INK EJECTION NOZZLE WITH OSCILLATOR AND SHUTTER ARRANGEMENT

Description

CROSS REFERENCES TO RELATED APPLICATIONS

This is a Continuation Application of U.S. application Ser. No. 11/839,541 filed on Aug. 16, 2007, which is a Continuation Application of U.S. application Ser. No. 11/525,859 filed on Sep. 25, 2006, now issued U.S. Pat. No. 7,270,399, which is a Continuation Application of U.S. application Ser. No. 11/144,804 filed Jun. 6, 2005, now granted U.S. Pat. No. 7,144,098, which is a continuation of U.S. application Ser. No. 10/693,990 filed Oct. 28, 2003, now issued as U.S. Pat. No. 6,929,352, which is a continuation of U.S. application Ser. No. 10/302,606 filed on Nov. 23, 2002, now issued U.S. Pat. No. 6,644,767, which is a Continuation of U.S. application Ser. No. 09/855,094 filed May 14, 2001, now issued U.S. Pat. No. 6,485,123 which is a Continuation-in-part of U.S. application Ser. No. 09/112,815 filed on Jul. 10, 1998, now issued U.S. Pat. No. 6,247,792, all of which is herein incorporated by reference.

The following Australian provisional patent applications are hereby incorporated by reference. For the purposes of location and identification, US patents/patent applications identified by their US patent/patent application serial numbers are listed alongside the Australian applications from which the US patents/patent applications claim the right of priority.

CROSS-	US PATENT/PATENT
REFERENCED	APPLICATION
AUSTRALIAN	(CLAIMING RIGHT
PROVISIONAL	OF PRIORITY FROM
PATENT	AUSTRALIAN PROVISIONAL
APPLICATION NO.	APPLICATION)	DOCKET 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 an ink jet printer for use with a pulsating pressure ink supply.

BACKGROUND OF THE INVENTION

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 on ink jet printing have been invented. For a survey of the field, reference is made to an article by J Moore, “Non-Impact Printing: Introduction and Historical Perspective”, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).

Ink Jet printers themselves come in many different types. The utilisation of a continuous stream ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream 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 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 used 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 used ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which discloses a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode of operation of a piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972) which discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 which discloses a piezoelectric push mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode type of piezoelectric transducer element.

Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned references disclose ink jet printing techniques rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Printing devices using the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.

As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and operation, high speed operation, safe and continuous long term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction operation, durability and consumables.

SUMMARY OF THE INVENTION

According to an aspect of the present disclosure, an ink ejection nozzle includes an ink reservoir with an oscillator configured to oscillate ink pressure in the reservoir; a wafer assembly defining an ink supply channel in fluid communication with the ink reservoir; a nozzle chamber structure on the wafer assembly and defining a nozzle chamber in fluid communication with the ink supply channel, and an ink ejection port in fluid communication with the nozzle chamber; and a shutter positioned in the nozzle chamber and configured to shut the ink ejection port to the ejection of ink from the nozzle chamber. The shutter is moved by a thermoelastic actuator having a coiled serpentine heater.

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:

FIG. 1 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with the preferred embodiment;

FIG. 2 is a perspective view, partly in section, of a single ink jet nozzle constructed in accordance with the preferred embodiment;

FIG. 3 provides a legend of the materials indicated in FIGS. 4 to 16;

FIG. 4 to FIG. 16 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle; and

FIG. 17 shows a schematic, sectional end view of part of an ink jet nozzle array showing two nozzle arrangements of the array;

FIG. 18 shows the array with ink being ejected from one of the nozzle arrangements;

FIG. 19 shows a schematic side view of re-filling of the nozzle of the first nozzle arrangement; and

FIG. 20 shows operation of the array preceding commencement of ink ejection from the second of the illustrated nozzle arrangements.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In the preferred embodiment, an oscillating ink reservoir pressure is used to eject ink from ejection nozzles. Each nozzle has an associated shutter which normally blocks the nozzle. The shutter is moved away from the nozzle by an actuator whenever an ink drop is to be fired.

Turning initially to FIG. 1, there is illustrated in exploded perspective a single ink jet nozzle 10 as constructed in accordance with the principles of the present invention. The exploded perspective illustrates a single ink jet nozzle 10. Ideally, the nozzles are formed as an array on a silicon wafer 12. The silicon wafer 12 is processed so as to have two level metal CMOS circuitry which includes metal layers and glass layers 13 and which are planarised after construction. The CMOS metal layer has a reduced aperture 14 for the access of ink from the back of silicon wafer 12 via an ink supply channel 15.

A bottom nitride layer 16 is constructed on top of the CMOS layer 13 so as to cover, protect and passivate the CMOS layer 13 from subsequent etching processes. Subsequently, there is provided a copper heater layer 18 which is sandwiched between two polytetrafluoroethylene (PTFE) layers 19,20. The copper layer 18 is connected to lower CMOS layer 13 through vias 25,26. The copper layer 18 and PTFE layers 19,20 are encapsulated within nitride borders e.g. 28 and nitride top layer 29 which includes an ink ejection port 30 in addition to a number of sacrificial etched access holes 32 which are of a smaller dimension than the ejection port 30 and are provided for allowing access of a etchant to lower sacrificial layers thereby allowing the use of the etchant in the construction of layers, 18,19,20 and 28.

Turning now to FIG. 2, there is shown a cutaway perspective view of a fully constructed ink jet nozzle 10. The ink jet nozzle uses an oscillating ink pressure to eject ink from ejection port 30. Each nozzle has an associated shutter 31 which normally blocks it. The shutter 31 is moved away from the ejection port 30 by an actuator 35 whenever an ink drop is to be fired.

The ports 30 are in communication with ink chambers which contain the actuators 35. These chambers are connected to ink supply channels 15 which are etched through the silicon wafer. The ink supply channels 15 are substantially wider than the ports 30, to reduce the fluidic resistance to the ink pressure wave. The ink channels 15 are connected to an ink reservoir. An ultrasonic transducer (for example, a piezoelectric transducer) is positioned in the reservoir. The transducer oscillates the ink pressure at approximately 100 KHz. The ink pressure oscillation is sufficient that ink drops would be ejected from the nozzle were it not blocked by the shutter 31.

The shutters are moved by a thermoelastic actuator 35. The actuators are formed as a coiled serpentine copper heater 23 embedded in polytetrafluoroethylene (PTFE) 19/20. PTFE has a very high coefficient of thermal expansion (approximately 770×10⁻⁶). The current return trace 22 from the heater 23 is also embedded in the PTFE actuator 35, the current return trace 22 is made wider than the heater trace 23 and is not serpentine. Therefore, it does not heat the PTFE as much as the serpentine heater 23 does. The serpentine heater 23 is positioned along the inside edge of the PTFE coil, and the return trace is positioned on the outside edge. When actuated, the inside edge becomes hotter than the outside edge, and expands more. This results in the actuator 35 uncoiling.

The heater layer 23 is etched in a serpentine manner both to increase its resistance, and to reduce its effective tensile strength along the length of the actuator. This is so that the low thermal expansion of the copper does not prevent the actuator from expanding according to the high thermal expansion characteristics of the PTFE.

By varying the power applied to the actuator 35, the shutter 31 can be positioned between the fully on and fully off positions. This may be used to vary the volume of the ejected drop. Drop volume control may be used either to implement a degree of continuous tone operation, to regulate the drop volume, or both. When data signals distributed on the printhead indicate that a particular nozzle is turned on, the actuator 35 is energized, which moves the shutter 31 so that it is not blocking the ink chamber. The peak of the ink pressure variation causes the ink to be squirted out of the nozzle 30. As the ink pressure goes negative, ink is drawn back into the nozzle, causing drop break-off. The shutter 31 is kept open until the nozzle is refilled on the next positive pressure cycle. It is then shut to prevent the ink from being withdrawn from the nozzle on the next negative pressure cycle.

Each drop ejection takes two ink pressure cycles. Preferably half of the nozzles 10 should eject drops in one phase, and the other half of the nozzles should eject drops in the other phase. This minimises the pressure variations which occur due to a large number of nozzles being actuated. Referring to FIGS. 17 to 20, the operation of the printhead is described in greater detail.

The printhead comprises an array of nozzle arrangements or nozzles 10, two of which are shown as 10.1 and 10.2 in FIG. 17. Each nozzle arrangement 10 has a chamber 58 in which its associated shutter 31 is arranged.

Each chamber 58 is in communication with an ink reservoir 60 via an ink supply channel 36. An ultrasonic transducer in the form of a piezoelectric transducer 62 is arranged n the ink reservoir 60.

As described above, each ink drop ejection takes two ink pressure cycles. The two ink pressure cycles are referred to as a phase. Half of the nozzles 10 should eject ink drops 64 (FIG. 18) in one phase with the other half of the nozzles ejecting ink drops in the other phase. Consequently, as shown in FIG. 17 of the drawings, the shutter 31.2 of the nozzle 10.2 is in an open position while the shutter 31.1 of the nozzle 10.1 is in its closed position. It will be appreciated that the nozzle 10.2 represents all the open nozzles of the array of the printhead while the nozzle 10.1 represents all the closed nozzles of the array of the printhead.

In a first pressure cycle, the transducer 62 is displaced in the direction of arrows 66 imparting positive pressure to the ink 57 in the reservoir 60 and, via the channels 36, the chambers 58 of the nozzles 10. Due to the fact that the shutter 31.2 of the nozzle 10.2 is open, ink in the ink ejection port 30.2 bulges outwardly as shown by the meniscus 68. After a predetermined interval, the transducer 62 reverses direction to move in the direction of arrows 70 as shown in FIG. 18 of the drawings. This causes necking, as shown at 72, resulting in separation of the ink drop 64 due to a first negative going pressure cycle imparted to the ink 57. In the second positive pressure cycle, as shown in FIG. 19 of the drawings, with the transducer moving again in the direction of arrow 66, the positive pressure applied to the ink results in a refilling of the chamber 58.2 of the nozzle 10.2. It is to be noted that the shutter 31.2 is still in an open position with the shutter 31.1 still being in a closed position. In this cycle, no ink is ejected from either nozzle 10.1 or 10.2. Before the second negative pressure cycle, as shown in FIG. 20 of the drawings, the shutter 31.2 moves to its closed position. Then, as the transducer 62 again moves in the direction of arrows 70 to impart negative pressure to the ink 57, a slight concave meniscus 74 is formed at both ink ejection ports 30.1 and 30.2 However, due to the fact that both shutters 31.1 and 31.2 are closed, withdrawal of ink from the chambers 58.1 and 58.2 of the nozzles 10.1 and 10.2, respectively, is inhibited.

The amplitude of the ultrasonic transducer can be altered in response to the viscosity of the ink (which is typically affected by temperature), and the number of drops which are to be ejected in the current cycle. This amplitude adjustment can be used to maintain consistent drop size in varying environmental conditions. The drop firing rate can be around 50 KHz. The ink jet head is suitable for fabrication as a monolithic page wide printhead. FIG. 2 shows a single nozzle of a 1600 dpi printhead in “up shooter” configuration.

Returning again to FIG. 1, one method of construction of the ink jet print nozzles 10 will now be described. Starting with the bottom wafer layer 12, the wafer is processed so as to add CMOS layers 13 with an aperture 14 being inserted. The nitride layer 16 is laid down on top of the CMOS layers so as to protect them from subsequent etchings.

A thin sacrificial glass layer is then laid down on top of nitride layers 16 followed by a first PTFE layer 19, the copper layer 18 and a second PTFE layer 20. Then a sacrificial glass layer is formed on top of the PTFE layer and etched to a depth of a few microns to form the nitride border regions 28. Next the top layer 29 is laid down over the sacrificial layer using the mask for forming the various holes including the processing step of forming the rim 40 on nozzle 30. The sacrificial glass is then dissolved away and the channel 15 formed through the wafer by means of utilisation of high density low pressure plasma etching such as that available from Surface Technology Systems.

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

1. Using a double sided polished wafer 12, complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 13. The wafer is passivated with 0.1 microns of silicon nitride 16. This step is shown in FIG. 4. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. FIG. 3 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

2. Etch nitride and oxide down to silicon using Mask 1. This mask defines the nozzle inlet below the shutter. This step is shown in FIG. 5.

3. Deposit 3 microns of sacrificial material 50 (e.g. aluminum or photosensitive polyimide)

4. Planarize the sacrificial layer to a thickness of 1 micron over nitride. This step is shown in FIG. 6.

5. Etch the sacrificial layer using Mask 2. This mask defines the actuator anchor point 51. This step is shown in FIG. 7.

6. Deposit 1 micron of PTFE 52.

7. Etch the PTFE, nitride, and oxide down to second level metal using Mask 3. This mask defines the heater vias 25, 26. This step is shown in FIG. 8.

8. Deposit the heater 53, which is a 1 micron layer of a conductor with a low Young's modulus, for example aluminum or gold.

9. Pattern the conductor using Mask 4. This step is shown in FIG. 9.

10. Deposit 1 micron of PTFE 54.

11. Etch the PTFE down to the sacrificial layer using Mask 5. This mask defines the actuator and shutter This step is shown in FIG. 10.

12. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated.

13. Deposit 3 microns of sacrificial material 55. Planarize using CMP

14. Etch the sacrificial material using Mask 6. This mask defines the nozzle chamber wall 28. This step is shown in FIG. 11.

15. Deposit 3 microns of PECVD glass 56.

16. Etch to a depth of (approx.) 1 micron using Mask 7. This mask defines the nozzle rim 40. This step is shown in FIG. 12.

17. Etch down to the sacrificial layer using Mask 6. This mask defines the roof of the nozzle chamber, the nozzle 30, and the sacrificial etch access holes 32. This step is shown in FIG. 13.

18. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 7. This mask defines the ink inlets 15 which are etched through the wafer. The wafer is also diced by this etch. This step is shown in FIG. 14.

19. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch. This step is shown in FIG. 15.

20. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation.

21. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.

22. Hydrophobize the front surface of the printheads.

23. Fill the completed printheads with ink 57 and test them. A filled nozzle is shown in FIG. 16.

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