Document Presence/Absence Detection; Detection Of Last Document - Canon DADF-AA1 Service Manual

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b. Mixed size print mode and banner paper mode

In the mixed size print mode and banner paper mode, the following three document detection functions are used:

Document presence/

absence detection

Last document detection

Document length detection Detects the document length

3.3.2 Document Presence/Absence Detection

The document placement sensor (SR5) detects presence/absence of a document on the document tray.

When a document is placed on the document tray, the detection lever moves the light shielding plate to allow light to pass thorough the photo interrupter. Thus, the

document placement sensor (SR5) generates an document detection signal (EMPTY_SEN) to notify the host machine that an document has been placed on the

document tray via the ADF drive PCB.

3.3.3 Detection of Last Document

The last document detection sensor (SR9) and document placement sensor (SR5) detect whether the document being picked up is the last one.

When the trailing edge of the last document has moved past the last document detection lever, the detection lever moves the light shielding plate to allow light pass

through the photo interrupter. Thus, the last document detection sensor (SR9) generates a last document detection signal (LAST_SEN). When the last document

has moved past the document sensor (SR5), a document absence signal (EMPTY_SEN) is generated to notify the host machine that the document being picked up

is the last one via the ADF drive PCB.

Function

Description

Detects whether there is a document

on the document pickup tray.

Detects whether the document being

fed is the last one.

according to the distance from the

position where the read sensor (SR2)

turns on to the position where the read

sensor (SR2) turns off.

ADF driver PCB