JPS6324599Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an optical fiber type photoelectric switch that has a built-in light emitting/receiving element and is equipped with an optical fiber. It concerns a photoelectric switch.

This type of photoelectric switch has been put into practice in some places in recent years, but when assembling it, the optical axis of the light emitting/receiving element must be aligned with the optical axis of the optical fiber in order to improve the transmission efficiency. .

Conventionally, the optical coupling means was to mechanically fix and attach a dedicated plug to the optical fiber, and then insert it into the mating receptacle, thereby optically coupling the two. A special plug is required for this purpose, so if the length of the optical fiber is changed depending on the application or installation method, the plug must be reattached each time. There was a problem that the length could not be cut with a knife or the like, and the operability was poor.

This idea was created in view of these problems, and aims to improve operability by easily positioning and connecting the optical axis of the light emitting/receiving element and the optical fiber without using a special plug. The purpose is to

In order to achieve the above objectives, this invention forms a through hole having a diameter smaller than the outer diameter of the optical fiber at the center of the front surface on the outer periphery of the light emitting/receiving element, and also forms a plurality of slits on the outer periphery. It is characterized by a press-fitted cap.

Embodiments of the present invention will be described in detail below with reference to the drawings.

What is shown in FIG. 1 is a cross-sectional view of an optical fiber type photoelectric switch. 1 is a case, and inside this case 1 is housed a printed circuit board 3 on which various electronic circuits 2 are mounted. A cord 4 for connecting a power source and an output line is led out from the rear end of the case 1.

Further, a detection head 6 is attached to the front end of the case 1, and a printed circuit board 7 is attached to this, and a light projecting element 8 and a light receiving element 9 are mounted on this printed circuit board 7, respectively. 10
3 shows a cap that is press-fitted and attached to the outer periphery of the light emitting/receiving elements 8 and 9. As shown in an enlarged view in FIG. Slit 10a
(four in the drawing), and a through hole 10b is formed in the center of the front surface of the cap 10 so as to coincide with the optical axis of the optical fiber, which will be described later, and to have a diameter smaller than the outer diameter of the optical fiber. Furthermore, claw pieces 10c are formed between each of the slits 10a.

Further, a fixed side block piece 11 is integrally formed on the back surface of the detection head 6, and a semicircular groove 11a having a diameter of φ/2 of the optical fiber is provided on the bottom surface of this block piece 11. and protrusions 11b are provided at appropriate intervals on the bottom surface of this groove 11a.
is provided.

Reference numeral 12 denotes a holding plate which is paired with the stationary block piece 11 and clamps and fixes the optical fiber, and the bottom surface of this holding plate 12 also has the φ/φ of the optical fiber as described above.
A semicircular groove 12a having a diameter of 2 is provided, and protrusions 12b are also provided in this groove 12a, and these protrusions 12b are arranged alternately with the protrusions 11b. 13 is a screw hole provided in the holding plate 12 and the fixed block piece 11, and 14 is a plastic optical fiber cord for transmitting and receiving light (hereinafter referred to as an optical fiber), which is composed of a jacket 14a and an optical fiber 14b. .

The photoelectric switch according to this invention is constructed as described above, and an example of its assembly will now be described. At the same time, the optical fiber 1 is press-fitted into this.
Push in 4. However, since the through hole 10b in the center of the cap 10 is formed smaller than the outer diameter of the optical fiber 14, the optical fiber 14 should not enter even if it is pushed in from the front. Since the slit 10a is provided, if the force applied to the optical fiber 14 is increased, the outer periphery of the cap 10 will bend, the diameter of the hole 10b will become larger, and the optical fiber 14 will enter the through hole 10b. Once the optical fiber 14 enters the through hole 10b, the resistance of the hole 10b of the cap 10 decreases rapidly, so if you keep pressing with a constant force, the optical fiber 1
The tip of 4 is pushed in until it hits the tip of the light emitting element 8 (the same applies to the light receiving element 9) and stops there. That is, since there is a sudden change in the pushing force, you will feel a "click action" and it will be pushed in correctly until it comes into contact with the light emitting element 8. At this time, it is natural that the light coupling efficiency will be low if the tip of the optical fiber 14 and the tip of the light projecting element 8 are not in close contact with each other.

Once the optical fiber 14 is pushed in, the four claw pieces 10c of the cap 10 bite into the outer sheath 14a of the optical fiber 14 like a kind of tight fit, and when the optical fiber 14 is pulled out, the four claw pieces 10c
The tip of 4c acts as a resistance, making it difficult to pull out, and serves as a temporary fix.

By the way, in order to increase the light coupling efficiency, it is necessary to align the optical axes of the light projecting element 8 and the optical fiber 14, but the optical axis of the through hole 10b of the cap 10 is aligned with the optical axis of the optical fiber 14 in advance. Since they are formed to match and the optical fiber 14 is held in a tight fitting structure as described above, centering (optical axis alignment) can be automatically performed by simply pushing the optical fiber 14. .

By pushing the optical fiber 14 into the cap 10 as described above, the optical fiber 14 is inserted into the cap 10.
Although the fixing and optical axis alignment of step 4 can be done to some extent, the tensile strength is not sufficient by this alone.
The holding power is only temporary.

Therefore, for full-scale fixing of the optical fiber 14, the optical fiber 14 is fixed between the fixing side block piece 11 and the holding plate 12.
This is done by clamping it between the two and tightening it with a screw.

That is, the cap 10 is
Insert the optical fiber 14 temporarily fixed into the groove 11a of the stationary block piece 11, cover the holding plate 12 and insert it into the groove 12a in the same way, and screw the screw 15 into the screw hole 13 to tighten the optical fiber 14.
is clamped and fixed between the two. Therefore, since the optical fiber 14 is tightened in a somewhat undulating state, the holding force of the optical fiber 14 is further increased.

It should be noted that if the optical fiber 14 is bent extremely, the light transmission efficiency will be reduced, but bending to this extent has no optical effect.

As described above, the photoelectric switch according to this invention has a through hole formed at the center of the front surface on the outer periphery of the light emitting/receiving element and having a diameter smaller than the outer diameter of the optical fiber, and a plurality of slits are provided on the outer periphery. Since the cap is press-fitted with the cap, by pushing the optical fiber into the cap, the optical axis can be automatically aligned and optical coupling becomes possible.

Therefore, sufficient optical coupling is possible even if the optical fiber used is simply cut with a jig such as a knife, and it can be easily coupled without using a dedicated plug as in the past. Therefore, it has excellent operability, and furthermore, the length of the optical fiber can be freely cut according to the application, installation method, etc., and can be used as is, so it is possible to provide a so-called free-cut photoelectric switch. .

In addition, along with the pushing operation of the optical fiber,
As mentioned above, because of the click action, you can feel the limit position of pushing.
Reliable optical coupling is possible, and since the optical fibers are fixed using temporary fixing means and full-scale fixing means as described above, the optical coupling becomes extremely strong. have

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of the photoelectric switch according to this invention, Fig. 2 is an exploded perspective view of the photoelectric switch, Fig. 3 is an enlarged exploded perspective view showing the main parts of the switch of the present invention, and Fig. 4 is the connecting portion thereof. FIG. DESCRIPTION OF SYMBOLS 1... Case, 3... Printed circuit board, 6... Detection head, 7... Printed circuit board, 8... Light emitting element, 9... Light receiving element, 10... Cap, 10a
...Slit, 10b...Through hole, 10b...Claw piece, 14...Optical fiber.

Claims (1)

[Scope of utility model registration request] In a photoelectric switch having a built-in light emitting/receiving element and an optical fiber, a through hole having a diameter smaller than the outer diameter of the optical fiber is formed at the center of the front surface on the outer periphery of the light emitting/receiving element; An optical fiber type photoelectric switch characterized in that a cap formed with a plurality of slits is press-fitted.