Canon imagerunner C5180 Service Manual page 166

Contents
6.1 Construction ....................................................................................................... 6-1
6.1.1 Specifications, Control Mechanisms, and Functions............................................ 6-1
6.1.2 Major Components..................................................................................................... 6-2
6.1.3 Construction of the Control System ........................................................................ 6-4
6.1.4 Reader Controller PCB ............................................................................................. 6-5
6.2 Basic Sequence................................................................................................. 6-6
6.2.1 Basic Sequence of Operation at Power-On........................................................... 6-6
6.2.2 Basic Sequence of Operation in Response to a Press on the Start Key .......... 6-7
6.3 Various Control Mechanisms .......................................................................... 6-9
6.3.1 Controlling the Scanner Drive System ....................................................................6-9
6.3.1.1 Overview ................................................................................................................................ 6-9
6.3.1.2 Controlling the Scanner Motor.......................................................................................... 6-10
6.3.2 Enlargement/Reduction ..........................................................................................6-11
6.3.2.1 Changing the Magnification in Main Scanning Direction.............................................. 6-11
6.3.2.2 Changing the Magnification in Sub Scanning Direction ............................................... 6-11
6.3.3 Controlling the Scanning Lamp ..............................................................................6-11
6.3.3.1 Overview .............................................................................................................................. 6-11
6.3.3.2 Scanning Lamp ................................................................................................................... 6-12
6.3.3.3 Turning On and Off the Scanning Lamp......................................................................... 6-12
6.3.4 Detecting the Size of Originals ..............................................................................6-12
6.3.4.1 Identifying the Size of Originals........................................................................................ 6-12
6.3.4.2 Points of Measurement Used for Original Size Identification ...................................... 6-13
6.3.4.3 Overview of Operation ....................................................................................................... 6-15
6.3.5 Dirt Sensor Control ..................................................................................................6-17
6.3.5.1 Stream Reading Dust Detection Control ........................................................................ 6-17
6.3.5.2 White Plate Dust Detection Control ................................................................................. 6-19
6.3.6 Image Processing ....................................................................................................6-21
6.3.6.1 Overview .............................................................................................................................. 6-21
6.3.6.2 CCD Drive............................................................................................................................ 6-22
6.3.6.3 CCD Gain Correction, Offset Correction ........................................................................ 6-22
6.3.6.4 CCD Output A/D Conversion............................................................................................ 6-22
6.3.6.5 Outline of Shading Correction .......................................................................................... 6-22
6.3.6.6 Shading Adjustment ........................................................................................................... 6-23
6.3.6.7 Shading Correction ............................................................................................................ 6-23
6.4 Parts Replacement Procedure...................................................................... 6-24
6.4.1 Copyboard Glass .....................................................................................................6-24
6.4.2 Exposure Lamp ........................................................................................................6-24
6.4.3 Reader Controller PCB ...........................................................................................6-25
Contents