Apparatus for driving mirror of camera

A mirror driving apparatus for a camera which rotatably drives a mirror between two predetermined position, by an elastic restoring force stored in a mirror biasing member, including an engaging device which retains an elastic restoring force in the mirror biasing member, and a disengaging and shock absorbing spring which elastically biases the engaging device in a disengaging direction thereof when the mirror is in one of the predetermined position. The disengaging and shock absorbing spring biases the mirror in a direction to stop the same immediately before the movement of the mirror is completed when the mirror is moved to the other of the predetermined position by the elastic restoring force of the mirror biasing member.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an apparatus for driving a mirror in a 
camera, such as a single lens reflex camera. 
2. Description of Related Art 
A known single lens reflex camera is provided with a quick-return mirror in 
a mirror box of a camera body. The quick-return mirror is moved between a 
viewing position and a photographing position by a driving mechanism. The 
driving mechanism is constituted, for example, by a motor which moves the 
quick-return mirror upwardly, from the viewing position, toward the 
photographic position in which a picture can be taken. Alternatively, it 
is also known to provide an elastic biasing mechanism, such as a coil 
spring, which continuously biases the quick-return mirror toward the 
photographic position. With such a mechanism, the quick-return mirror is 
moved upwardly to the photographic position when the elastic restoring 
force is released, In such a known mirror driving means, the upward 
movement of the quick-return mirror is suddenly stopped at the 
photographic position. Accordingly, it is necessary to provide a shock 
absorbing mechanism, such as an elastic damper or a governor, to absorb 
the oscillation or vibration that occurs when the mirror is brought to a 
sudden stop. This prevents the associated elements from being deformed or 
broken. If a motor is used as the driving mechanism, a braking mechanism 
is necessary to brake the motor. However, conventional measures to absorb 
shock or oscillation, or to brake the motor are complex. 
SUMMARY OF THE INVENTION 
The primary object of the present invention is to provide a mirror driving 
apparatus of a camera in which shock, oscillation, or vibration of the 
quick-return mirror that occurs when the upward movement of the 
quick-return mirror is brought to a halt, can be effectively dampened or 
absorbed by a simple mechanism. 
To achieve the object mentioned above, according to the present invention, 
there is provided a mirror driving apparatus for a camera which drives a 
mirror, and is rotatably movable between two predetermined positions, by 
an elastic restoring force stored in a mirror biasing member. The mirror 
driving apparatus comprises an engaging mechanism for retaining the 
elastic restoring force in the mirror biasing member, and a disengaging 
and shock absorbing mechanism for elastically biasing the engaging 
mechanism in a disengaging direction thereof when the mirror is in one of 
the predetermined positions, and for biasing the mirror in a direction to 
stop the same immediately before the movement of the mirror is completed, 
when the mirror is moved to the other of the predetermined positions by 
the elastic restoring force of the mirror biasing member. 
With this structure, since the disengaging and shock absorbing means for 
elastically biasing the mirror engaging mechanism in the disengaging 
direction acts on the mirror before the movement of the mirror is 
completed, the mirror is biased in the stop direction thereby decelerating 
the mirror. Thus, the shock which would occur when the mirror is brought 
to a stop is absorbed or dampened. 
The present disclosure relates to subject matter contained in Japanese 
utility model application No. 03-95965 (filed on Sep. 9, 1991) which is 
expressly incorporated herein by reference in its entirety.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1 through 3 show a mirror driving apparatus in a single lens reflex 
camera according to an embodiment of the present invention. A main part of 
the mirror driving apparatus, according to the present invention, is 
unified in a mirror box. 
A quick-return mirror 21 is housed in a mirror box 12 provided in a camera 
body 11. The mirror box 12 is provided with a bottom wall and a pair of 
upright side walls projecting from the bottom wall at opposite ends 
thereof. The upper, front, and rear faces of mirror box 12 are open. The 
mirror 21 is secured to a mirror sheet 22. The mirror sheet 22 is pivoted, 
with respect to the mirror box 12, at its upper end about a shaft 23 
through a bearing 24. The mirror sheet 22 rotates about the shaft 23 to 
move the mirror 21 between a viewing position and a photographing 
position. The mirror sheet 22 is continuously biased toward the viewing 
position (i.e., downwardly) by a mirror returning spring 25 provided 
between the mirror box 12 and the mirror sheet 22. The mirror sheet 22 is 
provided on the side surface thereof with a mirror driving pin 26 which 
projects out of the mirror box 12 through a window 14 formed in the mirror 
box 12. 
Mirror box 12 is provided on the outer side wall surface thereof with a 
mirror elevating lever 31 which is pivoted with respect to the mirror box 
12 at a pivot shaft 32 so as to come into contact with the mirror driving 
pin 26. The mirror driving pin 26 and, accordingly, the mirror 21 and the 
mirror sheet 22, are moved to the photographic position against the force 
of mirror returning spring 25 by the rotation of the mirror elevating 
lever 31 in the upward direction (i.e., clockwise direction as shown in 
FIG. 1) to bring the mirror into the photographic position. 
Mirror elevating lever 31 comes into contact with a mirror elevating collar 
43 which is provided on a mirror driving lever 41 near the end thereof on 
the side opposite the mirror driving pin 26. The mirror driving lever 41 
is rotatably supported at the intermediate portion thereof, on the outer 
surface of the mirror box 12, through a shaft 42. A mirror driving spring 
(mirror biasing means) 44 is provided between an abutment 48a provided on 
the other end of the mirror driving lever 41 and another abutment 15 
provided on the mirror box 12 to continuously bias the mirror driving 
lever 41 in the mirror elevating direction (i.e., counterclockwise 
direction as shown in FIG. 1). 
Mirror driving lever 41 has an arm portion 45 which comes into contact with 
a charging lever 18 provided in the camera body 11. The charging lever 18 
is moved in a charging direction (i.e., right hand direction as shown in 
FIG. 1) by a charging device (not shown) upon winding a film, and is 
returned to the initial position after charging is completed. The mirror 
driving lever 41 is rotated in the charging direction, causing tension in 
the mirror driving spring 44. The rotation of lever 41 is done in 
association with the movement of the charging lever 18 in the charging 
direction, so that an abutment 46 of mirror driving lever 44 will engage 
an abutment 52 of an engaging lever 51 at the viewing position of the 
mirror 21 when the charging of the mirror is completed. 
Engaging lever 51 is rotatably supported on the mirror box 12 through a 
shaft 53 and is biased to rotate in a direction in which the abutment 52 
engages the abutment 46 of the mirror driving lever 41. The engaging lever 
51 is biased by a return spring 54 which is provided around the shaft 53. 
The engaging lever 51 has an engaging arm portion 55 extending from the 
shaft 53 in a direction different from the abutment 52. The front end of 
the engaging arm portion 55 is in contact with a driving arm portion 63 of 
a mirror disengaging lever 61 to be rotated in the disengaging direction 
by the mirror disengaging lever 61. 
Mirror disengaging lever 61 is provided between the mirror driving lever 41 
and the engaging lever 51 to rotate about a shaft 62 on the mirror box 12. 
The mirror disengaging lever 61 is biased in a predetermined direction by 
a disengaging and shock absorbing spring 65 provided around the shaft 62. 
Disengaging and shock absorbing spring 65 is a torsion type spring in which 
at a free end 65a thereof engages end 47a of an abutment 47 of the mirror 
driving lever 41 and free end 65b engages end 64b of an abutment 64 of 
mirror disengaging lever 61, to bias the mirror disengaging lever 61 in 
the disengaging direction, and biases the mirror driving lever 41 in a 
direction that moves the mirror to a raised position, when the mirror 
driving lever 41 is in the viewing position (FIG. 1). 
On the other hand, when the mirror driving lever 41 is in the photographic 
position (FIG. 3), the free ends 65a and 65b of the disengaging and shock 
absorbing spring 65 act on the mirror driving lever 41 and the mirror 
disengaging lever 61 in the opposite direction. In particular, the free 
end 65a engages the other end 64a of the free end 64 of the mirror 
disengaging lever 61 and abutment 65b engages with the other end 47b of 
the abutment 47 of the mirror driving lever 41 to bias the mirror 
disengaging lever 61 and the mirror driving lever 41 toward the engaging 
position and the downward position of the mirror, respectively. 
Mirror disengaging lever 61 is connected to a plunger 72 of an 
electromagnet (solenoid) 71 which is secured to the mirror box 12. The 
plunger 72 is normally retracted and attracted by a permanent magnet (not 
shown) to hold the mirror disengaging lever 61 in the engaging position. 
When the electromagnetic solenoid 71 is energized, the plunger 72 is 
projected due to the cancellation of magnetic force of the permanent 
magnet. That is, when the electromagnetic solenoid 71 is energized, the 
mirror disengaging lever 61 rotates in the disengaging direction and pulls 
the plunger 72 with the aid of elastic force of the disengaging and shock 
absorbing spring 65. 
Mirror driving lever 41 is associated with a shutter mechanism disengaging 
lever 81 and a diaphragm operating lever 91. The shutter mechanism 
disengaging lever 81 is pivoted with respect to the mirror box 12 through 
a shaft 82, and is provided on one end thereof with an association pin 83. 
Association pin 83 is fitted in an elongated hole 49 formed in the mirror 
driving lever 41. The shutter mechanism disengaging lever 81 disengages 
the shutter mechanism (not shown) in association with the rotation of the 
mirror driving lever 41 to move the mirror upwardly, so that shutter 
curtains (leading and trailing curtains) can be moved by the 
electromagnetic control. 
Diaphragm operating lever 91 is independently and rotatably supported by 
shaft 42 of the mirror driving lever 41 and is elastically connected to 
the mirror driving lever 41 through an association spring 93 provided 
around the shaft 42. In particular, the association spring 93, in a free 
state, engages at one end thereof an abutment 48b of the mirror driving 
lever 41 and at the other end engages an abutment 91b of the diaphragm 
operating lever 91. The diaphragm operating lever 91 bears against a stop 
16 provided in the mirror box 12 when a taking lens is not mounted to the 
camera body in the mirror charging position. When a taking lens is mounted 
to the camera body, the diaphragm operating lever 91 is rotated to a 
diaphragm open position by a diaphragm releasing plate (not shown) 
provided on the taking lens. When the mirror driving lever 41 is rotated 
in the direction to move the mirror upward, the diaphragm operating lever 
91 is rotated together therewith through the association spring 93 against 
the diaphragm releasing plate of the taking lens to reduce the diaphragm 
aperture. 
The upward movement of the mirror is effected as follows. 
When a release switch (not shown) is turned ON in the mirror charging 
position shown in FIG. 1, the electromagnetic solenoid 71 is energized and 
the mirror disengaging lever 61 is disengaged. Consequently, the mirror 
disengaging lever 61 is rotated in the disengaging direction 
(counterclockwise direction) by the spring force of the disengaging and 
shock absorbing spring 65. 
Rotation of the mirror disengaging lever 61 in the counterclockwise 
direction causes the driving arm portion 63 to come into contact with the 
association arm portion 55 of the engaging lever 51 to rotate the latter 
in the disengaging direction against the engaging lever returning spring 
54. Consequently, the abutment 52 is disengaged from the abutment 46 (FIG. 
2). As a result of the disengagement, the mirror driving lever 41 is 
rotated in the mirror elevating direction by the restoring force of the 
mirror driving spring 44. 
When the mirror driving lever 41 is rotated in the mirror elevating 
direction, the mirror elevating collar 43 comes into sliding contact with 
the mirror elevating lever 31 to rotate the same in the mirror elevating 
direction. The mirror elevating lever 31 is in sliding contact with the 
mirror driving pin 26 to rotate the mirror 21 and the mirror sheet 22 to 
the photographic position (upward direction) against the mirror returning 
spring 25. Consequently, the mirror 21 is moved upwardly until it comes 
into contact with the elastic stop 17 provided in the mirror box 12, at 
which point it is held in the photographic position (FIG. 3). 
When the mirror driving lever 41 is rotated to elevate the mirror, the free 
end 65a of the disengaging and shock absorbing spring 65 is moved in a 
direction to release the elastic restoring force (i.e., in a direction to 
decrease the angle defined between the free ends 65a and 65b) in 
accordance with the movement of the abutment 47. During the rotation, the 
free ends 65a comes into contact with the end 64a of the abutment 64 of 
the mirror disengaging lever 61 to bias the mirror disengaging lever 61 in 
the engaging direction (clockwise direction). The other free end 65b comes 
into contact with the other end 47b of the abutment 47 and is rotated in 
the direction to spread the free ends 65a and 65b immediately before the 
rotation is completed. 
The disengaging and shock absorbing spring 65 biases the mirror driving 
lever 41 in the elevational direction of the mirror when the mirror 
driving lever 41 is held in the viewing position. However, the biasing 
direction is reversed to bias the mirror driving lever 41 in the downward 
direction of the mirror at a position immediately before the photographic 
position. 
Consequently, the mirror driving lever 41 is subject to an elastic biasing 
force in the downward direction, and rotates the mirror disengaging lever 
61 in the return direction through the disengaging and shock absorbing 
spring 65, immediately before the upward movement of the mirror is 
completed. Thus, the shock and oscillation of the mirror driving lever 41 
which occur at the stoppage thereof can be reduced or damped. 
Upon completion of the upward movement of the mirror 21, the latter is held 
in the photographic position by the restoring spring force of the mirror 
driving spring 44 through the mirror driving lever 41 and the mirror 
elevating lever 31. 
Mirror disengaging lever 61 pushes the plunger 72 by the restoring force of 
the disengaging and shock absorbing spring 65 in the engaging direction, 
so that the plunger 72 is attracted by the permanent magnet to be held in 
the engaging position, whereby the engaging lever 51 is rotated by the 
restoring force of the engaging lever returning spring 54 to be held in 
the engaging position. 
If movement of the shutter curtains ends when the upward movement of the 
mirror is completed, charging lever 18 is driven in the charging direction 
by the charging device (not shown) to rotate the mirror driving lever 41 
in the direction corresponding to downward movement of the mirror, the 
mirror 21 is moved downward (in the clockwise direction) toward the 
viewing position by the restoring force of the mirror returning spring 25. 
During the rotation of the mirror driving lever 41 in the downward 
direction, the shoulder portion of the abutment 46 comes into sliding 
contact with the upper edge of the abutment 52 to rotate the engaging 
lever 51 in the disengaging direction against the biasing force of the 
engaging lever returning spring 54. 
Upon completion of charging, abutment 46 is disengaged from the upper edge 
of the abutment 52, so that the engaging lever 51 is rotated in the 
engaging direction to bring the abutment 46 into contact with the abutment 
52. Thus, the mirror driving lever 41 is returned to and held in the 
charging position shown in FIG. 1. 
As can be seen from the above discussion, according to the present 
invention, since the abutment 65b of the disengaging and shock absorbing 
spring 65 for biasing the mirror disengaging lever 61, which disengages 
the engagement of the mirror driving lever 41, comes into contact with the 
abutment 47 when the mirror driving lever 41 approaches the elevated 
position to brake the mirror driving lever 41, the latter and, 
accordingly, mirror 21, are suddenly decelerated by the elastic biasing 
force of the disengaging and shock absorbing spring 65, so that the shock 
and oscillation occurring at the stopping position of the mirror can be 
damped. 
As can be understood from the foregoing, according to the present 
invention, since the disengaging and shock absorbing means for elastically 
biasing the abutment means, which engages the mirror biasing member with 
an elastic restoring force, acts on the mirror to bias the same in the 
downward direction during the upward movement of the mirror immediately 
before the upward movement is completed, the shock and oscillation of the 
mirror which occurs when the mirror comes to a stop is prevented.