BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is related to a fiber optical polishing machine to polish end surfaces of optical fibers secured in ferrules, or the connection end surfaces of optical connectors with high polishing quality. The Pressure device and fixture for fiber optic polisher herein disclosed is an improvement over our previous invention in U.S. Pat. No. 7,491,114.
2. Description of Related Art
Unlike electrical wires, optical fibers require end-surface treatment for proper light propagation. The two most common ways of end surface preparations are cleaving and polishing, in which polishing is essential and key process for almost all glass-based fibers with cladding diameters larger than 200 microns. Furthermore, polishing is required for all glass fiber connectors used in optical communication to achieve low insertion loss and high return loss. Because the diameter of most optical fibers ranges from 80 um to 1000 um, too small to be polished directly, ceramic, metal, or glass ferrules are often used to protect the fibers. The most commonly used fiber connectors employ ceramic or metal ferrules. Glass ferrules are preferred when optical coating is necessary after polishing for better adhesion. Unlike lens polishing, the convex surfaces of the fiber ferrules are achieved by pressing the ferrules on flexible polishing pads. The polished dome surface is ideal for true physical contact between two single mode fiber cores. Physical contact is also possible with multimode fibers when the core diameter is small. The dome radius of curvature is determined by the polishing locus (movement path), pressing force, the hardness and the thickness of the polishing pad. A true physical contact also requires a slight undercut of the fiber. The amount of undercut is the result of the type of polishing film used, polishing locus, the force applied, and the polishing speed. As one can imagine, a consistent high-quality and high speed polish can only be achieved by a polishing machine with a well designed polishing locus.
Generally speaking, a fiber optic polishing machine, or a polisher, consists of the following modules: Mechanical transmission module, Fixture Module, Pressure Module, Accessory module, and Control module if it is needed.
Mechanical transmission module, would convert the rotation of motor, or human hand, into desired polishing motion of a turntable, which provides a support for polishing pad, or polishing film.
A polishing Fixture Module is used to clamp, or secure fiber optic connectors, or ferrules during polishing operations. Fixture Module should maintain stationary when polishing machine is working in all directions, except in the pressure direction in some design.
For a polishing machine, or a polisher, it is required that the foremost end surface of the ferrule is normally brought into pressure contact with the working surface of the polishing film during each polishing operation. Pressure module is a mechanism to enable the jig, or fixture to be pressed against the polishing film with an adjustable pressure.
In our previous invention in U.S. Pat. No. 7,491,114, a fiber optic polishing apparatus is disclosed including a single degree-of-freedom (DOF) gear transmission system, a pressure module, a fixture module, and a housing assembly. The single DOF gear transmission system would enable a fiber optic polishing machine, or polisher to be driven by only one motor, or by human hand. The manual polisher is a unique field polishing machine where electricity or battery is not available or not allowed. Both manual polisher and motorized polisher have the following features: polishing up to four connectors or ferrules simultaneously; adjustable force ensures consistent finish for a wide variety of connector types and the number of connectors in the fixture; quick release for convenient removal of polish fixture; small footprint for multiple-machine operation to avoid time-consuming film change.
The polishing fixture module in our previous invention is made of single metal plate with flexuous features, cut out by wire EDM method, for holding and releasing fiber ferrules or connectors during the polishing process controlled by a set screw. One of the drawback to use set screw in this invention is to cause damage to the flexure from the variable torque applied by different operators.
Like most prior arts, U.S. Pat. Nos. 4,979,334, and 5,674,114, the pressure module in our previous invention is to apply an adjustable pressure on top of the polishing fixture module. So the Fixture Module could be floating in the pressure direction to maintain a constant polishing pressure. The disadvantage of those inventions is that the Fixture Module cannot maintain stationary when polishing machine is working. Actually it is movable in the pressure direction.
In U.S. Pat. No. 6,808,314, the adjustable pressure is applied on 4 corners of the fixture plate through 4 springs in 4 supporting posts. The drawback of this invention is the difficulty to maintain the 4 spring forces equal. Also the Fixture Module cannot maintain stationary when polishing machine is working.
SUMMARY OF THE INVENTION
In order to solve the aforementioned problem, the first object of the present invention is to provide a pressure module for fiber optic polishing machine, or polisher, which is able to apply an adjustable pressure from bottom of the polishing fixture module. So the Fixture Module could not be floating in the pressure direction and maintain stationary when polishing machine is working.
Another object of the present invention is to provide a quick-release mechanism for polishing fixture module, for holding and releasing fiber ferrules or connectors during the polishing process controlled by sets of magnets. It's easy to work, and to protect the fixture flexure from the un-proper torque applied by different operators.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a 3D view of a manual polisher in the current invention.
FIG. 2 is a 3D view of the manual polisher of our previous invention in U.S. Pat. No. 7,491,114.
FIG. 3 is a cross section view of first preferred embodiment of the fixture module and the pressure module in the current invention.
FIG. 4
a and FIG. 4b are top view and a cross section view, respectively, of first preferred embodiment of the quick-release mechanism for polishing fixture module in the current invention.
FIG. 5
a is the top view of the fixture flexure in the current invention, and FIG. 5b is the bottom view the fixture flexure with fixture plate in the current invention.
FIG. 6 is a cross section view of the pressure module in our previous invention in U.S. Pat. No. 7,491,114.
FIG. 7 shows the fixture module and pressure module in our previous invention in U.S. Pat. No. 7,491,114.
FIG. 8 is a cross section view of second preferred embodiment of the fixture module with the quick-release mechanism in the current invention.
FIG. 9 is a cross section view of second preferred embodiment of the quick-release mechanism for polishing fixture module in the current invention.
FIG. 10
a and 10b show how to adjust the pressure of the pressure module in the current invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is now described in detail with reference to the accompanying drawings for particular applications. However, the present invention is not limited thereto.
One of a preferred embodiment in our previous invention in U.S. Pat. No. 7,491,114, is the manual polisher as illustrated in FIG. 2, FIG. 6 and FIG. 7. The one DOF gear transmission system is installed inside of the housing 11. A rubber polishing pad (not shown) is placed on the top surface of turntable 20 and moves along with the turntable 20. The crank handle 09 is forming a revolute joint with crank 07. So once a rotational motion is applied to crank 07, the turntable 20 performs a compound rotary-revolution motion. On the top surface of cover plate 12, there are the fixture module and pressure module. Fixture 18 is a single piece of metal plate with features cut out by wire EDM method for holding and releasing fiber ferrules, or connectors in place. It allows the optic ferrule ends extending out of the bottom surface of fixture 18 during the polishing process. Fixture 18 sits on top of the rubber polisher pad and is supported by a pair of pins 80 and 88 through bush 79. Pin 80 and 88 are screwed into the screw holes of plate 12 so that the fixture height can be adjusted (FIG. 7). Polishing pressure is provided by adjusting the micrometer 92 to enable the pressure head 17 down to the top surface of fixture (FIG. 6). As shown in FIG. 6, pressure head 17 can be tuned up and down in the central hole of holder 15, which is fixed on the polishing arm 14. Spring 100 and plug 16 are mounted in the central hole above pressure head 17. The amount of polishing pressure is controlled by a micrometer 92, which is held on the top end of holder 15. By turning the micrometer 92, polishing pressure is adjusted through plug 16 and spring 100.
One of a preferred embodiment in current invention is illustrated in FIG. 1, where, Mechanical transmission module, and Accessory module, are the same as in our previous invention in U.S. Pat. No. 7,491,114, except the Fixture Module, and Pressure Module. If a rotational motion is applied to crank 09, the turntable 120 performs a compound rotary-revolution motion.
As shown in FIG. 5a, a polishing fixture 135 is made of single metal plate with features cut out by wire EDM method for holding and releasing 2 fiber ferrules or connectors during the polishing process. The clamping holes 1351 and 1352 geometrically comprise two-half cylinders: the first half cylinder on frame 1355, and the second half cylinder on cantilever 1354. The frame 1355 of the polishing fixture 135 is secured on polishing plate 130 as shown in FIG. 5b. When the tip 1412 of the drive-bar 141 is moving into the notch 1353 between two cantilever 1354, the cantilever would move against each other to drive the second half cylinder to tighten the fiber ferrules or connectors (not shown) in the clamping holes 1351 and 1352 respectively during the polishing process. When the tip 1412 of the drive-bar 141 is moving out of the notch 1353 between two cantilever 1354, the cantilever would recover to their original position due to the flexuous feature of the fixture to release the fiber ferrules or connectors from the clamping holes 1351 and 1352 respectively. The polishing plate 130 is located above the polishing pad 151, and supported by a number of rods 101 from the top surface of cover plate 12 through a couple of magnets 102 and 131 (FIG. 3, FIG. 4a and FIG. 4b). Because the poles of the magnets 102 and 131 are arranged to attract each other, the polishing plate 130 is easy to mount and remove away from polishing pad 151.
Refer to FIG. 3, FIG. 4a and FIG. 4b, the first preferred quick-release mechanism for polishing fixture module includes the drive-bar 141, spring 149, release lever 142, pin 148, release holder 136, magnet 143, 144, 145, 146. The release holder 136 is secured on polishing plate 130 and provide the host to magnet 146, and the drive-bar 141. Magnet 144 is secured on one of the distal end of the drive-bar 141. The release lever 142 is rotatable relative to release holder 136 through pin 148. The poles of magnets 145 and 146 are arranged to attract each other. While the poles of the magnets 143 and 144 are arranged to repel each other. So when the release lever 142 is rotated to engaged position (like FIG. 3FIG. 4a and FIG. 4b), the attraction force between magnets 145 and 146 would maintain the engagement status. At the same time, magnets 143 and 144 is repelled each other to force the drive-bar 141 to move into the notch 1353 (FIG. 5a) of the fixture 135 while the spring 149 is compressed. When the release lever 142 is rotated away from the engaged position (not shown in drawing), the magnets 145 and 146, magnets 143 and 144 is moved away each other. While the spring 149 would force the drive-bar 141 to move out of the notch 1353 of the fixture 135. The pole axes between magnets 145, 146, and magnets 143, 144 are arranged perpendicular each other.
Refer to FIG. 8 and FIG. 9, the second preferred quick-release mechanism for polishing fixture module includes the drive-bar 301, spring 302, release lever 304, pin 312, release holder 303, set screw 305, magnet 308 and 310. The release holder 303 is secured on polishing plate 130 and provide the host to magnet 308, and the drive-bar 301. Magnet 310 is secured on one of the distal end of release lever 304. The release lever 304 is rotatable relative to release holder 303 through pin 312. The poles of magnets 308 and 310 are arranged to attract each other. So when the release lever 304 is rotated to engaged position (like FIG. 9 and FIG. 8), the attraction force between magnets 308 and 310 would maintain the engagement status. At the same time, set screw 305 would touch the end of drive-bar 301 and force the drive-bar 301 to move into the notch 1353 (FIG. 5a) of the fixture 135 while the spring 302 is compressed. When the release lever 304 is rotated away from the engaged position (not shown in drawing), magnets 308 and 310 is moved away each other. While the spring 302 would force the drive-bar 301 to move out of the notch 1353 of the fixture 135.
The advantage of the quick-release mechanism for polishing fixture module in the current invention is that the clamping force on the polished fiber ferrules or connectors remain the same, not reply on the operator's personal skill.
Polishing pressure is provided by the pressure module of the polishers in the current invention. As shown in FIG. 3 and FIG. 10a, the pressure module of the current invention includes bottom turntable 120, top turntable 150, polishing pad 151, drive pin 156 (3), drive pin bush 155 (3), pressure spring 154, pressure nut 153, and pressure threaded stud 152. The compound rotary-revolution motion of bottom turntable 120 is obtained from three drive pin 156, which are driven by the Mechanical transmission module in our previous invention in U.S. Pat. No. 7,491,114. The drive pin bush 155 are secured on the top turntable 150. So the top turntable 150 and polishing pad 151 would be forced to follow the bottom turntable 120 due to the engagement of drive pin 156 and bush 155 to provide a compound rotary-revolution polishing motion. But the drive pin 156 and the drive pin bush 155 are relatively movable along the drive pin axis direction. The threaded stud 152 is secured on the top turntable 150. The nut 153 is engaged with the threaded stud 152 by their thread. The pressure spring 154 is located between the nut 153 and bottom turntable 120 so as to physically to provide a support to the top turntable 150 along the drive pin axis direction. The polishing pressure can be adjusted by turning pressure nut 153. Refer to FIG. 10a and FIG. 10b, there are scales 202 on the surface of drive pin 156. By turning pressure nut 153, the relative position between edge 200 of the drive pin bush 155 and the scales 202 would indicate the pressure values for different polishing requirements.
Patent Application
20140287661
