, d, e, or higher, Y1 + Y2.
The phase difference 30 from the signal is measured, and a substantially minimum value at which the measured value is almost stable is used as the level of the disturbance signal X.

FIG. 7 shows an example of frequency characteristics of the open loop transfer function. In order to match the gain intersection points, the frequency of the disturbance signal X is set to f1 and the gain is adjusted so that the phase difference of the sum of the disturbance signal X and the signals before and after the point where the disturbance signal is applied becomes 90 degrees.

In this state, the frequency is f2 and the disturbance signal X
When the gain is adjusted so that the phase difference of the sum of the signals before and after the point where the disturbance signal is added becomes 90 degrees, a state in which the gain is reduced by F compared to when the frequency is f1 is obtained.

The slope of the frequency characteristic of the open loop transfer function does not change even if the loop gain of the focus servo system or the tracking servo system changes.

Therefore, since the value of F with respect to the value of f2 / f1 is obtained by calculation in advance, when the error from the gain measurement value due to the phase difference is within the predetermined range, it is judged that the phase measurement is correct and the loop gain is set. .

Alternatively, these values are calculated and averaged by the gain at the desired frequency and set.

By further increasing the frequency for measurement,
The effect of averaging is improved. These processes are performed by the digital signal processing circuit 20.

At the inner and outer circumferences of the optical disk 5, the optical disk 5
If the slope of is different, the light amount to the detector of the optical head changes and the loop gain changes.

Although the tracking error signal detection system is not shown in the figure, the known three-beam method is used for the optical disk 5.
The detection sensitivity of tracking changes depending on the assembly accuracy of the mechanism in the direction of movement to the center, inner circumference, and outer circumference. An example is shown in FIG.

The gain measurement is stored together with the position of the optical disk 5, and the other parts are interpolated to set the gain.

The interpolation is performed by assuming that the gain is monotonically increased or monotonically decreased between the positions where the gain is measured.

The position of the optical disk 5 is stored by the address recorded on the optical disk 5.

When the gain of the destination address is not measured, it is calculated that the gain is monotonically increasing or decreasing within a predetermined range based on the measured value, and the gain is set to move.

Further, the gain may be stored by the number of tracks from a predetermined inner peripheral position. Further, in the gain measurement, the disturbance signal level, the disturbance signal frequency, and the position of the optical disk may be combined or processed in parallel to reset the gain value.

Initially, the gain is measured and stored at a predetermined position. If the amount of data is too small to set the gain at the move destination, move it with the current gain set.

Further, the number of cycles of the triangular wave of the disturbance value is reduced as one unit, the phase difference is obtained in this unit, and the phase difference is calculated a predetermined number of times to set the gain.

At this time, the measurement position is obtained, and it is not used when the positions are more than a predetermined distance. Alternatively, it is stored as phase measurement data in an address within a predetermined range, and when a predetermined number of times is satisfied, it is set as a gain measurement value in that address range.

Although a triangular wave is used as the disturbance signal in the embodiment, a sine wave signal or a rectangular wave can be similarly used.

FIG. 9 shows a flow for measuring and setting the gain deviation. (1) A disturbance is applied to the control system at a predetermined value, a phase is calculated, and a gain deviation is obtained and stored.

(2) The disturbance value is increased by a predetermined value from the initial predetermined value, the disturbance is added to the control system, the phase is calculated, and the gain deviation is obtained and stored.

(3) (2) is repeated a predetermined number of times. (4) The minimum disturbance value within which the stored variation in gain deviation falls within a predetermined range is obtained.

(5) The gain is set so as to correct the gain deviation obtained in (4). The repetition of (3) may be passed at a value at which the gain deviation can be measured to be substantially equal in the process of gradually increasing from the initial disturbance value.

FIG. 10 shows a flow for measuring the gain deviation based on the disturbance value obtained above. (6) When the position of the optical disc is moved, the disturbance waiting time obtained in (4) is added to the predetermined cycle control system during the rotation waiting time,
The gain deviation is obtained by the subsequent phase calculation in a predetermined cycle.

(7) The gain deviation is stored together with the address indicating the position of the optical disk. (8) When a predetermined number of gain deviation measurement data within a predetermined range of addresses have been accumulated, the gain is reset according to the gain deviation value.

(9) Repeat steps (7) and (8). The predetermined cycle is, for example, two cycles, and the phase calculation of the subsequent one cycle is performed to obtain and store the gain deviation. When the number of times of storage is, for example, 16 times in an address within a predetermined range, the gain deviation is averaged to set the gain.

The predetermined address range is, for example, a value divided into 10 in the radial direction of the disk. In this case, the gain is corrected when the gain deviation measurement is performed 16 times in the address range divided into 10.

The predetermined cycle, the average number of times, and the number of divisions are optimized by changing the processing time and the characteristics.

When the optical disk is changed, the procedure is performed from (6). The change in the amount of reflected light from the optical disk is obtained from the amplitude of the focus error signal, and the disturbance value obtained in (1) to (4) is corrected according to the change and used.

Instead of the focus error signal, the sum signal of the amplifier circuits 13 and 14 or the sum signal of 13, 14, 15 and 16 may be used.

If the processing time may be long, the process is repeated from (1).

[0071]

As described above, according to the present invention, by adjusting the gain of the focus / tracking servo system every ON operation, the gain of the control system can be optimally adjusted even if it changes over time.

When measuring the gain of the control system, the disturbance value is set so as to be the minimum required value, so that the influence of the disturbance on the control system is small.

Since the gain measurement is performed at a plurality of frequencies, the gain can be adjusted with high accuracy and the gain can be set with high reliability.

Measurement is performed by moving the position of the optical disk and performing the next processing, for example, by dividing the processing to a rotation waiting time so that the processing time is shortened, and the gain setting is performed when the predetermined number of division processings are completed. In order to perform it, the gain adjustment can be performed at regular time intervals, and the same effect as that of performing the gain adjustment almost at all times can be obtained.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing the configuration of a servo system.

[Fig. 3] Vector diagram of servo system signals

FIG. 4 is a detected waveform diagram when a disturbance is applied.

FIG. 5 is a block diagram of a servo system for explaining gain measurement.

FIG. 6 is a disturbance waveform diagram for explaining gain measurement.

FIG. 7 is a frequency characteristic diagram for explaining gain measurement.

FIG. 8 is a diagram showing the relationship between optical disc position and gain.

FIG. 9 is a gain deviation setting flowchart.

FIG. 10 is a gain deviation setting flowchart.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 semiconductor laser 5 optical disk 10 focus shift detector 11 track shift detector 13,14 amplification circuit 17,18 differential amplification circuit 19 AD conversion circuit 20 digital signal processing circuit 21,22 drive circuit 23 focus actuator 24 tracking actuator 25 optical head System 26 Digital signal processing unit 27 Actuator system 28 Filter processing 29 Gain processing

Claims (5)

[Claims] 1. A focus shift detection means for detecting a focus shift between a recording surface formed on a record carrier and a light spot,
A focus moving unit that moves the light spot in a direction substantially perpendicular to the recording surface, a focus control unit that controls the focus moving unit according to a signal from the focus shift detection unit, and an information track formed on the recording surface. Track deviation detecting means for detecting a track position deviation from a light spot, track moving means for moving the information track in a substantially vertical direction, and track control for controlling the track moving means in response to a signal from the track deviation detecting means. Means, a disturbance adding means for adding a disturbance to the signal of the focus shift detecting means or the track shift detecting means, a phase calculating means for calculating a phase from the disturbance and the signal after the disturbance addition, and a gain for changing the gain of the control means. It is provided with an adjusting means and a calculating means for controlling the disturbance value control and the phase calculating means. Optical disk apparatus according to symptoms. 2. A calculation means for changing the amplitude of the disturbance value applied to the disturbance addition means to a plurality of values to obtain a substantially minimum disturbance value at which the phase values detected by the phase calculation means are substantially equal. The optical disk device according to claim 1. 3. The frequency of the disturbance value applied to the disturbance adding means is changed to a plurality of values, the gain is changed so that the phase value detected by the phase calculating means becomes a predetermined value, and a predetermined gain is obtained from the plurality of gain change values. 2. The optical disk device according to claim 1, further comprising arithmetic means for operating the gain adjusting means. 4. A calculation means is provided which operates the gain adjusting means to change the position of the optical disc to be measured, stores the position and the gain change value, and interpolates the gain value according to the position of the optical disc to operate. The optical disk device according to claim 1, wherein: 5. The gain is reset when a divided partial process of the process related to the gain measurement is performed during the period from the movement of the optical disc position to the next process, and the divided process is executed and the predetermined process is completed. 2. The optical disk device according to claim 1, further comprising a computing means for performing the operation.