JPH0676465A - Disk motor control circuit of optical disk recording and reproducing device - Google Patents

Abstract

PURPOSE:To stabilize the rotation control of a disk motor. CONSTITUTION:The wobble signal generated in a preamplifier 4 is made to pass a band-pass filter 5 which makes an FM modulation signal pass the band necessary for demodulating and is inputted in a signal processing circuit 7 and a band-pass filter 6. The signal processing circuit 7 demodulates the inputted wobble signal. The band-pass filter 6 makes the wobble signal pass by the narrow band which is necessary for the rotation control of a disk motor 3. A changeover switch 12 is controlled by a control circuit 8, the passing signal of the band-pass filter 5 and the passing signal of the band-pass filter 6 are selected and the selected signal is inputted in the control circuit 8. The control circuit 8 controls the rotation of the disk motor 3 so that the average frequency of the wobble signal to be inputted from the changeover switch 12 may be 22.05kHz and swiches the changeover 12 by the state of the rotation control of the disk motor 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording / reproducing apparatus, and more particularly to a disk motor control circuit for controlling the rotation of a disk motor using a wobble signal.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional optical disk recording / reproducing apparatus. 1 shown in the figure is a recordable optical disc,
A pre-groove is engraved in a spiral in the recordable area. The pregroove has a waveform and includes FM-modulated address information.

Reference numeral 2 denotes an optical pickup, which irradiates a laser beam so as to focus on the disk so as to trace the pregroove, and picks up information from the reflected light. Further, at the time of disc recording, the laser emission intensity is changed according to the record information to write the information on the disc.

Reference numeral 3 denotes a disk motor, which rotationally drives the optical disk 1 clamped on a turntable provided on the rotary shaft. A preamplifier 4 amplifies the signal picked up by the optical pickup 2, generates respective error signals required for focus control and tracking control, outputs the error signals to the control circuit 8, and generates an information signal engraved on the optical disc 1. Then, the wobble signal from the pre-groove is generated and output to the signal processing circuit 7 and the control circuit 8 via the band pass filter 5.

The preamplifier 4 further drives the laser diode of the optical pickup 2 so that the laser diode emits light at a constant power necessary for reading information when reproducing the disc, and when recording the disc, the laser diode is operated according to the recording information from the signal processing circuit 7. Change the power.

The control circuit 8 receives the error signal from the preamplifier 4 to control the focus and tracking of the optical pickup 1 and controls the rotation of the disk motor 3 so that the average frequency of the wobble signal becomes 22.05 kHz. The control circuit 8 further moves the optical pickup 2 in response to a command from the system controller 9 to search for a designated address.

The signal processing circuit 7 is used for A / D at the time of recording.
Recording information is generated from the digital audio signal input from the converter 11 and the sub data input from the system controller 9 and output to the preamplifier 4.

During reproduction, the digital audio signal and the sub data are demodulated from the signal from the preamplifier 4 and output to the D / A converter 10 and the system controller 9, respectively, and further the address information is demodulated from the wobble signal to the system controller. Output to 9.

The system controller 9 is a signal processing circuit 7
It also controls the operation state of the control circuit 8 while communicating with the control circuit 8, and obtains the information engraved on the disc from the signal processing circuit 7 and sends the data necessary for recording and the operation command.

There are two optical disks to be reproduced by the above-mentioned conventional optical disk recording / reproducing apparatus, for example, a CD-WO disk.
2.05kHz carrier wave with frequency shift of ± 1kHz F
The M-modulated signal is engraved. 3.15 with a 6.3 kHz bi-phase clock as an FM modulated signal
Data of kbit / s is included.

When the disc is rotated and the track is followed by the optical pickup, a wobble signal is detected in the push-pull error signal component. The rotation of the disk is controlled so that the average frequency of the wobble signal becomes 22.05 kHz, but the FM demodulation signal is also extracted from the wobble signal.

At the time of laser modulation, the S / N ratio of the wobble signal deteriorates due to the intensity of laser light emission, and the wobble signal cannot be read accurately. Therefore, the band required to demodulate the FM modulation signal (22.05 kHz). The wobble signal is input to the signal processing circuit 7 through the bandpass filter 5 that allows only (± 6.3 kHz) to pass.

The signal for controlling the rotation of the disk is also input to the control circuit 8 through the band pass filter 5 which passes the band necessary for demodulating the FM modulated signal. However, the band required for the rotation control of the motor is about 22.05 kHz ± 1 kHz, and a signal in a band wider than necessary is input to the control circuit 8.
Then, there is a drawback that the noise of the signal used for controlling the rotation of the motor cannot be sufficiently removed.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to use a wobble signal from which noise is sufficiently removed so that the laser modulation is performed. In order to provide a stable control, a disc motor control circuit for an optical disc recording / reproducing apparatus is also provided.

[0015]

DISCLOSURE OF THE INVENTION A disk motor control circuit of the present invention is an optical disk recording / reproducing apparatus for recording / reproducing an optical disk in which address information is frequency-modulated and carved into a pre-groove waveform. The wobble signal is input through the band pass filter having a band narrower than that of the band pass filter for guiding the signal to the demodulation circuit, and the rotation of the disk motor is controlled so that the average frequency of the wobble signal becomes constant.

In the disc motor control circuit, when the disc motor speed control is off,
The input is a signal that has passed through a bandpass filter that guides the wobble signal generated by the pregroove to the demodulation circuit.

[0017]

According to the disk motor control circuit of the optical disk recording / reproducing apparatus of the present invention, the wobble signal is limited to a narrow band necessary for the rotation control of the motor and is used as the signal for the disk motor rotation control. Noise is sufficiently removed and stable control is performed.

Further, when the speed control of the disk motor is out of control, if the disk motor rotation control signal is switched to the signal that has passed through the band pass filter of a wider band, the speed control pull-in may be delayed or the control may be delayed. Impossible is prevented.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A disk motor control circuit of an optical disk recording / reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an optical disk recording / reproducing apparatus using a disk motor control circuit according to an embodiment of the present invention. In the figure, parts having the same functions as those shown in the conventional example are designated by the same reference numerals, and detailed description of the same functions will be omitted.

In the optical disk recording / reproducing apparatus of the embodiment, the wobble signal generated by the preamplifier 4 is set to 22.05 kHz.
The band pass filter 5 having a band of z ± 6.3 kHz passes the signal with a constant group delay and inputs the signal to the signal processing circuit 7 and the band pass filter 6.

The signal processing circuit 7 demodulates the input wobble signal to take out biphase-modulated data, demodulates it, and outputs it to the system controller 9.

The bandpass filter 6 outputs the wobble signal to 2
Pass in the band of 2.05 kHz ± 1 kHz. The changeover switch 12 is controlled by the control circuit 8 and selects the pass signal of the band pass filter 5 and the pass signal of the band pass filter 6 and inputs them to the control circuit 8. In the control circuit 8, the average frequency of the wobble signal input from the changeover switch 12 is 2
The rotation of the disk motor 3 is controlled so that the frequency becomes 2.05 kHz, and the changeover switch 12 is switched depending on the rotation control state of the disk motor 3.

When the disc motor 3 is started in this optical disc recording / reproducing apparatus, the control circuit 8 causes the changeover switch 1 to operate.
2 to select the output signal of the band pass filter 5 and wait until the average frequency of the wobble signal falls within a predetermined speed control lock range.

When the average frequency of the wobble signal falls within a predetermined speed control lock range, the control circuit 8 causes the changeover switch 12 to operate.
To output the output signal of the narrow bandpass filter 5 to the control circuit 8.

After the rotation of the disk motor 3 is settled in this manner, the system controller 9 receives a signal indicating that the rotation speed is locked from the control circuit 8 and outputs an information signal included in the wobble signal from the signal processing circuit 7. After that, the operation moves to a predetermined recording or reproducing operation.

When the control circuit 8 receives a search or stop command from the system controller 9, it switches the changeover switch 12 to the bandpass filter 5 side. After the end of the search, when the average frequency of the wobble signal falls within a predetermined speed control lock range, the control circuit 8 returns the changeover switch 12 to the bandpass filter 5 side, and when it stops, the changeover switch 12 remains the bandpass filter 5 side. Leave.

In this way, by switching the pass band of the wobble signal input to the control circuit 8, stabilization of the disc motor rotation control at the time of reproduction and recording is achieved. In particular, the S / N ratio of the wobble signal at the time of recording, that is, at the time of laser modulation is remarkably improved, and the effect of stabilizing the disk motor rotation control is increased.

[0028]

According to the disk motor control circuit of the optical disk recording / reproducing apparatus of the present invention, in particular, since the noise of the wobble signal at the time of laser modulation is sufficiently removed, the rotation of the disk motor is stabilized and the information is correctly recorded on the disk. Can be carved into.

[Brief description of drawings]

FIG. 1 is a block diagram showing an optical disk recording / reproducing apparatus using a disk motor control circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a conventional optical disc recording / reproducing apparatus.

[Explanation of symbols]

 1 Optical Disc 2 Optical Pickup 3 Disc Motor 4 Preamplifier 5 Bandpass Filter 6 Bandpass Filter 7 Signal Processing Circuit 8 Control Circuit 9 System Controller 10 D / A Converter 11 A / D Converter 12 Changeover Switch

Claims (2)

[Claims] 1. In an optical disc recording / reproducing apparatus for recording / reproducing an optical disc in which address information is frequency-modulated and engraved in a pre-groove waveform, a band narrower than a band pass filter band for guiding a wobble signal generated by the pre-groove to a demodulation circuit. A disk motor control circuit that controls the rotation of the disk motor so that the wobble signal is input through the band pass filter of and the average frequency of the wobble signal becomes constant. 2. The disk motor control circuit according to claim 1, wherein when the speed control of the disk motor is out of control, a signal that has passed through a band pass filter for guiding a wobble signal generated by the pre-groove to a demodulation circuit is input.