JPH08185665A - Optical disk device - Google Patents

Abstract

PURPOSE: To provide an optical disk device whose constitution is simple, in which a stable operation is secured and which is capable of improving both performances of the pull-in characteristic and the suppression characteristic of a disk control. CONSTITUTION: Plural pieces of frequency dividers 10A to 10C frequency-dividing a reference clock frequency having a predetermined frequency in accordance with plural double speeds in the case of making possible the rotating and the controlling of a disk 1 with plural double speeds and of controlling the rotation of the optical disk based on a wobble signal are provided in this device. Then, one output is selected in accordance with a speculated double speed among outputs from plural pieces of frequency dividers 10A to 10C and the characteristic (the center frequency and the Q value) of a band-pass filter 4 for detecting the wobble signal is variably set in accordance with the selected output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device,
In particular, the present invention relates to an optical disc device having a simplified structure and improved playability.

[0002]

2. Description of the Related Art A conventional optical disk device has a 1 × speed, a 2
Many are capable of reproducing and recording at double speed and recording TOC information. On the other hand, there is also a demand for an operation such as recording at a higher speed, for example, triple speed, and in order to satisfy such a demand, the configuration shown in FIG. 5 has been conventionally used.

In FIG. 5, the signals obtained from the optical disk 1 rotated by the disk motor 2 through the optical pickup 3 are center frequencies for wobble signal extraction at respective speeds, that is, 1x speed, 2x speed and 3x speed. Bandpass filters 12A, 12B and 12C with
Sent to Wobble signal is 2 at 1x speed
2.05kHz carrier wave with frequency shift of ± 1kHz F
The M-modulated signal has an FM-modulated signal of 6.3.
3.15 kbit / with a bi-phase clock of kHz
It contains s time data. The selector 13 is controlled by the microcomputer 8 and selects the output from the designated bandpass filter corresponding to the double speed and sends it to the demodulator 6 and the CLV control unit 7. The time information obtained by the demodulation unit 6 is supplied to the microcomputer 8. The CLV control unit 7 compares the frequency of the carrier wave with a predetermined reference clock and controls the disc motor 2 so that the optical disc 1 has a constant linear velocity so as to have a constant linear velocity.

FIG. 6 shows the bandpass filter 12 described above.
The frequency characteristics (and Q characteristics) of A, 12B and 12C are shown. The center frequency of each band pasta filter is set corresponding to the rotation speed of the optical disc (1 × speed, 2 × speed, and 3 × speed).

[0005]

The pull-in characteristic of the disc control in the above-mentioned optical disc device is improved when the band of each band pass filter is wide, that is, when the Q value is set to a small value. In order to suppress the steady deviation during recording and reproduction and to improve the characteristics, it is better to set the band of each bandpass filter narrower, that is, to set the Q value to a large value. There was a limit to the performance improvement because it was necessary to set contradictory characteristics. In particular, since the pull-in characteristic cannot be sufficiently secured, there is no choice but to slow down the track jump and the search speed, and there is a problem that playability deteriorates.

Further, since the bandpass filter is usually composed of an operational amplifier, a resistor, and a capacitor, the number of parts is increased, the circuit configuration is complicated, and the set center frequency of the bandpass filter depends on temperature. There is also the problem of slipping.

Therefore, an object of the present invention is to have a simple structure,
An object of the present invention is to provide an optical disk device capable of ensuring stable operation and improving both the pull-in characteristic and the suppression characteristic of disk control.

[0008]

In order to solve the above-mentioned problems, an optical disk device according to the present invention is capable of controlling the rotation of an optical disk at a plurality of speeds and extracting a wobble signal obtained from the optical disk via an optical pickup. Then, in the optical disk device for controlling the rotation of the optical disk, a reference clock generating section for generating a reference clock having a predetermined frequency and the frequency of the reference clock are divided corresponding to the plurality of double speeds. A plurality of frequency dividers,
A selector that selects one of the outputs from the plurality of frequency dividers corresponding to a specified double speed, and a center frequency that is variably set according to the output selected by the selector, A bandpass filter for inputting a signal via a pickup and extracting a wobble signal.

An optical disc apparatus according to another aspect of the present invention can control the rotation of the optical disc at a plurality of speeds, and extracts a wobble signal obtained from the optical disc through an optical pickup to rotate the optical disc. In an optical disc device to be controlled, a reference clock generating unit that generates a reference clock having a predetermined frequency, a plurality of frequency dividers that divide the frequency of the reference clock in correspondence with the plurality of double speeds, A selector that selects one of the outputs from the plurality of frequency dividers corresponding to a designated double speed, and a center frequency that is variably set and designated corresponding to the output selected by the selector. A band pass filter for inputting a signal via the optical pickup to extract a wobble signal, the Q value being variably set according to the operating state. It is made.

Here, the bandpass filter may be a frequency control type bandpass filter or a voltage control type bandpass filter.

[0011]

In the present invention, the rotation of the optical disk can be controlled at a plurality of double speeds, and when the rotation of the optical disk is controlled based on the wobble signal, the frequency of the reference clock having a predetermined frequency is set to the plurality of double speeds. A plurality of frequency dividers for corresponding frequency division are provided, and one of the outputs from the plurality of frequency dividers is selected according to the specified double speed, and a band for wobble signal detection is selected. The characteristics (center frequency, Q value) of the pass filter are variably set corresponding to the selected output.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of an optical disk device according to the present invention.

The signal obtained from the optical disc 1 rotated by the disc motor 2 through the optical pickup 3 is:
It is input to, for example, a frequency control type band pasta filter 4 having variable frequency characteristics. As the frequency control type band pasta filter 4, for example, a switched capacitor IC (LMF100 or the like) manufactured by National Semiconductor can be used. As shown in FIG. 2, a plurality of operational amplifiers 411 of the switched capacitor filter 41 (in this example, 2 One) of the feedback resistors R2a and R2b.
2 is configured to be selectively connectable. The switching connection of the selector 42 is controlled by a coefficient switching signal from the coefficient switching unit 5 under the control of the microcomputer 8. A resistor R1 is connected in series to the input side of the operational amplifier 411 of the switched capacitor filter 41, and a filter output is obtained via the resistor R3 connected in parallel and is sent to the demodulation unit 6.

The center frequency f0 of this bandpass filter
If the input clock frequency is fCLK, for example, f0
= FCLK / 50, the Q value when each resistor is selected is Qa = R3 / R2a, or Qb = R3 /
It becomes R2b. Since the gain is -R3 / R1, if R1 = R3, it will be 0 dB at f = f0.

Therefore, assuming that the center frequency of the wobble signal at 1 × speed is fW1 = 22.05 kHz, the center frequency at 2 × speed is fW2 = 2fW1, and the center frequency at 3 × speed is fW3.
= 3fW1.

In FIG. 1, the frequency divider 10A for dividing the reference clock frequency from the reference clock generator 11 is divided by 6, the frequency divider 10B is divided by 3, and the frequency divider 10C is divided by 2. Then, the selector 9 controlled by the microcomputer 8 supplies a frequency reference clock suitable for the designated double speed to the frequency control type hand-pass filter 4.

For example, when the frequency of the reference clock from the reference clock generator 11 is set to 300 fW1, if the selector 9 selects the output of the frequency divider 10A, the clock fCLK input to the frequency control type band pass filter 4 is selected. Is fCLK = 300fW1 / 6 = 50fW1, and the center frequency f0 of the bandpass filter is f0 = fCLK / 50.
0 = fW1.

If the selector 9 selects the output of the frequency divider 12B, the center frequency f0 = 2fW1 = fW2. If the selector 9 selects the output of the frequency divider 12C, the center frequency f0 = 3fW1 = fW3. Becomes

The wobble signal is detected by the above configuration, and if the circuit shown in FIG. 2 is used as the circuit configuration for that purpose, it can be realized by several resistors, and the circuit configuration is simplified.

The demodulator 6 decodes the time information based on the signal that has passed through the wobble detection circuit as described above and outputs it to the microcomputer 8. The CLV controller 7 receives a command from the microcomputer 8 and controls the disk motor 2 so that the optical disk 1 has a constant linear velocity.

The microcomputer 8 also controls the coefficient switching unit 5 and sends a coefficient switching signal to the selector 42 to select the resistor R2a having the relationship of R2a> R2b when the servo is pulled. As a result, Qa <Qb, and the pull-in characteristic is improved. On the contrary, in the steady state, the resistor R2b is selected and Q
Increase the value to improve the suppression characteristics.

FIG. 3 shows the frequency characteristic and the Q characteristic of the frequency control type bandpass filter in the present embodiment at 1 × speed, 2 × speed and 3 × speed. In FIG.
The solid line characteristic shows a large Q value when steady, and the broken line characteristic shows a small Q value when the disk is pulled in.

In the above embodiments, the accuracy can be improved by connecting the frequency control type bandpass filters 4 in cascade to increase the filter order.

FIG. 4 is a block diagram showing the configuration of another embodiment of the optical disk device according to the present invention. In the present embodiment, the frequency control type bandpass filter 4 is used in the embodiment shown in FIG. 1, whereas the voltage control type bandpass filter 14 is used. The frequency characteristic is variably set.

[0025]

As described above, according to the wobble detection circuit of the optical disk device of the present invention, the structure is simplified,
Stable operation can be secured, and both performances of the disk control pull-in characteristic and suppression characteristic can be significantly improved.

[Brief description of drawings]

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

2 is a diagram showing a configuration example of a frequency control type band pasta filter 4 in FIG.

3 is a diagram showing frequency characteristics and Q characteristics at 1 × speed, 2 × speed, and 3 × speed of the frequency control type bandpass filter in the embodiment shown in FIG.

FIG. 4 is a configuration block diagram of another embodiment of the optical disk device according to the present invention.

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

6 is a band pass filter 12A, 12 in FIG.
It is a figure which shows the frequency characteristic of B and 12C.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 optical disk 2 disk motor 3 optical pickup 4 frequency control type bandpass filter 5 coefficient switching section 6 demodulation section 7 CLV control section 8 microcomputer 9,13,42 selector 10A-10C frequency divider 11 reference clock generation section 12A-12C bandpass Filter 14 Voltage-controlled bandpass filter

Claims (3)

[Claims] 1. An optical disk device capable of controlling rotation of an optical disk at a plurality of double speeds, extracting a wobble signal obtained from the optical disk through an optical pickup, and controlling the rotation of the optical disk. A reference clock generating section for generating a reference clock; a plurality of frequency dividers for dividing the frequency of the reference clock in correspondence with the plurality of double speeds; and an output from the plurality of frequency dividers. A selector that selects one output corresponding to the specified double speed, and a center frequency is variably set corresponding to the output selected by the selector, and a signal via the optical pickup is input and a wobble signal is input. An optical disk device comprising: a bandpass filter for extracting the. 2. An optical disk device capable of controlling rotation of an optical disk at a plurality of speeds, extracting a wobble signal obtained from the optical disk through an optical pickup, and controlling the rotation of the optical disk. A reference clock generating section for generating a reference clock; a plurality of frequency dividers for dividing the frequency of the reference clock in correspondence with the plurality of double speeds; and an output from the plurality of frequency dividers. A selector that selects one output corresponding to the specified double speed and a center frequency that is variably set according to the output selected by the selector, and a Q value that is variable according to the specified operating state An optical disk device comprising: a bandpass filter which is set and which inputs a signal via the optical pickup and extracts a wobble signal. 3. The optical disk device according to claim 1, wherein the bandpass filter is a frequency control type bandpass filter or a voltage control type bandpass filter.