JPH0350481Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to an optical fiber case used in a terminal optical device of an optical fiber type photoelectric switch, and more specifically, the tip of the optical fiber is used for light input or light output. Concerning a case for attaching a lens.

(b) Prior art In the optical fiber type photoelectric switch mentioned above, the conventional general configuration for attaching a lens to the optical fiber is as shown in Fig. 1, in which a glass lens 2 is installed at the tip of a metal case 1. The optical fiber 3 is inserted from the other end, the relative positions of the glass lens 2 and the optical fiber 3 are determined by a spacer 4, and the case 1 and the optical fiber 3 are fixed with adhesive.

(c) Problems to be solved by the invention However, according to the above-mentioned conventional technology, the metal case 1 and the glass lens 2 are more expensive than the same type of plastic case, and the number of component parts is four. This resulted in an increase in the number of parts and the assembly process, resulting in an overall high cost.

In addition, since the fixing method uses adhesive as described above, the adhesive strength (fixing strength) is unstable and the assembly process becomes complicated (if a two-component epoxy adhesive is used, measuring → mixing → stirring → coating steps are required), which further increases costs.

Furthermore, if the optical fiber 3 and the lens 2 are bonded together, the degree of freedom in attaching the case housing the optical fiber and the photoelectric switch circuit will be reduced.

For example, if the case containing the photoelectric switch circuit is already installed in the equipment and the length of the optical fiber is too long, it is possible to shorten the optical fiber (as opposed to plastic optical fiber). (Cutting tools that can be used to cut freely with a knife or the like have been devised); however, if the optical fiber and lens are bonded together, this cutting will cause a decrease in the detection distance.

The object of this invention is to provide an optical fiber case that can connect an optical fiber and a lens at low cost, firmly fixes the two, and allows a high degree of freedom in attaching the tip of the optical fiber.

(d) Means for solving the problem This invention is a plastic case that has a lens section at one end and a fiber insertion hole at the other end, and the case wall of this case has the above-mentioned and other components. An opening is cut out from the end toward the lens part, and a tightening part consisting of a pair of wings is formed across the opening, and on the upper and lower surfaces of the case wall around the fiber insertion hole, This is an optical fiber case for an optical fiber type photoelectric switch, in which a plurality of slits each having an approximately semicircular range are opened with adjacent slits shifted approximately half a circumference from each other, and locking protrusions are provided on the inner wall of the case facing these slits. It is characterized by

(E) Function The optical fiber case of the optical fiber type photoelectric switch of this invention is made by inserting the optical fiber into the fiber insertion hole of the case, bringing the tip end into contact with the back side of the lens part, and connecting the optical fiber with the pair of fibers. The diameter of the case is reduced by tightening the fastening portion made of wing pieces with a screw or the like, and the locking protrusion on the inner wall of the case bites into the optical fiber coating to fix it.

(f) Effects of the invention According to this invention, the case is a flexible resin product that integrally has a fiber insertion hole and a lens part, and all the components associated with the optical system are incorporated into a single case. As a result, the number of parts and assembly man-hours can be reduced, leading to significant cost reductions.

In addition, since the connection with the optical fiber does not rely on adhesive, the connection strength is stable, and since the optical fiber and the glass part are not bonded, when it is necessary to cut the optical fiber as mentioned above, it is possible to The fiber can be removed from the case, so the degree of freedom in attaching the tip of the optical fiber is extremely high.

Furthermore, since a tightening part consisting of a pair of blades that reduces the inner diameter of the case is provided, after the optical fiber is inserted into the fiber insertion hole, by reducing the inner diameter of the case, the upper and lower surfaces of the inner wall of the case can be alternately At this position, the locking protrusion bites into the optical fiber coating, allowing a strong connection between the optical fiber and the case.

Furthermore, since the lens portion is integrally provided with the case, the optical fiber and the lens portion can be easily and automatically positioned by simply inserting the optical fiber into the fiber insertion hole.

Furthermore, since the above-mentioned locking projection is provided on the inner wall of the case on the surface facing the slit, it is easy to make the molded projection higher and firm fixation is possible.

(G) Embodiment of the invention Hereinafter, an embodiment of the invention will be explained using the drawings of FIGS. 2 to 4.

The case 5 shown in FIGS. 2 to 4 is a plastic molded product, and a lens portion 6 is formed at one end.
The other end has a fiber insertion hole 7 leading to this lens portion 6.
is bored, and the innermost end of the fiber insertion hole 7 reaches the lens surface. In addition, an opening 8 is formed in the case 5 from the other end to the middle part of the fiber insertion hole 7, and a pair of upper and lower wings 9, 9 are protruded from the case wall 10, sandwiching this opening 8. At the same time, screw holes 11 are provided in these wing pieces 9, 9 to face each other. In addition, a plurality of slits 1 are provided on the upper and lower surfaces of the case wall 10 at regular intervals in the longitudinal direction of the case.
2..., 13... are each established in a substantially semicircular range. In this case, as shown in FIG. 3, the upper and lower slits 12 and 13 are provided so as to be shifted from each other in the longitudinal direction of the case, and the inner wall 14 of the case has locking protrusions 15 facing each of the slits 12 and 13. ... is similarly formed over a substantially semicircular range. Note that the optical fiber contact surface 16 at the innermost part of the fiber insertion hole 7 is slightly recessed toward the lens portion 6 side.

In this case 5, the optical fiber 3 is pushed into the fiber insertion hole 7, and the fiber tip is brought into contact with and engaged with the above-mentioned fiber contact surface 16, so that the relative relationship between the optical fiber 3 and the lens portion 6 is Positioning is done automatically. Next, screws 17 (shown in FIG. 2) are passed through the screw holes 11 of the blades 9, 9 and tightened with nuts, so that the diameter of the case 5 is reduced, and as the diameter is reduced, the optical fiber 3 is At the same time as being tightened, each locking protrusion 15 bites into the fiber sheath 3a of the optical fiber 3 and acts on its own, thereby firmly connecting the case 5 and the optical fiber 3. The above-mentioned slits 12 and 13 are provided so that the elastic diameter reduction operation of the case 5 can be easily performed. In addition, since the tip of the optical fiber 3 enters the recessed fiber contact surface 16, the slit 1
Disturbing light that enters through 3 cannot enter between the fiber tip and the fiber abutting surface 16, so even if the slits 12 and 13 are provided, the influence of the ambient light can be eliminated.

As is clear from the above explanation, this invention has successfully achieved its initial objective.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a terminal optical device as a conventional example, and FIG. 2 is an exploded view showing an embodiment of this invention.
FIG. 3 is a cross-sectional view, and FIG. 4 is a cross-sectional view of the state in which the case and the optical fiber are connected. 5... Case, 6... Lens portion, 7... Fiber insertion hole, 8... Opening, 9... Wing piece, 10...
Case wall, 12, 13... slit, 15... locking protrusion.

Claims (1)

[Scope of Claim for Utility Model Registration] A flexible resin case with a lens part provided at one end and a fiber insertion hole provided at the other end, the case wall of the case having a lens part side closer to the other end than the other end. An opening is cut out toward the opening, and a tightening part consisting of a pair of blades is formed between the opening, and a substantially semicircular area is formed on the upper and lower surfaces of the case wall around the fiber insertion hole. An optical fiber case for an optical fiber type photoelectric switch, wherein a plurality of slits are formed with adjacent slits shifted approximately half a circumference from each other, and locking protrusions are provided on the inner wall of the case facing the slits.