Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-03-21
2003-04-01
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S048000
Reexamination Certificate
active
06540339
ABSTRACT:
THE FIELD OF THE INVENTION
The present invention relates generally to fluid drop ejectors, and more particularly to a flextensional transducer assembly for ejecting droplets of a flowable material.
BACKGROUND OF THE INVENTION
Fluid drop ejectors have been developed for ejecting droplets of a flowable material in a controlled manner. An example of a fluid drop ejector includes a flextensional transducer. As illustrated in
FIGS. 1A and 1B
, a conventional flextensional transducer
90
includes a cylindrical body
92
, a circular flexible membrane
94
having an orifice
96
defined therein, and an annular actuator
98
. The cylindrical body defines a reservoir for holding a supply of flowable material and the circular flexible membrane has a circumferential edge clamped to the cylindrical body. The annular actuator includes a piezoelectric material which deforms when an electrical voltage is applied. As such, when the piezoelectric material deforms, the circular flexible membrane deflects causing a quantity of flowable material to be ejected through the orifice from the reservoir.
One application of a flextensional transducer is in an inkjet printing system. As such, the inkjet printing system includes a printhead including a plurality of flextensional transducers which eject droplets of ink through orifices or nozzles to form an image on a print medium. One way to improve a quality of the image is to increase the resolution of the image. Resolution of the image is measured in dots-per-inch. To increase the resolution, therefore, the number of dots per inch must increase. Accordingly, the number of drops per inch must increase.
One way to increase the number of drops per inch is to increase the number of orifices or nozzles per unit of area of the printhead. Thus, a density of the flextensional transducers which eject the drops must increase. Therefore, for a fixed drop size, a spacing between the flextensional transducers and, more specifically, a spacing between the orifices or nozzles must decrease. Since the conventional flextensional transducer is cylindrical in shape, an arrangement of and/or spacing between the flextensional transducers is restricted by the cylindrical shape. Thus, increasing the density of a plurality of conventional flextensional transducers is limited.
Accordingly, a need exists for a flextensional transducer which provides greater flexibility in a design of an individual flextensional transducer as well as an arrangement of a plurality of flextensional transducers. More particularly, a need exists for a flextensional transducer which enables a compact array and, therefore, a greater density of orifices of a plurality of flextensional transducers.
SUMMARY OF THE INVENTION
One aspect of the present invention provides a flextensional transducer assembly. The flextensional transducer assembly includes a substrate having a plurality of fluid cavities formed therein, a plurality of flexible membrane portions each supported by the substrate, and a plurality of actuators each associated with one of the flexible membrane portions. Each of the flexible membrane portions have a pair of spaced edges and an orifice defined therein which communicates with one of the fluid cavities. As such, each of the flexible membrane portions is adapted to deflect in response to application of an electrical signal to an associated one of the actuators.
In one embodiment, each of the fluid cavities is adapted to hold a supply of fluid in communication with the orifice of an associated one of the flexible membrane portions. In one embodiment, the orifice of each of the flexible membrane portions defines a nozzle adapted to eject a quantity of the fluid in response to deflection of the associated one of the flexible membrane portions.
In one embodiment, the substrate includes a plurality of opposing sidewalls which define opposing sides of the fluid cavities. In one embodiment, the pair of spaced edges of each of the flexible membrane portions are positioned within associated ones of the sidewalls of the substrate. In one embodiment, the pair of spaced edges of each of the flexible membrane portions are formed by a pair of spaced slits. In one embodiment, each of the actuators includes a piezoelectric material.
In one embodiment, each of the plurality of flexible membrane portions has an axis extending between opposite ends thereof. In one embodiment, the axis of one of the flexible membrane portions is oriented substantially parallel to the axis of an adjacent one of the flexible membrane portions. In another embodiment, the axis of one of the flexible membrane portions is oriented at an angle to the axis of an adjacent one of the flexible membrane portions.
In one embodiment, the orifice of each of the flexible membrane portions has an axis extending substantially perpendicular to the axis of an associated one of the flexible membrane portions. In one embodiment, the axis of the orifice of one of the flexible membrane portions is aligned with the axis of the orifice of another one of the flexible membrane portions. In another embodiment, the axis of the orifice of one of the flexible membrane portions is offset relative to the axis of the orifice of another one of the flexible membrane portions.
In one embodiment, the axis of the orifice of one of the flexible membrane portions is aligned with the axis of the orifice of an adjacent one of the flexible membrane portions. In another embodiment, the axis of the orifice of one of the flexible membrane portions is offset relative to the axis of the orifice of an adjacent one of the flexible membrane portions.
In one embodiment, the orifice of each of the flexible membrane portions is spaced radially a predetermined distance from a common point.
Another aspect of the present invention provides an inkjet printing system. The inkjet printing system includes a substrate having a plurality of fluid cavities formed therein, a plurality of flexible membrane portions each supported by the substrate, and a plurality of actuators each associated with one of the flexible membrane portions. Each of the flexible membrane portions have a pair of spaced edges and an orifice defined therein which communicates with one of the fluid cavities. As such, each of the flexible membrane portions is adapted to deflect in response to application of an electrical signal to an associated one of the actuators.
Another aspect of the present invention provides a flextensional transducer assembly. The flextensional transducer assembly includes a substrate having a plurality of fluid cavities formed therein, a plurality of flexible membrane portions each supported by the substrate and having an orifice defined therein which communicates with one of the fluid cavities, a plurality of actuators each associated with one of the flexible membrane portions, and a compliant feature adjacent each of the actuators. Each of the flexible membrane portions is adapted to deflect in response to application of an electrical signal to an associated one of the actuators. As such, the compliant feature facilitates deflection of an associated one of the flexible membrane portions.
The present invention provides a flextensional transducer adapted to eject droplets of a fluid in a controlled manner. The flextensional transducer includes an actuator which deflects a flexible membrane portion in response to an electrical signal. The flexible membrane portion has spaced edges and an orifice defined therein such that deflection of the flexible membrane portion causes ejection of fluid from a fluid cavity and through the orifice. In addition, the present invention provides a flextensional transducer assembly which includes a plurality of flextensional transducers arranged in an array.
REFERENCES:
patent: 4533082 (1985-08-01), Maehara et al.
patent: 4605167 (1986-08-01), Maehara
patent: 5152456 (1992-10-01), Ross et al.
patent: 5255016 (1993-10-01), Usui et al.
patent: 5518179 (1996-05-01), Humberstone et al.
patent: 5659346 (1997-08-01), Moynihan et al.
patent: 5828394 (1998-10-01), Khuri
Hewlett--Packard Company
Vo Anh T. N.
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