JPH06118299A - Focal point detecting device - Google Patents

Abstract

PURPOSE:To surely fix an aperture mask and an image reforming lens at the preset positions in a focal point detecting device arranged to automatically detect the focal point state in a camera. CONSTITUTION:The first reference plane 63 restricting the optical axis direction position of an aperture mask 59 is formed on the support section 51c of a device main body 51, the second reference plane 65 restricting the optical axis direction position of an image reforming lens 61a (61b) is formed, and an elastic member 69 pressing the aperture mask 59 toward the first reference plane 63 is arranged between the image reforming lens 61a (61b) and the aperture mask 59.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detecting device arranged in a camera or the like for automatically detecting a focus state.

[0002]

2. Description of the Related Art Conventionally, in a camera or the like, for example, a focus detection device using a TTL phase difference detection method is often used to automatically detect a focal length.

FIG. 3 shows a camera equipped with this type of focus detection device. In this camera, a part of the subject light that has passed through the taking lens 11 is placed in a mirror box 13 which is a movable mirror 15. After passing through the light-transmitting part, the light is reflected downward by the sub-mirror 17 fixed to the movable mirror 15 and is incident on the focus detection device 19.

The light incident on the focus detection device 19 passes through the condenser lens 21, is reflected by the mirror 23, and then is guided to the photoelectric conversion element array 29 through the diaphragm mask 25 and the re-imaging lens 27.

On the other hand, part of the subject light reflected by the movable mirror 15 passes through the viewfinder screen 31 from the upper opening of the mirror box 13, is guided to the pentaprism 33 of the viewfinder, and is bent by the pentaprism 33. Then, it is guided to the photographer's eyeball through the eyepiece lens 35.

FIG. 4 shows the details of the optical system of the focus detecting device 19 described above. The subject light that has passed through the taking lens 11 is imaged on the planned focal plane 37, and after passing through the condenser lens 21, The pupil of the taking lens 11 is divided into two regions by the aperture mask 25 having the pair of apertures 25a and 25b, and the apertures 25a and 2 of the aperture mask 25 are divided.
5b, a pair of re-imaging lenses 27a formed corresponding to 5b,
It is led to a pair of photoelectric conversion element rows 29a and 29b through 27b.

Then, the pair of photoelectric conversion element arrays 29a, 2
It is determined whether or not the light amount distribution of the secondary image re-formed on 9b deviates from the reference distribution at the time of focusing, and the focus of the photographing lens 11 is detected based on the relative positional relationship. Be seen.

Conventionally, the diaphragm mask 25 and the re-imaging lenses 27a and 27b described above are disclosed, for example, in JP-A-61-16.
It is attached to the device body of the focus detection device as disclosed in Japanese Patent No. 5712.

FIG. 5 shows the details of the mounting portion disclosed in this publication, in which a supporting portion 39a formed in the apparatus body 39 is provided with a through hole 39b which serves as an optical path of light from the condenser lens 21. Has been done.

A diaphragm mask 25 having a pair of openings 25a and 25b is formed on a side surface of the support portion 39a opposite to the condenser lens 21, and is adjacent to the diaphragm mask 25 at a position facing the through hole 39b. , Diaphragm mask 25
Lens plate 41 in which a pair of re-imaging lenses 27a and 27b are formed at positions corresponding to the pair of openings 25a and 25b.
Are arranged.

A boss 39c is provided on the support portion 39a so as to project therefrom. The boss 39c is inserted through the through holes formed in the diaphragm mask 25 and the lens plate 41 to form the boss 39c.
The diaphragm mask 25 and the lens plate 41 are fixed to the support portion 39a by adhering 43 the tip of c to the lens plate 41.

According to such a mounting structure, by sufficiently controlling the positional accuracy of the aperture mask 25 and the through holes of the lens plate 41, the positions of the aperture mask 25 and the lens plate 41 in the direction perpendicular to the optical axis. The deviation can be made sufficiently small.

[0013]

However, in such a conventional mounting structure, since the diaphragm mask 25 and the lens plate 41 are superposed adjacent to each other, the position of the lens plate 41 in the optical axis direction is the diaphragm. There is a problem that it is difficult to dispose the lens plate 41 at a predetermined position due to the influence of the thickness error of the mask 25.

That is, when the position of the re-imaging lens 27 deviates from the predetermined position in the optical axis direction as described above, the accuracy of the distance between the re-imaging lens 27 and the photoelectric conversion element array 29 decreases, and the photoelectric conversion element array is reduced. The relative positional relationship of the light quantity distribution of the secondary image at 29 is deviated due to an error in the interval.

In this type of focus detection device, after being incorporated in a camera, a correction term for correcting the gap between the secondary image interval and the conversion factor of the focus state of the photographing lens 11 due to various dimensional errors. However, if the factor of the conversion coefficient shift increases, it takes a long time to perform the adjustment after assembling, and in some cases, the shift cannot be corrected because the shift is large.

The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to provide a focus detection device capable of securely fixing the diaphragm mask and the lens plate at a predetermined position.

[0017]

In the focus detecting apparatus of the present invention, a through hole 51d which is an optical path of light from a condenser lens 55 is formed in a supporting portion 51c formed in a main body 51 of the apparatus, and the supporting portion is formed. A diaphragm mask 59 having a pair of openings 59a and 59b formed at a position facing the through hole on the side opposite to the condenser lens.
In the focus detection device, which is arranged next to the diaphragm mask, has a lens plate 61 on which a pair of re-imaging lenses 61a and 61b are formed at positions corresponding to the pair of openings of the diaphragm mask. Forming a first reference surface 63 for restricting the position of the diaphragm mask in the optical axis direction, and forming a second reference surface 65 for restricting the position of the lens plate in the optical axis direction. An elastic member 6 for pressing the diaphragm mask toward the first reference surface between the mask and the mask.
9 are arranged.

[0018]

In the focus detecting apparatus of the present invention, the position of the diaphragm mask in the optical axis direction is regulated by pressing the diaphragm mask against the first reference surface formed on the supporting portion by the elastic member.

By pressing the lens plate against the second reference surface formed on the supporting portion, the position of the re-imaging lens in the optical axis direction is regulated.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 show an embodiment of the focus detection apparatus of the present invention, in which reference numeral 51 is used.
Indicates the apparatus main body.

A through hole 5 is formed in the upper surface 51a of the apparatus main body 51.
1b is formed, and the diaphragm member 53 and the condenser lens 55 are arranged in the through hole 51b. Below the condenser lens 55, a mirror 57 that reflects the light from the condenser lens 55 is provided.
5 is arranged at an angle of 45 degrees with respect to the optical axis L.

A support portion 51c is formed integrally with the device body 51 in the center of the device body 51 in a direction perpendicular to the optical axis L of the light of the condenser lens 55 reflected by the mirror 57.

A through hole 51d is formed in the center of the support portion 51c to serve as an optical path for the light from the condenser lens 55. A diaphragm mask 59 having a pair of openings 59a and 59b formed therein is disposed on a side surface of the support portion 51c opposite to the condenser lens 55, at a position facing the through hole 51d.

A pair of openings 59a and 59b of the diaphragm mask 59 are arranged at a predetermined distance from the diaphragm mask 59.
A lens plate 61 on which a pair of re-imaging lenses 61a and 61b are formed is arranged at a position corresponding to.

The lens plate 61 is made of transparent resin. Thus, in this embodiment, the supporting portion 51c
A rectangular recess 51e is formed on the side of the stop mask 59, and the bottom surface of the recess 51e is the optical axis L of the stop mask 59.
It serves as a first reference surface 63 for regulating the directional position.

The side surface of the support portion 51c outside the recess 51e serves as a second reference surface 65 for regulating the position of the lens plate 61 in the optical axis L direction. Support part 51c
A pair of bosses 51f are provided at predetermined intervals in the vertical direction on the lens plate 61 side of the boss 51f.
Through holes 59c and 59d formed in the aperture mask 59.
And through holes 61c and 61d formed in the lens plate 61
Has been inserted into.

A pair of screw holes 61e and 61f are formed in the lens plate 61 at predetermined intervals in the vertical direction, and a screw 67 is inserted through the screw holes 61e and 61f so that the tip of the screw 67 is supported by a supporting portion. The lens plate 61 is fixed to the support portion 51c by being screwed into screw holes 65a and 65b formed in the second reference surface 65 of 51c.

An elastic member 69 made of, for example, sponge, rubber or the like is arranged between the lens plate 61 and the diaphragm mask 59 to press the diaphragm mask 59 toward the first reference surface 63. .

The elastic member 69 has an annular shape surrounding the pair of openings 59a and 59b of the diaphragm mask 59. One side of the elastic member 69 is directly contacted with the lens plate 61, and the other side is covered with the diaphragm mask 59. It is directly abutted.

In the focus detection device described above, the support portion 51c
The bosses 51f formed in the position regulate the positions of the lens plate 61 and the aperture mask 59 in the direction perpendicular to the optical axis L.
The position of the diaphragm mask 59 in the optical axis L direction is regulated by the first reference surface 63 formed on the support portion 51c, and the lens plate 61 is formed by the second reference surface 65 formed on the support portion 51c. The position of the optical axis in the optical axis L direction is regulated.

However, in the above-described focus detection device, the diaphragm mask 59 is pressed by the elastic member 69 against the first reference surface 63 formed on the support portion 51c, whereby the position of the diaphragm mask 59 in the optical axis L direction. Is regulated, and the lens plate 61 is attached to the second reference surface 65 formed on the support portion 51c.
By pressing, the position of the lens plate 61 in the optical axis L direction is regulated, so that it becomes possible to easily securely fix the diaphragm mask 59 and the lens plate 61 at a predetermined position.

Therefore, unlike the conventional case, the position of the lens plate 61 does not deviate from the predetermined position in the optical axis L direction, and stable focus detection accuracy can be secured. Further, since the diaphragm mask 59 is pressed by the elastic member 69 arranged between the lens plate 61 and the diaphragm mask 59, variations in the thickness of the diaphragm mask 59 can be prevented.
Deformation of the elastic member 69 allows reliable absorption,
The diaphragm mask 59 and the lens plate 61 can be securely fixed at a predetermined position.

Further, by only disposing the elastic member 69 between the lens plate 61 and the diaphragm mask 59, the diaphragm mask 59 can be obtained.
Since it can be fixed, it is not necessary to fix the diaphragm mask 59 to the support portion 51c by adhesion or the like, and the number of steps can be reduced.

Further, in this embodiment, the elastic member 69 is
Since the aperture mask 59 has an annular shape that surrounds the pair of openings 59 a and 59 b, the aperture mask 59 is formed on the first reference plane 63.
Can be reliably pressed.

The elastic member 6 having an annular shape as described above
By using 9, it is possible to project the re-imaging lenses 61a and 61b to the elastic member 69 side, so that it is not necessary to use re-imaging lenses 61a and 61b as plano-convex lenses as in the conventional case. As a result, the re-imaging lens 61a,
The degree of freedom of design of 61b is increased, and the reimaging lens 61a,
The performance of the secondary image is not deteriorated due to the deterioration of the performance of 61b.

Further, in this embodiment, the elastic member 69 is used.
Since the lens is directly contacted with the lens plate 61, the number of parts can be reduced. It should be noted that in the above-described embodiment, an example in which the lens plate 61 is fixed to the second reference surface 65 with the screw 67 has been described, but the present invention is not limited to this embodiment, and for example, the lens plate 61 is used. Needless to say, may be fixed to the second reference surface 65 by adhesion or the like.

In the embodiment described above, the aperture mask 59 is formed with the pair of openings 59a and 59b, and the lens plate 61 is formed with the pair of re-imaging lenses 61a and 61b. Although the example in which the present invention is applied to the focus detection device has been described, the present invention is not limited to such an example, and a plurality of pairs of openings are formed in the aperture mask,
Needless to say, the present invention can be applied to a focus detection device for multi-point distance measurement in which a plurality of pairs of re-imaging lenses are formed on the lens plate.

[0038]

As described above, in the focus detection device of the present invention, the position of the diaphragm mask in the optical axis direction is changed by pressing the diaphragm mask against the first reference surface formed on the supporting portion by the elastic member. The second that is regulated and formed on the support portion
By pressing the lens plate against the reference plane, the position of the lens plate in the optical axis direction is regulated, so that there is an advantage that the diaphragm mask and the lens plate can be reliably fixed at a predetermined position.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a focus detection device of the present invention.

FIG. 2 is an exploded perspective view showing the focus detection device of FIG.

FIG. 3 is an explanatory diagram showing a camera provided with a conventional focus detection device.

FIG. 4 is an explanatory diagram showing an optical system of the focus detection device of FIG.

FIG. 5 is a cross-sectional view showing a part of a conventional focus detection device.

[Explanation of symbols]

 51 Device Main Body 51c Supporting Part 51d Through Hole 55 Condenser Lens 59 Aperture Mask 59a, 59b Opening 61 Lens Plates 61a, 61b Re-imaging Lens 63 First Reference Surface 65 Second Reference Surface 69 Elastic Member L Optical Axis

Claims (3)

[Claims] 1. A support part formed in the main body of the apparatus is provided with a through hole serving as an optical path of light from a condenser lens, and a side surface of the support part opposite to the condenser lens is provided at a position facing the through hole. A diaphragm mask having a pair of openings is arranged, and a lens plate having a pair of re-imaging lenses is arranged next to the diaphragm mask at positions corresponding to the pair of openings of the diaphragm mask. In the focus detection device, the first reference surface that restricts the position of the diaphragm mask in the optical axis direction is formed on the support portion, and the second reference surface that restricts the position of the lens plate in the optical axis direction is formed. A first stop mask is provided between the lens plate and the stop mask.
A focus detection device, in which an elastic member that presses toward the reference surface of is disposed. 2. The focus detection device according to claim 1, wherein the elastic member is in direct contact with the lens plate. 3. The focus detection device according to claim 1, wherein the elastic member has an annular shape surrounding the opening of the diaphragm mask.