JPH05316416A - Lens diaphragm control system - Google Patents

Abstract

PURPOSE:To attain a stable automatic diaphragm operation of a lens with high accuracy by controlling the diaphragm a varied summing coefficient to a deviation signal depending on the positive and negative deviation signal. CONSTITUTION:A detection section 9 detects a peak level of a video signal, a differential comparison section 11 compares the level with a reference voltage 10 and outputs a deviation signal as the result of comparison. A deviation signal processing section 15 discriminates the polarity of the deviation signal from the differential comparison section 11, implements the processing based on a function set accordingly and converts the input output characteristic of the deviation signal depending on the polarity and outputs the result. A deviation signal addition section 12 adds the deviation signal and a signal from an aperture position signal output 14 and gives the result to an aperture control motor 1 as an aperture control signal input 13. The aperture control motor 1 implements opening/closing depending on the polarity of the deviation signal so that the operating speed of the aperture 4 in the opening direction is equal to that in the closing direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic aperture control system for lenses in TV cameras.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing a conventional automatic lens aperture control system. In the figure, 1 is a diaphragm adjusting motor,
2 is a potentiometer, 3 is a lens, 4 is a diaphragm, 5 is an image sensor, 6 and 7 are video signal amplifiers, 8 is a video signal output, 9 is a detector, 10 is a reference voltage, 11 is a differential comparator. ,
Reference numeral 12 denotes a displacement signal adding unit, 13 denotes an aperture control signal input, and 14
Is an aperture position signal output. Next, the operation of the automatic lens diaphragm control system having the above configuration will be described. The detection unit 9 detects the peak level of the video signal, the differential comparison unit 11 compares it with the reference voltage 10, and outputs the displacement signal as a comparison result. Then, the displacement signal adder 12 adds the aperture position signal output 14 and the displacement signal, and supplies them as the aperture control signal output 13 to the aperture adjusting motor 1 to open and close the aperture 4. As a result, the level of the video signal changes, and the diaphragm 4 is adjusted so that the detection signal of the detection unit 9 and the reference voltage 10 become equal.
Is controlled. The above operation is repeated to perform automatic lens aperture control.

[0003]

In the conventional method, when the operating speed of the lens diaphragm is mechanically different between the opening direction and the closing direction, fine opening and closing are repeated or stabilized until the diaphragm position stabilizes. There is a drawback that the time error becomes large. It is an object of the present invention to eliminate these drawbacks and to realize a TV camera having an automatic aperture control function capable of highly accurate and stable operation.

[0004]

In order to achieve the above object, the present invention compares a video signal level with a reference voltage, adds the comparison result as a displacement signal to an aperture position signal output, and outputs an aperture control signal. In the lens diaphragm control system that controls the lens diaphragm so that the video signal level matches the reference voltage, the deviation signal is added as a positive deviation signal and a negative deviation signal. It is configured to control by changing the coefficient.

[0005]

As a result, since the operating speed of the lens diaphragm is the same in the opening direction and the closing direction, the opening and closing is not repeated until the lens diaphragm position is stabilized at the optimum position, and the lens diaphragm can be controlled accurately. I can.

[0006]

1 is a block diagram showing the configuration of a lens diaphragm control system according to the present invention. In FIG. 1, 1 is a diaphragm control motor, 2 is a potentiometer, 3 is a lens, and 4 is a lens.
Is an aperture, 5 is an image sensor, 6, 7 is a video amplifier, 8 is a video signal output, 9 is a detector, 10 is a reference voltage, 11 is a peak level of the video signal, and the reference voltage 10 is compared to obtain a deviation signal. Is output as a comparison result, 12 is an excursion signal adder, 13 is an aperture control signal input, 14 is an aperture position signal output, and 15 is a positive or negative polarity of the excursion signal. Is a deviation signal processing unit that performs processing based on the set function and converts the input / output characteristics of the deviation signal according to its polarity.

Next, the operation of the automatic diaphragm control system having the above configuration will be described. The detector 9 detects the peak level of the video signal, the differential comparator 11 compares it with the reference voltage 10, and outputs the displacement signal as a comparison result. here,
The displacement signal processing unit 15 determines whether the polarity of the displacement signal output from the differential comparison unit 11 is positive or negative, performs processing based on the function set corresponding to each, and inputs / outputs the displacement signal. Converts the property according to its polarity. Then, the deviation signal adding unit 12 adds the deviation signal and the signal from the diaphragm position signal output 14 and outputs the result as the diaphragm control signal input 13, thereby supplying the diaphragm control motor 1 with the deviation signal. The opening / closing is performed according to the polarity of the signal, that is, the operation speed of the diaphragm 4 is the same in the opening direction and the closing direction. As a result, the level of the video signal changes, and the diaphragm 4 is controlled so that the detection signal of the detection unit 9 and the reference voltage 10 become equal. The above operation is repeated to perform automatic lens aperture control.

[0008]

According to the present invention, since the operating speed of the lens diaphragm is the same in the opening direction and the closing direction, it is possible to realize a TV camera having an automatic diaphragm control function capable of highly accurate and stable operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a conventional automatic aperture control method.

FIG. 2 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

9: Detection unit, 10: Reference voltage, 11: Differential comparison unit, 1
2: deviation signal adder, 13: aperture control signal input, 14:
Aperture position signal output, 15: deviation signal processing unit.

Claims (1)

[Claims] 1. A video signal level is compared with a reference voltage, and the comparison result is added as an excursion signal to an aperture position signal output,
In the lens diaphragm control system, which supplies the diaphragm control signal as an output to the diaphragm adjusting motor and controls the lens diaphragm so that the video signal level matches the reference voltage, the positive bias signal and the negative bias signal are used to shift the bias. A lens aperture control method that controls by changing the addition coefficient of the position signal.