JPH046314Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial field of application] This invention allows the return video signal and the synchronously combined video signal (Gen Lock Video) to be transmitted to TV in a time-sharing manner.
The present invention relates to a control device suitable for supplying to cameras and the like.

[Background technology and its problems]

When broadcast programs are being filmed using several TV cameras installed in a station, each TV camera is supplied with a synchronously combined video signal for synchronous control, and the video signal being broadcast from the central control room ( NTSC)
is supplied as a return video signal so that it can be viewed on the TV camera's viewfinder.

By the way, in addition to the above-mentioned signals, each TV camera also receives various signals such as power supply, R, G, B, shooting signals, adjustment control control signals, audio signals, etc.
Since it is connected to the central control room via a CCU (camera control unit), multi-core cables are used, but there is a desire to minimize the number of such transmission cables.

One way to reduce the number of transmission cables is to multiplex the return video signal and the synchronously coupled video signal (hereinafter referred to as the Gen Lock signal).
A method of transmitting data using real cables has been developed.
(For example, Sony camera control unit CCU-1800) This method uses a synchronization signal S and a color burst signal (hereinafter referred to as burst signal) B as shown in Figure 1.
is the Gen that is commonly supplied to each TV camera.
Use lock signal VS but return video signal Vr
converts only the video signal Y+C to the Gen Lock signal.
A synthesized video signal Vc is inserted into the video signal period of Vs.
It is provided as follows. However, since the transmission distance of the return video signal Vr and Gen Lock signal Vs differs for each TV camera, they are not included in the burst signal B supplied from the Gen Lock signal Vs and the video signal Y+C of the return video signal Vr. The phases of the carrier color signals C do not match, and this composite video signal Vc does not allow an image with accurate hue to be displayed on TV.
It cannot be displayed on the camera's view index.

Therefore, there is a problem in that the hue must always be corrected manually.

[Purpose of invention]

This idea was made in view of the above situation, and when multiplexing a return video signal and a Gen Lock signal, the burst signals of both signals are compared, and the phase of the carrier color signal is automatically adjusted using this comparison signal. By controlling the phase of the color burst signal of the Gen Lock signal and the phase of the carrier color signal of the return video signal, the relationship between the phase of the color burst signal of the return video signal and the phase of the carrier color signal of the return video signal is changed. It makes the relationship equal.

[Summary of the idea]

In order to achieve the above object, the present invention extracts the burst signal of the return video signal and the burst signal of the Gen Lock signal, and detects the phase difference between them. The phase of the carrier color signal is changed to 0° by the first phase shift circuit.
or inverted to 180°, and then injecting the carrier color signal of said first phase-shifting circuit into a second phase-shifting circuit that adjusts the phase shift between 0 and 180°, and this second phase-shifting circuit In, the above
The second signal is based on the burst signal of the Gen Lock signal.
The hue is further adjusted by inputting the detection signal of the phase detector. When performing such hue correction, the detection signal of the first phase detector described above is given a hysteresis characteristic so that the hue can be corrected automatically, and the correction operation is prevented from flapping. It was designed to eliminate the

〔Example〕

Figure 2 shows a block diagram of the automatic hue correction circuit for the return video signal Vr of this invention.
T ₁ is the input terminal for the return video signal Vr supplied as an external video signal, and T ₂ is the reference signal.
The input terminal for the Gen Lock signal Vs, and T3, is the output terminal for the multiplexed composite video signal Vc.

1 is the carrier color signal C from the return video signal Vr
The video signal from which the carrier color signal C is separated is separated by the Y/C separation circuit using a filter or the like, and the synchronization signal S is separated by the next synchronization clip circuit 2, and only the luminance signal Y is sent to the mixing circuit 3. supply to. 4
is a burst gate circuit that extracts the burst signal B.

On the other hand, Gen input from input terminal _T2
As for the lock signal Vs, only the synchronization signal S is extracted in the synchronization separation circuit 5 and inputted to the mixing circuit 3, and the burst signal Bs is inputted to the burst gate circuit 6.
The signal is extracted by the same and supplied to the mixing circuit 3 in the same way.

Therefore, if the phase of the carrier color signal C separated by the Y/C separation circuit 1 is corrected by the hue correction circuit 7 as described later, and becomes the carrier color signal C for the burst signal B of the Gen Lock signal Vs. By supplying this carrier color signal C to the mixing circuit 3, the aforementioned composite video signal Vc is formed, and this composite video signal Vc is supplied to a TV camera and reproduced with accurate hue on a viewfinder.

The hue correction circuit 7 must be capable of at least 360° phase shift correction, but since 360° phase shift adjustment is complicated with an electrical circuit, in this invention, first, the first phase shift correction circuit 7 is required. The circuit 7a and the first phase detector 7b perform a phase inversion of 0° or 180°, and then the second phase shift circuit 7c and the second phase detector 7d perform further inversion of 0° to 180°. Correct the phase within 180°. Note that 7e is a burst gate circuit, and 7f is a burst removal circuit.

The operation of the hue correction circuit 7 will be explained below with reference to FIG.

Burst signal extracted from Gen Lock signal Vs
The first phase detector 7b detects that the burst signal Br extracted from the return video signal Vr is within ±90° with respect to Bs, as shown in FIG. 3a, that is, between B _r1 and B _r2 . When the first phase shift circuit 7
In a, the carrier color signal C separated from the return video signal Vr is not inverted, and the next second phase shift circuit 7
supply to c.

However, as shown in the burst signal B _r3 in Figure 3a, the burst signal extracted from the Gen Lock signal Vs
When it is outside the range of ±90° with respect to Bs, it is reversed by 180° as shown in Figure 3b, so that the phase error range is ±90° or less, and the next second phase shift circuit 7c is used. supply

In the second phase shift circuit 7c, the burst signal Br extracted from the burst gate circuit 7e and the Gen Lock
The phase of the burst signal Bs of the signal Vs is detected again by the second phase detector 7d, and if there is a phase difference between these burst signals, the carrier color signal C is phase-shifted according to the phase difference, and the hue is changed. Configure. Then, the burst signal Br is removed by the burst removal circuit 7f, and the Gen Lock signal Vs is sent to the mixing circuit 3 mentioned above.
It is supplied as a carrier color signal C corresponding to the .

In this case, since the detection signal of the first phase detector 7b has a hysteresis characteristic as shown in FIG. 4, the first phase shift circuit 7a is Make sure it doesn't flap.

FIG. 4 shows a specific circuit example of the first phase shift circuit 7a and the first phase detector 7b, in which T _r1 is a transistor to which a DC signal corresponding to the phase difference is input; OA ₁ is a buffer amplifier,
OA ₂ is a voltage comparator whose hysteresis characteristic is formed by a positive feedback resistor R, and Dz is a Zener diode.

The output of the Zener diode Dz is connected to the switching transistor via the transistor T _r2 .
On/off control of T _r3 and T _r4 is performed, and the carrier color signal C input from the base of transistor T _r5 and the carrier color signal C which is inverted (180° phase shifted) of this signal (output of transistor T _r6 ) is configured to select one of the signals.

Therefore, when the output voltage of the voltage comparator OA ₂ is low, the Zener diode Dz does not conduct, and the switching transistor T _r3 conducts and the carrier color signal C is output, but the output of the voltage comparator OA ₂ When the voltage increases, the Zener diode Dz conducts,
The switching transistor T _r4 is turned on and the inverted carrier color signal C is selected and output.

Since the output voltage of the voltage comparator OA ₂ has a hysteresis characteristic, Gen Lock occurs as seen in the burst signals Br1 and Br2 in Figure 3a mentioned above.
Exactly ±90° with the burst signal B _s extracted from the signal V _s
Even if there is oscillation in the vicinity, one of the comparison signals is output, eliminating flapping and stabilizing the hue correction operation.

[Effect of idea]

As explained above, the control device of this invention is
The relationship between the phase of the color burst signal of the Gen Lock signal and the phase of the carrier color signal of the return video signal is made equal to the relationship between the phase of the color burst signal of the return video signal and the phase of the carrier color signal of the return video signal. In addition, since the phase of the carrier color signal of the return video signal is automatically phase-shifted, the Gen Lock signal and the return video signal can be multiplexed to save cables, and images with accurate hue can be transmitted to the TV camera. This has the advantage that the viewfinder can be displayed without manual correction.

[Brief explanation of drawings]

FIG. 1 is a waveform diagram of a composite video signal formed by multiplexing a return video signal and a synchronously combined video signal, FIG. 2 is a block diagram of a hue correction circuit for a return video signal showing an embodiment of this invention, and FIG. Figures a and b are explanatory waveform diagrams when performing a phase shift of 0° and 180°,
FIG. 4 is a specific circuit diagram of the first phase detector. In the figure, 7a and 7c are first and second phase shift circuits;
b, 7d are the first and second phase detectors, Vr is the return video signal, Vs is the Gen Lock signal, Br is the burst signal of the return video signal, Bs is the Gen
Indicates a lock signal burst signal.

Claims (1)

[Claim for Utility Model Registration] Control that time-division multiplexes a broadcast external video signal and a reference signal consisting of a reference synchronization signal and a reference color burst signal and supplies the resultant signal to a television camera. In the apparatus, a first separation circuit that separates the external video signal into a luminance signal and a carrier color signal; a second separation circuit that separates a color burst signal from the external video signal; phase comparison means for comparing the phase of the color burst signal synchronized with the external video signal separated by the second separation circuit; based on the output of the phase comparison means; A first circuit that inverts the phase shift of the carrier color signal supplied from the first separation circuit by 180 degrees only when the phase difference between the phase of the burst signal and the phase of the color burst signal of the external video signal is ±90 degrees or more. a transfer circuit; a phase relationship between the reference color burst signal and the carrier color signal output from the first phase shift circuit is such that the phase relationship between the color burst signal output from the second separation circuit and the carrier color signal output from the first phase shift circuit A second phase shifter that shifts the phase of the carrier color signal supplied from the first phase shift circuit between 0° and 180° so as to have a phase relationship with the carrier color signal output from the separation circuit. a phase shift circuit; a signal obtained by removing the color burst signal from the output of the second phase shift circuit; a signal obtained by removing the synchronization signal from the luminance signal output from the first separation circuit; and the reference synchronization signal. , and a color burst signal, and is configured to supply the signal multiplexed by the mixing circuit to the television camera.