JPS5925432B2 - Audio circuit time base correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a time base correction device for an audio circuit.

More specifically, in a video disc player, when the rotational speed fluctuates due to uneven rotation of the motor, eccentricity of the video disc, vibration of the pickup, etc., a time axis error signal is generated, and this time axis error signal is supplied to the speaker. Then, a rumbling sound occurs. The present invention was made in order to eliminate audio disturbances caused by such time axis fluctuations, and extracts a time axis error signal from a final image signal reproduced from a video disc and combines it with the output signal of an audio demodulator. By subtracting the time-base error signal, an audio signal that does not include the time-base error signal is obtained.

Therefore, no audio disturbance occurs in the reproduced sound. An embodiment of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes an input terminal for an audio signal among signals detected by a pickup from a video disk rotating at high speed.

Further, 2 is an input terminal for a video signal (line sequential signal).
One input terminal 1 is connected via a bandpass filter 3 to
Phase detector 4 and voltage controlled oscillator (hereinafter referred to as vCo) 5
It is further connected to an output terminal 8 via a subtracter 1.

The other input terminal 2 is connected via a synchronization separation circuit 9 to a time-base error signal detection circuit 13 configured by a PLL circuit consisting of a phase detector 10, a low-pass filter 11, and a VCO 12, and further connected to a phase detector 13. 10 is connected to the subtracter T via a low-pass filter 14 and a phase shifter 15.

Next, the operation of the present invention will be explained. When the FM carrier signal reproduced from the video disc enters the audio signal input terminal 1, the audio FM carrier signal is extracted by the bandpass filter 3, and the audio signal is demodulated by the phase detector 4 and VC05. Ru.

A video demodulator (not shown) is connected to the other video signal input terminal 2.
A video signal reproduced by the synchronization separation circuit 9 is input, and a composite synchronization signal is extracted by the synchronization separation circuit 9.

This composite synchronization signal is synchronized with the oscillation frequency of the VCO 12 of the PLL circuit 13. However, the played FM
If the carrier signal has time axis error fluctuations, the audio signal obtained by the audio demodulator 6 will include the time axis error signal.

For example, in a TED video disc player, the time axis error signal has a frequency of 30 Hz, 160 Hz, and 1360 Hz, and often causes trouble in the audio circuit. Such a time axis error signal also appears at the output of the phase detector 10 of the PLL circuit 13, and this is transmitted to the low pass filter 1.
4, the phase shifter 15 aligns the phase with the audio output and sends it to the subtracter 7.

The subtracter 7 subtracts the time axis error signal including the audio signal from the audio demodulator 6 and the time axis error signal from the phase shifter 15, so that the output terminal 8 receives the time axis error signal. Only the erased audio signal is obtained. As described above, the present invention uses a subtracter to eliminate the time axis error signal from the audio signal including the time axis error signal obtained by the audio demodulator, and only the audio signal is left. No disturbance to audio will occur.

In particular, TED video disc players completely eliminate audio disturbances caused by frequencies such as deviation due to the frequency of one frame being 30Hz, 60Hz that appears to occur during disc cutting, and 360Hz that appears to occur from the motor rotation system. It will be resolved.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of a time base correction device for an audio circuit according to the present invention. 1...Audio signal input terminal, 2...Video signal input terminal, 3...Band pass filter, 4
... Phase detector, 5 ... VCO, 6.
...Audio demodulator, 7...Subtractor, 8...
...Output terminal, 9...Synchronization separation circuit, 10
... Phase detector, 11 ... Low pass filter, 12 ... VCO, 13 ... Time axis error signal detection circuit, 14 ... Low pass filter, 15... phase shifter.

Claims (1)

[Claims] 1. A device comprising an audio demodulator for demodulating an audio signal from a reproduced carrier signal and a detection circuit for detecting a time axis error signal, wherein the audio demodulator is coupled to a subtracter, and the detection circuit A phase detector is coupled to the subtracter via a low-pass filter and a phase shifter for aligning the phases of the output of the audio demodulator and the output of the low-pass filter, and the subtracter performs audio demodulation. 1. A time axis correction device for an audio circuit, characterized in that a time axis error signal is deleted from an output signal of an audio circuit to obtain only an audio signal.