JP2877541B2 - Optical rotary connector and optical drum using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical rotary connector for connecting a pair of optical fibers and an optical drum using the same.

[0002]

2. Description of the Related Art An optical drum for winding an optical fiber generally rotates a drum having a bobbin so that the optical fiber can be wound or unwound while conducting an optical signal. In this case, since the winding end of the optical fiber also rotates with the rotation of the drum, the winding end of the optical fiber is positioned at the rotation center of the drum, and the winding end is pulled out to the outside via the optical rotary connector. It has become.

[0003] A conventional optical rotary connector is constructed by abutting a fixed ferrule holding the tip of one optical fiber and a rotating ferrule holding the tip of the other optical fiber. A selfoc lens is interposed between the end faces. The SELFOC lens expands the beam so that an optical signal can be transmitted, thereby mitigating radial blur caused by the mechanical accuracy of the bearing of the rotating ferrule.

[0004]

In such a conventional optical rotary connector, a selfoc lens is required, the alignment of the optical axis is troublesome, the coupling loss between one optical fiber and the selfoc lens, and the cell loss. The optical loss of the Fock lens itself and the coupling loss between the Selfoc lens and the other optical fiber occur, and there is a problem that the coupling loss becomes large as a whole.

It is an object of the present invention to provide an optical rotary connector having a simple structure and reduced coupling loss of an optical fiber, and an optical drum using the same.

[0006]

In order to achieve the above object, according to the present invention, a fixed ferrule holding the tip of one optical fiber is brought into contact with the fixed ferrule, and the other optical fiber is brought into contact with the fixed ferrule. The tip of the cylindrical rotating ferrule whose tip is held at the axis, and the tip of one optical fiber and the other optical fiber are located on the same axis,
A split sleeve is provided which includes the fixed ferrule and the rotating ferrule in a state where the distal ends of the ferrules face each other.

In this case, the distal end face of one optical fiber and the distal end face of the other optical fiber are formed in a concave shape, and the distal end face of one optical fiber and the distal end face of the other optical fiber are formed in a concave shape. Is preferably filled with a refractive index matching agent.

According to a fourth aspect of the present invention, the rotary connector is the same as the optical rotary connector according to any one of the first, second, and third aspects, wherein an engagement protrusion or an engagement groove is formed on the peripheral surface of the rotating ferrule. A rotary drum that has a bobbin that can be wound around an optical fiber and that is positioned on the rotary shaft and that is capable of winding an optical fiber around the rotary drum; a rotary drive unit that rotates the rotary drum; A rotating body having an engaging protrusion or an engaging groove that engages with the protrusion or the engaging groove and synchronously rotating the rotating drum and the rotating ferrule is provided.

In this case, it is preferable that the engagement protrusion or the engagement groove of the rotating body and the engagement protrusion or the engagement groove of the rotating ferrule are engaged in a loosely connected state.

[0010]

In the structure of the first aspect, the rotating ferrule is formed in a cylindrical shape, and the tip of the rotating ferrule is included in the split sleeve, so that the rotating ferrule is rotated using the split sleeve as a bearing. In this case, the tip of the other optical fiber held by the rotating ferrule is located at its axis, and this optical fiber, one optical fiber of the fixed ferrule and the split sleeve are located on the same axis. I have. Therefore, the rotating ferrule is rotated while maintaining the optical axis alignment. Since the split sleeve expands due to thermal expansion of the ferrule and the like, the rotation-side ferrule is smoothly rotated without galling.

Further, if the distal end surface of one of the optical fibers and the distal end surface of the other optical fiber are formed in a concave shape, the beam is collimated on the distal end surface of one (the other) optical fiber and then collimated. On the other hand, the optical fiber is transmitted while being narrowed down at the tip end surface of the optical fiber. Furthermore, if the abutting gap between the end faces of both optical fibers is filled with a refractive index matching agent, diffusion of light from the end faces of the optical fibers is suppressed. In addition, the refractive index matching agent acts as a lubricant, and together with the concave shape of the distal end surface, damage to the distal end surface of the optical fiber during rotation is prevented.

According to the fourth aspect of the present invention, the optical rotary connector is used to rotate the rotary drum and the rotating ferrule synchronously via the rotary body, so that the optical fiber is wound or wound while the optical signal is kept in a conductive state. As a result, the coupling loss is suppressed, and the optical loss is reduced as a whole.

[0013] In this case, the rotating body and the rotating ferrule are adapted to transmit rotation by engaging an engaging protrusion and an engaging groove provided on each of the rotating body and the rotating ferrule. Are engaged in a loosely connected state so that an external force generated by thermal expansion of the rotating body does not directly reach the rotating ferrule.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical rotary connector according to an embodiment of the present invention and an optical drum using the same will be described below with reference to FIGS. Here, FIG. 1 is a cut-away side view of the optical rotary connector, FIG. 2 is an enlarged sectional view of a butt end face of the optical rotary connector, and FIG. 3 is a longitudinal sectional view of the optical drum.

First, in order to facilitate understanding of the optical rotary connector of this embodiment, an optical drum using the optical rotary connector will be described. As shown in FIG. 3, the optical drum 1 includes a cylindrical rotary drum 2 around which a two-core SK type optical fiber cord C is wound, a rotary driving unit 3 for driving the rotary drum 2 to rotate, and a rotary drum 2. A pair of left and right optical rotary connectors 4 and 4 positioned on the axis of the optical rotary connector, and a rotating body 5 that engages with the rotating system of each optical rotary connector 4 and rotates the rotating system synchronously with the rotating drum 2. Component 6 in casing
It is configured to be housed in. In the optical drum 1, a cord-like first (other) optical fiber Fa, which is drawn into the casing 6 from the outside, wound around the rotating drum 2, and further connected to the rotating system of the optical rotary connector 4. F
a from the fixed system of the optical rotary connector 4 to the casing 6.
The cord-like second (one) optical fibers F1 and F2 drawn out of the optical fiber are joined by the optical rotary connector 6.

The rotating drum 2 is rotatably supported on the outer peripheral surfaces of both ends by bearings 8, 8 held on a pair of left and right ring blocks 7, 7 fixed to both inner surfaces of the casing 6, respectively. The optical rotary connector 4 is attached to a portion corresponding to. The intermediate portion 2a in the circumferential direction of the rotating drum 2 protrudes in a belt shape, and the first optical fiber F1 is wound around the intermediate portion 2a and a pair of left and right circular plates 21 and 21 attached so as to sandwich the intermediate portion 2a. A bobbin 22 is configured. One portion of the intermediate portion 2a of the rotary drum 2 is provided with the bobbin 22 and the rotary drum 2
A take-out hole 2b communicating with the inside of the tube is formed, and the winding end of the first optical fiber F1 can be guided to the optical rotary connector 4 from the take-out hole 2b. On the other hand, each side surface of the rotary drum 2 is closed by a lid 23 having an opening 23a at the center, and the optical rotary connector faces the opening 23a of the lid 23. ing. A rotating body 5 that engages with a rotating ferrule (rotating system) 51 of the optical rotary connector 4 described below and that rotates the rotating ferrule 51 in synchronization with the rotating drum 2 is fixed to each of the openings 23a.

The rotating body 5 includes a cylindrical main body 31 enclosing the rotating ferrule 51, a coil spring 32 for urging the rotating ferrule 51 in the axial direction, and a spring press 33 receiving a reaction force of the coil spring 32. It is composed of While an internal thread is formed on the inner surface of the main body 31,
An external thread is screwed onto the outer peripheral surface of the spring push 33, and the rotating ferrule 51 inserted into the main body 31 is pushed through the coil spring 32 into the spring push 3.
In step 3, it can be biased with an appropriate biasing force. Further, two fin-shaped engaging projections 34, 34 are formed inwardly facing each other at an end of the inner surface of the main body 31, and the rotating projections 34 of the optical rotary connector 4 are formed by the engaging projections 34. That is, it engages with the rotating system. On the other hand, a fixing system of the optical rotary connector 4 is fixed to an outer surface of the housing 6 via a holder 9.

The rotary drive means 3 is provided at a drive shaft 42 pivotally supported by a bearing 41 mounted on the housing 6, a rotary plate 43 provided at one end of the drive shaft 42, and at the other end. A first gear 44 and a second gear 45 meshed with the first gear 44 and fixed to the outer peripheral surface of the rotating drum 2. 43, a drive shaft 42, a first gear 44, and a second gear 45 in this order.
Can be driven. That is, the forward and reverse rotation of the handle 46 causes the first optical fiber F <b> 1 to be wound and unwound with respect to the rotating drum 2.
At this time, since the winding end of the first optical fiber F1 is connected to the rotation-side ferrule 51 of the optical rotary connector 4 located at the axis of the rotary drum 2, the first optical fiber F1 rotates while maintaining the conduction state of the optical signal. Is done. Note that the handle 46 is configured to be detachable so that anyone other than the operator cannot operate it without permission. Reference numeral 10 in the drawing denotes a rotary drum stopper that restricts rotation of the rotary drum 2.

FIG. 1A is an enlarged view of the optical rotary connector 4 located on the left side of FIG.
(A) shows a cross section of the engaging portion. As shown in the figure, the optical rotary connector 4 has a rotating ferrule 51 on which the distal end of the first optical fiber F1 is held.
And a fixed ferrule 52 that holds the distal end of the second optical fiber F2, and a split sleeve 53 that includes the distal ends of both ferrules 51, 52. The rotating side and fixed side ferrules 51 and 52 have flanges 51a and 52a in the middle respectively, and hold the first and second optical fibers F1 and F2 at their axial centers. . An engagement groove 54 is formed in the flange 51 a of the rotation side ferrule 51 at a radially opposed position, and is engaged with the engagement protrusion 34 formed on the main body 31 of the rotating body 5 in a loose contact state. (See FIG. 1B). The engagement between the engagement groove 54 and the engagement protrusion 34 causes the rotary drum 2 and the rotation-side ferrule 51 to rotate synchronously, while the loose force releases the external force from the engagement protrusion 34 to the engagement groove 54. Through the rotation side ferrule 51. That is, the rotating ferrule 5
1 is supported only by a split sleeve 53,
Is in a floating state with respect to the main body 31 so that the optical axis does not become out of alignment during rotation.

The split sleeve 53 contains the fixed ferrule 52 and the rotating ferrule 51 at the ends thereof in abutting condition on the same axis.
The distal end of 1 is rotatably inserted into the split sleeve 53. Therefore, regardless of the rotation of the rotation-side ferrule 51, the optical axes of the first and second optical fibers F1 and F2 held at the axial center portions of the two ferrules 51 and 52,
The axis of the split sleeve 53 is completely coincident with the axis. The split sleeve 53 is formed with a vertically split slit 53a so that rotation of the rotary ferrule 51 does not hinder rotation due to thermal expansion or the like.

As described above, the split sleeve 53 projects the distal ends of the fixed ferrule 52 and the rotating ferrule 51, that is, the distal end face F1a of the first optical fiber F1 and the distal end face F2a of the second optical fiber F2. It will be in a matching state. The distal end face F1a of the first optical fiber F1 and the distal end face F2a of the second optical fiber F2 are respectively shown in FIG.
Are formed in a concave shape, as shown in FIG.
The signal light beam emitted from the distal end face F1a of the optical fiber F1 spreads, is transmitted to the second (first) optical fiber F2, is converged on the distal end face F2a, and is converged on the second (first) optical fiber F2.
1) reaches a focal point on the optical axis of the optical fiber F2. For this reason, even if rotational blurring occurs in the rotating ferrule 51, the coupling loss can be suppressed to a small value. In addition, the refractive index matching agent 5 is provided between the tip surfaces F1a and F2a of the first and second optical fibers Fa and Fb, that is, between the concave surfaces.
5 are filled. The refractive index matching agent 55 is made of, for example, silicon oil, and performs a lubricating action in addition to the action of adjusting the refractive index, reduces coupling loss, and realizes a smooth rotation of the rotating ferrule 51. Of the front end surfaces F1a and F2a of the two optical fibers Fa and Fb.

With the above configuration, the rotating ferrule 51 holding the first optical fiber F1 and the fixed ferrule 5 holding the second optical fiber F2 are provided.
The coupling loss can be reduced with a simple structure in which the two 2 are butt-connected by a split sleeve 53.

Next, an experiment performed by the applicant using the optical rotary connector 4 described in the above embodiment will be described.

In this experiment, a two-core SM optical fiber F
a, a fiber cord C having a diameter of 2 mm × length 50 m incorporating Fb, zirconia ceramic ferrules 51 and 52 having a diameter of 2.5 mm × length 8 mm, and a split sleeve 53 of the same zirconia ceramic. Was.
Further, the tip surfaces F1a, F2a of the optical fibers Fa, Fb.
Was subjected to a concave processing of about 0.5 μm or more.

As a result of the experiment, a coupling loss of about 0.2 dB in the stop state and a loss fluctuation of up to 0.3 dB in the rotation state,
Even at the maximum value, the coupling loss was 0.5 dB. Further, in this case, the fiber cord 50m was wound and unwound three times, but no change in the coupling loss was observed before and after the winding.

[0026]

As described above, according to the first aspect of the present invention,
Since it is composed of a fixed ferrule holding one optical fiber and a rotating ferrule holding the other optical fiber, and a split sleeve containing these tips, the structure is simple. The optical axis can be accurately aligned even when the rotation-side ferrule rotates, so that coupling loss can be reduced. In addition, the split sleeve can achieve a smooth rotational movement without blurring the optical axis. In addition, in this case, by forming the distal end surfaces of the two optical fibers in a concave shape, optical axis deviation due to rotation is reduced, and low coupling loss can be maintained. In addition, by filling the abutting gap between the end faces of the two optical fibers with the refractive index matching agent, the coupling loss can be reduced, and the rotation side ferrule can be smoothly rotated and the end face of the optical fiber can be prevented from being damaged. Can be.

According to the fourth aspect of the invention, the optical rotary connector is used to rotate the rotary drum and the rotating ferrule synchronously via the rotating body, so that the optical signal line length can be maintained while the optical signal is in a conductive state. Can be freely changed and rewound and unwound can be performed. In this case, since the engaging protrusion and the engaging groove provided respectively on the rotating body and the rotating ferrule are engaged in a loose contact state, this part of the rotating ferrule is in a floating state, and The deviation of the optical axis of the side ferrule can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical rotary connector according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a joint portion of the optical rotary connector of FIG.

FIG. 3 is a cut-away side view of an optical drum according to one embodiment of the present invention using the optical rotary connector of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical drum 2 ... Rotary drum 3 ... Rotation drive means 4 ... Optical rotary connector 5 ... Rotary body 22 ... Bobbin 31 ... Main body 34 ... Engagement protrusion 51 ... Rotation side ferrule 52 ... Fixed side ferrule 53 ... Split sleeve 54 ... Mating groove 55 ... refractive index matching agent C ... optical fiber cord F1 ... first optical fiber F1a ... tip face F2 ... second optical fiber F2a ... tip face

Continuation of front page (72) Inventor Hiroyuki Akimoto 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-61-213806 (JP, A) JP-A-2-33110 (JP, A) Japanese Utility Model Showa 61-78175 (JP, U) Japanese Utility Model Showa 62-53407 (JP, U) Japanese Utility Model Utility Model 1-60208 (JP, U) (58) Field surveyed (Int. Cl. ⁶⁾ G02B 6/36-6/38 G02B 6/00 336

Claims (5)

(57) [Claims] 1. A fixed ferrule holding an end of one optical fiber, a cylindrical ferrule abutted against the fixed ferrule, and a tip of the other optical fiber held on an axis. A split sleeve that includes the fixed-side ferrule and the rotating-side ferrule in a state where the distal ends of the fixed-side ferrule and the rotating-side ferrule abut each other such that the distal ends of the one optical fiber and the other optical fiber are located on the same axis. An optical rotary connector, comprising: 2. The optical rotary connector according to claim 1, wherein a tip surface of said one optical fiber and a tip surface of said other optical fiber are formed in a concave shape. 3. An optical rotary according to claim 2, wherein a gap between abutment of said one optical fiber and said other optical fiber is filled with a refractive index matching agent. connector. 4. The optical rotary connector according to claim 1, wherein an engagement protrusion or an engagement groove is formed on a peripheral surface of said rotation-side ferrule, and said rotary connector is on the same rotation axis. , A rotating drum having a bobbin around which an optical fiber can be wound, a rotation driving means for rotating the rotating drum, and an engagement of the rotating ferrule fixed to the rotating drum. An optical drum, comprising: a rotating body having an engaging protrusion or an engaging groove that engages with the protrusion or the engaging groove, and rotating the rotating drum and the rotating ferrule synchronously. 5. The engagement protrusion or engagement groove of the rotating body and the engagement protrusion or engagement groove of the rotating ferrule are engaged in a loosely contacted state. Light drum as described.