Liquid ejection device

Details Liquid ejection device Liquid ejection device

2000-02-15

2001-10-23

Barlow, John (Department: 2853)

Incremental printing of symbolic information

Ink jet

Ejector mechanism

C347S020000, C347S044000

Reexamination Certificate

active

06305788

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the field of micro mechanical or micro electromechanical liquid ejection devices. 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 to other micro mechanical or micro electro-mechanical devices, e.g. micro electromechanical pumps.
BACKGROUND OF THE INVENTION
Micro mechanical and micro electromechanical devices are becoming increasingly popular and normally involve the creation of devices on the micrometer (micron) scale utilizing semi-conductor fabrication techniques. For a recent review on micro-mechanical 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 utilising 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 liquid ejection devices for use in the MEMJET technology or other micro mechanical or micro electromechanical devices.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the present invention, there is provided a liquid ejection device comprising a nozzle chamber, an ejection paddle located within the nozzle chamber for ejecting liquid from the nozzle chamber though an aperture in one wall of the nozzle chamber when the paddle is moved from a first state into an ejection state, a liquid supply port arranged in a manner such that it is substantially closed by the lo paddle when the paddle is in the first state, and wherein the nozzle chamber comprises an internal protrusion on a wall structure thereof which is aligned closely adjacent to a rim of the paddle when the paddle is in the first state, and wherein, in the ejection state, at least a portion of the rim of the paddle is spaced apart from the protrusion, thereby forming a liquid refill channel defined between the wall structure and the portion of the rim of the paddle.
The internal protrusion may have a staircase-like cross-sectional profile.
The paddle and the internal protrusion are preferably formed in one deposition step.
The internal protrusion may be formed using a lower aspect ratio deposition step when compared to a high aspect ratio deposition step for forming the wall structure of the nozzle chamber.
The paddle may be substantially planar.


REFERENCES:
patent: 5278585 (1994-01-01), Karz et al.
patent: 5838351 (1998-11-01), Weber

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