1. Field of the Invention
The present invention is directed to an apparatus and method for polishing an optical fiber, in particular, an optical fiber terminated and polished in the field.
2. Background
In the area of optical telecommunication networks, fiber optic connectors are one of the primary ways to connect two or more optical fibers. There are several classes of optical fiber connectors including adhesive ferruled connectors, in which the fiber tip is held in a substantially fixed position relative to the tip of the ferrule by adhesively securing the fiber within the bore of the ferrule. Another class of connectors includes non-ferrule connectors, which rely on the buckling of a length of fiber to create contact force. Another class of connectors includes remote grip (ferruled) connectors, where the fiber is secured at some distance away from the terminal end or tip of the fiber.
When installing a remote grip connector in the field, one current practice uses a coplanar/flush polish. In remote grip connectors, as with other connector types, low optical losses and minimal reflections are achieved when the terminal ends of at least two optical fibers make secure physical contact. However, any differences in the coefficient of expansion between the fiber and the ferrule assembly may result in a non-contacting fiber tip when the temperature is raised, or lowered. The resulting gap can lead to significant reflection. A conventional remote grip connector is described in U.S. Pat. No. 5,408,558.
Another current practice involves a technician performing a field polish to create a fiber terminal end which protrudes beyond the ferrule tip. This method of polishing remote grip connectors produces a range of protrusions that provide a secure physical contact while avoiding excess force on the fiber tips. This method, when carefully followed, allows sufficient physical contact of the at least two fiber terminal end faces at temperatures for indoor applications (0° C. to 60° C.). However, the conventionally polished field-terminated remote grip connector may not be recommended for outdoor use, which has more stringent temperature requirements (−40° C. to 80° C.). Factors leading to unacceptable optical loss may result from the intrinsic variability of the field polishing process, craftsman error, over polishing (e.g. using too much force or too many strokes and coarse, clogged or contaminated abrasive) or substitution of a different type of abrasive.
The following references describe conventional devices for polishing optical fibers: US 2003/0139118 A1; US 2004/0086251 A1; US 2008/0119111 A1; U.S. Pat. No. 3,975,865; U.S. Pat. No. 4,178,722; U.S. Pat. No. 4,291,502; U.S. Pat. No. 4,979,334; U.S. Pat. No. 5,007,209; U.S. Pat. No. 5,185,966; U.S. Pat. No. 5,216,846; U.S. Pat. No. 5,349,784; and U.S. Pat. No. 5,351,445.
According to an exemplary aspect of the present invention, a hand-held polishing apparatus is provided for polishing an optical fiber connector. The optical fiber connector includes a connector housing and a ferrule. The optical connector is mounted on the end of an optical fiber. The polishing apparatus includes a connector mount to receive and hold the optical connector to position the end face of the ferrule adjacent to a polishing media. The polishing apparatus includes a housing having an upper portion and a base portion, a drive assembly and a lubricant dispensing system. The drive assembly controls orbital movement of the optical connector and linear movement of the polishing media through the polishing device, and the lubricant dispensing system supplies a lubricant from an internal reservoir disposed within the housing to the polishing media near the end face of the ferrule of the optical connector.
In another exemplary aspect of the present invention, a hand-held polishing apparatus is provided for polishing an optical fiber connector which uses a tape-style polishing media. The optical fiber connector, which is mounted on an end of an optical fiber, includes a connector housing and a ferrule. The polishing apparatus includes a connector mount to receive and hold the optical connector to position the end face of the ferrule adjacent to the tape-style polishing media. The polishing apparatus includes a housing having an upper portion and a base portion and a drive assembly. The drive assembly controls orbital movement of the optical connector and linear movement of the tape-style polishing media through the polishing device.
According to another exemplary aspect of the present invention, a method of polishing an optical connector comprises providing an optical fiber having a stripped terminal end. The optical fiber is inserted through a connector body and a ferrule. A protrusion of the fiber tip from an end face of the ferrule is set. The optical fiber is secured in the optical connector. The optical connector is mounted in a connector mount of a polishing apparatus. The polishing apparatus includes a housing having an upper portion and a base portion, a drive assembly and a lubricant dispensing system. The method further includes dispensing a lubricant using the lubricant dispensing system. The lubricant is supplied from an internal reservoir disposed within the housing to the polishing media near the end face of the ferrule of the optical connector. Activation of the drive assembly initiates the polishing of the fiber tip protruding from the end face of the ferrule. The drive assembly controls orbital movement of the optical connector and linear movement of the polishing media through the polishing device causing the protruding fiber tip to travel a predetermined distance against the polishing media. Further, the exposed fiber can be cleaved either prior to setting the protrusion of the fiber from the end face of the ferrule or after the fiber is secured in the optical connector.
The present invention will be further described with reference to the accompanying drawings, wherein:
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “forward,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.
The present invention is directed to an apparatus and method for polishing an optical fiber terminated in an optical fiber connector. As described herein, a simple method of field polishing and assembly of an optical connector can provide consistent, repeatable results and can substantially reduce the craft sensitivity, when contrasted with traditional field polishing methods, and can reduce connector installation costs. In a preferred aspect, the polishing apparatus can be a lightweight, hand-held, mechanical device that is operated manually in the field.
The upper and lower portions of the housing can be joined together by known mechanical means such as by mechanical fasteners, latches or clips. In the exemplary embodiment shown in
The polisher housing 110 can be constructed from a rigid material, such as a metal or a molded polymer (e.g., a glass or mineral filled plastic). In a preferred aspect, apparatus 100 is lightweight (e.g., less than 1 lbs., more preferably less than 0.5 lbs.) and can be held securely in one hand during operation.
In use, a connector 10 is inserted into the connector mount 120 of the polishing apparatus. A lubricant supplied by the lubricant dispensing system 130 from an internal reservoir 132 can be applied to the polishing media 142 near the connector tip. The drive assembly 150 can be actuated to create the polishing motion used to polish the end face of the fiber held by the optical connector 10. The pattern 199 of the polishing motion is one in which the optical connector moves in a circular orbit, represented by arrow 199a, while the polishing media 142 moves in a generally linear movement, represented by arrow 199b, and is shown in
Referring to
In an exemplary embodiment, the power to drive the polishing mechanism can be provided by pulling on a string 151 attached to drive assembly 150. String 151 is wrapped around a spool 152 within the drive assembly which is attached to a first one way drive plate 153. A flat wound spring, not shown, retracts the string as the user releases the tension on it causing it to wrap back around the spool in preparation for the next polishing operation.
When assembled, wedge shaped projections 153a (
Drive shaft 155 passes through support wall 112c where it connects to the center gear 156c in a three gear set 156. The three gear set 156 includes the center gear 156c, a first side gear 156a positioned on one side of the center gear and a second side gear 156b located on a second side of the center gear opposite the first gear. In an exemplary embodiment, the first and second side gears 156a, 156b are the same size and turn in unison when the center gear 156c rotates. Each of the first and second side gears has an off-center stub 157a, 157b projecting from a lower side gear surface as shown in
The motion of the connector holding plate 160 activates the media dispenser 140 to mete out the polishing media 142 from a storage roll 142a in a controlled manner. Media dispenser 140 may be disposed within base portion 114 of the polisher housing 110 and dispenses polishing media 142 as shown in
Referring to
The roll of polishing media can be replaced by separating the upper portion 112 and the base portion 114 of the housing 110. The spent disposable container can be removed from the media dispenser 140 and replaced with a new one including a roll 142a of the appropriate polishing media 142. A length of the polishing media 142 can be pulled out of the new container and routed over spring loaded pressure plate assembly 149 before the upper portion 112 and the base portion 114 of the housing 110 are reassembled.
Connector plate 160 interacts with tabs 143a, 143b on either side of bell crank 143 causing the bell crank to pivot back and forth as shown in FIGS. 5 and 6A-D. Bell crank 143 is pivotally attached to a lower portion 114 of the housing 110 by pin 145. A pawl 146 is attached to bell crank 143 on either side at points 146a, 146b. As the bell crank pivots to one side, one of the pawls is pushed forward while the other is pulled back. When the pawl 146 is pulled back, a hook 146c on the end of the pawl engages with a tooth on ratchet 147a on the side of a lower nip roller 147 which causes the polishing media 142 to be meted out in a direction 148 when it is squeezed between the lower nip roller 147 and an upper nip roller 147b (
During polishing, the polishing media 142 is supported by a spring loaded pressure plate assembly 149 (see
The spring loaded pressure plate assembly includes a compliant layer 149a, a floating rigid base plate 149b, a hollow support shaft 149e, a solid support shaft 149c and a spring 149d. One end of the hollow support shaft 1493 is fixedly attached to the rigid base plate 149b while the other end of the hollow support shaft 149e is placed over a solid support shaft 149c that is fixedly attached to the base portion 114 of the polisher housing 110. The outer diameter of solid support shaft 149c is slightly smaller than the inner diameter of hollow support shaft 149e, allowing hollow support shaft 149e, and therefore the rest of spring loaded pressure plate assembly 149, to slide telescopically up and down solid support shaft 149c. The spring 149d is sized such that it fits over both support shafts 149c and 149e and is constrained at its ends against rigid base plate 149b and base portion 114, providing the lifting pressure for the spring loaded pressure plate assembly 149. Compliant layer 149a can comprise a relatively hard material (e.g., having a Shore A durometer of about 60 to about 80, preferably a Shore A durometer of about 70). The spring force of the spring 149d provides overall compliance for the spring loaded pressure plate assembly 149 while the compliant layer 149a provides the appropriate support for the polishing media 142.
In a further exemplary aspect, the appropriate contact force on the fiber tip being polished can be from about 100 grams force to about 150 grams force, preferably about 130 grams force, depending on the length of the protruding fiber and the abrasive media. The combination of contact force, compliance of the spring loaded pressure plate assembly 149 and shape of the ferrule tip cooperate to help provide a desired shape on the polished fiber surface.
An additional feature of the dispenser system 140 is the cut-off blade 197 (see
An additional feature of the exemplary polishing system is the integral lubricant dispensing system 130 housed within the polishing apparatus. The lubricant dispensing system 130 can supply a lubricant (not shown) to the polishing media 142 near the tip of the optical connector ferrule. Referring to
As shown in
The connector mount 120 is configured to receive a conventional optical fiber connector, such as an SC, LC, ST, FC or MT style connector. For example, a conventional connector can include a remote grip connector 10 (see e.g.
In alternative aspects, the conventional connector 10 can include a Crimplok™ Connector available from 3M Company (St. Paul, Minn.), a 3M™ 8300 Hot Melt SC connector, or 3M™ 8206 FC/APC Connector (Epoxy) available from 3M Company (St. Paul, Minn.). In an exemplary aspect, the connector 10 can have an SC format. In other aspects, the polishing apparatus can be configured to receive a connector having another standard connector format, such as an LC format or an FC format. In a further alternative, the connector mount 120 can be configured to receive a connector having multiple fibers, such as an MT fiber connector.
The connector mount 120 is configured to releasably hold and secure optical fiber connector 10 and to provide a snug fit to hold connector 10, e.g., by a snap fit. Preferably, connector 10 can be held by the connector mount 120 at a predetermined angle. For example, the connector mount 120 can hold connector 10 for a flat polish (0°), where the polishing media is perpendicular to the axial direction of the fiber, or, alternatively, an angled polish that is at a small angle (about 2° to about 12°) from perpendicular, to yield an angle-polished connector.
In an alternative aspect, the string pull of the drive assembly can be replaced by a crank or a rotating knob. While in another alternative aspect, the polishing apparatus manually operated drive assembly can be replaced by an electric motor, at least one battery, and a control circuit. The electric motor would control the motion of the connector plate and the moving of the polishing media during operation in a method similar to that described above.
Advantageously, apparatus 100 can provide consistent, repeatable polishing results and can substantially reduce the craft sensitivity. The incorporation of the lubricant dispensing system eliminates the need for an external supply of lubricant. Also, the tape style polishing media allows the polishing apparatus to hold enough media to polish a plurality of optical connectors before the roll of media needs to be replaced, thus saving time and simplifying the polishing process.
An exemplary method of the present invention provides a repeatable process that can lead to repeatable field polishing or optical fiber connectors. In particular, the following method can be employed to effectuate one or more field polished optical fiber connectors in a straightforward manner. In an exemplary aspect, the overall process includes stripping and cleaving the fiber cable, setting the fiber protrusion (distance between the fiber tip and the ferrule end face, and polishing the fiber tip. After polishing, the fiber tip can be cleaned.
In more detail, a strain relief boot (see
The fiber can be positioned into a field cleaver, such as the cleaver described in PCT publication Number WO2008/100768, incorporated by reference herein in its entirety. A cleaving operation, using e.g., a diamond coated wire, can be performed using the field cleaver. This cleaver can produce a fiber tip having a cleave angle of between 0° to about 3.5° from perpendicular.
The cleaved fiber is then moved to a protrusion setting mechanism that sets the distance the fiber tip protrudes from the end face of the ferrule. At this stage, the fiber can be guided into the remaining connector components until the fiber tip protrudes from the ferrule end. In an exemplary aspect, the protrusion setting mechanism comprises a setting jig having a ferrule-type end with a fixed step formed thereon. The setting jig is brought into contact with the connector 10 so that the stepped end of the setting jig contacts the end of the connector ferrule. This process sets the proper protrusion distance to the point where a slight bow in the fiber assures that fiber contact with the setting jig is maintained. A sufficient protrusion can be from about 15 μm to about 35 μm, with a preferable protrusion of about 25 μm. With the remote grip connector, the gripping element is then actuated using the actuator cap to secure the fiber position. In addition, buffer strain relief is activated using the buffer clamp portion of the connector 10. Optionally, when utilized, a crimping tool can be used to compress the crimp sleeve around the fiber jacket to secure the fiber cable in place after the fiber protrusion setting.
In an alternative aspect of the invention the exposed end of the optical fiber may be cleaved after the optical fiber is secured in an optical connector, such as a Crimplok™ Connector available from 3M Company (St. Paul, Minn.).
The connector 10 is thus ready for polishing and can be inserted in connector mount 120 of the polishing apparatus 100. The polishing media (e.g., a 863XW 3M™ Final Polish, available from 3M Company, St. Paul, Minn.) can be wetted with a lubricant (e.g. DI water or other conventional polishing fluid) by pressing the compressible bulb 134a (
The craftsman can activate the polishing apparatus by pulling on an end pull string 151. Advantageously, the pull string can have a knob 151 a or other holder on an end thereof to facilitate gripping the string during polisher activation. This action activates the drive assembly 150 which creates moves the connector holding plate 160 in an orbital motion while simultaneously moving the polishing media in a linear direction. If additional polishing is needed, this process can be repeated. The degree of polish needed will determine the number of activation steps needed to complete the polishing operation. Factors such as the type of polishing media, connector style, and application need to be considered when determining the required degree of polish needed.
The exemplary embodiments described above can simplify the field polishing process, while controlling several sources of variability that have in the past led to a skill-level dominated practice. For example, the common “air polishing” practice of beginning a field polish while holding an abrasive polishing material in air (without any controlled backing force being applied) can be eliminated. Also, the field technician needs to be concerned the polishing force or polishing distance (e.g. the size and shape of figure 8's traced on the polishing media). The polishing apparatus can be a simple hand tool, without the need for a motor or power source. For certain connectors, such as described above, only a single polishing step would be needed.
The present invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention as fairly set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the present specification. The claims are intended to cover such modifications and devices.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US10/24865 | 2/22/2010 | WO | 00 | 8/10/2011 |
Number | Date | Country | |
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61160817 | Mar 2009 | US |