Patent Application
20050260932
The present invention relates to the field of polishing of connectors and fiber stubs. More particularly the present invention relates to a polishing fixture and a method for simultaneous loading, reloading and polishing a plurality of fiber stubs or optical connectors.
With the growth of optical communication networks there is a growing need for altering the network configuration, connecting to it new nodes and devices, disconnecting old devices and maintaining the network. These connections are easy and convenient to make with the help of an optical connector, which is a demountable device for attaching an optical fiber to another optical fiber, or to an active or passive device.
The losses of the optical signal power at each connection depend on the geometry of the connector end-face, matching surfaces geometry, surface quality and other parameters. In order to reduce optical signal power coupling losses, the end-face of an optical connector, typically comprising an optical fiber inserted into a ferrule, is polished. The polished end-face surface may be flat, inclined or have a radius in accordance with the type of connection desired. The term “ferrule” as used in the text of the disclosure means an optical connector the polished end-face of which comprises a fiber inserted into a ferrule. The term “ferrule” as used herein includes optical connector having a ferrule and fiber stubs.
Polishing of an optical connector on a piece-by-piece basis is not practical due to the nature of the process as well as the mix of the quantities and the structure of the connectors to be polished. This is the main reason why optical connectors are typically polished in batches. In the context of the present invention, batch means a plurality of connectors polished or processed simultaneously. For polishing, a batch of optical connectors is loaded in a so-called polishing fixture. U.S. Pat. No. 5,961,374 to Minami et al. discloses some such polishing fixtures.
U.S. Pat. Nos. 5,947,797, 6,183,343, and 6,190,239 all to Buzzetti disclose polishing fixture (
Loading of fiber stubs in a polishing fixture is even more complicated. The term “fiber stub” as used in the text of the disclosure means a ferrule with inserted in it a relatively short section of optical fiber. Fiber stubs 86 typically have two ends, both of which must have polished end-face surfaces. One of the ends is polished first. Following this, the partially polished stubs are removed from the polishing fixture, which as shown in
Polishing fixtures are not versatile enough to adopt the variety of existing connectors. In practice each connector type, such as FC, SC, ST and others require a dedicated polishing fixture. This forces the supplier of polished optical fiber cables to stock a variety of polishing fixtures. Polishing fixtures are expensive and the stock cost increases the cost of polished optical fiber cables and connectors.
Certain cables have a multi fiber connector on one of its ends. The other end of the same optical fiber cable may be split into a number of simplex or duplex connectors. Each of the connectors may be of a different type. Existing polishing fixtures do not support loading and polishing of different types of connectors on the same fixture. Polishing of such cables requires their loading in a suitable fixture for holding only one of the connector types with subsequent reloading in a polishing fixture that supports a different type of connector used in a particular cable. This naturally extends the cable production time and increases the cost. Furthermore, different connectors of the same cable are polished at different conditions. This results in differences in the quality of the polished connectors, increased spoilage and additional polishing costs.
Polishing is usually conducted in the presence of water or specially formulated water-based or other fluid-based coolant or lubricant. Water (or other coolant) plays an important role in the polishing process. Water cools the part being polished, removes particles, contamination and other debris that might otherwise destroy a polished connector end-face made up of the fiber and ferrule surface. The supply rate of water is controlled to maintain proper concentration of polishing slurry, and the water provides lubrication between polished parts and polishing substrate. Water (and sometimes other fluids) is usually delivered to the polishing member and to the actual polishing area, typically to the periphery of the polishing fixture by a fluid delivery system separate from the polishing fixture. International Application PCT/IL03/00733 to the present assignee discloses a polishing fixture that ensures proper water (coolant) delivery to each and every polished connector mounted on the polishing fixture. Despite the advantages of the fixture described therein, the connectors to be polished are still loaded one-by-one. Water is conducted through special water conducting tubing distributed across the top of the fixture. The tubing occupies some of the space required for more convenient connector loading activities.
There is no polishing fixture known to the inventors of the present invention enabling simultaneous loading (mounting) of a plurality (batch) of connectors to be polished. There is no polishing fixture known to the inventors of the present invention enabling simultaneous polishing of different type of connectors loaded in the same polishing fixture.
Fibers protruding from connectors or fiber stubs loaded in a polishing fixture for polishing generally have to be cleaved or trimmed. The cleaving procedure is supposed to make fibers protruding from the connectors of equal length and ensure uniform pressure on each connector polished. However, since ferrules and connector housings have certain tolerances the ferrules protrusion with respect to the housing of the connectors is not equal. Accordingly, the pressure developed by the polishing process is different for each connector. There are no polishing fixture loading methods known to the inventors of the present invention that ensure equal protrusion of connectors or their ferrules loaded in a polishing fixture.
It would be desirable to have a polishing fixture enabling simultaneous loading of a plurality (batch) of connectors or fiber stubs to be polished. It would be also desirable to have a polishing fixture, which would ensure equal protrusion of the loaded connectors or fiber stubs to be polished.
The industry is in need of a polishing fixture that would allow loading of a plurality of different connector types in the same polishing fixture and their subsequent polishing in the same polishing fixture.
Polishing fixtures having water-conducting tubing within the body of the fixture that would not occupy the space across the top of the fixture and would thereby facilitate more convenient connector loading activities would better serve the polishing industry needs.
The industry needs a polishing fixture and a polishing fixture loading method that would ensure equal protrusion of connectors or their ferrules loaded in a polishing fixture and accordingly apply equal pressure developed by the polishing process to each connector.
The present invention is a polishing fixture enabling simultaneous loading and simultaneous polishing of a plurality (batch) of connectors or fiber stubs to be polished.
According to the teachings of the present invention there is provided, a fixture for simultaneously clamping a plurality of optical fiber ferrules or fiber stubs for polishing. The fixture optionally and preferably includes a plate assembly having an upper surface, a lower surface and a plurality of ferrule-receiving bores disposed across the upper surface and extending from the upper surface to the lower surface, each ferrule-receiving bore for receiving a ferrule. The fixture further includes a plurality of ferrule gripper arrangements. Each arrangement is associated with one of the ferrule-receiving bores, each of the ferrule gripper arrangements being selectively deployable between a released state for insertion of a ferrule into the ferrule-receiving bore and a gripping state. In the gripping state the gripper arrangement clamps a ferrule within the ferrule-receiving bore; and a locking mechanism associated with at least a group of the plurality of ferrule gripper arrangements. The locking mechanism is configured to deploy the group of ferrule gripper arrangements substantially simultaneously from the released state to the gripping state so as to clamp substantially simultaneously a plurality of optical fiber ferrules located within a corresponding group of the ferrule-receiving bores.
According to a further teaching of the present invention, the plate assembly includes an upper plate providing the upper surface and a lower plate providing the lower surface, and the plurality of ferrule gripper arrangements that are substantially enclosed between the upper and lower plates.
According to still a further teaching of the present invention, the locking mechanism includes a gripper carrier and an actuator mechanism for displacing the gripper carrier, and wherein the group of ferrule gripper arrangements is implemented as resilient elements mechanically interconnected to be displaced together with the gripper carrier.
According to an additional feature of the present invention, each of the ferrule-receiving bores has an internal diameter of no more than about 3 millimeters.
In agreement with a further teaching of the present invention, the fixture preferably includes a loading plate that assists in loading of a plurality of connectors or fiber stubs in the fixture. The loading plate has a loading calibration surface having a plurality of alignment openings. Each opening is configured to define a degree of projection (protrusion) of a ferrule or a fiber stub from a corresponding one of the ferrule-receiving bores. The loading plate and the plate assembly featuring inter-engaging alignment features configured to align the loading plate with the lower surface such that one of the alignment openings is aligned with each of the ferrule-receiving bores.
According to an additional teaching of the present invention, the fixture preferably further includes a fiber-stub insertion tool including at least one spring-loaded pin configured for pressing a fiber stub to a fully inserted position within one of the ferrule-receiving bores.
In agreement with an additional teaching of the present invention, the fixture preferably further includes a fiber-stub inversion assembly that assists in the fiber-stubs loading for polishing of one of the end-faces and automatic inversion of the stubs in the same fixture for polishing the second end-face.
According to a further teaching of the present invention, the fiber-stub inversion assembly preferably includes a storage plate having a plurality of fiber-stub-receiving openings disposed on a surface of the storage plate in a pattern similar to a pattern of the ferrule-receiving bores and a support mechanism configured to support the storage plate. The support mechanism optionally and preferably includes an inversion mechanism for selectively allowing inversion of the storage plate.
According to a further teaching of the present invention, the fiber-stub inversion assembly and the plate assembly of the fixture preferably include inter-engaging alignment features configured to align the storage plate with each of the lower surface and the upper surface such that one of the fiber-stub-receiving openings is aligned with each of the ferrule-receiving bores.
According to an additional teaching of the present invention, the fixture may further include a mounting arm projecting from the upper surface of the plate assembly, and the storage plate is formed with an opening configured to accommodate the mounting arm when the storage plate is aligned with the upper surface.
According to a further teaching of the present invention, the fixture preferably includes a plurality of fiber-stub-receiving openings formed in a first surface of the storage plate. The storage plate further includes a second surface being a loading calibration surface formed with a plurality of alignment openings each configured to define a degree of projection of a ferrule from a corresponding one of the ferrule-receiving bores. Both surfaces of the storage plate and the plate assembly preferably feature inter-engaging alignment features configured to align the storage plate with the surfaces of plate assembly such that one of the alignment openings is aligned with each of the ferrule-receiving bores.
The present invention further provides a method for simultaneously clamping a plurality of optical fiber ferrules or fiber stubs for polishing. The method optionally and preferably includes steps of: providing a fixture including a plate assembly having a plurality of ferrule-receiving bores, a plurality of ferrule gripper arrangements, each associated with one of the ferrule-receiving bores, and a locking mechanism associated with at least a group of the plurality of ferrule gripper arrangements. Deploying a plurality of optical fiber ferrules within the ferrule-receiving bores and operating the locking mechanism to cause at least the group of ferrule gripper arrangements to substantially simultaneously clamp a group of the ferrules within a corresponding group of the ferrule-receiving bores.
According to the method of the present invention, the step of providing the plate assembly includes an assembly having an upper plate providing an upper surface and a lower plate providing a lower surface, and the plurality of ferrule gripper arrangements that are substantially enclosed between the upper and lower plates. The locking mechanism includes a gripper carrier and the group of ferrule gripper arrangements are implemented as resilient elements mechanically interconnected with the gripper carrier, and the step of operating the locking mechanism is being performed by operating an actuator mechanism to displace the gripper carrier and hence the resilient elements.
According to a further feature of the method of the present invention, each of the ferrule-receiving bores has an internal diameter of no more than about 3 millimeters.
According to an additional feature of the method of the present invention, the step of bringing the loading plate calibration surface into juxtaposition with the plate assembly so as to define a desired degree of projection of the ferrules from the ferrule-receiving bores precedes the step of deploying the ferrules within the ferrule receiving bores. The step of the calibration surface of the loading plate and the plate assembly separation is subsequent to the step of operating of the locking mechanism.
According to a further feature of the method of the present invention, the loading plate calibration surface features a plurality of alignment openings for cooperation with end portions of the ferrules, the bringing into juxtaposition being performed to align the alignment openings with corresponding of the ferrule-receiving bores.
In agreement with the method of the present invention, preferably a step of employing at least one spring-loaded pin for pressing a fiber stub to a fully inserted position within one of the ferrule-receiving bores is used.
The method of the present invention preferably further includes the step of polishing a first end of a plurality of fiber-stubs while the fiber stubs are clamped in the fixture in a first orientation. The step of polishing is followed by the step of off-loading the plurality of fiber-stubs substantially simultaneously into fiber-stub-receiving openings of a storage plate and the step of reloading the plurality of fiber-stubs substantially simultaneously into the ferrule-receiving bores of the plate assembly. The step of reloading places the fiber stubs in a second orientation inverted relative to the first orientation and the step of operating the locking mechanism is performed so as to substantially simultaneously clamp the fiber-stubs within the ferrule-receiving bores.
The present invention further provides a method of polishing of both ends of a plurality of optical fiber stubs. The method preferably includes the steps of providing a fixture including a plate assembly having an upper surface, a lower surface and a plurality of ferrule-receiving bores extending from the upper surface to the lower surface, each ferrule-receiving bore for receiving a fiber stub, and a plurality of ferrule gripper arrangements, each associated with one of the ferrule-receiving bores. Providing a fiber-stub inversion assembly including a storage plate, a plurality of fiber-stub-receiving openings disposed on a surface of the storage plate in a pattern similar to a pattern of the ferrule-receiving bores, and a support mechanism configured to support the storage plate, the support mechanism including an inversion mechanism for selectively allowing inversion of the storage plate. Deploying and clamping a plurality of optical fiber stubs within the ferrule-receiving bores with a first end of each of the fiber stubs projecting from the lower surface. Polishing the first ends of the fiber stubs and bringing the plate assembly into juxtaposition with the storage plate such that the ferrule-receiving bores are aligned with the fiber-stub-receiving openings. Releasing and off-loading the fiber stubs from the ferrule-receiving bores into the fiber-stub-receiving openings. Inverting the plate assembly and bringing the plate assembly into inverted juxtaposition with the storage plate such that the ferrule-receiving bores are aligned with the fiber-stub-receiving openings. Re-loading the fiber stubs from the fiber-stub-receiving openings into the ferrule-receiving bores and clamping the fiber stubs within the ferrule-receiving bores with a second end of each of the fiber stubs projecting from the lower surface and polishing the second ends of the fiber stubs.
In accordance with the method of polishing of the present invention, the step of re-loading includes inverting the plate assembly together with the storage plate. And the steps of the deploying and the re-loading both include bringing the plate assembly into juxtaposition with the loading calibration surface, the calibration surface having a plurality of alignment openings each configured to define a degree of projection of the fiber stub from a corresponding one of the ferrule-receiving bores. The loading calibration surface is implemented as one of the surfaces of the storage plate.
According to the method of polishing of the present invention, the steps of deploying and clamping and the re-loading and clamping include operating a locking mechanism to simultaneously operate a plurality of the ferrule gripper arrangements, and at least the step of deploying includes employing a fiber-stubs insertion tool. The insertion tool includes at least one spring-loaded pin for pressing a fiber stub to a fully inserted position within one of the ferrule-receiving bores.
The present invention provides a polishing fixture for simultaneously clamping (loading) and polishing of a plurality of connector end faces wherein the connectors are held in the polishing fixture by applying pressure to their ferrules. Since ferrules of different types of connectors have similar size loading of different types of connectors on the same polishing fixture is enabled.
Another feature of the present invention is a method of polishing of end faces of a plurality of connectors wherein the connectors are held in the polishing fixture by applying pressure to their ferrules.
The present invention significantly reduces the time required for loading a polishing fixture with a plurality of connectors or ferrules to be polished and accordingly reduces the polishing costs.
Connectors or fiber stubs loaded in a polishing fixture for polishing have a uniform projection (protrusion) length that does not depend on the ferrule within connector housing position. The polishing force is equally distributed between the connectors or fiber stubs further improving polishing quality and yield.
Polishing is a process where abrasive materials and polishing debris are usually accumulated in the polishing fixture. The present invention supports easy polishing fixture assembly and dismantling and enables easy polishing fixture cleaning.
The present invention also supports reloading of the polishing fixture with a plurality of connectors or ferrules to be polished and further reduces the polishing costs.
The invention is herein described, by way of non-limiting examples only, with reference to the accompanying drawings, wherein:
FIGS. 16 is a magnified schematic cross section of
FIGS. 17 schematically illustrates another step of the method of polishing both ends of a plurality of optical fiber stubs according to the present invention;
FIGS. 18 is a magnified schematic cross section of
FIGS. 20 is a magnified schematic cross section of
FIGS. 21 schematically illustrates an additional step of the method of polishing both ends of a plurality of optical fiber stubs according to the present invention;
The principles and execution of a method according to the present invention, and the operation and properties of the fixture, loading plate, fiber stub insertion tool and fiber stub inversion assembly described thereby may be understood with reference to the drawings, wherein like reference numerals denote like elements through the several views and the accompanying description of non-limiting, exemplary embodiments.
Reference is now made to
Plate assembly 106 includes an upper plate 102 providing upper surface 130 and a lower plate 108 providing lower surface 132, and plurality of ferrule gripper arrangements 142 are substantially enclosed between upper 102 and lower 108 plates.
Locking mechanism includes a gripper carrier 126 and an actuator mechanism 128 for displacing gripper carrier 126. Locking mechanism may be any mechanism that ensures rapid deployment of the group of ferrule gripper arrangements 142 from the released state to the gripping state and it may be a quarter turn screw, or a cam, or magnetic plates, or other similar devices. Each group of ferrule gripper arrangements 126 is implemented as resilient elements 124 and 140 mechanically interconnected (
Fixture 100 may optionally include coolant conducting channels 114 (
According to the teaching of the present invention, fixture 100 preferably includes a loading plate 150 that assists in loading of a plurality of connectors or fiber stubs in fixture 100. Loading plate 150 has a loading calibration surface 154 having a plurality of alignment openings 156 (
Shown in
Loading plate 150 may be of a stand-alone construction or alternatively it may have leg type inserts 164 to be positioned on a worktable where the loading of polishing fixture 100 takes place.
Fixture 100 preferably further includes a fiber-stub insertion tool 166 shown in
Fixture 100 preferably further includes a fiber-stub inversion assembly 200 shown in
Storage plate 202 of fiber-stub inversion assembly 200 and plate assembly 106 of fixture 100 preferable include inter-engaging alignment features 212, 214 and 136. Inter-engaging alignment features 212, 214 and 136 are configured to align surfaces 220 and 226 of storage plate 202 with each of lower surface 132 and upper surface 130 such that one of fiber-stub-receiving openings 208 or one of alignment openings 156 is aligned with each of ferrule-receiving bores 104.
Inversion assembly 200 optionally may have a number of screws 218 or other fast locking mechanism for locking in a fixed position juxtaposed with it fixture 100. Such locking mechanism enables more convenient operator work.
Fixture 100 may preferably further include a mounting arm 134 (
The present invention further provides a method for simultaneously clamping a plurality of optical fiber ferrules or fiber stubs for polishing. The method optionally and preferably includes steps of: providing a fixture 100 including a plate assembly 106 having a plurality of ferrule-receiving bores 104, a plurality of ferrule gripper arrangements 126, each associated with one of the ferrule-receiving bores 104, and a locking mechanism associated with at least a group of the plurality of ferrule gripper arrangements 142. Providing a loading plate 150 having a loading calibration surface 154 and a fiber-stub insertion tool 166 (Step 320).
Plate assembly 106 (
Bringing loading calibration surface 154 of loading plate 150 (Step 322) into juxtaposition with plate assembly 106 to define a desired degree of projection (protrusion) of ferrules 138 from ferrule-receiving bores 104. Operating the locking mechanism for deploying a group of ferrule gripper arrangements 126 to the released state (Step 324) and deploying a plurality of optical fiber ferrules 138 within ferrule-receiving bores 104 (Step 326). Employing spring-loaded pins 178 of fiber-stub insertion tool 166 (Step 328) for pressing fiber stubs 138 to a fully inserted position within ferrule-receiving bores 104. Operating the locking mechanism (Step 330) to cause at least a group of ferrule gripper arrangements 126 to substantially simultaneously clamp a group of ferrules 138 within a corresponding group of ferrule-receiving bores 104.
The method for simultaneously clamping a plurality of optical fiber ferrules or fiber stubs for polishing preferably further includes step of polishing (Step 332) a first end 144 (
The present invention further provides a method of polishing of both ends of a plurality of optical fiber stubs. The method illustrated in
According to the method of polishing of the present invention, step of re-loading (Step 364) includes inverting plate assembly 106 together with storage plate 202 having a plurality of fiber-stub-receiving openings 208 disposed on a surface 220 and extending from surface 220 to surface 226. Fiber-stub-receiving openings 208 disposed on a surface 220 feature alignment openings similar to alignment openings 156 (
The steps of deploying (Step 352) and clamping (Step 366) and the steps of re-loading (Step 364) and clamping (Step 366) include operating a locking mechanism to simultaneously operate a plurality of ferrule gripper arrangements 142, and at least step of deploying (Step 352) includes employing an insertion tool 166. Insertion tool 166 includes at least one spring-loaded pin 178 for pressing a fiber stub 138 to a fully inserted position within one of ferrule-receiving bores 104.
Polishing fixture 100 with a plurality of optical connectors (not shown) is attached by means of projection 134 (See
The polishing process begins with coupling of polishing fixture 100 with a plurality of ferrules 138 (optical connectors of fiber stubs) by means of projection 134 (See
The present invention provides a polishing fixture for simultaneously clamping (loading) and polishing of a plurality (batch) of connector end faces wherein the connectors are hold in the polishing fixture by applying pressure to their ferrules.
The present invention additionally provides a method of simultaneous clamping (loading) and off-loading of a polishing fixture by a plurality of connectors and fiber stubs end faces of which have to be polished.
Another feature of the present invention is a method of polishing of end faces of a plurality (batch) of connectors wherein the connectors are hold in the polishing fixture by applying pressure to their ferrules.
The present invention significantly reduces the time required for loading a polishing fixture with a plurality of connectors or ferrules to be polished and accordingly reduces the polishing costs.
Connectors or fiber-stubs loaded in a polishing fixture for polishing have a uniform protrusion length. The polishing force is equally distributed between the connectors or fiber stubs further improving polishing quality and yield.
The present invention also supports fast re-loading of the polishing fixture with a plurality of connectors or fiber stubs to be polished and further reduces the polishing costs. In course of the reloading ferrules are automatically inverted and their position reducing the possibility of contamination or scratches of already polished end faces.
While the exemplary embodiments of the present invention have been illustrated and described, it will be appreciated that various changes can be made therein without affecting the spirit and scope of the invention.
