Patent ID: 6106088
Filing Date: 2000-08-22
Classification: B41J

Abstract:
A method of recording the amount of use which has taken place for a given replaceable printhead for a printer in terms of portions of the printhead lifetime for feedback to either a customer or a supplier, the replaceable printhead having a plurality of active nozzles and each active nozzle having a heating element, the heating elements of the active nozzles being selectively energizable by a printer controller to eject an ink droplet from the printhead nozzles, the method comprising the steps of:(a) establishing a printhead lifetime in terms of a total number of units of printing output achievable by said printhead, each unit of printing output representing an energization of the heating elements of the active nozzles;(b) dividing the total number of printing output units into a plurality of groups of printing output units, each group of printing output units representing a portion of the printhead lifetime;(c) storing the number of printing output units representing one of the groups of printing output units in a memory of the printer;(d) providing a plurality of non-droplet ejecting, inactive nozzles in said replaceable printhead, each inactive nozzle having a heating element associated therewith which functions as a permanently switchable device on said printhead for each group of printing output units, the heating elements of the inactive nozzles being adapted to move from a conductive state to a permanently non-conductive state when selectively energized by said printer controller;(e) counting the number of units of printing output accomplished by the printhead for each printing operation conducted by said printer;(f) storing the number of counted units of printing output in the memory of the printer;(g) comparing the number of counted units of printing output with the number of printing output units in said group stored in the printer memory;(h) selectively energizing one of the heating elements associated with an inactive nozzle each time the counted printing output units equal the number of printing output units in the one group thereof which is stored in the printer memory to cause the heating element associated with an inactive nozzle to move permanently from a conductive state to a non-conductive state; and(i) preventing further printing by the printer when all of the heating elements associated with the inactive nozzles on said printhead have been have been changed to the non-conductive state, indicating that the printhead lifetime has expired, thereby requiring that the printhead be replaced.