Patent Publication Number: US-2005133984-A1

Title: Automatic document feeder

Description:
This application claims the benefit of Taiwan application Serial No. 92132644, filed Nov. 20, 2003, the subject matter of which is incorporated herein by reference.  
     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 automatic document feeder which disposes a bearing board on an elastic structure of a sloping paper feeding tray.  
      2. Description of the Related Art  
      Referring to  FIG. 1A , a cross-sectional view of the structure of a conventional automatic document feeder (ADF) is shown. In  FIG. 1A , an automatic document feeder  100 , which includes a horizontal paper feeding tray  104 , an automatic paper feeding roller set  106 , a paper supporting plate  108  and a spring  111 , for feeding a to-be-fed paper sheet  102  into an office machine (not shown in  FIG. 1A ) such as a printer, a copier, a scanner or a facsimile machine is shown. The horizontal paper feeding tray  104  is for accommodating the to-be-fed paper sheet  102 . A feeding end  112  is formed by a flange of the automatic paper feeding roller set  106  and a paper feeding pad  110 , wherein the flange of the automatic paper feeding roller set  106  and the paper feeding pad  110  are adjacent to and in contact with each other. The automatic paper feeding roller set  106  rotates clockwise around the roller shaft  116  and carries the to-be-fed paper sheet  102  to move forward. The paper supporting plate  108 , with its one end being pivotally connected to the horizontal paper feeding tray  104 , is able to turn around on the horizontal paper feeding tray  104 . One end of the spring  111  is fixed at a slot  113  of the horizontal paper feeding tray  104  while the other end of the spring  111  is fixed onto the bottom of the other end of the paper supporting plate  108 , forming an included angle θ 1  between the paper supporting plate  108  and the horizontal paper feeding tray  104 .  
      Referring to  FIG. 1B , a cross-sectional view of the structure of the automatic document feeder of  FIG. 1A  with a paper stack  114  being loaded therein is shown. In  FIG. 1B , the paper stack  114  is placed on the horizontal paper feeding tray  104 , wherein the paper stack  114  includes a paper sheet  102   a , a paper sheet  102   b , a paper stack  114   a  and a paper sheet  102   c  according to a top-down arrangement. Since the gravity of the paper stack  114  is much larger than that of the single to-be-fed paper sheet  102  in  FIG. 1A , the included angle between the paper supporting plate  108  and the horizontal paper feeding tray  104  in  FIG. 1B  is smaller than the included angle θ 1  in  FIG. 1A . Furthermore, since the paper stack  114  weighs heavier, the spring  111  must have a larger elasticity so that the front end of the paper stack  114  may be raised up to the paper feeding pad  110  with the front end of the paper sheet  102   a  just reaching the feeding end  112 .  
      After the automatic paper feeding roller set  106  has fed the paper sheets  102   a  and  102   b  and the paper stack  114   a  into the office machine in succession, only the paper sheet  102   c  will be left in the horizontal paper feeding tray  104  like the case in  FIG. 1A . By means of the upward elasticity of the spring  111 , the included angle between the paper supporting plate  108  and the horizontal paper feeding tray  104  is expanded to be θ 1 , so that the paper sheet  102   c  is raised up with the front end of the paper sheet  102   c  reaching the feeding end  112 . Consequently, the automatic paper feeding roller set  106  may carry the paper sheet  102   c  towards the feeding end  112 . The step of automatic document feeding of the automatic document feeder  100  is completed here.  
      Since the structure of the horizontal paper feeding tray  104  adopts a horizontal design, the spring  111  must provide an upward elasticity to support the weight of the paper sheets and to enable the paper supporting plate  108  to raise the paper sheets up so that the front ends of the paper sheets may reach the feeding end  112 . When the number of paper sheets placed on the paper supporting plate  108  becomes larger, the elasticity of the spring  111  needs to be enhanced accordingly to assure that the topmost paper sheet may reach the feeding end  112 . Since the assembly mechanism of the horizontal paper feeding tray  104 , the spring  111  and the paper supporting plate  108  is very complicated, the assembly is costly and is difficult to be done during the manufacturing process.  
      Referring to  FIG. 2A , a cross-sectional view of the structure of an automatic document feeder  200  disclosed in Taiwanese patent publication number 509143 is shown. In  FIG. 2A , an automatic document feeder  200 , which includes a sloping paper feeding tray  204 , a automatic paper feeding roller set  206  and a Mylar  208 , is for feeding a to-be-fed paper sheet  202  into an office machine (not shown in  FIG. 2A ) such as a printer, a copier, a scanner or a facsimile machine is shown. The sloping paper feeding tray  204  is for accommodating the to-be-fed paper sheet  202 . Both the automatic paper feeding roller set  206  and the paper feeding pad  210  are disposed at the bottom of the sloping paper feeding tray  204 . A feeding end  212  is formed by a flange of the automatic paper feeding roller set  206  and the paper feeding pad  210 , wherein the flange of the automatic paper feeding roller set  206  and the paper feeding pad  210  are adjacent to and in contact with each other. Moreover, the automatic paper feeding roller set  206  rotates clockwise around a roller shaft  216  and carries the to-be-fed paper sheet  202  to move forward. The Mylar  208  further includes a junction portion  208   a  and a supporting portion  208   b , wherein the junction portion  208   a  is flatly adhered onto the sloping paper feeding tray  204  while an included angle β 1  is formed between the supporting portion  208   b  and the sloping paper feeding tray  204 . As more paper sheets are placed on the Mylar  208 , the included angle between the supporting portion  208   b  and the sloping paper feeding tray  204  becomes smaller. By means of the structural elasticity, the Mylar  208  is able to support the to-be-fed paper sheet  202 . Availed by the sloping design of the structure of the sloping paper feeding tray  204 , the front end of the to-be-fed paper sheet  202  may slide to reach the feeding end  212  due to gravity, so that the automatic paper feeding roller set  206  may carry the to-be-fed paper sheet  202  to move towards the feeding end  212 .  
      Referring to  FIG. 2B , a cross-sectional view of the structure of an automatic document feeder  200  in  FIG. 2A  with a paper stack  214  being loaded therein is shown. In  FIG. 2B , the paper stack  214  including two paper sheets  202   a  and  202   b , a paper stack  214   a  and a paper sheet  202   c  arranged in a top-down order is loaded in a sloping paper feeding tray  204 . Since the downward gravity of the paper stack  214  is larger than the gravity of the single to-be-fed paper sheet  202  in  FIG. 2A  and the upward elasticity of the Mylar  208  as well, the included angle between the supporting plate  208   b  and the sloping paper feeding tray  204  is smaller than β 1 . Furthermore, the bottom of the supporting portion  208   b  of the Mylar  208  may come into contact with the sloping paper feeding tray  204 . Meanwhile, the front end of the paper stack  214  comes into contact with the paper feeding pad  210  with the front end of the paper sheet  202   a  just reaching the feeding end  212 .  
      After the paper sheets  202   a  and  202   b  and the paper stack  214   a  are sequentially carried by the paper feeding roller set  206  and fed into the office machine, only the paper sheet  202   c  will be left on the sloping paper feeding tray  204  like the case in  FIG. 2A . Owing to the upward elasticity of the Mylar  208 , the included angle between the supporting portion  208   b  and the sloping paper feeding tray  204  is expanded and becomes β 1  so that the paper sheet  202   c  is raised upward with the front end of the paper sheet  202   c  reaching the feeding end  212 . Consequently, the automatic paper feeding roller set  206  may carry the paper sheet  202   c  to move towards the feeding end  212 . The step of automatic document feeding of the automatic document feeder  200  is completed here.  
      However, the Mylar  208 , which has a fragile structure and is directly exposed on the sloping paper feeding tray  204 , will be easily worn out in the long run and is likely to be damaged by a careless operator. Once the Mylar  208  is damaged, the automatic document feeder  200  cannot function properly and needs to be repaired, boosting the repair and maintenance cost even higher.  
     SUMMARY OF THE INVENTION  
      It is therefore an object of the invention to provide an automatic document feeder whose design of disposing a bearing board on a sloping paper feeding tray not only protects the Mylar disposed under the supporting plate from being damaged but also reduces the damage rate of the Mylar, so that the lifespan of the Mylar may be lengthened and a stable operation of the automatic document feeder may be achieved  
      It is therefore another object of the invention to provide an automatic document feeder including a sloping paper feeding tray, a bearing board and an elastic structure. The sloping paper feeding tray is for accommodating a to-be-fed paper sheet. The bearing board, with its one end being pivotally connected to the sloping paper feeding tray, is able to turn around on the sloping paper feeding tray, while the other end of the bearing board supports the to-be-fed paper sheet. The elastic structure, which is disposed between the sloping paper feeding tray and the bearing board, elastically supports the other end of the bearing board to create an included angle between the supporting plate and the sloping paper feeding tray. The elastic structure may be a Mylar or a spring for instance.  
      It is therefore another object of the invention to provide an automatic document feeder including a sloping paper feeding tray, a bearing board and a Mylar. The sloping paper feeding tray is for accommodating a to-be-fed paper sheet. The bearing board, with its one end being pivotally connected to the sloping paper feeding tray, is able to turn around on the sloping paper feeding tray, while the other end of the bearing board supports the to-be-fed paper sheet. The Mylar, which is disposed between the sloping paper feeding tray and the supporting plate, may elastically spring the other end of the bearing board so that an included angle is created between the bearing board and the sloping paper feeding tray. The Mylar includes a junction portion and a supporting portion with the junction portion being flatly adhered onto the sloping paper feeding tray. The supporting portion, which creates another included angle with the sloping paper feeding tray, elastically supports the bearing board.  
      Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1A  shows a cross-sectional view of the structure of a conventional automatic document feeder;  
       FIG. 1B  shows a cross-sectional view of the structure of the automatic document feeder of  FIG. 1A  with a paper stack being loaded therein;  
       FIG. 2A  shows a cross-sectional view of the structure of an automatic document feeder  200  disclosed in Taiwanese patent publication number 509143;  
       FIG. 2B  shows a cross-sectional view of the structure of an automatic document feeder  200  in  FIG. 2A  with a paper stack  214  being loaded therein;  
       FIG. 3A  shows a cross-sectional view of the structure of an automatic document feeder according to preferred embodiment one of the invention;  
       FIG. 3B  shows a cross-sectional view of the structure of the automatic document feeder of  FIG. 3A  with a paper stack being loaded therein;  
       FIG. 4A  shows a cross-sectional view of the structure of an automatic document feeder according to preferred embodiment two of the invention; and  
       FIG. 4B  shows a cross-sectional view of the structure of the automatic document feeder of  FIG. 4A  with a paper stack being loaded therein. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     PREFERRED EMBODIMENT ONE  
      Referring to  FIG. 3A , a cross-sectional view of the structure of an automatic document feeder  300  according to preferred embodiment one of the invention is shown. In  FIG. 3A , the automatic document feeder  300  includes a sloping paper feeding tray  304 , an automatic paper feeding roller set  306 , a paper feeding pad  310 , a bearing board  307  and an elastic structure, wherein the elastic structure may be a spring or a Mylar  308 . The automatic document feeder  300  is for feeding a to-be-fed paper sheet  302  into an office machine (not shown in  FIG. 3A ) such as a printer, a copier, a scanner or a facsimile machine. The sloping paper feeding tray  304  is for accommodating the to-be-fed paper sheet  302 . Both the automatic paper feeding roller set  306  and the paper feeding pad  310  are disposed at the bottom of the sloping paper feeding tray  304 . A feeding end  312  is formed by a flange of the automatic paper feeding roller set  306  and the paper feeding pad  310 , wherein the flange of the automatic paper feeding roller set  306  and the paper feeding pad  310  are adjacent to and in contact with each other. Moreover, the automatic paper feeding roller set  306  rotates clockwise around a roller shaft  316  and carries the to-be-fed paper sheet  302  to move forward.  
      The bearing board  307 , with its one end being pivotally connected to the sloping paper feeding tray  304 , is able to turn around on the sloping paper feeding tray, while the other end of the bearing board  307  supports the to-be-fed paper sheet  302 . The Mylar  308 , which is disposed between the sloping paper feeding tray  304  and the bearing board  307 , may elastically spring the other end of the bearing board  307  so that an included angle ω 1  is created between the bearing board and the sloping paper feeding tray.  
      The Mylar  308  includes a junction portion  308   a  and a supporting portion  308   b  with the junction portion  308   a  being flatly adhered onto the sloping paper feeding tray  304 . The supporting portion  308   b , which creates another included angle with the sloping paper feeding tray  304 , elastically supports the bearing board  307 . As more and more paper sheets are placed on the bearing board  307 , the included angle between the bearing board  307  and the sloping paper feeding tray  304  becomes smaller and so does the included angle between the supporting portion  308   b  and the sloping paper feeding tray  304 . The bearing board  307  uses the elasticity of the Mylar  308  to support the to-be-fed paper sheet  302  with the front end of the to-be-fed paper  302  reaching the feeding end  312 , so that the automatic paper feeding roller set  306  may carry the to-be-fed paper sheet  302  to move towards the feeding end  312 .  
      Referring to  FIG. 3B , a cross-sectional view of the structure of the automatic document feeder of  FIG. 3A  with a paper stack being loaded therein is shown. In  FIG. 3B , the paper stack  314  including a paper sheet  302   a , a paper sheet  302   b , a paper stack  314   a  and a paper sheet  302   c  arranged in a top-down order is loaded in a sloping paper feeding tray  304 . Since the downward gravity of the paper stack  314  is larger than the gravity of the single to-be-fed paper sheet  302  in  FIG. 3A  and the upward elasticity of the Mylar  308  as well, the included angle between the bearing board  307  and the sloping paper feeding tray  304  is smaller than ω 1 . Furthermore, the bottom of the supporting portion  308   b  of the Mylar  308  may even come into contact with the sloping paper feeding tray  304 . Meanwhile, the front end of the paper stack  314  comes into contact with the paper feeding pad  310  and the front end of the paper sheet  302   a  just reaches the feeding end  312 .  
      When the automatic paper feeding roller set  306  starts to rotate around a roller shaft  316 , the automatic paper feeding roller set  306  will carry the paper sheet  302   a  to move towards the feeding end  312  because the front end of the paper sheet  302   a  has reached the feeding end  312  already. After the paper sheet  302   a  has completely passed through the feeding end  312  and is carried forward by the automatic paper feeding roller set  306 , the upward elasticity of the Mylar  308  will bring the front end of the paper sheet  302   b  to reach the feeding end  312  to be carried forward by the automatic paper feeding roller set  306  like the case mentioned above. When fewer and fewer paper sheets are left at the paper stack  314 , the downward gravity of the paper stack  314  becomes smaller and smaller accordingly. Owing to the upward elasticity of the Mylar  308 , the included angle between the bearing board  307  and the sloping paper feeding tray  304  will become larger and larger to support the weight of the remaining paper sheets of the paper stack  314 . Consequently, the front end of the remaining paper sheets of the paper stack  314  will reach the feeding end  312  sequentially, so that the automatic paper feeding roller set  306  may sequentially carry the paper sheets of the paper stack  314  to move forward.  
      After the paper sheets  302   a  and  302   b  and the paper stack  314   a  are sequentially carried by the paper feeding roller set  306  and fed into the office machine, only the paper sheet  302   c  will be left at the sloping paper feeding tray  204  like the case in  FIG. 3A . Owing to the upward elasticity of the Mylar  308 , the included angle between the bearing board  307  and the sloping paper feeding tray  304  is expanded and becomes ω 1  so that the paper sheet  302   c  is pushed upward with the front end of the paper sheet  302   c  reaching the feeding end  312 . Consequently, the automatic paper feeding roller set  306  may carry the paper sheet  302   c  to move towards the feeding end  312 . The step of automatic document feeding of the automatic document feeder  300  is completed here.  
     PREFERRED EMBODIMENT TWO  
      Referring to  FIG. 4A , a cross-sectional view of the structure of an automatic document feeder  400  according to preferred embodiment two of the invention is shown. In  FIG. 4A , the automatic document feeder  400  includes a sloping paper feeding tray  404 , an automatic paper feeding roller set  406 , a paper feeding pad  410 , a bearing board  407  and an elastic structure, wherein the elastic structure may be a spring or a Mylar  408 . The automatic document feeder  400  is for feeding a to-be-fed paper sheet  402  into an office machine (not shown in  FIG. 4A ) such as a printer, a copier, a scanner or a facsimile machine. The sloping paper feeding tray  404  is for accommodating the to-be-fed paper sheet  402 . Both the automatic paper feeding roller set  406  and the paper feeding pad  410  are disposed at the bottom of the sloping paper feeding tray  404 . A feeding end  412  is formed by a flange of the automatic paper feeding roller set  406  and the paper feeding pad  410 , wherein the flange of the automatic paper feeding roller set  406  and the paper feeding pad  410  are adjacent to and in contact with each other. Moreover, the automatic paper feeding roller set  406  rotates clockwise around a roller shaft  416  and carries the to-be-fed paper sheet  402  to move forward.  
      The bearing board  407 , with its one end being pivotally connected to the sloping paper feeding tray  404 , is able to turn around on the sloping paper feeding tray, while the other end of the bearing board  407  supports the to-be-fed paper sheet  402 . The Mylar  408 , which is disposed between the sloping paper feeding tray  404  and the bearing board  407 , may elastically spring the other end of the bearing board  407  so that an included angle ψ 1  is created between the bearing board  407  and the sloping paper feeding tray  404 .  
      The Mylar  408  includes a junction portion  408   a , a supporting portion  408   b  and a bending portion  408   c , wherein the supporting portion  408   b  connects the junction portion  408   a  and the bending portion  408   c  with the junction portion  408   a  being flatly adhered onto the sloping paper feeding tray  404 . The supporting portion  408   b , which creates another included angle with the sloping paper feeding tray  404 , elastically supports the bearing board  407 . The bending portion  408   c  forms an included angle with the supporting portion  408   c , wherein the included angle may be a fixed included angle or an adjustable included angle. Furthermore, one terminal end of the bending portion  408   c  is embedded into a slot  413  of the sloping paper feeding tray  404 . As more and more paper sheets are placed on the bearing board  407 , the included angle between the bearing board  407  and the sloping paper feeding tray  404  becomes smaller while the bending portion  408   c  slide inwardly along the slot  413 . The bearing board  407  uses the elasticity of the Mylar  408  to support the to-be-fed paper sheet  402  with the front end of to-be-fed paper  402  reaching the feeding end  412 , so that the automatic paper feeding roller set  406  may carry the to-be-fed paper sheet  402  to move towards the feeding end  412 .  
      Referring to  FIG. 4B , a cross-sectional view of the structure of the automatic document feeder  400  of  FIG. 4A  with a paper stack being loaded therein is shown. In  FIG. 4B , the paper stack  414  including a paper sheet  402   a , a paper sheet  402   b , a paper stack  414   a  and a paper sheet  402   c  arranged in a top-down order is loaded in a sloping paper feeding tray  404 . Since the downward gravity of the paper stack  414  is larger than the gravity of the single to-be-fed paper sheet  402  in  FIG. 4A  and the upward elasticity of the Mylar  408  as well, the included angle between the bearing board  407  and the sloping paper feeding tray  404  is smaller than ψ 1  while the bending portion  408   c  slides inwardly along the slot  413 . Consequently, the bottom of the supporting portion  408   b  of the Mylar  408  may even come into contact with the sloping paper feeding tray  404 , while the bending portion  408   c  may be completely embedded into the slot  413  with the bottom of the bearing board  407  touching one end of the junction portion  408   a . Meanwhile, the front end of the paper stack  414  reaches the paper feeding pad  410  and the front end of the paper sheet  402   a  just reaches the feeding end  412 .  
      After the automatic paper feeding roller set  406  has sequentially carried the paper sheet  402   a , the paper sheet  402   b  and the paper stack  414   a  to move forward and to be fed into the office machine, only the paper sheet  402   c  will be left at the sloping paper feeding tray  404  like the case in  FIG. 4A . Owing to the upward elasticity of the Mylar  408 , the included angle between the bearing board  407  and the sloping paper feeding tray  404  will be expanded and become ψ 1 , while the bending portion  407   c  will slide outwardly along the slot  413  to push the paper sheet  402   c  upward with the front end of the paper sheet  402   c  reaching the feeding end  412 . Consequently, the automatic paper feeding roller set  406  may carry the paper sheet  402   c  to move towards the feeding end  412 . The step of automatic document feeding of the automatic document feeder  400  is completed here.  
      However, anyone who is familiar with the invention will realize that the technique of the invention is not limited thereto. For example, owing to the sloping design of the structure of the sloping paper feeding tray, after a paper sheet is loaded into the sloping paper feeding tray, the paper sheet will be disposed on the bearing board with a slope so that the front end of the paper sheet will automatically slide to the feeding end. Therefore, the upward elasticity of the elastic structure of the invention does not need to be as large as that in  FIG. 1A . A smaller upward elasticity will do as long as the elasticity suffices to enable the front end of the paper sheet to reach the feeding end after the paper sheet slides into the sloping paper feeding tray due to gravity.  
      With the design of disposing a bearing board on a sloping paper feeding tray, the automatic document feeder disclosed above not only protects the Mylar disposed under the bearing board from being damaged but also reduces the damage rate of the Mylar, so that the lifespan of the Mylar may be lengthened and a stable operation of the automatic document feeder may be achieved.  
      While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On 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.