Optical connector connecting apparatus with matching agent coating mechanism

Abstract: The present invention relates to an optical connector connecting apparatus and an optical connector connecting method in which an optical path switch excellent in reproducibility is effected by providing a matching agent coating mechanism provided in opposed relation to a connecting surface of a second optical connector. The inventive method includes the steps of moving an optical connector (2) to be abutted against a matching agent coating mechanism (20) and to apply the matching agent to a connecting surface of said optical connector and moving said optical connector to be connected to a fixed optical connector (3) to switch an optical path.

Description: The present invention relates to an optical connector connecting apparatus in accordance with the generic clauses of claims 1 and 3 which is excellent in reproducibility of a connection loss to be measured and is used for the connection of a multi-core optical connector having guide pins. Also, the invention relates to an optical connector connecting apparatus and an optical connector connecting method in which an optical path switching excellent in reproducibility is effected. Such an optical connector connecting apparatus is already disclosed in document WO-A-89 11 668. From Abstract of JP-A-63053503, there is already known a matching agent coating mechanism which teaches that a valve of a tank is driven by the end surface of the optical fiber itself. Conventionally, for measuring a connection loss of an optical connector, a pair of optical connectors 61 and 62 are guided through guide pins 64 as shown in Fig. 8, and are connected together. Then, as shown in Fig. 9, these connectors 61 and 62 thus connected are fixed together by a resilient clip 63. With this connection method, however, the fixing by the clip 63 must be done manually, so that much labor and time have been required, and another drawback is that the reproducibility of the measured value has been poor. Therefore, in order to overcome these drawbacks, connection apparatus have been proposed, using a general-purposed robot or an X-Y-Z stage moveable in three axes directions. The above-mentioned connecting apparatus using the robot or the X-Y-Z stage are of such a construction that optical connectors are connected by guide pins or a ferrule, and therefore the positioning of the guide pins must be done at a high precision on the order of not more than a micron. Therefore, much labor and time have been required for the positioning and the positioning control mechanism has become bulky, which has disadvantageously resulted in high costs. Further, the connecting surfaces of the optical connectors have fine depressions and projections, and it is possible that when these connectors are connected together, a gap on the order of 0.1 µm to several tens of µm will be formed between optical fiber cores of the connectors. Therefore, in order to prevent a deterioration of a connection loss and reflection characteristics which are caused by this gap, it s a common practice to fill this gap with a matching agent which matches the refractive index with the optical fiber core. The matching agent is manually applied to connecting surfaces, using an applicator 65 as shown in Fig. 10 or a toothpick. However, much labor and time have been required for such a manual application of the matching agent. Considering the foregoing, it is an object of the invention to provide an optical connector connecting apparatus which provides a good reproducibility of connection. This object is met by the characterizing features of claims 1 and 3. In order to achieve this object, there must be provided the type of construction in which the connection surfaces of a pair of opposed fixed and movable optical connectors to be connected together can be positively brought into intimate contact with each other using guide pins. Here, assuming that the connection surfaces are disposed perpendicular to the guide pins, there are two kinds of deviations of the guide pin from its mating fitting hole, that is, the deviation due to a parallel movement and the deviation due to the rotation or the bending. On the other hand, it is possible to support the movable optical connector by a mechanical element, such as a linear guide and a ball bearing, so that this connector can be stably connected to the fixed optical connector. However, if such a mechanism is used, the rigidity of the moving mechanism must be increased which would increase the force required for the driving. As a result, the apparatus would become bulky, and there is a possibility that the optical connector would be damaged unless the driving force is not suitably controlled. Therefore, it is necessary to provide an arrangement in which a displacement of several tens to several hundred µm is enabled by a following force of about several hundred grams. Further, for continuously checking a plurality of optical connectors, because of limited time it is difficult to precisely effect a position adjustment in accordance with the position of each fixed optical connector each time each fixed optical connector is checked. In addition, the amount of displacement (commonly called "offset") between the connected movable and fixed connectors varies depending on the combination. Fig. 1 is a perspective view showing a basic construction of an optical connector connecting apparatus not according to the present invention. Fig. 2 is a perspective view showing a basic construction of a first embodiment of the present invention; Fig. 3(a) is a vertical cross-sectional view showing a matching agent coating mechanism in the first embodiment; Fig. 3(b) is a view taken along the line E-E of Fig. 3(a); Fig. 4 is a procedure of an operation program of the connection of an optical connector in the embodiment of the invention; Fig. 5 is a diagram showing the difference in connection characteristics between the case where the matching agent is applied and the case where the matching agent is not applied; Fig. 6(a) is a vertical cross-sectional view of a matching agent coating mechanism in a second embodiment of the invention; Fig. 6(b) is a view taken along the line F-F of Fig. 6(a); Fig. 7 is a vertical cross-sectional view of a matching agent coating mechanism in a third embodiment of the invention; Fig. 8 is a perspective view of conventional optical connectors; Fig. 9 is a perspective view of the conventional optical connectors in its connected condition; and Fig. 10 is a perspective view showing the manner of coating a matching agent to the conventional optical connectors. Fig. 1 shows a basic construction of an optical connector connecting apparatus, wherein a plurality of fixed optical connectors (first optical connectors) 1 are mounted on fixed members 3 in a lined-up manner. A movable optical connector (second optical connector) 2 is mounted on an optical connector containing member 4 in opposed relation to the fixed optical connectors 1. The optical connector containing member 4 is fixedly secured through a beam (member) 6 to a support member 7 on an apparatus body 10. On the other hand, a support bed 12 is supported on a base 11 through a ball thread 13 and guide shafts 14 so as to move in an X-axis direction, the base 11 constituting part of the apparatus body 10. An X-axis motor 15 mounted on the base 11 rotates the ball thread 13 to move the support bed 12 in the X-axis direction. A moving plate 22 is supported on the support bed 12 through a ball thread 23 and guide shafts 24 so as to move in a Y-axis direction perpendicular to the X-axis direction. A Y-axis motor 25 mounted on the support bed 12 rotates the ball thread 23 to move the moving plate 22 in the Y-axis direction. Further, the above-mentioned support member 7 is supported on the moving plate 22 through a ball thread 33 and guide shafts 34 so as to move in a Z-axis direction perpendicular to the X-axis direction and the Y-axis direction. A Z-axis motor 35 mounted on the moving plate 22 rotates the ball thread 33 to move the support member 7 in the Z-axis direction. Namely, the apparatus is constituted by the support member 7, the base 11, the ball threads 13, 23, and 33, the guide shafts 14, 24, and 34, the motors 15, 25, and 35, and so on, the apparatus body 10 serving as the X-Y-Z stage movably supports the movable optical connector 2 through the beam 6. Next, the measurement of an optical attenuation of the fixed optical connector 1 by the optical connector connecting apparatus of the above construction will now be described. The motors 15, 25, and 35 on the apparatus body 10 are driven under a servo control to move the support member 7 to a prescribed address in the sequence of the X-axis, the Y-axis and the Z-axis. The movable optical connector 2 supported through beam 6, is positioned and connected to fixed optical connector 1 to measure the amount of optical attenuation. Continuously, a first embodiment of an optical connector connecting apparatus of the present invention is shown in Figs. 2 to 5. This embodiment will now be described with reference to these Figures. The optical connector connecting apparatus in this embodiment is the same in construction as that shown in Fig. 1, except for the provision of a matching agent coating mechanism 20. Therefore, explanation of the same portions as those in Fig. 1 will be omitted. In Fig. 2, the matching agent coating mechanism 20 is mounted on a base 11 in parallel relation to fixed members 3. Therefore the matching agent coating mechanism 20 faces the connecting surface of a movable optical connector 2. As shown in Figs. 3(a) and 3(b), in the matching agent coating mechanism 20, a pair of insertion holes 42 for respectively receiving guide pins 64 are formed in a lower portion of a case 40 which has at its support portion a tank 41 for holding the matching agent. An outlet 43 is also formed in this lower portion and is disposed between the insertion holes 42. The outlet 43 is connected to the tank 41 by an introduction passage 44, part of the introduction passage 44 intersecting the insertion holes 42. A pair of plunger-like pins 45 are provided in registry respectively with the insertion holes 42. A spring 46 wound around the pin 45 normally urges a generally conically-shaped head of the pin 45 toward the outlet 43 to close the introduction passage 44. Therefore, the pins 45 and the springs 46 constitute the opening and the closing means. The movable optical connector 2 approaches the case 40, and the guide pins 64 are inserted respectively into the insertion holes 42, so that the movable optical connector is abutted against the case 40. As a result, the pins 45 are retracted to open the introduction passage 44, and the matching agent is applied from the outlet 43 to be coated to the connecting surface 2a of the movable optical connector 2. Next, reference is now made to the switching of the optical paths of the fixed optical connectors by the optical connector connecting apparatus of the above construction. The apparatus body 10 is driven under a servo control of the motors 15, 25, and 35 to move the support member 7 in the sequence of the X-axis, the Y-axis, and the Z-axis. The movable optical connector 2 supported through the beam 6 is positioned and is connected to the fixed optical connector 1, thereby switching the optical path. At this time, the movable optical connector 2, instructed to be connected to a selected one of the fixed optical connectors 1, is first abutted against the matching agent coating mechanism 20 disposed in opposed relation to the movable optical connector 2, and the matching agent is coated to the end face of the movable optical connector 2. The movable optical connector 2 is abutted against the matching agent coating mechanism 20 either each time the instruction to connect the movable optical connector 2 to the fixed optical connector 1 is produced or each time per they are connected a predetermined number (N) of times. Fig. 4 shows one example of operation program with respect to an optical connector connecting method of the present invention, the operation of which will be described with reference to this Figure. As shown in Fig. 4, when the operation is started, the number of the fixed optical connector 1, as well as the connection is instructed in Step S1. In Step S2, a required number of connections is recalled whenever the power switch is turned on. In Step S3, the X-, Y-, and Z-direction addresses of the fixed optical connector 1 to be connected are called and the target position is confirmed. In Step S4, the present connection number is judged. If the connection number is not 0 or an integral multiple of N, the program shifts to Step S6. If the connection number is 0 or an integral multiple of N, the program shifts to Step S5. In Step S5, a match agent coating instruction is produced and the movable optical connector 2 is moved in the sequence of the X-axis, the Y-axis and the Z-axis, and the guide pins 64 are inserted into the insertion holes 42 in the matching agent coating mechanism 20, so that the matching agent is coated onto the connecting surface 2a of the movable optical connector 2. Then, the movable optical connector 2 is withdrawn and is returned to the initial position. In Step S6, an instruction for the connection to the fixed optical connector 1 is produced, the movable optical connector 2 is moved in the sequence of the X-axis, the Y-axis and the Z-axis relative to the fixed optical connector to be connected, and is connected thereto. Then, in this condition, signals are sent to effect various measurements. Instead of the sequential motion from X to Z in Step S5 or S6, a parallel motion of X and Y can be employed for the purpose of time-saving. In the latter case, Z motion should be independent to avoid damage to the guide pins and the connectors. In Step S7, the count of a connection number counter is an incremented one, and in Step S8, it is judged whether or not this connection number reaches the predetermined number. If this result is "NO", the program returns to Step S1, and if this result is "YES", the program is finished. Next, results of tests for confirming the effect of the above optical connector connecting method and apparatus are shown in Fig. 5, which will be explained with reference to this Figure. Referring to the conditions here, the case where the matching agent is not applied at all is condition A. The case where the matching agent is applied each time the connection is effected is condition B. The case where the matching agent is applied each time the connection is effected 10 times is condition C. The case where the matching agent is applied each time the connection is effected 50 times is condition D. In each case, the connection loss of the optical connector, as well as reflection characteristics thereof, was measured. As a result, as shown in Fig. 5, it has been confirmed that the characteristics in conditions B and C are excellent. Next, a second embodiment of an optical connector connecting apparatus of the present invention is shown in Figs. 2, 4, 5, 6(a), and 6(b). This embodiment will now be described with reference to these Figures. Those portions identical to those of the first embodiment will be designated by identical reference numerals, respectively, and a repetition of the explanation is omitted. As shown in Figs. 6(a) and 6(b), a cylinder 57, having a piston 55 urged left by a spring 56, is formed in a lower portion of a case 50 of a matching agent coating mechanism 20 which has at its upper portion a tank 51 for holding a matching agent. The tank 51 is communicated via a valve 58 with the space in the cylinder 57, and the valve 58 is opened and closed by the reciprocal movement of the piston 55 in the right and left directions. There is provided an introduction passage 54 extending from the space of the cylinder 57 to an opening 53 disposed midway between insertion holes 52, and the matching agent is forced from the space of the cylinder 57 into the introduction passage 54 by the reciprocal movement of the piston 55, so that the matching agent is discharged from the opening 53. Therefore, the movable optical connector 2 approaches the case 50, and the guide pins 64 are inserted respectively into the insertion holes 52, so that the movable optical connector 2 is abutted against the case 50. As a result, the piston 55 is moved right, so that the matching agent flows out of the case 50 to deposit on the connecting surface 2a of the movable optical connector 2. When the guide pins 64 are withdrawn from the insertion holes 52, the spring 56 is urged left, and therefore the piston 55 is moved. At the same time the valve 58 is opened to replenish the cylinder 57 with the matching agent. Next, a third embodiment of an optical connector connecting apparatus of the present invention is shown in Figs. 2, 4, 5, and 7, which will now be described with reference to these figures. Those portions identical to those of the first embodiment will be designated by identical reference numerals, respectively, and a repetition of the explanation is omitted. As shown in Fig. 7, a swelling cloth 73 is supported on an outer peripheral surface of a tank 71 of a matching agent coating mechanism 20 which holds a matching agent. The lower end portion of the swelling cloth 73 is dipped in the matching agent. A pair of insertion holes 72 for respectively receiving the guide pins 64 are formed in the upper portion of the tank 71 in such a manner that the swelling cloth 73 is disposed between these insertion holes 72. Therefore, when the movable optical connector 2 is abutted against the swelling cloth 73 with the guide pins 64 inserted in the insertion holes 72, the matching agent impregnated in the swelling cloth 73 by a surface tension is applied to the connecting surface of the movable optical connector 2. In the above description, although the guide pins 64 of the movable optical connector 2 push the plunger-like pins 45 or the piston 55, the part for pushing these pins 45 and piston 55 are not limited to the guide pins 64, and any part connected to the movable optical connector 2 may be used for this purpose. In the optical connector connecting apparatus according to the present invention, the matching agent is provided between the connecting surfaces when the optical connectors are connected together, and therefore the connection loss amount is reduced, and the fine positioning mechanism which makes the apparatus construction complicated becomes unnecessary.

Claims: An optical connector connecting apparatus (10) comprising: a plurality of first optical connectors (1) fixedly supported on a body (3) of said apparatus; a second optical connector (2) movably supported on the apparatus body (4,7), said second optical connector (2) being moved to be connected to any one of said first optical connectors (1) and having at least one guide pin (64) for positioning said second connector; wherein an optical path is switched by a connection of said optical connectors (1,2), characterized by a matching agent coating mechanism (20), provided in opposed relation to a connecting surface (2a) of said second optical connector (2), for applying a matching agent which improves optical connection characteristics to said second optical connector (2); wherein said matching agent coating mechanism includes an insertion hole (42), a tank (41) for holding the matching agent, an introduction passage (44,43) for feeding the matching agent from said tank (41), a valve provided in said introduction passage (44,43) for opening and closing said introduction passage (44,43), and an opening and closing member (45,44,50,51) which opens said valve upon insertion of said guide pin (64) into the insertion hole (42). An optical connector connecting apparatus (10) according to claim 1 characterized in that said matching agent coating mechanism further includes a cylinder (57) for holding the matching agent therein; said opening and closing member further includes an insertion hole (53) for receiving said guide pin, said insertion hole (53) being communicated with said cylinder; and a piston (55) provided within said cylinder (50), said piston (55) being urged upon insertion of said guide pin (64), so that said piston (55) is moved within said cylinder to feed the matching agent. An optical connector connecting apparatus (10) comprising: a plurality of first optical connectors (1) fixedly supported on a body (3) of said apparatus; a second optical connector (2) movably supported on the apparatus body (4,7), said second optical connector (2) being moved to be connected to any one of said first optical connectors (1) and having at least one guide pin (64) for positioning said second connector; wherein an optical path is switched by a connection of said optical connectors (1,2), characterized by a matching agent coating mechanism (20), provided in opposed relation to a connecting surface (2a) of said second optical connector (2), for applying a matching agent which improves optical connection characteristics to said second optical connector (2); wherein said matching agent coating mechanism includes a tank (71) for holding the matching agent therein, and a swelling cloth (73) having its lower end portion dipped in the matching agent, said swelling cloth (73) being disposed in opposed relation to the connecting surface (2a) of said second optical connector (2), and a pair of insertion holes for respectively receiving guide pins (64) which position said second optical connector (2).

Inventors: ARIMOTO KAZUHIKO, ASANO YASUO, KOMIYA TAKEO, OSAKA KEIJI, SANO TOMOMI, TAKASUGI HIDETOSHI, ARIMOTO, KAZUHIKO, ASANO, YASUO, KOMIYA, TAKEO, OSAKA, KEIJI, SANO, TOMOMI, TAKASUGI, HIDETOSHI, ARIMOTO, KAZUHIKO, C/O SUMIDEN OPCOM, LTD., ASANO, YASUO, C/O YOKOHAMA WORKS OF SUMITOMO, KOMIYA, TAKEO, C/O YOKOHAMA WORKS OF SUMITOMO, OSAKA, KEIJI, C/O YOKOHAMA WORKS OF SUMITOMO, SANO, TOMOMI, C/O YOKOHAMA WORKS OF SUMITOMO, TAKASUGI, HIDETOSHI, C/O NIPPON TELEGRAPH AND
Applicants: NIPPON TELEGRAPH & TELEPHONE, SUMIDEN OPCOM LTD, SUMITOMO ELECTRIC INDUSTRIES, NIPPON TELEGRAPH AND TELEPHONE CORPORATION, SUMIDEN OPCOM, LTD., SUMITOMO ELECTRIC INDUSTRIES, LTD.
Application year: 1992
Main classification: G02B26
IPC codes: G02B6