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HP LaserJet 3200 Service Manual - Page 77

Step 1, Conditioning, Writing, Developing., Transfer.

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Breakdown of the seven image formation processes Step 1 Conditioning (primary charging). This process consists of applying a uniform negative charge to the surface of the drum with the primary charging roller located in the toner cartridge. The primary charging roller is coated with conductive rubber. An AC bias is applied to the roller to erase any residual charges from any previous image. In addition, a negative DC bias is applied by the charging roller to create a uniform negative potential on the drum surface. The amount of DC voltage is modified by the print density setting. Step 2 Writing (scanning exposure). During this process, a modulated laser diode projects the beam onto a rotating scanning mirror. As the mirror rotates, the beam reflects off the mirror, first through a set of focusing lenses, then off a mirror, and finally through a slot in the top of the toner cartridge, and onto the photosensitive drum. The beam sweeps the drum from left to right, discharging the negative potential wherever the beam strikes the surface. This creates a latent electrostatic image, which later is developed into a visible image. Because the beam is sweeping the entire length of the drum and the drum is rotating, the entire surface area of the drum can be covered. At the end of each sweep, the beam strikes the beam detect lens, generating the beam detect signal (BD signal). The BD signal is sent to the ECU where it is converted to an electrical signal used to synchronize the output of the next scan line of data. Step 3 Developing. At this stage of the process, the latent electrostatic image is present on the drum. The toner particles obtain a negative surface charge by rubbing against the developing cylinder which is connected to a negative DC supply. The negatively charged toner is attracted to the discharged (exposed, grounded) areas of the drum, and repelled from the negatively charged (unexposed) areas. Step 4 Transfer. During the transferring process, the toner image on the drum surface is transferred to the paper. A positive charge applied to the back of the paper by the transfer roller causes the negatively charged toner on the drum surface to be attracted to the paper. After separation, the drum is cleaned and conditioned for the next image. EN Printer functions 75

Section	Page
Contents	5
Figures	9
Tables	13
Product information	15
Chapter contents	15
Introduction	16
Hardware description	16
Firmware description	17
Product specifications	18
Model and serial numbers	21
Product overview	22
Warranty statement	25
Hewlett-Packard limited warranty statement	25
Declaration of Conformity	27
Toner cartridge information	28
Additional product stewardship	29
Environmental conformity	29
Installation and operation	31
Chapter contents	31
Operating environment	32
Identifying product components	33
Control panel lights and keys	33
Using the control panel menu structure	35
Control panel error messages	37
Selecting media	45
Selecting media to print	45
Selecting media to fax, copy, or scan	46
Loading media	47
Loading media to fax, copy, or scan	47
Loading media to be printed	50
Selecting the output path	52
Maintenance	53
Chapter contents	53
Life expectancies of consumables	54
Cleaning and maintaining the equipment	55
Cleaning the product	56
Cleaning the scanner path	59
Recalibrating the scanner	61
User-replaceable parts	62
Operational overview	63
Chapter contents	63
Basic functions	64
Optical system	65
Formatter system	67
Control panel	68
Draft mode	68
MEt	68
Enhanced I/O	68
Page Protect	69
PJL Overview	69
Printer functions	70
Engine control unit/power system	71
Image formation system	76
Printer paper feed system	79
Basic sequence of operation (formatter-to-printer)	84
Removal and replacement	87
Chapter contents	87
Removal and replacement strategy	89
Required tools	89
Parts removal order	90
Covers	91
DIMMs	91
Back cover	92
Right side cover	93
Left side cover	95
Internal paper guide	96
Top cover	97
Document scanner assemblies	98
Printer door	98
Document scanner assembly	102
Contact image sensor	105
Document scanner pickup roller	107
Document scanner separation pad	108
Document scanner motor	109
Upper guide assembly	110
Control panel/scanner board	114
Internal assemblies	115
Laser/scanner assembly	115
Output roller	116
Delivery assembly	118
Paper exit-sensor flag	120
Fusing element	121
Gear train motor	126
Solenoid	129
Pressure roller	130
Transfer roller	132
Pickup roller	133
Paper-pickup assembly	134
Kick plate	136
Separation pad	137
Bottom assemblies	139
Formatter pan	139
Formatter and LIU	140
ECU pan	141
Paper-feed assembly	143
Troubleshooting	147
Chapter contents	147
Basic troubleshooting	148
Errors	151
Image formation troubleshooting	157
Checking the toner cartridge	157
Solving image-quality problems	158
Solving paper feed problems	164
Functional checks	167
Engine test	167
Half-self-test functional check	168
Drum rotation functional check	169
Heating element check	170
High-voltage power supply check	171
Paper path check	173
Service mode functions	174
Secondary service menu	174
Developer’s menu	175
Diagnostic mode	183
NVRAM init	185
PJL software commands	185
Troubleshooting tools	188
Internal reports	188
Printing all fax reports at once	189
T.30 protocol trace	190
Repetitive image defect ruler	209
Document scanner recalibration	210
Main wiring	212
Locations of connectors	214
Parts and diagrams	217
Chapter contents	217
Ordering parts and supplies	218
Parts	218
Parts exchange program	219
Related documentation and software	219
Consumables	219
Accessories	220
How to use the parts lists and diagrams	221
Common hardware	222
Assembly locations	223
Covers	224
Trays and bins	225
External covers and panels	227
Document scanner assemblies	228
Document scanner assemblies	229
Document feeder	231
Upper guide assembly	233
Internal assemblies	234
Internal components (1 of 4)	235
Internal components (2 of 4)	237
Internal components (3 of 4)	239
Internal components (4 of 4)	241
Feed assembly	243
Electrical components	245
Alphabetical parts list	246
Numerical parts list	251
Index	257
A	257
B	257
C	257
D	258
E	258
F	259
G	259
H	260
I	260
J	260
K	260
L	260
M	261
N	261
O	261
P	261
Q	263
R	263
S	263
T	264
U	265
V	265

Match case Limit results 1 per page

Printer functions

Breakdown of the seven image formation processes

Step 1

Conditioning

(primary charging). This process consists of

applying a uniform negative charge to the surface of the drum

with the primary charging roller located in the toner cartridge.

The primary charging roller is coated with conductive rubber.

An AC bias is applied to the roller to erase any residual

charges from any previous image. In addition, a negative DC

bias is applied by the charging roller to create a uniform

negative potential on the drum surface. The amount of DC

voltage is modified by the print density setting.

Step 2

Writing

(scanning exposure). During this process, a

modulated laser diode projects the beam onto a rotating

scanning mirror. As the mirror rotates, the beam reflects off

the mirror, first through a set of focusing lenses, then off a

mirror, and finally through a slot in the top of the toner

cartridge, and onto the photosensitive drum. The beam

sweeps the drum from left to right, discharging the negative

potential wherever the beam strikes the surface. This creates

a latent electrostatic image, which later is developed into a

visible image.

Because the beam is sweeping the entire length of the drum

and the drum is rotating, the entire surface area of the drum

can be covered. At the end of each sweep, the beam strikes

the beam detect lens, generating the beam detect signal (BD

signal). The BD signal is sent to the ECU where it is

converted to an electrical signal used to synchronize the

output of the next scan line of data.

Step 3

Developing.

At this stage of the process, the latent

electrostatic image is present on the drum. The toner

particles obtain a negative surface charge by rubbing against

the developing cylinder which is connected to a negative DC

supply. The negatively charged toner is attracted to the

discharged (exposed, grounded) areas of the drum, and

repelled from the negatively charged (unexposed) areas.

Step 4

Transfer.

During the transferring process, the toner image on

the drum surface is transferred to the paper. A positive

charge applied to the back of the paper by the transfer roller

causes the negatively charged toner on the drum surface to

be attracted to the paper. After separation, the drum is

cleaned and conditioned for the next image.