JPH11203702A - Optical disk drive - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve tracking control performance and to improve system robustness against disk defects and the like.
Further, an optical disk device provided with a learning controller capable of improving the processing speed of a control system without increasing the manufacturing cost is provided. SOLUTION: In an optical disk device having a tracking control system, a plurality of digital filters 1 (1) to 1 (N) are used as a learning controller 1 for learning and controlling disturbance mixed in a tracking error signal. By providing switching means 4 and 5 for sequentially switching the input side and the output side to one of the filters 1 (1) to 1 (N) and connecting them periodically, each of the filters 1 (1) to 1 (N) is provided. )
Then, the time-division tracking error signal is sequentially and periodically assigned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus using a learning controller for a servo control system, and more particularly to improving the servo control performance, improving the robustness of the system against disk defects, and manufacturing the same. The present invention relates to a system capable of improving the processing speed of a system without increasing costs.

[0002]

2. Description of the Related Art In an optical disk apparatus for recording and reproducing signals on and from a disk-shaped optical recording medium (hereinafter, collectively referred to as an optical disk) such as a compact disk (CD) or a magneto-optical disk, a tracking control system and a focusing system are used. Initially, as a method to improve the stability and responsiveness of a servo control system such as a control system, a method of inserting a phase delay compensation element / phase advance compensation element into the servo control system, The method of adding was adopted.

[0003] By the way, in today's optical disks, the recording density is steadily increasing in order to satisfy needs such as an increase in recording capacity and an improvement in recording / reproducing speed. As the recording density increases, the spacing between tracks decreases,
In an optical disk device that performs recording and reproduction of such an optical disk, it is required to perform tracking control with higher precision.

On the other hand, among optical discs, the numerical aperture of an objective lens is standardized to 0.45 in a CD, whereas
Digital video disc (DVD) that appeared afterwards
, This numerical aperture is standardized to 0.6. It is considered that such a tendency of the numerical aperture increase will be further accelerated in the future. Since the numerical aperture may be considered to be the angle at which the laser beam is narrowed, the laser beam is narrowed at a steeper angle as the numerical aperture increases. It is known that an allowable error range of focusing of an objective lens, which is called a depth of focus, is inversely proportional to the square of the numerical aperture. Therefore, as the numerical aperture increases, the optical disc device also needs to perform focusing control with higher precision.

However, maintaining the stability and responsiveness of the control system when performing such high-accuracy tracking control and focusing control requires a method of inserting a phase delay compensation element and a phase advance compensation element as in the related art. It was difficult to add a feedback loop.

Therefore, by adopting a learning controller for learning control of disturbance mixed into the tracking error signal and the focusing error signal (reducing the control deviation of tracking control and focusing control due to the disturbance by a learning effect), a highly accurate learning controller is provided. An optical disk device with improved tracking control performance and focusing control performance so that stability and quick response is maintained even when performing tracking control and focusing control has appeared.

The learning controller reduces the control deviation by an integrator (digital filter). The principle of the learning controller is as follows. As shown in FIG. 7, if an integrator 31 is provided in the control system, even if a digital signal (a signal obtained by sampling an analog signal at a predetermined sampling frequency) input to the control system changes stepwise, It is known that the operation of the integrator 31 causes a signal equal to this step-like input signal to be output from the control system without any offset (that is, to follow the step-like input signal without any offset). (Classical control).

[0008] This can be intuitively grasped as follows. If the input signal to the integrator 31 (the difference between the input signal to the control system and the output signal from the control system) is the control deviation, the integrator 31 continues to integrate (add) this control deviation. As time elapses, the output of the integrator 31 increases. Since the output of the controlled object also increases in accordance with the increase in the output of the integrator 31, the output signal of the controlled object gradually approaches its input signal. Then, when the output signal of the control target becomes equal to the input signal, the control deviation becomes 0, and therefore, the integrator 31 stops increasing the output (when the output signal of the control target becomes equal to the input signal). Is held). Thereby, the integrator 3
The control system provided with 1 follows a step-like input signal without any offset.

Therefore, such a learning controller is provided in the tracking control system or the focusing control system, and a tracking error signal or a focusing error signal which is digitally converted at a predetermined sampling frequency is input to the tracking control system or the focusing control system.
It follows the tracking error signal and the focusing error signal mixed with the disturbance without any offset.

Conventionally, the learning controller used in the servo control system of the optical disk apparatus in this way has only one integrator (digital filter).

[0011]

However, the optical disk device using such a conventional learning controller has the following disadvantages.

(A) In general, in a consumer optical disk device, sudden (non-periodic) due to a defect (for example, a scratch) or the like of a disk occurs in order to prioritize cost reduction.
It is desired that the system be less susceptible to disturbance, that is, a system having robustness (robust control performance) against disk defects and the like. In contrast,
In an optical disk device using a conventional learning controller, once a sudden disturbance due to such a defect of the disk is mixed into a tracking error signal or a focusing error signal, the control deviation due to the sudden disturbance is continuously propagated. Therefore, it has been difficult to improve the robust control performance.

(B) In order to increase the sampling frequency in order to improve the processing speed of the system, it is necessary to use a digital filter composed of a processor having a high arithmetic processing speed (and therefore expensive). This leads to higher costs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and solves the disadvantages of an optical disk device using a conventional learning controller, improves tracking control performance and focusing control performance, and improves robust control performance. It is another object of the present invention to provide an optical disk device provided with a learning controller capable of improving the processing speed of a control system without increasing the manufacturing cost.

[0015]

According to a first aspect of the present invention, there is provided an optical disk apparatus having a tracking control system, wherein a plurality of digital filters are used as learning controllers for learning and controlling disturbances mixed in a tracking error signal. Switching means for sequentially switching the input side and the output side of the learning controller to each of the plurality of digital filters and connecting the digital filters periodically.

In this optical disc apparatus, the input side and the output side of the learning controller are sequentially switched to one of a plurality of digital filters (integrators) and connected periodically, so that each digital filter is time-divided. The tracking error signals are sequentially and periodically assigned.

Here, the disturbance constantly mixed in the tracking error signal is a periodic disturbance caused by the eccentricity of the disk. FIG. 8A shows an example of a tracking error signal (analog signal) mixed with such a periodic disturbance (more precisely, a fundamental wave component of the periodic disturbance), and FIG. 8B shows a sampled analog signal of FIG. An example of the obtained signal (digitally converted tracking error signal) is shown.

Therefore, by sequentially and periodically taking charge of the tracking error signal thus time-divided,
Each digital filter can periodically take charge of a step-like input signal having a different level (for example, in the example of FIG. 8B, each of the time-division tracking error signals e1 to e10 of each period is one by one). (Total 1
0) digital filters can be assigned). According to the principle described above, the operation of each digital filter allows the digital filter to follow the step-like input signal assigned thereto without offset. As a result, the tracking error signal mixed with the periodic disturbance follows without any offset, so that the tracking control performance is greatly improved.

Further, even when a non-periodic disturbance caused by a defect of the optical disk or the like is mixed in the tracking error signal, the digital filters other than the digital filter which is responsible for the tracking error signal in the portion where the disturbance is mixed are completely different. Unaffected by the disturbance. (For example, if such disturbance is mixed in the tracking error signal e1 in the example of FIG. 8B, the tracking error signal e2
The digital filter assigned to e10 is not affected at all. As described above, since the influence of the disturbance due to the defect of the optical disk or the like is limited to a part of the digital filters, the robust control performance of the entire system is improved.

Further, by sequentially assigning a tracking error signal to each of a plurality of digital filters as described above, the system can be manufactured without increasing the manufacturing cost for the reason described below with reference to FIG. The processing speed as a whole can be improved.

FIG. 9 is a time table showing an example of input / output timing of each digital filter when, for example, three digital filters 21 to 23 are provided. In the figure, the first tracking error signal is output to the digital filter 21 at time t0, although three arithmetic operations are required for each of the digital filters 21 to 23 once.
After the time t3 when the tracking error signal is again input to the digital filter 21 after input to the digital filter 21 (that is, after the second cycle), the digital filter 21
Signals are sequentially output from the signals 22 and 23 (the system turns around in one unit time). In this case, at least one unit time is sufficient for the sampling cycle when the tracking error signal is converted into a digital signal.

On the other hand, when only one of these digital filters 21 to 23 is provided as in the prior art, a signal is output from the digital filter only every three unit times (3 unit time). Therefore, at least three unit times are required as the sampling period.

Therefore, in the case of the example shown in FIG. 9, even if a digital filter constituted by a processor having a low arithmetic processing speed (and therefore inexpensive) is used as a plurality of digital filters, the sampling frequency is made higher than in the prior art ( Therefore, the processing speed of the entire system can be improved).

Although three digital filters are provided in the example of FIG. 9, it goes without saying that this sampling frequency can be increased as the number of digital filters is increased. In this way, the processing speed of the entire system can be improved without using a digital filter constituted by a processor having a high arithmetic processing speed (and thus without increasing the manufacturing cost).

Next, in an optical disk device according to a second aspect of the present invention, in the optical disk device having a focusing control system, a plurality of digital filters are provided as learning controllers for learning and controlling disturbances mixed in a focusing error signal. Switching means for sequentially switching the input side and the output side of the learning controller to each one of the plurality of digital filters and periodically connecting the digital filters is provided.

Also in this optical disk device, just like the optical disk device according to the first aspect, each digital filter sequentially and periodically takes charge of a time-division focusing error signal.

The disturbance that constantly mixes with the focusing error signal is also a periodic disturbance caused by the disk runout. Therefore, for exactly the same reason as already described for the optical disk device according to claim 1,
Also, the focusing error signal mixed with the periodic disturbance follows without any offset, so that the focusing control performance is greatly improved.

In addition, even when a non-periodic disturbance caused by a defect of the optical disk or the like is mixed in the focusing error signal, the effect of the non-periodic disturbance still remains in some digital filters. Control performance is improved.

For the same reason as already described for the optical disk device according to the first aspect, it is also possible to use a digital filter constituted by a processor having a low processing speed (and thus inexpensive) as each of the plurality of digital filters. Since the processing speed of the entire system can be improved, the processing speed of the entire system can be improved without increasing manufacturing costs.

In the optical disk devices according to the first and second aspects, it is preferable that the plurality of digital filters of the learning controller have a power function characteristic. By doing so, in these digital filters, the evaluation of the control deviation input in the past becomes higher exponentially with respect to the control deviation input in the past (that is, the evaluation of the control deviation input in the past becomes higher). The weighted integration is performed (so that it drops sharply).

Therefore, a signal of a portion where a non-periodic disturbance due to a defect or the like of an optical disc is mixed (for example, FIG. 8B
In the digital filter that is in charge of the tracking error signal e1), the ratio of the control deviation due to the non-periodic disturbance rapidly decreases as time elapses (that is, the periodic deviation is added) because the subsequent control deviation is added. Therefore, the control deviation due to the disturbance which does not occur is not continuously propagated.) Thereby, the robust control performance is further improved.

In these optical disk devices,
It is preferable to provide a means for generating a signal synchronized with the rotation of the optical disc, and to perform switching by the switching means based on this signal.

The reason is as follows. As described above, the disturbance that constantly mixes into the tracking error signal and the focusing error signal is a periodic disturbance caused by the eccentricity and runout of the optical disk, and the period of such periodic disturbance corresponds to the rotation speed of the optical disk. (More precisely, the period of the fundamental component of the periodic disturbance coincides with the rotation period of the disk, and the periodic disturbance includes higher harmonic components of this fundamental wave.)

As a result, when the switching cycle of the switching means is fixed, only the control deviation due to the periodic disturbance of one cycle corresponding to a certain rotation speed is reduced. If the rotation speed is different from this fixed rotation speed, the control deviation due to the periodic disturbance caused by eccentricity and surface runout will not be reduced, so that the tracking error signal and the focusing error signal mixed with the periodic disturbance will be lost. It will not follow without an offset.

On the other hand, in the case where the switching is performed by the switching means based on a signal synchronized with the rotation of the disk, the control deviation due to the periodic disturbance having the period corresponding to the current rotational speed is always reduced. Therefore, the control deviation due to the periodic disturbance caused by the eccentricity and the surface runout is always reduced irrespective of the rotation speed fluctuation (the tracking error signal and the focusing error signal in which the periodic disturbance caused by the eccentricity and the surface runout are mixed) Always follows without offset). Thereby, the tracking control performance and the focusing control performance are further improved.

Of the optical discs, for example, a CD is configured to rotate at a constant linear velocity so that the number of revolutions is changed between when reproducing an inner track and when reproducing an outer track. As described above, for an optical disc apparatus that performs recording and reproduction of an optical disc whose rotation speed is not constant,
It is particularly desirable that control deviations due to periodic disturbances of a cycle always corresponding to the current rotational speed are reduced.

Even in an optical disk apparatus that performs recording and reproduction of an optical disk without changing the rotation speed of the disk (rotating at a constant angular velocity), the rotation speed of the disk actually varies to some extent due to uneven rotation of the motor. Therefore, it is still desirable that the control deviation due to the periodic disturbance having the cycle corresponding to the current rotational speed is always reduced.

Incidentally, in an optical disk apparatus for recording and reproducing an optical disk having a pit address portion in which grooves or address information wobbled at a predetermined frequency, such as a magneto-optical disk, for example, the rotation is synchronized with the rotation of the optical disk as described above. Instead of providing a means for generating such a signal, switching by the switching means may be performed based on address information reproduced from the groove or pit address portion.

Since such address information is also reproduced in synchronization with the rotation of the disk, switching is performed based on this address information. The tracking error signal and the focusing error signal mixed with the periodic disturbance are always followed without any offset. In addition, since there is no need to provide a means for generating a signal synchronized with the rotation of the optical disk, an increase in manufacturing cost can be suppressed from this point as well.

[0040]

FIG. 1 is a block diagram showing an example of a tracking control system of an optical disk device according to the present invention. This tracking control system includes a learning controller 1, a dynamic characteristic compensator 2, and a tracking actuator 3. The dynamic characteristic compensator 2 is for setting the dynamic characteristic of the control system, and is composed of, for example, a well-known phase lead compensation element.

An example of the configuration of the learning controller 1 is shown in FIG.
It is as follows. The learning controller 1 includes N (N is an appropriate integer of 2 or more) parallel digital filters 1 (1) each including a digital signal processor (DSP) (or realized using a general-purpose microprocessor).
-1 (N) (R1 (z) to RN (z) are transfer functions of these digital filters) and the input and output sides of the learning controller 1 are digital filters 1 (1) to 1 (1), respectively.
1 (N) and an input-side switch 4 and an output-side switch 5 for switching and connecting to one of them.

FIG. 3 shows an individual digital filter 1 (1).
FIG. 2 is a functional block diagram showing processing in 1 to (N);
a is a multiplier coefficient (tap coefficient), and z is a unit delay time of the delay element. As can be understood from the figure, the processing contents of the individual digital filters 1 (1) to 1 (N) are slight,
(1) to 1 (N) need only have a small configuration. FIG.
3 specifically shows the transfer functions R1 (z) to RN (z) in FIG. 2 in relation to FIG.

This optical disk device has an encoder (not shown) for detecting the rotation angle position of an optical disk (not shown), and inverts at a constant rotation angle (360 / N degrees) using an output signal of the encoder. And a clock signal generating circuit (not shown) for generating a clock signal to be supplied to the input side switch 4 and the output side switch 5 as a switching control signal.

The input side switch 4 and the output side switch 5
Each time the clock signal is inverted, the digital filter connected to the input side and the output side of the learning controller 1 is set to 1 (1),
Are sequentially switched to 1 (2),..., And when 1 (N) is reached, the process returns to 1 (1) and the switching of 1 (1), 1 (2),.

As shown in FIG. 5, the input side and the output side of the learning controller 1 use the digital filter 1 with the current rotation period T of the optical disk as the repetition period.
(1) to (N) are sequentially switched one by one so that they are periodically connected.
(1) to 1 (N) sequentially and periodically take charge of the time-division tracking error signal. (In the figure,
The period in which each of the filters 1 (1) to 1 (N) is responsible for the time-division tracking error signal within this repetition period is represented by the transfer function of the filter (see FIG. 2). Also, the waveform in the figure shows the transition of the eccentric amount of the optical disk within one rotation period T. In addition, the input side switch 4 and the output side switch 5 may be realized by any of hardware (for example, a multiplexer) for performing electronic switching and software.

The operation of the tracking control system is divided into a case where the value of the multiplication coefficient a of each of the digital filters 1 (1) to 1 (N) is set to a = 1 and a case where a <1. This will be described below.

[When a = 1] The input side and the output side of the learning controller 1 are sequentially switched to each of the digital filters 1 (1) to 1 (N) by the input side switch 4 and the output side switch 5. Thus, the digital filters 1 (1) to 1 (N) sequentially and periodically take charge of the time-division tracking error signal. Since the repetition cycle of switching by the input side switch 4 and the output side switch 5 coincides with the current rotation cycle of the optical disc as described above, this repetition cycle is currently mixed into the tracking error signal due to the eccentricity of the disc. The period of the periodic disturbance (to be exact, the period of the fundamental wave).

For this reason, the tracking control system always follows the tracking error signal without periodic offset due to the periodic disturbance caused by the eccentricity of the disk, regardless of the rotation speed, for the reasons described above. Therefore, the tracking control performance is greatly improved.

Further, even when a non-periodic disturbance caused by a defect of the optical disk or the like is mixed in the tracking error signal, the tracking error signal of the part where the non-periodic disturbance is mixed is, for example, a digital filter 1.
Assuming that the input is time-divisionally input to (1), the other digital filters 1 (2) to 1 (N) are not affected by the non-periodic disturbance at all. As described above, since the influence of the non-periodic disturbance due to the defect of the optical disc or the like is limited to some digital filters, the robust control performance of the entire system is improved.

For the reasons already described with reference to FIG. 9, digital filters 1 (1) to 1 (N) each using a processor having a low operation processing speed (and therefore inexpensive) are used. However, since the processing speed of the tracking control system as a whole is improved,
The processing speed of the whole system can be improved without increasing the manufacturing cost.

[Case of a <1] In this case as well, very similar to the case of a = 1, the tracking control performance is greatly improved, and the robust control performance of the entire system is improved. In addition, the processing speed of the entire system can be improved without increasing the manufacturing cost.

Further, in this case, each of the digital filters 1 (1) to 1 (N) has a characteristic of a power function. The control deviation input afterwards is weighted so that the evaluation of the control deviation input later is exponentially higher (that is, the evaluation of the control deviation input in the past is rapidly lowered), and the integration is performed. .

Therefore, the digital filters 1 (2) to 1 (1)
In (N), even in a digital filter in which a tracking error signal of a portion where non-periodic disturbance caused by a defect of an optical disk or the like is mixed in is input in the past, the subsequent control deviation is added. The ratio of the control deviation due to the non-periodic disturbance decreases rapidly with time (that is, the control deviation due to the non-periodic disturbance does not continue to propagate). Thereby, the robust control performance is further improved.

The ratio between the evaluation of the past control deviation and the evaluation of the current control deviation in this weighting can be adjusted to a desired ratio by changing the value of a within the range of a <1. It is.

FIG. 6 is a block diagram showing an example of the focusing control system of the optical disk device according to the present invention. This focusing control system includes a learning controller 11,
Dynamic characteristic compensator 12 and focusing actuator 1
3 is included. The configuration and operation of the learning controller 11 may be exactly the same as those of the learning controller 1 described above, and the description thereof will be omitted.

By providing such a learning controller 11, the focusing error signal in which the periodic disturbance caused by the disk runout is mixed always without offset irrespective of the fluctuation of the rotation speed. Therefore, a great improvement in focusing control performance is realized. In addition, the robust control performance of the entire system is improved, and the processing speed of the entire system is improved without increasing the manufacturing cost.
Further, when each digital filter of the learning controller 11 has a characteristic of a power function, the robust control performance is further improved.

In the above example, the switching by the input side switch 4 and the output side switch 5 is performed by using a clock signal which is inverted every fixed rotation angle created from the output signal of the encoder for detecting the rotation angle position of the optical disk. Is going. However, the present invention is not limited to this. Providing appropriate means other than an encoder that generates a signal synchronized with the rotation of the optical disc,
Switching by the input side switch 4 and the output side switch 5 may be performed based on the signal.

Alternatively, in an optical disk apparatus for recording or reproducing an optical disk having a pit address portion in which groove or address information is wobbled at a predetermined frequency, such as a magneto-optical disk, for example, an optical disk such as an encoder is synchronized with the rotation of the optical disk. Instead of providing a means for generating such a signal, the switching by the input side switch 4 and the output side switch 5 may be performed based on the address information reproduced from the groove or pit address portion.

Since such address information is also reproduced in synchronization with the rotation of the disk, switching is performed based on this address information. The tracking error signal and the focusing error signal mixed with the periodic disturbance are always followed without any offset. In addition, since there is no need to provide a means for generating a signal synchronized with the rotation of the optical disk, such as an encoder, the increase in manufacturing cost can be suppressed from this point as well.

Further, for example, in an optical disk apparatus for recording or reproducing an optical disk which does not change the rotation speed of the disk (rotates at a constant angular velocity), fluctuations in the rotation speed of the disk due to uneven rotation of the motor may be ignored. In such a case, for example, the input side switch 4 and the output side switch 5 are controlled based on a constant frequency signal such as a system clock for controlling the operation timing of each unit in the apparatus.
, The repetition cycle of this switching may be fixed.

Further, the present invention is not limited to the above-described example, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0062]

As described above, according to the optical disk device of the first aspect of the present invention, each of the plurality of digital filters sequentially and periodically handles the time-division tracking error signal. Since the tracking error signal following the periodic disturbance is mixed without offset, the tracking control performance is greatly improved.

Further, even when a non-periodic disturbance caused by a defect of the optical disk or the like is mixed in the tracking error signal, the influence of the non-periodic disturbance is limited to a part of the digital filters. Performance will be improved.

Further, the processing speed of the entire system can be improved by using a digital filter constituted by a processor having a small arithmetic processing speed (and therefore inexpensive) as each of the plurality of digital filters, so that the manufacturing cost does not increase. The processing speed of the entire system can be improved.

Next, according to the optical disk device of the second aspect of the present invention, each of the plurality of digital filters sequentially and periodically takes charge of the time-division focusing error signal. Since it follows the focusing error signal mixed with the disturbance without any offset, the focusing control performance is greatly improved.

In addition, even when a non-periodic disturbance caused by a defect of the optical disk or the like is mixed in the focusing error signal, the effect of the non-periodic disturbance still remains in some digital filters. Control performance is improved.

Further, even if a digital filter constituted by a processor having a small arithmetic processing speed (and therefore inexpensive) is used as a plurality of digital filters, the processing speed of the whole system can be improved, which also leads to an increase in manufacturing cost. And the processing speed of the entire system can be improved.

In these optical disk devices, when the plurality of digital filters of the learning controller have a power function characteristic, the control deviation inputted in the past is smaller than the control deviation inputted in the past. Is weighted so that the evaluation becomes exponentially higher, and the integration is performed. Therefore, a tracking error signal or a focusing error signal of a portion where non-periodic disturbance caused by a defect of the optical disk or the like is input in the past. Also in the digital filter, the ratio of the control deviation due to the non-periodic disturbance rapidly decreases with time (that is, the control deviation due to the non-periodic disturbance does not continuously propagate). Thereby, the robust control performance is further improved.

Further, in these optical disk devices,
When a means for generating a signal synchronized with the rotation of the optical disk is provided, and the switching is performed by the switching means based on this signal, regardless of the fluctuation of the rotation speed,
Since the tracking error signal and the focusing error signal mixed with the periodic disturbance caused by the eccentricity and the surface runout always follow without any offset, the tracking control performance and the focusing control performance are further improved.

Also, in an optical disk apparatus for recording or reproducing an optical disk having a pit address portion in which groove information or address information is wobbled at a predetermined frequency, such as a magneto-optical disk, a signal synchronized with the rotation of the optical disk is generated. Instead of providing a means to
When switching is performed by the switching means based on the address information reproduced from the groove or pit address portion, periodic disturbance due to eccentricity or surface runout is mixed regardless of the rotation speed. The tracking error signal and the focusing error signal always follow without an offset, and there is no need to provide a means for generating a signal synchronized with the rotation of the optical disk. Become.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a tracking control system of an optical disc device according to the present invention.

FIG. 2 is a block diagram showing an example of a configuration of a learning controller 1 of FIG.

FIG. 3 shows individual digital filters 1 (1) to 1 of FIG. 2;
It is a functional block diagram showing processing in (N).

FIG. 4 shows digital filters 1 (1) to 1 in FIG.
It is the figure which represented the transfer function of (N) concretely.

FIG. 5 is a diagram illustrating an example of a repetition cycle of switching of digital filters 1 (1) to 1 (N).

FIG. 6 is a block diagram showing an example of a focusing control system of the optical disc device according to the present invention.

FIG. 7 is a block diagram for explaining the principle of a learning controller;

FIG. 8 is a diagram showing an example of a tracking error signal mixed with a periodic disturbance.

FIG. 9 is a time table showing an example of input / output timings of a plurality of digital filters.

[Explanation of symbols]

Reference numerals 1, 11: learning controller, 1 (1) to 1 (N): digital filter, 2, 12: dynamic characteristic compensator, 3: tracking actuator, 4: input side switch, 5
... output side switch, 13 ... focusing actuator

Claims (6)

[Claims] 1. An optical disc device having a tracking control system, comprising: a plurality of digital filters as learning controllers for learning and controlling disturbances mixed into a tracking error signal; and a plurality of input terminals and an output side of the learning controllers. An optical disk device comprising: switching means for sequentially switching the digital filters one by one and connecting them periodically. 2. An optical disc device having a focusing control system, wherein: as a learning controller for learning and controlling disturbance mixed in a focusing error signal, a plurality of digital filters; and an input side and an output side of the learning controller are connected to the plurality of learning controllers. An optical disk device comprising: switching means for sequentially switching the digital filters one by one and connecting them periodically. 3. The optical disk device according to claim 1, wherein the plurality of digital filters have a power function characteristic. 4. The optical disk device according to claim 1, further comprising: means for generating a signal synchronized with the rotation of the optical disk, wherein the switching by the switching means is performed based on the signal. An optical disc device characterized by the above-mentioned. 5. The optical disk device according to claim 1, wherein the switching unit performs switching based on address information reproduced from a groove wobbled at a predetermined frequency on the optical disk. An optical disc device characterized by the above-mentioned. 6. The optical disk device according to claim 1, wherein the switching is performed by the switching unit based on address information reproduced from a pit address portion on which the address information on the optical disk is recorded. An optical disc device characterized by the above-mentioned.