Plate lockup device position detecting apparatus for printing press

A plate lockup device position detecting apparatus for a printing press, comprising:

• a plate cylinder having a circumferential surface on which a plate is mounted;
• a gap formed in the circumferential surface of said plate cylinder in an axial direction thereof and having a bottom portion;
• a leading-side plate lockup device provided in said gap and having a first recess formed on a bottom side thereof, the leading-side plate lockup device being slidable on the bottom portion of the gap;
• a trailing-side plate lockup device provided in parallel with said leading-side plate lockup device in said gap and having a second recess formed on a bottom side thereof, the trailing-side plate lockup device being slidable on the bottom portion of the gap;
• a first origin position detecting switch with a first actuating member, fixed on the bottom portion of said gap, for detecting that said leading-side plate lockup device, a position of which is adjustable at least in one of vertical and horizontal directions of the plate, is restored to a first origin thereof, said first actuating member capable of being engaged with the first recess of said leading-side plate lockup device when the leading-side plate lockup device is located at the first origin position thereof;
• a second origin position detecting switch with a second actuating member, fixed on the bottom portion of said gap, for detecting that said trailing-side plate lockup device, a position of which is adjustable at least in one of vertical and horizontal directions of the plate, is restored to a second origin position thereof, said second actuating member capable of being engaged with the second recess of said trailing-side plate lockup device when the trailing-side plate lockup device is located at the second origin position thereof;
• and
• informing means for informing that said leading- and trailing-side plate lockup devices are respectively restored to the first and second origin positions on the basis of detection outputs from said first and second origin position detecting switches.