JPS5915207A - Focusing detecting device - Google Patents

Abstract

PURPOSE:To simplify the constitution, by providing a light shielding part having an opening on the photodetecting face side of a photodetector train, and making two adjacent photodetectors have directivity so that each light from two areas whose boundary is a face containing an optical axis of an image forming optical system is made incident mainly to the photodetector. CONSTITUTION:A light shielding member 12 forms a stripe mask to each pair of photodetectors, and by these stripe masks, an opening 17 which makes a luminous flux transmitting the upper and lower side parts of an exist pupil face whose boundary is an optical axis, incident to two photodetectors is formed. As a result, two photodetectors for constituting each pair of photodetectors, for instance, photodetectors 14A-1, 14B-1 have directivity in each different direction, and the luminous flux which transmits the upper side is made incident to a photodetector group 14A, and the luminous flux which transmits the lower side is made incident to a photodetector group 14B. Accordingly, the illumination distribution of an image formed on the photodetector groups 14A, 14B coincides at the time of focusing, and is shifted in the opposite direction to each other at the time of non-focusing, therefore, by detecting a horizontal shift direction of its image, each focal state of pre-focusing and post-focusing can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a focus detection device for detecting a focus state of a camera, a microscope, a high-density optical recording/reproducing device, etc.

A lateral shift detection method is conventionally known as a method for detecting the focal state of an object image formed by an imaging optical system.

FIG. 1 is a diagram showing the configuration of a single-lens reflex camera in which a focus detection device f implementing the above lateral shift detection method is applied. The image of the object] passes through the photographic optical system 2 and the quick return mirror 3, and is then transferred to the focusing plate 4 and the pentaprism 5.
and the like, and is projected onto the film 6 by flipping up the quick return mirror 3. In Fig. 1, the central part of the quick return mirror 3 is a half mirror 7, and the light beam that passes through this half mirror 7 is reflected by a reflection mirror 8 installed on the back side of the quick return mirror 3, and this light beam is photographed. The photographing optical system 2 is connected to the auxiliary optical system 9 via a minute auxiliary optical system 9 such as a lenticular lens arranged near the predetermined focal plane of the optical system 2, that is, on a plane that is 1゛ conjugate to the optical system 2.
The light is incident on a light-receiving element array arranged at a position that is optically almost conjugate with the exit pupil plane. As shown in FIG. 2, the light-receiving element row 10 includes a light-receiving element group] (IA, ioB, these light-receiving element groups) 0'A, IUB, each light-receiving element 11JA-1.
~I OA -n and l (l B -i~+0B-
n corresponds to 1111t1, respectively, as the light receiving element pair 10A-1, IUB-1; .; l0A-n.

JOB-n is completely formed, and the arrangement is shifted so that all of these light receiving elements are located on a straight line. In addition, the auxiliary optical system 9
is a photodetector pair] 0A-1, ], 0B-1; ・; ]
0A-n, ] 0B-n, and the two light-receiving elements constituting each light-receiving element pair are perpendicular to the arrangement direction of the light-receiving elements approximately on the exit pupil plane of the photographing optical system 2. if, the portions located on each side of the plane containing the optical axis of the photographing optical system 2 (which is perpendicular to the plane of paper containing the optical axis in Fig. 1), that is, the radiation bordering the optical axis in Fig. 1; - Arranged to receive the image above the exit pupil plane and on the -F side.

In such a configuration, the photographing optical system 2 and the auxiliary optical system 9
When a small common part of the image of the subject 1 is projected onto the light-receiving element group 10 through On the contrary, only the light beam that has passed through the upper part will be incident, and the illuminance distribution of the images projected onto the photodetector group 1 (IA and IUB will be the same when in focus, and will be shifted when out of focus). The focus detection device shown in FIG. 1 shifts laterally in opposite directions depending on the direction of
The directions of the light-receiving element groups 11JA and 1tlB are appropriately processed to detect the lateral shift direction of the image, and based on this, the front bin, rear bin, and in-focus state are detected.

However, in the conventional focus detection device shown in FIG.
It is difficult to manufacture minute auxiliary optical systems 9 such as lenticular lenses, which makes the entire device expensive, expensive, and large. The disadvantage is that it is difficult to make adjustments.

An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a focus detection device that detects the focus state by using the lateral shift of the image using a simple, inexpensive, and compact structure Fj'j, fc. This is what I am trying to do.

The focus detection device of the present invention includes a light-receiving element array disposed at or near a predetermined focal plane of an imaging optical system, and a light-receiving element array disposed in an optical path between the light-receiving element array and the imaging optical system. a surface (f) including the optical axis of the imaging optical system on adjacent light receiving elements in the row;
, a light-receiving element pair that receives light from a first region of the imaging optical system of the light-receiving element row, and a light-receiving element group that receives light from a second region of the light-receiving element array. The present invention is characterized in that it is configured to detect the lateral shift of the object image formed by the imaging optical system to determine the focal state of the object image formed by the imaging optical system.

The present invention will now be described in detail with reference to the drawings.

Fig. 1 is a diagram showing the optical arrangement +t'fc of the focus detection device of the present invention applied to a single-lens reflex camera/mirror, and the same reference numerals as those shown in Fig. 1 represent the same members, and their explanations are as follows. is omitted. In this example, a light-receiving element array ]] is arranged on a plane that is y-conjugate with the film 6 with respect to the photographing optical system 2, and a light-shielding member ]2 is arranged on the light-receiving surface side of the light-receiving element array. The light beam is made to enter the light-receiving element array J1 through the light receiving section J2.

FIG. 4A is a perspective view showing the structure of the light receiving element array J1 and the light shielding part 2. The light-receiving element array 11 consists of a large number of light-receiving elements formed on the same substrate 3 at equal intervals on one surface.

In this example, the odd-numbered light receiving element 1 with respect to the arrangement direction is
4A-1 to 14A-n and even numbered light receiving elements 14B
-1 to 14B-n respectively light receiving element groups] 4A and 1
4B, and one adjacent element of both groups forms a pair of light receiving elements 14A-1, 14B-1;-; 14A-
Construct n, 14 B-11. 6 light section 4a'
121d, on a transparent substrate 15 such as a glass or a polymer film, each pair of light-receiving elements is coated with 1-. n stripe masks] 6-1 to 6-n are formed by vapor deposition, printing, etc., and each light-receiving element pair is configured as shown in FIGS. 44B and C. The photographing optical system 2 is mounted perpendicularly to the arrangement direction of the light receiving elements.
The first and second regions bounded by the plane containing the optical axis of , that is, the upper part of the exit pupil plane and the 1" 1111 portion defined as the boundary in FIG. An opening J7 is formed to mainly allow the light to enter.

With this configuration, 6 receivers) 2 elements constituting the e element pair
A light receiving element, for example, an element JヰA-1゜1.
4B-1 is not shown in Figure 5! like! The light-receiving elements 14A-1 to 14A-n of the light-receiving element group i4A have directivity in different directions, and in FIG. The light flux enters the light receiving element 14B-]~14.1 of the light receiving element group 14B.
3-11 The light flux that has passed through the lower side is mainly incident on the VC. Therefore, the light receiving element groups 14A, 14B
The illuminance distributions of the images formed in each image are the same when in focus, and when out of focus, they shift in opposite directions depending on the direction of the shift. Therefore, it is possible to detect all lateral shift directions of one image. It is possible to detect each focus state of in-focus, front focus, and rear focus.

FIG. 6 is a block diagram showing the configuration of an example of a signal processing circuit that obtains focus information representing -C focus, front focus, and rear focus based on the output of the light receiving element array 11.

In this example, the outputs of a large number of light receiving elements Qj2, light receiving element array]l are sequentially read out in the arrangement direction, and are sent to the A/D conversion circuit J.
At step 8, analog-to-digital conversion is sequentially carried out and input into an arithmetic circuit j9, where, for example, the outputs of the light receiving element 14A- and 1+B-k (where ≦≦n) are used as At and Bk, respectively. This calculated value S is the light receiving element array]
Corresponding to the position of the photographing optical system 2 with respect to J, as shown in FIG. 7, it is positive in the front bin state, zero in the in-focus state, and negative in the rear bin state. z
At O, front focus, focus, and rear focus are all displayed. Note that the operations of the light-receiving element array] ], A/D conversion circuit] 8, arithmetic circuit] 9, and display circuit 20 are flu! It is controlled by a control circuit 21.

FIG. 8 shows the structure of another example of the light shielding part used in the focus detection device of the present invention. This light-shielding member 22 is formed as a first light-shielding member on the surface of the transparent substrate 23 on the side of the imaging optical system, and n stripe masks 24-] to 24 are formed corresponding to each light-receiving element pair, similarly to the embodiment described above. -n to form a relatively large aperture 25, and the light receiving element array 1 ] (lill
On the surface of 20+1 s;.
These striped masks 26-1 to 26-1 are formed by forming live masks 26-J to 26-(2n+]) by vapor deposition, printing, etc.
26-(2n+J), as shown in FIG. 9, an opening 27 is formed which faces each light-receiving element and whose width is relatively smaller than its length in the arrangement direction. If this light shielding member 22 is used, the light shielding member 22 and the light receiving element array]1
As is clear from FIG. 9, even if the optical adjustment with respect to the light receiving elements is slightly shifted in the arrangement direction of the light receiving elements, the light receiving area of each light receiving element facing each aperture 27 does not change.
4A.

Since the balance of photoelectric power incident on 14B does not change, optical adjustment of the light shielding part phase 22 and the light receiving element array JJ7 is easy.
Moreover, highly accurate focus detection can be performed at all times. Incidentally, in the parallax light section 12 used in the above-described embodiment, if it is arranged with a slight shift to the right side in the row direction of the light receiving element row 1J, for example, in FIGS. 41B and C, the light receiving elements 14A- 1~] The light receiving area of 4A-n uniformly expands, and conversely, the light receiving area of light receiving elements 14B-1 to 14B-n uniformly narrows, and the light receiving element groups 14A and 14
In some cases, the unbalance of the output with respect to the light receiving element B becomes severe and focus detection with surface accuracy becomes impossible, so a relatively high degree of filJ is required for optical adjustment between the light receiving element array 1 and the light shielding member J2.

Note that the present invention is not limited to the above-mentioned example, and can be modified or changed in many ways.

For example, the stripe mask shown in FIG. 4A] 6-1 to 1
6-n and stripe masks 26-1 to 26-1 shown in FIG.
26-(2n+]) can be formed directly on the light-receiving element, on the body, or on the case or cover of the light-receiving element array. The shape of the mask mentioned above, kJ stripes, can definitely be transformed into gods.

As described above, in the present invention, without using a minute auxiliary optical system to form an image of the exit pupil of the imaging optical system,
A light-shielding member having an opening on the L side of the light-receiving element array is provided, so that two adjacent light-receiving elements are separated from the J-th and second regions that include the optical axis of the imaging optical system. Since the structure is made to have a directional metal layer so that each of the light beams is mainly incident thereon, the structure is simple and easy to manufacture, and the structure can be made inexpensive and compact. Further, since the light receiving element array and the light shielding member can be formed integrally, optical adjustment of both can be easily performed to a quotient of f* lit.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the configuration of a conventional focus detection device, Figure 2 is a plan view showing the arrangement relationship between the auxiliary optical system and the light receiving element array in Figure @1, and Figure 3 is a diagram showing the configuration of a conventional focus detection device. 4A, B and C are lines showing the configuration of the light shielding member and light receiving element array shown in FIG. 3 and their arrangement relationship. 5 is a line diagram showing the directivity characteristics of a pair of light receiving elements according to the present invention. FIG. 6 is a block diagram showing the configuration Fy of an example of a signal processing circuit of the focus detection device according to the present invention. The figure is a line diagram showing all aspects of the detection signal representing the focus state, Figure 8 is a line diagram showing the configuration of another example of the light shielding member used in the focus detection device of the present invention, Figure 9 e'': Figure 8 FIG. 3 is a plan view showing the arrangement relationship between the second light shielding member and the light receiving element array shown in FIG. J. Subject, 2. Imaging (photography) optical system, 3. Quick return mirror, 6. Film, 7. Half mirror 18
Reflection mirror,] 1 Light-receiving element array, 12 - Light shielding member, ]
a-substrate, 14A, 14B-light receiving element group,] 4 A
, -] ~J4A-n,14B-1~
J4B-n-light receiving element, ]5...transparent substrate, 16-''~
16-n stripe mask, 17 openings, ]8 A/
D conversion circuit, J9... η circuit, 20 Display circuit, 2
]-fu control circuit, 22 light shielding member, 23 transparent substrate,
24-1 to 24-n...stripe mask, 25 opening, 26-1 to 26-(2n+1) stripe mask, 27 opening. Patent Applicant: t IJ Mbus Hikariji Kogyo Co., Ltd. Figure 4 Figure 5 Figure 6 Procedural Amendment Statement August 25, 1981 1. Indication of Matter No. 1 1988 Patent Application No. 100759 2. Name of the invention A<d Detection device 3, relationship with correction person A'1 i1. ! ! '〒Revised applicant applicant 7)
Olympus Optical Industry Co., Ltd. (58)
No. 2241 (Representative) 5゜6 Correction target

Claims (1)

[Claims] ■ Arranged at or near the predetermined focal plane of the imaging optical system 1
A light receiving element array is disposed in the optical path between the light receiving element array and the imaging optical system, and a plane including the optical axis of the imaging optical system is bounded by adjacent light receiving elements in the light receiving element array. a light shielding member having an aperture formed to mainly allow light from the first and second regions respectively to be incident thereon; A focus state of the object image formed by the imaging optical system by detecting the lateral shift of the object image formed in the light receiving element group that receives light and the light receiving element group that receives light from the second area. A focus detection device characterized by being configured to detect. Herein, the light shielding member includes a first light shielding member having a relatively large aperture arranged on the side of the imaging optical system, and a second light shielding member having a relatively small aperture disposed on the side of the light receiving element array. The focus detection device according to claim 1, characterized in that t' has the following characteristics.