JPH02103024A - Finder display device - Google Patents

Abstract

PURPOSE:To always allow an object image to coincide with the visual field of a focusing display even if object distance is changed by changing the position of an emitting element which lights a hologram plate according to the object distance. CONSTITUTION:The hologram plate 5 set in a non-TTL type finder system diffracts light from an emitting element 4 arranged outside a finder optical path and performs focusing display in a finder visual field. When the object distance is changed, the light emitting element 4 is moved in the way that the diopter of the focusing display coincides with an object diopter, for example, by a motor, a bimorph, etc., in response to object distance found by a range- finding device 1. Therefore, even if the object distance is changed a photographer can constantly see a focusing display at the same position as an object image position and obtain the finder easy to see.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a finder display device used in an autofocus camera equipped with a non-TTL type finder in which the diopter of a subject image changes depending on the subject distance.

[Prior Art] Japanese Patent Publication No. 58-27504 discloses that the optical distance from the position of an image reproduced by diffracted light from a hologram to the eyepiece of a monitor system is the distance from the monitor i image to the eyepiece of the monitor system. By arranging the hologram in a part of the monitor system so that the optical distance is the same as or almost equal to the optical distance of An information display method is disclosed. The same publication also proposes using the above display method when displaying information within the field of view in a camera finder.

[Problems to be Solved by the Invention] However, the content disclosed in the above-mentioned publication cannot deal with the case where the optical distance from the monitor image to the eyepiece changes. The embodiment disclosed in the above publication has the following features: - In the finder optical system of an eye reflex camera, the optical distance from the eyepiece to the reconstructed image by the hologram is the same as the optical distance from the focusing plate below the pentaprism to the eyepiece. The holograms are arranged so that they are equal, and the optical distance between the monitor image and the eyepiece is constant. However, when a lens-shutter camera is equipped with a non-TTL finder optical system, the optical distance from the finder's eyepiece to the subject image changes depending on the subject distance. In the conventional technology, in such a case, it is not possible to change the optical distance from the eyepiece to the reconstructed image by the hologram, so the diopter of the displayed information and the diopter of the monitor image differ. When the observer's eyes focus on either the monitor image or the displayed information, the other image will be out of focus, making it impossible to observe both at the same time.

The present invention has been made in view of the above points, and its purpose is to provide an autofocus camera equipped with a viewfinder that changes the diopter of the subject image depending on the subject distance. An object of the present invention is to provide a finder display device in which the diopter of an image and a focus display match.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, the first
As shown in the figure, a distance measuring device 1 that measures a subject distance,
A finder display for an autofocus camera, comprising a lens driving device 2 that drives a photographing lens so as to focus on a subject distance measured by a distance measuring device 1, and a finder 3 whose diopter of a subject image changes depending on the subject distance. The device includes a light emitting element 4 arranged outside the finder optical path, a hologram plate 5 arranged in the finder optical path and diffracting the light from the light emitting element 4 to display a focus within the finder field of view, It is characterized by comprising a light emitting position adjusting means for varying the light emitting position of the light emitting element 4 according to the subject distance measured by the distance measuring device 1 so that the diopter of the display matches the diopter of the subject image. That is.

Specific examples of the light emitting position adjusting means for changing the light emitting position of the light emitting element 4 include a method in which the light emitting element is moved using a motor or a bimorph (see Fig. 1), and a method in which the light emitting element is moved using a motor or a bimorph, and a method in which a plurality of light emitting elements 4a to 4d are moved. are arranged in a row along the direction in which the light emitting position can be changed, and one of the light emitting elements is selectively emitted (
(see FIG. 2), etc. can be used.

[Function] The finder display device of the present invention is an automatic finder display device that includes a distance measuring device 1 that measures a subject distance, and a lens driving device 2 that drives a photographing lens so as to focus on the subject distance measured by the distance measuring device 1. Since it is used in a focus camera, even if the diopter of the subject image in the finder 3 changes depending on the subject distance, it is possible to know where the subject image is formed in the finder 3 based on information from the distance measuring device 1. Can be done. The focus display is displayed within the viewfinder field of view by diffracting the light from the light emitting element 4 placed outside the viewfinder optical path by the hologram plate 5 placed in the viewfinder optical path. The display position can be changed depending on the light emitting position of the light emitting element 4. Therefore, if the light emitting position of the light emitting element 4 is made variable according to the subject distance measured by the distance measuring device 1 so that the diopter of the focus display matches the diopter of the subject image, the subject Even if the diopter of the image changes, the viewer can always see the focus display in the same position as the subject image.

[Example] FIG. 1 is a schematic diagram of an embodiment of the present invention.

Reference numeral 1 denotes a distance measuring device, which measures the distance to a subject using, for example, a triangular distance measuring method including a light projecting optical system and a light receiving optical system. 2
is a lens driving device, which drives the photographic lens so that the photographic lens focuses on the subject distance measured by the distance measuring device 1; 3 is a reverse Galilean-style phisider,
A concave lens is used for the objective lens 3A and a convex lens for the eyepiece lens 3B, and the erect virtual image of the subject formed by the concave lens is enlarged by the convex lens to make it easier to see.

Assuming that the objective lens 3A is not linked to the focusing of the photographic lens, the diopter of the subject image changes depending on the subject distance, and this becomes more noticeable as the finder magnification increases.

Reference numeral 4 denotes a light emitting element, and the light emitting element 4, which is made of a semiconductor laser that generates coherent light or a light emitting diode that generates non-coherent light, is arranged outside the finder optical path and irradiates light into the finder optical path. Reference numeral 5 denotes a hologram plate, which is placed in the finder optical path just in front of the eyepiece lens 3B. This hologram plate 5 transmits a part of the transmitted light to the eyepiece lens 3 when transmitting the light from the light emitting element 4.
It is diffracted toward B and forms an image indicating focus. Further, the light from the objective lens 3A passes through without being obstructed. Therefore, from the eyepiece lens 3B, an erect virtual image of the subject formed by the pair of lenses 3A and an in-focus image formed by the transmitted diffracted light of the hologram plate 5 are observed.

As mentioned above, the diopter of the subject image changes depending on the subject distance, so when the subject distance is CK) (infinity),
The light emitting element 4 is arranged at point A so that the subject image and the diopter of the focus display match. Since the transmission type hologram plate 5 of this embodiment has a convex lens-like effect, as the light emitting element 4 moves rightward in the figure, the diopter of focus display becomes closer. Therefore, by moving the light emitting element 4 to the right in the figure as the subject distance measured by the distance measuring device 1 becomes shorter, it becomes possible to always match the subject image and the diopter of the focus display. Note that as a driving means for the light emitting element 4, a motor, a bimorph, or the like can be used.

FIG. 2 is a schematic configuration diagram of another embodiment of the present invention. In this embodiment, instead of moving the light emitting elements, a plurality of light emitting elements 4a to 4d are arranged in a line along the moving direction of the light emitting position. and according to the subject distance measured by the distance measuring device 1,
It is configured to selectively cause any one light emitting element to emit light so that the diopter of the subject image and the focus display substantially match.

The hologram plate 5 is connected to the objective lens 3 in the finder optical path.
It is placed immediately after A. When this hologram plate 5 reflects the light from the light emitting elements 4a to 4d, it diffracts a part of the reflected light toward the eyepiece lens 3B to form an image indicating focus. Further, the light from the objective lens 3A is transmitted without being obstructed. Therefore, an erect virtual image of the subject formed by the objective lens 3A and an in-focus image formed by the reflected and diffracted light from the hologram plate 5 are observed through the eyepiece 3B. Since this hologram plate 5 has a concave mirror effect, the diopter for displaying focus can be changed depending on which light emitting element emits light among the light emitting elements 48 to 4d arranged in the optical axis direction of the finder optical system. can.

FIG. 3 is an explanatory diagram of the operation of the hologram plate 5.

Interference fringes 5A are provided on the surface of the hologram plate 5. When the interference fringes 5A are irradiated with reproduction light from the light emitting element 4, a portion of the transmitted light is diffracted and becomes reproduction light as transmitted diffraction light. In this case, since the pitch of the interference fringes 5A of the hologram plate 5 differs, the diffraction angle of the transmitted diffracted light differs, and the hologram plate 5 acts like a convex lens. On the other hand, a part of the reflected light is diffracted and becomes reproduced light as reflected diffracted light. In this case, the interference #! of the hologram plate 5! Since the pitch of 5A is different, the diffraction angle of the reflected diffracted light is different, and the hologram plate 5 has a concave mirror effect. In the embodiment shown in FIG.
A transmission hologram is used that performs reproduction using transmitted diffraction light, and the embodiment shown in FIG. 2 uses a reflection hologram that performs reproduction using reflected diffraction light. The hologram plate 5 in each embodiment, by its convex lens action or concave mirror action, allows the light emitting element 4 located outside the viewfinder optical path to appear within the viewfinder field of view without distortion, and does not affect the subject light within the viewfinder field of view. It is located in

It goes without saying that the present invention is applicable not only to an inverted Galilean type finder but also to any autofocus camera equipped with a finder in which the diopter of the subject image changes depending on the subject distance.

[Effects of the Invention] As described above, the present invention is a finder display device for an autofocus camera equipped with a finder in which the diopter of the subject image changes depending on the subject distance, and the present invention utilizes a hologram plate in the finder optical path to display a subject image within the viewfinder field of view. This device displays focus by changing the light emitting position of the light emitting element that illuminates the hologram board from outside the viewfinder optical path according to the subject distance, so that the diopter of the focus display matches the diopter of the focused subject image. So even if the subject distance changes,
The viewer can always see the focus display on the subject image and rotation position, making the viewfinder easier to see.
Another advantage is that it is easy to confirm that the subject is in focus.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of one embodiment of the present invention, FIG. 2 is a schematic block diagram of another embodiment of the present invention, and FIG. 3 is an explanatory diagram of the operation of a hologram plate used in each of the above embodiments. 1 is a distance measuring device, 2 is a lens driving device, 3 is a finder, 4 is a light emitting element, and 5 is a hologram plate.

Claims (1)

[Claims] (1) A distance measurement device that measures the distance to the subject, a lens drive device that drives the photographic lens to focus on the subject distance measured by the distance measurement device, and a finder that changes the diopter of the subject image depending on the distance to the subject. A finder display device for an autofocus camera, comprising: a light-emitting element disposed outside the finder optical path; and a light-emitting element disposed within the finder optical path, diffracting light from the light-emitting element to display focus within the viewfinder field of view. and a light emitting position adjusting means for varying the light emitting position of the light emitting element in accordance with the subject distance measured by the distance measuring device so that the diopter of the focus display matches the diopter of the subject image. A finder display device characterized by comprising: