US 8,287,066 B2 · Ink jet printing method

Abstract

This invention pertains to a drop-on-demand ink jet printing method, more particularly to a method of printing wherein a purge image is logically combined with a selected image so as to insure a desired amount of drop firing from every jet of an ink jet printhead for every page printed. The inventive method avoids image defects that could otherwise occur as a result of faulty drop firing from infrequently used nozzles. Purge image data that specifies the deposition of at least one ink dot on at least one predetermined pixel location on each of the plurality of image scanlines is constructed and stored in a purge image memory accessible by the printing apparatus. Imperceptible purge image patterns are constructed having blue noise spatial frequency characteristics and optical density levels equal to or less than 0.01 OD above print medium base OD. A plurality of purge image data sets are constructed and stored for retrieval to adapt to a variety of conditions. Acceptable purge image data sets are determined using a purge performance image as a test pattern which is optically scanned or analyzed by user observation. The present invention further include numerous printing apparatus configured to implement the disclosed methods of maintaining ink jet printheads.

Claims36

Dependent claims

A method for maintaining a plurality of ink jets used in a printing apparatus that forms a selected ink image on a print medium by relatively moving the plurality of ink jets and the print medium in a process direction while ink drops are ejected by the plurality of ink jets, the printing apparatus forming a selected ink image in response to selected image data specifying the deposition of ink dots at selected predetermined pixel locations on a plurality of image scanlines aligned with and extending in the process direction a predetermined image length on the print medium, the method comprising the steps of:

(a) constructing purge image data that specifies the deposition of at least one ink dot on at least one predetermined pixel location on each of the plurality of image scanlines within the predetermined image length;
(b) storing the purge image data in a purge image memory accessible by the printing apparatus;
(c) receiving selected image data specifying a selected ink image;
(d) logically combining the purge image data and the selected image data to create print image data that specifies the deposition of ink dots at every predetermined pixel location based on the purge image data or the selected image data;
(e) printing the print image data on the print medium and
wherein the print medium has an average base optical density, the purge image data specifies a printed purge image of substantially uniformly distributed ink dots along and among the image scanlines, and the printed purge image has an average purge image optical density less than about 0.01 OD above the print medium average base optical density.

3 more elements

A method for maintaining a plurality of ink jets supplied with a plurality of inks of different types, used in a printing apparatus that forms a selected ink image on a print medium by relatively moving the plurality of ink jets and the print medium in a process direction while ink drops of the different types are ejected by the plurality of ink jets, the printing apparatus forming a selected ink image in response to selected image data specifying the deposition of ink dots of the different types at selected predetermined pixel locations on a plurality of image scanlines aligned with and extending in the process direction a predetermined image length on the print medium, the image scanlines further associated with one or more of the plurality of ink types, the method comprising the steps of:

(a) constructing purge image data that specifies for each scanline, the deposition of at least one ink dot of each ink type associated with that scanline on at least one predetermined pixel location within the predetermined image length;
(b) storing the purge image data in a purge image memory accessible by the printing apparatus;
(c) receiving selected image data specifying a selected ink image;
(d) logically combining the purge image data and the selected image data to create print image data that specifies the deposition of ink dots at every predetermined pixel location based on the purge image data or the selected image data;
(e) printing the print image data on the print medium and wherein the print medium has an average base optical density, the purge image data specifies a printed purge image of substantially uniformly distributed ink dots along and among the image scanlines, and the printed purge image has an average purge image optical density less than about 0.01 OD above the print medium average base optical density.

2 more elements

A method for maintaining a plurality of ink jets used in a printing apparatus that forms a selected ink image on a print medium by relatively moving the plurality of ink jets and the print medium in a process direction a predetermined image length in a print time Tp while ink drops are ejected by the plurality of ink jets, the printing apparatus forming a selected ink image in response to selected image data specifying the deposition of ink dots at selected predetermined pixel locations on a plurality of image scanlines aligned with and extending in the process direction a predetermined image length on the print medium, wherein there are a plurality, r, of minimum steady state drop purging frequencies, fpr, that are required to maintain a desired ink drop volume and velocity ejected from the plurality of ink jets based on a plurality, r, of conditions, the method comprising the steps of:

(a) constructing a plurality, r, of purge image data sets, Ipr, so that ink dots are specified for at least Npr predetermined pixel locations on each of the plurality of image scanlines within the predetermined image length, wherein Npr≧fprTp;
(b) constructing a purge performance image data set that comprises portions of the plurality of purge image data sets, Ipr, and test image patterns sensitive to variations in ink drop ejection volume, velocity, or both;
(c) storing the plurality of purge image data sets, Ipr, and the purge performance image data set in a purge image memory accessible by the printing apparatus;
(d) printing the purge performance image data set to form a purge performance test image;
(e) determining from, at least, the purge performance test image a purge image data set, Ips, of the plurality of purge image data sets, Ipr, that maintains the desired ink drop volume and velocity;
(f) retrieving the purge image data set, Ips;
(g) receiving selected image data specifying a selected ink image;
(h) logically combining the purge image data set, Ips, and the selected image data to create print image data that specifies the deposition of ink dots at every predetermined pixel location based on the purge image data set, Ips, or the selected image data;
(i) printing the print image data on the print medium.

6 more elements

Dependencies are inferred from the claim text.

Ink jet printing method

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Ink jet printing method

Life of this patent

Abstract

Claims36