JPH063517B2 - Camera TTL metering device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a TTL photometric device for a single-lens reflex camera, and more particularly to a light receiving system for light passing through the semi-transmissive part of a main mirror for a finder having a semi-transmissive part. The present invention relates to a TTL photometric device having a guiding sub-mirror.

(Background of the Invention) FIG. 3 shows an arrangement of an optical system and a photometric device in a body of a single-lens reflex camera. The conventional TTL photometry device for photometry of the subject light passing through the taking lens 1 includes a partial photometry for measuring a part of the photographing screen, an average photometry for uniformly measuring the photographing screen, and some There is multi-divisional metering that divides into areas and obtains proper exposure from the metering output of each part.

In FIG. 3, at the time of photometry, the light that has passed through the taking lens 1 is reflected by the main mirror 2 to be guided to the finder 3, and is provided rotatably on the optical mirror 2 that has passed through a semi-transparent portion of the main mirror 2. The reflected light is reflected by the sub-mirror 41 and guided to the light receiving lens 5 and the light receiving element 6 for photometry. The main mirror 2 is a flip-up mirror or the like of a single-lens reflex camera, and the semi-transmissive portion of the main mirror 2 is formed of a half mirror, a pinhole mirror, or the like. The light receiving lens 5 is
It is arranged in the mirror box of the camera so that the image of the covering body on the sub mirror 41 is formed on the light receiving element 6. The subject image on the sub mirror 41 is re-imaged on the light receiving element 6 by the light receiving lens 5 and 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 having a diffusion surface as the sub mirror 41. FIG. 9 shows an example in which a reflecting mirror having a diffusing surface is used as the conventional sub mirror 4. Hereinafter, in order to simplify the explanation, the direction of light travels from the light receiving system toward the taking lens 1
Take in the direction of the exit pupil of. A region 10 shows a diffusion characteristic when the light beam 9 from the light receiving lens 5 is diffused on the diffusion surface of the sub mirror 4, and also shows an intensity distribution of the reflected light from the point P where the light beam 9 enters the sub mirror 4. The light flux 10 ′ in the diffused region 10 is directed to the exit pupil of the taking lens 1, but the light flux indicated by the shaded area other than the light flux 10 ′ does not reach the light receiving element 6 and becomes a useless light flux. Therefore, this means that the incident light coming from the taking lens 1 is diffused by the sub-mirror 4 and is reduced, and the light taken in by the light receiving element 6 is reduced. Therefore, in order to raise the light receiving output of the light receiving system as much as possible, the transmissivity of the semi-transmissive portion of the main mirror 2 must be increased, and the finder becomes dark.

(Object of the Invention) It is an object of the present invention to solve this drawback and to provide a photometric device having a large received light output and a bright finder.

(Summary of the Invention) In the present invention, in the TTL photometric device, the reflecting surface of the sub-mirror has a special reflection characteristic so that the light reflected by the sub-mirror passing through the semi-transmissive portion of the main mirror can be efficiently received. The technical point is to form an assembly of reflecting mirrors to collect the subject light from the taking lens in the light receiving system.

(Embodiment) FIGS. 1 to 6 show a first embodiment of the present invention. First
The figure is an enlarged view of the sub-mirror 41, the taking lens 1, and the light receiving system (light receiving lens 5, light receiving element 6) in FIG. 3 for the sake of explanation. FIG. 2 shows the taking lens 1, the main mirror 2, the sub mirror 41, and the light receiving system of FIG.
Reference numeral 1 denotes a state in which partial light velocities 17 and 18 of the light flux from the light receiving lens 5 are guided to the exit pupil of the photographing lens 1. FIG. 4 is an explanatory diagram when the light flux 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 sub-mirror 41 shown in FIG. 1. The sub-mirror 41 is a minute conical mirror 41a having a vertex 41b.
It is composed of a collection of.

In FIG. 1, the minute conical mirror 4 of this sub-mirror 41 is shown.
1a is formed so as to have a vertex 41b at the center, and each minute conical mirror 41a reflects each light beam from the light receiving system and guides it to the exit pupil of the projection lens 1 as shown in FIG. In FIG. 1, the light beams reflected by the micro-conical mirror 41a are represented by using the light beams 11 and 12, and a part of the light beam 11 from the light receiving system is reflected in the downward direction of the micro-conical mirror 41a. Enters the lower part of the exit pupil of the taking lens 1, and the other light flux 12 from the light receiving system is reflected by the upper surface of the minute conical mirror 41a and enters the upper part of the exit pupil of the projection lens 1. Thus, the light beams reflected by a part of the minute conical mirror 41a are guided to the exit pupil of the taking lens 1 like the light beams 11 and 12 as shown in FIG. That is, FIG. 4 shows a state in which the light fluxes 11 and 12 are projected on the exit pupil of the projection lens 1 as a representative of the light flux shown in FIG. 1, but in reality, an infinite number of light fluxes from the light receiving system are one minute cone. It can be seen that the light flux from the light receiving system is guided to the entire exit pupil of the taking lens 1 as reflected by the surface mirror 41a and indicated by a chain line (a shaded portion is rotated about the center of the exit pupil).

Therefore, even if only one minute conical mirror 41a is taken, it is understood that the light flux reflected from it is guided to the entire exit pupil of the taking lens 1. As described above, each of the minute conical mirrors 41a of the sub mirror 41 is formed so as to have a reflection characteristic of reflecting the photographed image of the entrance pupil of the light receiving lens 5 so as to include the exit pupil of the photographing lens 1,
A minute conical mirror 41a formed on the entire surface of the sub mirror 41
All have the characteristics described above.

In FIG. 2, the luminous flux 13 (or the luminous flux 14) is the luminous fluxes 11 and 12 reflected by the minute conical mirror 41a as described above.
Etc. Considering the case where this light flux 14 is reflected at the upper point Q of the sub-mirror 41, the micro-conical mirror 41a of the sub-mirror 41 transmits the principal ray 14i of the light flux 14 from the light receiving lens 5 to the center point of the exit pupil of the taking lens 1. A reflecting surface is formed so as to pass through R. That is, the sub mirror 41
The principal ray of the light flux from the light receiving system which is incident on all the minute conical mirrors 41a above passes through the center point R of the exit pupil of the taking lens 1.

In this way, the reflection characteristic of the minute conical mirror 41a is realized at any point of the sub mirror 41. The sub-mirror 41 as a whole is configured to have a condensing characteristic such that the luminous flux of the exit pupil is condensed on the light receiving element 6 of the light receiving system.

Therefore, if the surface of the sub-mirror 41 is made up of an assembly of micro-conical mirrors 41a as shown in FIG. 5, the subject light incident on the sub-mirror 41 from the exit pupil of the taking lens 1 will be reflected by each micro-conical mirror 41a. Is efficiently reflected by the light receiving system, so that the light collecting ability of the sub mirror 41 is greatly improved. As a result, even if the transmissivity of the semi-transmissive part of the main mirror 2 is made lower than the conventional transmissivity in order to make the finder 3 brighter,
The subject light incident on the light receiving element 6 is sufficiently condensed by the sub-mirror 41, so that photometry can be performed.

FIG. 6 shows an example of the light receiving element 6 for multi-division photometry, and the light receiving element 6 is divided into five segments 61 to 65. The light-receiving element 6 corresponds to the shooting screen, and the segments 61 to 65 of the light-receiving element 6 perform multi-division photometry on the shooting screen. Each minute conical mirror 4 of the sub mirror 41
1a is formed so as to uniformly collect the incident light from the taking lens 1 on the light receiving element 6, so that in the multi-division photometry using the multi-division element shown in FIG. The photometric output of is properly obtained.

The shape of the minute conical mirror 41a shown in FIG. 5 is a conical surface, but it may be a concave or convex pyramidal surface, a spherical surface, or the like, and its shape depends on the configuration of the taking lens 1 and the light receiving lens 5. You can decide to.

7 and 8 show a second embodiment of the present invention, and FIGS. 7 and 8 show an improvement of the sub mirror 41 of the first embodiment. If the sub-mirror 41 is configured as in the first embodiment, photometry can be performed most efficiently. However, in the first embodiment, the directions of the micro-conical mirrors 41a are all different from one another, and it is very difficult to manufacture the sub-mirrors. . Therefore, in order to facilitate the production of the sub mirror, the sub mirror may be constructed as described below.

As shown in FIG. 7 and FIG. 8, the sub mirror 42 is divided into several blocks, and the minute conical mirror 41a of each block is divided.
Are formed in the same direction for each block, that is, in the same shape having the same reflection characteristics. In FIG. 7, the entire surface of the sub-mirror 42 is divided into 15 blocks, and the direction of the minute conical mirror 41a is determined for each block.
It is assumed that the minute conical mirror 41a is configured to have the same performance as that of the first embodiment. Since the direction of the minute conical mirror 41a is determined for each block,
The orientation of each block is determined so that the light flux from the exit pupil of the taking lens 1 is most efficiently condensed in the light receiving system as shown in FIG.

FIGS. 8A to 8D show the shapes of the blocks. FIGS. 8A and 8B are triangular and hexagonal blocks, respectively, and FIG. 8C is the photometry at the center of the photographing screen. When the system is especially required, the sizes of the blocks are changed between the central part and the peripheral part, and (d) shows an example in which the blocks are radially arranged. In this way, by changing the shape of each block, it is possible to correspond to the photometric mode of the photometric device, and to reduce the number of block divisions for those that do not require a photometric accuracy of the photometric device.

Therefore, if the micro-conical mirror 41a is constructed with a fixed direction for each block as shown in FIGS. 7 and 8, the sub-mirror 42 can be easily manufactured, and as shown in FIG. The shape of each block can be determined according to the required use.

(Effects of the Invention) As described above, according to the present invention, since the assembly of the micro-reflecting mirrors can efficiently guide the subject light from the photographing lens to the light receiving means, the light receiving output of the light receiving means becomes large and low. It is possible to measure the brightness of a subject. Further, since the assembly of the micro-reflecting mirrors can efficiently collect the subject light, the transmissivity of the semi-transmissive portion of the main mirror can be lowered to make the finder bright.

[Brief description of drawings]

FIGS. 1 to 6 show a first embodiment of the present invention. FIG. 1 is an enlarged view of a micro conical mirror which is a part of a sub mirror, and FIG.
Fig. 3 is a layout of the TL photometer, Fig. 3 is a layout of the optical system and the photometer in the body of the single-lens reflex camera, and Fig. 4 is the projection of the light beam reflected by the micro-conical mirror shown in Fig. 1. FIG. 5 is an enlarged perspective view of a part of the sub-mirror of FIG. 1, and FIG. 6 is a diagram showing an example of a multi-division photometric device. 7 and 8 show a second embodiment of the present invention, and FIGS. 7 and 8 are improved views showing improvements of the sub-mirror of the first embodiment. FIG. 9 shows a layout of a conventional TTL photometric device. (Explanation of Signs of Main Parts) 1 ... Shooting lens 2 ... Main mirror 4; 41; 42 ... Sub mirror 4a ... Micro-conical mirror

Claims (1)

[Claims] 1. A main mirror having a semi-transmissive portion that reflects subject light to a finder system and allows the subject light to pass through, and the subject light that has passed through the semi-transmissive portion to a light receiving means in a mirror box. In a TTL photometric device for a camera having a sub-mirror that reflects and is rotatably provided on the main mirror, the sub-mirror is formed by an assembly of micro-reflecting mirrors, and an entrance pupil of a light-receiving lens of the light-receiving means is formed by the micro-mirror. When reflected by a reflecting mirror and projected onto the exit pupil of the taking lens, each of the micro-reflecting mirrors has such a reflection characteristic that the projected image of the entrance pupil of the light receiving lens substantially includes the exit pupil of the taking lens. A TTL photometric device for a camera characterized in that