JPH0650589B2 - Disc-shaped recording medium and recording / reproducing apparatus thereof - Google Patents

Description

The present invention relates to a disc-shaped recording medium and a recording / reproducing apparatus therefor.

Recently, a system has been proposed in which an audio signal converted into a PCM signal on a disc-shaped recording medium is recorded and reproduced as a binary signal. In this case, the sync signal is recorded in the form of, for example, a Barker code, and the sync signal is detected by a constant digital signal pattern. On the other hand, in order to lengthen the recording time of a disc-shaped recording medium (hereinafter referred to as a disc), the number of rotations of the disc is set small at the outer peripheral portion and large at the inner peripheral portion to keep the recording density constant and the recording time longer. It has also been proposed to lengthen the length, which is called the CLV method (Constant Linear Velocity). In the case of such a CLV system, it is necessary to detect the synchronization signal and control the number of rotations of the recording medium so that the period becomes constant. For that purpose, the recorded digital signal is reproduced and the synchronization is performed. The signal must be detected stably, and in the case of the Barker code or the like, it is difficult to detect the Barker code stably without controlling the rotation speed of the disk to the normal rotation speed. Therefore, conventionally, it was difficult to reproduce the digital signal to obtain a stable audio signal.

It is an object of the present invention to provide a disc-shaped recording medium capable of stably reproducing a sync signal and a recording / reproducing apparatus therefor.

In the disk-shaped recording medium of the present invention, a synchronization signal of a modulation method different from that of a data signal is recorded on a meandering track, the distances of the synchronization signal on the disk are substantially equal, and the recording band of the synchronization signal is data. It is characterized in that it is narrower than the recording band of the signal.

In the recording / reproducing apparatus of the present invention, a synchronization signal of a modulation method different from that of the data signal is recorded on a meandering track, the distances of the synchronization signal on the disk are substantially equal, and the recording band of the synchronization signal is a data signal. Sync signal detecting means for detecting the sync signal from a disk-shaped recording medium narrower than the recording band of the sync signal detecting means, and comparing the output of the sync signal detecting means with the output of the reference oscillator to generate the output of the sync signal detecting means. A control device for controlling the rotation speed of the disk is provided so as to keep the cycle of the synchronizing signal constant.

Hereinafter, the present invention will be described based on an example.

FIG. 1 shows the main structure of a recording / reproducing apparatus for recording / reproducing an audio signal, and 1 is a digital signal obtained by PCMizing an audio signal I supplied to an input terminal (a) for recording.
RCM modulator that converts to II, PC on the output (c) side
A digital signal II converted into M and a sync signal III indicating the delimiter of the digital signal II are output in the format shown in FIG. 2 (a), and a signal representing the period of the sync signal III is provided on the output (b) side. Occurs. Reference numeral 2 denotes a modulator that modulates the output (C) signal, for example, an MFM modulator. Reference numeral 3 denotes an FM modulator for modulating a portion of the synchronizing signal III of the output of the modulator 2, for example, a burst signal in which the pilot signal d output from the oscillator 5 is gated by the output signal (b) via the gate circuit 4. The signal e is FM-modulated.

FIG. 2 shows this waveform, and FIG. 2 (a) shows the PCM signal divided by the synchronization signal III as described above.
FIG. 2B is an enlarged view of the portion of the synchronization signal III. Only the sync signal portion of FIG. 2 (b) is FM-modulated by the burst signal O as shown by arrow (d).

As is well known, the MFM-modulated signal has three periods of "To", "1.5To" and "2To" when the minimum period is "To".
Since it is composed of pulses with different periods, the synchronization signal II
The FM-modulated signal of the portion I must be selected so that the period is not shorter than "To". In this embodiment, the pulse of "1.5To" is continuously used as the synchronizing signal pulse and then the burst signal e is used. This "1.5To" pulse was used as a carrier for modulation.

At the time of recording, the disk 13 is driven at a constant relative speed, the signal of the output of the synchronizing signal modulator 3 is recorded, and the signal reproduced by the signal reproducing device (not shown) at the time of reproduction is the waveform shaper 6
After that, the FM demodulator 7 reproduces the burst signal shown in FIG. This is extracted by the bandpass filter 8,
The waveform shaper 9 converts the signal into a sync signal pulse.

The bandpass filter 8 is selected in an appropriate band (0.5f to 1.5f) centering on the frequency of the pilot signal d, for example, according to the rotation speed control range of the disk 13.

The output (reproduction synchronization signal) of the waveform shaper 9 is compared with the output of the reference oscillator 11 by the control device 10, and the disk drive motor 12 that rotationally drives the disk 13 so that the reproduction synchronization signal becomes equal to the output of the reference oscillator 11. Control the rotation.

Although the above embodiment has been described by adding the FM-modulated synchronizing signal to the MFM-modulated signal, the same applies to the combination of other modulation methods. Of course, the modulation method of the synchronizing signal portion is preferably a method having a large jitter margin and strong against fluctuations in the level of the reproduced signal, and the FSK method and the phase modulation method are also excellent.

Further, in the above embodiment, all of the sync signals are FM-modulated, but the modulation system may be partially changed to use the conventional Barker code or the like for the remaining sync signal parts. Also, when a signal is recorded on a disc, if the disc-shaped recording medium of the present invention is used together with the CLV system in a signal reproducing device provided with a so-called track wobbling type tracking servo that causes the recording track to meander, reproduction of the recording / reproducing device is performed. Has been confirmed to work stably.

In the above embodiment, the sync signal detecting means in the claims is composed of the waveform shaper 6, the FM demodulator 7, the bandpass filter 8 and the waveform shaper 9.

As described above, according to the disc-shaped recording medium and the recording / reproducing apparatus thereof of the present invention, it is possible to stably and accurately reproduce the sync signal, and the conventional method using the Barker code or the like causes a disc defect. Although it often caused malfunction due to dropout, it is confirmed by experiments that this point can be remarkably improved.

Also, when detecting the synchronization signal from the disk-shaped recording medium,
Since the band of the sync signal is narrower than the band of the data signal, the band of the sync signal can be separated by using the filter of the narrow band, and the detection of the sync signal can be stabilized.

Since track woblink and CLV are methods that depend greatly on the stability of detection of the synchronization signal, this combination produces a great effect.

[Brief description of drawings]

FIG. 1 is a block diagram of the essential parts of a disk-shaped recording medium and a recording / reproducing apparatus of the present invention, and FIG. 2 is an explanation of FIG. 1 ... PCM modulator, 2 ... MFM modulator, 3 ... synchronization signal modulator, 4 ... gate circuit, 5 ... pilot signal oscillator, 6,9 ... waveform shaper, 7 ... FM demodulator , 8
...... Band filter, 10 ...... Control device, 11 ...... Reference oscillator, 12 ...... Disk drive motor, 13 ...... Disk-shaped recording medium.

Claims (3)

[Claims] 1. A synchronization signal of a modulation system different from that of a data signal is recorded on a meandering track, the distances of the synchronization signal on the disk are substantially equal, and the recording band of the synchronization signal is a recording band of the data signal. A disk-shaped recording medium characterized by being narrower. 2. The method according to claim 1, wherein the synchronization signal part is modulated by an FM signal system in which a predetermined signal is modulated, and the band of the FM signal is narrower than the band of the data signal part for recording. Disk-shaped recording medium. 3. A synchronization signal of a modulation method different from that of the data signal is recorded on the meandering track, the distances of the synchronization signal on the disk are substantially equal, and the recording band of the synchronization signal is the recording band of the data signal. A sync signal detecting means for detecting the sync signal from a narrower disc-shaped recording medium is provided, and the sync signal generated at the output of the sync signal detecting means by comparing the output of the sync signal detecting means with the output of the reference oscillator. A recording / reproducing apparatus provided with a control device for controlling the rotational speed of the disk so that the cycle of the disk becomes constant.