JPH0139562B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical fiber cable used in laser processing machines, laser scalpels, and the like.

Conventional Structure and Problems Conventionally, optical fibers have been coated with plastic in order to protect them. As with optical fiber cables for optical communications, if the fiber is sufficiently thin, for example, several tens of micrometers in diameter, it can withstand bending with a radius of several millimeters. However, in optical fibers for transmitting optical power in laser processing machines, etc., the diameter of the optical fiber is required to be approximately 0.5 mm to 2 mm. in this case,
Sometimes optical fibers can break due to bending with a radius of several 100 mm. As described above, for optical fibers having a large diameter, the plastic coating is not sufficient to protect the optical fibers. Several 100mm
A high rigidity that is extremely difficult to bend is required below the fracture curvature. At the same time, it is also necessary to bend flexibly until the fracture curvature is reached.

Purpose of the Invention In view of the above points, an object of the present invention is to provide an optical fiber cable that bends flexibly up to the breaking curvature, is extremely difficult to bend below the breaking curvature, and has high rigidity. .

Structure of the Invention The present invention involves passing a plurality of short inner pipes closely to the outside of a tube into which an optical fiber has been inserted, and covering adjacent portions of the inner pipes.
Multiple outer pipes are installed in a row and fixed at the cable ends to prevent them from shifting in the longitudinal direction.
The inner and outer pipes touch each other and are prevented from bending below a certain curvature.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of the vicinity of the end of the optical fiber cable according to the present invention. 1 is the core of the optical fiber, 2 is the loose cladding of the stainless steel tube, and these constitute the optical fiber. Of course, this may also be a plastic-coated fiber. The optical fiber is housed in a flexible tube 3 made of plastic, rubber, etc., and a plurality of inner pipes 4a, 4b, 4c, 4d, . . . are closely fitted on the outside of the tube 3. These inner pipes 4a, 4b,
Inner pipe 4 so as to cover the adjacent parts of 4c,...
Outer pipes 5a, 5b, 5c... having inner diameters slightly larger than the outer diameters of pipes a, 4b, 4c... are closely fitted with play. Reference numeral 6 denotes a sleeve for fixing the fiber, which is bonded to the fiber and the inner pipe 4a. The sleeve 6 is not necessarily necessary, and the fiber may be directly bonded to the tube 3. 7 is a vinyl jacket that prevents dirt from sticking between the pipes.

FIG. 2 is a perspective view showing the state in which the inner pipe 4a and the outer pipe 5a are locked at the end of the tube 3. The claw 4x formed on the inner pipe 4a sinks into the tube 3, and the inner pipe 4a and the tube 3
A claw 5x formed on the outer pipe 5a is bent and inserted into a small hole 4y formed on the inner pipe 4a, whereby the tube 3, inner pipe 4a, and outer pipe 5a are are locked together. The other end of the tube 3 is also locked in the same way, so that the tube 3,
Inner pipes 4a, 4b, 4c..., outer pipes 5a, 5
b, 5c... are not shifted in the longitudinal direction. In this embodiment, these are fixed with nails or the like, but they may be simply glued.

When the optical fiber cable configured as described above is bent, the inner pipes 4a, 4b, 4c... and the outer pipes 5a, 5b, 5c... are bent at a certain radius of curvature, as shown in the cross-sectional view of Fig. 3. The outer surface of the inner pipe and the inner surface of the outer pipe are in contact and cannot be bent below this curvature. If the curvature at this time is made larger than the fracture surface of the optical fiber, breakage of the optical fiber can be prevented. It can be bent extremely flexibly over a bending range larger than this curvature.

This curvature is determined by the gaps between the inner pipes 4a, 4b, 4c... and the outer pipes 5a, 5b, 5c... and the lengths of these pipes. Since the vicinity of the end of an optical fiber cable is frequently subjected to repeated bending, making the pipe in this part longer and increasing the curvature will provide a safer measure against breakage of the optical fiber. It is also possible to attach a hand piece such as a condenser lens to the end face of the optical fiber cable shown in this embodiment.

Effects of the Invention As described above, according to the present invention, by providing a plurality of inner pipes and a plurality of outer pipes and locking them to the tube, bending of the optical fiber can be restricted by the abutment of both pipes. , it is possible to eliminate breakage of the optical fiber.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an optical fiber cable according to an embodiment of the present invention, FIG. 2 is a perspective view of a tube end face of the same embodiment, and FIG. 3 is a sectional view showing a state in which an inner pipe is in contact with the cable. 1, 2...Optical fiber, 3...Tube, 4
a, 4b, 4c...inner pipe, 5a, 5b, 5
c...Outer pipe.

Claims (1)

[Scope of Claims] 1. A plurality of inner pipes are closely attached to the outside of a tube in which optical fibers are installed, and a plurality of outer pipes are inserted so as to cover adjacent portions of the respective end surfaces of the plurality of inner pipes. An optical fiber cable in which pipes are closely and loosely fitted, and the outer pipe, the inner pipe, and the tube end located at the ends are locked to each other. 2. The optical fiber cable according to claim 1, wherein the length of the outer pipe or the inner pipe near the end of the optical fiber is longer than that of the central part.