JP2878974B2 - Optical disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus for reading and reproducing signals recorded on tracks on an optical disk.

[0002]

2. Description of the Related Art Optical discs are widely used as consumer media in the form of compact discs (hereinafter abbreviated as "CDs") and laser discs as audio-video package media. An optical disk has an excellent feature that a signal is read out in a non-contact manner, so that there is no deterioration of the disk due to signal reproduction.

Referring to the drawings, the balance adjustment of an optical servo system of a conventional optical disk reproducing apparatus will be described with reference to the focus astigma method and the tracking three beam method.
This will be described by taking the D player as an example. FIG. 6 is a block diagram showing an optical servo system of a conventional CD player.
In FIG. 6, reference numeral 1 denotes a photodetector having regions a to f, a, b, c, and d denote regions for generating a high-frequency signal and a focus error signal, and e and f denote regions for generating a tracking error signal. 11, 12, 21, and 22 are I
-V converters (current-voltage converters), 13 and 23 are balance control amplifiers, 14 and 24 are subtractors, 15 is a focus loop filter, 25 is a tracking loop filter, 16 and 26 are drivers, 17 is a focus actuator, 27 is a tracking actuator, 1
8 and 28 are disturbance generators, 19 and 29 are switches, and 31 is an adder.

A method of adjusting the balance of the optical servo system of the CD player configured as described above will be described below. A laser beam emitted from a laser (not shown) also passes through an optical lens block (not shown), and is irradiated so as to be focused on a signal surface of a CD (not shown), and recorded on the CD. Modulated by the digital signal being processed. At this time, the state of the reflected light is a characteristic state depending on the shape of the beam spot on the signal surface of the CD. The reflected light passes through the optical lens block again and is applied to the photodetector 1.

The output currents from the regions a and c and the output currents from the regions b and d on the photodetector 1 are added, and then IV-converted by IV converters 11 and 12. IV converter 11,
Both outputs of the amplifier 12 are input to a balance control amplifier 13, and the balance is controlled as described later. The output of the balance control amplifier 13 is input to the subtractor 14, and the output of the subtractor 14 becomes the focus error signal FE. The focus error signal FE is input to the focus loop filter 15, undergoes phase compensation and low-frequency compensation, and is then input to the driver 16. The output of the driver 16 is connected to a focus actuator 17, and the focus actuator 17 operates to control the position of the optical lens block in the optical axis direction so as to keep the focus of the laser beam on the signal surface of the CD.

On the other hand, regions e and f on photodetector 1
Output currents are subjected to IV conversion by the IV converters 21 and 22, respectively. The outputs of the IV converters 21 and 22 are both input to the balance control amplifier 23, and the balance is controlled as described later. The output of the balance control amplifier 23 is input to a subtractor 24,
4 becomes the tracking error signal TE. The tracking error signal TE is the tracking loop filter 2
5, and after being subjected to phase compensation and low-frequency compensation, is inputted to the driver 26. The output of the driver 26 is connected to a tracking actuator 27. The tracking actuator 27 controls the position of the optical lens block in the radial direction of the CD, and operates to keep the beam spot on the signal track of the CD.

The outputs of the IV converters 11 and 12 are also input to an adder 31. The output of the adder 31 becomes the high frequency signal RF. The balance adjustment of the focus system can be performed by closing the switch 19, applying a disturbance of a predetermined frequency to the focus servo loop from the disturbance generator 18, and observing how the envelope of the high-frequency signal RF is modulated by the disturbance. it can. This is shown in FIG. In FIG. 7, (A) is a schematic diagram showing a disturbance, and (B) to (F) are schematic diagrams showing various states of a high-frequency signal RF. As shown in FIG. 7D, in a balanced state, the envelope on the dark level side of the high-frequency signal RF is modulated at twice the frequency of the disturbance, and the maximum degree of modulation depends on the polarity of the disturbance. Equal. However, when the balance slightly deviates, the degree of modulation differs depending on the polarity of the disturbance as shown in FIGS. When the balance further deviates, the envelope on the dark level side of the high-frequency signal RF is modulated at the same frequency as the disturbance, as shown in FIGS. 7B and 7F. Therefore, if the balance control amplifier 13 is controlled so as to have a waveform as shown in FIG. 7D while monitoring the high frequency signal RF, the balance of the focus system can be adjusted.

FIG. 8 shows a circuit example of a balance control amplifier 13 using an operational amplifier and a semi-fixed resistor. FIG.
In the figure, 71 and 72 are operational amplifiers, 73 is a semi-fixed resistor, 74 to 81 are resistors, IN ₁ and IN ₂ are input terminals, O
UT ₁ and OUT ₂ are output terminals. Note that the balance control amplifier 23 can be similarly configured. The balance adjustment of the tracking system can be performed in exactly the same manner. That is, the operation can be performed by closing the switch 29, applying a disturbance of a predetermined frequency to the tracking servo loop from the disturbance generator 28, and observing a state where the dark level envelope of the high-frequency signal RF is modulated by the disturbance. . The situation is the same as in FIG. FIG.
As shown in (D), when the balance is in place,
The envelope on the dark level side of the high-frequency signal RF is modulated at twice the frequency of the disturbance, and the degree of modulation is equal regardless of the polarity of the disturbance. However, when the balance is slightly deviated, the degree of modulation differs depending on the polarity of the disturbance as shown in FIGS. When the balance is further shifted, FIG.
(B) As shown in (F), the envelope on the dark level side of the high-frequency signal RF is modulated at the same frequency as the disturbance. Therefore, while monitoring the high frequency signal RF,
If the balance control amplifier 23 is controlled so as to have a waveform as shown in FIG. 7D, the balance of the tracking system can be adjusted.

[0009]

However, the above-mentioned conventional method for adjusting the balance of the optical servo system of the optical disk reproducing apparatus is good for a person to visually adjust, but unsuitable for automation. For example, if an algorithm is adopted in which the maximum degree of modulation of the envelope of a high-frequency signal is matched between a positive section and a negative section in order to automate, as shown in FIGS. 7 (C), (D), and (E). While the balance deviation is small, the point at which the modulation depth becomes maximum is near the maximum of the absolute value of the disturbance, and adjustment is possible.
As shown in FIGS. 7B and 7F, when the deviation is large, the modulation degree becomes maximum near the amplitude of the disturbance near zero, and the adjustment becomes unstable or the convergence of the adjustment becomes slow. Was.

In addition, the modulation degree of the envelope of the high-frequency signal at the point where the absolute value of the disturbance becomes maximum is matched.
It must be ensured that the degree of modulation of the envelope of the high-frequency signal also becomes maximum at the point where the absolute value of the disturbance becomes maximum. However, a phase rotation always occurs in a loop filter or a detection circuit, and it is not easy to compensate for the phase rotation, and it is impossible to cope with an arbitrary system.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described conventional problems, and has as its object to provide an optical disk reproducing apparatus capable of easily and accurately adjusting the balance of an optical servo system automatically.

[0012]

According to a first aspect of the present invention, there is provided an optical disk reproducing apparatus comprising: a laser serving as a light source; a laser beam emitted from the laser being focused on the optical disk; a signal recorded on the optical disk; An optical lens block for obtaining reflected light according to the above, a focus actuator for moving the optical lens block in the optical axis direction, a photodetector comprising a plurality of areas for detecting reflected light from the optical disc, and a photodetector A focus error detector that obtains a focus error signal by performing arithmetic processing after electrically adjusting the balance of outputs from a plurality of areas, and recording on an optical disc by performing arithmetic processing on outputs from a plurality of areas of a photodetector A high-frequency signal detector for obtaining a high-frequency signal corresponding to the detected signal, and a focus error signal output from the focus error detector. A filter amplifier performing filtering, an optical disc reproducing apparatus having a focus servo loop for amplifying the output of the filter amplifier comprising a driver for driving the focus actuator, a disturbance generator for injecting a disturbance to the focus servo loop When,
A detector for detecting an envelope of a high-frequency signal which is an output of the high-frequency signal detector; a first maximum value detecting means for detecting a maximum value of an output of the detector during a first predetermined period; First minimum value detection means for detecting the minimum value of the output of the detector, second maximum value detection means for detecting the maximum value of the output of the detector during a second predetermined period,
A second minimum value detection means for detecting a minimum value of the output of the detector in a second predetermined period; a sum of an output of the first maximum value detection means and an output of the first minimum value detection means; An error signal generator that obtains a difference between the output of the maximum value detection means and the sum of the outputs of the second minimum value detection means and outputs the error signal as an error signal; In this case, the balance of the focus error detector is adjusted.

According to a second aspect of the present invention, there is provided an optical disk reproducing apparatus, comprising: a laser serving as a light source; a laser beam emitted from the laser being focused on the optical disk; and reflected light corresponding to a signal recorded on the optical disk and a beam spot state. An optical lens block for obtaining the optical lens block, a tracking actuator for moving the optical lens block in the radial direction of the disc, a photodetector comprising a plurality of areas for detecting light reflected from the optical disc, and a plurality of areas of the photodetector. A tracking error detector that obtains a tracking error signal by performing arithmetic processing after electrically adjusting the output balance, and an arithmetic processing of outputs from multiple areas of the photodetector to correspond to the signal recorded on the optical disk High-frequency signal detector that obtains a high-frequency signal and tracking error that is the output of the tracking error detector An optical disc reproducing apparatus provided with a tracking servo loop including a filter amplifier for filtering a signal and a driver for amplifying an output of the filter amplifier and driving a tracking actuator, wherein a disturbance generator injects disturbance into the tracking servo loop. A detector for detecting an envelope of a high-frequency signal which is an output of the high-frequency signal detector; a first maximum value detecting means for detecting a maximum value of an output of the detector during a first predetermined period; First minimum value detection means for detecting the minimum value of the output of the detector during the period, second maximum value detection means for detecting the maximum value of the output of the detector during the second predetermined period, and second predetermined value. Second minimum value detection means for detecting the minimum value of the output of the detector during the period, output of the first maximum value detection means and detection of the first minimum value An error signal generator for obtaining a difference between the sum of the outputs of the stages and the sum of the output of the second maximum value detection means and the sum of the outputs of the second minimum value detection means and outputting the difference as an error signal; The balance of the tracking error detector is adjusted so that the error signal output from the tracking error detector becomes substantially zero.

According to a third aspect of the present invention, in the optical disc reproducing apparatus according to the first or second aspect, the disturbance generator generates a substantially sinusoidal disturbance. An optical disk reproducing apparatus according to claim 4 is:
3. The optical disc reproducing apparatus according to claim 1, wherein
The disturbance generator is characterized in that a disturbance having a substantially triangular waveform is generated.

According to a fifth aspect of the present invention, in the optical disk reproducing apparatus according to the first or second aspect, the detector extracts a signal component of the highest frequency included in the high-frequency signal output from the high-frequency signal detector. It is characterized in that the envelope is detected.

[0016]

According to the configuration of the present invention, a disturbance generator for injecting disturbance into the focus servo loop, a detector for detecting an envelope of a high-frequency signal output from the high-frequency signal detector, and a detection for a first predetermined period First maximum value detection means for detecting the maximum value of the output of the detector, first minimum value detection means for detecting the minimum value of the output of the detector in a first predetermined period, and detection in a second predetermined period Second maximum value detection means for detecting the maximum value of the output of the detector, second minimum value detection means for detecting the minimum value of the output of the detector during a second predetermined period, and first maximum value detection means Signal generation for obtaining a difference between the sum of the output of the first and second minimum value detection means and the sum of the output of the second maximum value detection means and the output of the second minimum value detection means and outputting the difference as an error signal And the output of the error signal generator That by the error signal is to adjust the balance of the focus error detector so as to be substantially zero, it is possible to adjust the balance of the optical servo system of a focus easily and accurately automatically.

Also, a disturbance generator for injecting disturbance into the tracking servo loop, a detector for detecting an envelope of a high-frequency signal output from the high-frequency signal detector, and a maximum value of the output of the detector during a first predetermined period First to detect
Maximum value detection means, first minimum value detection means for detecting the minimum value of the output of the detector during a first predetermined period, and second value detection means.
Second maximum value detection means for detecting the maximum value of the output of the detector during the predetermined period, second minimum value detection means for detecting the minimum value of the output of the detector during the second predetermined period, The difference between the sum of the output of the maximum value detection means and the output of the first minimum value detection means and the sum of the output of the second maximum value detection means and the output of the second minimum value detection means is determined as an error signal. By providing an error signal generator to output, by adjusting the balance of the tracking error detector so that the error signal output from the error signal generator is substantially zero,
The balance adjustment of the tracking optical servo system can be easily and accurately performed automatically.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disk reproducing apparatus according to the present invention will be described in detail with reference to the drawings, taking a CD player as an example. FIG. 1 is a block diagram showing an optical servo system of a CD player according to an embodiment of the present invention.

In FIG. 1, the same components as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, reference numerals 13a and 23a denote balance control amplifiers, 3
2 is a detector, 33 is a switch, 34 and 36 are maximum value detectors (first and second maximum value detection means), and 35 and 37 are minimum value detectors (first and second minimum value detection means). , 38,39
Is an adder, 40 is a subtractor, 41 is an error signal generator, 42
Denotes a focus error detector, 43 denotes a tracking error detector, the photodetector 1 corresponds to a photodetector, the focus loop filter 15 corresponds to a filter amplifier, the tracking loop filter 25 corresponds to a filter amplifier, and the adder 31 corresponds to a high frequency signal detector.

The operation of the optical disk reproducing apparatus configured as described above will be described focusing on differences from the conventional example of FIG. The detector 32 detects the dark level side of the high-frequency signal RF. The output (envelope) of the detector 32 is input to the switch 33. The switch 33 divides the output of the detector 32 into two periods on the time axis according to, for example, the polarity of the disturbance generated by the disturbance generator 18. When the disturbance is positive, the output of the switch 33 is the maximum value detector 3
4, input to the minimum value detector 35, where the maximum value and the minimum value are respectively detected. When the disturbance is negative, the output of the switch 33 is input to the maximum value detector 36 and the minimum value detector 37, and the maximum value and the minimum value are detected.
The output of the maximum value detector 34 and the output of the minimum value detector 35 are added by an adder 38. The output of the maximum value detector 36 and the output of the minimum value detector 37 are added by an adder 39. The output of the adder 38 and the output of the adder 39 are subtracted by a subtractor 40. The output of the subtractor 40 becomes an error signal ERR for focus balance adjustment.

FIG. 2 shows the amount of balance deviation and the high-frequency signal RF.
(A) is a disturbance, and (B) to (F) are diagrams showing dark-side envelopes of high-frequency signals RF having different balance shift amounts. is there. The maximum value (output of the maximum value detector 34) of the envelope of the high-frequency signal RF during the period in which the disturbance is positive is MAX1, the minimum value (output of the minimum value detector 35) is MIN1, and the envelope of the high-frequency signal RF during the period in which the disturbance is negative. Assuming that the maximum value (output of the maximum value detector 36) of the envelope is MAX2 and the minimum value (output of the minimum value detector 37) is MIN2, the error signal ERR is ERR = MAX1 + MIN1-MAX2-MIN2. FIG. 2B shows a state in which the balance is greatly shifted, and since MIN1 = MAX2, ERR = MAX1-MIN2. FIG. 2C shows a state in which the balance is slightly shifted, and since MIN1 = MIN2, ERR = MAX1-MAX2. FIG. 2D shows a state in which the balance is maintained, and MAX1 = MAX2 MIN1 = MIN2, so that ERR = 0. FIG. 2E shows a state in which the balance is slightly shifted in the opposite direction to FIG. 2C, and since MIN1 = MIN2, ERR = MAX1-MAX2. FIG. 2F shows a state in which the balance is largely shifted in the opposite direction to that of FIG. 2B. Since MAX1 = MIN2, ERR = MIN1-MAX2.

FIG. 3 shows the error signal ERR and the high-frequency signal R
9 shows the relationship between the jitters of F. As shown in FIG. 3, the point where the error signal ERR becomes zero and the high-frequency signal RF
(The point where the eye pattern of the high-frequency signal RF is the most open, that is, the point where the balance adjustment is the best) almost coincides. Therefore, by giving feedback so that the obtained error signal ERR becomes zero and controlling the balance control amplifier 13a, the focus balance can be easily and accurately adjusted automatically.

The disturbance injection point may be located immediately before the focus loop filter 15 instead of immediately before the driver 16 as shown in FIG. However, in this case, since the phase of the injected disturbance and the phase of the modulation waveform of the envelope of the high-frequency signal RF are shifted by the focus loop filter 15, it is divided into two periods according to the polarity of the focus error signal FE. It is desirable to determine the value and the minimum value. At this time, since a DC offset generated in a focus servo loop is often added to the focus error signal FE, it is better to determine the polarity of the focus error signal FE in a state where the offset is canceled.

The waveform of the disturbance is desirably sinusoidal or triangular in order to detect the maximum value and the minimum value of the envelope of the high-frequency signal RF in each period as shown in FIG. Since the degree of modulation of the high-frequency signal RF due to the balance shift appears more remarkably with a higher frequency component, the high-frequency signal RF that has passed through a band-pass filter that passes the highest frequency component of the high-frequency signal RF may be detected. Good.

The output of the detector 32 can be A / D converted using an A / D converter, input to a microcomputer, and digitally processed. FIG. 4 shows a flowchart of an example of an algorithm for that purpose. Disturbance is generated by D / A using the same microcomputer.
When using a converter, the sign of the disturbance can be managed by microcomputer software, and a comparator and an A / D converter for discriminating the sign of the disturbance are not required, and can be realized by a simple algorithm as shown in FIG. It is possible.

First, in step S1, as an initial setting for obtaining the maximum value and the minimum value, A1 is set in MAX1 and MAX2.
The minimum value min of the output of the / D converter is defined as MIN1, M
The maximum value max of the A / D converter is set to IN2.
If the disturbance generated in step S2 is 0 or more, the process jumps to step S3, and if less than 0, the process jumps to step S7.

Steps S3 to S6 are processing when the disturbance is 0 or more. In step S3, a value obtained by A / D converting the level of the envelope of the high-frequency signal RF (hereinafter referred to as “RFE”)
Is read, and if the RFE is greater than MAX1, the value of RFE is substituted for MAX1 (step S4), and the process goes to step S5. If the value of RFE is not larger than MAX1, the process directly proceeds to step S5. In step S5, if RFE is smaller than MIN1, the value of RFE is set to MIN1.
(Step S6), and then go to Step S11.
If the value of RFE is not smaller than MIN1, the process directly proceeds to step S11.

Steps S7 to S10 are processing when the disturbance is less than 0, and the contents are the same as steps S3 to S6.
In step S7, the RFE is read, and the RFE is set to MAX2.
If it is larger, the value of RFE is substituted for MAX2 (step S8), and the procedure goes to step S9. RFE value is MAX
If it is not larger than 2, the process directly proceeds to step S9. In step S9, if RFE is smaller than MIN2, RFE
Is substituted for MIN2 (step 10), and the procedure goes to step S11. If the value of RFE is not smaller than MIN2, the process directly proceeds to step S11.

Step S11 is a timeout process.
MAX1, MAX2, MIN1, MI after a predetermined time has passed
If it is determined that the measurement of N2 has been completed, step S12 is performed.
Go to If the predetermined time has not elapsed, step S2
Return to and continue the measurement. In step S12, the error signal ERR is calculated. In step S13, a balance correction output corresponding to the error signal ERR is output, and the balance control amplifier is controlled.

As described above, the error signal measurement (step S
1 to S12), balance correction output (step S1)
3), convergence determination, until it is determined that convergence is established
The algorithm is repeated. The convergence determination condition is that the absolute value of the amount of change in the balance correction output from the previous value is twice or less and equal to or less than a predetermined value.

FIG. 5 shows a configuration example of the balance control amplifier 13a in this embodiment. 5, 51 is a differential amplifier, 52 and 53 are analog multipliers, 54 is a microcomputer, 55 is a D / A converter, IN ₁ and IN ₂ are input terminals, OUT ₁ and OUT _2.
Is an output terminal. This balance control amplifier 1
3a shows a differential amplifier 51 and two analog multipliers 52,
The balance correction is performed by the output of the D / A converter 55 set by the microcomputer 54. Note that the balance control amplifier 23a can be configured similarly to the balance control amplifier 13a.

The tracking balance adjustment can be easily and accurately performed automatically in the same manner.
As shown in FIG. 1, when a disturbance is injected immediately before the driver 26, the switch 33 changes the output of the detector 32 on the time axis according to the polarity of the disturbance generated by the disturbance generator 28. Is divided into two periods, and the maximum value and the minimum value in each period are obtained. When a disturbance is injected immediately before the tracking loop filter 25, the phase of the injected disturbance and the high-frequency signal are detected by the tracking loop filter 25. Since the phase of the modulation waveform of the RF envelope is shifted, it is desirable to divide the period into two periods according to the polarity of the tracking error signal TE and obtain the maximum value and the minimum value in each period. At this time, since the tracking error signal TE often includes a DC offset generated in the tracking servo loop, it is better to determine the polarity of the tracking error signal TE in a state where the offset is canceled.

Also, like the disturbance generator 18, the waveform of the disturbance generated by the disturbance generator 28 has a sine wave because it is necessary to detect the maximum value and the minimum value of the envelope of the high-frequency signal RF in each period as shown in FIG. Desirably, the shape is wavy or triangular.

[0034]

As described above, the present invention provides a disturbance generator for injecting disturbance into a focus servo loop, a detector for detecting an envelope of a high-frequency signal output from a high-frequency signal detector, and a first predetermined period. , First maximum value detection means for detecting the maximum value of the output of the detector in the above, first minimum value detection means for detecting the minimum value of the output of the detector during a first predetermined period, and a second predetermined period A second maximum value detecting means for detecting a maximum value of the output of the detector in the above, a second minimum value detecting means for detecting a minimum value of the output of the detector in a second predetermined period, and a first maximum value An error which is obtained by calculating a difference between the sum of the output of the detection means and the output of the first minimum value detection means and the sum of the output of the second maximum value detection means and the output of the second minimum value detection means and outputs the difference as an error signal. A signal generator and an error signal generator Error signal output by the by which to perform the balance adjustment of the focus error detector so as to be substantially zero, it is possible to perform the optical servo system balancing the focus easily and accurately automatically.

Further, a disturbance generator for injecting disturbance into the tracking servo loop, a detector for detecting the envelope of the high-frequency signal output from the high-frequency signal detector, and a maximum value of the output of the detector during the first predetermined period First to detect
Maximum value detection means, first minimum value detection means for detecting the minimum value of the output of the detector during a first predetermined period, and second value detection means.
Second maximum value detection means for detecting the maximum value of the output of the detector during the predetermined period, second minimum value detection means for detecting the minimum value of the output of the detector during the second predetermined period, The difference between the sum of the output of the maximum value detection means and the output of the first minimum value detection means and the sum of the output of the second maximum value detection means and the output of the second minimum value detection means is determined as an error signal. By providing an error signal generator to output, by adjusting the balance of the tracking error detector so that the error signal output from the error signal generator is substantially zero,
The balance adjustment of the tracking optical servo system can be easily and accurately performed automatically.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical servo system of a CD player according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing how an error signal is calculated from a balance shift amount and an envelope of a high-frequency signal according to an embodiment of the present invention.

FIG. 3 is a conceptual diagram showing a relationship between an error signal and a jitter of a high-frequency signal in one embodiment of the present invention.

FIG. 4 is a flowchart when an error signal generator according to an embodiment of the present invention is realized by software of a microcomputer;

FIG. 5 is a configuration diagram of a balance control amplifier according to an embodiment of the present invention.

FIG. 6 is a block diagram of an optical servo system of a conventional CD player.

FIG. 7 is a schematic diagram showing a state of a balance shift amount, a disturbance, and a high-frequency signal in a conventional example.

FIG. 8 is a circuit diagram of an example of a balance control amplifier in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photodetector 11, 12, 21, 22 IV converter 13a, 23a Balance control amplifier 14, 24, 40 Subtractor 15 Focus loop filter 16, 26 Driver 17 Focus actuator 18, 28 Disturbance generator 19, 29, 33 Switch Reference Signs List 25 tracking loop filter 27 tracking actuator 31, 38, 39 adder 32 detector 34, 36 maximum value detector 35, 37 minimum value detector 41 error signal generator 42 focus error detector 43 tracking error detector

Claims (5)

(57) [Claims] 1. A laser as a light source, and an optical lens for focusing a laser beam emitted from the laser on an optical disc and obtaining reflected light corresponding to a signal recorded on the optical disc and a beam spot state. A block, a focus actuator for moving the optical lens block in the optical axis direction, a photodetector comprising a plurality of areas for detecting reflected light from the optical disc, and a balance between outputs from the plurality of areas of the photodetector. A focus error detector that obtains a focus error signal by performing arithmetic processing after electrically adjusting the frequency, and a high frequency corresponding to a signal recorded on the optical disk by performing arithmetic processing on outputs from a plurality of regions of the photodetector. A high-frequency signal detector for obtaining a signal; and filtering the focus error signal output from the focus error detector. A filter amplifier that performs the output of the filter amplifier amplifies an optical disc reproducing apparatus having a focus servo loop comprising a driver for driving the focus actuator, a disturbance generator for injecting a disturbance to the focus servo loop A detector for detecting an envelope of a high-frequency signal output from the high-frequency signal detector; a first maximum value detecting means for detecting a maximum value of an output of the detector during a first predetermined period; First minimum value detection means for detecting the minimum value of the output of the detector during a predetermined period of time, and second maximum value detection means for detecting the maximum value of the output of the detector during a second predetermined period, A second minimum value detecting means for detecting a minimum value of the output of the detector during a second predetermined period; an output of the first maximum value detecting means; And an error signal generator that obtains a difference between the sum of the outputs of the minimum value detection means and the sum of the outputs of the second maximum value detection means and the second minimum value detection means and outputs the difference as an error signal. An optical disc reproducing apparatus, wherein a balance of the focus error detector is adjusted so that an error signal output from the error signal generator becomes substantially zero. 2. A laser as a light source, and an optical lens for focusing a laser beam emitted from the laser on an optical disc and obtaining reflected light corresponding to a signal recorded on the optical disc and a beam spot state. A block, a tracking actuator for moving the optical lens block in a radial direction of the disk, and a photodetector including a plurality of regions for detecting light reflected from the optical disk,
A tracking error detector that obtains a tracking error signal by performing arithmetic processing after electrically adjusting the balance of outputs from the plurality of regions of the photodetector, and performing arithmetic processing on outputs from the plurality of regions of the photodetector. A high-frequency signal detector for obtaining a high-frequency signal corresponding to a signal recorded on the optical disk, a filter amplifier for filtering a tracking error signal output from the tracking error detector, and an output of the filter amplifier. An optical disc reproducing apparatus provided with a tracking servo loop including a driver for driving the tracking actuator, comprising: a disturbance generator that injects disturbance into the tracking servo loop; and a high-frequency signal output from the high-frequency signal detector. A detector for detecting the envelope; First maximum value detection means for detecting the maximum value of the output of the detector in the first period, first minimum value detection means for detecting the minimum value of the output of the detector in a first predetermined period, and second A second maximum value detection unit that detects a maximum value of the output of the detector during a predetermined period; a second minimum value detection unit that detects a minimum value of the output of the detector during a second predetermined period; The difference between the sum of the output of the first maximum value detection means and the output of the first minimum value detection means and the sum of the output of the second maximum value detection means and the output of the second minimum value detection means And an error signal generator that outputs the error signal as an error signal, and balances the tracking error detector so that the error signal output from the error signal generator becomes substantially zero. Optical disc playback device. 3. The optical disk reproducing apparatus according to claim 1, wherein the disturbance generator generates a disturbance having a substantially sinusoidal waveform. 4. The optical disk reproducing apparatus according to claim 1, wherein the disturbance generator generates a disturbance having a substantially triangular waveform. 5. The optical disk according to claim 1, wherein the detector extracts a signal component of the highest frequency included in the high-frequency signal output from the high-frequency signal detector and detects the envelope. Playback device.