Abstract:
The present invention relates to an ejecting roller assembly for use in an automatic document feeder to adaptively adjust the nip force between the follower roller and the driving roller in response to input and output of the paper sheet, there effectively preventing the paper sheet from getting jammed. The ejecting roller assembly includes a swing lever, a follower roller, a friction-generating element and a driving roller. The swing lever is coupled to the follower roller for adaptively adjusting the nip force. The friction-generating element is arranged between the swing lever and the follower roller for facilitating increasing the friction force between the swing lever and the follower roller. The driving roller is used for controlling input and output of the paper sheet.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an ejecting roller assembly, and more particularly to an ejecting roller assembly for use in an automatic document feeder. 
       BACKGROUND OF THE INVENTION 
       [0002]    Image scanning apparatuses such as image scanners, copiers, printers and multi function peripherals (MFPs) are widely used in our daily lives or offices for scanning images of objects such as paper sheets. As known, the image scanning apparatus usually has an automatic document feeder for automatically and continuously feeding many paper sheets one by one. During operation of the automatic document feeder, the paper sheet is readily jammed, especially in the vicinity of the ejecting roller assembly. 
         [0003]    Referring to  FIG. 1 , a schematic cross-sectional view of a conventional automatic document feeder is illustrated. The automatic document feeder  200  principally includes a paper input tray  202 , a paper ejecting tray  204 , a pick-up roller assembly  210 , a transfer roller assembly  220 , an inner roller assembly  230 , an ejecting roller assembly  240 , a first transfer path  250  and a second transfer path  260 . The ejecting roller assembly  240  includes a driving roller  241  and a follower roller  242 . The driving roller  241  and the follower roller  242  are fixed within the automatic document feeder  200  and in contact with each other to provide a specified nip force therebetween. 
         [0004]      FIG. 2A  is a schematic cross-sectional view illustrating that the paper sheet is transported out of the automatic document feeder.  FIG. 2B  is a schematic cross-sectional view illustrating that the paper sheet is transported into the automatic document feeder. 
         [0005]    Hereinafter, the procedure of performing a single-side scanning operation by the automatic document feeder  200  will be illustrated with reference to  FIG. 2A . First of all, the paper sheet  206  to be scanned is placed in the sheet input tray  202 . The pick-up roller assembly  210  transports the paper sheet  206  into the first transfer path  250  (as indicated in  FIG. 1 ). The paper sheet  206  is successively transported by the transfer roller assembly  220 , the inner roller assembly  230  and the ejecting roller assembly  240 . When the paper sheet  206  is transported across a scan region (not shown) in the first transfer path  250 , a first side of the paper sheet  206  is scanned by a scanning module (not shown) under the scan region. Next, the driving roller  241  of the ejecting roller assembly  240  is rotated in an anti-clockwise direction to have the paper sheet  206  eject to the paper ejecting tray  204 . 
         [0006]    Hereinafter, the procedure of performing a duplex scanning operation by the automatic document feeder  200  will be illustrated with reference to  FIG. 2B . After the first side of the paper sheet  206  is scanned by using the above produce and a majority of the paper sheet  206  is ejected to the paper ejecting tray  204 , the driving roller  241  of the ejecting roller assembly  240  is reversely rotated in the clockwise direction, so that the paper sheet is transported into the second transfer path  260  (as indicated in  FIG. 1 ). Next, the paper sheet  206  is successively transported by the transfer roller assembly  220 , the inner roller assembly  230  and the ejecting roller assembly  240 . When the paper sheet  206  is transported across the scan region, a second side of the paper sheet  206  is scanned by the scanning module. Next, the driving roller  241  of the ejecting roller assembly  240  is rotated in the anti-clockwise direction to have the paper sheet  206  eject to the paper ejecting tray  204 . 
         [0007]    Generally, the driving roller  241  and the follower roller  242  need to be in contact with each other so as to provide sufficient nip force for transmitting the paper sheet  206  into or out from the inner portion of the automatic document feeder  200 . In a case that the nip force is too large, the paper sheet fails to be smoothly transferred across the region between the driving roller  241  and the follower roller  242 , and thus the paper sheet is readily jammed. For preventing the paper sheet  206  from getting jammed between the driving roller  241  and the follower roller  242 , the driving roller  241  and the follower roller  242  needs to be in loose contact with each other. Under this circumstance, the nip force may be insufficient for transmitting the paper sheet  206  into or out from the inner portion of the automatic document feeder  200 . Moreover, since the driving roller  241  and the follower roller  242  of the ejecting roller assembly  240  are fixed within the automatic document feeder  200 , it is difficult to adjust the nip force as required. 
         [0008]    Therefore, there is a need of providing an ejecting roller assembly for used in an automatic document feeder to effectively prevent the paper sheet from getting jammed. 
       SUMMARY OF THE INVENTION 
       [0009]    It is an object of the present invention to provide an ejecting roller assembly for use in an automatic document feeder to adaptively adjust the nip force between the follower roller and the driving roller in response to input and output of the paper sheet, there effectively preventing the paper sheet from getting jammed. 
         [0010]    In accordance with an aspect of the present invention, there is provided an ejecting roller assembly for use in an automatic document feeder to transport a paper sheet. The ejecting roller assembly includes a swing lever, a follower roller, a friction-generating element and a driving roller. The swing lever has a first end coupled to the automatic document feeder such that the swing lever is pivotal about the first end. The follower roller is coupled to a second end of the swing lever. The friction-generating element is arranged between the swing lever and the follower roller for facilitating increasing the friction force between the swing lever and the follower roller. The driving roller is coupled to the automatic document feeder. When the paper sheet is transported therebetween in an inward direction, the follower roller has a tendency to be close to the driving roller, such that the nip force between the follower roller and the driving roller is increased. When the paper sheet is transported therebetween in an outward direction, the follower roller has a tendency to be away from the driving roller, such that the nip force between the follower roller and the driving roller is reduced. 
         [0011]    The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a schematic cross-sectional view of a conventional automatic document feeder; 
           [0013]      FIG. 2A  is a schematic cross-sectional view illustrating that the paper sheet is transported out of the automatic document feeder; 
           [0014]      FIG. 2B  is a schematic cross-sectional view illustrating that the paper sheet is transported into the automatic document feeder; and 
           [0015]      FIG. 3  is a schematic cross-sectional view of an automatic document feeder according to a preferred embodiment of the present invention; 
           [0016]      FIG. 4A  is a schematic cross-sectional view illustrating that the paper sheet is transported across the ejecting roller assembly in the outward direction; 
           [0017]      FIG. 4B  is a schematic cross-sectional view illustrating that the paper sheet is transported across the ejecting roller assembly in the inward direction; 
           [0018]      FIG. 5  is a schematic cross-sectional view of an automatic document feeder according to another preferred embodiment of the present invention; and 
           [0019]      FIG. 6  is a schematic exploded view of an ejecting roller assembly according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    Referring to  FIG. 3 , a schematic cross-sectional view of an automatic document feeder according to a preferred embodiment of the present invention is illustrated. The automatic document feeder  300  principally includes a paper input tray  302 , a paper ejecting tray  304 , a pick-up roller assembly  310 , a transfer roller assembly  320 , an inner roller assembly  330 , an ejecting roller assembly  340 , a first transfer path  350  and a second transfer path  360 . The ejecting roller assembly  340  includes a swing lever  342 , a follower roller  345 , a friction-generating element (not shown) and a driving roller  348 . The swing lever  342  includes a first end  343  fixed to the automatic document feeder  300  and a second end  344  coupled to the follower roller  345 . 
         [0021]    Hereinafter, a process of adaptively adjusting the nip force between the follower roller  345  and the driving roller  348  in response to input and output of the paper sheet will be illustrated as follows with reference to  FIG. 4A and 4B . The arrangement of the ejecting roller assembly  340  will be illustrated later. 
         [0022]      FIG. 4A  is a schematic cross-sectional view illustrating that the paper sheet is transported across the ejecting roller assembly  340  in the outward direction. First of all, the paper sheet  306  to be scanned is placed in the sheet input tray  302 . The pick-up roller assembly  310  transports the paper sheet  306  into the first transfer path  350  (as indicated in  FIG. 3 ). The paper sheet  306  is successively transported by the transfer roller assembly  320 , the inner roller assembly  330  and the ejecting roller assembly  340 . When the paper sheet  306  is transported across a scan region (not shown) in the first transfer path  350 , a first side of the paper sheet  306  is scanned by a scanning module (not shown) under the scan region. Next, the driving roller  348  of the ejecting roller assembly  340  is rotated in the anti-clockwise direction to eject the paper sheet  306  in the outward direction  370 . Since the rotating shaft (not shown) of the driving roller  348  is fixed within the automatic document feeder  300 , the driving roller  348  is rotated with respect to the rotating shaft thereof when the paper sheet is transported across the ejecting roller assembly  340  in the outward direction  370 . Whereas, during the paper sheet  306  is transported across the ejecting roller assembly  340  in the outward direction  370 , the follower roller  345  has a tendency to be away from the driving roller  348  in the outward direction  370 . Since the displacement of the follower roller  345  is restrained by the swing lever  342 , an upward component of force is applied on the follower roller  345 . The upward component of force may reduce the nip force between the follower roller  345  and the driving roller  348 . Accordingly, the probability of causing jammed paper sheet is minimized. 
         [0023]      FIG. 4B  is a schematic cross-sectional view illustrating that the paper sheet is transported across the ejecting roller assembly  340  in the inward direction. After the first side of the paper sheet  306  is scanned by using the above produce and a majority of the paper sheet  306  is ejected to the paper ejecting tray  304 , the driving roller  348  of the ejecting roller assembly  340  is reversely rotated in the clockwise direction, so that the paper sheet is transported into the second transfer path  360  (as indicated in  FIG. 3 ) in the inward direction  380 . Likewise, the driving roller  348  is rotated with respect to the rotating shaft thereof when the paper sheet is transported across the ejecting roller assembly  340  in the inward direction  380 . Whereas, during the paper sheet  306  is transported across the ejecting roller assembly  340  in the inward direction  380 , the follower roller  345  has a tendency to be close to the driving roller  348  in the inward direction  380 . Since the displacement of the follower roller  345  is restrained by the swing lever  342 , a downward component of force is applied on the follower roller  345 . The downward component of force may increase the nip force between the follower roller  345  and the driving roller  348 . Accordingly, the paper sheet may be smoothly transported into the second transfer path  360  of the automatic document feeder  300 . 
         [0024]    Please refer to  FIG. 4A  and  FIG. 4B . The first end  343  of the swing lever  342  is coupled to a first position of the automatic document feeder  300 , which is disposed above the driving roller  348  and slants toward the internal side of the automatic document feeder  300 . During the paper sheet  306  is transported across the ejecting roller assembly  340  in the outward direction  370 , an upward component of force is applied on the follower roller  345  and thus the probability of causing jammed paper sheet is minimized. Whereas, during the paper sheet  306  is transported across the ejecting roller assembly  340  in the inward direction  380 , a downward component of force is applied on the follower roller  345  and thus the paper sheet will be smoothly transported into the second transfer path  360  of the automatic document feeder  300 . 
         [0025]    Referring to  FIG. 5 , a schematic cross-sectional view of an automatic document feeder according to another preferred embodiment of the present invention is illustrated. The automatic document feeder  500  of this embodiment is similar to that of the first preferred embodiment except for the arrangement of the swing lever. In this embodiment, the swing lever  542  includes a first end  543  fixed to the automatic document feeder  500  and a second end  544  coupled to the follower roller  545 . The first end  543  of the swing lever  542  is coupled to a second position of the automatic document feeder  500 , which is disposed under the driving roller  548  and slants toward the external side of the automatic document feeder  500 . Likewise, during the paper sheet is transported across the ejecting roller assembly  540  in the outward direction, a downward component of force is applied on the follower roller  545  and thus the probability of causing jammed paper sheet is minimized. Whereas, during the paper sheet is transported across the ejecting roller assembly  540  in the inward direction, an upward component of force is applied on the follower roller  545  and thus the paper sheet will be smoothly transported into the second transfer path of the automatic document feeder  500 . 
         [0026]    Referring to  FIG. 6 , a schematic exploded view of an ejecting roller assembly according to the present invention is illustrated. The ejecting roller assembly principally comprises a hinge stand  600 , a swing lever  642 , a friction-generating element  646 , a follower roller  645 , a rotating shaft  604  and a driving roller  648 . The first end  643  of the swing lever  642  is a hinge coupled to the hinge stand  600  such that the swing lever  642  is pivotal about the first end  643 . The friction-generating element  646  is a spiral spring. The spiral spring  646  and the follower roller  645  are sheathed around the rotating shaft  604 . Both terminals of the rotating shaft  604  are fixed onto the second end  644  of the swing lever  642 . Both terminals of the spiral spring  646  are sustained between the second end  644  of the swing lever  642  and a sidewall of the follower roller  645 . The friction-generating element  646  may increase the frictional force between the follower roller  645  and the swing lever  642 . Since the frictional force between the follower roller  645  and the swing lever  642  is increased, the effectiveness of obtaining upward or downward component of force is enhanced when the paper sheet is transported across the ejecting roller assembly. Accordingly, the nip force between the follower roller  645  and the driving roller  648  is adaptively adjusted. 
         [0027]    It is noted that, however, those skilled in the art will readily observe that numerous modifications and alterations of the ejecting roller assembly may be made while retaining the teachings of the invention. For example, the hinge stand may be replaced by two retaining recess structures and the first end of the swing lever may have a channel therein. After a retaining rod is penetrated through the channel and the both terminals thereof are embedded into the retaining recess structures, the swing lever is pivotal about the first end. Moreover, the friction-generating element may be made of other elastic material such as resilient sheet, rubber or foam. For example, in a case that the friction-generating element is a foam-made sleeve, the foam-made sleeve is sheathed around the rotating shaft and also sustained between the second end of the swing lever and a sidewall of the follower roller. In another case that the friction-generating element is a resilient sheet having a body portion and an arm portion, the body portion is coupled to the first end of the swing lever and the arm portion is coupled to the follower roller. In a further case that the friction-generating element is a rubbery sheet, the surface of the rotating shaft is covered with the rubbery sheet and the rubbery sheet is arranged between the rotating shaft and the follower roller, thereby increasing the friction between the rotating shaft and the follower roller. 
         [0028]    While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.