JP2598522Y2 - Optical fiber detection head - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber detecting head, and more particularly, to an optical fiber detecting head for capping a detection end face of an optical fiber.

[0002]

2. Description of the Related Art A fiber-type photoelectric sensor in which light emitted from a detection end face of an optical fiber is reflected or transmitted by an object to be detected and received by an optical sensor is widely used.

FIG. 8 is an explanatory view showing the structure of an optical fiber detecting head of a conventional fiber type photoelectric sensor. In FIG. 8, reference numeral 1 denotes a cylindrical body, and the cylindrical body 1 is made of a Ni-plated brass shaft. A two-stage insertion hole 2 is formed around the center, and a step portion 1 a is formed in the insertion hole 2 on the distal end side of the cylindrical body 1. Further, two kinds of screws having different outer diameters are cut on the outer periphery of the cylindrical body 1, and the cylindrical body 1 is screwed and fixed to a mounting member. An optical fiber 3 is inserted into the insertion hole 2 of the cylindrical body 1, and an adhesive P is applied and fixed to the inner surface of the insertion hole 2. At the tip of the optical fiber 3, the polyethylene coating 3a is removed and the fiber 3c is removed.
Is exposed, and the removed end face of the covering portion 3a is connected to the stepped portion 1 of the insertion hole 2.
The optical fiber 3 is fixed to the cylindrical body 1 so as to abut on a. Then, one end of the fiber portion 3c of the optical fiber 3, that is, the detection end face 3b is polished after the adhesive P is cured and dried, so that the detection end face 3b is hardly contaminated with dust and the like, so that it is hardly contaminated.

However, in this conventional head for detecting an optical fiber, the detection end face 3b of the optical fiber 3 is polished in a number of steps, and it takes a long time.
Has been proposed. In the optical fiber detection head according to this proposal, the insertion holes 12 formed in the cylindrical body 10 are formed with the same diameter. Further, an engagement piece 21 is formed at the tip of the cylindrical body 10, and the cap 20 including the engagement piece 22 that engages with the engagement piece 21 is
It is attached to the cylinder 10 by snapping. As shown in FIG. 10, one end of the cap 20 is divided into four engagement pieces 22 in the axial direction, and an engagement protrusion 22 a is formed on the end side of each of the engagement pieces 22. This cap 20
Is engaged and fixed to the cylindrical body 10 by engaging the claw engaging projection 22a with the engaging piece 21 of the cylindrical body 10. Reference numeral 15 denotes a ring body. The ring body 15 is snap-coupled to the other end of the cylindrical body 10, so that the slit-shaped pressing piece bites into the outer peripheral surface of the coating portion 3 a of the optical fiber 3, and eventually, the cap 20. , The cylindrical body 10 and the ring body 15 are integrally fixed to the optical fiber 3. According to the optical fiber detection head according to this proposal, various detections can be performed by holding and fixing the cylindrical body 10 by the fixing means while the optical fiber 3 is cut to a predetermined length. Then, the detection end face 3b of the optical fiber 3 is covered with the transparent cap 20, so that no dust adheres to the detection end face 3b and polishing is not required.

[0005]

According to the optical fiber detecting head according to the above-mentioned proposal, polishing of the detection end face 3b of the optical fiber 3 becomes unnecessary, but there is a possibility that a problem of reflected light accompanying the cutting of the optical fiber 3 may occur. There is. FIGS. 11 to 13 are diagrams for explaining a problem in the optical fiber detection head according to the above proposal. When the optical fiber 3 is cut by the cutter K as shown in FIG. The detection end face 3b is
It is not cut perpendicular to the axis of c, but cut diagonally,
When the optical fiber 3 is attached to the cylindrical body 10, the detection end face 3b of the optical fiber 3 does not adhere to the entire inner surface of the cap 20, and as shown in FIG.
A clearance G composed of an air layer is generated between b. Such a clearance G is formed between the inner surface of the cap 20 and the detection end surface 3.
When it occurs between b and b, reflection occurs on each surface as shown in FIG. 13 and the amount of reflected light R increases, and the light coupling efficiency decreases.

The present invention has been made in view of the above-mentioned problems of the prior art, and has been made to solve the problem. An object of the present invention is to ensure that the detection end face of the optical fiber and the inner surface of the cap can be in close contact with each other, thereby improving the light coupling efficiency. It is an object of the present invention to provide an optical fiber detection head that can perform the above-described steps.

[0007]

An object of the present invention is to provide an optical fiber detection head for emitting light from a detection end face of an optical fiber and detecting an object to be detected by an optical sensor. A cylindrical body for fixing, the core wire of the optical fiber and the coating covering the core wire are cut together to form the same detection end face, and the detection end face is mounted on the cylinder, and the detection end face side of the optical fiber is attached to the detection body. and a translucent cap having a convex portion is butt set formed in the axial direction of the optical fiber to the inner surface is caused to mainly contact with the core wire, when mounting the light-transmitting cap to the cylinder during assembly, the convex parts is achieved by taking a configuration so as to close contact with the detection end face of climate fiber before by the contact with the detecting end surface.

[0008]

According to the above means, the core wire of the optical fiber and the core
Cut the covering over the lines together to make the same plane
Detection end face and the detection end of the optical fiber attached to the cylinder
Protruding on the inner surface on the surface side so that it can be displaced in the direction of the optical fiber axis
It has a protrusion that is formed and mainly abuts the core wire
And the end face of the core wire of the optical fiber
Not cut completely perpendicular to the fiber axis
At least, make sure that the core wire on the detection end
Can be through the optical fiber core through the translucent cap
Emitting and receiving light from the line can be performed without any trouble, and the light coupling efficiency
Can be improved.

[0009]

FIG. 8 illustrates an embodiment of the present invention.
13 to FIG. 13 in which the same parts as those in FIG. First, a first embodiment will be described with reference to FIGS. 1 to 6. FIG. 1 is an explanatory view showing the entire configuration of the first embodiment, and FIGS. 2A to 2C show the first embodiment. FIG. 3 is an explanatory view of a manufacturing process of a main part of the embodiment, FIG. 3 is a perspective view of an engagement portion of a ring body of the first embodiment of the present invention, FIG.
5 (a) to 5 (c) are explanatory views of a joining process of a cylindrical body and a ring body according to a first embodiment of the present invention, and FIGS. FIG. 6 is an explanatory diagram showing the effect of the first embodiment.

As shown in FIG. 1, in the first embodiment, the distal end portion of the cylindrical body 10 has a concave step portion 10n formed on the inner peripheral surface thereof and is reduced in thickness to form a caulked portion 10p. A cylindrical cap 20 having an open end at one end in the caulked portion 10p
Is formed of acrylic which is a light transmitting material, and a fiber portion 3c of the optical fiber 3 mounted on the cylindrical body 10 is provided on the inner surface of the end portion.
A protruding surface 20p having substantially the same size as that of FIG. The optical fiber 3 inserted into the cylindrical body 10 is held and fixed to the cylindrical body 10 by a ring body 15 described later with the detection end face 3b abutting on the convex surface 20p. In addition, this convex surface 2
5p, as shown in FIG. 5A, a circular projection is formed at the center of the inner surface of the cap 20, and the upper surface thereof is a flat surface. It is good also as a curved-surface shape which has a top part in a center part like above.

Here, the ring body 15 of the first embodiment will be described with reference to FIGS. 3 and 4A to 4C.
As shown in FIG. 4A, a first inclined surface 13 is formed on the inner peripheral surface on the rear end side of the cylindrical body 10 in a direction away from the axis toward the open end side. An engaging recess 10g is formed by forming a locking projection 10f on the opening end side of the first inclined surface 13. The ring body 15 is inserted into the cylindrical body 10 from the rear end side of the cylindrical body 10 through which the optical fiber 3 is inserted, and the inserted front end of the ring body 15 is divided into four pieces 15a. An engagement projection 15f is provided at the tip of the inner peripheral surface of each divided piece 15a of the ring body 15, and a second inclined surface 16 is formed on the outer periphery of each divided piece 15a of the ring body 15. A locking engagement piece 15h is formed in parallel with the divided piece 15a of the ring body 15, and the locking engagement piece 15h is formed.
A knob 15i is protruded from the outer surface of h. By pushing the knob 15i, the locking engagement piece 15h is pushed and bent in a direction approaching the axis of the optical fiber 3, as shown in FIG. FIG. 4 (c) shows a state in which the locking projection 15f is in a coupled state, and the cover 3 of the optical fiber 3 is moved by the action of the first inclined surface 13 and the second inclined surface 16.
It is fixed by biting into the outer surface of a.

In the first embodiment having such a configuration, in order to hold and fix the optical fiber 3, as shown in FIG. 2A, the end face of the cylindrical body 10 is opposed to the concave step portion 10n from the tip side. The cap 20 is inserted into the caulked portion 10p of the cylindrical body 10 until the contact position is reached, and the caulked portion 10p is caulked and deformed as shown in FIG. . On the other hand, optical fiber 3
Is cut into a predetermined length, and inserted into the ring body 15 and the cylindrical body 10 with the detection end face 3b formed by the cutting first,
The detection end surface 3b abuts on the convex surface 20p of the cap 20, and the outer surface of the distal end of the cap 20 is located inside the distal end of the caulked portion 10p .
Insert the optical fiber 3 until it hits the surface . At this position, as shown in FIG. 4A, the divided piece 15a of the ring body 15 into which the optical fiber 3 has been inserted is inserted into the cylindrical body 10 from the rear end side. Continuing with this insertion, and the second inclined surface 16 of the first inclined surface 13 and the ring member 15 of the cylindrical body 10 as shown in FIG. 4 (b) contact with each other. Then, as shown in FIG. 4 (c), the locking engagement piece 15h
Is locked with the locking projection 10f, the locking engagement piece 15h is engaged with the engagement recess 10g, and the second inclined surface 16 is pressed by the first inclined surface 13 to engage. Projection 1
5f bites into the covering portion 3a of the optical fiber 3, and the optical fiber 3 and the cylindrical body 10 are stably held and fixed. In this state, as shown in FIG. 2C, the cap 20 is positioned at a predetermined position by the caulking portion 10p, and the detection end face 3b of the optical fiber 3 comes into close contact with the convex face 20p of the cap 20. When the optical fiber 3 is detached from the cylindrical body 10 to replace the damaged optical fiber 3 or the damaged cylindrical body 10, when the knob 15 i is pushed in, the engagement between the locking engagement piece 15 h and the locking projection 10 f is performed. Since the stop is released, the optical fiber 3 and the cylindrical body 10 can be easily removed by moving the ring body 15 away from the cylindrical body 10 while pushing the knob 15i. In addition, 1 in FIG.
0r is a gap generated due to the movement of the cap 20 .

As described above, according to the first embodiment, since the convex surface 20p of the inner surface of the cap 20 is in contact with the fiber portion 3c, even if the optical fiber 3 is not completely perpendicular to the axis and is cut at an inclination, The detection end face 3c almost completely adheres to the convex face 20p. For this reason, as shown in FIG.
No clearance G of the air layer is formed between Op and the detection end face 3c, the reflected light R is greatly reduced, and the light coupling efficiency is improved. Further, according to the first embodiment, the holding and fixing of the cylindrical body 10 and the optical fiber 3 can be easily performed with one touch, and the assembling can be performed in a short time and at low work cost. Therefore, when one of the optical fiber 3 and the cylindrical body 10 is damaged and replaced, the optical fiber 3 can be easily removed from the cylindrical body 10 by pushing in the knob 15i, and only the damaged part is replaced. It is possible to realize efficient use of parts.

FIG. 7 is a diagram for explaining the second embodiment.
The second embodiment is different from the first embodiment in that an O-ring 28 made of a rubber material, which is an annular elastic body, is closely attached to the periphery of the end of the cap 20A. The O-ring 28 is attached to the annular groove 20b around the end of the cap 20A, and the cap 20A to which the O-ring 28 is attached is attached.
Are inserted into the caulked portion 10p of the cylindrical body 10 and caulked and fixed by the caulked portion 10p as in the first embodiment. The other parts of the configuration of the second embodiment are the same as those of the first embodiment already described. In the second embodiment, a force in the direction of the white arrow acts on the cap 20A due to the elastic force of the O-ring 28 elastically provided, while the force of the fiber portion 3c acts in the direction of the black arrow. Accordingly, the allowable range of insertion of the optical fiber 3 into the cylindrical body 10 is widened, the detection end face 3b is always in close contact with the convex face 20p, and the air gap G is not generated, so that the light coupling efficiency can be further improved. In addition, it is possible to completely prevent water or oil from entering the cap 20A from the outer peripheral edge of the cap 20A and adhering to the detection end face 3b of the optical fiber 3, thereby deteriorating the optical characteristics. Note that the present invention is not limited to the above embodiment, and the optical fiber 3 may be fixed to the cylindrical body 10 using, for example, an adhesive.

[0015]

According to the first aspect of the present invention, the optical fiber core wire and the coating covering the core wire are cut together to form a detection end face and the same surface, and the optical fiber is mounted on the cylindrical body,
And a translucent cap having a convex portion is butt set formed on the inner surface of the detection end face of the optical fiber in the axial direction of an optical fiber is caused to mainly contact with the core wire, when mounting the light-transmitting cap the cylindrical body during assembly, the convex portion is so as to close contact with the detection face of the optical <br/> fiber by the contact with the detecting end surface, completely perpendicular end face of the core of the optical fiber constituting the detecting end surface with the axis of the optical fiber Even if it is not cut, it can be securely brought into close contact with the protrusion at the core part of the detection end face, and light can be emitted and received from the core of the optical fiber through the translucent cap without hindrance, and the light coupling efficiency Can be improved. According to the invention described in claim 2, in addition to the effects obtained by the invention described in claim 1, the head and the optical fiber can be easily replaced, the cost can be reduced, and the light-transmitting cap is held in the cylindrical body. Since the light transmitting cap is fixed to the optical fiber via the body, the convex portion of the light transmitting cap can be securely adhered to the detection end face of the optical fiber. According to the third aspect of the present invention, since the annular elastic body is interposed between the peripheral edge of the light-transmitting cap and the cylindrical body, in addition to the effect obtained by the first aspect of the present invention, the light-transmitting cap is provided. Water and oil can be prevented from entering the optical fiber from the peripheral edge of the end of the cap, and the fiber portion and the inner surface of the light transmitting cap can be brought into close contact with each other.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an entire configuration of a first embodiment of the present invention.

FIG. 2 is an explanatory view of a step of caulking the cap according to the first embodiment of the present invention;

FIG. 3 is a perspective view of an engagement portion of the ring body according to the first embodiment of the present invention.

FIG. 4 is an explanatory view of a joining process of the cylinder and the ring according to the first embodiment of the present invention;

FIG. 5 is an explanatory view of the convex surface of the cap according to the first embodiment of the present invention;

FIG. 6 is an explanatory diagram showing the effect of the first embodiment of the present invention.

FIG. 7 is a sectional view showing a configuration of a main part of a second embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a configuration of a conventional optical fiber detection head.

FIG. 9 is an explanatory diagram showing a configuration of an optical fiber detection head according to the proposal.

FIG. 10 is a perspective view of a cap of the proposed optical fiber detection head.

FIG. 11 is an explanatory diagram of cutting an optical fiber.

FIG. 12 is an explanatory diagram of a clearance that occurs in the current state of holding and fixing the optical fiber to the cylindrical body.

FIG. 13 is an explanatory diagram of a problem caused by clearance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cylindrical body 10f Locking protrusion 10g Engaging concave part 10n Concave step part 10p Caulking part 20, 20A Cap 20p Convex surface 28 O-ring

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Showa 60-186404 (JP, U) Japanese Utility Model Showa 60-202034 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) G02B 6/00 G01V 8/16 G02B 6/04 G02B 6/10 G02B 6/42

Claims (3)

(57) [Scope of request for utility model registration] 1. An optical fiber detection head for emitting light from a detection end face of an optical fiber and detecting an object to be detected by an optical sensor, comprising: a cylindrical body for fixing the head to a device to which the head is attached; The detection end face, which is formed by cutting the core wire of the optical fiber and the coating covering the core wire together to form the same surface, and the inner surface of the optical fiber which is mounted on the cylindrical body and on the inner surface of the optical fiber on the detection end face side. to be butt set form a translucent cap having a convex portion is caused to mainly contact with the core wire, when mounting the light-transmitting cap to the cylinder upon assembly, contact the convex portion of said detection end face optical fiber sensing head is characterized in that so as to close contact with the detecting end surface of the front climate fibers by the. 2. The light-transmitting cap is attached to the detection end face side of the optical fiber of the cylindrical body, and a holding body is detachably fixed to the other end side of the cylindrical body. 2. The optical fiber detecting head according to claim 1, wherein a fixing claw is provided which engages with the cylindrical body when being mounted on the cylindrical body and is bitten into a coating of the optical fiber. 3. The head for detecting an optical fiber according to claim 1, wherein an annular elastic body is interposed between a peripheral edge of an end portion of the light transmitting cap and the cylindrical body.