JP3491789B2 - Camera viewfinder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finder for a camera in which a finder optical system is arranged in addition to a photographing optical system and which is further equipped with an automatic focus detection mechanism.

[0002]

2. Description of the Related Art Conventionally, an infrared projection active triangulation system has been used in many distance detection devices for lens shutter type cameras. This is an infrared light emitting diode (I
Infrared light is projected from the RED) through the light projecting lens to the subject, and the reflected light from the subject is received by the semiconductor detection device (PSD) through the light receiving lens arranged at a fixed distance (baseline length) from the light projecting lens, The subject distance is detected based on the incident position.

Usually, the distance measuring optical system and the finder optical system are separately provided. Therefore, parallax (parallax) between the optical axis of the projection lens system and the optical axis of the finder optical system is likely to occur, and there is a possibility that a point not intended by the photographer may be focused. Furthermore, it is necessary to secure a space for each optical system in the camera layout. However, the demand for miniaturization of compact cameras these days is increasing, so it is extremely difficult to house the shooting optical system, viewfinder optical system, range finding optical system, and even photometric optical system independently in a small body. It has become a business. Those trying to solve these problems are disclosed in JP-A-2-29723 and JP-A-4-29723.
No. 269734, etc.

The one disclosed in Japanese Patent Application Laid-Open No. 2-29723 eliminates parallax by making part of the optical axes of the finder objective lens system and the projection lens system common. As a means for this, a half mirror is used in the middle of the optical path of the finder objective lens system to divide into a finder optical path and a projection system optical path. However, the half mirror leads to an increase in cost and is not suitable for a compact camera that requires low cost. Japanese Patent Laid-Open No. 4-2
Japanese Patent Publication No. 69734 discloses a distance measuring optical system, or a device in which the photometric optical system is arranged so as to be orthogonal to the optical axis of the finder in the optical path of the finder. With this configuration, another optical system such as a distance measuring optical system and a photometric optical system can be arranged in the space of the finder optical system, thus saving space in the camera layout.

However, the finder optical system described in the above publication uses a relay lens as an image inverting means. Therefore, the viewfinder itself is already large, and even if the other optical systems are well laid out, there is no great effect when the size of the entire camera is considered.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of these problems, and its object is to provide an optical axis of another optical system such as a distance measuring optical system or a photometric optical system in the middle of a finder optical path. By arranging so that it intersects with the optical axis of the finder optical system, the space in the camera layout can be effectively utilized and the camera itself can be made compact, and the parallax of the finder optical system and the ranging optical system It is to provide a viewfinder for a camera that hardly exists.

[0007]

In order to solve the above problems, a camera finder of the present invention comprises a finder optical system and a distance measuring optical system in addition to a photographing optical system, and the finder optical system is a positive optical system. The finder includes an objective lens system having a refractive power of 1, an image inverting optical member having a plurality of reflecting surfaces for making an image formed by the objective lens system an erect image, and an eyepiece system having a positive refractive power. The optical axes of the optical system and the distance measuring optical system intersect at a common optical member in the optical path of the finder, and the common member is the fiber.
On the optical axis of the under optics
Molded and measured independently of the viewfinder optical system.
It is characterized in that a surface having power is formed on the optical axis of the distance optical system . In the present invention, since it is a primary image forming type real image type finder, a Porro prism, a penta prism, a mirror or the like is used as an image inverting member, and an intermediate image is erected as an erect image by its reflecting surface . In the present invention the is found <br/>, optical system having an optical axis intersecting the optical axis of the finder optical system further may be a photometric optical system in the light receiving lens system in the projection lens system of the distance measuring optical system.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a distance measuring optical system having an optical axis intersecting with the optical axis of the finder optical system is arranged in a space in the optical path of the finder optical system, and is conventionally provided separately. The finder optical system and the distance measuring optical system that were used are partly common. Therefore, most of the distance measuring optical system can be arranged in the volume required for the finder optical system, so that a large space can be saved in the camera layout, which can greatly contribute to the downsizing of the camera. Moreover, since the number of parts can be reduced by the common use, it is also advantageous in terms of cost.

Further, the finder optical system according to the present invention is a primary imaging type finder, which uses a reflecting surface such as a Porro prism as an image inverting means to make the intermediate image of the objective lens an erect normal image. Therefore, the finder optical system itself can be downsized as compared with the case where a relay lens is used as the image inverting means. In addition to this, a part of the space for the distance measuring optical system is unnecessary, which facilitates the layout of the camera body. Further, since the objective lens of the finder optical system and the projection lens of the distance measuring optical system can be located relatively close to each other, it is possible to perform highly accurate distance measurement with almost no parallax. Further, the IRED of the distance measuring optical element includes a package of a spherical type and a package of a flat type. A convenient one can be selected and used according to the conditions such as the layout of the projection optical system.

Embodiments of the present invention will be described below with reference to examples shown in the drawings. First Reference Example FIGS. 1 and 2 show a first viewfinder for a camera according to the present invention.
A top view and a perspective view of the reference example are shown, respectively. This ginseng
Considered example is a real-image viewfinder of the primary imaging type, in order from the object side, the objective lens system, the positive lens 1, prism 2 containing 1 plane reflecting surface for image reversal, and the field frame 3, The eyepiece lens system is composed of a three-reflection prism 4 and a positive lens 5 for image reversal, and the prism 2 and the prism 4 reflect a total of four times to convert the intermediate image by the objective lens into an erect normal image. . On the other hand, the distance-measuring projection optical system is composed of, in order from the object side, a positive lens 6, a prism 4, and a distance-measuring light-emitting element 7, and has an optical axis A of the finder optical system and a distance-measuring light-emitter. The optical axis B of the optical system intersects with the finder optical path. In this embodiment, a part of the prism 4 in the eyepiece system has a common finder optical system and a distance-measuring projection optical system. Therefore, it is possible to eliminate the need for a space for a distance-measuring projection optical system, which is separately provided in addition to the finder optical system in the related art.

First Embodiment FIGS. 3 and 4 show a first viewfinder for a camera according to the present invention.
A top view and a perspective view of the embodiment are respectively shown. This embodiment is a primary-image-formation real-image finder, and in the objective lens system, in order from the object side, a prism 8 as an objective lens including one reflecting surface for image inversion, a light projecting lens, The common prism 9, the visual field frame 10, and the eyepiece lens system include a three-reflection prism 11 and a positive lens 12 for image reversal. Similar to the first reference example, an erect normal image is obtained from the intermediate image by the objective lens by a total of four reflections by the Porro prism. On the other hand, the distance-measuring projection optical system is composed of a prism 9 and a distance-measuring light-emitting element 13 in order from the object side. The optical axis A of the finder optical system and the light of the distance-measuring projection optical system are arranged in this order. The axis B intersects with the finder optical path.

Second Embodiment FIGS. 5 and 6 show a second viewfinder for a camera according to the present invention.
A top view and a perspective view of the embodiment are respectively shown. This embodiment is a primary image formation type real image finder, and in order from the object side, a positive lens 14, a roof prism 15, and a field frame 16 in the objective lens system, and a penta prism 17 and a positive lens in the eyepiece system. It is composed of a lens 18, and the roof prism 15 and the penta prism 17 are arranged to obtain an erect image. On the other hand, the distance-measuring projection optical system is composed of a roof prism 15 and a distance-measuring light-emitting element 19 in this order from the object side, and the optical axis A of the finder optical system and the distance-measuring projection optical system The optical axis B intersects with the finder optical path. With this configuration,
Since the space above and below the viewfinder for the camera is not used, this space can be effectively used in the camera layout. In this embodiment, a part of the roof prism 15 in the eyepiece system is commonly used for the finder optical system and the distance measuring projection optical system. In each of the above embodiments, the optical system having an optical axis that intersects the optical axis of the finder optical system may be the light projecting lens system, the light receiving lens system, or the photometric optical system of the distance measuring optical system.

[0013]

As described above in detail, and as is clear from the embodiments, according to the present invention, the optical axes of the finder optical system and the distance measuring optical system are crossed to each other, thereby improving the layout of the camera. The space can be effectively used, and the camera can be made compact. In addition, since some common members are used, the cost can be reduced. Further, in this configuration, the optical axis of the objective system and the optical axis of the distance measuring optical system can be arranged close to each other, so parallax can be almost eliminated.

[Brief description of drawings]

FIG. 1 is a top view showing a first reference example of a camera finder according to the present invention.

FIG. 2 is a perspective view showing a first reference example of a camera finder according to the present invention.

FIG. 3 is a top view showing a first embodiment of the camera finder according to the present invention.

FIG. 4 is a perspective view showing a first embodiment of a camera finder according to the present invention.

FIG. 5 is a top view showing a second embodiment of the camera finder according to the present invention.

FIG. 6 is a perspective view showing a second embodiment of the camera finder according to the present invention.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B ^7/ 28-7/40 G02B 25/00 G03B ^7/ 00-7/28 G03B 13/06

Claims (4)

(57) [Claims] 1. A finder optical system and a distance measuring optical system are provided separately from a photographing optical system, and the finder optical system has an objective lens system having a positive refracting power and an image formed by the objective lens system is an erect image. An image reversing optical member having a plurality of reflecting surfaces and an eyepiece lens system having a positive refractive power, and the optical axes of the finder optical system and the ranging optical system are common in the middle of the finder optical path. It intersects with each other at such member
The common member is the optical axis of the finder optical system.
A surface with power or a reflective surface is molded on the
On the optical axis of the distance measurement optical system independent of the inder optical system
A viewfinder for a camera, which has a molded surface with power . 2. The finder optical system is a real-image finder of a primary imaging type.
The viewfinder for the camera described in. 3. A finder optical system and a photometric optical system are provided separately from the photographing optical system, and the finder optical system has an objective lens system having a positive refracting power and an image formed by the objective lens system is an erect normal image. An image inverting optical member having a plurality of reflecting surfaces for effecting, and an eyepiece lens system having a positive refractive power, wherein the optical axes of the finder optical system and the photometric optical system are common members in the middle of the finder optical path. All in crossing
The common member is the optical axis of the finder optical system.
A surface with power or a reflective surface is molded on the
On the optical axis of the photometric optical system independent of the inder optical system
A viewfinder for a camera, which has a molded surface with power . 4. The finder optical system is a primary image-forming real image finder.
The viewfinder for the camera described in.