JPH10148874A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera capable of easily replacing a focusing screen and also accurately positioning the focusing screen (positioning the screen, in particular in an in plane direction). SOLUTION: As for the camera whose main body 1 is provided with a screen holding member 18 which is made movable between a set position of positioning the focusing screen 4 in the optical axis direction and an attaching/detaching position of attaching/detaching the focusing screen, the camera is provided with pressing means 22L and 19 for pressing the focusing screen 4 against abutting parts 22R and 2a installed on the camera main body when the screen holding member is moved from the attaching/detaching position to the set position, and for positioning the focusing screen in the in plane direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a camera having a replaceable focusing screen.

[0002]

2. Description of the Related Art Some cameras have a so-called superimpose display function of displaying a selected distance measurement field of view on a subject image in a viewfinder field of view. According to this superimposed display function, the image and the display are overlapped, and the "position" of the display and the "state" of the display are used as meanings such as "autofocus distance measurement field" and "focus", respectively. It is very intuitive to tell people.

As such a camera, for example, there is a camera proposed in Japanese Patent Application Laid-Open No. 4-345150.
In this camera, superimposed display is enabled by disposing a guest-host type liquid crystal display member between a pentaprism and a focusing screen.

By the way, in such a camera,
The difference between the display of the focusing screen and the display of the superimposed display member poses a problem. In view of this, Japanese Patent Application Laid-Open No. 6-148735 proposes a configuration in which the display of the display member indicates a wider area than the display of the focusing screen, and does not require high-precision positioning of the two.

On the other hand, as disclosed in, for example, Japanese Utility Model Publication No. 57-37132, a holding frame (screen holding member) for holding a focusing screen, and a set position for positioning the holding frame in the optical axis direction of the screen. And a hinge means for swingably supporting between a detachable position for attaching and detaching the focusing screen and an engaging means for engaging the holding frame at the set position to constitute a screen holding mechanism, thereby facilitating replacement of the focusing screen. Some cameras did. When such a screen holding mechanism is employed, the size (inside dimension) of the holding frame is often made somewhat larger than the outer size of the focusing screen so that the focusing screen can be smoothly attached to and detached from the holding frame.

[0006]

However, if the size of the holding frame is made larger than the external dimensions of the focusing screen, the focusing screen will play with respect to the holding frame. There is a problem that the focusing screen cannot be positioned in a plane perpendicular to the optical axis. In other words, the center of the display of the superimpose and the center of the display of the focusing screen are shifted,
At the same time, the quality of the viewfinder is greatly impaired, and the original function of notifying the user of the exact position on the screen cannot be performed.

In order to solve such a problem, Japanese Patent Laid-Open Publication No. Hei 8-54666 discloses a method in which a holding portion positioned at a set position is deformed by a pressing force of a spring or the like so that the holding portion is brought into contact with a focusing screen. Has been proposed to absorb backlash. However, in this configuration, since the rigidity of the holding frame cannot be increased, for example, when the holding frame is pressed against the camera body to perform the positioning of the focusing screen, it is hard to say that the positioning accuracy is high.

Therefore, the present invention makes it easy to replace the focusing screen by using the above-described screen holding mechanism, and to accurately perform the positioning of the focusing screen (particularly, the positioning in the screen plane direction). The purpose is to provide a camera that has been optimized.

[0009]

In order to achieve the above object, according to the present invention, there is provided a screen holder movable between a set position for positioning the focusing screen in the optical axis direction and a detachable position for attaching and detaching the focusing screen. In the camera in which the member is attached to the camera body, when the screen holding member moves from the attaching / detaching position to the set position, the focusing screen is pressed against the abutting portion provided on the camera body to position the focusing screen in the in-plane direction. A pressing means for performing the operation is provided.

That is, for example, an opening for projecting the abutting portion inward is provided in the screen holding member, and the screen holding member protrudes inside the holding member in the process of moving from the attaching / detaching position to the set position. As compared with the case where the outer periphery of the focusing screen is directly abutted on the abutting portion and the focusing screen is abutted on the abutting portion via the screen holding member,
The in-plane positioning of the focusing screen can be performed with high accuracy.

By performing superimposition display on the focusing screen positioned with high precision, a high-quality finder is provided in which the center of the superimposed display matches the center of the display on the focusing screen. The camera can be realized.

As the pressing means, a means attached to the camera body and protruding inside the screen holding member to press the focusing screen, or a focusing screen via a screen holding member movable in an in-plane direction of the focusing screen. What is necessary is just to use what presses independently and to use together.

When using a pressing means for pressing the focusing screen through the screen holding member,
The pressing means may also serve as a member for locking the screen holding member at the set position.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a camera according to a first embodiment of the present invention. In this figure, reference numeral 1 denotes a camera main body. Hereinafter, the left side in FIG. 1 is referred to as a front side of the camera main body 1, and the right side is referred to as a rear side of the camera main body 1.

Reference numeral 2 denotes a mirror box serving as a reference for a finder optical system fixed to the camera body 1. Reference numeral 3 denotes a mirror unit rotatable with respect to the mirror box 2, and reference numeral 4 denotes a focusing screen. This focusing screen 4 has a Fresnel lens 4
a, and has a matt surface 4b on the light exit surface. And
As shown in FIG. 5, a spot metering mark 4c and a partial metering mark 4d are engraved on the mat surface 4b.

Reference numeral 5 denotes a reflector which functions as a display member for superimposed display described later, and is fixed to the mirror box 2 with high accuracy. As shown in FIG. 4, five distance measurement field frames 5a to 5e are formed on the reflection surface 5g of the reflection plate 5.

Reference numeral 6 denotes a condenser lens, and reference numeral 7 denotes a pentaprism. 8a and 8b are eyepieces, 9
Is a protective glass. These components constitute a finder system.

Reference numerals 10 and 11 denote a photometric sensor and a photometric lens for measuring the luminance of the subject, respectively. The photometric sensor 10 and the photometric lens 11 can perform spot photometry for measuring an extremely narrow area in the center of the screen and partial photometry having sensitivity to the outside of the spot. Reference numeral 15 denotes a known focus detection unit, and reference numeral 16 denotes a shutter device. Reference numeral 17 denotes a mount fixed to the opening of the mirror box 2 and for mounting an interchangeable lens (not shown).

In the camera according to the present embodiment configured as described above, the photographing conditions such as the shutter speed, the aperture value, and the exposure correction amount located outside the subject visual field as shown in FIG. A viewfinder visual field having a display section (not shown) outside the visual field to be displayed is obtained. The subject field of view is obtained by arranging the reflecting plate 5 and the focusing screen 4 in the direction of the finder optical axis as shown in FIG.
c and 4d can be superimposed on the subject image for observation. The superimposed display can be performed by illuminating the ranging field frames 5a to 5e at appropriate times.

Here, the configuration of the illumination device for illuminating the distance measurement field frames 5a to 5e will be described with reference to FIG. Reference numeral 12 denotes a light projecting lens, and the light projecting lens 12 is disposed from the upper front portion to the upper portion of the pentaprism 7. Above the pentaprism 7, five Ls each containing therein a light emitting diode (hereinafter, referred to as an LED) as a light source are provided.
An ED package 13 (only the center package is visible in FIG. 1) and a mask 14 are attached. The wavelength of this LED is in the visible light range.

The light emitted from the LED package 13 is stopped down by an opening provided in the mask 14 and enters the light projecting lens 12. The light projecting lens 12 is composed of a large number of divided surfaces, and the surface 12 a is an incident surface of a light beam from the LED package 13. The light beam entering the light projecting lens 12 from the surface 12a is totally reflected by the surface 12b and the subsequent surface 12c, and reaches the lens portion 12d at the front end with almost no loss. The lens part 12d at the tip of the light projecting lens 12 is composed of three lens parts (only the center lens is visible in the cross-sectional view). The light flux emitted from the LED package 13 passes through the lens part 12d. Only the effective light flux is obtained.

The lens portion 12a has the function of placing the above-mentioned reflecting plate 5 and the mask 14 in a projection relationship, and the light beam emitted from the lens portion 12a is condensed, and the pentaprism 7 is projected from the surface 7a.
Incident inside. After that, the light exits from the surface 7b of the pentaprism 7 and reaches the distance measurement field frame 5a provided on the lower surface of the reflection plate 5 through the condenser lens 6. Then, only the light beam reflected by the distance measurement field frame is visually recognized through the pentaprism 7, the eyepieces 8a and 8b, and the protective glass 9.

The five LEDs correspond to the five ranging field frames 5a to 5e, and the luminous flux emitted from the LEDs is guided through the projection lens 12 to the respective ranging field frames.
Therefore, it is possible to control lighting / non-lighting for each ranging field frame.

By the way, in the camera of this embodiment, a focusing screen having photometric marks 4c and 4d engraved at the center as shown in FIG.
Alternatively, it is possible to select and mount the one (4 ') in which the grid is engraved as shown in FIG. However, when any of the focusing screens 4 and 4 'is selected, as shown in FIGS. 7 and 8, the distance measurement field frames 5a to 5e formed on the reflector 5 and the focusing screens 4 and 4' are used.
It is necessary that the photometric marks 4c and 4d formed on the 4 'and the grid are properly overlapped.

Therefore, in the camera of the present embodiment, the focusing screens 4, 4 'can be easily exchanged, and the mounted focusing screens 4, 4' can be easily replaced.
Has a screen holding mechanism that can accurately position the camera with respect to the distance measurement field frames 5a to 5e, that is, the camera body 1 (mirror box 2).

Reference numeral 18 denotes a holding frame (screen holding member) in which the focusing screen 4 is removably mounted. A hinge portion 18a bent into a horizontal U-shape is provided at a rear end portion of the holding frame 18, and a hook portion 18c is formed at a front end portion. Near the shutter side of the mirror box 2, a hinge portion 18a is provided.
Is fixedly mounted.

Thus, the holding frame 18 is positioned between the reflector 21 and the set position (position shown in FIG. 1) where the mounted focusing screen 4 approaches the reflector 5 in the finder optical axis direction around the axis 21. It is possible to swing between a focusing screen 4 and an attaching / detaching position (a position shown in FIG. 3A) which forms a space for attaching / detaching the focusing screen 4. The holding frame 18 is slidable in the in-plane direction of the mounted focusing screen 4 by sliding the hinge portion 18a in the radial direction with respect to the shaft 21.

A leaf spring 18 is provided on the bottom of the holding frame 18.
The leaf spring 18b presses the focusing screen 4 mounted on the holding frame 18 against a reference surface 2b (see FIG. 3) of the mirror box 2 serving as a reference for focusing, as described later.

Reference numeral 19 denotes a leaf spring, which engages with a hook 18c of the holding frame 18 located at the set position to lock the holding frame 18 at the set position and also pushes the holding frame 18 backward. It is a pressing member. 20 is the mount 17
The cover is formed inside and is fixed to the mirror box 2 so as to cover the locking and pressing member 19.

As shown in detail in FIG. 2, a fixing pin 22R (abutting portion referred to in the claims) is integrally attached to one of the inner surfaces of the mirror box 2, and the other side. The movable pin 22L is attached by being biased by a spring 23 in a direction protruding inside the mirror box 2 at a position facing the fixed pin 22R.

Next, the loading procedure of the focusing screen 4 and the movement of the holding mechanism in the camera configured as described above will be described. First, as shown in FIG. 3A, in a state where the holding frame 18 is lowered to the attaching / detaching position,
Is loaded with a focusing screen 4. Note that FIG.
As shown in FIG.
8, the holding frame 18 is made large so as to have play in the front, rear, left and right with respect to the focusing screen 4. In this state, the holding frame 18
Is slid forward by its own weight to a position where the shaft 21 abuts on a portion corresponding to the bottom of the horizontal U-shaped groove of the hinge portion 18a.

The focusing screen 4 is held by the holding frame 18.
When the holding frame 18 is pushed up toward the set position as shown in FIG. 3B, the tips of the fixed pin 22R and the movable pin 22L are connected to the opening 18e formed in the side surface of the holding frame 18. Through the inside of the holding frame 18. The left and right side surfaces (outer peripheral portions) of the focusing screen 4 abut against the tips of the fixed pin 22R and the movable pin 22L protruding inside the holding frame 18, and the left and right sides inside the holding frame 18 along the curved surfaces of these tips. (In-plane direction)
Go to Thereby, the focusing screen 4
Is positioned in the left-right direction while being pressed by the fixed pin 22R by the movable pin 22L. At the same time, the hook portion 18c of the holding frame 18 is
9 against the lower slope.

From this state, the holding frame 18 is further moved from FIG.
As shown in (C), when the push-up is performed, the hook portion 18c rises along the slope of the locking / pressing member 19 and the locking / pressing member 19 is elastically deformed. Is generated, and the holding frame 18 is slid backward (in the direction of the arrow in the figure) with respect to the mirror box 2 by this elastic force. Note that the hinge 1
A gap is formed between the shaft 21 and a portion corresponding to the bottom of the U-shaped groove 8a.

When the holding frame 18 slides rearward with respect to the mirror box 2, a projection formed on the mirror box 2 passes through an opening 18 f formed at the rear end of the holding frame 18. Butting part in the range)
2a protrudes inside the holding frame 18, and the rear end of the focusing screen 4 receiving the elastic force of the locking and pressing member 19 via the front end of the holding frame 18 abuts on the projection 2a. Thus, the focusing screen 4 is positioned in the front-rear direction while being pressed by the projection 2a by the locking and pressing member 19.

After the positioning of the focusing screen 4 in the in-plane direction, that is, the left-right direction and the front-back direction is completed, the holding frame 18 is further pushed up.
As shown in FIG. 2, the hook portion 18c engages with the locking portion 19a of the locking and pressing member 19, and the holding frame 18 is locked at the set position. At the same time, the focusing screen 4 is pressed against the reference surface 2b of the mirror box 2 by the urging force of the leaf spring 18b, and positioning in the direction of the finder optical axis is performed.

That is, when the focusing screen 4 is replaced or the like, the focusing screen 4 is loaded into the holding frame 18 and the holding frame 18 is pushed up toward the set position. First, the pins 22R and 22L are used to perform horizontal positioning. Next, positioning in the front-rear direction is performed by the projection 2a and the locking and pressing member 19, and finally positioning in the finder optical axis direction is performed by the reference surface 2b and the leaf spring 18b. In this way, the focusing screen 4 is accurately positioned with respect to the mirror box 2 in the in-plane direction and the optical axis direction.

Therefore, according to the present embodiment, not only can the holding frame 18 be lowered to the attachment / detachment position to easily attach / detach the focusing screens 4, 4 'to / from the holding frame 18, but also the attachment / detachment of the holding frame 18 can be performed. The focusing screens 4 and 4 ′ can be accurately and coaxially superimposed on the reflector 5 only by a simple operation of pushing up from the position to the set position.

In this embodiment, a case has been described in which the fixing pin 22R, which is separate from the camera body 1, is attached to the camera body 1 (mirror box 2). May be integrally formed.

In the present embodiment, the focusing screen 4 is directly pushed by the movable pin 22L in one of the in-plane directions of the focusing screen 4, and the engaging / pressing member 19 pushes the focusing screen 4 in the other direction via the holding frame 18. Although the case of pressing the focusing screen 4 has been described, direct pressing by the movable pin may be performed in both directions, or pressing via the holding frame 18 may be performed in both directions.

[0040]

As described above, according to the present invention, in the process of moving the screen holding member from the attaching / detaching position to the setting position, the focusing screen is brought into direct contact with the abutting portion projecting inside the holding member. Therefore, the in-plane positioning of the focusing screen with respect to the superimposed display section can be performed with higher accuracy than when the focusing screen is brought into contact with the abutment section via the screen holding member.

By performing superimposed display on the focusing screen positioned with high precision, a high-quality finder is provided in which the center of the superimposed display matches the center of the display on the focusing screen. A camera can be realized.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an outline of a camera according to a first embodiment of the present invention.

FIG. 2 is a plan view of a screen holding mechanism of the camera.

FIG. 3 is an operation explanatory view of the screen holding mechanism.

FIG. 4 is a plan view showing a reflector for superimposed display of the camera.

FIG. 5 is a plan view of a focusing screen of the camera.

FIG. 6 is a plan view of a focusing screen of the camera.

FIG. 7 is a plan view showing a finder visual field in the camera.

FIG. 8 is a plan view showing a finder visual field in the camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camera main body 2 Mirror box 3 Mirror mechanism 4 Focusing screen 5 Reflector 6 Condenser lens 7 Pentaprism 8 Eyepiece 9 Protective glass 10 Photometric sensor 11 Photometric lens 12 Floodlight lens 13 LED package 14 Mask 15 Focus detection unit 16 Shutter device 17 Mount 18 Holding frame 19 Locking and pressing member 20 Cover 21 Shaft 22R, 22L Pin 23 Spring

Claims (6)

[Claims] 1. A camera in which a screen holding member movable between a set position for positioning a focusing screen in an optical axis direction and a detachable position for attaching and detaching the focusing screen is attached to a camera body. A camera having a pressing means for pressing the focusing screen against an abutting portion provided on the camera body to move the focusing screen in an in-plane direction when moving from the attachment / detachment position to the set position. . 2. The camera according to claim 1, wherein the screen holding member has an opening for projecting the abutting portion inward. 3. The camera according to claim 1, wherein the pressing unit is attached to the camera body, protrudes inside the screen holding member, and presses the focusing screen. 4. The screen holding member is movable in an in-plane direction of the focusing screen, and the pressing unit presses the focusing screen against the abutting portion via the screen holding member. The camera according to claim 1 or 2, wherein: 5. The camera according to claim 4, wherein said pressing means also serves as a member for locking said screen holding member at said set position. 6. The camera according to claim 1, wherein the screen holding member is mounted near a display member for displaying a superimposed image.