5
Theory of operation
This chapter describes how to use the engine control system, laser/scanner system, image
information system, and pickup/feed system for the HP Color LaserJet 5500 series printer.
Basic operation .....................................................................................................................129
Operation sequence .......................................................................................................129
Engine control system ...........................................................................................................131
DC controller circuit ........................................................................................................131
Motors and fans ..............................................................................................................133
Fuser power supply circuit ..............................................................................................135
Heater temperature control .............................................................................................136
Heater temperature control (HP Color LaserJet 5550 models) ......................................137
Failure detection (HP Color LaserJet 5550 models) ......................................................138
High-voltage power supply .............................................................................................138
Low-voltage power supply ..............................................................................................139
Formatter system ............................................................................................................140
PowerSave .....................................................................................................................140
Input/Output ....................................................................................................................141
Printer memory ...............................................................................................................142
Read-only memory .........................................................................................................142
Random-access memory ................................................................................................142
Firmware DIMM (HP Color LaserJet 5500 models) .......................................................142
Firmware compact flash (HP Color LaserJet 5550 models) ..........................................142
Nonvolatile memory ........................................................................................................142
PJL overview ..................................................................................................................143
PML .................................................................................................................................143
Control panel ..................................................................................................................143
Laser/scanner system ...........................................................................................................144
Scanner motor control ....................................................................................................145
Image formation system ........................................................................................................146
Image formation process ................................................................................................147
Print cartridges ................................................................................................................149
Toner level detection ......................................................................................................150
Electrostatic transfer/transport belt (ETB) unit ...............................................................154
Electrostatic latent image formation block ......................................................................155
Development block .........................................................................................................157
Transfer block .................................................................................................................158
Fusing block ....................................................................................................................159
Fuser motor speed control ..............................................................................................160
Cleaning block ................................................................................................................160
Calibration and cleaning .................................................................................................161
Color plane registration calibration .................................................................................165
Drum phase calibration ...................................................................................................166
Image stabilization control ..............................................................................................166
Pickup/feed system ...............................................................................................................169
Pickup/feed unit ..............................................................................................................172
Fuser/delivery unit ..........................................................................................................179
Duplex feed unit ..............................................................................................................180
ENWW 127
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