Metal working – Method of mechanical manufacture – Fluid pattern dispersing device making – e.g. – ink jet
Reexamination Certificate
1998-01-08
2001-04-03
Cuda, Irene (Department: 3726)
Metal working
Method of mechanical manufacture
Fluid pattern dispersing device making, e.g., ink jet
C347S047000
Reexamination Certificate
active
06209203
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to printheads for thermal inkjet print cartridges. More particularly, this invention relates to the manufacture of nozzle plates for printheads.
BACKGROUND OF THE INVENTION
Thermal inkjet printers utilize print cartridges having printheads for directing ink droplets onto a medium, such as paper, in patterns corresponding to the indicia to be printed on the paper. In general, ink is directed from a reservoir via flow paths to bubble chambers and associated orifices or nozzles for release onto the paper. Heaters are provided adjacent the nozzles for heating ink supplied to the nozzles to vaporize a component in the ink in order to propel droplets of ink through the nozzle holes to provide a dot of ink on the paper. During a printing operation the print head is moved relative to the paper and ink droplets are released in patterns corresponding to the indicia to be printed by electronically controlling the heaters to selectively operate only the heaters corresponding to nozzles through which ink is to be ejected for a given position of the printhead relative to the paper.
Printheads typically include a nozzle plate attached, as by adhesive, to a silicon chip containing the heating elements. The flowpaths, bubble chambers and nozzles are typically provided by laser ablating the nozzle plate material to provide such structure. As will be appreciated, the precision and uniformity of such features significantly affect the quality of printing. Thus, for example, if the walls which surround the nozzles and define the bubble chambers do not smoothly interface the silicon chip, leakage can result and adversely affect print quality. Conventional methods for manufacturing nozzle plates often fail to provide the desired precision and uniformity of the flow features thus adversely affecting the yield of usable nozzle plates and/or the performance of the printer.
Accordingly it is an object of the present invention to provide an improved method for the manufacture of inkjet printheads.
Another object of the present invention is to provide a method of the character described which enables the production of printheads having greater reliability and performance characteristics as compared to printheads provided using conventional techniques.
A further object of the present invention is to provide a method for manufacturing a printhead having an improved nozzle and heater array.
An additional object of the present invention is to provide a method of the character described which avoids many of the disadvantages of conventional methods.
SUMMARY OF THE INVENTION
Having regard to the foregoing and other objects, the present invention is directed to a method for making a nozzle plate for an inkjet printer by laser ablating a nozzle plate material. The method includes the steps of a) selecting a plurality of desired nozzle hole locations, b) ablating a first portion of the nozzle plate material in an area of the nozzle plate material adjacent each nozzle hole location to a predetermined depth to provide a plurality of flow paths c) ablating nozzle holes through the full thickness of the nozzle plate material at each desired nozzle hole location, wherein unablated material remains adjacent each nozzle hole to provide an ink chamber, and d) ablating a throat region through a second portion of the nozzle plate material adjacent each nozzle hole so that each ink chamber is in flow communication with at least one flow path outside of the chamber.
The method of the invention enables nozzle plates of improved quality and precision as compared to those manufactured using conventional techniques. For example, the method enables the manufacture of nozzle plates having smoother and more uniform surfaces as well as finer flow features. In particular, the invention enables the formation of bubble chamber walls having a thickness of less than about 10 microns and having substantially uniform wall features which provide an improved interface between the nozzle plate and the underlying silicon chip so that problems associated with ink leaking between the upper wall edges of the ink chambers and the silicon chip is substantially avoided.
According to another aspect of the invention, the invention provides a method for making a nozzle plate for an inkjet printer by laser ablating a nozzle plate material. The method includes the steps of laser ablating the nozzle plate material to provide a first nozzle hole array having a plurality of nozzle holes, each of which is positioned to correspond to a desired print location, with the print location of each of the nozzle holes of the first nozzle array being different from one another; and laser ablating the nozzle plate material to provide a second nozzle hole array having a plurality of nozzle holes, each nozzle hole of the second nozzle hole array being positioned to correspond to a desired print location, with the print location of each of the nozzle holes of the second array corresponding to one of the print locations of the first nozzle hole array such that the first and second nozzle hole arrays each have a nozzle hole corresponding to each desired print location so that at least two nozzle holes are provided for each print location.
Preferred nozzle plates manufactured in accordance with the invention provide a redundancy feature in that the resulting printhead includes at least two nozzle holes (and associated heaters) for each print location. During a printing process, the printer controller alternates between the at least two nozzles such that the effect of an improperly operating heater and/or nozzle is significantly reduced.
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Murthy Ashok
Powers James Harold
Srinivasan Sudarsan
Cuda Irene
Lexmark International Inc.
Nguyen Trinh T.
Sanderson Michael T.
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