JP2003157554A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more stably perform tracking servo control in the amplitude adjustment of a tracking error signal of an optical disk device by eliminating the error of amplitude adjustment in the case when the frequency of the tracking error signal becomes higher and its intensity becomes weaker in an optical disk having a large excitation or the eccentric component. SOLUTION: Between a received light signal amplification circuit 21 and a tracking error signal producing circuit 22, there are provided: an anti-aliasing filer 28 for receiving an output signal of the received light signal amplification circuit 21 to remove the frequency component >=1/2 of a sampling frequency of an analog-digital converter 29; and the analog-digital converter 29 for converting this output signal to a digital signal and outputting the resultant signal to a tracking error signal producing circuit 22. The input signal of a gain adjusting circuit 27 for variably controlling the amplification factor of a gain amplifier 23 is made to be an output signal of the gain amplifier 23 before being deteriorated by a low-pass filter 24.

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 information on an optical disc having concentric or spiral information tracks.

[0002]

2. Description of the Related Art In recent years, CD (Compact Disc) and MD (Mi
ni discs), DVDs (Digital Versatile Discs), and the like, have developed optical disc devices that record or reproduce information on or from optical discs having concentric or spiral information tracks.

In general, an optical disc apparatus irradiates a disc-shaped optical disc with laser light to read information from reflected light, a traverse motor for moving the optical pickup in the radial direction of the optical disc, and a spindle motor for rotating the optical disc. Etc.

The optical pickup includes a light source which emits a laser beam, an objective lens supported by a spring so as to be movable in the rotation axis direction and the radial direction of the optical disk, and the objective lens which is moved in the rotation axis direction and the radial direction. And an optical detector that splits the reflected light and converts it into an electric signal.

In such an optical disc apparatus, the data recorded on the information track on the optical disc is reproduced by simultaneously performing the focus servo and the tracking servo while rotating the optical disc. The focus servo moves the objective lens in the vertical direction with respect to the optical disc to control the focus point on the reflection surface of the optical disc. The tracking servo is performed after the focus servo is turned on, and the objective lens is moved in the radial direction of the optical disc so that the light spot follows the information track.

When the focus servo is on, the photodetector converts a signal for generating a tracking error signal indicating a displacement between the position of the light spot and the information track into an electric signal.

FIG. 6 shows an example of the waveform of the tracking error signal. In FIG. 6, the vertical axis represents the output value of the tracking error signal, and the horizontal axis represents the relative position of the light spot and the information track. The tracking error signal represents the amount of positional deviation between the light spot and the information track, and a sinusoidal signal of one cycle is output every time the light spot passes through the information track by one track. When the signal is at the zero level, the light spot is located on the information track, which means the so-called tracking-on state. When the signal is at zero level, it may be in the upper right or in the lower right, but when the light spot is located on the information track, it is only one of them. Depending on the characteristics of the optical pickup and the relative movement direction of the light spot and the information track, which of the zero point at the upper right and the lower right becomes the on-track point. FIG. 6 shows an example in which the upper right corner is on track.

The tracking servo controls to move the objective lens in the radial direction of the optical disk so that the tracking error signal becomes zero. FIG. 7 is an example of the waveform of the tracking error signal for one track. One cycle of the tracking error signal represents one track interval. Therefore, as shown by the solid line in FIG. 7, the amplitude from the minimum value of the tracking error signal to the maximum value via the on-track point is
It represents 1/2 of the track interval. For example, the amplitude of the tracking error signal is TEpp [V] and the track interval is TP.
If [m], the error amount ΔTP0 per unit amplitude of the tracking error signal is represented by ΔTP0 = TP / (2 · TEpp) [m / V] (1).

The amplitude of the tracking error signal is determined by the intensity of the reflected light from the optical disk, the amplification factor of the preamplifier that converts the current signal from the photodetector into a voltage, and the like. Therefore, the amplitude of the tracking error signal is not constant due to variations in the reflectance of the optical disc.

Here, for example, when the amplitude of the tracking error signal is very small, the error amount per unit amplitude represented by the tracking error signal becomes very large according to the equation (1). That is, when the tracking servo is controlled using this signal, the accuracy is rough and the control may be unstable.

From these things, it is necessary to adjust the amplitude of the tracking error signal so as to have an appropriate magnitude.

A conventional optical disk device will be described below with reference to the drawings. FIG. 5 is a block diagram showing the configuration of a conventional optical disc device.

As shown in FIG. 5, the conventional optical disc apparatus includes an optical pickup 11 and a received light signal amplification circuit 21.
A tracking error signal generation circuit 22, a gain amplifier 23, a low pass filter 24, a switch 25,
Tracking loop filter 26 and gain adjustment circuit 2
7, analog-digital converter 29, and digital-analog converters 30 and 32.

The optical pickup 11 is a light collecting means, and collects the light from the light source on the optical disk 1 having the information track of the concentric circle shape or the spiral shape.
2, a tracking actuator 13 for moving the objective lens 12 in the radial direction of the optical disc 1, and a photodetector 14 for converting the reflected light from the optical disc 1 into an electric signal.

The received light signal amplification circuit 21 converts the current output from the photodetector 14 into a voltage and amplifies it.

The tracking error signal generation circuit 22 generates a tracking error signal a indicating the positional deviation between the light spot irradiated on the optical disc 1 and the information track in the optical disc 1 from the input signal.

The gain amplifier 23 outputs a signal b obtained by amplifying the tracking error signal a. This amplification factor is variable.

The low-pass filter 24 is the gain amplifier 2
The noise on the high frequency component of the output signal b of No. 3 is removed and output.

The switch 25 is a switch for switching on / off of the tracking servo control according to an instruction from a control means (not shown).

The tracking loop filter 26 uses the output signal c of the low-pass filter 24 when the switch 25 is on to drive the tracking actuator 13 so that the light spot follows the information track on the optical disk 1. It is a tracking servo means for generating a signal.

The gain adjusting circuit 27 variably controls the amplification factor of the gain amplifier 23 so that the amplitude value of the input signal substantially matches the reference amplitude value. This gain adjustment circuit 27
A signal c obtained by digitally converting the output signal of the low-pass filter 24 is input to the.

The analog-digital converter 29 is provided after the low-pass filter 24 and converts the output signal of the low-pass filter 24 from an analog signal to a digital signal.

The digital-analog converter 30 is provided after the tracking loop filter 26, converts the output signal of the tracking loop filter 26 from a digital signal into an analog signal, and inputs it to the tracking actuator 13 in the optical pickup 11.

The digital-analog converter 32 converts the amplification factor, which is the adjustment result of the gain adjustment circuit 27, from a digital signal to an analog signal. The amplification factor converted into the analog signal is input to the gain amplifier 23.

The conventional amplitude adjustment operation of the tracking error signal will be described below.

When the focus servo is turned on, the photodetector 14 converts the reflected light from the optical disk into an electric signal and sends it to the received light signal amplification circuit 21. The light reception signal amplification circuit 21 which receives the electric signal which is a current converts the voltage and amplifies it by a fixed factor. At this time, the amplification factor of the received light signal amplification circuit 21 is a constant value determined by the characteristics of the optical pickup and the reflectance of the optical disc, for example. The tracking error signal generation circuit 22 receives the output signal from the received light signal amplification circuit 21, generates a tracking error signal a, and outputs it.
The gain amplifier 23 amplifies the tracking error signal a and outputs the tracking error signal b. The low pass filter 24 receives the tracking error signal b and outputs a signal from which noise components of a certain frequency or higher are removed. Upon receiving the signal, the analog-digital converter 29 converts the signal into a digital signal and outputs the tracking error signal c. When the switch 25 is open and the tracking servo is off, the tracking error signal a is a sinusoidal signal as shown in FIG.

When the gain adjusting circuit 27 receives an instruction from the control means (not shown) to adjust the amplitude of the tracking error signal, the gain adjusting circuit 27 first measures the amplitude of the tracking error signal c for a certain period of time and obtains its average amplitude value. Next, the amplification factor is calculated from the ratio of the measured average amplitude value to the reference amplitude value so that the amplitude of the output signal c of the low pass filter 24 becomes the reference amplitude value, and the gain amplifier 23 is instructed.
For example, when the reference amplitude value is N, the average amplitude value which is the measurement result is TC, and the amplification factor of the gain amplifier 23 at the time of measurement is G0, the amplification factor GC is as follows: GC = N / TC × G0 (2) Become.

The gain adjusting circuit 27 converts the amplification factor GC thus calculated into an analog signal by the digital-analog converter 32, reflects it in the gain amplifier 23, and finishes the adjustment. Also, in this way, the gain amplifier 2
There is also a method of improving the accuracy by reflecting the amplification factor in 3 and then performing the same adjustment processing a plurality of times.

[0029]

The most important thing in such a gain adjusting method is to accurately measure the amplitude of the tracking error signal.

During the gain adjustment, the objective lens may momentarily move at high speed due to external vibration. Then, the radial relative velocity of the light spot with respect to the information track on the optical disc temporarily increases, and the frequency of the tracking error signal a increases. Further, in the case of an optical disc having a large eccentricity component, the number of tracks traversed by the optical spot increases when the optical disc makes one rotation. Therefore, the radial relative velocity of the information track with respect to the light spot increases, and the frequency of the tracking error signal a increases.

When the frequency of the tracking error signal a becomes high in this way, the amplitude of the output signal c of the low pass filter 24 having a cutoff frequency characteristic of a relatively low frequency may be attenuated.

When the gain adjustment is performed when the signal c is temporarily attenuated with respect to the signal b for the above reason, the gain adjustment circuit 27 performs the gain adjustment on the basis of the signal c. It will be adjusted. That is, since the gain adjustment processing is performed on the signal c whose amplitude is attenuated, the adjustment result has a larger amplification factor than the normal value.

The present invention provides an optical disc device which eliminates the above-mentioned error in gain adjustment, more accurately adjusts the amplitude of a tracking error signal, and can more stably cause an optical spot to follow an information track. The purpose is.

[0034]

In order to achieve the above object, an optical disk device according to a first aspect of the present invention is a light collecting means for collecting light from a light source as a light spot on the optical disk, and an optical disk from the optical disk. A photodetector for converting the reflected light into a current, an optical pickup having a tracking actuator for moving the condensing means in the radial direction of the optical disc, a light receiving signal amplifying circuit for converting the current output by the photodetector into a voltage, and amplifying the voltage, Tracking error signal generating means for generating a tracking error signal indicating a positional deviation in the radial direction between the light spot and the information track on the optical disc, based on the output signal of the received light signal amplification circuit;
A gain amplifier with a variable amplification factor that amplifies the tracking error signal, a low-pass filter that removes high-frequency noise components of the output signal of the gain amplifier, and an optical spot that follows the information track based on the output signal of the low-pass filter. Tracking servo means for generating a servo drive signal for driving the tracking actuator and the output signal of the gain amplifier are input to obtain the amplitude value, and the amplification factor of the gain amplifier is adjusted so that the amplitude value substantially matches the reference amplitude value. And a gain adjusting means for variably controlling.

According to this structure, even if the output signal of the low-pass filter is attenuated due to the fact that the tracking error signal temporarily becomes a high frequency due to an external vibration or an optical disc having a large eccentricity component, the gain is increased. Since the input signal of the gain adjustment means that variably controls the amplification factor of the amplifier is the output signal of the gain amplifier before being attenuated by the low-pass filter, the amplitude of the tracking error signal is accurately adjusted, and the light spot information is more stably displayed. You can follow the track.

An optical disk device according to a second aspect of the present invention is the optical disk device according to the first aspect, wherein an analog-digital conversion circuit for converting an analog signal into a digital signal and a sampling frequency of the analog-digital conversion circuit is ½ or more. And an anti-aliasing filter for removing the frequency component of the input signal, the output signal of the received light signal amplifying circuit is input to the anti-aliasing filter, and the output signal of the anti-aliasing filter is input to the tracking error signal generation means via the analog-digital conversion circuit. It is characterized by inputting into.

With this configuration, the signal input to the gain adjusting means can be easily realized as the output signal of the gain amplifier in the preceding stage of the low-pass filter, and the anti-aliasing filter necessary for analog-digital conversion can be realized. It is possible to separate the low-pass filter required for the tracking servo. As a result, it becomes easy to finely adjust the characteristics of the low-pass filter based on the result of evaluating the stability of the tracking servo.

According to a third aspect of the present invention, in the optical disc apparatus according to the second aspect, the frequency determination is performed by detecting the frequency of the tracking error signal and determining whether the detected frequency is higher than a predetermined frequency. Means are provided, and the gain adjusting means receives the determination result of the frequency detecting circuit and ignores the input signal from the gain amplifier when the detected frequency is higher than a predetermined frequency.

According to this structure, the signal for generating the tracking error signal temporarily has a high frequency due to the external vibration or the optical disc having a large eccentricity component, and the tracking is performed by the anti-aliasing filter or the like. Even when the error signal is temporarily attenuated, the gain adjusting means does not reflect the input signal at the time of high frequency in the processing, so that the amplitude of the tracking error signal is accurately adjusted and the light spot information is more stable. You can follow the track.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) An optical disk device according to Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the optical disc device according to the first embodiment.

As shown in FIG. 1, the optical disk device according to the first embodiment includes an optical pickup 11, a received light signal amplification circuit 21, and a tracking error signal generation circuit 22.
A gain amplifier 23, a low-pass filter 24, a switch 25, a tracking loop filter 26, a gain adjusting circuit 27, and an anti-aliasing filter 28.
And an analog-digital converter 29 and a digital-analog converter 30. The configuration and operation other than the gain adjusting circuit 27, the anti-aliasing filter 28, and the analog-digital converter 29 are the same as those of the conventional example, and the description thereof will be omitted.

The gain adjusting circuit 27 variably controls the amplification factor of the gain amplifier 23 so that the amplitude value of the input signal substantially matches the reference amplitude value. This gain adjustment circuit 27
The output signal b of the gain amplifier 23 is input to the.

The anti-aliasing filter 28 receives the output signal of the received light signal amplifying circuit 21, and removes frequency components of 1/2 or more of the sampling frequency of the analog-digital converter 29. Here, the cutoff frequency of the anti-aliasing filter 28 is configured to be higher than the cutoff frequency of the low pass filter 24. That is, the cut-off frequency of the anti-aliasing filter 28 is set to the minimum high frequency necessary for analog-digital conversion, and the cut-off frequency of the low-pass filter 24 is set to the minimum low frequency necessary for tracking servo.

The analog-digital converter 29 receives the output signal of the anti-aliasing filter 28 and converts it into a digital signal. The digitally converted signal is input to the tracking error signal generation circuit 22.

Next, the operation of adjusting the amplitude of the tracking error signal in the optical disk device according to the first embodiment will be described.

When the focus servo is turned on, the photodetector 14 converts the reflected light from the optical disk into an electric signal and sends it to the received light signal amplification circuit 21. The light reception signal amplification circuit 21 which receives the electric signal which is a current converts the voltage and amplifies it by a fixed factor. At this time, the amplification factor of the received light signal amplification circuit 21 is a constant representative value determined by the characteristics of the optical pickup and the reflectance of the optical disc, for example. The anti-aliasing filter 28 receives the output signal of the received light signal amplifying circuit 21, removes a frequency component of ½ or more of the sampling frequency of the analog-digital converter 29, and inputs it to the analog-digital converter 29. Analog-to-digital converter 2
Reference numeral 9 digitally converts the input signal and outputs it to the tracking error signal generation circuit 22. The tracking error signal generation circuit 22 receives the output signal from the analog-digital converter 29 and generates and outputs the tracking error signal a. The gain amplifier 23 uses the tracking error signal a
Is amplified and a tracking error signal b is output. The low-pass filter 24 receives the tracking error signal b and outputs a signal c from which noise components of a certain frequency or higher are removed. When the switch 25 is open and the tracking servo is off, the tracking error signal a is
It has a sinusoidal signal as shown in FIG.

When the gain adjusting circuit 27 receives an instruction from the control means (not shown) to adjust the amplitude of the tracking error signal, it first measures the amplitude of the tracking error signal b for a certain period of time, and obtains its average amplitude value. Next, the amplification factor is calculated from the ratio of the measured average amplitude value to the reference amplitude value so that the amplitude of the output signal b of the gain amplifier 23 becomes the reference amplitude value, and the gain amplifier 23 is instructed. For example, the reference amplitude value is N, and the average amplitude value that is the measurement result is TB.
When the amplification factor of the gain amplifier 23 at the time of measurement is G0, the amplification factor GB is GB = N / TB × G0 (3).

The gain adjusting circuit 27 reflects the amplification factor GB calculated in this way on the gain amplifier 23 and finishes the adjustment. In addition, there is also a method of increasing the accuracy by reflecting the amplification factor in the gain amplifier 23 in this way and then performing the same adjustment processing a plurality of times.

Here, the tracking error signal b measured by the gain adjusting circuit 27 is a signal before the low pass filter 24. Therefore, even if the frequency of the tracking error signal a temporarily rises due to external vibration or an optical disc having a large eccentricity component, the tracking error signal b is not attenuated like the signal c.
Further, since the cut-off frequency of the anti-aliasing filter 28 is configured to be higher than that of the low-pass filter 24, even when the frequency of the tracking error signal becomes larger than that of the conventional example, the erroneous gain is not obtained. No adjustment will be made. As a result, the amplitude of the tracking error signal can be accurately adjusted, and the light spot can follow the information track more stably.

Further, in the optical disk device according to the first embodiment of the present invention, the low-pass filter 24 is arranged so as to be after the analog-digital converter 29. As a result, the low-pass filter 24 and the gain adjusting circuit 27 are
Can be controlled by digital signal processing, and the signal input to the gain adjusting circuit 27 can be easily configured to be the signal b in the preceding stage of the low-pass filter 24. In addition, a conventional low-pass filter is used in the first embodiment.
As described above, the anti-aliasing filter 28 necessary for analog-digital conversion and the low-pass filter 24 necessary for tracking servo can be separated. The cut-off frequency characteristic of the anti-aliasing filter 28 is
The cutoff frequency of the low-pass filter 24 is usually finely adjusted and set from the result of evaluation of the stability of the tracking servo, while it is uniquely determined according to the sampling frequency of the analog-digital converter 29.
Because of that, the anti-aliasing filter 28
It is practically advantageous to separate the low-pass filter 24 and the low-pass filter 24 from each other and to configure the low-pass filter 24 by digital processing whose characteristics are generally easy to change.

In the configuration of FIG. 1, the tracking error signal generating circuit 22 to the tracking loop filter 26
Although the processing up to the above is configured to be digitally processed, it can be arbitrarily configured to be digitally processed or analogly processed, and basically can be configured as shown in FIG. That is, even if the frequency of the tracking error signal a output from the tracking error signal generation circuit 22 is temporarily increased by setting the input signal of the gain adjustment circuit 27 to the tracking error signal b in the previous stage of the low pass filter 24. The tracking error signal b input to the gain adjusting circuit 27 is a signal c due to the influence of the low pass filter 24.
As described above, since the gain adjustment can be performed accurately without attenuation, the light spot can be made to follow the information track more stably.

(Second Embodiment) An optical disk device according to a second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram showing the configuration of the optical disc device according to the second embodiment.

As shown in FIG. 3, the optical disk device according to the second embodiment includes an optical pickup 11, a received light signal amplification circuit 21, and a tracking error signal generation circuit 22.
A gain amplifier 23, a low-pass filter 24, a switch 25, a tracking loop filter 26, a gain adjusting circuit 27, and an anti-aliasing filter 28.
An analog-digital converter 29, a digital-analog converter 30, and a frequency detection circuit 31. In addition,
The configuration and the operation other than the frequency detection circuit 31 are the same as those in FIG. 1, and the description thereof will be omitted.

The frequency detection circuit 31 includes a gain amplifier 23.
When the output signal b is received, the frequency is detected. When the detected frequency is higher than the predetermined frequency, the frequency detection circuit 3
1 instructs the gain adjusting circuit 27 not to use the amplitude measurement result. If the detected frequency is equal to or lower than the predetermined frequency, the gain adjusting circuit 27 is instructed to use the amplitude measurement result.

FIG. 4 shows an example of the waveform of the tracking error signal b when the gain is adjusted when the frequency detection circuit 31 is provided.

For example, it is assumed that the gain adjusting circuit 27 measures the amplitude and the frequency detecting circuit 31 measures the frequency for each cycle of the signal b. As shown in FIG. 4, the amplitude measurement results are A1 to A9, and the frequency detection results are f1 to f9. At this time, for example, the frequency detection results f1, f2, f
3, f8 and f9 are lower than a certain predetermined frequency f0, and f
It is assumed that 4, f5, f6 and f7 are higher than the predetermined frequency f0.

The gain adjusting circuit 27 adds the amplitude values measured for each cycle in order to obtain the average amplitude value TB. At this time, the frequency detection circuit 31 outputs the predetermined frequency f
Information about whether the frequency is lower than 0 or higher than 0 is obtained, and the measured amplitude value when the frequency is higher than f0 is calculated so as not to be added. In the case of FIG. 4, the average amplitude value TB is calculated by the following equation (4).

TB = (A1 + A2 + A3 + A8 + A9) / 5 (4) The average amplitude value TB thus calculated is output from the received light signal amplification circuit 21 due to external vibration or an optical disc with a large eccentricity component. Even if the frequency of the signal for generating the tracking error signal a is temporarily increased and the output signal of the anti-aliasing filter 28 is temporarily attenuated, the signal when the frequency is high in the gain adjustment processing is the measurement result. Is not reflected as
Prevents incorrect gain adjustment. As a result, the amplitude of the tracking error signal can be accurately adjusted, and the light spot can follow the information track more stably.

[0059]

As described above, according to the optical disk device of the present invention, the tracking error signal generating means generates the tracking error signal based on the output signal of the light receiving signal amplifier circuit, and the tracking error signal is gained. The gain is amplified by the gain amplifier whose amplification factor is variably controlled by the adjusting means, the high frequency noise component of the output signal of the gain amplifier is removed by the low pass filter, and the tracking servo means operates the tracking actuator based on the output signal of the low pass filter. In the configuration for driving, the gain adjusting means inputs the output signal of the gain amplifier, obtains its amplitude value, and variably controls the amplification factor of the gain amplifier so that the amplitude value substantially matches the reference amplitude value. There is. As a result, even if the tracking error signal temporarily becomes a high frequency and the output signal of the low-pass filter is attenuated due to external vibration or an optical disc with a large eccentricity component, the input signal of the gain adjusting means is Since the output signal of the gain amplifier before being attenuated by the low-pass filter is used, the amplitude of the tracking error signal can be accurately adjusted and the light spot can follow the information track more stably.

Further, an analog-to-digital conversion circuit for converting an analog signal into a digital signal and an anti-aliasing filter for removing a frequency component of 1/2 or more of the sampling frequency of the analog-to-digital conversion circuit are provided, and the received light signal amplification circuit The output signal is input to the anti-aliasing filter, and the output signal of the anti-aliasing filter is input to the tracking error signal generation means via the analog-digital conversion circuit, so that the signal input to the gain adjustment means is low-passed. It can be easily realized to use as the output signal of the gain amplifier in the previous stage of the filter, and it is possible to separate the anti-aliasing filter required for analog-digital conversion and the low-pass filter required for tracking servo. . As a result, it becomes easy to finely adjust the characteristics of the low-pass filter based on the result of evaluating the stability of the tracking servo.

Further, frequency determining means for detecting the frequency of the tracking error signal and determining whether or not the detected frequency is higher than a predetermined frequency is provided, and the gain adjusting means is
By receiving the judgment result of the frequency detection circuit and ignoring the input signal from the gain amplifier when the detected frequency is higher than the predetermined frequency, it is possible to use an optical disk with large external vibration or eccentricity component. Due to this, the signal for generating the tracking error signal temporarily has a high frequency, and even when the tracking error signal is temporarily attenuated by the anti-aliasing filter, etc. By not reflecting the input signal in the processing, the amplitude of the tracking error signal can be accurately adjusted and the light spot can be made to follow the information track more stably.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing another configuration example of the optical disc device according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an optical disc device according to a second embodiment of the present invention.

FIG. 4 is a waveform diagram showing an example of a tracking error signal at the time of gain adjustment in the optical disc device according to the second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional optical disc device.

FIG. 6 is a waveform diagram showing an example of a tracking error signal.

FIG. 7 is a waveform diagram showing an example of a tracking error signal for one track.

[Explanation of symbols]

1 Optical Disc 11 Optical Pickup 12 Objective Lens 13 Tracking Actuator 14 Photodetector 21 Photoreception Signal Amplifying Circuit 22 Tracking Error Signal Generating Circuit 23 Gain Amplifier 24 Low Pass Filter 25 Switch 26 Tracking Loop Filter 27 Gain Adjusting Circuit 28 Anti-Aliasing Filter 29 Analog-to-Digital Converter 30, 32 Digital-to-analog converter 31 Frequency detection circuit a Tracking error signal b output by tracking error signal generation circuit b Tracking error signal c output by gain amplifier 23 Tracking error signal output by low-pass filter 24

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5D096 RR01                 5D118 AA19 AA24 BA01 CA02 CA13                       CB03

Claims (3)

[Claims] 1. A light condensing means for condensing light from a light source as a light spot on an optical disk, a photodetector for converting reflected light from the optical disk into a current, and the light converging means in the radial direction of the optical disk. An optical pickup having a tracking actuator for converting the current output from the photodetector into a voltage,
A light receiving signal amplification circuit for amplifying, and a tracking error signal generation for generating a tracking error signal indicating a radial positional deviation between the light spot and the information track on the optical disc based on the output signal of the light receiving signal amplification circuit. Means, a gain amplifier having a variable amplification factor for amplifying the tracking error signal, a low-pass filter for removing a high frequency noise component of the output signal of the gain amplifier, and the optical spot based on the output signal of the low-pass filter. A tracking servo unit that generates a servo drive signal that drives the tracking actuator so as to follow the information track, and an output signal of the gain amplifier are input to obtain an amplitude value thereof, and the amplitude value is approximately the reference amplitude value. Gain adjustment that variably controls the amplification factor of the gain amplifier so that they match. Optical disc apparatus that includes a stage. 2. An analog-to-digital conversion circuit for converting an analog signal into a digital signal, and an anti-aliasing filter for removing frequency components of 1/2 or more of the sampling frequency of the analog-to-digital conversion circuit are provided, and the received light signal amplification An output signal of a circuit is input to the anti-aliasing filter, and an output signal of the anti-aliasing filter is input to the tracking error signal generating means via the analog-digital conversion circuit. 1. The optical disk device described in 1. 3. A frequency determination means for detecting the frequency of the tracking error signal and determining whether or not the detected frequency is higher than a predetermined frequency is provided, and the gain adjustment means determines the determination result of the frequency detection circuit. The optical disk device according to claim 2, wherein the input signal from the gain amplifier when the detected frequency is higher than a predetermined frequency is ignored.