JPS6115657Y2 - - Google Patents

Description

[Detailed description of the invention] This invention enables the camera to be used on the monitor side even when the distance between the camera installation position and the monitor TV is several tens of meters or more in a color television camera device used for surveillance purposes. The present invention provides an apparatus for obtaining a color image with good reproducibility by adjusting the color temperature of the image, the pedestal, etc.

Conventionally, in order to miniaturize the camera head, the camera control unit was separated from the camera head and the two were electrically connected using a multi-core camera cable, which is often seen in portable color television cameras. , It is disadvantageous to extend the multi-core camera cable for a long time for the following reasons.

(b) Camera cables need to be thin and flexible so that they can be easily constructed, and they need to be cheap.In particular, it is better to have fewer cores, especially thick and expensive wires like coaxial cables. desirable.
In the case of the above type, horizontal and vertical synchronization signals for beam deflection of the image pickup tube must be transmitted from the camera control unit to the camera head, and the longer the cable, the more special wires are required.

(b) If the video signal output from the camera head is in the three primary colors of R, G, and B, three coaxial cables are required, and the low-range luminance signal and high-range color signal are If multiplexed, the ratio between the two changes depending on the length of the cable, making accurate color reproduction difficult.

(c) With the recent development of semiconductor technology in particular, it has become possible to make the camera control unit and camera head compact enough for practical use even if the camera control unit and camera head are integrated. Furthermore, in the case of color television cameras using solid-state image sensors, which are expected to become popular in the future, the synchronization circuit system and the image sensor are tightly coupled, so it is often inconvenient to separate the camera head and camera control unit.

For the above reasons, in the case of a system that connects the monitor TV and camera with a long cable,
It is disadvantageous to separate the camera section into the camera head and camera control unit as described above and extend the distance between them.The two should be integrated, or even if they are separated, the distance between them should not be extended and the output cable of the camera control unit should be It is better to extend the That way, you only need one coaxial line for the video output signal. However, even in this case, the power supply section is usually separated from the camera section to reduce the size of the camera section.

By the way, in the case of a color television camera,
Unlike with the naked eye, depending on the color temperature of the subject's lighting, the image may appear more red or blue, so the ratio of the three primary colors must be corrected with circuit gain to obtain natural color reproduction.

It is desirable to be able to adjust the color temperature and other settings such as the pedestal to suit the lighting and image while watching a TV monitor.

FIG. 1 shows an example of the configuration of a monitoring color television camera that takes the above points into consideration. In the figure 1
1 is a camera unit, which integrates the camera head and most of the camera controls.
A power supply section 3 is installed near the monitor television 5, and the two are electrically connected via a coaxial cable 4. The power supply section 3 and the camera section 1 are connected by a multicore cable 2, and this cable can be made long depending on the purpose. The power supply section 3 has the following three functions.

supplying a power supply voltage to the first camera unit 1;
Has a second color temperature and pedestal adjustment knob,
controlling the color temperature of the camera unit 1 and the pedestal circuit by sending a DC voltage according to the setting of the knob;
Thirdly, the video signal output from the camera section 1 is
If the cable 2 is long, it will be attenuated, so the frequency characteristics must also be compensated for.

Now, the problem with the device shown in FIG. 1 is the voltage drop in the cable 2. Generally, when the cable is short or the current flowing is small, the voltage drop due to the resistance of the cable can be ignored, but when the cable is long and a considerable amount of current flows, it becomes too large to be ignored, even if the power supply section sends a constant voltage. The power input voltage of the camera section will vary depending on the length of the cable and current consumption. Making the power supply current supply line thicker will reduce the voltage drop due to the cable, but it cannot be made too thick due to ease of construction and cost reasons, so there will be a considerable voltage difference between short and long cables. . It is not preferable for the constant voltage circuit in the camera section 1 to absorb this change in voltage from the viewpoint of downsizing and heat dissipation.

Therefore, as a means of supplying constant voltage to the camera unit 1 without being affected by the length of the cable 2, a remote controlled constant voltage power supply using remote sensing is known, and Fig. 2 shows an example of this. , the upper half is the circuit. To explain, lines 2b and 2c for detecting the input voltage of the camera section 1 are provided separately from the lines 2a and 2d for supplying power supply current.
The constant voltage circuits 6 and 7 are operated so that the voltage between b and 2c is constant, and the resistance Ra of wire 2a and the resistance of wire 2d are
The voltage drop caused by the resistor Rd is prevented from affecting the input voltage of the camera section 1. Since the control section 7 of the constant voltage circuit has to absorb voltage changes due to the length of the cable, which increases the burden, a switching system is more suitable than a series type constant voltage power supply.

On the other hand, in order to remotely control the color temperature and pedestal settings using the power supply unit 3, a direct current control system is suitable since it does not require special cables and has a simple circuit. Current mode and voltage mode can be considered for DC control, but current mode has the characteristic that it is unaffected even if there is a potential difference between the control part and the controlled part, but a constant current circuit is required for each control signal. The circuit becomes complicated. On the other hand, in the voltage mode, if the control part and the controlled part can have a common potential, DC control can be performed with a simple circuit.

In the present invention, the color temperature and the pedestal are remotely controlled by this voltage mode direct current control, and the common potential necessary for this purpose is obtained from the remote sense lines 2b and 2c of the remote control power source.

FIG. 2 shows an embodiment of the present invention, which will be explained below based on the figure.

As explained above about the remote control type constant voltage circuit, if the impedance of the remote sense wires 2b, 2c on the power supply 3 side is high enough, the wires 2b, 2c
There is no current flowing through the wires, and there is no voltage drop due to the wire resistances Rb and Rc. Therefore, points B and C of the power supply section have the same potential as points A and D of the power input section of the camera section 1, respectively, and serve as a reference for DC control.

The color temperature setting variable resistor 10 divides the reference voltage between points B and C to create a control voltage for color temperature setting, which is made low impedance by the emitter follower 11 and transmitted through the cable 2e. The color temperature control circuit 26 of the camera unit 1 receives this at high impedance and controls the variable gain circuits 24 and 25, so that, for example, when the color temperature is set high, the gain for red is large and the gain for blue is small. .

The adjustment of the pedestal is the same, and the variable resistor 12
The control voltage generated is transmitted to the pedestal control circuit 27 of the camera unit 1 through the emitter follower 13 and the cable 2f, and acts on each of the R, G, and B process amplifiers 21, 22, and 23 to control the pedestal.

In FIG. 2, R _a , R _b , R _c , R _d , R _e , R
_f is the resistance of the lines 2a, 2b, 2c, 2d, 2e, 2f, 14 is the amplitude and frequency correction circuit, 15, 1
4 is a protective resistor in case the remote sense line becomes open, 16, 17, 18 are resistors and semi-fixed resistors for setting the power supply voltage of camera unit 1, and 28 is a matrix and encoder that creates an NTSC composite color signal. It is. 29 and 30 are capacitors for removing noise AC components appearing in the DC control lines 2e and 2f, 8 is a rectifier, and 9 is a power transformer.

Thus, according to the present invention, it is possible to remotely adjust a color television camera located far away with low cable costs.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram of a color television camera device according to an embodiment of the present invention, and FIG. 2 is a specific circuit diagram of the same device. 1...Camera part, 2...Multi-core camera cable,
3...Power supply unit, 4...Video signal cable, 5
... Monitor TV, 6 ... Error detection/amplifier in constant voltage circuit, 7 ... Control section of constant voltage circuit, 10
...Color temperature adjustment variable resistor, 12...Pedestal adjustment variable resistor, 2a, 2d...Power supply current supply line, 2
b, 2c...Remote sense line, 2e, 2f...
Color temperature and pedestal control line, 2g... coaxial cable for video signal.

Claims (1)

[Scope of utility model registration request] In a color television camera device in which the power supply voltage of the camera unit is supplied from a power supply unit located in a separate location from the camera unit, a line for detecting the power supply voltage of the camera unit is provided separately from a line for supplying power supply current. In addition to supplying a constant voltage to the camera unit, the camera unit's color temperature adjustment circuit, pedestal adjustment circuit, etc. are remotely controlled by DC voltage from the power supply side, and the reference potential necessary for this DC voltage control is A color television camera device characterized in that the voltage is obtained by the voltage detection line.