JP2585129Y2 - Fiber unit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type fiber unit, such as an optical fiber type photoelectric switch, which detects the presence or absence or size of an object by light.

[0002]

2. Description of the Related Art Conventionally, the structure of a sensor head of a reflection type fiber unit of an optical fiber type photoelectric switch has a diameter of the optical fiber when one optical fiber for projection and one optical fiber for light reception having the same diameter are used. A hole having a radius slightly larger than the radius is made on the center axis of the end face of the sensor head on the object side, and after inserting the optical fiber, the light emitting optical fiber and the light receiving optical fiber are fixed with an adhesive. Drill a hole in the shape of two circles whose diameter is slightly larger than the diameter of the optical fiber to be inserted, connect them with a tangent line, insert the optical fiber, and then use the adhesive to project the optical fiber for transmission and the optical fiber for reception. There was something to fix.

[0003]

However, in the case of a sensor head manufactured by a conventional technique using an adhesive, the sensor head is left for a long time in a high-temperature and high-humidity condition, for example, at 60 ° C. and 95% RH. In other words, a phenomenon in which the photoelectric switch always responds even when there is no object, that is, a phenomenon of light leakage may appear and cause a problem.

[0004] When investigating the cause, the adhesive swells at the end face of the sensor head on the object side in a high-temperature and high-humidity atmosphere of 60 ° C and 95% RH, and the swell of the adhesive causes light leaking to the adjacent optical fiber. Thus, it was found that the photoelectric switch was responding as if there was an object at all times.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies and have arrived at the present invention. That is, the present invention provides a sensor head,
In the reflection type fiber unit including the light emitting optical fiber and the light receiving optical fiber, at least the object side end of the sensor head has a plurality of independent holes through which the light emitting optical fiber and the light receiving optical fiber pass. Hole depth 5
mm or less, and at least on the object side end face of the sensor head, an optical fiber for light emission and an optical fiber for light reception are fixed to the sensor head by an adhesive, and the depth of the hole is An optical fiber unit having a length of 1 mm to 4 mm, wherein the plurality of holes are made of parts separated from the sensor head main body, and are coupled when the fiber unit is manufactured.

[0006] The plurality of holes may be integral with the sensor head body, or may be made of parts separated from the sensor head body.
It may be combined at the time of manufacturing the fiber unit. When two single-core optical fiber cords are used, the sensor head can be manufactured by integrating the plurality of holes, but when a two-core optical fiber cord is used, two optical fiber cords are integrated. Therefore, it is difficult to pass the optical fiber through the two holes at the same time. Therefore, it is best to use a sensor head in which the plurality of holes are made of parts separated from the sensor head body. The fiber cord can be easily manufactured by passing the tip of the two-core optical fiber cord through the head main body, covering the above separated parts and inserting. Even in the case of an optical fiber cord having three or more cores, it is effective to use a sensor head having a plurality of holes separated from the sensor head body.

The material of the sensor head is not particularly limited, but metals such as brass, stainless steel, aluminum alloy, iron,
BT, nylon, POM, PC, modified PPO, PSF,
Heat-resistant plastics such as polyarylate, PPS, PP, ABS, and PTFE can be used. Preferably, the inner diameter of the hole is larger than the outer diameter of the optical fiber by 0.02-0.2 mm. If it is smaller than 0.02 mm, it is substantially difficult to insert the fiber. If it is larger than 0.2 mm, the adhesive contained therein may seep out and cause a problem.

[0008] The depth of the hole is 5 mm or less. If it is larger than 5 mm, under the condition of high temperature and high humidity, the effect of the difference in the thermal behavior between the optical fiber and the adhesive or the material of the sensor head comes out, and the phenomenon that the optical fiber protrudes from the end face of the head occurs. Sometimes a problem. The smaller the depth is, the more the holding strength can be maintained mechanically. The minimum value differs depending on the material of the sensor head, but it is usually preferably 0.2 mm or more. More preferably, 1
mm to 4 mm.

The number of the plurality of holes is, for example, two in the case of one light emitting optical fiber and one light receiving optical fiber. In the case of two light emitting optical fibers and two light receiving optical fibers, the number is four independently. Alternatively, there may be one large hole for light reception at the center and a plurality of small independent holes for light projection surrounding the large hole for light reception. The combination of the number of holes is not limited to this.

Although the material of the optical fiber is not particularly limited, a plastic optical fiber whose core is made of a material such as polymethyl methacrylate, polystyrene, or polycarbonate is often used. The diameter of the fiber is not particularly limited.
25mmφ, 0.5mmφ, 0.75mmφ, 1.0m
Fibers such as mφ are often used.

[0011]

The present invention will be described in more detail with reference to the following examples.

[0012]

Embodiment 1 A sensor head is made of brass and has a tip part having two holes with a diameter of 1.05 mm, a depth of 2 mm, and a center-to-center distance of 1.2 mm, which are symmetrical with respect to the center axis of the object side end face. A sensor head component consisting of a sensor head body having a hole of 2.3 mm in diameter was prepared. First, a covering material at one end of a two-core plastic optical fiber cord (TC1000W manufactured by Asahi Kasei Corporation) having a diameter of 1.0 mm and coated with polyethylene to an outer diameter of 2.2 mm is applied to the sensor head body for 15 m.
Insert each stripped plastic optical fiber for light transmission and light reception, fill with epoxy adhesive, then insert the plastic optical fiber into the two holes of the tip parts, and then use epoxy adhesive. A fiber unit having a total length of 2 m fixed by the above was manufactured. The end face of the sensor head was polished to 3 μm, and the end face on the opposite side was cut with a razor. (FIG. 1, two-hole type) The detection distance and the amount of change in the appearance of the end face were measured immediately after the production and left for 200 hours in an atmosphere of 60 ° C. and 95% RH. Table 1 shows the measurement results.

For the measurement of the detection distance, OMRON E3XR-CE4T (power supply voltage 12 V) was used for the amplifier unit, and 30 mm × 30 mm white paper was used for the detection object. As the detection distance, the sensitivity of the amplifier unit was maximized and the fiber unit was gradually separated from the detection object, and the distance from the point at which the signal of the amplifier unit turned on to off or from off to on was read. The appearance of the end face is
The swelling amount of the adhesive was mainly observed with an optical microscope having a magnification of 30 times.

After 200 hours, there is no change in the end face of the head, and the detection distance has not changed.

[0015]

EXAMPLE 2 Next, two holes having a diameter of 1.05 mm, a depth of 4 mm, and a center-to-center distance of 1.2 mm were formed in a brass material symmetrically with respect to the center axis of the end surface on the object side. 1.0m diameter coated with polyethylene to 2.2mm outside diameter
m plastic optical fiber cord (TC10 manufactured by Asahi Kasei Corporation)
Each of the plastic optical fibers for light emission and light reception, each having 15 mm of the coating material on one end of (00) peeled off, was inserted into the sensor head, and was filled with an epoxy adhesive and fixed to a total length of 2 m.
Was manufactured. Sensor head end face is 3
After polishing by μm, the opposite end face was cut with a razor. (Fig. 2, 2-hole type) Immediately after production and at 60 ° C, 95% R
The detection distance and the amount of change in the appearance of the end face were measured for those left for 200 hours in an atmosphere of H. Table 2 shows the measurement results.

After 200 hours, there is no change in the end face of the head, and the detection distance has not changed.

[0017]

Embodiment 3 The sensor head was made of brass and was made symmetrically with respect to the center axis of the end surface on the object side by making four holes with a diameter of 0.60 mm, a depth of 3 mm and a center-to-center distance of 0.7 mm.
A plastic optical fiber cord having a diameter of 0.5 mm covered with polyethylene and having an outer diameter of 1.0 mm, and two plastic optical fibers obtained by stripping off a coating material at one end of the cord by about 15 mm were used as light emitting and receiving fibers. Every other four holes were inserted into four holes of the sensor head, and a fiber unit having a total length of 2 m fixed by filling with an epoxy adhesive was manufactured. The end face of the sensor head is polished to 3 μm,
The opposite end face was cut with a razor. (FIG. 2, 4-hole type) The detection distance and the amount of change in the appearance of the end face were measured immediately after the production and after leaving for 200 hours in an atmosphere of 60 ° C. and 95% RH. Table 3 shows the measurement results.

After 200 hours, there is no change in the end face of the head, and the detection distance has not changed.

[0019]

Comparative Example 1 The sensor head was made of brass and was formed with a hole having a diameter of 2.3 mm and a depth of 4 mm on the center axis of the end face on the object side. A plastic optical fiber cord of 1.0 mm in diameter coated with polyethylene and having an outer diameter of 2.2 mm was peeled off by about 15 mm at one end, and one plastic optical fiber for light transmission and one for light reception was used as a sensor head. A fiber unit with a total length of 2 m, which was inserted and filled with an epoxy adhesive, was fixed. The end face of the sensor head was polished to 3 μm, and the end face on the opposite side was cut with a razor.
(FIG. 3, 1-hole type) The detection distance and the amount of change in the external appearance of the end face were measured immediately after fabrication and after leaving for 200 hours in an atmosphere of 60 ° C. and 95% RH. Table 4 shows the measurement results.

After 200 hours, the swelling amount of the adhesive is
With 0.15 mm, the amplifier unit always responded and the detection distance could not be measured.

[0021]

Example 4 and Comparative Example 2 A test was performed on the same sensor head as in Example 1 except that the depth of the hole was changed variously. The sensor head is made of brass and has a diameter of 1.05 mm and a center-to-center distance of 1.2 mm symmetrically with the center axis of the object-side end surface.
Drill two holes and make the depth of the hole 1 mm, 2 mm,
Examples 4-1 to 4-5 of 3 mm, 4 mm, and 5 mm and Comparative Examples 2-1 and 2-2 of 7 mm and 10 mm were prepared and prepared. The following processing was performed on each of these to produce a sensor head. That is, a plastic optical fiber for light transmission and light reception, in which a coating material at one end of a plastic optical fiber cord having a diameter of 1.0 mm coated with polyethylene and having an outer diameter of 2.2 mm is stripped off by 15 mm, is inserted into the sensor head. Then, a fiber unit having a total length of 2 m, which was filled with an epoxy adhesive and fixed, was manufactured. Sensor head end face is 3 μm
And the opposite end face was cut with a razor.
(FIG. 2, 2-hole type) The detection distance and the amount of change in the protrusion of the optical fiber in the appearance of the end face were measured immediately after the production and left for 200 hours in an atmosphere of 60 ° C. and 95% RH.
Table 5 shows the measurement results.

After 200 hours, the depth of the hole is 1 mm, 2 mm
Examples 4-1 to 4-5 of mm, 3 mm, 4 mm, and 5 mm
Has little protrusion of the end face of the head,
Comparative examples 2-1 and 2-2 having a hole depth of 7 mm and 10 mm
In this case, the optical fiber protrudes from the end face of the head.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

[0028]

According to the present invention, a highly reliable fiber unit having good dimensional stability of a sensor head even under high temperature and high humidity, no light leakage, and high reliability can be provided.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fiber unit of the present invention, (a): an example of a tip part split type (b);

FIG. 2 shows an example of the fiber unit of the present invention (a); a sensor head integrated type, a two-hole example (b);

FIG. 3 shows a comparative example; a conventional fiber unit example (a); an example in which the sensor head is integrated and the optical fiber has one through hole (front); and (b); Hole example (front)

FIG. 4 is a schematic diagram of a detection distance measuring system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber cord 2 Optical fiber 3 Sensor head 4 Object-side part of a part-split type 5 Example of conventional sensor head 6 Example of conventional sensor head 7 Fiber unit 8 Amplifier unit 9 Detected object

Claims (3)

(57) [Scope of request for utility model registration] In a reflection type fiber unit comprising a sensor head, a light projecting optical fiber and a light receiving optical fiber, at least an object side end of the sensor head is a light projecting optical fiber.
Through the fiber and the receiving optical fiber.
Number of holes, the depth of the holes is 5 mm or less, and
At least on the end face of the sensor head on the object side.
The light emitting optical fiber and the light receiving optical fiber are
An optical fiber unit fixed to a cable. 2. The fiber unit according to claim 1, wherein the depth of the hole is 1 mm to 4 mm. 3. The fiber unit according to claim 1, wherein the plurality of holes are made of parts separated from the sensor head body, and are connected when the fiber unit is manufactured.