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e-STUDIO3511/4511 SCANNER 6 - 12 November 2003 © TOSHIBA TEC
6
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 Fig. 6-
601. 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).
Fig. 6-601
Fig. 6-602 Original size detection circuit
APS-3
APS-1
APS-2
APS-C
APS-R
Original
Original glass
[A4 Series]
APS-3
APS-2
APS-C
APS-R
[LT Series]
Original glass
Original
V
DD
GND
PWA-SLG
APS-C
APS-3
APS-2
APS-R
CPU
Reflection type
photosensor
[LT Series][A4 Series]
V
DD
GND
PWA-SLG
APS-C
APS-3
APS-2
APS-1
APS-R
CPU
6.6.2 Process of detection of original size
(1) When the equipment is in the original size detection mode, carriage-1 is set at its home position.
(2) When the platen cover is opened, the sensors receive the light reflected from the original and if one
of the matrix conditions shown in (4) for original sizes are met, the size of the original is instantly
detected.
(3) The output signal from each sensor is input to CPU on the scanning section control PC board to
determine the size of the original.
Reflection type
photosensor