JPS6243284Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an automatic focal length control device.

As shown in Fig. 1, an automatic focal length control device using a double image matching detection method that uses the principle of conventional triangulation detects the position of the photographing lens when the images incident on the two light-receiving elements 1 and 2 match. Although the focus is now fixed, the light from multiple objects that appear close to each other despite the large difference in distance is reflected by the light receiving elements 1 and 2.
When the light is incident on the light receiving elements 1 and 2, a plurality of images are formed in each region 3a to 3n and 4a to 4n of the light receiving elements 1 and 2, since the power supply voltage Vcc is supplied to the entire light receiving elements 1 and 2. Then, each region 3a of the light receiving elements 1 and 2 -
3n, 4a to 4n to differential amplifiers 5a to 5.
It was determined that the focus was fixed when the output difference between the light receiving elements 1 and 2 was closest to zero, that is, when the output of the adder 6 became the minimum.

Therefore, it has been impossible to automatically focus on a desired subject among a plurality of subjects with different distances.

For example, when photographing a row of trees that gradually become farther away from the right side of the photographic screen, conventional cameras could only focus on the row of trees in the center of the screen.

The purpose of the present invention is to solve the problems of the conventional automatic focal length control device, and selectively use a part of the light receiving element to select an object to focus on from among multiple objects that appear close together. An object of the present invention is to provide an automatic focal length control device that is characterized by being able to perform the following functions.

The feature of the automatic focal length control device of the present invention, which employs a double image matching detection method using the principle of triangulation, is that it selects the target image from among multiple subject images focused on one light receiving element, so the light receiving surface It is equipped with means for dividing the image into several parts and operating the light-receiving surface of only the part containing the target subject, and temporarily stopping the function of the other parts.

Hereinafter, the present invention will be explained in detail with reference to Examples.

In FIG. 2, parts having the same functions as those in FIG. 1 are given the same symbols.

FIG. 2 is a block diagram showing a schematic configuration of an embodiment of the present invention, with blocks 11a to 11n and 12a to
12n is one section obtained by dividing the light-receiving surfaces of the light-receiving elements 1 and 2 into n equal parts, each having a plane corresponding to the photographing screen. 13a to 13n are power lines; 14
A to 14n are gate circuits for supplying or stopping power to desired sections of the light receiving elements 1 and 2. 15a to 15n and 16a to 16n are output signal lines, and 17a to 17n are light receiving elements 1,
This is a selection signal line for selecting the desired section of 2.

Next, the operation of this embodiment will be explained.

By applying a division selection signal from the outside to a desired line among the selection signal lines 17a to 17n, the gate circuit corresponding to the division selection signal among the gate circuits 14a to 14n operates, and the light receiving elements 1, 2, each section 11a to 11n, 12a to 12
The power supply voltage Vcc is supplied to the corresponding section of n, and only the section becomes operational.

Here, as means for generating the selection signal, externally
For example, if a switch for generating segmentation selection signals corresponding to the upper right area, upper left area, center area, lower right area, and lower left area of the light-receiving surface is provided, the subject that you want to focus on will be imaged by the switch. By selecting a region, a selection signal is supplied only to the selection signal line corresponding to the region.

As a result, desired areas of the light receiving surfaces of the light receiving elements 1 and 2 are partially brought into operation, and automatic focal length control for each desired area can be performed using output signals corresponding to the desired areas.

Therefore, when a plurality of objects with different distances are imaged on the light receiving surface, the light receiving elements 1 and 2 included in the area of the light receiving surface where the object to be focused is imaged. By supplying the power supply voltage Vcc to only the sections as described above, focusing can be performed using a signal based only on the subject to be focused.

As described above, according to the present invention, when photographing a plurality of subjects with large differences in distance and distance, automatic focal length control can be performed for the desired subject.

Furthermore, if the present invention is used for camera autofocus, you can select the focusing area to focus on the subject anywhere in the picture, without having to place the subject in focus in the center of the composition (photographing screen). Can focus automatically.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional automatic focal length control device, and FIG. 2 is a block diagram of an embodiment of the present invention. 1, 2... Light receiving element, 5a to 5n... Differential amplifier, 6... Adder, 11a to 11n... Dividing section of light receiving element 1, 12a to 12n... Division section of light receiving element 2, 13a to 13n ...Power line, 14
a to 14n...gate circuit, 15a to 15n, 1
6a-16n...Output signal line, 17a-17
n...Selection signal line.

Claims (1)

[Scope of utility model registration request] An automatic focal length control device using a double image matching detection method using the principle of triangulation, characterized in that each of the double image matching detection light receiving elements is divided into a plurality of parts, and a means is added for selectively operating the parts. Automatic focal length control device.