Patent Publication Number: US-2011070812-A1

Title: Circular path generating device

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a circular path generating device, and more particularly, to a circular path generating device utilizing bi-axial movement and characterized by a mechanism of one degree of freedom, a simple structure, uniform circular motion, and easy control, etc. 
     2. Description of Related Art 
     Mechanism of machines and/or polishers for grinding end surfaces of optical fiber ferrules has three types, namely the planetary gear mechanism, the linkage mechanism, and the eccentric mechanism. 
     Generally speaking, wafer grinding machines are functionally similar to those machines designed for grinding end surfaces of optical fiber ferrules. Both of them require a grinding platform, and are capable of repeated and circulative grinding. However, conventional optical fiber grinding machines and conventional wafer grinding machines also share the following drawbacks: 
     [1] Inevitable performing via a mechanism of two degrees of freedom: The first example of conventional mechanism designs for grinding end surfaces of optical fiber ferrules is disclosed, for example, in U.S. Pat. No. 6,428,391 B2, entitled “METHOD AND APPARATUS FOR POLISHING”, wherein grinding is effected by motions of the linkage mechanism driven by two driving input sources which are commonly controlled by one motor. Such grinding mechanism of two degrees of freedom needs belts to drive an additional crank, and therefore results in excessive complicity of the driving input sources. 
     [2] Complex (cam-linkage) mechanism: The second example of conventional mechanism designs for grinding end surfaces of optical fiber ferrules is disclosed, for example, in U.S. Pat. No. 6,454,631, entitled “POLISHING APPARATUS AND METHOD”, wherein two cams are configured for driving operations of an upper platform and a lower platform so as to generate intended grinding paths. Such grinding mechanism has two degrees of freedom and is not capable of functioning based on a single platform. 
     [3] Incapability of uniform circular motion: Another conventional mechanism design for grinding optical fiber patch cords is exemplified by Taiwan Patent No. 431258 (Patent Certificate No. 175358), entitled “MACHINE FOR GRINDING OPTICAL FIBER PATCH CORDS”, wherein the linkage mechanism thereof cannot generate uniform circular motion for grinding, and in consequence, the velocity thereof at every point varies entirely. 
     [4] Requirement of complicated control: The third example of conventional mechanism designs for grinding end surfaces of optical fiber ferrules is disclosed, for example, in U.S. Pat. No. 5,947,797, entitled “COMPUTER-CONTROLLED METHOD FOR POLISHING”, wherein X-direction plates and Y-direction plates are controlled by a programmed logic controller (PLC) to generate grinding motions along the desired paths, and yet such control is rather complicated. 
     Hence it is imperative to develop a novel method/mechanism to overcome the foregoing drawbacks. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a circular path generating device which employs a mechanism of one degree of freedom, features a simple structure, is capable of operating based on uniform circular motions, and can be easily controlled, etc., so as to overcome the drawbacks of the conventional designs such as complexity of driving input sources, complex mechanism, incapability of uniform circular motion, and requirement of complicated control. 
     The technical solution to the aforesaid problems according to the present invention is to provide a circular path generating device comprising: 
     a base having a first axial-direction rail portion; 
     a sliding stage having a first sliding portion and a second axial-direction rail portion, wherein the first sliding portion is slidably disposed on the first axial-direction rail portion so that the sliding stage is able to move along a first axial direction; 
     a working portion having a second sliding portion, a working surface, and a non-working surface, wherein the second sliding portion is slidably disposed on the second axial-direction rail portion so that the working portion is able to move along a second axial direction, and a central position of the non-working surface has a connecting portion; and 
     a driving device having a driving portion and a crank portion, wherein the driving portion is configured for driving the crank portion to rotate, and the crank portion is connected to the connecting portion. 
     Accordingly, through motions of the working portion along the second axial direction and motions of the sliding stage along the first axial direction, coordinates of the working portion can vary within a predetermined planar range. When the crank portion is driven by the driving portion to rotate, the working portion is driven by the crank portion to move along a circular path. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The invention will become more fully understood from the following detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a perspective view of a circular path generating device according to the present invention; 
         FIG. 2  is a side elevation view of the circular path generating device according to the present invention; 
         FIG. 3A  schematically shows a first motion of the circular path generating device according to the present invention; 
         FIG. 3B  schematically shows a second motion of the circular path generating device according to the present invention; 
         FIG. 3C  schematically shows a third motion of the circular path generating device according to the present invention; 
         FIG. 3D  schematically shows a fourth motion of the circular path generating device according to the present invention; 
         FIG. 4A  schematically shows a first grinding direction of the circular path generating device according to the present invention; 
         FIG. 4B  schematically shows a second grinding direction of the circular path generating device according to the present invention; 
         FIG. 4C  schematically shows a third grinding direction of the circular path generating device according to the present invention; 
         FIG. 4D  schematically shows a fourth grinding direction of the circular path generating device according to the present invention; 
         FIG. 5  schematically shows a moving process of the circular path generating device according to the present invention; 
         FIG. 6  schematically shows a moving path of the circular path generating device according to the present invention; 
         FIG. 7  is an exploded perspective view of a second embodiment of the circular path generating device according to the present invention; and 
         FIG. 8  is a sectional view of parts of a third embodiment of the circular path generating device according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
     Referring to  FIG. 1  and  FIG. 2 , a circular path generating device according to the present invention includes a base  10 , a sliding stage  20 , a working portion  30 , and a driving device  40 . 
     The base  10  has a first axial-direction rail portion  11 . 
     The sliding stage  20  has a first sliding portion  21  and a second axial-direction rail portion  22 . The first sliding portion  21  is slidably disposed on the first axial-direction rail portion  11 , thus allowing the sliding stage  20  to move along a first axial direction X. 
     The working portion  30  (e.g., a single-layer grinding plate) has a second sliding portion  31 , a working surface  32 , and a non-working surface  33 . The second sliding portion  31  is slidably disposed on the second axial-direction rail portion  22 , thus allowing the working portion  30  to move along a second axial direction Y. A central position of the non-working surface  33  has a connecting portion  331 . 
     The driving device  40  has a driving portion  41  and a crank portion  42 . The driving portion  41  is configured for driving the crank portion  42  to rotate. The crank portion  42  is connected to the connecting portion  331 . 
     Accordingly, with the working portion  30  moving along the second axial direction Y, and the sliding stage  20  moving along the first axial direction X, coordinates of the working portion  30  can vary within a predetermined planar range. When the crank portion  42  is driven to rotate by the driving portion  41 , the working portion  30  is driven by the crank portion  42  to move along a circular path. 
     Referring to  FIG. 3A , assuming that the working portion  30  defines a reference point A, when the crank portion  42  moves the connecting portion  331  to a first position P 1 , the reference point A is located at a fifth position P 5 . Referring to  FIG. 3B , when the crank portion  42  moves the connecting portion  331  from the first position P 1  to a second position P 2 , the working portion  30  is driven to move along the second axial-direction rail portion  22  in the second axial direction Y by a predetermined distance S, and the sliding stage  20  is driven to move along the first axial-direction rail portion  11  in the first axial direction X by the predetermined distance S. In consequence, the reference point A is moved from the fifth position P 5  to a sixth position P 6 . Referring to  FIG. 3C , when the crank portion  42  moves the connecting portion  331  from the second position P 2  to a third position P 3 , the working portion  30  is driven to move along the second axial-direction rail portion  22  in the second axial direction Y by the predetermined distance S, and the sliding stage  20  is driven to move along the first axial-direction rail portion  11  in the first axial direction X by the predetermined distance S, such that the reference point A is moved from the sixth position P 6  to a seventh position P 7 . Referring to  FIG. 3D , when the crank portion  42  moves the connecting portion  331  from the third position P 3  to a fourth position P 4 , the working portion  30  is driven to move along the second axial-direction rail portion  22  in the second axial direction Y by the predetermined distance S, and the sliding stage  20  is driven to move along the first axial-direction rail portion  11  in the first axial direction X by the predetermined distance S. As a result, the reference point A is moved from the seventh position P 7  to an eighth position P 8 . 
       FIG. 4A  to  FIG. 4D  show variations of grinding directions of the working surface  32  when grinding a predetermined workpiece. While the connecting portion  331  is driven by the crank portion  42  to move from the first position P 1  toward the second position P 2 , the grinding direction in which the predetermined workpiece is ground is shown in  FIG. 4A . Similarly,  FIGS. 4B to 4D  show the grinding directions in which the predetermined workpiece is ground when the connecting portion  331  is driven by the crank portion  42  to move from the second position P 2  toward the third position P 3 , from the third position P 3  toward the fourth position P 4 , and from the fourth position P 4  toward the first position P 1 , respectively. 
     It can be understood from the above descriptions and  FIG. 5  that the crank portion  42 , when driven by the driving portion  41 , drives the working portion  30  to move as uniform circular motions (as illustrated in  FIG. 6 , which shows the moving path of the working portion  30 ). 
     With reference to  FIG. 7 , the driving device  40  further comprises a speed reducer  43 . The speed reducer  43  has two ends which are disposed upon the driving portion  41  and the crank portion  42 , respectively. The speed reducer  43  is driven by the driving portion  41  and in turn drives the crank portion  42  to rotate. In addition, the circular path generating device of the present invention is equipped with two ball bearings  50 . One of the ball bearings  50  is disposed at the connecting position where the connecting portion  331  is connected to the crank portion  42 , and the other of the ball bearings  50  is disposed at the connecting position where the driving portion  41  is connected to the speed reducer  43 . 
     The present invention is applicable to various grinding machines, polishing machines, and other equipment for use in optical fiber and semiconductor manufacturing processes so as to enhance quality of optical-fiber-related and semiconductor-related products. 
     In the embodiment depicted in  FIG. 7 , the second sliding portion  31 , the working surface  32 , and the non-working surface  33  are separate parts assembled together to form the working portion  30 . It is understood that the working portion  30  may also be integrally formed, as shown in  FIG. 8 , wherein a single workpiece is processed to form the second sliding portion  31 , the working surface  32 , and the non-working surface  33 . 
     To sum up, the present invention has the following advantages and effects: 
     [1] Performing by a mechanism of one degree of freedom: As previously mentioned, some conventional mechanism designs for grinding end surfaces of optical fiber ferrules use a motor to control two driving input sources and drive related linkage mechanism to move. However, such grinding mechanisms of two degrees of freedom need belts to drive an additional crank, and as a result, driving input sources become much complicated. By contrast, the present invention utilizes the driving portion  41  to directly drive the crank portion  42 , and therefore, is characterized by its simple driving input source design. The mechanism according to the present invention of one degree of freedom is apparently superior to conventional grinding mechanisms of two degrees of freedom. 
     [2] Simple structure: As previously mentioned, some conventional mechanism designs for grinding end surfaces of optical fiber ferrules are more structurally complicated because grinding paths thereof are generated by upper and lower platforms which are driven by two cams. In the present invention, however, a much simpler structure is employed in which the working portion  30  moves along a circular path simply by virtue of the crank portion  42  and accompanying sliding motions along the first and second axial directions X, Y. 
     [3] Capability of Uniform circular motion: As previously mentioned, the linkage mechanisms of some conventional mechanism designs for grinding optical fiber patch cords cannot contribute to uniform circular motions, thus rendering velocity of every point to be variable entirely. Nevertheless, the driving portion  41  of the present invention is a single driving output source and capable of contributing to uniform circular motions. 
     [4] Achievement of Easy control: As previously mentioned, some conventional mechanisms for grinding end surfaces of optical fiber ferrules require complicated control by using a PLC to control X-direction and Y-direction plates, and thereby generate grinding motions along desired paths. By contrast, the present invention takes advantage of the driving relationships among components and makes it possible to control forward and backward rotating motions simply by connecting the power source to related capacitors. 
     While the present invention is demonstrated herein with reference to the preferred embodiments, it is to be understood that the foregoing embodiments may be slightly modified or changed without departing from the spirit and scope of the present invention.