JPS6354893A - Video system - Google Patents

Abstract

PURPOSE:To contrive to interleave the frequency of a chrominance signal between adjacent tracks without applying any processing and to simplify circuit constitution by directly applying orthogonal two-phase modulation to a color difference signal by a phase controlled carrier to obtain the chrominance signal. CONSTITUTION:A video signal is separated to a luminance signal and an RB signal in a luminance signal separating circuit 5 and an RB signal separating circuit 6 and further converted into the luminance signal and the color difference signal of R-Y, B-Y by a matrix circuit 7. A low frequency carrier signal formed in a synchronizing signal generating circuit 10, for instance, a reference signal having the frequency of 40fH is changed in phase by +90 deg. for every 1H during one field period by a phase shift circuit 11 and changed in phase by -90 deg. for every 1H during the next field. A phase rotating low frequency carrier signal of 40fH is fed to an RY modulator 8 and a signal shifted in phase by 90 deg. is fed to a B-Y modulator 9. Thereby, the frequency of the obtained chrominance signal is interleaved between the adjacent fields.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a video system for recording color video signals.

<Prior Art> Conventionally, in a video system, a camera converts a video signal taken out by an image pickup tube or a solid-state image pickup plate into a luminance signal and R,
It is configured to separate the B signal and output it as a video signal (hereinafter simply referred to as a color video signal) containing a luminance signal and a color signal subjected to quadrature two-phase modulation using an encoder.
During recording, TR separates a luminance signal and a color signal from a color video signal, FM modulates the luminance signal, and converts the frequency of the color signal to its lower frequency side, and converts the frequency of the FM modulated luminance signal and the color signal. When recording, the reproduced signal is separated into a luminance signal and a color signal, and the luminance signal is
The M demodulated color signal is frequency inversely converted to the original band, and the FM demodulated luminance signal and the frequency inversely converted color signal are mixed and output as a color video signal.

<Problems to be solved by the invention> In the conventional system, the signal format transmitted from the camera to the VTR was a color video signal, so a filter was required on the VTR side to separate the luminance signal and color signal. Since the frequency of the color signal is converted to the lower frequency side and the frequency is interleaved between adjacent tracks, the circuit becomes complicated and large, and transmission distortion is likely to occur.

The present invention provides an improved video system in view of the above points.

<Means for solving the problem> For this purpose, in the system of the present invention, the phase of the carrier wave for quadrature two-phase modulation of the color difference signal is changed every predetermined period by using color signals whose frequencies are interleaved with each other. The configuration is such that the output is controlled alternately.

In the above-described configuration, if one track is sequentially formed every predetermined period, frequency interleaving can be performed between adjacent tracks without performing any processing on the color signal.

<Embodiment> FIG. 1 shows an embodiment of the present invention, in which numeral 1 indicates a recording-only machine consisting of a camera section 2 and a recording section of a VTR, and 3 indicates a reproduction-only machine. 4 is an imaging unit, 5 is a luminance signal separation circuit, 6 is an R and B signal separation circuit, 7 is a matrix circuit that generates a luminance signal and a color difference signal from the signals of the luminance signal separation circuit 5 and the RB signal separation circuit 6;
8 is a R-Y modulator, 9 is a B-Y modulator, IO is a synchronization signal generation circuit that generates a burst flag, horizontal synchronization signal, frame pulse, low-frequency carrier signal for modulation, etc., and 11 is a low-frequency carrier signal. 12 is a 90° phase shift circuit, 13 is a DC superimposition circuit that superimposes DC on the luminance signal, 14 is an AGC (auto gain controller), 15 is an FM modulator, and 16 is a bypass filter (
H, P, F), 17 is a level adjuster for adjusting the level of the color signal, 18 is a recording amplifier, 19 is a recording/playback switching circuit, 20 is a rotary transformer, 21 is a head, 22 is a playback amplifier, 23 is a A low-pass filter (L, P, F) separates the color signal from the reproduced signal, 24 is an autochromer controller (ACC), 25 is a frequency conversion circuit, 26 is a frequency conversion signal generation circuit that generates the signals necessary for frequency conversion, 27 are hand pulse filters B, P, F; 28 are comb filters for removing crosstalk; 29 are bypass filters H, P, F for luminance separation; 30 are FM demodulators; 31 are low-pass filters L, P, F, 32 is a playback video output terminal. A I''A s is an adder circuit.

Next, the operation of the above-mentioned configuration will be explained. A video signal taken out from an image pickup tube, a solid-state image pickup plate, etc. is separated into a brightness signal and an RB multiplied signal by a brightness signal separation circuit 5 and an RB signal separation circuit 6, and is further processed by a matrix circuit 7. Luminance signal and R-Y,
It is converted into a B-Y color difference signal. On the other hand, a low-frequency carrier signal generated by the synchronization signal generation circuit 10, for example, a reference signal having a frequency of 40 fH, is sent to the phase shift circuit 11 by +9 times for each IH during one field period, and for each IH during the next field period. The phase can be changed by 90 degrees.

As a result, the frequency of the low frequency carrier signal is shifted by fH between adjacent fields as is well known.The low frequency carrier signal of 40fH with 0 phase rotation is transmitted to the R-Y modulator 8, and the 40fH frequency with its phase rotation is The signal further phase-shifted by 906 is sent to the B-Y modulator 9. Therefore, the combined signal output from the modulators 8 and 9 is R-Y.

The BY signal is quadrature two-phase modulated with a 40 fH low frequency carrier signal, and the carrier wave rotates in phase by +90 for each IH in one field and -90' for each IH in the next field.

Therefore, the frequency of the resulting color signal will be frequency interleaved between adjacent fields. The signal is then adjusted to an appropriate level by a level adjuster 17 and sent to a recording amplifier 18. The luminance signal output from the matrix circuit 7 and the composite synchronization signal generated by the synchronization signal generation circuit 10 are mixed and connected to a DC superimposition circuit 12. The DC superimposition circuit 12 clamps the luminance signal to which the synchronization signal has been added, or superimposes a short DC on it.The AGC circuit keeps the level constant, and the FM modulator 15 modulates it to 3.4MH2 to 4.4MH2. It is.

It is sent to the recording amplifier 18 through H, P, and F1a. In the recording amplifier 18, a signal obtained by mixing the color signal arranged in the low frequency range and the FM-modulated luminance signal is amplified by the adder circuit A4, and by setting the switch 19 to the R side, one track is formed for each field as is well known. and record it on tape.

During playback, the switch 19 is set to the P side, and the playback output is amplified by the playback amplifier 22 and output from the recording-only device. The amplified playback output is input to the playback-only device 3, and first H, P, F
, 29, the luminance signal is separated and FM demodulated, P,
F.

Bandwidth is limited by 23.

On the other hand, it is separated by monochromatic beams P, F, 23 and ACC
24, the level is kept constant, and a frequency conversion circuit 25 converts the low frequency color signal to the same high frequency band as the color video signal.

27, crosstalk components between adjacent tracks are removed by a comb filter 28 as is well known, and the signal is mixed with a luminance signal and output.

Next, another embodiment of the present invention will be explained.

FIG. 2 describes an embodiment of a video system comprising a camera and a VTR 34 having a line input terminal. Blocks that are the same as in FIG. 1 are designated by the same numbers. 33 is a luminance signal input terminal from the camera 2, 34 is a color signal input terminal from the camera 2, 35 is a line input terminal, 36 is an input signal detection circuit that detects whether the input signal is from the camera side or from the line input, 37 38 is a switch that controls the supply of color signals from the camera to the level adjuster; 38 is a signal B from the AGC 14;

P, a switch for controlling the supply to F2O, and 40 a color signal separation bandpass filter (B.

P, F), 41 is the same as ACC24, ACC142 is a frequency converter that converts the color signal in the high frequency range to the low frequency side, 43 is a frequency conversion signal generation circuit that generates a signal used for low frequency conversion, and 44 is a low frequency converter. Low-pass filters (L, P, F) for extracting gamut-converted color signals are shown. A6-A7 are adder circuits
− is.

The operation of the embodiment configured as described above will be explained.

In this embodiment, a line input terminal 35 is provided, from which a normal color video signal is input.

On the other hand, since the signals from the camera are a luminance signal and a color signal placed in the low range, these must be detected and the circuit must be switched. By the way, the luminance signal output from the camera enters the input terminal 33 with a certain DC level superimposed thereon. The input signal detection circuit 36 detects this to determine whether the currently input signal is a camera signal or a line input signal. In reality, this circuit is composed of simple circuits such as comparators.

First, to explain the case where the input signal is from a camera, a luminance signal on which DC is superimposed is output from the input terminal 33.
When a color signal distributed in the low range comes in from 4, the input signal detection circuit 36 detects the DC component and turns on the switch 37.
, 38 are turned off. Therefore, the color signal passes through the level adjuster 17, and the luminance signal is FM modulated and mixed with the color signal, and is amplified and recorded by the recording amplifier 18. In other words, the signal flow is the same as in FIG.

Next, when an input signal enters from the line input terminal 35, that is, when the input signal is a color video signal, the input signal detection circuit 36 detects that no direct current is superimposed, and the switch 3
7 is turned off and switch 38 is turned on. Therefore, the color video signal input from the line input is made to a constant level by the AGC 14, and outputs P, F, 39, B, P, F.

Leading to 40. Luminance signal beams, P, F.

The 0 color signal separated by 39 and FM modulated in the same manner as described above is separated by B, P, F, 40, and sent to the ACC circuit 41.
The level is kept constant.

This color signal is modulated with a high-frequency subcarrier, and is frequency-converted by a frequency converter 42 using a signal generated by a frequency conversion signal generation circuit 43.
At step 44, the low frequency side is taken out, converted into a low frequency converted color signal placed in the same band as the camera output color signal, and mixed with the FM modulated luminance signal. Further, the mixed signal is amplified by a recording amplifier and recorded by a head. During playback, in any case, the input signal becomes a color video signal and is output from the terminal 32 in the same manner as described with reference to FIG. - <Effects of the Invention> As described above, the present invention directly performs quadrature two-phase modulation on a color difference signal using a phase-controlled carrier wave to obtain a color signal, so that the color signal can be obtained without any further processing. The frequency can be interleaved between adjacent tracks, and the circuit configuration can be simplified.

Furthermore, the present invention is particularly effective when a system configuration is adopted in which the recording systems of a camera and a VTR are integrated into a recording-only machine and a playback-only machine, and most of the conventional color signal processing system is omitted in the recording-only machine. This makes it possible to configure a compact video system with little deterioration in image quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating an embodiment of the present invention;
FIG. 2 is a block diagram illustrating another embodiment of the present invention. 11... Phase shift circuit 12... 90° shift circuit

Claims (1)

[Scope of Claims] A system for recording a color signal obtained by quadrature two-phase modulation of a color difference signal using a carrier wave, wherein the phase of the carrier wave is adjusted such that the color signals whose frequencies are interleaved with each other are output alternately at predetermined intervals. A video system characterized by controlling.