Reliable high performance drop generator for an inkjet printhead
First Claim
1. An inkjet drop ejection system comprising:
- (a) a substantially rectangular substrate having a top surface and an opposing bottom surface, and having a first outer edge along a periphery of said substrate and a second outer edge along said opposite periphery of said substrate, said substantially rectangular substrate having two opposed edges that are shorter than said first and second outer edges;
(b) a nozzle member having a plurality of ink orifices formed therein, said nozzle member being positioned to overlie said top surface of said substrate;
(c) first and second pluralities of ink ejection elements formed on said top surface of said substrate, each of said ink ejection elements comprising a firing element in a vaporization chamber and being located approximate to an associated one of said orifices for causing a portion of ink to be expelled from said associated orifice as said inkjet drop ejection system is moved along a scan direction, said first plurality of ink ejection elements arranged in a first array along said first outer edge and said second plurality of ink ejection elements arranged in a second array along said second outer edge;
(d) an ink reservoir for holding a quantity of ink;
(e) a fluid channel, communicating with said reservoir, leading to each of said orifices and said ink ejection elements, said fluid channel allowing ink to flow from said ink reservoir, around said first outer edge of said substrate and to said top edge of said substrate so as to be proximate to said orifices and said ink ejection elements;
(f) a separate inlet passage defined by a barrier layer for each vaporization chamber connecting said secondary channel with said vaporization chamber for allowing high frequency refill of said vaporization chamber;
(g) said separate inlet passage for each vaporization chamber having pinch points formed in said barrier layer to prevent cross-talk and overshoot during high frequency operation;
(h) circuit means for transmitting firing signals to said ink firing elements at a maximum frequency greater than 9 KHz;
(i) said inkjet drop ejection system forming a part of a color set of comprising at least one ink, said ink comprising at least one colorant in an aqueous vehicle; and
(j) a support surface under said two shorter edges of said substrate, each support surface including a projection extending beneath said substrate to support said substrate while allowing ink to flow unimpeded around said first outer edge.
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Accused Products
Abstract
An inkjet drop ejection system comprises a combination of printhead components and ink, mutually tuned to maximize operating characteristics of the printhead and print quality and dry time of the ink. Use of a short shelf (distance from ink source to ink firing element), on the order of 55 microns, provides a very high speed refill. However, it is a characteristic of high speed refill that it has a tendency for being overdamped. To provide the requisite damping, the ink should have a viscosity greater than about 2 cp. In this way, the ink and architecture work together to provide a tuned system that enables stable operation at high frequencies. One advantage of the combination of a pigment and a dispersant in the ink is the resultant higher viscosity provided. The high speed would be of little value if the ink did not have a fast enough rate of drying. This is accomplished by the addition of alcohols or alcohol(s) and surfactant(s) to the ink. Fast dry times are achieved with a combination of alcohols, such as isopropyl alcohol with a 4 or 5 carbon alcohol or with iso-propyl alcohol plus surfactant(s). One preferred embodiment of a short shelf (90 to 130 microns), ink viscosity of about 3 cp, and surface tension of about 54 provides a high speed drop generator capable of operating at about 12 KHz. Reducing the shelf length to about 55 microns, in combination with rotating the substrate at an angle to the scan direction, permits maximum drop generator operation as high as about 20 KHz. As a consequence of employing pigment-based inks, high optical densities are realized, along with excellent permanence (no fade and better waterfastness), and good stability. The combination of preferred ink and pen architecture provides good drop generator stability.
90 Citations
42 Claims
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1. An inkjet drop ejection system comprising:
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(a) a substantially rectangular substrate having a top surface and an opposing bottom surface, and having a first outer edge along a periphery of said substrate and a second outer edge along said opposite periphery of said substrate, said substantially rectangular substrate having two opposed edges that are shorter than said first and second outer edges; (b) a nozzle member having a plurality of ink orifices formed therein, said nozzle member being positioned to overlie said top surface of said substrate; (c) first and second pluralities of ink ejection elements formed on said top surface of said substrate, each of said ink ejection elements comprising a firing element in a vaporization chamber and being located approximate to an associated one of said orifices for causing a portion of ink to be expelled from said associated orifice as said inkjet drop ejection system is moved along a scan direction, said first plurality of ink ejection elements arranged in a first array along said first outer edge and said second plurality of ink ejection elements arranged in a second array along said second outer edge; (d) an ink reservoir for holding a quantity of ink; (e) a fluid channel, communicating with said reservoir, leading to each of said orifices and said ink ejection elements, said fluid channel allowing ink to flow from said ink reservoir, around said first outer edge of said substrate and to said top edge of said substrate so as to be proximate to said orifices and said ink ejection elements; (f) a separate inlet passage defined by a barrier layer for each vaporization chamber connecting said secondary channel with said vaporization chamber for allowing high frequency refill of said vaporization chamber; (g) said separate inlet passage for each vaporization chamber having pinch points formed in said barrier layer to prevent cross-talk and overshoot during high frequency operation; (h) circuit means for transmitting firing signals to said ink firing elements at a maximum frequency greater than 9 KHz; (i) said inkjet drop ejection system forming a part of a color set of comprising at least one ink, said ink comprising at least one colorant in an aqueous vehicle; and (j) a support surface under said two shorter edges of said substrate, each support surface including a projection extending beneath said substrate to support said substrate while allowing ink to flow unimpeded around said first outer edge. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification