Optical fibre ferrule sleeve material, split sleeve and method of manufacturing a split sleeve

Abstract: A split sleeve material (10) is generally in a cylindrical form to have penetrating grooves (11 - 14) extending in an axial direction and, at respective end portions, annular end portions (15, 16) where the penetrating groove is not formed over an entire periphery thereof. A split sleeve (10A) is formed by cutting the annular end portions (15, 16). The split sleeve is produced by sintering and is used to connect two ferrules which hold optical fibers.

Description: BACKGROUND OF THE INVENTION This invention relates to a split sleeve material, a split sleeve and a method of manufacturing a split sleeve. The split sleeve material is used to make the split sleeve. The split sleeve is adapted to connect two ferrules which hold optical fibers in their central axes. Conventionally, split sleeves 100 as shown in Fig. 5 are being used to easily photo-coupling to each other ferrules for holding an optical fiber, or the like. The split sleeve 100 as shown in Fig. 5 is made of ceramics such as zirconia, which is usually formed by sintering a cylindrical body and then lapping an inner surface and then forming a slit 101 by grinding. Such sleeves are known from EP 0 590 586 A. However, there is a problem that, since the ceramics such as zirconia is very high in hardness, it takes much labor to form the slit 101 by grinding. On the other hand, there is another problem that, if the slit 101 is formed from a sintering stage, the entire shape is deformed. Also, there is a problem that the shape having one strip of a slit 101 provided in the cylindrical body as above tends to cause variations in inner diameter dimension and there is a fear that the center somewhat deviates to degrade in alignment stability. Therefore, for example, the coupling loss becomes large where coupling between ferrules holding an optical fiber. The present invention has been made in view of such situations, and it is the object to provide a split sleeve material easy to manufacture and by which a split sleeve excellent in alignment stability is obtainable, and split sleeve, and a method of manufacturing a split sleeve. SUMMARY OF THE INVENTION A split sleeve material, that solves the above problem, adapted for forming a split sleeve for fitting rod members therein from respective sides to thereby place the rod members at their tip surfaces in abutment against each other, shows the features of claim 1. The split sleeve material of the invention is for being formed into a split sleeve by cutting the annular end portions. A split sleeve of the present invention adapted for fitting rod members therein from respective sides to thereby place the rod members at their tip surfaces in abutment against each other, has the features of claim 3. A method of manufacturing a split sleeve adapted for fitting therein rod members from respective sides to thereby place the rod members at their tip surfaces in abutment against each other, is set forth in claim 4. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1A and 1B are perspective views of a split sleeve material and a split sleeve. Figs. 2A and 2B are perspective views of a split sleeve material and a split sleeve according to an embodiment of the present invention. Figs. 3A and 3B are perspective views of a split sleeve material and a split sleeve. Figs. 4A and 4B are perspective views of a split sleeve material and a split sleeve. Figs. 5 is a perspective view of a split sleeve according to the conventional art. DETAILED DESCRIPTION OF THE INVENTION Explanations will be made hereinbelow on embodiments of the present invention by the drawings. Fig. 1A is a perspective view of a split sleeve material, while Fig. 1B is a perspective view of a sleeve obtained from the same sleeve material. As shown in Fig. 1A, the split sleeve material 10 has substantially a cylindrical shape formed with axially-extending penetrating grooves 11 - 14 respectively at circumferentially opposite two locations thereof. These penetrating grooves 11 - 14 are not formed up to the respective axial end portions. At respective end portions of the split groove material 10, annular end portions 15 and 16 are provided where no penetrating groove 11 - 14 is formed in its circumferential direction. An annular portion 17 is also formed at an axially central portion so that the annular portion 17 is positioned between the penetrating groove 11, 13 and the penetrating groove 12, 14. The split sleeve material 10 like this employs, as a material, yttria-added partially-stabilized zirconia (ZrO 2 . Y 2 O 3 (Y 2 O 3 : contained by 3% in mol) which is temporarily formed in a shape as stated above and thereafter formed, for example, by heating at 150°C and further sintered at a high temperature of approximately 1500°C. Incidentally, the inner peripheral surface may be lapped as required after sintering. Also, there is no necessity of grinding an opening end face of the penetrating groove 11 - 14 so that it may be in a sintered skin as it is without necessity of grinding. The split sleeve material 10 of Fig. 1A is formed into a split sleeve 10A as shown in Fig. 1B by cutting the annular end portions 15 and 16 at the respective ends to open one end of each of the penetrating grooves. This split sleeve 10A has the penetrating grooves arranged symmetrical in the circumferential direction and the axial direction so that it is extremely high in alignment stability. Also, the split groove 10A like this is very difficult to form by the method of cutting the slits by grinding as the conventional. Embodiment: Fig. 2A is a perspective view of a split sleeve material according to a present invention, while Fig. 2B is a perspective view of a sleeve obtained from the same sleeve material. As shown in Fig. 2A, the sleeve material 20 of the present embodiment has substantially a cylindrical shape formed with axially-extending penetrating grooves 21 - 24 respectively at circumferentially opposite two locations. At respective end portions and an axially central portion, annular end portions 25, 26 and 27 are provided that are not formed with the penetrating groove 21 - 24 in the circumferential direction. Here, the penetrating grooves 22 and 24 adjacent the annular end portion 26 are opposite in a diametrical direction but the penetrating grooves 21 - 24 are deviated therebetween by 90 degrees in the circumferential direction. The split sleeve material 20 of Fig. 2A is formed into a split sleeve 20A as shown in Fig. 2B by cutting the annular end portions 25 and 26 at the respective ends to open one end of each of the penetrating grooves. This split sleeve 20A has the penetrating grooves arranged symmetrical in the circumferential direction and further in the axial direction so that it is extremely high in alignment stability. Also, the split groove 20A like this is very difficult to form by a method of cutting the slits by grinding as the conventional. Fig. 3A is a perspective view of a split sleeve material, while Fig. 3B is a perspective view of a sleeve obtained from the same sleeve material. As shown in Fig. 3A, the sleeve material 30 has substantially a cylindrical shape formed with axially-extending penetrating grooves 31 and 32 respectively extending in the axial direction at circumferentially opposite two locations. At respective end portions, annular end portions 35 and 36 are provided that are not formed with the penetrating groove 31 and 32 in the circumferential direction. Here, the penetrating grooves 31 and 32 are formed at locations opposite in a diametrical direction, but the penetrating groove 31 adjacent the annular end portion 35 is not extended up to the annular groove 36 and the penetrating groove 32 adjacent the annular end portion 36 is not extended up to the annular portion 35. However, the penetrating grooves 31 and 32 are overlapped with each other in the axially central portion so that no annular portion is provided at the central portion. The split sleeve material 30 of Fig. 3A is formed into a split sleeve 30A as shown in Fig. 3B by cutting the annular end portions 35 and 36 at the respective ends to open one end of each of the penetrating grooves. This split sleeve 20A has the penetrating grooves arranged symmetrical in the circumferential direction and the axial direction so that it is extremely high in alignment stability. Also, the split groove 20A like this is very difficult to form by making the slits through grinding as the conventional. This split sleeve 30A is wholly symmetrical in arrangement of the penetrating grooves, and very high in alignment stability. Also, the split sleeve 30A like this is difficult to form by the method of cutting a slit by grinding as the conventional. Fig. 4A is a perspective view of a split sleeve material, while Fig. 4B is a perspective view of a sleeve obtained from the same sleeve material. As shown in Fig. 4A, the split sleeve material 40 has substantially a cylindrical shape formed with an axially-extending penetrating groove 41 respectively extending in the axial direction at a circumferentially one location. At respective end portions, annular end portions 45 and 46 are provided that are not formed with the penetrating groove 45 and 46 in the circumferential direction. The split sleeve material 40 of Fig. 4A is formed into a split sleeve 40A as shown in Fig. 4B by cutting the annular end portions 35 and 36 at the respective ends to open one end of each of the penetrating grooves. Although this split sleeve 40A is similar in shape to the conventional one. However, the manufacturing method is quite different and so that an effect is provided that is easy to manufacture as compared to the conventional. As stated above, according to the present invention, since the penetrating groove of the split groove is formed during sintering, the manufacture is very easy as compared to the conventional. Further, a symmetrical form of a split sleeve can be made, which is accordingly excellent in alignment stability.

Claims: A split sleeve material (20) for forming a split sleeve adapted for fitting rod members therein from respective sides to thereby place said rod members at their tip surfaces in abutment against each other, wherein said split sleeve material (20) is generally in a cylindrical form with slits (21 - 24) extending in an axial direction and, at respective edges of the split sleeve material, with annular end portions (25, 26), in which the slits (21 - 24) do not extend, characterized in that the slits (21 - 24) are at opposite two locations spaced apart from each other by 90 degrees in the circumferential direction of the split sleeve material, that an annular portion (27) is provided at an axial central position of the split sleeve material, in which the slits do not extend, and that said split sleeve material consists of ceramic material. Split sleeve material according to claim 1, characterized in that the respective slits (21 - 24) extend to only one of said annular end portions (25, 26) at the respective edges. A split sleeve (20A) adapted for fitting rod members therein from respective sides to thereby place said rod members at their tip surfaces in abutment against each other, wherein said split sleeve (20A) is generally in a cylindrical form with slits (21 - 24) extending axially, characterized in that the slits (21 - 24) are at opposite two locations spaced apart from each other by 90 degrees in the circumferential direction of the split sleeve and extend to the edges of the sleeve, respectively, that an annular portion (27) is provided at an axial central position of the split sleeve, in which the slits do not extent, and that said split sleeve (20A) consists of ceramic material. A method of manufacturing a ceramic split sleeve (10A, 20A, 30A, 40A) adapted for fitting rod members therein from respective sides to thereby place said rod members at their tip surfaces in abutment against each other, characterized by forming at least one axially extending slit (11 - 14; 21 - 24; 31 - 32; 41) in said ceramic split sleeve (10A, 20A, 30A, 40A) with a cylindrical form during sintering, wherein the slit(s) (11 - 14; 21 - 24; 31 - 32; 41) do not extend to the edges of the split sleeve (10A, 20A, 30A, 40A) thereby leaving annular end portions (15, 16, 25, 26, 35, 36, 45, 46) of the split sleeve (10A, 20A, 30A, 40A), and by cutting away the annular end portions (15, 16, 25, 26, 35, 36, 45, 46) to open the end(s) of said slit(s) (11 - 14; 21 - 24; 31 - 32; 41).

Inventors: SHOUJI SETSUO, TSUNEMI MASAHIKO, SHOUJI, SETSUO, TSUNEMI, MASAHIKO, Shouji, Setsuo c/o Nasutekku Precision Co., Ltd., Tsunemi, Masahiko c/o Nasutekku Precision Co., Ltd
Applicants: SEIKO INSTR INC, SEIKO INSTRUMENTS INC.
Application year: 1998
Main classification: G02B6
IPC codes: F16B7, B65D59, G02B6, B21D53