JPH03195190A - Video camera - Google Patents

Abstract

PURPOSE:To always obtain white balance based on a correct color temperature by arranging a color temperature sensor between a lens in the front raw of a lens system and an image pickup element and defining the output of this sensor as a reference signal for obtaining the white balance of a video signal. CONSTITUTION:In the internal part of a camera main body 1, a color temperature sensor S is arranged at a position between a lens 3a in the front raw of a lens system 3 and an image pickup element 2 and the output of this sensor S is used as the reference signal for obtaining the white balance of picture information. The color temperature to be detected by the sensor S becomes the color temperature of light to be really guided to the image pickup element 2. Thus, regardless of the difference of the color temperature between the place of an object and the place of the video camera, the white balance can be always obtained with the correct color temperature as a reference. Further, since the sensor S is installed at the position in front of a zoom lens, regardless of zoom-up, the white balance can be always obtained with the correct color temperature as the reference.

Description

[Detailed description of the invention] <Industrial application field> TECHNICAL FIELD The present invention relates to video cameras.

<Conventional technology> Recently, video cameras are becoming fully automatic.

The three major auto functions of video cameras include auto focus, auto iris, and auto white balance. Among these automatic functions, it is difficult to adjust the white balance manually, especially in the current situation where color viewfinders are not widespread, so automatic white balance is one of the most important functions.

Currently, two methods are used for auto white balance. One is the so-called external sensor method, in which the camera body is equipped with a sensor that detects the color temperature of its surroundings, and the output signal of this sensor is used to perform white balance. The color temperature is determined from the output of the image sensor and the white balance is calculated based on this color temperature.
This is the L (Thr-ogh The Lens) method.

<Problems to be Solved by the Invention> By the way, according to the above-mentioned external sensor method, if the color temperature of the light differs between the location of the subject and the location of the video camera, and in the TTL method, it may be If the image of the subject is focused on the camera's full field of view, either method will not be able to correctly detect the color temperature, resulting in a white balance malfunction and the colors of the reproduced image may differ from the actual colors. There was a problem that the color was different from the color of the subject.

<Means for Solving the Problems> The present invention has been made to solve the above problems.
The configuration will be explained with reference to FIG. 1 corresponding to an embodiment. The present invention focuses an image of a subject on the light receiving surface of an image sensor 2 using a lens system 3, and outputs an output signal of the image sensor 2. In a video camera that outputs image information of a subject to a device such as a television or a videotape recorder, the lens 3 is located inside the camera body 1 and is located in the front row of the lens system 3.
A color temperature sensor S is arranged at a position between a and the image sensor 2,
It is characterized by a configuration in which this sensor S output is used as a reference signal for white balancing image information.

<Operation> The color temperature detected by the sensor S is the color temperature of the light actually guided to the image sensor 2. As a result, regardless of the difference in color temperature between the location of the subject and the location of the video camera, white balance can always be achieved using the correct color temperature as a reference.

In addition, by installing the sensor S in front of the zoom lens, even if the image of a monochromatic object is expanded to the full angle of view due to zoom-up, the light immediately after passing through the lens system in front of the zoom lens can be It is possible to detect the color temperature of light that includes the following colors, and in this case, white balance can always be determined based on the correct color temperature, regardless of zoom-up or the like.

<Example> FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention.

A solid-state image sensor 2 is disposed within the camera body 1,
An image of the subject is formed on the light-receiving surface of the solid-state image sensor 2 by a lens system 3 consisting of a convex lens 3a and a concave lens 3b. The output signal of the solid-state image sensor 2 is subjected to noise removal, amplification, etc. by a signal processing circuit 4, and is output as a video signal to, for example, a video tape recorder (not shown). Note that the timing/SSG circuit 5 is a circuit for synchronizing the operations of both the solid-state image sensor 2 and the signal processing circuit 4. The above is publicly known.

Now, a color temperature sensor S for detecting the color temperature of light is disposed near the rear of the concave lens 3b, and the output signal of this sensor S is input to the signal processing circuit 4. The signal processing circuit 4 removes noise from the output signal from the solid-state image sensor 2.
In addition to processing such as amplification, it is configured to white balance the video signal that is output using the output signal from the color temperature sensor S as a reference signal.

With this configuration, the white balance of the output video signal is automatically adjusted, but by installing the color temperature sensor S near the rear of the lens system 3, the white balance of the output video signal is automatically adjusted. Can detect the color temperature of light. Then, by adjusting the white balance of the output video signal based on this detected value, an image with a color almost the same as the actual color of the subject will be displayed on the screen of a monitor device or the like.

FIG. 2 is an explanatory diagram of the configuration of another embodiment of the present invention, showing an example in which the present invention is applied to a video camera equipped with a zoom function.

An image of a subject is formed on the light-receiving surface of the solid-state image sensor 2 disposed within the camera body 21 by a front lens system 23, a zoom lens system 26, and a rear lens system 27. The solid-state image sensor 2 includes a signal processing circuit 4 similar to the previous embodiment.
and a timing/SSG circuit 5 are connected.

In this example, a color temperature sensor S is disposed near the rear of the front lens system 23. This color temperature sensor S
The output signal is input to the signal processing circuit 4, and the video signal is subjected to the same processing as in the previous embodiment.

In this way, by installing the color temperature sensor S near the rear of the front lens system 23, that is, in front of the zoom lens system 26, even when the image of a monochromatic subject widens to the full angle of view due to zoom-up, The reference color temperature used for white balance is the color temperature of the light immediately after passing through the front lens system 23, that is, the color temperature of light containing a plurality of colors. Therefore, in this example as well, an image with a color substantially the same as the actual color of the subject will be displayed on the screen of the monitor device or the like.

However, the color temperature sensor S should be installed at a position that does not interfere with the movement of the zoom lens system 26, and where the solid-state image sensor 2
The position is such that it does not affect the light that forms the image on the light-receiving surface.

Note that in the above two embodiments, the number of color temperature sensors S installed is one, but the number is not limited to this, and an arbitrary plurality may be used.

<Effects of the Invention> As explained above, according to the present invention, a color temperature sensor is disposed between the front lens of the lens system and the image sensor, and the output of this sensor is used to white balance the video signal. Because it is used as a reference signal, the color temperature is always correct regardless of the color temperature of the light between the subject location and the camera location, or even if the image of a monochromatic subject is expanded to the full angle of view due to zoom-up. It is possible to adjust the white balance based on the image. As a result, the range of use for zoom-up etc. is expanded compared to the conventional technology.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of another embodiment of the invention. 1...Camera body 2...Solid-state image sensor 3...Lens system 4...Signal processing circuit S...Color temperature sensor

Claims (1)

[Claims] In a video camera that uses a lens system to form an image of a subject onto the light-receiving surface of an image sensor, and outputs the output signal of the image sensor as image information of the subject to equipment such as a television or video tape recorder, , and a color temperature sensor is disposed between the front-row lens of the lens system and the image sensor, and the sensor output is used as a reference signal for white balancing the image information. A video camera featuring: