JPH0536073A - Optical disk device - Google Patents

Abstract

PURPOSE:To attain the exact reading of time information by controlling the central frequency of a band pass filter, the oscillated output signal frequency of a PLL circuit, and basic clock signal frequency corresponding to a double speed. CONSTITUTION:A 44.1KHz band pass filter 30 is selected by a changeover switch 31, and a signal is transmitted to an amplifier 5, at the time of a double speed. Also in an FSK demodulating circuit, the output of a voltage control oscillator 10 is 1/2 frequency-divided by a frequency-divider 32, and supplied to a phase comparator 6 so that a 44.1KHz PLL lock can be attained at the time of the double speed. In a data demodulating circuit, a frequency-divider 36 is selected by a switcher 37 so that a 12.6KHz clock can be obtained, at the time of the double speed. A desired demodulated clock can be obtained near at the center of the range of the oscillated frequency by a voltage control oscillator 15 after a preliminary adjustment. Thus, the time information can be exactly read while rotating an optical disk at the double speed.

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, and more particularly to an optical disk device which operates properly during recording / reproduction at double speed rotation.

[0002]

2. Description of the Related Art While rotating an optical disk, information is sequentially recorded on circumferential tracks using an optical head, and when recording is performed, time information obtained from a change in track groove of an optical disk due to wobbling (WOBBLE). (ATIP) is reading at the same time. The change due to wobbling is obtained as the amplitude of the tracking error signal TE as shown in FIG. FIG. 4A shows a wobbling tracking error signal, and FIG. 4B shows a normal tracking error signal.

The extraction of the above-mentioned time information in the conventional optical disk device is performed by the configuration as shown in FIG. 2 obtained by the two-division photoelectric converters 1a and 1b of the optical head
Each of the two signals is a current / voltage (IV) converter 2a
And 2b, it is converted into a voltage signal, and the differential amplifier 3 obtains a TE signal which is a differential signal. The TE signal has a center frequency of 2
Only the wobbling signal is extracted through the 2.05 KHz bandpass filter 4. The extracted wobbling signal passes through the comparator 5, and the FSK signal is obtained. FSK signal is ± 1KH centered at 22.05KHz
It is represented as 0 and 1 data by the frequency change of z.

The FSK demodulation circuit includes a phase comparator 6, a low pass filter (LPF) 7 and a voltage controlled oscillator (VC).
O) 8 PLL circuit, amplifier 9, capacitor 1
0, a low-pass filter 11 and a comparator 12, the PLL circuit locks the 22.05 KHz signal, and the low-pass filter 7 obtains a change of ± 1 KHz. This ± 1 KHz change signal is applied to the amplifier 9
After passing through the capacitor 10 and the low-pass filter 11
And the FSK demodulated output is obtained by comparing the average voltage of this output with the comparator 12. The output data thus obtained contains a clock component, and this clock component comprises a phase comparator 13, a low-pass filter 14 and a voltage controlled oscillator (V
In the PLL circuit composed of the CO) 15, the demodulation clock (6.3 KHz) is obtained by being synchronized.

The ATIP demodulation circuit 16 demodulates data based on the obtained demodulation clock and the FSK demodulation output from the comparator 12, and outputs a CRC signal and demodulation data (time information). Further, the output from the comparator 5 is divided by the frequency divider 17, the oscillation output from the oscillator 18 is divided by the frequency divider 19, and each divided output is supplied to the motor driver circuit 20 to drive the motor 21. To do. The above optical disc device is disclosed in Japanese Patent Laid-Open No. 312087.

[0006]

As described above, the conventional optical disk device obtains time information based on the wobbling signal obtained from the optical disk rotated at a constant speed. However, when the optical disc is rotated at a double speed, the frequency of the wobble signal obtained from the tracking error signal is doubled. Therefore, in the above conventional device, accurate recording position control and recording based on the time information engraved on the optical disc are performed. There was a problem that it could not be played.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disk device which enables accurate recording and reproduction based on time information even at double speed rotation.

[0008]

In order to solve the above-mentioned problems, an optical disk device according to the present invention provides an optical disk device for obtaining time information and the like based on a wobble signal obtained from an optical disk, in which the fundamental frequency component of the wobble signal is The center frequency of the bandpass filter to be extracted, the frequency of the oscillation output signal from the voltage controlled oscillator of the PLL circuit included in the circuit for FSK demodulating the output from this bandpass filter, and the frequency of the basic clock signal for rotating the optical disc are It is configured to selectively set the frequency corresponding to the double speed at the double speed rotation.

[0009]

In the present invention, the bandpass filter,
Voltage-controlled oscillator for FSK demodulation circuit, PLL for data demodulation
By controlling the voltage controlled oscillator of the circuit and the switching of the reference clock of the motor circuit, etc. in correspondence with the double speed, it is possible to read the accurate time information even at the double speed rotation, and the accurate time information can be read based on the read time information. It enables various recording position control.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an optical disk device according to the present invention. In the figure, the components having the same reference numerals as those in FIG. 5 indicate the same functional components. In this embodiment, the bandpass filter 4 is arranged in parallel with the 4th speed compatible filter 4.
A 4.1 KHz bandpass filter 30 is provided, and one of the bandpass filters is selected by the changeover switch 31. In addition, the feedback loop between the phase detector 6 and the voltage controlled oscillator 10 in the PLL circuit section of the FSK demodulation circuit is connected in parallel with 1
A / 2 frequency divider 32 is provided, and a changeover switch 33 is used for switching connection. Similarly, filter 1
A filter 34 is connected in parallel to 1 as well, and is selected by a changeover switch 35. A ½ frequency divider 36 is connected to the output of the voltage controlled oscillator 15 in the data demodulation circuit, and the voltage controlled oscillator 15 is switched by the changeover switch 37.
Or the output of the 1/2 frequency divider 36 is selected and sent to the ATIP demodulation circuit 16. Further, a ½ divider 38 for dividing the output of the oscillator 18 by ½ is provided, and the output of the oscillator 18 and the output of the ½ divider 38 are switched and output by a switch 39. The switching devices 31, 33, 35, 37
The switching of 39 and 39 is controlled by the double speed control signal output at the double speed.

At the time of double speed rotation, the wobble signal in the tracking error signal is a signal in which the frequency signal of 44.1 KHz and the TE error signal are superimposed. Therefore, at double speed, the changeover switch 31 causes 44.1K.
The Hz bandpass filter 30 is selected and its output is sent to the amplifier 5. Also in the FSK demodulation circuit, a PLL lock is applied to a wobble signal having a center frequency of 22.05 KHz during normal rotation, and 4 times during double speed rotation.
The output of the voltage controlled oscillator 10 is frequency-divided by a 1/2 frequency divider 32 into 1/2 so as to be PLL locked at 4.1 KHz and supplied to the phase comparator 6. The filter 34 has a filter characteristic of blocking a clock component corresponding to the rotation speed of the eye pattern signal during FSK demodulation, and is switched and used by the changeover switch 35 at the time of double speed.

In the data demodulation circuit, the PLL circuit is constructed so that the data demodulation clock of 6.3 KHz can be extracted during normal rotation.
½ frequency divider 36 to obtain a 6 KHz clock
Is selected by the switch 37. In addition, the voltage controlled oscillator 1
The oscillation frequency of No. 5 is adjusted in advance so that a desired demodulation clock can be obtained near the center of the oscillation frequency range.
This is oscillated at twice the frequency in normal rotation,
It is easier to construct by dividing by 1/2 in normal rotation. As the reference clock of the motor drive system, the 1/2 frequency divider 38 is switched by the changeover switch 39 and used to obtain an appropriate clock. In the above embodiment, the respective changeover switches are changed over by the high speed control signals "High" and "Low" so that the time information can be read while doubling the rotation of the optical disk.

FIG. 2 shows a reference clock (O) for signal processing.
SC) 46 to 16.9344 MHz or 8.4672
An example is shown in which it is possible to select the mode to be used in MHz. In the PLL circuit including the phase comparator 41, the low-pass filter 42, the voltage controlled oscillator (VCO) 43, the 1/2 frequency divider 44, and the switch 45, the output of the 1/2 frequency divider 44 is controlled by the double speed control signal.
By switching and selecting the output of the VCO 43, E
An FM signal is obtained. The signal processing circuit 47 includes a switch 45.
, The EFM signal, and the output signal of the oscillator 46, and performs predetermined signal processing and decoding processing corresponding to the double speed based on the mode switching signal. From the signal processing circuit 47, the data DATA and the strobe signal (44.1 KH
The right and left clocks LRCK, which are also z), are supplied to the digital filter 48. The strobe signal is shown in Fig. 1.
Is also supplied to the frequency divider 19 and can be used as a reference signal of the motor driver circuit 20. Here, the clock LRCK is normally 44.1 KHz, but becomes 88.2 KHz because the mode is switched at the double speed. Thus, the sampling clock of the digital filter 48 is set to 88.2K based on the sampling frequency switching signal.
Switching to Hz to obtain the acoustic signal for monitoring. However, since the data was originally recorded at a sampling frequency of 44.1 KHz, the band is suppressed to 20 KHz, and only a 10 KHz component is output at double speed, but it is practical when listening to music for monitoring. Not a big problem. The output of the digital filter 48 is converted into an analog signal by the D / A converter 49 and output from the speaker SP.

When the waveform shaping filter of the FSK data demodulation circuit in FIG. 1 is constructed, as shown in FIG. 3, the FSK demodulation waveform shaping filter is constructed by the first-stage low-pass filter during normal rotation. At the time of normal rotation, the first-stage low-pass filter removes frequency components higher than 3.15 KHz, which is the highest frequency of the FSK demodulation eye pattern, so the filter 51 cuts off at about 4 KHz and the second-stage low-pass filter. About 16 KHz to remove 22.05 KHz component of wobble signal with a filter
The unnecessary frequency component is removed by the configuration. As a result, it is possible to reduce errors in the demodulated data. Since the cutoff frequency is different at double speed, the filter is switched. Further, in order to simplify the circuit configuration, as shown in FIG. 3, the low pass filter 11 in the subsequent stage may be separated by the changeover switch 35 at low speed. A notch filter may be used to extract only the 22.05 KHz component.

[0015]

As described above, in the optical disk device according to the present invention, the bandpass filter, the FS
The voltage control oscillator of the K demodulation circuit, the voltage control oscillator of the PLL circuit for data demodulation, and the switching of the reference clock of the motor circuit are controlled corresponding to the double speed, so that the time information is accurate while rotating the optical disk at the double speed. Can be read out. Therefore, accurate recording position control based on the read time information is also possible. Further, in the FSK demodulation process, the data error can be reduced by switching the filter for removing unnecessary components from the demodulation eye pattern from the PLL circuit to an appropriate characteristic at the time of double speed rotation.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing another embodiment of the optical disk device according to the present invention.

FIG. 3 is a block diagram showing still another embodiment of the optical disk device according to the present invention.

FIG. 4 is a waveform diagram of a wobbling tracking error (TE) signal and a normal TE signal.

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

[Explanation of symbols]

1a, 1b Photoelectric converters 2a, 2b Current / voltage (IV) converter 3 Differential amplifiers 4, 7, 11, 14, 30, 34, 42, 51 Bandpass filters 5, 8 Amplifiers 6, 13, 41 Phase comparator 9 Capacitors 10, 15, 43 Voltage controlled oscillator (VCO) 12 Comparator 16 ATIP demodulator 17, 19 Divider 18, 46 Oscillator 20 Motor driver circuit 21 Motor 31, 33, 35, 37, 39, 45 Switching Switches 32, 36, 38, 44 1/2 divider 47 Signal processing circuit 48 Digital filter 49 D / A converter

Claims (3)

[Claims] 1. An optical disc device for obtaining time information and the like based on a wobble signal obtained from an optical disc, wherein a center frequency of a bandpass filter for extracting a fundamental frequency component of the wobble signal and an output from the bandpass filter are FSK demodulated. An optical disk device, wherein a frequency of an oscillation output signal from a voltage controlled oscillator of a PLL circuit included in the circuit and a frequency of a basic clock signal for rotating the optical disk are selectively set to a frequency corresponding to a double speed during double speed rotation. 2. An optical disk device, wherein the reference clock signal is a strobe signal output from a signal processing circuit for demodulating an EFM signal or the like. 3. An optical disc apparatus for obtaining time information and the like based on a wobble signal obtained from an optical disc, wherein a fundamental wave component of the wobble signal is obtained from a demodulated eye pattern signal obtained from a low pass filter of a PLL circuit included in an FSK demodulation circuit. And a cutoff frequency of a noise removal filter that mainly cuts off a frequency component higher than the highest frequency component in the demodulated eye pattern, at a high frequency corresponding to a double speed at the time of high speed rotation.