JP2007025552A - Movable reflection mirror and camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a movable reflection mirror or the like of which the bound is reduced. <P>SOLUTION: The movable reflection mirror 3 moving between a reflection position for reflecting a luminous flux from a subject and a retreat position for retreating from an optical path of the luminous flux has a configuration including a mirror part 5 having a reflection face and holding parts 6 and 8 for non-fixedly holding the mirror part 5 between themselves, and transmission to the mirror part 5 of vibrations including a twist component, which are generated in the holding part 6 when stopping the movable reflection mirror 3, is prevented to early attenuate the vibrations. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a movable reflector that reflects a subject light beam and guides it to an optical system such as a finder, and retracts from the optical path during exposure, and a camera equipped with such a movable reflector.

A single-lens reflex camera is called a quick return mirror that retracts (mirrors up) between the photographic lens group and the imaging unit immediately before the start of exposure and returns to the original position (mirror down) after the exposure ends. A movable reflector is provided.
Conventionally, a quick return mirror is known that is provided with a mirror balancer that propagates an impact generated at the time of stopping to another member so as to prevent the mirror from bouncing and quickly come to rest (for example, a patent) Reference 1).
JP 7-261268 A

However, such a mirror balancer has a complicated structure, and it is complicated to design each quick return mirror that is different for each model to obtain a desired performance.
An object of the present invention is to provide a movable reflector that can reduce the bounce with a simple configuration, and a camera equipped with such a movable reflector.

The present invention solves the above problems by the following means.
According to a first aspect of the present invention, there is provided a movable reflecting mirror that moves between a reflection position that reflects a subject light beam and a retreat position that is retracted from an optical path of the subject light beam. It is a movable reflecting mirror provided with the clamping part fixedly clamped.

According to a second aspect of the present invention, in the movable reflecting mirror according to the first aspect, the movable reflecting mirror is characterized in that the movable reflecting mirror has a buffer member disposed to face at least one surface of the mirror portion.
According to a third aspect of the present invention, in the movable reflecting mirror according to the first or second aspect, the clamping portion has a pressing portion that presses the surface of the mirror portion on the reflection position side. It is a reflector.

  According to a fourth aspect of the present invention, there is provided an imaging optical system, an imaging surface on which a subject image is formed by the imaging optical system, and a movable reflector group provided between the imaging optical system and the imaging surface. A camera provided with the movable reflector according to any one of claims 1 to 3 in at least a part of the movable reflector group.

  According to the present invention, by holding the mirror portion non-fixed by the holding portion, the impact generated when the movable reflecting mirror stops suddenly becomes difficult to propagate to the mirror portion, and the mirror portion is likely to cause a bounce. Generation of torsional vibrations can be prevented and the bounce of the movable reflector can be reduced.

  The object of the present invention is to provide a quick return mirror or the like with reduced bounce by bringing the main mirror into contact with the main mirror holder in a separable manner and pressing and clamping the main mirror from the opposite surface portion with a spring. Achieve.

A camera main mirror unit that is an embodiment of a movable reflecting mirror to which the present invention is applied will be described below.
FIG. 1 is a diagram showing a configuration around the main mirror unit of the present embodiment.
In this embodiment, the camera is, for example, a lens interchangeable digital single lens reflex camera.
This camera includes a mount 1, an imaging unit 2, a main mirror unit 3, and a stop pin 4.

The mount 1 is a base portion to which a photographic lens barrel (not shown) is detachably mounted, is formed in an annular shape, and is fixed to a camera body (not shown) with its central axis facing the subject side.
The imaging unit 2 includes an imaging surface on which a subject image is formed by a photographic lens group included in the photographic lens barrel, and includes an imaging element such as a CCD or a CMOS that acquires the subject image as an electrical signal. ing.

The main mirror unit 3 is provided between the mount 1 and the imaging unit 2, reflects a subject light beam emitted from the photographing lens group and introduces it into a finder optical system, a photometric optical system, and the like, and a subject light beam. It is a quick return mirror that moves between the retracted position retracted from the optical path.
The main mirror unit 3 includes a reflective surface portion M formed in a substantially rectangular shape. As shown in FIG. 1, at the reflection position, the front end portion (end portion on the subject side) during normal shooting is the rear end portion (image side). The normal line direction of the reflecting surface portion M is inclined at, for example, 45 ° with respect to the optical axis of the photographing lens group.
Further, the main mirror unit 3 is disposed in the vicinity of the rear end portion in the retracted position, and the front end portion is rotated around the rotation axis A extending in the width direction of the camera at the time of normal photographing, thereby reflecting the surface portion. M is substantially parallel to the optical axis.

  The main mirror unit 3 is normally disposed at the reflection position, and the user performs a release operation in this state by performing a preparation operation such as composition setting and exposure determination. When the release operation is performed, the main mirror unit 3 moves from the reflection position to the retracted position (mirror up), and subsequently a shutter (not shown) is opened to start exposure to the imaging unit 2. After that, when the shutter is closed and the exposure is completed, the main mirror unit 3 returns from the retracted position to the reflecting position (mirror down).

  The stop pin 4 is fixed to the camera body, and is a protrusion that abuts on the lower surface of the main mirror unit 3 when it is in the reflection position. And positioning around the rotation axis A when the main mirror unit 3 is in the reflection position.

FIG. 2 is a perspective perspective view of the main mirror unit 3. 3 is a cross-sectional view taken along line III-III in FIG.
The main mirror unit 3 includes a main mirror 5, an upper holder 6, a lower holder 7, a spring 8, an upper cushioning material 9, and a lower cushioning material 10.

The main mirror 5 is formed by forming a metal thin film on the surface (surface on the mount 1 side) of a rectangular glass flat plate to form a mirror-like reflecting surface portion M, at least a part of which is a part of incident light. It is a half mirror that transmits light.
Here, a sub mirror (not shown) is provided on the back surface (surface on the imaging unit 2 side) side of the range where the main mirror 5 is a half mirror. The sub-mirror reflects a part of the subject light flux that has passed through the main mirror 5 and introduces it into an optical system such as an AF distance sensor provided at the lower part of the camera during normal shooting, for example.

The upper holder 6 is a frame body that supports the outer peripheral edge of the main mirror 5 on the surface side and has a rectangular opening. The upper holder 6 is formed by, for example, injection molding of a resin material, and includes protrusions 6a and ribs 6b. Yes.
As shown in FIG. 3, the protrusion 6 a is provided so that the upper holder 6 protrudes from the flat surface portion 6 c facing the surface of the main mirror 5, and the flat surface portion formed at the protruding end contacts the surface of the main mirror 5. Is.
As shown in FIG. 2, the protrusions 6 a are provided at three positions spaced from each other on the inner peripheral edge of the upper holder 6, and the surface of the protrusion 6 a is positioned by supporting the main mirror 5 at three points.
The rib 6b is formed to protrude from the outer peripheral edge of the flat surface portion 6c to the back side of the main mirror 5, and is formed along the outer peripheral edge of the main mirror 5. The main mirror 5 is It restricts movement in a plane parallel to the surface.
Here, the upper holder 6 is merely in contact with the main mirror 5 by the protrusion 6 a and is not fixed, and can be separated in a direction away from the surface of the main mirror 5.

  The lower holder 7 is a frame body provided on the back side of the main mirror 5 and having a rectangular opening, and is formed, for example, by injection molding of a resin material. As shown in FIG. 3, the lower holder 7 is fixed to the upper holder 6 with a flat portion 7 a facing the back surface of the main mirror 5 facing the back surface with a space therebetween. .

The spring 8 is a leaf spring fixed to the flat surface portion 7a of the lower holder 7, and abuts against the back surface of the main mirror 5 to press the main mirror 5 toward the upper holder 6 to be held unfixed. It is.
As shown in FIG. 3, the spring 8 is formed in a band plate shape, and its central portion in the longitudinal direction is fixed to the flat portion 7 a of the lower holder 7, and the regions on both sides thereof are bent toward the upper holder 6 side. The both ends thereof press the back surface of the main mirror 5 by elasticity such as a bent portion.

The upper cushioning material 9 is formed in a sheet shape using an elastic material having a shock absorbing property such as rubber and having a vibration damping capability better than that of the material of the upper holder 6. It arrange | positions between the part 6c and the surface of the main mirror 5, and is being fixed to the plane part 6c by adhesion | attachment etc., for example. Further, the upper cushioning material 9 is disposed on the flat surface portion 6 c of the upper holder 6 so as to avoid the above-described protrusion 6 a.
The upper cushioning material 9 is formed to have a thickness larger than the projection height of the projection 6a from the flat surface portion 6c in a state where no pressure is applied thereto. When the main mirror 5 is pressed by the urging force of the spring 8, the upper cushioning material 9 is compressed and compressed until the surface of the main mirror 5 comes into contact with the protruding end of the protrusion 6a.

The lower cushioning material 10 is formed in a sheet shape using the same material as the upper cushioning material 9, and is disposed between the back surface of the main mirror 5 and the flat portion 7a of the lower holder 7, For example, it is fixed to the flat portion 7a by adhesion or the like. As shown in FIG. 3, the lower cushioning material 10 is in a state of being separated from the main mirror 5 in a normal state, but may be in a state of being lightly pressed against the main mirror 5.
Hereinafter, the effects of the above-described embodiment will be described in comparison with comparative examples described below.

Comparative example

FIG. 4 is an external perspective view of a main mirror unit which is a comparative example of the present invention.
In the following, the same parts as those in the above-described embodiment are denoted by the same reference numerals, description thereof is omitted, and differences are mainly described.
The main mirror unit 11 of the comparative example includes a main mirror 5 and a holder 12.
The holder 12 is a frame body that supports the outer peripheral edge portion on the back surface side of the main mirror 5 and has a rectangular opening, and is formed with a protrusion 12a and a recess 12b.

The protrusion 12a is provided so that the holder 12 protrudes from a flat surface portion 12c facing the back surface of the main mirror 5, and the flat surface portion formed at the protruding end abuts on the back surface of the main mirror 5 to perform positioning. . The protrusions 12 a are provided at three locations on the inner peripheral edge of the holder 12 so as to be separated from each other.
The recess 12b is formed by recessing the flat surface portion 12c and receives a part of the adhesive that bonds the back surface of the main mirror 5 and the holder 12. The recess 12b is formed at a location adjacent to each of the plurality of protrusions 12a.

  The main mirror unit 11 of the comparative example moves from the retracted position to the reflecting position (mirror down), and when the holder 12 collides with the stop pin 4 at the end of the stroke, the holder 12 is twisted by the impact of this collision. Vibration including a vibration mode (hereinafter referred to as “torsional vibration”) occurs. This vibration is also propagated to the main mirror 5 bonded to the holder 12, and the main mirror 5 also vibrates following the holder 12, so that a so-called bounce that does not immediately stop the main mirror 5 occurs.

On the other hand, according to the present embodiment, when the main mirror unit 3 collides with the stop pin 4 at the end of the mirror-down stroke, the main mirror 5 causes the spring 8 and the lower cushioning material 10 to move by the inertial force. While being deformed, it moves relative to the direction away from the upper holder 6 and is not restrained by the upper holder 6 and the lower holder 7.
For this reason, even if torsional vibration is generated in the upper holder 6 and the lower holder 7 due to the collision with the stop pin 4, propagation of the vibration energy to the main mirror 5 is prevented. Torsional vibration is less likely to occur. Further, the torsional vibrations of the upper holder 6 and the lower holder 7 are attenuated in a relatively short time because the mass of the vibrating portion is smaller than that of the comparative example. Then, after the torsional vibration is attenuated, the main mirror 5 is pressed against the upper holder 6 again by the urging force of the spring 8 to be stationary in a relatively short time, and the occurrence of bounce as in the comparative example is prevented.

  Further, since the main mirror unit 3 of the embodiment includes the upper cushioning material 9 and the lower cushioning material 10, when the main mirror 5 moves relative to the upper holder 6 and the lower holder 7, It is possible to prevent a collision and receive an impact, and it is also possible to prevent the generation of an impact sound due to such an impact.

Further, since the main mirror unit 3 of the embodiment presses the main mirror 5 against the upper holder 6 from the back surface side which is the traveling direction side when the mirror is down, the main mirror unit 3 is moved from the upper holder 6 by the inertial force at the end of the mirror down. It is easy to separate, and it is easy to exhibit the above-described bounce reduction effect.
Here, the bounce of the main mirror 5 is more likely to be a problem when the mirror is down than when the finder image is not generally observed, but according to this embodiment, the bounce when the mirror is down is effective. Can be prevented.

  Further, since the upper cushioning material 9 and the lower cushioning material 10 are both formed using a material having better vibration damping ability than the material of the upper holder 6 and the lower holder 7, the upper holder 6 and the lower holder 7. Can be attenuated early, and the bounce of the main mirror 5 can be further reduced.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes can be made, and these are also within the equivalent scope of the present invention.
(1) The configuration of the movable reflecting mirror is not limited to that of the embodiment, and can be changed as appropriate. For example, in the embodiment, the main mirror is pressed to the upper holder side by a spring provided in the lower holder, but conversely, the main mirror may be pressed from the upper holder side to the lower holder side. Further, the number of stop pins is not limited to one as in the embodiment, and a plurality of stop pins may be provided.
(2) Although the movable reflecting mirror of the embodiment is a main mirror of a camera that is a quick return mirror, the present invention is not limited to this and can be applied to other movable reflecting mirrors. In conjunction with this, it can be applied to sub-mirrors that constitute a movable reflector group together with a main mirror, and can also be applied to uses other than cameras.

It is a figure which shows the structure of the periphery of the main mirror unit for cameras which is an Example of the movable reflecting mirror to which this invention is applied. It is a perspective perspective view of the main mirror unit of FIG. FIG. 3 is a cross-sectional view of the main mirror unit in FIG. It is an external appearance perspective view of the main mirror unit which is a comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mount: 2 Image pick-up part: 3 Main mirror unit: 4 Stop pin: 5 Main mirror: 6 Upper holder: 7 Lower holder: 8 Spring: 9 Upper buffer material: 10 Lower buffer material

Claims (4)

In a movable reflector that moves between a reflection position that reflects a subject light beam and a retraction position that is retreated from the optical path of the subject light beam,
A mirror portion having a reflective surface;
A movable reflecting mirror comprising: a clamping unit that clamps the mirror unit in a non-fixed manner. The movable reflector according to claim 1,
A movable reflector having a buffer member disposed to face at least one surface of the mirror portion. The movable reflector according to claim 1 or 2,
The movable holding mirror is characterized in that the clamping unit includes a pressing unit that presses a surface of the mirror unit on the reflection position side. A photographic optical system;
An imaging surface on which a subject image is formed by the imaging optical system;
In a camera comprising a movable reflecting mirror group provided between the imaging optical system and the imaging surface,
A movable reflector according to any one of claims 1 to 3 is provided on at least a part of the movable reflector group.

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