JP2746400B2 - Automatic aperture device for video cameras - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic iris device in a video camera device.

2. Description of the Related Art A conventional automatic diaphragm device is configured as shown in FIG. The imaging apparatus 1 includes an optical lens system and a diaphragm mechanism, and an imaging element disposed at a position where light passing through the optical lens system and the diaphragm mechanism forms an image.
The video signal is photoelectrically converted and read by the image sensor. The signal photoelectrically converted and read by the image pickup device is also input to the detection unit 3 via the amplification unit 2, and based on the output signal obtained by detecting the signal by the detection unit 3, the aperture control unit 4 determines an appropriate aperture value, and the aperture control unit 4 adjusts the aperture mechanism of the above-described image pickup apparatus to the appropriate aperture value. Only the control loop including the imaging device 1, the detection unit 3, and the aperture control unit 4 cannot perform an appropriate automatic aperture adjustment at the time of shooting in a backlight state. The user manually supplies the switching signal 6 to the switching unit 5 when shooting in the backlight state, and substitutes the output signal of the detection unit 3 with a fixed value set in the setting unit 7 in advance. The input is supplied to adjust the aperture mechanism of the imaging device.

In such a conventional configuration, at the time of imaging in the backlight state, the user manually supplies the switching signal 6 to the switching unit 5 to adjust the aperture mechanism, so that the switching unit 5 is erroneously operated. Is switched to the setting device 7 side, so that it is not possible to perform the backlight compensation when photographing in the normal light state and perform the appropriate aperture adjustment, or to forget the manual operation of the backlight compensation when photographing in the backlight state and perform the appropriate aperture adjustment. There is a problem that can not be done.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic aperture device that can automatically adjust the aperture by performing backlight correction without manually instructing backlight correction.

Means for Solving the Problems The automatic aperture device of the present invention is an automatic aperture device that controls an aperture mechanism according to an output signal of the image sensor to automatically adjust the amount of light incident on the image sensor. A first detection unit that detects a first region that is a central portion in the captured image; a second detection unit that detects a second region that is a region around the first region; The first and second amplifying sections for amplifying the output signal of the second detection means at an arbitrary amplification degree, respectively, and comparing the levels of the output signal of the first amplifying section and the output signal of the second amplifying section. A plurality of gate sections for dividing a video period of an output signal of the image sensor into a plurality of regions independent of the first and second regions, and extracting a signal of each of the divided regions; A plurality of gain control units for varying the gain of the output signal of each gate unit; A plurality of control units for varying the gain of each of the gain control units according to a level determination output of a comparator; an addition unit for adding the output signals of the gain control units; and detecting an output signal of the addition unit A detection unit, and an aperture control unit that determines an aperture value in accordance with an output signal of the detection unit, wherein an aperture mechanism that adjusts the amount of light incident on the image sensor is controlled by a signal from the aperture control unit. And

According to this configuration, the comparator compares the signals based on the first and second regions in the video period of the output signal of the image sensor with the comparator to determine whether the light state is forward light or back light. .
Each control unit determines the gain of each gain control unit according to the determined light state. The signals of the respective regions extracted from the output signals of the image sensor through the respective gate units are amplified by the respective gain control units at an amplification degree according to the light beam state at that time, and then synthesized by the addition unit. The output of the adder obtains a signal corrected in accordance with the state of the light beam. An aperture control unit that controls the aperture mechanism is controlled based on a signal obtained by detecting the signal of the adding unit via a detection unit, and the aperture control unit determines an appropriate aperture value based on a signal that is corrected according to a light beam state. decide.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. Note that components having the same functions as those in FIG. 5 showing a conventional example are denoted by the same reference numerals and described.

FIG. 1 shows an automatic drawing device according to the present invention. The output signal of the imaging device 1 is applied to the inputs of the first and second detectors 8 and 9 and the first, second and third gate units 10, 11 and 12. FIG. 2 shows an imaging screen of the imaging device 1. The first detection means 8 includes a gate 13 for extracting a signal of a central first region T1 of the output signal of the imaging device 1, and a gate 13 for extracting the signal. And a first detector 14 for detecting the output signal. The second detection means 9 includes a gate 15 for extracting a signal of a second area T2 around the first area T1 from an output signal of the imaging device 1, and a gate 15 for extracting the signal.
And a second detection unit 16 for detecting the output signal of The output signal of the first detector 14 is amplified by the first amplifier 17 to an amplification factor m times, and the output signal of the second detector 16 is
Is amplified to an arbitrary amplification factor n times. here,
The respective amplification factors m and n are usually about 2 to 5 times,
Optimization is achieved through experiments. The output signal (Im) of the first amplifier 17 and the output signal (IIn) of the second amplifier 18
Are compared by the comparator 19. When (Im) ≧ (II · n), it is determined that the light is in the forward light state and when (I · m) <(II · n), the light is in the backlight state.

The first gate unit 10 extracts the signal of the region t1 shown in FIG. 3 from the output signal of the imaging device 1, and the second gate unit 11 extracts the signal of the region t2 outside the region t1 from the output signal of the imaging device 1. , And the third gate unit 13 extracts the signal of the region t3 outside the region t2 from the output signal of the imaging device 1. The output signals of the first to third gate units 10, 11, and 12 are input to the addition unit 23 via the first, second, and third gain control units 20, 21, and 22, and are added to each other. The two signals are combined into one. The amplification factors of the first, second, and third gain control units 20, 21, and 22 are equal to the first, second, and third control units 24, 25,
26 is controlled as follows.

In a state where the comparator 19 determines that the light is in the normal light state,
As shown in FIG. 4 (a), the third control units 24, 25 and 26 control the first gain control unit 20 to gain G10 and the second gain control unit 21 to gain G1.
1. The third gain control 22 is set to the gain G12. Here, G10>G11> G12, and the gain G10 is slightly larger than G11 and G12.

In a state in which the comparator 19 determines that the backlight is in the backlight state, the first and the
2, the third control units 24, 25, and 26 control the first gain control unit 20 to gain G20 and the second gain control unit 21 to control gain as shown in FIG.
G21, the third gain control unit 22 is set to the gain G22. Here, G20>G21> G22, and the gain G20 is much larger than G21 and G22.

Therefore, in a state where the comparator 19 determines that the light is in the normal light state, the regions t1 and t1 amplified by the gains G10, G11 and G12, respectively.
The signal obtained by synthesizing the signals of 2 and t3 in the adder 23 is used to adjust the aperture mechanism of the imaging apparatus to an appropriate aperture value via the detector 3 and the aperture controller 4.

In a state where the comparator 19 has determined that the backlight state, the gain G2
A signal obtained by combining the signals of the regions t1, t2, and t3 amplified by 0, G21, and G22, respectively, in the adder 23. Adjust to.

As described above, in the state where the comparator 19 determines the normal light state and the state where the comparator 19 determines the backlight state, the gain of the first gain control unit 20 with respect to the area t1 is G20 in the backlight state and the area t2,
The gains of the second and third gain controllers 21 and 22 with respect to t3 are much larger than the gains G21 and G22, and the diaphragm mechanism of the imaging apparatus 1 uses a signal focused on the central region t1 so that an appropriate diaphragm mechanism Automatically adjusted to the value.

In the above embodiment, the second region T2 does not include the first region T1 as shown in FIG. 2, but the second region T2 is the first region.
The same applies to the case where at least a part of the region T1 is included.

In the above embodiment, the case where the signal is extracted by dividing the signal into three regions t1 to t3 by the first to third gate units 10 to 12 has been described as an example. The same applies to the case where the image is divided into one or more regions and extracted.

Advantageous Effects of Invention As described above, according to the present invention, an automatic aperture device that controls an aperture mechanism according to an output signal of an image sensor and automatically adjusts the amount of light incident on the image sensor is provided. A first detecting means for detecting a first area which is a central portion of the first section, a second detecting means for detecting a second area which is an area around the first area, and the first and second sections. First and second amplifying sections for amplifying the output signals of the detecting means at an arbitrary amplification degree, respectively, and the output signal of the first amplifying section and the second amplifying section.
And a comparator for comparing the level of the output signal of the amplifying unit, and dividing the video period of the output signal of the image sensor into a plurality of regions independent of the first and second regions. A plurality of gate sections for extracting the signals of the above, a plurality of gain control sections for varying the gain of the output signal of each of the gate sections, and varying the gain of each of the gain control sections according to the level determination output of the comparator. A plurality of control units, an addition unit for adding the output signals of the respective gain control units, a detection unit for detecting the output signal of the addition unit, and an aperture for determining an aperture value according to the output signal of the detection unit A control unit is provided, and a diaphragm mechanism for adjusting the amount of light incident on the image sensor is controlled by a signal of the diaphragm control unit. Automatically switch to a different value. Therefore, those capable of automatically adjusting the aperture in backlit without performing quantitative correction by manual operation as in the prior art.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the automatic aperture device of the present invention, FIG. 2 is an explanatory diagram of first and second regions extracted by first and second detection means of the device, and FIG. FIG. 4 is an explanatory view of each region extracted by a gate unit of the apparatus, FIG. 4 is an explanatory view of a gain change of a gain control unit in a forward light state and a backlight state of the apparatus, and FIG. FIG. DESCRIPTION OF SYMBOLS 1 ... Imaging device, 3 ... Detection part, 4 ... Aperture control part, 8th, 9th ...
1, second detection means, 10, 11, 12 ... first, second, third gate sections, 17, 18 ... first and second amplification sections, 19 ... comparators, 20, 21, 22
... first, second, third gain control units, 23 ... addition units, 24,25,26 ...
1st, 2nd, 3rd control part, T1, T2 ... 1st, 2nd area, t1, t
2, t3 ... area.

Claims (1)

(57) [Claims] An automatic aperture device for controlling an aperture mechanism in accordance with an output signal of an image sensor to automatically adjust the amount of light incident on the image sensor, wherein the first device is a central portion in a captured image of the image sensor. First detecting means for detecting an area;
Second detection means for detecting a second area around the area, and first and second amplification means for amplifying output signals of the first and second detection means at an arbitrary amplification degree, respectively. Unit, a comparator for comparing the level of the output signal of the first amplifier unit and the level of the output signal of the second amplifier unit, and the image period of the output signal of the image sensor is defined as the first and second regions. A plurality of gate sections that are divided into a plurality of independent areas and extract signals of the divided areas; a plurality of gain control sections that vary gains of output signals of the respective gate sections; A plurality of control units that vary the gain of each of the gain control units according to a level determination output, an addition unit that adds the output signals of the gain control units, and a detection unit that detects the output signal of the addition unit. ,
An automatic aperture device that includes an aperture control unit that determines an aperture value in accordance with an output signal of the detection unit, and controls an aperture mechanism that adjusts the amount of light incident on the image sensor with a signal from the aperture control unit.