MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
NSF CRCD Project Lecture
April 14, 2003
Fa-Gung Fan
Wilson Center for Research & Technology
Xerox Corporation
Webster, NYhttp://chester.xerox.com/innovation/wcrt.html
Particle Transport, Deposition, and Removal in Xerography
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Outline of the Lecture
� General Overview of Xerography
� Transport, Adhesion/Cohesion and Removal of Fine Particles (Toner) in XerographyMeasuring Toner Charge --- Cage Blowoff, Charge SpectrographElectrostatic Adhesion, Detachment of Toner ParticlesMeasuring Toner Adhesion --- Atomic Force Microscopy (AFM), Centrifuge Detachment, Electric Field DetachmentMeasuring Cohesion --- Fluidized Bed
�� Modeling of Electrostatics in SubsystemsModeling of Electrostatics in Subsystems(in MAE Seminar 4:00(in MAE Seminar 4:00--5:00pm today)5:00pm today)
�� Q&AQ&A
Acknowledgements:
S. Chang, C. Duke, D. Hays
N. Goodman, H. Mizes
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Xerographic Process
ChargingCleaning
Exposure
Paper
Fusing
Transfer
PhotoreceptorSubstrate
S NS N
SN
SNN
Development
4
5
6
2
1
3
C. Duke, J. Noolandi, T. Thieret, “The surface
science of xerography,” Surface Science, 500, p.
1005, (2002)
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Xerox Phaser 7700 Color Desktop Laser Printer
22 prints/min, full-color
Xerography is a versatile technology that scales from desktop, to
office, to production machines; black-and-white, hightlight color,
and full color.
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
DocuColor 40 Pro Color Office Multifunction Machine
40 prints/min, full-color
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
DocuTech 6180 Production Publisher
180 prints/min
Black-and-White
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
DocuColor iGen3 Digital Production Color Press
100 prints/min, full-color
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
iGen3
Xerographic Unit
Finisher/Binder
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
�A semiconductor whose
conductivity is a strong
function of light exposure.
Exposure (ergs/cm2)
Volt
age
on S
urf
ace
(V)
Electron/hole pairs
_ _ _ _
+ + + + ++ +
_ _ _
+_
+_
_ _ _ __ _ _ _
+ + + + ++ ++ + + + ++ + + + ++ +
_ _ __ _ _
+_
+_
+_
+_
_ _ _ _
+ + ++ ++ +
_ _ _ __ _ _ _
+ + ++ ++ +
0
-1000
0 5
• Requirements
– Insulator in the dark.
– Conductor when exposed to light
– Builds up enough voltage.
– Uniform properties
Photoreceptor
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Charging Subsystem
Electrons
Positive Ions
Electrons
Positive Ions
Free ions are attracted
to wire; Free electrons are
repelled. Counter-charges
build up on grounded surfaces.
Rapidly moving electrons
and ions collide with air
molecules, ionizing them
and creating a corona.
Electrons continue to
follow Electric Field lines
to Photoreceptor until
uniform charge builds up
HV Power
Supply (-)
HV Power
Supply (-)
HV Power
Supply (-)
HV Power
Supply (-)
HV Power
Supply (-)
HV Power
Supply (-)
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Imaging/Exposure
Traditional Analog Copier Laser Printer
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Development
� Charge particles
triboelectrically
� Electric field moves
particles from developer
roll to photoreceptor
Apply E
Field
Development roll
Photoreceptor Photoreceptor
Development roll
Toner
Photo
rece
pto
r Development
Roll
Mixing
Charging
Toner
Photo
rece
pto
r Development
Roll
Mixing
Charging
Triboelectrification of
toner particles and carrier
beads
E
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
5-10 microns5-10 microns
• Charging
• Adhesion/cohesion
• Powder flow
• Rheology
• Color - hue and density
• Pigment dispersion
Toner
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
q ≅≅≅≅ 2 x 104 em ≅≅≅≅ 2 x 10-10 gm
q/m ≅≅≅≅ 16 µµµµC/gm
20 µm
Toned Carrier Bead
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Transfer
Apply E
Field &
Separate
Paper
Photoreceptor
Paper
Photoreceptor
Paper
Photoreceptor
Paper
Photoreceptor
� Electric field moves particles from
photoreceptor to paper or transparency
� Detachment field must overcome toner
adhesion to photoreceptor
Photoreceptor
Paper
E
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Fusing Subsystem
� Permanently affix the image to the final substrate
� paper of various roughnesses and surface treatment
� transparency (plastic)
�Apply heat and/or pressure
Hot Roll Fuser: Pressure Roll
Heat Roll
Paper
Pressure Roll
Heat Roll
Paper
Elastomer
Unfused toner Fused toner
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Cleaning and Erase
� Removes unwanted residual toner and charge
from photoreceptor before next imaging cycle
�Physical agitation removes toner (blade or brush)
�Light neutralizes charge by making entire photoreceptor
conductive
__
__
_
__
_
Photoreceptor
Residual toner
Charge
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Transport, Adhesion/Cohesion and Removal of Fine Particles (Toner) in Xerography
paper
Toner must transfer from
roll to paper
Toner must flow smoothly
down dispenser
Toner must develop
onto roll uniformly
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Toner Charge Measurements
Blowoff Tribo
� Blow toner from toned beads in cage
� Measure charge & mass difference
� Calculate average Q/M
0
10
20
30
40
50
0 1 2 3 4
Toner Concentration (%)
Q/M
(µµ µµ
C/g
m)
Air
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Toner Charge Measurements
Charge Spectrograph
-0.5
0
0.5
1
1.5
0 5 10 15 20 25 30 35
Air Flow
E Field
Diameter (µµµµm)
q/D
(fC
/ µµ µµm
)
� Inject toner
� Displacement ∝∝∝∝ q/D
� Measure position & size of particles
Lycopodium50%
80%
90%95%
99%
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Particle adhesion depends on:
� Size, shape, & roughness
� Materials
� Flow agents
� Charge
� Surface charge distribution on particle
Toner Adhesion Forces
++
++
++++ +
+++++
+
++
++
++++ +
+++++
+
++
++
++++ +
+++++
+
Fad
Fa
Detachment when Fa > Fad
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
σσσσππππ
====Q
R42
R
FiQ
oR==== −−−− αααα
ππππεεεε
2
162
Fi
Fa QE o R E==== −−−−ββββ γγγγ ππππ εεεε 2 2
EEFa
EdQ
o R≅≅≅≅ ≈≈≈≈
αααα
ββββ ππππ εεεεµµµµ
16 21 V / m
Image Force Applied Force
Electrostatic Image Force Model
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Q At==== σσσσ
fAc
At====
AcFa
Charge Patch Adhesion Model
cc
o
ad AWAF −−−−−−−−====εεεε
σσσσ
2
2
Fad
++++−−−−====
σσσσεεεε
σσσσ WQf
o2
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Additives Control Adhesion
Changing type of additive modifies adhesionChanging type of additive modifies adhesion
Atomic Force Microscopy results
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Atomic Force Microscopy (AFM)
Bring toner
near surface
Push toner
against surface
Retract toner until
probe releases
200 µm
20 µm
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Measure Single Particle Adhesion
Laser
Cantilever
Photodetector
Particle
Piezoelectric:
moves up
and down
AFM
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Centrifuge Detachment
Measure Many Particle Adhesion
Putt, putt, putt,... Vroom, vroom,... Whoosh,...
Observe Donor Plate after Each Spin
H. Mizes, “Adhesion of Small Particle”, Electro. Soc. Amer.
Univ. of Rochester, 6/23/95
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Electric Field Detachment
VVDonor ReceiverV
transparent
conductive
electrodes
Measure Many Particle Adhesion
E. Eklund, W. Wayman, L. Brillson, D. Hays, 1994 IS&T Proc.,
10th Int. Cong. on Non-Impact Printing, 142-146
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Electrical Field Detachment of Charged Toner
Detachment Cell
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10 12 14 16 18
Detachment Field (V/µµµµm)
Tra
ns
ferr
ed
Fra
cti
on
Adhesion of Triboelectrically Charged Toner
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
-
-
-
-
FE
FAD
Toner Transferred
When FE >>>> FAD
Donor Surface-
-
-
-
FE
FAD
Toner Transferred
When FE >>>> FAD
Donor Surface
E. Eklund, W. Wayman, L. Brillson, D. Hays, 1994 IS&T Proc.,
10th Int. Cong. on Non-Impact Printing, 142-146
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Fluidized Bed
Measure Powder Cohesion
P.K. Watson, “Yield Locus of Cohesive Granular Materials”, Workshop on
Dynamics of Granular Materials: Understanding & Control, Univ. of Chicago,
5/11/95
αααα
∆ ∆ ∆ ∆ P
h
ααααττττ σσσσ
σσσσ
Stresses on the toner bed
σ = ρ (1σ = ρ (1σ = ρ (1σ = ρ (1−−−−ε)ε)ε)ε) gh cos α α α α −−−− ∆ ∆ ∆ ∆ P
τ = ρ (1τ = ρ (1τ = ρ (1τ = ρ (1−−−−ε)ε)ε)ε) gh sin αααα
Tension \ Compression
Shear
αααα
∆ ∆ ∆ ∆ P
h
ααααττττ σσσσ
σσσσ
Stresses on the toner bed
σ = ρ (1σ = ρ (1σ = ρ (1σ = ρ (1−−−−ε)ε)ε)ε) gh cos α α α α −−−− ∆ ∆ ∆ ∆ P
τ = ρ (1τ = ρ (1τ = ρ (1τ = ρ (1−−−−ε)ε)ε)ε) gh sin αααα
Tension \ Compression
Shear
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
0
10
20
30
40
50
60
70
ττ ττ,, ,,
Sh
ea
rS
tre
ss
(N/m
2)
Tension
Compression
-30 -20 -10 0 10 20 30 40 50 60 70
σσσσ ,,,, Compress ive Stress (N/m2)
Less Additives
More Additives
0
10
20
30
40
50
60
70
ττ ττ,, ,,
Sh
ea
rS
tre
ss
(N/m
2)
Tension
Compression
-30 -20 -10 0 10 20 30 40 50 60 70
σσσσ ,,,, Compress ive Stress (N/m2)
Less Additives
More Additives
MAE Dept., Clarkson University, 4/14/2003Fa-Gung Fan, Xerox Corporation
Q&AQ&A
Top Related