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HP Color LaserJet Professional CP5220 Service Manual - Page 54

Image density control (DMAX), Image halftone control (DHALF)

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Image density control (DMAX) The image density control calibrates each high-voltage bias to stabilize the image density variation caused by the deterioration of the photosensitive drum or toner. The DC controller commands the formatter to control the image density under the following conditions: ● The detected temperature of the fuser is a specified degree or lower when the product is turned on ● The product is turned on or the door is closed and also whenever a specified number is printed after replacing any one of the cartridges ● The product is turned on or the door is closed after replacing the ITB unit or the laser scanner unit ● A specified number of pages have been printed ● After a specified period of time from the previous image density control ● The environment is changed for a specified condition after the previous image density control Image halftone control (DHALF) The image halftone control is performed by the formatter to calibrate the halftone. The DC controller measures the halftone pattern according to a command from the formatter. Accordingly, the formatter calibrates the halftone. The DC controller controls the image halftone under the following conditions: ● The image density control is completed ● The formatter sends a command 42 Chapter 1 Theory of operation ENWW

Section	Page
Theory of operation	13
Basic operation	14
Major product systems	14
Product block diagram	14
Sequence of operation	15
Normal sequence of operation	15
Formatter-control system	17
Sleep mode	17
Input/output	17
CPU	18
Memory	18
Firmware	18
Nonvolatile memory	18
PJL overview	18
PML	18
Control panel	18
Engine-control system	19
DC controller	20
Motors	23
Fans	25
Fuser-control circuit	26
Fuser temperature control	27
Fuser protective function	28
Fuser failure detection	29
Low-voltage power supply	30
Overcurrent/overvoltage protection	32
High-voltage power supply	33
Laser scanner system	35
Laser failure detection	36
Image-formation system	37
Electrophotographic process	37
Image formation process	39
Latent-image formation block	40
Pre-exposure	40
Primary charging	40
Laser beam exposure	41
Developing block	42
Transfer block	43
Primary transfer	43
Secondary transfer	43
Separation	44
Fusing block	44
ITB cleaning block	45
Drum cleaning block	45
Print cartridges	46
Memory tag	47
Cartridge presence detection	47
Toner level detection	47
Cartridge life detection	47
Developing unit engagement and disengagement control	47
ITB unit	49
Primary transfer roller engagement and disengagement control	50
ITB unit presence detection	51
ITB cleaning mechanism	51
Calibration	52
Color-misregistration control	52
Environment change control	53
Image stabilization control	53
Image density control (DMAX)	54
Image halftone control (DHALF)	54
Pickup, feed, and delivery system	55
Photo sensors	56
Motors and solenoids	57
Pickup and feed block	57
Cassette pickup	57
Cassette multiple-feed prevention	58
Tray 1 (MP tray) paper pickup	59
Tray 1 (MP tray) last-paper detection	60
Paper feed	61
Skew-feed prevention	63
Feed-speed control	64
Fusing and delivery block	64
Loop control	64
Pressure roller pressurization and depressurization control	66
Output bin full detection	67
Duplex block (duplex models only)	68
Jam detection	69
Paper feeder	71
Paper-feeder motors	72
Paper-feeder paper pickup and feed	73
Paper-feeder cassette lift operation	73
Paper-feeder jam detection	74
Removal and replacement	75
Introduction	76
Removal and replacement strategy	77
Electrostatic discharge	78
Required tools	79
Service approach	80
Before performing service	80
After performing service	80
Post-service test	80
Print-quality test	80
Removal and replacement procedures	81
Customer self repair (CSR) components	81
Print cartridges	81
Toner-collection unit	84
Memory DIMM	86
Product memory	86
Install memory and font DIMMs	86
Enable memory	90
Enable memory for Windows	90
Check DIMM installation	90
Fuser	91
Pickup roller (Tray 1)	92
Separation pad (Tray 1)	93
Separation roller assembly (Tray 2)	94
Pickup roller (Tray 2)	96
Pickup roller, separation roller, and feed roller (Tray 3)	97
Secondary transfer roller	98
Intermediate transfer belt (ITB)	99
External panels, covers, and doors	101
Identification and location	101
Right-front cover and control-panel assembly	102
Left cover	104
Rear cover	105
Remove the rear cover	105
Toner collection unit access door	105
Right-rear cover	107
Top cover	108
Remove the top cover	108
Front-door assembly	110
Right-door assembly	114
Internal assemblies	116
Laser scanner assembly	117
Remove the laser scanner assembly	117
Cassette pickup drive assembly	120
Remove the cassette pickup drive assembly	120
Registration sensor assembly	124
Remove the registration sensor assembly	124
Lifter-drive assembly	127
Remove the lifter-drive assembly	127
ITB front guide assembly	129
ITB rear guide assembly	131
Residual toner full sensor	132
Remove the residual toner full sensor	133
Formatter case	135
Delivery assembly	136
Remove the delivery assembly	136
Duplex drive assembly (duplex models)	139
Remove the duplex-drive assembly	139
Delivery drive assembly (simplex models)	141
Remove the delivery drive assembly	141
Residual-toner-feed assembly	142
Remove the residual-toner-feed assembly	142
ITB motor	144
Remove the ITB motor	144
Drum motor	146
Remove the drum motor	146
Developing motor	147
Remove the developing motor	147
Fuser motor	148
Remove the fuser motor	148
Developing-disengagement motor	149
Remove the developing-disengagement motor	149
Power-supply fan	151
Remove the power-supply fan	151
Fuser fan	154
Remove the fuser fan	154
Formatter PCA	156
Formatter resets	156
DC controller PCA	158
Remove the DC controller PCA	158
Low-voltage power supply	160
Remove the low-voltage power supply	160
Imaging (developing) high-voltage power supply	164
Remove the imaging (developing) high-voltage power supply	164
First transfer high-voltage power supply	165
Remove the first transfer high-voltage power supply	165
Second transfer high-voltage power supply	167
Remove the second transfer high-voltage power supply	167
Driver PCA	169
Remove the driver PCA	169
Power switch PCA	171
Remove the power switch PCA	171
Environmental sensor	172
Remove the environmental sensor	172
Optional paper feeder assembly (Tray 3)	173
Tray 3 rear cover	173
Tray 3 left cover	173
Tray 3 right-front cover	175
Tray 3 front-upper cover	176
Tray 3 right door	176
Tray 3 right-lower cover	178
Tray 3 pickup assembly	179
Tray 3 lifter drive assembly	180
Tray 3 pickup motor	181
Tray 3 driver PCA	182
Solve problems	183
Solve problems checklist	184
Menu map	185
Troubleshooting process	186
Pretroubleshooting checklist	186
Power-on checks	188
Tools for troubleshooting	189
Diagrams	189
Block diagrams	189
Plug/jack locations	191
Location of connectors	192
DC controller connections	192
Product connections	194
Locations of major components	201
General timing charts	208
General circuit diagram	209
HP ToolboxFX	212
Open HP ToolboxFX	212
Status	213
Event log	213
Alerts	214
Set up Status Alerts	214
Set up E-mail Alerts	214
Product information	214
Set password	214
Help	215
System Settings	216
Device Information	216
Paper Setup	217
Print Quality	218
Print Density	218
Paper Types	218
Extended Print Modes	218
System Setup	218
Save/Restore Settings	218
Product Security	219
Print Settings	219
Printing	219
PCL5	219
PostScript	219
Network Settings	219
Shop for Supplies	219
Other Links	219
Internal print quality test pages	220
Use HP ToolboxFX to troubleshoot print-quality problems	220
Configuration page	221
Print quality troubleshooting tools	221
Repetitive image-defect ruler	221
Calibrate the product	222
Control-panel menus	223
Use the menus	223
Reports menu	223
System Setup menu	225
Service menu	228
Network Configuration menu	229
Interpret control-panel and status-alert messages	230
Event-log messages	241
Print an event log	241
Event-log messages	241
Clear jams	242
Common causes of jams	242
Jam locations	243
Change Jam Recovery setting	243
Clear jams in the right door	244
Clear jams in the output bin area	247
Clear jams in Tray 1	247
Clear jams in Tray 2	249
Clear jams in the optional 500-sheet paper and heavy media tray (Tray 3)	250
Clear jams in the lower right door (Tray 3)	251
Solve image-quality problems	252
Image defects table	252
Clean the product	258
Solve performance problems	259
Solve connectivity problems	260
Solve direct-connect problems	260
Solve network problems	260
Service mode functions	261
Secondary service menu	261
Open the secondary service menu	261
Secondary service menu structure	261
Product resets	262
Restore the factory-set defaults	262
Engine test page	262
Cold reset	262
NVRAM initialization	263
Super NVRAM initialization	263
Product updates	264
Parts and diagrams	265
Order parts by authorized service providers	266
Order parts, accessories, and supplies	266
Related documentation and software	266
Supplies part numbers	267
Customer self repair parts	267
Accessories part numbers	269
How to use the parts lists and diagrams	270
Assembly locations	271
External covers, panels, and doors	272
Right door assembly	274
Internal components (1 of 6)	276
Internal components (2 of 6)	278
Internal components (3 of 6)	280
Internal components (4 of 6)	282
Internal components (5 of 6)	284
Internal components (6 of 6)	286
Cassette	288
Paper pickup assembly	290
Paper delivery assembly	292
Printed circuit assemblies	294
Paper feeder external components	296
Paper feeder internal components	298
Paper feeder PCA	300
Alphabetical parts list	302
Numerical parts list	309
Service and support	317
Hewlett-Packard limited warranty statement	318
HP's Premium Protection Warranty: LaserJet print cartridge limited warranty statement	319
HP Color LaserJet Fuser Kit Limited Warranty Statement	320
End User License Agreement	321
Customer self-repair warranty service	323
Customer support	324
Product specifications	325
Physical specifications	326
Performance specifications	326
Electrical specifications	326
Acoustic specifications	326
Environmental specifications	327
Skew specifications	328
Regulatory information	329
FCC regulations	330
Declaration of conformity	331
Safety statements	332
Laser safety	332
Canadian DOC regulations	332
VCCI statement (Japan)	332
Power cord statement (Japan)	332
EMC statement (Korea)	332
Laser statement for Finland	332
Substances Table (China)	333

Match case Limit results 1 per page

Image density control (DMAX)

The image density control calibrates each high-voltage bias to stabilize the image density variation

caused by the deterioration of the photosensitive drum or toner. The DC controller commands the

formatter to control the image density under the following conditions:

●

The detected temperature of the fuser is a specified degree or lower when the product is turned

●

The product is turned on or the door is closed and also whenever a specified number is printed

after replacing any one of the cartridges

●

The product is turned on or the door is closed after replacing the ITB unit or the laser scanner unit

●

A specified number of pages have been printed

●

After a specified period of time from the previous image density control

●

The environment is changed for a specified condition after the previous image density control

Image halftone control (DHALF)

The image halftone control is performed by the formatter to calibrate the halftone. The DC controller

measures the halftone pattern according to a command from the formatter. Accordingly, the formatter

calibrates the halftone. The DC controller controls the image halftone under the following conditions:

●

The image density control is completed

●

The formatter sends a command

Chapter 1

Theory of operation

ENWW