Protective circuit for inkjet printhead

摘要

An inkjet printhead includes an array of resistive heaters; an array of nozzles associated with the array of resistive heaters; a heater voltage input for providing a heater voltage; a fire control pulse input for providing a fire control pulse having a first pulsewidth for controlling a length of time that current from the heater voltage input is allowed to pass through at least one of the resistive heaters; and a protective circuit configured to receive the fire control pulse from the fire control pulse input, and to override the fire control pulse if the first pulsewidth is greater than or equal to a predetermined length of time.

主权项

1. An inkjet printhead comprising:
an array of resistive heaters; an array of nozzles associated with the array of resistive heaters; a heater voltage input for providing a heater voltage; a fire control pulse input for providing a fire control pulse having a first pulsewidth for controlling a length of time that current from the heater voltage input is allowed to pass through at least one of the resistive heaters; and a protective circuit configured to receive the fire control pulse from the fire control pulse input, and to override the fire control pulse if the first pulsewidth is greater than or equal to a predetermined length of time; wherein the protective circuit includes a timer circuit having an output that is connected to a triggerable circuit element that emits a pulse having a width that is substantially equal a difference between the first pulsewidth and the predetermined length of time if the first pulsewidth is greater than or equal to the predetermined length of time, and wherein the triggerable circuit element is connected to a first input of a latch.