Automatic Original Size Detection Circuit; Principle Of Original Size Detection - Toshiba e-STUDIO200L Service Manual

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.
[ A4 Series ]
Original
APS-3
APS-1
APS-2
e-STUDIO200L/202L/203L/230/232/233/280/282/283
SCANNER
Original glass
APS-R
APS-C
Fig. 6-14
6 - 12
[ LT Series ]
Original
APS-3
APS-2
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Original glass
APS-R
APS-C