Ricoh B121 Service Manual page 19

6.1.1 COMPONENT LAYOUT ...................................................................6-1
6.1.2 PAPER PATH ...................................................................................6-3
6.1.3 DRIVE LAYOUT ...............................................................................6-4
6.2 BOARD STRUCTURE...............................................................................6-5
6.2.1 BLOCK DIAGRAM............................................................................6-5
1. BICU (Base Engine and Image Control Unit)......................................6-6
2. SBU (Sensor Board Unit)....................................................................6-6
6.3 COPY PROCESS OVERVIEW..................................................................6-7
6.4 SCANNING................................................................................................6-9
6.4.1 OVERVIEW ......................................................................................6-9
Lamp Stabilizer Fuse ............................................................................6-9
6.4.2 SCANNER DRIVE ..........................................................................6-10
6.4.3 ORIGINAL SIZE DETECTION IN PLATEN MODE.........................6-11
6.5 IMAGE PROCESSING ............................................................................6-13
6.5.1 OVERVIEW ....................................................................................6-13
6.5.2 SBU (SENSOR BOARD UNIT).......................................................6-14
6.5.3 IPU (IMAGE PROCESSING UNIT).................................................6-15
Overview.............................................................................................6-15
Image Processing Modes ...................................................................6-16
Image Processing Path.......................................................................6-17
Original Modes....................................................................................6-18
SP Modes for Each Image Processing Step .......................................6-18
Auto Shading ......................................................................................6-20
White Line Erase.................................................................................6-21
Black Line Erase .................................................................................6-21
Auto image density (ADS)...................................................................6-22
Scanner Gamma (γ) Correction ..........................................................6-23
Main Scan Magnification.....................................................................6-24
Mirroring for ADF Mode ......................................................................6-24
Filtering ...............................................................................................6-25
ID Gamma (γ) Correction ....................................................................6-26
Gradation Processing .........................................................................6-27
6.5.4 VIDEO CONTROL UNIT (VCU)......................................................6-28
Fine Character and Image (FCI) .........................................................6-28
Printer Gamma Correction ..................................................................6-28
6.6 LASER EXPOSURE................................................................................6-29
6.6.1 OVERVIEW ....................................................................................6-29
6.6.2 AUTO POWER CONTROL (APC) ..................................................6-30
6.6.3 LD SAFETY SWITCH .....................................................................6-31
6.7 PHOTOCONDUCTOR UNIT (PCU) ........................................................6-32
6.7.1 OVERVIEW ....................................................................................6-32
6.7.2 DRIVE.............................................................................................6-33
6.8 DRUM CHARGE .....................................................................................6-34
6.8.1 OVERVIEW ....................................................................................6-34
6.8.2 CHARGE ROLLER VOLTAGE CORRECTION ..............................6-35
Correction for Environmental Conditions ............................................6-35
6.8.3 ID SENSOR PATTERN PRODUCTION TIMING............................6-36
6.8.4 DRUM CHARGE ROLLER CLEANING ..........................................6-37
6.9 DEVELOPMENT .....................................................................................6-38
SM vii B121 Series/B259 Series