A thermal ink jet printer including a printhead having a plurality of ink drop firing resistors responsive to ink drop firing pulse groups wherein a pulse group includes one or more pulses sufficiently closely spaced to produce respective droplets which merge in flight to form an ink drop whose volume...http://www.google.com/patents/US5600349?utm_source=gb-gplus-sharePatent US5600349 - Method of reducing drive energy in a high speed thermal ink jet printer
