Abstract:
The invention is to provide a paper feeding apparatus and a driving method thereof for an office machine. The office machine includes a paper accommodating device and a paper processing apparatus. The paper accommodating device is for accommodating paper sheets to be processed by the paper processing apparatus. The paper feeding apparatus is for feeding the paper sheets accommodated by the paper accommodating device one by one to the paper processing apparatus. The paper feeding apparatus includes a pickup roller, a delivery roller, a pair of feeding rollers, a detection device, a transmission gear assembly, a drive motor and a controller. The detection device detects a leading edge and a trailing edge of the paper sheet delivered by the paper feeding apparatus. In particular, the paper feeding apparatus is a simple-configuration, light-weight and compact component and capable of feeding paper sheets accurately. During feeding operation of the paper feeding apparatus, the rollers of the paper feeding apparatus are driven rotating in respective direction or stopped rotating so as to feed the paper sheets accurately.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 09/630,001 filed on Jul. 31, 2000 now U.S. Pat. No. 6,485,001. The disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a paper feeding apparatus and a driving method thereof for an office machine, such as a printer, a copy machine, a scanner, a fax, a multi-function office machine or an all-in-one office machine. 
     BACKGROUND OF THE INVENTION 
     An office machine inevitably requires a paper feeding apparatus for feeding paper sheets to be processed by the office machine. The related prior arts refer to the following: U.S. Pat. Nos. 5,392,092; 5,296,908; 4,798,374; 4,975,749; 4,984,779; 5,016,061; 4,846,456; 5,054,768; 4,905,054; 4,979,727; and 5,228,669. 
     A typical paper feeding apparatus of an office machine must meet the needs of feeding the paper sheets accurately. The paper feeding apparatus should feed the paper sheets in order, such that a misfeed or a double feed of the paper sheets does not take place. Moreover, the leading edge of the delivered paper sheet should be well aligned so that distortion of the sheet does not occur during the process performed by the office machine. 
     The current. design for office machines gravitate towards the desk-top type, multi-function and even all-in-one design in order to increase usefulness and portability. The so-called multi-function or all-in-one office machine combines the functions of various office equipments into one. Obviously, the current office machine still requires simple-configuration, light-weight and compact components to reduce weight of the machine and space occupied by the machine. Accordingly, an objective of the invention is to provide a simple-configuration, light-weight and compact paper feeding apparatus for an office machine. Moreover, the paper feeding apparatus feeds paper sheets into the office machine accurately. 
     In addition, another objective of the invention is to provide a method for driving such simple-configuration, light-weight and compact paper feeding apparatus. Moreover, the method can drive the paper feeding apparatus feeding paper sheets into the office machine accurately. 
     SUMMARY OF THE INVENTION 
     The objective of the invention is to provide a paper feeding apparatus for an office machine. The office machine includes a paper accommodating device and a paper processing apparatus. The paper accommodating device accommodates paper sheets to be processed by the paper processing apparatus. The paper feeding apparatus feeds the paper sheets accommodated by the paper accommodating device one by one to the paper processing apparatus. In particular, the paper feeding apparatus is simple-configuration, light-weight and compact, and feeds paper sheets into the office machine accurately. 
     According to a preferred embodiment of the invention, the paper feeding apparatus includes a pickup roller, a delivery roller, a pair of feeding rollers, a detection device and a driving device. The detection device detects a leading edge and a trailing edge of the paper sheet delivered by the paper feeding apparatus. The pickup roller selectively picks up an uppermost sheet of the paper sheets accommodated by the paper accommodating device. The delivery roller delivers the paper sheet picked up by the pickup roller. The feeding rollers selectively blocks delivery of the paper sheet, or selectively delivering the paper sheet delivered from the delivery roller to the paper processing apparatus. The detection device detects a leading edge and a trailing edge of the paper sheet being delivered by the paper feeding apparatus. The driving device, in response to the result detected by the detection device, selectively drives the rotation of the pick roller, delivery roller and feeding rollers. 
     Another objective of the invention is to provide a driving method for driving such paper feeding apparatus so as to feeding paper sheets by the paper feeding apparatus into the office machine accurately. 
     According to the driving method, while the feeding apparatus starts picking up and feeding the paper sheets, the driving device drives the pickup roller rotating in a first direction to pick up the uppermost sheet of the paper sheets accommodated by the paper accommodating device, drives the delivery roller rotating in the first direction to deliver the paper sheet delivered from the pickup roller, and drives an active roller of the feeding rollers rotating in a second direction, opposite to the first direction, to block the paper sheet delivered from the delivery roller. While the leading edge of the paper sheet delivered through the paper feeding apparatus. is located between the delivery roller and the feeding rollers, after a delay of short period of time, the driving device stops driving the pickup roller, drives the delivery roller rotating in the first direction still, and drives the active roller rotating in the first direction to deliver the paper sheet delivered from the delivery roller to the paper processing apparatus. 
    
    
     The advantage and spirit of the invention may be understood by the following recitations together with the appended drawings. 
     BRIEF DESCRIPTION OF THE APPENDED DRAWINGS 
     FIG. 1A shows an office machine  10  employing a paper feeding apparatus  20  according to a preferred embodiment of the invention while the roller  21  is operated in a clockwise direction, and the roller  23  rotates in counter-clockwise direction. 
     FIG. 1B shows the office machine  10  in FIG. 1A while roller  22  rotates in clockwise direction and the roller  23  rotates in clockwise direction. 
     FIG. 2A shows a preferred embodiment of the transmission gear assembly  28  while the transmission shaft  271  rotates in clockwise direction. 
     FIG. 2B show the transmission gear assembly  28  in FIG. 2A while the transmission shaft  271  rotates in counter-clockwise direction. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1A and 1B, a paper feeding apparatus  20  is provided for use in an office machine  10 . The office machine  10  may be a printer, a copy machine, a scanner, a fax, a multi-function office machine or an all-in-one office machine. The rotation directions of rollers in the paper feeding apparatus  20  during paper feeding operation are shown in FIGS. 1A and 1B. 
     As shown in FIGS. 1A and 1B, the office machine  10  includes an initial tray  11 , a paper processing apparatus  12 , a pair of discharge rollers  14 ,  15  and a finish tray  16 . The initial tray  11  accommodates paper sheets to be processed by the paper processing apparatus  12 . The paper processing apparatus  12  performs a predetermined process on the paper sheets delivered therein, e.g. duplicating or reading information on the paper sheets. The paper feeding apparatus  20  feeds the paper sheets accommodated by the initial tray  11  one by one into a processing path  121 . Within the processing path  121 , the components of the paper processing apparatus  12  respectively perform specific operations over the paper sheets. After being processed, each paper sheet is discharged by the discharge roller  14 ,  15  to the finish tray  16 . 
     The paper feeding apparatus  20  includes a pickup roller  21 , a delivery roller  22 , a pair of feeding rollers, a detection device  25 , a controller  26 , a drive motor  27 , a transmission gear assembly  28  and a guide board  29 . The pair of feeding rollers include an active roller  23  and an idle roller  24 . 
     The detection device  25  generates signals indicating the arrival of the leading edge and the departure of trailing edge of the paper sheet delivered by the paper feeding apparatus  20 . The detection device  25  could be a micro switch. During the period of delivering one sheet of paper, the leading edge of the sheet first approaches and triggers the detection device  25 . Then, the trailing edge of the sheet leaves and releases the detection device  25 . In other words, the detection device  25  detects the leading edge and trailing edge of the paper sheets delivered easily and accurately. 
     In this embodiment, the detection device  25  is a micro switch, and the micro switch is disposed between the delivery roller  22  and the pair of feeding rollers ( 23  and  24 ). 
     The pickup roller  21  selectively picks up and delivers an uppermost sheet S 1  of the paper sheets accommodated by the initial tray  11 . The delivery roller  22 , cooperating with the guide board  29 , delivers the paper sheet delivered from the pickup roller  21 . As shown, the delivery direction of the paper sheets delivered through the delivery roller  22  and the guide board  29  is rerouted to a direction opposite to the original direction. Obviously, this design reduces the space occupied by the office machine  10 . To help re-route the delivery direction of the delivered paper sheet S 1  passing the guide board  29 , a follow roller  291  is provided at a suitable location of the guide board  29  to assist the delivered paper sheet to adjust its delivery direction. Responsive to the detection result generated by the detection device  25 , the active roller  23  and idle roller  24  selectively block the delivery of the sheet delivered to align the leading edge of the sheet when the leading edge of the sheet contacting the active roller  23  and idle roller  24 , or selectively deliver the sheet into the processing path  121 . 
     The controller  26  is electrically connected to the detection device  25  and receives the signals generated by the detection device  25 . The controller  26  is also electrically connected to the drive motor  27  and controls the operation of the drive motor  27  in response to the signals generated by the detection device  25 . The drive motor  27  drives the transmission gear assembly  28  via the transmission shaft  271 . The transmission gear assembly  28  is operatively connected to the pickup roller  21 , the delivery roller  22  and the active roller  23  and the idle roller  24  for selectively controlling the rotation of the respective rollers  21 ,  22 ,  23  and  24 . The controller  26 , the drive motor  27  and the transmission gear assembly  28  constitute a driving device for selectively driving the rotation of the rollers in the paper feeding apparatus  20  in response to the result detected by the detection device  25 . According to this embodiment, the drive motor  27  could be a bi-directional drive motor. 
     The rotation of the pickup roller  21 , the delivery roller  22  and the active roller  23  driven by the driving device includes the following operation conditions. 
     1. While the paper feeding apparatus  20  starts picking up and feeding the uppermost sheet S 1  of the paper sheet, and before the detection device  25  generates signal indicating the arrival of the leading edge of the sheet S 1 , the driving device drives the pickup roller  21  to rotate in a first direction (a clockwise direction indicated in FIG. 1A) to pick up the uppermost sheet S 1 , drives the delivery roller  22  to rotate in the first direction to deliver the paper sheet S 1  delivered from the pickup roller  21 , and drives the active roller  23  to rotate in a second direction (a counterclockwise direction indicated in FIG.  1 A), opposite to the first direction, to temporarily block the sheet S 1  delivered from the delivery roller  22  so as to align the leading edge of the sheet S 1  across the span of the sheet S 1 . 
     2. As the detection device  25  generates signals indicating the arrival of the leading edge of the sheet S 1 , as shown in FIG. 1B, the driving device, after a delay of short period of time, stops driving the pickup roller  21  while driving the delivery roller  22  to rotate in the first direction, and drives the active roller  23  to rotate in the first direction to deliver the sheet S 1  into the processing path  121 . 
     3. As the detection device  25  generates signals indicating the departure of the trailing edge of the paper sheet S 1 , the driving device, after a delay of short period of time, drives the pickup roller  21  to rotate in the first direction to pick up another uppermost sheet S 2 , drives the delivery roller  22  to rotate in the first direction, and drives the active roller  23  to rotate in the second direction. 
     Also shown in FIGS. 1A and 1B, the discharge rollers include an active roller  14  and an idle roller  15 . During the discharging operation of the sheet, the active roller  14  is first driven to rotate in the second direction (the counterclockwise direction indicated in FIG. 1A) to align the leading edge of the sheet across the span of the sheet, and then is driven to rotate in the first direction (the clockwise direction as indicated in FIG. 1B) to discharge the sheet to the finish tray  16 . 
     It is apparent that the configuration of the paper feeding apparatus  20  of the invention is simpler than the prior arts. According to this embodiment, the paper feeding apparatus  20  feeds paper sheets accurately by using a number of components including the rollers  21 ,  22 ,  23  and  24 , detection device  25 , controller  26 , drive motor  27  and transmission gear assembly  28 . To further reduce the entire weight and space occupied of the office machine  10 , a simplified transmission gear assembly  28  is provided and will be described in detail hereinafter. 
     Referring to FIGS. 2A and 2B, an preferred embodiment of the transmission gear assembly  28  is shown to include a first driving gear  211 , a second driving gear  221 , a third driving gear  231 , a first gear set  281 , a second gear set  282 , a first planetary gear set  283  and a second planetary gear set  284 . Not shown in FIGS. 2A and 2B, the pickup roller  21  is driven by the first driving gear  211 , the delivery roller  22  is driven by the second driving gear  221 , the active roller  23  is driven by the third driving gear  231 . The first gear set  281  includes an even number of gears  2811 ,  2812 , the second gear set  282  includes an odd number of gears  2823 ,  2822 ,  2821 . The first planetary gear set  283  includes gears  2832 ,  2833 ,  2831  and the second planetary gear set  284  includes gears  2842 ,  2841 . 
     As shown in FIGS. 2A and 2B, the first end gear  2811  meshes with the transmission shaft  271 . The second end gear  2812  meshes with the third driving gear  231 . The first end gear  2821  meshes with the second driving gear  221  and the middle gear  2822 . It is required in this embodiment that an odd number of gears be disposed between the second driving gear  221  and the middle gear  2822 . For instance, there is one gear disposed between the driving gear  221  and the middle gear  2822  in FIGS. 2A and 2B. 
     The first end gear  2831  selectively meshes with the middle gear  2822 . The second end gear  2832  selectively meshes with the second end gear  2823 . The middle gear  2833  meshes with the first end gear  2811 . It is required that an odd number of gears be disposed between the transmission shaft  271  and the middle gear  2833  so that the middle gear  2833  and the transmission shaft  271  rotate in the same direction. In the preferred embodiment shown in FIGS. 2A and 2B, one gear  2811  is disposed between the transmission shaft  271  and the middle gear  2833 . The first end gear  2841  selectively meshes with the first driving gear  211 . 
     In the preferred embodiment of the invention shown in FIGS. 2A and 2B, the second end gear  2842  meshes with the third driving gear  231  so that the second end gear  2842  and the transmission shaft  271  rotate in the same direction. 
     In another preferred embodiment of the invention (not shown), the second end gear  2842  meshes with the driving gear  231  while there are an odd number of gears between the second end gear  2842  and the transmission shaft  271 . In this way, the second end gear  2842  and the transmission shaft  271  rotate in the same direction. 
     Through the above-mentioned arrangement the gears in the transmission gear assembly  28 , it is apparent that as the transmission shaft  271  is driven in the first direction, the pickup roller  21  and the delivery roller  22  are driven in the first direction, and the active roller  23  is driven in the second direction. As the transmission shaft  271  is driven in the second direction, the pickup roller  21  stops rotating, the delivery roller  22  and the active roller  23  are driven in the first direction. 
     Alternatively, there are a belt or an odd number of gears provided between the active roller  14  and the active roller  23  to ensure that the active roller  14  and the active roller  23  are driven in the same direction. 
     As a summary, the driving method provided to drive the paper feeding apparatus  20  includes the following steps. 
     1. As the feeding apparatus  20  starts picking up and feeding the paper sheet, and before the detection device  25  generates signals indicating the arrival of the leading edge of the paper sheet, the controller  26  drives the transmission shaft  271  rotating in the first direction. So that the pickup roller  21  rotates in the first direction to pick up the uppermost sheet S 1 , the delivery roller  22  rotates in the first direction to deliver the paper sheet delivered from the pickup roller  21 , and the active roller  23  rotates in a second direction to temporarily block the delivery of the paper sheet so as to align the leading edge of the paper sheet. 
     2. As the detection device  25  generates signals indicating the arrival of the leading edge of the paper sheet, after a delay of short period of time during which the alignment of the leading edge of the paper sheet is accomplished, the controller  26  drives the transmission shaft  271  to rotate in the second direction. So that the pickup roller  21  stops rotating while the delivery roller  22  rotates in the first direction and the active roller  23  rotates in the first direction to deliver the paper sheet to the paper processing apparatus  12 . 
     3. As the detection device  25  generates signals indicating the departure of the trailing edge of the paper sheet, after a delay of short period of time, the controller  26  drives the transmission shaft  271  to rotate in the first direction. So that the pickup roller  21  rotates in the first direction to pick up another paper sheet disposed uppermost on the paper sheets while the delivery roller  22  rotates in the first direction and the active roller  23  rotates in the second direction. 
     The above details of the preferred embodiments of the aforesaid invention are illustrative rather than limiting. For instance, the gear sets and planetary gear sets according to the invention may be replaced equivalently by other forms which are obvious to persons skillful in the arts. Accordingly, any equivalent modifications, substitutes, alterations or changes to the preferred embodiment without departing form the spirit of the invention are likely to persons with ordinary skills in the arts, and are still within the intended scope of the protection of the invention.