Abstract:
A convey system includes at least three rotatable shafts disposed in substantial parallel with one another. A pair of first rollers are disposed at each of the at least three rotatable shafts. A first distance between the pair of first rollers is fixed at each of the at least three rotatable shafts. At least a pair of second rollers are disposed between the pair of first rollers at each of the at least three rotatable shafts. A second distance between the pair of second rollers is varied at each of the at least three rotatable shafts. The second distance between the pair of second rollers is shortest at a middle one or two of the at least three rotatable shafts and increased gradually from thereof to two opposite ends of the at least three rotatable shafts. In order to prevent the substrate from sliding on the first and second rollers, a sandblasted treating or a roughness coating is applied on an outer surface of the first and second rollers.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/372,465, filed Aug. 11, 2010, which is herein incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field of Invention 
         [0003]    The present invention relates to a convey system, and more particularly relates to a roller convey system. 
         [0004]    2. Description of Related Art 
         [0005]    Various conveyors and guide tracks have been proposed in the art. In particular, mechanical conveyors have been used in the industry for transporting articles from one part of, for example, an industrial plant or warehouse to another. The more commonly used conveyors are the ones which transport goods in cartons, boxes and the like. 
         [0006]    The roller convey system used in modem clean rooms requires goods to be transported exactly along a desired direction and to be transported with a controlled and uniform speed. A conventional roller in the convey system pose limitations and difficulties in transporting goods exactly along a desired direction. For the forgoing reasons, there is a need for improving a conventional roller convey system. 
       SUMMARY 
       [0007]    In one aspect of the present invention, a convey system includes at least three rotatable shafts disposed in substantial parallel with one another. A pair of first rollers are disposed at each of the at least three rotatable shafts. A first distance between the pair of first rollers is fixed at each of the at least three rotatable shafts. At least a pair of second rollers are disposed between the pair of first rollers at each of the at least three rotatable shafts. A second distance between the pair of second rollers is varied at each of the at least three rotatable shafts. The second distance between the pair of second rollers is shortest at a middle one or two of the at least three rotatable shafts and increased gradually from thereof to two opposite ends of the at least three rotatable shafts. 
         [0008]    In another aspect of the present invention, a convey system includes a chamber and three rotatable shafts at least. The chamber includes an inlet and an outlet. The at least three rotatable shafts are disposed in substantial parallel with one another within the chamber. A pair of first rollers are disposed at each of the at least three rotatable shafts. A first distance between the pair of first rollers is fixed at each of the at least three rotatable shafts. At least a pair of second rollers are disposed between the pair of first rollers at each of the at least three rotatable shafts. A second distance between the pair of second rollers is varied at each of the at least three rotatable shafts. The second distance between the pair of second rollers is longest at one of the at least three rotatable shafts, which is closest to the inlet or outlet of the chamber and decreased gradually from thereof to one of the at least three rotatable shafts, which is farthest from the inlet and outlet of the chamber. 
         [0009]    In an embodiment disclosed herein, each of the first rollers has an outer rough surface. 
         [0010]    In another embodiment disclosed herein, each of the second rollers has an outer rough surface. 
         [0011]    In another embodiment disclosed herein, each of the at least three rotatable shafts has a plurality of concave scales to be fastened by the first roller or second roller. 
         [0012]    In another embodiment disclosed herein, each of the first rollers has an outer surface of an average roughness Ra ranging from about 0.5 μm to about 30 μm. 
         [0013]    In another embodiment disclosed herein, each of the first rollers has an outer surface of an average roughness Ra ranging from about 2 μm to about 8 μm. 
         [0014]    In another embodiment disclosed herein, each of the second rollers has an outer surface of an average roughness Ra ranging from about 0.5 μm to about 30 μm. 
         [0015]    In another embodiment disclosed herein, each of the second rollers has an outer surface of an average roughness Ra ranging from about 2 μm to about 8 μm. 
         [0016]    In another embodiment disclosed herein, the at least three rotatable shafts are driven by a transmission mechanism. 
         [0017]    In another embodiment disclosed herein, each of the at least three rotatable shafts has two opposite ends rotatable connected with a wall of the chamber. 
         [0018]    In another embodiment disclosed herein, the first roller has a larger radius than the second roller does. 
         [0019]    In still another aspect of the present invention, a convey system includes at least nine rotatable shafts disposed in substantial parallel with one another. A pair of first rollers are disposed at each of the at least nine rotatable shafts. A first distance between the pair of first rollers is fixed at each of the at least nine rotatable shafts. At least a pair of second rollers are disposed between the pair of first rollers at each of the at least nine rotatable shafts. A second distance between the pair of second rollers is varied at each of the at least nine rotatable shafts. The second distance between the pair of second rollers is relatively short at a middle one and two opposite ends of the at least nine rotatable shafts and increased gradually and then decreased gradually from the middle one to the two opposite ends of the at least nine rotatable shafts. 
         [0020]    It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings, 
           [0022]      FIG. 1  illustrates a cross-sectional view of a convey system according to one embodiment of this invention; 
           [0023]      FIG. 2  illustrates a rotatable shaft of the convey system according to another embodiment of this invention; 
           [0024]      FIG. 3  illustrates a side view of a substrate transferred by a convey system according to another embodiment of this invention; 
           [0025]      FIG. 4  illustrates a perspective view of a roller of the convey system according to still another embodiment of this invention; 
           [0026]      FIG. 5  illustrates a cross-sectional view of a convey system according to another embodiment of this invention; and 
           [0027]      FIG. 6  illustrates a cross-sectional view of a convey system according to another embodiment of this invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
         [0029]    A convey system disclosed herein is to transfer a substrate, e.g. a glass substrate or a semiconductor substrate, by means of rollers along a desired direction and to avoid uncontrolled sliding upon the roller&#39;s surface. 
         [0030]    Referring to  FIG. 1 , which illustrates a cross-sectional view of a convey system  100  according to one embodiment of this invention. The convey system  100  includes a chamber  102  and at least three rotatable shafts ( 101   a,    101   b,  installed inside the chamber  102 . Each rotatable shaft ( 101   a,    101   b,    101   c ) is equipped with rollers ( 103 ,  105 ), which are specially positioned to control a desired transferring direction. Each rotatable shaft ( 101   a,    101   b,    101   c ) is equipped with a pair of rollers  103 , which has a fixed distance D between thereof. The distance D should be slightly longer than a width of a substrate (also referring to substrate  305  in  FIG. 3 ) such that the substrate can be transferred along a desired direction  120  and between the pair of rollers  103 . Each rotatable shaft ( 101   a,    101   b,    101   c ) is further equipped with at least a pair of rollers  105  (i.e. two or more pair of rollers  105  are also applicable), which has a varied distance between thereof. The distance between the pair of rollers  105  is shortest (e.g. the distance d 2 ) at a middle one or two of the at least three rotatable shafts (e.g. the rotatable shaft  101   b ) and increased gradually (e.g. the distances d 1  and d 3 ) from thereof to two adjacent opposite ends (e.g. the rotatable shafts  101   a  and  101   c ) of the at least three rotatable shafts. That is, the distance between the pair of rollers  105  is longest (e.g. the distance d 1  or d 3 ) at one (e.g. the rotatable shaft  101   a  or  101   c ) of the at least three rotatable shafts, which is closest to the inlet  102   a  or outlet  102   b  of the chamber  102  and decreased gradually from thereof to one (e.g. the rotatable shaft  101   b ) of the at least three rotatable shafts, which is farthest from the inlet  102   a  and outlet  102   b  of the chamber  102 . In this embodiment, the distance d 1  can be equal to or not equal to the distance d 3 . With such design, a substrate can be precisely transferred along the desired direction  120  and its weight can be evenly distributed by all the rollers  103  and  105 . Besides, a transmission mechanism comprises at least a motor  106 , a transmission belt and/or at least a transmission gear  106   a,  which is installed to drive the three rotatable shafts ( 101   a,    101   b,    101   c ), wherein each rotatable shaft has its two opposite ends rotatably connected with a chamber wall of the chamber  102  or laid on a support set. In an alternate embodiment, the convey system  100  can also be operated without the chamber  102 , e.g. not within a vacuum chamber. 
         [0031]    Referring to  FIG. 2 , which illustrates a rotatable shaft  201  of the convey system according to another embodiment of this invention. The rotatable shaft  201  is equipped with several concave scales  201   r  such that the rollers (e.g. rollers  103  and  105  as illustrated in  FIG. 1 ) can be easily fastened at a position where a concave scale  201   r  is located to vary the distance between a pair of rollers. The roller (e.g. rollers  103  and  105  as illustrated in  FIG. 1 ) can be more reliably secured to the concave scale  201   r  compared with a rotatable shaft without concave scales. 
         [0032]    Referring to  FIG. 3 , which illustrates a side view of a substrate transferred by a convey system according to another embodiment of this invention. When a substrate  305  is supported and transferred by rollers  301  and  303 , the substrate  305  is positioned between the two rollers  303  such that the substrate  305  would not transferred out of the area between the two rollers  303 . A substrate may be supported by the two rollers  303  (referring the substrate  305  as illustrated in  FIG. 3 ) or not supported by the two rollers  303  (e.g. a substrate with a shorter width is only supported by the rollers  301 ). In this embodiment, the rollers  303  have a longer radius R and the rollers  301  have a shorter radius r such that the substrate  305  can be restricted between the two rollers  303  and supported both by the rollers  301  and  303 . 
         [0033]    Referring to  FIG. 4 , which illustrates a perspective view of a roller  401  of the convey system according to still another embodiment of this invention. In order to avoid uncontrolled sliding of a substrate upon the roller&#39;s surface, the roller  401  is specially treated and designed. In particular, an outer surface of the roller  401  is treated to have an average roughness Ra ranging from about 0.5 μm to about 30 μm by sandblasting or other applicable process. In an alternate embodiment, a roughness coating may be formed on the outer surface of the roller  401 . It is preferred that the outer surface of the roller  401  is treated to have an average roughness Ra ranging from about 2 μg in to about 8 μm such that the substrate can be transported smoothly with the least sliding. Besides, the outer surface of the roller  401  can be designed to have “flat-top mountains  401   a ” and “valleys  401   b ” so as to provide a better support and avoid uncontrolled sliding for a substrate thereon. In this embodiment, the flat-top mountains  401   a  may also be treated to have a rough surface with an average roughness Ra ranging from about 0.5 μm to about 30 μm or preferably ranging from about 2 μm to about 8 μm 
         [0034]      FIG. 5  illustrates a cross-sectional view of a convey system according to another embodiment of this invention. The convey system  200  is different from the convey system  100  in that the convey system  200  includes  5  rotatable shafts ( 201   a,    201   b,    201   c,    201   d,    201   e ). The convey system  200  includes a chamber  202  and 5 rotatable shafts ( 201   a,    201   b,    201   c,    201   d,    201   e ) installed inside a chamber  202 . Five rotatable shafts ( 201   a,    201   b,    201   c,    201   d,    201   e ) can be uniformly arranged, e.g. with the same pitch between adjacent two rotatable shafts. Each rotatable shaft ( 201   a,    201   b,    201   c,    201   d,    201   e ) is equipped with rollers ( 203 ,  205 ), which are specially positioned to control a desired transferring direction. Each rotatable shaft ( 201   a,    201   b,    201   c,    201   d,    201   e ) is equipped with a pair of rollers  203 , which has a fixed distance D between thereof. The distance D should be slightly longer than a width of a substrate (also referring to substrate  305  in  FIG. 3 ) such that the substrate can be transferred along a desired direction  220  and between the pair of rollers  203 . Each rotatable shaft ( 201   a,    201   b,    201   c,    201   d,    201   e ) is further equipped with at least a pair of rollers  205  (i.e. two or more pairs of rollers  205  are also applicable), which has a varied distance between thereof. The distance between the pair of rollers  205  is shortest (e.g. the distance d 5 ) at a middle one or two of the five rotatable shafts (e.g. the rotatable shaft  201   c ) and increased gradually (e.g. the distances d 3  and d 4 ) from thereof to two adjacent opposite ends (e.g. the rotatable shafts  201   a,    201   b,    201   d,    201   e ) of the five rotatable shafts. That is, the distance between the pair of rollers  205  is longest (e.g. the distance d 3 ) at one (e.g. the rotatable shaft  201   a  or  201   e ) of the five rotatable shafts, which is closest to the inlet  202   a  or outlet  202   b  of the chamber  202  and decreased gradually from thereof to one (e.g. the rotatable shaft  201   c ) of the five rotatable shafts, which is farthest from the inlet  202   a  and outlet  202   b  of the chamber  202 . With such design, a substrate can be precisely transferred along the desired direction  220  and its weight can be evenly distributed by all the rollers  203  and  205 . Besides, a motor  206  is installed to drive the five rotatable shafts ( 201   a,    201   b,    201   c,    201   d,    201   e ), which each has its two opposite ends rotatably connected with a chamber wall of the chamber  202  or laid on a support set, by means of a transmission belt or transmission gear  206   a.    
         [0035]      FIG. 6  illustrates a cross-sectional view of a convey system  200 ′ according to still another embodiment of this invention. The convey system  200 ′ is different from the convey system  200  in that the convey system  200 ′ includes nine rotatable shafts ( 201   a,    201   b,    201   c,    201   d,    201   e,    201   c ′,  201   c ″,  201   b ′,  201   d′ ). The convey system  200 ′ includes a chamber  202  and nine rotatable shafts installed inside the chamber  202 . The nine rotatable shafts can be uniformly arranged, e.g. with the same pitch between adjacent two rotatable shafts. Each rotatable shaft ( 201   a,    201   b,    201   c,    201   d,    201   e,    201   c ′,  201   c ″,  201   b ′,  201   d ′) is equipped with rollers ( 203 ,  205 ), which are specially positioned to control a desired transferring direction. Each rotatable shaft is equipped with a pair of rollers  203 , which has a fixed distance D between thereof. The distance D should be slightly longer than a width of a substrate (also referring to substrate  305  in  FIG. 3 ) such that the substrate can be transferred along a desired direction  220  and between the pair of rollers  203 . Each rotatable shaft is further equipped with at least a pair of rollers  205  (i.e. two or more pairs of rollers  205  are also applicable), which has a varied distance between thereof. The distance between the pair of rollers  205  is shortest or relatively short (e.g. the distance d 5 ) at a middle one (e.g. the rotatable shaft  201   c ) and two opposite ends (e.g. the rotatable shafts  201   c ′ and  201   c ″) of the nine rotatable shafts, and increased gradually and then decreased gradually (e.g. d 5 =&gt;d 4 =&gt;d 3 =&gt;d 4 =&gt;d 5 ) from the middle one to two adjacent opposite ends of the nine rotatable shafts. With such design, a substrate can be precisely transferred along the desired direction  220  and its weight can be evenly distributed by all the rollers  203  and  205 . Furthermore, a motor  206  is installed to drive the nine rotatable shafts, which each has its two opposite ends rotatably connected with a chamber wall of the chamber  202  or laid on a support set, by means of a transmission belt or transmission gear  206   a.    
         [0036]    According to the above-discussed embodiments, the convey system is equipped with rollers, which are specially positioned to guide a substrate along a desired direction and are specially treated to have an outer rough surface with a proper roughness to avoid uncontrolled sliding of the substrate. 
         [0037]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.