Importance

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Abstract

An ink jet printer of the type having a replaceable printhead assembly with a usage monitoring system detects and displays the remaining available use or lifetime for the printhead assembly installed in the printer. The droplet ejecting electrical pulses applied to selected heating elements of the printhead in the printhead assembly are counted and compared with the number of pulses assigned to a set of permanently inactivable or changeable cell sites integral with the printhead assembly. Each time the number of counted pulses are equal to the value assigned for a cell site, the cell site is addressed to change its state from active to inactive. The remaining active cell sites are representative of the percent of remaining available use for the installed printhead assembly, and this percentage is displayed for the convenience of the customer. Because the cell sites are permanently changed, the supplier can also determine the amount of use of the printhead assembly when warranty claims are submitted. In an alternate embodiment, the cell sites are the unused heating elements of spacing, inactivated nozzles which may be damaged or destroyed by lengthening the pulse duration of a pulse applied thereto when the assigned number of pulses per cell site have been reached.

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First Claim