Canon imageRUNNER ADVANCE C5500 Series Service Manual page 67

When an original is placed in the Document Pickup Tray, the detection lever of the LTR-R/ LGL Sensor (PS_A3) operates with
the Lightproof Plate and the Lightproof Plate blocks the Photo Interrupter.
At the same time, the reflective Large Size/ Small Size Sensor (PS_R3) detects whether the original has reflecting light.
The size of a paper in the Document Pickup Tray is estimated based on the signal (LGL_S) of the LTR-R/ LGL Sensor (PS_A3),
the signal (LGL_S2) of the Large Size/ Small Size Sensor (PS_R3), and the original width.
The original size is detected in real-time when turning ON the start key and sent to the connected equipment.
● Detection in the Width Direction
The original size in the width direction is detected using the Original Width Volume (UN_SNS1) and AB/ Inch Sensor (PS_A4) in
the Document Pickup Tray.
The analog resistance value of the Original Width Volume (UN_SNS1) changes according to the Slide Guide. The ADF Driver
PCB receives this change in the resistance value as an original size signal (UN_SNS1), and uses it as the size in the width
direction.
The AB/ Inch Sensor (PS_A4) is located inside the Document Pickup Tray to enable accurate width detection of A4R/LTRR and
A5R/STMTR using the Original Width Volume (UN_SNS1). The AB/ Inch Sensor (PS_A4) outputs "1" for the AB/inch detection
signal (A4LT_S) when the original width is "127 mm or more and less than 148 mm" or "197 mm or more and less than 214 mm".
LGL Size Original
Slide Guide
(Rear)
Gear
Original Width Volume
(UN_SNS1)
ADF Driver PCB
PS_A3
PS_R3
ADF Driver PCB
AB/ Inch
Determination Sensor
(PS_A4)
53
2. Technology
Detecting Flag
Slide Guide
(Front)