Patent Publication Number: US-2011068533-A1

Title: Sheet transporting apparatus having gear assembly for mounting rotating shaft, and scanner and image processing apparatus using the same

Description:
This application claims priority of No. 098131590 filed in Taiwan R.O.C. on Sep. 18, 2009 under 35 USC 119, the entire content of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a sheet transporting apparatus, and more particularly to a sheet transporting apparatus having a gear assembly capable of securely mounting a rotating shaft. 
     2. Related Art 
     A sheet transporting roller used in a conventional sheet transporting apparatus is mounted on a shaft, two ends of which are attached to a housing. In order to avoid the axial movement of the shaft, the two ends of the shaft are formed with ring-shaped grooves for the mounting of the E-rings, so that the shaft is rotatably mounted in the housing and is secured in the axial direction. 
     It is time-consuming and labor-consuming to secure the shaft using the E-rings. In order to place and remove the E-rings, dedicated tools or jigs have to be used. Nevertheless, more E-rings have to be used if more components are mounted on the shaft, and the removed E-rings cannot be reused if being bent. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide a sheet transporting apparatus having a shaft, which is secured without using E-rings. The shaft is secured by a gear assembly, so that the sheet transporting apparatus is easily assembled and the number of components of the sheet transporting apparatus are decreased. 
     To achieve the above-identified object, the invention provides a sheet transporting apparatus, which includes a housing, a rotating shaft, a roller and a gear assembly. The housing includes a first supporting member and a second supporting member. The rotating shaft is rotatably mounted in the housing. The rotating shaft has a first end portion mounted in the first supporting member, and a second end portion mounted in the second supporting member. The roller, mounted on the rotating shaft and rotated by the rotating shaft, transports a sheet. The gear assembly, coupled to the second end portion, transmits power to the rotating shaft. The gear assembly includes a gear member and a coupling member, rotatable with the gear member, for securing the second end portion to the second supporting member. 
     Thus, the gear assembly easily secures the rotating shaft to the housing to solve the problems of the prior art. 
     Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention. 
         FIG. 1  is a schematic side view showing a sheet transporting apparatus according to a preferred embodiment of the invention. 
         FIGS. 2A and 2B  are partially schematic front views respectively showing assembled and disassembled structures of the sheet transporting apparatus according to the preferred embodiment of the invention. 
         FIG. 3  is a partially schematic illustration showing a gear assembly of  FIG. 2A . 
         FIG. 4  is a cross-sectional view taken along a line  4 - 4  of  FIG. 3 . 
     
    
    
     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. 
       FIG. 1  is a schematic side view showing a sheet transporting apparatus  1  according to a preferred embodiment of the invention.  FIGS. 2A  and  2 B are partially schematic front views respectively showing assembled and disassembled structures of the sheet transporting apparatus  1  according to the preferred embodiment of the invention.  FIG. 3  is a partially schematic illustration showing a gear assembly of  FIG. 2A . Referring  FIGS. 1 to 3 , the sheet transporting apparatus  1  of this embodiment, which may be included in a scanner or an image processing apparatus, such as a printer or a multi-function peripheral, includes a housing  10 , a rotating shaft  20 , a gear assembly  30  and a roller  40 . In addition, the sheet transporting apparatus  1  may further include a second rotating shaft  20 ′, a second roller  40 ′, rotating shafts  60  and  60 ′, driven rollers  70  and  70 ′, a belt  80  and a driving gear  90 . 
     The housing  10  includes a first supporting member  12  and a second supporting member  14 , and serves as a frame for supporting the components of the rotating shaft  20 , the gear assembly  30  and the roller  40 . The first supporting member  12  and the second supporting member  14  may be integrally formed jointly with the housing  10 , and may also be individual members disposed in the housing  10 . 
     The rotating shaft  20  is rotatably mounted in the housing  10  and has a first end portion  22  and a second end portion  24 . The first end portion  22  is mounted in the first supporting member  12 , and the second end portion  24  is mounted in the second supporting member  14 . Similarly, the rotating shaft  20 ′ may also be rotatably mounted in the housing  10  in a similar manner. 
     The roller  40 , mounted on the rotating shaft  20  and rotated by the rotating shaft  20 , transports a document sheet S. The roller  40  may directly or indirectly drive the driven roller  70  to rotate. Similarly, the roller  40 ′ is also mounted on the rotating shaft  20 ′ in a similar manner. The second roller  40 ′ and the driven roller  70 ′ transport the document sheet S out of the sheet transporting apparatus  1 . 
     The gear assembly  30 , coupled to the second end portion  24 , transmits power to the rotating shaft  20 . The gear assembly  30  includes a gear member  32  and a coupling member  34 , rotatable with the gear member  32 , for securing the second end portion  24  to the second supporting member  14 . 
     The gear member  32  includes gear teeth  32 A and/or gear teeth  32 B. In this embodiment, the gear teeth  32 B mesh with gear teeth  92  of the driving gear  90  and transmit power to the rotating shaft  20 . The coupling member  34  includes a sleeve  340  formed with elastic hooks  341  and  342  for securing the second end portion  24  to the second supporting member  14 . To securely mount the second end portion  24  to the second supporting member  14 , the sleeve  340  is wedged into an opening  14 A of the second supporting member  14  and fastened to the second supporting member  14  by the elastic hooks  341  and  342 , such that the gear assembly  30  is immovable in the axial direction DAx of the rotating shaft  20 . The gear member  32  includes a hollow body  32 E for accommodating the second end portion  24  of the rotating shaft  20 . The second end portion  24  passes through the hollow body  32 E. In addition, the gear member  32  may further include a flange  32 C, disposed between the gear teeth  32 A and  32 B, for restricting the position of the belt  80 . 
     In addition, the sheet transporting apparatus  1  may further include a scanning module  50  and/or a scanning module  50 ′. The scanning modules  50  and  50 ′, disposed in the housing  10 , scan images on two sides of the document sheet S transported by the roller  40 . 
     As shown in  FIGS. 2A and 2B , the first end portion  22  of the rotating shaft  20  includes a small-diameter section  22 A and a large-diameter section  22 B coaxially disposed with the small-diameter section  22 A. The diameter of the small-diameter section  22 A is smaller than the diameter of the large-diameter section  22 B, and the small-diameter section  22 A is seated within an opening  12 A of the first supporting member  12 . Thus, the axial movement of the rotating shaft  20  may be restricted to prevent the rotating shaft  20  from getting loose. The two end portions  22  and  24  of the rotating shaft  20  may be respectively seated within the first opening  12 A and the opening (also referred to as a second opening)  14 A of the second supporting member  14 . The second end portion  24  passes through the second opening  14 A. The gear assembly  30  is coupled to the second end portion  24  by wedging into the second opening  14 A in the direction as indicated by the arrow of  FIG. 2B .  FIG. 2A  shows a resulting integration of the gear assembly  30  and the rotating shaft  20 , where the rotating shaft  20  is securely fixed to second supporting member  14 . 
     As shown in  FIG. 3 , the gear assembly  30  is inserted into the second opening  14 A of the second supporting member  14  from the outside of the housing  10 , and the elastic hooks  341  and  342  of the coupling member  34  of the gear assembly  30  pass through the second opening  14 A and hook the second supporting member  14  from the inside. An outer periphery  34 A of the coupling member  34  of the gear assembly  30  rests against an inner peripheral wall  14 B of the second opening  14 A of the second supporting member  14 . 
     A surface  31  of the gear assembly  30  facing a wall  14 W of the second supporting member  14  is formed with a plurality of projections  31 A and the plurality of projections are in direct contact with the second supporting member  14 , so that the friction between the gear assembly  30  and the surface  31  would be well reduced. 
       FIG. 4  is a cross-sectional view taken along a line  4 - 4  of  FIG. 3 . As shown in  FIG. 4 , the hollow body  32 E has a D-shaped cavity  32 D. The second end portion  24  has a D-shaped cross section  24 D matching with the D-shaped cavity  32 D to fix the gear assembly  30  to the rotating shaft  20 , so that the rotating shaft  20  is driven by the gear assembly  30 . In addition, a set screw or other means may also be handled to fix the gear assembly  30  to the rotating shaft  20 . According to the above-mentioned design, the rotating shaft  20  may be secured to the housing  10  as well as being driven by the gear assembly  30 . 
     The operations of the sheet transporting apparatus of the invention will be described in the following. The driving gear  90  attached to a motor (not shown) rotates the gear assembly  30  through the gear teeth  32 B, and the gear assembly  30  rotates the belt  80  and the gear teeth  32 A′ through the gear teeth  32 A. Thus, the rollers  40  and  40 ′ can rotate the driven rollers  70  and  70 ′ synchronously to transport the document sheet S past the scan regions of the scanning modules  50  and  50 ′, so that the scanning modules  50  and  50 ′ can scan the images of the document sheet S. 
     With the sheet transporting apparatus of the invention, the rotating shaft may be rotatably mounted in the housing by coupling with the gear assembly, without using any tools, and the coupling member of the gear assembly can function as a bearing. Thus, the components used in the prior art, including the E-rings and the bearings, are dispensable, and no further metal working has to be done to machine ring-shaped grooves into the ends of the rotating shaft. In addition, to the same degree of precision as in the prior art, the coupling portion of the rotating shaft and the gear assembly is tightly fitted to the opening of the supporting member within which the rotating shaft is seated. Furthermore, no tool is required to remove the gear assembly from the apparatus, and users could unfasten the gear assembly simply by pressing the two elastic hooks inwards. Thus, the sheet transporting apparatus of the invention not only retains the quality of high precision in the installation of the components, but also reduces the associated material and machining costs. 
     While the invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications.