Patent ID: 8810874

Claim:
A duplex scanning apparatus, comprising: a sheet entrance and a sheet exit; a sheet feeding channel connected to said sheet entrance; a sheet pick-up module disposed in said sheet entrance for feeding a document into said sheet feeding channel; a sheet transfer channel arranged between said sheet feeding channel and said sheet exit; an inverting channel, wherein a first end of said inverting channel is connected to a junction between said sheet feeding channel and said sheet transfer channel, and a second end of said inverting channel is connected to said sheet transfer channel; an image reading module disposed in said sheet transfer channel for reading an image of a document; a transfer roller assembly for transferring said document which is located within said sheet feeding channel, said sheet transfer channel or said inverting channel; a sheet sensing module for sensing a transmitting status of said document in said inverting channel, thereby issuing a sensing signal, wherein said sheet sensing module comprises: a first sensing arm at least partially exposed to said inverting channel, wherein when said document is transferred through said inverting channel, said first sensing arm is pushed by said document; an electronic sensor for issuing said sensing signal according to a moving status of said first sensing arm, wherein said electronic sensor is an optical sensor, wherein said optical sensor has an emitting part for emitting a light beam and a receiving part for receiving said light beam; and a second sensing arm, which is at least partially exposed to said sheet feeding channel, wherein when said document is transferred through said sheet feeding channel, said second sensing arm is pushed by said document, wherein said electronic sensor issues said sensing signal according to a moving status of said second sensing arm; and a controller electrically connected to said sheet pick-up module and said sheet sensing module, wherein in response to said sensing signal, said controller drives said sheet pick-up module to feed a next document into said sheet feeding channel, wherein a distance between said sheet sensing module and said first end of said inverting channel is greater than a distance between said sheet sensing module and said second end of said inverting channel.