JPH11271847A - Finder for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a finder for a camera capable of sufficiently eliminating irregular reflections so that restrictions in the design of a finder optical system is swept away independently of its constitution. SOLUTION: A finder optical system of a camera is equipped with a prism 52, and an irregular reflection light beam L2 is generated on the edge surfaces 52c and 52d of the prism 52. By disposing a louver member 54 between the prism 52 and an ocular 56, an irregular reflection light beam is eliminated and the occurrence of ghost is prevented. The louver member 54 is formed by disposing many slender belt-like light shielding films 58 in parallel with each other by leaving a space between them, and it is disposed in a finder optical path so that the extended surface of the light shielding film 58 may be in parallel with an optical axis L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera viewfinder.

[0002]

2. Description of the Related Art Irregularly reflected light rays may be generated inside a viewfinder optical system of a camera. An irregularly reflected light beam is a light beam that is reflected on a surface that should not reflect light and deteriorates the visibility of a subject image in a finder. For example, light rays that are reflected on the inner wall surface of the lens barrel or case of the finder optical system and enter the eye are irregularly reflected light rays. The outer peripheral surface of the lens and the side surface of the prism surface extending parallel to the optical axis (that is, the non-optical surface that is neither the input / output surface nor the original reflection surface) are called edge surfaces. However, light that is incident on the edge surfaces of the lenses and prisms and reflected therefrom also becomes an irregularly reflected light beam, which may deteriorate the visibility of the subject image in the viewfinder.

[0003] Irregularly reflected light from the inner surface of the lens barrel or the case, or irregularly reflected light from the edge of the lens or prism, as the angle of incidence at which the light is incident on those surfaces becomes smaller, the reflection becomes stronger and the harmfulness becomes worse. Increase. If the reflection is strong, some countermeasures are necessary.For example, with regard to the inner surface of the lens barrel or case, a number of grooves extending in the direction perpendicular to the optical axis are formed, or matte black paint is applied. , The reflection can be weakened. The edge surface of the lens has a small dimension in the optical axis direction, and the vicinity of the edge surface is covered by a lens holding frame or the like, so that light rarely enters the edge surface at a small incident angle, and harmful reflection is caused. Is unlikely to occur. On the other hand, not only the edge surface of the prism has a large physical dimension in the optical axis direction, but also the optical path is bent in the prism, so that the optical equivalent dimension in the optical axis direction is further increased. Therefore, light is likely to enter the edge surface of the prism at an extremely shallow angle, and a ghost or the like is likely to appear due to generation of a strong illegally reflected light beam.

[0004]

Conventionally, when designing a finder optical system, the occurrence of a ghost or the like is prevented by devising a design such as avoiding disposing a prism immediately before an eyepiece. But that was a major design constraint. The present invention has been devised in view of the above circumstances, and an object of the present invention is to be able to satisfactorily eliminate irregular reflection regardless of the configuration of a finder optical system of a camera, and thus to provide a finder optical system. An object of the present invention is to provide a camera finder that eliminates design restrictions.

[0005]

In order to achieve the above object, a finder for a camera according to the present invention comprises a louver member formed by arranging a number of elongated strip-shaped light-shielding films in parallel with each other at intervals. It is characterized in that the light-shielding film is disposed in the finder optical path such that the extending surface of the light-shielding film is parallel to the optical axis, so that illegally reflected light rays in the finder optical path are eliminated. Further, the invention is characterized in that the louver member is constituted by a laminate in which transparent material layers and light-shielding film layers are alternately laminated. Further, in the invention, it is preferable that the finder includes a prism and an eyepiece, and the louver member is disposed between the prism and the eyepiece. Further, according to the present invention, the prism has a flat edge surface, and the louver member is disposed such that an extending surface of the light shielding film is parallel to the edge surface, so that the light is reflected on the edge surface. The illegally reflected light beam is eliminated by the light shielding film.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a camera viewfinder according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a plan view of a camera provided with a finder according to an embodiment of the present invention, FIG. 2 is a front view of the camera of FIG.
3 is a sectional plan view of the finder, FIG. 4 is an exploded perspective view of the finder, FIG. 5 is an explanatory view of a prism of the finder, and FIG. 6 is a cross-sectional side view in which main parts of the finder are enlarged.

The camera 10 is a horizontally long compact camera, has a photographing lens 12 having a zoom function on the front, and has a finder block 14, an auto focus (AF) block 16, an AF auxiliary light emitting block 18,
And a photometric block 20. Further, a viewfinder window 22 and an AF
A window 24, an AF auxiliary light projection window 26, a photometry window 28, and a flash window 30 are formed.

As shown in FIGS. 3 and 4, the finder 40 is configured as a finder block 14 and then assembled to the body of the camera 10. The finder block 14 has a plastic case 42 in which various optical elements are incorporated. On the front side (upper side in FIG. 3) of the case 42, a finder imaging lens 44 including first to third lens groups 44a, 44b, 44c is provided. The first lens group 44 a among these lens groups is fixed to the case 42. The second lens group 44b and the third lens group 44c are movable along the optical axis L, and a zoom function is obtained by moving them. A roof mirror 46 is provided behind the finder imaging lens 44, and the optical axis L is bent at a right angle by the roof mirror 46 to reach a focusing screen 48. The reticle 48 is formed by using a flat surface 48a of the condenser lens as a focus surface. The roof mirror 46 and the focusing screen (condenser lens) 48 form vertical, horizontal, and right normal images on a focus surface 48a.

A viewing frame 50 is provided behind the focusing screen 48 in the light traveling direction, and a pentagonal prism 52 is further provided behind the viewing frame 50. The pentagonal prism 52 is a pentagonal prism, and the optical axis L is bent twice inside the pentagonal prism 52.
Incidentally, the pentaprism used in many single-lens reflex cameras is exactly what is called a pentagonal roof prism, and is a pentagonal prism with a roof surface incorporated therein. The pentagonal prism 52 used here does not have a roof surface. In the following description, the pentagonal prism 52 will be simply referred to as a prism. The prism 52 has a light-incident surface 52a facing right in FIG.
And an emission surface 52b facing downward (to the rear of the camera) in FIG.
And The light incident from the incident surface 52a is reflected from the two reflecting surfaces of the prism 52 and then exits from the exit surface 52b.

A louver member 54 is provided so as to be in contact with the exit surface 52b of the prism 52, which will be described in more detail later. An eyepiece 56 is provided behind the louver member 54, and a user of the camera approaches the eyepiece 56 and looks into the viewfinder 40. The finder imaging lens 44 is interlocked with the photographing lens 10, and forms the same image as the image captured on the film on the focusing surface 48 a of the reticle 48. By observing the image on the focus surface 48a reflected twice by the prism 52 through the eyepiece lens 56, the photographed image can be visually recognized by the viewfinder 40.

However, in the prism 52, there is a possibility that an illegally reflected light beam is generated. That is, the upper surface 52c and the lower surface 52d of the prism 52 are planes parallel to each other, and extend parallel to the optical axis L. The upper surface 52c and the lower surface 52d are non-optical surfaces that are neither incident / outgoing surfaces nor original reflecting surfaces, and are generally called edge surfaces. Since the optical axis L is bent twice inside the prism 52, the optically equivalent shape of the prism 52 when the optical axis L is developed in a straight line is as shown by a solid line and a dashed line in FIG. become. As can be seen from FIG. 5, the upper and lower surfaces, which are the edge surfaces of the prism 52, have not only a considerably large physical dimension but also an optically equivalent dimension larger than that (indicated by LO in the figure). Therefore FIG.
As shown in FIG.
Since the light beam L1 from the focusing screen 48 is incident on d at a very faint angle, a strong irregularly reflected light beam L2 is generated. If the light beam L2 is directly incident on the eye like the light beam L3, it causes a ghost.

In the present invention, the louver member 54 suitably prevents the ghost from deteriorating the visibility of the subject image in the finder. FIG.
As shown in (1), the louver member 54 is formed by arranging a number of elongated strip-shaped light shielding films 58 in parallel with each other at intervals. In particular, in this embodiment, the louver member 54 is formed of a laminate in which transparent material layers 60 and light-shielding film layers 58 are alternately laminated. That is, the transparent material layer 6
On one side of a transparent plastic sheet having a thickness of 0,
By forming a block by laminating a plurality of layers having a light-shielding film thereon, and forming a block, and slicing the block along a plane perpendicular to the extending surface of the sheet, a plate-shaped block is formed. The louver member 54 is used.

By disposing the louver member 54 thus formed in the finder optical path so that the extending surface of the light-shielding film 58 is parallel to the optical axis L, it is possible to eliminate illegally reflected light rays in the finder optical path. I have to. More specifically, as shown in FIG. 6, the louver member 54 is disposed between the prism 52 and the eyepiece 56, and the extending surface of the light-shielding film 58 of the louver member 54 is By disposing the louver member 54 so as to be parallel to the upper surface 52c and the lower surface 52d, which are surfaces,
The illegally reflected light beam L2 reflected on the upper surface 52c and the lower surface 52d of the prism 52 is excluded by the light shielding film 58 so as not to enter the eye looking into the finder 40. As a result, the ghost does not enter the eyes, and the deterioration of the visibility of the subject image in the viewfinder 40 is completely prevented. On the other hand, the subject image on the focusing screen 48 can be clearly observed without being greatly affected by arranging the louver member 54 at a certain distance from the focus plane. The louver member 54 can be configured in various ways other than those described above. For example, a configuration in which a tape-shaped light-shielding film is stretched on a frame body is also possible.

[0014]

As described above, according to the present invention,
In a finder of a camera, a louver member formed by arranging a number of elongated strip-shaped light shielding films in parallel with each other at intervals is disposed in a finder optical path such that an extending surface of the light shielding film is parallel to an optical axis. The finder optical path is provided to eliminate the irregularly reflected light rays. Therefore, illegally reflected light rays generated inside the finder optical system are eliminated by the louver member, and deterioration of the visibility of the subject image in the finder is suitably prevented.

[Brief description of the drawings]

FIG. 1 is a top view of a camera provided with a viewfinder according to an embodiment of the present invention.

FIG. 2 is a front view of the camera of FIG.

FIG. 3 is a sectional plan view of a finder.

FIG. 4 is an exploded perspective view of the finder.

FIG. 5 is an explanatory diagram of a prism of a finder.

FIG. 6 is an enlarged sectional side view of a main part of the finder.

[Explanation of symbols]

 Reference Signs List 10 camera 12 finder block 40 finder 52 pentagonal prism 54 louver member 56 eyepiece 58 light shielding film

Claims (4)

[Claims] 1. A viewfinder for a camera, comprising: a louver member formed by arranging a number of elongated strip-shaped light-shielding films in parallel with each other at intervals so that an extending surface of the light-shielding film is parallel to an optical axis. A finder for a camera, wherein the finder is disposed in a finder optical path to eliminate illegally reflected light rays in the finder optical path. 2. The louver member according to claim 1, wherein the louver member comprises a laminate in which transparent material layers and light-shielding film layers are alternately laminated.
Viewfinder for the camera described. 3. The camera viewfinder according to claim 1, wherein said viewfinder includes a prism and an eyepiece, and said louver member is disposed between said prism and said eyepiece. 4. The prism has a flat edge surface,
4. The light-shielding film according to claim 3, wherein the louver member is disposed such that an extending surface of the light-shielding film is parallel to the edge surface, so that an illegally reflected light beam reflected on the edge surface is eliminated by the light-shielding film. Camera viewfinder.