Abstract:
An ADF with simple structure includes an input tray and elastic film. The input tray is for receiving a document to be fed and the elastic film disposed upon the input tray is for supporting the document to be fed by bounce. The elastic film includes a jointing portion for fixing the elastic film onto the input tray and a supporting portion forming an angle with the input tray for supporting the document to be fed. The elastic film further includes a bending portion, wherein one end of the bending portion connects to the supporting portion and the other end of bending portion bends towards the input tray.

Description:
This application incorporates by reference Taiwanese application Serial No. 089222406, Filed Dec. 22, 2000. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates in general to an Automatic Document Feeder (ADF), and more particularly to an ADF using a supporting structure for feeding documents smoothly. 
     2. Description of the Related Art 
     Feeding documents smoothly is important for every machine equipped with an ADF (Automatic Document Feeder), such as scanners, printers, facsimile machines or the like. The scanner with an ADF can carry a large amount of documents ready for use at a time, which is more efficient than the flatbed scanner does. Compared with the traditional machine, which is restricted by the image processing speed and memory capacity, the machine nowadays, requires more documents at a time for an efficient and timesaving operation, especially for office automation. However, there are restrictions of the traditional feeding device under some circumstances. For example, the document to be fed might not contact with the feed roller for being carried when the space of the input tray is large but there are only a little documents put in the input tray. The supporting structure is therefore developed for being fixed on the input tray. 
     Referring to FIG. 1A, a cross-sectional view of a conventional ADF is illustrated. As shown in FIG. 1A, the ADF  100  may be applied in scanners, printers, facsimile machines or the like for feeding the document  102  to the machines. The ADF  100  includes an input tray  104 , a feed roller  106 , a feed pad  110 , a flat board  108  and a spring  111 . The input tray  104  is for receiving a document  102 . One end of the flat board  108  is pivoted on the input tray  104  by a hinge  115 . Besides, one end of the spring  111  is fixed on the flat board  108  while the other end of the spring  111  is fixed on the notch  113  of the input tray  104 . The flat board  108  and the input tray  104  therefore form an angle θ 1 . The rim of the feed roller  106  touches the feed pad  110 . The feed roller  106  and the feed pad  110  therefore create a feeding end  112 . When the feed roller  106  rotates around the axis  116 , the feed roller  106  drives the document  102  to advance by fiction. The more documents the flat board  108  carries, the smaller the angle θ 1  is. The flat board  108  supports the document  102  by the elasticity of the spring  111 . The leading edge of the document  102  gets into the feeding end  112  so that the feed roller  106  can drive the document  102  to advance while rotating. 
     Referring to FIG. 1B, a cross-sectional view of the ADF in FIG. 1A which carries a stack of documents is shown. As shown in FIG. 1B, documents  114  are placed on the input tray  104 . The documents  114  include a document  102   a , document  102   b , documents  114   a  and document  102   c . The documents  114  in FIG. 1B are a stack of paper and the document  102  in FIG. 1A is a sheet. The documents  114  are therefore heavier than the document  102 . Besides, the gravity of the stack of paper  114  downward is far larger than the elasticity of the elastic film  108  upward. The angle θ 2  between the flat board  108  and the input tray  104  is less than θ 1 . The leading edge of the document  102   a  gets into the feeding end  112 . 
     When the feed roller  106  starts to rotate around the axis  116 , the feed roller  106  drives the document  102   a  to advance toward the feeding end  112 . After the document  102   a  completely passes through the feeding end  112 , the elasticity from the spring  111  pushes the document  102   b  upward for getting into the feeding end  112 . The document  102   b  is then driven to pass through the feeding end  112  by the feed roller  106 . The same operation will be proceeded and the amount of the documents  114  therefore gradually decreases, meanwhile, the angle θ 2  between the flat board  108  and the input tray  104  becomes larger. The feed roller  106  drives the rest of documents put on the input tray  104  to advance toward the feed end  112  sequentially. 
     After the feed roller  106  drives the document  102   a , document  102   b  and documents  114   a  to sequentially pass through the feeding end  112  and to be completely fed into the machine (not shown). The last document  102   c  is left on the input tray  104  and the angle θ 2  between the flat board  108  and the input tray  104  becomes equal to θ 1  due to the upward elasticity of the spring  111 . The leading edge of document  102   c  gets into the feeding end  112  for being fed  102  and the feeding process of the ADF  100  is therefore finished. 
     Nevertheless, the ADF  100  stated above with a pivotal flat board, hinge and spring is structurally complex, costly and difficult to assemble during manufacturing. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide an Automatic Document Feeder with an elastic film for supporting the documents put on the input tray, the documents are able to be carried by the feed roller for being fed smoothly and sequentially. 
     The invention achieves the above-identified objects by providing an ADF, which includes an input tray and elastic film. The input tray is for receiving a document or documents to be fed and the elastic film disposed upon the input tray is for supporting the document or documents to be fed by bounce. The elastic film includes a jointing portion for fixing the elastic film onto the input tray and a supporting portion forming an angle with the input tray for supporting the document or documents to be fed. The elastic film further includes a bending portion, wherein one end of the bending portion connects to the supporting portion and the other end of bending portion bends towards the input tray. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The description is made with reference to the accompanying drawings in which: 
     FIG. 1A (Prior Art) illustrates a cross-sectional view of a conventional ADF; 
     FIG. 1B (Prior Art) shows a cross-sectional view of the conventional ADF in FIG. 1A, which carries a stack of documents; 
     FIG. 2A is a cross-sectional view of an ADF according to a preferred embodiment of the invention; 
     FIG. 2B shows a cross-sectional view of the ADF in FIG. 2A, which carries a stack of documents; 
     FIG. 3A is a cross-sectional view of an ADF according to another preferred embodiment of the invention; and 
     FIG. 3B shows a cross-sectional view of the ADF in FIG. 3A, which carries a stack of documents. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 2A, an ADF according to a preferred embodiment of the invention is shown. The ADF (Automatic Document Feeder)  200  may be applied in scanners, printers, facsimile machines or the like for feeding the document  202  to the machines. The ADF according to the invention includes an input tray  204 , a feed roller  206 , a feed pad  210  and an elastic film  208 . The input tray  204  is for receiving a document to be fed. The elastic film  208  disposed upon the input tray  204  supports the document  202  by bounce. The feed pad  210  connects to the bottom of the input tray  204  for abutting against the document  202  at its leading edge. The rim of the feed roller  206  touches the feed pad  210 . The feed roller  206  and the feed pad  210  therefore create a feeding end  212 . When the feed roller  206  rotates around the axis  216 , the feed roller  206  drives the document  202  to advance by fiction. The elastic film  208  further includes a jointing portion  208   a  and a supporting portion  208   b . The jointing portion  208   a  fixes the elastic film  208  onto the input tray  204 . The supporting portion  208   b  supports the document  202  and forms an angle β 1  with the input tray  204 . The more documents the elastic film  208  carries, the smaller the angle β 1  is. The elastic film  208  supports the document  202  by bounce. The leading edge of the document  202  gets into the feeding end  212  so that the feed roller  206  can drive the document  202  to advance while rotating. 
     Referring to FIG. 2B, a cross-sectional view of the ADF in FIG. 2A which carries a stack of documents is shown. In FIG. 2B, documents  214  are placed on the input tray  204 . The documents  214  include a document  202   a , document  202   b , documents  214   a  and document  202   c . The documents  214  in FIG. 2B are a stack of paper and the document  202  in FIG. 2A is a sheet. The documents  214  are therefore heavier than the document  202 . Besides, the gravity of the stack of paper  214  downward is far larger than the elasticity of the elastic film  208  upward. The angle β 2  (not shown in FIG. 2B) between the supporting portion  208   b  and the input tray  204  is less than β 1 . It causes the supporting portion  208   b  of the elastic film  208  approaches the input tray  204  and the leading edge of the document  202   a  can neatly get into the feeding end  212 . 
     When the feed roller  206  starts to rotate around the axis  216 , the feed roller  206  drives the document  202   a  to advance toward the feeding end  212 . After the document  202   a  completely passes through the feeding end  212 , the elasticity of the elastic film  208  pushes the document  202   b , documents  214   a  and document  202   c  upward. The leading edge of the next document  202   b  neatly gets into the feeding end  212  and the document  202   b  is then driven to pass through the feeding end  212  by the feed roller  206 . The same operation will be done on each document. Therefore, the amount of the documents  214  gradually decreases, meanwhile, the angle β 2  between the supporting portion  208   b  and the input tray  204  becomes larger. The feed roller  206  can drive the rest of documents put on the input tray  204  to advance and to be fed smoothly and sequentially by the support of the elastic film  208 . 
     After the feed roller  206  drives the document  202   a , document  202   b  and documents  214   a  to sequentially pass through the feeding end  212  and be completely fed into the machine. The last document  202   c  is left on the input tray  204  and the angle β 2  between the supporting portion  208   b  and the input tray  204  becomes equal to β 1  due to the upward elasticity of the elastic film  208 . The leading edge of document  202   c  can get into the feeding end  212  and the feeding process of the ADF  200  is therefore finished. 
     Referring to FIG. 3A, an ADF according to another preferred embodiment of the invention is shown. The ADF may be applied in scanners, printers, facsimile machines or the like for feeding the document  302  to the machines. As shown in FIG. 3A, the ADF  300  according to the invention includes an input tray  304 , a feed roller  306 , a feed pad  310  and an elastic film  308 . The input tray  304  is for receiving a document  302 . The elastic film  308  disposed upon the input tray  304  supports the document  302  by bounce. The feed pad  310  connects to the bottom of the input tray  304  for abutting against the document  302  at its leading edge. The rim of the feed roller  306  touches the feed pad  310 . The feed roller  306  and the feed pad  310  therefore create a feeding end  312 . When the feed roller  306  rotates around the axis  316 , the feed roller  306  drives the document  302  to advance by friction. The elastic film  308  further includes a jointing portion  308   a , a supporting portion  308   b  and a bending portion  308   c . The jointing portion  308   a  fixes the elastic film  308  onto the input tray  304 . The supporting portion  308   b  supports the document  302  and forms an angle β 3  with the input tray  304 . The supporting portion  308   b  and the bending portion  308   c  are linked together and form an angle α. The angle α is stationary or variable while the angle β 3  is variable. Besides, one end of the bending portion  308   c  gets into the notch  313  of the input tray  304  and slides down the notch  313  while the supporting portion  308   b  is pressed by the document to be fed. As the elastic film  308  carries more and more documents, the angle β 3  becomes less and less as well as the bending portion  308   c  moves deeper and deeper inside the notch  313 . The elastic film  308  supports the document  302  by bounce. The leading edge of the document  302  gets into the feeding end  312  so that the feed roller  306  can drive the document  302  to advance while rotating. 
     Referring to FIG. 3B, a cross-sectional view of the ADF in FIG. 3A which carries a stack of documents is shown. In FIG. 3B, documents  314  are placed on the input tray  304 . The documents  314  include a document  302   a , document  302   b , documents  314   a  and document  302   c . The documents  314  in FIG. 3B are a stack of paper and the document  302  in FIG. 3A is a sheet. The documents  314  are therefore heavier than the document  302 . Besides, the gravity of the stack of paper  314  downward is far larger than the elasticity of the elastic film  308  upward. The angle β 4  (not shown in FIG. 3B) between the supporting portion  308   b  and the input tray  304  is less than β 3 . The bending portion  308   c  moves insides the notch  313  so that it causes the supporting portion  308   b  approaches the input tray  304  and the bending portion  308   c  almost gets into the notch  313 . Meanwhile, the leading edge of the document  302   a  can neatly get into the feeding end  312  and the leading edges of the documents  314  touches the feeding pad  310 . 
     When the feed roller  306  starts to rotate around the axis  316 , the feed roller  306  drives the document  302   a  to advance toward the feeding end  312 . After the document  302   a  completely passes through the feeding end  312 , the elasticity of the elastic film  308  pushes the document  302   b , documents  314   a  and document  302   c  upward. The leading edge of the next document  302   b  neatly gets into the feeding end  312  and the document  302   b  is then driven to pass through the feeding end  312  by the feed roller  306 . The same operation will be done on each document. Therefore, the amount of the documents  314  gradually decreases, meanwhile, the angle β 4  between the supporting portion  308   b  and the input tray  304  becomes larger. The feed roller  306  can drive the rest of documents put on the input tray  304  to advance and to be fed smoothly and sequentially by the support of the elastic film  308 . 
     After the feed roller  306  drives the document  302   a , document  302   b  and documents  314   a  to sequentially pass through the feeding end  312  and be completely fed into the machine. The last document  302   c  is left on the input tray  304  and the angle β 4  between the supporting portion  308   b  and the input tray  304  becomes equal to β 3  due to the upward elasticity of the elastic film  308 . The leading edge of document  302   c  can get into the feeding end  312  for being fed by the driving of the feed roller  306  and the feeding process of the ADF  300  is therefore finished. 
     The elastic film is a polyester film and preferably a Mylar. In addition, the elastic film is firmly attached to the input tray so that the elastic film would not be loosed or damaged by the friction produced by the moving document. 
     While the invention has been described by way of example and in terms of the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. To the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.