Recorders – Record receivers and/or driving means therefor – Web
Reexamination Certificate
1999-08-09
2002-07-02
Barlow, John (Department: 2853)
Recorders
Record receivers and/or driving means therefor
Web
Reexamination Certificate
active
06414701
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to hard copy printing and more specifically to a methods and devices for containing and feeding printing media in a drum type hard copy apparatus.
2. Description of Related Art
The art of hard copy printing technology is well developed in commercial products such as computer printers, graphics plotters, copiers, and facsimile machines. One specific type of hard copy printing employs ink-jet technology for producing the 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). In order to explain the present invention, a ink-jet hard copy apparatus will be used as an exemplary embodiment. As the present invention may be extended to other forms of printing, no limitation on the scope of the invention is intended by the use of this exemplary embodiment nor should any such intention be implied.
FIG. 1
(PRIOR ART) depicts an ink-jet hard copy apparatus (with its cover shell removed, in this exemplary embodiment a computer peripheral printer,
101
. A housing
103
encloses the electrical and mechanical operating mechanisms of the printer
101
. Operation is administrated by an electronic controller
102
, usually a microprocessor or application specific integrated circuit (“ASIC”) controlled printed circuit board 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 logic with firmware or software instructions for conventional or general purpose microprocessors or with ASIC's. Cut-sheet print media
105
, loaded by the end-user onto an input tray
120
, is fed by a suitable paper-path transport mechanism (not shown) to an internal printing station, or printing zone,
107
where graphical images or alphanumeric text is created. A carriage
109
, mounted on a slider
111
, scans the print medium. An encoder
113
is provided for keeping track of the position of the carriage
109
at any given time. At least one, or a set, of individual ink-jet pens, or print cartridges,
115
x
are releasable mounted in the carriage
109
for easy access. Generally, in a full color system, inks for the subtractive primary colors—cyan, yellow, magenta (CYM)—and true black (K) (F standing for a fixer fluid) are provided in remote, or “off-axis,” replaceable or refillable, ink reservoirs
117
x
having fluidic couplings
119
to the pens
115
x
. Once a printed page is completed, the print medium is ejected onto an output tray
121
. It is common in the art to refer to the pen scanning direction as the x-axis, the paper feed direction as the y-axis, and the ink drop firing direction as the z-axis.
Hard copy apparatus, be it in the form of a printer, plotter, copier, scanner, facsimile machine, or the like, share the need for having a blank printing media supply, preferably in an automated-feeder device appurtenant to the hard copy apparatus. In turn, printing media come in a variety of forms. A common computer printer
101
, such as a Hewlett-Packard™ DeskJet™ ink-jet printer as depicted in
FIG. 1
, is usually designed to be compatible with a variety of media, such as plain paper, special paper, transparencies, and envelopes, up to and including legal size (8.5×14-inches) media as are commonly used in an office or home environment. On the other hand, a common large format plotter
201
, such as an ink-jet plotter like the Hewlett-Packard DesignJet™ series illustrated by
FIG. 2
(Prior Art), requires accommodation for large sheets, or continuous, media
203
, currently up to eighty inches in the scanning x-axis width dimension. As the computing arts expand into new fields, such as palm top computers or specialized computer printing needs, such as dedicated photograph ink printing as in the Hewlett-Packard PhotoSmart™ digital camera
300
direct printer
303
series depicted by
FIG. 3
(Prior Art), other sizes of printing media (e.g., 3.5×5 for photographs) and other forms of recording media, such as cloth (e.g., for ink printing on T-shirts) and advanced automated-feeder devices are needed.
Herein, the terms “recording” and “printing” are used synonymously, intended to include the action of applying any type of colorant (e.g., ink, toner, and the like) to any kind of printing medium (e.g., paper, cloth, plastic, flexible materials, and the like)—referred to hereinafter generically as “paper”—and any kind of hard copy producing apparatus—referred to hereinafter generically as a “printer.”
One specific type of hard copy apparatus is generically referred to as a “drum printer.” A schematic depiction of a drum printer
401
is shown in
FIG. 4
(Prior Art). The operational functions of the printer are administered by an electronic controller
402
, as would be known in the art, coupled to an input/output device
400
, such as a computing apparatus. A drum printer
401
wraps a sheet of paper
403
from a provided supply
405
around a rotating cylinder
407
which then acts as a paper platen. A writing instrument
409
is located parallel to the drum surface or has a carriage (not shown), carrying one or more writing instruments as demonstrated by
FIGS. 1 and 2
, that travels along an axis parallel to the cylinder's rotational axis. In a scanning carriage type drum printer, both carriage and drum velocities are held constant during printing to keep power consumption low and reduce dynamic operational problems, such as accounting for carriage reversal acceleration and deceleration ramp distances and durations during a print cycle. In general, drum printers have a higher throughput (“pages per minute” or “ppm”) than flat bed scanning carriage printers such as shown in
FIGS. 1 and 2
.
Drum printers have design variations such as having a less than “page wide”, “W,” writing instrument stationary while the medium
403
rotates with the cylinder
407
, moving the writing instrument only between printing each successive swath. Having the writing instrument stationary provides inherent print quality enhancing capabilities. The medium
403
does not cover the entire circumference of the drum; that is a gap, “G,” separates the medium's leading edge
411
and trailing edge
413
. The writing instrument is shifted quickly to start printing a next swath while this gap on the drum is passing. In another design variation, helical scanning by a writing instrument can be provided by slowing scanning the writing instrument carriage while the drum rotates or by translating the drum relative to a stationary writing instrument.
A main problem with drum printers is the loading and holding of the medium to the cylinder surface. Print quality may be degraded by variations of the medium registration to the drum surface. Manual taping or clamping is cumbersome and time consuming. Automated pick-and-feed mechanisms associated with an input tray combined with mechanical or electromechanical edge clamping devices improve the loading cycle time and eliminate the need for user intervention. Such mechanisms add significant complexity and cost to manufacture. Automated pick-and-feed mechanisms associated with an input tray combined with vacuum holddown cylinder drum printers are also known. Such vacuum systems also add significant complexity and cost to manufacture. Moreover, localized suction forces from the pattern of vacuum through-holes in the cylinder surface are generally transmitted through the printing medium and thus also can effect the print quality. Both automated clamping and vacuum systems compromise the desire for a small workplace footprint. Mechanica
Lo Clement C.
Lowe David J.
Seu Preston Dow
Barlow John
Do An H.
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