JPH0112743Y2 - - 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. This invention relates to a photoelectric switch that can be firmly held with a simple structure.

This type of photoelectric switch has been implemented in some areas in recent years, but in order to improve transmission efficiency when assembling it, the optical axis of the light emitting/receiving element must be aligned with the optical axis of the optical fiber. It won't happen.

The conventional optical coupling means mechanically fixes and attaches a dedicated plug to the optical fiber, and then inserts it into the mating receptacle, thereby optically coupling the two. Since a special plug is required for this method, if the length of the optical fiber is changed depending on the purpose or installation method, the plug must be reattached each time. It cannot be used by cutting the length with a knife etc.
There was a problem with poor operability.

Naturally, various structures for holding optical fibers have been proposed, but all of these structures are complicated, making the installation process troublesome and having problems with their holding power. However, there were many problems such as high costs.

This idea was created in view of these problems, and it allows for easy positioning and connection of the optical axes of the light emitting/receiving element and the optical fiber without using a special plug, and has a simple structure with excellent holding power. The object of the present invention is to provide an optical fiber type photoelectric switch with excellent operability.

This idea solves the above problems,
A cap consisting of a through hole having a diameter smaller than the outer diameter of the optical fiber in the center of the front surface and a plurality of slits formed on the outer periphery is press-fitted onto the outer periphery of the light emitting/receiving element, and the light emitting/receiving element is A semicircular groove is formed at one end of the detection head to which the detection head is attached, and a stationary block piece with a protrusion is provided in this groove, while a similar groove is provided opposite to this block piece. The optical fiber is also provided with a holding plate provided with a protrusion, and the optical fiber is clamped and fixed between the fixed side block piece and the groove of the holding plate.

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 drawing out a power supply and output line is drawn out from the rear end of the case element 1. Also case 1
A detection head 6 is attached to the front end of the detector, and a light emitting element 8 and a light receiving element 9 are attached to the detection head 6 via a printed circuit board 7, respectively. Reference numeral 10 indicates a cap that is press-fitted and attached to the outer periphery of the above-mentioned emitter and light-receiving elements 8 and 9;
In particular, as shown in an enlarged view in FIG. 3, a plurality of slits 10a (four in the drawing) are formed along the longitudinal direction of the outer circumference and the front surface of the cap 10, and at the center of the front surface of the cap 10. A through hole 10b having a diameter smaller than the outer diameter of the optical fiber is formed so as to coincide with the optical axis of the optical fiber, which will be described later, and a claw piece 10c is formed between the slits 10a.

Further, a stationary 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 formed at appropriate intervals on the bottom surface of this groove 11a.

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. There is.

The photoelectric switch according to this invention is constructed as described above. Next, an example of its assembly will be described. The cap 10 is press-fitted and the optical fiber 14 is pushed into it. 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 be able to enter even if it is pushed in from the front. 10a is formed, 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 decreases rapidly.
If the push is continued with a constant force, the tip of the optical fiber 14 will be pushed in until it hits the tip of the light emitting element 8 (the same applies to the light receiving element 9), and will stop there.

In other words, because the pushing force changes rapidly,
You will feel a "click action" and it will be pushed in correctly until it makes contact with the light projecting element 8. At this time, the tip of the optical fiber 14 and the light emitting element 8
It is natural that the light coupling efficiency is low when the side edges of the two sides are not in close contact with each other.

Once the optical fiber 14 is pushed in, the four claws 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 claws 10c
The tip of c becomes a resistance and becomes difficult to pull out.
This serves as a temporary fix.

Incidentally, 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 must be aligned with the optical axis of the optical fiber 14 in advance. In addition, since the optical fiber 14 is held in a tight fit structure as described above, centering (optical axis alignment) can be automatically performed by simply pushing the optical fiber 14.

However, by pushing the optical fiber 14 into the cap 10 as described above, the optical fiber 14
Although it is possible to temporarily fix and align the optical axis, this alone does not provide sufficient tensile strength and can only be held temporarily.

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, while inserting the optical fiber 14 into the groove 11a of the stationary block piece 11,
is inserted into the groove 12 in the same manner, and then the screw 15 is screwed into the screw hole 13 and the optical fiber 14 is clamped and fixed between them. Therefore, according to the above structure, the optical fiber 14 is tightened in a somewhat wavy state, so that its holding force is extremely strong. It should be noted that if the optical fiber 14 is bent extremely, its transmission efficiency will be reduced, but such a bend has no optical effect.

Furthermore, the arrangement positions and shapes of the protrusions formed on the stationary block piece and the holding plate are not limited to those in the above embodiment, and for example, as shown in FIG. It goes without saying that the protrusions 11b and 12b may be disposed opposite each other at the same location, or may be formed in the shape of a threaded groove as shown in FIG. 5B.

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 can be performed.

Therefore, sufficient optical coupling is possible even if the optical fiber used is cut with a jig such as a knife, and it can be easily coupled without using a dedicated plug as in the past, making it easy to operate. Furthermore, the length of the optical fiber can be used for various purposes.
Since it can be cut freely depending on the mounting method and the like and can be used as is, it is possible to provide a so-called free-cut type photoelectric switch.

In addition, along with the pushing operation of the optical fiber,
As mentioned above, because of the click action effect,
Since the pushing limit position can be detected by feel, reliable optical coupling is possible.

Furthermore, in the photoelectric switch of the present invention, a semicircular groove is formed at one end of the detection head, and
A stationary block piece is provided with a protrusion in this groove, while a similar groove is provided opposite to this block piece, and a holding plate is provided with a protrusion to hold the optical fiber between them. Therefore, the holding structure is extremely simple, and the entire optical fiber is subjected to external force, and the protrusion in the groove is wedged into the outer sheath of the optical fiber. , has sufficient tensile strength and excellent holding power.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of the photoelectric switch according to this invention, Fig. 2 is a perspective view showing the same exploded state, Fig. 3 is an enlarged exploded perspective view showing the optical coupling part, and Fig. 4 is an enlarged sectional view of the same. , FIGS. 5A and 5B are enlarged sectional views showing other embodiments of the optical fiber holding structure in the switch of the present invention. 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, 10c...Claw piece, 11...Fixed side block piece, 11a...Groove,
11b...protrusion, 12...pressing plate, 12a...
Groove, 12b...protrusion, 14...optical fiber.

Claims (1)

[Claims for Utility Model Registration] (1) In a photoelectric switch that has a built-in light emitting/receiving element and is equipped with an optical fiber, the optical fiber is press-fitted onto the outer periphery of the light emitting/receiving element, and the optical fiber is fitted in the center of the front surface. A cap is formed with a through hole having a diameter smaller than the outer diameter and a plurality of slits formed on the outer periphery, and is attached to one end of a detection head to which the above-mentioned light emitting/receiving element is attached. a fixed-side block piece having a groove formed therein and a protrusion provided in the groove; and a fixed-side block piece disposed opposite to the fixed-side block piece, and provided with the same groove and protrusion as the fixed-side block piece. An optical fiber type photoelectric switch is provided with a holding plate, and the optical fiber is clamped and fixed between the groove of the fixed side block piece and the holding plate. (2) The optical fiber according to claim 1 of the utility model registration claim, characterized in that the projections provided on the holding plate are provided alternately with the projections provided on the stationary block piece. Photoelectric switch.