JP2710170B2 - Automatic aperture adjustment device for TV camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic iris adjusting device for a television camera.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing an example of a conventional automatic aperture adjusting device for a television camera. In the figure,
The light incident from the lens 1 is adjusted in the light amount by the diaphragm unit 2 and then formed into an image on the imaging unit 3 to be converted into a video signal. This video signal is supplied to the light quantity distribution measuring unit 4 to measure the light quantity distribution on the screen. In this embodiment, as shown in FIG. 3, the light quantity distribution is measured by dividing the screen area into four screen areas A to D. Therefore, the video signal is supplied to the four gate circuits 4A and 4A.
B, 4C, and 4D. Gate circuit 4A
4D extracts only signals of respective portions corresponding to the screen regions A to D of the video signal in accordance with the control signal output from the region identification unit 5, and then smoothes and outputs the signals so as to be suitable for lens aperture control. . Signals corresponding to the light amounts output from the gate circuits 4A to 4D of the light amount distribution measuring unit 4 are multiplied by weighting coefficients by conversion coefficient circuits 8A, 8B, 8C, and 8D of the coefficient unit 8, respectively, and further added by the adding unit 7. This is output as the aperture control signal Y.

Now, gate circuits 4A, 4B, 4C, 4D
Are XA, XB, XC, and XD, and the weighting coefficients of the conversion coefficient circuits 8A, 8B, 8C, and 8D are a, b, c, and d, respectively. ... (1) The aperture control signal Y is supplied to an aperture drive unit 9 to control the aperture unit 2 of the lens.

[0004]

In the conventional automatic iris adjustment device for a television camera described above, the characteristics of the conversion coefficient circuit
That is, since the weighting coefficients a, b, c, and d in the equation (1) are constants set in advance by design, they cannot be easily changed. Therefore, there is a disadvantage that a person who operates the television camera cannot easily correct the lens aperture and change the brightness of the imaging screen in various ways.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic iris adjustment device for a television camera which allows a person who operates the television camera to easily correct the lens iris.

[0006]

SUMMARY OF THE INVENTION An automatic iris adjustment device for a television camera according to the present invention generates an iris control signal by multiplying the amount of light in each area of a screen by a respective weighting coefficient and adding the result.
In an automatic iris adjustment device for a television camera which controls the iris of a lens by the iris control signal, a position detecting means for detecting an amount of change when the position of the iris of the lens is changed by a manual operation; and the difference detecting means for detecting a difference between the throttle control signal and the detection signal, the
The area of the maximum light amount in the area so that the difference becomes zero
And a coefficient control means for changing the weighting coefficient. Further, the coefficient control means compares a light amount of each area of the screen and detects a screen area having a maximum light amount, and a maximum value detection unit provided in correspondence with each area of the screen according to a coefficient control signal. A conversion coefficient circuit that changes and multiplies a weighting coefficient, and a changeover switch that selects the conversion coefficient circuit corresponding to the screen area of the maximum light amount and supplies the output of the difference detection unit as the coefficient control signal. May be.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. Compared with the conventional one shown in FIG. 3, an aperture position detector 10 for detecting the position of a lens aperture, an aperture control signal Y and an aperture control A differential amplifying unit 11 for amplifying a difference between output signals of the position detecting unit 10 and an output signal X of the light amount distribution measuring unit 4
A to XD, a maximum value detection unit 12 for detecting the screen area of the maximum light amount, a changeover switch unit 13 for selectively switching according to the output of the maximum value detection unit 12, and a weighting coefficient according to the control signal. Variable conversion coefficient circuits 6A, 6B, 6
C and 6D are newly provided.

If a person operating the television camera wants to slightly change the aperture of the lens when capturing an image of a certain subject, the aperture section 2 is moved to an appropriate position by manual operation. The diaphragm position detector 10 detects a change in the position of the lens diaphragm, and outputs a detection signal P corresponding to the change in the position to the differential amplifier 11. Normally, since the level of the aperture control signal Y and the level of the detection signal P are equal, the output of the differential amplifier 11 is zero. However, the diaphragm unit 2 is manually operated.
Is moved, the differential amplifier 11 outputs a signal Q proportional to the position change.

On the other hand, the maximum value detecting section 12 has the
In D, a region where the amount of light is the largest is detected, and a switching signal S is sent to the switching unit 13. The changeover switch unit 13 selects a conversion coefficient circuit corresponding to the region of the maximum light amount among the conversion number circuits 6A, 6B, 6C, and 6D according to the changeover signal S, and sends out the output signal Q of the differential amplifier unit 11. I do. The conversion coefficient circuit receiving the output signal Q changes the weighting coefficient according to the output signal Q.

For example, for example, a screen area A being imaged
It is assumed that the area B has the maximum light amount among the areas. Here, assuming that the aperture position of the lens is changed by a manual operation, the weighting coefficient b of the conversion circuit 6B is controlled so as to change, and changes until the output signal Q of the differential amplifier 11 becomes zero.

When the weighting coefficient b of the conversion circuit 6B changes to b ', the aperture control signal Y' is as follows: Y '= aXA + b'XB + cXC + dXD (2)

The conversion number circuits 6A, 6B, 6C, 6D
Has a function of storing and holding a conversion coefficient, and when the aperture position of the lens is changed by a manual operation, thereafter, it operates according to the equation (2).

[0014]

As described above, the automatic iris adjustment device for a television camera according to the present invention detects a change in the lens iris position caused by a manual operation and generates a iris control signal by changing a weighting coefficient in accordance with the change in the position. By doing so, the person who operates the television camera can easily correct the lens aperture and change the brightness of the imaging screen in various ways.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating an example of a conventional automatic aperture adjustment device for a television camera.

FIG. 3 is a diagram illustrating an example of a screen area.

[Description of Signs] 4 Light amount distribution measuring unit 6 Coefficient unit 6A to 6D Conversion coefficient circuit 7 Addition unit 10 Position detection unit 11 Differential amplification unit 12 Maximum value detection unit 13 Switching switch unit

Claims (2)

(57) [Claims] An automatic iris adjustment device for a television camera, which generates an iris control signal by multiplying a light amount in each area of a screen by a respective weighting coefficient and adds the iris control signal, and controls the iris of the lens by the iris control signal. position detecting means for detecting a change in the amount when changing the position of the aperture of the lens by the operation, the difference detecting means for detecting a difference between the detection signal and the aperture control signal from the position detecting means, the difference is
Automatic iris adjustment device of the television camera, characterized in that Ru and a coefficient control means for changing the weighting coefficient of the maximum light amount region of said region to be zero. 2. A coefficient control unit, comprising: a maximum value detection unit for comparing a light amount of each area of the screen to detect a screen area having a maximum light quantity; and a coefficient control signal provided for each area of the screen. And a changeover switch for selecting the conversion coefficient circuit corresponding to the screen area of the maximum light amount and supplying the output of the difference detection means as the coefficient control signal. 2. The automatic iris adjustment device for a television camera according to claim 1, wherein: