JPH10197915A - Finder device for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize an optical path synthesizing element such as a half mirror without raising the cost by providing a real image type objective optical system closer to an ocular optical system side than the optical path synthesizing element in a double superposing type finder. SOLUTION: The real image type objective optical system 20 is provided closer to the ocular optical system 28 side than the optical path synthesizing element 13 in the double superposing type finder. In this device, luminous flux from an object O, which is made incident from a field window 11, and luminous flux from the object O, which is made incident from a rangefinder window 31 and reflected by a turning mirror 32, are synthesized by the element 13 and made incident on the optical system 20 constituted of four groups of lenses 21 to 24 so as to form a real image on an image-formation surface IM. The object light emitted from the optical system 20 is inverted in terms of an image up and down and right and left by a mirror 25a and a prism 25 and becomes an erected image, and is made incident on a photographer's eye through the optical system 28 constituted of two groups of lenses 26 and 27.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finder device having a double image matching finder for forming a double image by combining a rangefinder image with a part of a finder field.

[0002]

2. Description of the Related Art A double image matching finder has a field-of-view window and a distance meter window separated from each other by a predetermined base line length. Inject into the system. The photographer observes a double image of the subject through the eyepiece optical system. Between the rangefinder window and the half mirror, there is provided a rotating mirror that deflects the optical path so as to change the degree of overlap of the double images along the base line length direction, and is used when the two subject images overlap. The subject distance is obtained from the rotation angle of the rotation mirror.

In the interlocking rangefinder, the movement of the taking lens and the turning of the rotating mirror are interlocked, and the interlocking relationship is set so that the taking lens is focused when two subject images match. Have been.

In the conventional double image matching type viewfinder, the following two types are required depending on the positional relationship between the objective lens and the half mirror.
There are two types. In the first type, an objective lens is provided in each of two optical paths on the object side of the half mirror, and in the second type, a common virtual image type objective lens is provided on the eyepiece side of the half mirror. .

[0005] The first type makes it possible to clarify the outline of a double image, particularly when the objective lens is a real image type, and to obtain an easy-to-see visual field. On the other hand, the second type has a very small number of parts and is easy to assemble as compared with the first type, so that the cost can be reduced.

[0006]

However, the above-described first type double image matching type viewfinder has a problem that the number of parts is large and the assembling is troublesome, so that the cost is increased. In the second type of finder, since the half mirror is arranged on the object side of the virtual image type objective lens, the area of the half mirror is relatively large. Also,
In the second type, since the objective lens is a virtual image type, there is a problem that the field frame is not clearly seen in the finder field, and it is difficult to display information in the finder.

Further, in the finder of the first type, if the magnification of the finder is changed in response to the zooming operation of the photographing optical system, the objective lenses on both the visual field side and the distance meter side are changed in magnification. However, there is a problem in that the configuration is complicated because it is necessary to move them simultaneously.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and does not increase the cost as in the first type, and has an optical path combining element such as a half mirror compared to the second type. It is an object of the present invention to provide a finder device having a double image matching finder that can be reduced in size.

[0009]

According to the present invention, there is provided a camera viewfinder apparatus for achieving the above object.
The double image matching type finder is characterized in that a real image type objective optical system is provided closer to the eyepiece optical system than the optical path combining element.

That is, in the finder device for a camera according to the present invention, an optical path synthesizing element for synthesizing light beams incident from a field-of-view window and a distance meter window separated by a predetermined base line length, and a light beam synthesized by the optical path synthesizing element are made incident. A real image type objective optical system, and an eyepiece optical system for observing a subject image formed by the objective optical system, and an overlapping state of a double image observed through the eyepiece optical system is changed along a base line length direction. An optical path deflecting means for deflecting an optical path of a light beam incident from the rangefinder window.

In order to limit the range in which a double image can be formed, an aperture may be provided in the optical path between the rangefinder window and the optical path combining element. When a turning mirror is used as the optical path deflecting means, a stop for limiting the range where a double image can be formed may be formed on the mirror surface of the turning mirror.

Further, when the camera has an auto-focus function, based on subject distance information corresponding to the subject distance, a light beam formed on a subject at that distance from a field window and a distance meter window is formed by a light beam 2. If the optical path deflecting means is controlled so that two subject images overlap, the double image can be used as a means for checking the autofocus function.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a finder device for a camera according to the present invention will be described. FIG. 1 shows the first
FIG. 3 is an explanatory diagram showing a configuration of an optical system of a finder device according to the embodiment. The optical system includes a viewing window 11 and a distance meter window 31 that are separated by a predetermined base line length, and a light beam from the subject O incident from the viewing window 11 and incident from the distance meter window 31 and reflected by the rotating mirror 32. The light flux from the subject O thus obtained is synthesized by the optical path synthesizing element 13, and the four groups of lenses 21,
Real image type objective optical system 2 composed of 22, 23 and 24
At 0, a real image is formed on the image plane IM.

The object light emitted from the objective optical system 20 is turned upside down and left and right by a mirror 25a and a prism 25 constituting the erecting optical system to become an erect image, and is constituted by two groups of lenses 26 and 27. Incident on the photographer's eye via the eyepiece optical system 28. Although the prism 25 is actually a right-angle prism having two reflecting surfaces orthogonal to each other,
In FIG. 1, it is shown expanded. In the following description, the axis obtained by linearly extending the optical axes of the objective optical system 20 and the eyepiece optical system 28 is the optical axis Ax1 of the finder system, and the axis turned back to the rotation mirror 32 by the optical path combining element 13. It is defined as the optical axis Ax2 of the distance meter.

In the optical path between the rotating mirror 32 and the light beam combining element 13, an aperture plate 33 for limiting the range of the light beam incident from the rangefinder window 31 in order to determine the area where the double image is formed. Is provided. As shown in FIG. 2, the aperture plate 33 has a rectangular transmission region 33a formed in the center, and a surrounding hatched portion is an opaque region 33b.

The optical path synthesizing element 13 is a transparent plane-parallel plate having a half-mirror region at a part of the center, so that the optical axis Ax1 of the finder system is orthogonal to the optical axis Ax2 of the distance meter. , Are arranged at 45 degrees to the optical axis Ax1. At the periphery of the field of view, only the light beam incident from the field window 11 enters the objective optical system 20, and at the center portion, the light beams incident from both windows are combined to form the objective optical system 20.
Incident on. For this reason, in the viewfinder visual field observed by the photographer via the eyepiece optical system 28, the view window 1
It is possible to observe a non-overlapping image formed by the light beams incident from No. 1 and a double image formed by the light beams incident from both windows at the center.

A turning mirror 32, which is an optical path deflecting means, is provided so as to be rotatable around a turning axis B intersecting the optical axis in a direction indicated by an arrow, and enters from the rangefinder window 31 by turning. By deflecting the optical path of the light beam, the eyepiece optical system 2
The degree of overlap of the double images at the center of the finder visual field observed through 8 can be changed along the base line length direction. In this example, the rotating mirror 32 is configured to rotate in conjunction with the focusing of a photographic lens (not shown), similarly to the conventional double image matching type viewfinder. When the images match each other, the taking lens is focused on the subject.

The aperture plate 33 is not only located at the position of the above-described embodiment, but is also connected to the light beam combining
As long as the rotation mirror 32 does not hinder the rotation, it can be provided at any position in the optical path up to 3. Further, instead of the diaphragm plate 33, the rotating mirror 32 may have the function of a diaphragm plate. When the turning mirror 32 has the function of a diaphragm, as shown in FIG.
A rectangular reflective area 32a indicated by a mesh in the figure is formed at the center, and the surrounding area is formed as a non-reflective area 32b. Alternatively, the size of the rotating mirror 32 is
It is formed in the size of a.

When a field frame is displayed in the finder field, the frame can be clearly displayed in the field by arranging it near the image plane IM of the objective optical system 20. Also, when variable information is displayed in the viewfinder using the liquid crystal panel, the visibility of the display can be kept high by providing the display element near the imaging plane.

FIG. 4 is an explanatory view similar to FIG. 1 showing a second embodiment of the present invention. In the second embodiment, the configuration of the optical system is the same as that of the first embodiment shown in FIG. In the second embodiment, a distance measuring device 104 for measuring a distance to a subject is provided, and the rotating mirror 32 is driven by a mirror driving motor 140. Based on the distance information to the subject measured by the distance measuring device 104, the control circuit 103 generates two subject images formed by the luminous flux incident from the viewing window 11 and the rangefinder window 31 on the subject at that distance. The mirror drive motor 140 is controlled to overlap.

The subject distance information output from the distance measuring device 104 is generally used by an autofocus device that automatically focuses the taking lens on the subject. In this embodiment, as described above, the rotating mirror 32 is used. The subject distance information is also used as information for determining the rotation angle.
Thus, it is possible to know whether or not the subject intended by the photographer is focused by the autofocus while looking through the viewfinder. In other words, since the image of the subject to be measured is observed in alignment in the double image display area without any shift, if it is the subject intended by the photographer, the subject intended by the autofocus is focused on. If it can be determined that the intended subject image is displaced in the double image display area and is observed twice, it is understood that the intended subject and the subject to be measured are different. Therefore, when the image of the intended subject is double-observed, the photographing lens can be focused on the intended subject by re-measuring the distance until the image of the intended subject is observed.

The object distance information input means for obtaining the distance information to the object is not limited to the distance measuring device for directly obtaining the object distance as in the above embodiment, but is also driven for focusing based on the object distance information. It is also possible to use the position information of the photographing lens obtained, or to use the defocus amount of the photographing lens detected by the phase difference type focus state detecting device. When the defocus amount is used, the subject distance can be obtained based on the current focus position of the photographing lens and the defocus amount.

When the photographing lens system is a zoom lens capable of zooming, it is preferable that the finder also be of a zoom type. FIGS. 5 and 6 show a finder optical system having a configuration similar to that shown in FIGS. 1 and 4, in which the second lens group 22 of the real image type objective optical system is moved in the optical axis direction. FIG. 4 is an explanatory diagram showing light paths on the visual field side and the range finder side when the magnification is changed according to FIG. The arrangement and function of the optical elements are the same as in the above-described embodiment.

FIGS. 5A and 5B are optical path diagrams at the time of low magnification. FIG. 5A shows light rays incident from the rangefinder window and incident on the eye, and FIG. 5B shows light rays incident from the viewing window 11 and incident on the eye. Is shown.
In FIG. 5A, two light beams entering from the rangefinder window 31 indicate a range of a light beam emitted from one point of the subject included in the formation range of the double image in the viewing range, and enter from the viewing window 11. 2
The light rays indicate the range of the luminous flux emitted from the same point as the one point. Similarly, in FIG. 5B, two sets of two parallel light beams incident from the viewing window 11 indicate the range of light flux from different points in the viewing range.

FIGS. 6A and 6B are optical path diagrams at the time of high magnification. FIG. 6A shows a light ray entering from the rangefinder window and entering the eye, and FIG. Fig. 3 shows light rays incident on the eye. The meaning of the light beam in each figure is the same as in FIG. In the case where a common real image type objective optical system is provided on the image side of the light beam combining element 13 as in this example, the lens group located on the common path of the light beam from the rangefinder window and the view window is moved. Since zooming is possible, the configuration of the moving mechanism can be simplified as compared with the case of moving the lens of each optical path as in the first type described in the conventional example.

[0026]

As described above, according to the present invention, by providing the objective optical system as a real image type on the eyepiece optical system side with respect to the optical path combining element, the size required for the optical path combining element is different from that of the virtual image type. The information can be easily displayed in the viewfinder because the field of view can be clearly seen in the viewfinder. On the other hand, the finder device of the present invention can reduce the number of parts and cost, as compared with a configuration in which two sets of objective optical systems are provided. Also, in order to make the finder system have a zooming effect, it is enough to move the common lens group in both optical systems, so the structure of the moving mechanism is simplified compared to moving the lens groups in each optical path. Can be

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an optical system and a control system showing a first embodiment of a finder device according to the present invention.

FIG. 2 is a plan view showing a configuration of an aperture plate used in the apparatus of FIG.

FIG. 3 is a plan view showing a modified example of the rotating mirror used in the apparatus of FIG.

FIG. 4 is an explanatory diagram of an optical system and a control system showing a second embodiment of the finder device according to the present invention.

FIG. 5 is an optical path diagram at a low magnification when the finder device of the embodiment is configured as a variable power optical system.

FIG. 6 is an optical path diagram at a high magnification when the finder device of the embodiment is configured as a variable power optical system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 View window 13 Optical path synthesis element 20 Objective optical system 28 Eyepiece optical system 31 Distance meter window 32 Rotating mirror 33 Aperture plate

[Procedure amendment]

[Submission date] December 27, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

The subject light emitted from the objective optical system 20 is
The image is inverted upside down and left and right by the mirror 25a and the prism 25 constituting the erecting optical system to become an erect image, and enters the eye of the photographer via the eyepiece optical system 28 including the two groups of lenses 26 and 27. I do. Although the prism 25 is actually a right-angle prism having three reflecting surfaces orthogonal to each other, it is shown expanded in FIG. In the following description, the axis obtained by linearly extending the optical axes of the objective optical system 20 and the eyepiece optical system 28 is the optical axis Ax1 of the finder system, and the axis turned back to the rotation mirror 32 by the optical path combining element 13. It is defined as the optical axis Ax2 of the distance meter.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

The aperture plate 33 is not limited to the position in the above-described embodiment , but is also provided through the rangefinder window 31 through the light beam combining element 13.
As long as the rotation mirror 32 does not hinder the rotation, it can be provided at any position.
Further, instead of the diaphragm plate 33, the rotating mirror 32 may have the function of a diaphragm plate. In the case where the turning mirror 32 has an aperture function, as shown in FIG. 3, a rectangular reflective area 32a shown by a mesh in the figure is formed at the center, and the surrounding area is formed as a non-reflective area 32b. .
Alternatively, the size of the rotating mirror 32 is formed to the size of the reflection area 32a.

Claims (8)

[Claims] 1. An optical path combining element for combining light beams incident from a field-of-view window and a distance meter window separated by a predetermined base line length, a real image type objective optical system for receiving the light beam combined by the optical path combining element, and An eyepiece optical system for observing a subject image formed by the objective optical system, and incident from the rangefinder window so as to change the degree of overlap of a double image observed through the eyepiece optical system along the base line length direction. And a light path deflecting means for deflecting an optical path of the light beam to be emitted. 2. An object distance information input means for obtaining object distance information corresponding to a distance to an object, and a visual field for an object at the distance based on the object distance information obtained by the object distance information input means. 2. The camera viewfinder device according to claim 1, further comprising: a control unit that controls the optical path deflecting unit such that a window and two subject images formed by light beams incident from the rangefinder window overlap each other. 3. The camera viewfinder device according to claim 2, wherein said subject distance information input means is a distance measuring device for directly obtaining a subject distance. 4. The finder device for a camera according to claim 1, wherein said optical path deflecting means comprises a turning mirror and a driving means for turning said turning mirror. 5. The viewfinder device for a camera according to claim 4, wherein a stop for limiting a range in which a double image can be formed is provided on a mirror surface of the rotating mirror. 6. The optical system according to claim 1, wherein an aperture for limiting a range where a double image can be formed is provided in an optical path between the rangefinder window and the optical path combining element. Camera viewfinder device. 7. The viewfinder device for a camera according to claim 1, wherein the optical path combining element is a transparent plate partially provided with a half mirror area. 8. The objective optical system is configured as a variable power optical system that changes magnification relative to a subject by changing a relative distance in a direction of an optical axis of a plurality of lens groups included in the objective optical system. The finder device for a camera according to claim 1, wherein: