Linear substrate heater for ink jet print head chip

Abstract

An ink jet print head includes a nozzle plate having a substantially linear array of ink jet nozzles through which ink droplets are ejected toward a print medium. An integrated circuit chip, which is disposed adjacent the nozzle plate on the print head, includes a semiconductor substrate, a source voltage conductor connected to a source voltage, and a ground return conductor. A substantially linear array of ink heating resistors are disposed on the substrate substantially parallel to the length of the chip, each associated with a corresponding one of the ink jet nozzles. The chip also includes a plurality of substrate heater resistors disposed on the substrate in a substantially linear arrangement and aligned substantially parallel with the nozzles. The substrate heater resistors are electrically connected in parallel, with one node of each being connected to the source voltage conductor and another node of each being connected to the ground return conductor. Preferably, the substrate heater resistors include first substrate heater resistors disposed near a lengthwise center of the chip and second substrate heater resistors that are distally disposed relative to the lengthwise center of the chip. The first and second substrate heater resistors have different first and second electrical resistance values, respectively, that are determined by thermal dissipation patterns of the chip. The difference between the first and second electrical resistance values cause the first and second substrate heater resistors to generate different amounts of heat when supplied with the source voltage. The different amounts of heat generated by the first and second substrate heater resistors and the relative positions of the first and second substrate heater resistors compensate for differing thermal dissipation patterns across the chip.