JPH0638634B2 - Video camera system and camera head and camera control unit used therefor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera system, and more 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 synchronously coupled with an external synchronization signal. Regarding the improvement of.

[Prior Art] In a commercial 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, a video signal is sent from the camera head to the CCU via this coaxial cable, and when an external synchronization signal from another camera head or the like is given to the CCU, this is sent to the coaxial cable. Is supplied to the camera head via the, and the internal synchronizing signal generating circuit is controlled.

As a method of transmitting an external synchronizing signal or a signal synchronized with the external synchronizing signal to the camera head, there is a method of removing the synchronizing signal of the video signal of the camera head, inserting the external synchronizing signal in the period, and sending back. That is, in the system block diagram of FIG. 4, the camera head 20 'takes out the external synchronizing signal transmitted from the CCU 30' and uses it for the synchronous coupling of the synchronizing signal generating circuit. Further, the CCU 30 'removes the external synchronizing signal transmitted to the camera head 20' from the signal on the coaxial cable 13 and outputs the synchronizing signal generated by the synchronizing signal generating circuit 19 which is synchronously coupled to the external synchronizing signal in the CCU 30 '. Add and CCU
Output from the output terminal 21 as an output composite video signal.

FIG. 5 is a signal waveform diagram in the conventional video camera system of FIG. From this figure, it can be seen that the signal on the coaxial cable 13 is a signal in which the video signal from the camera head 20 'and the synchronizing signal from the CCU 30' are superimposed.

[Problems to be Solved by the Invention] In the conventional video camera system, the configuration and operation are complicated because the synchronization signal generation circuit is provided in both the camera head and the CCU. That is, when performing internal synchronization, C
The synchronization signal generation circuit in the CU controls the synchronization signal generation circuit in the camera head to perform synchronous coupling, but when an external synchronization signal from another camera head or the like is given to the CCU, double synchronization coupling is performed. Therefore, it is troublesome to set various characteristics to obtain the optimum response, and the cost tends to be high.

Further, since the transmission signal is delayed depending on the length of the coaxial cable, assuming that the delay time is τ _D , when the external synchronizing signal is sent from the CCU to the camera head, a delay of 2 τ _D is required in the round trip of the coaxial cable. . Because of this delay eg Hsync
There is a case where the position of is shifted from the predetermined position of the broadcast standard and gets into the video signal. In order to prevent such a problem, it is necessary to adjust the position of Hsync by providing a delay compensation circuit in the camera head.

Therefore, the present invention provides a video camera system that realizes synchronous coupling between a camera head and a CCU with a simple structure and at low cost, and can perform both internal synchronization and external synchronization through a single coaxial cable. To aim.

[Means for Solving the Problem] In order to solve the above-mentioned conventional problems and to achieve the above-mentioned object, the present invention is provided with a synchronization signal generating circuit only in the camera head, and the composite video signal transmitted from the camera head as it is. While outputting as a composite video signal from the CCU, the CCU
The external sync signal is superimposed on the composite video signal as it is, transmitted to the camera head, and the camera sync signal and external sync signal that overlap on the coaxial cable are removed by the camera head and external sync signal by the CCU section. A cancel circuit is provided to remove each.

That is, according to the present invention, a video camera system comprising a camera head, a camera control unit, and a coaxial cable connecting the two, wherein the 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 externally supplied to the camera control unit to the camera head via the coaxial cable to control a synchronization signal generation circuit in 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 synchronous coupling control signal, and the camera control unit is provided with the coaxial cable. The turtle Video camera system is provided, characterized in that the signal in the control unit side provided with the external synchronization coupling control signal canceling means for retrieving the video signal by subtracting the external synchronization coupling control signals. According to the present invention, there is also 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 externally supplied to the camera control unit to the camera head via the coaxial cable to control a synchronization signal generation circuit in the camera head. In the camera head used in the system, the camera head is provided with video signal canceling means for subtracting the video signal from a signal on the camera head side of the coaxial cable and extracting the external synchronous coupling control signal. The head is provided and the camera A video camera system comprising a camera, 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 is externally supplied to the camera control unit. In a camera control unit used in a video camera system, which sends a control signal for external synchronization coupling synchronized with an external synchronization signal supplied to the camera head via the coaxial cable, and controls a synchronization signal generation circuit in the camera head. 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 to extract the video signal. Control unit is provided.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. First
FIG. 1 is a block diagram showing an embodiment of a video camera system of the present invention. This video camera system is composed of a camera head 20, a CCU 30, and a coaxial cable 13 connecting them, but differs from the conventional video camera system of FIG. 4 in the following points. That is, the synchronization signal generation circuit (SSG) is provided only in the camera head 20, and C
It is not provided in the CU 30, and a signal cancel circuit described later is provided in both the camera head 20 and the CCU 30.

In FIG. 1, the camera head 20 includes an imager 1 including a light receiving element, a process matrix 2 for processing the output signal thereof, and an encoder 3 for producing a composite color television signal from the output signal. The output signal of the encoder 3 is a buffer amplifier. 4 and resistor 5B to the end of the coaxial cable 13 on the camera head side. Both ends of the resistor 5B are connected to two inputs of an operational amplifier 5A used as a subtractor. The operational amplifier 5A and the resistor 5B form a video cancel circuit.

The output of the operational amplifier 5A is given to the sync separation circuit 6, where the horizontal sync signal (Hsync) and the vertical reset signal (Vrese
t) is obtained. Hsync is applied to the other input of the phase comparator 8 whose output signal from the delay circuit 7 is applied to one input, and its output is passed through the reduction filter (LPF) 9 to the synchronization signal generation circuit (SSG). Is given to. or
Hsync is SSG1 via pulse width detection circuit 10 and LPF11.
2 and the Vreset signal from the sync separation circuit 6 is also provided to SSG12. As the SSG 12, an IC integrated circuit can be used, and the internal configuration thereof is as shown in the figure. However, since this circuit configuration is the same as the conventional one, description thereof will be omitted.

The above-mentioned delay circuit 7 delays the horizontal synchronizing signal output from the counter pulse generating circuit of the SSG 12 by the time τ determined by the delay time τ _D of the coaxial cable 13. In the conventional circuit, the delay time is 2τ _D. It is τ. The three output signals of SSG12, that is, the burst flag (BF) and the two subcarriers (SC) having 90 ° different phases are sent to the encoder 3 and the three signals from the process matrix 2, Y, RY, and A composite color video signal is created using BY.

When an external synchronizing signal (EXT VBS) from another camera head (not shown) comes in, the CCU 30 receives a sync separation circuit.
Hsync and Vsync are separated at 15, and Hsync is a pulse width modulation circuit 1
It is given to one input of AND gate 18 via 7
nc is supplied to the other input of the AND gate 18. AND
The output of the gate 18 is C of the coaxial cable 13 via the resistor 14B.
It is given to the end portion on the CU side, and both ends of this resistor 14B are given to the two inputs of the operational amplifier 14A constituting the subtractor. The operational amplifier 14A and the resistor 14B form a control signal cancel circuit for external synchronous coupling. The output of the operational amplifier 14A is given as an output signal of the CCU 30 to the output terminal 21, is also given to one input of the phase comparator 16, and is compared in phase with the external synchronizing signal given to the other input, and the output signal of the comparison result. Is used as a control signal for the pulse width modulation circuit. The circuits 15, 16, 17, and 18 generate an external synchronous coupling control signal in synchronization with the external synchronous signal, and the external synchronous coupling control signal is supplied to the camera head via the resistor 14B and the coaxial cable 13. Sent to 20.

Although the SSG 19 is provided in the CCU 30 'in the conventional circuit of FIG. 4, such SSG is not used in the present invention.

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

When the external sync signal is applied to the CCU 30, the external sync coupling control signal is generated by the CCU 30 as described above and applied to the camera head 20 via the coaxial cable 13. This external synchronous coupling control signal is given to the synchronous separation circuit 6, and as a result, the SSG 12 is controlled, and the desired 5 signals (Hsync, Vsyn).
c, BF, SC, SC) are created. The color signal is encoded using this, and the composite color video signal is given from the encoder 3 to the coaxial cable 13 via the buffer amplifier 4 and the resistor 5B. Therefore, the signal in the coaxial cable 13 is a superposition of the composite color video signal sent from the camera head 20 (Fig. 2b) and the external synchronous coupling control signal sent from the CCU 30 (Fig. 2c). The waveform is as shown in FIG.

The cancel circuit (5A, 5B) on the side of the camera head 20 subtracts the signal of the waveform of FIG. 2b from the signal of the waveform of FIG. 2a, so that the signal of the waveform of FIG. CC
Control signal for external synchronous coupling made by U30 is operational amplifier 5
It is output from A.

On the other hand, the cancel circuit (14A, 14B) on the CCU 30 side is the second
From the signal of the waveform of FIG. 2A, the signal of the waveform of FIG. 2C, that is, the composite color signal produced by the camera head 20 is output from the operational amplifier 14A and sent to the output terminal 21. FIG. 3 shows the signal waveform of each part centering on Hsync. The signal d is an external synchronous coupling control signal made by the CCU 30, e is the output signal of the sync separation circuit 6 and the output signal of the delay circuit 7 of the camera head 20, f is the input signal of the delay circuit 7, and g is the coaxial cable 13. A signal on the CCU 30 side, h is a superimposed signal of d and g, that is, a signal in the coaxial cable 13, and i is a signal obtained by subtracting d from h, that is, an output signal of the operational amplifier 14A. In the figure, τ _D is the delay time due to the coaxial cable 13, and the delay amount τ of the delay circuit 7 is selected so that the Hsync is within the original horizontal blanking period for both the minimum and maximum lengths of the coaxial cable 13. To be done.

The above operation is when an external synchronization signal is given.
When no external sync signal is given, the camera head
The sync signal generated by the 20 SSG 12 is given as it is to the CCU 30 via the coaxial cable 13 as a part of the composite color video signal, and is sent to the output terminal 21 via the operational amplifier 14A.

[Effect] As is apparent from the above description in detail, 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 cancel circuit. Then, since the composite color video signal transmitted from the camera head is detected and directly output as CCU, the position of the synchronization signal always conforms to the broadcasting standard. Therefore, even if the length of the coaxial cable changes, it is not necessary to manually adjust the position of the sync signal.

Further, the circuit configuration for synchronously coupling the CCU and the camera head is simplified, and not only the cost is reduced, but also various response characteristics are improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a video camera system of the present invention, FIGS. 2 and 3 are waveform charts for explaining the operation of the system of FIG. 1, and FIG. 4 is a conventional video camera system. A block diagram and FIG. 5 are waveform diagrams showing the operation. 1 ... Imager, 2 ... Process matrix 3 ... Encoder, 4 ... Buffer amplifier 5A, 14A ... Operational amplifier, 5B, 14B ... Resistor 6, 15 ... Sync separation circuit, 7 ... Delay circuit 8, 16 ...... Phase comparator, 12 …… Synchronous signal generation circuit 13 …… Coaxial cable, 20 …… Camera head 21 …… Output terminal, 30 …… CCU

Claims (3)

[Claims] 1. A video camera system comprising a camera head, a camera control unit, and a coaxial cable connecting them, wherein a video signal is sent from the camera head to the camera control unit via the cable, A video camera system for sending a control signal for external synchronization coupling synchronized with an external synchronization signal externally supplied to the camera control unit to the camera head via the coaxial cable to control a synchronization signal generation circuit in the camera head. In the camera head, video signal canceling means for extracting the video signal from the signal on the camera head side of the coaxial cable to extract the external synchronous coupling control signal is provided, and the camera control unit is provided with the coaxial cable. Camera control Video camera system, characterized in that from the signal at the Ruyunitto side provided with external synchronization coupling control signal canceling means for retrieving the video signal by subtracting the external synchronization coupling control signals. 2. A video camera system comprising a camera head, a camera control unit, and a coaxial cable connecting them, wherein a video signal is sent from the camera head to the camera control unit via the cable, A video camera system for sending a control signal for external synchronization coupling synchronized with an external synchronization signal externally supplied to the camera control unit to the camera head via the coaxial cable to control a synchronization signal generation circuit in the camera head. In the camera head used for, the camera head is provided with video signal canceling means for subtracting the video signal from a signal on the camera head side of the coaxial cable to take out the external synchronous coupling control signal. . 3. A video camera system comprising a camera head, a camera control unit, and a coaxial cable connecting them, wherein a video signal is sent from the camera head to the camera control unit via the cable, A video camera system for sending a control signal for external synchronization coupling synchronized with an external synchronization signal externally supplied to the camera control unit to the camera head via the coaxial cable to control a synchronization signal generation circuit in the camera head. In the camera control unit used for the above, 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 to take out the video signal. A camera control unit, wherein the door.