Toshiba e-STUDIO182 Service Manual page 109

About reflection type photosensor
The reflection type photosensor is comprised of an infrared light emitting diode and a phototransistor. It
uses pulse modulation to detect an original.
Original
8 µsec
130 µsec LED Phototransistor
Fig. 6-10
The light emitting diode is driven by a pulse having a 130 µsec. cycle and an 8 µsec. ON time. When
the phototransistor receives the same signal as this pulse, it is determined that there is an original. The
6
pulse modulation is performed inside the reflection type phototransistor.
© 2009 TOSHIBA TEC CORPORATION All rights reserved e-STUDIO182/212/242
SCANNER
6 - 15