# Patent

## Title
Ink jet nozzle arrangement with a segmented actuator nozzle chamber cover

## Abstract

A nozzle arrangement for an inkjet printer comprises a nozzle chamber; an ink supply channel for supplying ink to the nozzle chamber; a cover for covering the nozzle chamber, the cover defining an ink ejection port through which ink is ejected; a plurality of thermal bend actuators radially arranged around the ink ejection port; and a plurality of heater elements each corresponding to one of the plurality of thermal bend actuators. Each heater element is provided at an end of a corresponding thermal bend actuator opposite the ink ejection port.

## Background
CROSS REFERENCES TO RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No. 11/525,861 filed on Sep. 25, 2006, which is a continuation application of U.S. Ser. No. 11/202,331 filed on Aug. 12, 2005, now issued U.S. Pat. No. 7,182,436, which is a continuation of U.S. Ser. No. 10/728,796, filed on Dec. 8, 2003, now issued U.S. Pat. No. 6,966,633, which is a continuation of U.S. Ser. No. 10/303,291, filed on Nov. 23, 2002, now issued U.S. Pat. No. 6,672,708, which is a Continuation of U.S. Ser. No. 09/855,093 filed May 14, 2001, now issued U.S. Pat. No. 6,505,912, which is a Continuation of U.S. Ser. No. 09/112,806, filed Jul. 10, 1998, now issued as U.S. Pat. No. 6,247,790, all of which are herein incorporated by reference.
The following Australian provisional patent applications are hereby incorporated by cross-reference. For the purposes of location and identification, U.S. patent applications identified by their U.S. patent application serial numbers (USSN) or patent numbers are listed alongside the Australian applications from which the U.S. patent applications claim the right of priority.













US PATENT/PATENT



CROSS-REFERENCED
APPLICATION


AUSTRALIAN
(CLAIMING RIGHT


PROVISIONAL
OF PRIORITY FROM


PATENT
AUSTRALIAN PROVISIONAL
DOCKET


APPLICATION NO.
APPLICATION)
NO.







PO7991
6,750,901
ART01US


PO8505
6,476,863
ART02US


PO7988
6,788,336
ART03US


PO9395
6,322,181
ART04US


PO8017
6,597,817
ART06US


PO8014
6,227,648
ART07US


PO8025
6,727,948
ART08US


PO8032
6,690,419
ART09US


PO7999
6,727,951
ART10US


PO8030
6,196,541
ART13US


PO7997
6,195,150
ART15US


PO7979
6,362,868
ART16US


PO7978
6,831,681
ART18US


PO7982
6,431,669
ART19US


PO7989
6,362,869
ART20US


PO8019
6,472,052
ART21US


PO7980
6,356,715
ART22US


PO8018
6,894,694
ART24US


PO7938
6,636,216
ART25US


PO8016
6,366,693
ART26US


PO8024
6,329,990
ART27US


PO7939
6,459,495
ART29US


PO8501
6,137,500
ART30US


PO8500
6,690,416
ART31US


PO7987
7,050,143
ART32US


PO8022
6,398,328
ART33US


PO8497
7,110,024
ART34US


PO8020
6,431,704
ART38US


PO8504
6,879,341
ART42US


PO8000
6,415,054
ART43US


PO7934
6,665,454
ART45US


PO7990
6,542,645
ART46US


PO8499
6,486,886
ART47US


PO8502
6,381,361
ART48US


PO7981
6,317,192
ART50US


PO7986
6,850,274
ART51US


PO7983
09/113,054
ART52US


PO8026
6,646,757
ART53US


PO8028
6,624,848
ART56US


PO9394
6,357,135
ART57US


PO9397
6,271,931
ART59US


PO9398
6,353,772
ART60US


PO9399
6,106,147
ART61US


PO9400
6,665,008
ART62US


PO9401
6,304,291
ART63US


PO9403
6,305,770
ART65US


PO9405
6,289,262
ART66US


PP0959
6,315,200
ART68US


PP1397
6,217,165
ART69US


PP2370
6,786,420
DOT01US


PO8003
6,350,023
Fluid01US


PO8005
6,318,849
Fluid02US


PO8066
6,227,652
IJ01US


PO8072
6,213,588
IJ02US


PO8040
6,213,589
IJ03US


PO8071
6,231,163
IJ04US


PO8047
6,247,795
IJ05US


PO8035
6,394,581
IJ06US


PO8044
6,244,691
IJ07US


PO8063
6,257,704
IJ08US


PO8057
6,416,168
IJ09US


PO8056
6,220,694
IJ10US


PO8069
6,257,705
IJ11US


PO8049
6,247,794
IJ12US


PO8036
6,234,610
IJ13US


PO8048
6,247,793
IJ14US


PO8070
6,264,306
IJ15US


PO8067
6,241,342
IJ16US


PO8001
6,247,792
IJ17US


PO8038
6,264,307
IJ18US


PO8033
6,254,220
IJ19US


PO8002
6,234,611
IJ20US


PO8068
6,302,528
IJ21US


PO8062
6,283,582
IJ22US


PO8034
6,239,821
IJ23US


PO8039
6,338,547
IJ24US


PO8041
6,247,796
IJ25US


PO8004
6,557,977
IJ26US


PO8037
6,390,603
IJ27US


PO8043
6,362,843
IJ28US


PO8042
6,293,653
IJ29US


PO8064
6,312,107
IJ30US


PO9389
6,227,653
IJ31US


PO9391
6,234,609
IJ32US


PP0888
6,238,040
IJ33US


PP0891
6,188,415
IJ34US


PP0890
6,227,654
IJ35US


PP0873
6,209,989
IJ36US


PP0993
6,247,791
IJ37US


PP0890
6,336,710
IJ38US


PP1398
6,217,153
IJ39US


PP2592
6,416,167
IJ40US


PP2593
6,243,113
IJ41US


PP3991
6,283,581
IJ42US


PP3987
6,247,790
IJ43US


PP3985
6,260,953
IJ44US


PP3983
6,267,469
IJ45US


PO7935
6,224,780
IJM01US


PO7936
6,235,212
IJM02US


PO7937
6,280,643
IJM03US


PO8061
6,284,147
IJM04US


PO8054
6,214,244
IJM05US


PO8065
6,071,750
IJM06US


PO8055
6,267,905
IJM07US


PO8053
6,251,298
IJM08US


PO8078
6,258,285
IJM09US


PO7933
6,225,138
IJM10US


PO7950
6,241,904
IJM11US


PO7949
6,299,786
IJM12US


PO8060
6,866,789
IJM13US


PO8059
6,231,773
IJM14US


PO8073
6,190,931
IJM15US


PO8076
6,248,249
IJM16US


PO8075
6,290,862
IJM17US


PO8079
6,241,906
IJM18US


PO8050
6,565,762
IJM19US


PO8052
6,241,905
IJM20US


PO7948
6,451,216
IJM21US


PO7951
6,231,772
IJM22US


PO8074
6,274,056
IJM23US


PO7941
6,290,861
IJM24US


PO8077
6,248,248
IJM25US


PO8058
6,306,671
IJM26US


PO8051
6,331,258
IJM27US


PO8045
6,110,754
IJM28US


PO7952
6,294,101
IJM29US


PO8046
6,416,679
IJM30US


PO9390
6,264,849
IJM31US


PO9392
6,254,793
IJM32US


PP0889
6,235,211
IJM35US


PP0887
6,491,833
IJM36US


PP0882
6,264,850
IJM37US


PP0874
6,258,284
IJM38US


PP1396
6,312,615
IJM39US


PP3989
6,228,668
IJM40US


PP2591
6,180,427
IJM41US


PP3990
6,171,875
IJM42US


PP3986
6,267,904
IJM43US


PP3984
6,245,247
IJM44US


PP3982
6,315,914
IJM45US


PP0895
6,231,148
IR01US


PP0869
6,293,658
IR04US


PP0887
6,614,560
IR05US


PP0885
6,238,033
IR06US


PP0884
6,312,070
IR10US


PP0886
6,238,111
IR12US


PP0877
6,378,970
IR16US


PP0878
6,196,739
IR17US


PP0883
6,270,182
IR19US


PP0880
6,152,619
IR20US


PO8006
6,087,638
MEMS02US


PO8007
6,340,222
MEMS03US


PO8010
6,041,600
MEMS05US


PO8011
6,299,300
MEMS06US


PO7947
6,067,797
MEMS07US


PO7944
6,286,935
MEMS09US


PO7946
6,044,646
MEMS10US


PP0894
6,382,769
MEMS13US











FIELD OF THE INVENTION
The present invention relates to the field of inkjet printing and, in particular, discloses an inverted radial back-curling thermoelastic ink jet printing mechanism.
BACKGROUND OF THE INVENTION
Many different types of printing mechanisms have been invented, a large number of which are presently in use. The known forms of printers 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 forms. The utilization of a continuous stream of ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream electro-static ink jet printing.
U.S. Pat. No. 3,596,275 by Sweet also discloses a process of a continuous ink jet printing including a step wherein the ink jet stream is modulated by a high frequency electro-static field so as to cause drop separation. This technique is still utilized by several manufacturers including Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweet et al).
Piezoelectric ink jet printers are also one form of commonly utilized ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode form of operation of a piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972) which discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 which discloses a piezoelectric push mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode type of piezoelectric transducer element.
Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned references disclose ink jet printing techniques which rely on the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Printing devices utilizing the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.
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 and operation, durability and consumables.
SUMMARY OF THE INVENTION
According to an aspect of the present disclosure, a nozzle arrangement for an inkjet printer comprises a nozzle chamber; an ink supply channel for supplying ink to the nozzle chamber; a cover for covering the nozzle chamber, the cover defining an ink ejection port through which ink is ejected; a plurality of thermal bend actuators radially arranged around the ink ejection port; and a plurality of heater elements each corresponding to one of the plurality of thermal bend actuators. Each heater element is provided at an end of a corresponding thermal bend actuator opposite the ink ejection port.



BRIEF DESCRIPTION OF THE DRAWINGS
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:
FIGS. 1-3 are schematic sectional views illustrating the operational principles of the preferred embodiment;
FIG. 4(a) and FIG. 4(b) are again schematic sections illustrating the operational principles of the thermal actuator device;
FIG. 5 is a side perspective view, partly in section, of a single nozzle arrangement constructed in accordance with the preferred embodiments;
FIGS. 6-13 are side perspective views, partly in section, illustrating the manufacturing steps of the preferred embodiments;
FIG. 14 illustrates an array of ink jet nozzles formed in accordance with the manufacturing procedures of the preferred embodiment;
FIG. 15 provides a legend of the materials indicated in FIGS. 16 to 23; and
FIG. 16 to FIG. 23 illustrate sectional views of the manufacturing steps in one form of construction of a nozzle arrangement in accordance with the invention.



DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS
In the preferred embodiment, ink is ejected out of a nozzle chamber via an ink ejection port using a series of radially positioned thermal actuator devices that are arranged about the ink ejection port and are activated to pressurize the ink within the nozzle chamber thereby causing the ejection of ink through the ejection port.
Turning now to FIGS. 1, 2 and 3, there is illustrated the basic operational principles of the preferred embodiment. FIG. 1 illustrates a single nozzle arrangement 1 in its quiescent state. The arrangement 1 includes a nozzle chamber 2 which is normally filled with ink so as to form a meniscus 3 in an ink ejection port 4. The nozzle chamber 2 is formed within a wafer 5. The nozzle chamber 2 is supplied with ink via an ink supply channel 6 which is etched through the wafer 5 with a highly isotropic plasma etching system. A suitable etcher can be the Advance Silicon Etch (ASE) system available from Surface Technology Systems of the United Kingdom.
A top of the nozzle arrangement 1 includes a series of radially positioned actuators 8, 9. These actuators comprise a polytetrafluoroethylene (PTFE) layer and an internal serpentine copper core 17. Upon heating of the copper core 17, the surrounding PTFE expands rapidly resulting in a generally downward movement of the actuators 8, 9. Hence, when it is desired to eject ink from the ink ejection port 4, a current is passed through the actuators 8, 9 which results in them bending generally downwards as illustrated in FIG. 2. The downward bending movement of the actuators 8, 9 results in a substantial increase in pressure within the nozzle chamber 2. The increase in pressure in the nozzle chamber 2 results in an expansion of the meniscus 3 as illustrated in FIG. 2.
The actuators 8, 9 are activated only briefly and subsequently deactivated. Consequently, the situation is as illustrated in FIG. 3 with the actuators 8, 9 returning to their original positions. This results in a general inflow of ink back into the nozzle chamber 2 and a necking and breaking of the meniscus 3 resulting in the ejection of a drop 12. The necking and breaking of the meniscus 3 is a consequence of the forward momentum of the ink associated with drop 12 and the backward pressure experienced as a result of the return of the actuators 8, 9 to their original positions. The return of the actuators 8,9 also results in a general inflow of ink from the channel 6 as a result of surface tension effects and, eventually, the state returns to the quiescent position as illustrated in FIG. 1.
FIGS. 4(a) and 4(b) illustrate the principle of operation of the thermal actuator. The thermal actuator is preferably constructed from a material 14 having a high coefficient of thermal expansion. Embedded within the material 14 are a series of heater elements 15 which can be a series of conductive elements designed to carry a current. The conductive elements 15 are heated by passing a current through the elements 15 with the heating resulting in a general increase in temperature in the area around the heating elements 15. The position of the elements 15 is such that uneven heating of the material 14 occurs. The uneven increase in temperature causes a corresponding uneven expansion of the material 14. Hence, as illustrated in FIG. 4(b), the PTFE is bent generally in the direction shown.
In FIG. 5, there is illustrated a side perspective view of one embodiment of a nozzle arrangement constructed in accordance with the principles previously outlined. The nozzle chamber 2 is formed with an isotropic surface etch of the wafer 5. The wafer 5 can include a CMOS layer including all the required power and drive circuits. Further, the actuators 8, 9 each have a leaf or petal formation which extends towards a nozzle rim 28 defining the ejection port 4. The normally inner end of each leaf or petal formation is displaceable with respect to the nozzle rim 28. Each activator 8, 9 has an internal copper core 17 defining the element 15. The core 17 winds in a serpentine manner to provide for substantially unhindered expansion of the actuators 8, 9. The operation of the actuators 8, 9 is as illustrated in FIG. 4(a) and FIG. 4(b) such that, upon activation, the actuators 8 bend as previously described resulting in a displacement of each petal formation away from the nozzle rim 28 and into the nozzle chamber 2. The ink supply channel 6 can be created via a deep silicon back edge of the wafer 5 utilizing a plasma etcher or the like. The copper or aluminium core 17 can provide a complete circuit. A central arm 18 which can include both metal and PTFE portions provides the main structural support for the actuators 8, 9.
Turning now to FIG. 6 to FIG. 13, one form of manufacture of the nozzle arrangement 1 in accordance with the principles of the preferred embodiment is shown. The nozzle arrangement 1 is preferably manufactured using microelectromechanical (MEMS) techniques and can include the following construction techniques:
As shown initially in FIG. 6, the initial processing starting material is a standard semi-conductor wafer 20 having a complete CMOS level 21 to a first level of metal. The first level of metal includes portions 22 which are utilized for providing power to the thermal actuators 8, 9.
The first step, as illustrated in FIG. 7, is to etch a nozzle region down to the silicon wafer 20 utilizing an appropriate mask.
Next, as illustrated in FIG. 8, a 2 μm layer of polytetrafluoroethylene (PTFE) is deposited and etched so as to define vias 24 for interconnecting multiple levels.
Next, as illustrated in FIG. 9, the second level metal layer is deposited, masked and etched to define a heater structure 25. The heater structure 25 includes via 26 interconnected with a lower aluminium layer.
Next, as illustrated in FIG. 10, a further 2 μm layer of PTFE is deposited and etched to the depth of 1 μm utilizing a nozzle rim mask to define the nozzle rim 28 in addition to ink flow guide rails 29 which generally restrain any wicking along the surface of the PTFE layer. The guide rails 29 surround small thin slots and, as such, surface tension effects are a lot higher around these slots which in turn results in minimal outflow of ink during operation.
Next, as illustrated in FIG. 11, the PTFE is etched utilizing a nozzle and actuator mask to define a port portion 30 and slots 31 and 32.
Next, as illustrated in FIG. 12, the wafer is crystallographically etched on a <111> plane utilizing a standard crystallographic etchant such as KOH. The etching forms a chamber 33, directly below the port portion 30.
In FIG. 13, the ink supply channel 34 can be etched from the back of the wafer utilizing a highly anisotropic etcher such as the STS etcher from Silicon Technology Systems of United Kingdom. An array of ink jet nozzles can be formed simultaneously with a portion of an array 36 being illustrated in FIG. 14. A portion of the printhead is formed simultaneously and diced by the STS etching process. The array 36 shown provides for four column printing with each separate column attached to a different colour ink supply channel being supplied from the back of the wafer. Bond pads 37 provide for electrical control of the ejection mechanism.
In this manner, large pagewidth printheads can be fabricated so as to provide for a drop-on-demand ink ejection mechanism.
One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps:
1. Using a double-sided polished wafer 60, complete a 0.5 micron, one poly, 2 metal CMOS process 61. This step is shown in FIG. 16. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. FIG. 15 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.
2. Etch the CMOS oxide layers down to silicon or second level metal using Mask 1. This mask defines the nozzle cavity and the edge of the chips. This step is shown in FIG. 16.
3. Deposit a thin layer (not shown) of a hydrophilic polymer, and treat the surface of this polymer for PTFE adherence.
4. Deposit 1.5 microns of polytetrafluoroethylene (PTFE) 62.
5. Etch the PTFE and CMOS oxide layers to second level metal using Mask 2. This mask defines the contact vias for the heater electrodes. This step is shown in FIG. 17.
6. Deposit and pattern 0.5 microns of gold 63 using a lift-off process using Mask 3. This mask defines the heater pattern. This step is shown in FIG. 18.
7. Deposit 1.5 microns of PTFE 64.
8. Etch 1 micron of PTFE using Mask 4. This mask defines the nozzle rim 65 and the rim at the edge 66 of the nozzle chamber. This step is shown in FIG. 19.
9. Etch both layers of PTFE and the thin hydrophilic layer down to silicon using Mask 5. This mask defines a gap 67 at inner edges of the actuators, and the edge of the chips. It also forms the mask for a subsequent crystallographic etch. This step is shown in FIG. 20.
10. Crystallographically etch the exposed silicon using KOH. This etch stops on <111> crystallographic planes 68, forming an inverted square pyramid with sidewall angles of 54.74 degrees. This step is shown in FIG. 21.
11. Back-etch through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 6. This mask defines the ink inlets 69 which are etched through the wafer. The wafer is also diced by this etch. This step is shown in FIG. 22.
12. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets 69 at the back of the wafer.
13. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.
14. Fill the completed print heads with ink 70 and test them. A filled nozzle is shown in FIG. 23.
The presently disclosed ink jet printing technology is potentially suited to a wide range of printing systems including: color and monochrome office printers, short run digital printers, high speed digital printers, offset press supplemental printers, low cost scanning printers high speed pagewidth printers, notebook computers with inbuilt pagewidth printers, portable color and monochrome printers, color and monochrome copiers, color and monochrome facsimile machines, combined printer, facsimile and copying machines, label printers, large format plotters, photograph copiers, printers for digital photographic “minilabs”, video printers, PHOTO CD (PHOTO CD is a registered trade mark of the Eastman Kodak Company) printers, portable printers for PDAs, wallpaper printers, indoor sign printers, billboard printers, fabric printers, camera printers and fault tolerant commercial printer arrays.
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 embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects to be illustrative and not restrictive.

## Claims

1. A nozzle arrangement for an inkjet printer, the nozzle arrangement comprising:
a nozzle chamber;
an ink supply channel for supplying ink to the nozzle chamber;
a cover for covering the nozzle chamber, the cover defining an ink ejection port through which ink is ejected;
a plurality of thermal bend actuators radially arranged around the ink ejection port; and
a plurality of heater elements each corresponding to one of the plurality of thermal bend actuators, each heater element provided at an end of a corresponding thermal bend actuator opposite the ink ejection port.

2. A nozzle arrangement as claimed in claim 1, wherein each thermal bend actuator comprises a polytetrafluoroethylene (PTFE) layer.

3. A nozzle arrangement as claimed in claim 1, wherein each heater element comprises an internal serpentine copper core connected to drive circuitry.

4. A nozzle arrangement as claimed in claim 1, wherein the plurality of thermal bend actuators form a generally segmented annulus shape.

5. A nozzle arrangement as claimed in claim 1, wherein each thermal bend actuator defines a well for collecting ink spatter from the rim.

6. A nozzle arrangement as claimed in claim 1, wherein the cover is substantially planar when each thermal bend actuator is de-activated.

7. A nozzle arrangement as claimed in claim 1, wherein each of the thermal bend actuators are adapted to bend into the nozzle chamber.