JPS6118936A - Ttl photometric instrument of camera - Google Patents

Abstract

PURPOSE:To perform photometry with low luminance by forming an assembly of micro reflecting mirrors with special reflection characteristics as the reflecting surface of a submirror and reflecting light which reaches the submirror through the translucent part of a main mirror. CONSTITUTION:Light from a photographic lens 1 is reflected by the main mirror 2 and guided to a viewfinder 3, and the light is transmitted through the translucent part as part of the main mirror and reflected by the submirror 41 to be made incident on a photodetector 6 through a lens 5. The surface of the submirror 41 is formed of micro reflecting mirrors 41a and 41b having special reflection characteristics to guide the transmitted light to the photodetector 6 efficiently. Consequently, photometry with low luminance is performed and the viewfinder is held bright.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a TTL photometry device for a single-lens reflex camera, and in particular to a main mirror for a finder having a semi-transparent section and a light receiving system that transmits light that has passed through the semi-transmissive section. The present invention relates to a TTT and photometry device equipped with a guiding sub-mirror.

(Background of the Invention) FIG. 3 shows the arrangement of an optical system and a photometric device within the body of a single-lens reflex camera. Conventional TTL photometry methods that measure the subject light passing through the photographic lens 1 include partial metering that measures a part of the photographic screen, average metering that measures the average of the photographic screen, and metering that measures both sides of the photographic screen in several ways. There is multi-segment photometry, which divides the image into areas and attempts to obtain appropriate exposure from the photometry output of each area.

In FIG. 3, during photometry, the main mirror 2 reflects the light that has passed through the photographic lens 1 and guides it to the finder 3, and the light that has passed through the partially transmissive part of the main mirror 2 is reflected by the main mirror 2.
The light is reflected by a sub-mirror 41 that is rotatably provided and guided to a light-receiving lens 5 and a light-receiving element 6 for photometry. This main mirror 2 is a flip-up mirror of a single-lens flex camera, etc., and the semi-transparent part of the main mirror 2 is a half-mirror,
It is made of a pinball mirror, etc. The light-receiving lens 5 is arranged in the mirror box of the camera so as to form an image of the subject on the sub-mirror 41'2 onto the light-receiving element 6. The subject image of the sub-mirror 41-L is formed into a 111 image by the light-receiving lens 5 on the light-receiving element 6-1- and is received.

In order to re-image the subject image on the sub-mirror 41 on the light-receiving element 6, for example, there is a method of using a reflecting mirror with a diffusive surface as the sub-mirror 41. FIG. 9 shows an example in which a reflecting mirror with a diffusive surface is used as the sub-mirror 4 of the IJ conventional system. Hereinafter, in order to simplify the explanation, the traveling direction of light will be assumed to be from the light receiving system toward the exit pupil of the photographing lens 1. Region 10 shows the diffusion characteristics when the light beam 9 from the light-receiving lens 5 is diffused by the diffusion surface of the sub-mirror 4, and also shows the intensity distribution of reflected light from the point P where the light beam 9 enters the sub-mirror 4.

The light beam 10' within this diffused region 10 heads toward the exit pupil of the photographing lens 1, but the light beams other than the light beam 10' shown in the shaded area do not reach the light receiving element 6 and become wasted light beams. Therefore, this means that the incident light that has entered from the photographing lens 1 is diffused by the submirror 4 and is reduced, causing the ITY of the light receiving element 6 to decrease.
This indicates that the amount of light entering the area is decreasing. Therefore, in order to increase the light-receiving output of the light-receiving system even a little, it is necessary to increase the transmittance of the semi-transparent part of the main mirror 2, which has the disadvantage that the finder also becomes dark.

(Object of the Invention) An object of the present invention is to solve this drawback and to provide a photometric device that has a large light receiving output and a bright finder.

(Summary of the Invention) The present invention provides a reflective surface of a sub-mirror with special reflection characteristics in order to efficiently receive light that passes through a semi-transparent part of a main mirror and is reflected by a sub-mirror in a TTl or photometry device. The technical point is to form an assembly of micro-reflecting mirrors to focus the subject light from the photographic lens onto the light-receiving system.

(Example) FIGS. 1 to 6 show a first example of the present invention. 1st
The figure shows the sub-mirror 41, photographing lens 1, and photometry system (light-receiving lens 5, light-receiving element 6) of FIG. 3 enlarged for explanation. FIG. 2 G11 shows the photographing lens 1, main mirror 2, sub-mirror 41, and light-receiving system in FIG.
8 is shown to be guided to the exit pupil of the photographic lens 1. FIG. 4 is an explanatory diagram when the light beam reflected by the micro conical mirror 41a shown in FIG. 1 is projected. FIG. 5 is an enlarged perspective view of a part of the submirror 41 shown in FIG.
It is composed of an aggregate of 1a.

In FIG. 1, the micro conical mirror 4 of this submirror 41 is
1a is formed to have an apex 41b at the center, and each of the micro conical mirrors 41a reflects the respective light beams from the light receiving system and guides them to the exit pupil of the photographic lens 1 as shown in FIG. In FIG. 1, the light beams 11 and 12 are used to represent the light beams reflected by the small conical mirror 41a, and part of the light beam 11 from the light receiving system is reflected to the lower surface of the small conical mirror 41a. The light enters the lower part of the exit pupil of the photographic lens 1, and another light beam from the light receiving system is reflected onto the upper surface of the 12th minute conical mirror 41a and enters the upper part of the exit pupil of the photographic lens 1. In this way, the light beam reflected by a portion of the micro conical mirror 41a is guided to the exit pupil of the photographing lens 1 as a light beam 11 and a light beam 12, as shown in FIG. That is, although FIG. 4 shows the projection of light beams 11 and 12 onto the exit pupil of the photographing lens l, representing the light beams shown in FIG. It can be seen that the light beam from the light receiving system is reflected by the surface mirror 41a and guided to the entire exit pupil of the photographing lens 1, as shown by the dashed line (the hatched part rotated around the center of the exit pupil).

Therefore, even if we take only one microconical mirror 41a, it can be seen that the light beam reflected from it is guided to the entire exit pupil of the photographic lens 1. As mentioned above, Zabmirror 4
Each of the micro conical mirrors 41a of 1 is formed to have a reflection characteristic of reflecting a projected image of the entrance pupil of the light receiving lens 5 so as to include the exit pupil of the photographing lens 1, and is formed on the entire surface of the submirror 41. All of the micro conical mirrors 41a have the above-mentioned characteristics.

In FIG. 2, the luminous flux 13 (or luminous flux +4) is the luminous flux 11.12 reflected by the micro conical mirror 41a as described above.
It is a collection of etc. Even if we consider the case that part of this light 14 is reflected at the upper point Q of the submirror 41, the micro conical mirror 41a of the submirror 41 directs the principal light t6f l 41 of the light flux 14 from the light receiving lens 5 to the exit pupil of the photographing lens 1. A reflecting surface is formed such that the light passes through the center point R of A1. In other words, the 1
The chief ray of the light flux from the j111 optical system passes through the center point R of the 10 power/1 power pupil of the photographing lens.

In this way, the reflection characteristics of the micro conical mirror 41a are achieved at any point on the submirror 4I. submirror
41 as a whole is configured to have a condensing characteristic to condense the light flux of the exit pupil onto the light receiving element 6 of the light receiving system.

Therefore, if the surface of the sub-mirror 41 is formed by a combination of micro-conical mirrors 41a as shown in FIG. Since the A-plane mirror 41a efficiently reflects light to the light receiving system, the light collecting ability of the sub-mirror 41 is greatly improved. Even if the ratio is lower than the submirror 41, the subject light incident on the light receiving element 6
Since the light is sufficiently focused, photometry becomes possible.

FIG. 6 shows an example of a light-receiving element 6 for multi-division photometry, and the light-receiving element 6 is divided into five segments 61-65. This light-receiving element 6 is compatible with both sides of the photographing surface, and the segments 61 to 65 of the light-receiving element 6 divide the photographing screen into multiple sections 41.
There will be 11 lights. Each of the micro conical mirrors 41a of the submirror 41 is formed so as to uniformly condense the incident light from the photographing lens 1 onto the light receiving element 6, so that multi-segment photometry using the multi-segment element shown in FIG. 6 is possible. In this case, the photometric output of each divided photographic screen can be obtained appropriately.

Although the shape of the micro conical mirror 4]a shown in FIG. 5 is a conical surface, it may also have a concave or convex square peg C curve, a 171 plane, etc.
Its shape may be determined to be an optimal shape depending on the configuration of the photographing lens 1 and the light receiving lens 5.

7 and 8 show a second embodiment of the present invention, and FIGS. 7 and 8 show an improvement of the submirror 41 of the first embodiment. If the snow mirror 41 is configured as in the first embodiment, photometry can be performed most efficiently, but in the first embodiment, the micro conical mirror 41
Since the orientation of 1a is different for each submirror, manufacturing of the submirror becomes very difficult. Therefore, in order to facilitate the manufacture of the sub-mirror, the structure may be changed as described below.

As shown in FIGS. 7 and 8, the submirror 42 is divided into several blocks, and each block has a micro conical mirror 41a.
are formed in the same direction for each block, that is, in the same shape so as to have the same reflection characteristics. In FIG. 7, the entire surface of the submirror 42ζ is divided into 15 blocks, and the direction of the micro conical mirror 41a is determined for each block. This micro conical mirror 41a has the same feature as the first embodiment.
il. Since the direction of the microcircle 11 and 41a is determined for each block, the direction of each block is determined so that the light flux from the exit pupil of the photographic lens 1 is sent to the light receiving system most efficiently (condensing) as shown in FIG. It is decided to do so.

Figures 8 (a) to (d) show the shape of each block; (a) and (b) are triangular and hexagonal blocks, respectively, and (C) is the photometry at the center of the shooting screen. In cases where precision is particularly required, the size of the blocks is different between the central part and the peripheral part, and (d) shows an example in which the blocks are arranged radially. In this way, by changing the shape of each block, it is possible to make it compatible with the photometry mode of the tilt photometer, or to reduce the number of block divisions for photometers that do not require high photometry accuracy.

Therefore, as shown in FIGS. 7 and 8, the microcircle 11 and the top mirror 41
, a in a fixed direction for each block, the fabrication of the submirror 42 becomes simple, and the shape of each block can be determined according to the specifications required for the photometric device, as shown in FIG. .

(Effects of the Invention) As described above, according to the present invention, the assembly of minute reflecting mirrors can efficiently guide the subject light from the photographing lens to the light receiving means, so that the light receiving output of the light receiving means is increased and the light receiving output is reduced. It is possible to measure the brightness of the subject. Furthermore, since the assembly of microreflectors can efficiently collect the subject light, the viewfinder can be made brighter by lowering the transmittance of the semi-transparent part of the main mirror.

[Brief explanation of drawings]

1 to 6 show a first embodiment of the present invention, FIG. 1 is an enlarged view of a part of the submirror with a microcircle & FIG. 3 is a layout diagram of the optical system and photometry device inside the body of a single-lens reflex camera, and FIG. 4 is an explanatory diagram when the light beam reflected by the micro conical mirror shown in FIG. 1 is projected. Fig. 5 is an enlarged perspective view of a part of the submirror shown in Fig. 1, and Fig. 6 is a diagram showing an example of a multi-segment photometer. Fig. 7 and Fig. 8 show a second embodiment of the present invention. 7 and 8 are improved views showing improvements to the sub-mirror of the first embodiment. FIG. 9 shows a layout diagram of a conventional TTL photometer. (Explanation of symbols of main parts) ■...Photographing lens 2...Main mirror 4; 41; 42...Sub mirror 4a...Micro conical mirror Applicant: Takashi Watanabe, Agent, Nippon Kogaku Kogyo Co., Ltd.■2 C-ba, Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claims] A main mirror that reflects subject light to a finder system and has a semi-transparent section through which the subject light can pass, and a light receiving means in a mirror box that receives the subject light that has passed through the semi-transmissive section. In the TTL photometry device for a camera, the camera has a sub-mirror that is rotatably provided on the main mirror, and the sub-mirror is formed by an assembly of micro-reflecting mirrors, and the entrance pupil of the light-receiving lens of the light-receiving means is set to the Each of the micro-reflecting mirrors has a reflection characteristic such that when reflected by the micro-reflecting mirror and projected onto the exit pupil of the photographing lens, the projected image of the entrance pupil of the light-receiving lens almost encompasses the exit pupil of the photographing lens. A TTL photometry device for a camera, comprising: