Incremental printing of symbolic information – Ink jet – Controller
Patent
1994-10-31
1997-10-28
Reinhart, Mark J.
Incremental printing of symbolic information
Ink jet
Controller
347 19, 347 60, B41J 2195, B41J 29373
Patent
active
056821832
ABSTRACT:
Disclosed is a method of determining imminent ink exhaustion in a thermal inkjet print cartridge based on the discovery that ink drop volume falls at a faster rate at high frequency firing rates than at low frequency firing rates as ink supply diminishes. The method includes warming the print cartridge printhead and ink to a predetermined temperature; then operating the print cartridge printhead at a first firing frequency to eject a volume of ink, said operating step including heating the ink and printhead, carrying away heat in the ejected volume of ink, and conveying a volume of cooler ink to the printhead to replace the ejected volume; and monitoring a first temperature change from the predetermined temperature. Then warming the same print cartridge printhead and ink to a predetermined temperature; operating the print cartridge printhead at a second firing frequency which is different than the first firing frequency to eject a volume of ink, said operating step including heating the ink and printhead, carrying away heat in the ejected volume of ink, and conveying a volume of cooler ink to the printhead to replace the ejected volume; and monitoring a second temperature change from the predetermined temperature. The first and second temperature changes are compared to indicate a low ink supply. The method is quickly and readily performed by a printer before printing or between printing intervals. The indication of low ink supply can be used to develop printer shutdown, or use of a reserve print cartridge, or an operator warning, or a combination of these tactics.
REFERENCES:
patent: 5206668 (1993-04-01), Lo et al.
patent: 5418558 (1995-05-01), Hock et al.
patent: 5428376 (1995-06-01), Wade et al.
Huntingdon Betsy C.
Shultz Christopher J.
Wade John M.
Hallacher Craig A.
Hewlett--Packard Company
Reinhart Mark J.
Stenstrom Dennis G.
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