JP2801217B2 - camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a single-lens reflex camera in which a so-called reflex mirror is formed by a fixed transflective mirror.

[Related Art] Conventional single-lens reflex cameras employ a so-called quick-return mirror. At the time of photographing, the mirror structure retreats to the outside of the photographing optical path immediately before photographing, and immediately returns to the optical path after photographing is completed, and the subject is moved to the viewfinder optical system. It had a structure to guide light. However, due to the above structure, the finder image disappears during shooting, and the subject at the moment of shooting cannot be seen. Especially in sports, races, animal photographs, etc. where the subject moves fast, continuous shooting is performed. It was very difficult to shoot while following the subject while doing so, and sometimes missed a so-called critical moment.

Therefore, there is a single-lens reflex camera that can always observe the state of the subject with the finder even during shooting by dividing the photographic light beam into the finder system and the film surface direction, always using the mirror that guides the light beam to the finder system as a fixed semi-transmissive mirror. Were present.

However, in recent years, a single-lens reflex camera has a built-in auto-focus mechanism, and therefore, a first mirror device (main mirror) for obtaining a finder light beam, and a light beam that has passed through a semi-transmissive portion of the first mirror. A second mirror device (sub-mirror) for guiding the second mirror mechanism to the auto-focus detection device arranged on the lower surface of the mirror box, and further, the second mirror mechanism is rotatably supported by the first mirror device, and the second mirror mechanism is supported by the first mirror device. The first with the retreat of the first mirror out of the optical path
The mirror device swings so as to overlap with the mirror device.

Therefore, as described above, the camera of the semi-transmissive mirror type in which the first mirror device is fixed cannot retract the second mirror device.

However, in a conventional camera, there is known a camera in which the second mirror device (sub-mirror) is swingably supported on a film surface side on a lower surface of a mirror box of the camera body. The interference between the swing trajectories of the mirror device and the second mirror device is prevented by shifting the swing timing of the two mirror devices. Therefore, this cannot be realized if the first mirror device is fixed.

In order to swing the second mirror device while the first mirror device is fixed in the above-described method, for example, the swing branch of the second mirror device is separated from the first mirror device. However, this would increase the size of the camera itself. It is also conceivable that the swing fulcrum of the second mirror device is set to the photographic lens side to prevent interference with the first mirror device. However, in this case, the second mirror device receives the central transmitted light of the first mirror device. This means that the mirror portion of the mirror device cannot be retracted out of the imaging optical path.

[Means for Solving the Problems] Accordingly, in the present invention, a fixed first mirror for splitting a light beam from a photographing lens into reflected light in a finder direction and transmitted light in a film surface direction is provided. In a camera having a second mirror which reflects and guides transmitted light to a lower portion of the first mirror, a first lever holding the second mirror and a second lever rotatably supporting the first lever are provided. A second lever, a driving member for moving the second lever to a position to withdraw the light beam out of the photographing optical path during photographing, and a driving member for moving the second lever to the withdrawal position. A camera is provided with a mirror driving mechanism having a cam for swinging the first lever so as to be folded over the second lever.

[Embodiment] FIGS. 1 to 6 show an embodiment of the present invention, and show a cross section of a main part of a camera.

In the drawing, reference numeral 1 denotes a semi-transmissive film or glass surface, and a first mirror for dividing a light beam of a subject incident from a photographing lens in a finder system direction and a film surface direction, and 2 denotes a first mirror for bonding and holding the first mirror 1. The first mirror frame 3 is a first mirror holding member having a spring portion 3a for pressing the first mirror frame 2 against the shaft 4 and the adjustment shaft 5, and is supported rotatably on the shaft 3b. Fixed to Reference numeral 4 denotes an axis for receiving the first mirror frame 2, and although only one is shown in the figure, there are two right and left when the camera is viewed from the front. 5 is two shafts 4
At the same time, the angle of the first mirror can be adjusted by adjusting the amount of protrusion of the adjustment shaft 5 with the adjustment shaft receiving the first mirror frame 2 at three points. Reference numeral 7 denotes a second mirror which reflects and guides the light beam transmitted through the first mirror 1 in the direction of the distance measuring device 30, and reference numeral 8 denotes a second mirror as a first lever for bonding and holding the second mirror 7. The receiving plate 10 rotatably supports the second mirror receiving plate 8 on an axis 9, and an axis located on the photographing lens side.
A second mirror driving plate as a second lever rotatably supported by the camera body at 11, and a second mirror driving plate as described later
The mirror receiving plate 8 has a hole 10a for accommodating the second mirror 7 when the mirror receiving plate 8 is folded, a contact portion 10b that contacts the spring 12, and a shaft portion 10c that receives a force from the cam portion 40a of the mirror gear 40.
Reference numeral 12 denotes a coil-shaped spring for urging the second mirror and the driving plate 10 to a predetermined position during standby of the camera, and is wound around the shaft 11 to urge the second mirror driving plate in a counterclockwise direction. A stop dowel 13 contacts the second mirror driving plate biased by the spring 12 and is positioned at a predetermined position. A stop dowel 14 is supported by the camera body and contacts the dowel portion 8a of the second mirror receiving plate 8 to stand by the camera. In the state, the spring 15 applies a biasing force for rotating the second mirror receiving plate 8 in the clockwise direction in the figure. A spring 15 contacts the second mirror receiving plate 8 urged by the spring 14 to position the second mirror 7 at a predetermined position. Stop dowel for the camera body. 16
Is a cam portion formed on the camera body, which abuts on the shaft portion 8a of the second mirror receiving plate 8 when the mirror is stored, which will be described later, and regulates the movement of the second mirror receiving plate 8. Reference numeral 17 denotes a spring member fixed to the camera body. When the second mirror driving plate 10 and the second mirror receiving plate 8 are folded, the shaft member 8a of the second mirror receiving plate 8 is urged to rotate counterclockwise. Gives a biasing force. Reference numeral 18 denotes a group of front blades of a shutter, which covers the aperture of the camera and prevents the film 20 from being exposed to harmful light while the camera is on standby. 19 is a rear blade group of the shutter, 20 is a film for photographing, 21 is a focusing plate that forms an image after a light beam from the photographing lens is reflected by the first mirror 1, 22 is an image of the focusing plate 21 on the eyepiece lens 23. Leading pentaprism. 24 is a mount that detachably holds the taking lens.

FIG. 1 shows a standby state before photographing by the camera. The light beam that has passed through the photographing lens (not shown) is reflected by the semi-transmissive first mirror 1 in the reflected light beam B heading in the finder direction.
Is divided into transmitted light fluxes C traveling toward the second mirror 7. The light beam B forms an image on the focus plate 21 and the pentaprism 2
2. Through the eyepiece lens 23, the photographer can observe the subject image. The transmitted light flux C is reflected by the second mirror 7 and guided to the distance measuring device 30. The distance to the subject is calculated by a predetermined process, and a lens (not shown) is driven to perform focusing.

Next, the operation after the release will be described with reference to FIGS.

When the release operation of the camera is performed, the mirror down gear 40 (see FIG. 4) disposed on the camera body receives the force of the motor or the spring and starts rotating counterclockwise. As the rotation of the mirror down gear 40 advances, the cam 40 of this gear 40
a comes into contact with the shaft portion 10c of the second mirror driving plate 10, and the second mirror driving plate 10 starts to rotate clockwise around the shaft 11 against the force of the spring 12. When the second mirror driving plate 10 starts rotating clockwise (FIGS. 2 and 5), the shaft portion 8a of the second mirror receiving plate 8 comes into contact with the cam surface 16 formed on the camera body, and Of the mirror receiving plate 8 starts to rotate counterclockwise about the axis 9. When the rotation of the mirror down gear 40 further advances and the second mirror driving plate 10 is pushed down to a substantially horizontal position (FIG. 3,
(FIG. 6), the shaft portion 8a of the second mirror receiving plate 8 is in contact with the spring 17, and the second mirror receiving plate 8 receives the urging force of the counterclockwise rotation by the urging force of the spring 17; The mirror driving plate 10 and the second mirror receiving plate 8 are closed so as to be substantially folded (FIG. 3,
(Fig. 6). At this time, the rotation of the mirror down gear 40 is stopped, and the second mirror driving plate 10 and the second mirror receiving plate 8 are held at the lower part of the mirror box so as to be folded, and there is no one that blocks the light flux transmitted through the first mirror 1. The transmitted light beam C reaches the shutter leading blade group 18. Next, the shutter blade groups 18 and 19 run at predetermined intervals, and the shooting ends. At this time, the driving plate 10 and the second mirror receiving plate 8 are connected to the focus detecting device 30.
Since the shape is folded on top of the film, it also functions to prevent harmful reflected light from the focus detection device from reaching the film 20 during photographing.

When the photographing is completed, the mirror down gear 40 starts to rotate counterclockwise again, and the contact between the cam 40a and the shaft portion 10c is released (FIGS. 1 and 4). The second mirror driving plate 10 has a spring 12
Starts counterclockwise rotation with the force of
8a also returns to the state shown in FIG.

[Effect of the Invention] As described above, in the present invention, the support of the second mirror for guiding the transmitted light from the fixed first mirror downward is provided by the first lever and the second lever. At least two parts, the second lever is moved to the retracted position by the driving member during shooting, and the first lever is swung by the cam so as to be folded over the second lever, so that the camera is enlarged. Thus, it is possible to obtain the evacuation movement during shooting with the second mirror alone.

Further, by setting the rotation center of the second lever at the position on the photographing lens side, it is possible to reduce the size of the camera using the arrangement shape of the first mirror.

Also, in the present embodiment, the second mirror device is folded on the autofocus detection device at the time of photographing,
It has become feasible to realize a camera that can also prevent harmful reflected light from being generated by the autofocus detection device during shooting.

In the embodiment, the structure in which the autofocus detection device is arranged on the lower surface of the mirror box has been described. However, it is needless to say that the same effect can be obtained in a camera in which a photometric device for measuring the light amount is arranged.

[Brief description of the drawings]

FIGS. 1 to 6 show a camera embodying the present invention. FIGS. 1 to 3 are side views for explaining the operation of the camera, and FIGS. 4 to 6 are FIGS. 1 to 3. FIG.

Claims (2)

(57) [Claims] 1. A fixed first mirror for dividing a light beam from a photographing lens into a reflected light in a finder direction and a transmitted light in a film surface direction, and reflects the transmitted light to a lower part of the first mirror. A second mirror for holding the second mirror, a second lever for rotatably supporting the first lever, and a second lever for holding the second mirror. A driving member for moving the light flux to a position where the light beam retracts outside the photographing optical path, and folding the first lever with the second lever with the movement of the second lever to the retract position; Characterized in that a mirror driving mechanism having a cam for swinging is provided. 2. A camera according to claim 1, wherein the center of rotation of said second lever is set at a position on the taking lens side.