U.S. patent application number 09/854762 was filed with the patent office on 2001-11-22 for ink jet with coiled actuator.
Invention is credited to Silverbrook, Kia.
Application Number | 20010043253 09/854762 |
Document ID | / |
Family ID | 25645484 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010043253 |
Kind Code |
A1 |
Silverbrook, Kia |
November 22, 2001 |
Ink jet with coiled actuator
Abstract
An ink jet printer uses an actuator and an oscillating pressured
ink supply. A shutter is located between the ink supply and an ink
ejection port, normally blocking the ink ejection port. An actuator
is provided for moving the shutter mechanism on demand away from
the ink ejection port so as to allow for the ejection of ink on
demand from the ink ejection port. The actuator includes a thermal
actuator in a coiled form constructed primarily from
polytetrafluorethylene. The coil is uncoiled upon heating. The
actuator includes a serpentine heater element encased in a material
having a high coefficient of thermal expansion. The serpentine
heater takes a concertina form upon heating and a thick return
trace returns the actuator to its original position upon
cooling.
Inventors: |
Silverbrook, Kia; (Balmain,
AU) |
Correspondence
Address: |
SILVERBROOK RESEARCH PTY LTD
393 DARLING STREET
BALMAIN
2041
AU
|
Family ID: |
25645484 |
Appl. No.: |
09/854762 |
Filed: |
May 14, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09854762 |
May 14, 2001 |
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09112815 |
Jul 10, 1998 |
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6247792 |
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Current U.S.
Class: |
347/54 ;
348/E5.024; 348/E5.055 |
Current CPC
Class: |
B82Y 30/00 20130101;
H04N 5/225 20130101; B41J 2/1637 20130101; B41J 2/1629 20130101;
B41J 2/1646 20130101; B41J 2/14427 20130101; B41J 2/1639 20130101;
G06F 21/79 20130101; B41J 2/16585 20130101; G06K 19/06037 20130101;
B41J 2/1642 20130101; G11C 11/56 20130101; B41J 2/17513 20130101;
G06K 7/14 20130101; B41J 2/1645 20130101; G06K 7/1417 20130101;
B41J 2/1631 20130101; B41J 2/1648 20130101; B41J 2/1635 20130101;
B41J 2/1632 20130101; B41J 2/1643 20130101; H04N 1/2112 20130101;
G06K 1/121 20130101; G06F 2221/2129 20130101; B41J 2/1623 20130101;
B41J 2002/041 20130101; B41J 2/17503 20130101; H04N 2101/00
20130101; B41J 2202/21 20130101; G06F 21/86 20130101; H04N 5/2628
20130101; H04N 5/7458 20130101; B41J 2/1626 20130101; B41J 2/17596
20130101; B41J 2/1628 20130101; H04N 1/2154 20130101 |
Class at
Publication: |
347/54 |
International
Class: |
B41J 002/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 1997 |
AU |
PO8001 |
Jul 15, 1997 |
AU |
PO7991 |
Claims
I claim:
1. An ink jet nozzle arrangement comprising: a nozzle chamber
defining means which defines a chamber; an ink ejection port in
fluid communication with the chamber; and a coiled actuator
operatively arranged relative to the ink ejection port, said
actuator, upon being activated on demand, at least partially
coiling or uncoiling to cause ejection of ink from said ink
ejection port.
2. The arrangement of claim 1 in which the actuator is an
electro-thermally operable bend actuator.
3. The arrangement of claim 2 in which the actuator includes a
heater element at least partially embedded in a jacket, application
of current through said heater element causing heating of one side
of the actuator to cause at least partial uncoiling of the
actuator.
4. The arrangement of claim 2 in which the heater element is a
serpentine heater element having a serpentine portion and a return
trace, the return trace being of thicker cross-section than the
serpentine portion.
5. The arrangement of claim 1 which includes a shutter arranged
within the nozzle chamber for opening and closing the ink ejection
port, the shutter being mounted on the actuator and being in a
normally closed position in a rest condition of the actuator to
inhibit escape of ink through said ink ejection port.
6. The arrangement of claim 5 which includes a substrate with the
nozzle chamber defining means being arranged on the substrate, an
ink inlet opening being defined in the substrate.
7. The arrangement of claim 6 in which the ink inlet opening is
aligned with the ink ejection port, the shutter being interposed
between the ink inlet opening and the ink ejection port.
8. The arrangement of claim 6 in which the ink inlet opening is
arranged at an end of a supply channel through the substrate, the
supply channel having a larger cross-sectional area than the ink
inlet opening and the ink ejection port.
9. The arrangement of claim 1 in which the actuator is arranged
within said nozzle chamber.
10. The arrangement of claim 1 in which the port is defined in a
wall of the nozzle chamber defining means.
Description
[0001] The present invention further relates to the field of drop
on demand ink jet printing.
BACKGROUND OF THE INVENTION
[0002] Many different types of printing have been invented, a large
number of which are presently in use. The known forms of print have
a variety of methods for marking the print media with a relevant
marking media. Commonly used forms of printing include offset
printing, laser printing and copying devices, dot matrix type
impact printers, thermal paper printers, film recorders, thermal
wax printers, dye sublimation printers and ink jet printers both of
the drop on demand and continuous flow type. Each type of printer
has its own advantages and problems when considering cost, speed,
quality, reliability, simplicity of construction and operation
etc.
[0003] In recent years, the field of ink jet printing, wherein each
individual pixel of ink is derived from one or more ink nozzles has
become increasingly popular primarily due to its inexpensive and
versatile nature.
[0004] Many different techniques on ink jet printing have been
invented. For a survey of the field, reference is made to an
article by J Moore, "Non-Impact Printing: Introduction and
Historical Perspective", Output Hard Copy Devices, Editors R Dubeck
and S Sherr, pages 207-220 (1988).
[0005] Ink Jet printers themselves come in many different types.
The utilisation of a continuous stream ink in ink jet printing
appears to date back to at least 1929 wherein U.S. Pat. No.
1,941,001 by Hansell discloses a simple form of continuous stream
electrostatic ink jet printing.
[0006] U.S. Pat. No. 3,596,275 by Sweet also discloses a process of
a continuous ink jet printing including the step wherein the ink
jet stream is modulated by a high frequency electrostatic field so
as to cause drop separation. This technique is still used by
several manufacturers including Elmjet and Scitex (see also U.S.
Pat. No. 3,373,437 by Sweet et al)
[0007] Piezoelectric ink jet printers are also one form of commonly
used ink jet printing device. Piezoelectric systems are disclosed
by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which discloses
a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212
(1970) which discloses a squeeze mode of operation of a
piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972)
which discloses a bend mode of piezoelectric operation, Howkins in
U.S. Pat. No. 4,459,601 which discloses a piezoelectric push mode
actuation of the ink jet stream and Fischbeck in U.S. Pat. No.
4,584,590 which discloses a shear mode type of piezoelectric
transducer element.
[0008] Recently, thermal ink jet printing has become an extremely
popular form of ink jet printing. The ink jet printing techniques
include those disclosed by Endo et al in GB 2007162 (1979) and
Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned
references disclose ink jet printing techniques rely upon the
activation of an electrothermal actuator which results in the
creation of a bubble in a constricted space, such as a nozzle,
which thereby causes the ejection of ink from an aperture connected
to the confined space onto a relevant print media. Printing devices
using the electro-thermal actuator are manufactured by
manufacturers such as Canon and Hewlett Packard.
[0009] As can be seen from the foregoing, many different types of
printing technologies are available. Ideally, a printing technology
should have a number of desirable attributes. These include
inexpensive construction and operation, high speed operation, safe
and continuous long term operation etc. Each technology may have
its own advantages and disadvantages in the areas of cost, speed,
quality, reliability, power usage, simplicity of construction
operation, durability and consumables.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to provide an
alternative form of ink jet printing using an actuator and a
shuttered oscillating pressured ink supply.
[0011] In accordance with the first aspect of the present
invention, there is provided an ink jet nozzle comprising an ink
ejection port for the ejection of ink, an ink supply with an
oscillating ink pressure interconnected to the ink ejection port, a
shutter mechanism interconnected between the ink supply and the ink
ejection port, which blocks the ink ejection port, and an actuator
mechanism for moving the shutter mechanism on demand away from the
ink ejection port so as to allow for the ejection of ink on demand
from the ink ejection port.
[0012] Further, the actuator comprises a thermal actuator which is
activated by the heating of one side of the actuator. Preferably
the actuator has a coiled form and is uncoiled upon heating. The
actuator includes a serpentine heater element encased in a material
having a high coefficient of thermal expansion. The serpentine
heater concertinas upon heating. Advantageously, the actuator
includes a thick return trace for the serpentine heater element.
The material in which the serpentine heater element is encased
comprises polytetrafluoroethylene. The actuator is formed within a
nozzle chamber which is formed on a silicon wafer and ink is
supplied to the ejection port through channels etched through the
silicon wafer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Notwithstanding any other forms which may fall within the
scope of the present invention, preferred forms of the invention
will now be described, by way of example only, with reference to
the accompanying drawings in which:
[0014] FIG. 1 is an exploded perspective view illustrating the
construction of a single ink jet nozzle in accordance with the
preferred embodiment;
[0015] FIG. 2 is a perspective view, partly in section, of a single
ink jet nozzle constructed in accordance with the preferred
embodiment;
[0016] FIG. 3 provides a legend of the materials indicated in FIGS.
4 to 16; and
[0017] FIG. 4 to FIG. 16 illustrate sectional views of the
manufacturing steps in one form of construction of an ink jet
printhead nozzle.
DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS
[0018] In the preferred embodiment, an oscillating ink reservoir
pressure is used to eject ink from ejection nozzles. Each nozzle
has an associated shutter which normally blocks the nozzle. The
shutter is moved away from the nozzle by an actuator whenever an
ink drop is to be fired.
[0019] Turning initially to FIG. 1, there is illustrated in
exploded perspective a single ink jet nozzle 10 as constructed in
accordance with the principles of the present invention. The
exploded perspective illustrates a single ink jet nozzle 10.
Ideally, the nozzles are formed as an array on a silicon wafer 12.
The silicon wafer 12 is processed so as to have two level metal
CMOS circuitry which includes metal layers and glass layers 13 and
which are planarised after construction. The CMOS metal layer has a
reduced aperture 14 for the access of ink from the back of silicon
wafer 12 via an ink supply channel 15.
[0020] A bottom nitride layer 16 is constructed on top of the CMOS
layer 13 so as to cover, protect and passivate the CMOS layer 13
from subsequent etching processes. Subsequently, there is provided
a copper heater layer 18 which is sandwiched between two
polytetrafluoroethylene (PTFE) layers 19,20. The copper layer 18 is
connected to lower CMOS layer 13 through vias 25,26. The copper
layer 18 and PTFE layers 19,20 are encapsulated within nitride
borders e.g. 28 and nitride top layer 29 which includes an ink
ejection port 30 in addition to a number of sacrificial etched
access holes 32 which are of a smaller dimension than the ejection
port 30 and are provided for allowing access of a etchant to lower
sacrificial layers thereby allowing the use of the etchant in the
construction of layers, 18,19,20 and 28.
[0021] Turning now to FIG. 2, there is shown a cutaway perspective
view of a fully constructed ink jet nozzle 10. The ink jet nozzle
uses an oscillating ink pressure to eject ink from ejection port
30. Each nozzle has an associated shutter 31 which normally blocks
it. The shutter 31 is moved away from the ejection port 30 by an
actuator 35 whenever an ink drop is to be fired.
[0022] The ports 30 are in communication with ink chambers which
contain the actuators 35. These chambers are connected to ink
supply channels 15 which are etched through the silicon wafer. The
ink supply channels 15 are substantially wider than the ports 30,
to reduce the fluidic resistance to the ink pressure wave. The ink
channels 15 are connected to an ink reservoir. An ultrasonic
transducer (for example, a piezoelectric transducer) is positioned
in the reservoir. The transducer oscillates the ink pressure at
approximately 100 KHz. The ink pressure oscillation is sufficient
that ink drops would be ejected from the nozzle were it not blocked
by the shutter 31.
[0023] The shutters are moved by a thermoelastic actuator 35. The
actuators are formed as a coiled serpentine copper heater 23
embedded in polytetrafluoroethylene (PTFE) 19/20. PTFE has a very
high coefficient of thermal expansion (approximately
770.times.10.sup.-6). The current return trace 22 from the heater
23 is also embedded in the PTFE actuator 35, the current return
trace 22 is made wider than the heater trace 23 and is not
serpentine. Therefore, it does not heat the PTFE as much as the
serpentine heater 23 does. The serpentine heater 23 is positioned
along the inside edge of the PTFE coil, and the return trace is
positioned on the outside edge. When actuated, the inside edge
becomes hotter than the outside edge, and expands more. This
results in the actuator 35 uncoiling.
[0024] The heater layer 23 is etched in a serpentine manner both to
increase its resistance, and to reduce its effective tensile
strength along the length of the actuator. This is so that the low
thermal expansion of the copper does not prevent the actuator from
expanding according to the high thermal expansion characteristics
of the PTFE.
[0025] By varying the power applied to the actuator 35, the shutter
31 can be positioned between the fully on and fully off positions.
This may be used to vary the volume of the ejected drop. Drop
volume control may be used either to implement a degree of
continuous tone operation, to regulate the drop volume, or
both.
[0026] When data signals distributed on the printhead indicate that
a particular nozzle is turned on, the actuator 35 is energized,
which moves the shutter 31 so that it is not blocking the ink
chamber. The peak of the ink pressure variation causes the ink to
be squirted out of the nozzle 30. As the ink pressure goes
negative, ink is drawn back into the nozzle, causing drop
break-off. The shutter 31 is kept open until the nozzle is refilled
on the next positive pressure cycle. It is then shut to prevent the
ink from being withdrawn from the nozzle on the next negative
pressure cycle.
[0027] Each drop ejection takes two ink pressure cycles. Preferably
half of the nozzles 10 should eject drops in one phase, and the
other half of the nozzles should eject drops in the other phase.
This minimises the pressure variations which occur due to a large
number of nozzles being actuated.
[0028] The amplitude of the ultrasonic transducer can be altered in
response to the viscosity of the ink (which is typically affected
by temperature), and the number of drops which are to be ejected in
the current cycle. This amplitude adjustment can be used to
maintain consistent drop size in varying environmental
conditions.
[0029] The drop firing rate can be around 50 KHz. The ink jet head
is suitable for fabrication as a monolithic page wide printhead.
FIG. 2 shows a single nozzle of a 1600 dpi printhead in "up
shooter" configuration.
[0030] Returning again to FIG. 1, one method of construction of the
ink jet print nozzles 10 will now be described. Starting with the
bottom wafer layer 12, the wafer is processed so as to add CMOS
layers 13 with an aperture 14 being inserted. The nitride layer 16
is laid down on top of the CMOS layers so as to protect them from
subsequent etchings.
[0031] A thin sacrificial glass layer is then laid down on top of
nitride layers 16 followed by a first PTFE layer 19, the copper
layer 18 and a second PTFE layer 20. Then a sacrificial glass layer
is formed on top of the PTFE layer and etched to a depth of a few
microns to form the nitride border regions 28. Next the top layer
29 is laid down over the sacrificial layer using the mask for
forming the various holes including the processing step of forming
the rim 40 on nozzle 30. The sacrificial glass is then dissolved
away and the channel 15 formed through the wafer by means of
utilisation of high density low pressure plasma etching such as
that available from Surface Technology Systems.
[0032] One form of detailed manufacturing process which can be used
to fabricate monolithic ink jet printheads operating in accordance
with the principles taught by the present embodiment can proceed
using the following steps:
[0033] 1. Using a double sided polished wafer 12, complete drive
transistors, data distribution, and timing circuits using a 0.5
micron, one poly, 2 metal CMOS process 13. The wafer is passivated
with 0.1 microns of silicon nitride 16. This step is shown in FIG.
4. For clarity, these diagrams may not be to scale, and may not
represent a cross section though any single plane of the nozzle.
FIG. 3 is a key to representations of various materials in these
manufacturing diagrams, and those of other cross referenced ink jet
configurations.
[0034] 2. Etch nitride and oxide down to silicon using Mask 1. This
mask defines the nozzle inlet below the shutter. This step is shown
in FIG. 5.
[0035] 3. Deposit 3 microns of sacrificial material 50 (e.g.
aluminum or photosensitive polyimide)
[0036] 4. Planarize the sacrificial layer to a thickness of 1
micron over nitride. This step is shown in FIG. 6.
[0037] 5. Etch the sacrificial layer using Mask 2. This mask
defines the actuator anchor point 51. This step is shown in FIG.
7.
[0038] 6. Deposit 1 micron of PTFE 52.
[0039] 7. Etch the PTFE, nitride, and oxide down to second level
metal using Mask 3. This mask defines the heater vias 25,26. This
step is shown in FIG. 8.
[0040] 8. Deposit the heater 53, which is a 1 micron layer of a
conductor with a low Young's modulus, for example aluminum or
gold.
[0041] 9. Pattern the conductor using Mask 4. This step is shown in
FIG. 9.
[0042] 10. Deposit 1 micron of PTFE 54.
[0043] 11. Etch the PTFE down to the sacrificial layer using Mask
5. This mask defines the actuator and shutter This step is shown in
FIG. 10.
[0044] 12. Wafer probe. All electrical connections are complete at
this point, bond pads are accessible, and the chips are not yet
separated.
[0045] 13. Deposit 3 microns of sacrificial material 55. Planarize
using CMP
[0046] 14. Etch the sacrificial material using Mask 6. This mask
defines the nozzle chamber wall 28. This step is shown in FIG.
11.
[0047] 15. Deposit 3 microns of PECVD glass 56.
[0048] 16. Etch to a depth of (approx.) 1 micron using Mask 7. This
mask defines the nozzle rim 40. This step is shown in FIG. 12.
[0049] 17. Etch down to the sacrificial layer using Mask 6. This
mask defines the roof of the nozzle chamber, the nozzle 30, and the
sacrificial etch access holes 32. This step is shown in FIG.
13.
[0050] 18. Back-etch completely through the silicon wafer (with,
for example, an ASE Advanced Silicon Etcher from Surface Technology
Systems) using Mask 7. This mask defines the ink inlets 15 which
are etched through the wafer. The wafer is also diced by this etch.
This step is shown in FIG. 14.
[0051] 19. Etch the sacrificial material. The nozzle chambers are
cleared, the actuators freed, and the chips are separated by this
etch. This step is shown in FIG. 15.
[0052] 20. Mount the printheads in their packaging, which may be a
molded plastic former incorporating ink channels which supply the
appropriate color ink to the ink inlets at the back of the wafer.
The package also includes a piezoelectric actuator attached to the
rear of the ink channels. The piezoelectric actuator provides the
oscillating ink pressure required for the ink jet operation.
[0053] 21. Connect the printheads to their interconnect systems.
For a low profile connection with minimum disruption of airflow,
TAB may be used. Wire bonding may also be used if the printer is to
be operated with sufficient clearance to the paper.
[0054] 22. Hydrophobize the front surface of the printheads.
[0055] 23. Fill the completed printheads with ink 57 and test them.
A filled nozzle is shown in FIG. 16.
[0056] It would be appreciated by a person skilled in the art that
numerous variations and/or modifications may be made to the present
invention as shown in the preferred embodiment without departing
from the spirit or scope of the invention as broadly described. The
present embodiment is, therefore, to be considered in all respects
to be illustrative and not restrictive.
[0057] The presently disclosed ink jet printing technology is
potentially suited to a wide range of printing systems including:
colour and monochrome office printers, short run digital printers,
high speed digital printers, offset press supplemental printers,
low cost scanning printers, high speed pagewidth printers, notebook
computers with inbuilt pagewidth printers, portable colour and
monochrome printers, colour and monochrome copiers, colour and
monochrome facsimile machines, combined printer, facsimile and
copying machines, label printers, large format plotters, photograph
copiers, printers for digital photographic `minilabs`, video
printers, PhotoCD printers, portable printers for PDAs, wallpaper
printers, indoor sign printers, billboard printers, fabric
printers, camera printers and fault tolerant commercial printer
arrays.
[0058] Ink Jet Technologies
[0059] The embodiments of the invention use an ink jet printer type
device. Of course many different devices could be used. However
presently popular ink jet printing technologies are unlikely to be
suitable.
[0060] The most significant problem with thermal ink jet is power
consumption. This is approximately 100 times that required for high
speed, and stems from the energy-inefficient means of drop
ejection. This involves the rapid boiling of water to produce a
vapor bubble which expels the ink. Water has a very high heat
capacity, and must be superheated in thermal ink jet applications.
This leads to an efficiency of around 0.02%, from electricity input
to drop momentum (and increased surface area) out.
[0061] The most significant problem with piezoelectric ink jet is
size and cost. Piezoelectric crystals have a very small deflection
at reasonable drive voltages, and therefore require a large area
for each nozzle. Also, each piezoelectric actuator must be
connected to its drive circuit on a separate substrate. This is not
a significant problem at the current limit of around 300 nozzles
per printhead, but is a major impediment to the fabrication of
pagewidth printheads with 19,200 nozzles.
[0062] Ideally, the ink jet technologies used meet the stringent
requirements of in-camera digital color printing and other high
quality, high speed, low cost printing applications. To meet the
requirements of digital photography, new ink jet technologies have
been created. The target features include:
[0063] low power (less than 10 Watts)
[0064] high resolution capability (1,600 dpi or more)
[0065] photographic quality output
[0066] low manufacturing cost
[0067] small size (pagewidth times minimum cross section)
[0068] high speed (<2 seconds per page).
[0069] All of these features can be met or exceeded by the ink jet
systems described below with differing levels of difficulty.
Forty-five different ink jet technologies have been developed by
the Assignee to give a wide range of choices for high volume
manufacture. These technologies form part of separate applications
assigned to the present Assignee as set out in the table under the
heading Cross References to Related Applications.
[0070] The ink jet designs shown here are suitable for a wide range
of digital printing systems, from battery powered one-time use
digital cameras, through to desktop and network printers, and
through to commercial printing systems.
[0071] For ease of manufacture using standard process equipment,
the printhead is designed to be a monolithic 0.5 micron CMOS chip
with MEMS post processing. For color photographic applications, the
printhead is 100 mm long, with a width which depends upon the ink
jet type. The smallest printhead designed is IJ38, which is 0.35 mm
wide, giving a chip area of 35 square mm. The printheads each
contain 19,200 nozzles plus data and control circuitry.
[0072] Ink is supplied to the back of the printhead by injection
molded plastic ink channels. The molding requires 50 micron
features, which can be created using a lithographically
micromachined insert in a standard injection molding tool. Ink
flows through holes etched through the wafer to the nozzle chambers
fabricated on the front surface of the wafer. The printhead is
connected to the camera circuitry by tape automated bonding.
[0073] Tables of Drop-on-Demand Ink Jets
[0074] Eleven important characteristics of the fundamental
operation of individual ink jet nozzles have been identified. These
characteristics are largely orthogonal, and so can be elucidated as
an eleven dimensional matrix. Most of the eleven axes of this
matrix include entries developed by the present assignee.
[0075] The following tables form the axes of an eleven dimensional
table of ink jet types.
[0076] Actuator mechanism (18 types)
[0077] Basic operation mode (7 types)
[0078] Auxiliary mechanism (8 types)
[0079] Actuator amplification or modification method (17 types)
[0080] Actuator motion (19 types)
[0081] Nozzle refill method (4 types)
[0082] Method of restricting back-flow through inlet (10 types)
[0083] Nozzle clearing method (9 types)
[0084] Nozzle plate construction (9 types)
[0085] Drop ejection direction (5 types)
[0086] Ink type (7 types)
[0087] The complete eleven dimensional table represented by these
axes contains 36.9 billion possible configurations of ink jet
nozzle. While not all of the possible combinations result in a
viable ink jet technology, many million configurations are viable.
It is clearly impractical to elucidate all of the possible
configurations. Instead, certain ink jet types have been
investigated in detail. These are designated IJ01 to IJ45 above
which matches the docket numbers in the table under the heading
Cross References to Related Applications.
[0088] Other ink jet configurations can readily be derived from
these forty-five examples by substituting alternative
configurations along one or more of the 11 axes. Most of the IJ01
to IJ45 examples can be made into ink jet printheads with
characteristics superior to any currently available ink jet
technology.
[0089] Where there are prior art examples known to the inventor,
one or more of these examples are listed in the examples column of
the tables below. The IJ01 to IJ45 series are also listed in the
examples column. In some cases, a print technology may be listed
more than once in a table, where it shares characteristics with
more than one entry.
[0090] Suitable applications for the ink jet technologies include:
Home printers, Office network printers, Short run digital printers,
Commercial print systems, Fabric printers, Pocket printers,
Internet WVW printers, Video printers, Medical imaging, Wide format
printers, Notebook PC printers, Fax machines, Industrial printing
systems, Photocopiers, Photographic minilabs etc.
[0091] The information associated with the aforementioned 11
dimensional matrix are set out in the following tables.
1 Description Advantages Disadvantages Examples ACTUATOR MECHANISM
(APPLIED ONLY TO SELECTED INK DROPS) Thermal An electrothermal
Large force High power Canon Bubblejet bubble heater heats the ink
to generated Ink carrier 1979 Endo et al GB above boiling point,
Simple limited to water patent 2,007,162 transferring significant
construction Low efficiency Xerox heater-in- heat to the aqueous No
moving parts High pit 1990 Hawkins et ink. A bubble Fast operation
temperatures al U.S. Pat. 4,899,181 nucleates and quickly Small
chip area required Hewlett-Packard forms, expelling the required
for actuator High mechanical TIJ 1982 Vaught et ink. stress al U.S.
Pat. 4,490,728 The efficiency of the Unusual process is low, with
materials required typically less than Large drive 0.05% of the
electrical transistors energy being Cavitation causes transformed
into actuator failure kinetic energy of the Kogation reduces drop.
bubble formation Large print heads are difficult to fabricate
Piezo- A piezoelectric crystal Low power Very large area Kyser et
al U.S. Pat. electric such as lead consumption required for
actuator 3,946,398 lanthanum zirconate Many ink types Difficult to
Zoltan U.S. Pat. (PZT) is electrically can be used integrate with
3,683,212 activated, and either Fast operation electronics 1973
Stemme expands, shears, or High efficiency High voltage U.S. Pat.
3,747,120 bends to apply drive transistors Epson Stylus pressure to
the ink, required Tektronix ejecting drops. Full pagewidth IJ04
print heads impractical due to actuator size Requires electrical
poling in high field strengths during manufacture Electro- An
electric field is Low power Low maximum Seiko Epson, strictive used
to activate consumption strain (approx. Usui et all JP
electrostriction in Many ink types 0.01%) 253401/96 relaxor
materials such can be used Large area IJ04 as lead lanthanum Low
thermal required for actuator zirconate titanate expansion due to
low strain (PLZT) or lead Electric field Response speed magnesium
niobate strength required is marginal (.about.10 (PMN). (approx.
3.5 V/.mu.m) .mu.s) can be generated High voltage without
difficulty drive transistors Does not require required electrical
poling Full pagewidth print heads impractical due to actuator size
Ferro- An electric field is Low power Difficult to IJ04 electric
used to induce a phase consumption integrate with transition
between the Many ink types electronics antiferroelectric (AFE) can
be used Unusual and ferroelectric (FE) Fast operation materials
such as phase. Perovskite (<1 .mu.s) PLZSnT are materials such
as tin Relatively high required modified lead longitudinal strain
Actuators require lanthanum zirconate High efficiency a large area
titanate (PLZSnT) Electric field exhibit large strains of strength
of around 3 up to 1% associated V/.mu.m can be readily with the AFE
to FE provided phase transition. Electro- Conductive plates are Low
power Difficult to IJ02, IJ04 static plates separated by a
consumption operate electrostatic compressible or fluid Many ink
types devices in an dielectric (usually air). can be used aqueous
Upon application of a Fast operation environment voltage, the
plates The electrostatic attract each other and actuator will
displace ink, causing normally need to be drop ejection. The
separated from the conductive plates may ink be in a comb or Very
large area honeycomb structure, required to achieve or stacked to
increase high forces the surface area and High voltage therefore
the force. drive transistors may be required Full pagewidth print
heads are not competitive due to actuator size Electro- A strong
electric field Low current High voltage 1989 Saito et al, static
pull is applied to the ink, consumption required U.S. Pat. No.
4,799,068 on ink whereupon Low temperature May be damaged 1989
Miura et al, electrostatic attraction by sparks due to air U.S.
Pat. No. 4,810,954 accelerates the ink breakdown Tone-jet towards
the print Required field medium. strength increases as the drop
size decreases High voltage drive transistors required
Electrostatic field attracts dust Permanent An electromagnet Low
power Complex IJ07, IJ10 magnet directly attracts a consumption
fabrication electro- permanent magnet, Many ink types Permanent
magnetic displacing ink and can be used magnetic material causing
drop ejection. Fast operation such as Neodymium Rare earth magnets
High efficiency Iron Boron (NdFeB) with a field strength Easy
extension required. around 1 Tesla can be from single nozzles High
local used. Examples are: to pagewidth print currents required
Samarium Cobalt heads Copper (SaCo) and magnetic metalization
should materials in the be used for long neodymium iron boron
electromigration family (NdFeB, lifetime and low NdDyFeBNb,
resistivity NdDyFeB, etc) Pigmented inks are usually infeasible
Operating temperature limited to the Curie temperature (around 540
K.) Soft A solenoid induced a Low power Complex IJ01, IJ05, IJ08,
magnetic magnetic field in a soft consumption fabrication IJ10,
IJ12, IJ14, core electro- magnetic core or yoke Many ink types
Materials not IJ15, IJ17 magnetic fabricated from a can be used
usually present in a ferrous material such Fast operation CMOS fab
such as as electroplated iron High efficiency NiFe, CoNiFe, or
alloys such as CoNiFe Easy extension CoFe are required [1], CoFe,
or NiFe from single nozzles High local alloys. Typically, the to
pagewidth print currents required soft magnetic material heads
Copper is in two parts, which metalization should are normally held
be used for long apart by a spring. electromigration When the
solenoid is lifetime and low actuated, the two parts resistivity
attract, displacing the Electroplating is ink. required High
saturation flux density is required (2.0-2.1 T is achievable with
CoNiFe [1]) Lorenz The Lorenz force Low power Force acts as a IJ06,
IJ11, IJ13, force acting on a current consumption twisting motion
IJ16 carrying wire in a Many ink types Typically, only a magnetic
field is can be used quarter of the utilized. Fast operation
solenoid length This allows the High efficiency provides force in a
magnetic field to be Easy extension useful direction supplied
externally to from single nozzles High local the print head, for to
pagewidth print currents required example with rare heads Copper
earth permanent metalization should magnets. be used for long Only
the current electromigration carrying wire need be lifetime and low
fabricated on the print- resistivity head, simplifying Pigmented
inks materials are usually requirements. infeasible Magneto- The
actuator uses the Many ink types Force acts as a Fischenbeck,
striction giant magnetostrictive can be used twisting motion U.S.
Pat. No. 4,032,929 effect of materials Fast operation Unusual IJ25
such as Terfenol-D (an Easy extension materials such as alloy of
terbium, from single nozzles Terfenol-D are dysprosium and iron to
pagewidth print required developed at the Naval heads High local
Ordnance Laboratory, High force is currents required hence
Ter-Fe-NOL). available Copper For best efficiency, the metalization
should actuator should be pre- be used for long stressed to approx.
8 electromigration MPa. lifetime and low resistivity Pre-stressing
may be required Surface Ink under positive Low power Requires
Silverbrook, EP tension pressure is held in a consumption
supplementary force 0771 658 A2 and reduction nozzle by surface
Simple to effect drop related patent tension. The surface
construction separation applications tension of the ink is No
unusual Requires special reduced below the materials required in
ink surfactants bubble threshold, fabrication Speed may be causing
the ink to High efficiency limited by surfactant egress from the
Easy extension properties nozzle. from single nozzles to pagewidth
print heads Viscosity The ink viscosity is Simple Requires
Silverbrook, EP reduction locally reduced to construction
supplementary force 0771 658 A2 and select which drops are No
unusual to effect drop related patent to be ejected. A materials
required in separation applications viscosity reduction can
fabrication Requires special be achieved Easy extension ink
viscosity electrothermally with from single nozzles properties most
inks, but special to pagewidth print High speed is inks can be
engineered heads difficult to achieve for a 100:1 viscosity
Requires reduction. oscillating ink pressure A high temperature
difference (typically 80 degrees) is required Acoustic An acoustic
wave is Can operate Complex drive 1993 Hadimioglu generated and
without a nozzle circuitry et al, EUP 550,192 focussed upon the
plate Complex 1993 Elrod et al, drop ejection region. fabrication
EUP 572,220 Low efficiency Poor control of drop position Poor
control of drop volume Thermo- An actuator which Low power
Efficient aqueous IJ03, IJ09, IJ17, elastic bend relies upon
differential consumption operation requires a IJ18, IJ19, IJ20,
actuator thermal expansion Many ink types thermal insulator on
IJ21, IJ22, IJ23, upon Joule heating is can be used the hot side
IJ24, IJ27, IJ28, used. Simple planar Corrosion IJ29, IJ30, IJ31,
fabrication prevention can be IJ32, IJ33, IJ34, Small chip area
difficult IJ35, IJ36, IJ37, required for each Pigmented inks IJ38,
IJ39, IJ40, actuator may be infeasible, IJ41 Fast operation as
pigment particles High efficiency may jam the bend CMOS actuator
compatible voltages and currents Standard MEMS processes can be
used Easy extension from single nozzles to pagewidth print heads
High CTE A material with a very High force can Requires special
IJ09, IJ17, IJ18, thermo- high coefficient of be generated material
(e.g. PTFE) IJ20, IJ21, IJ22, elastic thermal expansion Three
methods of Requires a PTFE IJ23, IJ24, IJ27, actuator (CTE) such as
PTFE deposition are deposition process, IJ28, IJ29, IJ30,
polytetrafluoroethylene under development: which is not yet IJ31,
IJ42, IJ43, (PTFE) is used. As chemical vapor standard in ULSI IJ44
high CTE materials deposition (CVD), fabs are usually non- spin
coating, and PTFE deposition conductive, a heater evaporation
cannot be followed fabricated from a PTFE is a with high conductive
material is candidate for low temperature (above incorporated. A 50
.mu.m dielectric constant 350.degree. C.) processing long PTFE bend
insulation in ULSI Pigmented inks actuator with Very low power may
be infeasible, polysilicon heater and consumption as pigment
particles 15 mW power input Many ink types may jam the bend can
provide 180 .mu.N can be used actuator force and 10 .mu.m Simple
planar deflection. Actuator fabrication motions include: Small chip
area Bend required for each Push actuator Buckle Fast operation
Rotate High efficiency CMOS compatible voltages and currents Easy
extension from single nozzles to pagewidth print heads Conduct-ive
A polymer with a high High force can Requires special IJ24 polymer
coefficient of thermal be generated materials thermo- expansion
(such as Very low power development (High elastic PTFE) is doped
with consumption CTE conductive actuator conducting substances Many
ink types polymer) to increase its can be used Requires a PTFE
conductivity to about 3 Simple planar deposition process, orders of
magnitude fabrication which is not yet below that of copper. Small
chip area standard in ULSI The conducting required for each fabs
polymer expands actuator PTFE deposition when resistively Fast
operation cannot be followed heated. High efficiency with high
Examples of CMOS temperature (above conducting dopants compatible
voltages 350.degree. C.) processing include: and currents
Evaporation and Carbon nanotubes Easy extension CVD deposition
Metal fibers from single nozzles techniques cannot Conductive
polymers to pagewidth print be used such as doped heads Pigmented
inks polythiophene may be infeasible, Carbon granules as pigment
particles may jam the bend actuator Shape A shape memory alloy High
force is Fatigue limits IJ26 memory such as TiNi (also available
(stresses maximum number alloy known as Nitinol - of hundreds of
MPa) of cycles Nickel Titanium alloy Large strain is Low strain
(1%) developed at the Naval available (more than is required to
extend Ordnance Laboratory) 3%) fatigue resistance is thermally
switched High corrosion Cycle rate between its weak resistance
limited by heat martensitic state and Simple removal its high
stiffness construction Requires unusual austenic state. The Easy
extension materials (TiNi) shape of the actuator from single
nozzles The latent heat of in its martensitic state to pagewidth
print transformation must is deformed relative to heads be provided
the austenic shape. Low voltage High current The shape change
operation operation causes ejection of a Requires pre- drop.
stressing to distort the martensitic state Linear Linear magnetic
Linear Magnetic Requires unusual IJ12 Magnetic actuators include
the actuators can be semiconductor Actuator Linear Induction
constructed with materials such as Actuator (LIA), Linear high
thrust, long soft magnetic alloys Permanent Magnet travel, and high
(e.g. CoNiFe) Synchronous Actuator efficiency using Some varieties
(LPMSA), Linear planar also require Reluctance semiconductor
permanent magnetic Synchronous Actuator fabrication materials such
as (LRSA), Linear techniques Neodymium iron Switched Reluctance
Long actuator boron (NdFeB) Actuator (LSRA), and travel is
available Requires the Linear Stepper Medium force is complex
multi- Actuator (LSA). available phase drive circuitly Low voltage
High current operation operation BASIC OPERATION MODE Actuator This
is the simplest Simple operation Drop repetition Thermal ink jet
directly mode of operation: the No external rate is usually
Piezoelectric ink pushes ink actuator directly fields required
limited to around 10 jet supplies sufficient Satellite drops kHz.
However, this IJ01, IJ02, IJ03, kinetic energy to expel can be
avoided if is not fundamental IJ04, IJ05, IJ06, the drop. The drop
drop velocity is less to the method, but is IJ07, IJ09, IJ11, must
have a sufficient than 4 m/s related to the refill IJ12, IJ14,
IJ16, velocity to overcome Can be efficient, method normally IJ20,
IJ22, IJ23, the surface tension. depending upon the used IJ24,
IJ25, IJ26, actuator used All of the drop IJ27, IJ28, IJ29, kinetic
energy must IJ30, IJ31, IJ32, be provided by the IJ33, IJ34, IJ35,
actuator IJ36, IJ37, IJ38, Satellite drops IJ39, IJ40, IJ41,
usually form if drop IJ42, IJ43, IJ44 velocity is greatere than 4.5
m/s Proximity The drops to be Very simple print Requires close
Silverbrook, EP printed are selected by head fabrication can
proximity between 0771 658 A2 and some manner (e.g. be used the
print head and related patent thermally induced The drop the print
media or applications surface tension selection means transfer
roller reduction
of does not need to May require two pressurized ink), provide the
energy print heads printing Selected drops are required to separate
alternate rows of the separated from the ink the drop from the
image in the nozzle by nozzle Monolithic color contact with the
print print heads are medium or a transfer difficult roller.
Electro- The drops to be Very simple print Requires very
Silverbrook, EP static pull printed are selected by head
fabrication can high electrostatic 0771 658 A2 and on ink some
manner (e.g. be used field related patent thermally induced The
drop Electrostatic field applications surface tension selection
means for small nozzle Tone-Jet reduction of does not need to sizes
is above air pressurized ink), provide the energy breakdown
Selected drops are required to separate Electrostatic field
separated from the ink the drop from the may attract dust in the
nozzle by a nozzle strong electric field. Magnetic The drops to be
Very simple print Requires Silverbrook, EP pull on ink printed are
selected by head fabrication can magnetic ink 0771 658 A2 and some
manner (e.g. be used Ink colors other related patent thermally
induced The drop than black are applications surface tension
selection means difficult reduction of does not need to Requires
very pressurized ink), provide the energy high magnetic fields
Selected drops are required to separate separated from the ink the
drop from the in the nozzle by a nozzle strong magnetic field
acting on the magnetic ink. Shutter The actuator moves a High speed
(>50 Moving parts are IJ13, IJ17, IJ21 shutter to block ink kHz)
operation can required flow to the nozzle. The be achieved due to
Requires ink ink pressure is pulsed reduced refill time pressure
modulator at a multiple of the Drop timing can Friction and wear
drop ejection be very accurate must be considered frequency. The
actuator Stiction is energy can be very possible low Shuttered The
actuator moves a Actuators with Moving parts are IJ08, IJ15, IJ18,
grill shutter to block ink small travel can be required IJ19 flow
through a grill to used Requires ink the nozzle. The shutter
Actuators with pressure modulator movement need only small force
can be Friction and wear be equal to the width used must be
considered of the grill holes. High speed (>50 Stiction is kHz)
operation can possible be achieved Pulsed A pulsed magnetic
Extremely low Requires an IJ10 magnetic field attracts an `ink
energy operation is external pulsed pull on ink pusher` at the drop
possible magnetic field pusher ejection frequency. An No heat
Requires special actuator controls a dissipation materials for both
catch, which prevents problems the actuator and the the ink pusher
from ink pusher moving when a drop is Complex not to be ejected.
construction AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Electro-
An electric field is Low power Field strength Silverbrook, EP
static used to accelerate Simple print head required for 0771 658
A2 and selected drops towards construction separation of small
related patent the print medium. drops is near or applications
above air Tone-Jet breakdown Direct A magnetic field is Low power
Requires Silverbrook, EP magnetic used to accelerate Simple print
head magnetic ink 0771 658 A2 and field selected drops of
construction Requires strong related patent magnetic ink towards
magnetic field applications the print medium. Cross The print head
is Does not require Requires external IJ06, IJ16 magnetic placed in
a constant magnetic materials magnet field magnetic field. The to
be integrated in Current densities Lorenz force in a the print head
may be high, current carrying wire manufacturing resulting in is
used to move the process electromigration actuator. problems Pulsed
A pulsed magnetic Very low power Complex print IJ10 magnetic field
is used to operation is possible head construction field cyclically
attract a Small print head Magnetic paddle, which pushes size
materials required in on the ink. A small print head actuator moves
a catch, which selectively prevents the paddle from moving.
ACTUATOR AMPLIFICATION OR MODIFICATION METHOD None No actuator
Operational Many actuator Thermal Bubble mechanical simplicity
mechanisms have Ink jet amplification is used. insufficient travel,
IJ01, IJ02, IJ06, The actuator directly or insufficient force,
IJ07, IJ16, IJ25, drives the drop to efficiently drive IJ26
ejection process. the drop ejection process Differential An
actuator material Provides greater High stresses are Piezoelectric
expansion expands more on one travel in a reduced involved IJ03,
IJ09, IJ17, bend side than on the other. print head area Care must
be IJ18, IJ19, IJ20, actuator The expansion may be taken that the
IJ21, IJ22, IJ23, thermal, piezoelectric, materials do not IJ24,
IJ27, IJ29, magnetostrictive, or delaminate IJ30, IJ31, IJ32, other
mechanism. The Residual bend IJ33, IJ34, IJ35, bend actuator
converts resulting from high IJ36, IJ37, IJ38, a high force low
travel temperature or high IJ39, IJ42, IJ43, actuator mechanism to
stress during IJ44 high travel, lower formation force mechanism.
Transient A trilayer bend Very good High stresses are IJ40, IJ41
bend actuator where the two temperature stability involved actuator
outside layers are High speed, as a Care must be identical. This
cancels new drop can be taken that the bend due to ambient fired
before heat materials do not temperature and dissipates delaminate
residual stress. The Cancels residual actuator only responds stress
of formation to transient heating of one side or the other. Reverse
The actuator loads a Better coupling Fabrication IJ05, IJ11 spring
spring. When the to the ink complexity actuator is turned off, High
stress in the the spring releases. spring This can reverse the
force/distance curve of the actuator to make it compatible with the
force/time requirements of the drop ejection. Actuator A series of
thin Increased travel Increased Some stack actuators are stacked.
Reduced drive fabrication piezoelectric ink jets This can be
voltage complexity IJ04 appropriate where Increased actuators
require high possibility of short electric field strength, circuits
due to such as electrostatic pinholes and piezoelectric actuators.
Multiple Multiple smaller Increases the Actuator forces IJ12, IJ13,
IJ18, actuators actuators are used force available from may not add
IJ20, IJ22, IJ28, simultaneously to an actuator linearly, reducing
IJ42, IJ43 move the ink. Each Multiple efficiency actuator need
provide actuators can be only a portion of the positioned to
control force required. ink flow accurately Linear A linear spring
is used Matches low Requires print IJ15 Spring to transform a
motion travel actuator with head area for the with small travel and
higher travel spring high force into a requirements longer travel,
lower Non-contact force motion. method of motion transformation
Coiled A bend actuator is Increases travel Generally IJ17, IJ21,
IJ34, actuator coiled to provide Reduces chip restricted to planar
IJ35 greater travel in a area implementations reduced chip area.
Planar due to extreme implementations are fabrication difficulty
relatively easy to in other orientations. fabricate. Flexure A bend
actuator has a Simple means of Care must be IJ10, IJ19, IJ33 bend
small region near the increasing travel of taken not to exceed
actuator fixture point, which a bend actuator the elastic limit in
flexes much more the flexure area readily than the Stress remainder
of the distribution is very actuator. The actuator uneven flexing
is effectively Difficult to converted from an accurately model even
coiling to an with finite element angular bend, resulting analysis
in greater travel of the actuator tip. Catch The actuator controls
a Very low Complex IJ10 small catch. The catch actuator energy
construction either enables or Very small Requires external
disables movement of actuator size force an ink pusher that is
Unsuitable for controlled in a bulk pigmented inks manner. Gears
Gears can be used to Low force, low Moving parts are IJ13 increase
travel at the travel actuators can required expense of duration. be
used Several actuator Circular gears, rack Can be fabricated cycles
are required and pinion, ratchets, using standard More complex and
other gearing surface MEMS drive electronics methods can be used.
processes Complex construction Friction, friction, and wear are
possible Buckle plate A buckle plate can be Very fast Must stay
within S. Hirata et al, used to change a slow movement elastic
limits of the "An Ink-jet Head actuator into a fast achievable
materials for long Using Diaphragm motion. It can also device life
Microactuator", convert a high force, High stresses Proc. IEEE
MEMS, low travel actuator involved Feb. 1996, pp 418- into a high
travel, Generally high 423. medium force motion. power requirement
IJ18, IJ27 Tapered A tapered magnetic Linearizes the Complex IJ14
magnetic pole can increase magnetic construction pole travel at the
expense force/distance curve of force. Lever A lever and fulcrum is
Matches low High stress IJ32, IJ36, IJ37 used to transform a travel
actuator with around the fulcrum motion with small higher travel
travel and high force requirements into a motion with Fulcrum area
has longer travel and no linear movement, lower force. The lever
and can be used for can also reverse the a fluid seal direction of
travel. Rotary The actuator is High mechanical Complex IJ28
impeller connected to a rotary advantage construction impeller. A
small The ratio of force Unsuitable for angular deflection of to
travel of the pigmented inks the actuator results in actuator can
be a rotation of the matched to the impeller vanes, which nozzle
requirements push the ink against by varying the stationary vanes
and number of impeller out of the nozzle. vanes Acoustic A
refractive or No moving parts Large area 1993 Hadimioglu lens
diffractive (e.g. zone required et al, EUP 550,192 plate) acoustic
lens is Only relevant for 1993 Elrod et al, used to concentrate
acoustic ink jets EUP 572,220 sound waves. Sharp A sharp point is
used Simple Difficult to Tone-jet conductive to concentrate an
construction fabricate using point electrostatic field. standard
VLSI processes for a surface ejecting ink- jet Only relevant for
electrostatic ink jets ACTUATOR MOTION Volume The volume of the
Simple High energy is Hewlett-Packard expansion actuator changes,
construction in the typically required to Thermal Ink jet pushing
the ink in all case of thermal ink achieve volume Canon Bubblejet
directions. jet expansion. This leads to thermal stress,
cavitation, and kogation in thermal ink jet implementations Linear,
The actuator moves in Efficient High fabrication IJ01, IJ02, IJ04,
normal to a direction normal to coupling to ink complexity may be
IJ07, IJ11, IJ14 chip surface the print head surface. drops ejected
required to achieve The nozzle is typically normal to the
perpendicular in the line of surface motion movement. Parallel to
The actuator moves Suitable for Fabrication IJ12, IJ13, IJ15, chip
surface parallel to the print planar fabrication complexity IJ33,
IJ34, IJ35, head surface. Drop Friction IJ36 ejection may still be
Stiction normal to the surface. Membrane An actuator with a The
effective Fabrication 1982 Howkins push high force but small area
of the actuator complexity U.S. Pat. No. 4,459,601 area is used to
push a becomes the Actuator size stiff membrane that is membrane
area Difficulty of in contact with the ink. integration in a VLSI
process Rotary The actuator causes Rotary levers Device IJ05, IJ08,
IJ13, the rotation of some may be used to complexity IJ28 element,
such a grill or increase travel May have impeller Small chip area
friction at a pivot requirements point Bend The actuator bends A
very small Requires the 1970 Kyser et al when energized. This
change in actuator to be made U.S. Pat. No. 3,946,398 may be due to
dimensions can be from at least two 1973 Stemme differential
thermal converted to a large distinct layers, or to U.S. Pat. No.
3,747,120 expansion, motion. have a thermal IJ03, IJ09, IJ10,
piezoelectric difference across the IJ19, IJ23, IJ24, expansion,
actuator IJ25, IJ29, IJ30, magnetostriction, or IJ31, IJ33, IJ34,
other form of relative IJ35 dimensional change. Swivel The actuator
swivels Allows operation Inefficient IJ06 around a central pivot.
where the net linear coupling to the ink This motion is suitable
force on the paddle motion where there are is zero opposite forces
Small chip area applied to opposite requirements sides of the
paddle, e.g. Lorenz force. Straighten The actuator is Can be used
with Requires careful IJ26, IJ32 normally bent, and shape memory
balance of stresses straightens when alloys where the to ensure
that the energized. austenic phase is quiescent bend is planar
accurate Double The actuator bends in One actuator can Difficult to
make IJ36, IJ37, IJ38 bend one direction when be used to power the
drops ejected by one element is two nozzles. both bend directions
energized, and bends Reduced chip identical. the other way when
size. A small another element is Not sensitive to efficiency loss
energized. ambient temperature compared to equivalent single bend
actuators. Shear Energizing the Can increase the Not readily 1985
Fishbeck actuator causes a shear effective travel of applicable to
other U.S. Pat. 4,584,590 motion in the actuator piezoelectric
actuator material, actuators mechanisms Radial con- The actuator
squeezes Relatively easy High force 1970 Zoltan striction an ink
reservoir, to fabricate single required U.S. Pat. No. forcing ink
from a nozzles from glass Inefficient 3,683,212 constricted nozzle.
tubing as Difficult to macroscopic integrate with VLSI structures
processes Coil/uncoil A coiled actuator Easy to fabricate Difficult
to IJ17, IJ21, IJ34, uncoils or coils more as a planar VLSI
fabricate for non- IJ35 tightly. The motion of process planar
devices the free end of the Small area Poor out-of-plane actuator
ejects the ink, required, therefore stiffness low cost Bow The
actuator bows (or Can increase the Maximum travel IJ16, IJ18, IJ27
buckles) in the middle speed of travel is constrained when
energized. Mechanically High force rigid required Push-Pull Two
actuators control The structure is Not readily IJ18 a shutter. One
actuator pinned at both ends, suitable for ink jets pulls the
shutter, and so has a high out-of- which directly push the other
pushes it. plane rigidity the ink Curl A set of actuators curl Good
fluid flow Design IJ20, IJ42 inwards inwards to reduce the to the
region behind complexity volume of ink that the actuator they
enclose. increases efficiency Curl A set of actuators curl
Relatively simple Relatively large IJ43 outwards outwards,
pressurizing construction chip area ink in a chamber surrounding
the actuators, and expelling ink from a nozzle in the chamber. Iris
Multiple vanes enclose High efficiency High fabrication IJ22 a
volume of ink. These Small chip area complexity simultaneously
rotate, Not suitable for reducing the volume pigmented inks between
the vanes.
Acoustic The actuator vibrates The actuator can Large area 1993
Hadimioglu vibration at a high frequency. be physically distant
required for et al, EUP 550,192 from the ink efficient operation
1993 Elrod et al, at useful frequencies EUP 572,220 Acoustic
coupling and crosstalk Complex drive circuitry Poor control of drop
volume and position None In various ink jet No moving parts Various
other Silverbrook, EP designs the actuator tradeoffs are 0771 658
A2 and does not move. required to related patent eliminate moving
applications parts Tone-jet NOZZLE REFILL METHOD Surface This is
the normal way Fabrication Low speed Thermal ink jet tension that
ink jets are simplicity Surface tension Piezoelectric ink refilled.
After the Operational force relatively jet actuator is energized,
simplicity small compared to IJ01-IJ07, IJ10- it typically returns
actuator force IJ14, IJ16, IJ20, rapidly to its normal Long refill
time IJ22-1145 position. This rapid usually dominates return sucks
in air the total repetition through the nozzle rate opening. The
ink surface tension at the nozzle then exerts a small force
restoring the meniscus to a minimum area. This force refills the
nozzle. Shuttered Ink to the nozzle High speed Requires IJ08, IJ13,
IJ15, oscillating chamber is provided at Low actuator common ink
IJ17, IJ18, IJ19, ink pressure a pressure that energy, as the
pressure oscillator IJ21 oscillates at twice the actuator need only
May not be drop ejection open or close the suitable for frequency.
When a shutter, instead of pigmented inks drop is to be ejected,
ejecting the ink drop the shutter is opened for 3 half cycles: drop
ejection, actuator return, and refill. The shutter is then closed
to prevent the nozzle chamber emptying during the next negative
pressure cycle. Refill After the main High speed, as Requires two
IJ09 actuator actuator has ejected a the nozzle is independent drop
a second (refill) actively refilled actuators per nozzle actuator
is energized. The refill actuator pushes ink into the nozzle
chamber. The refill actuator returns slowly, to prevent its return
from emptying the chamber again. Positive ink The ink is held a
slight High refill rate, Surface spill Silverbrook, EP pressure
positive pressure. therefore a high must be prevented 0771 658 A2
and After the ink drop is drop repetition rate Highly related
patent ejected, the nozzle is possible hydrophobic print
applications chamber fills quickly head surfaces are Alternative
for:, as surface tension and required IJ01-IJ07, IJ10-IJ14, ink
pressure both IJ16, IJ20, IJ22-IJ45 operate to refill the nozzle.
METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Long inlet The ink
inlet channel Design simplicity Restricts refill Thermal ink jet
channel to the nozzle chamber Operational rate Piezoelectric ink is
made long and simplicity May result in a jet relatively narrow,
Reduces relatively large chip IJ42, IJ43 relying on viscous
crosstalk area drag to reduce inlet Only partially back-flow,
effective Positive ink The ink is under a Drop selection Requires a
Silverbrook, EP pressure positive pressure, so and separation
method (such as a 0771 658 A2 and that in the quiescent forces can
be nozzle rim or related patent state some of the ink reduced
effective applications drop already protrudes Fast refill time
hydrophobizing, or Possible from the nozzle. both) to prevent
operation of the This reduces the flooding of the following: IJ01-
pressure in the nozzle ejection surface of IJ07, IJ09-IJ12, chamber
which is the print head. IJ14, IJ16, IJ20, required to eject a
IJ22, IJ23-IJ34, certain volume of ink. IJ36-IJ41, IJ44 The
reduction in chamber pressure results in a reduction in ink pushed
out through the inlet. Baffle One or more baffles The refill rate
is Design HP Thermal Ink are placed in the inlet not as restricted
as complexity Jet ink flow. When the the long inlet May increase
Tektronix actuator is energized, method. fabrication piezoelectric
ink jet the rapid ink Reduces complexity (e.g. movement creates
crosstalk Tektronix hot melt eddies which restrict Piezoelectric
print the flow through the heads). inlet. The slower refill process
is unrestricted, and does not result in eddies. Flexible flap In
this method recently Significantly Not applicable to Canon
restricts disclosed by Canon, reduces back-flow most ink jet inlet
the expanding actuator for edge-shooter configurations (bubble)
pushes on a thermal ink jet Increased flexible flap that devices
fabrication restricts the inlet, complexity Inelastic deformation
of polymer flap results in creep over extended use NOZZLE CLEARING
METHOD Normal All of the nozzles are No added May not be Most ink
jet nozzle firing fired periodically, complexity on the sufficient
to systems before the ink has a print head displace dried ink IJ01,
IJ02, IJ03, chance to dry. When IJ04, IJ05, IJ06, not in use the
nozzles IJ07, IJ09, IJ10, are sealed (capped) IJ11, IJ12, IJ14,
against air. IJ16, IJ20, IJ22, The nozzle firing is IJ23, IJ24,
IJ25, usually performed IJ26, IJ27, IJ28, during a special IJ29,
IJ30, IJ31, clearing cycle, after IJ32, IJ33, IJ34, first moving
the print IJ36, IJ37, IJ38, head to a cleaning IJ39, IJ40, IJ41,
station. IJ42, IJ43, IJ44, IJ45 Extra In systems which heat Can be
highly Requires higher Silverbrook, EP power to the ink, but do not
boil effective if the drive voltage for 0771 658 A2 and ink heater
it under normal heater is adjacent to clearing related patent
situations, nozzle the nozzle May require applications clearing can
be larger drive achieved by over- transistors powering the heater
and boiling ink at the nozzle. Rapid The actuator is fired in Does
not require Effectiveness May be used success-ion rapid succession.
In extra drive circuits depends with: IJ01, IJ02, of actuator some
configurations, on the print head substantially upon IJ03, IJ04,
IJ05, pulses this may cause heat Can be readily the configuration
of IJ06, IJ07, IJ09, build-up at the nozzle controlled and the ink
jet nozzle IJ10, IJ11, IJ14, which boils the ink, initiated by
digital IJ16, IJ20, IJ22, clearing the nozzle. In logic IJ23, IJ24,
IJ25, other situations, it may IJ27, IJ28, IJ29, cause sufficient
IJ30, IJ31, IJ32, vibrations to dislodge IJ33, IJ34, IJ36, clogged
nozzles. IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, 1IJ4, IJ45 Extra
Where an actuator is A simple Not suitable May be used power to not
normally driven to solution where where there is a with: IJ03,
IJ09, ink pushing the limit of its motion, applicable hard limit to
IJ16, IJ20, IJ23, actuator nozzle clearing may be actuator movement
IJ24, IJ25, IJ27, assisted by providing IJ29, IJ30, IJ31, an
enhanced drive IJ32, IJ39, IJ40, signal to the actuator. IJ41,
IJ42, IJ43, IJ44, IJ45 Acoustic An ultrasonic wave is A high nozzle
High IJ08, IJ13, IJ15, resonance applied to the ink clearing
capability implementation cost I117, IJ18, IJ19, chamber. This wave
is can be achieved if system does not IJ21 of an appropriate May be
already include an amplitude and implemented at very acoustic
actuator frequency to cause low cost in systems sufficient force at
the which already nozzle to clear include acoustic blockages. This
is actuators easiest to achieve if the ultrasonic wave is at a
resonant frequency of the ink cavity. Nozzle A microfabricated Can
clear Accurate Silverbrook, EP clearing plate is pushed against
severely clogged mechanical 0771 658 A2 and plate the nozzles. The
plate nozzles alignment is related patent has a post for every
required applications nozzle. A post moves Moving parts are through
each nozzle, required displacing dried ink. There is risk of damage
to the nozzles Accurate fabrication is required Ink The pressure of
the ink May be effective Requires May be used pressure is
temporarily where other pressure pump or with all IJ senes ink
pulse increased so that ink methods cannot be other pressure jets
streams from all of the used actuator nozzles. This maybe Expensive
used in conjunction Wasteful of ink with actuator energizing. Print
head A flexible `blade` is Effective for Difficult to use if Many
ink jet wiper wiped across the print planar print head print head
surface is systems head surface. The surfaces non-planar or very
blade is usually Low cost fragile fabricated from a Requires
flexible polymer, e.g. mechanical parts rubber or synthetic Blade
can wear elastomer. out in high volume print systems Separate A
separate heater is Can be effective Fabrication Can be used with
ink boiling provided at the nozzle where other nozzle complexity
many IJ series ink heater although the normal clearing methods jets
drop e-ection cannot be used mechanism does not Can be require it.
The heaters implemented at no do not require additional cost in
individual drive some ink jet circuits, as many configurations
nozzles can be cleared simultaneously, and no imaging is required.
NOZZLE PLATE CONSTRUCTION Electro- A nozzle plate is Fabrication
High Hewlett Packard formed separately fabricated simplicity
temperatures and Thermal Ink jet nickel from electroformed
pressures are nickel, and bonded to required to bond the print head
chip. nozzle plate Minimum thickness constraints Differential
thermal expansion Laser Individual nozzle No masks Each hole must
Canon Bubblejet ablated or holes are ablated by an required be
individually 1988 Sercel et drilled intense UV laser in a Can be
quite fast formed al., SPIE, Vol. 998 polymer nozzle plate, which
is Some control Special Excimer Beam typically a polymer over
nozzle profile equipment required Applications, pp. such as
polyimide or is possible Slow where there 76-83 polysulphone
Equipment are many thousands 1993 Watanabe required is relatively
of nozzles per print et al., U.S. Pat. No. low cost head 5,208,604
May produce thin burrs at exit holes Silicon A separate nozzle High
accuracy is Two part K. Bean, IEEE micro- plate is attainable
construction Transactions on machined micromachined from High cost
Electron Devices, single crystal silicon, Requires Vol. ED-25, No.
10, and bonded to the precision alignment 1978, pp 1185-1195 print
head wafer. Nozzles may be Xerox 1990 clogged by adhesive Hawkins
et al., U.S. Pat. No. 4,899,181 Glass Fine glass capillaries No
expensive Very small 1970 Zoltan U.S. Pat. capillaries are drawn
from glass equipment required nozzle sizes are 3,683,212 tubing.
This method Simple to make difficult to form has been used for
single nozzles Not suited for making individual mass production
nozzles, but is difficult to use for bulk manufacturing of print
heads with thousands of nozzles. Monolithic, The nozzle plate is
High accuracy Requires Silverbrook, EP surface deposited as a layer
(<1 .mu.m) sacrificial layer 0771 658 A2 and micro- using
standard VLSI Monolithic under the nozzle related patent machined
deposition techniques. Low cost plate to form the applications
using VLSI Nozzles are etched in Existing nozzle chamber IJ01,
IJ02, IJ04, litho- the nozzle plate using processes can be Surface
may be IJ11, IJ12, IJ17, graphic VLSI lithography and used fragile
to the touch IJ18, IJ20, IJ22, processes etching. IJ24, IJ27, IJ28,
IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40,
IJ41, IJ42, IJ43, IJ44 Monolithic, The nozzle plate is a High
accuracy Requires long IJ03, IJ05, IJ06, etched buried etch stop in
the (<1 .mu.m) etch times IJ07, IJ08, IJ09, through wafer.
Nozzle Monolithic Requires a IJ10, IJ13, IJ14, substrate chambers
are etched in Low cost support wafer IJ15, IJ16, IJ19, the front of
the wafer, No differential IJ21, IJ23, IJ25, and the wafer is
expansion IJ26 thinned from the back side. Nozzles are then etched
in the etch stop layer. No nozzle Various methods have No nozzles
to Difficult to Ricoh 1995 plate been tried to eliminate become
clogged control drop Sekiya et al U.S. Pat. the nozzles entirely,
to position accurately No. 5,412,413 prevent nozzle Crosstalk 1993
Hadimioglu clogging. These problems et al EUP 550,192 include
thermal bubble 1993 Elrod et al mechanisms and EUP 572,220 acoustic
lens mechanisms Trough Each drop ejector has Reduced Drop firing
IJ135 a trough through manufacturing direction is sensitive which a
paddle moves, complexity to wicking. There is no nozzle Monolithic
plate. Nozzle slit The elimination of No nozzles to Difficult to
1989 Saito et al instead of nozzle holes and become clogged control
drop U.S. Pat. 4,799,068 individual replacement by a slit position
accurately nozzles encompassing many Crosstalk actuator positions
problems reduces nozzle clogging, but increases crosstalk due to
ink surface waves DROP EJECTION DIRECTION Edge Ink flow is along
the Simple Nozzles limited Canon Bubblejet (`edge surface of the
chip, construction to edge 1979 Endo et al GB shooter`) and ink
drops are No silicon High resolution patent 2,007,162 ejected from
the chip etching required is difficult Xerox heater-in- edge. Good
heat Fast color pit 1990 Hawkins et sinking via substrate printing
requires al U.S. Pat. 4,899,181 Mechanically one print head per
Tone-jet strong color Ease of chip handing Surface Ink flow is
along the No bulk silicon Maximum ink Hewlett-Packard (`roof
surface of the chip, etching required flow is severely TIJ 1982
Vaught et shooter`) and ink drops are Silicon can make restricted
al U.S. Pat. 4,490,728 ejected from the chip an effective heat
IJ02, IJ11, IJ12, surface, normal to the sink IJ20, IJ22 plane of
the chip. Mechanical strength Through Ink flow is through the High
ink flow Requires bulk Silverbrook, EP chip, chip, and ink drops
are Suitable for silicon etching 0771 658 A2 and forward ejected
from the front pagewidth print related patent (`up surface of the
chip, heads applications shooter`) High nozzle IJ04, IJ17, IJ18,
packing density IJ24, IJ27-1145 therefore low manufacturing cost
Through Ink flow is through the High ink flow Requires wafer IJ01,
IJ03, IJ05, chip, chip, and ink drops are Suitable for thinning
IJ06, IJ07, IJ08, reverse ejected from the rear pagewidth print
Requires special IJ09, IJ10, IJ13, (`down surface of the chip.
heads handling during IJ14, IJ15, IJ16, shooter`) High nozzle
manufacture IJ19, IJ21, IJ23, packing density IJ25, IJ26 therefore
low manufacturing cost Through Ink flow is through the Suitable for
Pagewidth print Epson Stylus actuator actuator, which is not
piezoelectric print heads require Tektronix hot fabricated as part
of heads several thousand melt piezoelectric the same substrate as
connections to drive ink jets the drive transistors. circuits
Cannot be manufactured in standard CMOS fabs Complex assembly
required INK TYPE Aqueous, Water based ink which Environmentally
Slow drying Most existing ink dye typically contains: friendly
Corrosive jets water, dye, surfactant, No odor Bleeds on paper All
IJ series ink humectant, and May jets biocide. strikethrough
Silverbrook, EP Modern ink dyes have
Cockles paper 0771 658 A2 and high water-fastness, related patent
light fastness applications Aqueous, Water based ink which
Environmentally Slow drying IJ02, IJ04, IJ21, pigment typically
contains: friendly Corrosive IJ26, IJ27, IJ30 water, pigment, No
odor Pigment may Silverbrook, EP surfactant, humectant, Reduced
bleed clog nozzles 0771 658 A2 and and biocide. Reduced wicking
Pigment may related patent Pigments have an Reduced clog actuator
applications advantage in reduced strikethrough mechanisms
Piezoelectric ink- bleed, wicking and Cockles paper jets
strikethrough. Thermal ink jets (with significant restrictions)
Methyl MEK is a highly Very fast drying Odorous All IJ series ink
Ethyl volatile solvent used Prints on various Flammable jets Ketone
for industrial printing substrates such as (MEK) on difficult
surfaces metals and plastics such as aluminum cans. Alcohol Alcohol
based inks Fast drying Slight odor All IJ series ink (ethanol, 2-
can be used where the Operates at sub- Flammable jets butanol,
printer must operate at freezing and others) temperatures below
temperatures the freezing point of Reduced paper water. An example
of cockle this is in-camera Low cost consumer photographic
printing. Phase The ink is solid at No drying time- High viscosity
Tektronix hot change room temperature, and ink instantly freezes
Printed ink melt piezoelectric (hot melt) is melted in the print on
the print medium typically has a ink jets head before jetting.
Almost any print `waxy` feel 1989 Nowak Hot melt inks are medium
can be used Printed pages U.S. Pat. 4,820,346 usually wax based, No
paper cockle may `block` All IJ series ink with a melting point
occurs Ink temperature jets around 80.degree. C. After No wicking
maybe above the jetting the ink freezes occurs curie point of
almost instantly upon No bleed occurs permanent magnets contacting
the print No strikethrough Ink heaters medium or a transfer occurs
consume power roller. Long warm-up time Oil Oil based inks are High
solubility High viscosity: All IJ series ink extensively used in
medium for some this is a significant jets offset printing. They
dyes limitation for use in have advantages in Does not cockle ink
jets, which improved paper usually require a characteristics on
Does not wick low viscosity. Some paper (especially no through
paper short chain and wicking or cockle). multi-branched oils Oil
soluble dies and have a sufficiently pigments are required. low
viscosity. Slow drying Micro- A microemulsion is a Stops ink bleed
Viscosity higher All IJ series ink emulsion stable, self forming
High dye than water jets emulsion of oil, water, solubility Cost is
slightly and surfactant. The Water, oil, and higher than water
characteristic drop size amphiphilic soluble based ink is less than
100 nm, dies can be used High surfactant and is determined by Can
stabilize concentration the preferred curvature pigment required
(around of the surfactant. suspensions 5%)
* * * * *