Abrading – Precision device or process - or with condition responsive... – With indicating
Reexamination Certificate
1999-10-14
2001-08-28
Banks, Derris H. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
With indicating
C451S270000, C451S271000, C451S008000
Reexamination Certificate
active
06280293
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressurizing apparatus for polishing end faces of fine workpieces, and more particularly to an end face polishing apparatus for polishing to a spherical form a ferrule end face as a connector component part of an optical fiber.
2. Description of the Related Art
In recent years, optical communication is expected to become the next generation communication technology because of its high capacity and speed. Optical fibers have been introduced into our surroundings. The ferrules are formed of zirconia based ceramic material into a cylindrical form through an injection molding, extrusion or pressing technique, and used as major optical connector parts for optical fibers. Here, the ferrule has its hollow portion termed as a fiber insertion bore in which an optical fiber is inserted. Such ferrules are abutted against each other at their end faces thereby providing coupling between optical fibers. In coupling optical fibers, there is a necessity to polish ferrule end faces to a high surface roughness accuracy in order to prevent light from reflecting and attenuating at abuttment faces of the ferrules and keep a fiber optical characteristic favorable.
Conventionally, when polishing an end face of a ferrule, the ferrule has been fixed by a jig plate. Thereafter, the ferrule at an end face is pressed onto a polishing sheet that is elastically deformable by given pressure (load weight, spring force) and then the polishing sheet is rotated. By utilizing a spherical depression surface on the polishing sheet resulting from pressing the ferrule end face, the ferrule end face is polished to a spherical shape through three stages of rough, middle and fine finishes.
The conventional polishing apparatus have not had a means to control the pressure at which the ferrule end face is urged against the polishing sheet during polishing of the ferrule end face. As a result, the ferrule end face has to be urged onto the polishing sheet at a given high pressure for polishing into a spherical shape. Consequently the ferrule end face is burdened with a high application of pressure at the start of polishing operation, resulting in damage to the ferrule end face.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an end face polishing apparatus which is capable of controlling the pressing force with which pressure of a ferrule end face is urged against a polishing sheet wherein, particularly at a start of polishing, the pressing force is set low to prevent against occurrence of damage to the ferrule end face. The above and other objects and novel features of the invention will became apparent from the description and attached drawings.
An end face polishing apparatus according to the present invention, comprises: a lever coupled with a jig plate for fixing a fine workpiece; a pressurizing section for moving down the lever to urge an end face of the fine workpiece onto an elastically deformable polishing sheet; and a pressurization control section for controlling the pressure applied to the fine work piece when urged onto the polishing sheet by the pressurizing section.
Furthermore, the pressurizing section is formed by a motor for pressurizing the fine workpiece, a screw for moving down the lever by rotation of the motor, and a pressure sensor for detecting urge pressure of an end face of the fine workpiece onto the polishing sheet and feed back detected urge pressure to the pressurization control section. The pressurization control section controls urge pressure of the fine workpiece end face onto the polishing sheet.
Furthermore, the pressurization control section comprises a memory device for outputting a set pressure signal to urge the fine workpiece end face onto the polishing sheet, a comparator for comparing between an urge set pressure signal given from the memory device and an urge pressure detection signal given from the pressure sensor and calculating a difference between the urge set pressure signal and the urge pressure detection signal, a pressure corrector for correcting an urge pressure of the fine workpiece onto the polishing sheet depending on a difference between the urge set pressure signal and the urge pressure detection signal, and a pressurization driver for driving the motor to bring the urge pressure of the fine workpiece end face onto the polishing sheet to an urge pressure corrected by the corrector.
Furthermore, the fine workpiece is a ferrule as a connector component part of an optical fiber.
Accordingly, in the invention after a ferrule for example is fixed, the jig plate is installed on a lever and the lever is moved down by rotation of the motor. Thus, the fine workpiece at its end face is urged at predetermined pressure against the polishing sheet.
On this occasion, the pressure sensor detects an urging force of the fine workpiece end face onto the polishing sheet. The comparator compares between an urge set pressure signal memorized in the set pressure memory device and an urge pressure detection signal given from the pressure sensor. Calculated is a difference between the urge set pressure signal and the urge pressure detection signal.
Then, the corrector corrects for the urge pressure of the fine workpiece end face onto the polishing sheet depending on the difference between the urge set pressure signal and the urge pressure detection signal. The driver drives the motor such that the urge pressure of the fine workpiece end face onto tire polishing sheet becomes corrected urge pressure by the corrector Thus, the polishing sheet is rotated thereby polishing the fine workpiece end face into a spherical shape.
In this manner, the invention can control the urge pressure of the fine workpiece end face onto the polishing sheet. It is possible to prevent damage from occurring in the fine workpiece end face by setting low the urge pressure of the fine workpiece end face particularly at a start of polishing.
REFERENCES:
patent: 4914867 (1990-04-01), Saito et al.
patent: 5107627 (1992-04-01), Mock, Jr. et al.
patent: 5503590 (1996-04-01), Saitoh et al.
patent: 6039630 (2000-03-01), Chandler et al.
patent: 6102785 (2000-08-01), Chandler et al.
Kato Mari
Minami Kouji
Sugiyama Masaharu
Adams & Wilks
Banks Derris H.
Seiko Instruments Inc.
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