JPS6150326B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a surveillance television camera device, for example, which has a power supply section located away from a load circuit section and connects the two with a cable to supply power. This invention relates to a remote control device that can be used for.

Configuration of conventional example and its problems In a surveillance television camera device, the power supply cable is also used as a signal transmission cable. FIG. 1 shows a conventional example of its configuration. In the figure, 1 is a power supply section, and 2 is a load circuit section, for example, a television camera section. The power supply unit 1 supplies power from a constant current power supply 3 to a cable 5 through a buffer circuit 4. On the other hand, the load circuit section 2 which receives the power supplies a constant voltage to the load circuit 8 through the buffer circuit 6 and from the parallel constant voltage circuit 7 . On the other hand, the output signal from the television camera, which is the load circuit section 2, is outputted to the cable 5 through the capacitor 9, and is transmitted to the power supply section 1 via the cable 5, and then the capacitor 10
It is retrieved by In addition, the buffer circuits 4 and 6
has the function of separating the signal and power components so that they do not interfere. In this way, in the circuit shown in Figure 1, the power supply cable and the signal transmission cable are used both, and only one coaxial cable is required.

By the way, in such surveillance television camera equipment, the main power of the camera is turned off except when taking images, mainly to extend the life of the image pickup tube and to save power consumption.
On the other hand, a preheating method is often used in which only the heater of the image pickup tube is preheated so that an image is displayed instantly when necessary. If switching between the preheat state and the imaging operation can be performed from the power supply section 1, it will be extremely user-friendly in terms of operation.

Purpose of the Invention In view of the above points, an object of the present invention is to provide a device that can perform switching control of the operation of a load circuit from a power supply section without increasing the number of cables between the power supply section and the load circuit section. It is.

Structure of the Invention In the present invention, a cable for power supply is also used for transmitting control signals for controlling the operating state of the load circuit section, and when the control signal supplied from the power supply section is changed, the load circuit This system detects changes in the input voltage of the power supply and switches and controls the operation of the load circuit.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, parts having the same functions as those in FIG. 1 are given the same numbers. The power supply unit 1 constitutes a constant current power supply, and its basic configuration is very similar to a commonly used series type constant voltage circuit. As a result, the current flowing through the resistor 11 becomes constant. 13 is a DC power supply for controlling the operating state of the load circuit section 2; 14 and 15 are voltage dividing resistors for dividing the voltage of this DC power supply 13; 16 is a switch for switching the output current of this constant current power supply; is connected to one terminal + of the error detection amplifier 12. One fixed terminal 1 of this switch 16
6a is connected to the positive electrode of the DC power supply 13, and the other fixed terminal 16b is connected to the connection point of the voltage dividing resistors 14 and 15. 17 is a series control transistor controlled by the output of the error detection amplifier 12; 18 is an AC power input terminal; 19 is a power transformer;
20 is a rectifier circuit, and 21 is a smoothing capacitor.

On the other hand, in the load circuit section 2, 22 is an image pickup tube;
3 and 24 are transistors and constant voltage elements that control current supply to the heater of the image pickup tube 22 according to the state of the switch 16, 25 is a buffer transistor, and 26 and 27 are transistors that control on/off of the buffer transistor 25. transistor and constant voltage element.

In the above configuration, the switch 16 is connected to the terminal 16a.
When tilted to the side, a constant current sufficient for all operations of the load circuit section 2 is sent from the power supply section 1. At this time, the load 8 of the load circuit section 2 includes a transistor 2.
5 and 26 are turned on, a specified power supply voltage is applied by the action of the parallel constant voltage circuit 7. Here, a voltage of several volts is applied to the buffer transistor 25, so the potential at point a is several volts higher than the power supply voltage at point b. On the other hand, a prescribed voltage is applied to the heater of the image pickup tube 22 by the function of the transistor 23 and the constant voltage element 24, which operate as a constant voltage circuit. In this way, the load circuit section 2 is brought into a normal operating state.

Next, when the switch 16 is turned to the terminal 16b side, the potential of the + side terminal of the error detection amplifier 12 decreases, the conductivity of the transistor 17 decreases, and the output current from the power supply section 1 decreases. This current is, for example, about 20% smaller than the current when the switch 16 is in full operation when the switch 16 is turned to the terminal 16a side, so the potential at point a of the load circuit section 2 is about half that when it is in full operation. Go down. The transistor 26 and the constant voltage element 27 detect this change in potential, and the transistor 26 itself turns off, thereby turning off the transistor 25. Therefore, the constant voltage circuit 7 does not operate, and the load 8 is not supplied with power. On the other hand, the transistor 23 becomes completely conductive, and almost all of the output current from the power supply section 1 flows into the heater of the image pickup tube 22. This results in a so-called preheat state. In this way, by switching the switch 13 in the power supply section 1, all operations of the television camera, which is the load circuit section, and switching between the preheat states can be controlled.
It goes without saying that the output signal from the television camera passes through the capacitor 9 and is obtained from the capacitor 10 via the cable 5.

Effects of the Invention As described above, according to the present invention, by providing the power supply cable with the function of transmitting the switching control signal of the load circuit, the number of cables is not increased and it is extremely convenient in practice. Particularly in the case of a surveillance television camera device, a single coaxial cable can serve as power supply, image signal transmission, preheating, and switching of all operations.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a conventional surveillance television camera device, and FIG. 2 is a circuit diagram showing the configuration of a surveillance television camera device to which a remote control device according to an embodiment of the present invention is applied. . DESCRIPTION OF SYMBOLS 1... Power supply section, 2... Load circuit section, 5... Coaxial cable, 7... Constant voltage circuit, 8... Load, 11... Resistor for current detection, 12... Error detection amplifier, 13... DC power supply, 14, 15... For voltage division Resistance, 16...Switch,
17, 23, 25, 26...transistor, 22...
Image pickup tube, 24, 27...constant voltage element.

Claims (1)

[Claims] 1. A cable is provided that connects the power supply section and the load circuit section, supplies power from the power supply section to the load circuit, and transmits signals between them, and the power supply section is connected to the load circuit section via the cable. A switching means is provided to switch the power supplied to the device between high power and low power.
The load circuit section includes a first transistor connected in series between the cable and a first load circuit such as a heater for an image pickup tube, and the first transistor operates as a constant voltage circuit when large power is supplied. A first transistor connected to the base side of the first transistor so as to operate in a conductive state when small power is supplied.
a constant voltage element; a second transistor connected in series between the cable and the second load circuit; the second transistor is operated in a conductive state when a large power is supplied; a circuit including a second constant voltage element connected to the base side of the second transistor so as to turn off the second transistor.