JP4021055B2 - Brake device for focal plane shutter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brake device that stops a focal plane shutter at its advance end, and more particularly to a brake device that suppresses rebound at the advance end of the focal plane shutter as much as possible.
[0002]
[Prior art]
As is well known, the focal plane shutter is released in the initial setting state after releasing the front curtain in a state where the exposure opening is shielded in the initial setting state so as to open the exposure opening. One exposure operation is performed by releasing the rear curtain in a state where the opening is opened toward the state where the exposure opening is shielded. In this kind of focal plane shutter, the time difference from the release of the first curtain to the release of the second curtain corresponds to the exposure time, but it reduces the exposure unevenness in the image frame in the high-speed seconds, or speeds up the flash synchronization time. In order to achieve this, it is desired to increase the curtain speed itself. When this curtain speed is increased, the impact at the advance end of the actuating member including the blade member also rises. Therefore, in order to absorb this impact efficiently and stop the various actuating members at the advance end, the performance is improved. An excellent brake device is required. As specific examples of this type of brake device, for example, Japanese Utility Model Publication No. 56-88227, Japanese Utility Model Application Publication No. 1-177736, and the like can be pointed out. In Japanese Utility Model Laid-Open No. 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 on the shock absorbing rubber member 7 at an entry angle of 30 degrees or less to rebound. The content of adding braking while suppressing is shown. Further, in the actual Japanese Utility Model Laid-Open No. 1-177736, the final contact surface is assumed on the premise of a brake device in which the final contact surface formed on the blade driving arm 11 is finally brought into contact with the buffer member 14 and stopped. The front contact surface that contacts the shock absorber is formed on the blade drive arm before the contact, and the front contact surface absorbs a part of the kinetic energy in the process of rotating the shock absorber. ing. Further, Japanese Utility Model Laid-Open No. 4-61325 is similar to Japanese Utility Model Laid-Open No. 1-177736 in that the front contact surface contacts the buffer member and absorbs energy before the final contact surface. The content which improved durability by forming an outer periphery with a rigid body is disclosed. However, among the above methods, in Japanese Utility Model Publication No. 56-88227 and Japanese Utility Model Application Publication No. 1-177736, the drive member for driving the blade member is slid directly on the buffer member at the advance end. Therefore, it may be difficult to obtain a sufficient braking force. In the case of Japanese Utility Model Laid-Open No. 1-177736, Japanese Utility Model Laid-Open No. 4-61325, and the like, the final contact is brought into contact with the final abutting surface, so that a bounce at the advanced end may occur.
[0003]
In order to obtain a stable braking force, the drive member itself is not directly stopped, but a drive member is provided in the process of providing a brake member having, for example, frictional resistance on the travel path of the drive member and operating the brake member. It is desirable to convert the kinetic energy into the frictional heat energy of the braking member. FIG. 7, FIG. 8 and FIG. 9 show an example of a brake device for a focal plane shutter having such a braking member. In the figure, reference numeral 1 denotes a blade drive lever connected to a shutter blade (not shown), which can be either a front blade or a rear blade. The blade drive lever 1 is swingably supported by a shaft 2 on the base plate, and its tip The blade drive pin 1a implanted in the part penetrates the arc-shaped slot 3 formed in the base plate and engages with a shutter blade (not shown). Thus it is possible to operate the non-illustrated shutter blade by lowering along the blade drive lever 1 is rotated the watch around the blade drive pin 1a of the slot 3. Reference numeral 4 denotes a brake lever for converting the kinetic energy of the blade drive lever 1 into frictional heat energy. The brake lever 4 is supported by the shaft 5 so as to be swingable. 7, when the blade driving pin 1 a is pressed against the “<”-shaped arm 4 b of the braking lever 4, the braking lever 4 rotates counterclockwise about the shaft 5. In this process, the blade driving lever 1 The kinetic energy of the blade drive lever 1 is absorbed by converting the kinetic energy into frictional heat energy between the brake lever 4 and the ground plane. Reference numeral 6 denotes a buffer member for stopping the brake lever 4 when the arm 4a of the brake lever 4 abuts. The buffer member 6 is formed of an elastic material such as rubber. Further, a stopper pin 1b is formed on the rear surface of the blade drive lever 1 to restrict the left-handed rotation of the brake lever 4 by contacting the arm 4b of the brake lever 4.
[0004]
FIG. 8 shows a state in which the blade driving lever 1 is rotated to the right and the arm 4b of the braking lever 4 is in contact with the stopper pin 1b of the blade driving lever 1. At this time, the arm 4a of the braking lever 4 is It bites into the buffer member 6. Accordingly, in the state shown in FIG. 8, a clockwise rotation force is applied to the arm 4a of the braking lever 4 by the elastic force of the buffer member 6, and the braking lever 4 is slightly rotated to the right as shown in FIG. Accordingly, the arm 4b of the brake lever 4 is slightly separated from the stopper pin 1b, and the arm 4b of the brake lever 4 slightly pushes back the blade drive pin 1a of the blade drive lever 1, so that the shutter blades (not shown) are also pushed back slightly and stopped. To do.
[0005]
[Problems to be solved by the invention]
Therefore, in designing the shutter mechanism, it is necessary to prevent the exposure opening from being affected even if the shutter blades are pushed back slightly as shown in FIG. 9. However, the frictional force of the brake lever 4 and the buffer member 6 are not affected by the brake lever 4. the elastic force exerted against the not of absolute immutable, there are those inevitable that with the impact of changes in the aging and camera orientation. When the buffer member 6 is an elastic force exerted against the brake lever 4 is applied in excess of the friction force of the brake lever 4, there is a problem that the exposure opening is affected.
[0006]
[Means for Solving the Problems]
The present invention has been made in view of such problems, and presupposes a brake device for a focal plane shutter having a braking member for stopping the blade driving member and a buffer member for stopping the braking member at a target position. Therefore, an object of the present invention is to provide a brake device for a focal plane shutter that is hardly affected by the elastic force of the elastic member. In summary, the brake device for a focal plane shutter according to claim 1 is: a leading blade group that starts an exposure operation by running from an initial position where the exposure opening (AP) is shielded toward a forward limit that opens the exposure opening (AP). 11) or connected to the rear blade group (12) that terminates the exposure operation by running from the initial position where the exposure opening is opened toward the forward limit that shields the exposure opening, and the front blade group or the rear blade Blade driving members (13, 36) for driving the group from the initial position toward the forward limit: The blade driving members are rotatably provided at positions that interfere with the travel locus of the blade driving member, and the blade driving member is moved forward from the initial position. Braking members (30, 53) for attenuating the kinetic energy of the blade drive member by converting the kinetic energy of the blade drive member into frictional heat energy in the course of traveling : The brake system of the focal-plane shutter the braking member has a contact buffering member (34,57) assuming: mutual contact portion of said braking member and the buffer member are respectively formed in a circular arc shape, the buffer The elastic force exerted on the braking member by the member is generally directed toward the rotation center (31, 54) of the braking member.
[0007]
Further, the brake device of the focal plane shutter according to claim 2 is based on the brake device of claim 1: the brake member is engaged with the blade driving member after the brake member abuts against the buffer member, and The engaging member ( 35, 58) for restricting the operation limit of the braking member is formed.
[0008]
According to the focal plane shutter brake device of the present invention, the kinetic energy of the blade driving member is basically converted into thermal energy generated by the braking member when the blade driving member operates the braking member. This makes it difficult to affect the magnitude of the braking force, so that the initial design braking force can be obtained stably. In addition, since the elastic force exerted by the buffer member on the brake member is substantially directed toward the center of rotation of the brake member, the elastic force exerted by the buffer member on the brake member when the brake member comes into contact with the buffer member is No longer acts as a rebounding force, and the exposure opening is not affected by the rebounding. Furthermore, as shown in claim 2, the brake member is formed with an engagement member that engages with the blade drive member after the brake member abuts against the buffer member and restricts the operation limit of the brake member. In this case, the forward limit of the braking member can be stabilized, and the braking member is moved in the reverse direction by the repulsive force between the blade driving member and the braking member when the braking member is engaged with the blade driving member. Even if the rotational force is received, this rotation is braked by the elastic force exerted by the buffer member on the braking member, and it is possible to prevent the blade opening position from being affected .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described 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 the 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. An exposure opening AP is formed in the vicinity of the center of the shutter base plate 10. FIG. 1 shows a state immediately after the end of one exposure operation, and a plurality of (five in the embodiment) leading blade groups 11 are superimposed on the lower side of the exposure opening AP, and the exposure opening It is in the position which opened AP. Further, the plurality of rear blade groups 12 are unfolded on the exposure opening AP, and are in a position where the exposure opening AP is shielded. A leading blade driving lever 13 is an example of a blade driving member for driving the leading blade group 11, and the leading blade driving lever 13 is rotatably supported on a shaft 14 on the shutter base plate 10.
[0010]
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 can swing on a shaft 14 common to the front blade driving lever 13. The leading blade connecting lever 16 is pivotally supported by a shaft 17 on the shutter base plate 10 so as to be swingable. The engaging pin 18 erected on the back surface of the leading blade driving lever 13 is engaged with the leading blade connecting lever 15 through a slit 19 formed in an arc shape around the shaft 14 with respect to the shutter base plate 10 . When the leading blade drive lever 13 pivots about the shaft 14, the leading blade connecting lever 15 also pivots about the shaft 14. The front blade having the smallest working distance in the front blade group 11 is rotationally crimped on the shaft 20 formed on the front blade connecting lever 15 and the shaft 21 formed on the front blade connecting lever 16. Similarly, the front blades 23 and 16 formed on the front blade connecting levers 15 and 16 are swiveled with the front blade having the second smallest working distance in the front blade group 11, and the shafts 24 and 25 are in the front blade group 11. The leading blade having the third smallest working distance is rotated and crimped, the leading blade having the fourth smallest working distance in the leading blade group 11 is crimped on the shafts 26 and 27, and the leading blade group is disposed on the shafts 28 and 29. 11, the leading blade having the largest working distance is rotated and crimped. The leading blade connecting levers 15 and 16 and the leading blade group 11 form a parallel link as a whole, and when the leading blade connecting lever 15 pivots about the shaft 14, each blade constituting the leading blade group 11 is an axis. By translating by an amount proportional to the distance between the two, a transition is made between the unfolded state where the exposure aperture AP is shielded and the overlapped state where the exposure aperture AP is opened.
[0011]
Next, 30 is a front blade brake lever for attenuating the kinetic energy of the leading blade driving lever 13, leading blade brake lever 30 is swingably supported to the shaft 31 on the shutter base plate 10, a shutter base plate 10 It has a sufficiently large coefficient of friction. The engagement pin on the back surface of the leading blade drive lever 13 in the process of the right turn of the leading blade drive lever 13 in the hollow portion inside the "<"-shaped arm 32 extending to one end of the leading blade braking lever 30 As a result, the leading blade braking lever 30 rotates counterclockwise about the shaft 31. At this time, the kinetic energy of the leading blade driving lever 13 is changed to the thermal energy generated by the friction between the leading blade braking lever 30 and the shutter base plate 10. As a result, the kinetic energy of the leading blade drive lever 13 is attenuated. An arc-shaped convex piece 33 formed at the other end of the leading blade braking lever 30 is in contact with a circular outer peripheral cushioning member 34 made of an elastic material near the forward limit of the leading blade driving lever 13. As a feature of the present embodiment, the direction of the elastic force exerted by the buffer member 34 on the arc-shaped convex piece 33 is directed to the direction of the rotating shaft 31 of the leading blade braking lever 30. On the other hand, the elastic force exerted on the leading blade braking lever 30 does not generate torque. Further, a stopper 35 for restricting the leftward rotation of the leading blade braking lever 30 is formed on the back surface of the leading blade driving lever 13.
[0012]
Next, reference numeral 36 denotes a rear blade drive lever as an example of a blade drive member for driving the rear blade group 12 , and the rear blade drive lever 36 is rotatably supported by a shaft 37 on the shutter base plate 10. Reference numerals 38 and 39 denote rear blade coupling levers for transmitting the rotation of the rear blade driving lever 36 to the rear blade group 12. The rear blade coupling lever 38 is swingable on a shaft 37 common to the rear blade driving lever 36. The rear blade connecting lever 39 is pivotally supported by a shaft 40 on the shutter base plate 10 so as to be swingable. The engagement pin 41 erected on the rear surface of the rear blade drive lever 36 passes through a slit 42 formed in an arc shape centering on the shaft 37 with respect to the shutter base plate 10 and is engaged with the rear blade connection lever 38. When the trailing blade drive lever 36 pivots about the shaft 37, the trailing blade coupling lever 38 also pivots about the shaft 37. The rear blade having the smallest working distance in the rear blade group 12 is rotationally crimped on the shaft 43 formed on the rear blade connecting lever 38 and the shaft 44 formed on the rear blade connecting lever 39. Similarly working distance in the rear blade group 12 in the axial 45 and 46 formed in the rear blade connecting lever 38, 39 is the rear blades less the second rotated caulking, the rear blade group 12 in the shaft 47, 48 , The rear blade having the third smallest working distance is rotationally crimped, the rear blade group 12 having the fourth smallest working distance is rotationally crimped on the shafts 49 and 50, and the rear blade group is disposed on the shafts 51 and 52. In FIG. 12 , the rear blade having the largest working distance is rotationally crimped. The rear blade connecting levers 38 and 39 and the rear blade group 12 form a parallel link as a whole, and when the rear blade connecting lever 38 pivots about the shaft 37, each blade constituting the rear blade group 12 is a shaft. By translating by an amount proportional to the distance between the two, a transition is made between the unfolded state where the exposure aperture AP is shielded and the overlapped state where the exposure aperture AP is opened.
[0013]
Next, 53 is a blade brake lever after attenuating the kinetic energy of the rear curtain drive lever 36, the second blade brake lever 53 is swingably supported to the shaft 54 on the shutter base plate 10, a shutter base plate 10 It has a sufficiently large coefficient of friction. An engagement pin on the back surface of the rear blade drive lever 36 in the course of the right turn of the rear blade drive lever 36 in the hollow portion inside the "<"-shaped arm 55 extending to one end of the rear blade brake lever 53 The rear blade braking lever 53 rotates counterclockwise about the shaft 54 due to the abutment of 41, and the kinetic energy of the rear blade driving lever 36 at this time is the thermal energy generated by the friction between the rear blade braking lever 53 and the shutter base plate 10. As a result, the kinetic energy of the trailing blade drive lever 36 is attenuated. An arc-shaped convex piece 56 formed at the other end of the rear blade braking lever 53 is in contact with an outer peripheral circular buffer 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 buffer member 57 on the arc-shaped convex piece 56 is directed to the direction of the rotating shaft 54 of the trailing blade braking lever 53. The elastic force exerted against the rear blade braking lever 53 does not generate torque. Further, a stopper 58 is formed on the rear surface of the rear blade drive lever 36 for restricting the leftward rotation of the rear blade braking lever 53. Next, FIG. 3 is a cross-sectional view showing a part of the leading blade drive mechanism. The components described with reference to FIGS. 1 and 2 are denoted by the same reference numerals as those in FIGS. In the figure, 59 is a friction plate for adjusting the frictional force between the shutter base plate 10 and the leading blade braking lever 30, and 60 is a blade pressing plate.
[0014]
Next, the operation of the present embodiment will be described in detail with reference to the above items and FIGS. 4 to 6 show changes in the state of the brake device on the leading blade side. Among these, FIG. 4 shows that the engaging pin 18 moves the arm 32 of the leading blade braking lever 30 during the traveling process of the leading blade driving lever 13. contact with state started taking braking force by the first blade brake lever 30, Fig. 5 is arc-shaped convex piece 33 of the first blade brake lever 30 bites the cushioning member 34 state, FIG. 6 is Sakiwa Neka kinematic lever Reference numeral 13 denotes a state where the vehicle has traveled to the forward limit. Since the rear blade side has the same structure as that of the leading blade side, the leading blade side will be described as a representative.
[0015]
First, in the initial state, the leading blade driving lever 13 and the trailing blade driving lever 36 are respectively locked at the positions where the leading blade driving lever 13 and the trailing blade driving lever 36 are turned to the leftmost position (the positions where the engaging pins 18 and 41 are in contact with the left ends of the slits 19 and 42, respectively). ing. 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 portion of the focal plane shutter. Since the structure of the brake device is common between the leading blade side and the trailing blade side, only the operation on the leading blade side will be described. When the leading blade driving lever 13 is released, the leading blade driving lever 13 is rotated clockwise around the shaft 14 by, for example, a biasing force of a spring (not shown), and the engaging pin 18 is inserted into the slit 19 as shown in FIG. Descent along. As a result, the leading blade connecting levers 15 and 16 are rotated clockwise around the shafts 14 and 17 while maintaining a parallel link with the leading blade group 11, and in the initial state, the leading blades are in a deployed state that shields the exposure aperture AP. The group 11 descends toward the overlapping state where the exposure aperture AP is opened, and opens the exposure aperture AP from the upper edge.
[0016]
FIG. 4 shows a state in which the engaging pin 18 is in contact with the inner edge portion of the “<”-shaped arm 32 of the leading blade braking lever 30 in the process in which the leading blade driving lever 13 rotates clockwise as described above. In this state, when the leading blade driving lever 13 further rotates clockwise, the leading blade braking lever 30 rotates counterclockwise about the shaft 31 while being engaged with the engaging pin 18. The kinetic energy of the leading blade driving lever 13 so this time the leading blade brake lever 30 and is between the shutter base plate 10 friction plate 59 is interposed is converted into heat energy generated by the frictional force between the friction plate 59 It decays. Further, arc-shaped convex piece 33 of the case leading blade brake lever 30 begins to contact with the cushioning member 34, arc-shaped convex piece 33 as shown in FIG. 5 by the elasticity of the cushioning member 34 is Yuku bites into the cushioning member 34 . In the present embodiment, since the buffer member 34 and the arc-shaped convex piece 33 are each formed with an arc-shaped outer peripheral surface, the elastic force exerted by the buffer member 34 on the leading blade braking lever 30 is the leading blade braking. oriented in the direction of the axis of rotation 31 of the lever 30, therefore, the elastic force of the cushioning member 34 exerts against the leading blade brake lever 30 does not generate a torque to the front blade brake lever 30, thus, the first blade brake lever 30 does not cause a rebound operation caused by the arc-shaped convex piece 33 coming into contact with the buffer member 34 .
[0017]
Then, the left旋限the leading blade brake lever 30 on the back side of the stopper 35 while contacting the outer leading blade driving lever 13 of the shaped arm 32 of the "V" as shown in FIG. 6 is restricted, therefore, The right limit of the leading blade drive lever 13 is also restricted. Incidentally, the right-handed direction of the torque with respect to the stopper 35 is the leading blade brake lever 30 when the outer shape of the arm 32 of the "V" in this manner is brought into contact with the back side of the stopper 35 of the leading blade driving lever 13 the resulting allowed to the rotational speed of the front blade brake lever 30 at this time, along with its arc-shaped convex piece 33 is sufficiently decelerated by biting into the cushioning member 34, further, the cushioning member 34 is the leading blade braking by rebound because they act as be suppressed right gyratory operation of the lever 30, "V" shaped outer leading blade driving lever 13 back side of the stopper 35 to the stopper 35 when abutting the first blade brake lever of the arm 32 of the There is no risk that a large rebound will occur due to the clockwise torque applied to 30.
[0018]
【The invention's effect】
As described above, according to the present invention, according to the brake device for a focal plane shutter according to the present invention, the kinetic energy of the blade driving member is basically determined by the braking member when the blade driving member operates the braking member. Since it is converted into the generated thermal energy, changes in the camera posture or the like hardly affect the magnitude of the braking force, and it is possible to stably obtain the initial designed braking force. In addition, since the elastic force exerted by the buffer member on the brake member is substantially directed toward the center of rotation of the brake member, the elastic force exerted by the buffer member on the brake member when the brake member comes into contact with the buffer member is No longer acts as a rebounding force, and the exposure opening is not affected by the rebounding. Further, as shown in claim 2, the brake member is formed with an engagement member that engages with the blade drive member after the brake member abuts against the buffer member and restricts the operation limit of the brake member. In this case, the forward limit of the braking member can be stabilized, and the braking member is moved in the reverse direction by the repulsive force between the blade driving member and the braking member when the braking member is engaged with the blade driving member. Even when the rotational force is received, the rotation is braked by the elastic force exerted by the buffer member on the braking 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.
3 is a cross-sectional view showing a portion of a power transmission mechanism and a braking system mechanism on the leading blade side of the focal plane shutter shown in FIGS. 1 and 2. FIG.
FIG. 4 is a plan view showing a state in which a leading blade driving lever is in contact with a leading 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 bites 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 the 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 in which 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 the leading blade drive lever has rebounded from the forward limit in the conventional brake device.
[Explanation of symbols]
AP exposure opening 10 the shutter base plate 11 13 destination leading blade group 12 trailing blade group blade drive lever 30 leading blade brake lever 31 rotates shaft 32 A over arm <br/> 33 arc-shaped convex piece 34 cushioning member 35 stopper

Claims (2)

The leading blade group that starts the exposure operation by running from the initial position where the exposure opening is shielded toward the forward limit where the exposure opening is opened, or the forward limit where the exposure opening is shielded from the initial position where the exposure opening is opened. A blade driving member that is connected to the rear blade group that ends the exposure operation by traveling toward the front blade group, and that drives the leading blade group or the rear blade group from the initial position toward the forward limit;
The blade drive member is rotatably provided at a position that interferes with the travel locus of the blade drive member, and converts the kinetic energy of the blade drive member into frictional heat energy in the process of traveling from the initial position to the forward limit. A braking member that attenuates the kinetic energy of the blade drive member;
In a brake device for a focal plane shutter having a buffer member against which the braking member abuts,
The focal point of the buffer member and the brake member is formed in an arc shape, and the elastic force exerted by the buffer member on the brake member is generally directed toward the rotation center of the brake member. A brake device for a plain shutter. The brake device for a focal plane shutter according to claim 1,
The focal plane shutter is characterized in that an engaging member is formed on the braking member to engage with the blade driving member after the braking member abuts against the buffer member and restricts an operation limit of the braking member. Brake device.

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