The present invention relates to micro-fluid ejection devices, such as inkjet printers. More particularly, although not exclusively, it relates to ejection heads having multiple ejection chips adjacently joined to create a lengthy micro-fluid ejection array or print swath.
The art of printing images with micro-fluid technology is relatively well known. A permanent or semi-permanent ejection head has access to a local or remote supply of fluid. The fluid ejects from an ejection zone to a print media in a pattern of pixels corresponding to images being printed. Over time, the heads and fluid drops have become increasingly smaller. Multiple ejection chips joined together are also known to make large arrays, such as in page-wide printheads.
In large arrays, fluid ejections near boundaries of adjacent chips have been known to cause problems of image “stitching.” That is, registration needs to occur between fluid drops from adjacent firing elements, but getting them stitched together is difficult especially when the firing elements reside on different substrates. Also, stitching challenges increase as arrays grow into page-wide dimensions, or larger, since print quality improves as the print zone narrows in width. Some prior art designs with narrow print zones have introduced firing elements for colors shifted laterally by one fluid via to align lengthwise with a different color near terminal ends of their respective chips. This, however, complicates chip fabrication. In other designs, complex chip shapes have been observed. This too complicates fabrication.
In still other designs, narrow print zones have tended to favor narrow ejection chips. Between colors, however, narrow chips leave little room to effectively seal off colors from other colors. Narrow chips also have poor mechanical strength, which can cause elevated failure rates during subsequent assembly processes. They also leave limited space for distribution of power, signal and other routing of lines.
Accordingly, a need exists to significantly improve ejection chips in larger micro-fluid arrays. The need extends not only to improving stitching, but to manufacturing. Additional benefits and alternatives are also sought when devising solutions.
The above-mentioned and other problems become with ejection chips having skewed nozzle arrays for micro-fluid applications. A micro-fluid ejection head has multiple ejection chips joined adjacently to create a lengthy array across a print media, also known as stationary page-wide printheads. The chips have skewed ink vias paralleling a skewed periphery to enable seamless stitching of fluid ejections. Each chip includes firing elements arranged along the vias that become energized to eject fluid and individual ones have spacing according to color. Overlapping firing elements serve redundancy efforts during imaging. Variable chips sizes and shapes are disclosed as are relationships between differently colored fluid vias. Fluid via lengths range from one-half to four mm and colors are adjacent across or down the chips. Representative skew angles range from five to eighty-five degrees with examples given for thirty and forty-five degrees. Singulating individual chips from larger wafers provide still further embodiments. Dicing lines, etch patterns and techniques are disclosed.
These and other embodiments will be set forth in the description below. Their advantages and features will become readily apparent to skilled artisans. The claims set forth particular limitations.
The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings:
In the following detailed description, reference is made to the accompanying drawings where like numerals represent like details. The embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that other embodiments may be utilized and that process, electrical, and mechanical changes, etc., may be made without departing from the scope of the invention. Also, the term wafer or substrate includes any base semiconductor structure, such as silicon-on-sapphire (SOS) technology, silicon-on-insulator (SOI) technology, thin film transistor (TFT) technology, doped and undoped semiconductors, epitaxial layers of silicon supported by a base semiconductor structure, as well as other semiconductor structures hereafter devised or already known in the art. The following detailed description, therefore, is not to be taken in a limiting sense and the scope of the invention is defined only by the appended claims and their equivalents. In accordance with the present invention, methods and apparatus include skewed ejection chips for a micro-fluid ejection head, such as an inkjet printhead.
With reference to
Each chip includes pluralities of fluid firing elements (shown as darkened circles representing nozzles). The elements are any of a variety, but contemplate resistive heaters, piezoelectric transducers, or the like. They are formed on the chip through a series of growth, patterning, depositing, evaporating, sputtering, photolithography or other techniques. They have spacing along an ink via to eject fluid from the chip at times pursuant to commands of a printer microprocessor or other controller. The timing corresponds to a pattern of pixels of the image being printed on the media. The color of fluid also corresponds to the source of ink, such as those labeled C (cyan), M (magenta), Y (yellow), K (black).
In
Via length×Cos [skew angle]=Horizontal separation between same color vias [Equation 1].
A cell print zone width (1.2 mm) perpendicular to the skew via is denoted as:
Cell print zone width ⊥ skew via=Via length×Cos [skew angle]×Sin [skew angle]=½×Via length×Sin [2×skew angle] [Equation 2].
According to Equation 2, a via seal distance that is proportional to a cell print zone width, perpendicular to a skew via, can be altered by changing the skew angle, such as in
Of course, the size of the seal distance contributes to mechanical strength of a chip since the more structure that exists between adjacent ink vias the stronger the chip. Also, the more the structure that exists, the more room that is available for actions involving the dispensing of adhesives, bonding the ejection chip to other structures, laminating the seal area, or the like. On the other hand, extending the seal distance comes at the expense of chip width growing from 2 mm in
With reference to
dpi media resolution={2/a×Sec[skew angle]}×{2/a×Csc[skew angle]} [Equation 3].
With reference to
With reference to
In any wafer, skew vias 75 are etched by DRIE (deep reactive ion etching) or other processes at chip ends. Along the edges of the chips, a hole pattern 77 is formed by the same etching step. The pattern consists of interleaved full and half-patterned holes 76, 79. The wafer is mechanically diced at the lowest cost to individual chips along horizontal lines 91. Dicing blade thicknesses are assumed to be 0.1 mm, therefore, only the solid part 90 between two holes will be diced when the dicing blade is aligned with the centers of the full holes 76. In this manner, all cracks introduced by the dicing process are bounded by the holes. In addition, the etched holes along the horizontal dicing streets greatly reduce dicing slurry from contaminating concurrently formed nozzle plates. Skilled artisans will also observe that the shapes of the chips are relatively simple compared to the complex shapes in the prior art. In turn, the introduction of dicing when the prior art has none greatly simplifies singulation.
With reference to
Relatively apparent advantages should now be readily apparent to skilled artisans. They include, but are not limited to: (1) high mechanical strength ejection chips for at least the reason of shorter ink vias along skew directions; (2) easier power distribution or other signal routing along many spacious “streets” between adjacent ink vias; (3) seamless in-line stitching because of relatively large stitching seal distances; (4) high imaging resolutions with traditional nozzle spacing; and (5) easy silicon fabrication, including traditional dicing techniques.
The foregoing has been presented for purposes of illustrating the various aspects of the invention. It is not intended to be exhaustive or to limit the claims. Rather, it is chosen to provide the best illustration of the principles of the invention and its practical application to enable one of ordinary skill in the art to utilize the invention, including its various modifications that naturally follow. All such modifications and variations are contemplated within the scope of the invention as determined by the appended claims. Relatively apparent modifications, naturally, include combining one or more features of various embodiments with one another.
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“Memjet Printhead”, www.memjetwideformat.com/technology/printhead/, 2 pp, printed May 27, 2010. |
Number | Date | Country | |
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20110292122 A1 | Dec 2011 | US |