EXTENDING THE LIFE OF A THERMAL INK JET PRINTHEAD BY HEATER-NOZZLE SHIFTING
Original Publication Date: 1991-Aug-31
Included in the Prior Art Database: 2004-Apr-05
Xerox Disclosure Journal
In a typical ink jet printhead having, for example, 48 nozzles and therefore 48 heater elements, an approximately 1/6 inch high vertical array is provided. This array is scanned horizontally and the appropriate heating elements are enabled to produce a printed swath of information. The printhead is then moved vertically one scan line and the process is repeated until a full page is printed. Because of the head arrangement, typically certain groups of nozzle combinations receive a higher number of operations and thus wear (erosion, impedance change, ink droplet non-uniformity, etc.). To improve head life, a larger than 48 element nozzle array is used and on alternate lines (sets, sheets, pages, or job runs) a different heater set can be used. For example, the accompanying figure shows an expanded array containing 64 such elements. (An array consisting of more or less than 64 would be used similarly.) Using the alternate line technique on this array, elements 1 through 48 could be used for vertical scan 1,2 through 49 for scan line 2, 3 through 50 for scan 3 and so on. The same array because of electronic simplicity, could be staged using elements 1 through 48 for scan 1,5 through 53 scan 2,9 through 57 scan 3 and so on. Using this scheme, it is necessary to selectively index the horizontal drive mechanism appropriately, in order to maintain horizontal magnification and registration. By using a stepper motor of one step/horizontal pixel, the stepper would index 49 steps per line until reaching and using the last element (64) then indexing 47 steps per line until getting back to the starting point. Similar techniques can be used for alternate sets, sheets, pages, or jobs.