EP0628415A2
Expired / Lapsed
EP
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High fidelity print modes
Assignee: HP Inc
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Filing: 1994-02-22
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Granted: —
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Expires: 2014-02-22
Abstract
Abstract In an ink jet printing system (10), improved gray scale and color resolution is achieved without modifying the printing grid resolution by reducing the ink droplet volume to a level below the unit droplet volume selected to cover a nominal printing grid location. Multiple passes of the print head are used to print an integer multiple number of the reduced-volume droplets, thereby forming effective dots with greater gray scale resolution. Multiple different droplet volumes are provided in a printing system so as to achieve enhanced resolution without a linear increase in the number of print passes. Another aspect of the invention is to reduce the ink concentration or dye load again to improve gray scale resolution without changing the printing grid. Multiple different dye load concentrations may be provided for further enhancements in resolution again without a linear increase in the number of print passes required. Finally, the invention includes printing with a reduced-volume droplet of a reduced-dye load ink, called a hifi droplet, for still further improvements in print quality, resulting in printed images approximating those produced by continuously variable color densities.
Inventors
- 👤 Douglas L. Franz
- 👤 William J. Allen
- 👤 Joseph M. Torgerson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 13:45
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/21; B41J2/2121; B41J2/2125; B41J2/135; B41J2/14; B41J2002/14475
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
159 words
In a non-continuous drop-on-demand ink jet printing system (10), the printing system having a predetermined printing grid (30) defining an array of pixel locations (32,34) and having a unit ink droplet volume selected for covering approximately one pixel location on a printing medium, a method of printing at a selected pixel location comprising: providing a print cartridge (16) having a nozzle for delivering a droplet of ink, the nozzle being located on a carriage (14) that traverses across the printing medium parallel to its surface; reducing the ink droplet volume so that the nozzle delivers a reduced-volume droplet of ink (48) on demand having a volume less than the unit ink drop volume; and depositing at least one reduced-volume droplet of ink (48) onto the printing medium at the selected pixel location, each reduced-volume droplet being deposited on a different traverse of the carriage, thereby printing the pixel with a gray scale resolution greater than the printing grid resolution.
Claim 2
Dependent Claim
50 words
A method of printing according to claim 1 wherein the reduced droplet volume is approximately 1/Nth of the unit droplet volume, where N is an integer, to allow printing any one of N+1 different volumes of ink at the selected pixel location over at most two passes of the carriage.
Claim 3
Dependent Claim
91 words
A method according to claim 1 wherein: the print cartridge (16) has at least three nozzles (FIG. 2), each nozzle arranged for delivering a respective one of three different color inks (CMY); said reducing the ink droplet volume includes providing a reduced-volume droplet on demand of each color ink; and said depositing step includes, on each pass of the carriage, depositing up to one reduced-volume droplet of each color ink at the selected pixel location (FIG. 4), thereby printing the pixel location with improved color resolution without modifying the printing grid.
Claim 4
Dependent Claim
75 words
A method according to claim 3 further comprising: increasing a black ink resolution for printing black ink at a greater number of dots per unit distance than the color resolution defined by the printing grid (30); reducing the black ink droplet volume in proportion to the increase in black ink printing resolution; and at the pixel location (32,34), printing a combination of the reduced-volume color ink droplets and the reduced-volume black ink droplets (Table 2).
Claim 5
Dependent Claim
119 words
A method according to claim 1 further comprising: providing first and second different ink droplet volumes on demand on the same carriage (FIGS. 3A,3B), each of the first and second volumes being less than the unit volume; depositing up to one first volume droplet onto the selected pixel location on the medium; and depositing up to one second volume droplet onto the same pixel location on the medium, thereby depositing at the pixel location a total volume of ink equal to any one of of no ink, the first volume, the second volume or the first volume plus the second volume, for printing the pixel location with four-level gray scale resolution over at most two passes of the carriage.
Claim 6
Dependent Claim
159 words
In a non-continuous drop-on-demand ink jet printing system (10), the printing system having a predetermined printing grid (30) defining an array of pixel locations (32,34) and having a unit ink droplet volume selected for covering approximately one pixel location on a printing medium, a method of printing at a selected pixel location comprising: defining a selected ink concentration as a standard dye load; selecting the unit volume and the standard dye load at respective levels adequate for forming a dot on the print medium sized to approximately cover the pixel location when a unit volume droplet of the standard dye load ink is deposited on the pixel location; providing a droplet of ink on demand having a reduced dye load less than the standard dye load; and depositing at least one reduced-dye load droplet of ink onto the printing medium at the selected pixel location, thereby printing the pixel with improved gray scale resolution without changing the printing grid.
Claim 7
Dependent Claim
64 words
A method according to claim 6 wherein: the reduced volume is approximately equal to one-fourth of the unit volume; the reduced dye load is approximately equal to one-half of the standard dye load; and said depositing step includes depositing up to a total of eight hifi droplets on the same pixel location over multiple print passes, thereby providing nine gray scale levels per pixel.
Claim 8
Dependent Claim
36 words
A printing method according to claim 6 wherein the printing system has at least three ink colors and said providing step includes providing reduced-dye load droplets on demand of each of the three different color inks.
Claim 9
Dependent Claim
77 words
A method according to claim 8 wherein the reduced-dye load for all three color inks is approximately equal to 1/Nth of the standard dye load, where N is an integer greater than 1, to allow printing any one of N+1 different amounts of dye of each color at the selected pixel location over N print passes, thereby providing (N+1) ^3 (cubed) different possible basic system colors at the selected pixel location without modifying the system printing grid.
Claim 10
Dependent Claim
54 words
A method according to claim 8 further comprising: reducing the volume of each droplet of reduced-dye load ink to a reduced-volume less than the unit volume, thereby forming a hifi droplet; and wherein said providing step includes depositing hifi droplets of each of the three different color inks on demand to the pixel location.
References Cited (Backward Citations)
No citation records indexed.
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