Stop device

Details Stop device Stop device

1999-08-20

2002-09-03

Mahoney, Christopher (Department: 2851)

Photography

Camera detail

Diaphragm

Reexamination Certificate

active

06443636

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stop device for use in optical equipment.
2. Description of the Related Art
Conventionally, a lens barrel using a flare stop is known as proposed in Japanese Unexamined Patent Publication No. 5-188274. The sectional views of
FIGS. 8A
,
8
B and
8
C show the operating state of the flare stop. The flare stop device of the lens barrel comprises a third lens barrel
60
, which is advanced and retracted to and from a fixed frame
101
by a zooming operation and a collapsing operation, a float key
80
, whose distance in an optical-axis direction changes with respect to the fixed frame
101
and the third lens barrel
60
in the zooming operation and the collapsing operation, a flare stop
100
, which is locked to the float key
80
and interposed between the fixed frame
101
and the third lens barrel
60
, and so forth.
The flare stop
100
is a thin disc having a flare stop opening
100
c
formed at the center thereof. The flare stop
100
includes an annular peripheral wall section
100
b
formed at the outer peripheral portion thereof in a forward direction, an elastic piece
100
a
extending in the forward direction from the trisected position of the front surface of the annular peripheral wall section
100
b,
and a locking pawl
100
d
formed at the outer peripheral portion of the extreme end of the mounting piece
100
a.
The flare stop
100
is mounted in such a manner that it is engaged with the float key
80
along the inner peripheral wall
80
f
of the float key
80
from the rear side thereof so as not to interfere with the third lens barrel
60
, and the locking pawl
100
d
of the mounting piece
100
a
is elastically inserted into the rectangular engaging hole
80
e
of the float key
80
. As a result, the flare stop
100
can move in the optical-axis direction by the length of the engaging hole
80
e
rearward of the float key
80
.
The operation of the flare stop
100
in zooming and collapsing will be described with reference to
FIGS. 8A
,
8
B and
8
C. First, when respective lens groups are retracted, the flare stop
100
is in a state shown in FIG.
8
A. In the collapsed state, the flare stop
100
is abutted against the mask front side
101
a
of a main body
101
. The locking pawl
100
d
of the flare stop
100
is located at a position near to the front end of the engaging hole
80
e
of the float key
80
.
Next, when the respective lens groups are driven to a wide-angle state, the flare stop
100
is in a state shown in FIG.
8
B. In this state, the third lens barrel
60
relatively moves backward by a distance F
2
in the optical-axis direction with respect to the float key
80
while the float key
80
moves in the optical-axis direction. With this movement, the rear end surface
61
a
of a lens support frame
61
which is engaged with the third lens barrel
60
is abutted against the front end surface
100
f
of the flare stop
100
, thereby pushing out the flare stop
100
toward the rear side of the optical-axis.
Next, when the respective lens groups are zoomed up to a telephoto state, the flare stop
100
is in a state shown in FIG.
8
C. In this state, the third lens barrel
60
moves by a predetermined distance in the optical-axis direction. However, the relative positional relationship between the float key
80
and the flare stop
100
is not changed from the wide-angle state because the movement of the third lens barrel
60
does not physically affect the flare stop
100
. Then, the flare stop opening
100
c
is located at a midway position between a third lens group L
3
and the mask front side
101
a
and doe not interfere with an effective light beam OP in the telephoto state.
However, in the flare stop device of the lens barrel in Japanese Unexamined Patent Publication No. 5-188274 mentioned above, the flare stop
100
is held to the float key
80
by the elastic force of the mounting piece
100
a.
Thus, the locking pawl
100
d
of the flare stop
100
can be moved at least within the range of the engaging hole
80
e
of the float key
80
between, for example, the wide-angle state in FIG.
8
B and the telephoto state in FIG.
8
C. The flare stop
100
itself has little possibility that it moves because it is composed of a light member. However, when strong shock is applied to the main body, there is a possibility that the locking pawl
100
d
will be released from the confines of the engaging hole
80
e,
i.e., from the range in which it normally moves.
SUMMARY OF THE INVENTION
An object of the present invention, which was made to overcome the above disadvantage, is to provide a stop device which can accurately maintain the relative distance between the stop member and the frame member for supporting it and which further occupies a small space and is effective to reduce the size of the lens barrel to which the stop device is assembled.
A stop device of the present invention comprises a stop member having arm sections including convex portions at the extreme ends thereof and permitting a desired photographing light beam to pass therethrough; and a frame member having a first sliding surface on which the convex portions can slide, a second sliding surface, on which the convex portions can slide, having a step with respect to the first sliding surface and an inclined surface for continuously connecting the sliding surfaces and capable of moving in the optical-axis direction of the lens barrel about the optical-axis thereof, wherein the stop member slides on the first sliding surface when the lens barrel moves from a collapsed position to a photographing preparation position, slides and falls on the inclined surface and reaches the second sliding surface when the lens barrel moves from the photographing preparation position to a first photographing magnification position, and slides on the second sliding surface when the lens barrel moves from the first photographing magnification position to a second photographing magnification position.
Other features and advantages of the present invention will be apparent form the following description when taken in conjunction with the accompanying drawings.


REFERENCES:
patent: 5376983 (1994-12-01), Yamazaki et al.
patent: 5392160 (1995-02-01), Satoh et al.
patent: 5485315 (1996-01-01), Nomura et al.
patent: 5589987 (1996-12-01), Tanaka
patent: 5758205 (1998-05-01), Hara et al.
patent: 5966249 (1999-10-01), Aoki
patent: 6028718 (2000-02-01), Nakayama et al.
patent: 5-188274 (1993-07-01), None

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