Ink jet printing method

摘要

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.