Abstract:
A card-feeding mechanism has two rollers positioned before a limiting device, and a roller and a sensor positioned after the limiting device. When a motor rotates clockwise, a transmission device drives the three rollers simultaneously to deliver a card from a front end toward a rear end. When the sensor detects an edge of the card, the motor rotates counterclockwise, and only drives the roller after the limiting device. Then, the card is only driven by the roller after the limiting device, and the rollers before the limiting device are driven by the card.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a card-feeding mechanism, and more particularly, to a card-feeding mechanism implemented in a printer for ID cards. 
     2. Description of the Prior Art 
     A card-feeding mechanism can be positioned at an input of a printer of ID cards to deliver cards into the printer. The card-feeding mechanism drives a roller beneath a card, and when a friction force between the card and the roller is greater than a friction force between stacked cards, the card can be delivered into the printer. Furthermore, there is a limiting device in the card-feeding mechanism for assisting the bottom card in moving into the printer and keeping other cards in their respective positions. 
     Please refer to  FIG. 1 , which is a card-feeding mechanism  10  according to the prior art. A limiting device  12  of the card-feeding mechanism  10  can keep all cards  11  over a bottom card  13  in their respective positions. A roller  14  is connected to a motor  15  that drives the roller  14  to rotate and move the bottom card  13  into the printer. Additionally, there is another roller  16  positioned on the other side of the limiting device  12 , and connected to a motor  17 . The roller  16  is capable of assisting the card  13  in passing through the limiting device  12  until the card  13  is completely inside the printer and is ready to be printed. 
     The roller  14  has a rubber surface for increasing a friction coefficient between the roller and the card  13 . However, often an adhesive material is added to the roller  14  for improving the friction coefficient between the roller and the card  13 , and thus, the roller  14  requires constant maintenance. In addition, there is only one roller  14  before the limiting device  12  to deliver the card  13 , and so the transmission of the card  13  is not very smooth. Therefore, some printers include a sensor to detect whether a card has become stuck or if there is any other malfunction during operation. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary objective of the claimed invention to provide a card-feeding mechanism that has improved performance to solve the above-mentioned problem. 
     The claimed invention discloses a card-feeding mechanism. The card-feeding mechanism comprises a card-delivering device, a card-receiving device, a transmission device, a driver, and a sensor. The card-delivering device pushes a card in a first direction, and the card-receiving device continuously pushes the card in the first direction. The transmission device is positioned between the card-delivering device and the card-receiving device for engaging the card-delivering device and the card-receiving device when the transmission device is driven forwardly to simultaneously drive the card-delivering device and the card-receiving device, and for engaging the card-receiving device and disengaging from the card-delivering device when the transmission device is driven backwardly to drive the card-receiving device. The driver engages the transmission device for driving the transmission device. The sensor detects the pushed card. When the sensor detects the pushed card, the transmission device stops driving the card-delivering device. 
     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 
         FIG. 1  is a card-feeding mechanism according to the prior art. 
         FIG. 2  shows a card-feeding mechanism based on the present invention. 
         FIG. 3  shows a unidirectional bearing, the second gear, and the second roller of  FIG. 2 . 
         FIG. 4  is a lateral view when the card-feeding mechanism of  FIG. 2  is not operating. 
         FIG. 5  to  FIG. 7  show how the card-feeding mechanism of the present invention operates. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 2 , which shows a card-feeding mechanism  100  based on the present invention. The card-feeding mechanism  100  comprises a card-delivering device  130 , a card-receiving device  140 , a transmission device  120 , a driver  110 , a limiting device  150 , and a sensor  160 . The details for each device are described as follows. 
     The card-receiving device  140  comprises a third roller  146  having an eighth gear  144  positioned on an axle  148  of the third roller  146 , and a ninth gear  142  positioned between the eighth gear  144  and the transmission device  120 . The transmission device  120  is a V-shaped panel. There are a fifth gear  122  positioned at a first end of the V-shaped panel, a sixth gear  124  positioned at a second end of the V-shaped panel, and a seventh gear  126  positioned between the fifth gear  122  and the sixth gear  124  and engaging the driver  110 . The driver  110  comprises a motor  122  and a gear set comprising gears  114  and  116 . 
     The card-delivering device  130  comprises a first roller  131  having a first gear  133  positioned on an axle  132  of the first roller  131 , a second roller  134  having a second gear  136  positioned on an axle  135  of the second roller  134 , a third gear  138  positioned between the first gear  133  and the second gear  136 , and a fourth gear  139  positioned between the second gear  136  and the fifth gear  122  of the transmission device  120 . 
     Please refer to  FIG. 3 , which shows a unidirectional bearing  137 , the second gear  136 , and the second roller  134  of  FIG. 2 . The unidirectional bearing  137  is positioned inside the second gear  136 . When the transmission device  120  drives the card-delivering device  130  to rotate, the unidirectional bearing  137  causes the second gear  136  to drive the second roller  134  to rotate. The unidirectional bearing  137  causes the second roller  134  not to drive the second gear  136  to rotate when the transmission device  120  does not drive the card-delivering device  130 . 
     Please refer to  FIG. 4 , which is a lateral view when the card-feeding mechanism  100  of  FIG. 2  is not operating. The limiting device  150  limits a thickness of cards  171 ,  172  to ensure there is only one card passing through the limiting device  150  at a time. When the card-feeding mechanism  100  does not operate, the fifth gear  122  of the transmission device  120  engages the fourth gear  139  of the card-delivering device  130  while the sixth gear  124  of the transmission device  120  engages the ninth gear  142  of the card-receiving device  140 . The seventh gear  126  of the transmission device  120  engages the gear  116  of the driver  110  for receiving a rotating force provided by the motor  112 . 
     Please refer to  FIG. 5 , which is a lateral view when the card-feeding mechanism  100  of  FIG. 2  starts to operate. When the motor  112  starts to rotate clockwise, the gear  114  positioned on the motor  112  also rotates clockwise, and provides the rotating force to the transmission device  120  via the gear  116 . After the motor  112  rotates, the V-shaped panel swings to engage the fifth gear  122  with the eighth gear  144 , and then swings to engage the fourth gear  139  with the ninth gear  142 . Therefore, the transmission device  120  is simultaneously connected to the card-delivering device  130  and the card-receiving device  140  via the fifth gear  122  and the sixth gear  124  to cause the transmission device  120  to drive the card-delivering device  130  and the card-receiving device  140 . As shown in  FIG. 5 , the first gear  133 , the second gear  136 , and the eighth gear  144  rotate counterclockwise simultaneously and drives rollers  131 ,  134 ,  146  correspondingly. 
     The friction forces between the card  171  and the first roller  131 , and between the card  171  and the second roller  134  are greater than the friction force between the cards  171  and  172  due to the rotation of the first roller  131  and the second roller  134 . Therefore, the card  171  can be pushed in a first direction. When the card  171  passes through the limiting device  150 , the third roller  146  of the card-receiving device  140  assists the card  171  in moving in the first direction. 
     Please refer to  FIG. 6 , which is a lateral view when the motor  112  rotates in reverse. When the sensor  160  detects the card  171 , a signal is sent to cause the motor  122  to rotate in reverse (counterclockwise). At the same time, the seventh gear  126  receives a reverse rotation. Since a torque generated by the friction force between the V-shaped panel and the central axle of such is smaller than a torque generated by the friction force between the V-shaped panel and the fifth gear  122 , and between the V-shaped panel and the sixth gear  124 , when the motor  122  rotates in reverse, the fifth gear  122  of the transmission device  120  disengages the fourth gear  139  of the card-delivering device  130 , and engages the eighth gear  144  of the card-receiving device  140 . The sixth gear  124  of transmission device  120  also disengages the ninth gear  142  of the card-receiving device  140 . Therefore, in  FIG. 6 , the transmission device  120  only drives the card-receiving device  140  while the first roller  131  and the second roller  134  are driven by the movement of the card  171 . 
     Please refer to  FIG. 7 , which is a lateral view after the motor  122  rotates in reverse. In  FIG. 7 , the card  171  departs from the first roller  131 , and only drives the second roller  134  to rotate. Due to the unidirectional bearing  137 , the rotation of the second roller  134  will not drive the second gear  136  to rotate. Thus, the second gear  136  and the unidirectional bearing  137  of  FIG. 7  remain still. The card  172  on top of the card  171  contacts the first roller  131 . Because of the friction force between the card  172  and the first roller  131 , the first roller  131  is still until the card  171  is completely pushed into the printer to cause the motor  122  to rotate clockwise, thereby starting to push the next card  172  into the printer. 
     Compared to the prior art, the card-feeding mechanism  100  of the present invention utilizes the first roller  131  and the second roller  134  to simultaneously push the card  171  in the first direction. This means that the card  171  is transferred more smoothly. Additionally, the friction force between the card and the two rollers  131 ,  134  is increased, and thereby the present invention does not require adhesive material on the rollers  131 ,  134 , increasing a life-span of the rollers  131 ,  134 . 
     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.