Photography – Camera detail – Shutter
Reexamination Certificate
2002-07-02
2004-03-09
Gray, David M. (Department: 2851)
Photography
Camera detail
Shutter
C396S497000
Reexamination Certificate
active
06702484
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a shutter for use in a camera, and more particularly to a shutter that prevents reexposure due to rebounding of the sectors when the shutter is in the fully closed state.
2. Description of the Related Art
One camera shutter of the related art is shown in
FIGS. 4-6
, where a driving lever
26
is rotated by a rotor shaft of an actuator M. A driving pin
27
is mounted on the driving lever
26
. A base plate
21
is provided with an elongate hole portion
21
b
. The driving pin
27
extends through the hole portion
21
b
and through through-holes
24
b
and
25
b
formed in sectors
24
and
25
, respectively. The sectors
24
and
25
are mounted to pivot or swing about shafts
22
and
23
, respectively. The driving pin
27
is so constructed that it makes sliding contact with the through-holes
24
b
and
25
b.
In the related art structure described above, when the shutter is fully opened as shown in
FIG. 4
, the driving pin
27
is in contact with one end portion of the hole portion
21
b
and the shaft
23
is at rest in contact with a recessed portion of the sector
24
. As shown in
FIG. 5
, when the driving lever
26
is rotated by the rotor shaft of the actuator M, the driving pin
27
begins to move. The driving pin
27
moves away from the end portion of the hole portion
21
b
, and the motion of the driving pin
27
is transmitted to the sectors
24
and
25
. When the shutter is fully closed, the driving pin
27
is in contact with the other end portion of the hole portion
21
b
as shown in
FIG. 6
, and the shutter opening
21
a
is closed by the sectors
24
and
25
. When the driving pin
27
drives the sectors
24
and
25
to the fully closed state, the driving pin
27
collides against the other end portion of the hole portion
21
b
and bounces or rebounds off the end portion. Since the sectors
24
and
25
are interlocked with the driving pin
27
, the rebounding of the driving pin
27
causes the sectors
24
and
25
to swing back and forth in the opening and closing directions.
Therefore, if the amount of overlap between the sectors
24
and
25
is small, the problem arises that the shutter opening
21
a
is repeatedly opened and closed a slight amount when in the fully closed state. As a consequence, there is the danger that light leaks through the shutter opening
21
a
and makes a reexposure. Accordingly, to prevent reexposure, the amount of overlap between the sectors
24
and
25
must be set to a large value. However, if the amount of overlap is made larger, this prevents reducing the size of the shutter. Furthermore, this makes it difficult to improve the shutter speed, because the shutter blades are made larger and are therefore heavier.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a camera shutter which prevents reexposure when the shutter is in a fully closed state and permits miniaturization of the shutter and improvement in shutter speed.
A shutter for use in a camera in accordance with the present invention has a shutter opening formed in a base plate, plural sectors capable of opening and closing the shutter opening, and an operating member driven by an actuator for operating the sectors. The operating member extends through through-holes formed in the sectors. The through-hole in at least one of the sectors is so configured that a gap is formed in the direction of movement of the operating member.
By such a structure, when the shutter speed is sufficiently accelerated and the shutter opening is closed, if the operating member bounces or rebounds, the gap formed in the sector through-hole prevents the sector from directly interlocking with bounce or rebound of the operating member. Instead, this sector can still move in the direction of closing the shutter opening owing to inertia. Accordingly, when the other sector or sectors interlock with the bounce or rebound of the operating member and move in the direction to open the shutter opening, the former sector keeps moving in the direction of closing the shutter. Therefore, even if the amount of overlap between the sectors at full closure is reduced to a minimum, no reexposure occurs. Consequently, the shutter blades and hence the whole shutter can be miniaturized. Furthermore, by reducing the size and hence the weight of the shutter blades, the shutter speed is improved.
REFERENCES:
patent: 5432576 (1995-07-01), SanGregory et al.
patent: 6123468 (2000-09-01), Furlani et al.
patent: 2002/0094204 (2002-07-01), Mizukami et al.
patent: 2003/0021604 (2003-01-01), Yamaga et al.
Mizukami Hiroyuki
Oishi Seiichi
Yamaga Munetaka
Adams & Wilks
Gray David M.
Seiko Precision Inc.
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