JPS61114230A - Automatic focusing camera - Google Patents

Abstract

PURPOSE:To eliminate error factors between a right and a left image and utilize the space for optical system arrangement by providing the 1st incidence window and the 2nd incidence window in order at right angles to the incidence direction of luminous flux for range measurement, and reflecting pieces of luminous flux incident from those windows almost in the same direction ad guiding them to a photodetection part. CONSTITUTION:A photodetecting element chip 7 is arranged at right angles to the conventional direction for the two pieces L1 and L2 of luminous flux from a subject; one piece L1 of luminous flux is passed through a lens 10 and reflected by a mirror 11 at right angles, and the other piece L2 is reflected by a mirror 12 at right angles and then passed through a lens 13, so that the both are guided to respective photodetecting elements A and B. Thus, an optical system for range measurement is arranged and the there is some space between the two pieces L1 and L2 of luminous flux in the camera, so the finder optional system composed of lenses 8 and 9 is arranged in this space, which is utilized. Further, the optical system for range measurement uses only one lens and one mirror for one piece of luminous flux, so error factors of an image position are decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an autofocus camera that makes effective use of the space inside the camera and facilitates adjustment of the relative position of an optical image for distance measurement.

(b) Prior Art Conventionally, autofocus cameras have been developed and put into practical use. As methods for optically detecting the focus of a subject in an autofocus camera, there is a blurred image detection method that detects the sharpness of the image of the object to be measured, and a double image matching detection method that detects the overlap of the left and right two objects to be measured. Various methods are known, such as the upper and lower image coincidence detection method, and the ray distance method, which uses the reflected light of the light beam emitted towards the object to be measured to calculate the distance by triangulation from the base line length and angle of view.

On the other hand, the distance measurement methods for focusing include the so-called active AF method, which projects a beam of light such as an infrared beam toward the subject and receives the reflected beam light to measure the distance, and the There is a so-called passive AF method in which two different light beams are received by separate light receiving elements to form an image, and distance measurement is performed by monitoring the coincidence of the images.

By the way, in active AF type cameras, the finder optical system can be placed between the optical axis of the light emitting lens and the optical axis of the light receiving lens, through which the infrared beam light used for distance measurement passes. However, in passive AF cameras, the rangefinding optical system and finder optical system must be placed independently and separately for the reasons described below. It is difficult to make the camera more compact.

That is, in the passive AF method that measures distance based on triangulation, two arrayed light receiving elements receive different lights, but these two light receiving elements must be formed on one chip for the following reason.

(i) As the photodetector is made up of a large number of strip-shaped photoelectric elements arranged in an array as shown in Figure 3, configuring the left and right photodetectors A and B on separate chips would require significant wiring. It becomes complicated.

(ii) If the characteristics of the two light-receiving elements are not the same, there is a possibility that a distance measurement error will occur.

When performing distance measurement based on triangulation using such a set of light receiving elements, the distance measuring ability depends on the optical base length, the focal length of the imaging lens, and each element of the plurality of photoelectric elements that make up the light receiving element. The optical baseline length is generally 15
It is often assumed that the size is ~351 m. Therefore, 2
When two light-receiving elements are arranged on a square chip, a mirror or the like is used to convert the base line length, as shown in FIG. That is, different light fluxes Ll coming from the subject
-, L2 are once reflected at a right angle by mirror 1.2, passed through lenses 3 and 4, and further reflected by mirrors 5 and 6, and projected onto two light receiving elements A and B on chip 7, respectively. Therefore, from Fig. 4, it can be seen that both luminous fluxes Ll and L
The space between 2 and 2 becomes a dedicated space for the distance measuring optical system, and the finder optical system consisting of lenses 8 and 9 has to be placed outside of that space, resulting in an increase in camera size.

On the other hand, in the passive AF method that performs triangulation based on the phase difference of the brightness distribution of the subject, both the left and right light beams L1
．． , The image incident as L2 must be adjusted so that there is no phase difference between the left, right, top and bottom images on the light receiving element with respect to the reference distance, but as can be seen from Figure 4, the distance measuring optical system is Since one lens and two mirrors are used for the light beam, there are many factors that can disturb the relative positions of the left and right images, and one lens and two mirrors are used for position adjustment.
There is also the problem that adjustment is complicated because two mirrors intervene.

(c) Object and structure of the invention The present invention has been made in view of the above points, and it is possible to eliminate the cause of errors in the left and right images for distance measurement and to make effective use of space for optical system arrangement in a passive AF camera. In order to achieve this purpose, a first entrance window and a second entrance window are provided in order when viewed from the direction perpendicular to the direction of incidence of the ranging light beam, and The light flux incident through the entrance window and the second entrance window is bent in substantially the same direction by a reflecting mirror and guided to the light receiving section.

) Example The present invention will be explained below based on the drawings.

ig1 is a diagram showing an example of the optical system arrangement of an autofocus camera according to the present invention.

In this embodiment, there are two light beams Ll from the subject.

The light receiving element chip 7 is arranged in a direction perpendicular to L2, which is different from the conventional one, and one light beam L1 passes through a lens 10 and is then reversed at a right angle by a mirror 11, and the other light beam L2 is passed through a mirror 12.
After being reflected at right angles, the light passes through the lens 13 and passes through each light receiving element A on the chip 7.

It is designed to lead to B.

If the distance measuring optical system is arranged in this way, two light beams L1. Since a space is created between L2, effective use of the space can be achieved by arranging the finder optical system consisting of lenses 8 and 9 within this space. In addition, since the distance measuring optical system uses only one lens and one mirror for one beam of light, the error factors in the left, right, top and bottom positions of the image formed on the light receiving element are reduced. Become. Further, since the relative position of the image can be adjusted by only 1-12 in both the vertical and horizontal directions, there is also the effect that the adjustment becomes easy.

FIG. 2 shows another embodiment of the invention.

In this embodiment, the light-receiving element chip 7 is placed in the same manner as in the embodiment shown in FIG. After being reflected at right angles by mirror 16, lens 17
through the light receiving elements A and B on the chip 7, respectively. In this embodiment, the arrangement of the light receiving elements A and B on the chip 7 is reversed from that in the embodiment shown in FIG.

In this embodiment as well, since a space is created between the two light beams Ll and L2, a finder optical system consisting of lenses 8 and 9 can be placed in this space, and the space can be used effectively. In addition, since there is one lens and one mirror that make up the ranging optical system for each light beam,
This is the same as the embodiment shown in Fig. 1 in that the factors that cause errors in the position of the image are reduced compared to the conventional case, and the relative position can be adjusted easily because only one mirror needs to be adjusted. be.

(e) As described in detail of the invention, in the present invention, the first entrance window and the second entrance window are provided in order when viewed from the direction perpendicular to the direction of incidence of the ranging light beam, and the second entrance window is provided in order. The structure is such that the light beams entering from the first entrance window and the second entrance window are bent in almost the same direction by the reflecting mirror and guided to the light receiving section, so a space is created between the two light beam paths, and the finder optical By arranging the system, space can be used effectively and the camera can be made more compact. In addition, since the distance measuring optical system for one light beam is composed of one lens and a reflecting mirror, error factors in the image position are reduced, and adjustment of the relative position of the image formed by two light beams is done by one reflection. Adjustment is easy, just by adjusting the mirror.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the arrangement of the optical system of an autofocus camera according to the present invention, and FIG. 2 is a diagram showing another embodiment of the arrangement of the optical system of the autofocus camera according to the invention. FIG. 3 is an example of a chip in which a pair of light receiving elements are arranged, and FIG. 4 is a diagram showing an example of the arrangement of a conventional optical system. 7... Chip 8,9,10.13... Lens 11.12... Mirror L, I, 2... Luminous flux A, B... Light receiving element

Claims (3)

[Claims] (1) A first entrance window and a second entrance window are provided in order when viewed from a direction perpendicular to the direction of incidence of the distance-measuring light beam, and the first entrance window
1. An autofocus camera having a distance measuring device, characterized in that a light flux incident through an entrance window and a second entrance window is bent in substantially the same direction by a reflecting mirror and guided to a light receiving section. (2) The autofocus camera according to claim 1, wherein a finder optical system is disposed between the first entrance window and the second entrance window. (3) The light receiving section is composed of a one-chip light receiving element having a pair of photosensitive parts, and the light receiving element is connected to the first and second photosensitive parts.
The autofocus camera is placed approximately parallel to the light flux entering the entrance window of the camera.