Canon iR2020 Series Service Manual page 139

Contents
4.1 Construction ...................................................................................................................................................................4-1
4.1.1 Specifications, Control Methods, and Functions (iR2020/iR2020J/iR2020i) ............................................................................. 4-1
4.1.2 Specifications, Control Methods, and Functions (iR2016/iR2016J/iR2016i) ............................................................................. 4-1
4.1.3 Major Components (iR2020/iR2020J/iR2020i)........................................................................................................................... 4-1
4.1.4 Major Components (iR2016/iR2016J/iR2016i)........................................................................................................................... 4-2
4.1.5 Control System Configuration (iR2020/iR2020J/iR2020i) ......................................................................................................... 4-3
4.1.6 Control System Configuration (iR2016/iR2016J/iR2016i) ......................................................................................................... 4-3
4.1.7 Reader Controller PCB (iR2020/iR2020J/iR2020i) .................................................................................................................... 4-4
4.1.8 Reader Controller PCB (iR2016/iR2016J/iR2016i) .................................................................................................................... 4-5
4.2 Basic Sequence ..............................................................................................................................................................4-5
4.2.1 Basic Sequence at Power-on ........................................................................................................................................................ 4-5
4.2.2 Basic Sequence after Depression of Start Key (Book mode, One Sheet of original) .................................................................. 4-6
4.2.3 Basic Sequence after Depression of Start Key (ADF Mode, One Sheet of Original) ................................................................. 4-6
4.3 Various Control..............................................................................................................................................................4-7
4.3.1 Controlling the Scanner Drive System ........................................................................................................................................ 4-7
4.3.1.1 Outline.............................................................................................................................................................................................................4-7
4.3.1.2 Reader Motor Control .....................................................................................................................................................................................4-8
4.3.2 Contact Image Sensor (CIS) ........................................................................................................................................................ 4-8
4.3.2.1 Outline.............................................................................................................................................................................................................4-8
4.3.2.2 Analog Control Performed by the CIS (iR2020/iR2020J/iR2016/iR2016J)...................................................................................................4-9
4.3.2.3 Analog Control Performed by the CIS (iR2020i/iR2016i) ...........................................................................................................................4-10
4.3.3 Enlargement/Reduction.............................................................................................................................................................. 4-10
4.3.3.1 Magnification Change in Vertical Scan Direction ........................................................................................................................................4-10
4.3.3.2 Magnification Change in Horizontal Scan Direction....................................................................................................................................4-10
4.3.4 Detecting the Size of Originals .................................................................................................................................................. 4-10
4.3.4.1 Outline...........................................................................................................................................................................................................4-10
4.3.4.2 Outline of Original Size Detection................................................................................................................................................................4-11
4.3.5 Dirt Sensor Control .................................................................................................................................................................... 4-12
4.3.5.1 Outline...........................................................................................................................................................................................................4-12
4.3.6 Image Processing ....................................................................................................................................................................... 4-14
4.3.6.1 Outline...........................................................................................................................................................................................................4-14
4.3.6.2 CMOS Sensor Drive .....................................................................................................................................................................................4-15
4.3.6.3 CMOS Sensor Output Gain Correction and Offset Correction.....................................................................................................................4-15
4.3.6.4 CMOS Sensor Output A/D Conversion ........................................................................................................................................................4-15
4.3.6.5 Shading Correction (Outline) .......................................................................................................................................................................4-15
4.3.6.6 Shading Adjustment ......................................................................................................................................................................................4-15
4.3.6.7 Shading Correction........................................................................................................................................................................................4-16
4.4 Parts Replacement Procedure.......................................................................................................................................4-17
4.4.1 Copyboard glass......................................................................................................................................................................... 4-17
4.4.1.1 Removing the Copyboard glass ....................................................................................................................................................................4-17
4.4.1.2 Procedure after Replacing the Copyboard Glass (iR2020i/iR2016i) ............................................................................................................4-17
4.4.1.3 Removing the ADF Reading Glass ...............................................................................................................................................................4-17
4.4.2 Reader Controller PCB .............................................................................................................................................................. 4-17
4.4.2.1 Removing the Rear Cover .............................................................................................................................................................................4-17
4.4.2.2 Removing the Right Cover (Lower) .............................................................................................................................................................4-18
4.4.2.3 Removing the Right Cover (Upper) ..............................................................................................................................................................4-18
4.4.2.4 Removing the Left Cover (Rear)...................................................................................................................................................................4-18
4.4.2.5 Removing the Reader Rear Cover.................................................................................................................................................................4-18
4.4.2.6 Removing the Copyboard glass ....................................................................................................................................................................4-19
4.4.2.7 Removing the Reader Controller PCB..........................................................................................................................................................4-19
4.4.3 Scanner Motor............................................................................................................................................................................ 4-20
4.4.3.1 Removing the Rear Cover .............................................................................................................................................................................4-20
4.4.3.2 Removing the Right Cover (Lower) .............................................................................................................................................................4-20
Contents