JP2518338Y2 - Camera shutter drive mechanism - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to a drive mechanism for a shutter used in a still camera or an electronic still camera, and more specifically, a blade drive that drives a shutter blade by the operation of a cam member that is connected to a motor that rotates substantially in one direction and operates. The present invention relates to an improvement of a drive mechanism that charges and releases members.

[Prior art]

An elastic material such as a spring is used as a drive source of a shutter mechanism used in a still camera or an electronic still camera,
It is known that the energy stored in the elastic material is released to drive the shutter blades. In this type of mechanism, a charge mechanism for returning the blade drive member, which is the driven member, to the set position while storing energy in the elastic material that is the drive source, and the blade drive member, which is the driven member, are held at the set position. A hold mechanism for releasing the hold mechanism and a mechanism for releasing the hold mechanism are required.
It is known that a single member also serves as these various mechanisms and that has a cam mechanism using a motor as a drive source. More specifically, the blade opening / closing lever itself or a member connected to the blade opening / closing lever is biased toward the forward limit by a spring, which is an example of an elastic material, and a cam is connected to a rotating member that rotates in one direction by a motor. Thereby pulling back the blade opening / closing lever or the like from the forward limit toward the set position against the biasing force of the spring, and stopping the rotating member at the set position to hold the blade opening / closing lever or the like at the set position. Further, by further rotating the rotating member from the set position, the hold of the blade opening / closing lever or the like is released, and the blade opening / closing lever or the like can travel from the set position toward the forward limit by the biasing force of the spring. And

[Problems to be solved by the device]

Although this method is extremely excellent in that a single member also has various functions, it also has a problem that the control of the motor stop timing becomes extremely delicate. That is, in the case of this type of mechanism, a current brake (a brake that supplies a reverse current sufficient to overcome the inertial force of the motor and the auxiliary mechanism) is generally used to stop the motor at the time of holding or releasing. However, the braking force of the current brake is affected by fluctuations in the electromotive force of the battery, changes in the frictional force between the members, and changes in the tension of the spring, and cannot always stop at a certain point. Therefore, for example, when the braking force is insufficient at the time of holding, overrun occurs and the blade opening / closing member cannot be held at the set position, or when the braking force becomes excessive at the time of releasing, the reverse rotation is performed. As a result, the cam members may interfere with each other to cause abnormal exposure time.

[Means for solving problems]

The present invention has been made in view of these problems, and provides a shutter drive mechanism capable of reliably holding the blade opening / closing member even if some overrun occurs when the setting member is held. This is the first purpose. It is a second object of the present invention to provide a shutter drive mechanism in which interference of the cam member is unlikely to occur and abnormal exposure time is unlikely to occur even if some reverse rotation occurs when the set member is released. . In summary, the drive mechanism of the camera shutter of the present invention is:
A blade driving member connected to the shutter blade and urged in a direction to expose the shutter blade; a blade driving member that can travel in a direction to move the blade driving member to a set position, and sets the blade driving member A set member biased in a direction opposite to the direction of moving the set member to a position; a force that is formed in association with the set member and runs the set member in a direction of moving the blade drive member to the set position. An arcuate cam edge that receives; a rotation of a motor that rotates substantially in one direction is transmitted, and the radius of curvature of the turning locus of the cam edge contact point is equal to the radius of curvature of the arcuate cam edge. , Contacting the cam edge causes the set member to travel to the set position of the blade drive member, and releases the set member by moving away from the cam edge A rotary member having a set roller for holding the blade drive member at a set position by stopping the rotary member while the set roller is in contact with the arcuate cam edge. It is premised on a drive mechanism for a camera shutter which is designed to release the set member by stopping the rotary member while the set roller is separated from the arcuate cam edge. For members,
For example, a pin that prevents the set member from returning from the set position of the blade drive member to a position behind the set roller and at a distance from the set roller that is shorter than the width of the arcuate cam edge. It is characterized in that a return prevention member having a shape of a circle is provided. Further, more preferably, the drive mechanism of the camera shutter of the present invention is based on the above; the blade drive member cannot be overcharged from the set position; The radius of curvature is smaller than the radius of curvature of the turning locus of the cam edge contact point of the set roller by an amount corresponding to the amount of overcharge of the blade driving member, and more preferably; It is characterized in that at least the end portion of the prevention member in the traveling direction is formed in an arc shape having a radius of curvature smaller than that of the set roller.

[Action]

That is, the camera shutter drive mechanism of the present invention basically holds and releases the blade drive member in accordance with the rotating operation of the rotary member, as in the conventional mechanism. The recovery prevention member, which is a feature of the present invention, holds the set member at the set position even if the set roller overruns unless a too large overrun occurs at the time of holding. Further, since the radius of curvature of the return prevention member is smaller than the radius of curvature of the set roller, even if the current brake when releasing the set member is somewhat strong, the risk of interference with the cam member is reduced accordingly.

【Example】

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows the principle of a shutter drive mechanism according to one embodiment of the present invention, and the present invention is applied to a drive mechanism of a focal plane shutter. Reference numeral 1 denotes a leading blade driving lever for opening and closing a leading blade group (not shown), which is swingably supported by a shaft 2 on the main plate. The engaging pin 1a, which is planted on the rear surface of the leading edge of the leading blade driving lever 1, penetrates a slot 3a formed in an arc shape around the shaft 2 on the main plate and engages with a leading blade group (not shown). The swing range of the leading blade drive lever 1 is limited by the slot 3a. The leading blade drive lever 1 is urged toward the forward limit by the spring 4, and when the leading blade drive lever 1 travels from the set position to the forward limit, the leading blade group (not shown) moves from the position where the exposure aperture is closed. Drive toward the position where the exposure aperture is opened. Conversely, when the leading blade drive lever 1 travels from the forward limit to the set position against the biasing force of the spring 4, the leading blade group (not shown) travels from the position where the exposure aperture is opened to the position where it is closed. It will be. Next, 5 is a trailing blade drive lever for opening and closing a trailing blade group (not shown), which is swingably supported by a shaft 6 on the main plate. The engaging pin 5a, which is planted on the rear surface of the leading edge of the trailing blade driving lever 5, penetrates through a slot 3b formed in an arc shape around the shaft 6 on the main plate and engages with the trailing blade group (not shown). The swing range of the trailing blade drive lever 5 is limited by the slot 3b. The trailing blade drive lever 5 is biased toward the forward limit by the spring 7, and when the trailing blade drive lever 5 travels from the set position to the forward limit, the trailing blade group (not shown) moves from the position where the exposure aperture is opened. Drive toward the position that closes the exposure aperture. Conversely, when the trailing blade drive lever 5 travels from the forward limit to the set position against the biasing force of the spring 7, the trailing blade group (not shown) travels from the position where the exposure aperture is closed to the position where it is opened. It will be. Next, 8 is a set bar for setting the drive levers 1 and 5 of the leading blade and the trailing blade. The long holes 8a and 8b formed along the longitudinal direction of the set bar 8 are formed in the base plate. The guide pins 3c and 3d are inserted, and the set bar 8 can move up and down within the range of the elongated holes 8a and 8b. At the outer edge of the set bar 8, there are formed a leading blade set piece 8c for setting the leading blade drive lever 1 against the spring 4 and a trailing blade set piece 8d for setting the trailing blade drive lever 5 against the spring 7. The leading blade set piece 8c and the trailing blade set piece 8d are engaged with the engagement pins 1a and 5a, respectively, in the process of lowering the set bar 8. Reference numeral 9 is an output pinion connected to the motor 10, and the shaft 11
Rotate around. A cam gear 12 meshes with the output pinion 9 and rotates about the shaft 13. A set roller 12b is rotatably attached to a shaft 12a on the cam gear 12, and a return prevention pin 12c, which is a feature of the present invention, is planted. The mutual relationship between the set roller 12b and the return prevention pin 12c is a characteristic point of this embodiment, and will be described later. A cam arm 8e extends from the outer edge of the set bar 8, and a cam edge 8f cam-joined to the set roller 12b is formed on the upper surface of the cam arm 8e. Next, 14 is a magnet for magnetically attaching the iron piece 1b formed on the leading blade drive lever 1, and the iron core 14a of the magnet 14 is supported by the spring 14b. Similarly, 15 is a magnet for magnetically attaching the iron piece 5b formed on the trailing blade drive lever 1, and the iron core 15a of the magnet 15 is supported by the spring 15b. Next, FIG. 2 is an enlarged view of the cam gear 12, and the mutual relationship between the set roller 12b and the return prevention pin 12c will be described in detail with reference to FIG. First, the radius of curvature R1 of the orbit about the axis 13 of the cam edge contact point of the set roller 12b is equal to the radius of curvature of the cam edge 8f, and the center of the axis 13 of the cam edge contact point of the return prevention pin 12c is the center. The radius of curvature R2 of the swirling trajectory is the axis 1 of the set roller 12b.
It is smaller than the radius of curvature R1 of the turning trajectory of the cam edge contact point centered on 3. However, the radius of curvature R1 of the turning locus of the cam edge contact point around the shaft 13 of the set roller 12b and the recovery prevention pin
The difference between the radius of curvature R2 of the turning locus of the cam edge contact point around the shaft 13 of 12c is smaller than the overcharge amount of the leading blade driving lever 1 and the trailing blade driving lever 5. That is, the difference between the lowering limit of the set bar 8 by the set roller 12b and the lowering limit of the set bar 8 by the return prevention pin 12c falls within the range of expansion and contraction of the springs 14b and 15b, and the return prevention pin 12c also drives the leading blade. The set bar 8 can be lowered to a position where the lever 1 and the trailing blade drive lever 5 can be initially held. The return prevention pin 12c is located rearward with respect to the turning direction (clockwise) of the cam gear 12. Also, the radius r2 of the recovery prevention pin 12c itself is set to the set roller 12b.
It is smaller than its own radius r1. Furthermore, the distance from the contact point of the set roller 12b with the cam edge 8f to the contact point of the recovery prevention pin 12c with the cam edge 8f is
Narrower than the width of f. Next, the operation of the above embodiment will be described with reference to the above matters and FIGS. 2 to 6. When the motor 10 is energized from the state shown in FIG. 1, the motor pinion 9 rotates counterclockwise about the shaft 11 and the cam gear 12 rotates clockwise. When the cam gear 12 rotates and the set roller 12b contacts the upper edge of the cam arm 8e as shown in FIG. 3, the set roller 12b pushes down the set bar 8, and in the process, the front blade set piece 8c and the rear blade are set. Each set piece 8d has an engaging pin 1a
-The front blade drive lever 1 and the rear blade drive lever 5 are turned counterclockwise while engaging 5a. When the cam gear 12 further rotates and the set roller 12b is in contact with the cam edge 8f as shown in FIG. 4, the set bar 8 is pushed down to the lower limit, and the engaging pins 1a and 5a are also moved by the slots 3a and 3b. Turn counterclockwise to the regulated set position.
At this time, the iron pieces 1b and 5b slightly push down the iron cores 14a and 15a against the support springs 14b and 15b, respectively. Then, a reverse current is supplied to the motor 10, the current brake stops the cam gear 12 in the state shown in FIG. 4, and the leading blade driving lever 1 and the trailing blade driving lever 5 are each held at the set position. By the way, if the braking force of the current brake at this time and the inertial force of the rotating member are balanced, the cam gear 12 should be stopped at the position shown in FIG. When the braking force of the current brake is insufficient for some reason, the cam gear 12 stops in the overrun state as shown in FIG. However, in the case of this embodiment, in the case of a slight overrun, the return prevention pin 12c provided behind the set roller 12b stays within the range of the cam edge 8f. Of course, as shown in FIG. 2, the radius of curvature R2 of the turning locus of the cam edge contact point of the return prevention pin 12c is smaller than the radius of curvature R1 of the turning regulation of the set roller 12b.
The set bar 8 rises slightly due to the overrun of the cam circle 8f, but the curvature radius R1 of the turning regulation of the cam edge contact point of the set roller 12b and the turning locus of the cam edge contact point of the return prevention pin 12c. Since the difference in the radius of curvature R2 is within the range of the overcharge amount of the leading blade driving lever 1 and the trailing blade driving lever 5, even if the set bar 8 is slightly raised, the expansion of the springs 14b and 15b causes the iron cores 14a and 15a to move. It is possible to maintain the state of being in contact with the iron pieces 1b and 5b, respectively. When the photographer presses a shutter button (not shown), the magnets 14 and 15 are energized, and the leading blade driving lever 1 and the trailing blade driving lever 5 are magnetically attached at the set positions. Thereafter, the motor 10 is energized, the rotation of the motor 10 is transmitted, and the cam gear 12 further rotates clockwise from the position shown in FIG. Then, for example, when the cam gear 12 rotates to the position shown in FIG. 1, a reverse current is supplied to the motor 10,
The cam gear 12 is stopped by the current brake. The set bar 8 is returned to the upper limit by the tension of the spring 8g as the set roller 12b and the return prevention pin 12c retract from the cam edge, but the leading blade driving lever and the trailing blade driving lever 5 are magnetized by the magnets 14 and 15, respectively. Be worn and maintain the set position. By the way, if the braking force of the current brake at this time and the inertial force of the rotating member are balanced, the cam gear 12 should be stopped at the position shown in FIG. When the braking force of the current brake becomes excessive for some reason, the cam gear 12 is largely reversed by the current brake, and the recovery prevention pin 12c is likely to interfere with the cam arm 8e as shown in FIG. 6, for example. Sometimes. Of course, if the stop timing of the cam gear 12 at this time is greatly delayed, for example, if the cam gear 12 is stopped in the immediate vicinity of FIG. Although it is significantly reduced, in that case, the running distance of the cam gear 12 at the time of the charging operation is reduced, so that a sufficient inertial force required for the charging operation cannot be obtained, and therefore,
There is a demand to stop the cam gear 12 as early as possible. Now, in the case of the present embodiment, as described in FIG. 2 above, the radius of curvature r2 of the recovery prevention pin 12c itself is smaller than the radius of curvature r1 of the set roller 12b itself, so excessive current braking causes the cam gear 12 to move. Even if the reverse rotation occurs, the risk of the return prevention pin 12c interfering with the cam arm can be reduced. For example, FIG. 6 shows a state in which the cam gear 12 is rotated in the reverse direction up to a limit point where the recovery preventing pin 12c does not interfere with the cam arm 8e (the one indicated by a chain line) due to excessive current braking. At this time, if the radius of curvature of the return prevention pin 12c is equal to the radius of curvature of the set roller 12b as shown by the chain double-dashed line in FIG.
e (the one indicated by the chain double-dashed line) will be greatly interfered with. As described above, in this embodiment, the recovery prevention pin 12
The radius of curvature of c is smaller than that of the set roller 12b. Therefore, the return prevention pin 12c is connected to the cam arm 8e.
There is a margin in the limit angle that does not interfere with. After that, when the magnets 14 and 15 are sequentially demagnetized with a time difference corresponding to the exposure second, the leading blade drive lever 1 and the trailing blade drive lever 5 travel sequentially to the forward limit by the springs 4 and 7, and the leading blades not shown in the figure. Performs a single exposure operation by traveling in the direction of opening the exposure aperture and in the direction of closing the exposure aperture by the rear blade (not shown). Next, FIG. 7 shows another embodiment of the present invention. That is, although the embodiment shown in FIG. 6 shows an example in which the return preventing pin 12c is arranged behind the set roller 12b, the present invention is arranged behind the set roller 12b.
Is essential to form a portion that can be maintained in the hold state, and the portion that can maintain the set lever 8 in the hold state is not necessarily a pin-shaped member. For example, in the example shown in FIG. 7, a cam 12d extending rearward of the set roller 112b is formed, and the curvature radius R of the turning locus of the cam edge contact point at the rear end portion of the cam 12d is R.
2 and the radius of curvature R1 of the set roller 12b have the same relationship as in the embodiment shown in FIG. 6 and the radius of curvature r1 of the set roller 12b itself and the radius of curvature of the rear end portion of the cam 12d.
r2 also has the same relationship as that of the embodiment shown in FIG. In the above description, the example in which the present invention is applied to the drive mechanism of the focal plane shutter has been shown, but it goes without saying that the present invention can be applied to a lens shutter other than the focal plane shutter. In the above description, the cam edge 8e is formed on the cam arm 8f extending from the set bar 8. However, the cam member having the cam edge is separately formed in association with the set bar. The set bar may be run in conjunction with the running of.

【effect】

As described above, according to the present invention, even if the motor overruns during the set operation, the set roller
As long as the return prevention pin 12c and the cam 12d provided behind the 12b are within the range of the cam edge 8f, the blade driving member can be held at the set position. Further, even when the braking force of the current brake at the time of releasing the setting member is too large, the risk of interfering with the cam arm is greatly reduced, and causes such as abnormal exposure time are less likely to occur. Therefore, according to the present invention, even if the inertial force or the braking force of the rotating member fluctuates due to the influence of aging or fluctuation of the power supply voltage, malfunction due to overrun or excessive braking is less likely to occur, and the shutter reliability is improved. The property is improved.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a relation between a radius of curvature of a turning locus of a cam edge contact point of a set roller and a radius of curvature of a turning locus of a cam edge contact point of a return prevention pin. FIG. 3 is an enlarged view showing the relationship between the radius of curvature of the set roller and the radius of curvature of the return prevention pin, FIG. 3 is a plan view showing the state immediately before the set bar is lowered, FIG. 4 is a plan view showing the initial hold state, and FIG. FIG. 6 is an explanatory diagram of a case where the hold state can be maintained even if an overrun occurs at the set position, and FIG. 6 is an explanatory diagram of a case where interference with the cam arm can be prevented even if reverse rotation occurs when the set bar is released, FIG. 7 is a plan view showing another embodiment of the present invention. 1 ... Front blade drive lever, 5 ... Rear blade drive lever 8 ... Set bar, 8f ... Cam edge 12 ... Cam gear, 12b ... Set roller 12c ... Return prevention pin, 12d ... Return prevention cam

Claims (4)

(57) [Scope of utility model registration request] 1. A blade drive member that is connected to a shutter blade and is urged in a direction that exposes the shutter blade, and is movable in a direction that moves the blade drive member to a set position. A set member biased in a direction opposite to the direction in which the blade drive member is moved to the set position; and a set member formed in relation to the set member, in the direction in which the blade drive member is moved to the set position. The arc-shaped cam edge that receives a force to drive it and the rotation of the motor that rotates in substantially one direction are transmitted, and the radius of curvature of the turning locus of the cam edge contact point is the arc-shaped cam edge. Is equal to the radius of curvature of the blade driving member, the set member is moved to the set position of the blade driving member by coming into contact with the cam edge, and is separated from the cam edge to move the set member. A rotary member having a set roller for releasing the blade member, and holding the blade drive member at the set position by stopping the rotary member while the set roller is in contact with the arcuate cam edge. In addition, in the drive mechanism of the camera shutter, the set member is released by stopping the rotating member while the set roller is separated from the arcuate cam edge. A return for suppressing return travel of the set member from the set position of the blade drive member to a position behind the set roller and at a distance from the set roller that is shorter than the width of the arcuate cam edge. A drive mechanism for a camera shutter, which is provided with a prevention member. 2. The drive mechanism for a camera shutter according to claim 1, wherein the return prevention member is on the rotating member, behind the set roller, and at a distance from the set roller. Is a return prevention pin that is planted at a position shorter than the width of the arcuate cam edge. 3. The drive mechanism for a camera shutter according to claim 1 or 2, wherein the blade drive member can be overcharged beyond the set position, and the cam of the return prevention member is provided. A driving mechanism for a camera shutter, wherein a radius of curvature of a swirl locus of an edge contact point is smaller than a radius of curvature of a swirl locus of a cam edge contact point of the set roller by an amount corresponding to an overcharge of the blade drive member. 4. The drive mechanism for a camera shutter according to claim 1, 2, or 3 of the utility model registration claim, wherein at least the end portion of the return preventing member in the traveling direction of the set roller is provided with the set roller. A drive mechanism for a camera shutter, which is formed in an arc shape having a radius of curvature smaller than a radius of curvature.