JPS62287230A - Driving for mirror of camera - Google Patents

Abstract

PURPOSE:To reduce the collision speed of a mirror against a stopper at the lowermost descent and to shorten a bounce time by reducing the speed to half in the latter half of the downward movement of the mirror only by setting the shape of the cam of a quick-return mirror mechanism which uses a motor as a driving source. CONSTITUTION:A cam memory 9 is formed of the 1st cam surface 9a which moves up a mirror member 11, the 2nd cam surface 9b which holds the mirror member 11 at an elevation position, and the 3rd cam surface 9c which lowers the mirror member 11, and the 3rd cam surface 9c is so shaped the mirror member 11 is lowered speedily in the front half of downward movement and reduced in speed in the latter half according to the rotating speed of the motor 1. The mirror member 11 moves down speedily in the front half part by the cam surface 9c of the cam member 9, but is reduced in speed almost at the lowermost position of the latter half part, so the time of the convergence of bounce of the mirror member 11 at the lowermost position is shortened.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a quick return mirror drive device for a camera.

<Prior Art> Conventionally, a camera's mirror drive device accumulates spring force during manual winding operation, and the mirror is raised and lowered by releasing the locking member using the 7-Yanotare reset operation. This power source is now being replaced by a motor, and the mirror can now be raised and lowered by the same means by accumulating spring force using the motor's body power during winding.

However, this motor drive means has a drawback in that a load is applied to the motor that causes the spring to accumulate which is larger than the load for operating the mirror.

Therefore, recently, the driving force of the motor is directly transmitted to the mirror to raise the mirror while a mirror lowering spring is accumulated, and the mirror is lowered by releasing the locking member.

<Problems to be Solved by the Invention> However, according to this method, there is a problem that the lowering due to the spring force causes bounce after contacting the stopper, which delays the timing of operations such as photometry.

Further, in order to prevent bounce, a method of separately providing a bounce prevention member has been taken, but this has the disadvantage that the structure becomes complicated and expensive.

The present invention eliminates the drawbacks of the conventional example described above, has a simple structure by setting the cam shape, shortens the bouncing time when the mirror is lowered, and also reduces vibration and impact noise.The mirror is driven by a camera motor. The purpose is to provide equipment.

<Means for Solving the Problems> The configuration of the present invention for achieving the above-mentioned object will be explained using FIGS. 1 and 2 corresponding to embodiments. a drive motor 1, a cam member 9 rotated by the drive motor 1 via reduction transmission gear trains 2 to 8, a rotatable mirror member 11 that guides a light beam passing through a photographic lens to a finder, and the cam member. a lever member 10 that transmits the motion of 9 to the mirror member 11;
The cam member 9 has a mirror return spring 13 that urges the mirror member 11 in a direction crossing the optical axis, and the cam member 9
1, a second cam surface 9b that holds the mirror member 11 in the raised position, and the mirror member 1.
1. The third cam surface 9c is formed of a third cam surface 9c for lowering, and the lowering operation of the mirror member 11 is rapidly performed in the first half of the third cam surface 9c in accordance with the rotation speed of the motor 1, and the second half of the third cam surface 9c is formed of a third cam surface 9c for lowering. The shape is such that the speed is regulated.

Operation> First, the power is turned on by operating a not-shown button, the motor 1 rotates, and the cam member 9 rotates clockwise via the reduction gear trains 2 to 8.

When the cam member 9 rotates, the lever member 10 is rotated counterclockwise by its cam surface 9a, the mirror member 11 rises, and the force of the spring 13 is accumulated, and when the lever member 10 comes into contact with the cam surface 9b, the power is turned off. It is turned off, the rotation of the motor 1 is stopped, and the mirror member 11 is held at the highest position.

Then, the shutter (not shown) runs, the shutter 1 rotates again in response to the photographing end signal, the cam member 9 further rotates clockwise, and the lever member 10 moves the cam surface 9 of the cam member 9.
c, the lever member 10 rotates clockwise, and the force of the spring 130 accumulated in the front half and the mirror member 11
The mirror member 11 descends due to the gravity of the mirror member 11, and in the latter half of the mirror member 11, the mirror member 11 is regulated by the lever member 10 and reaches the lowermost position while decelerating, and the descending movement is completed.

Therefore, the downward movement of the mirror member 11 is caused by the cam member 9
The mirror member 1 rapidly descends in the first half due to the cam surface 9C, but is decelerated near the lowest position in the second half.
1 can shorten the time it takes for the bounce to subside at the lowest position.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4.

The motor 1 that serves as the mirror drive source built into the camera body is
Gears 3, 4, and 5 of the reduction transmission system are controlled by gear 2 at the output end.
, 6.7, a cam member 9 coaxial with the gear 8 is rotated clockwise in the drawing. A lever member 1 having an arm portion 10a that abuts and follows the cam surface of the cam member 9.
0 is pivotably supported by a structural member of the camera body (not shown), and another arm portion 10b of this lever member 10 is adapted to push up a mirror flip-up bin 12 fixed to a mirror member 11. The mirror member 11 has the lowest IQ
At lf, the light beam passing through the photographic lens is biased downward by a spring 13 held by a pin 14, and in the focused state is regulated by a stopper bin 15 to the lowest position intersecting the optical axis at 45°.

The shape of the cam member 9 includes a cam surface 9a for raising the mirror member 11, a cam surface 9b for holding the mirror member 11 at the highest position, and a cam surface 9C for lowering the mirror member 11.
and the photographing end stop surface 9d, especially the cam surface 9.
Regarding C, considering the rotation speed of the motor 1, the arm portion 10 of the lever member 10 is
The slope of the cam displacement is set large so that the movement of b matches the movement of the mirror member 11 due to the spring constant of the spring 13 and gravity, and the cam displacement is set so that the movement of the mirror member 11 is regulated and decelerated in the latter half. Either it is set to zero or the slope is set small.

The operation of the present embodiment described above is as follows: First, when a shutter button (not shown) is pressed, the power is turned on, the motor 1 rotates, the cam member 9 rotates clockwise as shown by the arrow, and the cam surface 9
At step a, the mirror member 11 is raised via the lever member 10 and the force of the spring 13 is accumulated, and when the arm portion 10b of the lever member 10 comes into contact with the cam surface 9b, the power is turned off by a switch (not shown) and the motor is turned off. 1 stops rotating,
As shown in FIG. 3a, the mirror member 11 stops at the highest position.

Then, the shutter (not shown) runs, the motor 1 rotates again in response to the photographing end signal, and when the cam member 9 further rotates clockwise, the cam surface 9C causes the lever member 1 to
0 rotates clockwise, and in the first half the mirror member 11 is not regulated by the movement of the lever member 10 and descends due to the force of the spring 13 and gravity, but in the second half the bin 12 fixed to the mirror member 11 is moved by the lever. The mirror member 11 descends under deceleration while being regulated by the arm portion 10b of the member 10, comes into contact with the stopper bin 15, and the descent of the mirror member 11 is completed as shown in FIG.

By the way, regarding the downward movement of the mirror member 11, if the bottle 12 is not restricted at all by the arm portion 10b of the lever member 10, the locus of the mirror member 11 will rapidly fall as shown by the dashed-dotted line in the operation characteristic diagram of FIG. , comes into contact with the stopper bin 15 for the first time at time t1, and the bounce stops at time t2. However, in this embodiment, by decelerating the mirror member 11 in the latter half, the stopper bin 15 comes into contact with the stopper bin 15 for the first time.
Since the speed at the time t when the ball makes contact with the ball 5 is braked, the time t2 for the bounce to subside is shortened.

The shape of the cam surface 9C of the cam member 9 is such that in the first half, the trajectory of the arm portion 10a of the lever member 10 due to the mirror lowering movement due to the spring constant of the spring 13 and gravity is the same as the cam surface 9 of the cam member 9.
The arm portion 10a may be set to contact the cam surface 9C midway without following C, and the mirror member 11 may be decelerated at the rear half of the cam surface 9C.

<Effects of the Invention> As explained above, the present invention can reduce the speed of the mirror at its lowest position by simply setting the shape of the cam of the quick return mirror drive mechanism using the motor as the drive source, and by decelerating the second half of the mirror's descent. It has the effect of softening the impact speed against the stopper and easily shortening the pounding time.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a configuration diagram of main parts of an embodiment of a camera mirror drive device according to the present invention, FIG. 2 is an enlarged view of the shape of a cam member thereof, and FIG.
The figures are explanatory diagrams of the operation of the mirror member, where (a) shows the highest position and (b) the lowest position, and FIG. 4 is a diagram showing the operational characteristics of the mirror member. DESCRIPTION OF SYMBOLS 1... Motor, 2-8... Reduction gear train, 9... Cam member, 9a-9d... Cam surface, 10... Lever member, 11-... Mirror member, 12... Mirror bounce Uppi/
, 13... Spring, 15... Stopper pi/Fig. 1 8 Gear Fig. 2 Fig. 3 (a) (b)

Claims (1)

[Claims] 1. A drive motor built into the camera, a cam member that is rotated by the drive motor via a reduction transmission gear train, a mirror member that guides the light beam passing through the photographic lens to the finder, and a mirror member that controls the movement of the cam member. and a mirror return spring that urges the mirror member in a direction intersecting the optical axis. The third cam surface is formed of a second cam surface for holding the mirror member at a lower position, and a third cam surface for lowering the mirror member, and the front half of the third cam surface has a large slope for rapidly lowering the mirror member. 1. A mirror drive device for a camera, characterized in that the rear half has a slope smaller than the first cam displacement to regulate and slow down the downward movement of the mirror member.