Transmission device for automatic document feeder

A transmission device for an automatic document feeder, the automatic document feeder defining a paper transmitting path, a pickup device, transmitting rollers and an output device being disposed along the paper transmitting path, the transmission device being disposed among the pickup device, the transmitting rollers and the output device for transmitting the driving torque of a driving motor which is located in the automatic document feeder, the transmission device comprising:

• a driving gear set driven by the driving motor and disposed between the pickup device and the output device;
• a first swing arm driven by the driving gear set and equipped with a first driving roller set, the first swing arm being swingable according to the rotating direction of the driving gear set between a first position meshing the first driving roller set with the pickup device to apply the driving torque to the pickup device, and a second position meshing the first driving roller set with the output device to apply the driving torque to the output device;
• a second swing arm driven by the driving gear set and equipped with a second driving roller set, the second swing arm being swingable according to the rotating direction of the driving gear set between a third position meshing the second driving roller set with the pickup device to apply the driving torque to the pickup device, and a fourth position meshing the second driving roller set with the output device to apply the driving torque to the output device;
• and
• a one-way gear set driven by the driving gear set for applying the driving torque in a constant direction to the transmitting rollers regardless of the rotating direction of the driving gear set;
• wherein when the first swing arm swings toward the first position, the second arm swings toward the fourth position, and when the first swing arm swings toward the second position, the second swing arm swings toward the third position.