JPS58209704A - Focusing point detector - Google Patents

Abstract

PURPOSE:To improve distance measurement precision by processing output signals of reference photodetectors and connected photodetectors within only a range where output signals of plural reference photodetectors in a photodetectors are close to successively connected photodetectors, and disregarding other output signals. CONSTITUTION:A section 1 is a CCD and consists of a photosensor part, integration function part, shift register part, etc., and an analog signal for distance measurement is led out of the shift register part successively. When the face 7 if a person is put in focus and long-distance mountains 8 and intermediate- distance houses 9 are all image-formed on a photodetection part, only the output signal of the image formation of the face 7 is employed in the stage of calculation of a computer 4 and other output signals of the image formation of the mountains 8 and houses 9 are omitted; and the calculated distance measurement signal is converted into a motor operating signal through the operation of a focus position switch 5 and a motor 6 for focal-length distance control is driven until a optical photographic system and an optical distance measurement system enter in-focus states.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a focused point detection device, and more specifically, an image formed on a light receiving section of an object existing around an object in focus is output as a noise signal from the light receiving section during focus detection processing. By eliminating this noise signal and incorporating as much of the signal output from the imaging of the object as possible for focus detection processing, we can create a focused point that allows high-precision distance measurement even when surrounding objects are present. This invention relates to a detection device.

Conventionally, for example, a CCD is also called a line sensor.

In the case of self-scanning light receiving elements such as photodiode arrays, when the object to be focused on is relatively small and there are objects at different distances around it, it is difficult to image the surrounding objects on the light receiving section. becomes a noise signal and leads to focusing errors.

In order to solve this problem, it is possible to configure the light receiving section with a small number of light receiving elements, but this poses a problem of reduced resolution, and although it would be possible to minimize the number of light receiving elements, it is difficult at the current stage due to both technical and cost considerations. It is.

The purpose of this invention is to support imaging of the focused target when there are objects at different distances around the focused target depending on the state of the subject, and all of these objects are imaged on the light receiving section. It is possible to improve the distance measurement accuracy by using only the signal of the light receiving element that corresponds to the distance and not using other equal signals, and by using a wide range of materials as long as the same level of output signal can be obtained. , an image of the subject is formed by an optical system on a light-receiving section consisting of a large number of light-receiving elements, and an analog signal output from the light-receiving element is extracted and sent to a focus detection device including an A/D converter and a microcomputer to detect focus. In the device that performs this, only the range in which the output signal of each of the connected light-receiving elements that are lined up in series with several reference light-receiving elements among the light-receiving element group is comparable to the output signal of the reference light-receiving element is included in the range. It is an object of the present invention to provide a focused point detection device characterized in that a microcomputer is set to process output signals of a reference light receiving element and a continuous light receiving element and omit other output signals. Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a CCD comprising a light sensor section, an integral function section, a shift register section, etc., from which analog signals for distance measurement can be sequentially taken out.

Note that this CCD 1 is incorporated in a distance measuring optical system provided separately from the imaging optical system. An image that is magnified than the pattern of the subject that is imaged by the focus lens of the optical system, for example, if a zoom lens is incorporated in the imaging optical system, an image that is about the same size as the image at the telephoto position is incident. It is preferable to set the distance measuring optical system so that

Reference numeral 2 denotes an analog signal processing device, which includes a function of extracting the difference between the masked reference sensor's dark current 1 signal and the sensor signal as a reflex level, and an automatic gain side circuit (AGC).

3 is an A/D conversion and 1 converts an analog signal into a digital signal for microcomputer processing.

Reference numeral 4 is a microcomputer that uses the output signals of a plurality of reference light receiving elements near the optical axis as a reference, and determines that each output signal of the connected light receiving elements arranged on the left and right sides of the reference light receiving element is equal to the output signal of the reference light receiving element. As long as , the output signals of the connected light-receiving elements are sequentially picked up and compared with the output signals of the reference light-receiving element. It is programmed to omit the output signals of the connected light-receiving elements, and to perform arithmetic processing within the range of the output signals of the connected light-receiving elements, which are equivalent to the reference light-receiving element.

Reference numeral 5 denotes a focus position switch for calculating a distance measurement signal into an operation signal for the focal length control motor 6.

Since the in-focus point detection device according to this embodiment is configured as described above, for example, when a person's face 7 is captured as an in-focus object as shown in FIG. 8 and a house 9 at a middle distance are all focused on the light receiving section,
At the calculation stage of the microcomputer 4, only the output signal from the image of the face 7 is adopted, the output signals from the images of the other mountains 8 and the house 9 are omitted, and the calculated distance measurement signal is sent to the focus position switch. 5, the focal length control motor 6 is driven to a position where the imaging optical system and the distance measuring optical system are brought into focus.

As described above, according to the in-focus point detection device according to the present invention, only the distance measurement signal of the in-focus object can be used as data,
Moreover, since the maximum number of data of the same level of output is processed, it is possible to detect a focused point with high distance measurement accuracy, and it has great effects such as being able to be manufactured at a low cost.

The present invention has been variously explained above with reference to preferred embodiments, but the present invention is not limited to these embodiments, and many modifications can be made without departing from the spirit of the invention. Of course.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a block diagram thereof, and FIG. 2 is an explanatory diagram showing the state of image formation of a subject on a light receiving section. 1...ccn, 2...analog signal processing device. 3... A/D converter, 4... Microcomputer, 5... Focus position switch. 6...Focal length control motor, 7...Face. 8...Mountain, 9...House.

Claims (1)

[Claims] 10. An image of the subject is formed by an optical system on a light-receiving section consisting of a large number of light-receiving elements, and an analog signal output from the light-receiving element is extracted and sent through a focus detection processing device including an A/D converter and a microcomputer to detect focus. In the device that performs this, only the range in which the output signal of each of the connected light-receiving elements that are lined up in series with several reference light-receiving elements among the light-receiving element group is comparable to the output signal of the reference light-receiving element is included in the range. A focused point detection device characterized in that a microcomputer is set to process output signals of a reference light receiving element and a continuous light receiving element and omit other output signals.