JPH0243296B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber type photoelectric switch used for detecting minute objects.

Conventionally, there has been a photoelectric detection device that irradiates light from a light emitting element directly or from one end of an optical fiber onto an object to be detected, receives the reflected light from one end of the optical fiber, and transmits it to a light receiving element from the other end. Are known. (Refer to Japanese Unexamined Patent Publication No. 52-113765 and Japanese Utility Model Publication No. 52-26608.) Also, a photoelectric detection device is known that receives light emitted from an object to be detected from one end of an optical fiber and transmits it to a light receiving element from the other end. There is. (Unexamined Japanese Patent Publication No. 50-10653
However, since the coating of the optical fiber is made of a generally known synthetic resin, it has the following drawbacks.

That is, when the optical fiber is coated with a flexible synthetic resin, a means for holding the leading end of the optical fiber is required when directing the leading end toward the object to be detected.

Therefore, not only is the work of setting up the optical fiber cumbersome, but also when the object to be detected is minute,
It is extremely difficult to precisely point an optical fiber at its sensed object, and it is also extremely difficult to accommodate this if the pointing angle of the optical fiber with respect to the sensed object often needs to be changed. be.

In addition, when the optical fiber is coated with a rigid synthetic resin, frequent bending operations may cause the optical fiber to bend under conditions of use where the orientation angle of the optical fiber with respect to the object to be detected must be changed frequently. When the coating breaks, various problems arise.

Therefore, the present invention allows the leading end of the optical fiber to be easily and accurately detected by arranging the leading end of the optical fiber in a bendable metal pipe held on the case side with a gap. The object of the present invention is to provide a simple optical fiber type photoelectric switch that can be directed toward an object.

An embodiment of the present invention will be described below with reference to the drawings.

Figures 1 and 2 show a reflective photoelectric switch. In the figures, numeral 10 is a box-shaped case made of synthetic resin, etc.
0 is a case body 10 that is bonded together with adhesive or the like.
1 and a cover 102. Reference numeral 11 denotes a shield plate bent into a U-shape, 12 and 13 are light emitting and light receiving elements, 14 is an element holder, and 15 is a printed wiring board to which an operation display element 16 and the like are attached.

The element holder 14 is formed of synthetic resin or the like into a box shape with an open front end, and locking protrusions 141 formed on both sides are locked into locking holes 111 formed in the flexible plate 11. By stopping it, it is firmly attached inside the case body 101 via this flexible plate 11. Inside the element holder 14, recesses 142 and 143 for element setting are formed in two stages, upper and lower, in the front-rear direction, and a pair of upper and lower protruding walls 144, 145 formed on the rear end surface are provided with the wiring board. Support groove 146, 1 which also serves as an insertion guide of 15
47 (Fig. 3) is formed. Each of the above recesses 1
42, 143 to hold each element 12, 13 by press fit through elastic cylinders 16, 17 made of rubber, etc., and lead terminals 12a, 13 of each element 12, 13.
By brazing and fixing a to the wiring board 15, the light emitting and light receiving elements 12, 13 are integrally attached to the holder 14 together with the wiring board 15, so that they can be easily incorporated into the case body 101. I can do it. In Figure 3, 14
Reference numerals 8 and 149 are formed on the holder 14 to connect each lead terminal 12 of the light emitting and light receiving elements 12 and 13.
This is a through hole that penetrates through a and 13a.

Reference numeral 18 denotes an external lead-out cord connected to the wiring board 15, and drawn out to the outside through a hole 10a formed in the rear wall of the case 10. The cord 18 and the case 10 are made liquid-tight by a packing 19 made of rubber or the like and having a convex cross section. Annular edge portions 20 and 21 are formed in the case 10 to correspond to the large diameter and small diameter portions 191 and 192 of the rubber packing 19, and the packing 19 of these edge portions 20 and 21
The above-mentioned liquid-tight effect is improved by biting into the hole.

22 and 23 are optical fibers, and the optical fiber 2
Reference numeral 2 constitutes an optical path for transmitting the light from the light emitting element 12 to the object to be detected, and optical fiber 23 constitutes an optical path for transmitting the reflected light from the object to be detected to the light receiving element 13. 24 is a holding base for both the optical fibers 22 and 23, and 25 is a stopper. On the rear end surface of the holding base 24, a convex portion 240 is formed which fits inside the square-shaped wall 140 surrounding the element setting recesses 142, 143 of the element holder 14, as shown in FIGS. 4 to 6. Further, a fiber insertion hole 242 is formed in the annular protrusion 241 on the front end surface. The convex portion 240 of the holding base 24 has a recess 243 for resin filling that communicates with the insertion hole 242.
is formed. 247 is a positioning projection formed on the projection 240, and 150 is the element holder 14.
This is a notch that is formed in and fits into the protrusion 247.

On the upper and lower surfaces of the plug body 25, there are grooves 244 formed on the upper and lower inner walls of the resin filling recess 243,
Grooves 251 and 252 are formed corresponding to the grooves 245, respectively. One end portion 22a, 2 of each optical fiber 22, 23 is inserted into each of these grooves 251, 252, respectively.
3a, one end surface of each of the optical fibers 22 and 23 is connected to the light emitting and light receiving element 1.
2 and 13 can be easily opposed. One end portion 22a, 23 of each of the optical fibers 22, 23
When the fiber a is inserted into the grooves 251 and 252, for example, if the fiber is bent with a large curvature, such as the optical fiber 23, the corner portion will be removed as shown in FIGS. 1, 2, and 4. By forming a conical taper portion 253 in a portion of the groove 252 corresponding to the groove 252, damage to the optical fiber 23 due to bending can be prevented. Horizontal grooves 2 are provided on both sides of the plug body 25.
54,255 are formed. One end portion 22a, 23a of each of the optical fibers 22, 23 is connected to the stopper 2.
After the plug body 25 is press-fitted into the resin filling recess 243 while fitting into the upper and lower grooves 251 and 252 of the 5, the epoxy resin 26 is injected from either one 254 of the horizontal grooves 254 and 255. When the recess 243 is filled, the resin 26 solidifies and the one ends 22a, 23 of the optical fibers 22, 23 are formed.
a is integrated with the holding base 24 together with the stopper 25 and resin 26. The optical fibers 22, 2 are connected by the holder 24, the stopper 25 and the resin 26.
3 holder 27 is constituted. In this case, the other lateral groove 255 serves as an escape port for air when the resin 26 is injected, so that the flow and solidification of the resin 26 are improved.

The other end 22b of both the optical fibers 22, 23,
23b is led out forward from the hole 104 of the conical cylinder part 103 on the front wall of the case 10, and these lead-out parts 22b and 23b are inserted into a bendable metal pipe 28 made of stainless steel, copper, etc. (See Figures 7 to 9). This metal pipe 28 is connected to the other ends 22b, 23 of the optical fibers 22, 23.
It has an inner diameter such that a gap (play) 29 exists between it and b. In this embodiment, a spacer 30 is interposed in a gap 29 between the inner peripheral surface of the metal pipe 28 and the outer peripheral surface of the optical fibers 22, 23 at the other ends 22b, 23b of the optical fibers 22, 23. The other ends 22b, 23b of the optical fibers 22, 23 are fixed to the lead-out end of the metal pipe 28, as shown in FIG.

One end portion 28a of the metal pipe 28 is formed into a flattened shape that widens at the end as shown in FIGS. is attached to.

Reference numeral 31 denotes a frusto-conical rubber packing inserted into the metal pipe 28 and interposed in the conical cylinder part 103 of the case 10, and the rear end surface thereof has a semicircular cross section facing the partition wall 105 of the case 10. O of
A ring portion 310 is integrally formed. An annular protrusion 106 is formed on the inner wall of the conical cylinder portion 103 corresponding to the conical surface of the rubber packing 31 .

In the above configuration, prior to the detection operation of the object to be detected, the metal pipe 28 is bent appropriately and set so that the other end surfaces of the optical fibers 22 and 23 are accurately oriented toward the object to be detected. In this state, when the light emitting and light receiving elements 12 and 13 are driven, the light from the light emitting element 12 passes through the optical fiber 22 and is irradiated onto the object to be detected. The reflected light from the object to be detected passes through the optical fiber 23 to the light receiving element 1.
The presence or absence of the object to be detected can be detected depending on whether or not light is received by the object.

As is clear from the above configuration, the optical fiber 2
2 and 23 are made of a bendable metal pipe 28, and one end 28 of this metal pipe 28
a is fixed to the holder 27, and a gap 29 is provided over almost the entire length between the inner peripheral surface of the metal pipe 28 and the outer peripheral surface of the optical fibers 22, 23, so that the optical fibers 22, 23 are connected to the metal The metal pipe 28 is inserted into the pipe 28 at the lead-out ends 22b, 23b of the optical fibers 22, 23.
A spacer 30 such as an auxiliary pipe or resin is interposed in the gap 29 between the inner peripheral surface of the optical fibers 22 and the outer peripheral surface of the optical fibers 22 and 23, and the ends 22b and 23b of the optical fibers 22 and 23 are connected to the metal pipes. It is characterized in that it is fixed to the lead-out end of 28.

In this way, a gap 29 is provided between the inner circumferential surface of the metal pipe 28 and the outer circumferential surface of the optical fibers 22, 23, and a spacer 30 is interposed at the end of the metal pipe 28, so that the optical fibers 22, 23 Since the other ends 22b and 23b are fixed, when the metal pipe 28 is bent in the direction of the object to be detected, the bending direction of the metal pipe 28 coincides with the light emission direction or light input direction. The detection range can be easily set.

That is, as disclosed in Japanese Patent Laid-Open No. 55-64202, in a configuration in which the ends of the optical fibers 22 and 23 are not fixed, the direction of the end faces of the optical fibers 22 and 23 is changed by bending the metal pipe 28. Since the bending direction of the metal pipe 28 does not match the emission direction or the incident direction of the light, it is very difficult to set the detection range.

Furthermore, the other end 2 of the optical fibers 22, 23
Since the optical fibers 2b and 23b are fixed to the inner circumferential surface of the metal pipe 28 via the spacer 30, even if the metal pipe 28 is bent frequently, the other ends of the optical fibers 22 and 23 will remain in the metal pipe. This optical fiber 22,
If the tips of the optical fibers 23 hit another object and break, or the tips of the optical fibers 22 and 23 sink into the metal pipe 28, forming a gap between the metal pipe 28 and the optical fibers 22 and 23. It is possible to effectively prevent dust and the like from entering the recess.

Further, in the above embodiment, a reflective photoelectric switch using light emitting and light receiving elements 12 and 13 was explained as an example, but any photoelectric switch having at least one of the elements can be applied. It is.

As described above, the present invention allows the lead-out end of the optical fiber led out to the outside to be loosely fitted into the bendable metal pipe supported by the case or the holder. The end face can be accurately and easily directed to the object to be detected without using a dedicated holding means, and
This has the effect of effectively preventing metal pipes from breaking.

[Brief explanation of the drawing]

1 and 2 are a cross-sectional view and an exploded perspective view showing an example of an optical fiber photoelectric switch according to the present invention, FIG. 3 is a perspective view showing an element holder and a wiring board, and FIG. 4 is an optical fiber holder. Figure 5 is a cross-sectional view of the optical fiber holder holding the optical fiber, Figure 6 is a rear view of the holder, and Figure 7 is a partially broken side view showing an example of a metal pipe. 8 is a rear view of the same metal pipe, and FIG. 9 is an enlarged sectional view of a packing portion corresponding to the metal pipe. 10... Case, 12... Light emitting element, 13...
Light receiving element, 22, 23... Optical fiber, 22a,
23a...One end of each of the optical fibers 22 and 23, 2
2b, 23b...Each lead-out end of the optical fibers 22, 23, 27...Optical fiber holder, 28...Metal pipe, 28a...One end of the metal pipe 28, 2
9...Gap, 30...Spacer.

Claims (1)

[Claims] 1 A case containing at least one of the light emitting and light receiving elements, holding one end of an optical fiber whose other end is guided outside and whose outer periphery is coated with a coating material, and a An optical fiber type photoelectric switch is provided with an optical fiber holder positioned so that one end face faces the above-mentioned element, and performs at least one of emitting light and receiving light from the other end face of the optical fiber, wherein the covering material of the optical fiber is the above-mentioned case. The optical fiber is made of a metal pipe that can be bent on the outside, and a gap is provided over almost the entire length between the inner circumferential surface of the metal pipe and the outer circumferential surface of the optical fiber, and the optical fiber is inserted into the metal pipe. The end of the optical fiber is fixed to the lead-out end of the metal pipe by interposing a spacer in the gap between the inner peripheral surface of the metal pipe and the outer peripheral surface of the optical fiber at the lead-out end of the fiber. Fiber optic photoelectric switch.