Abstract:
A media feeding device capable of detecting the size of the fed media is provided. The claimed media feeding device follows the property of different bit signals, wherein the bit signals are transformed from different rotational angles generated by the rotational shafts, which are pushed by the printed media of different sizes. Therefore, the sizes of the currently fed printed media are detected by the media feeding device rather than informing the media feeding device about the size of the currently fed printed media through manual methods by the user.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a media feeding device, and more particularly, to a media feeding device capable of detecting the size of a printed media fed into the media feeding device.  
         [0003]     2. Description of the Prior Art  
         [0004]     Generally speaking, while a printer having a function of feeding printed media is used, manual operations and an operation panel disposed on the printer are required for selecting a size of required printed media. If the printer is capable of automatically detecting the size of a printed media fed into the printer, a user does not have to manually select the size of the printed media through a computer or an operation panel. It is more convenient for the user to avoid manual operations in favor of the printer automatically detecting the size of the printed media.  
         [0005]     Therefore, a light sensor is disposed adjacent to a cartridge for detecting the size of a printed media while the cartridge is moved and the printed media is fed in a prior art printer. However, the cost of the light sensor is significant, and the light sensor is fragile so that the cost of maintaining the function of the light sensor is also significant.  
         [0006]     A light-intercepting switch is also utilized in another prior art printer for detecting the size of a printed media fed into the printer. However, a light-intercepting switch can only be utilized for detecting the size of single type of printed media. When it is required for detecting printed media having various types of sizes, the amount of light-intercepting switches is necessarily increased as well as the space for the increased light-intercepting switches. Therefore, the cost of the prior art printer is also increased because of the increased light-intercepting switches.  
       SUMMARY OF THE INVENTION  
       [0007]     The claimed invention provides a media feeding device for detecting a size of a printed media. The media feeding device comprises a case utilized for depositing a printed media, the case having a plurality of holes, an axle disposed above the case in a rotatable manner, and a plurality of shafts connected to the axle and utilized for driving a rotation of the axle while the plurality of shafts is pushed by the printed media deposited in the case, wherein the plurality of shafts is capable of stretching into the plurality of holes when the plurality of shafts is not pushed by the printed media.  
         [0008]     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a solid diagram of a media feeding device capable of detecting the size of a printed media while there is no printed media fed into the media feeding device of the present invention.  
         [0010]      FIG. 2  is a lateral view of the media feeding device shown in  FIG. 1 .  
         [0011]      FIG. 3  is a bit signal table of a sensing device of the present invention when the sensing device includes two sensing switches.  
         [0012]      FIG. 4  is a solid diagram of the media feeding device fed with a printed media having a size of the first type shown in  FIG. 3  of the present invention.  
         [0013]      FIG. 5  is a lateral diagram of the media feeding device fed with the printed media having a size of the first type shown in  FIG. 3  of the present invention.  
         [0014]      FIG. 6  is a solid diagram of the media feeding device fed with a printed media having a size of the second type shown in  FIG. 3  of the present invention.  
         [0015]      FIG. 7  is a lateral diagram of the media feeding device fed with a printed media having a size of the second type shown in  FIG. 3  of the present invention.  
         [0016]      FIG. 8  is a solid diagram of the media feeding device fed with a printed media having a size of the third type shown in  FIG. 3  of the present invention.  
         [0017]      FIG. 9  is a lateral view of the media feeding device fed with the printed media having a size of the third type shown in  FIG. 3  of the present invention.  
         [0018]      FIG. 10  is a combination of a front view and a lateral view of a first sensing device of the present invention.  
         [0019]      FIG. 11  is a combination of a front view and a lateral view of the first sensing device of the present invention while generating a two-digit signal ( 0 , 1 ).  
         [0020]      FIG. 12  is a combination of a front view and a lateral view of the first sensing device of the present invention while generating a two-digit signal ( 1 , 0 ).  
         [0021]      FIG. 13  is a combination of a front view and a lateral view of the first sensing device generating a two-digit signal ( 1 , 1 ) of the present invention.  
         [0022]      FIG. 14  is a combination of a front view and a lateral view of a second sensing device of the present invention.  
         [0023]      FIG. 15  is a combination of a front view and a lateral view of the second sensing device generating a two-digit signal ( 0 , 1 ) of the present invention.  
         [0024]      FIG. 16  is a combination of a front view and a lateral view of the second sensing device generating a two-digit signal ( 1 , 0 ) of the present invention.  
         [0025]      FIG. 17  is a combination of a front view and a lateral view of the second sensing device generating a two-digit signal ( 1 , 1 ) of the present invention.  
         [0026]      FIG. 18  is a combination of a front view and a lateral view of the second sensing device while the media feeding device of the present invention is fed with a plurality printed media having a size of the first type shown in  FIG. 3 .  
         [0027]      FIG. 19  is a combination of a front view and a lateral view of the second sensing device while a plurality of printed media having a size of the second type shown in  FIG. 3  is fed into the media feeding device of the present invention.  
         [0028]      FIG. 20  is a combination of a front view and a lateral view of the second sensing device while the media feeding device of the present invention is fed with a plurality of printed media having a size of the third type shown in  FIG. 3 .  
         [0029]      FIG. 21  is a bit signal table of a sensing device having three sensing switches. 
     
    
     DETAILED DESCRIPTION  
       [0030]     Please refer to  FIG. 1 , which is a solid diagram of a media feeding device  100  capable of detecting the size of a printed media while there is no printed media fed into the media feeding device  100  of the present invention. The media feeding device  100  comprises a case  101 , an axle  103 , a plurality of shafts  105 ,  107 , and  109 , a retarder  113 , and an elastic device  115 . The case  101  is utilized for deposit a fed printed media, and has a plurality of holes  151 ,  153 , and  155 . The axle  103  is disposed above the case  101  in a rotatable manner. The shafts  105 ,  107 , and  109  are connected to the axle  103  and are capable of stretching into the holes  151 ,  153 , and  155  respectively. The retarder  113  is utilized for restricting an axial movement of the axle  103 . The elastic device  115  is utilized for exerting an external force on the axle  103  for driving the shafts  105 ,  107 , and  109  deeply into the plurality of holes  151 ,  153 , and  155 . The elastic device  115  may be a torsional spring. When a printed media is fed into the case  101 , some shafts of the plurality of shafts  105 ,  107 , and  109  are pushed by the printed media according to the size of the printed media, then a rotation of the axle  103  is driven by the pushed shafts. A rotating angle of the axle  103  can be utilized for indicating a combination of the pushed shafts, therefore, the size of the printed media is also indicated. For example, when a printed media having a smaller size is fed into the case  101 , only the shaft  105  is pushed by the smaller printed media; when a printed media having a medium size is fed into the case  101 , both the shafts  105  and  107  are pushed by the medium printed media simultaneously; when a printed media having a larger size is fed into the case  101 , all the shafts  105 ,  107 , and  109  are pushed by the larger printed media simultaneously. The media feeding device  100  of the present invention may further comprises a sensing device for sensing a rotating angle of the axle  103 . After the rotating angle is sensed by the sensing device, the sensed rotating angle along with an indicated size of a corresponding printed media is transmitted to the media feeding device  100  for further processing. A detailed description of the sensing device is provided latter.  
         [0031]     In  FIG. 1 , when a printed media is fed into the case  101 , the printed media must be fed near a side of the case  101 , the side being closer to the shaft  105 . Therefore, a smaller printed media can only push the shaft  105 ; a medium printed media can push the shafts  105  and  107  simultaneously; a larger printed media can push the shafts  105 , 107 , and  109  simultaneously; and a combination of the pushed shafts mentioned above is thus generated. For example, in a preferred embodiment of the present invention, a paper of size A6 can only push the shaft  105 ; a paper of size A5 can only push the shafts  105  and  107  simultaneously; and a paper of size A4 can push the shafts  105 ,  107 , and  109  simultaneously. When a combination of the shafts  105 ,  107 , and  109  is pushed by a printed media, a rotating angle of the axle  103  corresponding to the combination is generated, and a digital signal is also generated for representing the rotating angle of the axle  103  and the combination of the shafts  105 ,  107 , and  109 . As shown in  FIG. 1 , the shafts  105 ,  107 , and  109  correspond to the holes  151 ,  153 , and  155  respectively. The aperture size of the hole  151  is smaller than the aperture size of the hole  153 , and the aperture size of the hole  153  is smaller than the aperture size of the hole  155 . Assume the shaft  105  has to rotate a rotating angle A 1  for moving above a datum plane of the hole  151 , the shaft  107  rotates with a rotating angle A 2  for moving above a datum plane of the hole  153 , and the shaft  109  rotates with a rotating angle A 3  for moving above a datum plane of the hole  155 . Therefore, the rotating angle A 1  is smaller than the rotating angle A 2  while the rotating angle A 2  is also smaller than the rotating angle A 3 . Through appropriately setting the aperture sizes of the holes, the size of the printed media fed into the case  101  is determined through the rotating angle of the axle  103  and without confusing the size of the printed media with the other types of printed media having different sizes. Please refer again to the preferred embodiment of the present invention mentioned above. When the shafts  105  and  107  are simultaneously pushed by a fed paper of size A5, the sensing device determines that the rotating angle A 2  of the axle  103  is driven by the shaft  107  pushed by the fed paper of size A5 since the paper is no longer in contact with the shaft  105 . Similarly, when the shafts  105 ,  107 , and  109  are simultaneously pushed by a fed paper of size A4, the sensing device determines that the rotating angle A 3  of the axle  103  is driven by the shaft  109  pushed by the fed paper of size A4 since the shafts  105  and  107  are no longer in contact with the fed paper. Additionally, the amount of printed media deposited in the case  101  is limited for preventing overflow in the case  101  and preventing the axle  103  from rotating by a rotating angle larger than the rotating angle representing the size of the printed media. When the axle  103  rotates by a larger rotating angle than the rotating angle representing the size of the printed media, the size of the printed media is easily mistaken to be a size larger than the printed media. The limitation of the amount of the printed media fed into the case  101  depends on the requirements and the size of the case  101 . Moreover, the direction of a section line  2  indicates a lateral view shown in  FIG. 2 .  
         [0032]     As mentioned above,  FIG. 2  is a lateral view of the media feeding device shown in  FIG. 1 . Since no printed media is fed into the case  101  in  FIG. 2 , the shafts  105 ,  107 , and  109  in  FIG. 2  are not pushed into the holes  151 ,  153 , and  155 . Note that since  FIG. 2  is a lateral view of the media feeding device  100  in  FIG. 1 , and the section line  2  corresponding to the lateral view lies on the hole  155 , thereby, the holes  151  and  153  are not visible in  FIG. 2  so that the depths and the opening lengths of the holes  151  and  153  are shown in dotted lines.  
         [0033]     Please refer to  FIG. 3 . As mentioned above, the media feeding device  100  of the present invention further comprises a sensing device for detecting a rotating angle of the axle  103  driven by the shafts pushed by the printed media.  FIG. 3  is a bit signal table of the sensing device when the sensing device includes two sensing switches. From the description in  FIG. 1 , when the shafts are pushed by the fed printed media, the axle  103  simultaneously rotates in an angle, which is transformed into a two-digits signal latter for representing the size of the fed printed media. Note that the sizes of the printed media correspond to different rotating angles of the axle  103  respectively. When the sensing device senses the rotating angle of the axle  103 , each of the sensing switches of the sensing device generates a bit signal of value 0 or 1 according to whether the corresponding sensing switch is triggered. Lastly, the sensing device integrates both the digital signals generated by the sensing switches respectively to form a two-digit signal, which represents the size of the printed media. As shown in  FIG. 3 , when the sensing device includes two sensing switches, four different statuses are generated for representing three types of sizes of the printed media and the instance when there is no printed media in the case  101 . For example, since there is no printed media fed into the media feeding device  100 , no sensing switches are triggered so that both the sensing switches generate a digital signal of value 0. Then the sensing device integrates both the digital signals into a two-digit signal ( 0 , 0 ) for representing the instance when there is no printed media in the media feeding device  100 . In the example, the number of sensing switches corresponds to the types of the sizes of the printed media. When the number of the sensing switches is N, which is a positive integer, the number of the types of the sizes of the printed media is (2 N −1). The media feeding device  100  may further include different sensing devices for detecting the rotating angle of the axle  103  pushed by the printed media.  
         [0034]      FIG. 4  is a solid diagram of the media feeding device  100  fed with a printed media  131 . As shown in  FIG. 4 , the shaft  105  is pushed by the printed media  131 . Since the size of the printed media  131  is smaller, the shafts  107  and  109  are not pushed by the printed media  131 . In this situation, a sensing device including two sensing switches, the sensing device not shown in  FIG. 4 , generates a two-digit signal ( 0 , 1 ) for representing the size of the printed media  131 . Moreover, the section line  5  shown in  FIG. 4  indicates a lateral view of  FIG. 5 .  
         [0035]      FIG. 5  is a lateral diagram of the media feeding device  100  fed with the printed media  131 . As shown in  FIG. 5 , the shaft  105  is pushed out of the hole  151  by the printed media  131 . Note that  FIG. 5  is a lateral view of the media feeding device shown in  FIG. 4 , and the section line of  FIG. 4  lies on the hole  151 , thereby, in  FIG. 5 , the holes  153  and  155  are not visible and the shafts  107  and  109  are not visible.  
         [0036]      FIG. 6  is a solid diagram of the media feeding device  100  fed with a printed media  133 . As shown in  FIG. 6 , the shafts  105  and  107  are pushed by the printed media  133 . Since the size of the printed media  133  is medium (i.e., not small and not large), only the shaft  109  is not pushed by the printed media  133 . Under this situation, a sensing device, which is not shown in  FIG. 6 , including two sensing switches correspondingly generates a two-digit signal ( 1 , 0 ) for representing the size of the printed media  133 . Moreover, the section line  7  indicates a lateral view of  FIG. 7 .  
         [0037]      FIG. 7  is a lateral diagram of the media feeding device  100  fed with a printed media  133 . As shown in  FIG. 7 , the shafts  105  and  107  are pushed out of the holes  151  and  153  respectively by the printed media  133 . Note that  FIG. 7  is a lateral diagram of the media feeding device  100  shown in  FIG. 6 , and the section line  7  lies on the hole  153 . Therefore, the hole  155  and the shaft  109  are not visible in  FIG. 7 , and the opening length and the depth of the hole  151  is illustrated with a dotted line.  
         [0038]      FIG. 8  is a solid diagram of the media feeding device  100  fed with a printed media  135 . As shown in  FIG. 8 , the shafts  105 ,  107 , and  109  are pushed by the printed media  135 . Under this situation, a sensing device, which is not shown in  FIG. 8 , including two sensing switches correspondingly generates a two-digit signal ( 1 , 1 ) for representing the size of the printed media  135 . Moreover, the section line  9  shown in  FIG. 8  indicates a lateral view in  FIG. 9 .  
         [0039]      FIG. 9  is a lateral view of the media feeding device  100  fed with the printed media  135 . As shown in  FIG. 9 , the shafts  105 ,  107 , and  109  are pushed out of the holes  151 ,  153 , and  155  respectively by the printed media  135 . Note that  FIG. 9  is a lateral diagram of the media feeding device  100  shown in  FIG. 8  with respect to the section line  9 , which lies on the hole  155 , therefore, the opening lengths and the depths of the holes  151  and  153  are illustrated with dotted lines.  
         [0040]     Please refer to  FIG. 10 , which is a combination of a front view and a lateral view of a first embodiment of the sensing device of the present invention. In  FIG. 10 , there is no printed media fed into the media feeding device  100 . The sensing device  111  comprises two sensing switches  117  and  119 , two shafts  121  and  123 , and an extension of the axle  103 . The shafts  121  and  123  are utilized for indicating the rotations of the shafts  105 ,  107 , and  109  so that both the sensing switches  117  and  119  are able to detect the corresponding rotating angles. While the shafts  121  and  123  rotate by a specific angle, the shafts  121  and  123  trigger the sensing switches  117  and  119  respectively, therefore, the rotating angle of the axle  103  driven by the shafts  105 ,  107 , and  109  is transformed into a two-digit signal representing the size of the fed printed media. The two-digit signal represents the detected size of the printed media, then the media feeding device  100  executes preceding procedures related to the fed printed media. In a preferred embodiment of the present invention, the sensing switches  117  and  119  may be touch-sensing switches or light-sensing switches. In  FIG. 10 , since there is no printed media fed in the case  101  of the media feeding device  100 , the sensing switches  117  and  119  are not triggered by the shafts  121  and  123 , and a two-digit signal ( 0 , 0 ) is thus generated by the sensing device  111 . The first  0  of the two-digit signal ( 0 , 0 ), i.e., the least significant digit  0  of ( 0 , 0 ), represents that the sensing switch  117  is not triggered by the shaft  121 . The second  0  of the two-digit signal ( 0 , 0 ), i.e., the most significant digit  0  of ( 0 , 0 ), represents that the sensing switch  119  is not triggered by the shaft  123 . Note that in the sensing device  111 , part of the shaft  121  overlaps with part of the shaft  123 . Therefore, dots are utilized for painting the shaft  123  in the lateral view to distinguish from the shaft  121 .  
         [0041]      FIG. 11  is a combination of a front view and a lateral view of the sensing device  111  of the present invention while generating a two-digit signal ( 0 , 1 ). When a printed media  131  is fed into the media feeding device  100 , the shaft  105  is pushed by the printed media  131 , thereby, the shafts  121 , 123  and the axle  103  are rotated in an angle as shown in  FIG. 11 . The sensing switch  117  is thus triggered by the shaft  121 , and a one-digit signal “1” is also generated. The sensing switch  119  is not triggered by the shaft  123 , and a one-digit signal “0” is generated. The sensing device  111  then combines both digits for generating a two-digit signal ( 0 , 1 ) and transmits the two-digit signal to the media feeding device  100  thereby informing the media feeding device  100  that the size of the printed media  131  fed into the media feeding device  100  is the first type shown in  FIG. 3 . Similarly, in the sensing device  111  shown in  FIG. 11 , part of the shaft  121  overlaps with part of the shaft  123 . Therefore, dots are plotted on the shaft  123  for distinguishing from the shaft  121  in the lateral view.  
         [0042]      FIG. 12  is a combination of a front view and a lateral view of the sensing device  111  of the present invention while generating a two-digit signal ( 1 , 0 ). When a printed media  133  is fed into the media feeding device  111 , the shafts  105  and  107  are pushed by the printed media  133 . Therefore, the axle  103  and the shafts  121 , 123  are driven to rotate in an angle, and the sensing switch  119  is triggered by the shaft  123  to generate a one-digit signal “1”. Although the sensing switch  117  is temporarily triggered by the shaft  121 , however, the shaft  121  continues rotating and thus leaving the triggering range of the sensing switch  117 . Therefore, a one-digit signal “0” is generated at last from the sensing switch  117 . The sensing device  111  then combines both the one-digit signals to generate a two-digit signal ( 1 , 0 ) and transmits the two-digit signal ( 1 , 0 ) to the media feeding device  100  for informing the media feeding device  100  that the size of the printed media  133  is the second type shown in  FIG. 3 . Similarly, in the sensing device  111  of the present invention, part of the shaft  121  overlaps with part of the shaft  123 , therefore, dots are plotted on the shaft  123  for distinguishing from the shaft  121  in the lateral view.  
         [0043]     Please refer to  FIG. 13 , which is a combination of a front view and a lateral view of the sensing device  111  generating a two-digit signal ( 1 , 1 ) in the present invention. When the media feeding device  100  of the present invention is fed with a printed media  135 , the shafts  105 ,  107 , and  109  are pushed by the printed media  135  and drive a rotation of the shafts  121 ,  123  and the axle  103  as shown in  FIG. 13 . Therefore, the shaft  121  is triggered by the sensing switch  117  and generates a one-digit signal “1”. Similarly, the sensing switch  119  is triggered by the shaft  123  and generates a one-digit signal “1”. The sensing device  111  combines both the one-digit signals and generates a two-digit signal ( 1 , 1 ) for transmitting the two-digit signal ( 1 , 1 ) to the media feeding device  100  of the present invention for informing the media feeding device  100  that the size of the printed media  135  is the third type shown in  FIG. 3 . Similarly, in the sensing device  111  of the present invention, part of the shaft  121  overlaps with part of the shaft  123 . Therefore, dots are plotted on the shaft  123  for distinguishing from the shaft  121  in the lateral view.  
         [0044]      FIG. 14  is a combination of a front view and a lateral view of the sensing device  112  of the present invention. In  FIG. 14 , the media feeding device  100  is not fed with any printed media. The sensing device  112  comprises two sensing switches  157  and  159 , three fan-shaped levers  125 ,  127 , and  129 , and an extension of the axle  103 . The fan-shaped levers  125 ,  127 , and  129  are utilized for indicating a rotation of the shafts  105 ,  107 , and  109  so that the sensing switches  157  and  159  sense the rotation of the shafts  105 ,  107 , and  109 . A rotation of the fan-shaped levers  125  and  127  are coaxial, therefore, both the fan-shaped levers  125  and  127  may trigger the sensing switch  157 . A rotation of the fan-shaped lever  129  may trigger the sensing switch  159 . Therefore, a rotating angle of the axle  103  driven by the shafts  105 ,  107 , and  109  is transformed into a two-digit signal, which indicates the size of the printed media fed into the media feeding device  100 . Please refer to the lateral view shown in  FIG. 14  again, the sensing switch  157  overlaps with the sensing switch  159 . In a preferred embodiment, the sensing switches  157  and  159  may be touch sensors or light sensors. In  FIG. 14 , since the case  101  of the media feeding device  100  is not fed with any printed media, the fan-shaped levers  125 ,  127 , and  129  are not pushed to trigger the sensing switches  157  and  159 , and a two-digit signal ( 0 , 0 ) is thus generated from the sensing device  112 . The least significant digit “0” in the two-digit signal ( 0 , 0 ) indicates that the sensing switch  157  is not triggered by the fan-shaped levers  125  and  127 , whereas the most significant digit “0” in the two-digit signal ( 0 , 0 ) indicates that the sensing switch  159  is not triggered by the fan-shaped lever  129 .  
         [0045]     Please refer to  FIG. 15 , which is a combination of a front view and a lateral view of the sensing device  112  generating a two-digit signal ( 0 , 1 ) in the present invention. When the printed media  131  is fed into the media feeding device  100  of the present invention, the shaft  105  is pushed by the printed media  131 . Therefore, as shown in  FIG. 15 , the fan-shaped lever  125  rotates in a rotating angle and triggers the sensing switch  157  for generating a one-digit signal “1”. The fan-shaped lever  127  does not trigger the sensing switch  157  since the rotating angle of the fan-shaped lever  127  does not reach the sensing switch  157 . The rotating angle of the fan-shaped lever  129  does not reach the sensing switch  159  either, thereby, a one-digit signal “0” is generated from the sensing switch  159 . Then the sensing device  112  combines both the one-digit signals to generate a two-digit signal ( 0 , 1 ) and transmits the two-digit signal ( 0 , 1 ) to the media feeding device  100  for informing the media feeding device  100  that the size of the printed media  131  is the first type shown in  FIG. 3 .  
         [0046]      FIG. 16  is a combination of a front view and a lateral view of the sensing device  112  generating a two-digit signal ( 1 , 0 ) of the present invention. When the printed media  133  is fed into the media feeding device  100  of the present invention, the shafts  105  and  107  are pushed by the printed media  133 . Therefore, the axle  103  and the fan-shaped levers  125 ,  127  are driven to rotate in a rotating angle by the shafts  105  and  107 . Then the fan-shaped lever  129  is triggered by the sensing switch  159  to generate a one-digit signal “1”. However, the sensing switch  157  is triggered by the fan-shaped lever  125  only temporarily, and the fan-shaped lever  125  continues rotating and thereby later leaves the triggering range of the sensing switch  157 . Thereby, a one-digit signal “0” is generated from the sensing switch  157  at last. The rotating angle of the fan-shaped lever  127  does not reach the triggering range of the sensing switch  157 . The sensing device  112  combines both the one-digit signals into a two-digit signal ( 1 , 0 ) and transmits the two-digit signal ( 1 , 0 ) to the media feeding device  100  for informing the media feeding device  100  that the size of the printed media  133  is the second type shown in  FIG. 3 .  
         [0047]     Please refer to  FIG. 17 , which is a combination of a front view and a lateral view of the sensing device  112  generating a two-digit signal ( 1 , 1 ) of the present invention. When the printed media  135  is fed into the media feeding device  100 , the shafts  105 ,  107 , and  109  are pushed by the printed media  135 , thereby, the fan-shaped levers  125 ,  127 , and  129  are driven to rotate a rotating angle as shown in  FIG. 17 . The fan-shaped lever  129  is triggered by the sensing switch  159  to generate a one-digit signal “1”. The sensing switch  157  is triggered by the fan-shaped lever  125  only temporarily, and the fan-shaped lever  125  continues rotating and thereby later leaves the triggering range of the sensing switch  157 . The fan-shaped lever  127  is triggered by the sensing switch  157  to generate a one-digit signal “1”. Then the sensing device  112  combines generate a two-digit signal ( 1 , 1 ) and transmits the two-digit signal ( 1 , 1 ) to the media feeding device  100  for informing the media feeding device  100  that the size of the printed media  135  is the third type shown in  FIG. 3 .  
         [0048]     When a plurality of printed media is fed into the media feeding device of the present invention, the shafts of media feeding device rotate in a larger rotating angle. However, through appropriate designs, the size of the plurality of printed media is still recognized by the media feeding device of the present invention according to the larger rotating angle.  
         [0049]     Please refer to  FIG. 18 , which is a combination of a front view and a lateral view of the sensing device  112  while the media feeding device  100  is fed with a plurality printed media  131  of the present invention. As shown in  FIG. 18 , the shaft  105  is pushed by the plurality of printed media  131 . Since the thickness of the plurality of printed media  131  is larger than single printed media  131 , the shaft  105  rotates by a larger rotating angle in  FIG. 18  than in  FIG. 15 . According to specifications of the sensing device  112  of the present invention, although the rotating angles of the fan-shaped levers  125 ,  127 , and  129  become larger, the rotation of the fan-shaped levers  125 ,  127 , and  129  is still detectable for the sensing switches  157  and  159  of the sensing device  112 . That is, through proper designs, the sensing device of the media feeding device of the present invention is capable of detecting the sizes of a plurality of printed media fed into the media feeding device of the present invention. Therefore, the sensing device  112  generates a two-digit signal ( 0 , 1 ) for indicating the sizes of the plurality of printed media  133  are the first type shown in  FIG. 3 .  
         [0050]      FIG. 19  is a combination of a front view and a lateral view of the sensing device  112  while a plurality of printed media  133  is fed into the media feeding device  100  of the present invention. Similarly, the shafts  105  and  107  are pushed by the plurality of printed media  133  and rotate by a larger rotating angle in  FIG. 19  than in  FIG. 16 . According to specifications of the sensing device  112 , the rotating angles of the fan-shaped levers  125 ,  127 , and  129  driven by the axle  103  are still detectable for the sensing switches  157  and  159  of the sensing device  112 . Therefore, a two-digit signal ( 1 , 0 ) is generated from the sensing device  112  for indicating the sizes of the plurality of printed media  133  are the second type shown in  FIG. 3 .  
         [0051]      FIG. 20  is a combination of a front view and a lateral view of the sensing device  112  while the media feeding device  100  is fed with a plurality of printed media  135 . Similarly, the shafts  105 ,  107 , and  109  are pushed by the plurality of printed media  135  and rotate by a larger rotating angle in  FIG. 20  than in  FIG. 17 . According to specifications of the sensing device  112  of the present invention, the rotating angles of the fan-shaped levers  125 ,  127 ,  129  driven by the axle  103  are still detectable for the sensing switches  157  and  159  of the sensing device  112 . Therefore, a two-digit signal ( 1 , 1 ) is generated from the sensing device  112  for indicating the sizes of the plurality of the printed media  135  are the third type shown in  FIG. 3 .  
         [0052]     Sensing devices capable of detecting additional sizes of the printed media fed into the media feeding device of the present invention may also be utilized in the present invention. Please refer to  FIG. 21 , which is a bit signal table of a sensing device having three sensing switches. As shown in  FIG. 21 , the sensing device having three sensing switches is capable of detecting various sizes of the printed media fed into the media feeding device such as ( 0 , 0 , 0 ), ( 0 , 0 , 1 ), ( 0 , 1 , 0 ), ( 0 , 1 , 1 ), ( 1 , 0 , 0 ), ( 1 , 0 , 1 ), ( 1 , 1 , 0 ), and ( 1 , 1 , 1 ), i.e., the sensing device is capable of detecting seven types of sizes of the printed media whereas ( 0 , 0 , 0 ) indicates that there is no printed media fed into the media feeding device of the present invention. Similarly, by utilizing a sensing device having more sensing switches, the media feeding device of the present invention is capable of detecting even more sizes of the printed media fed into the media feeding device of the present invention.  
         [0053]     In the present invention, various rotating angles of shafts and levers are utilized for indicating various sizes of printed media while the printed media push the shafts and thus trigger sensing switches of the sensing device. The present invention enables a general printer to automatically detect the size of the printed media fed into the media feeding device for facilitating preceding processes on the printed media. Manual settings for setting the size of the printed media fed into the printer are thereby unnecessary. Additionally, the number of sensing switches in a traditional sensing device equals the number of sizes of the printed media that the sensing device can detect. However, the number of sizes of the printed media is logarithmically proportional to the number of sensing switches in the present invention. In other words, utilizing the same number of sensing switches, the sensing device of the present invention detects more sizes of printed media than the traditional sensing device. Therefore, the sensing device of the present invention saves expense and facilitates the efficiency of the media feeding device of the present invention.  
         [0054]     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.