US Patent 7243830 Staple-leg guide mechanism

A guide piece 19 that enters between both legs 2b of a staple 2 is formed integrally on a pusher 16 that pushes a staple 2 as formed into a striking passage 12, an inclined surface 20 that engages with a staple 2 to operatively retreat the pusher is formed on the guide piece 19 to be positioned thereon so as not to engage with the staple 2 until tip ends of staple legs 2b penetrate through sheets, and a driver plate 7 and a forming plate 6 are set to operate out of phase relative to each other so that the forming plate 6 begins forming of a non-formed staple 2a after staple legs 2b struck out have penetrated through the sheets.