Method and system for detecting nonfunctional elements in an ink jet printer

An ink jet printer system for detecting a nonfunctional element in an ink jet printhead, comprising:

• means for supplying regulated power to the printhead;
• capacitor means, coupled to the means for supplying regulated power, for storing a dc voltage therein;
• means for discharging current from the capacitor means;
• means for shifting the dc voltage level stored in the capacitor means between a low state and a high state;
• means for measuring a test current discharging from the capacitor means when an element of the printhead is activated;
• and
• means for comparing the measured test current with a reference current which discharges from the capacitor means through only the means for discharging when no element of the printhead is activated.

A method of detecting a nonfunctional element in a printhead of an ink jet printer, comprising the acts of:

• supplying regulated power to the printhead;
• storing the regulated power in a capacitor so as to provide a dc voltage across the capacitor;
• shifting the dc voltage level stored in the capacitor from a low state to a high state;
• allowing the capacitor to discharge such that the dc voltage across the capacitor decreases from the high state to the low state;
• measuring a reference current discharging from the capacitor through a bleed resistor, when no elements of the printhead are activated;
• measuring a test current discharging from the capacitor when an element of the printhead is activated;
• and
• comparing the measured test current with the reference current.

An ink jet printer system for detecting a nonfunctional element in an ink jet printhead, without the necessity of adding a separate resistive element in series with the nonfunctional element, said ink jet printer system comprising:

• first means for supplying regulated power to said printhead;
• second means for storing a predetermined magnitude of charge from said regulated power supply so as to provide a dc voltage;
• third means coupled to said second means for discharging at least a portion of said stored charge into a circuit having a fixed reference resistance;
• and
• fourth means coupled to said second means for comparing the actual duration of a test discharge period, which corresponds to the time required to discharge at least a portion of said stored charge into said element of said printhead, with a reference discharge period which corresponds to the time required to discharge at least a portion of said stored charge into said circuit having a fixed reference resistance.