JPH1166578A - Circuit for detecting wobble signal of disk player - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect wobble signals with a simple arrangement by setting a signal balance-adjusting circuit which varies a position of a slider constituting a variable resistance element on the basis of a signal from a low pass filter circuit. SOLUTION: When wobble signals in a relationship of the same phase are applied to both ends of a resistor R, wobble signals taken out from a slider 6A are added, thereby increasing a signal level. If an addition level of low frequency components among signals obtained from an A part and a D part is different from an addition level of low frequency components of signals obtained from a B part and a C part, a difference of the levels of the signals appear as an output signal of a low pass filter circuit 9. A level of the output signal is detected and a position of the slider 6A is varied to reduce a difference of levels of addition signals. Because of this adjustment operation, data signals input to an output amplifier 7 through the slider 6A are offset and disappear, so that only the wobble signals are input to the output amplifier 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording a signal on a disk by a light beam emitted from an optical pickup and a reproducing or recording operation using a wobble signal recorded on a pre-groove formed on the disk. And a wobble signal detection circuit of the disc player configured to perform the following.

[0002]

2. Description of the Related Art A disk player configured to record a signal on an optical disk using a light beam emitted from an optical pickup has been commercialized. A groove called a pre-groove containing a wobble signal component is formed on an optical disc used in such a disc player, and the pre-groove is used to perform tracking control of a light beam at the time of recording while using the pre-groove. It is configured to perform rotation control. Further, such a disc player is configured to incorporate address information of an absolute time into the wobble signal, and to perform an access operation of a recording position by detecting the signal.

Such a disk player needs to perform the operation of detecting the wobble signal, and a circuit for detecting such a signal is disclosed, for example, in Japanese Patent Application Laid-Open No. 9-73636.

[0004]

The above-mentioned publication discloses a technique in which a compensation circuit for compensating for an amplitude change based on the eccentricity of the disk is described. To balance between the resulting signals,
It has a variable gain amplifier circuit that can adjust the gain. Such a variable gain amplifying circuit requires a characteristic of a wide change range of the gain, that is, a wide dynamic range, and thus has a problem that the configuration becomes complicated with higher performance.

An object of the present invention is to provide a wobble signal detection circuit which solves the above problem.

[0006]

A wobble signal detection circuit according to the present invention is incorporated in an optical pickup, is irradiated with light reflected from a disk surface, and is divided into four parts A, B, and C. A photodetector comprising a portion and a portion D, and a first detector for adding signals obtained from the portions A and D.
An adder circuit, a second adder circuit for adding signals obtained from the B section and the C section, an in-phase amplifier circuit to which an output signal of the first adder circuit is input and outputs an in-phase signal; An inverted-phase amplifier circuit that receives an output signal of the adder circuit and outputs an inverted-phase signal; an output signal of the in-phase amplifier circuit is applied to one end of a resistor; And a variable resistor element provided with a slider for deriving a signal applied from the other end thereof and inputted from both ends thereof, and an output for receiving a signal obtained from the slider and amplifying the signal. Amplifier circuit, a signal output from the output amplifier circuit, a low-pass filter circuit for removing a high-frequency signal, and the variable resistance element based on a signal obtained from the low-pass filter circuit. The position of the slider constituting being more configuration and signal balance adjusting circuit for variably.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The circuit shown in FIG. 1 is an embodiment of the wobble signal detection circuit of the present invention. In FIG. 1, reference numeral 1 denotes a photodetector incorporated in an optical pickup and irradiated with light reflected from a signal surface of a disk.
Part, part B, part C and part D. In the photodetector 1, the direction in which the division line between the portion A and the portion B extends is set so as to coincide with the tangential direction of the pregroove provided on the disk.

Reference numeral 2 denotes an A section and a D which constitute the photodetector 1.
The first addition circuit 3 receives the signals obtained from the sections and adds the signals, and adds the signals obtained from the sections B and C constituting the photodetector 1 and adds the signals. Is a second addition circuit. Reference numeral 4 denotes an in-phase amplification circuit that receives an output signal of the first addition circuit 2 and outputs a signal having the same phase as that of the input signal to an output terminal thereof, and 5 receives an output signal of the second addition circuit 3. And an output terminal for outputting a signal having a phase opposite to that of the input signal.

Reference numeral 6 denotes a variable resistance element provided with a resistor R and a slider 6A for changing the resistance value.
B is connected to the output terminal of the in-phase amplifier circuit 4,
C is connected to the output terminal of the reverse-phase amplifier circuit 5.
Reference numeral 7 denotes an output amplifier circuit to which a signal obtained through the slider 6A constituting the variable resistance element 6 is input, and the signal is amplified and output to the output terminal 8.

Reference numeral 9 denotes a low-pass filter circuit to which the output signal of the output amplifier circuit 7 is applied. The pass frequency of the filter is set so as to extract a signal obtained from a pre-groove provided on the disk. Reference numeral 10 denotes a signal balance adjustment circuit to which a signal that has passed through the low-pass filter circuit 9 is applied.
Has the effect of changing the position of the slider 6A that constitutes.

In such a configuration, the variable direction of the slider 6A by the signal balance adjusting circuit 10 is the direction in which the level of the output signal of the low-pass filter circuit 9 decreases, that is, the in-phase amplifier circuit extracted from the slider 6A. 4 is moved in a direction in which the level of the low-frequency signal of the output signal of the output signal 4 and the level of the low-frequency signal of the output signal of the reverse-phase amplifier circuit 5 become the same.

The present invention is configured as described above, and the operation will be described next. The data signal recorded on the disk is configured to be obtained by adding signals from all the parts A, B, C and D constituting the photodetector 1. When the output signal of the first addition circuit 2 for adding the signals obtained from the A and D parts is compared with the output signal of the second addition circuit 3 for adding the signals obtained from the B and C parts, the output signal is recorded on the disk. The phases of the signals obtained from the data signals are in the same phase, and the phases of the wobble signals obtained from the pregroove are in the opposite phases.

Therefore, when the output signal of the in-phase amplifier circuit 4 for amplifying the output signal of the first adder circuit 2 and the output signal of the reverse-phase amplifier circuit 5 for amplifying the output signal of the second adder circuit 3 are compared with each other, The phases of the signals obtained from the recorded data signals have an opposite phase relationship, and the phases of the wobble signals obtained from the pregroove have the same phase relationship. When a signal having such a relationship is applied to both ends of the resistor R constituting the variable resistance element 6, the data signals taken out from the slider 6A cancel each other, the signal level decreases, and the wobble signal is added. Therefore, the signal level increases.

When such an operation is performed, the addition level of the low-frequency signal in the signals obtained from the sections A and D, the sections B and C
If the added level of the low-frequency signal in the signal obtained from the section is different, the level difference of the signal will appear as an output signal of the low-pass filter circuit 9. By detecting the level of this output signal, the slider is detected. The position of 6A is changed so that the level difference of the added signal is reduced. As a result of such an adjusting operation, the data signal input to the output amplifier circuit 7 through the slider 6A is canceled out, and only the wobble signal is input to the output amplifier circuit 7. . Therefore, only the wobble signal amplified by the output amplifier circuit 7 is output to the output terminal 8, and the operation of detecting the wobble signal obtained from the pre-groove provided on the disk can be performed.

The slider 6A constituting the variable resistance element 6
Can be configured to be performed by providing a plurality of electronic switches and controlling the opening and closing operations of the switches.

[0016]

According to the present invention, the four parts A, B, C
A slider which derives a signal obtained from a part A and a part D of a photodetector comprising a part and a part D and a signal inverted from a signal obtained from the part B and a part C from both ends of a resistor. And a signal balance adjustment circuit that varies a position of a slider that constitutes the variable resistance element based on a signal obtained from a low-pass filter circuit that extracts a low-frequency signal. Since the wobble signal detection operation is performed, the configuration can be simplified and the device can be manufactured at low cost as compared with the case where a variable gain amplifier circuit is used.

[Brief description of the drawings]

FIG. 1 is an embodiment of a wobble signal detection circuit according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photodetector 2 1st addition circuit 3 2nd addition circuit 4 In-phase amplification circuit 5 Negative-phase amplification circuit 6 Variable resistance element 6A Slider 9 Low-pass filter circuit 10 Signal balance adjustment circuit

Claims (2)

[Claims] 1. A disc player configured to record a signal on a disc with a light beam emitted from an optical pickup and to perform a tracking control operation of the light beam using a pregroove formed on the disc. Irradiates light reflected from the disk surface while being incorporated in the optical pickup,
And a photodetector comprising four divided A, B, C and D parts, a first addition circuit for adding signals obtained from the A and D parts, and a photodetector obtained from the B and C parts. A second adder circuit for adding signals output from the first adder circuit, an in-phase amplifier circuit for receiving an output signal of the first adder circuit and outputting an in-phase signal, A negative-phase amplifier circuit that outputs the signal of the above, the output signal of the in-phase amplifier circuit is applied to one end of a resistor and the output signal of the reverse-phase amplifier circuit is applied to the other end of the resistor,
A variable resistance element provided with a slider for deriving a signal input from both ends thereof; an output amplifying circuit for receiving a signal obtained from the slider and amplifying the signal; A low-pass filter circuit that receives a signal output from the amplifier circuit and removes a high-frequency signal, and varies a position of a slider that constitutes the variable resistance element based on a signal obtained from the low-pass filter circuit. A wobble signal detection circuit for a disc player, comprising a signal balance adjustment circuit. 2. The wobble signal detection circuit according to claim 1, wherein the position of the slider is changed by an electronic switch.