Apparatus and method for detecting failure of thermal heaters in ink jet printers.

摘要

According to the present invention, a method and device for detecting failure of heating elements (20) in various jets of a thermal jet printing device is provided. The printing device which includes a plurality of thermally actuated printing jets, each of which jets includes a resistance heating element, is actuated when a current is supplied to generate a bubble. The bubble expands eject a drop of ink. Electrical circuit means are provided including power supply means (30) to supply current to the electrical resistance elements. Control means (33) are also provided to selectively connect the electrical resistance elements to this power supply in preselected arrays for forming bubbles in selected configuration to perform the ink jet printing. The operation includes a test circuit coupled to the resistive heater elements and operable by the control circuit to generate a failure signal representative of a resistance above a preselected value in any resistance heating elements with means (44) to detect the failure signal to identify the resistance heating element which has failed.