Integrated circuit printhead for an ink jet printer including an integrated identification circuit

An integrated circuit for use in thermal ink jet printheads for providing identifiable characteristics of individual print cartridges containing such a printhead to a printhead controller, comprising:

• an array circuit for heating an ink reservoir to produce a pattern of ink jets, the array circuit including a plurality of actively controlled resistor cells arranged in a predetermined number of rows and columns;
• a plurality of row and column lines coupled to the array circuit for selectively driving at least one of the resistor cells;
• an identification circuit including a plurality of programmable paths, a first end of each programmable path being coupled to a respective row line, a second end of each programmable path being coupled together to form a common node;
• and
• an output means having an input coupled to the common node and an output for providing an output signal in response to a polling of the row lines, the output signal being multiplexed onto an existing interconnect pad of the printhead.

A method for identifying characteristics of an integrated circuit thermal ink jet printhead, having an array circuit for heating an ink reservoir to produce a pattern of ink jets, the array circuit including a plurality of resistor cells arranged in a predetermined number of rows and columns and a plurality of row and column lines coupled to the array circuit for selectively driving at least one of the resistor cells, the method comprising the steps of:

• providing at least one programmable path coupled to each row line;
• and
• programming the programmable paths according to a predetermined pattern indicative of the characteristics of the printhead by:
• (a) forming a short-circuit path in response to a first logic state for passing a signal current;
• and
• (b) forming an open-circuit path in response to a second logic state for blocking the flow of a signal current.