JPH0448032B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a camera device such as an electronic camera device, and particularly to white balance adjustment and exposure control thereof.

Conventional configuration and problems The conventional camera device is shown in Figures 1 and 2.
This will be explained using figures. First, FIG. 1 shows the principle configuration of white balance adjustment. In the figure, 1 is an image sensor, 2 is a separation circuit that separates the output of the image sensor 1 into R, Y, and B signals, 3 and 4 are video amplifiers having a voltage-controlled variable gain section, and 5 is an R-Y 6 is a differential amplifier for obtaining signals, 7 is an encoder.

White balance adjustment involves forming an image of a white or achromatic object through an imaging lens, converting this image into an electrical signal by an imaging device 1, and converting this signal into an R, Y, B signal by a separation circuit 2. and controlling the gains of the video amplifiers 3 and 4, the outputs of the differential amplifiers 5 and 6 (R-
This is to make the color difference signals of Y) and (B-Y) zero.

Next, FIG. 2 shows a circuit block diagram of a conventional camera device. In the figure, 8 is a photometric photodetector;
9, 10, and 11 are photodetectors that detect each red, green, and blue light component; 12 is an amplifier for photometric photodetector output; 13 is an exposure control circuit; and 14, 15, and 16 are photodetectors for each color component. 17 and 18 are differential amplifiers, 19 is a lens, 20 is an aperture, 21 is a shutter, 22 is a shutter control circuit, and 23 is an aperture control circuit.

In conventional white balance adjustment, light component signals of each color are obtained from a subject corresponding to white using detectors 9, 10, and 11 that detect red, green, and blue light components independent of the image sensor 1, and then an amplifier 14 ,15,16
After amplification, "red-green" and "blue-green" optical component signals are obtained by differential amplifiers 17 and 18. The obtained optical component signal is used as a control signal to change the gain of the variable gain video amplifiers 3 and 4, and the levels of the R and B video signals, which are the output signals of the separation circuit 2, are controlled and the differential amplifiers 5 and 6 The color difference signal (R-
White balance adjustment is automatically performed by adjusting Y) and (B-Y). Further, in the case of an electronic camera, since exposure control is necessary, a photometric photodetector 8 is provided for this purpose, and after the output signal is amplified by an amplifier 12, it is sent to an aperture control circuit 23 by an exposure control circuit 13. Shutter control circuit 22
The diaphragm 20 and the shutter 21 are controlled by controlling the diaphragm 20 and the shutter 21 to perform appropriate exposure control.

As described above, conventional electronic cameras require a photodetector for white balance control and a photodetector for exposure control, which poses a problem in reducing the size and cost of cameras.

Purpose of the Invention The present invention solves the above-mentioned drawbacks of the conventional technology, and enables automatic white balance adjustment even when instantaneous image capture is performed with an electronic camera, improving operability and mobility, and reducing size and cost. It is an object of the present invention to provide a camera device that can also improve the performance.

Configuration of the Invention In order to achieve the above object, a camera device of the present invention includes a color image sensor, at least two photodetectors independent from the color image sensor and having mutually different spectral sensitivity characteristics, and a camera device that uses these at least two light a subtracter that obtains a difference signal between the output signals of the detectors; an adder that obtains a sum signal of the output signals of the at least two photodetectors; and a white balance control of the output of the color image sensor using the output signal of the subtractor. and an exposure control means for controlling the exposure of the color image sensor based on the output signal of the adder.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a circuit block diagram of a camera device according to an embodiment of the present invention, in which 24 is a photodetector that includes a wide-angle lens for color balance adjustment and is highly sensitive to short wavelength light (corresponding to blue); Reference numeral 25 denotes a photodetector having high sensitivity to long wavelength light (corresponding to red color), and these photodetectors 24 and 25 are arranged so that they can capture a subject with a wide angle of view. 26 and 27 are each blue,
A logarithmic amplifier that amplifies the signals corresponding to each color of the photodetectors 24 and 25 that detect the red component regardless of the strength of the light, 28 a summing amplifier that detects the sum of signal levels of blue and red, and 29 a blue and red signal. 30 is an exposure control circuit, 31 is a voltage converter that converts the output of the differential amplifier 29 into necessary voltage characteristics, 32 is a lens, 33 is an aperture, 34 is a shutter, 35 is an image sensor, 36
is the output of the image sensor 35 as (Cy-Mg), Y, (Y-
G) separation circuits 37 and 38 are video amplifiers that amplify the output signal of the image pickup device 35 to a specified level. In this case, the video amplifier 3
7 or 38, for example, the video amplifier 37
has a voltage-controlled variable gain section and is controlled by the output signal of the voltage converter 31. 39 is an encoder for combining the video outputs of the video amplifiers 37 and 38 into a regular color signal, 40 is an aperture control circuit, and 41 is a shutter control circuit.

In a camera device configured in this way, when white balance adjustment is performed at a certain color temperature as necessary, the photodetectors 24 and 25 for blue (short wavelength light) and red (long wavelength light) are used to adjust the white balance at a certain color temperature. Detection outputs corresponding to each color component from a subject at a viewing angle (corresponding to a white subject) are obtained and amplified by corresponding logarithmic amplifiers 26 and 27, respectively. At this time, the output of the differential amplifier 29 is transmitted to the photodetectors 24 and 25.
Since the logarithmic amplifiers 26 and 27 are used as amplifiers for the output of , it is independent of the intensity of the incident light. Therefore, the output of the differential amplifier 29 at this time corresponds to a certain color temperature. Next, this differential amplifier 2
9 is input to a voltage converter 31 that can convert and synthesize the required color temperature-voltage characteristics,
The output signal of this voltage converter 31 controls the gain of a differential amplifier 37 having a variable gain section. For example, if the video amplifier 37 is a video amplifier with a variable gain section, when a white or achromatic object is imaged for each color temperature, the output level of the video amplifiers 37 and 38 is set to the same level. It is necessary to control the gain of amplifier 37.
The control voltage and color temperature characteristics of the video amplifier 37 are obtained in the voltage converter 31. Furthermore, since the output signal of the summing amplifier 28 is the sum of the levels of the blue and red optical signals, it corresponds to the intensity of the incident light, and by using this output signal,
The aperture control circuit 40 can be controlled by the exposure control circuit 30 without the need for a photometric photodetector for exposure control.
By operating the shutter control circuit 1 and the shutter control circuit 1, appropriate exposure control can be performed.

In this way, the image sensor 35 and the independent photodetector 2
4 and 25, it is possible to simultaneously and constantly obtain a signal corresponding to the color temperature that corrects the white balance deviation at each color temperature and a signal corresponding to the incident light necessary to perform exposure control. White balance can be adjusted automatically even while shooting, and aperture control,
Exposure control such as shutter control can also be performed.

Effects of the Invention As explained above, according to the present invention, color temperature information and incident light amount information during shooting can be simultaneously detected using a common photodetector without using a specific white subject. The white balance can be constantly and automatically adjusted at any time without changing the white balance, and exposure control can also be performed at the same time. Price reduction can be significantly expanded.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing the principle of white balance adjustment, FIG. 2 is a circuit block diagram of a conventional camera device, and FIG. 3 is a circuit block diagram of a camera device according to an embodiment of the present invention. 24, 25... Photodetector, 26, 27... Logarithmic amplifier, 28... Summing amplifier, 29... Differential amplifier, 30... Exposure control circuit, 31... Voltage converter, 35... Image sensor, 36...Separation circuit, 3
7, 38...video amplifier, 39...encoder,
40...Aperture control circuit, 41...Shutter control circuit.

Claims (1)

[Claims] 1. A color imaging device, at least two photodetectors having mutually different spectral sensitivity characteristics independent of the color imaging device, and obtaining a difference signal between the output signals of these at least two photodetectors. a subtracter; an adder for obtaining a sum signal of the output signals of the at least two photodetectors; white balance control means for controlling the white balance of the output of the color image sensor based on the subtracter output signal; and the adder. A camera device comprising: exposure control means for controlling exposure of the color image sensor based on an output signal. 2. The at least two photodetectors are composed of a first photodetector that is primarily sensitive to red light and a second photodetector that is primarily sensitive to blue light;
2. The camera device according to claim 1, wherein color temperature information is obtained from a difference signal of the output signals of the first and second photodetectors, and light amount information is obtained from a sum signal. 3. The camera device according to claim 1, wherein the white balance control means includes a voltage converter that converts the difference signals of the plurality of photodetectors into necessary color temperature-voltage characteristics.