JPH06308375A - Focus detector - Google Patents

Abstract

PURPOSE:To provide a focus detector by which an image with high quality can be photographed and which is made as compact as possible. CONSTITUTION:Luminous flux for detecting a focus receiving an image forming action by a photographing lens 11 is guided to the detection aperture part 17 of the bottom part 12a of a mirror box 12 by a sub-mirror 15 in the box 12 and made incident on an image reforming optical system securing focusing accuracy by a condenser lens 18, a pair of brightness diaphragms 20a and 20b and image reforming lenses 21a and 21b where respective apertures corresponding to respective incident pupils are formed and photoelectrical conversion means 22a and 22b corresponding to the apertures of the respective diaphragms 20a and 20b from the aperture part 17. Then, two-surface light shielding walls 23a and 23b are arranged between the scheduled image forming surface 16 of the lens 11 in the box 12 and the bottom part 12a of the box 12 so that they are not in parallel with an image pickup surface 13 in order to detect the focus by detecting the phase difference of an output signal expressing the distribution of light intensity from the conversion means 22a and 22b corresponding to the respective incident pupils.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detection device,
More specifically, it relates to improvement of a focus detection device in a single-lens reflex camera or the like.

[0002]

2. Description of the Related Art Conventionally, as a focus detecting device of this type, an image formed by a photographing lens of a photographing optical system is used.
The re-imaging optical system symmetrically divides into two in a plane including the optical axis, and each photoelectric conversion element row (each light receiving element row) corresponding to each
A number of focus detection systems have been proposed which are re-formed on the photoelectric conversion means consisting of, and detect the positional shift between these two divided images to make a focus determination.
JP-A-55-118019 and JP-A-58-106
There are respective techniques disclosed in Japanese Patent Application Laid-Open No. 511, JP-A-60-32012 and the like. In each of these prior arts, each represents the light intensity distribution obtained by the photoelectric conversion means in the re-imaging optical system corresponding to the two entrance pupils capable of ensuring focusing accuracy. The focus is determined by detecting the phase difference between the two output signals.

FIG. 11 shows the concept of a re-imaging optical system in a conventional single-lens reflex camera of this type. That is, in the configuration of the re-imaging optical system of FIG. 11, reference numeral 51 is a condenser lens, and 52 is a field stop of a planned image formation surface provided close to the front surface side of the condenser lens 51. Reference numerals 53a and 53b are a pair of A re-imaging lens and B re-imaging lens arranged behind the condenser lens 51, and 54a and 54b.
Is the A re-imaging lens 53a and the B re-imaging lens 5
3A shows a pair of A aperture stop and B aperture stop that are provided close to the front side of 3b and similarly have a pair of apertures corresponding to the respective entrance pupils. Further, 55a and 55b are an A light receiving element array and a B light receiving element array as photoelectric conversion means provided corresponding to the A re-imaging lens 53a and the B re-imaging lens 53b. Here, in the configuration of such a re-imaging optical system, a light beam (so-called stray light) incident on the photoelectric conversion means from an incompatible entrance pupil.
In other words, in the case of the configuration shown in FIG. 11, it is necessary to block the light flux that passes through the B aperture stop 54b and is incident on the A light receiving element array 55a. It is generally known that stray light can be efficiently shielded by providing a field stop 52 on the planned image forming surface as in the configuration of FIG. 11 described above. Japanese Patent No. 133018 also proposes a configuration in which the detection aperture at the bottom of the mirror box and the field stop are integrated.

On the other hand, in the photographing optical system, in order to form a high-quality image, it is necessary to minimize the occurrence of flare in the device configuration. Of these, at the bottom of the mirror box. As one of the low-cost countermeasures for reducing the flare of, for example, FIG. 12 (a)
As shown in, the bottom portion 41a of the mirror box 41 with respect to the optical axis 42 of the taking lens in the mirror box 41.
12B, the flare 44 generated may be reflected by the surface of the bottom portion 41a and directly enter the imaging surface 43 such as a film. As described above, the bottom portion 41a of the mirror box 41 is arranged so as to be sufficiently separated from the optical axis 42 of the taking lens.
There is a configuration in which the flare 44 reflected by the surface is prevented from directly entering the imaging surface 43. Further, in view of the optical characteristics of the taking lens, in particular, in the configuration of the taking lens system having a small F value such as the wide-angle lens, in order to enable high quality image taking, the final taking lens system of the taking lens system with respect to the imaging surface There is a desire to bring the steps as close as possible. For example, in FIG.
As shown in FIG. 3 (a), the quick return mirror 45 is arranged so that the planned image forming surface 47 of the light flux entering the focus detection system from the photographing optical system coincides with the bottom portion 41a of the mirror box 41.
In order to satisfy such a demand without causing a phenomenon called so-called mirror breakage in the configuration in which the combination of the sub-mirror 46 and the sub-mirror 46 is arranged respectively, as shown in FIG. 13 (b), With respect to the imaging surface 43,
It is desirable to make the combination of the quick return mirror 45 and the sub mirror 46 as close as possible. That is, for each of these conventional means, as can be seen in FIGS. 12 (b) and 13 (b), respectively, as a result, as a result, the planned image forming plane 47 of the photographing lens with the light flux used for focus detection is obtained. Is an indispensable element that is separated from the bottom portion 41a side of the mirror box 41 and is brought closer to the optical axis 42 side of the taking lens. Incidentally, these FIG. 13 (a),
In (b), reference numerals 48 and 49 denote upper and lower luminous fluxes.

[0005]

However, as described above, the planned image forming surface 47 of the taking lens is placed on the mirror box 4 as described above.
1 is separated from the bottom 41a side, that is, in other words, as shown in FIG. 14, when the planned image forming surface 47 of the taking lens in the mirror box 41 and the field stop 52 are relatively separated from each other. However, there arises a problem that it is difficult to block the stray light 50, which is a light flux that enters each of the light receiving element arrays 55a and 55b from the non-corresponding entrance pupils.

Therefore, in order to avoid this, in the mirror box 41, for example, a light-shielding cylinder or the like (not shown) is arranged, and the light-shielding action of the light-shielding cylinder or the like is utilized to make Although it is possible to bring the field stop 52 closer to the planned image forming surface 47, in such a complicated configuration of disposing the light shielding tube or the like, the light flux from the photographing lens to the image capturing surface 43 such as a film is blocked during photographing. Or
It is not preferable because it causes flare. Further, each aperture stop in the focus detection system (see FIG. 11, A aperture stop 5
4a and B corresponding to the B aperture stop 54b) between the respective light receiving element rows corresponding to each other, that is, between the A light receiving element row 55a and the B light receiving element row 55b, the respective light receiving element rows 55a and 55b are expanded. Stray light 50 (Fig.
However, in the case of such a configuration, there is a disadvantage that the device itself is unnecessarily increased in size.

The present invention has been made to solve the above-mentioned conventional problems, and the purpose thereof is to:
It is an object of the present invention to provide a focus detection device that enables high-quality images to be captured and, at the same time, makes the device configuration as compact as possible.

[0008]

In order to achieve the above-mentioned object, a focus detecting apparatus according to the present invention uses a mirror box to detect a light flux for focus detection which is subjected to an image forming operation by a photographing lens of a photographing optical system. By the sub-mirror that is provided up and down freely in front of the imaging surface in the inside, while leading to the detection opening formed in the bottom of the mirror box through the planned image formation surface of the taking lens, from the detection opening, the condenser lens,
At least a pair of aperture diaphragms and re-imaging lenses having apertures corresponding to the respective entrance pupils, and photoelectric conversion means having light receiving element arrays corresponding to the apertures of the aperture diaphragms are provided at least. The light is incident on the re-imaging optical system capable of ensuring the focusing accuracy and is obtained from the photoelectric conversion means in the re-imaging optical system corresponding to each entrance pupil capable of ensuring the focusing accuracy, and the In a focus detection system for detecting a phase difference between individual output signals representing an intensity distribution to perform focus detection, an image pickup surface is provided between a planned image forming surface of a photographing lens in the mirror box and a bottom portion of the mirror box. Not parallel to
It is characterized in that at least two light shielding walls are arranged.

Further, in the focus detecting device according to the present invention, a sub-mirror is provided which is capable of undulating a light beam for focus detection, which is subjected to an image forming action by a photographing lens of a photographing optical system, in front of an image pickup surface in a mirror box. Guides the light to the detection aperture formed on the bottom of the mirror box through the planned image formation surface of the taking lens, and from the detection aperture, a condenser lens and a pair of brightnesses each corresponding to each entrance pupil are formed. A diaphragm and a re-imaging lens, and a photoelectric conversion means having at least a light receiving element array corresponding to the aperture of each brightness diaphragm are incident on a re-imaging optical system capable of ensuring focusing accuracy. Then, by detecting the phase difference between the individual output signals obtained from the photoelectric conversion means in the re-imaging optical system corresponding to each entrance pupil capable of ensuring the focusing accuracy, and representing the respective light intensity distributions. Perform focus detection In the point detection system, at least two light shielding walls are arranged between the planned image forming surface of the taking lens in the mirror box and the bottom of the mirror box, and are not parallel to the image pickup surface, and It is characterized in that the light receiving element array is constituted by a plurality of pairs arranged in parallel with each other.

In the present invention, the focus detecting light beam emitted from the object to be focused is subjected to the image forming action by the taking lens of the taking optical system, and is directed to the bottom side by the sub-mirror in front of the image taking surface in the mirror box. After being reflected and passing through a planned image forming surface set in the mirror box, it reaches the detection aperture of the re-imaging optical system having two light shielding walls which are not parallel to the image pickup surface. At this time, apparently, the light passes through the entrance pupils of the respective focus detection systems arranged at intervals that can secure the focusing accuracy, and if the photographing lens is in the focused state, an image is formed on the planned image forming surface. Then, the light flux entering the re-imaging optical system from the detection aperture section has the function of transmitting the pupil by the condenser lens, and a pair of apertures corresponding to the entrance pupil of each focus detection system are formed. After sequentially passing through the aperture stop and the re-imaging lens, each light receiving element row corresponding to the aperture of each pair of the aperture stop is reached, and each light receiving element row As a result, each detection signal obtained by the photoelectric conversion means corresponding to each entrance pupil capable of ensuring the focusing accuracy, here, the phase difference between the individual output signals representing the light intensity distribution is detected. The focus detection is carried out.

Therefore, in the present invention, two light-shielding walls which are provided between the planned image forming plane set in the mirror box of the taking lens and the bottom of the mirror box and are not parallel to the image pickup plane. Stray light is blocked by the stray light, and due to the stray light blocking effect of each light blocking wall, the planned image forming surface of the shooting lens with the light flux used for focus detection is separated from the bottom side of the mirror box, and the optical axis of the shooting lens. It is possible to bring the light receiving elements closer to the side without difficulty, and the arrangement of the light receiving element rows corresponding to the respective aperture diaphragms can be made as close to each other as possible, resulting in the desired high quality. It is possible to easily achieve various image formations and downsizing of the apparatus itself.

Here, in the present invention, since the light shielding walls are not arranged in parallel with the image pickup surface, there is no fear of blocking the light flux from the photographing lens to such an extent that it becomes a practical problem. Moreover, it is possible to secure a sufficient height for shading without causing a large flare. Further, it is preferable that each of the light shielding walls is arranged in a mode that is vertical or almost vertical to the image pickup surface and that the photographing lens side is slightly narrowed so that the influence upon photographing is further reduced. Then, when each of the light shielding walls is made substantially vertical to the image pickup surface, the light shielding efficiency is further improved.
Further, with respect to each of the light-receiving element rows, when these light-receiving element rows are projected on the planned image forming plane, the light-receiving element rows are arranged so as not to overlap each other in the direction perpendicular to the image pickup surface. It is possible to prevent invasion of stray light from the side where the light shielding walls are not arranged (in this case, the portion parallel to the imaging surface).

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, different embodiments of the focus detecting device according to the present invention will be described in detail with reference to FIGS.

First Embodiment FIGS. 1 to 3 show a focus detection apparatus to which the first embodiment of the present invention is applied. FIG. 1 shows a single lens reflex camera to which the focus detection apparatus according to the first embodiment is applied. FIG. 2 is a cross-sectional configuration diagram schematically showing the outline of the camera, and FIG. 2 is a perspective view showing an installation mode of each light shielding wall at the bottom of the mirror box as seen from the side of the photographing optical system, and FIG. It is explanatory drawing which shows the installation aspect of each shading wall toward the center of the exit pupil in a lens.

That is, in the apparatus configuration shown in FIGS. 1 and 2, the taking optical system in the apparatus according to the first embodiment includes a taking lens 11 arranged in the lens barrel of the camera and a taking lens 1.
1 and a mirror box 1 between an imaging surface 13 such as a film
2, a quick-return mirror 14 and a sub-mirror 15 made of a semi-transparent member that are arranged up and down freely, and the sub-mirror 15 and the bottom 12a of the mirror box 12.
And a bottom portion 1 of the mirror box 12 through a planned image forming surface 16 formed by the taking lens 11, which is set between
2a, and the detection aperture 17 in the re-imaging optical system. In addition, the re-imaging optical system includes the detection aperture 17
1, a condenser lens 18 arranged outside the mirror box 12, a reflection member 19 arranged behind the condenser lens 18, and a reflection member 19 arranged behind the reflection member 19 in a direction perpendicular to the plane of FIG. Side by side, a pair of aperture diaphragms 2 each having an aperture formed corresponding to each entrance pupil 2
0a, 20b, the re-imaging lenses 21a, 21b corresponding to the respective aperture stops 20a, 20b, and the re-imaging lenses 21a, 21b arranged near the imaging positions of the light beams emitted from the re-imaging lenses 21a, 21b. Similarly, it has respective light receiving element rows 22a and 22b arranged in a direction perpendicular to the paper surface of FIG. Furthermore,
The bottom portion 12a of the mirror box 12 and the planned image forming surface 16
As is clear from FIG. 2, a pair of light shielding walls 23a, which are arranged corresponding to the detection openings 17,
23b is provided. The tip ends of the light shielding walls 23a and 23b are provided at the light receiving element rows 22a and 22b.
It is desirable that it be conjugate with the surface on which b is arranged in the re-imaging optical system, and it does not necessarily have to coincide with the planned imaging surface 16. In addition, each of these light shielding walls 23
As for a and 23b, as shown in FIGS. 1 and 2, it may be formed in a direction perpendicular to the image pickup surface 13 such as a film surface, or alternatively, the mirror box 12 may have a bottom 12a. As shown in FIG. 3, which is an example when the side is viewed, it may be directed to the center of the exit pupil of the taking lens 11.

Therefore, in the case of the apparatus of the first embodiment having the above-mentioned configuration, the light flux for focus detection that has emitted an object to be focused is
First, after passing through the taking lens 11 of the taking optical system and receiving the image forming action, and passing through the quick return mirror 14 in the mirror box 12, it is reflected by the sub mirror 15 and reaches the planned image forming surface 16, and Shooting lens 11
Is focused, an image is formed on the planned image forming surface 16,
Further, the light flux that has passed through the planned image forming surface 16 enters the re-imaging optical system from the detection opening 17 of the bottom 12a of the mirror box 12. Next, the focus detection light flux entering the re-imaging optical system reaches the respective aperture stops 20a and 20b after being transmitted through the condenser lens 18 through the pupil and reflected by the reflecting member 19. . That is, the entrance pupils of the focus detection system, which are determined by the condenser lens 18 and the respective aperture stops 20a and 20b, are arranged at intervals that can secure the focusing accuracy here. Continued,
The light fluxes that have passed through the respective aperture stops 20a and 20b are incident on the respective re-imaging lenses 21a and 21b, and the respective light fluxes that have passed through the respective re-imaging lenses 21a and 21b are received in parallel. It is guided by the element rows 22a and 22b to be detected. In this case, the respective light receiving element rows 22a and 22b are detected.
22b can be arranged as close as possible by the light shielding effect of the respective light shielding walls 23a and 23b. As a result, the first embodiment apparatus has an extremely simple configuration, Therefore, it is possible to form a high-quality image, and at the same time, it is possible to easily make the apparatus itself compact.

Second Embodiment FIGS. 4 to 6 show a focus detecting device to which a second embodiment of the present invention is applied. FIG. 4 shows a single lens reflex camera to which the focus detecting device according to the second embodiment is applied. FIG. 6 is a cross-sectional configuration diagram schematically showing the outline of the camera, and FIG. 5 is a perspective view showing an installation mode of each light shielding wall at the bottom of the mirror box as seen from the photographing optical system side, and FIG. It is explanatory drawing which shows the arrangement aspect of each light receiving element row | line in a detection system.

That is, in the apparatus configuration shown in FIGS. 4 to 6, the taking optical system in the apparatus of the second embodiment is such that the taking lens 11 disposed inside the lens barrel of the camera, the taking lens 11 and the film. Between the image pickup surface 13 such as a surface and the like, and a quick return mirror 14 and a sub-mirror 15 that are arranged in a foldable manner in the mirror box 12 and a sub-mirror 15, and the sub-mirror 15 and the bottom portion 12 a of the mirror box 12. The photographing lens 1 to be set in between
It has a detection aperture 17 formed in the bottom 12a of the mirror box 12 through the planned image forming surface 16 of 1. The re-imaging optical system includes a condenser lens 18 arranged outside the mirror box 12 near the rear of the detection opening 17, a reflecting member 19 arranged behind the condenser lens 18, and a reflecting member 19. A pair of brightness diaphragms 24a, 2 arranged at the rear side and arranged in the up-down direction on the paper surface of FIG. 4 to form openings corresponding to the respective entrance pupils.
4b, re-imaging lenses 25a and 25b corresponding to the aperture diaphragms 24a and 24b, and re-imaging lenses 2 respectively.
Each light receiving element array 2 arranged near the image forming position of the light flux emitted from 5a, 25b and arranged in the direction perpendicular to the paper surface of FIG.
6a and 26b. Here, because of this configuration, in FIG. 4, the respective re-imaging lenses 25a, 25
The optical axis of b is not included on the same plane parallel to the paper surface at the same time, and the direction in which the light receiving element rows 26a and 26b are arranged is the direction perpendicular to the paper surface. Further, the mirror box 12
As shown in FIG. 5, a pair of light shielding walls 27a and 27b arranged corresponding to the detection opening 17 is provided between the bottom 12a of the optical disc and the planned image forming surface 16. . The tip end of each of the light shielding walls 27a and 27b is preferably conjugate with the surface on which the light receiving element rows 26a and 26b are arranged in the re-imaging optical system, and is not necessarily the planned image forming surface 16 Need not match.

Therefore, also in the case of the apparatus of the second embodiment having the above-mentioned structure, the light flux for focus detection, which has emitted the object to be focused, first passes through the taking lens 11 of the taking optical system to form an image. In addition, after passing through the quick return mirror 14 in the mirror box 12, it is reflected by the sub-mirror 15 to reach the planned image forming surface 16, and when the taking lens 11 is in focus, the predetermined image forming surface 16 is received. The light flux that has been imaged on the upper side and has passed through the planned image formation surface 16 is made incident on the re-imaging optical system from the detection opening 17 of the bottom 12 a of the mirror box 12. Then, the light beam for focus detection that is made incident on the re-imaging optical system is the condenser lens 18
The pupil is transmitted by and is reflected by the reflecting member 19, and then reaches the respective aperture stops 24a, 24b. That is, the entrance pupils of the focus detection system, which are determined by the condenser lens 18 and the brightness diaphragms 24a and 24b, are arranged at intervals that can secure the focusing accuracy here. Subsequently, the light fluxes passing through the respective aperture stops 24a, 24b are made incident on the respective re-imaging lenses 25a, 25b,
The respective light fluxes that have passed through the respective re-imaging lenses 25a and 25b are guided to and detected by the respective light receiving element rows 26a and 26b. Even in the configuration of the second embodiment device, the first embodiment device is also used. In addition to the same function and effect as described above, a further better function and effect can be obtained.

Third Embodiment FIGS. 7 to 9 show a focus detecting apparatus to which a third embodiment of the present invention is applied. FIG. 7 shows a single lens reflex camera to which the focus detecting apparatus according to the third embodiment is applied. FIG. 9 is a cross-sectional configuration diagram schematically showing the outline of the camera, and FIG. 8 is a perspective view showing an installation mode of each light shielding wall at the bottom of the mirror box as seen from the photographing optical system side, and FIG. It is explanatory drawing which shows the arrangement aspect of each light receiving element row | line in a detection system.

That is, in the apparatus configuration shown in FIGS. 7 to 9, the taking optical system in the apparatus of the third embodiment is such that the taking lens 11 disposed inside the lens barrel of the camera, the taking lens 11 and the film. Between the image pickup surface 13 such as a surface and the like, and a quick return mirror 14 and a sub-mirror 15 that are arranged in a foldable manner in the mirror box 12 and a sub-mirror 15, and the sub-mirror 15 and the bottom portion 12 a of the mirror box 12. The taking lens 1 that is formed between
It has an introduction opening 17 formed in the bottom portion 12a of the mirror box 12 through the planned image forming surface 16 of 1.
Further, the focus detection optical system by re-imaging is provided with the introduction opening 17
7, a condenser lens 18 arranged outside the mirror box 12 near the rear of the condenser lens, a reflection member 19 arranged behind the condenser lens 18, and a reflection member 19 arranged behind the reflection member 19 in a direction perpendicular to the plane of FIG. Side by side, a pair of respective aperture stops 28 formed with openings corresponding to the respective entrance pupils.
a, 28b, respective re-imaging lenses 29a, 29b corresponding to the respective aperture stops 28a, 28b, and arranged near the image forming positions of the respective light beams emitted from the respective re-imaging lenses 29a, 29b. Similarly, the light receiving element rows 30a and 30b arranged in the direction perpendicular to the paper surface of FIG. 7 and the light receiving element rows 31 parallel to each other with the light receiving element rows 30a and 30b sandwiched therebetween.
a, 31b and 32a, 32b. Furthermore,
The bottom portion 12a of the mirror box 12 and the planned image forming surface 16
And 1 arranged between the and
A pair of light shielding walls 33a and 33b are provided, and the tip portions of the light shielding walls 33a and 33b are provided at the respective light receiving element rows 30a,
It is conjugate with the surface on which 30b, 31a, 31b and 32a, 32b are arranged in the re-imaging optical system, and does not coincide with the planned imaging surface 16.

Therefore, also in the case of the apparatus of the third embodiment having the above-mentioned structure, the light flux emitted from the object to be focused first passes through the taking lens 11 in the taking optical system, and is in the mirror box 12. After passing through the quick return mirror 14, it reaches the planned image forming surface 16 via the sub-mirror 15, and when the photographing lens 11 is in focus, an image is formed on the planned image forming surface 16 and further the planned image forming is performed. The light flux that has passed through the surface 16 is detected by the detection opening 1 at the bottom 12 a of the mirror box 12.
It is incident on the re-imaging optical system from 7. Then, the light flux entering the re-imaging optical system reaches the respective aperture stops 28a and 28b after being transmitted through the pupil by the condenser lens 18 and reflected by the reflecting member 19. That is, the entrance pupils of the focus detection system, which are determined by the condenser lens 18 and the respective aperture stops 28a and 28b, are arranged at intervals that can secure the focusing accuracy here. Subsequently, the light fluxes that have passed through the respective aperture stops 28a and 28b are incident on the respective re-imaging lenses 29a and 29b, and the respective light fluxes from the respective re-imaging lenses 29a and 29b are arranged in a straight line. The light receiving element rows 30a and 30b and the respective light receiving element rows 31a, 31b and 32a, 32b that are parallel to each other with the light receiving element rows 30a and 30b interposed therebetween are guided and detected. Then, each light receiving element array 30
As shown in FIG. 9, a, 30b and 31a, 31b and 32a, 32b are arranged with a minimum gap required in terms of the element structure. Since there is no conjugate relationship with the image forming surface 16, for example, as shown in FIG. 10, the information in the distance measuring field, in other words, the information on the planned image forming surface 16 covers almost the entire range without any gap. It is guided to each light receiving element surface over,
Also in the configuration of the device of the third embodiment, in addition to the same action and effect as in the device of the first embodiment, more favorable action and effect can be obtained.

[0023]

As described above in detail with respect to each embodiment, according to the present invention, an image pickup surface is provided between the planned image forming surface of the taking lens set in the mirror box and the bottom of the mirror box. Since two non-parallel light shielding walls are provided, stray light blocks the invasion of stray light, and due to the stray light shielding effect of each of these light shielding walls, the light flux used for focus detection is The planned image forming surface of the taking lens can be reasonably brought close to the optical axis side of the taking lens by separating it from the bottom side of the mirror box, and it is possible to arrange each light receiving element row corresponding to each brightness diaphragm. As a result, the present invention has an excellent feature that the apparatus itself can be easily and effectively made compact in accordance with the formation of a high-quality image in the apparatus configuration.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram schematically showing an outline of a single-lens reflex camera to which a focus detection device according to a first embodiment of the present invention is applied.

FIG. 2 is a perspective view showing an installation mode of each light shielding wall at the bottom of the mirror box when viewed from the side of the photographing optical system according to the first embodiment.

FIG. 3 is an explanatory diagram showing another installation mode of the respective light shielding walls toward the center of the exit pupil in the taking lens unit according to Example 1 of the same.

FIG. 4 is a sectional configuration diagram schematically showing an outline of a single-lens reflex camera to which a focus detection device according to a second embodiment of the present invention is applied.

FIG. 5 is a perspective view showing an installation mode of each light shielding wall at the bottom of the mirror box as viewed from the side of the photographing optical system according to the second embodiment.

FIG. 6 is an explanatory diagram showing an arrangement mode of respective light receiving element rows in the focus detection system according to the second embodiment.

FIG. 7 is a sectional configuration diagram schematically showing an outline of a single-lens reflex camera to which a focus detection device according to a third embodiment of the present invention is applied.

FIG. 8 is a perspective view showing an installation mode of each light shielding wall at the bottom of the mirror box as viewed from the side of the photographing optical system according to the third example.

FIG. 9 is an explanatory diagram showing an arrangement mode of respective light receiving element rows in the focus detection system according to the third embodiment.

FIG. 10 is an explanatory diagram showing the operation of the focus detection system according to the third embodiment.

FIG. 11 is an explanatory diagram showing an operation of a conventional general focus detection system.

12 (a) and 12 (b) are cross-sectional explanatory views each showing a conventional flare incidence relationship due to the arrangement of the optical axis of the taking lens and the bottom of the mirror box with respect to the imaging surface.

13 (a) and 13 (b) are cross-sectional explanatory views each showing the positional relationship between the optical axis of the taking lens and the planned image forming surface via the sub-mirror with respect to the conventional image pickup surface.

FIG. 14 is a cross-sectional explanatory view showing a conventional invasion path of stray light with respect to an imaging surface.

[Explanation of symbols]

11 Shooting Lens 12 Mirror Box 12a Bottom of Mirror Box 13 Imaging Surface such as Film 14 Quick Return Mirror 15 Sub Mirror 16 Planned Image Forming Surface 17 Detection Aperture 18 Condenser Lens 19 Reflecting Member 20a, 20b, 24a, 24b, 28a, 28b Brightness Diaphragm 21a, 21b, 25a, 25b, 29a, 29b re-imaging lens 22a, 22b, 26a, 26b, 30a, 30b, 3
1a, 31b, 32a, 32b
Light receiving element array 23a, 23b, 27a, 27b, 33a, 33b Light shielding wall

Claims (2)

[Claims] 1. A sub-mirror provided in a mirror box so as to be capable of undulating in front of an image pickup surface in a mirror box, a light beam for focus detection which has been subjected to an image forming action by a photographing lens of a photographing optical system.
A pair of brightness diaphragms are formed that lead to a detection aperture formed at the bottom of the mirror box through the planned image forming surface of the taking lens, and form a condenser lens and each aperture corresponding to each entrance pupil from the detection aperture. , And a re-imaging lens and a photoelectric conversion unit having each light receiving element array corresponding to the aperture of each aperture stop are made to enter at least a re-imaging optical system capable of ensuring focusing accuracy, The focus detection is performed by detecting the phase difference between the individual output signals obtained from the photoelectric conversion means in the re-imaging optical system corresponding to the respective entrance pupils capable of ensuring the focusing accuracy and individually representing the light intensity distribution. In the focus detection system for performing, a planned image forming surface of the taking lens in the mirror box,
A focus detection device characterized in that at least two light-shielding walls are arranged between the bottom of the mirror box and not in parallel with the imaging surface. 2. A sub-mirror that is provided up and down freely in front of an image-capturing surface in a mirror box for a focus-detecting light beam that has undergone an image-forming action by the image-capturing lens of the image-capturing optical system.
A pair of brightness diaphragms are formed that lead to a detection aperture formed at the bottom of the mirror box through the planned image forming surface of the taking lens, and form a condenser lens and each aperture corresponding to each entrance pupil from the detection aperture. , And a re-imaging lens and a photoelectric conversion unit having each light receiving element array corresponding to the aperture of each aperture stop are made to enter at least a re-imaging optical system capable of ensuring focusing accuracy, The focus detection is performed by detecting the phase difference between the individual output signals obtained from the photoelectric conversion means in the re-imaging optical system corresponding to the respective entrance pupils capable of ensuring the focusing accuracy and individually representing the light intensity distribution. In the focus detection system for performing, a planned image forming surface of the taking lens in the mirror box,
At least two light shielding walls are arranged between the bottom of the mirror box and the image pickup surface in a state not parallel to the image pickup surface, and the light receiving element rows are constituted by a plurality of pairs arranged in parallel with each other. Focus detection device.