JP2000002905A - Brake device for focal plane shutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake device having stable braking force. SOLUTION: The brake member 30 is rotatably supported on a position for cushioning in terms of the traveling path of a blade driving member 13 driving a blade 11, the member 13 gives the member 30 torque in a left-turning direction after the engaging pin 18 of the member 13 is engaged with an arm 32, and the kinetic energy of the member 13 is converted to heat energy generated by the member 30 and attenuated. A cushioning member 34 exerts its influence of elastic force on a circular projecting piece formed on the member 30 when the projecting piece abuts on the member 34 having the elastic force; however, since the direction of the elastic force faces to the direction of the rotating shaft 31 of the member 30, the elastic force exerted by the member 34 to the member 30 does not generate torque with respect to the member 30, and the risk for reverse rotation by rebounding can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device for stopping a focal plane shutter at an advance end thereof, and more particularly, to a brake device for minimizing rebound at an advance end of a focal plane shutter.

[0002]

2. Description of the Related Art As is well known, a focal plane shutter releases a front curtain, which is in a state where an opening for exposure is blocked in an initial setting state, toward a state where the opening for exposure is opened, and then performs initial setting. One exposure operation is performed by releasing the rear curtain in the state where the exposure opening is opened so as to block the exposure opening. In this type of focal plane shutter, the time difference from the release of the first curtain to the release of the second curtain is equivalent to the exposure second, but the exposure unevenness in the image frame at high speed is reduced, or the flash synchronization speed is reduced at high speed. It is desired that the curtain speed itself be increased in order to achieve this. When the curtain speed is increased, the impact at the advance end of the operating member including the blade member also increases. Therefore, the impact is efficiently absorbed and various operating members are stopped at the advanced end. An excellent brake device is required. Specific examples of this type of brake device include, for example, Japanese Utility Model Laid-Open Publication No. Sho 56-88227 and Japanese Utility Model Laid-Open Publication No. 1-177736. In Japanese Utility Model Laid-Open Publication No. Sho 56-88227, the drive pin 6 at the tip of the support arm drive lever 4 for driving the shutter blade support arm 3 slides into the rubber cushioning member 7 at an angle of entry of 30 degrees or less, and rebounds. This shows that braking is applied while deterrent is being performed. In Japanese Utility Model Application Laid-Open No. 1-177736, the final contact surface formed on the blade drive arm 11 is finally
Assuming that the brake device comes into contact with and stops, the front contact surface that contacts the cushioning member is formed on the blade drive arm before the final contact surface contacts, and the front contact surface is the cushioning member. 3 shows that a part of the kinetic energy is absorbed in the process of rotating. In addition, Kaikai 4
No. 61325 discloses that the front contact surface comes into contact with the cushioning member before the final contact surface to absorb energy, and that the actual contact surface is 1-1.
No. 77736, but discloses that the outer periphery of the cushioning member is formed of a rigid body to improve durability. However, among the above methods, in the case of Japanese Utility Model Application Laid-Open No. 56-88227 and Japanese Utility Model Application Laid-Open No. 1-177736, the driving member for driving the blade member is rubbed directly with the buffer member at the advanced end. Therefore, it may be difficult to obtain a sufficient braking force. Also, Japanese Utility Model Laid-Open No. 1-177736 and Japanese Utility Model Laid-Open No. 4-613.
In the case of No. 25 or the like, since it finally comes into contact with the final contact surface and stops, a bounce at the advance end may occur.

In order to obtain a stable braking force, instead of directly stopping the driving member, a braking member having, for example, a frictional resistance is provided on a traveling path of the driving member, and a process of operating the braking member is performed. It is desirable to convert the kinetic energy of the driving member into frictional heat energy of the braking member. FIGS. 7, 8 and 9 show an example of a focal plane shutter brake device having such a braking member. In the figure, reference numeral 1 denotes a blade drive lever connected to a shutter blade (a front blade or a rear blade may be used) not shown, and the blade drive lever 1 is swingably supported by a shaft 2 on the main plate. The blade drive pin 1a implanted in the section penetrates an arc-shaped slot 3 formed in the base plate and engages with a shutter blade (not shown). Therefore, by rotating the blade drive lever 1 counterclockwise to lower the blade drive pin 1a along the slot 3, it becomes possible to operate a shutter blade (not shown). Reference numeral 4 denotes a braking lever for converting the kinetic energy of the blade driving lever 1 into frictional heat energy. The braking lever 4 is swingably supported by a shaft 5, and is shown in the process of turning the blade driving lever 1 clockwise. As shown in FIG. 7, when the blade drive pin 1a is pressed against the "U" -shaped arm 4b of the brake lever 4, the brake lever 4 turns left around the shaft 5, but in this process, the blade drive pin 1 The kinetic energy of the blade drive lever 1 is absorbed by converting the kinetic energy into frictional heat energy between the braking lever 4 and the main plate. Reference numeral 6 denotes a buffer member for stopping the brake lever 4 when the arm 4a of the brake lever 4 abuts, and the buffer member 6 is formed of an elastic material such as rubber.
A stopper pin 1b is formed on the back surface of the blade drive lever 1 to restrict the left rotation of the brake lever 4 when the arm 4b of the brake lever 4 comes into contact with the stopper pin 1b.

FIG. 8 shows a state in which the blade drive lever 1 is turned clockwise to the right rotation, and the arm 4b of the brake lever 4 is in contact with the stopper pin 1b of the blade drive lever 4. The arm 4a is cut into the buffer member 6.
Accordingly, in the state shown in FIG. 8, a clockwise turning force is applied to the arm 4a of the brake lever 4 by the elastic force of the buffer member 6, and the brake lever 4 slightly turns clockwise as shown in FIG. Accordingly, the arm 4b of the brake lever 4 is slightly separated from the pin 1b, and the arm 4b of the brake lever 4 slightly pushes back the pin 1a of the blade drive lever 1, so that the shutter blade (not shown) is slightly pushed back and stopped.

[0005]

Therefore, when designing the shutter mechanism, it is necessary to prevent the exposure opening from being affected even if the shutter blade is slightly pushed back as shown in FIG. The force and the elastic force exerted on the brake lever by the shock-absorbing member 6 are not absolutely invariant, and there is an unavoidable effect accompanying aging or a change in the camera attitude. When the elastic force exerted on the brake lever by the cushioning member 6 excessively acts on the frictional force of the brake lever, there is a problem that the exposed opening is affected.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and comprises a braking member for stopping a blade driving member and a cushioning member for stopping the braking member at a target position. It is an object of the present invention to provide a brake device for a focal plane shutter that is hardly affected by the elastic force of the elastic member, assuming a brake device for a focal plane shutter having the same. In summary, the focal plane shutter brake device according to claim 1 includes: a front blade group that starts an exposure operation by traveling from an initial position blocking an exposure opening (AP) to a forward limit opening the exposure opening ( 11) Alternatively, the leading blade group or the trailing blade group is connected to the trailing blade group (12) that completes the exposure operation by traveling from the initial position where the exposure opening is opened to the forward limit for blocking the exposure opening. Blade driving member (13, 36) for driving the group from the initial position toward the forward limit
And: converting the kinetic energy of the blade drive member into frictional heat energy in a process in which the blade drive member travels from the initial position to the limit of travel in a position interfering with the travel locus of the blade drive member. And a braking member (30, 53) for attenuating the kinetic energy of the blade drive member by:
Assuming a braking device of a focal plane shutter having a cushioning member (34, 57) with which the braking member abuts: The elastic force exerted on the braking member by the cushioning member is substantially the center of rotation of the braking member (31, 57). 54).

A second aspect of the present invention is a brake system for a focal plane shutter, which is based on the first aspect of the present invention: engaging the brake member with the blade drive member after the brake member comes into contact with the buffer member. Thus, an engaging member (35, 58) for restricting the operation limit of the braking member is formed.

According to the focal plane shutter brake device of the present invention, the kinetic energy of the blade driving member is basically converted into the heat energy generated by the braking member when the blade driving member operates the braking member. This makes it difficult for the change in the camera attitude or the like to affect the magnitude of the braking force, so that the braking force in the initial design can be stably obtained. In addition, since the elastic force exerted on the braking member by the cushioning member is substantially directed to the rotation center of the braking member, the elastic force exerted on the braking member by the cushioning member when the braking member contacts the cushioning member. No longer acts as a force for rebounding, and the rebound does not affect the exposed aperture. Further, as described in claim 2, an engagement member is formed on the braking member to engage with the blade drive member after the braking member comes into contact with the buffer member, thereby restricting an operation limit of the braking member. In this case, the forward limit of the braking member can be stabilized, and
Even if the braking member receives a rotational force in the opposite direction due to the repulsive force of the blade driving member and the braking member when the braking member is engaged with the blade driving member, the rotation exerts an elastic force exerted on the braking member by the cushioning member. To prevent the blade opening position from being affected.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view of a focal plane shutter according to an embodiment of the present invention as viewed from a subject side, and FIG. 2 is an enlarged view of a driving force transmission mechanism. In the figure, reference numeral 10 denotes a shutter base plate, and an exposure opening AP is formed substantially near the center of the shutter base plate 10. FIG. 1 shows a state immediately after one exposure operation is completed, and a plurality of (five in the embodiment) front blade groups 1 are shown.
Reference numeral 1 denotes a position where the exposure opening AP is opened, being superposed below the exposure opening AP. The plurality of rear blade groups 12 are deployed on the exposure opening AP, and are located at positions where the exposure opening AP is shielded. Reference numeral 13 denotes a front blade drive lever which is an example of a blade drive member for driving the front blade group 11, and the front blade drive lever 13 is rotatably supported by a shaft 14 on the main plate 10.

Reference numerals 15 and 16 denote front blade connecting levers for transmitting the rotation of the front blade driving lever 13 to the front blade group 11, and the front blade connecting lever 15 is connected to a shaft 14 common to the front blade driving lever 13. The front blade connecting lever 16 is pivotally supported by a shaft 17 on the main plate so as to be freely pivotable. An engaging pin 18 erected on the back surface of the front blade drive lever 13 penetrates a slit 19 formed in an arc shape with respect to the base plate around the shaft 14 and is engaged with the front blade connection lever 15. When the front blade drive lever 13 turns around the shaft 14, the front blade connecting lever 15 also turns around the shaft 14. The shaft 20 formed on the front blade connecting lever 15 and the shaft 21 formed on the front blade connecting lever 16 are rotationally caulked with the front blade having the shortest working distance in the front blade group 11. Similarly, the shafts 22 and 23 formed on the front blade connecting levers 15 and 16 are rotatably caulked with the front blades having the second smallest working distance in the front blade group 11, and the shafts 24 and 25 are provided with the shafts in the front blade group 11. The first blade having the third smallest working distance is rotationally caulked, and the first blade having the fourth smallest working distance in the first blade group 11 is rotatably caulked on the shafts 26 and 27, and the first blade group on the shafts 28 and 29. 11, the leading blade having the largest working distance is rotationally caulked. And the leading blade connecting levers 15, 16
The front blade group 11 forms a parallel link as a whole, and when the front blade connecting lever 15 turns around the shaft 14, each blade constituting the front blade group 11 translates by an amount proportional to the inter-axis distance. Then, a transition is made between an unfolded state in which the exposure opening AP is shielded and a superposed state in which the exposure opening AP is opened.

Reference numeral 30 denotes a leading blade braking lever that attenuates the kinetic energy of the leading blade driving lever 15. The leading blade braking lever 30 is supported by a shaft 31 on the main plate so as to swing freely. It has a sufficiently large coefficient of friction in between. An engagement pin on the back surface of the front blade drive lever 13 is formed in the recessed portion inside the arm 32 extending in one end of the front blade drive lever 30 in the process of turning the front blade drive lever 13 clockwise. As a result, the leading blade braking lever 30 rotates counterclockwise around the shaft 31. At this time, the kinetic energy of the leading blade driving lever 13 is converted into thermal energy generated by friction between the leading blade braking lever 30 and the main plate. The kinetic energy of the leading blade drive lever 13 is attenuated. The arcuate convex piece 3 formed at the other end of the front blade braking lever 30
Reference numeral 3 designates an abutment with a circular outer peripheral cushioning member 34 made of an elastic material in the vicinity of the forward limit of the leading blade drive lever 13. As a feature of the present embodiment, the direction of the elastic force exerted on the arc-shaped convex piece 33 by the cushioning member 34 is oriented in the direction of the rotation axis 31 of the front blade braking lever 30.
The elastic force exerted on the arc-shaped convex piece 33 does not generate a torque on the leading blade braking lever 30. A stopper 35 for restricting the left rotation of the front blade braking lever 30 is formed on the back surface of the front blade drive lever 13.

Reference numeral 36 denotes a rear blade drive lever, which is an example of a blade drive member for driving the rear blade group 11, and the rear blade drive lever 36 is rotatably supported by a shaft 37 on the main plate 10. . 38, 39 are rear blade drive levers 36;
Is a rear blade connecting lever for transmitting the rotation of the rotation to the rear blade group 11, and the rear blade connecting lever 38 is a rear blade driving lever 36.
The rear blade connecting lever 39 is pivotally supported by a shaft 40 on the main plate so as to be freely rockable.
Engagement pin 41 erected on the back surface of rear blade drive lever 36
Is engaged with the rear blade connecting lever 38 through a slit 42 formed in an arc shape about the shaft 37 with respect to the main plate, and when the rear blade drive lever 36 turns about the shaft 37, the rear The blade connecting lever 38 also pivots about the shaft 37. A shaft 43 formed on the rear blade connecting lever 38 and a shaft 44 formed on the rear blade connecting lever 39 are rotationally caulked for the rear blade having the shortest working distance in the rear blade group 11. Similarly, the working distance of the shafts 45 and 46 formed on the rear blade connecting levers 38 and 39 in the rear blade group 11 is the second.
The rear blade having a smaller working distance in the rear blade group 11 is axially caulked to the shafts 47 and 48, and the working distance in the rear blade group 11 is smaller for the shafts 49 and 50. Fourth, a small number of rear blades are swaged, and shafts 51 and 52 are rotated.
The rear blade having the largest working distance in the rear blade group 11 is rotationally caulked. Then, the rear blade connecting levers 38, 3
9 and the rear blade group 11 form a parallel link as a whole, and when the rear blade connecting lever 38 rotates about the shaft 37, each blade constituting the rear blade group 11 is parallel by an amount proportional to the distance between the shafts. It moves to change between a deployed state in which the exposure opening AP is shielded and a superimposed state in which the exposure opening AP is opened.

Reference numeral 53 denotes a rear blade braking lever that attenuates the kinetic energy of the rear blade driving lever 38. The rear blade braking lever 53 is supported by a shaft 54 on the main plate so as to be swingable. It has a sufficiently large coefficient of friction in between. The engagement pin on the back surface of the rear blade drive lever 36 is formed in the process of turning the rear blade drive lever 36 clockwise in the concave portion inside the arm 55 in the shape of a “<” extending from one end of the rear blade drive lever 53. The rear blade braking lever 53 rotates counterclockwise about the shaft 54 by the abutment of 41, and at this time, the kinetic energy of the rear blade driving lever 36 is converted into thermal energy generated by friction between the rear blade braking lever 53 and the main plate. The kinetic energy of the rear blade drive lever 36 is attenuated. The arc-shaped convex piece 5 formed at the other end of the rear blade braking lever 53
Reference numeral 6 designates an abutment with a circular outer cushioning member 57 made of an elastic material in the vicinity of the forward limit of the rear blade drive lever 36. As a feature of the present embodiment, the direction of the elastic force exerted by the cushioning member 57 on the arc-shaped convex piece 56 is in the direction of the rotating shaft 54 of the rear blade braking lever 53, and accordingly, the cushioning member 57
Does not generate torque on the rear blade braking lever 53. Further, a stopper 58 for restricting the left rotation of the rear blade braking lever 53 is formed on the rear surface of the rear blade drive lever 36. Next, FIG. 3 is a sectional view showing a part of the leading blade drive mechanism.
1 and 2 are denoted by the same reference numerals as those in FIGS. 1 and 2, and redundant description is omitted. In the figure, reference numeral 59 denotes a portion between the main plate 10 and the front blade braking lever 30. A friction plate 60 for adjusting the frictional force is a blade holding plate.

Next, the operation of this embodiment will be described in detail with reference to the above items and FIGS. 4 to 6
FIG. 4 shows a state change of the brake device on the front blade side. FIG. 4 shows a state in which the front blade drive pin 18 contacts the arm 32 of the front blade brake lever 30 during the travel of the front blade drive lever 13. FIG. 5 shows a state in which the braking force by the braking lever 30 has begun, FIG. 5 shows a state in which the arc-shaped convex piece 33 of the leading blade braking lever 30 bites into the buffer member 34, and FIG. Each state is shown. Further, the structure of the rear blade side is common to that of the front blade side.

First, in the initial state, the front blade drive lever 13 and the rear blade drive lever 36 are each turned to the left rotation (position where the engaging pins 18 and 41 abut the left ends of the slides 19 and 42, respectively). Locked. When a shutter button (not shown) is pressed in this state, the leading blade drive lever 13 is released by a release mechanism (not shown), and the trailing blade drive lever 36 is released with a time difference corresponding to the exposure time. The present invention relates to the brake device of the focal plane shutter. Since the structure of the brake device is common between the front blade side and the rear blade side, only the operation on the front blade side will be described. When the leading blade driving lever 13 is released, the leading blade driving lever rotates clockwise around the shaft 14 by, for example, the urging force of a spring (not shown), and the engaging pin 18 is turned into a slit 19 as shown in FIG.
Descend along. As a result, the connecting levers 15 and 16 maintain the parallel link with the front blade group 11 and the shafts 14 and 17 respectively.
The front blade group 11, which is in the unfolded state in which the exposure opening AP is closed in the initial state, descends toward the superposed state in which the exposure opening AP is opened, and moves the exposure opening AP to the upper edge portion. Open from.

FIG. 7 shows the leading blade drive lever 13
In the process of turning clockwise, the engaging pin 18
5 shows a state in which the arm 32 is in contact with the inner edge portion of the arm 32 in the shape of a circle. When the front blade drive lever 13 further rotates clockwise from this state, the brake lever 30 is engaged with the engagement pin 18. It turns left around the axis 31. At this time, since the friction plate 59 is interposed between the brake lever 30 and the main plate 10, the kinetic energy of the front blade drive lever 13 is converted into heat energy generated by the friction force between the friction plate 59 and attenuated. go. Further, at this time, the arc-shaped convex piece 33 of the braking lever 30 starts to contact the buffer member 34, and the arc-shaped convex piece 33 bites into the buffer member due to the elasticity of the buffer member 34 as shown in FIG. In the present embodiment, the cushioning member 34 and the arc-shaped convex piece 33 are each formed to have an arc-shaped outer peripheral surface.
The elastic force exerted on the brake lever 30 is directed in the direction of the rotation axis 31 of the brake lever 30.
The elastic force exerted on the brake lever 30 does not generate a torque on the brake lever 30, so that the brake lever 30
No rebound operation occurs due to the contact of 3 with the cushioning member.

Then, as shown in FIG. 6, the left rotation of the front blade braking lever 30 is restricted in a state where the outside of the "-"-shaped arm 32 is in contact with the stopper 35 on the back side of the front blade driving lever 13. Therefore, the right rotation of the leading blade drive lever 13 is also restricted. In this manner, when the outside of the “<”-shaped arm 32 comes into contact with the stopper 35 on the back side of the leading blade drive lever 13, the stopper 35 applies a right-turning torque to the leading blade braking lever 30. At this time, the rotation speed of the leading blade braking lever 30 is reduced to the arc-shaped convex piece 33 at this time.
Is sufficiently decelerated by biting into the cushioning member 34, and furthermore, the cushioning member 34 also acts to suppress the right-handed rotation of the front blade braking lever 30 due to rebound. When the outside contacts the stopper 35 on the back side of the front blade drive lever 13, the stopper 3
There is no danger that a large rebound will occur due to the right-handed torque exerted on the 5-blade front brake lever 30.

[0018]

As described above, according to the present invention, the kinetic energy of the blade driving member basically operates the braking member by the blade driving member according to the focal plane shutter braking device of the present invention. Since it is converted into thermal energy generated by the braking member when it is made to change, it is difficult for the change in the camera posture to affect the magnitude of the braking force, and it is possible to stably obtain the initial designed braking force. Become. In addition, since the elastic force exerted on the braking member by the cushioning member is substantially directed to the rotation center of the braking member, the elastic force exerted on the braking member by the cushioning member when the braking member contacts the cushioning member. No longer acts as a force for rebounding, and the rebound does not affect the exposed aperture. Further, as described in claim 2, an engagement member is formed on the braking member to engage with the blade drive member after the braking member comes into contact with the buffer member, thereby restricting an operation limit of the braking member. In this case, the forward movement limit of the braking member can be stabilized, and the repulsive force between the blade driving member and the braking member when the braking member is engaged with the blade driving member causes the braking member to move in the opposite direction. Even if a rotational force is applied, the rotation is damped by the elastic force exerted on the damping member by the cushioning member, and the risk of affecting the blade opening position can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view of a focal plane shutter including a focal plane shutter brake device according to the present invention.

FIG. 2 is an enlarged plan view showing a power transmission mechanism and a braking mechanism of the focal plane shutter shown in FIG. 1;

FIG. 3 is a sectional view showing a portion of a power transmission mechanism and a braking system mechanism on a front blade side of the focal plane shutter shown in FIGS. 1 and 2;

FIG. 4 is a plan view showing a state in which the front blade driving lever is in contact with the front blade braking lever in the brake device of the present invention.

FIG. 5 is a plan view showing a state in which a leading blade braking lever has bitten into a buffer member in the brake device of the present invention.

FIG. 6 is a plan view showing a state where the leading blade drive lever has reached a forward limit in the brake device of the present invention.

FIG. 7 is a plan view showing a state in which a leading blade driving lever is in contact with a leading blade braking lever in a conventional brake device.

FIG. 8 is a plan view showing a state where a leading blade drive lever has reached a forward limit in a conventional brake device.

FIG. 9 is a plan view showing a state in which a leading blade drive lever has rebounded from a forward limit in a conventional brake device.

[Explanation of symbols]

 AP Exposure opening 10 Shutter base plate 11 Front blade group 12 Rear blade group 13 Front blade drive lever 30 Front blade braking lever 31 Rotary shaft 32 "C" -shaped arm 33 Arc-shaped convex piece 34 Buffer member 35 Stopper

Claims (3)

[Claims] 1. A blade group that starts an exposure operation by traveling from an initial position in which the exposure opening is blocked toward a forward limit for opening the exposure opening, or the exposure opening is started from an initial position in which the exposure opening is opened. A blade driving member coupled to a rear blade group that completes an exposure operation by traveling toward a forward limit to be shielded and drives the front blade group or the rear blade group from an initial position toward the forward limit; The blade drive member is rotatably provided at a position that interferes with the travel locus of the drive member, and converts the kinetic energy of the blade drive member into frictional heat energy during the travel of the blade drive member from the initial position to the forward limit. In a brake device for a focal plane shutter having a braking member for attenuating kinetic energy of a member and a cushioning member with which the braking member abuts, the cushioning member is A braking device for a focal plane shutter, wherein an elastic force exerted on the braking member is substantially directed to a rotation center of the braking member. 2. A brake apparatus for a focal plane shutter according to claim 1, wherein said brake member is engaged with said blade drive member after said brake member comes into contact with said buffer member. A brake device for a focal plane shutter, wherein an engagement member for regulating the pressure is formed. 3. A focal plane shutter brake device according to claim 1, wherein said contact portions between said buffer member and said braking member are each formed in an arc shape. A shutter brake device.