Automatic Original Size Detection Circuit; Principle Of Original Size Detection - Toshiba e-STUDIO182 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
presence of reflection (when scanning black image).
[ A4 Series ]
Original
APS-3
APS-1
APS-2
© 2009 TOSHIBA TEC CORPORATION All rights reserved
[ LT Series ]
Original glass
APS-R
APS-C
Fig. 6-6
6 - 11
Original
APS-3
APS-2
APS-C
Original glass
APS-R
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SCANNER
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