Coating processes – Interior of hollow article coating – Removing excess coating material
Reexamination Certificate
2001-10-31
2004-05-18
Barr, Michael (Department: 1762)
Coating processes
Interior of hollow article coating
Removing excess coating material
C427S230000, C427S236000, C427S238000, C427S239000, C427S294000, C427S295000, C427S350000, C427S356000, C427S388100, C427S409000, C427S421100, C347S045000
Reexamination Certificate
active
06737109
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to a method of coating the ejector of an inkjet printhead and to the ejector surfaces so coated.
2. Description of Related Art
Acoustic inkjet printing processes are known. See, for example, U.S. Pat. No. 6,255,383 to Hanzlik, incorporated by reference herein in its entirety. As described therein, an acoustic beam exerts a radiation pressure against objects upon which it impinges. Thus, when an acoustic beam impinges on a free surface (i.e., liquid/air interface) of a pool of liquid from beneath, the radiation pressure which it exerts against the surface of the pool may reach a sufficiently high level to release individual droplets of liquid from the pool, despite the restraining force of surface tension. Focusing the beam on or near the surface of the pool intensifies the radiation pressure it exerts for a given amount of input power. These principles have been applied to prior ink jet and acoustic printing proposals. For example, K. A. Krause, “Focusing Ink Jet Head,” IBM Technical Disclosure Bulletin, Vol. 16, No. 4, September 1973, pp. 1168-1170, the disclosure of which is totally incorporated herein by reference, describes an ink jet in which an acoustic beam emanating from a concave surface and confined by a conical aperture is used to propel ink droplets out through a small ejection orifice.
Acoustic ink printers typically comprise one or more acoustic radiators for illuminating the free surface of a pool of liquid ink with respective acoustic beams. Each of these beams usually is brought to focus at or near the surface of the reservoir (i.e., the liquid/air interface). Furthermore, printing conventionally is performed by independently modulating the excitation of the acoustic radiators in accordance with the input data samples for the image that is to be printed. This modulation enables the radiation pressure which each of the beams exerts against the free ink surface to make brief, controlled excursions to a sufficiently high pressure level for overcoming the restraining force of surface tension. That, in turn, causes individual droplets of ink to be ejected from the free ink surface on demand at an adequate velocity to cause them to deposit in an image configuration on a nearby recording medium. The acoustic beam may be intensity modulated or focused/defocused to control the ejection timing, or an external source may be used to extract droplets from the acoustically excited liquid on the surface of the pool on demand. Regardless of the timing mechanism employed, the size of the ejected droplets is determined by the waist diameter of the focused acoustic beam.
Acoustic ink printing is attractive because it does not require the nozzles or the small ejection orifices which have caused many of the reliability and pixel placement accuracy problems that conventional drop on demand and continuous stream ink jet printers have suffered from. The size of the ejection orifice is a critical design parameter of an ink jet because it determines the size of the droplets of ink that the jet ejects. As a result, the size of the ejection orifice cannot be increased, without sacrificing resolution. Acoustic printing has increased intrinsic reliability because there are no nozzles to clog. As will be appreciated, the elimination of the clogged nozzle failure mode is especially relevant to the reliability of large arrays of ink ejectors, such as page width arrays comprising several thousand separate ejectors. Furthermore, small ejection orifices are avoided, so acoustic printing can be performed with a greater variety of inks than conventional ink jet printing, including inks having higher viscosities and inks containing pigments and other particulate components. It has been found that acoustic ink printers embodying printheads comprising acoustically illuminated spherical focusing lenses can print precisely positioned pixels (i.e., picture elements) at resolutions which are sufficient for high quality printing of relatively complex images.
It has also has been discovered that the size of the individual pixels printed by such a printer can be varied over a significant range during operation, thereby accommodating, for example, the printing of variably shaded images. Furthermore, the known droplet ejector technology can be adapted to a variety of printhead configurations, including (1) single ejector embodiments for raster scan printing, (2) matrix configured ejector arrays for matrix printing, and (3) several different types of pagewidth ejector arrays, ranging from single row, sparse arrays for hybrid forms of parallel/serial printing to multiple row staggered arrays with individual ejectors for each of the pixel positions or addresses within a pagewidth image field (i.e., single ejector/pixel/line) for ordinary line printing.
Inks suitable for acoustic ink jet printing typically are liquid at ambient temperatures (i.e., about 25° C.), but in other embodiments the ink is in a solid state at ambient temperatures and provision is made for liquefying the ink by heating or any other suitable method prior to introduction of the ink into the printhead. Images of two or more colors can be generated by several methods, including by processes wherein a single printhead launches acoustic waves into pools of different colored inks. Further information regarding acoustic inkjet printing apparatus and processes is disclosed in, for example, U.S. Pat. Nos. 4,308,547, 4,697,195, 5,028,937, 5,041,849, 4,751,529, 4,751,530, 4,751,534, 4,801,953, and U.S. Pat. No. 4,797,693, the disclosures of each of which are totally incorporated herein by reference.
A major source of ink jet misdirection is associated with improper wetting of the surface of the acoustic ink jet printhead. One factor which adversely affects directional accuracy is the interaction of ink accumulating on the surface of the printhead with the ejected ink droplets. Ink may accumulate on the printhead surface after extended expelling of the droplets of ink from the printhead. When the accumulating ink on the printhead surface makes contact with ink to be expelled, a resulting imbalance of the forces acts on the ejecting ink, which in turn leads to misdirection of the ejected ink. This wetting phenomenon becomes more troublesome after extensive use as the array face oxidizes or becomes covered with a dried ink film, leading to a gradual deterioration of the image quality that the printhead is capable of generating. To retain good ink jet directionality, it is desirable to reduce the wetting of the surface of the printhead.
Thus, the construction and operation of an acoustic ink jet printhead requires that a hydrophobic coating be coated on the inside surfaces of the inkjet printhead such that inks in a solvent do not wet the surfaces of the construction. The ejector surfaces of the printhead must be uniformly coated with the hydrophobic coating material. A uniform thickness of the coating is preferred to provide predictable, accurate printing.
In U.S. Pat. No. 5,451,992 to Shimomura et al., an ink jet head is described that is subjected to a liquid repellency treatment. The liquid repellency treatment is applied to at least a peripheral portion of a discharge port of the ink jet head. A mixture of a fluorine-containing high polymer compound and a compound having fluorine substituted hydrocarbon group and a silazane group, alkoxysilane group or halogenized silane group is employed as a liquid repellent agent. Shimomura describes that an absorbing member is immersed in the liquid repellency agent. The absorbing member is then applied to the discharge port of the inkjet head, thereby coating the liquid repellency treating agent on the discharge port. TEFLON® AF is described as a possible fluorine-containing high polymer compound.
In U.S. Pat. No. 3,946,398 to Kyser et al., a recording apparatus and method is disclosed which includes feeding a writing fluid source to a drop projection means which ejects a series of droplets of writing fluid from a nozzle in a discontinuous
Pan David H.
Stanton Donald S.
Barr Michael
Jolley Kirsten Crockford
Oliff & Berridg,e PLC
Xerox Corporation
LandOfFree
Method of coating an ejector of an ink jet printhead does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of coating an ejector of an ink jet printhead, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of coating an ejector of an ink jet printhead will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3219202