JPH0310481Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention relates to a terminal optical device for a reflective photoelectric switch using an optical fiber, and more specifically, the invention relates to a terminal optical device for a reflective photoelectric switch using an optical fiber. The present invention relates to a terminal optical device.

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

(c) Problems to be solved by the invention However, according to the above configuration, the metal case 1,
The glass lens 2 is more expensive than one made of the same type of plastic, and since there are four components, the number of parts and the number of assembly steps increase, resulting in an overall high cost.

Further, in the optical fiber 3, the fiber coating 3
If a and the core 3b were eccentric, the optical coupling between the optical fiber 3 and the lens 2 would be insufficient, which could lead to a decrease in detection ability.

Therefore, as shown in FIGS. 2 and 3, the lens portion 5
A plastic case 6 integrally formed has been proposed.

In this case, a fiber insertion hole 7 coaxial with the lens portion 5 is provided in the case 6, and the optical fiber 3 is inserted into the hole 7 and fixed with an adhesive 8.
Although this reduces the total number of parts used compared to the one shown in FIG. 1, the problem caused by the eccentricity of the optical fiber described above remains unresolved.

Furthermore, since the coating material for plastic fibers currently on the market is polyethylene, which has low adhesive strength, the polyethylene and the case 6 made of other plastic materials are bonded with adhesive 8, but in the case of FIG. By pulling the optical fiber 3, a situation arises in which it is easily pulled out of the case 6.

In order to avoid this, the fiber coating 3a is peeled off at the tip of the optical fiber 3 as shown in Fig. 3, and the core 3b (acrylic) and the case 6 (polycarbonate acrylic, etc.) are directly bonded. Although the strength can be expected to be improved, the position of the core 3b is not fixed due to the amount of force applied when inserting the optical fiber 3, and the optical coupling efficiency between the lens portion 5 and the core portion 3b is affected as well as the eccentricity described above. may be damaged.

In addition, when connecting the optical fiber 3 to the case 6 with the adhesive 8 as shown in Figs. 2 and 3, if the adhesive is used too little, the adhesive strength will decrease, and if it is added too much, the optical fiber insertion pressure will cause the fiber insertion and insertion. The adhesive 8 overflows from the hole 7 and solidifies outside, resulting in an unsightly appearance and a decrease in commercial value.

This idea allows for strong adhesion between the two optical fibers and the holder in an optical fiber type reflective photoelectric switch, but also prevents loss of optical coupling efficiency between the optical fibers and the lens section. To provide a terminal optical device having high commercial value and capable of automatically positioning both without fiber leakage.

(d) Means for solving the problem This invention consists of a fiber insertion hole, a plastic fiber terminal case integrally provided with a coaxial lens part, and two optical fibers. The diameter of the inner end of the fiber insertion hole is tapered toward the lens part, and a light shielding plate is buried in the lens part to a position that also partitions the lens part and the inside of the lens part, and each of the above-mentioned A predetermined amount of each core at the end of the optical fiber is exposed, and the tip of each exposed core is inserted into the tapered hole into which adhesive is injected, and is also inserted into a position defined by the inner end of the light shielding plate. The present invention is characterized in that it is a terminal optical device of an optical fiber type reflective photoelectric switch fixed with adhesive.

(E) Function According to the terminal optical device of the optical fiber type reflective photoelectric switch of this invention, the tip of each exposed core of two optical fibers inserted using the tapered fiber insertion hole as a guide. The parts are fixed to the lens part with an adhesive at appropriate positions while being partitioned by light shielding plates.

(f) Effects of the invention According to this invention, each core at the end of the two optical fibers is exposed and these cores and the holder are directly fixed with adhesive, so it can be made as strong as the one in Figure 3. Good adhesion can be obtained.

Furthermore, due to the presence of the light shielding plate, the light from the light emitting core does not leak to the light receiving core, and at the same time, it is possible to secure the proper position of each exposed core, and to ensure that the light from the light emitting side core does not leak to the light receiving side core. The optical coupling between the two optical fibers of the reflective photoelectric switch and the lens portion is maintained properly, and the optical coupling between the two optical fibers of the reflective photoelectric switch and the lens portion is not affected by the amount of force applied when inserting the optical fibers or the eccentricity of the fiber coating and core. Optical coupling efficiency can be maintained high.

Furthermore, in the conventional cases shown in Figures 2 and 3, the lens part beyond the inner part of the fiber insertion hole suddenly becomes thicker, so molding sink distortion occurs, but inside the fiber insertion hole. By tapering the diameter of the rear end, the wall thickness on the lens portion side can be gradually increased, thereby reducing molding sink distortion and producing a high-quality case with a glass portion.

In addition, if a recess is provided around the entrance of the optical fiber insertion hole, even if a large amount of adhesive is used, the excess adhesive that overflows from the fiber insertion hole when the optical fiber is inserted will be removed. The product value increases because it flows into the recess at the entrance of the hole and accumulates, and does not flow into the outside of the unplanted plant and solidify as in the past.

(g) Example of the invention An example of the invention will be described below in detail based on FIG. 4.

FIG. 4 shows a terminal optical device of an optical fiber type reflective photoelectric switch, in which the case 9a is a plastic molded product integrally provided with a fiber insertion hole 10a and a coaxial lens portion 11a, and a fiber insertion hole 10a is integrally formed with the case 9a. The inner tip of the fitting hole 10a is the lens portion 11a.
The diameter of the hole is tapered toward the end and then reduced to a small diameter to form a tapered hole portion 12a coaxial with the lens portion 11a.

The innermost diameter of this tapered hole 12a is formed to a diameter through which the cores 3b, 3b of the two optical fibers 3, 3 are inserted.
In order to prevent the light from the optical fibers 3, 3 of the book from being mixed, a light shielding plate 14 is embedded to a position that also partitions the lens portion 11a and the inside of the lens portion 11a.

In addition, although the taper hole part 12a has a shape in which the diameter is reduced in two stages in the drawing, it is not particularly limited to this shape.

Furthermore, a concave portion 13a is provided around the entrance of the fiber insertion hole 10a.

On the other hand, in the case of the optical fibers 3, 3, a predetermined amount of the fiber coating 3a at the tip of each fiber is peeled off to expose the core 3b, and the adhesive 8 is injected into the tapered hole 12a of the case 9a. The fibers 3, 3 are inserted into the fiber insertion hole 10a.
With this insertion, the exposed cores 3b, 3b are each guided by the tapered surface and plunge into the tapered hole 12a,
Each of them is positioned at a position in contact with a lens portion 11a defined by the inner end of the light shielding plate 14.

At the same time, the adhesive 8 in the tapered hole 12a flows between the optical fibers 3, 3 and the fiber insertion hole 10a due to the insertion pressure, and the optical fibers 3, 3 are adhesively fixed to the case 9a. .

This adhesion also applies to the exposed cores 3b, 3b.
Since it includes a part that is directly bonded to the case 9a, it is firmly attached. Further, the excess of the adhesive 8 overflowing from the fiber insertion hole 10a flows into the recessed portion 13a and solidifies in this portion, so that it is not exposed to the outside in the form of a build-up.

In this invention, it is desirable that the case 9a be made of a material that transmits only infrared light (for example, Iupilon L774 manufactured by Mitsubishi Gas Chemical).

In other words, unless a filter is installed on the case or the tip of the optical fiber as a countermeasure against disturbance light, visible light (lamp light) etc. will directly enter the light receiving element, and even in the case of a modulated light method, the visible light of the lamp etc. Malfunctions occur because the light receiving element becomes saturated with the light beam.

However, if the case 9a is made of a material that transmits only infrared light, the visible light region can be cut out without using the above-mentioned filter, and by using an infrared light emitting element, light reception based on disturbance light in the visible light region is possible. This eliminates malfunctions due to element saturation, and makes it possible to construct a photoelectric switch that is resistant to ambient light.

FIG. 5 is a graph showing the light transmission characteristics of Iupilon L774, in which A shows the wavelength range of light transmitted through the holder, and B shows the wavelength range of the light projecting element.

[Brief explanation of drawings]

1 to 3 are cross-sectional views showing various examples of conventional terminal optical devices, FIG. 4 is a cross-sectional view of a terminal optical device showing an embodiment of this invention, and FIG. 5 is a cross-sectional view showing various examples of terminal optical devices as conventional examples. 3 is a graph showing the light transmission characteristics of an example of a material that 3... Optical fiber having coating 3a and core 3b, 8... Adhesive, 9a... Case, 10a...
Fiber insertion hole, 11a...Lens portion, 12a...
... Tapered hole portion, 13a ... Recessed portion, 14 ... Light shielding plate.

Claims (1)

[Scope of Claim for Utility Model Registration] Consisting of a fiber insertion hole, a plastic fiber terminal case integrally provided with a coaxial lens part, and two optical fibers, the inner part of the fiber insertion hole The diameter of the tip is tapered toward the lens part, and a light shielding plate is buried in the lens part to a position that also partitions the lens part and the inside of the lens part, and each core of each optical fiber end part A predetermined amount of the exposed core is exposed, and the tip of each of the exposed cores is inserted into the taper hole into which the adhesive is injected, and is also inserted into the position defined by the inner end of the light shielding plate, and the adhesively fixed light beam is inserted. Terminal optical device for fiber reflective photoelectric switch.