1. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
Ink Delivery System (IDS) issues
overview
Gengrinovich Semion
IDS group

2. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
Content
2
• What it is IDS?
• Pressure
• Temperature
• Maintenance
• Numerical Simulation

3. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
IDS – what is this?
3
IDS – system that responsible supply ink whenever PH’s need
ink ink inkink
Load Cell
Ink
Atmosphere
10L Supply
Tank
Ink ID
Air
Purge
valve
Pressure
0.9bar
T2 (Optional)
Pump
Radiator
Filter
1mic
3WayValve
ffl
ffl
ffl
ffl
Recycling Bath
ffl
ffl
ST1 ST2
Filter
1mic
Feeding main
Tank /
Recycling
pump
3WayValve
Ink
Ink Rec Ink
Ink
Ink
Ink
Ink Rec
Air valve 2
Air valve 1
Ink Circ
Air for ST’s valves
Air relief for Valves
Pressure/Atmosphere
Atm
Heater
Water IN
T1
ffl
Critical
ffl
Feelingffl
Overflow
Pressure Transducer
3WayValve
Feeding
Secondary
tanks Pump
Ink
Ink
Overflow
Feeding
Low
Critical INK line
INK Recycling
INK Circulated
Water line
Air Valve relief
Atmosphere/Purge
Manual Valve
Waste
Tank
Ink ID
Manual Valve
Separator
Waste pump
Vacuum knife
Waste line
Simplified IDS
Actually IDS

4. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
IDS – what is this?
4
Pressure issues in PH’s
Machine serge
-140
-120
-100
-80
-60
-40
-20
0
20
40
1550 1600 1650 1700 1750 1800
Time (50samples per sec)
Pressure(mmH2O)
Machine serge
ttezz nn
tn 22
20 1cos1sin
1
-120
-100
-80
-60
-40
-20
0
20
-3 -2 -1 0 1 2 3 4
Time(sec)
Pressure(bar)
theoretical calculation Machine phenomena
propertiesLiquidpropertieslGeometrica
gl
D
2
162
1
propertiesLiquidpropertieslGeometrica
gl
D
2
162
-120
-100
-80
-60
-40
-20
0
20
-3 -2 -1 0 1 2 3 4
Time(sec)
Pressure(mmH2O)
Theoretical calculation Surge with flexible tubes
1

5. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
Pressure issues in PH’s
5
HP Confidential
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
0 5 10 15 20 25 30 35 40
Pressure(mmH2O)
Time (sec)
Valves 400 in nominal condition (pressure in Inlet of PH 16)
Valve 400 – opens dH=40mm
H=50m
m
-150
-100
-50
0
107 112 117 122 127 132 137
Valves 400 - closed during the printing)
After 4 copies in print mode 480 BB
100% 3.2 meter - Failure appear
H=80m
m
-110
-60
-10
110 115 120 125 130 135 140 145
Siphon installed - valves 400 in nominal conditions
H=30m
m
Valve 400 – opens
• After 20 copies in print mode
480 BB 100% 3.2 meter –
Stable (Failure not appear) but
not repeatable in all colors
• After 20 copies in print mode
480 BB 100% 3.2 meter –
Stable for all colors

6. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
Pressure issues in PH’s
Solved the “starvation” – tested on one machine – 6 colors
6
• After 4 copies in print mode 480 BB 100% 3.2
meter - Failure appear in all colors
• After 20 copies in print mode 480 BB 100% 3.2
meter – Stable for all colors

7. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.7
18
Particles with a size of 20 m or larger should be prevented from reaching the
nozzle. Inside the printhead, this can be achieved through filters. But dust
particles from outside also form a threat. Printing in a clean environment should
prevent particles from reaching the nozzle. Unfortunately, for printers in an
industrial environment it is often impossible to control the cleanness of the
ambient air.
Air entrapment triggered by particles in the ink, disrupting the
droplet formation
J. Acoust. Soc. Am., Vol. 120, No. 3, September 2006 de Jong et al.: Air
entrapment in piezo-driven inkjet printheads

8. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.8
Air entrapment caused by an ink layer on top of the nozzle
plate
The ink layer on the nozzle plate should stay below a thickness of 30 m. This
may be accomplished by a special design of the nozzle plates.
J. Acoust. Soc. Am., Vol. 120, No. 3, September 2006 de Jong et al.: Air
entrapment in piezo-driven inkjet printheads

9. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
White ink sedimentation
After Week End of 60Hr (2.5 days) and post weekend maintenance of purge 2sec *
3times @ 2bar in machine #40, was discovered a lot of missing nozzles in the
middle of the beam. After additional full cycle maintenance, problem disappear.

10. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
White phenomena solution – through RCD
1
0
Missing Nozzles in the middle of the
beam requires twice the “Purge”
process to “wake up”
During circulation More fresh ink is
available at the mid ink bushing for
sediments
Sedimentation rate of pigment at
the middle of the beam is higher
Stagnation point of bushing
creates more sediments in the
mid beam area
High ink waste – 66% at xx
usage
Sedimentation rate of pigment at
the middle of the beam during
circulation is higher
And/
Or
And/
Or
Change in flow direction separates
the pigments from the carrier
during the flow
First DOE iteration
point us to that
Root Cause
Well, Why the middle is
dramatically different from
others? Lets work on
circulation sequence.
Ok, This one can be easy
to check, by removing
the insert from the middle
This one not easy to implement
for proving, and can affect on
whole white system

11. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
Decap/Open time No First drops jetting
due to changing of ink
properties
Ink polymer separation in
nozzles
Under investigation
Proven false hypothesis. This is not a cause of
the problem
Proven true hypothesis
NOT Under investigation
Last Update: 22/03/2012
Updated by: Semion Gengrinovich
Locally in nozzles Ink
properties changed to
viscoelasty
Cross talk pressure
wave during the
printing
Temperature gradient
between nozzles and
plenum
Cheek depth
geometry differences
Temperature gradient
between PH’s in the
beam
Ink Volume above
the PH’s
Short decap / open time
Spontaneous curing of
ink at nozzle level
Sedimentation of
ink at nozzle level
Ambient
temperature
Higher ink
Evaporation at
nozzles level
Stray lights
And/Or
Nozzle plate
protruding
No circulation/mixing/
vibrations during the
idle time
Degassing level of ink
Ambient Air flow
above nozzle plate
And/Or
Initial Conditions After 10min with
air flow
After 20min with
air flow
After 40min with
air flow
RCD:
60 min idle, “micro purge” 0.01bar, 10
sec, no dripping observed

12. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
Thermal issues

13. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
Solution to dissipate the heat
Temperature during the printing @30kHz with Heat
Sink
37
39
41
43
45
47
49
51
53
55
1400 1450 1500 1550 1600 1650 1700 1750
Time (sec)
Temperature(C)
Ink temperature inside the PH chamber Electronic part of PH
Condition with water cooler. The effect of
water cooler is clearly observed (The
temperature almost identical on the all area
of PH – around 41.5C).
Temperature at PHs ink chamber– 37C
•Max hot spot temp(Initial to max)=44-40.5
= 3.5 [°C]
•Reservoir printing max Ink temp (Initial to
max) = 38.5-40.5 = 2 [°C]

14. © Copyright 2012 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
Thank you