Surgery – Endoscope – Having flexible tube structure
Reexamination Certificate
1999-09-17
2001-10-16
Mulcahy, John (Department: 3739)
Surgery
Endoscope
Having flexible tube structure
Reexamination Certificate
active
06302841
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a bendable tube of an endoscope, which bendable tube is constituted by linearly arranging a plurality of joint rings and pivotally connecting adjacent ones of them by means of shaft pins.
In an insertion section of an endoscope, a bendable tube is provided between a resilient tube and a distal portion. The bendable tube is forcibly bent by a pulling operation performed on the proximal-end side by means of manipulation wire elements. In an ordinary bendable tube, a plurality of joint rings are linearly arranged in the longitudinal direction of the insertion section of the endoscope and, with ear portions of adjacent joint rings overlapped, the overlapped ear portions are pivotally connected by means of shaft pins (see Jpn. U.M. Appln. KOKAI Publication No. 60-187702).
FIGS. 9 and 10
show the structure of a conventional bendable tube. As is shown in
FIG. 9
, a bendable tube
50
is constituted such that a plurality of joint rings
51
are linearly arranged in the longitudinal direction of an insertion section and, with mutually opposed ear portions
52
and
53
of adjacent joint rings
51
overlapped, rivet-like shaft pins
56
are passed through insertion holes
54
and
55
formed in the ear portions
52
and
53
. One end of each shaft pin
56
is caulked on one of opposed ear portions,
52
. Thus, adjacent joint rings
51
are pivotally connected.
Needless to say, the width of each ear portion
52
,
53
should be as small as possible in order to reduce the diameter of the bendable tube
50
and to reduce as much as possible the distance of that portion of the pivotal connection section, which projects toward the center of the inner cavity of the bendable tube
50
. However, since the insertion holes
54
and
55
for insertion of the shaft pins
56
need to be provided and the mechanical strength for caulking has to be maintained, it is necessary that the ear portions
52
,
53
have certain widths.
In an example shown in
FIG. 10
, the width of the ear portion
52
located inside is made different from that of the ear portion
53
located outside in order to achieve reduction in diameter of the bendable tube
50
while maintaining maximum widths of the ear portions
52
and
53
and to reduce as much as possible the distance of projection of the ear portion
52
,
53
toward the center of the inner cavity of the bendable tube
50
. The width of the ear portion
53
located outside is made less than that of the ear portion
52
located inside, and the insertion holes
54
and
55
are modified stepwise accordingly.
In this case, however, when the joint rings are pivotally connected, the ear portions of the adjacent joint rings of the bendable tube are overlapped, the rivet-type shaft pin is passed through the insertion holes of the overlapped ear portions, and one end of the shaft pin is caulked on one of the overlapped ear portions. Accordingly, the insertion holes need to be formed in both the overlapped ear portions and each insertion hole needs to be formed to have a certain size. Furthermore, the width of the ear portion needs to be determined in accordance with the size of the insertion hole. Although the width of the outside ear portion should preferably be made less than that of the inside ear portion, the reduction in width of the outside ear portion is limited. In the prior art, it is difficult to further reduce the width of the ear portion and to make the location of the structure of the pivotal connection closer to the inner surface of the cavity in the bendable tube.
In the conventional structure, unless a certain thickness is maintained for both the ear portions for pivotally connecting the adjacent joint rings, coupling strength cannot be ensured. This, too, is a factor which prevents the location of the structure of the pivotal connection section from being made closer to the inner surface of the cavity in the bendable tube.
Moreover, in the conventional structure, since the rivet-like shaft pin for connecting both the overlapped ear portions is fixed by caulking, the strength of retention of the shaft pin is relatively low. In order to ensure strength for preventing removal, there is a need to increase the diameter of the insertion hole for pivotal connection and the diameter of the shaft pin. Consequently, it is required to increase the width of the ear portion and the diameter of the shaft pin. Accordingly, the entire pivotal connection section becomes larger and this prevents the location of the structure of the pivotal connection section from being made closer to the inner surface of the cavity in the bendable tube.
Besides, since the shaft pin is of the rivet type and requires fixation by caulking, the assembling process therefor is time-consuming.
The above problems are common to all endoscopes. In the case of an endoscope with a small-diameter insertion section, however, the width and thickness of the ear portion are smaller and these problems become more serious.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a bendable tube of an endoscope, wherein a structural part of a pivotal connection section for connecting adjacent joint rings is reduced in size and the strength of connection is increased, and the structural part of the pivotal connection section can be situated closer to an inner surface of an inner cavity in the bendable tube, whereby the diameter of the bendable tube can be reduced.
In order to achieve the object, in a bendable tube of an endoscope according to the present invention, a plurality of joint rings each having a rotational axis perpendicular to a direction of bending of an insertion section of the endoscope are arranged in a longitudinal direction of the insertion section, and adjacent ones of the joint rings are rotatably connected by means of shaft members. Each shaft member comprises a small-diameter portion and a large-diameter portion. A rotary shaft hole, which has a diameter equal to or slightly greater than a diameter of the small-diameter portion, is formed in one of the adjacent joint rings which are rotatably connected. An end face of the small-diameter portion of the shaft member is fitted in the rotary shaft hole and fixed to the other joint ring by integral connection means.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 5178129 (1993-01-01), Chikama et al.
patent: 60-187702 (1985-12-01), None
patent: 3-37031A (1989-02-01), None
Hatori Tsuruo
Tsujiya Hideki
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Mulcahy John
Olympus Optical Co,. Ltd.
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