JPH0725782Y2 - Re-exposure prevention mechanism in camera shutter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention particularly relates to a re-exposure prevention mechanism in a lens shutter device for a camera.

[Problems to be solved by conventional techniques and devices]

Conventionally, in order to increase the shutter speed, there is a demand for shortening the rise time of the shutter blade opening and the fall time thereof. For example, in a shutter device including a shutter blade, a shutter blade driving member, and a drive source that controls opening and closing of the shutter blade via the shutter blade driving member, in order to realize such a request, the shutter blade after opening is closed. There is one that increases the force and makes the shutter closing speed faster.

However, in such a method, there is a problem that the inertia of the shutter blade causes the shutter blade to bounce at the shutter blade fully closed position, and at this time, re-exposure becomes easy. Thus, it is difficult to effectively increase the shutter speed by simply increasing the shutter blade speed.

In view of such circumstances, it is an object of the present invention to provide a re-exposure prevention mechanism for a lens shutter that can effectively prevent the shutter blade from bouncing and effectively increase the shutter speed.

[Means for Solving the Problems]

A re-exposure prevention mechanism in a camera shutter device according to the present invention is provided with an inflection point on a cam surface of a cam portion of a shutter blade drive member to which a drive pin of a drive source should slide in order to close the shutter blade. In the closing stroke, the shutter blade speed from the shutter blade fully open position or the small aperture opening position to the pinhole position and the shutter blade speed from the pinhole position to the shutter blade fully closed position are made different.

[Action]

According to the present invention, in the shutter blade closing process, the shutter blade speed can be increased until the pinhole position is reached, and the shutter blade speed from the pinhole position to the fully closed position can be reduced. Therefore, the shutter speed becomes substantially high, and re-exposure can be prevented by eliminating the occurrence of bouncing due to the inertia of the shutter blade at the shutter blade fully closed position.

〔Example〕

An embodiment of a re-exposure prevention mechanism in a camera shutter device according to the present invention will be described below with reference to FIGS. 1 to 7. In the figure, 1 is a shutter base plate, 2 and 2'is shutter blades pivotally attached to the base plate 1 (in FIG. 1, the closed state is shown by a solid line), 3 is a connecting pin 4,
A shutter blade drive lever 5 for opening and closing the shutter blades 2, 2'through 4 ', 5 is a shutter blade drive lever 3
1, a spring for imparting left-handedness to the pivot 6 is shown in FIG. 1, 7 is an autofocus ring for advancing and retracting the lens by its pivoting action, 8 is an aperture, and 9 is its drive pin 9a shown in a non-energized state. The above auto focus, which is designed to be brought to a neutral position,
An iris motor 10, which is a driving source for controlling the operation of the ring 7 and the shutter blade opening / closing control, is wound around and instructed by pins 11 and 11 'planted in the main plate 1, and both tip portions 10a and 10a' thereof are directed. Is a spring that elastically contacts so as to hold the drive pin 9a in its neutral position. Here, the cam surface 3a on which the drive pin 9a can slidably contact the shutter blade drive lever 3
_A cam portion 3a composed of ₁ and 3a ₂ and their inflection points 3a ₃ is formed, and when the shutter blade drive lever 3 is rotated to the right by the left rotation of the drive pin 9a, after the inflection point 3a _{3 is} passed. shutter blades both right旋速of the driving lever 3 is cam profile of the cam portion 3a so slower is formed, pinholes position of the shutter blades 2, 2 'on contact with the driving pin 9a and inflection point 3d ₃ Are set to correspond. Furthermore,
12 is provided with a left-handed habit around a pivot 13 by a spring 14, and the locking portion 12a can engage with the tip end portion 3b of the shutter blade drive lever 3 to hold the shutter blades 2, 2'in a closed state. It is a locking lever that is designed.

Since the re-exposure prevention mechanism in the camera shutter device according to the present invention is constructed as described above, first, in the initial state of photographing, the iris motor 9 is in a non-energized state, so that the drive pin 9a is in the neutral position by the spring 10. The shutter blade drive lever 3 is held by the lock lever 12 biased by a spring 14 so that the shutter blade is closed (FIG. 3). Then, the drive pin 9a of the iris motor 9 which is turned clockwise by the shutter blade opening signal (FIG. 1) is at the right turn end point position (9a '), and the arm portion 12b of the locking lever 12 is turned on.
Since the locking lever 12 is rotated rightward by contacting with the front end of the shutter blade drive lever 3, the shutter blade drive lever 3 starts the opening operation with the front end portion 3b being released from the engagement by the locking portion 12 (FIG. 4).

The drive pin 9a waits for a predetermined time at the clockwise end point position (9a '),
Although it is reversed (counterclockwise), the shutter blades are fully opened or a small aperture is formed according to the command standby time determined by the AE light information from the camera body side. That is, the timing at which the cam portion 3a of the shutter blade drive lever 3 that has rotated counterclockwise (opening operation) comes into contact with the drive pin 9a that waits for a time corresponding to the setting AE and reverses (clockwise rotation) depends on the setting AE. For example, in the case of a small aperture, the shutter blade drive lever 3 starts contacting the drive pin 9a at the position shown by the dotted line in FIG.

Then, the shutter blade closing stroke, until the driving pin 9a induced to left-handed by an iris motor 9 reaches the inflection point 3a ₃ along the cam surface 3a ₁ of the cam portion 3a (FIG. 5), the shutter blades As shown in Fig. 7, 2, 2'actuate from the fully open (or small aperture) state to the abruptly closed state until the pinhole position is reached (the drive pin 9a is in the neutral position at this pinhole position). ). During this time, although the shutter blade speed has become extremely high, further passed through the driving pin 9a is an inflection point 3a _3, right- shutter blade driving lever 3 according to the shape of the cam surface 3a ₂ When proceeding to the cam surface 3a ₂ speed,
That is, the shutter blade speed sharply decreases significantly. In this way, the drive pin 9a moves from the neutral position to the left turn end position (6th
(Fig.), That is, before the shutter blades 2,2 'reach the fully closed position from the pinhole position.
As a result, the inertia of 2,2 'can be almost eliminated,
Bounds in the fully closed position of the shutter blades 2, 2'can be eliminated, so that the risk of re-exposure can be completely prevented. In addition, since the drive pin 9a is brought to the left-hand end point position, the engagement portion 12a of the engagement lever 12 which is biased in the left-handed direction by the spring 14 becomes the tip portion 3b of the shutter blade drive lever 3 again. As they become engaged,
After reaching the left-hand end point position, the iris motor 9 is de-energized after a lapse of a predetermined time. When shooting like this,
Since the movement of the shutter blades 2 and 2'is slowed after the pinhole position where the shutter opening does not affect the shutter speed, the shutter speed becomes substantially slower, and re-exposure can be reliably prevented with a simple structure. Incidentally, as described above in the description of the conventional example, when the closing stroke speed of the shutter blades 2, 2'is simply increased, the shutter blades 2,
Since the speed of 2'is still high at the fully closed position as shown by the dotted line in FIG. 7, it is obvious that the shutter blades 2, 2'cannot be bound.

The position of the inflection point 3a ₃ of the cam portion 3a of the shutter blade driving lever 3 of the above embodiment, the shutter blades 2, 2 pinhole position the drive pins 9a than the neutral position of the drive pin 9a of the '
Since it can be set so as to correspond to the right rotation direction side of the actuator 9, for example, the actuator 9 on the left rotation direction side of the neutral position.
It becomes possible to provide a contact (contact piece) for taking out a shutter blade closing signal within the output range of the actuator 9 for the operation of the above-mentioned operation, and a lens feeding claw member (not shown) for autofocusing. ) Feeding operation and the like can be performed simultaneously.

[Effect of device]

As described above, according to the present invention, by effectively controlling the shutter blade speed, the shutter speed can be increased and the re-exposure can be prevented at the same time, and the structure therefor can be relatively simple. And so on.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part of an embodiment of a re-exposure prevention mechanism in a camera shutter device according to the present invention, and FIG. 2 is a partial vertical cross-sectional view of the re-exposure prevention mechanism, FIG. 3, FIG. 4, FIG. 5 and 6 are partial plan views for sequentially explaining the operational relationship between the shutter blade drive lever and the drive pin according to the present invention, and FIG. 7 is a view showing a temporal change of the shutter opening amount. 1 ... Shutter base plate, 2, 2 '... Shutter blade, 3 ...
Shutter blade drive lever, 5,14 ... Spring, 7 ... AF
Ring, 9 ... Iris motor, 10 ... Spring, 12 ... Locking lever.

Claims (2)

[Scope of utility model registration request] 1. A shutter blade, a shutter blade driving member connected to the shutter blade so as to urge the shutter blade toward the opening direction, and opening / closing control of the shutter blade via the shutter blade driving member. In a shutter device for a camera including a drive source, an inflection point is provided on a cam surface of a cam portion of the shutter blade drive member with which a drive pin of the drive source slides to close the shutter blade, and the shutter blade is closed. A re-exposure prevention mechanism characterized in that the operating speed of the shutter blades can be changed during the course of the stroke. 2. The utility model registration characterized in that the operating speed of the shutter blade in the opening and closing process of the shutter blade is such that the operating speed after the inflection point is slower than the operating speed up to the inflection point. The re-exposure prevention mechanism according to claim (1).