Endoscopic optical fiber bundle

Details Endoscopic optical fiber bundle Endoscopic optical fiber bundle

2000-01-27

2001-05-01

Palmer, Phan T. H. (Department: 2874)

Optical waveguides

Optical fiber bundle

Imaging

C385S115000, C606S015000, C600S182000

Reexamination Certificate

active

06226432

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an endoscopic optical fiber bundle comprising a bundle of optical fibers passed through the insertion portion of an endoscope.
If an endoscopic optical fiber bundle is simply passed as such through the insertion portion of an endoscope (i.e., without any protective sheath), the fibers will get stuck in various areas and break. To deal with this problem, the bundle is sheathed in a flexible tube except in a socket at the end portion.
However, typically in the curved portion of an endoscope that is bent in various directions by remote control, the optical fiber bundle is frequently bent in unspecified directions with small radii of curvature; the resulting strong cyclic flexural stress causes the sheath tube to tear at the boundary with the socket and the sheathed optical fibers may often bend to failure.
An idea to cope with this difficulty is to reinforce the flexible sheath tube over the optical fiber bundle by surrounding it with a helical tube of metal strip at least in the area within the curved portion of an endoscope.
FIG. 6
shows an end and the nearby portion of an endoscopic optical fiber bundle that adopts the above-stated idea. End portions of many optical fibers
91
in bundle are secured into a tubular socket
92
.
The optical fibers
91
in bundle are sheathed in a flexible tube
93
an end of which is tightly bound onto the socket
92
which, in turn, is surrounded with a helical tube
94
. An end of the helical tube
94
is inserted into a tube
95
tightly bound to the socket
92
and the inserted helical tube
94
is securely joined to the tube
95
.
The problem with the endoscopic optical fiber bundle shown in
FIG. 6
is that as it is bent repeatedly during the use of the endoscope, the fixed tube
95
is rubbed intensely by the tip of the helical tube
94
and may sometimes tear (in area A).
Then, the intense cyclic flexural stress is concentrated at the boundary (area B) between the sheath tube
93
and the socket
92
until the former tears in that area, causing failure of the optical fibers
91
.
SUMMARY OF THE INVENTION
An object, therefore, of the invention is to provide a durable endoscopic optical fiber bundle in which a helical tube installed around a sheath tube is positively secured to a socket to ensure that the optical fibers will not bend to failure during repeated use of the endoscope.
To attain the above-noted object, the present invention provides an arrangement for securing coupling a helical tube to a socket. The helical tube surrounding a sheath tube is securely coupled to the socket, so even if the curved portion of an endoscope is repeatedly bent, the helical tube remains securely coupled to the socket so that the helical tube bears the greater part of the strong cyclic flexural stress. Hence, the sheath tube will not tear at the boundary with the socket and none of the optical fibers will bend to failure.
An endoscopic optical fiber bundle according to an embodiment has a bundle of optical fibers passed through the insertion portion of an endoscope. At least one end portion of the bundle is secured within a tubular socket and sheathed in a flexible sheath tube fixed at an end to the socket. At least a part of the sheath tube is surrounded with a helical tube made up of a metal strip that is spirally wound in a specified diameter. Cutouts are formed near an end portion of the helical tube, and the area with the cutouts is placed over the socket. A string-like member is passed through the cutouts to be wound onto the outer surface of the helical tube so that the socket is tightly bound to the helical tube. If desired, the string-like member may be wound to pass through grooves formed in the outer peripheral surface of said socket.
An endoscopic optical fiber bundle according to another embodiment has a bundle of optical fibers passed through the insertion portion of an endoscope. At least one end portion of the bundle is secured within a tubular socket and sheathed in a flexible sheath tube fixed at an end to the socket. At least a part of the sheath tube is surrounded with a helical tube made up of a metal strip that is spirally wound in a specified diameter. The socket has a flange portion against which an end of the helical tube is allowed to abut, and the helical tube is fused to the socket in the abutting area. If desired, the fusion may be achieved by laser welding.
In either type of endoscopic optical fiber bundle, the helical tube may constructed of spaced turns of the strip, and the individual spaces between the adjacent turns may be filled with a flexible adhesive. If desired, the helical tube may at least be positioned in the curved portion of an endoscope.
The present disclosure relates to the subject matter contained in Japanese patent application No. Hei. 11-18169 (filed on Jan. 27, 1999), which is expressly incorporated herein by reference in its entirety.


REFERENCES:
patent: 4784464 (1988-11-01), Ouchi
patent: 5073048 (1991-12-01), Adachi et al.
patent: 5812719 (1998-09-01), Barry et al.
patent: 10111463 (1998-04-01), None

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