Patent ID: 6843545

Claim:
In a printer having a printhead having a plurality of print nozzles, which use a sonic pulse to discharge drops of ink from said nozzles to form an image during the print cycle, an ink cartridge to supply ink to said nozzles, a method of printing comprising the steps of: determining the initial volume of ink remaining in the ink cartridge prior to printing; recording said initial volume in a memory unit; determining the volume of ink required to print the next page; printing the next page if there is sufficient ink in the cartridge to print the page; counting the number of dots of ink discharged in the printing of the page; obtaining data on the size of a dot under present conditions; feeding the data on the size of a dot and the number of dots printed to a processor where the number of dots is multiplied by the volume of each dot to determine the volume of ink used in the printing of the page; feeding data on the volume of ink printed to the memory unit where the volume of ink, printed, is subtracted from the volume of ink in the cartridge prior to printing that page to obtain the volume of ink in the cartridge after printing that page, and repeating the above steps for each page printed.