Ricoh B121 Service Manual page 20

6.9.1 OVERVIEW ....................................................................................6-38
6.9.2 DRIVE.............................................................................................6-39
6.9.3 DEVELOPER MIXING ....................................................................6-39
6.9.4 DEVELOPMENT BIAS ...................................................................6-40
6.9.5 TONER SUPPLY ............................................................................6-41
Toner Bottle Replenishment Mechanism ............................................6-41
Toner Supply Mechanism ...................................................................6-42
6.9.6 TONER DENSITY CONTROL ........................................................6-43
Overview.............................................................................................6-43
Toner Density Sensor Initial Setting....................................................6-45
Toner Concentration Measurement ....................................................6-45
Vsp/Vsg Detection ..............................................................................6-45
Toner Supply Reference Voltage (Vref) Determination.......................6-45
Toner Supply Determination ...............................................................6-45
Toner Supply Motor On Time Determinations.....................................6-46
6.9.7 TONER SUPPLY IN ABNORMAL SENSOR CONDITIONS...........6-47
ID Sensor............................................................................................6-47
TD Sensor...........................................................................................6-47
6.9.8 TONER NEAR END/END DETECTION AND RECOVERY............6-48
Toner Near End Detection ..................................................................6-48
Toner Near End Recovery ..................................................................6-48
Toner End Detection ...........................................................................6-48
Toner End Recovery ...........................................................................6-48
6.10 DRUM CLEANING AND TONER RECYCLING.....................................6-49
6.10.1 DRUM CLEANING........................................................................6-49
6.10.2 TONER RECYCLING ...................................................................6-49
6.11 PAPER FEED........................................................................................6-50
6.11.1 OVERVIEW ..................................................................................6-50
6.11.2 PAPER FEED DRIVE MECHANISM ............................................6-51
6.11.3 PAPER FEED AND SEPARATION MECHANISM........................6-51
6.11.4 PAPER LIFT MECHANISM ..........................................................6-52
6.11.5 PAPER END DETECTION ...........................................................6-52
6.11.6 PAPER SIZE DETECTION...........................................................6-53
Paper Tray ..........................................................................................6-53
By-pass Tray.......................................................................................6-54
6.11.7 SIDE FENCES..............................................................................6-55
6.11.8 PAPER REGISTRATION..............................................................6-55
6.12 IMAGE TRANSFER AND PAPER SEPARATION .................................6-56
6.12.1 OVERVIEW ..................................................................................6-56
6.12.2 IMAGE TRANSFER CURRENT TIMING......................................6-57
6.12.3 TRANSFER ROLLER CLEANING................................................6-58
6.12.4 PAPER SEPARATION MECHANISM...........................................6-58
6.13 IMAGE FUSING AND PAPER EXIT......................................................6-59
6.13.1 OVERVIEW ..................................................................................6-59
6.13.2 FUSING UNIT DRIVE AND RELEASE MECHANISM ..................6-60
Fusing Unit Drive ................................................................................6-60
Drive Release Mechanism ..................................................................6-60
Contact/Release Control.....................................................................6-60
Drive Release Solenoid ......................................................................6-61
B121 Series/B259 Series viii SM