JPH1124155A - Display illumination device in viewfinder - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To be mountable in a narrow space in a viewfinder and to eliminate vignetting on a display surface. SOLUTION: A black display surface 2 on which characters or graphics are displayed in a transparent portion is formed by printing on a protective glass 3 parallel to the reticle 1 between a reticle 1 and a finder optical system 10 of the single-lens reflex camera. Then, a light guide 4 is provided on the lower surface of the protective glass 3 in parallel with the display surface 2, and a light source 5 such as a green LED is provided on the left end side. The light guide 4 is formed with a light guide 4 b for guiding the light from the light source 5 in parallel with the display surface 2 and a boundary inclined surface 4 a for directing the guided light toward the display surface 2. A large number of reflection surfaces and non-reflection surfaces are alternately formed in a step-like manner on the display surface 4a so that the light rays reflected on each reflection surface can uniformly illuminate the display surface 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finder which is provided in a small space in a finder of a camera and illuminates, as necessary, a display surface on which a character or a figure which can be viewed is displayed on a part of the finder. The present invention relates to a display lighting device.

[0002]

2. Description of the Related Art In this type of display illuminating device in a finder, the display surface cannot be directly illuminated by a light source such as a light emitting diode (LED) or a small lamp in a space. Therefore, light from the light source is usually displayed by a light guide. It is necessary to guide to the surface.

FIG. 5 is an explanatory view showing an example of a conventional display illumination device in a finder. A transparent protective glass 3 having a display surface 2 displaying characters or graphics is mounted between the reticle 1 and the finder optical system 10 of the single-lens reflex camera in parallel with the reticle 1, and a 45 ° A light guide 4 composed of a rod prism having a reflection surface 4c is provided in parallel with the protective glass 3, and a light source 5 is disposed at the tip thereof. Light from the light source 5 is guided to the right by the light guide 4 and is reflected by the reflection surface 4c. The display surface 2 is illuminated by being reflected upward by 90 °, and the finder optical system 1 is illuminated.
From 0, it can be seen with the focal plane.

[0004]

However, in such a conventional display illuminating device in a finder, the light emitted from the light source 5 and guided to the right by the light guide 4 is reflected by the 45 ° reflecting surface 4c. The light guide 4 and the display surface 2 are reflected upward to illuminate the display surface 2.
Taking into account the relative displacement of the illumination light, the width D1 of the illumination light is required to be wider than the width D of the display surface 2. Therefore, the thickness of the light guide 4 must be the same as the width D1 of the illumination light, and there is a possibility that the light guide 4 cannot be mounted in a small space in the finder.

If the thickness of the light guide 4 is smaller than the width D of the display surface 2, a part of characters or figures on the display surface 2 is not illuminated, resulting in vignetting. The present invention has been made in view of the above points, and an object of the present invention is to provide a display illuminating device in a finder which can be mounted in a small space between a reticle and a finder optical system of a camera and does not cause vignetting on a display surface. With the goal.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a light guide section for guiding a light beam from a light source in parallel with a display surface on which characters or graphics are displayed, and a light guide section provided by the light guide section. In a finder display illumination device provided with a light guide having a boundary inclined surface for directing the reflected light beam toward the display surface, the boundary inclined surface is divided into small steps in a stepwise manner at a predetermined interval orthogonal to the light passing direction. By alternately forming a reflecting surface for reflecting light rays from the light source in the direction of the display surface and a non-reflection surface substantially parallel to the display surface, the display in the finder is reduced in thickness of the light guide. A lighting device is provided. In the display illuminating device in the finder, at least the reflection surface of the boundary inclined surface may be a diffusion surface.

The display illuminating device in the finder according to the present invention can reduce the thickness of the light guide for guiding light rays from the light source to the display surface, and sufficiently illuminate the display surface without vignetting. And can be easily stored in a small space in the viewfinder.

[0008]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a sectional side view showing a main part of an embodiment of the present invention, FIG.
Is a side sectional view showing an enlarged part of the light guide,
FIG. 4 is an optical path diagram of a finder optical system of a single-lens reflex camera embodying the present invention. In these figures, parts corresponding to FIG. 5 are denoted by the same reference numerals.

First, an outline of a finder optical system of a single-lens reflex camera embodying the present invention will be described with reference to FIG. An image-forming light beam that has passed through a photographic lens (not shown), is reflected by a movable reflecting mirror of the camera body, and forms an image on a focusing screen 1 is collected by a condenser lens 11 of a finder optical system 10 and is reflected at right angles by a reflecting mirror 12 in the finder. And relay lens 1
3 forms an aerial image, and the aerial image is magnified by the eyepiece 14 and viewed.

As shown in FIG. 1, a finder display illumination device mounted between the reticle 1 and the finder optical system 10 has a substrate 6 for supporting the reticle on the reticle 1 as shown in FIG.
A protective glass 3 formed by printing a black display surface 2 on which characters or graphics (indicated by a strobe mark in FIG. 2) are displayed by a transparent portion is provided in parallel with the reticle 1.

A lower surface of the protective glass 3 has a boundary inclined surface 4a inclined at, for example, approximately 30 degrees with respect to the display surface 2 at a portion facing the display surface 2, and the display surface is leftward away from the finder optical path. A light guide 4 having a light guide portion 4b extending in parallel with the light guide 4 is provided, and a light source 5 made of, for example, a green LED or a small light bulb is disposed on the left end side of the light guide 4. On the boundary inclined surface 4a formed at the right end of the light guide 4, as shown in the enlarged view of FIG. Are alternately formed, and the angle θ formed by the reflection surface 4c with respect to the horizontal plane is set to approximately 45 ° so that the light rays reflected by each reflection surface 4c can illuminate the display surface 2 evenly.

Strictly speaking, the angle θ is set slightly smaller than 45 °, and the light reflected by each reflecting surface 4c passes through the transparent portion of the display surface 2 and then passes through the finder optical system 10 to the photographer. It is preferable to be able to enter the eye of the subject. In this way, the light reflected on the reflection surface 4c reaches the eyes,
Although the reflected light does not reach from the non-reflection surface 4d, the display surface 2 is almost uniformly illuminated because the light source 5 has a certain size.

However, if the light source 5 is very close to a point light source, the illumination of the display surface may be slightly uneven. In this case, at least the reflection surface 4 of the boundary inclined surface 4a is used.
It is preferable that c is a diffusion surface. Also, the light guide 4 may be a slightly curved surface instead of a flat surface.
By appropriately selecting the refractive index, it is possible to use the reflection surface 4c as a total reflection surface and omit sputtering on the boundary inclined surface 4a.

By the way, the strobe mark on the display surface 2 shown in FIG. 2 is turned on when charging is completed at the time of strobe shooting to indicate that shooting is possible, and flashes at, for example, 8 Hz after the strobe is turned on after the shutter release to properly flash. This indicates that dimming has been performed, and does not light when the strobe is not used. The display on the display surface 2 is not limited to this, and any character or figure may be used.

[0015]

As described above, the display illuminating device in a finder according to the present invention guides a light beam from a light source in parallel to a display surface, and then steps the inclined slope of the boundary of the light guide toward the display surface. Even if the thickness of the light guide is reduced by gently tilting the boundary slope surface, the entire display surface can be illuminated uniformly, and the viewfinder is narrowed down. It can be easily stored in a small space.

In the above-described display illuminating device in a finder, if at least the reflection surface of the boundary inclined surface is a diffusion surface, the display surface can be almost uniformly illuminated even when the light source is extremely small and close to a point light source.

[Brief description of the drawings]

FIG. 1 is a sectional side view of a main part showing an embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is an enlarged side sectional view showing a part of the light guide.

FIG. 4 is an optical path diagram of a finder optical system of a single-lens reflex camera embodying the present invention.

FIG. 5 is an explanatory view showing an example of a conventional display illumination device in a finder.

[Explanation of symbols]

 1: Focusing plate 2: Display surface 4: Light guide 4a: Boundary inclined surface 4c: Reflective surface 4d: Non-reflective surface 5: Light source 10: Viewfinder optical system 12: Reflector in viewfinder 13: Relay lens 14: Eyepiece

Claims (2)

[Claims] 1. A light guide section for guiding light rays from a light source in parallel with a display surface on which characters or graphics are displayed, and a boundary inclined surface for directing light rays guided by the light guide sections toward the display surface. In the finder display illumination device provided with a light guide, the boundary inclined surface is finely divided into stairs at predetermined intervals perpendicular to the light passing direction, and the light from the light source is reflected in the direction of the display surface. A display illuminating device in a finder, wherein a thickness of the light guide is reduced by alternately forming a reflecting surface to be formed and a non-reflecting surface substantially parallel to the display surface. 2. The display illumination device according to claim 1, wherein at least the reflection surface of the boundary inclined surface is a diffusion surface.