6.Paper End Sensor Circuit
Fig. 6-1 shows the paper end sensor circuit. The reflection type photo-interrupter is used as a sensor. When some paper is still left, the light reflected by paper strikes upon the photo-transistor; thus, the collector of the photo- transistor is L. When paper becomes short, no light is reflected, causing the collector to go H. As a result, the CPU input port P40 becomes H, going into the paper end state.
Control Circuit
Vcc
Paper End Sensor
PHI 1
CPU
R12 | R15 | P40 |
| R13 | |
|
|
C11Tr3
R14
Fig. 6-1 Paper End Sensor Circuit
13
