Punch

A punch connected to a machine such as an automatic paper feeder or a copying machine for receiving sheet-like members one by one, which are sent from said machine, and forming punched holes for filing in each sheet-like member at a predetermined punching position thereof, comprising:

• feeding means for feeding each received sheet-like member along a feed path, said feeding means including a feed roller mechanism and a DC motor driving said feed roller mechanism;
• position determination means for determining said predetermined punching position, at which each sheet-like member fed by said feeding means is punched, said position determination means including sensor means operative for detecting one of the leading and trailing ends of the sheet-like member in said feed path and providing an electrical detection signal;
• a punching member opposing said predetermined punching position and capable of executing a punching operation with a predetermined stroke to form punched holes for filing in the sheet-like member at said punching position thereof;
• first electrical-to-mechanical conversion element means for generating a predetermined amount of dimensional strain upon receipt of said electrical detection signal;
• first enlargement means for enlarging the dimensional strain generated in said first electrical-to-mechanical conversion element means and transmitting the enlarged dimensional strain to said punching member, thereby causing execution of the punching operation of said punching member with said predetermined stroke;
• and
• guide means defining said feed path and offering a predetermined feed resistance to the sheet-like member being fed along said feed path, wherein:
• said feed roller mechanism includes a drive roller and a driven roller, said feed roller mechanism being shiftable between an operative position, in which said driven roller is urged against the drive roller to feed said sheet-like member in a pinched state with a predetermined feeding force and an inoperative position, in which said driven roller is disengaged from the drive roller to provide substantially no feeding force to said sheet-like member;
• said position determination means further includes a shifting mechanism for shifting said driven roller from said operative position to said inoperative position temporarily in response to the operation of said sensor means to have said sheet-like member released from said feeding force and held stationary momentarily at said predetermined punching position;
• said drive roller is disposed at a stationary non-contact position to be normally out of contact with the sheet-like member running along said feed path, said driven roller being operable, when said feed roller mechanism is in said operative position, to cause sagging of the sheet-like member and thereby urge the sheet-like member against said drive roller, and when said feed roller mechanism is in the inoperative position, said driven roller being shifted by said shifting mechanism to be separated from said drive roller to release the sheet-like member from contact with said drive roller, thereby stopping the sheet-like member;
• and
• said guide means includes a pair of substantially parallel guide plates defining said feed path therebetween, and includes a brake portion operable in response to the shift of said driven roller from said operative position to said inoperative position to urge the running sheet-like member against one of said guide plates, thereby braking the sheet-like member.