Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-07-22
2001-09-18
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S048000, C347S070000, C347S071000
Reexamination Certificate
active
06290339
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to the field of fluid flow and, more particularly, to a method of directing fluid flow through a micro-orifice manifold using a functionally gradient piezoelectric element.
BACKGROUND OF THE INVENTION
Piezoelectric ink jet elements are used in a wide range of micro-fluidic printing devices. Conventional ink jet elements utilize piezoelectric transducers that comprise one or more uniformly polarized piezoelectric elements with attached surface electrodes. The three most common transducer configurations are multilayer ceramic, mono-morph or bi-morphs, and flex-tensional composite transducers. To activate a transducer, a voltage is applied across its electrodes thereby creating an electric field throughout the piezoelectric elements. This field induces a change in the geometry of the piezoelectric elements resulting in elongation, contraction, shear or combinations thereof. The induced geometric distortion of the elements can be used to implement motion or perform work. In particular, piezoelectric bimorph transducers that produce a bending motion, are commonly used in micro-pumping devices. However, a drawback of the conventional piezoelectric bimorph transducer is that two bonded piezoelectric elements are needed to implement the bending. These bimorph transducers are typically difficult and costly to manufacture for micro-pumping applications (in this application, the word micro means that the dimensions of the element range from
100
microns to
10
mm). Also, when multiple bonded elements are used, stress induced in the elements due to their constrained motion can damage or fracture an element due to abrupt changes in material properties and strain at material interfaces.
Therefore, a need persists for an ink jet head that overcomes the aforementioned problems associated with conventional ink jet apparatus.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method of directing fluid flow through a micro-orifice manifold actuated by a functionally gradient piezoelectric actuating element.
It is a feature of the invention that a functionally gradient piezoelectric transducer is provided integral to the micro-orifice manifold that actuates the flow of fluid between a fluid containment chamber in the manifold and a reservoir.
To accomplish these and other objects of the invention, there is provided a method of directing fluid flow between a reservoir and any one of a plurality of independent fluid containment chambers of the micro-fluidic manifold. The method of the invention involves the steps of providing a piezoelectric actuator element (described in details below) in structural relations with each one of the fluid containment chambers. Further included is the step of providing a source of power operably associated with each one of a plurality of first electrodes and a second electrode of the piezoelectric transducer for enabling fluid flow through any one of the plurality of fluid containment chambers of the micro-orifice manifold. The piezoelectric transducer is then actuated in a manner fully described herein for pumping fluid between any one of independent fluid containment chambers of the manifold and the reservoir.
REFERENCES:
patent: 5802686 (1998-09-01), Shimada et al.
Chatterjee Dilip K.
Furlani Edward P.
Ghosh Syamal K.
Bailey, Sr. Clyde E.
Barlow John
Do An H.
Eastman Kodak Company
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