JPH0750723Y2 - Optical fiber coil - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical interference angular velocity using an optical fiber, for example, an optical fiber coil used for an optical fiber sensor of a so-called optical fiber gyro, and particularly when an external vibration is generated, the optical fiber resonates with the vibration. The present invention relates to an optical fiber coil configured to suppress

[0002]

2. Description of the Related Art In a conventional optical fiber coil of this type, as shown in FIG. 4, an optical fiber 12 is wound around a cylindrical bobbin 11. This optical fiber coil is used by being fixed to the mounting base 13. When the mounting base 13 is subjected to external vibration during use and the bobbin 11 vibrates, the vibration causes the optical fiber 12 to resonate with the vibration. And the winding diameter of the optical fiber 12 fluctuates greatly,
It will not work properly as a sensor.

Therefore, conventionally, the bobbin 11 and the optical fiber 12 are provided.
At the time of winding, the optical fiber was relatively tightly wound by giving a relatively strong tension. Alternatively, as shown in FIG. 5, the optical fiber 12 is wound around the bobbin 11 while being bonded with the adhesive 14.

[0004]

However, in the former case, due to the difference in the thermal expansion coefficient between the optical fiber 12 and the bobbin 11, the bobbin 11 thermally expands more than the optical fiber 12 at a high temperature, and the bobbin 11 causes the optical fiber 12 to expand. Since it spreads from the inside, strong stress is applied to the optical fiber 12, and in the latter case, due to the difference in the thermal expansion coefficient between the optical fiber 12 and the adhesive 14, the adhesive 14 shrinks more than the optical fiber at low temperature. Since the adhesive 14 compresses the optical fiber 12 from the outside, strong stress is still applied to the optical fiber. In any case, the stress causes the optical propagation constant of the optical fiber 12,
Optical characteristics such as the refractive index change, and the characteristics as a sensor change.

[0005]

In this invention, an optical fiber is wound around the outer circumference of a bobbin, and an elastic body is provided which elastically presses the optical fiber from the outside to the peripheral surface of the bobbin. With this configuration, the optical fiber is in close contact with the bobbin, and even if the bobbin vibrates, the optical fiber does not resonate with the vibration.

[0006]

FIG. 1 shows an embodiment of this invention. The optical fiber coil includes a bobbin 11, an optical fiber 12 wound around the outer circumference of the bobbin 11, and an elastic body 15 that presses the optical fiber 12 from the outside to the bobbin 11.
In this example, the bobbin 11 has a cylindrical shape and has flanges 11a and 11a at both ends of the cylinder. The optical fiber 12 is wound around the outer circumference of the bobbin 11 between the both flanges 11a one or more times for each layer in a plurality of layers. In this example, the outermost layer is drawn inward from the outer edges of both flanges 11a. An elastic body 15 is arranged in pressure contact with the outermost layer of the optical fiber 12, and the elastic body 15 elastically presses the optical fiber 12 from the outside to the peripheral surface of the bobbin 11.

In this example, the elastic body 15 is the optical fiber 12
The outermost layer and the flange portions 11a are arranged so as to be almost fitted in the concave portions formed by the flange portions 11a. As a material forming the elastic body 15, for example, sheet-shaped silicon rubber is used. A cover 16 concentric with the bobbin 11 is provided outside the elastic body 15,
The elastic body 15 is elastically sandwiched between the inner peripheral surface of the cover 16 and the outermost layer of the optical fiber 12, and the elastic body 15 is elastically pressed against the outermost layer of the optical fiber 12. The cover 16 is
For example, the cylindrical shape is closed at one end, and its open end is used as the mounting side to the mounting base 13. A space is provided between the inner peripheral surface of the cover 16 and the outer peripheral surface of the flange 11a. The magnitude of this pressing force is not so large as to give a stress to the optical fiber 12 that affects its optical characteristics, and is suitable for suppressing the resonance of the optical fiber with the vibration of the bobbin 11. Set to size. Therefore, the thickness of the elastic body 15, the elasticity thereof, and the distance between the outermost layer of the optical fiber 12 and the inner peripheral surface of the cover 16 are appropriately selected.

Therefore, in the optical fiber coil of this example,
When the optical fiber 12 is wound, the optical fiber is pressed against the peripheral surface of the bobbin 11 by the elastic body 15 without increasing the tension so much that the optical fiber does not vibrate in the bobbin without a strong stress being applied to the optical fiber. Resonance is suppressed. As shown in FIG. 2, an elastic body 15a may be interposed between the bobbin 11 and the optical fiber 12 as compared with the embodiment shown in FIG. As the elastic body 15a, the distance between the optical fiber 12 after winding and the bobbin 11 hardly changes due to the bobbin vibration, and the optical fiber and the bobbin are well blended and integrated, and the elastic pressing effect of the elastic body 15 is obtained. Is preferable. When such an elastic body 15a is made of the same material as the elastic body 15, a material thinner than the elastic body 15 is used for the elastic body 15a.

In the optical fiber coil of this example, resonance of the optical fiber with respect to bobbin vibration is suppressed, and the difference in expansion / contraction between the bobbin 11 and the optical fiber 12 due to temperature change is absorbed by the elastic body 15a, and the optical fiber is absorbed. No stress that affects the optical characteristics is applied. Therefore, it is not necessary to select a bobbin material considering the coefficient of thermal expansion.

Still another embodiment shown in FIG. 3 is a case where the bobbin 11 in the optical fiber coil shown in FIG. 2 has an elliptic cylindrical shape. When the bobbin has an elliptical shape, when the optical fiber resonates with the vibration of the bobbin, the fluctuation of the diameter of the optical fiber is promoted in the major axis portion, so the effect of suppressing the resonance of the optical fiber in the present invention is that the bobbin has a cylindrical shape. Bigger than case.

[0011]

As described above, in the optical fiber coil of the present invention, since the elastic body elastically presses the optical fiber against the peripheral surface of the bobbin, the optical characteristics of the optical fiber are affected. Even if external vibration is applied to the bobbin without applying stress, there is no possibility that the optical fiber resonates with the external vibration, and the optical fiber sensor can be satisfactorily operated.

[Brief description of drawings]

FIG. 1 is an explanatory longitudinal sectional view showing an embodiment of an optical fiber coil of the present invention.

FIG. 2 is an explanatory longitudinal sectional view showing another embodiment of the optical fiber coil of the present invention.

FIG. 3 is a perspective view showing a part of still another embodiment of the optical fiber coil of the present invention in section.

FIG. 4 is an explanatory longitudinal sectional view showing a conventional optical fiber coil.

FIG. 5 is an explanatory longitudinal sectional view showing another conventional optical fiber coil.

Claims (1)

[Scope of utility model registration request] 1. An optical fiber coil comprising a bobbin, an optical fiber wound around the outer circumference of the bobbin, and an elastic body that elastically presses the optical fiber from the outside to the peripheral surface of the bobbin.