JPH0645947Y2 - Single-lens reflex camera mirror operation mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Technical Field) The present invention relates to a first mirror holding frame provided with a first mirror that is a semi-transmissive mirror that splits light incident from a lens into reflected light and transmitted light, A second mirror that reflects the transmitted light from the first mirror
The present invention relates to a mirror operation mechanism of a single-lens reflex camera having a second mirror holding frame provided with a mirror.

(Prior Art) In a single-lens reflex camera having a movable mirror for observation,
In order to make the release time lag as small as possible, the movable mirror is lifted out of the optical path of the taking lens at the time of release, and the bounce that occurs when the stopper stops the lift is made as small as possible.
As described above, in the single-lens reflex camera having the two mirrors, such a device is also applied to the second mirror.

In some conventional single-lens reflex cameras with two mirrors, pressing the release button causes the first
A second mirror holding frame that follows the first mirror holding frame as the mirror holding frame moves from an observation position located in the optical path of the taking lens to an ascending / descending position (also referred to as a shooting position) that ascends and separates from the optical path. The second mirror holding frame is guided by the second mirror actuating cam provided on the side wall of the mirror box, so that the second mirror holding frame is moved upward and away from the first mirror holding frame. Is overlapped at a predetermined position on the back surface of the. In this case, the bound of the second mirror holding frame overlapped with the predetermined position on the back surface of the first mirror holding frame at the lifted-off position is that the guide roller of the second mirror holding frame is the second mirror actuating cam on the side wall of the mirror box. It is pressed rigidly by.

In the mirror actuating mechanism disclosed in Japanese Utility Model Publication No. 60-30744 and Japanese Utility Model Publication No. 62-120746, the first mirror holding frame is lifted from the observation position located in the optical path of the taking lens and separated from the optical path. A second mirror holding frame that is driven so as to follow the first mirror holding frame as it moves to the detaching position and to be overlapped with a predetermined position on the back surface of the first mirror holding frame at the rising detaching position of the first mirror holding frame. At the overlapping position (also referred to as a closed position), the bounce is elastically pressed by colliding with a spring member provided as a stopper on the side wall of the mirror box.

(Problems to be Solved by the Invention) In the conventional rigid bounce prevention method as described above, the second mirror operation cam is provided unless the second mirror operation cam is provided at an appropriate position on the side wall of the mirror box. Therefore, the second mirror support frame arranged at the overlapping position cannot have a predetermined relative positional relationship with the back surface of the first mirror support frame arranged at the lift-off position.
The light entering from the viewfinder is not completely blocked by the second mirror and enters the optical path to cause fogging on the film. Therefore, it goes without saying that the second mirror actuating cam must be precisely machined.
The mirror actuating cam must be precisely located at the proper position on the side wall of the mirror box. Such precision processing and precision placement increase the manufacturing and assembly costs of the mirror actuating mechanism.

In the conventional elastic bounce prevention method as described above, unless the magnitude of the spring force of the spring member is set appropriately, the bounce of the second mirror support frame at the overlapping position cannot be sufficiently suppressed. On the contrary, it will be enlarged. The magnitude of the spring force applied by the spring member to the second mirror support frame changes depending on the size of the spring member itself and the relative position of the spring member as a stopper with respect to the side wall of the mirror box. In order to substantially suppress the bounding of the frame, it is necessary to precisely manufacture the spring member and position the spring member relative to the side wall of the mirror box. However, in practice, it is difficult to precisely set the spring force generated by the spring member in the manufacturing process of the spring member, and the spring force of the spring member cannot completely press the bound of the second mirror support frame, so the release is performed. The time lag does not get shorter.

The present invention has been made in view of the above circumstances, and an object of the present invention is to eliminate the need for precise processing and precise arrangement as in the above-described conventional example, and to have a simple structure and a movable mirror at an upper detached position, particularly It is an object of the present invention to provide a mirror operation mechanism for a single-lens reflex camera that can reliably prevent the bounce of two mirrors.

(Means for Solving the Problems) In order to achieve the above object, in a holding frame, a first mirror including a first mirror including a semi-transmissive mirror that splits light incident from a lens into reflected light and transmitted light. A mirror actuating mechanism of a single-lens reflex camera having a holding frame and a second mirror holding frame having a second mirror that reflects the transmitted light from the first mirror, has a second mirror holding mechanism at the end of the first mirror holding frame rising. (2) A cam member that has a cam surface that abuts on the mirror holding frame and that can be rotated and retracted after abutting, a restricting member that restricts downward operation of the cam member, and the cam member that presses the restricting member. A single or a plurality of elastic members urged in the direction and applied between the fixing member and at least the friction member to give the frictional force to the retreat of the cam member,
It is characterized in that it is provided with an end-of-rise stopper for the second mirror holding frame.

(Operation) In the mirror actuation mechanism of the single-lens reflex camera of the present invention, which is provided with the ascending end stopper configured as described above for the second mirror holding frame, at the ascending end of the first mirror holding frame. When the second mirror holding frame comes into contact with the cam surface of the cam member, the cam member is rotated in a direction away from the regulating member against the biasing force of the elastic member and the frictional force generated by the elastic member. . Here, the urging force of the elastic member and the frictional force generated by the elastic member absorb and absorb the impact force of the second mirror holding frame acting on the cam of the cam member, and at the end of the ascent of the first mirror holding frame. Bounce of the second mirror holding frame is reliably prevented.

The cam member that rotates in a direction away from the regulating member against the biasing force of the elastic member and the frictional force generated by the elastic member by the second mirror holding frame at the end of the rising of the first mirror holding frame, As described above, it is not necessary to precisely machine the second mirror actuating cam in the conventional rigid bounce prevention method, and the second mirror actuating cam can be moved to an appropriate position on the side wall of the mirror box.
There is no need to place it as precisely as a mirror-actuated cam.

(Embodiment) Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows a mirror actuating mechanism according to a first embodiment of the invention for a single-lens reflex camera.
The single-lens reflex camera is a semi-transparent mirror, not shown
It has a first mirror holding frame 10 to which a mirror is fixed,
The first mirror holding frame 10 extends from the upper end to both sides of the first mirror holding frame 10.
The rotation center shaft 12 is pivotally supported by a fixed base plate 14 constituted by both side walls of a mirror box (also referred to as a mirror box) 13 so as to be swingable with respect to the fixed base plate 14. The first mirror holding frame 10 is biased in the counterclockwise direction in FIG. 1 by a first mirror restoring spring (not shown), and is brought into contact with the first mirror angle adjusting pin 16 fixed to the fixed base plate 14. It is held at a position inclined by about 45 degrees as shown in FIG. 1 against the biasing force of the first mirror restoring spring (not shown). A plurality of photographing lenses (not shown) are located in front of the mirror box 13 (left side in FIG. 1) arranged in the main body of the single-lens reflex camera, and behind the mirror box 13 (right side in FIG. 1). The shutter means and the film are located on one side. Further, above the mirror box 13, light reflecting means such as a penta prism or a reflecting mirror is arranged. The first mirror (not shown) held by the first mirror holding frame 10 blocks the optical path from the taking lens (not shown) to the shutter means and the film at an inclined position as shown in FIG. The position of the 1-mirror holding frame 10 is the subject observation position.

The first mirror (not shown) transmits a part of the light 18 incident from the photographic lens (not shown) toward the shutter means and the film, and transmits the light other than the above part to the upper light reflecting means. The light-reflecting means reflects the light other than the above-mentioned part toward the finder (not shown).

A second mirror (not shown), which is a total reflection mirror for reflecting the light transmitted through the first mirror (not shown) toward the bottom wall of the mirror box 13 is fixed behind the first mirror holding frame 10 in the mirror box 13. A second mirror holding frame 20 is arranged, and the bottom wall is provided with, for example, a light receiving means for an exposure meter and a distance measuring element. The second mirror holding frame 20 has second upper end portions of both side walls concentrically extended from both side surfaces of the second mirror holding frame 10 to both sides.
Is swingably supported by the rotation center shaft 22 of the first mirror holding frame 10, and one of the upper ends of the both side walls extends to above the upper surface of the first mirror holding frame 10 and then faces the upper end of the first mirror holding frame 10. The guide pin support extending portion 23 is bent.
A guide pin 24 projecting outward is fixed to the extending end of the guide pin support extending portion 23, and the guide pin 24 projects into an opening 26 formed in a corresponding side wall of the mirror box 13. There is.

One end of a substantially U-shaped drive spring 28 is attached to the bending region of the guide pin support extending portion 23 on the one side wall of the second mirror holding frame 20, and the other end of the drive spring 28 is the second It is attached to one side wall of the first mirror holding frame 10 in the vicinity of the rotation center axis 22. The drive spring 28 generates an elastic force to bring both ends close to each other, and when the lower end of the second mirror holding frame 20 is largely separated from the back surface of the first mirror holding frame 10 as shown in FIG. The second mirror holding frame 20 is urged to rotate counterclockwise around the second rotation center shaft 22. The counterclockwise rotation of the second mirror holding frame 20 about the second rotation center shaft 22 is a fixed base plate in which the rear surface of the second mirror holding frame 20 is formed by one side wall of the mirror box 13. It is stopped by contacting the second mirror angle adjusting pin 30 fixed to 14. Here, the second mirror holding frame 20 resists the elastic force of the drive spring 28, and as shown in FIG.
Is held in a tilted position, in other words the second
The mirror holding frame 20 is held at a position separated from the first mirror holding frame 10 by approximately 90 degrees in the counterclockwise direction about the second rotation center axis 22. The second mirror (not shown) in the second mirror holding frame 20 is transmitted through the first mirror (not shown) in the first mirror holding frame 10 arranged at the subject observation position as shown in FIG. Partial light is reflected toward a light receiving means or a distance measuring element for an exposure meter provided on the bottom wall of the mirror box 13.

A mirror holding frame drive pin 32 protruding outward from one side wall of the first mirror holding frame 10 is also inserted into the opening 24 on one side wall of the mirror box 13, and the mirror holding frame drive pin 32 is also inserted. Is connected to a mirror driving means (not shown) outside the mirror box 13.

On the outer surface of the fixed base plate 14 that constitutes one side wall of the mirror box 13 in which the opening 24 is formed, the right end portion of the lower edge is formed as a gently curved cam surface 34 that is convex upward. A cam member 36 is disposed. The left end of the cam member 36 is the mirror box 13
It is rotatably supported on a rotation center shaft 38 fixed on one side wall of the cam member 36, and a rotation restricting pin 40 fixed on the one side wall is inserted into the right end portion of the cam member 36. A rotation restriction hole 42 is formed. Since the rotation restricting hole 42 has a larger diameter than the rotation restricting pin 40, the cam member 36 moves around the rotation center shaft 38 in a range where the peripheral edge of the rotation restricting hole 42 contacts the rotation restricting pin 40. The rotation restriction pin 40 constitutes a restriction member that restricts the rotation range of the cam member 36. While the cam member 36 is rotating in such a rotation range, the cam surface 34 is located above the guide pin 24 of the second mirror holding frame 20, and is located in the area corresponding to the opening 26. ing.

A torsion coil spring 44 is wound around the rotation center shaft 38, and both ends of the torsion coil spring 44 are engaged with the cam member 36 and the fixing pin 46 on the outer side surface of the fixed base plate 14 to fix the cam member 36. An elastic member that urges in the clockwise direction is configured. As shown in FIG. 2, the central spiral portion of the torsion coil spring 44 has one turn spaced apart from each other in the axial direction to form a compression coil spring in the axial direction. In the compressed state, the compression coil spring has its upper and lower ends abutted against the cam plate 36 and the stop plate 48 fixed to the upper end of the rotation center shaft 38, whereby the other end of the cam member 36 is abutted. A predetermined frictional force is generated between and the fixed base plate 14 of the mirror box 13. That said, this frictional force
It is not so large as to prevent the cam member 36 from rotating in the clockwise direction by the urging force of the.

In the mirror actuating mechanism according to the first embodiment of the present invention constructed as described above in detail, when the shutter release button (not shown) of the single-lens reflex camera is pressed, the mirror holding frame of the first mirror holding frame 10 is driven. The mirror driving means (not shown) connected to the pin 32 operates to rotate the first mirror holding frame 10 around the first rotation center shaft 12 against the biasing force of the first mirror restoring spring (not shown). Is rapidly rotated clockwise from the subject observation position in FIG. 1 upward.

The second mirror holding frame 20 connected to the first mirror holding frame 10 by the second rotation center shaft 22 has the guide pin 24 at the initial stage of the above-described clockwise rotation of the first mirror holding frame 10. Is brought into contact with the cam surface 34 of the cam member 36.
Here, the biasing force of the torsion coil spring 44 moves the cam member 36 in the clockwise direction more than the force of the substantially U-shaped drive spring 28 to rotate the second mirror holding frame 20 in the counterclockwise direction. Force to rotate and torsion coil spring 44
Since the total of the frictional force generated between the cam member 36 and the fixed base plate 14 by the central compression coil spring portion is much larger, the cam member 36 resists the biasing force of the torsion coil spring 44. Does not rotate counterclockwise. This causes the second mirror holding frame 20 to drive in a substantially U-shape by allowing the guide pin 24 to slide on the cam surface 34 while the first mirror holding frame 10 continues to rotate in the clockwise direction as described above. It starts rotating clockwise around the second rotation center shaft 22 against the biasing force of the spring 28, and goes toward the back surface of the first mirror holding frame 10.

When the second mirror holding frame 20 rotates around the second rotation center axis 22 toward the back surface of the first mirror holding frame 10,
The mounting position of the drive spring 28 on the mirror holding frame 20 is first.
After the drive spring 28 has a predetermined positional relationship with the mounting position of the drive spring 28 on the mirror holding frame 10, the drive spring 28 exerts its urging force in the direction in which the second mirror holding frame 20 faces the back surface of the first mirror holding frame 10. I will let you. The moment when the urging force generated by the drive spring 28 changes the action on the second mirror holding frame 20 as described above is called a speculation point.

That is, when the guide pin 42 is slidably contacted with the cam surface 34, the guide pin 42 is forcibly rotated in the clockwise direction around the second rotation center shaft 22 against the biasing force of the drive spring 28. The mirror holding frame 20 rapidly rotates in the clockwise direction by the urging force of the drive spring 28 after passing a predetermined point around the second rotation center axis 22, and rapidly moves to the back surface of the first mirror holding frame 10. approach. Such rapid rotation of the second mirror holding frame 20 causes
As shown in FIG. 3, the cam member 36 is separated from the cam surface 34.

When the second mirror holding frame 20 makes such a rapid rotation, the first mirror holding frame 10 has not yet reached its maximum raised position and is moved clockwise by the mirror driving means (not shown). It continues to rotate. First mirror holding frame
The guide pin 24 of the second mirror holding frame 20 already approaching the back surface of the 10 reaches the first mirror raising stopper 50 provided on the upper wall of the mirror box 13 at the lower end of the first mirror holding frame 10. Immediately before the collision, the cam surface 34 of the cam member 36 collides again. The impact force generated by this collision is due to the torsion coil spring 44 being the cam member.
The first mirror holding frame 10 does not cause a large bounce due to the collision because it is buffered by the turning force and the frictional force applied to the 36, and the second mirror holding frame 30 also does not cause a large bounce. Further, the extremely small bounce caused by the collision is immediately eliminated by the turning force and the frictional force.
After that, the first mirror holding frame 10 resists the turning force and the frictional force and is moved by the above-mentioned mirror driving means (not shown) to the first mirror holding frame 10.
It is further raised until it comes into contact with the mirror raising stopper 50. The first mirror lift stopper 50 in the state of being considerably decelerated.
The small bounce generated by the first mirror holding frame 10 that collides with the
The tendency of the second mirror holding frame 20 to bounce due to the extremely small impact force generated by the collision of the first mirror raising stopper 50 with the first mirror raising stopper 50 is immediately eliminated by the turning force and the frictional force applied to the cam member 36. Therefore, the above-mentioned first aspect of the present invention
In the mirror actuating mechanism according to the above embodiment, the release time lag can be minimized.

As shown in FIG. 4, the first mirror holding frame 10 which is in contact with the first mirror raising stopper 50 is completely separated from the optical path from the above-mentioned not-shown photographing lens to the shutter means and the film. 1 The position of the mirror holding frame 10 is called the ascending / descending position. When the first mirror holding frame 10 is arranged in the lifted-off position, the second mirror holding frame 20 has a biasing force from the torsion coil spring 44 given from the cam member 36 via the guide pin 24 and the first mirror holding frame 10. Of the first mirror holding frame 10 placed at the lifted-off position by surely overlapping the back surface of the first mirror holding frame 10 by the urging force of the drive spring 28 that is stretched between the second mirror holding frame 20 and the second mirror holding frame 20. The light that has entered the first mirror (not shown) from the viewfinder (not shown) via the light reflecting means (not shown) above the mirror box 13 is reliably prevented from entering the above-mentioned optical path.

FIG. 5 schematically shows a mirror actuation mechanism according to a second embodiment of the invention for a single lens reflex camera.
In the second embodiment, the same parts as those in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

In the second embodiment, the function of the cam surface 34 of the cam member 36 in the first embodiment is part of the peripheral edge of the opening 26 of the fixed base plate 14 which is one side wall of the mirror box 13. 34a and the cam surface 34b of the deformed cam member 36 '. That is, the part 34a of the peripheral edge of the opening 26 of the fixed base plate 14 comes into contact with the guide pin 24 of the second mirror holding frame 20 at the initial stage when the first mirror holding frame 10 starts to move from the subject observation position to the lifted-off position. A cam surface for driving the second mirror holding frame 20 against the biasing force of the substantially U-shaped drive spring 28 in the direction toward the above-mentioned thought point toward the above-mentioned overlapping position by contacting and sliding the guide pin 24. Is configured as. Further, the cam surface 34b of the cam member 36 'is on the rear surface of the first mirror holding frame 10 due to the biasing force of the drive spring 28 because the biasing force of the drive spring 28 has already passed the above-mentioned consideration point near the end of the raising operation of the first mirror holding frame 10. Second mirror holding frame that overlaps with
Abut the guide pin 24 of 20. Similar to the cam member 36 of the first embodiment, the cam member 36 'uses the biasing force of the torsion coil spring 44 and the frictional force between the cam member 36' and the fixed base plate 14 to move to the upward disengagement position. Bound of the first mirror holding frame 10 and arrival of the second mirror holding frame when the first mirror holding frame 10 arrives
Effectively buffers and suppresses 20 bounces.

FIG. 6 schematically shows a modified example of the frictional force generating mechanism that has generated the rotational frictional force on the cam member 36 or 36 'in the above-mentioned first and second embodiments.

In this modification, a disc spring 52 is attached to the rotation center shaft 38 between the cam member 36 or 36 'and the fixed base plate 14. The disc spring 52 presses the cam member 36 or 36 'toward the fixed plate 48 fixed to the protruding end of the rotation center shaft 38 to generate a rotational frictional force between the cam member 36 or 36' and the fixed plate 48. ing. In this modified example, it is not necessary that the spiral portion at the center of the torsion coil spring 44 is formed as a compression coil spring with one turn being axially separated from each other.

According to an experiment conducted by the inventor of the present application, it is the bounce amount and the bounce time of the second mirror holding frame that have a great influence on the release time lag in the mirror actuating mechanism having two movable mirrors. In the mirror actuating mechanism of the single-lens reflex camera of the present invention, as described in detail in the first and second embodiments, the cam member 36 or 36 'of the cam member 36 or 36' is moved when the first mirror holding frame 10 reaches the lifted-off position. Since the biasing force of the torsion coil spring 44 and the rotational frictional force generated by the cam member 36 or 36 'effectively buffer and restrain the bound of the second mirror holding frame 20, the release time lag can be reduced.

(Effect) As described in detail above, the mirror actuating mechanism of the single-lens reflex camera according to the present invention is provided with the first mirror including the semi-transparent mirror that splits the light incident from the lens into the reflected light and the transmitted light. In a mirror operating mechanism of a single-lens reflex camera having a mirror holding frame and a second mirror holding frame having a second mirror that reflects transmitted light from the first mirror, the mirror operating mechanism is provided at the end of the first mirror holding frame rising. A cam member that has a cam surface that abuts against the second mirror holding frame and that can be rotated and retracted after abutting, a restricting member that restricts downward operation of the cam member, and the cam member that presses the cam member against the restricting member. A second mirror holding frame end-up stopper composed of one or a plurality of elastic members applied between the fixing member and at least the elastic member for applying a frictional force to the withdrawal of the cam member. Is characterized by Bounds of the movable mirror, especially the second mirror in the ascending / descending position can be reliably prevented without requiring the precise processing and precise arrangement as in the above-mentioned conventional example, and having a simple structure.

[Brief description of drawings]

FIG. 1 is a side view schematically showing a state in which a first mirror holding frame is arranged at a subject observation position in a mirror actuating mechanism according to a first embodiment of the present invention for a single-lens reflex camera; 2 is a longitudinal sectional view schematically showing a rotary friction generating mechanism of a cam member by an elastic member in the first embodiment of FIG. 1; FIG. 3 and FIG. 4 are the first embodiment of FIG. FIG. 5 is a side view schematically showing the process in which the first mirror holding frame in the example rises from the subject observation position shown in FIG. 1 to the ascending / descending position; FIG. 5 shows this invention for a single-lens reflex camera. FIG. 6 is a side view schematically showing a state in which the first mirror holding frame is arranged at a subject observation position and a state where the first mirror holding frame is arranged at an ascending / descending position in the mirror actuating mechanism according to the second embodiment; In the first and second embodiments, a rotational frictional force is generated on the cam member. It is a longitudinal cross-sectional view which shows schematically the modification of the frictional force generation mechanism which arose. 10 …… First mirror holding frame, 12 …… First rotation center axis, 13
…… Mirror box, 20 …… Second mirror holding frame, 24 …… Guide pin, 28 …… Drive spring, 32 …… Mirror holding frame drive pin, 3
4,34a, 34b ...... Cam surface, 36 ...... Cam member, 40 ...... Rotation restriction pin (restriction member), 44 ...... Torsion coil spring (elastic member), 46 ...... Fixing pin, 52 ...... Disc spring (Elastic member).

Claims (1)

[Scope of utility model registration request] 1. A first mirror holding frame provided with a first mirror made of a semi-transmissive mirror for splitting light incident from a lens into reflected light and transmitted light, and a second mirror for reflecting transmitted light from the first mirror.
A mirror actuating mechanism of a single-lens reflex camera having a second mirror holding frame provided with a mirror, having a cam surface that abuts against the second mirror holding frame at the end of the first mirror holding frame rising, and A cam member capable of moving and retracting, a restricting member that restricts downward movement of the cam member, and a biasing force that presses the cam member against the restricting member to impart a frictional force to at least retracting the cam member. A mirror actuation mechanism for a single-lens reflex camera, comprising a single or a plurality of elastic members hung between the fixing member and a second mirror holding frame end stopper.