JP2011145547A - Hot-line detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot-line detector in which the positioning of a light detection part is easy and the variation in sensitivity is suppressed. <P>SOLUTION: The hot-line detector includes a photodiode 2 which detects the light P2 which leaks to a clad 11 side, which is a portion of light P1 propagating in the core 10 of an optical fiber 1. A protection coat 12, of which the portion in circumferential direction is a flat face 12a, is formed on the optical fiber 1, and the photodiode 2 is fixed on the flat face 12a via a transparent adhesive layer 3 composed of a transparent adhesive. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a live line detection device that detects whether or not an optical line formed by an optical fiber is in a live line state (a state in which light is normally transmitted through the optical line).

  2. Description of the Related Art Conventionally, there has been provided a live line detector that detects whether or not an optical line formed by an optical fiber is in a live line state (see, for example, Patent Document 1). This hot-line detector includes a modulation mechanism that modulates an optical signal by applying bending deformation to an optical fiber, and first and second detection mechanisms that are each provided with a light receiving element and are arranged on both sides of the modulation mechanism. In the state where the optical fiber is bent and deformed by the modulation mechanism, a part of the optical signal propagating in the optical fiber leaks from the bent portion, so that the leaked light is received by the light receiving element. The presence or absence of a signal can be detected. Then, when the leak light can be received by the light receiving element, the optical line is in a live line state, and when it is not received, it is determined that it is not in a live line state.

Japanese Patent Laid-Open No. 10-246818 (paragraph [0016] and FIG. 1)

  Some hot-line detectors such as Patent Document 1 described above are bonded using an adhesive or the like in order to improve the adhesion between the optical fiber and the light receiving element, but the cross-sectional shape of the optical fiber is circular. Therefore, it is difficult to fix the light receiving element at a predetermined position of the optical fiber, and there is a possibility that the sensitivity of the light receiving element varies when tilted in a plane intersecting the optical axis direction.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a hot-line detection apparatus in which the light detection unit can be easily positioned and sensitivity variations are suppressed.

  The invention according to claim 1 is a hot-wire detection device that detects whether or not an optical line formed by an optical fiber is in a hot-wire state, and leaks to the cladding side of the light propagating in the core of the optical fiber. A light detection portion for detecting light is provided, and a protective coating having a flat surface in the circumferential direction is formed on the optical fiber, and the light detection portion is fixed to the flat surface.

  According to a second aspect of the present invention, in the first aspect of the present invention, the light detection unit is fixed to a flat surface through a light transmission layer that transmits leakage light to the clad side.

  According to the first aspect of the present invention, since the mounting surface of the optical fiber is a flat surface, it is easy to position the light detection unit, and it does not tilt in a plane intersecting the optical axis direction. There is an effect that variations in sensitivity can be suppressed.

  According to the invention of claim 2, since the light detection unit is fixed to the flat surface through the light transmission layer, it is possible to increase the propagation efficiency of leaked light to the light detection unit. Since the light receiving efficiency is increased, the detection accuracy can be improved.

(A) is sectional drawing which looked at the hot-wire detection apparatus of this embodiment from the side, (b) is sectional drawing which looked at the same from the front. It is sectional drawing which looked at the other example same as the above from the side.

  An embodiment of a hot-wire detection apparatus according to the present invention will be described with reference to the drawings. In the hot-wire detection apparatus according to the present invention, for example, an optical line formed by fusing one end of two optical fibers is in a hot-wire state (a state in which light is normally transmitted through the optical line). Used to detect whether or not.

  FIGS. 1A and 1B are examples of the hot-wire detection device of the present embodiment, and this hot-wire detection device is light that leaks to the cladding 11 side of the light P <b> 1 that propagates in the core 10 of the optical fiber 1. A photodiode (light detection unit) 2 for detecting P2 is provided. In particular, in this embodiment, the light P2 leaking from the fusion part 13 in which one end parts of the two optical fibers 1 and 1 are fused together. Configured to detect. The photodiode 2 outputs a signal corresponding to the amount of received light.

  In the present embodiment, a circuit board (not shown) on which a discrimination circuit using a comparator is mounted is provided. When the signal input from the photodiode 2 exceeds a predetermined reference value, the discrimination circuit , A predetermined drive signal is output. Then, a light-emitting diode (not shown) is turned on by this drive signal to indicate that the optical line is in a live line state. Therefore, when the light emitting diode is turned off, it can be seen that the optical line is not in a live line state.

  The optical fiber 1 uses a quartz glass fiber that is excellent in environmental resistance such as propagation loss, transmission bandwidth, and mechanical strength, and in this embodiment, a single mode fiber is particularly used. Further, as light propagating through the optical fiber 1, it is preferable to use light having a wavelength in the ultraviolet region in consideration of transmission speed, bandwidth, etc. However, if the transmission speed or bandwidth is not a problem, this wavelength is not affected. The light is not limited to light, and may be light in the infrared region or visible region.

  Here, in the optical fiber 1 of this embodiment, as shown in FIG. 1B, the clad 11 is covered with a protective coating (for example, silicone resin) 12, and a predetermined position in the longitudinal direction A flat surface 12a is formed in a part in the direction. The photodiode 2 is fixed to the flat surface 12a. In the present embodiment, the photodiode 2 is fixed via a transparent adhesive layer 3 made of a transparent adhesive (for example, acrylic resin or epoxy resin). . Here, in the present embodiment, the transparent adhesive layer 3 constitutes a light transmission layer.

  Next, the operation of the live line detection apparatus of this embodiment will be described. Of the light P1 propagating through the core 10 of the left optical fiber 1 in FIG. 1 (a), the light P2 leaking from the fusion part 13 is shown in FIG. 1 (a) by the clad 11 and the transparent adhesive layer 3. And enters the photodiode 2, and the photodiode 2 outputs a signal corresponding to the amount of received light to the discrimination circuit. Then, the determination circuit outputs a drive signal because the signal input from the photodiode 2 exceeds the reference value, and turns on the light emitting diode.

  On the other hand, when there is no light P2 leaking from the fused portion 13, the light P2 does not enter the photodiode 2, so the photodiode 2 does not output the signal, and the discrimination circuit is connected to the photodiode 2. Since the signal is not input, the drive signal is not output. As a result, the light emitting diode is not lit. Therefore, the operator can determine whether or not the optical line is in a live line state by confirming the state of the light emitting diode (lighted or turned off).

  Thus, according to the present embodiment, since the mounting surface of the optical fiber 1 is the flat surface 12a, the positioning of the photodiode 2 is easy, and the optical fiber 1 does not tilt in the plane intersecting the optical axis direction. Variation in sensitivity of the photodiode 2 can also be suppressed. Furthermore, since the photodiode 2 is fixed to the flat surface 12a via the transparent adhesive layer 3, the propagation efficiency of the leaked light to the light detection unit can be increased, and as a result, the light receiving efficiency of the photodiode 2 is increased. Therefore, detection accuracy can be improved. Further, since the mounting surface of the optical fiber 1 is the flat surface 12a, the transparent adhesive layer 3 has a uniform thickness. For example, even when the transparent adhesive layer 3 is thermally deformed due to heat generated by the peripheral circuit such as the circuit board described above, it is substantially omitted. Since it is thermally deformed uniformly, peeling and cracking of the transparent adhesive layer 3 can be suppressed.

  In the present embodiment, the optical line formed by fusing one end portions of the two optical fibers 1 and 1 has been described as an example. For example, as shown in FIG. May be formed. In the present embodiment, the case where the optical fiber 1 is a single mode fiber has been described as an example. However, for example, a step index type multimode fiber or a graded index type multimode fiber may be used. In the present embodiment, the light transmission layer is formed by the transparent adhesive layer 3, but the light transmission layer may be formed by a liquid transparent layer such as matching oil. However, in this case, it is necessary to fix the light detection part to the flat surface by an appropriate fixing means.

1 Optical fiber 2 Photodiode (light detector)
10 core 11 clad 12 protective coating 12a flat surface P1, P2 light

Claims (2)

  A hot-line detection device that detects whether or not an optical line formed by an optical fiber is in a live-line state, and that detects light leaking to the clad side out of light propagating in the core of the optical fiber And a protective coating in which a part in the circumferential direction is a flat surface is formed on the optical fiber, and the light detection unit is fixed to the flat surface.   The hot detection device according to claim 1, wherein the light detection unit is fixed to the flat surface through a light transmission layer that transmits leakage light to the clad side.

Images