Gestetner B147 Service Manual page 20

Step 6: ID Sensor Highlight Pattern Generation .................................6-13
Step 7: Sensor Pattern Density Detection...........................................6-13
Step 8: VL (LD Power) Selection ........................................................6-13
6.2.4 VREF COMPENSATION DURING A PRINT JOB ..........................6-14
Highlight Pattern .................................................................................6-14
Adjustment Process ............................................................................6-14
6.2.5 TONER SUPPLY CONTROL .........................................................6-15
Overview.............................................................................................6-15
Toner Supply Control Modes ..............................................................6-15
6.2.6 TONER NEAR END/TONER END DETECTION ............................6-16
Introduction .........................................................................................6-16
Toner Near End Detection 1 ...............................................................6-17
Toner Near End Detection 2 ...............................................................6-17
Toner End Detection ...........................................................................6-18
Toner End Recovery ...........................................................................6-18
6.2.7 DEVELOPER INITIALIZATION ......................................................6-19
6.3 SCANNING..............................................................................................6-20
6.3.1 OVERVIEW ....................................................................................6-20
6.3.2 SCANNER DRIVE ..........................................................................6-21
6.3.3 ORIGINAL SIZE DETECTION........................................................6-22
6.3.4 ANTI-CONDENSATION HEATER ..................................................6-23
6.4 IMAGE PROCESSING ............................................................................6-24
6.4.1 OVERVIEW ....................................................................................6-24
6.4.2 SBU BLOCK DIAGRAM .................................................................6-25
Signal Processing ...............................................................................6-25
A/D Conversion...................................................................................6-25
White Level Correction........................................................................6-25
Others .................................................................................................6-25
Black Level Correction ........................................................................6-26
Adjustments ........................................................................................6-26
VPU Test Mode ..................................................................................6-26
6.4.3 IPU BLOCK DIAGRAM...................................................................6-27
Shading Correction .............................................................................6-27
Picture Element (Dot Position) Correction ..........................................6-28
Scan Line Correction ..........................................................................6-28
Image Separation................................................................................6-28
ACS (Auto Color Select) .....................................................................6-29
Scanner Gamma Correction (RGB Gamma Correction) .....................6-30
Filtering ...............................................................................................6-31
ADS (Auto Image Density Selection) ..................................................6-31
Color Conversion ................................................................................6-32
Main Scan Magnification.....................................................................6-33
Printer Gamma Correction ..................................................................6-34
Error Diffusion .....................................................................................6-36
IPU Board Test ...................................................................................6-36
6.5 IMAGE DATA PATH................................................................................6-37
Copier Application...............................................................................6-37
Printer Application...............................................................................6-37
Scanner Application (1 bit/8 bits) ........................................................6-37
B147/B149/B190 viii SM