Utilization of Quantum Wires in MEMS Actuators

The present invention relates to a thermal actuator device and, in particular, discloses a method of utilisation of quantum wires in MEMS actuators.

The present invention further relates to the construction of micro-electro mechanical systems (MEMS).

MEMS processes are often characterised by the construction of conductive layers in multilayered structures such as actuator devices or the like. Often, it is important for these conductive layers to be in thermal contact with an adjacent material where the conductive layer is utilised as a heater element to instigate the actuation of an active device of the micro-electro mechanical system. The conductive layer material is typically a different material than the material utilised in the adjacent, thermally active layer, creating problems associated with the formation of such active, multilayered structures such as de-lamination and in-efficient thermal connection which can cause problems in the device performance and ultimately devices may stop functioning.

It is an object of the present invention to provide a MEMS construction which alleviates the aforementioned problems.

In accordance with a first aspect of the present invention there is provided a method of constructing one or more electrically conductive portions within a substantially non-conductive material comprising embedding quantum wires of a substantially conductive material within said portions.

In accordance with a second aspect of the present invention there is provided a thermal actuator comprising a substantially non-conductive, heat expansive material having a predetermined portion thereof rendered electrically conductive by the incorporation of a series of quantum wires of a substantially conductive material.

Preferably, the non-conductive, expansive material comprises substantially polytetrafluoroethylene and the conductive material comprises substantially copper.

In accordance with a third aspect of the present invention there is provided a thermal actuator comprising first and second layers of substantially non-conductive, heat expansive materials, wherein one of said layers incorporates quantum wires of a substantially conductive material interposed with said substantially non-conductive, expansive material.

Preferably, the non-conductive, expansive material comprises substantially polytetrafluoroethylene and the conductive material comprises substantially copper.

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings which:

FIG. 1 is a cut out topside view of illustrating two adjoining inject nozzles constructed in accordance with the preferred embodiment.

FIG. 2 is an exploded perspective view illustrating the construction of a single inject nozzle in accordance with the preferred embodiment.

The preferred embodiment of the present invention will be described in respect of an ink jet print head construction which utilises quantum wires embedded in a thermal expansion layer. The present invention should, however, not necessarily be restricted to the field of ink jet printing, as will be readily evident.

In the preferred embodiment, an inkjet nozzle is provided having a thermally based actuator which is highly energy efficient. The thermal actuator is located within an chamber filled with ink and relies upon the thermal expansion of materials when an electric current is being passed through them to activate the actuator thereby causing the ejection of ink out of a nozzle provided in the nozzle chamber.

Turning to FIG. 1, there are illustrated two adjoining inkjet nozzles 10 constructed in accordance with the preferred embodiment. Each nozzle 10, can be constructed as part of an array of nozzles on a silicon wafer device and can be constructed utilising semiconductor processing techniques in addition to micro machining and micro fabrication process technology (MEMS) and a full familiarity with these technologies is hereinafter assumed.

The nozzle chamber 10 includes a ink ejection port 11 for the ejection of ink from within the nozzle chamber. Ink is supplied via an inlet port 12 which has a grill structure fabricated from a series of posts 14, the grill acting to filter out foreign bodies within the ink supply and also to provide stability to the nozzle chamber structure. Inside the nozzle chamber is constructed a thermal actuator device 16 which is interconnected to an electric circuit (not shown) which, when thermally actuated, acts as a paddle bending upwards so as to cause the ejection of ink from each ink ejection port 11. A series of etchant holes e.g. 18 are also provided in the top of nozzle chamber 10, the holes 18 being provided for manufacturing purposes only so to allow a sacrificial etchant to easily etch away the internal portions of nozzle chamber 10. The etchant ports 18 are of a sufficiently small diameter so that the resulting surface tension holds the ink within chamber 10 such that no ink leaks out via ports 18.

The thermal actuator 16 is composed primarily of polytetrafluoroethylene (PTFE) which is a generally hydrophobic material. The top layer of the actuator 16 is treated or coated so as to make it hydrophilic and thereby attract water/ink via inlet port 12. Suitable treatments include plasma exposure in an ammonia atmosphere. The bottom surface remains hydrophobic and repels the water from the underneath surface of the actuator 16. Underneath the actuator 16 is provided a further surface 19 also composed of a hydrophobic material such as PTFE. The surface 19 has a series of holes 20 in it which allow for the flow of air into the nozzle chamber 10. The diameter of the nozzle holes 20 again being of such a size so as to restrict the flow of fluid out of the nozzle chamber via surface tension interactions. out of the nozzle chamber.

The surface 19 is separated from a lower level 23 by means of a series of spaced apart posts e.g. 22 which can be constructed when constructing the layer 19 utilising an appropriate mask. The nozzle chamber 10, but for grill inlet port 12, is walled on its sides by silicon nitride walls e.g. 25,26. An air inlet port is formed between adjacent nozzle chambers such that air is free to flow between the walls 25,28. Hence, air is able to flow down channel 29 and along channel 30 and through holes e.g. 20 in accordance with any fluctuating pressure influences.

The air flow acts to reduce the vacuum on the back surface of actuator 16 during operation. As a result, less energy is required for the movement of the actuator 16. In operation, the actuator 16 is thermally actuated so as to move upwards and cause ink ejection. As a result, air flows in along channels 29,30 and through the holes e.g. 20 into the bottom area of actuator 16. Upon deactivation of the actuator 16, the actuator lowers with a corresponding airflow out of port 20 along channel 30 and out of channel 29. Any fluid within nozzle chamber 10 is firstly repelled by the hydrophobic nature of the bottom side of the surface of actuator 16 in addition to the top of the surface 19 which is again hydrophobic. As noted previously the limited size holes e.g. 20 further stop the fluid from passing the holes 20 as a result of surface tension characteristics.

A further preferable feature of nozzle chamber 10 is the utilisation of the nitride posts 14 to also clamp one end of the surfaces 16 and 19 firmly to bottom surface 20 thereby reducing the likelihood delaminating during operation.

In FIG. 2, there is illustrated an exploded perspective view of a single nozzle arrangement 10. The exploded perspective view illustrates the form of construction of each layer of a simple nozzle arrangement 10. The nozzle arrangement can be constructed on a base silicon wafer 34 having a top glass layer which includes the various drive and control circuitry and which, for example, can comprise a two level metal CMOS layer with the various interconnects (not shown). On top of the layer 35 is first laid out a nitride passivation layer 23 of approximately one micron thickness which includes a number of vias (not shown) for the interconnection of the subsequent layers to the CMOS layer 35. The nitride layer is provided primarily to protect lower layers from corrosion or etching, especially where sacrificial etchants are utilized. Next, a one micron PTFE layer 19 is constructed having the aforementioned holes e.g. 20 and posts 22. The structure of the PTFE layer 19 can be formed by first laying down a sacrificial glass layer (not shown) onto which the PTFE layer 19 is deposited. The PTFE layer 19 includes various features, for example, a lower ridge portion 38 in addition to a hole 39 which acts as a via for the subsequent material layers.

The actuator proper is formed from two PTFE layers 40,41. The lower PTFE layer 40 is made conductive. The PTFE layer 40 can be made conductive utilising a number of different techniques including:

(i) Doping the PTFE layer with another material so as to make it conductive.

(ii) Embedding within the PTFE layer a series of quantum wires constructed from such a material as carbon nano-tubes created in a mesh form. ("Individual single-wall carbon nano-tubes as quantum wires" by Tans et al Nature, Volume 386, 3rd April 1997 at pages 474-477). The PTFE layer 40 includes tubes certain cut out portions e.g. 43 so that a complete circuit is formed around the PTFE actuator 40. The cut out portions can be optimised so as to regulate the resistive heating of the layer 40 by means of providing constricted portions so as to thereby increase the heat generated in various "hot spots" as required. A space is provided between the PTFE layer 19 and the PTFE layer 40 through the utilisation of an intermediate sacrificial glass layer (not shown).

On top of the PTFE layer 40 is deposited a second PTFE layer 41 which can be a standard non conductive PTFE layer and can include filling in those areas in the lower PTFE layer e.g. 43 which are not conductive. The top of the PTFE layer is further treated or coated to make it hydrophilic.

Next, a nitride layer can be deposited to form the nozzle chamber proper. The nitride layer can be formed by first laying down a sacrificial glass layer and etching the glass layer to form walls e.g. 25, 26 and grilled portion e.g. 14. Preferably, the mask utilised results a first anchor portion 45 which mates with the hole 39 in layer 19 so as to fix the layer 19 to the nitride layer 23. Additionally, the bottom surface of the grill 14 meets with a corresponding step 47 in the PTFE layer 41 so as to clamp the end portion of the PTFE layers 41,40 and 39 to the wafer surface so as to guard against delamination. Next, a top nitride layer 50 can be formed having a number of holes e.g. 18 and nozzle hole 11 around which a rim can be etched through etching of the nitride layer 50. Subsequently, the various sacrificial layers can be etched away so as to release the structure of the thermal actuator.

Obviously, large arrays of inkjet nozzles 10 can be created side by side on a single wafer. The ink can be supplied via ink channels etched through the wafer utilising a high density low pressure plasma etching system such as that supplied by Surface Technology Systems of the United Kingdom.

The foregoing describes only one embodiment of the invention and many variations of the embodiment will be obvious for a person skilled in the art of semi conductor, micro mechanical fabrication. Certainly, various other materials can be utilised in the construction of the various layers.

It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiment without departing from the spirit or scope of the invention as broadly described. The present embodiment is, therefore, to be considered in all respects to be illustrative and not restrictive.

Ink Jet Technologies

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.

The most significant problem with thermal inkjet 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 inkjet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric inkjet 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 print head, but is a major impediment to the fabrication of pagewide print heads with 19,200 nozzles.

Ideally, the inkjet 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 inkjet technologies have been created. The target features include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the inkjet systems described below with differing levels of difficulty. 45 different inkjet 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 below.

The inkjet 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

For ease of manufacture using standard process equipment, the print head is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For color photographic applications, the print head is 100 mm long, with a width which depends upon the inkjet type. The smallest print head designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square mm. The print heads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the print head 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 print head is connected to the camera circuitry by tape automated bonding.

Cross-Referenced Applications

The following table is a guide to cross-referenced patent applications filed concurrently herewith and discussed hereinafter with the reference being utilized in subsequent tables when referring to a particular case:

Tables of Drop-on-Demand Inkjets

Eleven important characteristics of the fundamental operation of individual inkjet 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.

The following tables form the axes of an eleven dimensional table of inkjet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of inkjet nozzle. While not all of the possible combinations result in a viable inkjet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain inkjet types have been investigated in detail. These are designated IJ01 to IJ45 above.

Other inkjet configurations can readily be derived from these 45 examples by substituting alternative configurations along one or more of the 11 axes. Most of the IJ01 to IJ45 examples can be made into inkjet print heads with characteristics superior to any currently available inkjet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The IJ01 to IJ45 series are also listed in the examples column. In some cases, a printer may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications 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 printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix are set out in the following tables. - Description Advantages Disadvantages Examples ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Actuator Mechanism Thermal An electrothermal heater heats the .diamond-solid.Large force generated .diamond-solid.High power .diamond-solid.Canon Bubblejet bubble ink to above boiling point, .diamond-solid.Simple construct ion .diamond-solid.Ink carrier limited to water 1979 Endo et al GB transferring significant heat to the .diamond-solid.No moving parts .diamond-solid.Low efficiency patent 2,007,162 aqueous ink. A bubble nucleates and .diamond-solid.Fast operation .diamond-solid.High temperatures required .diamond-solid.Xerox heater-in- pit quickly forms, expelling the ink. .diamond-solid.Small chip area required for .diamond-solid.High mechanical stress 1990 Hawkins et al The efficiency of the process is low, actuator .diamond-solid.Unusua l materials required U.S. Pat. No. 4,899,181 with typically less than 0.05% of the .diamond-solid.Large drive transistors .diamond-solid.Hewlett-Packard TIJ electrical energy being transformed .diamond-solid.Cavitation causes actuator failure 1982 Vaught et al into kinetic energy of the drop. .diamond-solid.Kogation reduces bubble formation U.S. Pat. No. 4,490,728 .diamond-solid.Large print heads are difficult to fabricate Piezoelectric A piezoelectric crystal such as lead .diamond-solid.Low power consumption. .diamond-solid.Very large area required for actuator .diamond-solid.Kyser et al U.S. Pat. No. lanthanum zirconate (PZT) is .diamond-solid.Many ink types can be used .diamond-solid.Difficult to integrate with electronics 3,946,398 electrically activated, and either .diamond-solid.Fast operation .diamond-solid.High voltage drive transistors .diamond-solid.Zoltan U.S. Pat. No. expands, shears, or bends to apply .diamond-solid.High efficiency required 3,683,212 pressure to the ink, ejecting drops. .diamond-solid.Full pagewidth print heads impractical .diamond-solid.1973 Stemme U.S. Pat. No. due to actuator size 3,747,120 .diamond-solid.Requires electrical poling in high field .diamond-sol id.Epson Stylus strengths during manufacture .diamond-solid.Tektronix .diamond-solid.IJ04 Electro- An electric field is used to activate .diamond-solid.Low power consumption .diamond-solid.Low maximum strain (approx. 0.01%) .diamond-solid.Seiko Epson, Usui et strictive electrostriction in relaxor materials .diamond-solid.Many ink types can be used .diamond-solid.Large area required for actuator all JP 253401/96 such as lead lanthanum zirconate .diamond-solid.Low thermal expansion due to low strain .diamond-solid.IJ04 titanate (PLZT) or lead magnesium .diamond-solid.Electric field strength .diamond-solid.Response speed is marginal (.about.10 .mu.s) niobate (PMN). required (approx. 3.5 V/.mu.m) .diamond-solid.High voltage drive transistors required can be generated without .diamond-solid.Full pagewidth print heads impractical difficulty due to actuator size .diamond-solid.Does not require electrical poling Ferroelectric An electric field is used to induce a .diamond-solid.Low power consumption .diamond-solid.Difficult to integrate with electronic s .diamond-solid.IJ04 phase transition between the .diamond-solid.Many ink types can be used .diamond-solid.Unusual materials such as PLZSnT are antiferroelectric (AFE) and .diamond-solid.Fast operation (<1 .mu.s) required ferroelectric (FE) phase. Perovskite .diamond-solid.Relatively high longitudinal .diamond-solid.Actuators require a large area materials such as tin modified lead strain lanthanum zirconate titanate .diamond-solid.High efficiency (PLZSnT) exhibit large strains of up .diamond-solid.Electric field strength of to 1% associated with the AFE to FE around 3 V/.mu.m can be phase transition, readily provided Electrostatic Conductive plates are separated by a .diamond-solid.Low power consumption .diamond-solid.Difficult to operate electrostatic .diamond-solid.IJ02, IJ04 plates compressible or fluid dielectric .diamond-solid.Many ink types can be used devices in an aqueous environment (usually air). Upon application of a .diamond-solid.Fast operation .diamond-solid.The electrostatic actuator will normally voltage, the plates attract each other need to be separated from the ink and displace ink, causing drop .diamond-solid.Very large area required to achieve ejection. The conductive plates may high forces be in a comb or honeycomb .diamond-solid.High voltage drive transisto rs may be structure, or stacked to increase the required surface area and therefore the force. .diamond-solid.Full pagewidth print heads are not competitive due to actuator size Electrostatic A strong electric field is applied to .diamond-solid.Low current consumption .diamond-solid.High voltage required .diamond-solid .1989 Saito et al, U.S. Pat. No. pull on ink the ink, whereupon electrostatic .diamond-solid.Low temperature .diamond-solid.May be damaged by sparks due to air 4,799,068 attraction accelerates the ink towards breakdown .diamond-solid.1989 Miura et al, the print medium. .diamond-solid.Required field strength increases as the U.S. Pat. No. 4,810,954 drop size decreases .diamond-solid.Tone-jet .diamond-solid.High voltage drive transistors required .diamond-solid.Electrostatic field attracts dust Permanent An electromagnet directly attracts a .diamond-solid.Low power consumption .diamond-solid.Complex fabrication .diamond-solid.IJ07, IJ10 magnet permanent magnet, displacing ink .diamond-solid.Many ink types can be used .diamond-solid.Permanent magnetic material such as electro- and causing drop ejection. Rare earth .diamond-solid.Fast operation Neodymium Iron Boron (NdFeB) magnetic magnets with a field strength around .diamond-solid.High efficiency required. 1 Tesla can be used. Examples are: .diamond-solid.Easy extension from single .diamond-solid.High local currents required Samarium Cobalt (SaCo) and nozzles to pagewidth print .diamond-solid.C opper metalization should be used for magnetic materials in the heads long electromigration lifetime and low neodymium iron boron family resistivity (NdFeB, NdDyFeBNb, NdDyFeB, .diamond-solid.Pigmented inks are usually infeasible etc) .diamond-solid.Operating temperature limited to the Curie temperature (around 540 K) Soft magnetic A solenoid induced a magnetic field .diamond-solid.Low power consumption .diamond-solid.Complex fabrication .diamond-solid.IJ01, IJ05, IJ08, IJ10 core electro- in a soft magnetic core or yoke .diamond-solid.Many ink types can be used .diamond-solid.Materials not usually present in a .diamond-solid.IJ12, IJ14, IJ15, IJ17 magnetic fabricated from a ferrous material .diamond-solid.Fast operation CMOS fab such as NiFe, CoNiFe, or such as electroplated iron alloys such .diamond-solid.High efficiency CoFe are required as CoNiFe [1], CoFe, or NiFe alloys. .diamond-solid.Easy extension from single .diamond-solid.High local currents required Typically, the soft magnetic material nozzles to pagewidth print .diamond-solid.Copper metalization should be used for is in two parts; which are normally heads long electromigration lifetime and low held apart by a spring. When the resistivity solenoid is actuated, the two parts .diamond-solid.Electroplating is required attract, displacing the ink. .diamond-solid.High saturation flux density is required (2.0-2.1 T is achievable with CoNiFe [1]) Magnetic The Lorenz force acting on a current .diamond-solid.Low power consumption .diamond-solid.Force acts as a twisting motion .diamond-sol id.IJ06, IJ11, IJ13, IJ16 Lorenz force carrying wire in a magnetic field is .diamond-solid.Many ink types can be used .diamond-solid.Typically, only a quarter of the utilized. .diamond-solid.Fast operation solenoid length provides force in a This allows the magnetic field to be .diamond-solid.High efficiency useful direction supplied externally to the print head, .diamond-solid.Easy extension from single .diamond-solid.High local currents required for example with rare earth nozzles to pagewidth print .diamond-solid. Copper metalization should be used for permanent magnets. heads long electromigration lifetime and low Only the current carrying wire need resistivity be fabricated on the print-head, .diamond-solid.Pigmented inks are usually infeasible simplifying materials requirements. Magneto- The actuator uses the giant .diamond-solid.Many ink types can be used .diamond-solid.Force acts as a twisting motion .diamond-solid.F ischenbeck, U.S. Pat. No. striction magnetostrictive effect of materials .diamond-solid.Fast operation .diamond-solid.Unusual materials such as Terfenol-D 4,032,929 such as Terfenol-D (an alloy of .diamond-solid.Easy extension from single are required .diamond-solid.IJ25 terbium, dysprosium and iron nozzles to pagewidth print .diamond-solid .High local currents required developed at the Naval Ordnance heads .diamond-solid.Copper metalizati on should be used for Laboratory, hence Ter-Fe-NOL). For .diamond-solid.High force is available long electromigration lifetime and low best efficiency, the actuator should resistivity be pre-stressed to approx. 8 MPa. .diamond-solid.Pre-stressing may be required Surface Ink under positive pressure is held in .diamond-solid.Low power consumption .diamond-solid.Requires. supplementary force to effect .diamond-solid.Silverbrook, EP 0771 tension a nozzle by surface tension. The .diamond-solid.Simple construction drop separation 658 A2 and related reduction surface tension of the ink is reduced .diamond-solid.No unusual materials .diamond-solid.Requires special ink surfactants patent applications below the bubble threshold, causing required in fabrication .diamond-s olid.Speed may be limited by surfactant the ink to egress from the nozzle. .diamond-solid.High efficiency properties .diamond-solid.Easy extension from single nozzles to pagewidth print heads Viscosity The ink viscosity is locally reduced .diamond-solid.Simple construction .diamond-solid.Requires supplementary force to effect .diamond-solid.Silverbrook, EP 0771 reduction to select which drops are to be .diamond-solid.No unusual materials drop separation 658 A2 and related ejected. A viscosity reduction can be required in fabrication .diamond-solid.Requires special ink viscosity patent applications achieved electrothermally with most .diamond-solid.Easy extension from single properties inks, but special inks can be nozzles to pagewidth print .diamond-soli d.High speed is difficult to achieve engineered for a 100:1 viscosity heads .diamond-solid.Requires oscillating ink pressure reduction. .diamond-solid.A high temperature difference (typically 80 degrees) is required Acoustic An acoustic wave is generated and .diamond-solid.Can operate without a .diamond-solid.Complex drive circuitry .diamond-solid.1993 Hadimioglu et focused upon the drop ejection nozzle plate. .diamond-solid.Complex fabrication al, EUP 550,192 region. .diamond-solid.Low efficiency .diamond-solid.1993 Elrod et al, EUP .diamond-solid.Poor control of drop position 572,220 .diamond-solid.Poor control of drop volume Thermoelastic An actuator which relies upon .diamond-solid.Low power consumption .diamond-solid.Efficient aqueous operation requires a .diamond-solid.IJ03, IJ09, IJ17, IJ18 bend actuator differential thermal expansion upon .diamond-solid.Many ink types can be used thermal insulator on the hot side .diamond-solid.IJ 19, IJ20, IJ21, IJ22 Joule heating is used. .diamond-solid.Simple planar fabrication .diamond-solid.Corrosion prevention can be difficult .diamond-solid.IJ23, IJ24, IJ27, IJ28 .diamond-solid.Small chip area required for .diamond-solid.Pigmented inks may be infeasible, as .diamond-solid.IJ29, IJ30, IJ31, IJ32 each actuator pigment particles may jam the bend .diamond-solid. IJ33, IJ34, IJ35, IJ36 .diamond-solid.Fast operation actuator .diamond-solid.IJ37, IJ38, IJ39, IJ40 .diamond-solid.High efficiency .diamond-solid.IJ41 .diamond-solid.CMOS compatible voltages and currents .diamond-solid.Standard MEMS processes can be used .diamond-solid.Easy extension from single nozzles to pagewidth print heads High CTE A material with a very high .diamond-solid.High force can be generated .diamond-solid.Requires special material (e.g. PTFE) .diamond-s olid.IJ09, IJ17, IJ18, IJ20 thermoelastic coefficient of thermal expansion .diamond-solid.PTFE is a candidate for low .diamond-solid.Requires a PTFE deposition process, .diamond-solid.IJ21, IJ22, IJ23, IJ24 actuator (CTE) such as dielectric constant which is not yet standard in ULSI fabs .diamond-solid.IJ27, IJ28, IJ29, IJ30 polytetrafluoroethylene (PTFE) is insulation in ULSI .diamond-solid.PT FE deposition cannot be followed .diamond-solid.IJ31, IJ42, IJ43, IJ44 used. As high CTE materials are .diamond-solid.Very low power with high temperature (above 350.degree. C.) usually non-conductive, a heater consumption processing fabricated from a conductive .diamond-solid.Many ink types can be used .diamond-solid.Pigmented inks may be infeasible, as material is incorporated. A 50 .mu.m .diamond-solid.Simple planar fabrication pigment particles may jam the bend long PTFE bend actuator with .diamond-solid.Small chip area required for actuator polysilicon heater and 15 mW power each actuator input can provide 180 .mu.N force and .diamond-solid.Fast operation 10 .mu.m deflection. Actuator motions .diamond-solid.High efficiency include: CMOS compatible voltages 1) Bend and currents 2) Push .diamond-solid.Easy extension from single 3) Buckle nozzles to pagewidth print 4) Rotate heads Conductive A polymer with a high coefficient of .diamond-solid.High force can be generated .diamond-solid.Requires special materials .diamond-solid.IJ24 polymer thermal expansion (such as PTFE) is .diamond-solid.Very low power development (High CTE conductive thermoelastic doped with conducting substances to consumption polymer) actuator. increase its conductivity to about 3 .diamond-solid.Many ink types can be used .diamond-solid.Requires a PTFE deposition process, orders of magnitude below that of .diamond-solid.Simple planar fabrication which is not yet standard in ULSI fabs copper. The conducting polymer .diamond-solid.Small chip area required for .diamond-solid.PTFE deposition cannot be followed expands when resistively heated. each actuator with high temperature (above 350.degree. C.) Examples of conducting dopants .diamond-solid.Fast operation processing include: .diamond-solid.High efficiency .diamond-solid.Evaporation and CVD deposition 1) Carbon nanotubes .diamond-solid.CMOS compatible voltages techniques cannot be used 2) Metal fibers and currents .diamond-solid.Pigmented inks may be infeasible, as 3) Conductive polymers such as .diamond-solid.Easy extension from single pigment particles may jam the bend doped polythiophene nozzles to pagewidth print actuator 4) Carbon granules heads Shape memory A shape memory alloy such as TiNi .diamond-solid.High force is available .diamond-solid.Fatigue limits maximum number of .diamond-solid.IJ26 alloy (also known as Nitinol - Nickel (stresses of hundreds of cycles Titanium alloy developed at the MPa) .diamond-solid.Low strain (1%) is required to extend Naval Ordnance Laboratory) is .diamond-solid.Large strain is available fatigue resistance thermally switched between its weak (more than 3%) .diamond-solid.Cycl e rate limited by heat removal martensitic state and its high .diamond-solid.High corrosion resistanc e .diamond-solid.Requires unusual materials (TiNi) stiffness austenic state. The shape of .diamond-solid.Simple construct ion .diamond-solid.The latent heat of transformation must the actuator in its martensitic state is .diamond-solid.Easy extension from single be provided deformed relative to the austenic nozzles to pagewidth print .diamond- solid.High current operation shape. The shape change causes heads .diamond-solid.Requires pre-stres sing to distort the ejection of a drop. .diamond-solid.Low voltage operation martensitic state Linear Linear magnetic actuators include .diamond-solid.Linear Magnetic actuators .diamond-solid.Requires unusual semiconductor .diamond-solid.IJ12 Magnetic the Linear Induction Actuator (LIA), can he constructed with materials such as soft magnetic alloys Actuator Linear Permanent Magnet high thrust, long travel, and (e.g. CoNiFe [1]) Synchronous Actuator (LPMSA), high efficiency using planar .diamond-so lid.Some varieties also require permanent Linear Reluctance Synchronous semiconductor fabrication magnetic materials such as Actuator (LRSA), Linear Switched techniques Neodymium iron boron (NdFeB) Reluctance Actuator (LSRA), and .diamond-solid.Long actuator travel is .diamond-solid.Requires complex multi-phase drive the Linear Stepper Actuator (LSA). available circuitry .diamond-solid.Medium force is available .diamond-solid.High current operation .diamond-solid.Low voltage operation BASIC OPERATION MODE Operational mode Actuator This is the simplest mode of .diamond-solid.Simple operation .diamond-solid.Drop repetition rate is usually limited .diamond-solid.The rmal inkjet directly operation: the actuator directly .diamond-solid.No external fields required to less than 10 KHz. However, this is .diamond-solid.Piez oelectric inkjet pushes ink supplies sufficient kinetic energy to .diamond-solid.Satelli te drops can be not fundamental to the method, but is .diamond-solid.IJ0 1, IJ02, IJ03, IJ04 expel the drop. The drop must have a avoided if drop velocity is related to the refill method normally .diamond-solid.IJ05, IJ06, IJ07, IJ09 sufficient velocity to overcome the less than 4 m/s used .diamond-soli d.IJ11, IJ12, IJ14, IJ16 surface tension .diamond-solid.Can be efficient, depending .diamond-so lid.All of the drop kinetic energy must be .diamond-solid.IJ20, IJ22, IJ23, IJ24 upon the actuator used provided by the actuator .diamond-solid.IJ25, IJ26, IJ27, IJ28 .diamond-solid.Satellite drops usually form if drop .diamond-solid.I J29, IJ30, IJ31, IJ32 velocity is greater than 4.5 m/s .diamond-solid.IJ33, IJ34, IJ35, IJ36 .diamond-solid.IJ37, IJ38, IJ39, IJ40 .diamond-solid.IJ41, IJ42, IJ43, IJ44 Proximity The drops to be printed are selected .diamond-solid.Very simple print head .diamond-solid.Requires close proximity between the .diamond-solid.Silverbrook, EP 0771 by some manner (e.g. thermally fabrication can be used print head and the print media or 658 A2 and related induced surface tension reduction of .diamond-solid.The drop selection means transfer roller patent applications pressurized ink). Selected drops are does not need to provide the .diamond-solid.May require two print heads printing separated from the ink in the nozzle energy required to separate alternate rows of the image by contact with the print medium or the drop from the nozzle .diamond- solid.Monolithic color print heads are a transfer roller. difficult Electrostatic The drops to be printed are selected .diamond-solid.Very simple print head .diamond-solid.Requires very high electrostatic field .diamond-solid.Silverbrook, EP 077 pull on ink by some manner (e.g. thermally fabrication can be used .diamond-solid.Electrostatic field for small nozzle 658 A2 and related induced surface tension reduction of .diamond-solid.The drop selection means sizes is above air breakdown patent applications pressurized ink). Selected drops are does not need to provide the .diamond-solid.Electrostatic field may attract dust .diamond-solid.To ne-Jet separated from the ink in the nozzle energy required to separate by a strong electric field. the drop from the nozzle Magnetic pull The drops to be printed are selected .diamond-solid.Very simple print head .diamond-solid.Requires magnetic ink .diamond-solid.S ilverbrook, EP 0771 on ink by some manner (e.g. thermally fabrication can be used .diamond- solid.Ink colors other than black are difficult 658 A2 and related induced surface tension reduction of .diamond-solid.The drop selection means .diamond-solid.Requires very high magnetic fields patent applications pressurized ink). Selected drops are does not need to provide the separated from the ink in the nozzle energy required to separate by a strong magnetic held acting on the drop from the nozzle the magnetic ink. Shutter The actuator moves a shutter to .diamond-solid.High speed (>50 KHz) .diamond-solid.Moving parts are required .diamond-solid.IJ13, IJ17, IJ21 block ink flow to the nozzle. The ink operation can be achieved .diamond-solid.Requires ink pressure modulator pressure is pulsed at a multiple of the due to reduced refill time .diamond-solid.Friction and wear must be considered drop ejection frequency. .diamond-solid.Drop timing can be very .diamond-solid.Stiction is possible accurate .diamond-solid.The actuator energy can be very low Shuttered grill The actuator moves a shutter to .diamond-solid.Actuator s with small travel .diamond-solid.Moving parts are required .diamond-so lid.IJ08, IJ15, IJ18, IJ19 block ink flow through a grill to the can be used .diamond-solid.Requi res ink pressure modulator nozzle. The shutter movement need .diamond-solid.Actuators with small force .diamond-solid.Friction and wear must be considered only be equal to the width of the grill can be used .diamond-solid.Sti ction is possible holes. .diamond-solid.High speed (>50 KHz) operation can be achieved Pulsed A pulsed magnetic field attracts an .diamond-solid.Extremely low energy .diamond-solid.Requires an external pulsed magnetic .diamond-s olid.IJ10 magnetic pull `ink pusher` at the drop ejection operation is possible field on ink pusher frequency. An actuator controls a .diamond-solid.No heat dissipation .diamond-solid.Requires special materials for both the catch, which prevents the ink pusher problems actuator and the ink pusher from moving when a drop is not to .diamond-solid.Complex construction be ejected. AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Auxiliary Mechanism None The actuator directly fires the ink .diamond-solid.Simplicity of construction .diamond-solid.Drop ejection energy must be supplied .diamond-solid.Most inkjets, drop, and there is no external field or .diamond-solid.Simplicity of operation by individual nozzle actuator including other mechanism required .diamond-solid.Small physical size piezoelec tric and thermal bubble. .diamond-solid.IJ01-IJ07, IJ09, IJ11 .diamond-solid.IJ12, IJ14, IJ20, IJ22 .diamond-solid.IJ23-IJ45 Oscillating ink The ink pressure oscillates, .diamond-solid.Oscillating ink pressure can .diamond-solid.Requires external ink pressure .diamond-solid.Silverbrook, EP 0771 pressure providing much of the drop ejection provide a refill pulse, oscillator 658 A2 and related (including energy. The actuator selects which allowing higher operating .diamond-solid.Ink pressure phase and amplitude must patent application s acoustic drops are to be fired by selectively speed be carefully controlled .diamond-solid.IJ08, IJ13, IJ15, IJ17 stimulation) blocking or enabling nozzles. The .diamond-solid.The actuators may operate .diamond-solid.Acoustic reflections in the ink chamber .diamond-solid.IJ18, IJ19, IJ21 ink pressure oscillation may he with much tower energy must be designed for achieved by vibrating the print head, .diamond-solid.Acoustic lenses can be used or preferably by an actuator in the to focus the sound on the ink supply. nozzles Media The print head is placed in close .diamond-solid.Low power .diamond-solid.Precision assembly required .diamond-solid.Silverbrook, EP 0771 proximity proximity to the print medium. .diamond-solid.High accuracy .diamond-solid.Paper fibers may cause problems 658 A2 and related Selected drops protrude from the .diamond-solid.Simple print head .diamond-solid.Cannot print on rough substrates patent applications print head further than unselected construction drops, and contact the print medium. The drop soaks into the medium fast enough to cause drop separation. Transfer roller Drops are printed to a transfer roller .diamond-solid.H igh accuracy .diamond-solid.Bulky .diamond-solid.Silverbrook, EP 0771 instead of straight to the print .diamond-solid.Wide range of print .diamond-solid.Expensive 658 A2 and related medium. A transfer roller can also be substrates can be used .diamond- solid.Complex construction patent applications used for proximity drop separation. .diamond-solid.Ink can be dried on the .diamond-solid.Tektronix hot melt transfer roller piezoelectric inkjet .diamond-solid.Any of the IJ series Electrostatic An electric field is used to accelerate .diamond-solid.Lo w power .diamond-solid.Field strength required for separation .diamond-s olid.Silverbrook, EP 0771 selected drops towards the print .diamond-solid.Simple print head of small drops is near or above air 658 A2 and related medium. constriction breakdown patent applications .diamond-solid.Tone-Jet Direct A magnetic field is used to accelerate .diamond-solid.Low power .diamond-solid.Requires magnetic ink .diamond-solid.Silverbrook, EP 0771 magnetic field selected drops of magnetic ink .diamond-solid.Simple print head .diamond-solid.Requires strong magnetic field 658 A2 and related towards the print medium. construction patent applications Cross The print head is placed in a constant .diamond-solid.Does not require magnetic .diamond-solid.Requires external magnet .diamond-solid.I J06, IJ16 magnetic field magnetic field. The Lorenz force in a materials to be integrated in .diamond-solid.Current densities may be high, current carrying wire is used to move the print head resulting in electromigration problems the actuator. manufacturing process Pulsed A pulsed magnetic field is used to .diamond-solid.Very low power operation .diamond-solid.Complex print head construction .diamond-s olid.IJ10 magnetic field cyclically attract a paddle, which is possible. .diamond-solid.Magnetic materials required in print pushes on the ink. A small actuator .diamond-solid.Small print head size head moves a catch, which selectively prevents the paddle from moving. ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Actuator amplification None No actuator mechanical .diamond-solid.Operational simplicity .diamond-solid.Many actuator mechanisms have .diamond-solid.Thermal Bubble amplification is used. The actuator insufficient travel, or insuffici ent force, Inkjet directly drives the drop ejection to efficiently drive the drop ejection .diamond-solid.IJ01, IJ02, IJ06, IJ07 process. process .diamond-solid.IJ16, IJ25, IJ26 Differential An actuator material expands more .diamond-solid.Provides greater travel in a .diamond-solid.High stresses are involved .diamond- solid.Piezoelectric expansion on one side than on the other. The reduced print head area .diamond-solid.Care must be taken that the materials .diamond-solid.IJ03, IJ09, IJ17-IJ24 bend actuator expansion may be thermal, .diamond-solid.The bend actuator converts do not delaminate .diamond-solid.IJ27, IJ29-IJ39 IJ42, piezoelectric, magnetostrictive, or a high force low travel .diamond-s olid.Residual bend resulting from high .diamond-solid.IJ43, IJ44 other mechanism. actuator mechanism to high temperature or high stress during travel, lower force formation mechanism. Transient bend A trilayer bend actuator where the .diamond-solid.Very good temperature .diamond-solid.High stresses are involved .diamond-solid .IJ40, IJ41 actuator two outside layers are identical. This stability .diamond-soli d.Care must be taken that the materials cancels bend due to ambient .diamond-solid.High speed, as a new drop do not delaminate temperature and residual stress. The can be fired before heat actuator only responds to transient dissipates heating of one side or the other. .diamond-solid.Cancels residual stress of formation Actuator stack A series of thin actuators are stacked. .diamond-solid.I ncreased travel .diamond-solid.Increased fabrication complexity .diamond-solid.Some piezoelectric This can be appropriate where .diamond-solid.Reduced drive voltage .diamond-solid.Increased possibility of short circuits ink jets actuators require high electric field due to pinholes .diamond-solid. IJ04 strength, such as electrostatic and piezoelectric actuators. Multiple Multiple smaller actuators are used .diamond-solid.Increases the force available .diamond-solid.Actuator forces may not add linearly, .diamond-solid.IJ12, IJ13, IJ18, IJ20 actuators simultaneously to move the ink. from an actuator reducing efficiency .diamond-solid.IJ22, IJ28, IJ42, IJ43 Each actuator need provide only a .diamond-solid.Multiple actuators can be portion of the force required. positioned to control ink flow accurately Linear Spring A linear spring is used to transform a .diamond-solid.Mat ches low travel actuator .diamond-solid.Requires print head area for the spring .diamond-solid.IJ15 motion with small travel and high with higher travel force into a longer travel, lower force requirements motion. .diamond-solid.Non-contact method of motion transformation Reverse spring The actuator loads a spring. When .diamond-solid.Better coupling to the ink .diamond-solid.Fabrication complexity .diamond-soli d.IJ05, IJ11 the actuator is tuned off, the spring .diamond-solid.High stress in 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. Coiled A bend actuator is coiled to provide .diamond-solid.Increases travel .diamond-solid.Generally restricted to planar .diamond-solid.IJ17, IJ21, IJ34, IJ35 actuator greater travel in a reduced chip area. .diamond-solid.Reduces chip area implementations due to extreme .diamond-solid.Planar implementations are fabrication difficulty in other relatively easy to fabricate. orientations. Flexure bend A bend actuator has a small region .diamond-solid.Simple means of increasing .diamond-solid.Care must be taken not to exceed the .diamond-solid.IJ10, IJ19, IJ33 actuator near the fixture point, which flexes travel of a bend actuator elastic limit in the flexure area much more readily than the .diamond-solid.Stress distribution is very uneven remainder of the actuator. The .diamond-solid.Difficult to accurately model with actuator flexing is effectively finite element analysis converted from an even coiling to an angular bend, resulting in greater travel of the actuator tip. Gears Gears can be used to increase travel .diamond-solid.Low force, low travel .diamond-solid.Moving parts are required .diamond-solid.IJ13 at the expense of duration. Circular actuators can be used .diamond-so lid.Several actuator cycles are required gears, rack and pinion, ratchets, and .diamond-solid.Can be fabricated using .diamond-solid.More complex drive electronics other gearing methods can be used. standard surface MEMS .diamond-soli d.Complex construction processes .diamond-solid.Friction, friction, and wear are possible Catch The actuator controls a small catch. .diamond-solid.Very low actuator energy .diamond-solid.Complex construction .diamond-solid.IJ10 The catch either enables or disables .diamond-solid.Very small actuator size .diamond-solid.Requires external force movement of an ink pusher that is .diamond-solid.Unsuitable for pigmented inks controlled in a bulk manner. Buckle plate A buckle plate can be used to change .diamond-solid.Very fast movement .diamond-solid.Must stay within elastic limits of the .diamond-solid.S. Hirata et al, "An a slow actuator into a fast motion. It achievable materials for long device life Ink-jet Head . . . ", can also convert a high force, low .diamond-solid.High stresses involved Proc. IEEE MEMS, travel actuator into a high travel, .diamond-solid.Generally high power requirement Feb. 1996, pp 418- medium force motion. 423. .diamond-solid.IJ18, IJ27 Tapered A tapered magnetic pole can increase .diamond-solid.Linearizes the magnetic .diamond-solid.Complex construction .diamond-solid.IJ14 magnetic pole travel at the expense of force. force/distance curve Lever A lever and fulcrum is used to .diamond-solid.Matches low travel actuator .diamond-solid.High stress around the fulcrum .diamond-so lid.IJ32, IJ36, IJ37 transform a motion with small travel with higher travel and high force into a motion with requirements longer travel and lower force. The .diamond-solid.Fulcrum area has no linear lever can also reverse the direction of movement, and can be used travel. for a fluid seal Rotary The actuator is connected to a rotary .diamond-solid.High mechanical advantage .diamond-solid.Complex construction .diamond-solid.I J28 impeller impeller. A small angular deflection .diamond-solid.The ratio of force to travel .diamond-solid.Unsuitable for pigmented inks of the actuator results in a rotation of of the actuator can be the impeller vanes, which push the matched to the nozzle ink against stationary vanes and out requirements by varying the of the nozzle. number of impeller vanes Acoustic lens A refractive or diffractive (e.g. zone .diamond-solid.No moving parts .diamond-solid.Large area required .diamond-solid.1993 Hadimioglu et plate) acoustic lens is used to .diamond-solid.Only relevant for acoustic ink jets al, EUP 550, 192 concentrate sound waves. .diamond-solid.1993 Elrod et al, EUP 572,220 Sharp A sharp point is used to concentrate .diamond-solid.Simple construction .diamond-solid.Difficult to fabricate using standard .diamond-solid.Tone-jet conductive an electrostatic field. VLSL processes for a surface ejecting point ink-jet .diamond-solid.Only relevant for electrostatic ink jets ACTUATOR MOTION Actuator motion Volume The volume of the actuator changes, .diamond-solid.Simple construction in the .diamond-solid.High energy is typically required to .diamond-solid.Hewlett-Packard expansion pushing the ink in all directions. case of thermal ink jet achieve volume expansion. This leads Thermal Inkjet to thermal stress, cavitation, and .diamond-solid.Canon Bubblejet kogation in thermal ink jet implementations Linear, normal The actuator moves in a direction .diamond-solid.Efficie nt coupling to ink .diamond-solid.High fabrication complexity may be .diamond-solid.IJ01, IJ02, IJ04, IJ07 to chip surface normal to the print head surface. The drops ejected normal to the required to achieve perpendicular .diamond-solid.IJ11, IJ14 nozzle is typically in the line of surface motion movement. Linear, parallel The actuator moves parallel to the .diamond-solid.Suit able for planar .diamond-solid.Fabrication complexity .diamond-solid.IJ1 2, IJ13, IJ15, IJ33, to chip surface print head surface. Drop ejection fabrication .diamond-solid.Friction .diamond-solid.IJ34, IJ35, IJ36 may still be normal to the surface. .diamond-solid.Stiction Membrane An actuator with a high force but .diamond-solid.The effective area of the .diamond-solid.Fabrication complexity .diamond-solid.1982 Hawkins U.S. Pat. No. push small area is used to push a stiff actuator becomes the .diamond-s olid.Actuator size 4,459,601 membrane that is in contact with the membrane area .diamond-solid.Diff iculty of integration in a VLSI ink. process Rotary The actuator causes the rotation of .diamond-solid.Rotary levers may be used .diamond-solid.Device complexity .diamond-solid.IJ05, IJ08, IJ13, IJ28 some element, such a grill or to increase travel .diamond-solid.May have friction at a pivot point impeller .diamond-solid.Small chip area requirements Bend The actuator bends when energized. .diamond-solid.A very small change in .diamond-solid.Requires the actuator to be made from .diamond-s olid.1970 Kyser et al U.S. Pat. No. This may be due to differential dimensions can be at least two distinct layers, or to have a 3,946,398 thermal expansion, piezoelectric converted to a large motion. thermal difference across the actuator .diamond-solid.1973 Stemme U.S. Pat. No. expansion, magnetostriction, or other .diamond-solid.3,747,120 form of relative dimensional change. .diamond-solid.IJ03, IJ09, IJ10, IJ19 .diamond-solid.IJ23, IJ24, IJ25, IJ29 .diamond-solid.IJ30, IJ31, IJ33, IJ34 .diamond-solid.IJ35 Swivel The actuator swivels around a central .diamond-solid.Allows operation where the .diamond-solid.Inefficient coupling to the ink motion .diamond-solid.IJ06 pivot. This motion is suitable where net linear force on the there are opposite forces applied to paddle is zero opposite sides of the paddle, e.g. .diamond-solid.Small chip area Lorenz force. requirements Straighten The actuator is normally bent, and .diamond-solid.Can be used with shape .diamond-solid.Requires careful balance of stresses to .diamond-solid.IJ26, IJ32 straightens when energized. memory alloys where the ensure that the quiescent bend is austenic phase is planar accurate Double bend The actuator bends in one direction .diamond-solid.One actuator can be used to .diamond-solid.Difficult to make the drops ejected by .diamond-solid.IJ36, IJ37, IJ38 when one element is energized, and power two nozzles. both bend directions identical. bends the other way when another .diamond-solid.Reduced chip size. .diamond-solid.A small efficiency loss compared to element is energized. .diamond-solid.Not sensitive to ambient equivalent single bend actuators. temperature Shear Energizing the actuator causes a .diamond-solid.Can increase the effective .diamond-solid.Not readily applicable to other actuator .diamond-solid.1985 Fishbeck U.S. Pat. No. shear motion in the actuator material. travel of piezoelectric mechanisms 4,584,590 actuators Radial The actuator squeezes an ink .diamond-solid.Relatively easy to fabricate .diamond-solid.High force required .diamond-solid.1970 Zoltan U.S. Pat. No. constriction reservoir, forcing ink from a single nozzles from glass .diamond-solid.Inefficient 3,683,212 constricted nozzle. tubing as macroscopic .diamond-solid.Difficult to integrate with VLSI structures processes Coil/uncoil A coiled actuator uncoils or coils .diamond-solid.Easy to fabricate as a planar .diamond-solid.Difficult to fabricate for non-plana r .diamond-solid.IJ17, IJ21, IJ34, IJ35 more tightly. The motion of the free VLSI process devices end of the actuator ejects the ink. .diamond-solid.Small area required, .diamond-solid.Poor out-of-plane stiffness therefore low cost Bow The actuator bows (or buckles) in the .diamond-solid.Can increase the speed of .diamond-solid.Maximum travel is constrained .diamond-solid. IJ16, IJ18, IJ27 middle when energized. travel .diamond-solid.High force required .diamond-solid.Mechanically rigid Push-Pull Two actuators control a shutter. One .diamond-solid.The structure is pinned at .diamond-solid.Not readily suitable for inkjets which .diamond-solid.IJ18 actuator pulls the shutter, and the both ends, so has a high directly push the ink other pushes it. out-of-plane rigidity Curl inwards A set of actuators curl inwards to .diamond-solid.Good fluid flow to the .diamond-solid.Design complexity .diamond-solid.IJ20, IJ42 reduce the volume of ink that they region behind the actuator enclose. increases efficiency Curl outwards A set of actuators curl outwards, .diamond-solid.Relative ly simple .diamond-solid.Relatively large chip area .diamond-solid.IJ43 pressurizing ink in a chamber construction surrounding the actuators, and expelling ink from a nozzle in the chamber. Iris Multiple vanes enclose a volume of .diamond-solid.High efficiency .diamond-solid.High fabrication complexity .diamond-solid.IJ22 ink. These simultaneously rotate, .diamond-solid.Small chip area .diamond-solid.Not suitable for pigmented inks reducing the volume between the vanes. Acoustic The actuator vibrates at a high .diamond-solid.The actuator can be .diamond-solid.Large area required for efficient .diamond-solid.19 93 Hadimioglu et vibration frequency. physically distant from the operation at useful frequencies al, EUP 550,192 ink .diamond-solid.Acoustic coupling and crosstalk .diamond-solid.199 3 Elrod et al, EUP .diamond-solid.Complex drive circuitry. 572,220 .diamond-solid.Poor control of drop volume and position None In various ink jet designs the actuator .diamond-solid.No moving parts .diamond-solid.Various other tradeoffs are required to .diamond-sol id.Silverbrook, EP 0771 does not move. eliminate moving parts 658 A2 and related patent applications .diamond-solid.Tone-jet NOZZLE REFILL METHOD Nozzle refill method Surface After the actuator is energized, it .diamond-solid.Fabrication simplicity .diamond-solid.Low speed .diamond-solid.Thermal inkjet tension typically returns rapidly to its normal .diamond-solid.Oper ational simplicity .diamond-solid.Surface tension force relatively small .diamond-solid.Piezoelectric inkjet position. This rapid return sucks in compared to actuator force .diamond-solid.IJ01-IJ07, IJ10-IJ14 air through the nozzle opening. The .diamond-solid.Long refill time usually dominates the .diamond-solid.IJ16, IJ20, IJ22-IJ45 ink surface tension at the nozzle then total repetition rate exerts a small force restoring the meniscus to a minimum area. Shuttered Ink to the nozzle chamber is .diamond-solid.High speed .diamond-solid.Requires common ink pressure .diamond-solid.IJ08, IJ13, IJ15, IJ17 oscillating ink provided at a pressure that oscillates .diamond-solid.L ow actuator energy, as the oscillator .diamond-solid.IJ18, IJ19, IJ21 pressure at twice the drop ejection frequency. actuator need only open or .diamond-solid.May not be suitable for pigmented inks When a drop is to be ejected, the close the shutter, instead of shutter is opened for 3 half cycles: ejecting the ink drop drop ejection, actuator return, and refill. Refill actuator After the main actuator has ejected a .diamond-solid.Hi gh speed, as the nozzle is .diamond-solid.Requires two independent actuators per .diamond-solid.IJ09 drop a second (refill) actuator is actively refilled nozzle energized. The refill actuator pushes ink into the nozzle chamber. The refill actuator returns slowly, to prevent its return from emptying the chamber again. Positive ink The ink is held a slight positive .diamond-solid.High refill rate, therefore a .diamond-solid.Surface spill must be prevented .diamond-solid.Silverbrook, EP 0771 pressure pressure. After the ink drop is high drop repetition rate is .diamond-solid.Highly hydrophobic print head 658 A2 and related ejected, the nozzle chamber fills possible surfaces are required patent applications quickly as surface tension and ink .diamond-solid.Alternative for: pressure both operate to refill the .diamond-solid.IJ01-IJ07, IJ10-IJ14 nozzle. .diamond-solid.IJ16, IJ20, IJ22-IJ45 METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Inlet back-flow restriction method Long inlet The ink inlet channel to the nozzle .diamond-solid.Design simplicity .diamond-solid.Restricts refill rate .diamond-solid.Thermal inkjet channel chamber is made long and relatively .diamond-solid.Operational simplicity .diamond-solid.May result in a relatively large chip .diamond-solid.Piezoelectric inkjet narrow, relying on viscous drag to .diamond-solid.Reduces crosstalk area .diamond-solid.IJ42, IJ43 reduce inlet back-flow. .diamond-solid.Only partially effective Positive ink The ink is under a positive pressure, .diamond-solid.D rop selection and .diamond-solid.Requires a method (such as a nozzle .diamond-solid.Silverbrook, EP 0771 pressure so that in the quiescent state some of separation forces can be rim or effective hydrophobizing, or 658 A2 and related the ink drop already protrudes from reduced both) to prevent flooding of the patent applications the nozzle. .diamond-solid.Fast refill time ejection surface of the print head. .diamond-solid.possible operation of This reduces the pressure in the the following: nozzle chamber which is required to .diamond-solid.IJ01-IJ07, IJ09-IJ12 eject a certain volume of ink. The .diamond-solid.IJ14, IJ16, IJ20, IJ22, reduction in chamber pressure results .diamond-solid.IJ23-IJ34, IJ36-IJ41 in a reduction in ink pushed out .diamond-solid.IJ44 through the inlet. Baffle One or more baffles are placed in the .diamond-solid.The refill rate is not as .diamond-solid.Design complexity .diamond-solid.HP Thermal Ink Jet inlet ink flow. When the actuator is restricted as the long inlet .diamond-solid.May increase fabrication complexity .diamond-solid.Tektron ix energized, the rapid ink movement method. (e.g. Tektronix hot melt Piezoelectric piezoelectric ink jet creates eddies which restrict the flow .diamond-solid.Reduces crosstalk print heads). through the inlet. The slower refill process is unrestricted, and does not result in eddies. Flexible flap In this method recently disclosed by .diamond-solid.Signi ficantly reduces back- .diamond-solid.Not applicable to most inkjet .diamond-solid.Canon restricts inlet Canon, the expanding actuator flow for edge-shooter configurations (bubble) pushes on a flexible flap thermal ink jet devices .diamond-so lid.Increased fabrication complexity that restricts the inlet. .diamond-solid.Inelastic deformation of polymer flap results in creep over extended use Inlet filter A filter is located between the ink .diamond-solid.Additio nal advantage of ink .diamond-solid.Restricts refill rate .diamond-solid .IJ04, IJ12, IJ24, inlet and the nozzle chamber. The filtration .diamond-solid.May result in complex construction .diamond-solid.IJ29, IJ30 filter has a multitude of small holes .diamond-solid.Ink filter may be fabricated or slots, restricting ink flow. The with no additional process filter also removes particles which steps may block the nozzle. Small inlet The ink inlet channel to the nozzle .diamond-solid.Design simplicity .diamond-solid.Restricts refill rate .diamond-solid.IJ02, IJ37, IJ44 compared to chamber has a substantially smaller .diamond-solid.May result in a relatively large chip nozzle cross section than that of the nozzle, area resulting in easier ink egress out of .diamond-solid.Only partially effective the nozzle than out of the inlet. Inlet shutter A secondary actuator controls the .diamond-solid.Increase s speed of the ink- .diamond-solid.Requires separate refill actuator and .diamond-solid.IJ09 position of a shutter, closing off the jet print head operation drive circuit ink inlet when the main actuator is energized. The inlet is The method avoids the problem of .diamond-solid.Back-flow problem is .diamond-solid.Requires careful design to minimize .diamond- solid.IJ01, IJ03, IJ05, IJ06 located behind inlet back-flow by arranging the ink- eliminated the negative pressure behind the paddle .diamond-solid.IJ07, IJ10, IJ11, IJ14 the ink- pushing surface of the actuator .diamond-solid.IJ16, IJ22, IJ23, IJ25 pushing between the inlet and the nozzle. .diamond-solid.IJ28, IJ31, IJ32, IJ33 surface .diamond-solid.IJ34, IJ35, IJ36, IJ39 .diamond-solid.IJ40, IJ41 Part of the The actuator and a wall of the ink .diamond-solid.Significa nt reductions in .diamond-solid.Small increase in fabrication .diamond-s olid.IJ07, IJ20, IJ26, IJ38 actuator chamber are arranged so that the back-flow can be achieved complexity moves to shut motion of the actuator closes off the .diamond-solid.Comp act designs possible off the inlet inlet. Nozzle In some configurations of ink jet, .diamond-solid.Ink back-flow problem is .diamond-solid.None related to ink back-flow on .diamond-sol id.Silverbrook, EP 0771 actuator does there is no expansion or movement eliminated actuation 658 A2 and related not result in of an actuator which may cause ink patent applications ink back-flow back-flow through the inlet. .diamond-solid.Valve-jet .diamond-solid.Tone-jet .diamond-solid.IJ08, IJ13, IJ15, IJ17 .diamond-solid.IJ18, IJ19, IJ21 NOZZLE CLEARING METHOD Nozzle Clearing method Normal nozzle All of the nozzles are fired .diamond-solid.No added complexity on the .diamond-solid.May not be sufficient to displace dried .diamond-solid.Most ink jet systems firing periodically, before the ink has a print head ink .diamond-solid .IJ01-IJ07, IJ09-IJ12 chance to dry. When not in use the .diamond-solid.IJ14, IJ16, IJ20, IJ22 nozzles are sealed (capped) against .diamond-solid.IJ23-IJ34, IJ36-IJ45 air. The nozzle firing is usually performed during a special clearing cycle, after first moving the print head to a cleaning station. Extra power to In systems which heat the ink, but do .diamond-solid.Can be highly effective if .diamond-solid.Requires higher drive voltage for .diamond-solid.Silverbrook, EP 0771 ink heater not boil it under normal situations, the heater is adjacent to the clearing 658 A2 and related nozzle clearing can be achieved by nozzle .diamond-solid.May require larger drive transistors patent applications over-powering the heater and boiling ink at the nozzle. Rapid The actuator is fired in rapid .diamond-solid.Does not require extra drive .diamond-solid.Effectiveness depends substantially .diamond-s olid.May be used with: succession of succession. In some configurations, circuits on the print head upon the configuration of the inkjet .diamond-solid.IJ01-IJ07, IJ09-IJ11 actuator this may cause heat build-up at the .diamond-solid.Can be readily controlled nozzle .diamond-solid.IJ14, IJ16, IJ20, IJ22 pulses nozzle which boils the ink, clearing and initiated by digital logic .diamond-solid.IJ23-1125, IJ27-IJ34 the nozzle. In other situations, it may .diamond-solid.IJ36-IJ45 cause sufficient vibrations to dislodge clogged nozzles. Extra power to Where an actuator is not normally .diamond-solid.A simple solution where .diamond-solid.Not suitable where there is a hard limit .diamond-solid.May be used with: ink pushing driven to the limit of its motion, applicable to actuator movement .diamond-solid.IJ03, IJ09, IJ16, IJ20 actuator nozzle clearing may be assisted by .diamond-solid.IJ23, IJ24, IJ25, IJ27 providing an enhanced drive signal .diamond-solid.IJ29, IJ30, IJ31, IJ32 to the actuator. .diamond-solid.IJ39, IJ40, IJ41, IJ42 .diamond-solid.IJ43, IJ44, IJ45 Acoustic An ultrasonic wave is applied to the .diamond-solid.A high nozzle clearing .diamond-solid.High implementation cost if system .diamond-solid.IJ08, IJ13, IJ15, IJ17 resonance ink chamber. This wave is of an capability can be achieved does not already include an acoustic .diamond-solid.IJ18, IJ19, IJ21 appropriate amplitude and frequency .diamond-solid.May be implement ed at actuator to cause sufficient force at the nozzle very low cost in systems to clear blockages. This is easiest to which already include achieve if the ultrasonic wave is at a acoustic actuators resonant frequency of the ink cavity. Nozzle A microfabricated plate is pushed .diamond-solid.Can clear severely clogged .diamond-solid.Accurate mechanical alignment is .diamond-solid.Silverbrook, EP 0771 clearing plate against the nozzles. The plate has a nozzles required 658 A2 and related post for every nozzle. The array of .diamond-solid.Moving parts are required patent applications posts .diamond-solid.There is risk of damage to the nozzles .diamond-solid.Accurate fabrication is required Ink pressure The pressure of the ink is .diamond-solid.May be effective where .diamond-solid.Requires pressure pump or other .diamond-solid.May be used with all pulse temporarily increased so that ink other methods cannot be pressure actuator IJ series ink streams from all of the nozzles. This used .diamond-solid.Expensive may be used in conjunction with .diamond-solid.Wasteful of ink actuator energizing. Print head A flexible `blade` is wiped across the .diamond-solid.Effective for planar print .diamond-s olid.Difficult to use if print head surface is .diamond-solid.Many ink jet systems wiper print head surface. The blade is head surfaces non-planar or very fragile usually fabricated from a flexible .diamond-solid.Low cost .diamond-so lid.Requires mechanical parts polymer, e.g. rubber or synthetic .diamond-solid.Blade can wear out in high volume elastomer. print systems Separate ink A separate heater is provided at the .diamond-solid.Can be effective where .diamond-solid.Fabrication complexity .diamond-solid.C an be used with boiling heater nozzle although the normal drop e- other nozzle clearing many IJ series ink ection mechanism does not require it. methods cannot be used jets The heaters do not require individual .diamond-solid.Can be implemented at no drive circuits, as many nozzles can additional cost in some be cleared simultaneously, and no inkjet configurations imaging is required. NOZZLE PLATE CONSTRUCTION Nozzle plate construction Electroformed A nozzle plate is separately .diamond-solid.Fabrication simplicity .diamond-solid.High temperatures and pressures are .diamond-so lid.Hewlett Packard nickel fabricated from electroformed nickel, required to bond nozzle plate Thermal Inkjet and bonded to the print head chip. .diamond-solid.Minimum thickness constraints .diamond-solid.Differential thermal expansion Laser ablated Individual nozzle holes are ablated .diamond-solid.No masks required .diamond-solid.Each hole must be individually formed .diamond-solid.Canon Bubblejet or drilled by an intense UV laser in a nozzle .diamond-solid.Can be quite fast .diamond-solid.Special equipment required .diamond-solid.1988 Sercel et al., polymer plate, which is typically a polymer .diamond-solid.Some control over nozzle .diamond-solid.Slow where there are many thousands SPIE, Vol. 998 such as polyimide or polysulphone profile is possible of nozzles per print head Excimer Beam .diamond-solid.Equipment required is .diamond-solid.May produce thin burrs at exit holes Applications, pp. 76- relatively low cost 83 .diamond-solid.1993 Watanabe et al., U.S. Pat. No. 5,208,604 Silicon micro- A separate nozzle plate is .diamond-solid.High accuracy is attainable .diamond-solid.Two part construction .diamond-solid.K. Bean, IEEE machined micromachined from single crystal .diamond-solid.High cost Transactions on silicon, and bonded to the print head .diamond-solid.Requires precision alignment Electron Devices, wafer. .diamond-solid.Nozzles may be clogged by adhesive Vol. ED-25, No. 10, 1978, pp 1185-1195 .diamond-solid.Xerox 1990 Hawkin et al., U.S. Pat. No. 4,899,181 Glass Fine glass capillaries are drawn from .diamond-solid.No expensive equipment .diamond-solid.Very small nozzle sizes are difficult to .diamond-solid.1970 Zoltan U.S. Pat. No. capillaries glass tubing. This method has been required form 3,683,212 used for making individual nozzles, .diamond-solid.Simple to make single .diamond-solid.Not suited for mass production but is difficult to use for bulk nozzles manufacturing of print heads with thousands of nozzles. Monolithic, The nozzle plate is deposited as a .diamond-solid.High accuracy (<1 .mu.m) .diamond-solid.Requires sacrificial layer under the .diamond-solid.Silverbrook, EP 0771 surface micro- layer using standard VLSI deposition .diamond-solid.Mono lithic nozzle plate to form the nozzle 658 A2 and related machined techniques. Nozzles are etched in the .diamond-solid.Low cost chamber patent applications using VLSI nozzle plate using VLSI lithography .diamond-solid.Existing processes can be .diamond-solid.Surface may be fragile to the touch .diamond-solid.IJ01, IJ02, IJ04, IJ11 lithographic and etching. used .diamond-solid.IJ12, IJ17, IJ18, IJ20 processes .diamond-solid.IJ22, IJ24, IJ27, IJ28 .diamond-solid.IJ29, IJ30, IJ31, IJ32 .diamond-solid.IJ33, IJ34, IJ36, IJ37 .diamond-solid.IJ38, IJ39, IJ40, IJ41 .diamond-solid.IJ42, IJ43, IJ44 Monolithic, The nozzle plate is a buried etch stop .diamond-solid.High accuracy (<1 .mu.m) .diamond-solid.Requires long etch times .diamond-so lid.IJ03, IJ05, IJ06, IJ07 etched in the wafer. Nozzle chambers are .diamond-solid.Monolithic .diamond-solid.Requires a support wafer .diamond-solid.IJ08, IJ09, IJ10, IJ13 through etched in the front of the wafer, and .diamond-solid.Low cost .diamond-solid.IJ14, IJ15, IJ16, IJ19 substrate the wafer is thinned from the back .diamond-solid.No differential expansion .diamond-solid.IJ21, IJ23, IJ25, IJ26 side. Nozzles are then etched in the etch stop layer. No nozzle Various methods have been tried to .diamond-solid.No nozzles to become .diamond-solid.Difficult to control drop position .diamond-so lid.Ricoh 1995 Sekiya et plate eliminate the nozzles entirely, to clogged accurately al U.S. Pat. No. 5,412,413 prevent nozzle clogging. These .diamond-solid.Crosstalk problems .diamond-solid.1993 Hadimioglu et include thermal bubble mechanisms al EUP 550,192 and acoustic lens mechanisms .diamond-solid.1993 Elrod et al EUP 572,220 Trough Each drop ejector has a trough .diamond-solid.Reduced manufactur ing .diamond-solid.Drop firing direction is sensitive to .diamond-solid. IJ35 through which a paddle moves. complexity wicking. There is no nozzle plate. .diamond-solid.Monolithic Nozzle slit The elimination of nozzle holes and .diamond-solid.No nozzles to become .diamond-solid.Difficult to control drop position .diamond-solid.1989 Saito et al U.S. Pat. No. instead of replacement by a slit encompassing clogged accurately 4,799,068 individual many actuator positions reduces .diamond-solid.Crosstalk problems nozzles nozzle clogging, but increases crosstalk due to ink surface waves DROP EJECTION DIRECTION Ejection direction Edge Ink flow is along the surface of the .diamond-solid.Simple construction .diamond-solid.Nozzles limited to edge .diamond-solid.Canon Bubblejet (`edge chip, and ink drops are ejected from .diamond-solid.No silicon etching required .diamond-solid.High resolution is difficult 1979 Endo et al GB shooter`) the chip edge. .diamond-solid.Good heat sinking via .diamond- solid.Fast color printing requires one print patent 2,007,162 .diamond-solid.substrate head per color .diamond-solid.Xerox heater-in-pit .diamond-solid.Mechanically strong 1990 Hawkins et al .diamond-solid.Ease of chip handing U.S. Pat. No. 4,899,181 .diamond-solid.Tone-jet Surface Ink flow is along the surface of the .diamond-solid.No bulk silicon etching .diamond-solid.Maximum ink flow is severely .diamond-soli d.Hewlett-Packard TIJ (`roof shooter`) chip, and ink drops are ejected from required restricted 1982 Vaught et al the chip surface, normal to the plane .diamond-solid.Silicon can make an U.S. Pat. No. 4,490,728 of the chip. effective heat sink .diamond-solid.IJ02, IJ11, IJ12, IJ20 .diamond-solid.Mechanical strength .diamond-solid.IJ22 Through chip, Ink flow is through the chip, and ink .diamond-solid.High ink flow .diamond-solid.Requires bulk silicon etching .diamond-solid.Si lverbrook, EP 0771 forward drops are ejected from the front .diamond-solid.Suitable for pagewidth print 658 A2 and related (`up shooter`) surface of the chip. .diamond-solid.High nozzle packing patent applications density therefore low .diamond-solid.IJ04, IJ17, IJ18, IJ24 manufacturing cost .diamond-solid.IJ27-IJ45 Through chip, Ink flow is through the chip, and ink .diamond-solid.High ink flow .diamond-solid.Requires wafer thinning .diamond-solid.IJ01, IJ03, IJ05, IJ06 reverse drops are ejected from the rear .diamond-solid.Suitable for pagewidth print .diamond-solid.Requires special handling during .diamond- solid.IJ07, IJ08, IJ09, IJ10 (`down surface of the chip. .diamond-solid.High nozzle packing manufacture .diamond-solid.IJ13, IJ14, IJ15, IJ16 shooter`) density therefore low .diamond-solid.IJ19, IJ21, IJ23, IJ25 manufacturing cost .diamond-solid.IJ26 Through Ink flow is through the actuator, .diamond-solid.Suitable for piezoelectric .diamond-solid.Pagewidth print heads require several .diamond-solid.Epson Stylus actuator which is not fabricated as part of the print heads thousand connections to drive circuits .diamond-solid.Tektronix hot melt same substrate as the drive .diamond-solid.Cannot be manufactured in standard piezoelectric ink jets transistors. CMOS fabs .diamond-solid.Complex assembly required INK TYPE Ink type Aqueous, dye Water based ink which typically .diamond-solid.Environment ally friendly .diamond-solid.Slow drying .diamond-solid.Most existing inkjets contains: water, dye, surfactant, .diamond-solid.No odor .diamond-soli d.Corrosive .diamond-solid.All IJ series ink jets humectant, and biocide. .diamond-solid.Bleeds on paper .diamond-solid .Silverbrook, EP 0771 Modern ink dyes have high water- .diamond-solid.May strikethrough 658 A2 and related fastness, light fastness .diamond-solid.Cockles paper patent applications Aqueous, Water based ink which typically .diamond-solid.Environmentally friendly .diamond-solid.Slow drying .diamond-solid.IJ02, IJ04, IJ21, IJ26 pigment contains: water, pigment, surfactant, .diamond-solid.No odor .diamond-solid.Corrosive .diamond-solid.IJ27, IJ30 humectant, and biocide. .diamond-solid.Reduced bleed .diamond-solid.Pi gment may clog nozzles .diamond-solid.Silverbrook, EP 0771 Pigments have an advantage in .diamond-solid.Reduced wicking .diamond- solid.Pigment may clog actuator 658 A2 and related reduced bleed, wicking and .diamond-solid.Reduced strikethrough mechanisms patent applications strikethrough. .diamond-solid.Cockles paper .diamond-solid.Piezoelect ric ink-jets .diamond-solid.Thermal ink jets (with significant restrictions) Methyl Ethyl MEK is a highly volatile solvent .diamond-solid.Very fast drying .diamond-solid.Odorous .diamond-solid.All IJ series ink jets Ketone (MEK) used for industrial printing on .diamond-solid.Prints on various substrates .diamond-solid.Flammable difficult surfaces such as aluminum such as metals and plastics cans. Alcohol Alcohol based inks can be used .diamond-solid.Fast drying .diamond-solid.Slight odor .diamond-solid.All IJ series ink jets (ethanol, 2- where the printer must operate at .diamond-solid.Op erates at sub-freezing .diamond-solid.Flammable butanol, and temperatures below the freezing temperatures others) point of water. An example of this is .diamond-solid.Reduced paper cockle in-camera consumer photographic .diamond-solid.Low cost printing. Phase change The ink is solid at room temperature, .diamond-solid.No drying time-ink .diamond-solid.High viscosity .diamond-solid.Tektronix hot melt (hot melt) and is melted in the print head before instantly freezes on the .diamond-solid.Printed ink typically has a `waxy` feel piezoelectric ink jets jetting. Hot melt inks are usually print medium .diamond-solid.Printed pages may `block` .diamond-solid.1989 Nowak U.S. Pat. No. wax based, with a melting point .diamond-solid.Almost any print medium .diamond-solid.Ink temperature may be above the 4,820,346 around 80.degree. C. After jetting the ink can be used curie point of permanent magnets .diamond-solid.All IJ series ink jets freezes almost instantly upon .diamond-solid.No paper cockle occurs .diamond-solid.Ink heaters consume power contacting the print medium or a .diamond-solid.No wicking occurs .diamond-solid.Long warm-up time transfer roller. .diamond-solid.No bleed occurs .diamond-solid.No strikethrough occurs Oil Oil based inks are extensively used .diamond-solid.High solubility medium for .diamond-solid.High viscosity: this is a significant .diamond-solid.All IJ series ink jets in offset printing. They have some dyes limitation for use in inkjets, which advantages in improved .diamond-solid.Does not cockle paper usually require a low viscosity. Some characteristics on paper (especially .diamond-solid.Does not wick through short chain and multi-branched oils no wicking or cockle.). Oil soluble paper have a sufficiently low viscosity. dies and pigments are required. .diamond-solid.Slow drying Microemulsion A microemulsion is a stable, self .diamond-solid.Stops ink bleed .diamond-solid.Viscosity higher than water .diamond-solid.All IJ series ink jets forming emulsion of oil, water, and .diamond-solid.High dye solubility .diamond-solid.Cost is slightly higher than water based surfactant. The characteristic drop .diamond-solid.Water, oil, and amphiphilic ink size is less than 100 nm, and is soluble dies can be used .diamond-sol id.High surfactant concentration required determined by the preferred .diamond-solid.Can stabilize pigment (around 5%) curvature of the surfactant. suspensions

Ink Jet Printing

A large number of new forms of ink jet printers have been developed to facilitate alternative ink jet technologies for the image processing and data distribution system. Various combinations of ink jet devices can be included in printer devices incorporated as part of the present invention. Australian Provisional Patent Applications relating to these ink jets which are specifically incorporated by cross reference include:

Ink Jet Manufacturing

Further, the present application may utilize advanced semiconductor fabrication techniques in the construction of large arrays of ink jet printers. Suitable manufacturing techniques are described in the following Australian provisional patent specifications incorporated here by cross-reference:

Fluid Supply

Further, the present application may utilize an ink delivery system to the ink jet head. Delivery systems relating to the supply of ink to a series of ink jet nozzles are described in the following Australian provisional patent specifications, the disclosure of which are hereby incorporated by cross-reference:

MEMS Technology

Further, the present application may utilize advanced semiconductor microelectromechanical techniques in the 10 construction of large arrays of ink jet printers. Suitable microelectromechanical techniques are described in the following Australian provisional patent specifications incorporated here by cross-reference:

IR Technologies

Further, the present application may include the utilization of a disposable camera system such as those described in the following Australian provisional patent specifications incorporated here by cross-reference:

DotCard Technologies

Further, the present application may include the utilization of a data distribution system such as that described in the following Australian provisional patent specifications incorporated here by cross-reference:

Artcam Technologies

Further, the present application may include the utilization of camera and data processing techniques such as an Artcam type device as described in the following Australian provisional patent specifications incorporated here by cross-reference: