JPH01278178A - Video camera system and camera head and camera control unit used in the same - Google Patents

Abstract

PURPOSE:To simplify synchronous coupling between a camera head and a CCU (camera control unit) by providing a video signal cancelling means which takes out an external synchronizing signal to the camera head and an external synchronizing signal cancelling means which takes out a video signal to the CCU. CONSTITUTION:A synchronizing signal generation circuit 12 is provided only on the camera head 20, and a composite video signal transmitted from the camera head 20 is outputted as it is as the composite video signal from the CCU30. Also, the external synchronizing signal is superposed on the composite video signal as it is in the CCU30, and is transmitted to the camera head 20, and as for a camera synchronizing signal and the external synchronizing signal superposed on a coaxial cable 13, the video signal is removed at the camera head 20, and the external synchronizing signal is removed at the CCU30 part. Therefore, the position of the synchronizing signal can always be fitted in broadcasting specification. In such a way, it is possible to simplify circuit constitution for the synchronous coupling between the CCU and the camera head.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a video camera system, and particularly to a video camera system in which a camera head and a camera control unit are connected by a coaxial cable, and which can be synchronized with an external synchronization signal. Regarding the improvement of

[Conventional technology] In a professional video camera system such as ITV, a camera head and a camera control unit (hereinafter referred to as CCU) are connected by a coaxial cable, and video signals are sent from the camera head to the CCU via this coaxial cable. At the same time, when an external synchronization signal from another power head or the like is given to the CCU, this is supplied to the camera head via a coaxial cable to control the internal synchronization signal generation circuit. It has become.

A method of transmitting an external synchronization signal or a signal synchronized thereto to the camera head includes a method of removing the synchronization signal of the video signal of the camera head, inserting an external synchronization signal in that period, and transmitting it backwards. That is, in the system block diagram of FIG. 4, the camera controller 20' extracts an external synchronizing signal transmitted from the CCU 30' and uses it for synchronizing the synchronizing signal generating circuit. In addition, in the CCU 30', the external synchronization signal transmitted to the camera head 20° is removed from the signal on the coaxial cable 13, and the synchronization signal generated by the synchronization signal generation circuit 19 is synchronously coupled to the external synchronization signal in the CCU 30'. is added and output from the output terminal 21 as a CCU output composite video signal.

FIG. 5 is a signal waveform diagram in the conventional video camera system shown in FIG. From this figure, the signal on the coaxial cable 13 is the video signal from the RAD 20' to the camera, and the CCU 30.
It can be seen that the synchronization signal from ' is superimposed on the signal.

[Problem to be Solved by the Invention 1] In the conventional video camera system, the configuration and operation were complicated because the synchronization signal generation circuit was provided in both the camera head and the CCU. In other words, when performing internal synchronization, C
Synchronous coupling is performed by controlling the synchronizing signal generating circuit in the camera head with the synchronizing signal generating circuit of the CU, but when an external synchronizing signal from the camera head etc. is given to the CCU, double synchronizing coupling is performed. Setting the initial characteristics to obtain the optimal response is troublesome and tends to result in high costs.

Furthermore, there is a delay in the transmission signal depending on the length of the coaxial cable, so if the delay time is τD, when sending an external synchronization signal from the CCU to the camera head, there will be a delay of 2τD in the round trip of the coaxial cable. For example, H5y due to delay
The position of the nc may deviate from the predetermined position according to the broadcasting standard and enter the video signal. In order to prevent such problems, a delay compensation circuit is installed in the camera head.
The position of nc is v! I had to make four adjustments.

Therefore, it is an object of the present invention to provide a video camera system in which synchronous coupling between a camera head and 000 can be realized with a simple configuration and at low cost, and in which both internal and external synchronization can be performed via a single coaxial cable. purpose.

[Means for Solving the Problems 1] The present invention solves the above conventional problems and achieves the above objects by providing a synchronization signal generation circuit only in the camera head, and converting the composite video signal transmitted from the camera head as it is. While outputting as a composite video signal from the CCU,
The camera head superimposes the external synchronization signal on the composite video signal as it is and transmits it to the camera head.The camera head removes the video signal and transmits the overlapping camera synchronization signal and external synchronization signal to the composite video signal on the coaxial cable. A cancellation circuit is provided for each.

That is, according to the present invention, there is provided a video camera system comprising a camera head, a camera control unit, and a coaxial cable connecting the two, wherein a video signal is sent from the 6+J camera head to the camera control unit via the cable, A video camera that sends an external synchronization coupling control signal synchronized with an external synchronization signal supplied to the camera control unit from the outside to the camera head via the coaxial cable to control a synchronization signal generation circuit within the camera head. In the system, the camera head is provided with video signal canceling means for subtracting the video signal from the signal on the camera head side of the coaxial cable to extract the external synchronization coupling control signal, and the camera control unit is provided with video signal canceling means for subtracting the video signal from the signal on the camera head side of the coaxial cable. A video camera system is provided, characterized in that the video camera system is provided with an external synchronous coupling control signal canceling means for subtracting the external synchronous coupling control signal from the signal on the camera control unit side and extracting the video signal. Further, according to the present invention, there is provided a video camera system comprising a camera head, a camera control unit, and a coaxial cable connecting the two, wherein a video signal is sent from the camera head to the camera control unit via the cable, A video camera that sends an external synchronization coupling control signal synchronized with an external synchronization signal supplied to the camera control unit from the outside to the camera head via the coaxial cable to control a synchronization signal generation circuit within the camera head. The camera head used in the camera system is characterized in that the camera head is provided with video signal canceling means for subtracting the video signal from the signal on the camera head side of the coaxial cable and extracting the external synchronization coupling control signal. A video camera system comprising a camera head, a camera head, a camera control unit, and a coaxial cable connecting the two, wherein a video signal is sent from the camera head to the camera control unit via the cable. , a video camera for controlling a synchronization signal generation circuit in the camera head by sending an external synchronization coupling control signal synchronized with an external synchronization signal supplied to the camera control unit from the outside to the camera head via the coaxial cable; In a camera control unit used in a camera system, the camera control unit includes external synchronization coupling control signal canceling means for subtracting the external synchronization coupling control signal from the signal on the camera control unit side of the coaxial cable to extract the video signal. A camera control unit is provided.

[Examples] Examples of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing one embodiment of the video camera system of the present invention. This video camera system is comprised of a camera head 20, a CCU 30, and a coaxial cable 13 that connects the two, but differs from the conventional video camera system shown in FIG. 4 in the following points. That is, the synchronizing signal generation circuit (S S G ) is provided only in the camera head 20 and not in the CCU 3O, and the signal canceling circuit described later is provided between the camera head 20 and the CCU.
30i side.

In FIG. 1, the camera head 20 includes an imager 1 consisting of a light-receiving element, a process matrix 2 for processing its output signal, and an encoder 3 for producing a composite color television signal from the output signal.The output signal of the encoder 3 is buffed. Coaxial cable 13 via 7A amplifier 4 and resistor 5B
is given to the end of the camera end. Both ends of the resistor 5B are connected to two terminals of an operational amplifier 5A used as a subtracter. The operational amplifier 5A and the resistor 5B constitute a video signal cancellation circuit.

The output of the operational amplifier 5A is given to the synchronization separation circuit 6, where the horizontal synchronization signal (Hsync) and the vertical resensing (+=
(V reset) is obtained. ) (sync is given to the other input of a phase comparator 8 whose one input is given the output signal of the delay circuit 7, and its output is passed through a reduction filter (LPF) 9 to a synchronization signal generation circuit ( S
The six-pronged H5sync applied to the synchronous signal separation circuit 6 is applied to the 5SG12 via the pulse width detection circuit 10 and the LPFII, and the V reset signal from the synchronization separation circuit 6 is also applied to the 5SG12. The 5SG12 can be implemented as an IC, and its internal configuration is as shown in the figure, but since this circuit configuration is no different from the conventional one, its explanation will be omitted.

The aforementioned delay circuit 7 delays the horizontal synchronizing signal, which is the output of the counter pulse generation circuit of the 5SG12, by a time τ determined by the delay opening τD of the coaxial cable 13, whereas in the conventional circuit, the delay time was 2τD. The thing is τ. The three output signals of the 5SG12 are the burst flag (BF), two subcarriers (SC) that are 90° out of phase with each other, the encoder 31 and the three signals from the process matrix 2, Y,
A composite color video signal is created using R-Y and B-Y.

When the CCU3O receives an external synchronization signal (EXT VBS) from another camera head (not shown), the synchronization separation circuit 15 separates Hsync and V5sync, and outputs H5sync.
ync is AND date 1 via pulse width modulation circuit 17
8 and V 5sync is applied to the other input of AND data 118 . The output of AND date 18 is connected to CCUI of coaxial cable 13 via resistor 14B.
The resistor 14B is applied to the IllI end, and both ends of the resistor 14B are applied to two operational amplifiers 14^ that constitute a subtracter. The operational amplifier 14^ and the resistor 14B constitute an external synchronization coupling control signal canceling circuit. The output of the operational amplifier 14^ is applied to the output terminal 21 as an output signal of the CCU 30, and is also applied to one input of the phase comparator 16, where the phase is compared with an external synchronization signal applied to the other input, and the comparison result is The output signal is used as a control signal for the pulse width modulation circuit. Above circuit 15.16
．． Reference numerals 17 and 18 create an external synchronization coupling control signal synchronized with the external synchronization signal, and this external synchronization coupling control signal is sent to the camera head 20 via the resistor 14B and the coaxial cable 13.

In addition, in the conventional circuit shown in FIG. 4, there are 5S6 in the CCU 30'.
19, but the present invention does not use the SSG.

Next, the operation of the video camera system shown in FIG. 1 will be explained.

When an external synchronization signal is applied to ccuao, an external synchronization coupling control signal is generated by the CCU 30 as described above, and is applied to the camera head 20 via the coaxial cable 13. This external synchronization coupling control signal is transmitted to the synchronization separation circuit 6.
As a result, SSG\12 is controlled and five desired signals (H5ync, V5ync,
B F , 'sc, sc) are created. A color signal is encoded using this, and a composite color video signal is applied from the encoder 3 to the coaxial cable 13 via the buffer 7 amplifier 4 and resistor 5B. Therefore, the signal in the coaxial cable 13 is a composite color video signal sent from the camera head 20 (Fig. 2b) and the external synchronization coupling control signal sent from the CCU 30 (Fig. 2C) superimposed. The waveform is as shown in a of FIG.

Cancellation times on the camera head 20 side! (5A, 5B
) subtracts the signal with the waveform of FIG. 2C from the signal with the waveform of FIG. 2a, so that the signal with the waveform of FIG. It is output from the operational amplifier 5A.

On the other hand, the cancellation circuit on the CCU3O side (14^, 14B
) is output from the operational amplifier 14^ and sent to the output terminal 21 from the signal with the waveform shown in FIG. 2a to the signal with the waveform shown in FIG. FIG. 3 shows signal waveforms of various parts centering on H5yne. Signal d is an external synchronization coupling control signal generated by the CCU 3O, e is an output signal of the synchronization separation circuit 6 of the camera head 20, and an output signal of the delay circuit 7.
f is the input signal of the delay circuit 7, g is C of the coaxial cable 13
The signal h on the CU 3O side is a superimposed signal of d and 8, that is, the signal in the coaxial cable 13, and 1 is the signal obtained by subtracting d from 11, that is, the output signal to the operational amplifier 14. In the figure, τD is the delay time due to the coaxial cable 13, and the delay amount τ of the delay circuit 7 is selected so that H5ync falls within the horizontal blanking period at the end of the main line when the coaxial cable 13 is at its minimum and maximum length. Ru.

The above operation is when an external synchronization signal is given, but
When no external synchronization signal is given, the synchronization signal generated by the 5SG12 of the camera head 20 is sent directly to the CC via the coaxial cable 13 as part of the composite color video signal.
It is applied to U 30 and sent to output terminal 21 via operational amplifier 148.

[Effect 1] As is clear from the above detailed explanation, in the video camera system of the present invention, in the CCU, the external synchronization coupling control signal transmitted from the signal on the coaxial cable to the camera head is removed by the cancellation circuit. Then, the composite color video signal transmitted from the camera head is detected and output directly to the CCU, so the position of the synchronization signal always matches the broadcasting standard. Therefore, even if the length of the coaxial cable changes, there is no need to manually adjust the position of the synchronization signal.

Furthermore, the circuit configuration for synchronous coupling between the CCU and the camera is simplified, which not only reduces cost but also improves response characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the video camera system of the present invention, FIGS. 2 and 3 are waveform diagrams explaining the operation of the system in FIG. 1, and FIG. 4 shows a conventional video camera system. The block diagram and FIG. 5 are waveform diagrams showing its operation.

Claims (3)

[Claims] (1) A video camera system consisting of a camera head, a camera control unit, and a coaxial cable connecting the two, wherein a video signal is sent from the camera head to the camera control unit via the cable, and the camera control unit A video camera system that sends an external synchronization coupling control signal synchronized with an external synchronization signal supplied to the unit from the outside to the camera head via the coaxial cable to control a synchronization signal generation circuit in the camera head, The camera head is provided with video signal canceling means for subtracting the video signal from the signal on the camera head side of the coaxial cable to extract the external synchronization coupling control signal, and the camera control unit is provided with video signal canceling means for subtracting the video signal from the signal on the camera head side of the coaxial cable. A video camera system comprising an external synchronous coupling control signal canceling means for subtracting the external synchronous coupling control signal from a signal on the unit side and extracting the video signal. (2) A video camera system consisting of a camera head, a camera control unit, and a coaxial cable connecting the two, wherein a video signal is sent from the camera head to the camera control unit via the cable, and the camera control unit Used in a video camera system that sends an external synchronization coupling control signal synchronized with an external synchronization signal supplied to the unit from the outside to the camera head via the coaxial cable and controls a synchronization signal generation circuit within the camera head. 1. A camera head, characterized in that said camera head is provided with a video signal canceling means for subtracting said video signal from a signal on said camera head side of said coaxial cable and extracting said control signal for external synchronization coupling. (3) A video camera system consisting of a camera head, a camera control unit, and a coaxial cable connecting the two, wherein a video signal is sent from the camera head to the camera control unit via the cable, and the camera control unit Used in a video camera system that sends an external synchronization coupling control signal synchronized with an external synchronization signal supplied to the unit from the outside to the camera head via the coaxial cable and controls a synchronization signal generation circuit within the camera head. In the camera control unit, the camera control unit is provided with an external synchronous coupling control signal canceling means for subtracting the external synchronous coupling control signal from the signal on the camera control unit side of the coaxial cable and extracting the video signal. Features a camera control unit.