Motor-driven stapler

A motor-driven stapler comprising a table arranged as opposed to a staple drive portion for driving a staple and provided movably up and down on a stapler body, and a driver for driving a staple from said staple drive portion to sheets of paper when said table has been moved to press said sheets of paper against said staple drive portion,

• said motor-driven stapler being provided with a position sensor mechanism for sensing a home position of said table, wherein
• said position sensor mechanism comprises a position cam provided on a drive shaft for moving said table up and down, a sensor arm one end of which is rotatably pivoted, and arm sensor means for sensing that said sensor arm has rotated to a predetermined position,
• said position cam is provided, on a circumferential surface thereof, with a recessed portion for indicating said home position and a projected portion symmetrically opposite to the recessed portion, and
• said sensor arm has a first arm portion where a first top end portion is slidingly in contact with the circumferential surface of said position cam, a second arm portion where a second top end portion is slidingly in contact with the circumferential surface of said position cam, wherein said first top end portion and said second top end portion sandwich said position cam, said first top end portion is slidingly in contact with said recessed portion, and said second top end portion is slidingly in contact with said projected portion and said sensor arm rotates to a predetermined position.