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  • 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

  • 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

  • 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 PHs need

    ink ink inkink

    Load Cell

    Ink

    Atmosphere

    10L Supply Tank

    Ink ID

    Air Purge valve

    Pressure 0.9bar

    T2 (Optional)

    Pum

    p

    Radiator

    Filter 1m

    ic

    3Way Valve

    ffl

    ffl fflffl

    Recycling Bath

    fflffl

    ST1 ST2

    Filte

    r 1m

    ic

    Feeding main Tank /

    Recycling pump

    3Way Valve

    Ink Ink Rec Ink

    Ink

    Ink

    Ink

    Ink Rec

    Air valve 2Air valve 1

    Ink Circ

    Air for STs valves

    Air relief for Valves

    Pressure/Atmosphere

    Atm

    Heater

    Water IN

    T1

    fflCritical

    fflFeelingffl

    OverflowPressure Transducer

    3Way

    Val

    ve

    Feeding Secondary tanks Pump

    Ink Ink

    OverflowFeeding

    LowCritical INK line

    INK RecyclingINK CirculatedWater lineAir Valve reliefAtmosphere/Purge

    Manual Valve

    Waste Tank

    Ink ID

    Manual Valve

    Separator

    Waste pump

    Vacuum knife

    Waste lineSimplified IDS

    Actually IDS

  • 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 PHsMachine serge

    -140

    -120

    -100

    -80

    -60

    -40

    -20

    0

    20

    40

    1550 1600 1650 1700 1750 1800

    Time (50samples per sec)

    Pres

    sure

    (mm

    H2O

    )

    Machine serge

    ttezz nntn 22

    201cos1sin

    1

    -120

    -100

    -80

    -60

    -40

    -20

    0

    20

    -3 -2 -1 0 1 2 3 4

    Time(sec)

    Pres

    sure

    (bar

    )

    theoretical calculation Machine phenomena

    propertiesLiquidpropertieslGeometrica

    glD

    2162

    1

    propertiesLiquidpropertieslGeometrica

    glD

    2162

    -120

    -100

    -80

    -60

    -40

    -20

    0

    20

    -3 -2 -1 0 1 2 3 4

    Time(sec)

    Pres

    sure

    (mm

    H2O

    )

    Theoretical calculation Surge with flexible tubes

    1

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

    Pressure issues in PHs

    5

    HP Confidential

    -100-90-80-70-60-50-40-30-20-10

    0

    0 5 10 15 20 25 30 35 40

    Pres

    sure

    (mmH

    2O)

    Time (sec)

    Valves 400 in nominal condition (pressure in Inlet of PH 16)

    Valve 400 opens dH=40mm

    H=50mm

    -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=80mm

    -110

    -60

    -10

    110 115 120 125 130 135 140 145

    Siphon installed - valves 400 in nominal conditions

    H=30mm

    Valve 400 opens

    After 20 copies in print mode 480 BB 100% 3.2 meter Stable (Failure not appear) butnot repeatable in all colors

    After 20 copies in print mode 480 BB 100% 3.2 meter Stable for all colors

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

    Pressure issues in PHsSolved 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

  • Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.7 18

    October

    Particles with a size of 20 m or larger should be prevented from reaching thenozzle. Inside the printhead, this can be achieved through filters. But dustparticles from outside also form a threat. Printing in a clean environment shouldprevent particles from reaching the nozzle. Unfortunately, for printers in anindustrial environment it is often impossible to control the cleanness of theambient 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

  • 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

  • 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.

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

    White phenomena solution through RCD

    10

    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

  • 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: 22/03/2012Updated 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 PHs in the

    beam

    Ink Volume above the PHs

    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

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

    Thermal issues

  • 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

    37394143454749515355

    1400 1450 1500 1550 1600 1650 1700 1750Time (sec)

    Tem

    pera

    ture

    (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]

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

    Thank you