JPS6340495A - Video system - Google Patents

Abstract

PURPOSE:To attain good recording by recording a chrominance signal obtained by orthogonally two phase modulating a color difference signal based on an image picked up optical image without executing a frequency conversion. CONSTITUTION:In the case of an externally inputted color video signal, no direct current superimposed is detected in an input signal detecting circuit 36 to turn a switch 37 OFF and a switch 38 ON. Therefore, the color video signal is brought into a constant level by an AGC14 and guided to a low pass filter (L. P. F.)39 and a band pass filter (B. P. F.)40. A luminance signal is separated by the L. P. F. 39, FM modulated, the chrominance signal is separated by the B. P. F. 40 and the level thereof is made constant in an ACC circuit 41. Since this chrominance signal is modulated by a high frequency sub-carrier, it is converted in frequency by a signal formed in a frequency converting signal generating circuit 43, a low frequency side is taken out by an L. P. F. 44 to have the same low frequency converted chrominance signal as the chrominance signal of the output of a camera and it is mixed with the FM modulated luminance signal and recorded by a head.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a video system for recording color video signals, and more particularly to a video system including a camera and a recorder.

<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 an R.
, B signals and output 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. The luminance signal and the chrominance signal are separated from the signal, the luminance signal is FM modulated, the chrominance signal is frequency-converted to its lower frequency side, and the FM-modulated luminance signal and the frequency-converted chrominance signal are mixed. When recording and playing back, the playback signal is separated into a luminance signal and a chrominance signal, the luminance signal is FM demodulated, and the chrominance signal is frequency-inverted back to its original frequency and FM.
Mixing the demodulated luminance signal and the frequency inversely converted color signal,
It was configured to 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 on the VTR side, a filter was used to separate the luminance signal and color signal, and the color signal was Since recording is performed through a frequency converter that converts the frequency to the lower frequency side, there is a drawback that transmission distortion is likely to occur.

The present invention provides a video system capable of reducing transmission distortion of the video signal from the camera in a video system capable of recording both a video signal from the camera and a video signal from an external source.

Means for Solving the Problems〉 With the above object in mind, in the system of the present invention, the first color signal obtained by quadrature two-phase modulation of the color difference signal based on the captured optical image is frequency-converted. The second color signal in the color video signal inputted from the outside is recorded after its carrier frequency is converted to match the carrier frequency of the first color signal.

(Function) By configuring as described above, it is not necessary to perform frequency conversion on the color signal obtained from the camera, so the accompanying processing is also unnecessary, the occurrence of transmission distortion can be reduced, and the external The video signal input from the camera can be recorded in the same signal format as the video signal obtained from the camera.

<Embodiment> FIG. 1 is an embodiment of the present invention, and FIG. 2 is a diagram showing details of the camera section 2 in FIG. 1. In these figures, 1 is a recording section, 2 is a camera section, and 3 indicates the playback section. 4 is an imaging unit, 5 is a luminance signal separation circuit, 6 is an R and B signal separation circuit, 7 is a machine that generates a luminance signal color difference signal from the signals of the luminance signal separation circuit 5 and RB signal separation circuit 6) IJ Lux path, 8 is T't-
9 is a B-Y modulator; 10 is a synchronization signal generation circuit that generates a burst flag, a horizontal synchronization signal, a frame pulse, a low-frequency carrier signal for modulation, etc.; 1 is a shifter for shifting the phase of the 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 AGC (autocane controller),
15 is an FM modulator, 16 is an Ibus 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, 2
0 is a rotary transformer, 211 is a head, 22 is a reproduction amplifier, 23 is a low-pass filter (T, , P, P) that separates the color signal from the reproduction signal, and 24 is an autochromer.
Controller, A, CC125 is frequency conversion circuit, 2
6 is a frequency conversion signal generation circuit that generates a signal necessary for frequency conversion, and 27 is a band pulse filter r3. P, F, 2
8ijlJ losstalk removal comb filter, 29 is a luminance separation bypass filter H, P, F, 30 is an FM post-adjuster, 31 is a low-pass filter L, P, F, 32 is a playback video output terminal, 33 is a connection from camera 2 34 is a color signal input terminal from 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 line input, and 37 is a color signal input terminal from the camera. a switch controlling the supply of the signal to the level regulator;
38 is A, (a switch that controls the supply of signals from IC1, 4 to B, P, F2O, 4o is a band pass filter for color signal separation (B, P, F,), 41 is A, CO24
42 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 for extracting the low frequency converted color signal. Low-pass filters (L, P, F,) are shown. A1 to A7 are adder circuits.

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, the low-frequency carrier signal generated by the synchronization signal generation circuit 10, for example, a reference signal having a frequency of 40 fH, is transmitted to the phase shift circuit 11 by +90° for each I-1 during one field period, and during the next field period by +90° for each I-1. The phase is changed by 90° for each IH. The phase-rotated 40fH low-frequency carrier signal is R, -
A signal whose phase is further shifted by 90° from 40f11, which is phase rotated in the Y modulator 8, is sent to the BY modulator 9. Therefore, the combined signal of the outputs from the modulators 8 and 9 is R,
-Y, B-Y signals are quadrature two-phase modulated with a 40 fH low-frequency carrier signal, and the carrier wave has a phase change of +900 every 11-T in one field and 1... in the next field. The phase is rotated by 190 degrees every time I (). Then, it is 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 sent to the DC superimposition circuit 1.
Connected to 2. The DC superimposing circuit 12 either clamps the luminance signal to which the synchronizing signal has been added, or simply superimposes the DC signal, and outputs the signal to the terminal 33 .

In this embodiment, a line input terminal 35 is provided,
A normal color video signal comes in from here.

On the other hand, since the camera signal consists of a luminance signal and a color signal placed in its lower range, it is necessary to detect these signals and switch the circuit. By the way, the luminance signal output of the camera is superimposed with a certain DC level and is output to the input terminal 33. By detecting this in the input signal detection circuit 36, it is possible to determine whether the intervening 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 set to OTi"F. At this time, the luminance signal from the input terminal 33 is kept at a constant level through the A, G, and Cl paths, and the FM modulator 15 modulates the level from 3.4 MHz to 4.4 MHz.
It is modulated to 4 MHz and sent to the recording amplifier 18 through ) The signals are mixed and amplified by the adder circuit A4 and recorded on tape by setting the switch 19 to the R side.

Next, when an input signal enters from the line input terminal 35, that is, when the input signal is a color video signal input from the outside, the input signal detection circuit 36 detects that no direct current is superimposed.
The switch 37 is turned off and the switch 38 is turned on. Therefore, the color video signal input from the line input is AG
It is brought to a certain level at C14.

Guided by P, F, 39, B, P, F, 40. The luminance signal beams P, F, and 39 are separated and FM modulated in the same manner as described above. The color signals are separated by B, P, F, and 4.0, and the level is made constant by the ACC circuit 41. Since this color signal is modulated with a high-frequency subcarrier, it is frequency-converted at 42 with a signal generated by a frequency conversion signal generation circuit 43, and then transmitted to the low-frequency side at 44 T, P, F, 44. The low frequency converted color signal is the same as the color signal output from the camera and is mixed with the FM modulated luminance signal. Further, the mixed signal is amplified by a recording amplifier and recorded by a head.

During reproduction, the switch 19 is set to the P side, and the reproduction output is amplified by the reproduction amplifier 22 and output from the recording-only device. The amplified playback output is input to the playback-only device 3, and first Il, P,
The luminance signal is separated and FM demodulated by F, 29.■7
．． Bandwidth is limited by P, F, and 23.

On the other hand, the color signal beams P, F, and AC are separated by 23.
The level is kept constant in C24, and the frequency conversion circuit 25 inversely converts the low-frequency-converted color signal to the same high-frequency band as the color video signal.

27, crosstalk is removed by a comb filter 28, and the signal is mixed with a luminance signal and output.

<Effects of the Invention> As described above, the present invention records the color signal obtained by quadrature two-phase modulation of the color difference signal based on the captured optical image without frequency conversion, so that transmission distortion is small and good recording is possible. I can do it. On the other hand, color video signals input from the outside can also be recorded in the same signal format. Still, the present invention is particularly effective in a system configuration in which a camera and a VTR recording system are integrated, and a compact video system with little deterioration in image quality can be constructed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating an embodiment of the present invention;
FIG. 2 is a block diagram illustrating details of the camera section of FIG. 1. 8...RY modulator 9...B-Y modulator 33...Brightness signal input terminal 34...Color signal input terminal 35...Line input terminal 37.38...Switch diagram

Claims (1)

[Claims] The first color signal obtained by quadrature two-phase modulation of the color difference signal based on the captured optical image is recorded without frequency conversion, and the second color signal in the externally input color video signal is recorded without frequency conversion. A video system characterized in that the color signal is recorded by frequency converting its carrier wave frequency so as to match the carrier wave frequency of the first color signal.