JP3272636B2 - Camera viewfinder device - 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 device for a camera, and more particularly to a finder device provided independently of a photographic lens system.

[0002]

2. Description of the Related Art Recent cameras, whether a single-lens reflex camera or a compact camera, generally have an autofocus function. With a single-lens reflex camera, the degree of blurring of the image formed on the focus plate in the viewfinder changes with the focusing of the shooting lens, and as a result of autofocusing, it is determined whether or not the subject is in focus by looking at the viewfinder can do.

On the other hand, in a camera in which the finder system is provided independently of the photographing lens system, means for turning on a lamp in the finder when the subject distance can be detected is provided. When lights up, it is determined that the subject is in focus and the shutter is released.

[0004]

However, in a non-single-lens reflex camera, it is not possible to confirm whether or not the photographer can properly focus on the subject intended by the photographer before photographing. If the camera is set to autofocus without accurately focusing on the subject, or if the subject malfunctions because it is difficult to detect flames or scenery through glass by the distance measurement system, the intended subject will be in focus. There is a problem that does not fit.

That is, since the means such as the lamp in the finder only indicates whether or not the distance measurement has been successful for the subject located in the distance measurement area, the above-mentioned operation by the photographer is performed. In the event of a mistake or malfunction of the distance measurement system, a so-called out-of-focus photograph is taken without focusing on the subject intended by the photographer, even if the photographer confirms that the lamp is on. The Rukoto.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. In a camera in which a finder system is provided independently of a photographic lens system, the camera focuses on a subject intended by a photographer by autofocusing. It is an object of the present invention to provide a finder device that allows the user to know whether or not the camera can be adjusted while looking at the finder.

[0007]

In order to achieve the above object, a finder apparatus according to the present invention has a first objective optical system for forming a real image of a subject and a first objective optical system having a predetermined base line length. A second objective optical system that looks at the subject from a direction different from the first direction and forms a real image of the subject;
A light beam combining element that forms a double image by superimposing a light beam incident through the second objective optical system on a part of the field of view formed by the light beam incident through the objective optical system;
An erecting optical system for inverting an inverted image formed by the light beam synthesized by the light beam combining element to form an erect image, and an eyepiece optical system for guiding the light beam emitted from the erecting optical system to the photographer's eyes An optical path deflecting means for deflecting the optical path of the second objective optical system to change the degree of overlap of the double images along the base line length direction, and a light projecting system and a light receiving system for detecting a distance to a subject. Active distance measuring means, and two objects formed by light beams incident from the first and second objective optical systems on the object at the object distance based on the object distance detected by the distance measuring means. Control means for controlling the optical path deflecting means so that the images overlap each other, and the light projecting system projects the detection light to the subject side through the light beam combining element and at least a part of the lens of the first objective optical system in this order. The light receiving system is an optical path deflecting means. Through it, characterized in that it receives the detection light reflected by the object originating from the light projecting system.

[0008]

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 is an explanatory diagram illustrating a configuration of an optical system and a control system of the finder device according to the embodiment. The photographic optical system is provided independently of the finder, and has an autofocus function in which the photographic lens is driven for focusing according to a subject distance signal from a distance measuring device.

The optical system of the double image matching type finder according to the embodiment comprises a real image type finder optical system, a real image type rangefinder optical system, and an active type distance measuring means. The finder optical system includes a first objective optical system 10 that forms a real image of a subject, a condenser lens 13, and an erecting prism (an erecting optical system, which is expanded in the drawing) 8.
0, and an eyepiece lens (eyepiece optical system) 50 to constitute a Kepler-type finder. The first objective optical system 10 includes a negative lens 11 and a positive lens 12.

The rangefinder optical system includes a second objective optical system 20 that forms a real image of a subject using the light beam reflected by the rotating mirror 40. The second objective optical system 20 includes a negative lens 21 and a positive lens 22. The second objective optical system 20 differs from the first objective optical system 10 with a predetermined base line length by viewing a subject via the rotating mirror 40. Look at the subject from the direction. The range of the image formed by the rangefinder optical system is
The aperture (not shown) limits the viewfinder to only the center of the field of view.

A light beam incident via the first and second objective optical systems 10 and 20 is a half mirror as a light beam combining element disposed between the first objective optical system 10 and the erect prism 80. 30. First objective optical system 1
The imaging plane IM of 0 is located between the half mirror 30 and the condenser lens 13, and the imaging plane of the second objective optical system 20 also substantially coincides with the imaging plane IM of the first objective optical system 10. Match.

A light beam which enters through the first and second objective optical systems 10 and 20 and forms an inverted image on the image plane IM is inverted by the erect prism 80 so as to form an erect image, and is connected to the eyepiece. The light enters the lens 50. The light beam incident from the first objective optical system 10 covers the entire area of the finder visual field, a part of which passes through the half mirror 30, and passes through the condenser lens 13, the erect prism 80, and the eyepiece lens 50. Led to the eyes. On the other hand, the light beam incident from the second objective optical system 20 has a transmission range limited to a central portion in the viewfinder visual field by the stop, and a part thereof is a half mirror 30.
Reflected by the condenser lens 13 and the erect prism 8
0, the light enters the photographer's eye via the eyepiece 50. Therefore, the photographer can observe the double image formed by the light beams incident through the two objective optical systems 10 and 20 in the central area of the finder visual field, and observe the first object in the surrounding area. A non-overlapping image formed by the light beam incident through the optical system 10 can be observed.

The degree of overlapping of the double images is changed by changing the angle of the rotating mirror 40 according to the output of the distance measuring means. The angle of the rotating mirror 40 is controlled by a mirror driving motor 110 which is a stepping motor. The rotating mirror 40 and the mirror driving motor 110 deflect the optical path of the second objective optical system 20, that is, the second objective optical system Ax1 with respect to the optical axis Ax1 of the first objective optical system 10. By tilting the optical axis Ax2 of the system 20, it functions as an optical path deflecting unit that changes the degree of overlap of the double images along the base line length direction. As the optical path deflecting means, in addition to using the above-mentioned rotating mirror 40, at least a part of the lens of the second objective optical system 20 is connected to the second objective optical system 2.
A mechanism for eccentricity in the direction perpendicular to the optical axis 0 may be provided, or a variable apex angle prism may be used.

The active distance measuring means includes a light projecting system 60 having an infrared light emitting diode 61 and a light projecting lens 62.
And a light receiving system 70 including a light receiving lens 71 and a PSD element 72. The light projecting system 60 combines the detection light with the optical path of the first objective optical system 10 by using a half mirror for light projection, and projects the light toward the subject through at least a part of the lenses of the first objective optical system 10. Light. In this example, the light projecting half mirror is also used as the half mirror 30 as a light beam combining element. That is, the light projecting system 60 is arranged so that the detection light enters the half mirror 30 from the opposite side of the second objective optical system 20, and the detection light reflected by the half mirror 30 is the first light. The light is projected on the subject side through two lenses of the objective optical system 10.

The light receiving system 70 separates the optical path of the range finder optical system by a light receiving half mirror disposed on the object side of the second objective optical system 20 in the optical path of the range finder optical system, thereby providing a light projecting system. The detection light emitted from 60 and reflected by the subject is received. In this example, the light receiving half mirror is also used as the rotating mirror 40 which is an optical path deflecting unit. The rotating mirror 40 can be configured as a dichroic mirror that transmits infrared light and reflects visible light. The detection light transmitted through the rotating mirror 40 is condensed on the PSD element 72 via the light receiving lens 71.

The PSD element 72 is an element that detects the center position of the intensity distribution of the collected light as a resistance value. The control circuit 100 obtains the subject distance based on the principle of triangular distance measurement by reading, as a resistance value, the focus position of the detection light that changes according to the distance to the subject. Also, the control circuit 1
00 is a turning mirror 4 based on the calculated subject distance.
A rotation angle of 0 is obtained. The angle of the rotating mirror 40 is such that two subject images formed by the light beams incident from the first and second objective optical systems 10 and 20 on the subject at the calculated subject distance are within the double image forming range. To match
That is, the optical axis Ax1 of the first objective optical system 10 and the optical axis Ax2 of the second objective optical system are determined to intersect at the detected object distance. The control circuit 100 controls the mirror drive motor 110 so that the turning mirror 40 is set at the obtained turning angle.

The subject distance information output from the distance measuring means is generally used by an autofocus device that automatically focuses the photographing lens on the subject. In this embodiment, the rotation of the rotating mirror 40 is performed as described above. The subject distance information is also used as information for determining the moving 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, according to the finder device of the embodiment, the rotating mirror 4 is moved so that the image of the subject to be measured for distance can be observed in the double image forming range.
Since 0 is controlled, if it is a subject intended by the photographer, it can be determined that the intended subject can be focused by the auto focus, and the image of the intended subject is shifted in the double image display area and doubled. When the subject is observed, it is understood that the intended subject is different from the subject to be measured. 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.

When the photographing optical system is constituted by a variable-magnification lens such as a zoom lens, it is desirable that the first and second objective optical systems 10 and 20 are also constituted as a variable-magnification optical system. In this case, while changing the magnification of the first objective optical system 10 in accordance with the change in the focal length of the photographing optical system,
It is desirable to have a magnification changing means for changing the magnification of the second objective optical system 20 so as to be equal to the magnification of the first objective optical system 10.

[0019]

As described above, according to the present invention, a double image can be used as a means for confirming an autofocus function, and even in a camera in which a finder system is provided independently of a photographic lens system. Since it is possible to know whether or not the subject intended by the photographer is in focus before photographing, it is possible to prevent a photographing error relating to focusing in advance.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 1st objective optical system 20 2nd objective optical system 30 Half mirror (light beam combining means) 40 Rotating mirror (optical path deflecting means) 50 Eyepiece 60 Projection system 70 Light receiving system 80 Erect prism 100 Control circuit 110 Mirror Drive motor

Continuation of the front page (56) References JP-A-9-43682 (JP, A) JP-A-55-65938 (JP, A) JP-A-57-64217 (JP, A) , U) Japanese Utility Model Showa 49-55349 (JP, U) Japanese Patent Publication No. 39-15725 (JP, B1) Japanese Patent Publication No. 49-9276 (JP, B1) (58) Fields surveyed (Int. Cl. ⁷ , DB G03B 13/02-13/36 G02B 7/32

Claims (6)

(57) [Claims] In a finder device of a camera provided independently of a photographing optical system, a first objective optical system for forming a real image of a subject and the first objective optical system having a predetermined base line length are provided. A second objective optical system that looks at the subject from a different direction and forms a real image of the subject, and a second objective optical system that forms a real image of the subject, A light beam combining element that forms a double image by overlapping light beams incident through the objective optical system, and an inverted image formed by the light beam combined by the light beam combining element to form an erect image. An erecting optical system, an eyepiece optical system that guides a light beam emitted from the erecting optical system to a photographer's eye, and deflecting an optical path of the second objective optical system to determine how the double images overlap. Along the baseline length direction An optical path deflecting means for changing the distance to the object, an active distance measuring means for detecting a distance to the object, comprising a light projecting system and a light receiving system; and an object distance based on the object distance detected by the distance measuring means. Control means for controlling the optical path deflecting means so that two subject images formed by the light beams incident from the first and second objective optical systems on the subject at , A light beam combining element, and at least a part of the lens of the first objective optical system, and sequentially emits the detection light to the subject side. A camera finder device for receiving detection light emitted from the object and reflected by a subject. 2. The finder device for a camera according to claim 1, wherein the light beam combining element is disposed between the first objective optical system and the erecting optical system. 3. The image forming apparatus according to claim 1, wherein an image forming plane of the first objective optical system substantially coincides with an image forming plane of the second objective optical system. Camera viewfinder device. 4. The magnification of the first objective optical system is changed in accordance with a change in the focal length of the photographing optical system, and the second objective optical system is made equal to the magnification of the first objective optical system. 4. The finder device for a camera according to claim 1, further comprising a magnification changing means for changing a magnification of the system. 5. The camera according to claim 1, wherein the optical path deflecting unit includes a turning mirror and a mirror driving unit that turns the turning mirror. Viewfinder device. 6. The rotating mirror transmits infrared light,
6. The camera viewfinder device according to claim 5, wherein the viewfinder device is a dichroic mirror that reflects visible light.