Diaphragm device

Details Diaphragm device Diaphragm device

2001-02-05

2002-10-29

Phan, James (Department: 2872)

Optical: systems and elements

Light control by opaque element or medium movable in or...

C359S230000, C396S449000, C396S463000, C396S485000, C396S494000

Reexamination Certificate

active

06473217

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a diaphragm device for changing a shutter aperture diameter in a step-wise manner.
2. Description of the Related Art
A known diaphragm device is described in Japanese Patent Laid-open No. 79541/1993 by the present assignee. This known diaphragm device will be explained with reference to FIG.
8
.
In
FIG. 8
, a rotor
10
formed by a permanent magnet, a rotor actuated lever
11
, a diaphragm actuating member
12
and a small-diaphragm plate
73
are pivotably supported on a main plate (not-shown) through a rotor shaft
10
a
, a shaft
12
a
and a shaft
4
. The small-diaphragm plate
73
has a sufficient overall size to cover the shutter aperture
2
and has a small-diameter diaphragm aperture
73
a
. The small-diaphragm is pivotably supported by the shaft
4
to move between a first position A fully covering the shutter aperture
2
and a second position B fully retracted from the aperture
2
. Also, the small-diaphragm plate
73
is urged in a clockwise direction in the drawing by a spring
73
c
and abutted against and rested on a positioning pin
5
.
The diaphragm actuating member
12
is latched and biased in a counterclockwise direction in the drawing by a spring
13
, and is abutted against an engagement pin
14
.
When a coil L is energized to excite the stator
9
, the rotor
10
rotates in a counterclockwise direction and the rotor actuated lever
11
fixed on the rotor shaft
10
a
also rotates in a counterclockwise direction. This rotation causes the diaphragm actuating member
12
to rotate in a clockwise direction through a rotor actuated lever pin
11
a
. Through a protrusion
12
b
of the diaphragm actuating member
12
, the small-diaphragm plate
73
is rotated counterclockwise about the shaft
4
from the second position B to the first position A where it goes into abutment against a positioning pin
15
. Consequently, the shutter aperture
2
is restricted by a diaphragm aperture
73
a
. At this time, a pin
73
b
fixed on the small-diaphragm plate
73
moves a movable iron piece
18
along an attraction surface of an iron core
17
a
. At a time that the small-diaphragm plate
73
reaches the first position A, an electromagnet
17
b
is excited to attract and hold the movable iron piece
18
, maintaining the small-diameter diaphragm aperture
73
a.
In this related-art diaphragm device, the small-diaphragm plate
73
is structured by one plate and has a sufficient size to fully cover the shutter aperture
2
. Because the small-diaphragm plate
73
has a size large enough to cover the shutter aperture
2
when in the first position A, it must be moved by a large amount to the second position B to be fully retracted from the shutter aperture
2
. This requires the small-diaphragm plate
73
to be dimensioned to provide a large space for retraction, resulting in an increased size in the vicinity of the shutter aperture
2
.
SUMMARY OF THE INVENTION
In order to solve the above problem, a small-diaphragm plate is provided with a diaphragm aperture smaller in diameter than a shutter aperture and an auxiliary plate so that when the small-diaphragm plate is selected, the small-diaphragm plate and the auxiliary plate cooperate to cover the shutter aperture. Since the small-diaphragm plate is provided in a divided manner to cooperate with the auxiliary plate, the small-diaphragm plate can be made smaller in area than in the conventional device, making it possible to reduce the size of the diaphragm device.
A diaphragm device according to one aspect of the present invention comprises a small-diaphragm plate having a diaphragm aperture smaller in diameter than a shutter aperture and being movable between a first position at which the diaphragm aperture is positioned in the shutter aperture and a second position at which the diaphragm aperture is retracted from the shutter aperture, an auxiliary plate cooperating with the small-diaphragm plate to cover the shutter aperture, and a diaphragm actuating member for actuating the small-diaphragm plate or the auxiliary plate, wherein actuation of the diaphragm actuating member causes the small-diaphragm plate to be moved to the first position and the auxiliary plate to be moved to a first position covering the shutter aperture, and actuation of the diaphragm actuating member in the other direction causes the small-diaphragm plate to be moved to a the second position and the auxiliary plate to be moved to a second position retracted from the shutter aperture. Because the shutter aperture is covered by cooperation of the small-diaphragm plate and the auxiliary plate, the small-diaphragm plate can be made smaller than in the related device, making possible to reduce the dimensions in the periphery of a shutter.
The auxiliary plate may be positioned on a side opposite to or the same side of the shutter aperture as the small-diaphragm plate when the small-diaphragm plate is positioned in the second position. This structure improves the freedom in arrangement of parts around the periphery of the shutter.
Actuation of the diaphragm actuating member in one direction may be conveyed through the small-diaphragm plate to the auxiliary plate to move both in unison or may be conveyed through the auxiliary plate to the small-diaphragm plate to move both in unison. This structure improves the shape and freedom of the arrangement of parts. Also, the diaphragm actuating member if driven by a motor will achieve automation of the diaphragm device.


REFERENCES:
patent: 6343881 (2002-02-01), Yaginuma

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