JPH043281Y2 - - Google Patents

Description

[Detailed description of the invention] [Background and purpose of the invention] The present invention relates to a multi-core optical rotary joint in which light propagating through a plurality of optical fibers is switched to a plurality of rotating optical fibers for propagation through a rotating prism. It is something.

A conventional multi-core optical rotary joint will be explained with reference to FIG. FIG. 2 is a longitudinal sectional view. In the figure, 1a and 1b are input side optical fibers, 1c and 1
d is an optical fiber on the output side, 2a and 2b are micro-convex lenses for the optical fiber on the input side, 2c and 2d are micro-convex lenses for the optical fiber on the output side, 3 is a trapezoidal prism, 3a is an input surface, and 3b is a lens for transmitting incident light. The bottom surface 3c for reflection is an output surface. 8 is a prism holder, 9 is a fixed body, 10a, 10b, 10
c and 10d are speed change gears; 11a and 11b are receptacles that hold the incident side optical fibers 1a and 1b;
11c and 11d are receptacles that hold the incident side optical fibers 1c and 1d, 12 is a rotating body, and 13 is a speed change gear shaft. Ball bearings 18a and 18b rotatably connect the fixed body 9 and the rotating body 12; ball bearings 18c and 18d rotatably connect the fixed body 9 and the prism holder 8;
Ball bearings e and 18f rotatably connect the fixed body 9 and the speed change gear shaft 13. and,
The rotating body 12 is configured to rotate at twice the number of rotations of the trapezoidal prism 3.

This multi-core optical rotary joint uses a trapezoidal prism 3, and if the prism diameter is S ₁ , then
The prism length l ₁ is l ₁ =4.23×S ₁ . Also,
In the case of a general spur gear, the transmission gears 10b and 10c are installed unevenly as shown in Fig. 2, which increases the overall size. optical fiber 1c,
1d, the optical transmission loss increases.

Furthermore, the multi-core rotary joint is used to transmit light to a moving body such as a crane, and the rotating body 12 often rotates in forward and reverse directions, and the trapezoidal prism 3 rotates 1/2 of the rotation of the rotating body 12. Rotates with angular velocity. Therefore, the speed change gears 10a, 10b,
If there is a backlash in 10c, 10d, etc., the optical axis of the incident light will change from the input side optical fiber 1a to the output side optical fiber 1d and from the input side optical fiber 1b to the output side optical fiber 1c during the transition between forward and reverse rotation. Misalignment occurs, increasing optical transmission loss between the optical fibers. Further, abrasion powder generated when the gears mesh adheres to the exit surface 3c of the trapezoidal prism 3, increasing optical transmission loss. In addition, the total length l ₂ of this multi-core optical rotary joint is the total length l ₁ of the trapezoidal prism 3.
This is about twice as large, making the whole structure larger and increasing its weight, which is not preferable.

The present invention was developed in view of the above-mentioned circumstances, and aims to provide a multi-core optical rotary joint that can reduce optical transmission loss, exhibit high performance, and be compact.

[Summary of the invention] The gist of the invention is to provide a ball bearing that rotatably connects the prism holder of the Petyan prism to a rotating body and a fixed body, and a system for rotating the prism holder at an angular velocity that is half the angular velocity of the rotating body. A planetary gear, a gear, and a rotary drive shaft are provided on the outer periphery of the prism holder.

[Embodiments of the Invention] The multi-core optical rotary joint of the present invention will be described below with reference to FIG. 1 using an embodiment, in which the same parts as in the conventional art are denoted by the same reference numerals and the explanation of the structure of the same parts is omitted. 1st
The figure is a longitudinal sectional view. In the figure, 14a, 14
b is a cylindrical focusing lens for the input side optical fibers 1a and 1b, and 14c and 14b are output side optical fibers 1.
This is a cylindrical converging lens for C and 1D. 17
Ball bearings a, 17b, 17c, and 17d rotatably connect the prism holder 8 of the Petyan prism 16 to the rotating body 12 and the fixed body 9.

15a is a gear provided on the outer periphery of the rotating body 12;
15b and 15c are planetary gears of the same shape that are interposed between a gear 15d and a gear 15a provided on the inner periphery of the fixed body 9 and rotate. 13a is attached to the flange-like part of the prism holder 8, and planetary gears 15b,
It is a rotational drive shaft that is fitted into the prism holder 15c and rotates the prism holder 8. Further, inside the prism holder 8, a Pechiyan prism 16 is held such that its input and output surfaces are perpendicular to the optical axes of the input side optical fibers 1a, 1b and the output side optical fibers 1c, 1d.

The light emitted from the incident side optical fiber 1a is corrected into a parallel beam by the cylindrical converging lens 14a, and enters the incident surface 16a of the Pechiyan prism 16. The light that has gone straight through the Pechan prism 16 passes through the reflection surfaces 16b, 16c, 16a, 16d, and 16b, and then passes through the output surface 16e and the cylindrical converging lens 14d.
The light then propagates to the output side optical fiber 1c in the rotating body 12. That is, the reflective surface 16b at the center of the Pechiyan prism 16 reflects incident light at 45 degrees to the normal, and transmits light incident at right angles to the reflective surface 16b. Similarly, the light incident from the input side optical fiber 1b also propagates to the output side optical fiber 1d.

When the rotating body 12 rotates at an angular velocity ω, the number of teeth of the speed change gears 15a, 15b, 15c, and 15d is selected and the prism holder 8 and Pechiyan prism 1
6 is adapted to be rotated in the same direction at an angular velocity of 1/2ω of the angular velocity of the rotating body 12. The behavior of the light at this time is exactly the same as when using the trapezoidal prism 3 of the conventional example, and the image on the rotating body 12 side is in a stationary state when viewed from the stationary fixed body 9 side, and the propagation of the multiple optical fibers is It becomes possible. Petyan prism 16
is a type of image rotating prism, with 1/2
There is a characteristic that when rotated by θ, the image rotates by θ.
This embodiment reversely utilizes this.

If the diameter of the Pechiyan prism 16 is S, which is the same size as the diameter S ₁ of the trapezoidal prism ₃ in FIG _.
×S ₁ , the length of the trapezoidal prism 3, l ₁ = 4.23
Compared to ×S ₁ , it is shortened to about 1/3.5. However, the optical path length within the prism is the same for both. Also, a prism holder 8 that holds the Petyan prism 16 is provided.
Since the rotating body 12 is located on the outer periphery of the rotating body 12, and a speed change mechanism using planetary gears 15b and 15c is provided on the outside thereof, the distance between the output surface 16e and the receptacles 11c and 11d for holding the output side optical fibers can be shortened. Therefore, optical transmission loss between the input side optical fibers 1a, 1b and the output side optical fibers 1c, 1d can be reduced. Moreover, when the gears mesh, abrasion powder is released from the exit surface 1 of the Pechiyan prism 16.
It is possible to prevent the optical transmission loss from increasing due to adhesion to 6e. Furthermore, as shown in the figure, planetary gears 15b and 15c of the same shape are stacked and a spring (not shown) is used.
If the tooth surface is always in contact with the meshing surface of the gears 15a, 15d through a screw or the like to prevent backlash from occurring, accuracy can be further improved and the connection between the input side optical fibers 1a, 1b and the output side optical fiber during forward and reverse rotation can be improved. It is possible to prevent misalignment of the optical axis with respect to 1c and 1d and improve optical transmission performance. The total length l ₄ of the multi-core optical rotary joint in this embodiment is (1.6×l ₁ =2×S ₁ ), and the total length l ₃ of the conventional example is (2×l ₁ =8.5S _{1 )} . ) can be shortened to less than 1/4.

[Effects of the invention] As described above, according to the multi-core optical rotary joint of the invention, a ball bearing rotatably connects the prism holder of the Petyan prism to the rotating body and the fixed body, and the angular velocity of the rotating body is By providing a planetary gear, a gear, and a rotational drive shaft for rotating the prism holder at half the angular velocity on the outer circumference of the prism holder, the distance between the input optical fiber and the output optical fiber can be shortened. , it is possible to prevent abrasion powder generated when gears mesh from adhering to the prism exit surface. As a result, the optical transmission loss can be significantly reduced, and an extremely compact multi-core optical rotary joint can be provided, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the multi-core optical rotary joint of the present invention, and FIG. 2 is a longitudinal sectional view of a conventional multi-core optical rotary joint. 1a, 1b...Incidence side optical fiber, 1c, 1d
... Output side optical fiber, 9 ... Rotating body, 12 ...
Rotating body, 15a, 15d... Gear, 15b, 15
c... Planetary gear, 16... Petyan prism, 1
7a, 17b, 17c, 17d...Ball bearings.

Claims (1)

[Scope of utility model registration request] When optically connecting a plurality of optical fibers installed on a rotating body and a plurality of optical fibers installed on a fixed body that accommodates the rotating body in a one-to-one manner, A Pechiyan prism is arranged on the optical axis between the optical fiber end face and the optical fiber end face of the fixed body, and the Pechiyan prism is moved at an angular velocity that is half of the angular velocity of the rotating body so that the center between the plurality of optical axes is and means for rotating the rotating body in the same direction as the rotating body as a rotation center, the ball bearing rotatably coupling the prism holder of the Petyan prism to the rotating body and the fixed body, and the rotating body A multi-core optical rotary joint, characterized in that a planetary gear, a gear, and a rotary drive shaft are provided on the outer periphery of the prism holder for rotating the prism holder at an angular velocity that is half of the angular velocity of the prism holder.