U.S. patent application number 12/859206 was filed with the patent office on 2010-12-09 for ejection nozzle arrangement.
This patent application is currently assigned to Silverbrook Research Pty Ltd. Invention is credited to Kia Silverbrook.
Application Number | 20100309252 12/859206 |
Document ID | / |
Family ID | 46300479 |
Filed Date | 2010-12-09 |
United States Patent
Application |
20100309252 |
Kind Code |
A1 |
Silverbrook; Kia |
December 9, 2010 |
EJECTION NOZZLE ARRANGEMENT
Abstract
An ejection nozzle arrangement having a substrate, a fluid port
in the substrate, a chamber on the substrate so as to have the
fluid port therein, a roof on the chamber having an ejection port,
and an arm extending through an opening in the chamber into the
chamber for causing ejection of fluid within the chamber from the
ejection port. The arm is suspended within the opening so that the
arm is spaced from both the substrate and the chamber within the
opening.
Inventors: |
Silverbrook; Kia; (Balmain,
AU) |
Correspondence
Address: |
SILVERBROOK RESEARCH PTY LTD
393 DARLING STREET
BALMAIN
2041
AU
|
Assignee: |
Silverbrook Research Pty
Ltd
|
Family ID: |
46300479 |
Appl. No.: |
12/859206 |
Filed: |
August 18, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11490041 |
Jul 21, 2006 |
7802871 |
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12859206 |
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|
10728970 |
Dec 8, 2003 |
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11490041 |
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|
|
10160273 |
Jun 4, 2002 |
6746105 |
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10728970 |
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09112767 |
Jul 10, 1998 |
6416167 |
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|
10160273 |
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Current U.S.
Class: |
347/40 |
Current CPC
Class: |
H04N 2101/00 20130101;
B42D 2035/34 20130101; B41J 2/1643 20130101; B41J 2202/21 20130101;
G06K 1/121 20130101; B41J 2002/14435 20130101; H04N 1/2154
20130101; B82Y 30/00 20130101; B41J 2/1645 20130101; H04N 5/225
20130101; B41J 2/1623 20130101; B41J 2/1637 20130101; B41J 2/1648
20130101; B41J 2/16585 20130101; B41J 2002/041 20130101; B41J
2/1632 20130101; B41J 2/1646 20130101; B41J 2/17513 20130101; H04N
5/2628 20130101; B41J 2/1642 20130101; B41J 2002/14346 20130101;
B41J 2/1412 20130101; B41J 2/17503 20130101; B41J 2/1601 20130101;
B41J 2/1639 20130101; G06K 7/1417 20130101; G06F 21/79 20130101;
G06F 21/86 20130101; B41J 2/14427 20130101; B41J 2/17596 20130101;
G06K 19/06037 20130101; G11C 11/56 20130101; G06F 2221/2129
20130101; B41J 2/1631 20130101; B41J 2/1626 20130101; B41J 2/1629
20130101; B41J 2/1628 20130101; B41J 2/1635 20130101; G06F 1/1626
20130101; G06K 7/14 20130101 |
Class at
Publication: |
347/40 |
International
Class: |
B41J 2/145 20060101
B41J002/145 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 1997 |
AU |
PO7991 |
Mar 25, 1998 |
AU |
PP2592 |
Claims
1. An ejection nozzle arrangement comprising: a substrate; a
chamber on the substrate; a roof on the chamber having an ejection
port; and an arm extending through an opening in the chamber into
the chamber for causing ejection of fluid within the chamber from
the ejection port, the arm being suspended within the opening so
that the arm is spaced from both the substrate and the chamber
within the opening.
2. A nozzle arrangement according to claim 1, further comprising a
layer of passivation material on the substrate, the chamber being
arranged on the passivation layer.
3. A nozzle arrangement according to claim 2, wherein the
passivation material is silicone.
4. A nozzle arrangement according to claim 1, wherein the fluid is
ink.
5. A nozzle arrangement according to claim 4, wherein the nozzle
arrangement forms part of an inkjet printhead integrated
circuit.
6. A nozzle arrangement according to claim 1, wherein the arm
includes a heating circuit.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a Continuation of U.S.
application Ser. No. 11/490,041 filed Jul. 21, 2006, which is a
Continuation of U.S. application Ser. No. 10/728,970 (Now
Abandoned) filed on Dec. 8, 2003, which is a Continuation In Part
of U.S. application Ser. No. 10/160,273 filed on Jun. 4, 2002, now
issued as U.S. Pat. No. 6,746,105, which is a Continuation of U.S.
application Ser. No. 09/112,767 filed on Jul. 10, 1998, now issued
as U.S. Pat. No. 6,416,167 all of which is herein incorporated by
reference.
[0002] The following Australian provisional patent applications are
hereby incorporated by cross-reference. For the purposes of
location and identification, U.S. patent applications identified by
their U.S. patent application Ser. Nos. (USSN) are listed alongside
the Australian applications from which the U.S. patent applications
claim the right of priority.
TABLE-US-00001 CROSS-REFERENCED US PATENT/PATENT AUSTRALIAN
APPLICATION (CLAIMING PROVISIONAL RIGHT OF PRIORITY PATENT FROM
AUSTRALIAN DOCKET APPLICATION NO. PROVISIONAL APPLICATION) NO.
PO7991 6,750,901 ART01 PO8505 6,476,863 ART02 PO7988 6,788,336
ART03 PO9395 6,322,181 ART04 PO8017 6,597,817 ART06 PO8014
6,227,648 ART07 PO8025 6,727,948 ART08 PO8032 6,690,419 ART09
PO7999 6,727,951 ART10 PO8030 6,196,541 ART13 PO7997 6,195,150
ART15 PO7979 6,362,868 ART16 PO7978 6,831,681 ART18 PO7982
6,431,669 ART19 PO7989 6,362,869 ART20 PO8019 6,472,052 ART21
PO7980 6,356,715 ART22 PO8018 6,894,694 ART24 PO7938 6,636,216
ART25 PO8016 6,366,693 ART26 PO8024 6,329,990 ART27 PO7939
6,459,495 ART29 PO8501 6,137,500 ART30 PO8500 6,690,416 ART31
PO7987 7,050,143 ART32 PO8022 6,398,328 ART33 PO8497 7,110,024
ART34 PO8020 6,431,704 ART38 PO8504 6,879,341 ART42 PO8000
6,415,054 ART43 PO7934 6,665,454 ART45 PO7990 6,542,645 ART46
PO8499 6,486,886 ART47 PO8502 6,381,361 ART48 PO7981 6,317,192
ART50 PO7986 6,850,274 ART51 PO8026 6,646,757 ART53 PO8028
6,624,848 ART56 PO9394 6,357,135 ART57 PO9397 6,271,931 ART59
PO9398 6,353,772 ART60 PO9399 6,106,147 ART61 PO9400 6,665,008
ART62 PO9401 6,304,291 ART63 PO9403 6,305,770 ART65 PO9405
6,289,262 ART66 PP0959 6,315,200 ART68 PP1397 6,217,165 ART69
PP2370 6,786,420 DOT01 PO8003 6,350,023 Fluid01 PO8005 6,318,849
Fluid02 PO8066 6,227,652 IJ01 PO8072 6,213,588 IJ02 PO8040
6,213,589 IJ03 PO8071 6,231,163 IJ04 PO8047 6,247,795 IJ05 PO8035
6,394,581 IJ06 PO8044 6,244,691 IJ07 PO8063 6,257,704 IJ08 PO8057
6,416,168 IJ09 PO8056 6,220,694 IJ10 PO8069 6,257,705 IJ11 PO8049
6,247,794 IJ12 PO8036 6,234,610 IJ13 PO8048 6,247,793 IJ14 PO8070
6,264,306 IJ15 PO8067 6,241,342 IJ16 PO8001 6,247,792 IJ17 PO8038
6,264,307 IJ18 PO8033 6,254,220 IJ19 PO8002 6,234,611 IJ20 PO8068
6,302,528 IJ21 PO8062 6,283,582 IJ22 PO8034 6,239,821 IJ23 PO8039
6,338,547 IJ24 PO8041 6,247,796 IJ25 PO8004 6,557,977 IJ26 PO8037
6,390,603 IJ27 PO8043 6,362,843 IJ28 PO8042 6,293,653 IJ29 PO8064
6,312,107 IJ30 PO9389 6,227,653 IJ31 PO9391 6,234,609 IJ32 PP0888
6,238,040 IJ33 PP0891 6,188,415 IJ34 PP0890 6,227,654 IJ35 PP0873
6,209,989 IJ36 PP0993 6,247,791 IJ37 PP0890 6,336,710 IJ38 PP1398
6,217,153 IJ39 PP2592 6,416,167 IJ40 PP2593 6,243,113 IJ41 PP3991
6,283,581 IJ42 PP3987 6,247,790 IJ43 PP3985 6,260,953 IJ44 PP3983
6,267,469 IJ45 PO7935 6,224,780 IJM01 PO7936 6,235,212 IJM02 PO7937
6,280,643 IJM03 PO8061 6,284,147 IJM04 PO8054 6,214,244 IJM05
PO8065 6,071,750 IJM06 PO8055 6,267,905 IJM07 PO8053 6,251,298
IJM08 PO8078 6,258,285 IJM09 PO7933 6,225,138 IJM10 PO7950
6,241,904 IJM11 PO7949 6,299,786 IJM12 PO8060 6,866,789 IJM13
PO8059 6,231,773 IJM14 PO8073 6,190,931 IJM15 PO8076 6,248,249
IJM16 PO8075 6,290,862 IJM17 PO8079 6,241,906 IJM18 PO8050
6,565,762 IJM19 PO8052 6,241,905 IJM20 PO7948 6,451,216 IJM21
PO7951 6,231,772 IJM22 PO8074 6,274,056 IJM23 PO7941 6,290,861
IJM24 PO8077 6,248,248 IJM25 PO8058 6,306,671 IJM26 PO8051
6,331,258 IJM27 PO8045 6,110,754 IJM28 PO7952 6,294,101 IJM29
PO8046 6,416,679 IJM30 PO9390 6,264,849 IJM31 PO9392 6,254,793
IJM32 PP0889 6,235,211 IJM35 PP0887 6,491,833 IJM36 PP0882
6,264,850 IJM37 PP0874 6,258,284 IJM38 PP1396 6,312,615 IJM39
PP3989 6,228,668 IJM40 PP2591 6,180,427 IJM41 PP3990 6,171,875
IJM42 PP3986 6,267,904 IJM43 PP3984 6,245,247 IJM44 PP3982
6,315,914 IJM45 PP0895 6,231,148 IR01 PP0869 6,293,658 IR04 PP0887
6,614,560 IR05 PP0885 6,238,033 IR06 PP0884 6,312,070 IR10 PP0886
6,238,111 IR12 PP0877 6,378,970 IR16 PP0878 6,196,739 IR17 PP0883
6,270,182 IR19 PP0880 6,152,619 IR20 PO8006 6,087,638 MEMS02 PO8007
6,340,222 MEMS03 PO8010 6,041,600 MEMS05 PO8011 6,299,300 MEMS06
PO7947 6,067,797 MEMS07 PO7944 6,286,935 MEMS09 PO7946 6,044,646
MEMS10 PP0894 6,382,769 MEMS13
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0003] Not applicable.
FIELD OF THE INVENTION
[0004] The present invention relates to the field of inkjet
printers and, discloses an inkjet printing system using printheads
manufactured with microelectro-mechanical systems (MEMS)
techniques.
BACKGROUND OF THE INVENTION
[0005] 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.
[0006] 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.
[0007] 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).
[0008] Ink Jet printers themselves come in many different types.
The utilization of a continuous stream of 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
electro-static ink jet printing.
[0009] 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 electro-static field so
as to cause drop separation. This technique is still utilized by
several manufacturers including Elmjet and Scitex (see also U.S.
Pat. No. 3,373,437 by Sweet et al)
[0010] Piezoelectric ink jet printers are also one form of commonly
utilized ink jet printing device. Piezoelectric systems are
disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which
utilizes 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)
discloses a bend mode of piezoelectric operation, Howkins in U.S.
Pat. No. 4,459,601 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.
[0011] 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 disclosed ink jet printing techniques that 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
utilizing the electro-thermal actuator are manufactured by
manufacturers such as Canon and Hewlett Packard.
[0012] 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.
[0013] In the construction of any inkjet printing system, there are
a considerable number of important factors which must be traded off
against one another especially as large scale printheads are
constructed, especially those of a pagewidth type. A number of
these factors are outlined in the following paragraphs.
[0014] Firstly, inkjet printheads are normally constructed
utilizing micro-electromechanical systems (MEMS) techniques. As
such, they tend to rely upon standard integrated circuit
construction/fabrication techniques of depositing planar layers on
a silicon wafer and etching certain portions of the planar layers.
Within silicon circuit fabrication technology, certain techniques
are better known than others. For example, the techniques
associated with the creation of CMOS circuits are likely to be more
readily used than those associated with the creation of exotic
circuits including ferroelectrics, galium arsenide etc. Hence, it
is desirable, in any MEMS constructions, to utilize well proven
semi-conductor fabrication techniques which do not require any
"exotic" processes or materials. Of course, a certain degree of
trade off will be undertaken in that if the advantages of using the
exotic material far out weighs its disadvantages then it may become
desirable to utilize the material anyway. However, if it is
possible to achieve the same, or similar, properties using more
common materials, the problems of exotic materials can be
avoided.
[0015] With a large array of ink ejection nozzles, it is desirable
to provide for a highly automated form of manufacturing which
results in an inexpensive production of multiple printhead
devices.
[0016] Preferably, the device constructed utilizes a low amount of
energy in the ejection of ink. The utilization of a low amount of
energy is particularly important when a large pagewidth full color
printhead is constructed having a large array of individual print
ejection mechanism with each ejection mechanisms, in the worst
case, being fired in a rapid sequence.
SUMMARY OF THE INVENTION
[0017] It is an object of the present invention to provide an ink
ejection nozzle arrangement suitable for incorporation into an
inkjet printhead arrangement for the ejection of ink on demand from
a nozzle chamber in an efficient and reliable manner.
[0018] According to a first aspect, the present invention provides
an ink jet printhead comprising:
[0019] a plurality of nozzles;
[0020] a bubble forming chamber corresponding to each of the
nozzles respectively, the bubble forming chambers adapted to
contain a bubble forming liquid; and,
[0021] at least one heater element disposed in each of the bubble
forming chambers respectively, the heater elements configured for
thermal contact with the bubble forming liquid; such that,
[0022] heating the heater element to a temperature above the
boiling point of the bubble forming liquid forms a gas bubble that
causes the ejection of a drop of an ejectable liquid through the
nozzle corresponding to that heater element; wherein,
the bubble forming chamber is at least partially formed by an
amorphous ceramic material.
[0023] Amorphous ceramic material provides the bubble forming
chamber with high strength. The non-crystalline structure avoids
any points of weakness due to crystalline defects. These defects
can act as stress concentration areas and are prone to failure.
[0024] According to a second aspect, the present invention provides
a printer system which incorporates a printhead, the printhead
comprising:
[0025] a plurality of nozzles;
[0026] a bubble forming chamber corresponding to each of the
nozzles respectively, the bubble forming chambers adapted to
contain a bubble forming liquid; and,
[0027] at least one heater element disposed in each of the bubble
forming chambers respectively, the heater elements configured for
thermal contact with the bubble forming liquid; such that,
[0028] heating the heater element to a temperature above the
boiling point of the bubble forming liquid forms a gas bubble that
causes the ejection of a drop of an ejectable liquid through the
nozzle corresponding to that heater element; wherein,
[0029] the bubble forming chamber is at least partially formed by
an amorphous ceramic material.
[0030] According to a third aspect, the present invention provides
a method of ejecting drops of an ejectable liquid from a printhead,
the printhead comprising a plurality of nozzles;
a chamber corresponding to each of the nozzles respectively, the
chambers adapted to contain an ejectable liquid; and, at least one
droplet ejection actuator associated with each of the chambers
respectively; wherein, the chamber is at least partially formed by
an amorphous ceramic material; the method comprising the steps
of:
[0031] placing the ejectable liquid into contact with the drop
ejection actuator; and actuating the droplet ejection actuator such
that a droplet of an ejectable liquid is ejected through the
corresponding nozzle.
[0032] Preferably, the amorphous ceramic material is silicon
nitride. In another form, the amorphous ceramic material is silicon
dioxide. In yet another embodiment, the amorphous ceramic material
is silicon oxynitride.
[0033] Preferably, the thermal actuator units are interconnected at
a first end to a substrate and at a second end to a rigid strut
member. The rigid strut member can, in turn, be interconnected to
the arm having one end attached to the paddle vane. The thermal
actuator units can operate upon conductive heating along a
conductive trace and the conductive heating can include the
generation of a substantial portion of the heat in the area
adjacent the first end. The conductive heating trace can include a
thinned cross-section adjacent the first end. The heating layers of
the thermal actuator units can comprise substantially either a
copper nickel alloy or titanium nitride. The paddle can be
constructed from a similar conductive material to portions of the
thermal actuator units however it is conductively insulated
therefrom.
[0034] Preferably, the thermal actuator units are constructed from
multiple layers utilizing a single mask to etch the multiple
layers.
[0035] The nozzle chamber can include an actuator access port in a
second surface of the chamber. The access port can comprise a slot
in a corner of the chamber and the actuator is able to move in an
arc through the slot. The actuator can include an end portion that
mates substantially with a wall of the chamber at substantially
right angles to the paddle vane. The paddle vane can include a
depressed portion substantially opposite the fluid ejection
port.
[0036] In accordance with a further aspect of the present
invention, there is provided a thermal actuator including a series
of lever arms attached at one end to a substrate, the thermal
actuator being operational as a result of conductive heating of a
conductive trace, the conductive trace including a thinned
cross-section substantially adjacent the attachment to the
substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Notwithstanding any other forms that 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:
[0038] FIGS. 1-3 illustrate the basic operational principles of a
preferred embodiment using a thermal bend actuator;
[0039] FIG. 4 illustrates a three dimensional view of a single ink
jet nozzle arrangement constructed in accordance with the preferred
embodiment of FIG. 1;
[0040] FIG. 5 illustrates an array of the nozzle arrangements of
FIG. 4;
[0041] FIG. 6 shows a table to be used with reference to FIGS. 7 to
16;
[0042] FIGS. 7 to 16 show various stages in the manufacture of the
ink jet nozzle arrangement of FIG. 4;
[0043] FIG. 17 is a schematic cross-sectional view through an ink
chamber of a unit cell of a printhead according to an embodiment
using a bubble forming heater element;
[0044] FIG. 18 is a schematic cross-sectional view through the ink
chamber FIG. 17, at another stage of operation;
[0045] FIG. 19 is a schematic cross-sectional view through the ink
chamber FIG. 17, at yet another stage of operation;
[0046] FIG. 20 is a schematic cross-sectional view through the ink
chamber FIG. 17, at yet a further stage of operation; and
[0047] FIG. 21 is a diagrammatic cross-sectional view through a
unit cell of a printhead in accordance with an embodiment of the
invention showing the collapse of a vapor bubble.
[0048] FIG. 22 is a schematic, partially cut away, perspective view
of a further embodiment of a unit cell of a printhead.
[0049] FIG. 23 is a schematic, partially cut away, exploded
perspective view of the unit cell of FIG. 22.
[0050] FIG. 24 is a schematic, partially cut away, perspective view
of a further embodiment of a unit cell of a printhead.
[0051] FIG. 25 is a schematic, partially cut away, exploded
perspective view of the unit cell of FIG. 24.
[0052] FIG. 26 is a schematic, partially cut away, perspective view
of a further embodiment of a unit cell of a printhead.
[0053] FIG. 27 is a schematic, partially cut away, exploded
perspective view of the unit cell of FIG. 26.
[0054] FIG. 28 is a schematic, partially cut away, perspective view
of a further embodiment of a unit cell of a printhead.
[0055] FIG. 29 is a schematic, partially cut away, perspective view
of a further embodiment of a unit cell of a printhead.
[0056] FIG. 30 is a schematic, partially cut away, exploded
perspective view of the unit cell of FIG. 29.
[0057] FIGS. 31 to 41 are schematic perspective views of the unit
cell shown in FIGS. 29 and 30, at various successive stages in the
production process of the printhead.
[0058] FIGS. 42 and 43 show schematic, partially cut away,
schematic perspective views of two variations of the unit cell of
FIGS. 29 to 41.
[0059] FIG. 44 is a schematic, partially cut away, perspective view
of a further embodiment of a unit cell of a printhead.
[0060] FIG. 45 is a schematic, partially cut away, perspective view
of a further embodiment of a unit cell of a printhead.
DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS
Thermal Bend Actuator
[0061] In one preferred embodiment, there is provided a nozzle
arrangement having a nozzle chamber containing ink and a thermal
bend actuator connected to a paddle positioned within the chamber.
The thermal actuator device is actuated so as to eject ink from the
nozzle chamber. The preferred embodiment includes a particular
thermal bend actuator which includes a series of tapered portions
for providing conductive heating of a conductive trace. The
actuator is connected to the paddle via an arm received through a
slotted wall of the nozzle chamber. The actuator arm has a mating
shape so as to mate substantially with the surfaces of the slot in
the nozzle chamber wall.
[0062] Turning initially to FIGS. 1-3, there is provided schematic
illustrations of the basic operation of a nozzle arrangement of the
invention. A nozzle chamber 1 is provided filled with ink 2 by
means of an ink inlet channel 3 which can be etched through a wafer
substrate on which the nozzle chamber 1 rests. The nozzle chamber 1
further includes an ink ejection port 4 around which an ink
meniscus forms.
[0063] Inside the nozzle chamber 1 is a paddle type device 7 which
is interconnected to an actuator 8 through a slot in the wall of
the nozzle chamber 1. The actuator 8 includes a heater means eg. 9
located adjacent to an end portion of a post 10. The post 10 is
fixed to a substrate.
[0064] When it is desired to eject a drop from the nozzle chamber
1, as illustrated in FIG. 2, the heater means 9 is heated so as to
undergo thermal expansion. Preferably, the heater means 9 itself or
the other portions of the actuator 8 are built from materials
having a high bend efficiency where the bend efficiency is defined
as
bend efficiency = Young ' s Modulus .times. ( Coefficient of
thermal Expansion ) Density .times. Specific Heat Capacity
##EQU00001##
[0065] A suitable material for the heater elements is a copper
nickel alloy which can be formed so as to bend a glass
material.
[0066] The heater means 9 is ideally located adjacent the end
portion of the post 10 such that the effects of activation are
magnified at the paddle end 7 such that small thermal expansions
near the post 10 result in large movements of the paddle end.
[0067] The heater means 9 and consequential paddle movement causes
a general increase in pressure around the ink meniscus 5 which
expands, as illustrated in FIG. 2, in a rapid manner. The heater
current is pulsed and ink is ejected out of the port 4 in addition
to flowing in from the ink channel 3.
[0068] Subsequently, the paddle 7 is deactivated to again return to
its quiescent position. The deactivation causes a general reflow of
the ink into the nozzle chamber. The forward momentum of the ink
outside the nozzle rim and the corresponding backflow results in a
general necking and breaking off of the drop 12 which proceeds to
the print media. The collapsed meniscus 5 results in a general
sucking of ink into the nozzle chamber 2 via the ink flow channel
3. In time, the nozzle chamber 1 is refilled such that the position
in FIG. 1 is again reached and the nozzle chamber is subsequently
ready for the ejection of another drop of ink.
[0069] FIG. 4 illustrates a side perspective view of the nozzle
arrangement FIG. 5 illustrates sectional view through an array of
nozzle arrangement of FIG. 4. In these figures, the numbering of
elements previously introduced has been retained.
[0070] Firstly, the actuator 8 includes a series of tapered
actuator units e.g. 15 which comprise an upper glass portion
(amorphous silicon dioxide) 16 formed on top of a titanium nitride
layer 17. Alternatively a copper nickel alloy layer (hereinafter
called cupronickel) can be utilized which will have a higher bend
efficiency where bend efficiency is defined as:
bend efficiency = Young ' s Modulus .times. ( Coefficient of
thermal Expansion ) Density .times. Specific Heat Capacity
##EQU00002##
[0071] The titanium nitride layer 17 is in a tapered form and, as
such, resistive heating takes place near an end portion of the post
10. Adjacent titanium nitride/glass portions 15 are interconnected
at a block portion 19 which also provides a mechanical structural
support for the actuator 8.
[0072] The heater means 9 ideally includes a plurality of the
tapered actuator unit 15 which are elongate and spaced apart such
that, upon heating, the bending force exhibited along the axis of
the actuator 8 is maximized. Slots are defined between adjacent
tapered units 15 and allow for slight differential operation of
each actuator 8 with respect to adjacent actuators 8.
[0073] The block portion 19 is interconnected to an arm 20. The arm
20 is in turn connected to the paddle 7 inside the nozzle chamber 1
by means of a slot e.g. 22 formed in the side of the nozzle chamber
1. The slot 22 is designed generally to mate with the surfaces of
the arm 20 so as to minimize opportunities for the outflow of ink
around the arm 20. The ink is held generally within the nozzle
chamber 1 via surface tension effects around the slot 22.
[0074] When it is desired to actuate the arm 20, a conductive
current is passed through the titanium nitride layer 17 via vias
within the block portion 19 connecting to a lower CMOS layer 6
which provides the necessary power and control circuitry for the
nozzle arrangement. The conductive current results in heating of
the nitride layer 17 adjacent to the post 10 which results in a
general upward bending of the arm 20 and consequential ejection of
ink out of the nozzle 4. The ejected drop is printed on a page in
the usual manner for an inkjet printer as previously described.
[0075] An array of nozzle arrangements can be formed so as to
create a single printhead. For example, in FIG. 5 there is
illustrated a partly sectioned various array view which comprises
multiple ink ejection nozzle arrangements of FIG. 4 laid out in
interleaved lines so as to form a printhead array. Of course,
different types of arrays can be formulated including full color
arrays etc.
[0076] The construction of the printhead system described can
proceed utilizing standard MEMS techniques through suitable
modification of the steps as set out in U.S. Pat. No. 6,243,113
entitled "Image Creation Method and Apparatus (IJ 41)" to the
present applicant, the contents of which are fully incorporated by
cross reference.
[0077] Fabrication of the ink jet nozzle arrangement is indicated
in FIGS. 7 to 16. The preferred embodiment achieves a particular
balance between utilization of the standard semi-conductor
processing material such as titanium nitride and glass in a MEMS
process. The use of glass, or indeed any amorphous ceramic, to form
the chamber is particularly beneficial. The pressure transients
within the chamber can exert significant stresses on the chamber
wall. Amorphous ceramics are relatively inexpensive and high
strength, but also have a non-crystalline structure. Defects in a
crystal structure can act as stress concentration points that are
prone to failure in the cyclical loading environment of the nozzle
chambers.
[0078] Obviously the skilled person may make other choices of
materials and design features where the economics are justified.
For example, a copper nickel alloy of 50% copper and 50% nickel may
be more advantageously deployed as the conductive heating compound
as it is likely to have higher levels of bend efficiency. Also,
other design structures may be employed where it is not necessary
to provide for such a simple form of manufacture.
[0079] Bubble Forming Heater Element Actuator
[0080] The present invention is also applicable to printheads using
bubble forming heater elements. FIGS. 17 to 20 show a nozzle of
this type. While the fabrication of nozzles of this type is
described below, the nozzles, ejection actuators, associated drive
circuitry and ink supply passages is formed on and through a wafer
using lithographically masked etching techniques described in great
detail in U.S. Ser. No. 10/302,274. In the interests of brevity,
the disclosure of the '274 application is incorporated herein in it
entirety.
[0081] With reference to FIGS. 17 to 20, the unit cell 1 of a
printhead according to an embodiment of the invention comprises a
nozzle plate 2 with nozzles 3 therein, the nozzles having nozzle
rims 4, and apertures 5 extending through the nozzle plate. The
nozzle plate 2 is plasma etched from a silicon nitride structure
which is deposited, by way of chemical vapor deposition (CVD), over
a sacrificial material which is subsequently etched.
[0082] The printhead also includes, with respect to each nozzle 3,
side walls 6 on which the nozzle plate is supported, a chamber 7
defined by the walls and the nozzle plate 2, a multi-layer
substrate 8 and an inlet passage 9 extending through the
multi-layer substrate to the far side (not shown) of the substrate.
A looped, elongate heater element 10 is suspended within the
chamber 7, so that the element is in the form of a suspended beam.
The printhead as shown is a microelectromechanical system (MEMS)
structure, which is formed by a lithographic process which is
described in more detail below.
[0083] When the printhead is in use, ink 11 from a reservoir (not
shown) enters the chamber 7 via the inlet passage 9, so that the
chamber fills to the level as shown in FIG. 17. Thereafter, the
heater element 10 is heated for somewhat less than 1 microsecond,
so that the heating is in the form of a thermal pulse. It will be
appreciated that the heater element 10 is in thermal contact with
the ink 11 in the chamber 7 so that when the element is heated,
this causes the generation of vapor bubbles 12 in the ink.
Accordingly, the ink 11 constitutes a bubble forming liquid. FIG.
17 shows the formation of a bubble 12 approximately 1 microsecond
after generation of the thermal pulse, that is, when the bubble has
just nucleated on the heater elements 10. It will be appreciated
that, as the heat is applied in the form of a pulse, all the energy
necessary to generate the bubble 12 is to be supplied within that
short time.
[0084] When the element 10 is heated as described above, the bubble
12 forms along the length of the element, this bubble appearing, in
the cross-sectional view of FIG. 17, as four bubble portions, one
for each of the element portions shown in cross section.
[0085] The bubble 12, once generated, causes an increase in
pressure within the chamber 7, which in turn causes the ejection of
a drop 16 of the ink 11 through the nozzle 3. The rim 4 assists in
directing the drop 16 as it is ejected, so as to minimize the
chance of drop misdirection.
[0086] The reason that there is only one nozzle 3 and chamber 7 per
inlet passage 9 is so that the pressure wave generated within the
chamber, on heating of the element 10 and forming of a bubble 12,
does not affect adjacent chambers and their corresponding nozzles.
As discussed above in relation to the previous embodiment, the
pressure wave generated within the chamber creates significant
stresses in the chamber wall. Forming the chamber from an amorphous
ceramic such as silicon nitride, silicon dioxide (glass) or silicon
oxynitride, gives the chamber walls high strength while avoiding
the use of material with a crystal structure. Crystalline defects
can act as stress concentration points and therefore potential
areas of weakness and ultimately failure.
[0087] FIGS. 18 and 19 show the unit cell 1 at two successive later
stages of operation of the printhead. It can be seen that the
bubble 12 generates further, and hence grows, with the resultant
advancement of ink 11 through the nozzle 3. The shape of the bubble
12 as it grows, as shown in FIG. 3, is determined by a combination
of the inertial dynamics and the surface tension of the ink 11. The
surface tension tends to minimize the surface area of the bubble 12
so that, by the time a certain amount of liquid has evaporated, the
bubble is essentially disk-shaped.
[0088] The increase in pressure within the chamber 7 not only
pushes ink 11 out through the nozzle 3, but also pushes some ink
back through the inlet passage 9. However, the inlet passage 9 is
approximately 200 to 300 microns in length, and is only
approximately 16 microns in diameter.
[0089] Hence there is a substantial viscous drag. As a result, the
predominant effect of the pressure rise in the chamber 7 is to
force ink out through the nozzle 3 as an ejected drop 16, rather
than back through the inlet passage 9.
[0090] Turning now to FIG. 20, the printhead is shown at a still
further successive stage of operation, in which the ink drop 16
that is being ejected is shown during its "necking phase" before
the drop breaks off. At this stage, the bubble 12 has already
reached its maximum size and has then begun to collapse towards the
point of collapse 17, as reflected in more detail in FIG. 21.
[0091] The collapsing of the bubble 12 towards the point of
collapse 17 causes some ink 11 to be drawn from within the nozzle 3
(from the sides 18 of the drop), and some to be drawn from the
inlet passage 9, towards the point of collapse. Most of the ink 11
drawn in this manner is drawn from the nozzle 3, forming an annular
neck 19 at the base of the drop 16 prior to its breaking off.
[0092] The drop 16 requires a certain amount of momentum to
overcome surface tension forces, in order to break off. As ink 11
is drawn from the nozzle 3 by the collapse of the bubble 12, the
diameter of the neck 19 reduces thereby reducing the amount of
total surface tension holding the drop, so that the momentum of the
drop as it is ejected out of the nozzle is sufficient to allow the
drop to break off.
[0093] When the drop 16 breaks off, cavitation forces are caused as
reflected by the arrows 20, as the bubble 12 collapses to the point
of collapse 17. It will be noted that there are no solid surfaces
in the vicinity of the point of collapse 17 on which the cavitation
can have an effect.
Features and Advantages of Further Embodiments
[0094] FIGS. 22 to 45 show further embodiments of unit cells 1 for
thermal inkjet printheads, each embodiment having its own
particular functional advantages. These advantages will be
discussed in detail below, with reference to each individual
embodiment. However, the basic construction of each embodiment is
best shown in FIGS. 23, 25, 27 and 30. The manufacturing process is
substantially the same as that described above in relation to FIGS.
6 to 31 of the above referenced U.S. Ser. No. 10/302,274
(incorporated herein by cross reference). For consistency, the same
reference numerals are used in FIGS. 22 to 45 to indicate
corresponding components. In the interests of brevity, the
fabrication stages have been shown for the unit cell of FIG. 29
only (see FIGS. 31 to 41). It will be appreciated that the other
unit cells will use the same fabrication stages with different
masking. Again, the deposition of successive layers shown in FIGS.
31 to 41 need not be described in detail below given that the
lithographic process largely corresponds to that shown in FIGS. 6
to 31 in U.S. Ser. No. 10/302,274.
[0095] Referring to FIGS. 22 and 23, the unit cell 1 shown has the
chamber 7, ink supply passage 32 and the nozzle rim 4 positioned
mid way along the length of the unit cell 1. As best seen in FIG.
23, the drive circuitry is partially on one side of the chamber 7
with the remainder on the opposing side of the chamber. The drive
circuitry 22 controls the operation of the heater 14 through vias
in the integrated circuit metallisation layers of the interconnect
23. The interconnect 23 has a raised metal layer on its top
surface. Passivation layer 24 is formed in top of the interconnect
23 but leaves areas of the raised metal layer exposed. Electrodes
15 of the heater 14 contact the exposed metal areas to supply power
to the element 10.
[0096] Alternatively, the drive circuitry 22 for one unit cell is
not on opposing sides of the heater element that it controls. All
the drive circuitry 22 for the heater 14 of one unit cell is in a
single, undivided area that is offset from the heater. That is, the
drive circuitry 22 is partially overlaid by one of the electrodes
15 of the heater 14 that it is controlling, and partially overlaid
by one or more of the heater electrodes 15 from adjacent unit
cells. In this situation, the center of the drive circuitry 22 is
less than 200 microns from the center of the associate nozzle
aperture 5. In most Memjet printheads of this type, the offset is
less than 100 microns and in many cases less than 50 microns,
preferably less than 30 microns.
[0097] Configuring the nozzle components so that there is
significant overlap between the electrodes and the drive circuitry
provides a compact design with high nozzle density (nozzles per
unit area of the nozzle plate 2). This also improves the efficiency
of the printhead by shortening the length of the conductors from
the circuitry to the electrodes. The shorter conductors have less
resistance and therefore dissipate less energy.
[0098] The high degree of overlap between the electrodes 15 and the
drive circuitry 22 also allows more vias between the heater
material and the CMOS metalization layers of the interconnect 23.
As best shown in FIGS. 30 and 31, the passivation layer 24 has an
array of vias to establish an electrical connection with the heater
14. More vias lowers the resistance between the heater electrodes
15 and the interconnect layer 23 which reduces power losses.
[0099] In FIGS. 24 and 25, the unit cell 1 is the same as that of
FIGS. 22 and 23 apart from the heater element 10. The heater
element 10 has a bubble nucleation section 158 with a smaller cross
section than the remainder of the element. The bubble nucleation
section 158 has a greater resistance and heats to a temperature
above the boiling point of the ink before the remainder of the
element 10. The gas bubble nucleates at this region and
subsequently grows to surround the rest of the element 10. By
controlling the bubble nucleation and growth, the trajectory of the
ejected drop is more predictable.
[0100] The heater element 10 is configured to accommodate thermal
expansion in a specific manner. As heater elements expand, they
will deform to relieve the strain. Elements such as that shown in
FIGS. 22 and 23 will bow out of the plane of lamination because its
thickness is the thinnest cross sectional dimension and therefore
has the least bending resistance. Repeated bending of the element
can lead to the formation of cracks, especially at sharp corners,
which can ultimately lead to failure. The heater element 10 shown
in FIGS. 24 and 25 is configured so that the thermal expansion is
relieved by rotation of the bubble nucleation section 158, and
slightly splaying the sections leading to the electrodes 15, in
preference to bowing out of the plane of lamination. The geometry
of the element is such that miniscule bending within the plane of
lamination is sufficient to relieve the strain of thermal
expansion, and such bending occurs in preference to bowing. This
gives the heater element greater longevity and reliability by
minimizing bend regions, which are prone to oxidation and
cracking.
[0101] Referring to FIGS. 26 and 27, the heater element 10 used in
this unit cell 1 has a serpentine or `double omega` shape. This
configuration keeps the gas bubble centered on the axis of the
nozzle. A single omega is a simple geometric shape which is
beneficial from a fabrication perspective. However the gap 159
between the ends of the heater element means that the heating of
the ink in the chamber is slightly asymmetrical. As a result, the
gas bubble is slightly skewed to the side opposite the gap 159.
This can in turn affect the trajectory of the ejected drop. The
double omega shape provides the heater element with the gap 160 to
compensate for the gap 159 so that the symmetry and position of the
bubble within the chamber is better controlled and the ejected drop
trajectory is more reliable.
[0102] FIG. 28 shows a heater element 10 with a single omega shape.
As discussed above, the simplicity of this shape has significant
advantages during lithographic fabrication. It can be a single
current path that is relatively wide and therefore less affected by
any inherent inaccuracies in the deposition of the heater material.
The inherent inaccuracies of the equipment used to deposit the
heater material result in variations in the dimensions of the
element. However, these tolerances are fixed values so the
resulting variations in the dimensions of a relatively wide
component are proportionally less than the variations for a thinner
component. It will be appreciated that proportionally large changes
of components dimensions will have a greater effect on their
intended function. Therefore the performance characteristics of a
relatively wide heater element are more reliable than a thinner
one.
[0103] The omega shape directs current flow around the axis of the
nozzle aperture 5. This gives good bubble alignment with the
aperture for better ejection of drops while ensuring that the
bubble collapse point is not on the heater element 10. As discussed
above, this avoids problems caused by cavitation.
[0104] Referring to FIGS. 29 to 42, another embodiment of the unit
cell 1 is shown together with several stages of the etching and
deposition fabrication process. In this embodiment, the heater
element 10 is suspended from opposing sides of the chamber. This
allows it to be symmetrical about two planes that intersect along
the axis of the nozzle aperture 5. This configuration provides a
drop trajectory along the axis of the nozzle aperture 5 while
avoiding the cavitation problems discussed above. FIGS. 43 and 44
show other variations of this type of heater element 10.
[0105] FIG. 44 shows a unit cell 1 that has the nozzle aperture 5
and the heater element 10 offset from the center of the nozzle
chamber 7. Consequently, the nozzle chamber 7 is larger than the
previous embodiments. The heater 14 has two different electrodes 15
with the right hand electrode 15 extending well into the nozzle
chamber 7 to support one side of the heater element 10. This
reduces the area of the vias contacting the electrodes which can
increase the electrode resistance and therefore the power losses.
However, laterally offsetting the heater element from the ink inlet
31 increases the fluidic drag retarding flow back through the inlet
31 and ink supply passage 32. The fluidic drag through the nozzle
aperture 5 comparatively much smaller so little energy is lost to a
reverse flow of ink through the inlet when a gas bubble form on the
element 10.
[0106] The unit cell 1 shown in FIG. 45 also has a relatively large
chamber 7 which again reduces the surface area of the electrodes in
contact with the vias leading to the interconnect layer 23.
However, the larger chamber 7 allows several heater elements 10
offset from the nozzle aperture 5. The arrangement shown uses two
heater elements 10; one on either side of the chamber 7. Other
designs use three or more elements in the chamber. Gas bubbles
nucleate from opposing sides of the nozzle aperture and converge to
form a single bubble. The bubble formed is symmetrical about at
least one plane extending along the nozzle axis. This enhances the
control of the symmetry and position of the bubble within the
chamber 7 and therefore the ejected drop trajectory is more
reliable.
Other Embodiments
[0107] The invention has been described above with reference to
printheads using thermal bend actuators and bubble forming heater
elements. However, it is potentially suited to a wide range of
printing system including: color 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 color and monochrome printers, color and
monochrome copiers, color and monochrome facsimile machines,
combined printer, facsimile and copying machines, label printers,
large format plotters, photograph copiers, printers for digital
photographic "minilabs", video printers, PHOTO CD (PHOTO CD is a
registered trade mark of the Eastman Kodak Company) printers,
portable printers for PDAs, wallpaper printers, indoor sign
printers, billboard printers, fabric printers, camera printers and
fault tolerant commercial printer arrays.
[0108] It will be appreciated by ordinary workers in this field
that numerous variations and/or modifications may be made to the
present invention as shown in the specific embodiments without
departing from the spirit or scope of the invention as broadly
described. The present embodiments are, therefore, to be considered
in all respects to be illustrative and not restrictive.
Ink Jet Technologies
[0109] 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.
[0110] 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.
In conventional thermal inkjet printheads, this leads to an
efficiency of around 0.02%, from electricity input to drop momentum
(and increased surface area) out.
[0111] 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.
[0112] 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:
[0113] low power (less than 10 Watts)
[0114] high resolution capability (1,600 dpi or more)
[0115] photographic quality output
[0116] low manufacturing cost
[0117] small size (pagewidth times minimum cross section)
[0118] high speed (<2 seconds per page).
[0119] 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.
[0120] 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.
[0121] 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.
[0122] 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.
Tables of Drop-On-Demand Ink Jets
[0123] 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.
[0124] The following tables form the axes of an eleven dimensional
table of ink jet types.
[0125] Actuator mechanism (18 types)
[0126] Basic operation mode (7 types)
[0127] Auxiliary mechanism (8 types)
[0128] Actuator amplification or modification method (17 types)
[0129] Actuator motion (19 types)
[0130] Nozzle refill method (4 types)
[0131] Method of restricting back-flow through inlet (10 types)
[0132] Nozzle clearing method (9 types)
[0133] Nozzle plate construction (9 types)
[0134] Drop ejection direction (5 types)
[0135] Ink type (7 types)
[0136] 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
[0137] 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.
[0138] 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, print technology may be listed more
than once in a table, where it shares characteristics with more
than one entry.
[0139] 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 WWW printers, Video printers, Medical imaging, Wide format
printers, Notebook PC in printers, Fax machines, Industrial
printing systems, Photocopiers, Photographic minilabs etc.
[0140] The information associated with the aforementioned 11
dimensional matrix are set out in the following tables.
TABLE-US-00002 ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK
DROPS) Description Advantages Disadvantages Examples Thermal An
electrothermal Large force High power Canon bubble heater heats the
generated Ink carrier Bubblejet 1979 ink to above Simple limited to
water Endo et al GB boiling point, construction Low patent
2,007,162 transferring No moving efficiency Xerox heater-
significant heat to parts High in-pit 1990 the aqueous ink. A Fast
operation temperatures Hawkins et al bubble nucleates Small chip
required U.S. Pat. No. 4,899,181 and quickly forms, area required
for High Hewlett- expelling the ink. actuator mechanical Packard
TIJ The efficiency of stress 1982 Vaught et the process is low,
Unusual al U.S. Pat. No. with typically less materials 4,490,728
than 0.05% of the required electrical energy Large drive being
transformed transistors into kinetic energy Cavitation of the drop.
causes actuator failure Kogation reduces bubble formation Large
print heads are difficult to fabricate Piezo- A piezoelectric Low
power Very large Kyser et al electric crystal such as consumption
area required for U.S. Pat. No. 3,946,398 lead lanthanum Many ink
actuator Zoltan U.S. Pat. No. zirconate (PZT) is types can be
Difficult to 3,683,212 electrically used integrate with 1973 Stemme
activated, and Fast operation electronics U.S. Pat. No. 3,747,120
either expands, High High voltage Epson Stylus shears, or bends to
efficiency drive transistors Tektronix apply pressure to required
IJ04 the ink, ejecting Full drops. pagewidth print heads
impractical due to actuator size Requires electrical poling in high
field strengths during manufacture Electro- An electric field is
Low power Low Seiko Epson, strictive used to activate consumption
maximum strain Usui et all JP electrostriction in Many ink (approx.
0.01%) 253401/96 relaxor materials types can be Large area IJ04
such as lead used required for lanthanum Low thermal actuator due
to zirconate titanate expansion low strain (PLZT) or lead Electric
field Response magnesium strength required speed is niobate (PMN).
(approx. 3.5 V/.mu.m) marginal (~ 10 .mu.s) can be High voltage
generated drive transistors without required difficulty Full Does
not pagewidth print require electrical heads poling impractical due
to actuator size Ferro- An electric field is Low power Difficult to
IJ04 electric used to induce a consumption integrate with phase
transition Many ink electronics between the types can be Unusual
antiferroelectric used materials such as (AFE) and Fast operation
PLZSnT are ferroelectric (FE) (<1 .mu.s) required phase.
Perovskite Relatively Actuators materials such as high longitudinal
require a large tin modified lead strain area lanthanum High
zirconate titanate efficiency (PLZSnT) exhibit Electric field large
strains of up strength of to 1% associated around 3 V/.mu.m with
the AFE to can be readily FE phase provided transition. Electro-
Conductive plates Low power Difficult to IJ02, IJ04 static are
separated by a consumption operate plates compressible or Many ink
electrostatic fluid dielectric types can be devices in an (usually
air). Upon used aqueous application of a Fast operation environment
voltage, the plates The attract each other electrostatic and
displace ink, actuator will causing drop normally need to ejection.
The be separated conductive plates from the ink may be in a comb
Very large or honeycomb area required to structure, or achieve high
stacked to increase forces the surface area High voltage and
therefore the drive transistors force. may be required Full
pagewidth print heads are not competitive due to actuator size
Electro- A strong electric Low current High voltage 1989 Saito et
static pull field is applied to consumption required al, U.S. Pat.
No. on ink the ink, whereupon Low May be 4,799,068 electrostatic
temperature damaged by 1989 Miura et attraction sparks due to air
al, U.S. Pat. No. accelerates the ink breakdown 4,810,954 towards
the print Required field Tone-jet 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 Permanent magnetic
displacing ink and types can be magnetic causing drop used material
such as ejection. Rare Fast operation Neodymium Iron earth magnets
with High Boron (NdFeB) a field strength efficiency required.
around 1 Tesla can Easy High local be used. Examples extension from
currents required are: Samarium single nozzles to Copper Cobalt
(SaCo) and pagewidth print metalization magnetic materials heads
should be used in the neodymium for long iron boron family
electromigration (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 Low power Complex IJ01, IJ05, magnetic induced a
consumption fabrication IJ08, IJ10, IJ12, core magnetic field in a
Many ink Materials not IJ14, IJ15, IJ17 electro- soft magnetic core
types can be usually present magnetic or yoke fabricated used in a
CMOS fab from a ferrous Fast operation such as NiFe, material such
as High CoNiFe, or CoFe electroplated iron efficiency are required
alloys such as Easy High local CoNiFe [1], CoFe, extension from
currents required or NiFe alloys. single nozzles to Copper
Typically, the soft pagewidth print metalization magnetic material
heads should be used is in two parts, for long which are
electromigration normally held lifetime and low apart by a spring.
resistivity When the solenoid Electroplating is actuated, the two
is required parts attract, High displacing the ink. 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, force
acting on a current consumption twisting motion IJ13, IJ16 carrying
wire in a Many ink Typically, magnetic field is types can be only a
quarter of utilized. used the solenoid This allows the Fast
operation length provides magnetic field to High force in a useful
be supplied efficiency direction externally to the Easy High local
print head, for extension from currents required example with rare
single nozzles to Copper earth permanent pagewidth print
metalization magnets. heads should be used Only the current for
long carrying wire need electromigration be fabricated on lifetime
and low the print-head, resistivity simplifying Pigmented materials
inks are usually requirements. infeasible Magneto- The actuator
uses Many ink Force acts as a Fischenbeck, striction the giant
types can be twisting motion U.S. Pat. No. 4,032,929
magnetostrictive used Unusual IJ25 effect of materials Fast
operation materials such as such as Terfenol-D Easy Terfenol-D are
(an alloy of extension from required terbium, single nozzles to
High local dysprosium and pagewidth print currents required iron
developed at heads Copper the Naval High force is metalization
Ordnance available should be used Laboratory, hence for long
Ter-Fe-NOL). For electromigration best efficiency, the lifetime and
low actuator should be resistivity pre-stressed to Pre-stressing
approx. 8 MPa. may be required Surface Ink under positive Low power
Requires Silverbrook, tension pressure is held in consumption
supplementary EP 0771 658 A2 reduction a nozzle by surface Simple
force to effect and related tension. The construction drop
separation patent surface tension of No unusual Requires
applications the ink is reduced materials special ink below the
bubble required in surfactants threshold, causing fabrication Speed
may be the ink to egress High limited by from the nozzle.
efficiency surfactant Easy properties extension from single nozzles
to pagewidth print heads Viscosity The ink viscosity Simple
Requires Silverbrook, reduction is locally reduced construction
supplementary EP 0771 658 A2 to select which No unusual force to
effect and related drops are to be materials drop separation patent
ejected. A required in Requires applications viscosity reduction
fabrication special ink can be achieved Easy viscosity
electrothermally extension from properties with most inks, but
single nozzles to High speed is special inks can be pagewidth print
difficult to engineered for a heads achieve 100:1 viscosity
Requires reduction. oscillating ink pressure A high temperature
difference (typically 80 degrees) is required
Acoustic An acoustic wave Can operate Complex 1993 is generated and
without a nozzle drive circuitry Hadimioglu et focussed upon the
plate Complex al, EUP 550,192 drop ejection fabrication 1993 Elrod
et region. Low al, EUP 572,220 efficiency Poor control of drop
position Poor control of drop volume Thermo- An actuator which Low
power Efficient IJ03, IJ09, elastic relies upon consumption aqueous
IJ17, IJ18, IJ19, bend differential Many ink operation IJ20, IJ21,
IJ22, actuator thermal expansion types can be requires a IJ23,
IJ24, IJ27, upon Joule heating used thermal insulator IJ28, IJ29,
IJ30, is used. Simple planar on the hot side IJ31, IJ32, IJ33,
fabrication Corrosion IJ34, IJ35, IJ36, Small chip prevention can
IJ37, IJ38, IJ39, area required for be difficult IJ40, IJ41 each
actuator Pigmented Fast operation inks may be High infeasible, as
efficiency pigment particles CMOS may jam the compatible bend
actuator voltages and currents Standard MEMS processes can be used
Easy extension from single nozzles to pagewidth print heads High
CTE A material with a High force Requires IJ09, IJ17, thermo- very
high can be generated special material IJ18, IJ20, IJ21, elastic
coefficient of Three (e.g. PTFE) IJ22, IJ23, IJ24, actuator thermal
expansion methods of Requires a IJ27, IJ28, IJ29, (CTE) such as
PTFE deposition PTFE deposition IJ30, IJ31, IJ42,
polytetrafluoroethylene are under process, which is IJ43, IJ44
(PTFE) is development: not yet standard used. As high CTE chemical
vapor in ULSI fabs materials are deposition PTFE usually non-
(CVD), spin deposition conductive, a coating, and cannot be heater
fabricated evaporation followed with from a conductive PTFE is a
high temperature material is candidate for (above 350.degree. C.)
incorporated. A 50 .mu.m low dielectric processing long PTFE
constant Pigmented bend actuator with insulation in inks may be
polysilicon heater ULSI infeasible, as and 15 mW power Very low
pigment particles input can provide power may jam the 180 .mu.N
force and consumption bend actuator 10 .mu.m deflection. Many ink
Actuator motions types can be include: used Bend Simple planar Push
fabrication Buckle Small chip Rotate area required for each
actuator Fast operation High efficiency CMOS compatible voltages
and currents Easy extension from single nozzles to pagewidth print
heads Conductive A polymer with a High force Requires IJ24 polymer
high coefficient of can be generated special materials thermo-
thermal expansion Very low development elastic (such as PTFE) is
power (High CTE actuator doped with consumption conductive
conducting Many ink polymer) substances to types can be Requires a
increase its used PTFE deposition conductivity to Simple planar
process, which is about 3 orders of fabrication not yet standard
magnitude below Small chip in ULSI fabs that of copper. The area
required for PTFE conducting each actuator deposition polymer
expands Fast operation cannot be when resistively High followed
with heated. efficiency high temperature Examples of CMOS (above
350.degree. C.) conducting compatible processing dopants include:
voltages and Evaporation Carbon nanotubes currents and CVD Metal
fibers Easy deposition Conductive extension from techniques
polymers such as single nozzles to cannot be used doped pagewidth
print Pigmented polythiophene heads inks may be Carbon granules
infeasible, as pigment particles may jam the bend actuator Shape A
shape memory High force is Fatigue limits IJ26 memory alloy such as
TiNi available maximum alloy (also known as (stresses of number of
cycles Nitinol - Nickel hundreds of Low strain Titanium alloy MPa)
(1%) is required developed at the Large strain is to extend fatigue
Naval Ordnance available (more resistance Laboratory) is than 3%)
Cycle rate thermally switched High limited by heat between its weak
corrosion removal martensitic state resistance Requires and its
high Simple unusual stiffness austenic construction materials
(TiNi) state. The shape of Easy The latent the actuator in its
extension from heat of martensitic state is single nozzles to
transformation deformed relative pagewidth print must be to the
austenic heads provided shape. The shape Low voltage High current
change causes operation operation ejection of a drop. Requires pre-
stressing to distort the martensitic state Linear Linear magnetic
Linear Requires IJ12 Magnetic actuators include Magnetic unusual
Actuator the Linear actuators can be semiconductor Induction
Actuator constructed with materials such as (LIA), Linear high
thrust, long soft magnetic Permanent Magnet travel, and high alloys
(e.g. Synchronous efficiency using CoNiFe) Actuator planar Some
varieties (LPMSA), Linear semiconductor also require Reluctance
fabrication permanent Synchronous techniques magnetic Actuator
(LRSA), Long actuator materials such as Linear Switched travel is
Neodymium iron Reluctance available boron (NdFeB) Actuator (LSRA),
Medium force Requires and the Linear is available complex multi-
Stepper Actuator Low voltage phase drive (LSA). operation circuitry
High current operation
TABLE-US-00003 BASIC OPERATION MODE Description Advantages
Disadvantages Examples Actuator This is the Simple Drop Thermal ink
directly simplest mode of operation repetition rate is jet pushes
operation: the No external usually limited Piezoelectric ink
actuator directly fields required to around 10 kHz. ink jet
supplies sufficient Satellite drops However, IJ01, IJ02, kinetic
energy to can be avoided if this is not IJ03, IJ04, IJ05, expel the
drop. drop velocity is fundamental to IJ06, IJ07, IJ09, The drop
must less than 4 m/s the method, but IJ11, IJ12, IJ14, have a
sufficient Can be is related to the IJ16, IJ20, IJ22, velocity to
efficient, refill method IJ23, IJ24, IJ25, overcome the depending
upon normally used IJ26, IJ27, IJ28, surface tension. the actuator
used All of the drop IJ29, IJ30, IJ31, kinetic energy IJ32, IJ33,
IJ34, must be IJ35, IJ36, IJ37, provided by the IJ38, IJ39, IJ40,
actuator IJ41, IJ42, IJ43, Satellite drops IJ44 usually form if
drop velocity is greater than 4.5 m/s Proximity The drops to be
Very simple Requires close Silverbrook, printed are print head
proximity EP 0771 658 A2 selected by some fabrication can between
the and related manner (e.g. be used print head and patent
thermally induced The drop the print media applications surface
tension selection means or transfer roller reduction of does not
need to May require pressurized ink). provide the two print heads
Selected drops are energy required printing alternate separated
from the to separate the rows of the ink in the nozzle drop from
the image by contact with the nozzle Monolithic print medium or a
color print heads transfer roller. are difficult Electro- The drops
to be Very simple Requires very Silverbrook, static pull printed
are print head high electrostatic EP 0771 658 A2 on ink selected by
some fabrication can field and related manner (e.g. be used
Electrostatic patent thermally induced The drop field for small
applications surface tension selection means nozzle sizes is
Tone-Jet reduction of does not need to above air pressurized ink).
provide the breakdown Selected drops are energy required
Electrostatic separated from the to separate the field may attract
ink in the nozzle drop from the dust by a strong electric nozzle
field. Magnetic The drops to be Very simple Requires Silverbrook,
pull on printed are print head magnetic ink EP 0771 658 A2 ink
selected by some fabrication can Ink colors and related manner
(e.g. be used other than black patent thermally induced The drop
are difficult applications surface tension selection means Requires
very reduction of does not need to high magnetic pressurized ink).
provide the fields Selected drops are energy required separated
from the to separate the ink in the nozzle drop from the by a
strong nozzle magnetic field acting on the magnetic ink. Shutter
The actuator High speed Moving parts IJ13, IJ17, moves a shutter to
(>50 kHz) are required IJ21 block ink flow to operation can be
Requires ink the nozzle. The ink achieved due to pressure pressure
is pulsed reduced refill modulator at a multiple of the time
Friction and drop ejection Drop timing wear must be frequency. can
be very considered accurate Stiction is The actuator possible
energy can be very low Shuttered The actuator Actuators with Moving
parts IJ08, IJ15, grill moves a shutter to small travel can are
required IJ18, IJ19 block ink flow be used Requires ink through a
grill to Actuators with pressure the nozzle. The small force can
modulator shutter movement be used Friction and need only be equal
High speed wear must be to the width of the (>50 kHz) considered
grill holes. operation can be Stiction is achieved possible Pulsed
A pulsed magnetic Extremely low Requires an IJ10 magnetic field
attracts an energy operation external pulsed pull on `ink pusher`
at the is possible magnetic field ink drop ejection No heat
Requires pusher frequency. An dissipation special materials
actuator controls a problems for both the catch, which actuator and
the prevents the ink ink pusher pusher from Complex moving when a
construction drop is not to be ejected.
TABLE-US-00004 AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES)
Description Advantages Disadvantages Examples None The actuator
Simplicity of Drop ejection Most ink jets, directly fires the
construction energy must be including ink drop, and there
Simplicity of supplied by piezoelectric and is no external field
operation individual nozzle thermal bubble. or other Small physical
actuator IJ01, IJ02, mechanism size IJ03, IJ04, IJ05, required.
IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24, IJ25, IJ26,
IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36, IJ37,
IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The ink
pressure Oscillating ink Requires Silverbrook, ink oscillates,
pressure can external ink EP 0771 658 A2 pressure providing much of
provide a refill pressure and related (including the drop ejection
pulse, allowing oscillator patent acoustic energy. The higher
operating Ink pressure applications stimulation) actuator selects
speed phase and IJ08, IJ13, which drops are to The actuators
amplitude must IJ15, IJ17, IJ18, be fired by may operate be
carefully IJ19, IJ21 selectively with much lower controlled
blocking or energy Acoustic enabling nozzles. Acoustic reflections
in the The ink pressure lenses can be ink chamber oscillation may
be used to focus the must be achieved by sound on the designed for
vibrating the print nozzles head, or preferably by an actuator in
the ink supply. Media The print head is Low power Precision
Silverbrook, proximity placed in close High accuracy assembly EP
0771 658 A2 proximity to the Simple print required and related
print medium. head Paper fibers patent Selected drops construction
may cause applications protrude from the problems print head
further Cannot print than unselected on rough drops, and contact
substrates the print medium. The drop soaks into the medium fast
enough to cause drop separation. Transfer Drops are printed High
accuracy Bulky Silverbrook, roller to a transfer roller Wide range
of Expensive EP 0771 658 A2 instead of straight print substrates
Complex and related to the print can be used construction patent
medium. A Ink can be applications transfer roller can dried on the
Tektronix hot also be used for transfer roller melt proximity drop
piezoelectric ink separation. jet Any of the IJ series Electro- An
electric field is Low power Field strength Silverbrook, static used
to accelerate Simple print required for EP 0771 658 A2 selected
drops head separation of and related towards the print construction
small drops is patent medium. near or above air applications
breakdown Tone-Jet Direct A magnetic field is Low power Requires
Silverbrook, magnetic used to accelerate Simple print magnetic ink
EP 0771 658 A2 field selected drops of head Requires and related
magnetic ink construction strong magnetic patent towards the print
field applications medium. Cross The print head is Does not
Requires IJ06, IJ16 magnetic placed in a require magnetic external
magnet field constant magnetic materials to be Current field. The
Lorenz integrated in the densities may be force in a current print
head high, resulting in carrying wire is manufacturing
electromigration used to move the process problems actuator. Pulsed
A pulsed magnetic Very low Complex print IJ10 magnetic field is
used to power operation head field cyclically attract a is possible
construction paddle, which Small print Magnetic pushes on the ink.
head size materials A small actuator required in print moves a
catch, head which selectively prevents the paddle from moving.
TABLE-US-00005 ACTUATOR AMPLIFICATION OR MODIFICATION METHOD
Description Advantages Disadvantages Examples None No actuator
Operational Many actuator Thermal mechanical simplicity mechanisms
Bubble Ink jet amplification is have insufficient IJ01, IJ02, used.
The actuator travel, or IJ06, IJ07, IJ16, directly drives the
insufficient IJ25, IJ26 drop ejection force, to process.
efficiently drive the drop ejection process Differential An
actuator Provides High stresses Piezoelectric expansion material
expands greater travel in are involved IJ03, IJ09, bend more on one
side a reduced print Care must be IJ17, IJ18, IJ19, actuator than
on the other. head area taken that the IJ20, IJ21, IJ22, The
expansion materials do not IJ23, IJ24, IJ27, may be thermal,
delaminate IJ29, IJ30, IJ31, piezoelectric, Residual bend IJ32,
IJ33, IJ34, magnetostrictive, resulting from IJ35, IJ36, IJ37, or
other high temperature IJ38, IJ39, IJ42, mechanism. The or high
stress IJ43, IJ44 bend actuator during formation converts a high
force low travel actuator mechanism to high travel, lower force
mechanism. Transient A trilayer bend Very good High stresses IJ40,
IJ41 bend actuator where the temperature are involved actuator two
outside layers stability Care must be are identical. This High
speed, as taken that the cancels bend due a new drop can materials
do not to ambient be fired before delaminate temperature and heat
dissipates residual stress. The Cancels actuator only residual
stress of responds to formation transient heating of one side or
the other. Reverse The actuator loads Better Fabrication IJ05, IJ11
spring a spring. When the coupling to the complexity actuator is
turned ink High stress in off, the spring the spring releases. 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 Increased Some stack actuators
are travel fabrication piezoelectric ink stacked. This can Reduced
drive complexity jets be appropriate voltage Increased IJ04 where
actuators possibility of require high short circuits due electric
field to pinholes strength, such as electrostatic and piezoelectric
actuators. Multiple Multiple smaller Increases the Actuator IJ12,
IJ13, actuators actuators are used force available forces may not
IJ18, IJ20, IJ22, simultaneously to from an actuator add linearly,
IJ28, IJ42, IJ43 move the ink. Each Multiple reducing actuator need
actuators can be efficiency provide only a positioned to portion of
the control ink flow force required. accurately Linear A linear
spring is Matches low Requires print IJ15 Spring used to transform
a travel actuator head area for the motion with small with higher
spring travel and high travel force into a longer requirements
travel, lower force Non-contact motion. method of motion
transformation Coiled A bend actuator is Increases Generally IJ17,
IJ21, actuator coiled to provide travel restricted to IJ34, IJ35
greater travel in a Reduces chip planar reduced chip area. area
implementations Planar due to extreme implementations fabrication
are relatively difficulty in easy to fabricate. other orientations.
Flexure A bend actuator Simple means Care must be IJ10, IJ19, bend
has a small region of increasing taken not to IJ33 actuator near
the fixture travel of a bend exceed the point, which flexes
actuator elastic limit in much more readily the flexure area than
the remainder Stress of the actuator. distribution is The actuator
very uneven flexing is Difficult to effectively accurately model
converted from an with finite even coiling to an element analysis
angular bend, resulting in greater travel of the actuator tip.
Catch The actuator Very low Complex IJ10 controls a small actuator
energy construction catch. The catch Very small Requires either
enables or actuator size external force disables movement
Unsuitable for of an ink pusher pigmented inks that is controlled
in a bulk manner. Gears Gears can be used Low force, Moving parts
IJ13 to increase travel low travel are required at the expense of
actuators can be Several duration. Circular used actuator cycles
gears, rack and Can be are required pinion, ratchets, fabricated
using More complex and other gearing standard surface drive
electronics methods can be MEMS Complex used. processes
construction Friction, friction, and wear are possible Buckle A
buckle plate can Very fast Must stay S. Hirata et al, plate be used
to change movement within elastic "An Ink-jet a slow actuator
achievable limits of the Head Using into a fast motion. materials
for Diaphragm It can also convert long device life Microactuator",
a high force, low High stresses Proc. IEEE travel actuator into
involved MEMS, February a high travel, Generally 1996, pp 418-423.
medium force high power IJ18, IJ27 motion. requirement Tapered A
tapered Linearizes the Complex IJ14 magnetic magnetic pole can
magnetic construction pole increase travel at force/distance the
expense of curve force. Lever A lever and Matches low High stress
IJ32, IJ36, fulcrum is used to travel actuator around the IJ37
transform a motion with higher fulcrum with small travel travel and
high force into requirements a motion with Fulcrum area longer
travel and has no linear lower force. The movement, and lever can
also can be used for a reverse the fluid seal direction of travel.
Rotary The actuator is High Complex IJ28 impeller connected to a
mechanical construction rotary impeller. A advantage Unsuitable for
small angular The ratio of pigmented inks deflection of the force
to travel of actuator results in the actuator can a rotation of the
be matched to impeller vanes, the nozzle which push the ink
requirements by against stationary varying the vanes and out of
number of the nozzle. impeller vanes Acoustic A refractive or No
moving Large area 1993 lens diffractive (e.g. parts required
Hadimioglu et zone plate) Only relevant al, EUP 550,192 acoustic
lens is for acoustic ink 1993 Elrod et used to concentrate jets al,
EUP 572,220 sound waves. Sharp A sharp point is Simple Difficult to
Tone-jet conductive used to concentrate construction fabricate
using point an electrostatic standard VLSI field. processes for a
surface ejecting ink-jet Only relevant for electrostatic ink
jets
TABLE-US-00006 ACTUATOR MOTION Description Advantages Disadvantages
Examples Volume The volume of the Simple High energy is Hewlett-
expansion actuator changes, construction in typically Packard
Thermal pushing the ink in the case of required to Ink jet all
directions. thermal ink jet achieve volume Canon expansion. This
Bubblejet leads to thermal stress, cavitation, and kogation in
thermal ink jet implementations Linear, The actuator Efficient High
IJ01, IJ02, normal to moves in a coupling to ink fabrication IJ04,
IJ07, IJ11, chip direction normal to drops ejected complexity may
IJ14 surface the print head normal to the be required to surface.
The surface achieve nozzle is typically perpendicular in the line
of motion movement. Parallel to The actuator Suitable for
Fabrication IJ12, IJ13, chip moves parallel to planar complexity
IJ15, IJ33,, IJ34, surface the print head fabrication Friction
IJ35, IJ36 surface. Drop Stiction ejection may still be normal to
the surface. Membrane An actuator with a The effective Fabrication
1982 Howkins push high force but area of the complexity U.S. Pat.
No. 4,459,601 small area is used actuator Actuator size to push a
stiff becomes the Difficulty of membrane that is membrane area
integration in a in contact with the VLSI process ink. Rotary The
actuator Rotary levers Device IJ05, IJ08, causes the rotation may
be used to complexity IJ13, IJ28 of some element, increase travel
May have such a grill or Small chip friction at a pivot impeller
area point requirements Bend The actuator bends A very small
Requires the 1970 Kyser et when energized. change in actuator to be
al U.S. Pat. No. This may be due to dimensions can made from at
3,946,398 differential be converted to a least two distinct 1973
Stemme thermal expansion, large motion. layers, or to have U.S.
Pat. No. 3,747,120 piezoelectric a thermal IJ03, IJ09, expansion,
difference across IJ10, IJ19, IJ23, magnetostriction, the actuator
IJ24, IJ25, IJ29, or other form of IJ30, IJ31, IJ33, relative IJ34,
IJ35 dimensional change. Swivel The actuator Allows Inefficient
IJ06 swivels around a operation where coupling to the central
pivot. This the net linear ink motion motion is suitable force on
the where there are paddle is zero opposite forces Small chip
applied to opposite area sides of the paddle, requirements e.g.
Lorenz force. Straighten The actuator is Can be used Requires IJ26,
IJ32 normally bent, and with shape careful balance straightens when
memory alloys of stresses to energized. where the ensure that the
austenic phase is quiescent bend is planar accurate Double The
actuator bends One actuator Difficult to IJ36, IJ37, bend in one
direction can be used to make the drops IJ38 when one element power
two ejected by both is energized, and nozzles. bend directions
bends the other Reduced chip identical. way when another size. A
small element is Not sensitive efficiency loss energized. to
ambient compared to temperature equivalent single bend actuators.
Shear Energizing the Can increase Not readily 1985 Fishbeck
actuator causes a the effective applicable to U.S. Pat. No.
4,584,590 shear motion in the travel of other actuator actuator
material. piezoelectric mechanisms actuators Radial The actuator
Relatively High force 1970 Zoltan constriction squeezes an ink easy
to fabricate required U.S. Pat. No. 3,683,212 reservoir, forcing
single nozzles Inefficient ink from a from glass Difficult to
constricted nozzle. tubing as integrate with macroscopic VLSI
processes structures Coil/ A coiled actuator Easy to Difficult to
IJ17, IJ21, uncoil uncoils or coils fabricate as a fabricate for
IJ34, IJ35 more tightly. The planar VLSI non-planar motion of the
free process devices end of the actuator Small area Poor out-of-
ejects the ink. required, plane stiffness therefore low cost Bow
The actuator bows Can increase Maximum IJ16, IJ18, (or buckles) in
the the speed of travel is IJ27 middle when travel constrained
energized. Mechanically High force rigid required Push-Pull Two
actuators The structure Not readily IJ18 control a shutter. is
pinned at both suitable for ink One actuator pulls ends, so has a
jets which the shutter, and the high out-of- directly push the
other pushes it. plane rigidity ink Curl A set of actuators Good
fluid Design IJ20, IJ42 inwards curl inwards to flow to the
complexity reduce the volume region behind of ink that they the
actuator enclose. increases efficiency Curl A set of actuators
Relatively Relatively IJ43 outwards curl outwards, simple large
chip area pressurizing ink in construction a chamber surrounding
the actuators, and expelling ink from a nozzle in the chamber. Iris
Multiple vanes High High IJ22 enclose a volume efficiency
fabrication of ink. These Small chip complexity simultaneously area
Not suitable rotate, reducing for pigmented the volume inks between
the vanes. Acoustic The actuator The actuator Large area 1993
vibration vibrates at a high can be required for Hadimioglu et
frequency. physically efficient al, EUP 550,192 distant from the
operation at 1993 Elrod et ink useful al, EUP 572,220 frequencies
Acoustic coupling and crosstalk Complex drive circuitry Poor
control of drop volume and position None In various ink jet No
moving Various other Silverbrook, designs the parts tradeoffs are
EP 0771 658 A2 actuator does not required to and related move.
eliminate patent moving parts applications Tone-jet
TABLE-US-00007 NOZZLE REFILL METHOD Description Advantages
Disadvantages Examples Surface This is the normal Fabrication Low
speed Thermal ink tension way that ink jets simplicity Surface jet
are refilled. After Operational tension force Piezoelectric the
actuator is simplicity relatively small ink jet energized, it
compared to IJ01-IJ07, typically returns actuator force IJ10-IJ14,
IJ16, rapidly to its Long refill IJ20, IJ22-IJ45 normal position.
time usually This rapid return dominates the sucks in air 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, oscillating chamber is Low
actuator common ink IJ15, IJ17, IJ18, ink provided at a energy, as
the pressure IJ19, IJ21 pressure pressure that actuator need
oscillator oscillates at twice only open or May not be the drop
ejection close the shutter, suitable for frequency. When a instead
of pigmented inks drop is to be ejecting the ink ejected, the
shutter drop 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 the nozzle is independent ejected a drop a actively
refilled actuators per second (refill) 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 The ink is held a High refill
Surface spill Silverbrook, ink slight positive rate, therefore a
must be EP 0771 658 A2 pressure pressure. After the high drop
prevented and related ink drop is ejected, repetition rate is
Highly patent the nozzle possible hydrophobic applications chamber
fills print head Alternative quickly as surface surfaces are for:,
IJ01-IJ07, tension and ink required IJ10-IJ14, IJ16, pressure both
IJ20, IJ22-IJ45 operate to refill the nozzle.
TABLE-US-00008 METHOD OF RESTRICTING BACK-FLOW THROUGH INLET
Description Advantages Disadvantages Examples Long inlet The ink
inlet Design Restricts refill Thermal ink channel channel to the
simplicity rate jet nozzle chamber is Operational May result in
Piezoelectric made long and simplicity a relatively large ink jet
relatively narrow, Reduces chip area IJ42, IJ43 relying on viscous
crosstalk Only partially drag to reduce effective inlet back-flow.
Positive The ink is under a Drop selection Requires a Silverbrook,
ink positive pressure, and separation method (such as EP 0771 658
A2 pressure so that in the forces can be a nozzle rim or and
related quiescent state reduced effective patent some of the ink
Fast refill time hydrophobizing, applications drop already or both)
to Possible protrudes from the prevent flooding operation of the
nozzle. of the ejection following: IJ01-IJ07, This reduces the
surface of the IJ09-IJ12, pressure in the print head. IJ14, IJ16,
IJ20, nozzle chamber IJ22,, IJ23-IJ34, which is required IJ36-IJ41,
IJ44 to eject a certain volume of ink. The reduction in chamber
pressure results in a reduction in ink pushed out through the
inlet. Baffle One or more The refill rate Design HP Thermal baffles
are placed is not as complexity Ink Jet in the inlet ink restricted
as the May increase Tektronix flow. When the long inlet fabrication
piezoelectric ink actuator is method. complexity (e.g. jet
energized, the Reduces Tektronix hot rapid ink crosstalk melt
movement creates Piezoelectric eddies which print heads). restrict
the flow through the inlet. The slower refill process is
unrestricted, and does not result in eddies. Flexible In this
method Significantly Not applicable Canon flap recently disclosed
reduces back- to most ink jet restricts by Canon, the flow for
edge- configurations inlet expanding actuator shooter thermal
Increased (bubble) pushes on ink jet devices fabrication a flexible
flap that complexity restricts the inlet. Inelastic deformation of
polymer flap results in creep over extended use Inlet filter A
filter is located Additional Restricts refill IJ04, IJ12, between
the ink advantage of ink rate IJ24, IJ27, IJ29, inlet and the
filtration May result in IJ30 nozzle chamber. Ink filter may
complex The filter has a be fabricated construction multitude of
small with no holes or slots, additional restricting ink process
steps flow. The filter also removes particles which may block the
nozzle. Small The ink inlet Design Restricts refill IJ02, IJ37,
inlet channel to the simplicity rate IJ44 compared nozzle chamber
May result in to nozzle has a substantially a relatively large
smaller cross chip area section than that of Only partially the
nozzle, effective resulting in easier ink egress out of the nozzle
than out of the inlet. Inlet A secondary Increases Requires IJ09
shutter actuator controls speed of the ink- separate refill the
position of a jet print head actuator and shutter, closing off
operation drive circuit the ink inlet when the main actuator is
energized. The inlet The method avoids Back-flow Requires IJ01,
IJ03, is located the problem of problem is careful design to IJ05,
IJ06, IJ07, behind inlet back-flow by eliminated minimize the IJ10,
IJ11, IJ14, the ink- arranging the ink- negative IJ16, IJ22, IJ23,
pushing pushing surface of pressure behind IJ25, IJ28, IJ31,
surface the actuator the paddle IJ32, IJ33, IJ34, between the inlet
IJ35, IJ36, IJ39, and the nozzle. IJ40, IJ41 Part of The actuator
and a Significant Small increase IJ07, IJ20, the wall of the ink
reductions in in fabrication IJ26, IJ38 actuator chamber are
back-flow can be complexity moves to arranged so that achieved shut
off the motion of the Compact the inlet actuator closes off designs
possible the inlet. Nozzle In some Ink back-flow None related
Silverbrook, actuator configurations of problem is to ink back-flow
EP 0771 658 A2 does not ink jet, there is no eliminated on
actuation and related result in expansion or patent ink back-
movement of an applications flow actuator which Valve-jet may cause
ink Tone-jet back-flow through the inlet.
TABLE-US-00009 NOZZLE CLEARING METHOD Description Advantages
Disadvantages Examples Normal All of the nozzles No added May not
be Most ink jet nozzle are fired complexity on sufficient to
systems firing periodically, the print head displace dried IJ01,
IJ02, before the ink has ink IJ03, IJ04, IJ05, a chance to dry.
IJ06, IJ07, IJ09, When not in use IJ10, IJ11, IJ12, the nozzles are
IJ14, IJ16, IJ20, sealed (capped) IJ22, IJ23, IJ24, against air.
IJ25, IJ26, IJ27, The nozzle firing IJ28, IJ29, IJ30, is usually
IJ31, IJ32, IJ33, performed during a IJ34, IJ36, IJ37, special
clearing IJ38, IJ39, IJ40,, cycle, after first IJ41, IJ42, IJ43,
moving the print IJ44,, IJ45 head to a cleaning station. Extra In
systems which Can be highly Requires Silverbrook, power to heat the
ink, but do effective if the higher drive EP 0771 658 A2 ink heater
not boil it under heater is voltage for and related normal
situations, adjacent to the clearing patent nozzle clearing can
nozzle May require applications be achieved by larger drive
over-powering the transistors heater and boiling ink at the nozzle.
Rapid The actuator is Does not Effectiveness May be used succession
fired in rapid require extra depends with: IJ01, IJ02, of
succession. In drive circuits on substantially IJ03, IJ04, IJ05,
actuator some the print head upon the IJ06, IJ07, IJ09, pulses
configurations, this Can be readily configuration of IJ10, IJ11,
IJ14, may cause heat controlled and the ink jet nozzle IJ16, IJ20,
IJ22, build-up at the initiated by IJ23, IJ24, IJ25, nozzle which
boils digital logic IJ27, IJ28, IJ29, the ink, clearing IJ30, IJ31,
IJ32, the nozzle. In other IJ33, IJ34, IJ36, situations, it may
IJ37, IJ38, IJ39, cause sufficient IJ40, IJ41, IJ42, vibrations to
IJ43, IJ44, IJ45 dislodge clogged nozzles. Extra Where an actuator
A simple Not suitable May be used power to is not normally solution
where where there is a with: IJ03, IJ09, ink driven to the limit
applicable hard limit to IJ16, IJ20, IJ23, pushing of its motion,
actuator IJ24, IJ25, IJ27, actuator nozzle clearing movement IJ29,
IJ30, IJ31, may be assisted by IJ32, IJ39, IJ40, providing an IJ41,
IJ42, IJ43, enhanced drive IJ44, IJ45 signal to the actuator.
Acoustic An ultrasonic A high nozzle High IJ08, IJ13, resonance
wave is applied to clearing implementation IJ15, IJ17, IJ18, the
ink chamber. capability can be cost if system IJ19, IJ21 This wave
is of an achieved does not already appropriate May be include an
amplitude and implemented at acoustic actuator frequency to cause
very low cost in sufficient force at systems which the nozzle to
clear already include blockages. This is acoustic easiest to
achieve actuators if the ultrasonic wave is at a resonant frequency
of the ink cavity. Nozzle A microfabricated Can clear Accurate
Silverbrook, clearing plate is pushed severely clogged mechanical
EP 0771 658 A2 plate against the nozzles alignment is and related
nozzles. The plate required patent has a post for Moving parts
applications every nozzle. A are required post moves There is risk
through each of damage to the nozzle, displacing nozzles dried ink.
Accurate fabrication is required Ink The pressure of the May be
Requires May be used pressure ink is temporarily effective where
pressure pump with all IJ series pulse increased so that other
methods or other pressure ink jets ink streams from cannot be used
actuator all of the nozzles. Expensive This may be used Wasteful of
in conjunction ink with actuator energizing. Print A flexible
`blade` Effective for Difficult to Many ink jet head is wiped
across the planar print head use if print head systems wiper print
head surface. surfaces surface is non- The blade is Low cost planar
or very usually fabricated fragile from a flexible Requires
polymer, e.g. mechanical parts rubber or synthetic Blade can
elastomer. wear out in high volume print systems Separate A
separate heater Can be Fabrication Can be used ink is provided at
the effective where complexity with many IJ boiling nozzle although
other nozzle series ink jets heater the normal drop e- clearing
methods ection mechanism cannot be used does not require it. Can be
The heaters do not implemented at require individual no additional
drive circuits, as cost in some ink many nozzles can jet be cleared
configurations simultaneously, and no imaging is required.
TABLE-US-00010 NOZZLE PLATE CONSTRUCTION Description Advantages
Disadvantages Examples Electro- A nozzle plate is Fabrication High
Hewlett formed separately simplicity temperatures and Packard
Thermal nickel fabricated from pressures are Ink jet electroformed
required to bond nickel, and bonded nozzle plate to the print head
Minimum chip. thickness constraints Differential thermal expansion
Laser Individual nozzle No masks Each hole Canon ablated or holes
are ablated required must be Bubblejet drilled by an intense UV Can
be quite individually 1988 Sercel et polymer laser in a nozzle fast
formed al., SPIE, Vol. plate, which is Some control Special 998
Excimer typically a over nozzle equipment Beam polymer such as
profile is required Applications, pp. polyimide or possible Slow
where 76-83 polysulphone Equipment there are many 1993 required is
thousands of Watanabe et al., relatively low nozzles per print U.S.
Pat. No. 5,208,604 cost head May produce thin burrs at exit holes
Silicon A separate nozzle High accuracy Two part K. Bean, micro-
plate is is attainable construction IEEE machined micromachined
High cost Transactions on from single crystal Requires Electron
silicon, and precision Devices, Vol. bonded to the print alignment
ED-25, No. 10, head wafer. Nozzles may 1978, pp 1185-1195 be
clogged by Xerox 1990 adhesive Hawkins et al., U.S. Pat. No.
4,899,181 Glass Fine glass No expensive Very small 1970 Zoltan
capillaries capillaries are equipment nozzle sizes are U.S. Pat.
No. 3,683,212 drawn from glass required difficult to form tubing.
This Simple to Not suited for method has been make single mass
production used for making nozzles individual 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, surface deposited as a (<1 .mu.m)
sacrificial layer EP 0771 658 A2 micro- layer using Monolithic
under the nozzle and related machined standard VLSI Low cost plate
to form the patent using deposition Existing nozzle chamber
applications VLSI techniques. processes can be Surface may IJ01,
IJ02, litho- Nozzles are etched used be fragile to the IJ04, IJ11,
IJ12, graphic in the nozzle plate touch IJ17, IJ18, IJ20, processes
using VLSI IJ22, IJ24, IJ27, lithography and IJ28, IJ29, IJ30,
etching. IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40,
IJ41, IJ42, IJ43, IJ44 Monolithic, The nozzle plate is High
accuracy Requires long IJ03, IJ05, etched a buried etch stop (<1
.mu.m) etch times IJ06, IJ07, IJ08, through in the wafer.
Monolithic Requires a IJ09, IJ10, IJ13, substrate Nozzle chambers
Low cost support wafer IJ14, IJ15, IJ16, are etched in the No
differential IJ19, IJ21, IJ23, front of the wafer, expansion IJ25,
IJ26 and the wafer is thinned from the back side. Nozzles are then
etched in the etch stop layer. No nozzle Various methods No nozzles
to Difficult to Ricoh 1995 plate have been tried to become clogged
control drop Sekiya et al U.S. Pat. No. eliminate the position
5,412,413 nozzles entirely, to accurately 1993 prevent nozzle
Crosstalk Hadimioglu et al clogging. These problems EUP 550,192
include thermal 1993 Elrod et bubble al EUP 572,220 mechanisms and
acoustic lens mechanisms Trough Each drop ejector Reduced Drop
firing IJ35 has a trough manufacturing direction is through which a
complexity sensitive to paddle moves. Monolithic wicking. There is
no nozzle plate. Nozzle slit The elimination of No nozzles to
Difficult to 1989 Saito et instead of nozzle holes and become
clogged control drop al U.S. Pat. No. individual replacement by a
position 4,799,068 nozzles slit encompassing accurately many
actuator Crosstalk positions reduces problems nozzle clogging, but
increases crosstalk due to ink surface waves
TABLE-US-00011 DROP EJECTION DIRECTION Description Advantages
Disadvantages Examples Edge Ink flow is along Simple Nozzles Canon
(`edge the surface of the construction limited to edge Bubblejet
1979 shooter`) chip, and ink drops No silicon High Endo et al GB
are ejected from etching required resolution is patent 2,007,162
the chip edge. Good heat difficult Xerox heater- sinking via Fast
color in-pit 1990 substrate printing requires Hawkins et al
Mechanically one print head U.S. Pat. No. 4,899,181 strong per
color Tone-jet Ease of chip handing Surface Ink flow is along No
bulk Maximum ink Hewlett- (`roof the surface of the silicon etching
flow is severely Packard TIJ shooter`) chip, and ink drops required
restricted 1982 Vaught et are ejected from Silicon can al U.S. Pat.
No. the chip surface, make an 4,490,728 normal to the effective
heat IJ02, IJ11, plane of the chip. sink IJ12, IJ20, IJ22
Mechanical strength Through Ink flow is through High ink flow
Requires bulk Silverbrook, chip, the chip, and ink Suitable for
silicon etching EP 0771 658 A2 forward drops are ejected pagewidth
print and related (`up from the front heads patent shooter`)
surface of the chip. High nozzle applications packing density IJ04,
IJ17, therefore low IJ18, IJ24, IJ27-IJ45 manufacturing cost
Through Ink flow is through High ink flow Requires IJ01, IJ03,
chip, the chip, and ink Suitable for wafer thinning IJ05, IJ06,
IJ07, reverse drops are ejected pagewidth print Requires IJ08,
IJ09, IJ10, (`down from the rear heads special handling IJ13, IJ14,
IJ15, shooter`) surface of the chip. High nozzle during IJ16, IJ19,
IJ21, packing density manufacture IJ23, IJ25, IJ26 therefore low
manufacturing cost Through Ink flow is through Suitable for
Pagewidth Epson Stylus actuator the actuator, which piezoelectric
print heads Tektronix hot is not fabricated as print heads require
several melt part of the same thousand piezoelectric ink substrate
as the connections to jets drive transistors. drive circuits Cannot
be manufactured in standard CMOS fabs Complex assembly required
TABLE-US-00012 INK TYPE Description Advantages Disadvantages
Examples Aqueous, Water based ink Environmentally Slow drying Most
existing dye which typically friendly Corrosive ink jets contains:
water, No odor Bleeds on All IJ series dye, surfactant, paper ink
jets humectant, and May Silverbrook, biocide. strikethrough EP 0771
658 A2 Modern ink dyes Cockles paper and related have high water-
patent fastness, light applications fastness Aqueous, Water based
ink Environmentally Slow drying IJ02, IJ04, pigment which typically
friendly Corrosive IJ21, IJ26, IJ27, contains: water, No odor
Pigment may IJ30 pigment, Reduced bleed clog nozzles Silverbrook,
surfactant, Reduced Pigment may EP 0771 658 A2 humectant, and
wicking clog actuator and related biocide. Reduced mechanisms
patent Pigments have an strikethrough Cockles paper applications
advantage in Piezoelectric reduced bleed, ink-jets wicking and
Thermal ink strikethrough. jets (with significant restrictions)
Methyl MEK is a highly Very fast Odorous All IJ series Ethyl
volatile solvent drying Flammable ink jets Ketone used for
industrial Prints on (MEK) printing on various difficult surfaces
substrates such such as aluminum as metals and cans. plastics
Alcohol Alcohol based inks Fast drying Slight odor All IJ series
(ethanol, can be used where Operates at Flammable ink jets
2-butanol, the printer must sub-freezing and operate at
temperatures others) temperatures Reduced below the freezing paper
cockle point of water. An Low cost example of this is in-camera
consumer photographic printing. Phase The ink is solid at No drying
High viscosity Tektronix hot change room temperature, time-ink
Printed ink melt (hot melt) and is melted in instantly freezes
typically has a piezoelectric ink the print head on the print
`waxy` feel jets before jetting. Hot medium Printed pages 1989
Nowak melt inks are Almost any may `block` U.S. Pat. No. 4,820,346
usually wax based, print medium Ink All IJ series with a melting
can be used temperature may ink jets point around 80.degree. C. No
paper be above the After jetting cockle occurs curie point of the
ink freezes No wicking permanent almost instantly occurs magnets
upon contacting No bleed Ink heaters the print medium occurs
consume power or a transfer roller. No Long warm- strikethrough up
time occurs Oil Oil based inks are High High All IJ series
extensively used in solubility viscosity: this is ink jets offset
printing. medium for a significant They have some dyes limitation
for use advantages in Does not in ink jets, which improved cockle
paper usually require a characteristics on Does not wick low
viscosity. paper (especially through paper Some short no wicking or
chain and multi- cockle). Oil branched oils soluble dies and have a
pigments are sufficiently low required. viscosity. Slow drying
Micro- A microemulsion Stops ink Viscosity All IJ series emulsion
is a stable, self bleed higher than ink jets forming emulsion High
dye water of oil, water, and solubility Cost is surfactant. The
Water, oil, slightly higher characteristic drop and amphiphilic
than water based size is less than soluble dies can ink 100 nm, and
is be used High determined by the Can stabilize surfactant
preferred curvature pigment concentration of the surfactant.
suspensions required (around 5%)
* * * * *