Automatic Original Size Detection Circuit; Principle Of Original Size Detection - Toshiba e-studio 167 Service Manual

6.6

Automatic Original Size Detection Circuit

This circuit detects the size of original (standard sizes only) using the reflection type photosensors
arranged on the base frame of the scanner unit.
6.6.1

Principle of original size detection

Reflection type photosensors are placed on the base frame of the scanner unit as shown in the figure
below. Each sensor consists of an infrared Light Emitting Diode (LED) on the light emitting side, and a
phototransistor on the light receiving side.
When there is an original on the original glass, light beams from the LEDs are reflected by the original
and led to the phototransistors. This means that the presence of the original is detected by the pres-
ence of reflection (when scanning black image).
[ A4 Series ]
Original
APS-3
APS-1
APS-2
e-STUDIO167/207/237
SCANNER
Original glass
APS-R
APS-C
Fig. 6-7
6 - 12
[ LT Series ]
Original
APS-3
APS-2
APS-C
© 2007 - 2008 TOSHIBA TEC CORPORATION All rights reserved
Original glass
APS-R