JPH0731225Y2 - Focal plane shutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a focal plane shutter for a camera that opens and closes a shutter opening with an open shutter blade unit and a closed shutter blade unit.

[Conventional technology]

As a camera shutter, there is a focal plane shutter arranged in front of a film loaded in the camera.
Focal plane shutters often include an open shutter blade unit in which a plurality of shutter blades are stacked and a closed shutter blade unit in which a plurality of shutter blades are stacked in response to recent demands for weight reduction and compactness. It is used. The open shutter blade unit that covers the shutter opening opens the shutter opening, and the closed shutter blade unit closes the shutter opening after a predetermined time has elapsed according to the shutter speed. In this way, the open shutter blade unit and the closed shutter blade unit cooperate to perform proper exposure.

An example of such a focal plane shutter is shown in FIG. 6 (see Japanese Patent Publication No. 59-21536). This focal plane shutter includes an open shutter blade unit having two shutter blades 101 and 102 and two shutter blades 103, 103 before the shutter release operation.
The shutter aperture 105 is covered by a closed shutter blade unit having 104 to prevent light from the taking lens from leaking to the film surface loaded in the camera. When the shutter release operation is performed, the closing shutter blade unit is once housed by the driving force of the operating spring (not shown), and is located above the shutter opening 105 in the figure to open it. Thereafter, as described above, the open shutter blade unit causes the shutter opening 105 to move by the opening edge P of the shutter blade 101.
, And then the closing shutter blade unit closes the shutter opening 105 by the closing edge Q of the sitter blade 103.

[Problems to be solved by the device]

However, in such a focal plane shutter, although it is possible to prevent the light from the taking lens from leaking to the film surface, the closing shutter blade unit is temporarily stored by the operating spring and the shutter opening is performed.
It must be located above 105, and it may not be possible to meet the photo opportunity. Therefore, it is conceivable to increase the spring force of the operating spring in order to shorten the time for positioning the closed shutter blade unit above the shutter opening 105. In this case, there is a problem in that the charge weight of the closed shutter blade unit increases and, as shown in FIG. 7, when the shutter is stopped above the shutter opening, a bounce occurs and proper exposure cannot be performed.

Therefore, in order to prevent such a bouncing of the closing shutter blade unit, there is a method of applying a friction brake as described in Japanese Utility Model Laid-Open No. 55-162225. However, in this method, the operation of the friction brake is extremely unstable, and the stop position of the closing edge of the closing shutter blade unit changes depending on the strength of this frictional force (for example, position Q _{11 in} FIG. 7). However, there is still the problem that proper exposure is not performed.

In order to prevent the closing shutter blade unit from bouncing, a locking member is locked to the closing shutter blade unit at the locking position of the closing shutter blade unit as shown in Japanese Utility Model Publication No. 59-43540. There is. In this case, since the closing shutter blade unit is locked by the locking member, the bouncing is surely prevented. However, once the locked state is not released due to a failure or the like, or if an attempt is made to perform the exposure end operation of the closed shutter blade immediately after the exposure start operation of the open shutter blade to improve the shutter chance, this locked state will be There is a problem that it becomes an obstacle when the closing shutter blade is operated.

[Means for Solving the Problems] In order to solve such problems, in the present invention,
An opening shutter blade that operates by a shutter release to open the shutter opening and a closing shutter blade that operates after the opening operation of the shutter blade to close the shutter opening are provided, and the shutter opening is shielded by the closing shutter blade. Immediately before the opening operation of the opening shutter blade, a one-way delay mechanism that reduces only the retracting speed of the closing shutter blade is provided in the focal plane shutter that retracts the closing shutter blade from the shutter opening. is there.

[Action]

Before the shutter release operation, the closing shutter blade closes the shutter opening. When you operate the shutter release,
In conjunction with this operation, the closing shutter blade retracts from the shutter opening. At this time, the retracting speed of the closing shutter blade is reduced by the delay mechanism, and the closing shutter blade moves to the position on the side of the shutter opening without bouncing.

The open shutter blades perform an exposure start operation, and after a predetermined time has elapsed, the closed shutter blades perform an exposure end operation. At this time, since the delay mechanism prevents the closed shutter blades from bouncing, the closed shutter blades can be quickly moved to a position on the side of the shutter opening. For this reason, immediately after the exposure start operation of the open shutter blade, the closing shutter blade can perform the exposure end operation earlier in combination with the light charging force at this time.

Further, since the closing shutter blade prevents the occurrence of bouncing by the delay mechanism, the braking force applied to the closing shutter blade is always constant.

〔Example〕

Hereinafter, the present invention will be described with reference to the drawings. 1 to 5 are views showing an embodiment of a focal plane shutter according to the present invention.

First, the configuration will be described.

In FIG. 1, reference numeral 1 is a substrate disposed in front of the film surface loaded in the camera and on the side of the photographing lens. The substrate 1 has a shutter opening 1a and an electromagnet and an operating spring. Etc. (not shown) are attached to the drive unit. An open shutter blade unit 2 for opening the shutter opening 1a and a closed shutter blade unit 3 for closing the shutter opening 1a are arranged on the substrate 1.

The open shutter blade unit 2 is composed of an open slit blade 4 and a cover blade 5. The open slit blade 4 and cover blade 5 are pin-connected to a pair of parallel arms, an open arm 6 and an open auxiliary arm 7. The open arm 6 and the open auxiliary arm 7 are rotatably attached to the substrate 1 via pins 8 and 9. Similarly, the closing shutter blade unit 3 is also composed of a closing slit blade 10 and a covering blade 11, and the closing slit blade 10 and the covering blade 11 are pin-connected to a closing arm 12 and a closing auxiliary arm 13 as parallel links,
The closing arm 12 and the closing auxiliary arm 13 are rotatably attached to the substrate 1 via pins 14 and 15.

A receiving plate 16 is mounted on the substrate 1 on which the open shutter blade unit 2 and the closing shutter blade unit 3 are arranged, and the receiving plate 16 is provided with a drive mechanism for driving the closing shutter blade unit 3. ing. That is, as shown in FIG. 2, the first fitting into the engagement hole 12a of the closing arm 12
A closing lever 17 having an engaging pin 17a is rotatably provided on the receiving plate 16 via a pivot pin 18. Further, the closing lever 17 is provided with a second engaging pin 17b on the opposite side of the first engaging pin 17a. A locking lever 19 that rotates in conjunction with the shutter release operation is provided on the receiving plate 16 so as to be engageable with the first engagement pin 17a of the closing lever 17, and resists the tensile force of the first tension spring 20. When the locking lever 19 is rotated counterclockwise, the engagement state with the closing lever 17 is released.

A closing drive lever 21 is rotatably attached to the pivot pin 18 together with the closing lever 17, and a second tension spring 22 is stretched between the closing drive lever 21 and the closing lever 17. Second between the closing drive lever 21 and the backing plate 16
A third tension spring 23 having a stronger spring force than the tension spring 22 is stretched, and the closing drive lever 21 is always urged clockwise by the third tension spring 23.

Further, the closing drive lever 21 is formed with a first engagement protrusion 21a and a second engagement protrusion 21b, and as shown in FIG.
The engagement protrusion 21a can come into contact with and engage with the second engagement pin 17b provided on the closing lever 17. The second engaging protrusion 21b is a receiving plate
It is possible to engage with a closing claw 24 that is rotatably provided on 16.

When the closing claw 24 is rotated counterclockwise against the urging force of the fourth tension spring 25, the engagement state with the second engagement protrusion 12b is released as shown in FIG. The closing drive lever 21 is turned clockwise by the pulling force of the third tension spring 23, and since the second engaging pin 17b is engaged with the first engaging protrusion 21b, the closing lever 17 is also turned clockwise at the same time.

By the way, when the engagement state of the closing lever 17 with the locking lever 19 is released, as shown in FIG. 3, the closing lever 17 rotates counterclockwise by the urging force of the second tension spring 22, but at this time, the first engaging pin 17a Is a sector gear 26 rotatably provided on the receiving plate 16.
Abutting on the protrusion 26a. The sector gear 26 is meshed with the pinion 27, the pinion 27 is double provided on the receiving plate 16 so as to rotate integrally with the escape wheel 28, and the escape wheel 28 is swingably provided on the receiving plate 16. The pallet fork 29 can be engaged. When the pallet fork 29 swings and the claws engage with the claws of the escape wheel 28, the escape wheel 28 is intermittently and regularly rotated by one tooth. Where sector gear 26, pinion
27, escape wheel 28 and pallet 29 as a whole delay mechanism
When the closing lever 17 rotates counterclockwise and the first engaging pin 17a contacts the projection 26a of the sector gear 26, the delay mechanism 31 reduces the counterclockwise rotation speed of the closing lever 17. Further, the sector gear 26 is always pulled in the counterclockwise direction by the fifth tension spring 30.

In order to charge the closing lever 17 to the state shown in FIG. 2, the pin 21c on the closing drive lever 21 is turned counterclockwise by a charge lever (not shown) to close the closing drive lever.
21 and the closing claw 24 are engaged.

Next, the operation will be described.

Before the shutter release operation, the closed shutter blade unit 3 and the open shutter blade unit 2 are the shutter openings.
Double blocking of 1a prevents light from the shooting lens from leaking to the film surface. That is, the closing lever 17 engaging with the closing arm 12 is rotated clockwise as shown in FIG. 2 and the first engaging pin 17 a is locked to the locking lever 19.

Therefore, when the shutter release operation is performed, the locking lever 19 rotates counterclockwise against the pulling force of the first tension spring 20 as shown in FIG. 3 in conjunction with this operation, and the closing lever 17 moves the second tension spring. Turn left by a pulling force of 22.
When the closing lever 17 turns counterclockwise, it engages with it.
12 is left-handed in FIG. 1 and is a closed slit blade 10, cover blade
11 is superimposed on the upper side of the shutter opening 1a, and the closed shutter blade unit 3 is retracted from the shutter opening 1a.

When the closing lever 17 turns counterclockwise, the first engaging pin
The protrusion 17a contacts the protrusion 26a of the sector gear 26. When the first engagement pin 17a comes into contact with the protrusion 26a, the sector gear 26 rotates, and the escape wheel 28 rotates via the pinion 27 that meshes with the sector gear 26. Since the pallet fork 29 is engaged with the escape wheel 28, the escape wheel 28 is intermittently rotated by one tooth at regular intervals. As the escape wheel 28 is thus intermittently rotated by one tooth at regular intervals, the sector gear 26 is gently rotated via the pinion 27.

Therefore, when the counterclockwise closing lever 17 contacts the protrusion 26a of the sector gear 26, the counterclockwise speed (retraction speed) is decelerated by the delay mechanism 31, the closing lever 17 stops, and the closing shutter blade unit 3 opens the shutter opening. Evacuate from 1a. When the closing lever 17 stops, the second tension spring
The second engagement pin 17b comes into contact with the first engagement protrusion 21a by 22 and the closing lever 17 is integrated with the closing drive lever 21.
At this time, since the closing lever 17 is applied only with the pulling force of the second tension spring, the charging force is light.

Next, the opening arm 6 is turned clockwise in FIG. 1, and the opening slit blade 4 and the cover blade 5 of the opening shutter blade unit 2 move downward to open the shutter opening 1a.

When the opening shutter blade unit 2 is opened, the closing claw 24 is rotated counterclockwise against the pulling force of the fourth tension spring 25, as shown in FIG. Is released. When the engagement state of the closing drive lever 21 is released, the closing lever 17 is turned right by the pulling force of the third tension spring 23.

When the closing lever 17 is turned to the right, the closing arm 14 is also turned to the right in FIG. 1, and the closing slit blade 10 and the cover blade 11 move downward in the drawing. Thus, the rear end P of the open slit blade 4 in the opening direction and the front end Q of the closed slit blade 10 in the closing direction.
A slit is formed with and this slit is the shutter opening.
The exposure is performed by moving from the upper end side of 1a to the lower end side.

Here, the operation of the open slit blade 4 and the closed slit blade 10 is shown in FIG. 5. First, since the closed slit blade 10 shields the shutter opening 1a before the shutter release operation, the tip of the closed slit blade 10 is shown. Q is positioned Q _{0 above the} shutter opening 1a.

When the shutter release operation is performed, the closing slit blade 10 retracts from the shutter opening 1a in conjunction with this operation, so that the tip Q moves to the upper side of the shutter opening 1a. At this time,
The counterclockwise rotation speed of the closing arm 12 is reduced by the delay mechanism 31, and the tip Q of the closing slit blade 10 moves to the position Q ₁ at a distance 1 from the upper side of the shutter opening 1a without bouncing.

Immediately before the tip Q of the closed slit blade 10 is located at the distance l, the open slit blade 4 that shields the shutter opening 1a.
The rear end P is located at a distance l from the shutter opening 1a,
The exposure start operation is performed by moving at an accelerated speed while drawing a curve from this position.

Then, the tip Q of the closed slit blade 10 after a predetermined time has passed
Performs an exposure end operation by acceleratingly moving while drawing a curve from a position Q _{2 at a} distance 1 from the shutter opening 1a. Therefore, the rear end P of the open slit blade 4 and the closed slit blade
The tip Q of 10 is the same distance l from the upper side of the shutter opening 1a.
Since the exposure start operation and the exposure end operation are respectively performed from positions distant from each other, the exposure is properly performed.

Further, the tip Q of the closed slit blade 10 is prevented from bouncing by the delay mechanism 31, so that it can be quickly moved to the position Q ₁ at the distance 1 from the shutter opening 1a. Therefore, immediately after the exposure start operation of the rear end P of the open slit blade 4, the tip Q of the closed slit blade 10 is coupled with the fact that the charging force at this time is light, and as shown by the dashed line from the position Q _1. In addition, the exposure end operation can be quickly performed. Therefore, it is possible to improve the shutter chance without obstruction in accordance with the increase in shutter speed such as 1/8000 sec.

Furthermore, since the tip Q of the closed slit blade 10 is prevented from bouncing by the delay mechanism 31, the braking force related to the tip Q is always constant. Therefore, the stop positions Q1 and Q2 of the tip Q of the closed slit blade 10 do not change, and proper exposure can be performed.

[Effect of device]

As described above, according to the present invention, since the delay mechanism that reduces the retracting speed of the closing shutter blade is provided, the occurrence of bouncing when the closing shutter blade retracts is prevented, and it is possible to quickly move to the side of the shutter opening. Can be located at. For this reason, immediately after the exposure start operation of the open shutter blade, the closing shutter blade can perform the exposure end operation earlier in combination with the fact that the charging force at this time is light. Therefore, it is possible to improve the shutter chance without obstruction according to the increase in shutter speed. Further, since the braking force applied to the closing shutter blade is always constant, proper exposure can be performed without changing the stop position of the closing shutter blade on the side of the shutter opening.

[Brief description of drawings]

1 to 5 are views showing an embodiment of a focal plane shutter according to the present invention, and FIG. 1 is a plan view showing a state in which an opening shutter blade and a closing shutter blade block a shutter opening, FIG. 2 is a plan view showing a drive mechanism and a delay mechanism for driving the closing shutter blade, FIGS. 3 and 4 are plan views showing the operation of the drive mechanism and the delay mechanism, respectively, and FIG. 5 is a view showing the operation of the shutter. 7 is a graph showing a relationship between a shutter opening and time. 6 and 7 are views showing a conventional focal plane shutter, FIG. 6 is a plan view showing a state in which an opening shutter blade and a closing shutter blade block the shutter opening, and FIG. 7 is a shutter. 6 is a graph showing the operation of the above in relation to the shutter opening and time. 2 ... Open shutter blade unit, 3 ... Closed shutter blade unit, 4 ... Open slit blade, 10 ... Closed slit blade, 31 ... Delay mechanism.

Claims (1)

[Scope of utility model registration request] 1. An opening shutter blade that operates by a shutter release to open a shutter opening, and a closing shutter blade that operates after the opening operation of the shutter blade to close the shutter opening. The closing shutter blade opens the shutter opening. In the focal plane shutter that retracts the closing shutter blade from the shutter opening immediately before the opening operation of the opening shutter blade, a one-way speed reducing mechanism that reduces only the retracting speed of the closing shutter blade is provided. A focal plane shutter characterized by the above.