JPS5851351B2 - Saisei Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a playback device capable of playing back both audio discs and video discs.

As is well known, conventional audio discs have a track width of 2.
Sound is recorded as an analog signal on both side walls of a V-groove of about 0 to 50μ door size.

Although high-density analog recording has been achieved in the form of a four-channel system, and the degree of freedom of musical expression has increased, the quality of sound reproduced from discs is still unsatisfactory in terms of dynamic range, distortion, etc.

On the other hand, research and development of video discs on which video signals are recorded is progressing, and various systems have been proposed so far.

However, conventional video disk playback devices and audio disk playback devices are not compatible with each other, requiring the use of dedicated devices for each.

The present invention has been made in view of the above problems, and is designed to encode an audio signal, and to enable a disc on which the encoded signal and a synchronization signal are recorded to be played back as a video disc.

The present invention will be explained below.

An example of a conventional video disc is one in which a video signal including a synchronizing signal is FM-modulated and this FM signal is recorded.

Also, as a playback device, ■. Items that utilize changes in the amount of light reflected and transmitted, ■.

They are broadly divided into those that utilize changes in capacitance, those that utilize mechanical energy, and so on.

The rotation speed of the disk is 1800 r-pom, ■
are 45 Or, p, m.

Furthermore, as for the material of the disks, a part of the symbol (2) and a rigid disk are used, and a flexible disk is used for the other portion of the symbol (2).

For such video discs, the signal playback band is 6M.
You can expect about Hz.

On the other hand, when encoding an audio signal as a PCM signal, for example, if the video signal band is used to convert it into a PCM signal of about 15 pits and record it, a dynamic range of about 90 dB can be secured. .

In the case of music, this value is approximately equal to the actual dynamic range.

In addition, by encoding the audio signal, unlike conventional analog audio discs, there is a delicate relationship between the characteristics of the recorded signal and the characteristics of the converter system such as a pickup, and due to uneven rotation of the turntable, etc. Deterioration in sound quality can be completely eliminated.

Next, the frequency band required to encode the audio signal and record it on a disc will be roughly estimated.

To set the audio signal band from 0 to 15 KHz and obtain a dynamic range of about 90 dB with 15 bits including both side bands, 15 KH for one channel is required.
z XI 5
= 1.8 MHz.

Therefore, if the 6 MHz video signal reproduction band is used, it becomes possible to record three 4-channel signals, a total of 12 channels.

As signal processing techniques advance and the signal band per channel decreases, it goes without saying that the number of channels that can be recorded on a disc will increase.

Next, an example of a recording device will be described.

In FIG. 1, when recording a video signal, the video signal from signal source 1 is sent to FM via contact 3 of switch 2.
In addition to the modulator 4, this FM signal is converted into an optical signal by an optical modulator 5, and further converted into a laser beam 7 by a laser device 6.

This laser beam I is recorded on a master disc 12 rotated by a motor 11 via a lens 8, a mirror 9, a lens 10, etc.

The surface of this master 12 is coated with photoresist.
A video signal is recorded by being exposed to laser light 7 modulated with an FM signal.

Next, when recording an audio signal, the audio signal from the sound source 13 is encoded by the A/D converter 14 to form, for example, a PCM signal.

At this time, a synchronization signal is inserted.

For example, when recording four channels of audio signals in series, this synchronization signal may be inserted immediately before each recording of the first channel.

The PCM signal with the synchronization signal inserted is connected to contact 1 of switch 2.
5 to the FM modulator 4 to form an FM signal, and in the same manner as described above, it becomes a laser beam 7 and is transmitted to the master 12.
FM signals are recorded on.

As another method of recording audio signals, as shown by the dotted line in FIG.
The PCM signal may be directly recorded on the master disc 12 by adding the PCM signal to the master disc 12.

Next, an embodiment of the reproducing device according to the present invention will be described.

FIG. 2 shows the first embodiment, in which the audio signal is converted into PCM
This is for playing back audio discs and video discs that have been recorded after being FM modulated.

In FIG. 2, switches 20 and 2L22 are connected to disk 2.
If 3 is a video disc, it is closed to the contact V side,
In the case of an audio disc, the contact point a is closed.

F played by the pickup 24 from the disk 23
The M signal is applied to a preamplifier 25.

This pickup includes, for example, a laser light source 26, a lens 2
7, 28, a mirror 29, a photoelectric converter 30, etc., the light from the light source 26 is irradiated onto the track of the disk 23 via the mirror 29 and the lens 27, and the reflected light is transmitted to the lens 27, the mirror 29, the lens 28. It is converted into an electrical signal by applying it to the photoelectric converter 30 via the photoelectric converter 30.

The FM signal output from the preamplifier 25 is corrected for signal characteristics during recording by an equalizer 31, limited in amplitude by a limiter 32, and then demodulated by an FM demodulation circuit 33.

This demodulated signal is applied to the switch 21 after its frequency characteristics are corrected by a defunct system 34.

When the disc 23 is a video disc, the demodulated signal is applied to the video output circuit 35 via the contact V of the switch 21, and the video signal is taken out from the output terminal 36.

At the same time, the demodulated signal is also applied to the synchronization separation circuit 37 to extract a synchronization signal, and this synchronization signal is applied as a servo signal to the rotation control circuit 38 via the contact V of the switch 22, and its output The rotation speed of the disk rotation motor 39 is controlled by the control signal.

Further, the synchronization signal is also applied to the tracking and focusing control circuit 40 via the contact V of the switch 20, and the output control signal controls the movement of the pickup 24 in the radial direction with respect to the disk 23 and the focus control of the lens system.

If the disc 23 is an audio signal, switch 2F
The demodulated signal applied to is sent to the synchronous separation circuit 4 via contact a.
Added to 1.

A demodulated signal from which the synchronization signal has been removed is taken out from the synchronization separation circuit 41, and this signal is added to the buffer memory 42, and only the synchronization signal is extracted, and this synchronization signal is sent to the control circuit 38 via the switch 20. 40, the rotation speed of the motor 39 and the tracking and focusing of the pickup 24 are controlled as described above.

Along with this, the synchronization signal is transmitted to the clock pulse generation circuit 43.
is also added to drive this.

From this clock pulse generation circuit 43, the disk 230
A write clock pulse corresponding to the rotational unevenness is obtained, and the demodulated signal from which the synchronization signal is removed is applied to the buffer memory 42 based on the write clock pulse, which is then sampled and sequentially stored.

On the other hand, a read clock pulse of a predetermined frequency is obtained from the standard oscillator 44, and the signals stored in the buffer memory 42 are sequentially read out using the read clock pulse, and the read signals are corrected for bit errors, dropouts, etc. in the correction circuit 45. Thereafter, it is applied to a D/A converter 46 and converted into an original analog audio signal based on clock pulses from the standard oscillator 44.

This audio signal is extracted from an output terminal 48 via a low-pass filter 47.

According to the above configuration and operation, when playing a video disc and an audio disc, the pickup 24
, preamplifier 25, equalizer 31, limiter 32, F
M demodulation circuit 33, de-emphasis 34, control circuit 38,
40 and motor 39 can be used together.

Also, if the storage capacity of the buffer memory 42 is set as a dog,
It is also possible to omit the servo of the motor 39 during audio disc reproduction.

It is also possible to insert a discrimination signal into the disc 23 to determine whether it is an audio disc or a video disc. In that case, discrimination signal detection circuits 49 and 50 are provided separately, and the switches 20 and 21 are activated based on this detection signal. , 22 can be automatically switched.

This automatic switching can also be performed by a synchronization signal.

FIG. 3 shows the second embodiment, and in FIG. 1,
This is for playing back audio discs and video discs in which audio signals are recorded without FM modulation through the path shown by the dotted line, and the same parts as in Figure 2 are given the same reference numerals. be.

In this case, the switch 21 is provided after the preamplifier 25, and the pickup 2
The PCM signal obtained from the switch 21 is applied to the synchronization separation circuit 41 via the audio equalizer 51 via the contact a of the switch 21.

The circuit configuration and operation for obtaining the video signal from the FM signal from the video disk obtained through the V contact of the switch 21 and the circuit configuration and operation after the sync separation circuit 41 are the same as those shown in FIG.

Further, in this embodiment, the pickup 24, the preamplifier 2
5. The control circuit 38°40 and the motor 39 can be used in common.

According to the first and second embodiments described above, since the video signal playback band is used when playing the audio disc,
As mentioned above, if the number of audio channels is set to 12, for example,
Can be increased to channel and width.

Also, output the audio signal to a track with the same width as the video track.
If you turn it into a commercial and record it on 4 channels, the rotation speed of the disc will be lowered to 10~+ than when recording a video, and the playback time will be 3~4.
You can also double it.

Furthermore, if the recording time is the same as that of an analog disk, it becomes possible to significantly reduce the size of the disk.

Note that when the number of channels is limited as described above, it is difficult to achieve stable rotation due to the air bearing effect if a flexible disk is used, so a rigid disk is preferable in this case.

If the rotational speed is the same as that of a video disc, the playing time will be shorter, but the signal band will be expanded, so more than 12 channels will be recorded serially in time.

Therefore, the recorded contents of the disc can be reproduced in various states by electrically selecting the audio signal of each channel, or by appropriately accessing and selecting the pickup.

For example, it is possible to realize various usage modes, such as long-time disk play, simultaneous multi-channel play, specified performance of a program by specifying an address for music execution, and specified continuous play.

In the present invention, a disc on which an encoded audio signal including a synchronizing signal is recorded and a disc on which a video signal including a synchronizing signal is recorded are separately rotated by the same motor, turntable, or other rotary drive body. The recording signals are reproduced by a detection mechanism disposed facing the disk, and the rotational speed of the rotary drive body is detected as an audio signal or a video signal based on a synchronization signal in the reproduction signal. Since it is controlled to be suitable for playback, dynamic range, distortion, etc. are improved, and sound quality can be greatly improved. At the same time, sound quality deterioration caused by the mass production process of discs and differences in playback equipment can be avoided. ,
The degree of change is also minute, and the various usage modes described above can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a recording apparatus, FIG. 2 is a block diagram showing a first embodiment of the present invention, and FIG. 3 is a block diagram showing a second embodiment. In the symbols used in the drawings, 23 is a disk, 24 is a pickup, 37 is a synchronous separation circuit, 38 is a rotation control circuit, and 41 is a synchronous separation circuit. 39 is a motor,

Claims (1)

[Claims] 1 A disk on which an encoded audio signal including a synchronization signal is recorded and a disk on which a video signal including a synchronization signal is recorded are rotated separately by the same rotary drive body, and each of the above The recording signal is reproduced by a detection mechanism disposed facing the disk, and the rotation speed of the rotary drive body is controlled to be suitable for reproduction of audio signals or video signals based on a synchronization signal in the reproduction signal. A playback device characterized by: