JP2012002719A - Auxiliary amplifier of leaked light detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auxiliary amplifier to assist a leaked light detector for improving sensitivity of light leaking from an optical fiber.SOLUTION: An auxiliary amplifier 1 is arranged upstream of a leaked light detector 30 which detects leaked light by bending an optical fiber. Convexoconcave portions 12a-12c, 17a-17c, which bend an optical fiber 20, are formed between a pressing member 5 and a fixing member 16 and the ratio of a curvature radius R of the convexoconcave portions to a caliber d of the optical fiber is 2.77-0.33.

Description

  The present invention relates to an auxiliary amplifier for assisting a leaked light detection device for detecting leaked light from an optical fiber in order to perform live line determination or core line contrast of the optical fiber.

When a curved portion exists in an optical fiber, it is known that a part of the light propagating through the optical fiber leaks to the outside through the curved portion. Therefore, the leaked light detection device detects the leaked light.
As an example of this leakage light detection device, there is one disclosed in Japanese Patent Application Laid-Open No. 2002-257676, and a plan cross section of the leakage light detection device 30 is shown in FIG.

  The fiber insertion portion 54 to which the optical fiber core wire is attached is provided with a fixed clip 51 and a movable clip 52 that sandwich the core wire. The fixed clip 51 has a pair of minute concave portions 61 and 62, and the movable clip 52 has a pair of minute convex portions 63 and 64. The concave portions 61 and 62 and the convex portions 63 and 64 are formed. This deforms the core wire into a small waveform (microbending). The leaked light is detected by the light receiving sensors 54 and 55 provided below the recesses 61 and 62.

When the leakage light is detected by the leakage light detection device, when the material of the primary coating layer is an ultraviolet curable resin and the material of the secondary coating layer is a nylon resin, from the optical fiber generated in the curved portion, Leaked light easily passes through the primary coating layer and the secondary coating layer and exits to the outside, and the detection sensitivity at the curved portion of the optical fiber core wire is relatively sufficient.
However, it has been found that when the material of the primary coating layer is silicone resin and the material of the secondary coating layer is nylon resin, the detection sensitivity at the curved portion of the optical fiber core wire is not good.
Therefore, in Japanese Patent Application Laid-Open No. 2001-159580, leakage light detection is provided that includes first leakage forming means and second bending formation means, and includes leakage light detection means for detecting leakage light from the second bending portion. An apparatus is disclosed.

JP 2002-257676 A JP 2001-159580 A

However, as described above, even if the first curve forming means is provided and detected, the sensitivity level is low and the presence or absence of a live line state may be erroneously determined. Therefore, the inventor conducted various experiments and found that the cause is that the radius of curvature of the optical fiber in the first bending means is large, and the insertion loss increases due to the bending structure.
Therefore, the inventor provides an auxiliary amplifier capable of improving the sensitivity level related to the radius of curvature of the optical fiber.

The invention of claim 1 of the present application is an auxiliary amplifier disposed on the upstream side of a leaked light detection device for detecting leaked light by bending an optical fiber, wherein the optical fiber is bent between a pressing member and a fixing member. An uneven bent portion is formed, and the ratio of the radius of curvature of the uneven portion to the aperture of the optical fiber is set to 2.77 to 0.33.
The leakage sensitivity of the optical fiber in the auxiliary amplifier can improve the detection sensitivity by setting the ratio between the radius of curvature of the concavo-convex portion and the diameter of the optical fiber to 2.77 to 0.33.

The invention according to claim 2 improves the detection sensitivity of leaked light in the leaked light detection device by forming two bent portions of the optical fiber between the pressing member and the fixing member.
In the invention of claim 3, the amount of leakage light can be adjusted to the optical fiber disposed between the pressing member and the fixing member via the screw body, and the detection sensitivity can be improved.

  The invention of claim 4 includes a lock mechanism that attaches a spring to the end portion of the fixed guide bar to the reciprocating pressing member and fixes the pressing member, so that the optical fiber is narrowed under the same conditions. Measurement can be performed while wearing, and detection sensitivity can be improved in a stable state.

  By disposing the auxiliary amplifier of the present application on the upstream side of the leakage light detection device, the leakage light detection device can detect leakage light with high sensitivity.

It is a figure before setting an optical fiber with the plane sectional view of an auxiliary amplifier. It is the figure after setting an optical fiber with the plane sectional view of an auxiliary amplifier. It is sectional drawing which shows the adjustment mechanism of the light leakage amount of an auxiliary amplifier. It is sectional drawing of the use condition of an auxiliary amplifier and a leakage light detection apparatus. It is a top sectional view of the conventional leakage light detection device.

  FIG. 1 is a plan sectional view of an auxiliary amplifier 1 before setting an optical fiber, and FIG. 2 is a plan sectional view of the auxiliary amplifier 1 in which an optical fiber 20 is set. It is. FIG. 3 is a cross-sectional view showing a mechanism for adjusting the amount of light leakage of the auxiliary amplifier 1. FIG. 4 is a sectional view of the auxiliary amplifier 1 and the conventional leakage light detection device 30 in use.

The auxiliary amplifier 1 is set on the upstream side of the leakage light detection device 30 and amplifies the amount of light leakage.
In the auxiliary amplifier 1, a pair of guide rods 6 are attached to the pressing member 5 in the box 2, and a spring 8 is disposed at the end of the guide rod 6. Therefore, when the pressing member 5 is pressed down, the spring 8 is contracted, and when the pressing member 5 is released, the pressing member 5 can be reciprocated back to the original state by the elastic force of the spring 8.

  Further, in order to fix (lock) the reciprocating pressing member 5, a rotatable cam 10 is disposed at the center portion to constitute a locking mechanism. The cam 10 has an oval shape, and a concave groove (broken line) 11 into which the guide rod 6 can be inserted is formed at both ends of the cam 10. Further, an operating tool (pick) (not shown) for rotating the cam 10 is attached, and the rotating shaft 9 is rotated via the operating tool, so that the concave groove 11 of the cam 10 is in a horizontal state. By mounting (pressing) the guide rod 6 on the guide rod 6, the guide rod 6 is fixed and the reciprocating motion of the pressing member 5 is locked (FIG. 1). On the other hand, by rotating the operation tool from the locked state, When the ten concave grooves 11 are in the vertical state and separated from the guide rod 6, the guide rod 6 is in an unlocked state in which it can reciprocate (FIG. 2).

Further, the pressing member 5 is formed with two bent portions formed downward by the concave portion 12a, the convex portion 12b, and the concave portion 12c for bending the optical fiber, and the curvature radii of the concave portions 12a, 12c and the convex portion 12b. R is 2.5 to 3 mm with respect to the diameter d of the optical fiber of 0.9 mm. Therefore, the ratio of (radius of curvature R of concave or convex to bend) / (diameter d of optical fiber) is (2.5 to 3 mm) /0.9=2.77 to 0.33, and this value Is preferable for improving sensitivity.
Further, a screw body 15 is attached to the central convex portion 12b of the pressing member 5, and the tip end portion of the screw body 15 depends on the amount of rotation of the adjustment button 18 that rotates the screw body 15. The amount of light leakage can be adjusted by protruding from the convex portion 12b and pressing the optical fiber 20.

On the other hand, a fixing member 16 is provided in the box 2 corresponding to the pressing member 5 that moves up and down. The fixing member 16 also has convex portions 17a and 17c corresponding to the concave portions 12a and 12c and the convex portion 12b. Further, the concave portion 17b is formed, and the radius of curvature R thereof is the same as the radius of curvature R of the concave portions 12a, 12c and the convex portion 12b.
Therefore, the optical fiber 20 is tightly attached by the two bent portions, and the amount of light leakage can be adjusted by the screw body 15.

Next, the use of the auxiliary amplifier 1 will be described with reference to FIG. The auxiliary amplifier 1 is set on the upstream side of the leakage light detection device 30, and the separation distance L between the devices 1 and 30 is that the leakage light from the auxiliary amplifier 1 is combined with the leakage light in the leakage light detection device. A thickness of 20 to 30 mm that can improve the sensitivity is preferable.
And the lock | rock of the auxiliary | assistant amplifier 1 is cancelled | released, and after inserting an optical fiber between the uneven | corrugated | grooved part (12a-12c, 17a-17c) formed in the pressing member 5 and the fixing member 16, the pressing member 5 is made into the fixing member 16. When the optical fiber 20 is pushed and turned to be locked, two bent portions of the optical fiber 20 are formed.

  And since it is this locked state, the optical fiber 20 is closely attached on the same conditions. If necessary, the screw 15 can be rotated to adjust the amount of leaked light due to the difference in the amount of pressure applied to the optical fiber 20, and the light leaked at the bent portion of the auxiliary amplifier 1 is leaked light detection device 30. Since it is detected as the amount of light combined with the leaked light from the bent portion provided in, the leaked light can be detected in a stable state with improved detection sensitivity.

Further, the bending of the two optical fibers 20 is formed on the pressing member 5 and the fixing member 16, but the ratio of the radius of curvature R) / (optical fiber diameter d) of the concave portion to be bent is 2.77 to. If it is 0.33, it may be 1 or 3 or more.
Further, when the leakage light is detected by the leakage light detection device 30, the separation distance L from the auxiliary amplifier 1 is 20 to 30 mm, but the distance is further increased in the case of three or more bent portions where the leakage amount increases. You may arrange in a position.
Further, although the amount of leakage light is adjusted by the amount of pressure applied to the optical fiber 20 by the amount of rotation of the screw body 15, the amount of pressure applied to the optical fiber 20 may be adjusted by a tapered surface.

DESCRIPTION OF SYMBOLS 1 Auxiliary amplifier 2 Box 5 Press member 6 Guide bar 8 Spring 9 Rotating shaft 10 Cam 11 Groove 12a Recess 12b Protrusion 12c Recess 15 Screw body 16 Fixing member 17a Protrusion 17b Recess 18 Adjustment button 20 Optical fiber 30 Leakage light detection apparatus

Claims (4)

An auxiliary amplifier that is disposed upstream of a leaked light detection device for detecting leaked light by bending an optical fiber,
Form an uneven part that bends the optical fiber between the pressing member and the fixing member,
An auxiliary amplifier of a leaky light detection device, wherein a ratio of a radius of curvature of the concavo-convex portion to a diameter of an optical fiber is 2.77 to 0.33.   2. The auxiliary amplifier for a leak light detection apparatus according to claim 1, wherein two bent portions of the optical fiber are formed between the pressing member and the fixing member.   The auxiliary amplifier of the leaked light detection device according to claim 2, wherein the amount of leaked light is adjusted via a screw body in an optical fiber disposed between the pressing member and the fixing member. Attach a spring to the end of the fixed guide bar to the reciprocating pressing member,
The auxiliary amplifier of the leakage light detection device according to any one of claims 1 to 3, further comprising a lock mechanism for fixing the pressing member.

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