Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-02-15
2001-11-27
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S054000, C347S044000
Reexamination Certificate
active
06322195
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of liquid ejection devices such as ink jet printers. The present invention will be described herein with reference to Micro Electro Mechanical Inkjet technology. However, it will be appreciated that the invention does have broader applications, e.g. to other micromechanical and micro-electro mechanical devices such as micro mechanical liquid pumps.
BACKGROUND OF THE INVENTION
Micromechanical and micro-electro mechanical devices are becoming increasingly popular and normally involve the creation of devices on the &mgr;m (micron) scale utilizing semi-conductor fabrication techniques. For a recent review on micromechanical devices, reference is made to the article “The Broad Sweep of Integrated Micro Systems” by S. Tom Picraux and Paul J. McWhorter published December 1998 in IEEE Spectrum at pages 24 to 33.
One form of micro-electromechanical devices in popular use are ink jet printing devices in which ink is ejected from an ink ejection nozzle chamber. Many forms of ink jet devices are known.
Many different techniques on ink jet printing and associated devices 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 to 220 (1988).
Recently, a new form of ink jet printing has been developed by the present applicant, which is referred to as Micro Electro Mechanical Inkjet (MEMJET) technology. In one form of the MEMJET technology, ink is ejected from an ink ejection nozzle chamber utilizing an electro mechanical actuator connected to a paddle or plunger which moves towards the ejection nozzle of the chamber for ejection of drops of ink from the ejection nozzle chamber.
The present invention concerns improvements to a paddle for use in the MEMJET technology or other micro mechanical or micro electromechanical liquid ejection devices.
SUMMARY OF THE INVENTION
A paddle for ejecting liquid from within a nozzle chamber out through a liquid ejection nozzle defined in one wall of the nozzle chamber, the paddle comprising a first portion being configured to, in use, provide a substantially planar plunger surface opposite to and spaced apart from the nozzle, and a second portion formed on the plunger surface in the periphery of the first portion for providing structural support for the first portion, whereby, in use, during actuation of the plunger to eject liquid through the nozzle the second portion acts as a spacer preventing the plunger surface from reaching the nozzle.
Having the plunger surface spaced apart form the nozzle is important to reduce the likelihood of a meniscus of the liquid at the nozzle making contact with the plunger surface, which could affect the operational characteristics of such an arrangement. It will be appreciated by a person skilled in the art that accordingly the size of a chamber embodying the present invention can be reduced for the same ejection volume, when compared with a paddle having a constant thickness, previously thought to be required for structural soundness.
The second portion may be configured to define a continuous wall structure around a center portion of the plunger surface, the center portion, in use, being substantially aligned with the nozzle.
The center portion may preferably be of the same dimensions as the nozzle.
The first portion can have a circular circumference and the second portion can comprise an annulus around the circumference of the paddle.
The paddle can be substantially symmetrically arranged around the liquid ejection nozzle and can be formed by: depositing and etching a first layer to form the first paddle portion; depositing and etching a second layer to form a sacrificial layer supporting structure over the first paddle portion; and depositing and etching a third layer to from the third paddle portion.
REFERENCES:
patent: 6007187 (1999-12-01), Kashino et al.
patent: 404001051 (1992-01-01), None
patent: 406106723 (1994-04-01), None
Barlow John
Silverbrook Research PTY Ltd.
Stephens Juanita
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