JPH0616948U - Interchangeable viewfinder device for single-lens reflex camera - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a replaceable finder device that is lightweight and easy to carry, and to provide a replaceable finder device that is not easily affected by dust. An interchangeable viewfinder device for a single-lens reflex camera that can be attached to and detached from a camera body, the hollow pentamirror having an opening facing a focusing plate of the camera body, and the hollow pentamirror. An interchangeable finder device having a mirror holder, and a transparent protective cover member provided in the opening of the hollow pentamirror.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an interchangeable viewfinder device for a single-lens reflex camera.

[0002]

[Prior art and its problems]

 As shown in FIG. 4, the viewfinder device of a single-lens reflex camera forms an image of a subject, which is transmitted through a taking lens (not shown) and reflected by a quick return mirror (first mirror) 6, on a focusing plate 1. , This is reflected by the roof surface 3 at the top of the pentaprism (pentagonal roof prism) 2 and the third reflecting surface 4 at the front, and then led to the loupe lens (eyepiece) 5, where there is no vertical or horizontal reversal of the subject. It is designed to capture images.

The conventional finder device having such a structure has a problem that the processing cost of the pentaprism is high and heavy. Therefore, when the finder device is configured as an exchangeable finder device, it is heavy and inconvenient to carry. It becomes a finder device.

[0004]

[The purpose of the device]

 The present invention has been made in view of the above problems, and an object thereof is to provide a replaceable finder device which is lightweight and easy to carry. Another object of the present invention is to provide a replaceable finder device that is not easily affected by dust.

[0005]

[Outline of the device]

 The present invention that achieves the above object is therefore an interchangeable viewfinder device for a single-lens reflex camera that can be attached to and detached from a camera body, and a cavity-type pentamirror having an opening facing the focus plate of the camera body. It is characterized in that it has a mirror holder to be coupled with the cavity type pentamirror, and that a transparent protective cover member is provided in the opening of the cavity type pentamirror. The transparent protective cover member is preferably made of a material having a coefficient of thermal expansion substantially equal to that of the hollow pentamirror, and further, a packing member for absorbing thermal deformation is provided between the hollow pentamirror and the transparent protective cover member. It is also possible to intervene.

[0006]

【Example】

 The present invention will be described below with reference to the illustrated embodiments. Prior to the description of the exchangeable finder device of the present invention, a fixed finder device as a basis thereof will be described with reference to FIG. This finder device was proposed by the present applicant, and the parts corresponding to the roof surface 3 and the third reflecting surface 4 of the pentaprism 2 shown in FIG. 4 are formed as reflecting mirrors, and other parts are omitted. It has a cavity-type pentamirror 10 having a shape.

The hollow pentamirror 10 is fixed to a camera body (not shown) via a mirror holder 20 ′, has a roof surface on the upper left and right of the inner surface thereof, and a third reflecting surface on the front, and has a focus plate. An entrance opening (opening) 23 is provided at a position opposed to 1. The cavity type pentagonal mirror 10 is externally configured such that the left and right lower side surfaces 13 and the rear surface 14 are formed as substantially vertical surfaces, and the third reflection surface portion is formed as an inclined surface 15 protruding forward toward the upper part. Has been done. The mirror holder 20 'has a recess 21 into which the lower part of the hollow penta mirror 10 is fitted, and a flange 22 for fixing it to the camera body. The flange 22 is provided with a fixing screw hole 22a. . The concave portion 21 is composed of left and right inner side surfaces, a back surface and an inclined surface corresponding to the side surface 13, the back surface 14 and the inclined surface 15 of the cavity-type pentamirror 10. The mirror holder 20 ′ also has a step portion 26 ′ that determines the insertion depth of the hollow penta mirror 10 at the bottom thereof, and the entrance opening 23 of the hollow penta mirror 10 is provided at the center of the step portion 26 ′. Has a through opening 25 corresponding to.

Therefore, according to the fixed finder device having the hollow pentamirror, since the glass part of the conventional pentaprism is hollow, it is lightweight, and the manufacturing cost is reduced and the cost is reduced. Can also be expected.

Next, a first embodiment according to the present invention will be described. FIG. 1 is a side sectional view showing an interchangeable finder device for a single lens reflex camera according to the present invention. In the figure, the mirror holder 20 is slightly different in shape from the mirror holder 20 'described in FIG. 3 in order to obtain an interchangeable finder device for the camera body, but has the same basic function.

The cavity pentamirror 10 has substantially the same structure as that described with reference to FIG. 3, and has a roof surface 11 and a third reflecting surface 12 on its inner surface. Apparently, the left and right vertical side surfaces 13 (see FIG. 3), the same vertical surface back surface 14 and the front inclined surface 15 are provided, and the incident opening for receiving the incident light from the focusing plate 1 is formed. We have 23. The mirror holder 20 that receives the hollow pentamirror 10 has a recess 21 and a step 26, similar to the mirror holder 20 ′ described in FIG. 3, and the center of the step 26 has the entrance opening 23. It has a corresponding passage opening 25. Both the cavity type pentamirror 10 and the mirror holder 20 are made of a synthetic resin material or the like.

A transparent protective cover 30 for preventing dust from entering through the entrance opening 23 is adhered or fitted to the entrance opening 23 of the cavity pentamirror 10. The transparent protective cover 30 is made of a synthetic resin material or the like having a thermal expansion coefficient equal to that of the hollow pentamirror 10. For example, when the transparent protective cover is made of a material having a different coefficient of thermal expansion such as glass, the transparent protective cover adhered to the entrance aperture 23 expands with a coefficient of thermal expansion different from that of the cavity-type penta mirror 10. There is a risk of changing the flatness and the angle of the surface 11 and the third reflecting surface 12. In particular, the change in the angle formed by the roof surface 11 is a fatal defect. Since the transparent protective cover 30 of this embodiment is made of a material having the same coefficient of thermal expansion as the cavity type pentamirror 10 as described above, even if the cavity type pentamirror 10 is thermally expanded, it is expanded by the same coefficient of thermal expansion. Therefore, there is no fear that the hollow pentamirror 10 will be deformed.

The lower end of the penta roof 17 arranged outside the hollow penta mirror 10 is bonded or fitted to the outer peripheral edge of the mirror holder 20. As a result, the hollow penta-mirror 10, the mirror holder 20, the penta roof 17, the loupe lens 5 and the viewfinder eyepiece 18 are configured as an interchangeable viewfinder device that is integrally attached to and detached from the camera body.

In the present interchangeable finder device having such a configuration, the hollow pentamirror 10 and the mirror holder 20 are both hollow and made of a synthetic resin material or the like, so that the weight is reduced and the portable finder device is portable. Is made easier. Further, if the penta roof 17 is also made of a light material such as a synthetic resin material, the weight of the replaceable finder device can be further reduced.

Further, as shown in FIG. 2, if the cavity type penta mirror 10 and the transparent protective cover 30 are combined with the packing 31 interposed, the thermal expansion of the cavity type penta mirror 10 and the transparent protective cover 30. Since it is possible to absorb the heat, it is possible to more reliably prevent thermal deformation of the hollow type pentamirror 10.

[0015]

[Effect of device]

 As described above, according to the present invention, it is possible to realize a lightweight and replaceable finder device that is not affected by dust. If the transparent protective cover member is made of a material having a thermal expansion coefficient substantially equal to that of the hollow penta mirror, the hollow penta mirror and the transparent protective cover member expand with substantially equal thermal expansion coefficients, so that the deformation of the hollow penta mirror is performed. It is possible to eliminate the risk of causing. In addition, if a packing member for absorbing thermal deformation is interposed between the pentamirror and the transparent protective cover member, this packing member can absorb the thermal expansion of the cavity type pentamirror and the transparent protective cover. It is possible to more reliably prevent thermal deformation of the pentamirror.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of an interchangeable finder device for a single-lens reflex camera according to the present invention.

FIG. 2 is a side sectional view showing a second embodiment of an interchangeable finder device for a single-lens reflex camera according to the present invention.

FIG. 3 is a perspective view showing a fixed viewfinder device proposed by the present applicant, which is the basis of the present invention.

FIG. 4 is a side sectional view showing a conventional finder device using a pentaprism.

[Explanation of symbols]

 5 Loupe lens 10 Cavity type pentamirror 11 Roof surface 12 Third reflection surface 13 Side surface 14 Back surface 15 Slope 17 Penta roof 18 Finder eyepiece 20 Mirror holder 21 Recess 23 Entrance opening 25 Passage opening 26 Step section 30 Transparent protection cover 31 Packing

Claims (3)

[Scope of utility model registration request] 1. A replaceable viewfinder device for a single-lens reflex camera, which is attachable to and detachable from a camera body, wherein a hollow pentamirror provided with an opening facing a focusing plate of the camera body, and the hollow pentamirror. An interchangeable viewfinder device for a single-lens reflex camera, comprising a mirror holder to be coupled, and a transparent protective cover member provided in the opening of the hollow pentamirror. 2. The interchangeable viewfinder device for a single-lens reflex camera according to claim 1, wherein the transparent protective cover member is made of a material having a thermal expansion coefficient substantially equal to that of the hollow pentamirror. 3. The interchangeable viewfinder device for a single-lens reflex camera according to claim 1, further comprising a packing member for absorbing thermal deformation interposed between the hollow pentamirror and the transparent protective cover member.