The present invention relates to the field of ink jet printing systems.

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.

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.

Many different techniques of 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).

Ink jet printers themselves come in many different types. The utilisation of a continuous stream ink in ink jet printing appears to date back to at least 1929 wherein US Patent No. 1941001 by Hansell discloses a simple form of continuous stream electro-static inkjet printing.

US Patent 3596275 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 US Patent No. 3373437 by Sweet et al)

Piezo-electric ink jet printers are also one form of commonly utilized ink jet printing device. Piezo-electric systems are disclosed by Kyser et. al. in US Patent No. 3946398 (1970) which utilises a diaphragm mode of operation, by Zolten in US Patent 3683212 (1970) which discloses a squeeze mode of operation of a piezo electric crystal, Stemme in US Patent No. 3747120 (1972) discloses a bend mode of piezo-electric operation, Howkins in US Patent No. 4459601 discloses a Piezo electric push mode actuation of the ink jet stream and Fischbeck in US 4584590 which discloses a sheer mode type of piezo-electric transducer element.

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 US Patent 4490728. Both the aforementioned references disclosed ink jet printing techniques rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Printing devices utilising the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.

DE3234283 describes an inkjet nozzle comprising an electromagnet and an armature constructed as a tongue. When the electromagnet is activated and deactivated, the tongue rapidly moves, thereby ejecting ink from the nozzle.

JP05318724 describes an inkjet nozzle comprising a plastic magnetic plate positioned adjacent a magnetic substrate. Upon activation of an electromagnet, the magnetic plate is moved relative the substrate, thereby generating a pressure wave in the nozzle and causing ejection of ink.

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.

Many ink jet printing mechanisms are known. Unfortunately, in mass production techniques, the production of ink jet heads is quite difficult. For example, often, the orifice or nozzle plate is constructed separately from the ink supply and ink ejection mechanism and bonded to the mechanism at a later stage (Hewlett-Packard Journal, Vol. 36 no 5, pp33-37 (1985)). These separate material processing steps required in handling such precision devices often adds a substantially expense in manufacturing.

Additionally, side shooting ink jet technologies (U.S. Patent No. 4,899,181) are often used but again, this limit the amount ofmass production throughput given any particular capital investment.

Additionally, more esoteric techniques are also often utilized. These can include electroforming of nickel stage (Hewiett-Packard Journal, Vol. 36 no 5, pp33-37 (1985)), electro-discharge machining, laser ablation (U.S. Patent No. 5,208,604), micro-punching, etc.

The utilisation of the above techniques is likely to add substantial expense to the mass production of ink jet print heads and therefore add substantially to their final cost.

It would therefore be desirable if an efficient system for the mass production of ink jet print heads could be developed.

It is an object of the present invention to provide for an ink jet printing mechanism having a series of ink ejection nozzles, with the nozzles including an internal selective actuator mechanism activated on a nozzle by nozzle basis by the placement of a field around said nozzles.

Accordingly the invention provides an arrangement according to claim 1. Advantageous embodiments are provided in the dependent claims.

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

• Fig. 138 is a perspective, partly sectional view of a single ink jet nozzle in its quiescent position constructed in accordance with an embodiment;
• Fig. 139 is a perspective, partly sectional view of a single ink jet nozzle in its firing position constructed in accordance with an embodiment;
• Fig. 140 is an exploded perspective illustrating the construction of a single ink jet nozzle in accordance with an embodiment;
• Fig. 141 provides a legend of the materials indicated in Fig. 142 to Fig. 156; and
• Fig. 142 to Fig. 156 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

The preferred embodiments and other embodiments will be discussed under separate headings with the heading including an IJ number for ease of reference. The headings also include a type designator with T indicating thermal, S indicating shutter type and F indicating a field type.

In an embodiment, an array of ink jet nozzles is provided with each of the nozzles being under the influence of a outside pulsed magnetic field. The outside pulsed magnetic field causes selected nozzles to eject ink from their ink nozzle chambers.

Turning to Fig. 138 and Fig. 139, there is illustrated a side perspective view, partly in section, of a single ink jet nozzle 910. Fig. 138 illustrates a nozzle in a quiescent position and Fig. 139 illustrates a nozzle in an ink ejection position. The ink jet nozzle 910 has an ink ejection port 911 for the ejection of ink on demand. The ink jet ejection port 911 is connected to an ink nozzle chamber 912 which is usually filled with ink and supplied from an ink reservoir 913 via holes eg. 915.

A magnetic actuation device 925 is included and comprises a magnetic soft core 917 which is surrounded by a nitride coating eg. 918. The nitride coating includes an end protuberance 927.

The magnetic core 917, operates under the influence of an external pulsed magnetic field. Hence, when the external magnetic field is very high, the actuator 925 is caused to move rapidly downwards and to thereby cause the ejection of ink from the ink ejection port 911. Adjacent the actuator 920 is provided a locking mechanism 920 which comprises a thermal actuator which includes a copper resistive circuit having two arms 922, 924. A current is passed through the connected arms 922, 924 thereby causing them to be heated. The arm 922, being of a thinner construction undergoes more resistive heating than the arm 924 which has a much thicker structure. The arm 922 is also of a serpentine nature and is encased in polytetrafluoroethylene (PTFE) which has a high coefficient of thermal expansion, thereby increasing the degree of expansion upon heating. The copper portions expand with the PTFE portions by means of concertinaing. The arm 924 has a thinned portion 929 (Fig. 140) which becomes the concentrated bending region in the resolution of the various forces activated upon heating. Hence, any bending of arm 924 is accentuated in the region 929 and upon heating, the region 929 bends so that end portion 926 (Fig. 138) moves out to block any downward movement of the edge 927 of the actuator 925. Hence, when it is desired to eject an ink drop from a current nozzle chamber, the locking mechanism 920 is not activated and as a result ink is ejected from the ink ejection port during the next external magnetic pulse phase. When a current nozzle is not to eject ink, the locking mechanism 920 is activated to block any movement of the actuator 925 and therefore stop the ejection of ink from the chamber.

Importantly, the actuator 920 is located within a cavity 928 such that the volume of ink flowing past arm 922 is extremely low whereas the arm 924 receives a much larger volume of ink flow during operation.

Turning now to Fig. 140, there is illustrated an exploded perspective view of a single ink jet nozzle 910 illustrating the various layers which make up the nozzle. The nozzle 910 can be constructed on a semiconductor wafer utilizing standard semiconductor processing techniques in addition to those techniques commonly used for the construction of micro-electromechanical systems (MEMS). For a general introduction to a micro-electro mechanical system (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPIE (International Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field. At the bottom level 930 is constructed the nozzle plate including the ink ejection port 911. The nozzle plate 930 can be constructed from a buried boron doped epitaxial layer of a silicon wafer which has been back etched to the point of the epitaxial layer. The epitaxial layer itself is then etched utilizing a mask so as to form the nozzle rim (not shown) and the nozzle hole 911.

Next, is the silicon wafer layer 932 which is etched so as to include the nozzle chamber 912. The silicon layer 932 can be etched to contain substantially vertical side walls through the utilisation of high density, low pressure plasma etching such as that available from Surface Technology. Systems and subsequently filled with sacrificial material which will be later etched away.

On top of the silicon layer is deposited a two level CMOS circuitry layer 933 which comprises substantially glass in addition to the usual metal and poly layers. The layer 933 includes the formation of the heater element contacts which can be constructed from copper. The PTFE layer 935 can be provided as a departure from normal construction with a bottom PTFE layer being first deposited followed by the copper layer 934 and a second PTFE layer to cover the copper layer 934.

Next, a nitride passivation layer 936 is provided which acts to provide a passivation surface for the lower layers in addition to providing a base for a soft magnetic Nickel Ferrous layer 917 which forms the magnetic actuator portion of the actuator 925. The nitride layer 936 includes bending portions 940 utilized in the bending of the actuator.

Next a nitride passivation layer 939 is provided so as to passivate the top and side surfaces of the nickel iron (NiFe) layer 917.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps:

1. 1. Using a double sided polished wafer deposit 3 microns of epitaxial silicon heavily doped with boron.
2. 2. Deposit 10 microns of epitaxial silicon, either p-type or n-type, depending upon the CMOS process used.
3. 3. Complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. Relevant features of the wafer at this step are shown in Fig. 142. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. Fig. 141 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.
4. 4. Etch the CMOS oxide layers down to silicon or aluminum using Mask 1. This mask defines the nozzle chamber, and the edges of the print head chips. This step is shown in Fig. 143.
5. 5. Crystallographically etch the exposed silicon using, for example, KOH or EDP (ethylenediamine pyrocatechol). This etch stops on <111> crystallographic planes, and on the boron doped silicon buried layer. This step is shown in Fig. 144.
6. 6. Deposit 0.5 microns of silicon nitride (Si₃N₄).
7. 7. Deposit 10 microns of sacrificial material. Planarize down to one micron over nitride using CMP. The sacrificial material temporarily fills the nozzle cavity. This step is shown in Fig. 145.
8. 8. Deposit 0.5 microns of polytetrafluoroethylene (PTFE).
9. 9. Etch contact vias in the PTFE, the sacrificial material, nitride, and CMOS oxide layers down to second level metal using Mask 2. This step is shown in Fig. 146.
10. 10. Deposit 1 micron of titanium nitride (TiN).
11. 11. Etch the TiN using Mask 3. This mask defines the heater pattern for the hot arm of the catch actuator, the cold arm of the catch actuator, and the catch. This step is shown in Fig. 147.
12. 12. Deposit 1 micron of PTFE.
13. 13. Etch both layers of PTFE using Mask 4. This mask defines the sleeve of the hot arm of the catch actuator. This step is shown in Fig. 148.
14. 14. Deposit a seed layer for electroplating.
15. 15. Spin on 11 microns of resist, and expose and develop the resist using Mask 5. This mask defines the magnetic paddle. This step is shown in Fig. 149.
16. 16. Electroplate 10 microns of ferromagnetic material such as nickel iron (NiFe). This step is shown in Fig. 150.
17. 17. Strip the resist and etch the seed layer.
18. 18. Deposit 0.5 microns of low stress PECVD silicon nitride.
19. 19. Etch the nitride using Mask 6, which defines the spring. This step is shown in Fig. 151.
20. 20. Mount the wafer on a glass blank and back-etch the wafer using KOH with no mask. This etch thins the wafer and stops at the buried boron doped silicon layer, This step is shown in Fig. 152.
21. 21. Plasma back-etch the boron doped silicon layer to a depth of 1 micron using Mask 7. This mask defines the nozzle rim. This step is shown in Fig. 153.
22. 22. Plasma back-etch through the boron doped layer using Mask 8. This mask defines the nozzle, and the edge of the chips.
23. 23. Plasma back-etch nitride up to the glass sacrificial layer through the holes in the boron doped silicon layer. At this stage, the chips are separate, but are still mounted on the glass blank. This step is shown in Fig. 154.
24. 24. strip the adhesive layer to detach the chips from the glass blank.
25. 25. Etch the sacrificial layer. This step is shown in Fig. 155.
26. 26. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply different colors of ink to the appropriate regions of the front surface of the wafer.
27. 27. Connect the print heads to their interconnect systems.
28. 28. Hydrophobize the front surface of the print heads.
29. 29. Fill the completed print heads with ink, apply an oscillating magnetic field, and test the print heads. This step is shown in Fig. 156.

The presently disclosed ink jet printing technology is potentially suited to a wide range of printing system including: colour and monochrome office printers, short run digital printers, high speed digital printers, offset press supplemental printers, low cost scanning printers high speed pagewidth printers, notebook computers with inbuilt pagewidth printers, portable colour and monochrome printers, colour and monochrome copiers, colour and monochrome facsimile machines, combined printer, facsimile and copying machines, label printers, large format plotters, photograph copiers, printers for digital photographic "minilabs", video printers, PhotoCD printers, portable printers for PDAs, wallpaper printers, indoor sign printers, billboard printers, fabric printers, camera printers and fault tolerant commercial printer arrays.

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.

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: Docket No. Reference Title IJ01US IJ01 Radiant Plunger Ink Jet Printer IJ02US U02 Electrostatic Ink Jet Printer IJ03US IJ03 Planar Thermoelastic Bend Actuator Ink Jet IJ04US IJ04 Stacked Electrostatic Ink Jet Printer IJ05US IJ05 Reverse Spring Lever Ink Jet Printer IJ06US IJ06 Paddle Type Ink Jet Printer IJ07US U07 Permanent Magnet Electromagnetic Ink Jet Printer IJ08US IJ08 Planar Swing Grill Electromagnetic Ink Jet Printer IJ09US IJ09 Pump Action Refill Ink Jet Printer IJ10US IJ10 Pulsed Magnetic Field Ink Jet Printer IJ11US IJ11 Two Plate Reverse Firing Electromagnetic Ink Jet Printer IJ12US IJ12 Linear Stepper Actuator Ink Jet Printer IJ13US IJ13 Gear Driven Shutter Ink Jet Printer IJ14US U14 Tapered Magnetic Pole Electromagnetic Ink Jet Printer IJ15US IJ15 Linear Spring Electromagnetic Grill Ink Jet Printer IJ16US IJ16 Lorenz Diaphragm Electromagnetic Ink Jet Printer IJ17US IJ17 PTFE Surface Shooting Shuttered Oscillating Pressure Ink Jet Printer IJ18US IJ18 Buckle Grip Oscillating Pressure Ink Jet Printer IJ19US IJ19 Shutter Based Ink Jet Printer IJ20US IJ20 Curling Calyx Thermoelastic Ink Jet Printer IJ21US IJ21 Thermal Actuated Ink Jet Printer IJ22US U22 Iris Motion Ink Jet Printer IJ23US IJ23 Direct Firing Thermal Bend Actuator Ink Jet Printer IJ24US IJ24 Conductive PTFE Ben Activator Vented Ink Jet Printer IJ25US IJ25 Magnetostrictive Ink Jet Printer IJ26US IJ26 Shape Memory Alloy Ink Jet Printer IJ27US IJ27 Buckle Plate Ink Jet Printer IJ28US IJ28 Thermal Elastic Rotary Impeller Ink Jet Printer IJ29US IJ29 Thermoelastic Bend Actuator Ink Jet Printer IJ30US IJ30 Thermoelastic Bend Actuator Using PTFE and Corrugated Copper Ink Jet Printer IJ31US IJ31 Bend Actuator Direct Ink Supply Ink Jet Printer IJ32US IJ32 A High Young's Modulus Thermoelastic Ink Jet Printer U33US IJ33 Thermally actuated slotted chamber wall ink jet printer U34US IJ34 Ink Jet Printer having a thermal actuator comprising an external coiled spring IJ35US IJ35 Trough Container Ink Jet Printer IJ36US U36 Dual Chamber Single Vertical Actuator Ink Jet IJ37US IJ37 Dual Nozzle Single Horizontal Fulcrum Actuator Ink Jet IJ38US IJ38 Dual Nozzle Single Horizontal Actuator Ink Jet IJ39US IJ39 A single bend actuator capped paddle ink jet printing device IJ40US IJ40 A thermally actuated ink jet printer having a series of thermal actuator units IJ41US IJ41 A thermally actuated ink jet printer including a tapered heater element U42US IJ42 Radial Back-Curling Thermoelastic Ink Jet IJ43US IJ43 Inverted Radial Back-Curling Thermoelastic Ink Jet IJ44US IJ44 Surface bend actuator vented ink supply ink jet printer IJ45US IJ45 Coil Actuated Magnetic Plate Ink Jet Printer

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, h 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. Actuator Mechanism Description Advantages Disadvantages Examples Thermal bubble An electrothermal heater heats the ink to above boiling point, transferring significant heat to the aqueous ink. A bubble nucleates and quickly forms, expelling the ink. ◆ Large force generated ◆ High power ◆ Canon Bubblejet 1979 Endo et al GB patent 2,007,162 ◆ Simple construction ◆ Ink carrier limited to water ◆ Xerox heater-in-pit 1990 Hawkins et al USP 4,899,181 ◆ No moving parts ◆ Low efficiency ◆ Hewlett-Packard TIJ 1982 Vaught et at USP 4,490,728 ◆ Fast operation ◆ High temperatures required The efficiency of the process is low, with typically less than 0.05% of the electrical energy being transformed into kinetic energy of the drop. ◆ Small chip area required for actuator ◆ High mechanical stress ◆ Unusual materials required ◆ Large drive transistors ◆ Cavitation causes actuator failure ◆ Kogation reduces bubble formation ◆ Large print heads are difficult to fabricate Piezoelectric A piezoelectric crystal such as lead lanthanum zirconate (PZT) is electrically activated, and either expands, shears, or bends to apply pressure to the ink, ejecting drops. ◆ Low power consumption ◆ Very large area required for actuator ◆ Kyser et al USP 3,946,398 ◆ Many ink types can be used ◆ Difficult to integrate with electronics ◆ Zoltan USP 3,683,212 ◆ Fast operation ◆ High voltage drive transistors required ◆ 1973 Stemme USP 3,747,120 ◆ High efficiency ◆ Full pagewidth print heads impractical due to actuator size ◆ Epson Stylus ◆ Requires electrical poling in high field strengths during manufacture ◆ Tektronix ◆ IJ04 Electro-strictive An electric field is used to activate electrostriction in relaxor materials such as lead lanthanum zirconate titanate (PLZT) or lead magnesium niobate (PMN). ◆ Low power consumption ◆ Low maximum strain (approx. 0.01%) ◆ Seiko Epson, Usui et all JP 253401/96 ◆ Many ink types can be used ◆ Large area required for actuator due to low strain ◆ IJ04 ◆ Low thermal expansion ◆ Response speed is marginal (∼ 10 µs) ◆ Electric field strength required (approx. 3.5 V/µm) can be generated without difficulty ◆ High voltage drive transistors required ◆ Does not require electrical poling ◆ Full pagewidth print heads impractical due to actuator size Ferroelectric An electric field is used to induce a phase transition between the antiferroelectric (AFE) and ferroelectric (FE) phase. ◆ Low power consumption ◆ Difficult to integrate with electronics ◆ IJ04 ◆ Many ink types can be used ◆ Unusual materials such as PLZSnT are required Perovskite materials such as tin modified lead lanthanum zirconate titanate (PLZSnT) exhibit large strains of up to 1% associated with the AFE to FE phase transition. ◆ Fast operation (< 1 µs) ◆ Actuators require a large area ◆ Relatively high longitudinal strain ◆ High efficiency ◆ Electric field strength of around 3 V/µm can be readily provided Electrostatic plates Conductive plates are separated by a compressible or fluid dielectric (usually air). Upon application of a voltage, the plates attract each other and displace ink, causing drop ejection. The conductive plates may be in a comb or honeycomb structure, or stacked to increase the surface area and therefore the force. ◆ Low power consumption ◆ Difficult to operate electrostatic devices in an aqueous environment ◆ IJ02, IJ04 ◆ Many ink types can be used ◆ The electrostatic actuator will normally need to be separated from the ink ◆ Fast operation ◆ Very large area required to achieve high forces ◆ High voltage drive transistors may be required ◆ Full pagewidth print heads are not competitive due to actuator size Electrostatic pull on ink A strong electric field is applied to tho ink, whereupon electrostatic attraction accelerates the ink towards the print medium. ◆ Low current consumption ◆ High voltage required ◆ 1989 Saito et al, USP 4,799,068 ◆ Low temperature ◆ May be damaged by sparks due to air breakdown ◆ 1989 Miura et al, USP 4,810,954 ◆ Required field strength increases as the drop size decreases ◆ Tone-jet ◆ High voltage drive transistors required ◆ Electrostatic field attracts dust Permanent magnet electro-magnetic An electromagnet directly attracts a permanent magnet, displacing ink and causing drop ejection. Rare earth magnets with a field strength around 1 Tesla can be used. Examples are: Samarium Cobalt (SaCo) and magnetic materials in the neodymium iron boron family (NdFeB, NdDyFeBNb, NdDyFeB, etc) ◆ Low power consumption ◆ Complex fabrication ◆ IJ07, IJ10 ◆ Many ink types can be used ◆ Permanent magnetic material such as Neodymium Iron Boron (NdFeB) required. ◆ Fast operation ◆ High local currents required ◆ High efficiency ◆ Copper metalization should be used for long electromigration lifetime and low resistivity ◆ Easy extension from single nozzles to pagewidth print heads ◆ Pigmented inks are usually infeasible ◆ Operating temperature limited to the Curie temperature (around 540 K) Soft magnetic core electro-magnetic A solenoid induced a magnetic field in a soft magnetic core or yoke fabricated from a ferrous material such as electroplated iron alloys such as CoNiFe [1], CoFe, or NiFe alloys. Typically, the soft magnetic material is in two parts, which are normally held apart by a spring. When the solenoid is actuated, the two parts attract, displacing the ink. ◆ Low power consumption ◆ Complex fabrication ◆ IJ01, IJ05, IJ08, IJ10 ◆ Many ink types can be used ◆ Materials not usually present in a CMOS fab such as NiFe, CoNiFe, or CoFe are required ◆ IJ12, IJ14, IJ15, IJ17 ◆ Fast operation ◆ High local currents required ◆ High efficiency ◆ Copper metalization should be used for long electromigration life time and low resistivity ◆ Easy extension from single nozzles to pagewidth print heads ◆ Electroplating is required ◆ High saturation flux density is required (2.0-2.1 T is achievable with CoNiFe [1]) Magnetic Lorenz force The Lorenz force acting on a current carrying wire in a magnetic field is utilized. ◆ Low power consumption ◆ Force acts as a twisting motion ◆ IJ06, IJ11, IJ13, IJ16 This allows the magnetic field to be supplied externally to the print head, for example with rare earth permanent magnets. ◆ Many ink types can be used ◆ Typically, only a quarter of the solenoid length provides force in a useful direction ◆ Fast operation ◆ High local currents required ◆ High efficiency ◆ Copper metalization should be used for long electromigration lifetime and low resistivity Only the current carrying wire need be fabricated on the print-head, simplifying materials requirements. ◆ Easy extension from single nozzles to pagewidth print heads ◆ Pigmented inks are usually infeasible Magneto-striction The actuator uses the giant magnetostrictive effect of materials such as Terfenol-D (an alloy of terbium, dysprosium and iron developed at the Naval Ordnance Laboratory, hence Ter-Fe-NOL). For best efficiency, the actuator should be pre-stressed to approx. 8 MPa. ◆ Many ink types can be used ◆ Force acts as a twisting motion ◆ Fischenbeck, USP 4,032,929 ◆ Fast operation ◆ Unusual materials such as Terfenol-D are required ◆ IJ25 ◆ Easy extension from single nozzles to pagewidth print heads ◆ High local currents required ◆ High force is available ◆ Copper metalization should be used for long electromigration lifetime and low resistivity ◆ Pre-stressing may be required Surface tension reduction Ink under positive pressure is held in a nozzle by surface tension. The surface tension of the ink is reduced below the bubble threshold, causing the ink to egress from the nozzle. ◆ Low power consumption ◆ Requires supplementary force to effect drop separation ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Simple construction ◆ Requires special ink surfactants ◆ No unusual materials required in fabrication ◆ Speed may be limited by surfactant properties ◆ High efficiency ◆ Easy extension from single nozzles to pagewidth print heads Viscosity reduction The ink viscosity is locally reduced to select which drops are to be ejected. A viscosity reduction can be achieved electrothermally with most inks, but special inks can be engineered for a 100:1 viscosity reduction. ◆ Simple construction ◆ Requires supplementary force to effect drop separation ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ No unusual materials required in fabrication ◆ Requires special ink viscosity properties ◆ Easy extension from single nozzles to pagewidth print heads ◆ High speed is difficult to achieve ◆ Requires oscillating ink pressure ◆ A high temperature difference (typically 80 degrees) is required Acoustic An acoustic wave is generated and focussed upon the drop ejection region. ◆ Can operate without a nozzle plate ◆ Complex drive circuitry ◆ 1993 Hadimioglu et al, EUP 550,192 ◆ Complex fabrication ◆ 1993 Elrod et al, EUP 572,220 ◆ Low efficiency ◆ Poor control of drop position ◆ Poor control of drop volume Thermoelastic bend actuator An actuator which relies upon differential thermal expansion upon Joule heating is used. ◆ Low power consumption ◆ Efficient aqueous operation requires a thermal insulator on the hot side ◆ IJ03, IJ09, IJ17, IJ18 ◆ Many ink types can be used ◆ Corrosion prevention can be difficult ◆ IJ19, IJ20, IJ21, IJ22 ◆ Simple planar fabrication ◆ Pigmented inks may be infeasible, as pigment particles may jam the bend actuator ◆ IJ23, IJ24, IJ27, IJ28 ◆ Small chip area required for each actuator ◆ IJ29, IJ30, IJ31, IJ32 ◆ Fast operation ◆ IJ33, IJ34, IJ35, IJ36 ◆ High efficiency ◆ IJ37, IJ38 ,IJ39, IJ40 ◆ CMOS compatible voltages and currents ◆ IJ41 ◆ Standard MEMS processes can be used ◆ Easy extension from single nozzles to pagewidth print heads High CTE thermoelastic actuator A material with a very high coefficient of thermal expansion (CTE) such as polytetrafluoroethylene (PTFE) is used. As high CTE materials are usually non-conductive, a heater fabricated from a conductive material is incorporated. A 50 µm long PTFE bend actuator with polysilicon heater and 15 mW power input can provide 180 µN force and 10 µm deflection. Actuator motions include: ◆ High force can be generated ◆ Requires special material (e.g. PTFE) ◆ IJ09, IJ17, IJ18, IJ20 1) Bend ◆ PTFE is a candidate for low dielectric constant insulation in ULSI ◆ Requires a PTFE deposition process, which is not yet standard in ULSI fabs ◆ IJ21, IJ22, IJ23, IJ24 2) Push ◆ Very low power consumption ◆ PTFE deposition cannot be followed with high temperature (above 350 °C) processing ◆ IJ27, IJ28, IJ29, IJ30 3) Buckle ◆ Many ink types can be used ◆ Pigmented inks may be infeasible, as pigment particles may jam the bend actuator ◆ IJ31, IJ42, IJ43, IJ44 4) Rotate ◆ Simple planar fabrication ◆ Small chip area required for each actuator ◆ Fast operation ◆ High efficiency ◆ CMOS compatible voltages and currents ◆ Easy extension from single nozzles to pagewidth print heads Conductive polymer thermoelastic actuator A polymer with a high coefficient of thermal expansion (such as PTFE) is doped with conducting substances to increase its conductivity to about 3 orders of magnitude below that of copper. The conducting polymer expands when resistively heated, Examples of conducting dopants include: ◆ High force can be generated ◆ Requires special materials development (High CTE conductive polymer) ◆ IJ24 1) Carbon nanotubes ◆ Very low power consumption ◆ Requires a PTFE deposition process, which is not yet standard in ULSI fabs 2) Metal fibers ◆ Many ink types can be used ◆ PTFE deposition cannot be followed with high temperature (above 350 °C) processing 3) Conductive polymers such as doped polythiophene ◆ Simple planar fabrication ◆ Evaporation and CVD deposition techniques cannot be used 4) Carbon granules ◆ Small chip area required for each actuator ◆ Pigmented inks may be infeasible, as pigment particles may jam the bend actuator ◆ Fast operation ◆ High efficiency ◆ CMOS compatible voltages and currents ◆ Easy extension from single nozzles to pagewidth print heads Shape memory alloy A shape memory alloy such as TiNi (also known as Nitinol - Nickel Titanium alloy developed at the Naval Ordnance Laboratory) is thermally switched between its weak martensitic state and its high stiffness austenic state. The shape of the actuator in its martensitic state is deformed relative to the austenic shape. The shape change causes ejection of a drop. ◆ High force is available (stresses of hundreds of MPa) ◆ Fatigue limits maximum number of cycles ◆ IJ26 ◆ Large strain is available (more than 3%) ◆ Low strain (1%) is required to extend fatigue resistance ◆ High corrosion resistance ◆ Simple construction ◆ Cycle rate limited by heat removal ◆ Easy extension from single nozzles to pagewidth print heads ◆ Requires unusual materials (TiNi) ◆ Low voltage operation ◆ The latent heat of transformation must be provided ◆ High current operation ◆ Requires pre-stressing to distort the martensitic state Linear Magnetic Actuator Linear magnetic actuators include the Linear Induction Actuator (LIA), Linear Permanent Magnet Synchronous Actuator (LPMSA), Linear Reluctance Synchronous Actuator (LRSA), Linear Switched Reluctance Actuator (LSRA), and the Linear Stepper Actuator (LSA). ◆ Linear Magnetic actuators can be constructed with high thrust, long travel, and high efficiency using planar semiconductor fabrication techniques ◆ Requires unusual semiconductor materials such as soft magnetic alloys (e.g. CoNiFe [1]) ◆ IJ12 ◆ Long actuator travel is available ◆ Some varieties also require permanent magnetic materials such as Neodymium iron boron (NdFeB) ◆ Medium force is available ◆ Requires complex multi-phase drive circuitry ◆ Low voltage operation ◆ High current operation Operational mode Description Advantages Disadvantages Examples Actuator directly pushes ink This is the simplest mode of operation: the actuator directly supplies sufficient kinetic energy to expel the drop. The drop must have a sufficient velocity to overcome the surface tension. ◆ Simple operation ◆Drop repetition rate is usually limited to less than 10 KHz. However, this is not fundamental to the method, but is related to the refill method normally used ◆Thermal inkjet ◆ No external fields required ◆ All of the drop kinetic energy must be provided by the actuator ◆ Piezoelectric inkjet ◆Satellite drops can be avoided if drop velocity is less than 4 m/s ◆ Satellite drops usually form if drop velocity is greater than 4.5 m/s ◆ IJ01, IJ02, IJ03, IJ04 ◆ Can be efficient, depending upon the actuator used ◆ IJ05, IJ06, IJ07, IJ09 ◆ IJ11, IJ12, IJ14, IJ16 ◆ IJ20, IJ22, IJ23, IJ24 ◆ IJ25, IJ26, IJ27, IJ28 ◆ IJ29, IJ30, IJ31, IJ32 ◆ IJ33, IJ34, IJ35, IJ36 ◆ IJ37, IJ38, IJ39, IJ40 ◆ IJ41, IJ42, IJ43, IJ44 Proximity The drops to be printed are selected by some manner (e.g. thermally induced surface tension reduction of pressurized ink). Selected drops are separated from the ink in the nozzle by contact with the print medium or a transfer roller. ◆ Very simple print head fabrication can be used ◆ Requires close proximity between the print head and the print media or transfer roller ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ The drop selection means does not need to provide the energy required to separate the drop from the nozzle ◆ May require two print heads printing alternate rows of the image ◆ Monolithic color print heads are difficult Electrostatic pull on ink The drops to be printed are selected by some manner (e.g. thermally induced surface tension reduction of pressurized ink). Selected drops are separated from the ink in the nozzle by a strong electric field. ◆ Very simple print head fabrication can be used ◆ Requires very high electrostatic field ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ The drop selection means does not need to provide the energy required to separate the drop from the nozzle ◆ Electrostatic field for small nozzle sizes is above air breakdown ◆ Tone-Jet ◆ Electrostatic field may attract dust Magnetic pull on Ink The drops to be printed are selected by some manner (e.g. thermally induced surface tension reduction of pressurized ink). Selected drops are separated from the ink in the nozzle by a strong magnetic field acting on the magnetic ink. ◆ Very simple print head fabrication can be used ◆ Requires magnetic ink ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ The drop selection means does not need to provide the energy required to separate the drop from the nozzle ◆ Ink colors other than black are difficult ◆ Requires very high magnetic fields Shutter The actuator moves a shutter to block ink flow to the nozzle. The ink pressure is pulsed at a multiple of the drop ejection frequency. ◆ High speed (>50 KHz) operation can be achieved due to reduced refill time ◆ Moving parts are required ◆ IJ13, IJ17, IJ21 ◆ Drop timing can be very accurate ◆ Requires ink pressure modulator ◆ The actuator energy can be very low ◆ Friction and wear must be considered ◆ Stiction is possible Shuttered grill The actuator moves a shutter to block ink flow through a grill to the nozzle. The shutter movement need only be equal to the width of the grill holes. ◆ Actuators with small travel can be used ◆ Moving parts are required ◆ IJ08, IJ15, IJ18, IJ19 ◆ Actuators with small force can be used ◆ Requires ink pressure modulator ◆ High speed (>50 KHz) operation can be achieved ◆ Friction and wear must be considered ◆ Stiction is possible Pulsed magnetic pull on ink pusher A pulsed magnetic field attracts an 'ink pusher' at the drop ejection frequency. An actuator controls a catch, which prevents the ink pusher from moving when a drop is not to be ejected. ◆ Extremely low energy operation is possible ◆ Requires an external pulsed magnetic field ◆ IJ10 ◆ No heat dissipation problems ◆ Requires special materials for both the actuator and the ink pusher ◆ Complex construction Auxillary Mechanism Description Advantages Disadvantages Examples None The actuator directly ares the ink drop, and there is no external field or other mechanism required. ◆ Simplicity of construction ◆ Drop ejection energy must be supplied by individual nozzle actuator ◆ Most inkjets, including piezoelectric and thermal bubble. ◆ Simplicity of operation ◆ IJ01 - IJ07, IJ09, IJ11 ◆ Small physical size ◆ IJ12, IJ14, IJ20, IJ22 ◆ IJ23-IJ45 Oscillating ink pressure (including acoustic stimulation) The ink pressure oscillates, providing much of the drop ejection energy. The actuator selects which drops are to be fired by selectively blocking or enabling nozzles. The ink pressure oscillation may be achieved by vibrating the print head, or preferably by an actuator in the ink supply. ◆ Oscillating ink pressure can provide a refill pulse, allowing higher operating speed ◆ Requires external ink pressure oscillator ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ The actuators may operate with much lower energy ◆ Ink pressure phase and amplitude must be carefully controlled ◆ IJ08, IJ13, IJ15, IJ17 ◆ Acoustic lenses can be used to focus the sound on the nozzles ◆ Acoustic reflections in the ink chamber must be designed for ◆ IJ18, IJ19, IJ21 Media proximity The print head is placed in close proximity to the print medium. Selected drops protrude from the print head further than unselected drops, and contact the print medium. The drop soaks into the medium fast enough to cause drop separation. ◆ Low power ◆ Precision assembly required ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ High accuracy ◆ Paper fibers may cause problem ◆ Simple print head construction ◆ Cannot print on rough substrates Transfer roller Drops are printed to a transfer roller instead of straight to the print medium. A transfer roller can also be used for proximity drop separation. ◆ High accuracy ◆ Bulky ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Wide range of print substrates can be used ◆ Expensive ◆ Tektronix hot melt piezoelectric inkjet ◆ Ink can be dried on the transfer roller ◆ Complex construction ◆ Any of the IJ series Electrostatic An electric field is used to accelerate selected drops towards the print medium. ◆ Low power ◆ Field strength required for separation of small drops is near or above air breakdown ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Simple print head construction ◆ Tone-Jet Direct magnetic field A magnetic field is used to accelerate selected drops of magnetic ink towards the print medium. ◆ Low power ◆ Requires magnetic ink ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Simple print head construction ◆ Requires strong magnetic field Cross magnetic field The print head is placed in a constant magnetic field. The Lorenz force in a current carrying wire is used to move the actuator. ◆ Does not require magnetic materials to be integrated in the print head manufacturing process ◆ Requires external magnet ◆ IJ06, IJ16 ◆ Current densities may be high, resulting in electromigration problems Pulsed magnetic field A pulsed magnetic field is used to cyclically attract a paddle, which pushes on the ink. A small actuator moves a catch, which selectively prevents the paddle from moving. ◆ Very low power operation is possible ◆ Complex print head construction ◆ IJ10 ◆ Small print head size ◆ Magnetic materials required in print head Actuator amplification Description Advantages Disadvantages Examples None No actuator mechanical amplification is used. The actuator directly drives the drop ejection process. ◆ Operational simplicity ◆ Many actuator mechanisms have insufficient travel, or insufficient force, to efficiently drive the drop ejection process ◆ Thermal Bubble Inkjet ◆ IJ01, IJ02, IJ06, IJ07 ◆ IJ16, IJ25, IJ26 Differential expansion bend actuator An actuator material expands more on one side than on the other. The expansion may be thermal, piezoelectric, magnetostrictive, or other mechanism. ◆ Provides greater travel in a reduced print head area ◆ High stresses are involved ◆ Piezoelectric ◆ The bend actuator converts a high force low travel actuator mechanism to high travel, lower force mechanism. ◆ Care must be taken that the materials do not delaminate ◆ IJ03, IJ09, IJ17-IJ24 ◆ Residual bend resulting from high temperature or high stress during formation ◆ IJ27, IJ29-IJ39, IJ42, ◆ IJ43, IJ44 Transient bend actuator A trilayer bend actuator where the two outside layers are identical. This cancels bend due to ambient temperature and residual stress. The actuator only responds to transient heating of one side or the other. ◆ Very good temperature stability ◆ High stresses are involved ◆ IJ40, IJ41 ◆ High speed, as a new drop can be fired before heat dissipates ◆ Care must be taken that the materials do not delaminate ◆ Cancels residual stress of formation Actuator stack A series of thin actuators are stacked. This can be appropriate where actuators require high electric field strength, such as electrostatic and piezoelectric actuators. ◆ Increased travel ◆ Increased fabrication complexity ◆ Some piezoelectric ink jets ◆ Reduced drive voltage ◆ Increased possibility of short circuits due to pinholes ◆ IJ04 Multiple actuators Multiple smaller actuators are used simultaneously to move the ink. Each actuator need provide only a portion of the force required. ◆ Increases the force available from an actuator ◆ Actuator forces may not add linearly, reducing efficiency ◆ IJ12, IJ13, IJ18, IJ20 ◆ Multiple actuators can be positioned to control ink flow accurately ◆ IJ22, IJ28, IJ42, IJ43 Linear Spring A linear spring is used to transform a motion with small travel and high force into a longer travel, lower force motion. ◆ Matches low travel actuator with higher travel requirements ◆ Requires print head area for the spring ◆ IJ15 ◆ Non-contact method of motion transformation Reverse spring The actuator loads a spring. When the actuator is turned off, the spring releases. ◆ Better coupling to the ink ◆ Fabrication complexity High stress in the spring ◆ IJ05, IJ11 This can reverse the force/distance curve of the actuator to make it compatible with the force/time requirements of the drop ejection. Coiled actuator A bend actuator is coiled to provide greater travel in a reduced chip area. ◆ Increases travel ◆ Generally restricted to planar implementations due to extreme fabrication difficulty in other orientations. ◆ IJ17, IJ21, IJ34, IJ35 ◆ Reduces chip area ◆ Planar implementations are relatively easy to fabricate. Flexure bend actuator A bend actuator has a small region near the fixture point, which flexes much more readily than the remainder of the actuator. ◆ Simple means of increasing travel of a bend actuator ◆ Care must be taken not to exceed the elastic limit in the flexure area ◆ IJ10, IJ19, IJ33 The actuator flexing is effectively converted from an even coiling to an angular bend, resulting in greater travel of the actuator tip. ◆ Stress distribution is very uneven ◆ Difficult to accurately model with finite element analysis Gears Gears can be used to increase travel at the expense of duration. Circular gears, rack and pinion, ratchets, and other gearing methods can be used. ◆ Low force, low travel actuators can be used ◆ Moving parts are required ◆ IJ13 ◆ Can be fabricated using standard surface MEMS processes ◆ Several actuator cycles are required ◆ More complex drive electronics ◆ Complex construction ◆ Friction, friction, and wear are possible Catch The actuator controls a small catch. The catch either enables or disables movement of an ink pusher that is controlled in a bulk manner. ◆ Very low actuator energy ◆ Complex construction ◆ IJ10 ◆ Very small actuator size ◆ Requires external force ◆ Unsuitable for pigmented inks Buckle plate A buckle plate can be used to change a slow actuator into a fast motion. It can also convert a high force, low travel actuator into a high travel, medium force motion. ◆ Very fast movement achievable ◆ Must stay within elastic limits of the materials for long device life ◆ S. Hirata et al, "An Ink-jet Head ...", Proc. IEEE MEMS, Feb. 1996, pp 418-423. ◆ High stresses involved ◆ IJ18, IJ27 ◆ Generally high power requirement Tapered magnetic pole A tapered magnetic pole can increase travel at the expense of force. ◆ Linearizes the magnetic force/distance curve ◆ Complex construction ◆ IJ14 Lever A lever and fulcrum is used to transform a motion with small travel and high force into a motion with longer travel and lower force. The lever can also reverse the direction of travel. ◆ Matches low travel actuator with higher travel requirements ◆ High stress around the fulcrum ◆ IJ32, IJ36, IJ37 ◆ Fulcrum area has no linear movement, and can be used for a fluid seal Rotary impeller The actuator is connected to a rotary impeller. A small angular deflection of the actuator results in a rotation of the impeller vanes, which push the ink against stationary vanes and out of the nozzle. ◆ High mechanical advantage ◆ Complex construction ◆ IJ28 ◆ The ratio of force to travel of the actuator can be matched to the nozzle requirements by varying the number of impeller vanes ◆ Unsuitable for pigmented inks Acoustic lens A refractive or diffractive (e.g. zone plate) acoustic lens is used to concentrate sound waves. ◆ No moving parts ◆ Large area required ◆ 1993 Hadimioglu et al, EUP 550,192 ◆ Only relevant for acoustic ink jets ◆ 1993 Elrod et al, EUP 572,220 Sharp conductive point A sharp point is used to concentrate an electrostatic field. ◆ Simple construction ◆ Difficult to fabricate using standard VLSI processes for a surface ejecting ink-jet ◆ Tone-jet ◆ Only relevant for electrostatic ink jets Actuator motion Description Advantages Disadvantages Examples Volume expansion The volume of the actuator changes, pushing the ink in all directions. ◆ Simple construction in the case of thermal inkjet ◆ High energy is typically required to achieve volume expansion. Thisleads to thermal stress, cavitation, and kogation in thermal ink jet implementations ◆ Hewlett-Packard Thermal Inkjet ◆ Canon Bubblejet Linear, normal to chip surface The actuator moves in a direction normal to the print head surface. The nozzle is typically in the line of movement. ◆ Efficient coupling to ink drops ejected normal to the surface ◆ High fabrication complexity may be required to achieve perpendicular motion ◆ IJ01, IJ02, IJ04, IJ07 ◆ IJ11, IJ14 Linear, parallel to chip surface The actuator moves parallel to the print head surface. Drop ejection may still be normal to the surface. ◆ Suitable for planar fabrication ◆ Fabrication complexity ◆ IJ12, IJ13, IJ15, IJ33, ◆ Friction ◆ IJ34, IJ35, IJ36 ◆ Stiction Membrane push An actuator with a high force but small area is used to push a stiff membrane that is in contact with the ink. ◆ The effective area of the actuator becomes the membrane area ◆ Fabrication complexity ◆ 1982 Howkins USP 4,459,601 ◆ Actuator size ◆ Difficulty of integration in a VLSI process Rotary The actuator causes the rotation of some element, such a grill or impeller ◆ Rotary levers may be used to increase travel ◆ Device complexity ◆ IJ05, IJ08, IJ13, IJ28 ◆ Small chip area requirements ◆ May have friction at a pivot point Bend The actuator bends when energized. This may be due to differential thermal expansion, piezoelectric expansion, magnetostriction, or other form of relative dimensional change. ◆ A very small change in dimensions can be converted to a large motion. ◆ Requires the actuator to be made from at least two distinct layers, or to have a thermal difference across the actuator ◆ 1970 Kyser et al USP 3,946,398 ◆ 1973 Stemme USP 3,747,120 ◆ IJ03, IJ09, IJ10, IJ19 ◆ IJ23, IJ24, IJ25, IJ29 ◆ IJ30, IJ31, IJ33, IJ34 ◆ IJ35 Swivel The actuator swivels around a central pivot. This motion is suitable where there are opposite forces applied to opposite sides of the paddle, e.g. Lorenz force. ◆ Allows operation where the net linear force on the paddle is zero ◆ Inefficient coupling to the ink motion ◆ IJ06 ◆ Small chip area requirements Straighten The actuator is normally bent, and straightens when energized. ◆ Can be used with shape memory alloys where the austenic phase is planar ◆ Requires careful balance of stresses to ensure that the quiescent bend is accurate ◆ IJ26, IJ32 Double bend The actuator bends in one direction when one element is energized, and bends the other way when another element is energized. ◆ One actuator can be used to power two nozzles. ◆ Difficult to make the drops ejected by both bend directions identical. ◆ IJ36, IJ37, IJ38 ◆ Reduced chip size. ◆ A small efficiency loss compared to equivalent single bend actuators. ◆ Not sensitive to ambient temperature Shear Energizing the actuator causes a shear motion in the actuator material. ◆ Can increase the effective travel of piezoelectric actuators ◆ Not readily applicable to other actuator mechanisms ◆ 1985 Fishbeck USP 4,584,590 Radial constriction The actuator squeezes an ink reservoir, forcing ink from a constricted nozzle. ◆ Relatively easy to fabricate single nozzles from glass tubing as macroscopic structures ◆ High force required ◆ 1970 Zoltan USP 3,683,212 ◆ Inefficient ◆ Difficult to integrate with VLSI processes Coil / uncoil A coiled actuator uncoils or coils more tightly. The motion of the free end of the actuator ejects the ink. ◆ Easy to fabricate as a planar VLSI process ◆ Difficult to fabricate for non-planar devices ◆ IJ17, IJ21, IJ34, IJ35 ◆ Small area required, therefore low cost ◆ Poor out-of-plane stiffness Bow The actuator bows (or buckles) in the middle when energized, ◆ Can increase the speed of travel ◆ Maximum travel is constrained ◆ IJ16, IJ18, IJ27 ◆ Mechanically rigid ◆ High force required Push-Pull Two actuators control a shutter. One actuator pulls the shutter, and the other pushes it. ◆ The structure is pinned at both ends, so has a high out-of-plane rigidity ◆ Not readily suitable for inkjets which directly push the ink ◆ IJ18 Curl inwards A set of actuators curl inwards to reduce the volume of ink that they enclose. ◆ Good fluid flow to the region behind the actuator increases efficiency ◆ Design complexity ◆ IJ20, IJ42 Curl outwards A set of actuators curl outwards, pressurizing ink in a chamber surrounding the actuators, and expelling ink from a nozzle in the chamber. ◆ Relatively simple construction ◆ Relatively large chip area ◆ IJ43 Iris Multiple vanes enclose a volume of ink. ◆ High efficiency ◆ High fabrication complexity ◆ IJ22 These simultaneously rotate, reducing the volume between the vanes. ◆ Small chip area ◆ Not suitable for pigmented inks Acoustic vibration The actuator vibrates at a high frequency. ◆ The actuator can be physically distant from the ink ◆ Large area required for efficient operation at useful frequencies ◆ 1993 Hadimioglu et al, EUP 550,192 ◆ Acoustic coupling and crosstalk ◆ 1993 Elrod et al, EUP 572,220 ◆ Complex drive circuitry ◆ Poor control of drop volume and position None In various ink jet designs the actuator does not move. ◆ No moving parts ◆ Various other tradeoffs are required to eliminate moving parts ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Tone-jet Nozzle refill method Description Advantages Disadvantages Examples Surface tension After the actuator is energized, it typically returns rapidly to its normal position. This rapid return sucks in air through the nozzle opening. ◆ Fabrication simplicity ◆ Low speed ◆ Thermal inkjet The ink surface tension at the nozzle then exerts a small force restoring the meniscus to a minimum area. ◆ Operational simplicity ◆ Surface tension force relatively small compared to actuator force ◆ Piezoelectric inkjet ◆ Long refill time usually dominates the total repetition rate ◆ IJ01-IJ07, IJ10-IJ14 ◆ IJ16, IJ20, IJ22-IJ45 Shuttered Ink to the nozzle chamber is provided at a ◆ High speed ◆ Requires common ink pressure ◆ IJ08, IJ13, IJ15, IJ17 oscillating ink pressure pressure that oscillates at twice the drop ejection frequency. When a drop is to be ejected, the shutter is opened for 3 half cycles: drop ejection, actuator return, and refill. ◆ Low actuator energy, as the actuator need only open or close the shutter, instead of ejecting the ink drop oscillator ◆ IJ18, IJ19, IJ21 ◆ May not be suitable for pigmented inks Refill actuator After the main actuator has ejected a drop a second (refill) 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. ◆ High speed, as the nozzle is actively refilled ◆ Requires two independent actuators per nozzle ◆ IJ09 Positive ink pressure The ink is held a slight positive pressure. After the ink drop is ejected. the nozzle chamber fills quickly as surface tension and ink pressure both operate to refill the nozzle. ◆ High refill rate, therefore a high drop repetition rate is possible ◆ Surface spill must be prevented ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Highly hydrophobic print head surfaces are required ◆ Alternative for: ◆ IJ01-IJ07, IJ10-IJ14 ◆ IJ16, IJ20, IJ22-IJ45 Inlet back-flow restriction method Description Advantages Disadvantages Examples Long Inlet channel The ink inlet channel to the nozzle chamber is made long and relatively narrow, relying on viscous drag to reduce inlet back-flow. ◆ Design simplicity ◆ Restricts refill rate ◆ Thermal inkjet ◆ Operational simplicity ◆ May result in a relatively large chip area ◆ Piezoelectric inkjet ◆ Reduces crosstalk ◆ Only partially effective ◆ IJ42, IJ43 Positive ink pressure The ink is under a positive pressure, so that in the quiescent state some of the ink drop already protrudes from the nozzle. ◆ Drop selection and separation forces can be reduced ◆ Requires a method (such as a nozzle rim or effective hydrophobizing, or both) to prevent flooding of the ejection surface of the print head. ◆ Silverbrook, EP 0771 658 A2 and related patent applications This reduces the pressure in the nozzle chamber which is required to eject a certain volume of ink. The reduction in chamber pressure results In a reduction in ink pushed out through the inlet. ◆ Fast refill time ◆ Possible operation of the following: ◆ IJ01-IJ07, IJ09- IJ12 ◆ IJ14, IJ16, IJ20, IJ22, ◆ IJ23-IJ34, IJ36- IJ41 ◆ IJ44 Baffle One or more baffles are placed in the inlet ink flow. When the actuator is energized, the rapid ink movement creates eddies which restrict the flow through the inlet. ◆ The refill rate is not as restricted as the long inlet method. ◆ Design complexity ◆ HP Thermal Ink Jet The slower refill process is unrestricted, and does not result in eddies. ◆ Reduces crosstalk ◆ May increase fabrication complexity (e.g. Tektronix hot melt Piezoelectric print heads). ◆ Tektronix piezoelectric ink jet Flexible flap restricts inlet In this method recently disclosed by Canon, the expanding actuator (bubble) pushes on a flexible flap that restricts the inlet. ◆ Significantly reduces back-flow for edge-shooter thermal ink jet devices ◆ Not applicable to most inkjet configurations ◆ Canon ◆ Increased fabrication complexity ◆ Inelastic deformation of polymer flap results in creep over extended use Inlet filter A filter is located between the ink inlet and the nozzle chamber. The filter has a multitude of small holes or slots, restricting ink flow. The filter also removes particles which may block the nozzle. ◆ Additional advantage of ink filtration ◆ Restricts refill rate ◆ IJ04, IJ12, IJ24, IJ27 ◆ Ink filter may be fabricated with no additional process steps ◆ May result in complex construction ◆ IJ29, IJ30 Small inlet compared to nozzle The ink inlet channel to the nozzle chamber has a substantially smaller cross section than that of the nozzle , resulting in easier ink egress out of the nozzle than out of the inlet. ◆ Design simplicity ◆ Restricts refill rate ◆ IJ02, IJ37, IJ44 ◆ May result in a relatively large chip area ◆ Only partially effective Inlet shutter A secondary actuator controls the position of a shutter, closing off the ink inlet when the main actuator is energized. ◆ Increases speed of the ink-jet print head operation ◆ Requires separate refill actuator and drive circuit ◆ IJ09 The inlet is located behind the ink-pushing surface The method avoids the problem of inlet back-flow by arranging the ink-pushing surface of the actuator between the inlet and the nozzle. ◆ Back-flow problem is eliminated ◆ Requires careful design to minimize the negative pressure behind the paddle ◆ IJ01, IJ03, IJ05, IJ06 ◆ IJ07, IJ10, IJ11, IJ14 ◆ IJ16, IJ22, IJ23, IJ25 ◆ IJ28, IJ31, IJ32, IJ33 ◆ IJ34, IJ35, IJ36, IJ39 ◆ IJ40, IJ41 Part of the actuator moves to shut off the inlet The actuator and a wall of the ink chamber are arranged so that the motion of the actuator closes off the inlet. ◆ Significant reductions in back-flow can be achieved ◆ Small increase in fabrication complexity ◆ IJ07, IJ20, IJ26, IJ38 ◆ Compact designs possible Nozzle actuator does not result in ink back-flow In some configurations of ink jet, there is no expansion or movement of an actuator which may cause ink back-flow through the inlet. ◆ Ink back-flow problem is eliminated ◆ None related to ink back-flow on actuation ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Valve-jet ◆ Tone-jet ◆ IJ08, IJ13, IJ15, IJ17 ◆ IJ18, IJ19, IJ21 Nozzle Clearing method Description Advantage Disadvantages Examples Normal nozzle firing All of the nozzles are fired periodically, before the ink has a chance to dry. When not in use the nozzles are sealed (capped) against air. ◆ No added complexity on the print head ◆ May not be sufficient to displace dried Ink ◆ Most ink jet systems The nozzle firing is usually performed during a special clearing cycle, after first moving the print head to a cleaning station. ◆ IJ01-IJ07, IJ09-IJ12 ◆ IJ14, IJ16, IJ20, IJ22 ◆ IJ23-IJ34, IJ36-IJ45 Extra power to ink beater In systems which heat the ink, but do not boil it under normal situations, nozzle clearing can be achieved by over-powering the heater and boiling ink at the nozzle. ◆ Can be highly effective if the heater is adjacent to the nozzle ◆ Requires higher drive voltage for clearing ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ May require larger drive transistors Rapid succession of actuator pulses The actuator is fired in rapid succession. ◆ Does not require extra drive circuits on the print head ◆ Effectiveness depends substantially upon the configuration of the inkjet nozzle ◆ May be used with: In some configurations, this may cause heat build-up at the nozzle which boils the ink, clearing the nozzle. In other situations, it may cause sufficient vibrations to dislodge clogged nozzles. ◆ Can be readily controlled and initiated by digital logic ◆ IJ01-IJ07, IJ09- IJ11 ◆ IJ14, IJ16, IJ20, IJ22 ◆ IJ23-IJ25, IJ27-IJ34 ◆ IJ36-IJ45 Extra power to ink pushing actuator Where an actuator is not normally driven to the limit of its motion, nozzle clearing may be assisted by providing an enhanced drive signal to the actuator. ◆ A simple solution where applicable ◆ Not suitable where there is a hard limit to actuator movement ◆ May be used with: ◆ IJ03, IJ09, IJ16, IJ20 ◆ IJ23, IJ24, IJ25, IJ27 ◆ IJ29, IJ30, IJ31, IJ32 ◆ IJ39, IJ40, IJ41, IJ42 ◆ IJ43, IJ44, IJ45 Acoustic resonance An ultrasonic wave is applied to the ink chamber. This wave is of an appropriate amplitude and frequency to cause sufficient force at the nozzle to clear blockages. This is easiest to achieve if the ultrasonic wave is at a resonant frequency of the ink cavity. ◆ A high nozzle clearing capability can be achieved ◆ High implementation cost if system does not already include an acoustic actuator ◆ IJ08, IJ13, IJ15, IJ17 ◆ May be implemented at very low cost in systems which already include acoustic actuators ◆ IJ18, IJ19, IJ21 Nozzle clearing A microfabricated plate is pushed against plate the nozzles. The plate has a post for every nozzle. The array of posts ◆ Can clear severely clogged nozzles ◆ Accurate mechanical alignment is required ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Moving parts are required ◆ There is risk of damage to the nozzles ◆ Accurate fabrication is required Ink pressure pulse The pressure of the ink is temporarily increased so that ink streams from all of the nozzles. This may be used in conjunction with actuator energizing. ◆ May be effective where other methods cannot be used ◆ Requires pressure pump or other pressure actuator ◆ May be used with all IJ series ink jets ◆ Expensive ◆ Wasteful of ink Print head wiper A flexible 'blade' is wiped across the print head surface. The blade is usually fabricated from a flexible polymer, e.g. rubber or synthetic elastomer. ◆ Effective for planar print head surfaces ◆ Difficult to use if print head surface is non-planar or very fragile ◆ Many ink jet systems ◆ Low cost ◆ Requires mechanical parts ◆ Blade can wear out in high volume print systems Separate ink boiling heater A separate heater is provided at the nozzle although the normal drop e-ection mechanism does not require it. The heaters do not require individual drive circuits, as many nozzles can be cleared simultaneously, and no imaging is required. ◆ Can be effective where other nozzle clearing methods cannot be used ◆ Fabrication complexity ◆ Can be used with many IJ series ink jets ◆ Can be implemented at no additional cost in some inkjet configurations Nozzle plate construction Description Advantages Disadvantages Examples Electroformed nickel A nozzle plate is separately fabricated from electroformed nickel, and bonded to the print head chip. ◆ Fabrication simplicity ◆ High temperatures and pressures are required to bond nozzle plate ◆ Hewlett Packard Thermal Inkjet ◆ Minimum thickness constraints ◆ Differential thermal expansion Laser ablated or drilled polymer Individual nozzle holes are ablated by an intense UV laser in a nozzle plate, which is typically a polymer such as polyimide or polysulphone ◆ No masks required ◆ Each hole must be individually formed ◆ Canon Bubblejet ◆ Can be quite fast ◆ Special equipment required ◆ 1988 Sercel et al., SPIE, Vol. 998 Excimer Beam Applications, pp. 76-83 ◆ Some control over nozzle profile is possible ◆ Slow where there are many thousands of nozzles per print head ◆ 1993 Watanabe et al., USP 5,208,604 ◆ Equipment required is relatively low cost ◆ May produce thin burrs at exit holes Silicon micro-machined A separate nozzle plate is micromachined from single crystal silicon, and bonded to the print head wafer. ◆ High accuracy is attainable ◆ Two part construction ◆ K. Bean, IEEE Transactions on Electron Devices, Vol. ED-25, No. 10, 1978, pp 1185-1195 ◆ High cost ◆ Xerox 1990 Hawkins et al., USP 4,899,181 ◆ Requires precision alignment ◆ Nozzles may be clogged by adhesive Glass capillaries Fine glass capillaries are drawn from glass tubing. This method has been used for making individual nozzles, but is difficult to use for bulk manufacturing of print heads with thousands of nozzles. ◆ No expensive equipment required ◆ Very small nozzle sizes are difficult to form ◆ 1970 Zoltan USP 3,683,212 ◆ Simple to make single nozzles ◆ Not suited for mass production Monolithic, surface micro-machined using VLSI lithographic processes The nozzle plate is deposited as a layer using standard VLSI deposition techniques. Nozzles are etched in the nozzle plate using VLSI lithography and etching. ◆ High accuracy (<1 µm) ◆ Requires sacrificial layer under the nozzle plate to form the nozzle chamber ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Monolithic ◆ Surface may be fragile to the touch ◆ IJ01, IJ02, IJ04, IJ11 ◆ Low cost ◆ IJ12, IJ17, IJ18, IJ20 ◆ Existing processes can be used ◆ IJ22, IJ24, IJ27, IJ28 ◆ IJ29, IJ30, IJ31, IJ32 ◆ IJ33, IJ34, IJ36, IJ37 ◆ IJ38, IJ39, IJ40, IJ41 ◆ IJ42, IJ43, IJ44 Monolithic, etched through substrate The nozzle plate is a buried etch stop in the wafer. Nozzle chambers are etched in the front of the wafer, and the wafer is thinned from the back side. Nozzles are then etched in the etch stop layer. ◆ High accuracy (<1 µm) ◆ Requires long etch times ◆ IJ03, IJ05, IJ06, IJ07 ◆ Monolithic ◆ Requires a support wafer ◆ IJ08, IJ09, IJ10, IJ13 ◆ Low cost ◆ IJ14, IJ15, IJ16, IJ19 ◆ No differential expansion ◆ IJ21, IJ23, IJ25, IJ26 No nozzle plate Various methods have been tried to eliminate the nozzles entirely, to prevent nozzle clogging. These include thermal bubble mechanisms and acoustic lens mechanisms ◆ No nozzles to become clogged ◆ Difficult to control drop position accurately ◆ Ricoh 1995 Sekiya et al USP 5,412,413 ◆ Crosstalk problems ◆ 1993 Hadimioglu et al EUP 550,192 ◆ 1993 Elrod et al EUP 572,220 Trough Each drop ejector has a trough through which a paddle moves. There is no nozzle plate. ◆ Reduced manufacturing complexity ◆ Drop firing direction is sensitive to wicking. ◆ IJ35 ◆ Monolithic Nozzle slit instead of individual nozzles The elimination of nozzle holes and replacement by a slit encompassing many actuator positions reduces nozzle clogging, but increases crosstalk due to ink surface waves ◆ No nozzles to become clogged ◆ Difficult to control drop position accurately ◆ 1989 Saito et al USP 4,799,068 ◆ Crosstalk problems Ejection direction Description Advantages Disadvantages Examples Edge. ('edge shooter') Ink flow is along the surface of the chip, and ink drops are ejected from the chip edge. ◆ Simple construction ◆ Nozzles limited to edge ◆ Canon Bubblejet 1979 Endo et al GB patent 2,007,162 ◆ No silicon etching required ◆ High resolution is difficult ◆ Xerox heater-in-pit 1990 Hawkins et al USP 4,899,181 ◆ Good heat sinking via substrate ◆ Fast color printing requires one print head per color ◆ Tone-jet ◆ Mechanically strong ◆ Ease of chip handing ◆ Ease of chip handing Surface ('roof shooter') Ink flow is along the surface of the chip, and ink drops are ejected from the chip surface, normal to the plane of the chip. ◆ No bulk silicon etching required ◆ Maximum ink flow is severely restricted ◆ Hewlett-Packard TIJ 1982 Vaught et al USP 4,490,728 ◆ Silicon can make an effective heat sink ◆ IJ02, IJ11, IJ12, IJ20 ◆ Mechanical strength ◆ IJ22 Through chip, forward ('up shooter') Ink flow is through the chip, and ink drops are ejected from the front surface of the chip. ◆ High ink flow ◆ Requires bulk silicon etching ◆ Silverbrook, EP 0771 658 A2 and related patent applications ◆ Suitable for pagewidth print ◆ IJ04, IJ17, IJ18, IJ24 ◆ High nozzle packing density therefore low manufacturing cost ◆ IJ27-IJ45 Through chip, reverse ('down shooter') Ink flow is through the chip, and ink drops are ejected from the rear surface of the chip. ◆ High ink flow ◆ Requires wafer thinning ◆ IJ01, IJ03, IJ05, IJ06 ◆ Suitable for pagewidth print ◆ Requires special handling during manufacture ◆ IJ07, IJ08, IJ09, IJ10 ◆ High nozzle packing density therefore low manufacturing cost ◆ IJ13, IJ14, IJ15, IJ16 ◆ IJ19, IJ21, IJ23, IJ25 ◆ IJ26 Through actuator Ink flow is through the actuator, which is not fabricated as part of the same substrate as the drive transistors. ◆ Suitable for piezoelectric print heads ◆ Pagewidth print heads require several thousand connections to drive circuits ◆ Epson Stylus ◆ Cannot be manufactured in standard CMOS fabs ◆ Tektronix hot melt piezoelectric ink jets ◆ Complex assembly required Ink type Description Advantages Disadvantages Examples Aqueous, dye Water based ink which typically contains: water, dye, surfactant, humectant, and biocide. ◆ Environmentally friendly ◆ Slow drying ◆ Most existing inkjets Modem ink dyes have high water-fastness, light fastness ◆ No odor ◆ Corrosive ◆ All IJ series ink jets ◆ Bleeds on paper ◆ Silverbrook, EP 0771658 A2 and related patent applications ◆ May strikethrough ◆ Cockles paper Aqueous, pigment Water based ink which typically contains: water, pigment, surfactant, humectant, and biocide. ◆ Environmentally friendly ◆ Slow drying ◆ IJ02, IJ04, IJ21, IJ26 Pigments have an advantage in reduced bleed, wicking and strikethrough. ◆ No odor ◆ Corrosive ◆ IJ27, IJ30 Reduced bleed ◆ Pigment may clog nozzles ◆ Silverbrook, EP 0771658 A2 and related patent applications ◆ Reduced wicking ◆ Pigment may clog actuator mechanisms ◆ Piezoelectric ink-jets ◆ Reduced strikethrough ◆ Cockles paper ◆ Thermal ink jets (with significant restrictions) Methyl Ethyl Ketone (MEK) MEK is a highly volatile solvent used for industrial printing on difficult surfaces such as aluminum cans. ◆ Very fast drying ◆ Odorous ◆ All IJ series ink jets ◆ Prints on various substrates such as metals and plastics ◆ Flammable Alcohol (ethanol, 2-butanol, and others) Alcohol based inks can be used where the printer must operate at temperatures below the freezing point of water. An example of this is in-camera consumer photographic printing. ◆ Fast drying ◆ Slight odor ◆ All IJ series ink jets ◆ Operates at sub-freezing ◆ Flammable temperatures ◆ Reduced paper cockle ◆ Low cost Phase change (hot melt) The ink is solid at room temperature, and is melted in the print head before jetting. Hot melt inks are usually wax based, with a melting point around 80 °C. After jetting the ink freezes almost instantly upon contacting the print medium or a transfer roller. ◆ No drying time- ink instantly freezes on the print medium ◆ High viscosity ◆ Tektronix hot melt piezoelectric ink jets ◆ Almost any print medium can be used ◆ Printed ink typically has a 'waxy' feel ◆ 1989 Nowak USP 4,820,346 ◆ No paper cockle occurs ◆ Printed pages may 'block' ◆ All IJ series ink jets ◆ No wicking occurs ◆ Ink temperature may be above the curie point of permanent magnets ◆ No bleed occurs ◆ Ink heaters consume power ◆ No strikethrough occurs ◆ Long warm-up time Oil Oil based inks are extensively used in offset printing. They have advantages in improved characteristics on paper (especially no wicking or cockle). Oil soluble dies and pigments are required. ◆ High solubility medium for some dyes ◆ High viscosity: this is a significant limitation for use in inkjets, which usually require a low viscosity. Some short chain and multi-branched oils have a sufficiently low viscosity. ◆ All IJ series ink jets ◆ Does not cockle paper ◆ Slow drying ◆ Does not wick through paper

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.

Further, the present application may utilize advanced semiconductor fabrication techniques in the construction of large arrays of ink jet printers.

Further, the present application may utilize an ink delivery system to the ink jet head.

Further, the present application may utilize advanced semiconductor microelectromechanical techniques in the construction of large arrays of ink jet printers.

Further, the present application may include the utilization of a disposable camera system.

Further, the present application may include the utilization of a data distribution system.

Further, the present application may include the utilization of camera and data processing techniques such as an Artcam type device.

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 scope of the invention as broadly described. The present embodiment is, therefore, to be considered in all respects to be illustrative and not restrictive.