JPH0646810B2 - Still image capture device - Google Patents

Description

TECHNICAL FIELD The present invention relates to white balance adjustment in a still image capturing device.

Configuration of Conventional Example and Problems Thereof A conventional example will be described below with reference to the drawings. First of all
The figure shows the principle of white balance adjustment. In the figure, 101 is an image sensor, 102 is a separation circuit for separating the output of the image sensor into R, Y, and B signals, 103 and 104 are video amplifiers having a voltage-controlled variable gain portion, 105
Is a differential amplifier for obtaining an "RY" signal, 106 is a differential amplifier for obtaining a "BY" signal, and 107 is an encoder.

In white balance adjustment, a white or achromatic subject is formed through an image pickup lens, this image is converted into an electric signal by an image pickup device 101, and this signal is further converted into R, Y, B signals by a separation circuit 102, and an image is obtained. Amplifier 1
By controlling the gains of 03 and 104, the color difference signals of "RY" and "BY" output from the differential amplifiers 105 and 106 are made zero.

Next, FIG. 2 shows a block diagram of a conventional still image capturing device. In the figure, 201 is a photometric photodetector,
Reference numerals 202, 203, and 204 denote photodetectors that detect the red, green, and blue light components, and 205, an amplifier for the photodetector photodetector output,
206 is an exposure control circuit, 207, 208 and 209 are amplifiers of photodetector outputs of respective color components, 210 and 211 are differential amplifiers, 212 is a lens, 213 is an aperture, 214 is a shutter, 215 is a shutter control circuit, and 216 is Aperture control circuit, 217 is a flash unit, 218 is a flash control circuit, 101-
Reference numeral 107 denotes a white balance principle configuration diagram 101 to 101 in FIG.
Corresponding to 107.

It will be described with reference to FIG. In the conventional white balance adjustment, detectors 202, 203, and 204, which detect red, green, and blue light components independent of the image sensor 101, obtain light component signals of respective colors from a subject corresponding to white, and amplifiers 207 and 20.
After being amplified by 8, 209, differential amplifiers 210, 211 obtain "red-green" and "blue-green" light component signals. By using the obtained light component signal as a control signal, the gains of the variable gain video amplifiers 103 and 104 are changed to control the levels of the video signals of "R" and "B" which are the output signals of the separation circuit 102 to obtain a differential signal. White balance adjustment is performed by adjusting the color difference signals "RY" and "BY" output from the amplifiers 105 and 106.

Further, in the case of a still image photographing device, exposure control is necessary. Therefore, a photometric photodetector 201 is provided for this purpose, and after amplifying this output signal with an amplifier 205, an exposure control circuit 206 controls an aperture control circuit 216 and shutter control. Circuit 215
To control the aperture 213 and the shutter 214, and the exposure control circuit 206 operates the flash control circuit 218 to control the flash circuit 217 to perform appropriate exposure control according to the photographing state.

However, this conventional method has the following problems.

First, FIG. 3 shows a timing chart of the still image capturing apparatus. In the figure, (a) is a control signal for color temperature correction obtained by a photodetector, (b) is the shutter open / closed state or the timing of accumulating a still image in the image sensor, and (c) is a readout of the still image signal. This is the timing for performing signal processing for color temperature correction.

The problem will be described with reference to FIG. In the case of a still image capturing device, as shown in FIGS. 3B and 3C, there is a difference between the timing of storing a still image in the image sensor and the timing of signal processing. Therefore, as shown in FIG. 3A, there is a problem that the control signal for accumulating a still image in the image sensor and the control signal for signal processing after reading change. In particular, when the flash duration is momentary, such as during flash photography, the control signals described above change significantly, so the white balance adjustment is a certain issue, and operability and maneuverability associated with changes in shooting conditions become a major issue. There is.

An object of the present invention is to eliminate such a conventional problem, and to ensure the white balance adjustment during normal shooting and flash shooting regardless of shooting conditions in a still image shooting device,
It is an object of the present invention to provide a still image capturing device capable of improving operability and mobility associated with a change in a capturing state.

Configuration of the Invention A still image capturing device according to the present invention comprises a color image pickup device, means for accumulating a still image of a subject in the color image pickup device,
Means for obtaining color temperature information of illumination light at the moment when a still image of a subject is stored in the color image pickup device, and time for performing white balance signal processing by reading the still image signal stored in the color image pickup device from the color temperature information. And a means for performing white balance control of the output still image signal of the color image pickup device based on the held color temperature information, and the means for obtaining the color temperature information is mutually independent of the color image pickup device. It is composed of at least two photodetectors having different spectral sensitivity characteristics and a computing unit that computes the output signal of the photodetectors, and improves the certainty, operability, and maneuverability of white balance control. It is a thing.

Description of Embodiments An embodiment of the present invention will be described below with reference to the drawings. Fourth
The figure is a block diagram showing an embodiment of a still image photographing apparatus according to the present invention. In the figure, 401 is a photometric photodetector, and 402, 403, and 404 are lights for detecting red, green, and red light components. A detector, 405 is a photodetector signal amplifier for photometry, 406, 407, and 408 are photodetector signal amplifiers of respective color components, and 409 and 410 are differential amplifiers, 411.
Is a control signal generation circuit that generates a control signal for white balance adjustment corresponding to the color temperature of the flash light, 412 is a switching SW circuit for switching between normal shooting and flash shooting, 413 is a HOLD circuit that outputs a switching SW circuit, 414 is an exposure control circuit, 415
Is a flash unit, 416 is a flash control circuit, 417 is a shutter control circuit, 418 is an aperture control circuit, 419 is a lens, 4
20 is a diaphragm, 421 is a shutter, 422 is an image sensor,
Reference numeral 423 is a separation circuit for separating the image sensor output into R, Y, B signals, 424, 425 is a video amplifier having a voltage-controlled variable gain portion, 426 is a differential amplifier for obtaining an RY signal, and 427 is A differential amplifier for obtaining a BY signal,
Reference numeral 428 is an encoder.

FIG. 5 is a timing chart of the still image capturing apparatus according to the present invention. In the figure, (a) is the output from the differential amplifier 409 or 410 obtained by the photodetector, (b) is the output from the control signal generation circuit 411, and (c) is the exposure control circuit 4.
14 is a flash light use designation signal, (d) is a shutter opening / closing signal from the shutter control circuit 417, and (e) is timing of color temperature correction signal processing after reading a still image signal performed by the variable gain amplifier 424 or 425. , (F) are control signals used at the timing of (e).

The operation of the still image capturing apparatus configured as described above will be described below. When performing white balance adjustment at a certain color temperature as needed Each detection corresponding to each color component from a wide-angle object (corresponding to a white object) by red, green, and blue photodetectors 402, 403, and 404 Outputs are obtained and amplified by amplifiers 406, 407, and 408, respectively, to obtain output signals irrelevant to the intensity of incident light, and differential amplifiers 409 and 410 obtain control signals corresponding to color temperature in FIG. 5 (a). .

For flash photography, the control signal generation circuit 411 obtains a control signal shown in FIG. 5 (b) which is preset according to the color temperature of the flash.

The two control signals shown in FIGS. 5 (a) and 5 (b) are switching SW circuits 4
12 is input. The switching SW circuit 412 selects one of the two control signals [FIG. 5 (c)] according to the photographing state. The selected control signal is held by the hold circuit 413 in synchronization with the shutter 421 [Fig. 5 (d)] until the timing of necessary signal processing [Fig. 5 (e)]. The output of the hold circuit 413 [FIG. 5 (f)] controls the video amplifiers 424 and 425 having variable gain sections to output the color difference signal “R−, which is the output signal of the differential amplifiers 426 and 427 for each color temperature. White balance adjustment is performed by setting Y and “BY” to zero.

In addition, in order to perform appropriate exposure control, the photometric photodetector 401
After amplifying this output signal by the amplifier 405, the exposure control circuit 414 determines whether or not the flash light is necessary according to the shooting condition and generates a signal [FIG. 5 (c)] for instructing the flash light and aperture control. The circuit 418 is operated to control the diaphragm 420, and the shutter control circuit 417 is operated to operate the shutter opening / closing signal [FIG. 5 (d)] to release the shutter 421.
And the HOLD circuit 413 are controlled.

Therefore, the color temperature information of the ambient light is detected by the photodetector, and the white balance adjustment control signal is obtained from the color temperature information at the moment when the still image is accumulated. By providing a circuit for generating a balance adjustment control signal, a white balance adjustment control signal can be obtained regardless of the shooting state, and the HO
Since the still image in which the control signal is stored can be read out and the white balance adjustment can be actually performed by including the LD circuit, the automatic white balance adjustment can be performed more accurately.

Although the HOLD circuit 413 is opened and closed in synchronization with the shutter 421 in the embodiment, it may be synchronized with another appropriate signal.

Further, the switching SW 411 is automatically switched according to the output signal from the exposure control circuit, but it is the same even if it is manually switched.

EFFECTS OF THE INVENTION As described above, according to the present description, there is a means for accumulating a still image in the image pickup device, and the color temperature information of the illumination light at the moment when the still image is stored in the image pickup device is stored as the still image Accurately holds until the time of reading and signal processing, and in the case of flash photography, the necessary color temperature information regardless of the shooting situation,
Since the still image can be read and held until the time of signal processing, and the white balance adjustment can be performed using the held color temperature information, the reliability and mobility of the still image capturing device can be greatly expanded. Excellent effects such as being able to

[Brief description of drawings]

1 is a block diagram showing the principle of white balance adjustment, FIG. 2 is a block diagram showing an example of a conventional camera device, and FIG. 3 is a timing chart of control signals and signal processing in a conventional still image capturing device. FIG. 4 is a block diagram showing an embodiment of the still image capturing apparatus according to the present invention, and FIG. 5 is a timing chart for explaining the operation thereof. 401 ... Photometric detector for photometry, 402, 403, 404 ...
... Color component detection photodetector, 409,410 ... Differential amplifier, 411 ... Control signal generation circuit, 412 ... Switching SW circuit, 413 ... Hold circuit, 417 ... Shutter control circuit, 422 ... Imaging element 423 ... Separation circuit, 424, 425 ... Variable gain type video amplifier, 42
6,427 ... Differential amplifier, 428 ... Encoder.

Claims (2)

[Claims] 1. A color imaging device, means for accumulating a still image of a subject in the color imaging device, means for obtaining color temperature information of illumination light at the moment of accumulating a still image of the subject in the color imaging device, and the color. A means for holding the temperature information until the time when the still image signal stored in the color image pickup device is read and white balance signal processing is performed, and a white balance control of the still image signal output from the color image pickup device based on the held color temperature information. And a means for obtaining the color temperature information, the means for obtaining the color temperature information being independent of the color imaging device, having at least two photodetectors having mutually different spectral sensitivity characteristics, and a computing unit for computing an output signal of the photodetector. A still image capturing device characterized by being configured from. 2. A color imaging device, means for accumulating a still image of a subject in the color imaging device, means for detecting color temperature information of ambient light at the moment of accumulating a still image of the subject in the color imaging device, and Means for generating the color temperature information of the set flash, means for selecting the output of the two means according to the photographing situation, and still image signal stored in the color image sensor for the selected color temperature information. And a means for holding until the time of performing the white balance signal processing, and a means for performing white balance control of the still image signal output from the color image pickup device by the selected and held color temperature information. At least two photodetectors whose detection means are independent of the color image sensor and have different spectral sensitivity characteristics, and an output signal of the photodetectors. Still image shooting device, characterized in that and a calculator for.