JPS63256090A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To transmit a 2-channel video signal without causing any difference in characteristic by constituting the titled device by 2 sets of FM modulation circuits, an error detection circuit detecting the characteristic difference between the channels and an error correction circuit correcting the characteristic difference. CONSTITUTION:A reproducing circuit section 5 inputs a luminance signal Y and a chrominance signal C, a horizontal synchronizing signal is separated from a horizontal synchronizing signal separator circuit (HSS) 8 and supplied to an FF 9. A channel switcher 10 receives the signals Y, C and an output signal of an FF 8 is supplied to a control terminal and a signal shown in figures F, G is obtained, each signal is subjected to FM modulation by FM modulators 11, 12 and the result is supplied to an electromagnetic transducing section 6 and an error detection circuit 13. If only the center frequency of both FM modulators is deviated, the detection circuit 13 detects a DC level difference appearing at each nH at a sample point, the result of detection is inputted to an error correction circuit 14 to adjust automatically the center frequency of both the FM modulators.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal recording and reproducing apparatus such as a video tape recorder.

BACKGROUND OF THE INVENTION In recent years, video table recorders have been developed in the commercial and broadcasting fields that separate and record color video signals into two-channel component signals, a luminance signal and a chrominance signal (for example, M formant and βCAM). It is a VTR called such as Broadcasting Technology Magazine, October 1981 issue P.
872 to P890),
In addition, the 2-channel component signals can be overwritten (
For recording (so-called solid writing), a recording circuit section having a 2-channel input terminal, a 2-channel electromagnetic transducer section connected to the recording circuit section, and a 2-channel reproduction circuit section connected to the 1i magnetic transducer section. A video signal recording and reproducing device has been proposed.

Hereinafter, an example of the above-described video signal recording and reproducing apparatus will be described with reference to the drawings.

FIG. 7 is a block diagram of the main parts of the above-mentioned video signal recording and reproducing apparatus. In FIG. 7, the recording circuit unit 65 includes a first channel switcher 70 that mutually switches the channel of the input video signal every nH (H: horizontal synchronization interval, n is an arbitrary integer); a converter i1) circuit 7 that supplies an output signal to the electromagnetic converter 66;
1.72, the electromagnetic conversion section 66 is composed of a magnetic tape and two sets of magnetic heads, and the reproduction circuit section 67
is a video signal composed of demodulation circuits 73 and 74 that demodulate the two-channel reproduced signals from the electromagnetic conversion circuit section 66, and a second channel switcher 77 that mutually switches the channels of the demodulated signals every nH. Recording and reproducing devices have been proposed.

Problems to be Solved by the Invention However, in the above configuration, since the first channel switcher 70 switches the input two-channel video signals to the modulation circuits 71 and 72 every nH,
Differences in characteristics between the channels of the two sets of modulation circuits cause level, gain differences, non-linear distortion, etc., resulting in a problem of image quality deterioration. In particular, it is extremely difficult to eliminate differences in characteristics between channels in a circuit that performs nonlinear processing such as an FM modulator.

Means for Solving the Problems In order to solve the above problems, the video signal recording and reproducing apparatus of the present invention includes a recording circuit section having two-channel input terminals and a two-channel electromagnetic circuit section connected to the recording circuit section. The recording circuit section includes a converting section and a two-channel reproducing circuit section connected to the electromagnetic converting section; an error detection circuit that detects the characteristic difference between each channel;
and an error correction circuit that corrects the characteristic difference between the channels.

Effect of the Invention With the above-described configuration, the present invention allows two-channel video signals to be transmitted without causing a difference in characteristics between the channels of the two sets of FM modulation circuits, and no deterioration in image quality occurs.

Embodiment Hereinafter, a video signal recording and reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the main configuration of a first embodiment of the present invention. In FIG. 1, 1.2 is an input terminal, 3.4 is an output terminal, 5 is a recording circuit section, 6 is an electromagnetic conversion section, and 7 is a reproduction circuit section.

The operation of the video signal reproducing apparatus configured as described above will be described below.

For example, it is assumed that a luminance signal as shown in the second figure is input to the input terminal 1, and a time-base compression multiplexed color signal as shown in FIG. 2 is input to the input terminal 2. Here, the luminance signal and the time-base compression multiplexed color signal form a two-channel component signal. The luminance signal is transmitted together with the horizontal synchronization signal separation circuit (H3S) 8.
It is connected to the = input terminal of the first channel switcher 10 . In H3S8, the horizontal synchronizing signal is separated as shown in Figure 3 (A), and the flip-flop (FF) 9
is supplied to As shown in the sixth section, an example of the internal configuration of the first channel switcher 10 includes two switches 55 and 56, and outputs to output terminals 53 and 54. Control terminal 5 of first channel switcher 10
0 is supplied with an FF output signal as shown in FIG. 3(B). From the output terminals 53 and 54, Fig. 3 (F) is output.

Signals as shown in (G) are obtained, and each signal is FM
Modulator 1). 12, and the electromagnetic converter 6
and is supplied to the error detection circuit 13.

FIG. 2 shows a block diagram of the main parts of the error detection circuit 13.

Reference numeral 21 denotes a third channel switcher, and an example of the internal configuration thereof is shown in FIG. 6 similarly to the first channel switcher. FM modulator 1). The FM signal output from 12 is manually input to the third channel switcher 21,
It is switched by the output signal of the delay element 22 as shown in FIG. Here, for example, suppose that only the center frequency of each FM variation 1) is shifted by 2%. Then, the signal demodulated by the FM demodulator 23 becomes as shown in FIG. 3(H), and a DC level difference is calculated every nH. Therefore, the DC level difference is sampled at a certain sample point (for example, pedestal level) and detected by the detector 24, and the detection result is input to the error correction circuit 14, and the center frequency of the FM modulation Ill, 12 is automatically adjusted. By doing so, each FM modulator 1). 12 center frequency deviations can be corrected.

During reproduction, two channels of reproduction signals are supplied to the reproduction circuit section 7 through the electromagnetic conversion section 6 in FIG. The reproduced signals of the two channels are respectively supplied to FM demodulators 14 and 15, as shown in FIG. 3(F).

It is demodulated into a signal as shown in (G). The output signal of the FM demodulator 15 is sent to the horizontal synchronization signal separation circuit (H3S) 1
By supplying the signal to the flip-flop (FF) 13 via the channel 7, a signal for controlling the second channel switcher 19 as shown in FIG. 3(B) is obtained. The configuration of the second channel switcher 19 is similar to that of the first channel switch 10 shown in FIG.
The time series of the channel signals are restored to their original time series, and the output terminal 3 receives the luminance signal shown in FIG. 3(D), and the output terminal 4 receives the time-base compression multiplexed signal shown in FIG. 3(E). color signals are obtained.

In the above description, a luminance signal and a time-base compression multiplexed color signal are used as video signals divided into two channels, but this invention is applicable to all video signal recording and reproducing devices capable of two-channel recording.

In addition, in the above explanation, only the case where only the center frequency of each modulator 1) 12 is shifted, but by taking a plurality of sampling points in the error detection circuit 13, the modulator 1 ). 12 various characteristic differences can be suppressed. Furthermore, the error detection circuit 13
It goes without saying that the FM demodulator 23 can be used in common with the FM demodulator 15 or 16 in the reproducing circuit section 7.

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a block diagram of a main part of an error detection circuit showing a second embodiment of the present invention. The difference from the configuration shown in FIG. 2 is that two FM demodulators 41 and 42 are provided.

The operation of the error detection circuit configured as described above will be explained below.

The signals shown in Fig. 5 (C) and (D) are the FM modulator 1)
．． 12 , modulated, and supplied to the electromagnetic converter 6 and error detection circuit 13 . Here, for example, each F
Assume that only the center frequency of the M modulator is shifted. Then, in the error detection circuit 13, the signals input to the FM demodulators 41 and 42 are demodulated into signals as shown in FIGS. 5(E) and 5(F). There is a DC level difference in the signal input to the detector 43, and the DC level difference is shown in FIG. 5(B).
The signal supplied from the delay element 44 shown in FIG. ). By automatically adjusting the center frequency of each FM modulator 1). 12 center frequency deviations can be corrected.

Note that in the above description, each modulator 1). Although only the case in which only the center frequencies of the modulators 1) and 12 are shifted, the error detection circuit 13 takes a plurality of sampling points to detect the difference between the modulators 1) and 1). 12 various characteristic differences can be suppressed. Furthermore, the error detection circuit 13
It goes without saying that the FM demodulators 41 and 42 can be used in common with the FM demodulators 15 and 16 in the reproduction circuit section 7.

Effects of the Invention As described above, a recording circuit section having a two-channel input terminal, a two-channel electromagnetic conversion section connected to the recording circuit section, and a two-channel reproduction circuit section connected to the electromagnetic conversion section are provided. The recording circuit unit is configured to input an input signal to F.
2&Il FM modulation circuit that performs M modulation, and the two sets of FM
By comprising an error detection circuit that detects the characteristic difference between each channel of the modulation circuit and an error correction circuit that corrects the characteristic difference between the respective channels, two channels of video signals can be transmitted to the two sets of the FM modulation circuits. Transmission is performed without any difference in characteristics between each channel, and screen deterioration does not occur.

[Brief explanation of drawings]

FIG. 1 is a block diagram of main parts of a video signal recording and reproducing apparatus according to the first embodiment of the present invention, FIG. 2 is a block diagram of main parts of an error detection circuit, FIG. 3 is a signal waveform diagram of each part, and FIG. A main part configuration diagram of the error detection circuit in the second embodiment of the present invention, FIG. 5 is a signal waveform diagram of each part, FIG. 6 is a circuit diagram of an example of the internal configuration of a channel switcher, and FIG. 7 is a conventionally proposed circuit diagram. FIG. 1 is a configuration diagram of main parts of a video signal recording and reproducing device. 5... Recording circuit section, 6... Electromagnetic conversion section, 7... Reproduction circuit section, 13... Error detection circuit, 14...・Error correction circuit, 10...
...first channel switcher, 18...second channel switcher, 21...third channel switcher. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 2 Figure 4 Figure 6

Claims (3)

[Claims] (1) A video signal recording and reproducing device that records and reproduces each of video signals divided into two channels, which includes a recording circuit section having a two-channel input terminal, and a two-channel input terminal connected to the recording circuit section. The recording circuit section includes an electromagnetic conversion section and a two-channel reproducing circuit section connected to the electromagnetic conversion section, and the recording circuit section includes two sets of FM modulation circuits that FM modulate an input signal, and two sets of FM modulation circuits that perform FM modulation of an input signal. 1. A video signal recording and reproducing apparatus comprising: an error detection circuit that detects a difference in characteristics between each channel; and an error correction circuit that corrects a difference in characteristics between the channels. (2) The error detection circuit is composed of an FM demodulator and a detector, and detects each channel of the FM modulation circuit by comparing the level of a certain sample point of the two channels of signals demodulated by the FM demodulator. The video signal recording and reproducing apparatus according to claim 1, wherein the video signal recording and reproducing apparatus detects a characteristic difference between. (3) The error detection circuit detects the channel of the video signal input to the error detection circuit every nH (H: horizontal synchronization interval, n
is an arbitrary integer) It consists of a channel switcher that switches mutually, an FM modulator, and a detector, and each of the FM modulation circuits is Claim No. 1, characterized in that characteristic differences between channels are corrected.
1) The video signal recording and reproducing device described in item 1).