Incremental printing of symbolic information – Ink jet – Housing
Reexamination Certificate
2000-05-10
2001-07-10
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Housing
C347S085000
Reexamination Certificate
active
06257717
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to ink-jet technology and, more particularly, to methods and apparatus for producing hard copy with modular ink-jet hard copy devices and systems.
2. Description of Related Art
The art of ink-jet technology is relatively well developed. Commercial products such as computer printers, graphics plotters, copiers, and facsimile machines employ ink-jet technology for producing hard copy. The basics of this technology are disclosed, for example, in various articles in the Hewlett-Packard Journal, Vol. 36, No. 5 (May 1985), Vol. 39, No. 4 (August 1988), Vol. 39, No. 5 (October 1988), Vol. 43, No. 4 (August 1992), Vol. 43, No. 6 (December 1992) and Vol. 45, No. 1 (February 1994) editions. Ink-jet devices are also described by W. J. Lloyd and H. T. Taub in Output Hardcopy [sic] Devices, chapter 13 (Ed. R. C. Durbeck and S. Sherr, Academic Press, San Diego, 1988).
Fundamentally,
FIG. 1
(PRIOR ART) depicts an ink-jet hard copy apparatus, in this exemplary embodiment a computer peripheral printer,
101
. A housing
103
encloses the electrical and mechanical operating mechanisms of the printer
101
. Generally, operation is directed by an electronic controller (usually a microprocessor or application specific integrated circuit (“ASIC”) controlled printed circuit board, not shown) connected by appropriate cabling to a computer (not shown). It is well known to program and execute imaging, printing, print media handling, control functions and data processing logic with firmware or software instructions. Cut-sheet print media
105
, loaded by the end-user onto an input tray
107
, is fed by a suitable internal paper-path transport mechanism (not shown) to a printing station where graphical or photographical images and alphanumeric text is created. A carriage
109
, mounted on a slider rod
111
, scans the print medium. An encoder strip
113
is provided for keeping track of the position of the carriage
109
at any given time. A set
115
of individual ink-jet pens, or print cartridges,
117
A-
117
D is releasably mounted into the carriage
109
for easy access (generally, in a full color system, inks for the subtractive primary colors, cyan, yellow, magenta (CMY) and true black (K) are provided). Once a printed page is completed, the print medium is ejected by the transport mechanism onto an output tray
119
.
At the heart of an ink-jet hard copy apparatus is the writing instrument itself, commonly called a “print cartridge” or a “pen.” As shown in
FIG. 2
(the subject of separate patent applications assigned to the assignee of the present invention), an exemplary ink-jet pen
210
includes a body, or shell,
212
that encases an ink reservoir, or an ink accumulator chamber and related print head pressure regulator mechanisms (not shown), containing either fluid ink or hot melt type printing fluid. A print head
214
includes a nozzle plate
216
having a plurality of small (e.g., diameter approximately twenty &mgr;m) orifices
217
from which tiny droplets of ink (e.g., approximately ten picoliters) are ejected onto adjacent print media as the pen(s) scan across a printing zone at a high speed (approximately 25 inches per second, “ips”), depositing ink droplets in patterns that through dot matrix manipulation form alphanumeric text characters or graphic images. A flex circuit
218
includes electrical contacts
220
for connecting the pen
210
to the electronic controller. The print head elements have a limited life due to electrical, thermodynamic, and fluid dynamic loads imposed during operation. Thus, in the current state of the art, a costly and functionally significant portion of the writing system must be replaced with each print cartridge change.
The apparatus elements directly involved with inking a print media—in other words, all components of the system which come into contact with ink other than the print media itself—are referred to hereinafter as a writing engine; non-writing elements of the hard copy apparatus system are referred to hereinafter as a hard copy engine. Cartridges, pens, ink-reservoirs, and the like are referred to as ink-jet consumables. (Use of these terms is for convenience of description and is not intended as any limitation to the scope of the invention, nor should any such intention or limitation be implied therefrom.)
Having become commercially practicable in the early 1980's, ink-jet technology is a relatively young field of invention. In state-of-the-art thermal ink-jet systems, two complementary writing instruments have become commercially viable. The first is the disposable print cartridge type; the second is the semipermanent print head pen type.
The disposable writing instrument has a self-contained reservoir (“on-axis” or “on-board;” generally meaning on the pen carriage subsystem) for storing ink and providing appropriate amounts of ink to the print head during a printing or servicing cycle throughout the life of the writing instrument. When out of ink, the entire print cartridge is replaced by the end-user.
When ink-jet technology was in its early stages, print head life expectancy was more or less equivalent to the amount of ink that was held in the on-board ink reservoir. More recently, advances in the state-of-the-art for print head design and manufacture has led to a longer operational life expectancy for the print head than can be used with a reasonably-sized, non-replaceable ink reservoir. Thus, the development and commercialization of a second commercial type using a replaceable ink writing subsystem that employs a semi-permanent printing element, where the ink is supplied to the print head mechanism from a replaceable ink reservoir located either on-axis or “off-axis,” (with respect to the pen carriage subsystem), such as a biased ink bladder or bag (see e.g., U.S. Pat. No. 5,359,353 (Hunt et al.) assigned to the common assignee of the present invention and incorporated herein by reference). This second type of writing instrument, the semipermanent pen, can also include mechanisms for regulating both requisite print head back pressure (in a free-ink ink-jet writing instrument) and the flow of ink from the off-board ink reservoir to the pen (shown in
FIG. 2
as having an ink inlet mechanism
222
that would be coupled
223
to the replaceable or refillable off-axis ink supplies
224
). In the off-axis type of hard copy apparatus, separate, replaceable or refillable, ink reservoirs are located within the fixed apparatus housing
103
,
FIG. 1
, and appropriately coupled to the moving pen set
115
via ink conduits, such as tubes that are impervious to the ink chemicals. In the on-axis type of hard copy apparatus, separate, replaceable or refillable, ink reservoirs couple to the print head ink interface directly and are located on the moving pen carriage system.
Each commercial configuration has advantages and disadvantages. The disposable print cartridge type writing instrument is simple and easy to use but costly, as the relatively expensive print head mechanism is discarded along with the on-axis ink chamber once the ink is fully consumed. Moreover, the non-replaceable on-axis ink chamber in and of itself inherently limits the number of pages which can be printed due to its relatively small ink capacity. With the increase in print head longevity, end users have turned to refill kits or lower cost re-manufactured print cartridges that are less expensive than replacement with a new print cartridge. The use of ink refill kits is often a messy task. Still further, the need and desire for even less expensive ink continues to grow. The recent commercialization of near photographic quality ink-jet printing has increased the end user's consumption of ink much faster than in the past when simple text and color graphics imagery was the norm. Even traditional business documents are now including more images and complex graphics, thus consuming more ink. Naturally, end user replacement costs increase.
The semipermanent pen type syst
Axtell James P
Benjamin Trudy L
Kent Blair M.
Lowe David J
Seu Preston D.
Hewlett--Packard Company
Le N.
Vo Anh T. N.
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