JP3529376B2 - Viewfinder frame switching camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finder field frame switching camera, and more particularly to a finder field frame switching mechanism for switching a finder field frame. 2. Description of the Related Art There have conventionally been provided various types of view frame switching mechanisms for a finder. A typical one is a viewfinder field frame switching mechanism disclosed in Japanese Patent Laid-Open No. 4-53939. There is a mechanism. This mechanism includes two relatively movable movable field frames forming a finder field frame, and a large-diameter ring cam that changes the length and width ratio of the finder field frame formed by the two movable field frames. In this method, the ring cam is rotated in conjunction with the switching operation of the photographing screen size, and the movable visual field frame is moved so that the finder visual field corresponds to the switched photographing screen size. However, since the conventional finder field frame switching mechanism uses a large-diameter ring cam, a large arrangement space is required and a high degree of component accuracy is required. Problem. An object of the present invention is to provide a finder having a finder field frame switching mechanism which can be disposed in a small space by skillfully using an elastic member and can prevent rattling of the finder field frame. An object of the present invention is to provide a camera for switching a field frame. In order to achieve the above object, a finder field frame switching camera according to the present invention is arranged in an image forming plane of a finder optical system, and switches a screen size of the field frame. Finder field frame defining means having a cam groove for driving the cam groove by directly engaging the cam groove, and an elastic member which bends and generates an elastic force after the switching. And Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a viewfinder frame switching mechanism in a screen size switching camera according to an embodiment of the present invention. In this embodiment, a roll film having a width of 35 mm is used as an example and a camera in which a photographing screen size can be switched between a full size (standard size) and a horizontally long panoramic size smaller than this size. However, since the screen size switching mechanism has no direct relation, it is not shown. As shown in FIG. 1, the finder optical system of this camera comprises a real image type finder optical system comprising finder objective lenses 1 to 4, a first prism 5 and a second prism 6, and an eyepiece 7. Have been. The first
The prism 5 and the second prism 6 are each formed of a right-angle prism, and the two prisms are arranged so as to be coupled to each other such that the exit surface and the entrance surface thereof face each other. The subject light enters the first prism 5, is reflected by the first reflecting surface 5 a toward the lower second reflecting surface 5 b, is reflected forward by the second reflecting surface 5 b, and is reflected by the second prism 6. Incident. Then, the light is reflected laterally (rightward in FIG. 1) on the first reflection surface 6 a of the prism 6, then emitted backward on the second reflection surface 6 b, and reaches the eyepiece 7. That is, in this real image type viewfinder optical system, the exit surface 5c of the first prism 5 facing the second reflection surface 5b is an image forming surface, and the image formed on the output surface 5c is an eyepiece. It is designed to look through the lens 7. The exit surface 5c of the first prism 5
A finder field frame defining means is provided between the first prism 6 and the incident surface 6c of the second prism 6, and the field frame defining means is operated by an elastic member driven by an elastic member driving means. , The field of view is switched. In other words, the finder field frame defining means, the elastic member and the elastic member driving means constitute a finder field frame switching mechanism. The finder field frame defining means comprises a field mask 8, a first moving mask 9, and a second moving mask 10. The field mask 8 is formed of a plate member and fixed to an immovable member. The upper half of the field mask 8 is provided with a horizontally long opening 8a forming a normal full-size field frame. Is provided with a guide hole 8d as a horizontally elongated narrow cam means through which an elastic member 14 described later is inserted. Screw holes 8b and 8c for attaching a moving mask are formed at one side edge (the left side edge in FIG. 1) at upper and lower positions. The first moving mask 9 is arranged so that the front surface of the visual field mask 8 overlaps the same mask and is slidable in the vertical direction. The first moving mask 9 is formed in an L shape by a thin plate member, and a horizontal portion thereof is formed on a driving plate portion 9b having a shape substantially matching the shape of the lower half portion of the visual field mask 8, The upper portion of the driving plate portion 9b covers the lower portion of the opening 8a when the visual field frame is switched, and the upper edge thereof forms a frame portion 9a on the lower side of the visual field frame. The driving plate 9b is provided with a cam groove 9f as a cam means inclined obliquely downward to the right. The vertical portion is a narrow extending arm portion 9c corresponding to a portion where the screw holes 8b and 8c for mounting the visual field mask 8 are provided, and the extending arm portion 9c has the screw holes 8b and 8c. Elongated guide slots 9d and 9e are formed corresponding to 8c. The lower guide slot 9e of the guide slots 9d and 9e serves to regulate the position of the moving mask 9 when moving upward and downward. On the other hand, the second moving mask 10 is arranged so that the front surface of the first moving mask 9 overlaps with the same mask and is slidable up and down. The second moving mask 10 is also formed of a thin plate member in an inverted U-shape, and a horizontal portion below the driving plate 9 of the first moving mask 9 is formed.
b is formed on a driving plate portion 10b slightly narrower in the vertical direction than the driving plate portion 9b.
A cam groove 10f is formed in b as a cam means which is inclined in a direction opposite to the cam groove 9f of the first moving mask 9 and a part thereof overlaps the cam groove 9f. The upper horizontal portion is formed in a relatively narrow cover arm portion 10g, and its lower edge portion is a frame portion 1 on the upper side of the field frame when the field frame is switched.
0a is formed. A vertical portion connecting the upper horizontal portion and the lower horizontal portion is formed by a connecting arm portion 10c overlapping with the extending arm portion 9c of the first moving mask 9, and the connecting arm portion 10c has , The guide slot 9
Vertical guide slots 10d, 10e corresponding to d, 9e
Are drilled. The lower guide slot 10e of the guide slots 10d and 10e serves to regulate the position of the moving mask 10 when moving upward and downward. As shown in FIG. 2, the first moving mask 9 and the second moving mask 10 are provided with mounting screws 11,
By means of 12, it is attached to the field mask 8 so as to be movable up and down. Each of the mounting screws 11 and 12 is formed by a stepped screw. That is, the mounting screws 11 and 12
Are provided with small-diameter threaded portions 11c, 12c at the front end thereof, short shaft portions 11b, 12b into which the guide long holes 9d, 9e, 10d, 10e are inserted in the middle, and short shaft portions at the rear end. 11b, 12b, a countersunk dish-shaped head having a diameter larger than that of 12b.
a, 12a, wherein the short shaft portion 11
The guide slots 9d and 9e of the first moving mask 9 and the guide slots 10d and 10e of the second moving mask 10 are inserted through the b and 12b, respectively, and the small-diameter screw portions 11c and 12c are attached to the mounting screws of the visual field mask 8. The first moving mask 9 and the second moving mask 10 are screwed into the holes 8b and 8c, respectively.
The front surface of the field mask 8 is attached so as to be movable up and down. The field mask 8, the first moving mask 9, and the second moving mask 10, which are thus disposed between the exit surface 5c of the first prism 5 and the entrance surface 6c of the second prism 6, are provided.
Are guide holes 8d and cam groove holes 9 formed in the lower portions thereof.
f, 10f are disposed so as to protrude below the lower ends of the prisms 5, 6, and the guide hole 8d and the cam groove holes 9f, 1 are provided.
At 0f, a single linear spring, which is a linear elastic member 14, is provided to penetrate from the rear in the optical axis direction. As shown in FIGS. 1 and 2, the base of the linear spring (elastic member) 14 is attached to a switching gear 13 constituting an elastic member driving means. This switching gear 13
Is formed by a partial gear in which a gear 13a is partially formed on a part of the peripheral surface of the disk, and a base of the wire spring 14 is provided on the outer periphery of a short cylindrical boss 13b formed at the center thereof. A circular base 14a formed at the end is rotatably fitted. The free end of the same-line spring 14 is provided with a biasing projection 13c formed on a part of the periphery of the upper surface of the switching gear 13.
Through the guide hole 8 d and the cam groove 9.
f, 10f. The urging projection 13c has an opening formed by a projection facing the boss 13b and having an inverted U-shape in plan view, and a radial through-hole 13f provided therein. Pushing protrusions 13d and 13e are formed on the inner surface of the through hole 13f opposite to the through hole 13f. The switching gear 13 is rotatably mounted on a stationary member (not shown).
A driving gear (not shown) meshes with the third gear 13a. As shown in FIG. 9, the driving gear transmits the driving force generated by the screen size switching means 16 to the switching gear 13 to operate the field frame switching mechanism 18 configured as described above. At this time, the switching gear 13 is preset so as to slightly rotate in the rotation direction after switching the field frame. The driving force generated by the screen size switching means 16 also operates the screen size switching mechanism 17 at the same time. When the screen size is full size, the field frame becomes the corresponding field frame. When the size is switched to the panorama size, the field frame is also configured to be switched to a panorama-compatible field frame. Next, the operation of the finder field frame switching mechanism in the screen size switching camera of the present embodiment configured as described above will be described. First, screen size switching means 1
When the switch 6 is driven to switch the screen size to the full size, the switch gear 13 rotates in the direction of the arrow a as shown in FIG. Then, the pushing protrusion 13d pushes the linear spring 14, and the spring 14 also rotates in the same direction. As a result, the tip of the linear spring 14 pushes down the cam groove 9f of the first moving mask 9 and the second moving mask 10
, The first moving mask 9 is moved downward, and the second moving mask 10 is moved upward. As shown in FIG. 3, the upper edge of the guide slot 9 e below the first moving mask 9 is moved by the mounting screw 12.
The first moving mask 9 is stopped from moving downward by contact with the short shaft portion 12b, and the lower inside edge of the guide elongated hole 10e below the second moving mask 10 is fixed to the short shaft portion 12b of the mounting screw 12. , The upward movement of the second moving mask 10 is stopped. In this state, the driving plate 9b of the first moving mask 9 retreats below the opening 8a and the arm 10g of the second moving mask 10 retreats above the opening 8a. The opening 8a is displayed as a full-size field frame in the finder field. As described above, the finder field frame switching mechanism includes:
The finder field frame defining means is switched to the full size field frame in conjunction with the screen size switching mechanism. At the time of this switching, the drive by the screen size switching means 16 is further continued. When this driving is continued, the switching gear 13 further moves as shown by the arrow a in FIG.
Rotate in the direction of and stop. When the switching gear 13 rotates slightly, the free end of the wire spring 14 cannot move any more, so that it is bent by being pushed by the pushing protrusion 13d. Accordingly, the first and second moving masks 9 and 10 are stably maintained at the full-size field frame switching position (see FIG. 3) by the elastic force of the linear spring 14 due to the bending. Next, when the screen size switching means 16 is driven to switch the screen size to the panorama size,
The switching gear 13 rotates in the direction of arrow b as shown in FIG. Then, the pushing protrusion 13e pushes the wire spring 14 to rotate the spring 14 in the same direction. Thus, the tip of the linear spring 14 pushes up the cam groove 9f of the first moving mask 9 and pushes down the cam groove 10f of the second moving mask 10. Accordingly, this causes the first moving mask 9 to move upward and the second moving mask 10 to move downward. As shown in FIG. 4, this movement moves upward of the first moving mask 9 by the inner lower edge of the guide elongated hole 9 e below the first moving mask 9 abutting on the short shaft portion 12 b of the mounting screw 12. Is stopped, and the guide slot 10e below the second moving mask 10 is stopped.
Of the second moving mask 10 is stopped when the upper inner edge of the second abutment comes into contact with the short shaft portion 12b of the mounting screw 12. In this state, the driving plate 9b of the first moving mask 9 covers the lower part of the opening 8a at the upper part, and the arm 10g of the second moving mask 10 covers the opening 8a.
a, the upper side of the opening 8a has the frame 1
At 0a, a horizontally long panorama-size field frame whose lower side is regulated by the frame portion 9a is formed, and is displayed as a panorama-size field frame in the viewfinder field. As described above, the finder field frame switching mechanism includes:
The finder field frame defining means is switched to the panorama size field frame in conjunction with the screen size switching mechanism. Continue a little further. When this driving is continued, the switching gear 13 further rotates in the direction of arrow b and stops, as shown in FIG. When the switching gear 13 rotates slightly, the free end of the wire spring 14 cannot move any more, so that the wire spring 14 is pushed by the pushing protrusion 13e and bends. Accordingly, the first and second moving masks 9 and 10 are stably maintained at the panorama-size viewing frame switching position (see FIG. 4) by the elastic force of the linear spring 14 due to the bending. The first and second moving masks 9 and 10 forming the field frame are always pressed in the respective directions by the line springs 14 after the switching operation is completed, thereby preventing the field frame from rattling. Is done. Furthermore,
The elastic force due to the bending of the linear spring 14 also absorbs the variation in connection between the screen size switching means, the field frame switching mechanism, and the screen size switching mechanism. Therefore, the field frame is held at a stable position. In the above embodiment, a wire spring is used as the linear elastic member, but it is a matter of course that a mold or a pressed product may be used. As described above, according to the present invention, the finder field frame switching mechanism in the finder field frame switching camera uses an elastic member to switch the finder field frame. Since a small finder field frame switching mechanism that cannot be adopted can be configured and the elastic member is slightly bent after the field frame is switched, it is possible to prevent the field mask from rattling.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a viewfinder frame switching mechanism in a screen size switching camera according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part of a finder field frame switching mechanism of the embodiment. FIG. 3 is a front view showing a state in which the finder field frame switching mechanism is switched to a full-size field frame. FIG. 4 is a front view showing a state in which the finder field frame switching mechanism is switched to a panorama-size field frame. FIG. 5 is a plan view showing an operation of switching a field frame to a full size of a wire spring by a switching gear. FIG. 6 is a plan view showing an operation in which a line spring switches a field frame to a panoramic size by a switching gear. FIG. 7 is a plan view showing a state where a line spring is urged following a full-size field frame switching operation. FIG. 8 shows a panorama-size field frame switching operation,
FIG. 4 is a plan view showing a state where a wire spring is biased. FIG. 9 is a block diagram showing the relationship between screen size switching means, a field frame switching mechanism, and a screen size switching mechanism. [Description of Signs] 8 Field mask (field frame) 9 First moving mask (finder field frame defining means) 10 Second moving mask (finder field frame) Defining means) 9f cam groove 10f cam groove 13 switching gear (elastic member switching means) 14 wire spring (elastic member)

Claims (1)

(57) [Claim 1] In a finder field frame switching camera, a finder field frame arranged in an image forming plane of a finder optical system and having a cam groove for switching a screen size of the field frame. A viewfinder frame switching camera, comprising: a defining means; and an elastic member which directly engages with the cam groove to drive the cam groove, and after the switching, bends to generate an elastic force.