JPS63109668A - Automatic focusing mechanism - Google Patents

Abstract

PURPOSE:To effectively utilize two sequences of solid-state image pickup elements different in light receiving sensitivity and constituting an image sensor, by conversionally using the elements of one sequence which is not used for automatic focusing for white balance control. CONSTITUTION:Of the two sequences of solid-state image pickup elements 5A and 5B constituting an image sensor 4 prepared as a sensor for automatic focusing, the elements 5B of one sequence B which is left unused while the other sequence is assigned for automatic focusing in conventional image sensors are provided with a diffusing filter 12 on their front side and connected with an interface circuit 13. The interface circuit 13 supplies color temperature information necessary for white balance control to a white balance controlling circuit 14. Upon receiving the color temperature information through the interface circuit 13, the white balance controlling circuit 14 variably adjusts the gains of gain adjusting circuits 15 and 16. Therefore, the solid-state image pickup elements 5B of the sequence B which has been left unused can be utilized effectively for white balance control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image sensor that can be used both for automatic focusing and for white balance support control.

[Prior Art] The automatic focusing mechanism of a video camera includes an active method that measures the time it takes for a distance measurement medium such as infrared rays emitted toward a subject to be reflected by the subject and returns to the subject, thereby determining the distance to the subject. Without using any distance measurement media such as infrared rays or ultrasonic waves,
There are two passive methods that check the in-focus state based on the image information of the subject that enters the camera lens. An automatic focusing mechanism 1 based on the TCL phase system shown in FIG. 2 is one that belongs to the passive system and is also used in 35 mm eye reflex cameras. Automatic focus mechanism 1 shown in the same figure
, a part of the light that passes through the lens 2 directed toward the subject is collected into a plurality of condensing lenses 3 called fly-eye lenses.
An image is formed on a plurality of solid-state image sensors 5 arranged in pairs on the image sensor 4. And the interface circuit 6
The control circuit 7, which is supplied with the output of the image sensor 4 via the control circuit 7, controls the focusing of the lens 2 by driving the focus morph 8 so that the sensor output is minimized.

Image sensor 4 used in this type of automatic focusing mechanism
As shown in FIG. 3, the solid-state image sensor 5 has different sensitivity.
A unit with two series A and 5B, A and H, is produced, and one method is to select either series A or B depending on the aperture ratio of lens 2 used, that is, the F value. It will be done. That is, the solid-state image sensor 5A belonging to one series A is assigned for use with bright lenses of Fl, 4 to 2.8, and the solid-state image sensor 5B belonging to the other series B is assigned for use with dark lenses of approximately F4. Then, the direction of the available light rays for a pair of solid-state image sensors 5A or 5B placed behind one condenser lens 3,
In other words, the invention is such that the open F-number of the applicable lens 2 is not limited.

[Problems to be Solved by the Invention] The above-mentioned conventional automatic focusing mechanism 1 is configured such that, once the F value of the lens 2 to be used is determined, one series of solid-state image sensors 5A corresponding to this F value is determined.
Or 5B is connected to the interface circuit 6, but the remaining solid-state image sensor 5B or 5A of the other series is left unused. For this reason, the solid-state image sensor 5B or 5A of the other series that has been prepared remains as an idle part without being used at all, and unnecessary parts are removed even though the purpose is to widen the range of usable lenses 2. Installing it as is is not desirable from the viewpoint of reducing manufacturing costs.

[Means for Solving the Problems] The present invention solves the above-mentioned problems. An image sensor receives an image of a subject through a lens, and a focus shift obtained from the received light output of the image sensor is corrected. The image sensor is comprised of two series of solid-state image sensors with different light receiving sensitivities so that the image sensor can be selected according to the F value of the lens, and the image sensor is not compatible with the F value of the lens used. Therefore, the solid-state image sensor of the series that is not used for automatic focusing is equipped with a diffusion filter,
The device is characterized in that it is connected to a white balance control circuit for color temperature detection.

[Operation] The present invention converts and utilizes the one that is not used for autofocus for white balance control among two series of solid-state image sensors with different light receiving sensitivities prepared as sensors for autofocus. The two series of solid-state imaging devices that make up the image sensor are effectively utilized.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing an embodiment of an automatic focusing mechanism of the present invention.

In FIG. 1, the autofocus mechanism II automatically uses an image prepared as an autofocus sensor to automatically select one of the two series of solid-state image sensors 5A and 5B that compose the sensor 4 that is compatible with the lens 2 used. At the time when it is assigned for focus, the other series, which would otherwise have been left unused, is used as a sensor for white balance control.

In this embodiment, since a bright lens 2 with an F value of 1.2 to 2.8 is used, a diffusion filter I2 is arranged on the front side of the solid-state image sensor 5B belonging to series B, and the solid-state image sensor 5B is connected to the interface circuit I3 for white balance control. A milky-white resin plate is used for the diffusion filter 12, and the light rays that enter the solid-state image sensor 5B through this diffusion filter 12 contain color temperature information of the subject under a light source such as sunlight or an incandescent lamp. The interface circuit 13 supplies the white balance control circuit 14 with color temperature information necessary for white balance control.

The white balance control circuit 14 that has obtained color temperature information via the interface circuit 13 acts on gain adjustment circuits 15 and 16 provided in the middle of the color signal lines for red and blue obtained from the image information of the subject, and adjusts each color temperature. Gain adjustment circuit 15.
16 gains are variably adjusted. Therefore, a white object can be imaged as white regardless of the color temperature of the light source, whether outdoors or indoors.

In this way, the autofocus mechanism 11 can effectively utilize the series B solid-state image sensor 5B, which has been left unused because it is not used for autofocus, for white balance control. In addition, since white balance can be controlled based on information within the imaging lens system, there is no need to create a complex configuration such as installing a sensor for white balance control separately from the imaging lens system, allowing for higher mounting density and imaging. This makes it possible to simultaneously make the camera more compact and reduce the manufacturing cost.

In the above embodiment, since the lens 2 used is bright, two series of solid-state image sensors 5A, which constitute the image sensor 4, are used.
Of 5B, series B was used for color temperature detection, but when using a dark lens with an F value of about 4, series B is used for autofocus, so series A is used for white balance control. Good.

[Effects of the Invention] As explained above, the present invention provides white balance control for the solid-state imaging device that is not used for autofocus among two series of solid-state image sensors with different light receiving sensitivities prepared as sensors for autofocus. By converting the two series of solid-state image sensors that make up the image sensor into a configuration that makes effective use of both, one series of solid-state image sensors, which had been left unused until now, can be used as a white material. Since it can be effectively used for balance control and white balance control can be performed based on information within the imaging lens system, a complex configuration such as providing a sensor for white balance control separately from the imaging lens system is required. This provides excellent effects such as achieving higher packaging density and making the imaging camera more compact at the same time, and lowering the manufacturing cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of an automatic focusing mechanism of the present invention, and FIGS. 2 and 3 are a schematic configuration diagram and a front view of an image sensor portion, respectively, showing an example of a conventional automatic focusing mechanism. . 210. Lens, 4. ,,image sensor. 11. , automatic focus mechanism, 12. , , Diffusion filter, 14. ,,white balance control circuit.

Claims (1)

[Claims] An automatic focusing mechanism in which an image sensor receives an image of a subject passing through a lens, and performs focusing control based on a focus shift obtained from the received light output of the image sensor, wherein the image sensor controls focus according to the F value of the lens. It consists of two series of solid-state image sensors with different light-receiving sensitivities, so that you can select from
The solid-state image sensor of the series that cannot be used for automatic focusing because it does not match the F value of the lens used is characterized in that it is equipped with a diffusion filter in front and connected to a white balance control circuit for color temperature detection. Autofocus mechanism.