Parts Replacement Procedure - Canon iR4570 Series Service Manual

Contents
5.1 Construction ....................................................................................................................................................... 5-1
5.1.1 Specifications, Control Mechanisms, and Functions .................................................................................. 5-1
5.1.2 Major Components ...................................................................................................................................... 5-2
5.1.3 Construction of the Control System ............................................................................................................ 5-4
5.1.4 Reader Controller PCB................................................................................................................................ 5-5
5.2 Basic Sequence................................................................................................................................................... 5-7
5.2.1 Basic Sequence of Operation at Power-On ................................................................................................. 5-7
5.2.2 Basic Sequence of Operation in Response to a Press on the Start ............................................................. 5-7
5.2.3 Basic Sequence of Operation in Response to a Press on the Start ............................................................. 5-8
5.3 Various Control ................................................................................................................................................ 5-10
5.3.1 Controlling the Scanner Drive System ...................................................................................................... 5-10
5.3.1.1 Outline ................................................................................................................................................ 5-10
5.3.1.2 Controlling the Reader Motor ............................................................................................................ 5-10
5.3.2 Contact Image Sensor (CIS)...................................................................................................................... 5-12
5.3.2.1 Outline ................................................................................................................................................ 5-12
5.3.2.2 Analog Control Inside the Contact Image Sensor .............................................................................. 5-13
5.3.3 Enlargement/Reduction ............................................................................................................................. 5-14
5.3.3.1 Changing the Magnification in Main Scanning Direction ................................................................. 5-14
5.3.3.2 Varying the Magnification in Sub Scanning Direction ...................................................................... 5-14
5.3.4 Detecting the Size of Originals ................................................................................................................. 5-16
5.3.4.1 Outline ................................................................................................................................................ 5-16
5.3.4.2 Outline of Size Identification ............................................................................................................. 5-17
5.3.5 Dirt Sensor Control ................................................................................................................................... 5-19
5.3.5.1 Outline ................................................................................................................................................ 5-19
5.3.6 Image Processing....................................................................................................................................... 5-22
5.3.6.1 Outline ................................................................................................................................................ 5-22
5.3.6.2 CCD Drive.......................................................................................................................................... 5-23
5.3.6.3 Gain Correction and Offset Correction of the CCD Output............................................................... 5-23
5.3.6.4 A/D Conversion of the CCD Output .................................................................................................. 5-24
5.3.6.5 Shading Correction (outline) .............................................................................................................. 5-24
5.3.6.6 Shading Adjustment ........................................................................................................................... 5-24
5.3.6.7 Shading Correction............................................................................................................................. 5-24

5.4 Parts Replacement Procedure........................................................................................................................... 5-26

5.4.1 Copyboard glass ........................................................................................................................................ 5-26
5.4.1.1 Removing the Copyboard Glass......................................................................................................... 5-26
5.4.1.2 Removing the ADF Reading Glass .................................................................................................... 5-27
5.4.2 Reader Controller PCB.............................................................................................................................. 5-28
5.4.2.1 Before Replacing the Reader Controller PCB.................................................................................... 5-28
5.4.2.2 Removing the Reader Rear Cover...................................................................................................... 5-28
5.4.2.3 Removing the rear cover of the machine............................................................................................ 5-29
5.4.2.4 Removing the flexible cable cover ..................................................................................................... 5-29
5.4.2.5 Removing the Copyboard Glass......................................................................................................... 5-30
5.4.2.6 Removing the Reader Controller PCB ............................................................................................... 5-31
5.4.2.7 After Replacing the Reader Controller PCB or After Initializing the RAM...................................... 5-35
Contents