The Digital Photocell is a micro controller based unit. It consists of the Display Unit and the IO-Interface unit as shown in Figure 1. The Display Unit consists of 2 line seven segment displays and 25 keys feather touch keyboard. The upper line of the display shows various parameters such as sheet count, batch count value, and error message at impression OFF etc. whereas the lower line displays the machine speed in Rotations Per Hour. The Keyboard is used for programming the batch counter and various other functions of the controller. The IO-Interface unit is used to interface various inputsand outputs between machine and Photocell Controller
Figure 1: Photocell Unit comprising of display unit and the IO-Interface unit
Salient Features:
It controls the Feeder ON/OFF.
Front Lay Control.
Impression Control.
Overshoot control.
Machine Speed Display (RPH).
Batch Counter.
Error Display.
Advantages:
Avoiding damage to blankets by not allowing misaligned or mistimed sheets to be printed. Thus helps enormous cost savings.
Display of Error Message at impression OFF helps realize the cause of error at the first attempt.
Sheet Counter helps keep a track of the number of printed sheets.
Batch Counter is useful in printing a predetermined number of sheets after which the controller commands the machine to stop printing.
Auto control of impression, Feeder and Lay assures minimum wastage of sheets as it avoids back printing and also blank sheets.
