JPS6333409Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in a video disc player, which transmits a television audio multiplex signal stored on a video disc, and preferably transmits a control channel signal constituting the television audio multiplex signal. It is an object of the present invention to provide a player capable of operating a jitter correction circuit using a control signal carrier wave.

Conventional video discs use two different carrier waves to record two channels of audio signals, so the player that plays them requires a playback system for the two channels. In order to provide this signal to a television receiver equipped with a reception function, it is necessary to further multiplex the reproduced two-channel audio signal. Therefore, the present invention has developed a player that can transmit the two channels of audio signals using a single channel playback system by storing two channels of audio signals on a video disk in a format similar to a television multiplexed signal. The present invention is intended to eliminate the above-mentioned drawbacks.

Another object of the present invention is to provide a player which is equipped with a jitter correction circuit responsive to a control signal carrier and whose frequency characteristics for jitter detection can be improved compared to those based on conventional horizontal synchronization signals.

First, the transmission form of two channels of audio signals to be recorded on a video disc will be explained with reference to FIG. As shown in the figure, similar to the well-known television audio multiplex signal, each recorded program is provided with a main channel signal 1, a sub-channel signal 2, and a control channel signal 3. When the transmission signal is a stereo program, the signals that make up this multiplexed signal include a sum signal, an FM difference signal, and an AM first signal.
The control signal is 982.5Hz, and if the transmission signal is a different type of program, the main signal, FM sub signal, and
The second AM control signal is 922.5Hz. In addition, when the transmission signal is a monaural program, in addition to the well-known monaural signal, a control signal carrier of 55.125 kHz is transmitted in the present invention, although it is not transmitted by a normal television audio multiplex signal. As shown in FIG. 2, this audio multiplex signal is modulated below the FM band of the television signal, multiplexed, and stored on a video disk. In the figure, 4 is the shift band of the television signal, 5 is the lower sideband, and 6 is the band of the modulated television audio multiplex signal (for example, 0.7
~0.9MHz).

FIG. 3 shows a schematic block diagram of a player for reproducing signals stored on this video disc. The signals on the disk 7 are transmitted to a pickup 8 in a well-known manner and converted into electrical signals. The converted signal is divided into two parts via a preamplifier 9, and one is transmitted to a video processing system 10 and the other to an audio processing system 11. The video processing system 10 forms a standard television signal using a decoding method equivalent to the inverse conversion of the encoding method used for recording on the disk, and applies the output to the RF modulator 12. .
The audio processing system 11 also includes a band pass filter 13,
Equipped with an FM demodulator 14 and an amplifier 15,
The above-mentioned modulated television audio multiplex signal is separated and extracted, and the television audio multiplex signal obtained by demodulating the signal is amplified and applied to the RF modulator 12. The RF modulator processes the two inputs described above so that they are suitable for input to the antenna circuit of the television receiver 16. In this way, this video disc player, which has a transmission path from the pickup 8 to the RF modulator 12, does not require a two-channel transmission path in order to transmit two channels of audio information, unlike conventional devices. savings can be realized. It goes without saying that if the television receiver 16 is equipped with a decoder for television audio multiplexed signals, the audio signals of two channels on the disc can be taken out as its output.

The player of the present invention is equipped with a filter 17 for separating the control signal carrier from the output of the FM demodulator 14, and a circuit 18 for detecting jitter based on the output of this filter. This is done to offset the jitter. The general jitter detection method detects the horizontal synchronization signal that makes up the television signal.
This is applied to the PLL circuit to detect jitter components, but in reality, jitter at low frequencies (several Hz to several 100 Hz) is sufficiently detected, but jitter at high frequencies (for example, 500 Hz to 1 kHz) is detected. Jitter is relatively difficult to detect. However, in the present invention where the control signal carrier is the signal source, the carrier frequency is 3.5 times the horizontal synchronization signal frequency, so
We can expect demodulation characteristics corresponding to this. Therefore, high frequency jitter components can be detected and corrections can be made based on the detection.

[Brief explanation of drawings]

Figure 1 is a frequency spectrum diagram of a television audio multiplex signal, Figure 2 is a frequency spectrum diagram of a signal recorded on a video disk, and Figure 3 is a diagram of the frequency spectrum of a signal recorded on a video disc.
FIG. 2 is a schematic block diagram of an embodiment. 1...Video disk, 8...Pickup,
10...Video processing system, 11...Audio processing system, 1
8...Jitter detection circuit.

Claims (1)

[Scope of utility model registration request] FM modulated television audio multiplex signal and video signal obtained by modulating a television audio multiplex signal composed of main, sub, and control channel signals.
a pick-up for extracting both signals from a video disc on which a modulated FM video signal is multiplexed and recorded; a filter circuit for separating the modulated television audio multiplex signal from the pick-up output; and a filter circuit for separating the modulated television audio multiplex signal from the output of the pick-up; a circuit for demodulating a digital audio multiplex signal; a video processing circuit for forming a standard video signal from the FM video signal from the pickup output and including a jitter correction circuit; and outputs from the demodulation circuit and the video processing circuit. an RF modulation circuit for introducing a carrier television signal to form a carrier television signal, and the jitter correction circuit is configured to be controlled by a jitter component inherent in a control signal carrier constituting the control channel signal. disk player.