Canon iR C2880 Series Service Manual page 173

Contents
5.1 Construction ...................................................................................................................................................................5-1
5.1.1 Specifications, Control Mechanisms, and Functions ................................................................................................................... 5-1
5.1.2 Major Components....................................................................................................................................................................... 5-1
5.1.3 Construction of the Control System............................................................................................................................................. 5-2
5.1.4 Reader Controller PCB ................................................................................................................................................................ 5-4
5.2 Basic Sequence ..............................................................................................................................................................5-5
5.2.1 Basic Sequence of Operations at Power-On ................................................................................................................................ 5-5
5.2.2 Basic Sequence of Operations in Response to a Press on the Start Key (book mode, 1 original)............................................... 5-5
5.2.3 Basic Sequence of Operations in Response to a Press on the Start Key (ADF mode, 1 original)............................................... 5-6
5.3 Various Control Mechanisms.........................................................................................................................................5-7
5.3.1 Controlling the Scanner Drive System ........................................................................................................................................ 5-7
5.3.1.1 Overview .........................................................................................................................................................................................................5-7
5.3.1.2 Reader Motor Control .....................................................................................................................................................................................5-7
5.3.2 Contact Image Sensor (CIS) ........................................................................................................................................................ 5-9
5.3.2.1 Overview .........................................................................................................................................................................................................5-9
5.3.2.2 Analog Control Inside the Contact Image Sensor (CIS) ...............................................................................................................................5-10
5.3.3 Enlargement/Reduction.............................................................................................................................................................. 5-10
5.3.3.1 Changing the Magnification in Main Scanning Direction ............................................................................................................................5-10
5.3.3.2 Changing the Magnification in Sub Scanning Direction ..............................................................................................................................5-10
5.3.4 Controlling the Scanning Lamp ................................................................................................................................................. 5-11
5.3.4.1 Scanning Lamp..............................................................................................................................................................................................5-11
5.3.4.2 Overview .......................................................................................................................................................................................................5-11
5.3.4.3 Activation Control.........................................................................................................................................................................................5-11
5.3.4.4 Error Detection..............................................................................................................................................................................................5-11
5.3.5 Detecting the Size of Originals .................................................................................................................................................. 5-11
5.3.5.1 Overview .......................................................................................................................................................................................................5-11
5.3.5.2 Points of Original Size Detection..................................................................................................................................................................5-12
5.3.5.3 Overview of Detection Operation .................................................................................................................................................................5-12
5.3.6 Dirt Sensor Control .................................................................................................................................................................... 5-14
5.3.6.1 Overview .......................................................................................................................................................................................................5-14
5.3.7 Image Processing ....................................................................................................................................................................... 5-16
5.3.7.1 Overview .......................................................................................................................................................................................................5-16
5.3.7.2 Driving the CCD ...........................................................................................................................................................................................5-17
5.3.7.3 Gain Correction and Offset Correction for the CCD Output ........................................................................................................................5-17
5.3.7.4 A/D Conversion of the CCD Output.............................................................................................................................................................5-17
5.3.7.5 Shading Correction (outline).........................................................................................................................................................................5-17
5.3.7.6 Shading Adjustment ......................................................................................................................................................................................5-18
5.3.7.7 Shading Correction........................................................................................................................................................................................5-18
5.4 Parts Replacement Procedure.......................................................................................................................................5-19
5.4.1 Copyboard Glass ........................................................................................................................................................................ 5-19
5.4.1.1 Removing the Copyboard Glass....................................................................................................................................................................5-19
5.4.1.2 After Replacing the Copyboard Glass...........................................................................................................................................................5-19
5.4.1.3 Removing the ADF Reading Glass ...............................................................................................................................................................5-20
5.4.1.4 After Replacing the ADF Reading Glass ......................................................................................................................................................5-20
5.4.2 Reader Controller PCB .............................................................................................................................................................. 5-21
5.4.2.1 Before Replacing the Reader Controller PCB ..............................................................................................................................................5-21
5.4.2.2 Before Removing the Reader Controller PCB ..............................................................................................................................................5-21
5.4.2.3 Removing the Reader Controller PCB..........................................................................................................................................................5-21
5.4.2.4 After Replacing the Reader Controller PCB.................................................................................................................................................5-22
5.4.3 Inverter PCB .............................................................................................................................................................................. 5-23
5.4.3.1 Before Removing the Inverter PCB ..............................................................................................................................................................5-23
5.4.3.2 Removing the Inverter PCB ..........................................................................................................................................................................5-23
5.4.4 Scanner Motor............................................................................................................................................................................ 5-24
Contents