JPH0714962Y2 - Photodetector for core control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a photodetector for a fiber-corresponding device used during construction and maintenance of optical fiber lines.

(Prior Art) When constructing and maintaining an optical fiber line, it becomes necessary to perform a core wire comparison without affecting the transmission characteristics of the working line. A core wire checking device used for this purpose is known to include a transmitter, a receiver, and a photodetector directly connected to the receiver.

In FIG. 2, an optical fiber cable 1 is laid between the A station and the B station. For example, in the manhole at the C point, the core line of the A station is compared with the core line of the C point. At the point C, a mandrel in the photodetector 3 imparts a curved portion to the optical fiber core wire by sending an optical signal for optical fiber comparison from the transmitting portion 2 in the station. The light receiving sensor detects the presence or absence of light reception to detect the presence or absence of light reception, and converts the electric signal into an electric signal and determines the light reception level by the receiving unit 4 directly connected to the photodetector 3. At this time, it is confirmed by sequentially connecting the optical fibers one by one to which optical fiber the optical signal for optical fiber comparison is sent.

A plan view of the photodetector 3 is shown in FIG. In the figure, 5 is a guide for holding the optical fiber core wire, 6 is an LED that blinks when a light level above a predetermined level is detected, and 7 is a connection terminal for connecting to the receiving section.

As shown in FIG. 4, inside the photodetector 3, mandrel 9 and 10 of equal diameter having fixed shafts with a gap 11 between them for providing a curved portion to the optical fiber core wire 8 and a gap 11 are provided. A mandrel 12 slidable toward the side is provided, and a light receiving sensor 13 is provided.

The photodetector 3 as described above is attached to the optical fiber core wire in the manhole C, and the mandrel 12 is slid toward the gap 11 between the mandrel 9 and the mandrel 10 to bend the optical fiber core wire 8 as shown in FIG. Then, the optical signal for optical fiber comparison from the transmission unit 2 leaks at the curved portion of the optical fiber optical fiber 8. The LED of the photodetector 3 blinks when this minute leaked light is detected by the light-receiving sensor 13, converted into an electric signal and detected by the receiving unit 4, and when light of a specified level or higher is detected. Confirms the core control.

(Problems to be solved by the invention) In order to give a curved portion to the optical fiber core wire by the mandrel in the photodetector, as shown in FIG.
The optical fiber core wire is sandwiched between the mandrel 9 and the mandrel 9 and the mandrel 12 is slid in the gap direction (downward in the figure) between the mandrel 9 and the mandrel 10 as shown in FIG. Θ ₁ = 60 as shown in FIG.
The optical fiber core is bent by sliding until the angle becomes θ, θ ₂ = 120 °.

At this time, friction is generated between the optical fiber core wire 8 and the mandrel 9 and the mandrel 10, and stress is applied to the optical fiber by this frictional force. This stress varies depending on the physical properties such as Young's modulus of the coating material of the optical fiber core wire 8 and is expressed by the efficiency of trapping leaked light, that is, the ratio of the optical power in the optical fiber core wire 8 to the leaked light detection power. Variation occurs in the coupling loss. In addition, this differs depending on the slipperiness and the like depending on the coating state even in the same optical fiber. That is, the detection level of the leaked light differs depending on the type of the optical fiber coating material and the surface state thereof, and thus the detection may not be possible in some cases.

Therefore, a structure is proposed in which the mandrel is rotated around each fixed axis by the frictional force between the optical fiber core wire 8 and the mandrel 9 and the mandrel 10 to eliminate the above stress. However, even in this case, there is a frictional force, so the stress is not always completely eliminated. In addition, if the rigidity is low, such as the optical fiber core wire,
As shown in the figure, the optical fiber core may bend,
This causes variations in coupling loss.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and includes a mandrel 9, a mandrel 10, and a mandrel.
When the optical fiber core wire 8 is sandwiched between the optical fiber core wire 8 and the mandrel 9, the optical fiber core wire 8 has a rigidity sufficiently higher than the rigidity of the optical fiber core wire 8 against bending, and is used. It is intended to provide a photodetector mounted so as to interpose a single sheet made of a transparent polymer material having a small loss with respect to wavelength.

(Operation) When the curved portion is added to the optical fiber core as described above,
By interposing a sheet having a rigidity higher than that of the optical fiber core, the optical fiber core is guided by the sheet and is always kept constant without bending, and stress is absorbed by the sheet and stress is applied to the optical fiber. Since it does not exist, the variation in coupling loss is small.

(Embodiment) FIG. 1 is a cross-sectional view of a main part of a photodetector according to the present invention, that is, a mandrel part, and (a) shows a state in which a curved part is not added to the optical fiber core wire, (b) ) Indicates a state in which a curved portion is added to the optical fiber core wire by the mandrel. In the figure, mandrel 12 is mandrel 9 and mandrel
It is slidable (up and down in the figure) toward the gap between the mandrel 12 and the mandrel 9 and the mandrel 10 and is thicker than the optical fiber core wire. , A single sheet made of a transparent polymer material that has little loss with respect to the wavelength used, for example, polyester
I have attached 14. When giving a curved portion to the optical fiber core wire, the optical fiber core wire 8 is inserted along with the groove 14 formed along the circumferential surface of the mandrel 12 and inserted between the optical fiber core wire 8 and the sheet 14 to form the mandrel 12. To bend the optical fiber core wire 8.

(Effect of the Invention) In the photodetector of the present invention, the stress generated when the mandrel imparts a curved portion to the optical fiber core is absorbed by the sheet, so that no stress is applied to the optical fiber core.
Further, since the optical fiber core wire can be given a bent shape with good reproducibility without being slackened by being guided by the sheet, the ratio between the optical power in the optical fiber core wire and the leaked light detection power can be calculated. The variation of the coupling loss represented is eliminated, and the leaked light can be reliably captured.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a photodetector for an optical fiber core wire reference device according to the present invention, that is, a mandrel part.
(B) shows a state in which a curved portion is added to the optical fiber core wire. FIG. 2 is a schematic diagram for explaining the optical fiber comparison device and optical fiber identification, FIG. 3 is an external plan view of the photodetector, FIG. 4 is a cross-sectional view of the main part of the optical detector, and FIG. (A) to (c) are cross-sectional views for explaining the pattern of giving a curved portion to the optical fiber core wire, and FIG. 6 shows slack in the optical fiber core wire when the curved portion is given to the optical fiber core wire. It is sectional drawing of the principal part in a case. 8: Optical fiber core wire, 9, 10: Mandrel with fixed axis, 1
1: Gap, 12: Slidable mandrel, 13: Light receiving sensor, 1
4: Sheet.

Claims (1)

[Scope of utility model registration request] 1. A mandrel (1) and a mandrel (10) of equal diameter having fixed shafts with a gap between them, and a mandrel (1) slidable toward a gap (11) between these mandrels.
2), and a photodetector for a core wire contrast device, wherein a curved portion is provided by sandwiching the optical fiber core wire (8) between the mandrel (9) and (10) and the mandrel (12), When the optical fiber core wire (8) is sandwiched as described above, it is more rigid than the optical fiber core wire (8) so as to be interposed between the optical fiber core wire (8) and the mandrels (9) and (10). A photodetector for a fiber-correlation device, characterized in that a large transparent sheet is attached.