HP P 1100 Service Manual

Image formation process
Each of the following process function independently and must be coordinated with the other product
processes. Image formation consists of the following processes:
●Latent-image formation block
◦Step 1: primary charging
◦ Step 2: laser-beam exposure
● Developing block
◦Step 3: developing
● Transfer block
◦Step 4: transfer
◦ Step 5: separation
● Fusing block
◦Step 6: fusing
● Drum cleaning block
◦Step 7: drum cleaning
Figure 1-15   Image formation process
ENWW Image-formation...

Latent-image formation stage
During the latent-image formation stage, the laser/scanner forms an invisible image on the
photosensitive drum in the print cartridge.
Primary charging Step 1: dc and ac biases are applied to the primary charging roller, which transfers a uniform negative
potential to the photosensitive drum.
Figure 1-16   Primary charging
DC bias
Photosensitive drum
Primary charging roller
Laser beam exposure
Step 2: The laser beam scans the photosensitive drum to neutralize negative charges...

Developing stage
Print cartridgeStep 3: In the print cartridge, the developing cylinder transfers toner onto the electrostatic latent image
on the photosensitive drum.
Figure 1-18   Print cartridge
Blade
Developing cylinder
AC bias
DC bias
Photosensitive drum
Unexposed area
Exposed area
Exposed area
Unexposed area
Toner acquires a negative charge from the friction that occurs when the developing roller rotates against
the developing blade. The developing bias is applied to the developing roller to make a...

Transfer stage
Step 4: The transfer charging roller, to which a DC positive bias is applied, imparts a positive charge
on the paper. When the paper comes in contact with the photosensitive drum, the toner is transferred
to the paper.
Figure 1-19   Transfer
Media
Transfer roller Photosensitive
drum
DC bias
Step 5 : The elasticity of the paper causes its separation from the photosensitive drum. A static charge
eliminator aids separation by weakening any electrostatic adhesion.
Figure 1-20   Separation...

Fusing stageStep 6: The DC negative bias applied to the fusing film strengthens the holding force of the toner on the
paper and prevents the toner from scattering.
The product uses an on-demand fuser method. The toner image is permanently affixed to the paper by
heat and pressure.
Figure 1-21   Fusing
Fuser film
Toner 
Pressure roller 
Fuser heater
Media 
Cleaning stageStep 7: The cleaning blade scrapes the residual toner off of the photosensitive drum and deposits it into
the waste toner case.
Figure...

Pickup, feed, and delivery system
The media feed system picks up, feeds, and delivers the page.
Figure 1-23  Pickup, feed, and delivery system block diagram
Fuser film
Delivery roller
Single-sheet-feed slot
(HP LJP P1100w printer Series)
Transfer roller
Photosensitive drum
Feed roller Pickup roller
Separation
pad
Pressure roller
28 Chapter 1   Theory of operation ENWW 

Photo sensors and switches
NOTE:The illustration in this section also shows the product motor and solenoid. The power switch
is not shown.
Figure 1-24   Photo sensors, motor, and solenoid
M1
PS751
PS701
PS702
SL1
Single-sheet-feed slot
(HP LJP P1100w printer Series)
Table 1-7   Photo sensors, motor, and solenoid
ItemDescription
M1Main motor
SL1Pickup solenoid
PS701Fuser delivery sensor
PS702Media-width sensor
PS751TOP sensor
ENWW Pickup, feed, and delivery system 29 

Input tray, main-input tray, or priority input slot
NOTE:The HP LaserJet Professional P1100 Printer series has a single input tray. The HP LaserJet
Professional P1100w Printer series has a main-input tray and a priority input slot.
Jam detection
The product uses the following sensors to detect the presence of paper and to check for jams. The paper
must pass each sensor within a specified time.
NOTE: To find the following components, see Photo sensors and switches on page 29.
● PS701; fuser delivery...

2 Removal and replacement
●Introduction
●
Removal and replacement strategy
●
Electrostatic discharge
●
Required tools
●
Before performing service
●
After performing service
●
Post-service test
●
Parts removal order
●
Pickup roller
●
Separation pad
●
Transfer roller
●
Covers
●
Main assemblies
ENWW 31 

Introduction
This chapter describes the removal and replacement of field-replaceable units (FRUs) only.
Replacing FRUs is generally the reverse of removal. Occasionally, notes and tips are included to provide
directions for difficult or critical replacement procedures.
HP does not support repairing individual subassemblies or troubleshooting to the component level.
Note the length, diameter, color, type, and location of each screw. Be sure to return each screw to its
original location during reassembly....