Electrophotography – Image formation – Fixing
Reexamination Certificate
2001-07-06
2003-03-18
Tran, Hoan (Department: 2852)
Electrophotography
Image formation
Fixing
Reexamination Certificate
active
06535712
ABSTRACT:
RELATED APPLICATIONS
(Not applicable)
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
(Not applicable)
FIELD OF THE INVENTION
This invention relates to toner application systems and toner cartridges for imaging, such as inkjet and electrophotographic imaging.
BACKGROUND OF THE INVENTION
In the practice of conventional electrophotographic imaging, it is the general procedure to form electrostatic latent images on a surface by first uniformly charging a charge retentive surface such as a photoreceptor or charge retentive imaging surface. The charged area is selectively dissipated in accordance with a pattern of activating radiation corresponding to original images. The selective dissipation of the charge leaves a latent charge pattern on the imaging surface corresponding to the areas not exposed by radiation.
This charge pattern is made visible by developing it with toner by passing the photoreceptor past one or more developer housings. In monochromatic imaging, there is usually a single housing with toner comprising black thermoplastic powder particles which adhere to the charge pattern by electrostatic attraction. For color imaging, there are three developer housings each with a toner of a different subtractive color, cyan, magenta, yellow, and optionally black in a forth fourth developer housing. Latent images are developed with each of the developers, forming a color toner image for each color on the imaging surface. The developed image is then transferred to a receiving substrate or print media, such as plain paper, to which it is fixed by suitable fusing techniques.
Ink-jet printing is a non-impact printing process in which droplets of ink are deposited on print media, such as paper, transparency film, or textiles. Essentially, ink-jet printing involves the ejection of fine droplets of ink onto print media in response to electrical signals generated by a microprocessor.
There are two basic means currently available for achieving ink droplet ejection in ink-jet printing: thermally and piezoelectrically. In thermal ink-jet printing, the energy for drop ejection is generated by electrically-heated resistor elements, which heat up rapidly in response to electrical signals from a microprocessor to create a vapor bubble, resulting in the expulsion of ink through nozzles associated with the resistor elements. In piezoelectric ink-jet printing, the ink droplets are ejected due to the vibrations of piezoelectric crystals, again, in response to electrical signals generated by the microprocessor. The ejection of ink droplets in a particular order forms alphanumeric characters, area fills, and other patterns on the print medium.
Recently, there has been a great deal of effort directed to the development of color copiers, and printers, which utilize the electrophotographic and/or ink jet imaging process. Notwithstanding all the recent development in the area of monochromatic and color printers and copiers, there is room for improvement in the quality of images and the convenience in their operating and maintenance. In particular, there is yet a great need in the reproduction of high quality graphic images in systems that are inexpensive and are low-volume, such as conventional printer and copier systems used in business offices and at home. Currently, there is a level of print quality that can be achieved only in expensive, high-volume, commercial printing systems. To achieve or even approach this same quality in a low-volume, inexpensive system would be an advance not yet achieved in the art.
High quality graphics are often required for advertising, and promotional materials. Examples include brochures, programs, posters, and the like, and are often characterized by high-resolution color images with a quality finish, such as a clear high gloss finish. In commercial printing shops, these are usually created by first using an offset, or the like, printing systems to print a high-resolution image on a media, and then applying a clear coat of a varnish, or aqueous material to create a clear shiny gloss finish. This system works well for large printing orders, but is impractical for use for a small volume, because of the setup time and the cost of the equipment. For only a few copies, the investment in equipment and set-up time, makes the per copy cost prohibitive.
Another requirement in obtaining a desired gloss level, has been to choose an appropriate media, and configuring the printing device to apply an appropriate coating, based upon the print media. One way in which a printing device can be so configured to a particular to print media is to have a user make manual adjustments to the printing device based upon these characteristics. One problem with this approach is that it requires user intervention, which is undesirable. Another problem with this approach is that it requires a user to correctly identify and differentiate between glossy-finish and matte-finish print media which some users may be unable to do. A further problem with this approach is that a user may incorrectly manually configure the printing device so that optimal printing still does not occur in spite of user intervention. In environments where user training is low, and there is little ability or desire to stock and administer different print media, the manual approach has been unsuitable.
Printing devices, such as electrophotographic and inkjet printers and copiers, use printing composition (e.g., ink or toner) to print text, graphics, images, etc. onto print media. The print media may be of any of a variety of different types. For example, the print media may include letter quality paper, transparencies, envelopes, photographic print stock, cloth, etc. These print media may be placed in one of two broad categories relating to the finish of the surface of the print medium. These categories are glossy-finish for things such as transparencies and photographic print stock and matte-finish for things such as letter quality paper and envelopes. A glossy-finish is a print media finish that provides a surface brightness or shine when illuminated by a light source. A matte-finish is a print media finish that lacks surface brightness or shine when illuminated by a light source. Glossy-finish and matte-finish print media each have various characteristics that often effect the quality of the image and ideally should be accounted for during printing. Otherwise a less than optimal printed output may occur. For example, in electrophotographic printing, a high-gloss media often induces stray charges and the scattering of toner on the surface. This problem can be largely solved using matt media, but this precludes the user from obtaining high-quality reproductions with a high-gloss surface.
The color copier and printer technologies used in small volume and personal systems can now create high-resolution color images of a resolution approaching that achievable in commercial printing systems. However, although the image is of better quality, these systems, for the most part, are unable to create surface finish that can be obtained from large commercial printing equipment. The equipment for applying the finish, which usually involves coating varnish or aqueous substances on the media, is too large and expensive for office copier and printer applications. In addition, to optimize the finish the equipment requires careful setup of the equipment and the media or substrate must be chosen carefully to achieve optimum results. This is not suitable in many business offices where the user wishes only a few copies and has little or no training in the operation of printing equipment.
The ideal system for such users would be a consumer-level low-volume system that has a higher capability to produce commercial quality printing, which includes high quality color images with a finish of predetermined gloss. The system would be adaptable to small volumes and require little training, such that it can be used in the same way that small printers and copiers are currently used. The additional equipment for applying the gloss should not
Hewlett--Packard Company
Tran Hoan
LandOfFree
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