Toshiba e-studio555 - Automatic Original Size Detection Circuit; Principle of Original Size Detection; Process of Original Size Detection

6
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SCANNING SECTION
6 - 9
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
The 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 size of the original is detected by checking which
phototransistors are turned on or are not.
Fig. 6-10
6.6.2 Process of original size detection
1. When the equipment is in the original size detection mode, the carriage-1 is set at its home position.
2. When the RADF is opened, the sensors receive the light reflected from the original and if one of the
matrix conditions shown in 4) for original sizes is satisfied, the size of the original is instantly
detected.
3. The output signal from each sensor is input to the CPU on the scanner control PC board to
determine the size of the original.
Fig. 6-11
APS-3
APS-1
APS-2
APS-C
APS-R
Original Original glass
[
A4 Series
][
LT Series
]
APS-3
APS-2
APS-C
APS-R
Original Original glass
SLG board
APS-C
APS-3
APS-2
APS-R
IC10
Scanner
CPU
+5.1VD
SG
+5.1VD
SGSLG board
APS-C
APS-2
APS-3
APS-1
APS-R
IC10
Scanner
CPU
Reflection type
photosensor
Reflection type
photosensor
[
A4 Series
][
LT Series
]