Patent ID: 7134742
Filing Date: 2006-11-14
Classification: B41J

Abstract:
1. An ink-jet recording head substrate having a plurality of discharge ports arranged in a predetermined direction, the substrate comprising: a plurality of electrothermal conversion members, each comprising a plurality of exothermic bodies arranged along the line of the plurality of discharge ports for use in ejecting ink from the discharge ports respectively corresponding to the plurality of discharge ports and a pair of electrodes connected to the exothermic bodies; a plurality of drive elements, each connected to one of the pair of electrodes of the electrothermal conversion members for driving each of the exothermic bodies; common wiring A connected to the other of the pair of electrodes of the electrothermal conversion members for passing an electric current to the electrothermal conversion members; common wiring B connected to the electrodes provided in the drive elements for passing an electric current to the drive elements; an ink flow path respectively communicated to the discharge ports respectively corresponding to the exothermic bodies; an ink supply port having a quadrilateral opening, longer sides of the opening arranged along the line of the discharge ports, for supplying the ink to the ink flow path; and an electrode pad connected to the common wiring A and the common wiring B as well as to a power supply source, wherein by the rate (RlineA+RlineB)/(Rh+Rd) obtained from the sum of a wiring resistance value RlineA between the electrode pad and the remotest electrothermal conversion member therefrom via the common wiring A and a wiring resistance value RlineB between the electrode pad and the remotest drive element therefrom via the common wiring B, the sum being divided by the sum of a resistance value Rh of the exothermic body and a resistance value Rd of the drive element, a logic circuit driving the number n (n≧2) of the exothermic bodies at a time is determined in a range of (RlineA+RlineB)/(Rh+Rd)<0.05/(0.95 n−1), where n is the number of the exothermic bodies driven at a time among a plurality of the electrothermal conversion members connected to the common wiring A.