JPS62249593A - Time base correcting device - Google Patents

Abstract

PURPOSE:To eliminate the time base fluctuations of both a luminance signal and a color signal by separating the luminance signal and the color signal of a signal reproduced from a recording medium from each other, and inputting the repective signals to time base correcting circuits via respective limiter circuits. CONSTITUTION:The color signal component frequency-converted to lower band and the luminance signal component frequency-converted to higher band that are recorded in a magnetic tape 1, are reproduced by a magnetic head 2 and amplified 4 to obtain reproduced signals. The reproduced signals are separated into a luminance signal and a color signal through a HPF 4 and a LPF 5 respectively. The luminance signal is inputted to the first limiter circuit 8 and the color signal to an adding circuit 6. In the circuit 6, the color signal and a carrier wave from an oscillation circuit 7 added with each other, and the result is inputted to the second limiter circuit 9. In the circuits 8 and 9 respectively, an amplitude information is converted to a waveform made of only phase information, and the results are inputted to the first time base correcting circuit 10 and the second time base correcting circuit 11 respectively. In the circuits 10 and 11, a reference signal from a reference signal generating circuit 12 and the respective phase informations are phase-compared to detect a time base fluctuation component, and thus the time base fluctuation is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a recording medium in which the chrominance signal component of a video signal is frequency-converted to a low-frequency range, and the luminance signal component is frequency-modulated to a high-frequency range. The present invention relates to a time axis correction device that can be used in a device that reproduces a video signal from a medium.

Conventional technology In conventional consumer VTRs, etc., the color signal component of the video signal is
The luminance signal component is frequency-converted to a low-frequency range, and the luminance signal component is frequency-modulated to a high-frequency range and recorded on a video tape. During reproduction, in the process of converting the frequency of the color signal component converted to the low frequency range back to the original high frequency range, the time axis fluctuation (phase fluctuation) component contained in the color signal component is removed, and the frequency modulated signal is recorded and reproduced. It was added to the luminance signal component and output to the monitor TV receiver. This is because in the recording and reproducing system of a consumer VTR, a certain amount of time axis fluctuation occurs, and because the time axis fluctuation causes the phase of the color signal component to fluctuate significantly, it is necessary to remove that phase. . Furthermore, since the time axis fluctuation component included in the luminance signal component of the video signal has a low frequency, it is removed by the AFC circuit provided in the monitor television receiver. For this reason,
There was no particular need to remove the time axis fluctuations contained in the luminance signal. (For example, one time axis fluctuation and its correction method - Konishi et al., Journal of the Television Society, P495-503, Vol. 3, No. 6 (81)) Problems to be solved by the invention In such conventional consumer VTRs, As mentioned above,
The time axis variation component (phase variation) included in the color signal component is corrected, but the time axis variation component of the luminance signal component is not corrected. Therefore, the color signal component and the luminance signal component have different time axis variation components. This causes deterioration in image quality. In particular, the color signal component also includes a high-frequency luminance signal component of the video signal, and the high-frequency m degree signal component of the video signal has a time axis variation component different from the low-frequency luminance signal component. Therefore, on the monitor television receiver, the high-frequency luminance signal component of the video signal is not effectively used, and there is a problem that it acts as a kind of interference signal.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a method in which the color signal component of the video signal is frequency-converted to the low frequency range, and the luminance signal component is frequency-modulated to the high frequency range and recorded. The reproduced signal is separated from the frequency-modulated recording medium through a filter into the frequency-modulated luminance signal and the frequency-converted chrominance signal, and the frequency-modulated luminance signal is converted into an input signal. and a first time axis correction circuit to which the output signal of the first limiter circuit is supplied, and adds the frequency-converted color signal and carrier wave to the low frequency range. a second limiter circuit to which the output signal of the adder circuit is supplied; and a second time axis correction circuit to which the output signal of the second limiter circuit is supplied, The device is configured to output the removed frequency-modulated luminance signal and the color signal frequency-converted to the low frequency range.

Effect of the present invention With the above-described configuration, the reproduced signal from the recording medium is separated into a frequency-modulated luminance signal and a low frequency-converted color signal through a filter, and the first and second
The limiter circuit converts the reproduced signal into a reproduced signal that is not affected by amplitude fluctuations and inputs it to the first and second time axis correction circuits. First, it is possible to correct the time axis fluctuation component of the reproduced signal. Therefore, time axis variations in the luminance signal and color signal are removed, and luminance signals and color signals without time axis variations can be obtained, and in particular, the high frequency luminance signal included in the color signal can be effectively utilized. Furthermore, the color signal frequency-converted to the low frequency range is an AM-varied #J4 signal, but since the carrier wave is added via the adder circuit and supplied to the second limiter circuit, the amplitude information is converted into phase information. can be converted to .

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of main parts showing the main part configuration of the present invention. On the magnetic tape 1, the chrominance signal component is frequency-converted to a low-frequency range, and the luminance signal component is frequency-modulated and recorded to a high-frequency range. The signal recorded on the magnetic tape is reproduced by the magnetic head 2 and amplified by the amplifier circuit 3 to obtain a reproduced signal. Next, the obtained reproduced signal is separated through a high-pass filter 4 and a low-pass filter 5 into a frequency-modulated luminance signal and a chrominance signal whose frequency is converted to a low frequency. The luminance signal is input to a first limiter circuit 8, and the color signal frequency-converted to the low frequency range is input to an adder circuit 6. The first amplification circuit 8 converts the waveform into a waveform containing only phase information that is not affected by amplitude fluctuations, and supplies the waveform to the first time axis correction circuit 10.

Here, the first time axis correction circuit 10 is configured as shown in FIG.
With Loop C1rcuit), a signal having the same frequency as the reference signal which is the output of the reference signal generation circuit 12 and which is phase-synchronized with the horizontal synchronization signal is used.

The output signal and the reference signal output from the reference ig signal generation circuit 12 are compared in a phase comparator circuit 24 to detect a time axis fluctuation component and input to the delay amount variable circuit 21. The delay amount variable circuit 21 has a delay amount variable circuit 21 as shown in FIG.
The OS inverter circuit 35 is connected in multiple stages, and the amount of delay changes by controlling the power supply line INI.

Therefore, the delay amount of the variable delay amount circuit 21 changes according to the time axis fluctuation detected by the phase comparator circuit 24, thereby correcting the time axis fluctuation of the frequency-modulated luminance signal. On the other hand, the color signal inputted to the adder circuit 6 and frequency-converted to a low frequency band is added to the carrier wave of a single frequency which is the output of the oscillation circuit 7 (the frequency spectrum diagram shown in FIG. 2 + al is obtained. However, , Cam is a color signal whose frequency has been converted to a low frequency band, and Cw is a carrier wave).

Next, the output of the adder circuit 6 is supplied to a second limiter circuit 9. The second limiter circuit 9 converts amplitude information into phase information. In principle, when a carrier wave containing amplitude information as shown in FIG. 3 [al] is passed through the limiter circuit 5, a waveform as shown in FIG.

Therefore, amplitude information is converted to phase information. Also, when looking at this on the frequency axis, the input waste vector changes from Figure 2 (al) to Figure 2 (bl) (Cam, C'a
mH low-pass converted color signal, Cw; indicates carrier wave).

Here, it can be seen that the power of the low frequency converted color signal Cam in FIG. 2(4) is decomposed into two C'am as shown in FIG. 2cb). Therefore, the power difference between Cam and C'am is 6 dB. If it were assumed that the noise shown in FIG. 2(a) was white noise, the S/N would deteriorate by 6 dB. but,
Since the low-pass filter 5 is inserted, high-frequency noise components are removed, so there is no S/H deterioration in the second limiter circuit 9. If the amount of attenuation is insufficient, it can be improved by inserting a trap circuit at the frequency position of the high frequency band C'am of cb+ in FIG. Next, the output of the second limiter circuit 9 in which the amplitude information is converted into phase information is input to the time axis correction circuit 11. As shown in FIG. Delay variable circuit 26. Burst wave separation circuit 2
7. PLL circuit (Phased Locked Loo)
pC1rcuit) 28, phase comparison circuit 29
．． It consists of a reference signal generation circuit 12, a burst wave separation circuit 27 separates the burst waves in the color signal, and a PLL circuit (Phased Locked loop C1rcu).
it ) 28, phase-locked to the burst wave,
A signal having the same frequency as the reference signal output from the reference signal generation circuit 12 is used. The reference signal which is the output of the reference signal generation circuit 12 is
The phase comparator circuit 29 compares the signals, detects the time axis fluctuation component, and inputs the resultant signal to the delay amount variable circuit 26. The delay amount variable circuit 26 is configured as shown in FIG.
5 is connected in multiple stages, and the amount of delay changes by controlling the power supply line rN1.

Therefore, the delay amount of the variable delay amount circuit 26 changes according to the time axis fluctuation detected by the phase comparator circuit 29, and the time axis fluctuation of the color signal frequency-converted to the low frequency band is corrected. The frequency-modulated luminance signal whose time axis has been corrected and the chrominance signal whose frequency has been converted to a low frequency band are conventionally used in a consumer VTR, where the luminance signal is FM demodulated and the chrominance signal is converted to a high frequency band. By adding them together, the original video signal is restored and a video signal with no time axis fluctuation is obtained. Therefore, by configuring as in this embodiment, it is possible to obtain signals without temporal axis fluctuations for both the color signal and the luminance signal.

Furthermore, the reason why the reference signal generation circuit 12 is the same in the first and second time axis correction circuits is to achieve phase synchronization between the frequency-modulated luminance signal and the frequency-converted chrominance signal. be.

Furthermore, by configuring the first and second time axis correction circuits as shown in FIG. 6, it is possible to change the control loop type from a feeder type control loop to a feeder type control loop type. .

In addition, the delay amount variable circuit is a CCD (charge coupled device)
It is also possible to use other variable delay amount circuits such as .

Furthermore, by using the time axis correction device of this embodiment in a consumer VTR, it is possible to eliminate the phase control loop type of time axis correction that was conventionally performed when converting a color signal from a low frequency range to a high frequency range. .

Furthermore, in this embodiment, the burst wave and the horizontal synchronization signal are separated to detect the time axis fluctuation component, but a separate head may be provided to record the detection signal, or the same head may be used to record the detection signal. may be frequency multiplexed. Further, the delay amount of the delay amount variable circuit may be controlled using a time axis error signal of a servo circuit that controls the cylinder motor of a consumer VTR.

Effects of the Invention As described above, according to the present invention, both the color signal and the luminance signal can be made signals with no time axis fluctuations, and in particular, the high-frequency luminance signal component included in the color signal can be made effective. It can be used for. Furthermore, since a low-pass filter is inserted, there is no S/N deterioration, and amplitude information can be converted into phase information using a limiter circuit. Also,
By using the time axis correction device of this embodiment in a consumer VTR, it is possible to eliminate the phase control loop type of time axis correction conventionally performed when converting a color signal from a low frequency band to a high frequency band. Furthermore, since the luminance signal and the color signal are time-base corrected separately, no interference occurs between the two signals, and a good reproduced video signal can be obtained, which is extremely useful.

[Brief explanation of drawings]

Fig. 1 is a block diagram of essential parts of an embodiment of the present invention, Fig. 2 is a frequency spectrum diagram showing the principle of the invention, Fig. 3 is a waveform diagram showing the principle of the invention, and Fig. 4 is a diagram showing the principle of the invention. FIG. 5 is a block diagram of the main part showing the time axis correction circuit; FIG. 5 is a block diagram of the main part showing the variable delay amount circuit of the present invention; FIG. 6 is a block diagram of the main part showing the time axis correction circuit of the present embodiment. . ■...Magnetic tape, 2...Magnetic head, 3...Amplification circuit, 4...High pass filter, 5...Low Pass filter, 6...
...Addition circuit, 7...Oscillation circuit, 8...
・First limiter circuit, 9...Second 9177
Circuit, IO...First time axis correction circuit, 11.
...Second time axis correction circuit, 12...Reference signal generation circuit, 21...Delay amount variable circuit, 2
2...Horizontal synchronization separation circuit, 23...P
LL circuit, 24... Phase comparison circuit, 26...
...Delay amount variable circuit, 27...Burst wave separation circuit, 2B...PLL circuit, 29...
・Phase comparison circuit, 35...CMOS inverter circuit, 41...Horizontal synchronization or burst wave separation circuit, 42...PLL circuit, 43...
・Phase comparison circuit, 44...Delay amount variable circuit, 4
5...Reference signal generation circuit. Name of agent: Patent attorney Toshio Nakao
2 Ward Te-kuFigure 2Figure 3Figure 4

Claims (3)

[Claims] (1) A playback signal is reproduced from a recording medium in which the color signal component of the video signal is frequency-converted to the low frequency range, and the luminance signal component is frequency-modulated to the high frequency range, and is recorded through a filter. , a first limiter circuit that separates the frequency-modulated luminance signal and the frequency-converted chrominance signal into a low frequency range, and receives the frequency-modulated luminance signal as an input signal; and an output of the first limiter circuit. a first time axis correction circuit to which a signal is supplied; an adder circuit for adding the color signal frequency-converted to the low frequency band and a carrier wave; and a second limiter to which the output signal of the adder circuit is supplied. circuit and said second
and a second time base correction circuit to which the output signal of the limiter circuit is supplied. (2) The first time axis correction circuit includes a variable delay amount circuit, a horizontal synchronization separation circuit, a PLL circuit, and a reference signal generation circuit.
The time base correction device according to claim 1, characterized in that it is constituted by a phase comparison circuit. (3) The second time axis correction circuit is comprised of a variable delay amount circuit, a burst wave separation circuit, a PLL circuit, a reference signal generation circuit, and a phase comparison circuit. The time axis correction device described in section 1).