Toshiba e-studio 202L - Automatic Original Size Detection Circuit; Principle of Original Size Detection

e-STUDIO200L/202L/230/232/280/282 SCANNER June 2004 © TOSHIBA TEC
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6.6 Automatic Original Size Detection Circuit
This circuit detects the size of the 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
The reflection-type photosensors are placed on the base frame of the scanner unit as shown in the Fig.
6-14. Each sensor consists of an infrared LED (Light Emitting Diode) on the light-emitting side, and a
phototransistor on the light-receiving side.
When there is an original on the original glass, the light beams from the LEDs are reflected by the orig-
inal and led to the phototransistors. This means that the presence of the original is detected by the
presence of reflection.
Fig. 6-14
APS-3
APS-2
APS-C
APS-R
APS-3
APS-1
APS-2 APS-C
APS-R
Original Original glass Original Original glass
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A4 Series
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LT Series
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