JP2779316B2 - Inspection method for uneven thickness of colored layer of colored optical fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The method for inspecting the thickness of a colored layer of a colored optical fiber according to the present invention can be used to inspect the thickness of a colored layer formed on the outer periphery of an optical fiber.

[0002]

2. Description of the Related Art A primary coating layer (buffer layer) is formed on the outer periphery of a clad.
Is provided, and a secondary coating layer (external protective layer) is provided on the outer periphery of the optical fiber (hereinafter simply referred to as an optical fiber).
Is formed (coated) with a colored layer having a thickness of about several to several tens of μm. This is a procedure for allowing individual optical fibers to be identified by color in a cable or the like in which a large number of optical fibers are used, and there are various types of colors of the coloring layers. By the way, the coloring layer is formed by coating the optical fiber A with the coloring agent B as shown in FIG.
A colorant B is applied to the outer periphery by passing through a die C containing the colorant, and thereafter, the optical fiber A coated with the colorant B is irradiated with ultraviolet rays from an ultraviolet lamp, or a heater D is applied.
Then, the colorant B is dried and cured to form the colorant B, and then the outer diameter of the colored optical fiber F is inspected by the outer diameter measuring device E.

In the colored optical fiber F manufactured as described above, it is necessary to inspect whether or not the colored layer G has an uneven thickness. Was performed by observing the cross section. For example, when the optical fiber A is located at the center of the colored layer G as shown in FIG. 5A, it is determined that the optical fiber A is normal (non-defective) without uneven thickness, and as shown in FIG. Even if the eccentricity is slightly eccentric from the center of the colored layer G, it is judged as a good product, and FIG.
(C) As shown in FIG.
If it was exposed from, it was judged to be defective.

[0004]

However, the above-mentioned inspection method can inspect the uneven thickness state of the end face of the colored optical fiber F, but cannot inspect the section other than the cross section or the end face. Thus, the uneven thickness state of the colored layer G could not be inspected. For this reason, a complete inspection cannot be performed, and there is a possibility that a defective product may be produced. In addition, there is also a problem that it takes time since the inspection is performed manually.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for inspecting the thickness of a colored layer of a colored optical fiber capable of inspecting the thickness of the colored layer over the entire length without cutting the optical fiber. Is to eliminate.

[0006]

As shown in FIG. 1, the method for inspecting the thickness deviation of a colored layer of a colored optical fiber according to the present invention is the same as that of FIG. In the uneven thickness inspection method of inspecting the uneven thickness of the colored layer 2,
Light is irradiated toward the optical fiber 3 from two or more sides of the colored optical fiber 3, and of these lights, light passing outside the colored optical fiber 3 and reflected by the optical fiber 1 are reflected by the optical fiber 1 . Light passing through the outside sandwiches the optical fiber 3
In this method, the light is received by the light receivers 5 arranged so as to face the light irradiating means, and the uneven thickness of the colored layer 2 is inspected based on the difference in the amount of light detected by each light receiver 5. is there.

[0007]

According to the method for inspecting the thickness of a colored layer of a colored optical fiber according to the present invention, if there is no unevenness in the thickness of the colored layer 2, the light applied to the colored optical fiber 3 is removed from the light ( The light passing through the outside of the colored optical fiber 3) is directly incident on the photodetector 5, but the thickness of the colored layer 2 is deviated and the optical fiber 1 inside is exposed to the outside from the colored layer 2 or close to it. In this state, light originally blocked by the colored optical fiber 3 is transmitted by the inner transparent optical fiber 1 as shown in FIG.
The reflected light passes through the outside of the optical fiber 1 and the reflected light also enters the light receiver 5. In the case where the colored layer 2 has uneven thickness in this way, a thin portion due to the uneven thickness or more light is observed by the amount of light reflected by the optical fiber exposed portion. Alternatively, the amount of received light is greater than when there is no optical fiber exposed portion. Therefore, the optical fiber 3 is irradiated with light from two or more different positions outside the colored optical fiber 3 and the light is paired with the light irradiating means with the optical fiber 3 interposed therebetween.
In the present invention in which the light is received by two or more light receivers 5 arranged so as to face each other, the uneven thickness of the colored layer 2 can be detected from the difference between the received light amounts. In this case, it is possible to detect uneven thickness over the entire length by irradiating light while running the colored optical fiber 3.

[0008]

Embodiment 1 FIG. 1 shows an embodiment of a method for inspecting the thickness of a colored layer of a colored optical fiber according to the present invention, which is shown in FIG.
The two light sources 4 are arranged at a 90-degree angle with the fiber 3 interposed therebetween at a position where the colored optical fiber 3 below the outer diameter measuring device E shown in FIG. The light receivers 5 are respectively arranged on the sides facing each other with the light interposed therebetween so that the colored optical fiber 3 to be colored can be irradiated with light.

In this embodiment, an optical fiber 1 having a diameter of 400 μm is passed through a die C of a coloring agent B shown in FIG. 4 and drawn downward at a speed of about 200 m / min. The colored layer 2 of the colored optical fiber 3 was unevenly displaced little by little while being colored while the colored layer 2 was coated. The two light sources 4 irradiate light vertically toward the colored optical fiber 3, and each of the light sources 4 is separated by two light receivers 5 arranged on opposite sides of the optical fiber 3. The difference in the amount of light received was measured. The received light amount was read as a voltage value from a voltmeter connected to the light receiver 5. As a result, a graph of the correlation between the amount of movement of the dice C and the amount of received light as shown in FIG. 3 was obtained.

In this graph, when the amount of movement of the dice C increases, the difference between the amounts of light received by the two light receivers 5 increases. In particular, when the amount of movement of the dice C exceeds 14 μm, the inner optical fiber 1 is colored. When the layer 2 was partially exposed, the difference became remarkably large. The reason why the optical fiber 1 is not exposed from the colored layer 2 having a thickness of 8 μm when the movement amount of the die C exceeds 8 μm is that the movement amount of the die C and the uneven thickness amount of the colored layer 2 are not directly proportional. That's why.

As described above, the thickness deviation of the colored layer 2 of the colored optical fiber 3 can be inspected from the difference in the amount of light received by the light receiver 5 of the light irradiated on the colored optical fiber 3.

The light source 4 emits white light, and the light from the light source 4 has a light beam width of 30 μm by a slit plate (not shown) having a slit of 30 μm width formed on a plate of 2 mm thickness. Is squeezed. The amount of light emitted from each light source 4 is matched with high accuracy.

In the above embodiment, when the optical fiber 1 is exposed (or in a state close to it) near a shown in FIG. 1, the inspection accuracy is reduced because light is not irradiated to the portion a. 2, three light sources 4 are used, the light sources 4 are arranged at intervals of 120 degrees, and the light receivers 5 are arranged on the opposite sides of each light source 4 with the colored optical fiber 3 interposed therebetween. By irradiating the entire circumference of the optical fiber 3 with light, the uneven thickness can be detected regardless of the direction of the uneven thickness.

[0014]

According to the method for inspecting the thickness deviation of the colored layer of the colored optical fiber of the present invention, the light reflected by the optical fiber 1 and passing outside the fiber 1 is also used. It is possible to inspect the presence or absence of uneven thickness of the colored layer 2 even without it, and it is possible to continuously perform inspection while drawing, so that no time is required for inspection and defective products (defective parts) are reliably detected. can do. In addition, it is possible to inspect the colored layer 2 for unevenness in the thickness of the colored layer 2 without converting the light applied to the colored optical fiber 3 into an electric signal or performing complicated calculations.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a method for inspecting unevenness in thickness of a colored layer of a colored optical fiber according to the present invention.

FIG. 2 is a schematic view showing another embodiment of the method for inspecting the thickness deviation of a colored layer of a colored optical fiber according to the present invention.

FIG. 3 is an explanatory diagram showing a correlation between the amount of movement of a dice and the difference in the amount of received light in the method for inspecting the thickness of a colored layer of a colored optical fiber according to the present invention.

FIG. 4 is a schematic view showing a method for forming a colored layer on an optical fiber.

FIGS. 5A to 5C are explanatory diagrams showing examples of uneven thickness of a colored optical fiber.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Colored layer 3 Colored optical fiber 5 Receiver

Claims (1)

(57) [Claims] 1. A colored layer (2) on the outer periphery of an optical fiber (1).
In the uneven thickness inspection method for inspecting the uneven thickness of the colored layer (2) of the colored optical fiber (3) formed by forming the optical fiber (3), the optical fiber (3) can be seen from two or more sides of the colored optical fiber (3). And the light passing through the outside of the colored optical fiber (3) and the light reflected by the optical fiber (1) and passing through the outside of the optical fiber (1) are colored light.
The light is received by a light receiver (5) arranged so as to face the light irradiation means with the fiber (3) interposed therebetween . A method for inspecting the thickness of a colored layer of a colored optical fiber, the method comprising inspecting the thickness deviation.