JPS5919502Y2 - closed circuit television equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a closed circuit television device comprising a monitor receiver and a television camera.

In general closed-circuit television equipment, in order to ensure that a video signal is instantaneously derived from a television camera in a standby state at a predetermined time, conventionally only the heater of an image pickup tube, such as a videocon, is constantly preheated, and the necessary At times, it drove all the circuits in a television camera to obtain video signals.

In this case, preheating the image pickup tube heater is relatively easy for TV cameras that have a power supply circuit inside the camera case, but in this case, a power source is required near the TV camera, requiring electrical work and preheating from a distance. An extra control cable is required to switch between preheat and full power to control operation.

Furthermore, if a power supply circuit and horizontal/vertical oscillation circuit are installed on the TV camera side separately from the monitor receiver, the TV camera will become larger and more expensive, and the synchronization between the TV camera and the monitor receiver will not match, resulting in distorted images. was there.

The present invention was developed in view of these points, and it is an object of the present invention to provide a closed-circuit television device that can reduce the size and weight of a television camera and supply a stable image to a monitor receiver. The idea is to preheat the image pickup tube of a television camera so that images from the television camera can be instantaneously displayed on a monitor receiver at a predetermined time.

The present invention will be described below according to embodiments shown in the drawings.

The drawing particularly shows a circuit configuration diagram on the television camera side, where 1 is an image pickup tube, 2 is a video amplification circuit, 3 is a sync separation circuit, and 4 is a circuit configuration diagram on the television camera side.
5 is a rectifier circuit, 6 is a camera input/output terminal, and 7 is a transistor Q1. Q2. Q
3. Diode D1. D2, capacitor C1, resistor R
This is a heater voltage control circuit consisting of R1 to R5 and a variable resistor R1, and when in normal operation, horizontal and vertical synchronizing pulses are superimposed on the input/output terminal 6 from the monitor receiver side via the coaxial cable. The power supply voltage is supplied to drive each circuit within the television camera, and at the same time, a video signal from the television camera is supplied from the input/output terminal 6 to the monitor receiver via the same coaxial cable.

That is, when a synchronization pulse from the monitor receiver side η arrives at the input/output terminal 6, it is separated by the synchronization separation circuit 3 and supplied to the horizontal/vertical drive circuit 4, which is driven based on this pulse.

At this time, the horizontal and vertical pulses obtained from the horizontal and vertical drive circuit 4 are supplied to the image pickup tube 1, and the image pickup tube 1 is deflected and scanned. A voltage is generated.

The DC voltage is supplied to the heater voltage control circuit 7, and the transistor Q2. Q3 turns on and the transistor Q
A heater voltage is supplied from the monitor receiver side via 3.

In this case, the DC voltage obtained from the rectifier circuit 5 is
Therefore, the diode D2 is in a cut-off state, and at this time, a relatively high voltage (for example, about 9 mm) is applied to the heater of the image pickup tube 1.

As a result of the imaging operation of the imaging tube 1, the video signal obtained from the imaging tube 1 is amplified by the video amplifying circuit 2 and then supplied to the monitor receiver from the input/output terminal 6 via the coaxial cable.

However, when the above TV camera is on standby,
No synchronizing pulse is supplied from the monitor receiver side, and only the 10B power supply voltage is supplied.

Therefore, in this case, there is no output pulse from the synchronous separation circuit 3, the horizontal/vertical drive circuit 4 is not driven, and no DC voltage is derived from the rectifier circuit 5.

Therefore, diode D2 is turned on and resistor R4 and R
The divided voltage of 10B due to the voltage division ratio with 5 is the voltage of transistor Q2.
At this time, the conductivity of the transistor Q3 is suppressed, and a relatively low voltage (for example, about 6 V) is applied to the heater of the image pickup tube 1.

In this way, in the closed-circuit television apparatus of this embodiment, the horizontal and vertical synchronizing signals generated on the monitor receiver side are superimposed on the 10B power supply voltage and supplied to the television camera side, and the horizontal and vertical synchronizing signals generated on the monitor receiver side are superimposed on the 10B power supply voltage and supplied to the television camera side. In addition to driving the camera, the video signal obtained from the TV camera side is superimposed on the power supply voltage line using the same cable and returned to the monitor receiver, so a separate power supply circuit and oscillation circuit are required on the TV camera side. This makes it possible to make the television camera smaller and lighter without the need to provide a monitor, and it is also possible to obtain a synchronized and stable image on the monitor receiver side.

Furthermore, in this embodiment, a heater voltage control circuit is provided on the television camera side, and the synchronization pulse is not superimposed during standby, but the synchronization pulse is superimposed only when the television camera is being driven to drive each circuit within the television camera. The voltage supplied to the image pickup tube heater is controlled depending on the presence or absence of the synchronization pulse, and the image pickup tube heater is preheated even during standby, so the synchronization pulse must be supplied from the monitor receiver to the television camera at a predetermined time. The television camera will start operating instantly and the camera image will be displayed on the monitor receiver.

The closed circuit television device of the present invention is suitable as a monitoring device in which a television camera is installed at a front door.

[Brief explanation of drawings]

The drawing is a circuit configuration diagram of an embodiment of the present invention. 1... Image pickup tube, 3... Synchronization separation circuit,
4... Horizontal/vertical drive circuit, 5... Rectifier circuit, 6... Camera input/output terminal, 7...
...Heater voltage control circuit.

Claims (1)

[Scope of utility model registration request] In a device that superimposes the horizontal and vertical synchronizing pulses generated on the monitor receiver side on the power supply voltage and supplies the same to the television camera side to drive the television camera, a heater voltage control circuit is installed on the television camera side to control the synchronization signal. A closed circuit television device characterized in that a voltage supplied to a heater of an image pickup tube is controlled depending on the presence or absence of the heater.