JPH08185664A - Wobble detecting circuit for optical disk device - Google Patents

Abstract

PURPOSE: To provide a wobble detecting circuit of an optical disk device capable of stably detecting a wobble signal without depending on the number of revolution of a disk and capable of a quick search and whose circuit constitution is also simplified. CONSTITUTION: A variable characteristic band-pass filter 5 whose frequency characteristic is variable and which detects a wobble signal from a signal obtained via an optical pickup 2 is provided in this circuit. Then, the variable characteristic band-pass filter 5 is controlled to a frequency characteristic suitable for extracting the frequency component of the wobble signal to be calculated based on the detected position of the optical pickup 2 and the number of the revolution of an optical disk 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wobble detection circuit for an optical disk device, and more particularly to a wobble detection circuit for an optical disk device capable of detecting a stable wobble signal without depending on the rotation speed of the disk.

[0002]

2. Description of the Related Art In a conventional optical disk apparatus, detection of a wobble signal from a pregroup formed on an optical disk is detected by a carrier of 22.05 kHz ± 1 kHz included in an HF signal obtained from an optical pickup. Three
This is performed by extracting a wobble signal FM-modulated with a biphase clock of kHz using a bandpass filter.

However, since the center frequency of this bandpass filter is fixed at 22.05 kHz, when the disc rotation speed is not a predetermined linear velocity, that is, when the disc is started or when a large search is performed, The obtained wobble signal changes from the fixed center frequency of the bandpass filter and cannot be normally detected.

Therefore, since the wobble signal is used for the constant linear velocity control of the disk, the control becomes impossible in the above case. Therefore, in the conventional optical disk device, a large search is not carried out, but small and small searches are repeated, and at the time of start-up, FG rotation control is carried out by using a motor FG, and a wobble signal is input within the band of the bandpass filter. It was switched to CLV control after confirmation.

FIG. 6 is a block diagram showing the configuration of a conventional optical disc device of this type. The optical disc 1 is rotated by a disc motor 3 which is drive-controlled by a control signal sent from the FG control unit 14 or the CLV control unit 9 via a switch 15. The position of the optical pickup 2 is controlled by an actuator control unit 10 under the control of the microcomputer 8. The signal obtained through the optical pickup 2 is
After being converted into a voltage signal by the IV conversion unit 4, a bandpass filter (BPF) 12 having the fixed center frequency characteristic is provided.
Then, a frequency component in the vicinity of 22.05 kHz is extracted, the level of the extracted component is compared with a predetermined threshold by the comparator 6, and the comparison result is compared with the demodulation section 7 and C.
It is sent to the LV control unit 9.

On the other hand, the FG signal corresponding to the motor rotation speed obtained from the frequency generator (FG) attached to the disk motor 3 is supplied to the FG servo lock detector 13 and the FG controller 14. The switch 15 is
It is connected to the input terminal A side, FG rotation control is performed based on the FG signal, and the FG servo lock detection unit 13 outputs FG.
When the servo lock state is detected, the input terminal B of the switch 15 is connected via the microcomputer 8 and the disk motor 3 is controlled by the control of the CLV control unit 9.
The CLV control unit 9 compares the reference clock obtained by dividing the output of the oscillator 16 by the frequency divider 22 with the center frequency signal of the wobble signal obtained from the comparator 6 to obtain a constant linear velocity. Are controlled.

[0007]

FIG. 7 shows an example of frequency characteristics of the bandpass filter 12. As shown, the center frequency of the bandpass filter 12 is 22.0.
It is fixed at 5 kHz. Using this bandpass filter, when the inner peripheral portion of the disc is controlled to rotate at 600 rpm, when the high speed search is performed to the position where the outer peripheral portion must be controlled at 200 rpm, the disc rotation is still 600 rpm. Then, the wobble component included in the HF signal input to the bandpass filter has a center frequency tripled (600/200 = 3) to 66.15 kHz, making it impossible to detect the wobble signal. Also,
When the disc is started, the wobble signal is not detected unless the disc is started up to a rotation speed of around 600 rpm, assuming that the disc is started at the inner circumference of the disc.
It started using the FG control circuit until 00 rpm. At 600 rpm, the FG servo lock is detected, and thereafter, the CLV control is switched.

As described above, since the wobble detection circuit of the conventional optical disk device cannot perform a large search, a quick search cannot be performed, which not only impairs playability but also an FG control circuit for start-up control. Is required,
There was a problem that the burden of controlling the microcomputer also increased.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a wobble detection circuit for an optical disk device, which enables stable detection of a wobble signal without depending on the disk rotation speed, enables a quick search, and has a simplified circuit configuration. To do.

[0010]

In order to solve the above-mentioned problems, the wobble detection circuit of the optical disk device according to the present invention is
In a wobble detection circuit of an optical disc device that detects a wobble signal corresponding to a pre-groove formed on an optical disc through an optical pickup, a position detection circuit that detects the position of the optical pickup and a rotation number of the optical disc are detected. A rotation speed detection circuit, a variable characteristic band-pass filter to which a signal obtained through the optical pickup is input, and frequency characteristics are variable, the wobble obtained based on the detected position of the optical pickup and the rotation speed of the optical disk. And a control circuit for controlling the variable characteristic bandpass filter to have a frequency characteristic suitable for extracting the frequency component of the signal.

According to another aspect of the present invention, there is provided a wobble detection circuit for an optical disc device, wherein the wobble detection circuit for an optical disc device detects a wobble signal corresponding to a pre-groove formed on the optical disc through an optical pickup. A variable characteristic band pass filter having a variable frequency characteristic to which a signal obtained via an optical pickup is input, a potentiometer for detecting the position of the optical pickup, and a level shift circuit for shifting a level obtained by the potentiometer by a predetermined level. And an f-V conversion circuit for converting the frequency of the FG signal from the dimm motor that rotates the optical pickup into a voltage signal, and the output level from the f-V conversion circuit divided by the output level from the level shift circuit. And a variable division unit that outputs the variable characteristic by an output from the division unit. Configured to control the characteristic of the band-pass filter.

[0012]

According to the present invention, a variable characteristic bandpass filter having a variable frequency characteristic for detecting a wobble signal from a signal obtained through the optical pickup is provided, and the variable characteristic bandpass filter is obtained based on the detected position of the optical pickup and the rotation speed of the optical disk. The variable characteristic band pass filter is controlled to a frequency characteristic suitable for extracting the frequency component of the wobble signal.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of a wobble detection circuit of an optical disk device according to the present invention. In FIG. 1, components designated by the same reference numerals as those in FIG. 6 are components having the same function.

In this embodiment, the voltage control type bandpass filter 5 is used to make the frequency characteristic of the bandpass filter for wobble signal extraction variable, and the reference position information is obtained by the TOC position switch 11.

The microcomputer 8 uses the F from the disk motor 3
The G signal is received, the rotation speed of the motor is calculated from the FG signal (FG pulse), and the address information (time information) obtained from the demodulator 7 based on the reference position information of the TOC position switch 11 and the actuator controller The position of the optical pickup 2 in the radial direction is calculated based on the mirror signal and the like obtained from 10. The microcomputer 8 obtains the frequency of the wobble signal from the rotation number of the motor and the radial position of the optical pickup thus obtained, and a voltage that makes the obtained frequency the center frequency of the voltage control type bandpass filter 5 is set to the D / A port ( (Not shown).

For example, when the prescribed rotation speed of the disk (motor) is 600 rpm on the inner circumference and 200 rpm on the outer circumference, and it is approximated (assumed) that the rotation speed changes linearly between them, the target rotation speed No (rpm) depending on the radial position r Is r = r0 on the inner circumference,
When r = 0 on the outer circumference, N0 = 200 + (400 / r0) r (1). On the other hand, FG with n teeth per rotation of the disk motor
When the period T of one FG pulse wave is measured, the current rotation speed N (rpm) is N = (60 / nT) (2). The wobble signal is detected at fW0B = 22.05 kHz if the disk is rotating at the target rotation speed, so if the disk is rotating at N (rpm) away from the target rotation speed N0, f = fWOB (N / N0) (3) will be detected.

Therefore, the radial position r and the current rotational speed N
If is found, the frequency of the wobble signal can be calculated. A table of the input voltage and the center frequency of the voltage control type bandpass filter 5 is stored in the built-in memory of the microcomputer 8, and the corresponding voltage is output from the D / A port of the microcomputer 8 to obtain the voltage control type bandpass filter. 5
The center frequency of the can be made to follow the frequency of the detected wobble signal. The above-mentioned approximation error is absorbed by setting the Q value of the bandpass filter appropriately.

When the disk is started up, the TOC position switch 11 makes a radial position so that the center frequency of the bandpass filter 5 is initially detected when the detected rotational speed is low. The wobble signal can be extracted in any case because the center frequency rises following the frequency of the wobble signal to be detected as the number of revolutions increases, so that the wobble signal can be extracted in any case.
It is possible to pull in the disk servo without the G control unit 14.

When a predetermined amount of search is performed from a certain position, the position immediately before the search is calculated from the time address information obtained from the demodulator 7, and the search distance is counted by the mirror signal obtained from the actuator control section 10. To obtain. The position immediately after the search is obtained from the sum of the two pieces of information thus obtained. Further, the wobble signal can be quickly obtained by calculating the rotation speed from the FG signal and appropriately controlling the voltage of the voltage control type bandpass filter 5 based on the position and the rotation speed.

FIG. 2 shows an example of frequency characteristics of the voltage control type bandpass filter 5, which is 600 at the innermost circumferential position.
It shows the characteristic change when searching from the rpm rotation to the outermost position. Center frequency is approximately 22.05 kHz to approximately 6
It has changed to 6.15 kHz. At the outermost position, 600 rpm because the specified rotation speed is near 200 rpm
When rotated at, the center frequency of the obtained wobble signal becomes 66.15 kHz.

FIG. 3 is a structural block diagram showing another embodiment of the circuit according to the present invention. In this embodiment, the position of the optical pickup 2 is detected by the potentiometer 12 and is shifted by the level shifter 14 as shown in FIG. If the detection output VP of the potentiometer 12 is r = ro on the inner circumference and r = 0 on the outer circumference, and VP = 2 · r / ro is designed, and the voltage of the level shift unit 14 is VLS (V), then VLS = 2・ Design as r / ro + 1 (4). The f-V conversion unit 17, as shown in FIG.
A voltage corresponding to the disk rotation speed (rpm) is output based on the motor FG signal. When the voltage of the fv conversion unit 17 is Vfv (V), Vfv = N / 200 (5) Here, N is designed as the current rotation speed N (rpm).
The division unit 15 divides the output voltage from the fV conversion unit by the output voltage from the level shift unit 14 to obtain f /
fWOB can be determined. The result of the division unit 15 is Vfv / VLS = N / (200 + 400r / ro) (6) from the equations (4) and (5), and by substituting the equation (1), Vfv / VLS = N / No (7) Becomes Substituting equation (7) into equation (3) yields f = fWOB · Vfv / VLS (8). At this time, the characteristics of the voltage-controlled bandpass filter 5 are fBPF = fWOB at 1V and fBPF = x · f at xV.
By designing to be WOB, the same operation as that of the above-described embodiment can be realized without the intervention of the microcomputer 8. Further, in the present embodiment, the voltage control type band pass filter is used, but any frequency control type band pass filter, DSP band pass filter or the like may be used as long as the frequency characteristic is variable.

[0022]

As described above, according to the present invention,
The wobble signal can always be detected stably without depending on the disk rotation speed without requiring the FG control unit, and the quick search can be performed, the playability is remarkably improved, and the circuit configuration can be simplified.

[Brief description of drawings]

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

FIG. 2 is a voltage control type bandpass filter 5 in FIG.
It is a figure which shows the frequency characteristic example of.

FIG. 3 is a configuration block diagram showing another embodiment of the wobble detection circuit of the optical disk device according to the present invention.

4 is a diagram showing the relationship between the position of the optical pickup 2 shown in FIG. 3 and the outputs of the potentiometer 12 and the level shift unit 14. FIG.

5 is a diagram showing a characteristic example of the fV converter 17 shown in FIG.

FIG. 6 is a configuration block diagram of a conventional optical disc device.

7 is a diagram showing an example of frequency characteristics of the bandpass filter 12 shown in FIG.

[Explanation of symbols]

 1 Optical Disc 2 Optical Pickup 3 Disc Motor 4 I-V Converter 5 Voltage Controlled Bandpass Filter 6 Comparator 7 Demodulator 8 Microcomputer 9 CLV Controller 10 Actuator Controller 11 TOC Position Switch 12 Potentiometer 13 f-V Converter 14 Level Shift unit 15 Division unit

Claims (2)

[Claims] 1. A wobble detection circuit of an optical disc device for detecting a wobble signal corresponding to a pre-groove formed on an optical disc through an optical pickup, and a position detection circuit for detecting the position of the optical pickup, A rotation speed detection circuit for detecting the rotation speed, and a signal obtained via the optical pickup are input,
A variable characteristic bandpass filter having a variable frequency characteristic; and the variable characteristic bandpass filter having a frequency characteristic suitable for extracting the frequency component of the wobble signal obtained based on the detected position of the optical pickup and the rotation speed of the optical disc. And a control circuit for controlling the wobble detection circuit of the optical disk device. 2. A wobble detection circuit of an optical disc device for detecting, via an optical pickup, a wobble signal corresponding to a pregroup formed on an optical disc, a signal obtained via the optical pickup is input,
A variable characteristic bandpass filter having a variable frequency characteristic, a potentiometer for detecting the position of the optical pickup, a level shift circuit for shifting the level obtained by the potentiometer by a predetermined level, and a dimm motor for rotating the optical pickup. F
An f-V conversion circuit that converts the frequency of the G signal into a voltage signal, and a division unit that divides the output level from the f-V conversion circuit by the output level from the level shift circuit,
A wobble detection circuit for an optical disk device, wherein the characteristic of the variable characteristic bandpass filter is controlled by an output from the division unit.