JPH0385874A - Television camera system - Google Patents

Abstract

PURPOSE:To prevent damage to a component in a circuit by operating a mis- connection interrupt circuit so as to stop a power supply quickly when a prescribed television camera is not connected to a power unit or the television camera is faulty and short-circuited. CONSTITUTION:A mis-connection interrupt circuit 12 is provided with a video signal detection circuit 11, a power supply starter circuit 2, a power ON/OFF control circuit 8, and the video signal detection circuit 11 is provided with a synchronizing separator circuit 5, a rectifier circuit 6 and a comparator 7. When a video signal is not outputted from a television camera main body 3 (due to a broken cable or a short-circuited cable), since no video signal is outputted, no synchronizing separation is implemented and the comparator 7 discriminates the absence of the video signal. Then the power ON/OFF control circuit 8 is turned off and the current supply from a constant current power output circuit 1 is stopped. Thus, the damage of a component in the circuit is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply superimposition television camera system in which direct current and video signals are superimposed and transmitted on two coaxial lines.

[Conventional technology]

Traditionally, in TV camera systems that use power superimposition, there are problems when the connection is incorrect, when the camera is not connected, or especially when the camera is malfunctioning and does not output a normal signal (such as when the signal line is short-circuited). ), a constant current was also sent out from the constant current power supply output circuit.

[Problem to be solved by the invention]

Therefore, if current flows during such incorrect connections or short circuits, there is a drawback that it may damage the incorrectly connected equipment or the components in the circuit of the power superimposition TV camera system. .

[Means to solve the problem]

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks, and includes a DC cut capacitor, an input buffer,
It has an output buffer, a power supply starter circuit, a sync signal separation circuit, a rectifier circuit, a comparator, and a erroneous connection cutoff circuit consisting of a 'KIR on/off control circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In the figure, a power unit (power unit) 13 for a power superimposing TV camera system and a TV camera 14 of a power superimposing system are -
The power unit 13 for the television camera system, which uses a power superimposition method, is connected by a main coaxial cable, and includes a power supply circuit 10, a constant current power output circuit 1, and an incorrect connection cutoff circuit 1.
2, input buffer 4, output buffer 9, capacitor C1
and a capacitor C2, and the incorrect connection cutoff circuit 12 includes:
There are a video signal detection circuit 11, a power starter circuit 2, a power on/off control circuit 8, and a video signal detection circuit 1.
1 includes a synchronizing signal separation circuit 5, a rectifier circuit 6, and a comparator 7.

The power supply starter circuit 2 supplies a constant current of 1. Coaxial goo. It is supplied to the television camera body 3 through a pull process. When a video signal is output from the television camera body 3, it is sent via a coaxial cable to a power unit 13 for a television camera system using a power superimposition method. Therefore, after the DC current is cut off by the capacitor C2, the synchronizing signal is separated by the synchronizing signal separation circuit 5 via the input buffer 4. After the signal is rectified by the rectifier circuit 6, the comparator 7 determines that the video signal has been output, the power on/off control circuit 8 is turned on, and a constant current is continuously sent from the constant current power output circuit 1. .

Here, if the video signal is not output from the television camera body 3 (due to a cable break or short circuit, etc.), the video signal is not output, so the synchronization signal separation circuit 5 does not perform synchronization separation, and the comparator 7 detects the video signal. It is determined that it does not exist, the power on/off control circuit 8 is turned off, and the supply of current from the constant current power output circuit 1 is stopped.

〔Effect of the invention〕

As explained above, the present invention provides a power superimposition type television camera system with an incorrect connection cutoff circuit (video signal discrimination circuit) to automatically cut off the current supply when an abnormal phenomenon occurs in the television camera body. can be stopped,
This has the effect of preventing damage to components in the circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a power superimposed camera system according to an embodiment of the present invention. 1... Constant current power supply output circuit, 2... Power supply starter circuit, 3... TV camera body, 4
...Input buffer, 5 ... Synchronous signal separation circuit, 6 ... Rectifier circuit, 7 ... Comparator, 8 ... Power on/off Off control circuit, 9...output buffer, 10...power supply circuit, 11...video signal detection circuit, 12...
...Incorrect connection cutoff circuit, work 3... Power unit for TV camera system with power superimposition method, 14...
...TV camera with superimposed power system.

Claims (1)

[Claims] In a television camera system that transmits a direct current and a video signal in a superimposed manner on a single coaxial line, the power unit of the system has an erroneous connection cutoff circuit based on the presence or absence of the output signal of the television camera; A television camera system characterized in that when a predetermined television camera is not connected or when the television camera is malfunctioning and short-circuited, the erroneous connection cutoff circuit operates and promptly stops power supply.