Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2003-12-08
2004-12-21
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S054000
Reexamination Certificate
active
06832828
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the construction of micro-electro mechanical devices such as ink jet printers.
BACKGROUND OF THE INVENTION
In international patent application PCT/AU98/00550, the present applicant has proposed an ink jet printing device which utilizes micro-electro mechanical (MEMS) processing techniques in the construction of a print head driven by thermal bend actuator devices for the ejection of fluid such as ink from an array of nozzle chambers.
Devices of this type have a number of limitations and problems.
It is an object of the present invention to provide various aspects of an inkjet printing device which overcomes or at least ameliorates one of or more of the disadvantages of the prior art or which at least offers a useful alternative thereto.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a micro-electromechanical fluid ejection device that comprises
a substrate;
a nozzle chamber wall and a roof wall that are positioned on the substrate to define a nozzle chamber and an ink ejection port in the roof wall, a fluid being receivable in the nozzle chamber;
an elongate actuator arm having a fixed end portion that is fast with the substrate and a free end portion that is spaced from the substrate, the elongate actuator arm incorporating a heating circuit that is connectable to a power supply to heat the actuator arm, at least a portion of the actuator arm being of a material having a coefficient of thermal expansion which is such that the material is capable of thermal expansion to do work, the heating circuit being positioned to generate differential thermal expansion and contraction when heated and subsequently cooled to cause reciprocal displacement of the free end portion of the actuator arm;
a fluid ejection member that is fast with the free end of the elongate actuator arm to be positioned in the nozzle chamber such that said displacement of the free end portion of the actuator arm results in the ejection of fluid from the ink ejection port; and
control logic circuitry positioned on the substrate along an elongate region defined on the substrate and interposed between the actuator arm and the substrate, the control logic circuitry being connected to the heating circuit to enable and disable the power supply according to a control signal received by the control logic circuitry.
The elongate actuator arm may be a laminated structure having a first metal layer and a dielectric layer, the first metal layer being interposed between the dielectric layer and the substrate and defining the heating circuit.
The actuator arm may have a second metal layer that is positioned so that the dielectric layer is interposed between the metal layers, said second metal layer being substantially the same as the first metal layer.
The metal layers and the dielectric layer may project from the free end of the actuator arm to define the fluid ejection member. A discontinuity may be defined in the first metal layer between the heating circuit and the fluid ejection member.
The control logic circuitry may define transfer register circuitry to receive control signals and drive transistor circuitry connected to the transfer register circuitry. The drive transistor circuitry may be interposed between the heating circuit and the substrate and may be defined by a plurality of traces that are positioned to extend transversely with respect to a longitudinal axis of the actuator arm.
The invention extends to a printhead which comprises a plurality of micro-electromechanical fluid ejection devices as described above.
In accordance with a second aspect of the present invention, there is provided an inkjet printhead having a series of nozzles for the ejection of ink wherein each said nozzle has a rim formed by the conformal deposition of a rim material layer over a sacrificial layer and a subsequent planar etching of at least said rim material layer so as to form said nozzle rim.
The planar etching can comprise chemical-mechanical planarization of the rim material layer and any associated sacrificial layers.
In accordance with a third aspect of the present invention, there is provided an inkjet printhead comprising:
a plurality of nozzle chambers each having an ink ejection aperture in one wall thereof and an actuator interconnection aperture in a second wall thereof;
a moveable ink ejection paddle located within the nozzle chamber and moveable under the control of an external thermal actuator through said actuator interconnection aperture for the ejection of ink out of said ink ejection aperture;
said external actuator being covered by a protective covering shell around the operational portions of said actuator, spaced apart from said actuator.
The protective covering shell can be formed simultaneously with the formation of other portions of the inkjet printing arrangement in particular with the nozzle chamber walls.
The external actuator can comprise a thermal bend actuator.
In accordance with a third aspect of the present invention, there is provided a method of forming an inkjet printhead on a substrate said method including:
providing a first substrate on which is formed electrical drive circuitry made up of one or more interleaved layers of conductive, semi-conductive and non-conductive material for the control of said inkjet printed;
forming on said substrate at least one nozzle chamber having an ink ejection aperture in one wall thereof;
providing a moveable ink ejection paddle within said nozzle chamber, moveable under the control of an actuator for the ejection of ink out of said ink ejection aperture;
and utilizing portions of at least one of said interleaved layers as a sacrificial material layer in the formation of one or more of the group comprising said actuator and said ink ejection paddle.
The sacrificial material layer can comprise portions of a conductive layer of the electrical drive circuitry. The electrical drive circuitry can comprise a Complementary Metal Oxide (CMOS) process and the sacrificial material layer can comprise a CMOS metal layer.
The sacrificial material layer can be utilized in formulating the actor. The actuator can comprise a thermal actuator. The actuator can be located external to the nozzle chamber and can be interconnected to the ink ejection paddle through an actuation interconnection aperture formed in a second wall of the nozzle chamber.
In accordance with a fourth aspect of the present invention, there is provided an inkjet printhead constructed by MEMS processing techniques with a plurality of ink ejection nozzles each having a nozzle chamber, an external thermal bend actuator having a proximal end anchored to a substrate and a distal end connected to an ink ejection paddle within said chamber;
wherein said external thermal bend actuator further comprises a series of layers and includes a planar conductive heating circuit layer which includes a first portion adjacent said proximal end forming a planar conductive heating circuit for heating said thermal bend actuator, and a second portion extending into said ink ejection paddle, said second portion being electrically isolated from said first portion by means of a discontinuity in said planar conductive heating circuit layer, said discontinuity being located external to said nozzle chamber.
The planar conductive heating circuit layer can comprise substantially titanium nitride. The conductive circuit preferably can include at least one tapered portion adjacent the proximal end so as to increase resistive heating adjacent the proximal end.
In accordance with a fifth spect of the present invention, there is provided an inkjet printhead having a series of ink ejection nozzles for the ejection of ink, each of said nozzles interconnecting a nozzle chamber with an external atmosphere, each said nozzle having a first meniscus rim around which an ink meniscus normally forms, and an extended ink flow prevention rim spaced outwardly from said first meniscus rim and substantially encircling said first meniscus rim, arranged to prevent th
Do An H.
Meier Stephen D.
Silverbrook Research Pty Ltd
LandOfFree
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