JPS6052495B2 - disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disc playback device, which is capable of playing a disc (hereinafter referred to as an audio disc) on which information signals such as audio signals are recorded with high density, and on which video signals and audio signals are recorded with high density. It is an object of the present invention to provide a disc playback device (player) for a video disc that can perform playback while maintaining a normal rotational speed during playback.

Conventionally, in the video signal band of video discs on which video signals and audio signals are recorded with high density, there are also audio discs on which audio signals of one or more channels are recorded with high density.

This audio disc is placed on the turntable of a video disc player and rotated, from which audio signals can be picked up from the audio disc. However, many of the above-mentioned video disc players employ a rotation servo system that detects horizontal synchronization signals and color burst signals and controls the disc to maintain a constant rotational speed. In this case, it is not possible to control the rotation of the audio disc, and therefore the number of rotations cannot be kept constant. However, there was a drawback that information signals such as audio cannot be recorded during the recorded horizontal synchronization signal period.

i The present invention aims to eliminate the above-mentioned drawbacks, and each embodiment thereof will be described below with reference to the drawings.

FIG. 1 shows a block diagram of one embodiment of an audio disc recording device reproduced by the apparatus of the present invention.

In the figure, audio signals input from input terminals 1a and 1b are supplied to modulators 3a and 3b via amplifiers 2a and 2b, respectively, where carrier waves of different frequencies from carrier wave oscillators 4 and 5 are modulated. The modulated audio signals taken out from the modulators 3a and 3b are supplied to a mixer 6, where they are mixed, and then supplied to a cutting head 8 via an amplifier 7, where they are recorded on a disk 13. On the other hand, this disk 13 is placed on a turntable 14 driven by a motor 12 and rotated, and its rotational speed is detected by a rotational speed detection circuit 11. The output of this rotational speed detection circuit 11 is supplied to a phase comparator 10, where the phase is compared using a signal obtained by counting down the output of the carrier wave oscillator 5 in a countdown circuit 9 as a reference signal. The output of the phase comparator 10 controls the rotation speed and phase of the motor 12 so that the rotation speed is always constant. By the way, in one embodiment of the device of the present invention, at least one of the output carrier frequencies of the carrier wave oscillators 4 and 5 is selected to be approximately an integer multiple of ↓ of the horizontal synchronization frequency of the standard television signal. be.

In the above embodiment, the audio channels are two channels, but the invention is not limited to this, and the amplifier 2a
By providing an arbitrary number of circuits similar to the circuit consisting of one modulator 3a and carrier wave oscillator 4, it is possible to record an arbitrary number of channels. it is obvious.

FIG. 2 shows a block diagram of an example of a video disc player for playing back audio discs recorded by the apparatus of the present invention.

In the figure, 13'' is a disk, and the signal recorded by the pick-up needle 15 is picked up and supplied to the head amplifier 16, where it is amplified.Here, we will first explain the case where the disk 13'' is a video disk. . The FM modulated waves of, for example, color video signals and audio signals taken out from the head amplifier 16 and recorded on the video disk are sent to the audio FM detection circuit 17 and the audio amplifier circuit 1.
While only the audio signal is played back after passing through the video FM
The signal is supplied to a detection circuit 19, where it is subjected to FM detection and converted into a video signal, and then supplied to a luminance separation circuit 20, a chroma separation circuit 23, and a synchronization signal separation circuit 22, respectively.

The luminance signal separated by the luminance separation circuit 20 is supplied to a video amplifier 25, which will be described later, via a luminance amplifier 21. Further, the horizontal synchronization signal separated by the synchronization signal separation circuit 22 is supplied to the burst extraction pulse generation circuit 26, where it is made into a burst extraction pulse, and then supplied to the burst gate circuit 27, where it is output from the chroma separation circuit 23. For example, from the reproduced carrier color signal of 3.58
r1! Extract the 4HZ color burst signal. The color burst signal from the burst gate circuit 27 is supplied to a phase/frequency comparator 29 via a switch 28 which is connected to the fixed contact a side, and is then connected to the 3.58 MHz output from the crystal oscillator 32. The phase (or frequency) is compared.

Here, the switch 28 has fixed contacts A and b, respectively, and as will be described later, the output side of the switch 28 is connected to the fixed contact b, and together with the carrier wave averaging circuit 31, an audio disc recorded by the apparatus of the present invention is used. It is designed to reproduce. The error voltage extracted from the phase/frequency comparator 29 is supplied to a voltage controlled oscillator VCO3O having a center frequency of, for example, 5.11 MHz, and controls its output oscillation frequency.

The output of this VCO3O is supplied to the chroma separation circuit 23, where the output from the video FM detection circuit 19 is, for example, band 1.
~2MHz signal to 3.58r1-4Hz±500KH
Convert the frequency to a z signal. This frequency-converted signal is extracted by a notch filter using a 1H delay line, separating only the carrier color signal from the luminance signal.
Bandwidth 3.58MHz±5 from this chroma separation circuit 23
The reproduced carrier color signal of 00 KHz is supplied to the video amplifier 25 through the chroma amplifier 24, where it is band-sharing multiplexed with the luminance signal from the luminance amplifier 21, amplified, and output as a reproduced color video signal. In the above video disc player, the output of the phase/frequency comparator 29 controls the output oscillation frequency of the VCO3O and is also supplied to a well-known rotation control circuit 33, for example as shown in Japanese Patent Laid-Open No. 50-240-2. turntable (
It is possible to perform rotation servo of the arm stretcher (not shown) and servo of the arm stretcher (not shown). Next disk 1
The case where 3'' is an audio disk will be explained.

When this disc 13'' is played back by the video disc player mentioned above, the switch 28 is switched to the fixed contact b side.Here, the audio disc in the device of the present invention has a carrier wave of at least one channel as described above. The frequency is recorded as an integer multiple of the horizontal synchronization frequency of the standard television signal (3.58 MHZ in this case). Therefore, the carrier wave of at least one channel recorded on the audio disks 13'', 13. The audio signal (modulated wave) with a frequency of 3.58 MHz is supplied via the head amplifier 16 to a carrier wave averaging circuit 31 having a known configuration as shown in, for example, Utility Model Application No. 50-25418. Only a 3.58 MHz carrier wave having a frequency fluctuation component based on is obtained, and is further supplied to a phase/frequency comparator 29 via a switch 28,
The output of the crystal oscillator 32 is 3.5? Hz and phase (or frequency) are compared.

The output of the comparator 29 controls the rotation of the turntable and the movement of the arm stretcher, and keeps the relative speed between the disk 13'' and the pick-up needle 15 at a predetermined constant speed. The disc can be played back at a predetermined rotation speed without wow or flutter.The video disc player described above detects the color burst signal and performs rotation servo, etc.
In a player that performs rotation servo or the like using a horizontal synchronizing signal as another method, the audio disc can be played back by counting down the carrier wave of the audio disc to the horizontal synchronizing frequency. In another embodiment of the device of the present invention, the carrier frequency of at least one channel of the audio disk may be adjusted to the horizontal level of two or more different standard television signals such as the CCIR system (European standard television system) or the NTSC system. The least common multiple of each approximate value of the synchronization frequency (for example, CCIR method 15.6
25KHz,. In the case of NTSC system 15.75 KHz, it is selected as an integral multiple of 1.96875 MHz).

This allows common playback on any video disc player by changing the countdown ratio. As described above, the disc playback device according to the present invention records an FM-modulated audio signal on one or more channels, and synchronizes the carrier frequency of at least one of the channels with the horizontal synchronization of a standard television signal. An audio disk recorded at approximately an integer multiple of the frequency curve is placed on a playback device that can also be used as a video disk, and when this audio disk is played back, the carrier wave frequency signal of the played modulated audio signal is used as a reference. Since the rotational speed of the audio disc is controlled by comparing it with the frequency signal, by detecting the carrier wave frequency, the audio signal can be detected in a video disc player that performs rotation servo, etc. using a horizontal synchronization signal or a color burst signal. can be reproduced without wow or flutter at a predetermined rotational speed, and the carrier frequency of at least one of the channels is selected to be approximately an integer multiple of the least common multiple of each of the horizontal synchronizing frequencies of two or more different standard television signals. By recording this signal, it can be played back in common by changing the countdown ratio on any video disc player that plays back any one of the standard television signals mentioned above, and it is also possible to play back an audio disc on a video disc player. ), since there is no need to record the horizontal synchronization frequency itself on the disk, the period of the horizontal synchronization signal can also be effectively used as a period for recording information signals such as audio, and the disk surface is used more efficiently. It has characteristics.

[Brief explanation of the drawing]

Fig. 1 is a block system diagram of one embodiment of the device of the present invention;
The figure is a block diagram of an example of a video disc player for playing back a disc on which information signals such as audio are recorded by the apparatus of the present invention. 3a, 3b...Modulator, 4,5...Carrier wave oscillator,
6... Mixer, 10... Phase comparator, 11... Rotation speed detection circuit, 13, 13''... Disk, 17...
Audio FM detection circuit, 18...Audio amplifier circuit, 19...
・Video FM detection circuit, 27... Burst gate circuit, 28... Switch, 29... Phase/frequency comparator,
30... Voltage controlled oscillator (VCO), 31... Carrier wave averaging circuit, 32... Crystal oscillator, 33... Rotation control circuit.

Claims (1)

[Scope of Claims] 1. An FM modulated audio signal is recorded on one or more channels, and the carrier frequency of at least one of the channels is set to approximately 1/2 of the horizontal synchronization frequency of a standard television signal. An audio disc recorded at an integer multiple is placed on a playback device that can also be used with a video disc, and when playing the audio disc, the carrier wave frequency signal of the reproduced modulated audio signal is compared with the reference frequency signal. A disc playback device characterized in that the rotational speed of the audio disc is controlled by: 2. An FM modulated audio signal is recorded on one or more channels, and at least one carrier frequency of the channel is set to the least common multiple of the respective approximate values of the horizontal synchronization frequencies of two or more different standard television signals. When an audio disc recorded with an integral multiple of 1 is placed on a playback device that can also be used with a video disc, the carrier frequency signal of the reproduced modulated audio signal is used as the reference frequency signal when the audio disc is played back. A disc playback device characterized in that the rotation speed of the audio disc is controlled by comparison.