JPS6126390A - White balance adjuster for color video camera - Google Patents

Abstract

PURPOSE:To improve the answering ability of an object subjected to the white balance adjusting to color temperature by changing a mixing ratio of color temperature signals from plural color temperature detectors in accordance with a zoom magnification of an optical lens system and outputting said signals. CONSTITUTION:When an optical lens system 1 is in the state of a telephoto lens, a signal corresponding to a zoom magnification of a zoom magnification detector 7 is given to a mixing ratio changing mixer 8. Since a picture angle is small when the zoom magnification is large, color temperature signals are mixed so that a mixing ratio of a color temperature signal from a color temperature detector 6a having a light-receiving part with a small natural lighting angle can be larger than that of a color temperature signal from a color temperature detector 6b having a light-receiving part with a large natural lighting angle. Levels of a red signal in a white balance adjusting red signal variable gain amplifier 4a and a blue signal in a white balance adjusting red signal variable gain amplifier 4b depend further on the color temperature signal from the color temperature detector 6a having the light-receiving part with a small natural lighting angle, and is adjusted.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a white balance adjustment device for a color video camera, and in particular, to a white balance adjustment device for a color video camera. The present invention relates to a white balance adjustment device that improves the responsiveness of white balance adjustment to the color temperature of a subject by changing the mixing ratio of color temperature signals from a plurality of color temperature detectors and outputting them according to the color temperature of the object.

[Prior Art] FIG. 1 is a block diagram showing the configuration of a conventional white balance adjustment device. In FIG. 1, the white balance adjustment device is
An optical lens system 1 that conveys optical information about a subject; an image sensor 2 that separates the optical information that the optical lens system 1 conveys into the three primary colors of red, blue, and green and convert them into corresponding electrical signals; A red signal preamplifier 3a, a green signal preamplifier 3b, and a blue signal preamplifier 3G that amplify electrically converted red, green, and blue video signals, respectively, and a red signal variable gain amplifier 4a for white balance that adjusts the levels of the red signal and blue signal, respectively. and a white balance blue signal variable amplifier 4b, and a color temperature detector 6 that detects the color density of the subject and controls the amplification degree of each gain amplifier 4a, 4b based on its output signal.

The signals from the red signal variable gain amplifier 4a for white balance, the green signal preamplifier 3b, and the blue signal variable amplifier 4b for white balance are subjected to various signal processing by subsequent processes and color encoder 5 to become video image signals.

The operation of the white balance adjustment device will be described below. The color temperature detector 6 generates a color temperature signal corresponding to the color temperature of the light source light by detecting the ratio of the red component and the blue component contained in the light source light illuminating the subject. Optical information possessed by the subject is acquired by optical lens system 1. A red signal and a green signal pass through the image sensor 2.

Optical-to-electrical conversion is performed into a green video signal. The red signal, green signal, and blue signal converted into electrical signals are each sent to a preamplifier 3a,
3b, amplified by sc. Of these, the red signal and the blue signal are respectively input to the red signal variable gain amplifier 4a for white balance and the blue signal variable gain amplifier 4b for white balance, which adjust the white balance of the video signal, and their signal levels are adjusted. . This signal level adjustment is controlled to correspond to the ratio of the red signal and the blue signal included in the light source light that illuminates the subject, which is detected by the color temperature detector 6.

Thereafter, it is processed into a video image signal by the subsequent process and the color encoder 5. The conventional device is configured as described above and automatically adjusts the white balance.

However, in the white balance adjustment device configured as described above,
The lighting angle of the light receiving section included in the color temperature detector 6 (lighting solid angle seen from the light receiving section) is fixed.

On the other hand, the angle of view of the optical lens system 1 of the video camera changes as the zoom magnification changes. Therefore, the lighting angle of the light receiving section and the optical lens system 1. Due to the difference in the angle of view from the image sensor 2, a difference occurs between the color temperature detected by the color density detector 6 and the color temperature of the optical information provided from the optical lens system 1 to the image sensor 2.

Since the white balance adjustment is performed using the color temperature signal from the color temperature detector 6, the white balance adjustment may be performed incorrectly.

[Summary of the Invention] An object of the present invention is to eliminate the drawbacks of the above-mentioned conventional white balance adjustment device and to provide a white balance adjustment device that does not malfunction at any zoom magnification. .

In summary, this invention provides a plurality of color temperature detectors each having a light receiving section with different lighting angles, and mixes color temperature signals from the plurality of color temperature detectors at a ratio according to the zoom magnification. This is a white balance adjustment device that uses this mixed color temperature signal to perform white balance adjustment.

The objects and other objects and features of the present invention will become more apparent from the detailed description given below with reference to the drawings.

[Embodiment of the Invention] FIG. 2 is a diagram showing a white balance adjustment device which is an embodiment of the invention. In FIG. 2, unlike the conventional white balance adjustment device shown in FIG. 1, there is a zoom magnification detector 7 that detects the zoom magnification of the optical lens system 1, and a color saturation detector 6a that has light receiving sections with different lighting angles. , 5b, and a variable ratio mixer 8 which inputs the color temperature signals from the color temperature detectors 6a and 6b and changes its mixing ratio in response to the signal from the zoom magnification detector 7. The operation of the white balance adjusting device according to one embodiment of the present invention will be described below.

First, when the optical lens system 1 is in a telephoto lens state and has a large zoom magnification, the zoom magnification detector 7 detects the zoom magnification and supplies a signal corresponding to the zoom magnification to the variable ratio mixer 8. The variable ratio mixer 8 receives the signal from the zoom magnification detector 7 and sets its mixing ratio as follows. When the zoom magnification is large, the angle of view of the optical lens system 1 is small, so the mixing ratio of the color temperature signal from the color temperature detector 6a, which has a light receiving part with a small lighting angle, is such that the mixing ratio of the color temperature signal has a light receiving part with a large lighting angle. The color temperature signals are mixed so as to be greater than the mixing ratio of the color temperature signals from the color temperature detector 6b. Therefore, the optical v'; state of the telephoto lens of x system 1 (
Corresponding to this, the red signal and blue signal levels in the red signal variable gain amplifier 4a for white balance adjustment and the blue signal variable gain amplifier 4b for white balance adjustment have a light receiving section with a small lighting angle. Color temperature detector 6
The level is adjusted more dependent on the color temperature signal from a.

That is, when the angle of view of the wide-angle lens system 1 is small, white balance adjustment is performed depending more on the signal from the color temperature detector 6a having a light receiving section with a small lighting angle.

Next, consider a case where the optical lens system 1 is in a wide-angle lens state (when the angle of view is too large). At this point, in response to the signal from the zoom magnification detector 7, the variable mixing ratio mixer 8 sets its mixing ratio as follows. The mixing ratio of color temperature signals from the color temperature detector 6b having a light receiving part with a large lighting angle is set to be larger than the mixing ratio of color temperature signals from the color temperature detector 6a having a light receiving part with a small lighting angle. mixed. Since the levels of the red and blue signals are adjusted using the color temperature signal from the variable ratio mixer 8, the white balance adjustment in this case is performed using the color temperature signal from the color temperature detector 6b, which has a light receiving section with a large angle in the lighting direction. It will be done in a more dependent manner.

With the above configuration, the optical lens system 1. The white balance can be adjusted using a color temperature signal corresponding to the angle of view of the image element 2.

In the above embodiment, two color temperature detectors with different lighting angles are used, but even if additional color temperature detectors with different lighting angles are used, the same effect as in the above embodiment can be obtained. can get.

Furthermore, as a method of transmitting a signal indicating the zoom magnification to the variable mixing ratio mixer 8 to change the mixing ratio, in addition to a method using an electric signal, there is also a method using, for example, a semi-fixed resistor in the part where the mixing ratio is changed. A method may also be used in which the change in magnification is directly transmitted from the optical lens system using, for example, a gear.

[Effects of the Invention] As described above, according to the present invention, a plurality of color temperature detectors each having a light-receiving section having a different lighting angle are provided, and a plurality of color temperature detectors are provided to detect a plurality of colors at a ratio corresponding to the zoom magnification of the optical lens system. It is configured to mix the color temperature signals from the temperature detector.

Therefore, it is possible to reduce malfunctions in white balance adjustment due to the difference between the light receiving angle of the light receiving section of the color temperature detector and the angle of view of the optical lens system/imaging device, and a clear color image can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional white balance adjustment device. FIG. 2 is a block diagram showing a white balance adjustment device which is an embodiment of the present invention. In the figure, 1 is an optical lens system, 6a is a color temperature detector with a small lighting angle, 6b is a color temperature detector with a large lighting angle, 7 is a zoom magnification detector, and 8 is a variable mixing ratio mixer. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Procedural amendment (spontaneous) Date 2, Month, Showa 1939, Name of the invention: White balance adjustment device for color video camera 3, Representative Hitoshi Katayama of the person making the amendment, Department 4, Agent 5, Patent claim of the specification to be amended. Scope Column 9: Detailed Description of the Invention and Drawing 6, Contents of Amendment (1) The Scope of Claims column of the specification is corrected as shown in the attached sheet. (2) [Variable gain amplifier 4a] on page 3, line 4 of the specification
Correct J to [variable gain amplifier 4a J. (3) Replace “variable amplifier 4b” on page 3, line 5 of the specification with “
Correct to variable gain amplifier 4bJ. (4) "Each gain amplifier" on page 3, line 6 of the specification is corrected to "each variable gain amplifier." (5) "Variable gain amplifier" on page 3, line 8 of the specification is replaced with "
Corrected to "variable gain amplifier". (6) "Green signal variable j" on page 3, line 9 of the specification is corrected to "green signal gain variable." (7) "Variable gain" on page 4, line 3 of the specification is corrected to "variable gain." (8) "Variable gain" on page 4, line 4 of the specification is corrected to "variable gain." (9) "Red signal variable gain amplifier" in lines 4 and 5 on page 7 of the specification is corrected to "red signal variable gain amplifier." (1o) "Green signal variable gain amplifier" in lines 5 and 6 on page 7 of the specification is corrected to "green signal variable gain amplifier." (11) Figures 1 and 2 of the drawings will be corrected as shown in the attached sheet. 2. Claims: an optical lens system with a variable zoom magnification; a zoom magnification detection means for detecting the zoom magnification; A white balance adjusting device for a color video camera, comprising: a color temperature mixing means for mixing color density signals given from a plurality of color temperature means, and adjusting white balance according to the signal from the color temperature mixing means. (2) The mixing ratio is such that as the zoom magnification increases, the ratio of the color temperature signal from the color temperature detection means having the smaller solid angle of light intake increases.
A white balance adjustment device for a color video camera as described in .

Claims (2)

[Claims] (1) A white balance adjustment device for a color video camera that photographs a subject having a color temperature, which includes a plurality of color temperature detection means that detect the color temperature and have different solid angles of light reception, and a variable zoom magnification. an optical lens system; a zoom magnification detection means for detecting the zoom magnification; and a color temperature given by the plurality of color temperature means by changing the mixing ratio according to a zoom magnification signal from the zoom magnification detection means. A white balance adjustment device for a color video camera, comprising a color temperature mixing means for mixing signals, and adjusting white balance according to a signal from the color temperature mixing means. (2) The color video according to claim 1, wherein the mixture ratio is such that as the zoom magnification increases, the proportion of the color temperature signal from the color temperature detection means having the smaller solid angle of light intake increases. White balance adjustment device for cameras.