Abstract:
The present invention relates to a sheet stack thickness estimating device including a driving device, a first connecting rod, a second connecting rod, a pressing part and a sensor. The driving device provides a motive force to the sheet stack thickness estimating device so as to drive the first connecting rod moved horizontally for rotating the second connecting rod, so that the pressing part presses the sheets on the paper tray. By detecting if the signal generated by the sensor is blocked by the first connecting rod, the thickness estimating device can judge if the thickness of the sheets exceeds a predetermined value.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a sheet stack thickness estimating device, and more particularly to a sheet stack thickness estimating device for an office machine. 
     BACKGROUND OF THE INVENTION 
     Printers, scanners, and so on are common office machines in the office. In order to enhance the convenience of use, an additional subsequence processing device, such as a stapler or a punch, is generally equipped with the office machines in recent years, so as to automatically process the sheets according to the requirement of the users before the sheets are outputted from the office machines. However, both of the stapler and the punch have various sizes for the sheet stacks with different thickness. If the sheets on the paper tray are thicker than a processing limitation of the stapler or the punch, not only the sheets but also the subsequence processing device may be damaged. Thus, a sheet stack thickness estimating device is usually equipped for ensuring the thickness of the sheets on the paper tray is lower than a presetting thickness to avoid the above mentioned damages. 
       FIG. 1A  illustrates a schematic view of a conventional sheet stack thickness estimating device disclosed in the U.S. Pat. No. 6,773,004. The sheet stack thickness estimating device  1  in  FIG. 1A  comprises a driving device  11 , a first connecting rod  12 , a second connecting rod  13 , a shaft  14 , a pressing part  15 , an elastic component  16  and a sensor  17 . The first connecting rod  12  connects to the driving device  11 . The second connecting rod  13  comprises a front portion  131 , a middle portion  132  and an end portion  133 . Here, the front portion  131  and the end portion  133  are respectively perpendicular to the middle portion  132 , the front end  131  connects to the first connecting rod  12  and is pivoted to the shaft  14 , and the shaft  14  is disposed on a frame  18 . The pressing part  15  connects to the end portion  133  of the second connecting rod  13 . The elastic component  16  connects between the frame  18  and the second connecting rod  13 . The sensor  17  is disposed above the middle portion  132  of the second connecting rod  13 . 
     Also referring to  FIG. 1A , when the front edge of the sheet S is entering towards the paper tray  19 , the driving device  11  drives the first connecting rod  12  to move towards the driving device  11  horizontally. Hence, the first connecting rod  12  pulls the front portion  131  of the second connecting rod  13 , so as to drive the second connecting rod  13  rotates about the shaft  14  in the counterclockwise direction, and thus the second connecting rod  13  is raised to a first position (as the dashed line illustrated in  FIG. 1A ). At this time, the pressing part  15  is distant from the paper tray  19 . 
     After whole of the sheet S enters into the paper tray  19 , the driving device  11  stops to drive the first connecting rod  12  to move. Hence, the first connecting rod  12  stops to pull the front portion  131  of the second connecting rod  13 , and thus the second connecting rod  13  is driven by a return force provided by the elastic component  16  to rotate about the shaft  14  in the clockwise direction until the second connecting rod  13  is lowered to a second position (as the continuous line illustrated in  FIG. 1A ) to let the pressing part  15  lean against the sheets S on the paper tray  19 . At the same time, the second connecting rod  13  also pulls the first connecting rod  12  to move back towards the driving device  11  horizontally. As shown in  FIG. 1A , after a stack of sheets S need to be processed are all entered into the paper tray  19  and the thickness thereof is lower than a presetting thickness, the middle portion  132  of the second connecting rod  13  does not interrupt the sensor  17 , and then the controller la controls the subsequence processing device (not shown), such as a stapler or a punch, to bind or to punch the stack of sheets S. 
       FIG. 1B  illustrates a side view of the conventional sheet stack thickness estimating device where a stack of sheets are entered into the paper tray thereof. Referring to  FIG. 1B  hereinafter, after a stack of sheets S need to be processed are all entered into the paper tray  19  and the thickness thereof is thicker than the presetting thickness, the middle portion  132  of the second connecting rod  13  interrupts the sensor  17 , and then the controller  1   a  determines to stop binding or punching the stack of sheets S by the subsequence processing device (not shown), such as a stapler or a punch. 
     Accordingly, the sheet stack thickness estimating device  1  may detect whether the thickness of a stack of sheets S on the paper tray  19  is lower than the presetting thickness or not by the driving device  11 , the first connecting rod  12 , the second connecting rod  13 , the pressing part  15  and the sensor  17 . 
     However, the conventional sheet stack thickness estimating device  1  has problems as below. As described above, the sensor  17  must be disposed on the frame of the office machine above the sheet stack thickness estimating device  1 . Therefore, the sheet stack thickness estimating device  1  is not only difficult to be modulized and utilized in the office machines with various sizes, but also requiring larger vertical installation space. Further, the sensor  17  must be distant from the shaft  14  for increasing a detectable range of the sheet stack thickness, and thus requiring larger horizontal installation space as well. In addition, the probability of generating an interruption signal before the sensor  17  being completely interrupted by the second connecting rod  13  is increased due to the moving direction of the second connecting rod  13  is perpendicular to the sensor  17 , and thus it is likely to result in a misjudgement by the sheet stack thickness estimating device  1 . 
     Accordingly, it is necessary to provide a novel sheet stack thickness estimating device to overcome the above mentioned problems of the conventional stack thickness estimating device. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a modulized sheet stack thickness estimating device with higher accuracy. 
     In a preferred embodiment, the present invention provides a sheet stack thickness estimating device for detecting a thickness of a stack of sheets on a paper tray, comprising:
         a driving device, for providing a motive force to the sheet stack thickness estimating device;   a first connecting rod, comprising a notch, wherein the first connecting rod connects to the driving device, so as to be driven to move horizontally by the driving device;   a second connecting rod, wherein a first end of the second connecting rod connects to the first connecting rod and is synchronized with the first connecting rod, and a second end of the second connecting rod is pivoted to a shaft and is capable of rotating about the shaft;   a pressing part, for pressing the stack of sheets on the paper tray, wherein the pressing part is extended from the second end of the second connecting rod; and   a sensor, comprising an emitting end and a receiving end, wherein the emitting end and the receiving end are respectively located at two side of the first connecting rod.       

     In a preferred embodiment, the driving device comprises a coil rack, a pillar and a position limiting plate, wherein the coil rack has a through hole therein, the pillar is inserted inside the through hole of the coil rack with an end of the pillar exposed outside the coil rack, and the position limiting plate surrounds the end of the pillar. 
     In a preferred embodiment, an included angle substantially equal to 90 degrees is formed between the first connecting rod and the second connecting rod when there is no sheet on the paper tray. 
     In a preferred embodiment, the second connecting rod is substantially perpendicular to the pressing part. 
     In a preferred embodiment, the second connecting rod and the pressing part are formed integrally. 
     In a preferred embodiment, the sheet stack thickness estimating device further comprises a frame for supporting and holding the sheet stack thickness estimating device, wherein the driving device and the sensor are held on the frame, and the shaft and the frame are formed integrally. 
     In a preferred embodiment, the sheet stack thickness estimating device further comprises an elastic component disposed on the shaft, and the pressing part has a protrusion at a side thereof, wherein an end of the elastic component connects to the protrusion, and another end of the elastic component connects to the frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a schematic view of a conventional sheet stack thickness estimating device. 
         FIG. 1B  illustrates a side view of the conventional sheet stack thickness estimating device where a stack of sheets are entered into the paper tray thereof. 
         FIG. 2  illustrates a perspective view of a sheet stack thickness estimating device according to a preferred embodiment of the present invention. 
         FIG. 3  illustrates an explosion view of a sheet stack thickness estimating device according to a preferred embodiment of the present invention. 
         FIG. 4  illustrates a schematic view of a sheet stack thickness estimating device applied to an office machine with a subsequence processing device according to a preferred embodiment of the present invention. 
         FIG. 5A  illustrates a side view of a sheet stack thickness estimating device in a standby state according to a preferred embodiment of the present invention. 
         FIG. 5B  illustrates a side view of a sheet stack thickness estimating device where a sheet is entering into a paper tray according to a preferred embodiment of the present invention. 
         FIG. 5C  illustrates a side view of a sheet stack thickness estimating device after a stack of sheets with a thickness lower than a presetting thickness are entered into a paper tray according to a preferred embodiment of the present invention. 
         FIG. 5D  illustrates a side view of a sheet stack thickness estimating device after a stack of sheets with a thickness thicker than a presetting thickness are entered into a paper tray according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made in detail to specific embodiments of the present invention. Examples of these embodiments are illustrated in the accompanying drawings. While the invention will be described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the invention to these embodiments. In fact, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. In the following description, numerous specific details are set forth in order to provide a through understanding of the present invention. The present invention may be practiced without some or all of these specific details. In other instances, well-known process operations are not described in detail in order not to obscure the present invention. 
     According to a specific embodiment of the present invention, a sheet stack thickness estimating device capable of being applied to an office machine with a subsequence processing device is provided. 
       FIG. 2  illustrates a perspective view of a sheet stack thickness estimating device according to a preferred embodiment of the present invention. Referring to  FIG. 2 , the sheet stack thickness estimating device  2  comprises a driving device  21 , a first connecting rod  22 , a second connecting rod  23 , a pressing part  24 , a sensor  25  and a frame  26 . 
       FIG. 3  illustrates an explosion view of a sheet stack thickness estimating device according to a preferred embodiment of the present invention. Referring to  FIG. 2  and  FIG. 3  together, the driving device  21  comprises a coil rack  211 , a pillar  212  and a position limiting plate  213 . Here, the coil rack  211  has a through hole  211   a  therein. The first connecting rod  22  has a notch  221 . The pressing part  24  has a protrusion  241  at a side thereof. The sensor  25  comprises an emitting end  251  and a receiving end  252 . The frame  26  comprises a shaft  261  and an elastic component  262 , wherein the shaft  261  and the frame  26  are formed integrally. 
     An assembling process of a sheet stack thickness estimating device according to a preferred embodiment of the present invention is illustrated herein after. A pillar  212  of a driving device  21  is passed through a through hole  211   a  of a coil rack  211 , an end of the pillar  212  is exposed outside the coil rack  211 , and a position limiting plate  213  surrounds the end of the pillar  212 . The first connecting rod  22  is connected to the end of the pillar  212  of the driving device  21 . A first end of the second connecting rod  23  is connected to the first connecting rod  22 , and a second end of the connecting rod  23  is pivoted on a shaft  261  of the frame  26 . A pressing part  24  extends from the second end of the second connecting rod  23  and is perpendicular to the second connecting rod  23 , and the pressing part  24  and the second connecting rod  23  are formed integrally. An emitting end  251  and a receiving end  252  of a sensor  25  are respectively located at two sides of the first connecting rod  22  and opposite to each other. An elastic component  262  is wind around the shaft  261 , an end thereof is connected to a protrusion  241  and another end thereof is connected to the frame  26 . In addition, the driving device  21  and the sensor  25  are held on the frame  26 . 
       FIG. 4  illustrates a schematic view of a sheet stack thickness estimating device applied to an office machine with a subsequence processing device according to a preferred embodiment of the present invention. Referring to the  FIG. 4  first, an operation theory of the present embodiment is illustrated herein after. The subsequence processing device comprises the sheet stack thickness estimating device  2 , a stapler  3  and a paper tray  4 . A pressing part  24  of the sheet stack thickness estimating device  2  is exposed on the paper tray  4 . 
       FIG. 5A  illustrates a side view of a sheet stack thickness estimating device in a standby state according to a preferred embodiment of the present invention, and  FIG. 5B  illustrates a side view of a sheet stack thickness estimating device where a sheet is entering into a paper tray according to a preferred embodiment of the present invention. Referring to  FIG. 5A  and  FIG. 5B  together, the pressing part  24  is pushed by a force provided by the elastic component  262  when the sheet stack thickness estimating device  2  is standby, and thus the pressing part  24  and the second connecting rod  261  rotate about the shaft  261  in the counterclockwise direction until the pressing part  24  leans against the paper tray  4  as shown in  FIG. 5A . At this time, the driving device  21  is inactivated. Since the pillar  212  of the driving device  21  is synchronized with the first connecting rod  22  and the second connecting rod  23 , the second connecting rod  23  provides an acting force to the first connecting rod  22 , so as to bring the pillar  212  to move rightward to a standby position synchronously. At this time, an included angle substantially equal to 90 degrees is formed between the first connecting rod  22  and the second connecting rod  23 . 
     When a sheet S need to be bound is prepared for entering into the paper tray  4 , a controller (not shown) controls the driving device  21  to drive the pillar  212  and the first connecting rod  22  connected to the pillar  212  moving horizontally toward the coil rack  211  until the position limiting plate  213  leans against the coil rack  211 . At the same time, the second connecting rod  23  is brought to rotate about the shaft  261  in the clockwise direction, so as to raise up the pressing part  24  as illustrated in  FIG. 5B  to let the sheet S able to enter into the paper tray  4 . After whole of the sheet S enters into the paper tray  4 , the controller (not shown) stops to drive the driving device  21  to move. At this time, the pressing part  24  and the second connecting rod  23  are pushed by the force provided by the elastic component  262  again to rotate about the shaft  261  in the counterclockwise direction until the pressing part  24  leans against the sheet S on the paper tray  4 , so as to maintain the flatness of the sheet for binding. The driving device  21  repeats the above mentioned motions when each sheet S is prepared for entering into the paper tray  4  until all of the sheets S are entered into the paper tray  4 . 
       FIG. 5C  illustrates a side view of a sheet stack thickness estimating device after a stack of sheets with a thickness lower than a presetting thickness are entered into a paper tray according to a preferred embodiment of the present invention, and  FIG. 5D  illustrates a side view of a sheet stack thickness estimating device after a stack of sheets with a thickness thicker than a presetting thickness are entered into a paper tray according to a preferred embodiment of the present invention. Referring to  FIG. 5C  and  FIG. 5D , with the number of the sheets S increasing, the total thickness of the sheets S increases. Hence, the pressing part  24  gradually moves far away the paper tray  4 , and the first connecting rod  22  moves towards the coil rack  211  due to synchronizing with the second connecting rod  23 . As illustrated in  FIG. 5C , when a thickness of a stack of sheets S on the paper tray  4  is lower than a presetting thickness, the emitting end  251  of the sensor  25  may transmit a signal passing through the notch  221  of the first connecting rod  22  to the receiving end  252 . Therefore, the controller (not shown) determines the thickness of the stack of sheets S is lower than the presetting thickness, and thus the stapler  3  starts to bind the stack of sheets S. 
     However, as illustrated in  FIG. 5D , when a thickness of a stack of sheets S on the paper tray  4  is thicker than the presetting thickness, the first connecting rod  22  interrupts the signal transmitted from the emitting end  251  of the sensor  25 . Accordingly, the controller (not shown) determines the thickness of the stack of sheets S is thicker than the presetting thickness, and thus the stapler  3  stops binding. 
     According to the above mentioned preferred embodiment, it is understood that the sheet stack thickness estimating device  2  is modulized by combining the driving device  21 , the first connecting rod  22 , the second connecting rod  23 , the pressing part  24 , the sensor  25  and the frame  26  in the present invention. Therefore, not only the sheet stack thickness estimating device  2  may be applied to office machines with various sizes, but also it is unnecessary to enlarge an installation space due to a location of the sensor. In addition, the probability of misjudgement resulted from the sensor being incompletely interrupted is decreased due to both of the sensor and the first connecting rod are arranged horizontally, so as to increase the accuracy of the sheet stack thickness estimating device and avoid an error process. 
     Although specific embodiments of the present invention have been described, it will be understood by those of skill in the art that there are other embodiments that are equivalent to the described embodiments. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims.