Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1998-06-19
2001-03-27
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06206511
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an ink supply system for a color ink jet printer of the type having off-board ink supplies for supplying inks to printhead cartridge reservoirs. Operator intervention to replenish off-board ink supplies is reduced by dividing the ink supply for each color into N separately replaceable cartridges, where N>1. When all off-board cartridges holding one color ink are empty, an operator intervenes to replace all off-board cartridges which held ink of the one color, and any empty cartridges which held inks of the other colors. After an intervention to replenish the exhausted supply of one color ink, the supply of ink of each color is at least (N−1)/N of its maximum capacity if the empty cartridges of other colors are also replaced during the intervention.
BACKGROUND OF THE INVENTION
Network ink jet printers use high carriage velocities and high acceleration rates to achieve printing at rates of over 10 pages per minute. To minimize the mass that must be accelerated, ink reservoirs are usually located off-board the carriage and various systems are implemented to transfer ink from the reservoirs to the printhead cartridges.
U.S. Pat. No. 5,369,429 employs a continuous ink supply system wherein flexible hoses or tubes connect a plurality of printhead cartridges to respective ones of a plurality of off-board ink reservoirs so that ink is supplied continuously to the cartridges as needed. U.S. Pat. Nos. 3,967,286, 4,967,207, 4,968,998 and 5,136,305 disclose intermittent ink supply systems wherein an ink jet cartridge is intermittently filled from an off-board reservoir by moving the cartridge to a service station where the reservoir is located.
The intermittent and continuous ink supply systems of the prior art share a common disadvantage when employed in color network printers. Because (1) ink is consumed relatively rapidly due to the high printing rates, (2) there are four or possibly six colors of ink being used, and (3) the ink supply for each color is an undivided ink supply, an operator must intervene in the printing process relatively frequently to replenish the off-board ink supplies, thus reducing the time the printer is available for printing. For example, in a printer capable of printing in four colors, and having an undivided off-board supply for each color holding enough ink for printing 20,000 prints or pages (5% coverage), an operator has to intervene in the printing process, on average, about every 5000 prints because the different colors of ink are not used up at the same time. In the worst case, a second intervention may be required only one page after a first intervention. This assumes that only the empty ink supply is replaced during an intervention. Of course all the reservoirs could be replaced during a given intervention but this would be wasteful of ink and increase the printing costs.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink supply system for a color ink jet printer having off-board ink reservoirs, the supply system, as compared to prior art systems, requiring fewer operator interventions to replenish or replace the ink reservoirs.
Another object of the invention is to provide a color ink jet printer having an off-board ink reservoir for holding ink of each color, each reservoir comprising at least two separately replaceable cartridges.
A further object of the invention is to provide a color ink jet printing device having a printhead including printhead cartridge means mounted on-board a movable printhead carrier for ejecting a plurality of inks of different colors from ink reservoirs in the cartridge means, a like plurality of ink reservoirs located off-board the printhead carrier for refilling respective ones of the cartridge reservoirs with ink, the reservoirs off-board the carrier each comprising N separately replaceable off-board cartridges holding ink of the same color, N being an integer greater than one. The printhead cartridge means may comprise a plurality of disposable printhead cartridges, each holding ink of a different one of said colors, or a single cartridge having plural reservoirs.
Another object of the invention is to provide a color ink jet printing device having a printhead comprising a plurality of on-board cartridges mounted on-board a movable printhead carrier, each cartridge having therein an ink reservoir from which ink is ejected during printing, each reservoir holding ink of a different color, and an ink supply system for refilling the reservoirs in the on-board cartridges, the ink supply system comprising, for each of the on-board cartridges: an off-board ink reservoir comprising at least a first and a second off-board cartridge for holding ink of the same color, each off-board cartridge having an associated indicator for indicating to an operator when it is empty; a valve having first and second inputs connected to the first and second off-board cartridges and an output connected to a dispensing line through which ink flows to the ink reservoir of the on-board cartridge; first means for determining when the reservoir in the on-board cartridge is full and when the reservoir therein requires refilling; second means for determining when an off-board cartridge is empty; and, control means, responsive to the first means when the reservoir in the on-board cartridge requires refilling, for switching the valve so that ink may flow from the first off-board cartridge to the dispensing line, the control means being responsive to the second means for setting the indicator associated with the first off-board cartridge and switching the valve so that ink may flow from the second off-board cartridge to the dispensing line if the second means determines that the first off-board cartridge is empty. The control means comprises means for determining if all off-board cartridges holding ink of one color are empty and, if so, stopping the printing so that an operator may intervene and replace not only all the off-board cartridges which held the one color ink but also any empty cartridges which held inks of other colors.
Assuming N off-board cartridges for each color ink, each off-board reservoir will, after each intervention, hold at least (N−1)/N of its maximum capacity. If N=2, for example, and the volume of ink sufficient to print 20,000 prints is divided equally between the cartridges, operator intervention to replenish the ink reservoirs will be required no more often than every 10,000 prints, or approximately one-half as often as the average interval in the prior art, when printing takes place in four colors.
Still another object of the invention is to provide a method of supplying ink to an ink jet printhead having on-board reservoirs therein for holding inks of different colors, the method comprising: (1) providing an off-board ink reservoir for each color ink, each reservoir comprising a plurality of off-board cartridges; (2) for each color ink, supplying ink to the on-board reservoir from a first off-board cartridge until the first off-board cartridge is empty, then supplying ink to the on-board reservoir from a second off-board cartridge until the second off-board cartridge is empty, and so on until all off-board cartridges holding ink of the same color are empty, and, (3) when all off-board cartridges holding ink of one color are empty, replacing all empty off-board cartridges regardless of the color ink they held.
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Cook William Paul
Denton Gary Allen
Griffin B. Franklin
Le N.
Lexmark International Inc.
Nguyen Judy
Sanderson Michael T.
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