Patent ID: 7604312

Claim:
A fluid ejection assembly comprising: a plurality of drop ejecting elements arranged in a plurality of zones, with each zone having at least one drop ejecting element, wherein the drop ejecting elements of each zone are configured to conduct electrical current between a corresponding supply voltage and a corresponding reference voltage, and wherein up to all drop ejecting elements of a group of the plurality of drop ejecting elements are enabled to conduct at a given time, with each conducting drop ejecting element of the enabled group having a corresponding drop ejecting voltage; a zone controller configured to provide a corresponding desired supply voltage for each zone based on a temperature level of the drop ejecting elements of the corresponding zone; and an energy controller configured to couple across each conducting drop ejecting element of the enabled group and configured to regulate the supply voltage for each zone based on selected corresponding drop ejecting voltages and on each zone's corresponding desired supply voltage, wherein the enabled group is successively shifted through each zone according to a selected enabling pattern in response to a start signal and a clock, wherein each of the drop ejecting elements of the plurality of drop ejecting elements is coupled between a shared supply path at the supply voltage and a shared return path at the reference voltage, and wherein each drop ejecting element is individually selectable to conduct electrical current from the shared supply path to the shared return path to cause the drop ejecting element to eject a fluid droplet, wherein the zone controller comprises: a zone computer configured to calculate a setpoint supply voltage for each zone based on the temperature level of the drop ejecting elements of the corresponding zone and an enable signal representative of a number of drop ejecting elements in the enabled group; a plurality of memories each corresponding to and storing the calculated setpoint supply voltage for a corresponding one of the zones; and a digital-to-analog converter configured to convert a setpoint supply voltage from a selected one of the memories to the corresponding desired supply voltage, wherein the zone computer selects the selected one of the memories based on the start signal, the clock, and the selected enabling pattern.