JP3235707B2 - Viewfinder prism holding structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prism holding structure for a finder, and more particularly, to a method of forming an image of object light passing through an objective lens on an exit surface of a prism and using a field frame arranged close to the exit surface. The present invention relates to a prism holding structure applied to a finder configured to restrict a visual field.

[0002]

2. Description of the Related Art Conventionally, an optical viewfinder incorporated in a camera generally has an objective lens, a prism, a field frame, and an eyepiece disposed on a frame of the viewfinder. The subject image is formed by refraction, the field of view is regulated by a field frame, and then guided to an eyepiece, so that the subject image can be observed through the eyepiece. There is also a configuration in which an image forming surface of a subject image is matched with an emission surface of a prism, and a field frame for regulating a range of a visual field is arranged close to the emission surface of the prism.

[0003]

However, in the above-mentioned conventional finder, when a subject image is formed on the exit surface of the prism, the exit surface of the prism, which is the image-forming surface of the subject image, and the field frame for regulating the visual field range. Must be placed very close to each other because the focus needs to be substantially matched at the eyepiece. Therefore, when the prism is mounted on the frame of the finder, there is a problem that the end face of the prism is easily scratched by being rubbed by the field frame, and shaving is generated. A target mark, a parallax correction mark, and the like are engraved on the exit surface of the prism, and there is a problem that if the exit surface is damaged, the damage and shavings are enlarged and observed by an eyepiece.

If the exit end face of the prism is widened so as not to be rubbed by the field frame, the focus between the field frame and the target mark or the like deviates when the eyepiece is viewed. There's a problem. The present invention has been made in view of such circumstances, and provides a finder prism holding structure in which a prism can be mounted on a finder body frame in close proximity to a field frame without damaging an exit end face of the prism. The purpose is to do.

[0005]

According to the present invention, in order to achieve the above object, an image of a subject which has passed through an objective lens is formed on an exit end face of a prism, and a field of view is arranged in a field frame arranged close to the exit end face of the prism. In a finder that regulates a range and observes the subject image through an eyepiece, a prism housing portion having a size such that the prism can be loosely inserted is formed in a frame body that holds the prism. The prism is urged in the direction of the emission end face by an elastic member inserted into a clearance formed between the prism loosely inserted in the frame and the frame, and the emission end face of the prism is brought close to the field frame. It is characterized by being held.

According to the present invention, a clearance is formed in the frame on which the prism is mounted so that the prism can move in the direction of the emission end face, and the prism is inserted into the frame with play. In this way, by providing the clearance between the frame and the prism, the prism is mounted on the frame without the emission end face coming into contact with another member such as the frame or the field frame. After that, the prism inserted loosely into the frame is urged by an elastic member toward the exit end face of the prism to be fixed. Thus, the exit end face of the prism is located close to the field frame. Accordingly, the emission end face of the prism on which the subject image is formed when the prism is mounted can be arranged close to the field frame without damaging the emission end face.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a finder prism holding structure according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing an appearance of a camera to which a finder prism holding structure according to the present invention is applied. Outer case 11 of camera 10 shown in FIG.
At the center of the front surface of the lens is mounted a lens barrel 13 in which a photographing lens 12 is incorporated. A flash window 14 is provided at the upper right corner of the taking lens 12, and a finder objective window 16 and an AF projection window 1 are provided on the left side of the flash window 14 in the drawing.
8, a photometric window 20, and an AF light receiving window 22 are sequentially formed. A shutter button 24 is provided on the upper surface of the camera 10.
Is provided.

An AF light projecting portion is provided inside the AF light projecting window 18 and an AF light receiving device is provided inside the AF light receiving window 22. These AF light projecting / light receiving portions measure a distance to a subject. The distance measuring unit (AF unit) determines the distance to the subject based on, for example, the principle of triangulation, and the result is used for autofocus (AF) control. Inside the photometric window 20, there is provided a lens (not shown) through which external light is incident, and a photometric unit including a light receiving element provided at an image forming position of the lens. Is measured. The measurement result is the exposure control (A
E control).

The photographing lens 12 is, for example, a 2 × zoom in which the focal length can be changed in a range of f = 25 to 55 mm, or a 3 × zoom in which the focal length can be changed in a range of f = 30 to 90 mm. In addition, each model is configured with a different optical system. A zoom button (not shown) is provided on the back of the camera body 10. When the zoom button is operated, a lens driving motor (not shown) is driven, and the driving force of the motor is transmitted through a plurality of gears to the driving mechanism of the photographing lens 12 and the driving mechanism of the moving lens driving system of the zoom finder. Is transmitted to The photographer can select a desired photographing magnification by operating the zoom button, and can observe a field of view substantially equal to the photographing angle of view from the eyepiece of the viewfinder. The configuration of the zoom finder and the driving mechanism of the moving lens driving system will be described later.

Further, the photographing lens 1 inside the camera 10
A shutter (not shown) is incorporated on the optical axis 2 and operates in conjunction with the operation of the shutter button 24. FIG. 2 is a perspective view of the finder unit 30 incorporated in the camera 10. In the body frame 31 of the finder unit 30, an AF light receiving storage section 32 corresponding to the AF light
An AF light receiving section 34 corresponding to the F light projecting window 18, an objective lens 36 provided inside the viewfinder objective window 16
Is arranged.

In the finder unit 30, the main frame 31 is divided into a first storage frame 40 and a second storage frame 70 (see FIG. 3).
A first block is formed in the finder body frame 40 in which the AF unit (the AF light receiving unit and the AF light projecting unit), the objective lens 36, the moving lens system 38, and the like are housed. On the other hand,
The second storage frame (eyepiece frame) 70 houses a prism 72, an eyepiece 74, and the like to form a second block.

FIG. 4 is an exploded perspective view of the first block. As shown in the figure, the first block includes a finder variable magnification optical system in an AF / finder main body frame 40,
A driving mechanism for the variable power optical system is mounted. The finder variable magnification optical system includes an objective lens 36 and moving lenses 42 and 43. Objective lens 3
6 is fitted into an objective lens opening window 40a formed on the front surface of the AF / finder body frame 40, and the moving lenses 42 and 43 are housed in a groove 45 behind the objective lens 36. . In addition, the moving lenses 42 and 43
A mask member 47 is provided therebetween.

Flat portions 51 and 52 are formed on the left and right edges of the movable lenses 42 and 43, respectively. Projections 51A and 51A are formed integrally with these flat portions 51 and 51, and flat portions 52 and 51 are formed. , 52 have guide holes 54, 5
5 are formed. A guide rod 56 is inserted into the guide holes 54 and 55, and the front end of the guide rod 56
The guide rod 56 is press-fitted into a hole 40b formed in the front wall of the finder body frame 40, and the rear end of the guide rod 56 is press-fitted and fixed in a hole 40b formed in the rear wall of the AF / finder body frame 40.

In the AF / finder body frame 40, a step 57 is formed at the upper left side of the groove 45 for accommodating the moving lenses 42 and 43. The projections 51A, 51 of the moving lenses 42, 43
A is located, and the groove 45 is covered with the objective cover 41 from above the moving lenses 42 and 43, so that a slide groove is formed by the step 57 and the lower edge of the objective cover 41. The movable lenses 42 and 43 are guided along the slide grooves so as to be movable in the front-rear direction via the protrusions 51A and 51A, and the vertical shake is suppressed.

Driven pins 54A and 55A are provided on the side of the movable lenses 42 and 43 so as to protrude therefrom.
A and 55A are engaged with a cam shaft 58 constituting a drive mechanism of the variable power optical system. The driving mechanism includes a cam shaft 58
And a motor (not shown) for driving the cam shaft 58 to rotate. This motor is also used as a drive motor for the photographing lens barrel 13, and the rotational force of the motor is fixed to the cam shaft 58 via a gear train (not shown).
A.

The cam shaft 58 is connected to the movable lens 42,
Cam surfaces 58A, 58B defining the optical positional relationship of 43
Are formed on the outer periphery thereof. Both ends of the cam shaft 58 have holes 40c formed in the AF / finder body frame 40,
Each is press-fitted into 40c and fixed. Note that the rear gear 59B is linked to a strobe mechanism (not shown). A movable lens 42 is provided on a cam surface 58 </ b> A on the front side of the cam shaft 58.
The driven pin 54A of the movable lens 43 is provided on the cam surface 58B on the rear side of the cam shaft 58.
Is abutted. L-shaped hooks 54B and 55B are formed on the upper portions of the moving lenses 42 and 43, and a tension spring 48 is passed between the hooks 54B and 55B. The driven pin 54A is pressed against the cam surface 58A by the urging force of the tension spring 48, and the driven pin 55A is pressed against the cam surface 58B. Thus, the relative positions of the moving lenses 42 and 43 are restricted.

As described above, since the motor for rotating the cam shaft is also used as the motor for the photographing lens barrel 13, when the motor is driven, the cam shaft 58 rotates in conjunction with the lens barrel 13. As a result, the shooting angle of view and the viewfinder visual field range match. FIG. 5 is an exploded perspective view of the second block. As shown in the figure, the second block includes a second storage frame (eyepiece frame) 70, a prism 72, a high vision (H) field frame 75, a convention / panorama (CP) field frame 76, a field switching lever 79, a field of view. A frame base 80, a field lens 82, a mirror 83, an eyepiece 74 and the like are mounted.

The prism 72 is housed in the eyepiece frame 70 along an inclined surface 70A formed on the upper part of the eyepiece frame 70, and is urged to the right in FIG. Are positioned without play. The structure for holding the prism 72 will be described later. The prism 72 has a shape formed by combining two right-angle prisms, and reflects an incident subject light three times to obtain an erect image. That is, the subject light emitted from the zoom optical system enters from the entrance surface 72A of the prism 72,
2B, the light is reflected downward by 90 °, then reflected forward by 90 ° on the reflective surface 72C, further reflected by 90 ° in the horizontal direction (lateral direction) on the reflective surface 72D, and exits 72E orthogonal to the incident surface 72A. Is emitted from. The exit surface 72E
Are engraved with a target mark and a parallax correction mark, and a subject image is formed on the emission surface 72E.

An H field frame 75 provided in close contact with the exit surface 72E of the prism has a print aspect ratio (PA).
R) is a fixed frame that defines a field of view corresponding to the high-definition size (H size) of H, and is a field frame that defines the largest area including a convention (C) size or panorama (P) size described later. is there. Behind the H field frame, there is further provided a CP field frame 76 capable of switching and defining a field corresponding to the C size or the P size. The CP field frame 76 includes a pair of substantially L-shaped field frame pieces 76a and 76b, a field switching lever 79, and a field frame base 80.
a and 76b are vertically opposed to each other, and the pair of visual field frame pieces are moved in a direction approaching each other in a direction of 45 degrees or in a direction away from each other to enlarge or reduce a visual field area of a C size or a P size.

At both ends of the field frame pieces 76a and 76b, a rectangular stroke hole 77 is formed at an angle of 45 degrees.
A and 77B are formed. This stroke hole 77
Pins 80a and 80b projecting from the field frame base 80 are engaged with A and 77B. The field frame piece 76
Near the corners of a and b, elongated holes 78A and 78b, respectively.
B is formed, and pins 79a and 79b projecting from the visual field switching lever 79 are engaged with the long holes 78A and 78B, respectively.

An arc-shaped guide groove for guiding the rotation of the visual field switching lever 79 is formed on the front surface of the visual field frame base 80, and the visual field switching lever 79 is rotated by being guided by the arc groove. As a result, the visual field is switched by the visual field frame pieces 76a and 76b. A field lens 82 is fixed behind the field frame base 80, and a mirror 83 is further fixed behind the field lens 82. The mirror 83 is fitted on the edge of the eyepiece frame 70 at an angle of 45 degrees with respect to the exit surface of the field lens 82, is urged from behind the mirror 83 by the mirror pressing plate 85, and is fixed to the eyepiece frame 70. You. The mirror 83 reflects the optical axis of the exit surface of the prism 72 by 90 degrees toward the back of the camera 10, and is guided to the eyepiece 74.

The eyepiece lens 74 is attached to an opening formed in the eyepiece frame 70 via a diopter adjusting cam (not shown) so as to be movable back and forth. The diopter adjustment cam is connected to the diopter adjustment knob, and the photographer can move the diopter adjustment knob to move the eyepiece 74 back and forth to adjust the diopter. Next, the holding structure of the prism will be described with reference to FIGS. FIG. 6 is a front view of the prism holding structure, and FIG. 7 is a plan view. As shown in FIG. 6, in the eyepiece frame 70, a portion for accommodating the prism 72 (prism accommodating portion) is formed to be slightly larger than the width of the prism 72, and a clearance (play) enough to allow the prism 72 to move freely. ) D is formed. A concave portion 70B is formed on the bottom surface of the prism housing portion, and a pin 72F protruding from the bottom of the prism 72 is engaged with the concave portion 70B.

As shown in FIG. 7, guide pins 72G, 72G are provided on the right and left sides of the prism 72, respectively.
The guide pins 72G, 72G are guided by guide grooves 70C, 70C formed in the
Is inserted into the eyepiece frame 70. The prism 72 is the eyepiece frame 7
After being loosely inserted into the eyepiece 0, it is shifted to the right side in the figure, and is fixed by the prism pressing plate 73 inserted into the gap d between the wall surface of the eyepiece frame 70 and the prism 72 (see FIG. 6).
The prism 72 is urged to the right side in the figure by the prism pressing plate 73, and the pin 72F of the prism is brought into contact with the right wall surface of the recess 70B. Thus, the exit surface 72E of the prism 72 is positioned and fixed at a position close to the H field frame 75.

As described above, the second block includes the prism 72
And the optical components after the prism 72 are all the eyepiece frames 7
It is unitized to fit in 0. On the other hand, the first block shown in FIG. 4 is unitized so that the optical components and the AF unit in front of the prism 72 are accommodated in the AF / finder body frame 40. Then, in order to assemble the second block below the first block, a hole 40 formed in the AF finder body frame of the first block is required.
The projections 70d, 70d (see FIG. 5) formed on the second block are respectively fitted and positioned in d, 40d (see FIG. 4), and the holes 40e, 40e (see FIG. 4) of the first block and the second Align the holes 70e, 70e (see FIG. 5) of the block and connect them with screws from above. This results in the finder unit shown in FIG.

On the other hand, a gear 79C is formed below the view switching lever 79, and the gear 79C is meshed with the switching gear 88A. The switching gear 88A is formed at one end of the visual field switching shaft 88 shown in FIG. FIG. 8 is a structural view of the visual field switching mechanism. As shown in the figure, the visual field switching mechanism is provided on a wall surface 11a behind the camera so as to be movable up and down, and is connected to the PAR knob 90 and moves up and down integrally with the PAR knob 90. A PAR contact piece 91 and a PA
The CHP lever 93 is provided with a spring 92 for transmitting the vertical movement of the R contact piece 91 to the visual field switching shaft 88.

A click groove 95 for regulating the stop position of the PAR contact piece 91 is provided inside the wall surface 11a behind the camera.
A, 95B, and 95C are formed, and correspond to switching of the C, H, and P visual fields, respectively, from the top of the figure.
The click grooves 95A, 95
A claw 91A that engages with one of B and 95C is formed by bending, and the PAR knob 90 is switched to the three stages of C, H, and P.

One end of the visual field switching shaft 88 is connected to the gear 79C of the visual field switching lever 79 via the switching gear 88A as described above, and the other end is connected to the CHP lever 93 via the CHP spring 92. Thereby, the PAR knob 9
When 0 is switched up and down, the PAR contact piece 91 moves up and down, and CHP
The lever 93 moves up and down. The movement of the CHP lever 93 is transmitted to the visual field switching shaft 88 via a spring 92.

Since the C size or the P size is a size in which the high-vision size area is partially limited, the pair of the field frame pieces 76a and 76b are used while using the fixed frame of the H field frame 75. By vertically moving the two visual field frame pieces 76a and 76b in the diagonal direction, it is possible to switch the visual field corresponding to each size of H, C or P.

According to the finder configured as described above, as shown in FIGS. 6 and 7, the eyepiece frame 70 is provided with a clearance with the prism at a portion where the prism 72 is housed. When the prism 72 is attached to the eyepiece frame 70, the prism 72 can move freely by the clearance. That is, the prism 7
The second exit surface 72 </ b> E can be inserted into the eyepiece frame 70 without making contact with the H field frame 75 or the like. Then, after the prism 72 is loosely inserted into the eyepiece frame 70, a prism pressing plate 73 is inserted into a gap created by the clearance, and the prism 72 is urged toward the H field frame 75 to be fixed. Thus, the pin 72F provided on the bottom surface of the prism 72 abuts against the end surface of the positioning concave portion 70B formed on the bottom surface of the eyepiece frame 70, and the exit surface 72E of the prism 72 is positioned close to the H field frame 75. Is done.

Thus, the prism 72 can be held and fixed to the eyepiece frame 70 without damaging the exit surface 72E of the prism, which is the image-forming surface of the subject image, and the exit surface 72E can be extremely close to the field frame. Can be arranged. The subject light incident through the objective lens 36 is bent downward by the prism 72 as shown in FIG. 5, then folded forward, and further, in a direction orthogonal to the incident optical axis, That is, the camera 10
Is bent in the lateral direction of the prism, and the exit surface 72E of the prism is bent.
Is imaged. As described above, the optical path is once folded back in the incident direction (forward) by the prism 72, so that the camera 1
0 is made thinner. Then, this emission surface 72E
Can be observed from the eyepiece through the field lens 82 and the eyepiece 74.

When the photographer operates the zoom switch,
When the focal length of the taking lens 12 is changed, the taking lens 1
The camshaft 58 is rotated by a gear that rotates in conjunction with the second focus variable mechanism (see FIG. 4), and a subject image substantially equal to the magnification scaled by the photographing lens system is formed on the eyepiece of the viewfinder. can do. In addition, if the photographer uses the CHP knob 9
When the desired aspect ratio is selected by operating 0, the CP field frame 76 is enlarged and reduced as described above, and the field of view is switched.

In the above embodiment, the zoom finder capable of switching the field of view in three steps of CHP has been described. However, regardless of whether the field of view is switched and whether or not the finder variable magnification optical system is provided, the subject can be changed. The present invention can be widely applied to a finder that forms an image on an end face of a prism.
In the above embodiment, the prism 72 is attached to the eyepiece frame 70.
, The prism 72 is biased in the direction of the exit surface 72E, and the prism pressing plate 73 is inserted into a gap formed between the side wall of the eyepiece frame 70 and the prism 72. Although the case where the prism 72 is fixed by the urging force has been described, the prism pressing plate 73 is inserted into the eyepiece frame 70 in advance, the prism pressing plate 73 is retracted to the clearance portion, and the prism 72 is moved to the eyepiece frame 70.
May be loosely inserted, and then the retracting of the prism pressing plate 73 may be released to bias the prism 72.

Further, instead of the eyepiece frame 70 shown in FIG. 6 and FIG.
A spring (elastic member) for urging the opening 2 is provided on the openable / closed wall surface, the prism 72 is loosely inserted into the eyepiece frame, and then the openable / closed wall surface is closed. 72 may be energized.

[0034]

As described above, according to the prism holding structure of the finder according to the present invention, a clearance between the prism and the frame is formed in the frame holding the prism, and the elastic member is inserted after the prism is loosely inserted into the frame. In order to urge the prism in the direction of the exit end face and fix it, the exit end face of the prism on which the subject image is formed at the time of mounting the prism is not rubbed and damaged by a field frame, etc. It can be arranged close to the field frame.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of a camera to which a finder prism holding structure according to the present invention is applied.

FIG. 2 is a perspective view of a finder unit 30 incorporated in the camera 10.

FIG. 3 is a perspective view of a first block and a second block of the finder unit 30;

FIG. 4 is an exploded perspective view of a first block of the finder unit 30.

FIG. 5 is an exploded perspective view of a second block of the finder unit 30.

FIG. 6 is a front view of a prism holding structure.

FIG. 7 is a plan view of a prism holding structure.

FIG. 8 is a structural view of a finder visual field switching mechanism.

[Explanation of symbols]

 36 ... Objective lens 70 ... Eyepiece frame (frame) 72 ... Prism 72E ... Prism exit surface 74 ... Eyepiece 73 ... Prism pressing plate (elastic member) 75 ... H field frame 76 ... CP field frame d ... Clearance

Claims (1)

(57) [Claims] 1. An image of a subject that has passed through an objective lens is formed on an exit end face of a prism, a field of view is regulated by a field frame disposed close to the exit end face of the prism, and the subject image is observed via an eyepiece. in the viewfinder of, the frame body for holding the prism, loosely inserted the prism
A prism housing with the largest possible size is formed.
It is, between said prisms loosely inserted into the frame member the frame member
The inserted elastic member clearance formed
Prism holding structure of the viewfinder, wherein said biasing the prism on the exit end face direction, and holds the exit end face of the prism is adjacent to the field frame.