Thermal ink jet printhead with increased drop generation rate

Abstract

An improved ink jet printhead comprising upper and lower substrates that are mated and bonded together with a thick film insulative layer sandwiched therebetween. One surface of the upper substrate has etched therein one or more grooves and a recess which when mated with the lower substrate will serve as capillary filled ink channels and ink supply manifold, respectively. The grooves are open at one end and closed at the other. The open ends serve as nozzles. The manifold recess is adjacent the grooved closed ends. Each channel has a heating element located upstream of the nozzle. The heating elements are selectively addressable by input signals representing digitized data signals to produce ink vapor bubbles. The growth and collapse of the bubbles expel ink droplets from the nozzles and propel them to a recording medium. A recess patterned in the thick layer provides a flow path for the ink from the manifold to the channels by enabling the ink to flow around the closed ends of the channels and increase the flow area to the heating elements. Thus, the heating elements lie at the distal end of the recesses so that a vertical wall of elongated recess prevents air ingestion while it increases the ink channel flow area and increases refill time, resulting in an increase in bubble generation rate.