Patent ID: 7354139
Filing Date: 2008-04-08
Classification: B41J

Abstract:
1. An inkjet printhead substrate, comprising a plurality of heaters arranged along a longer side direction of a rectangular board near one longer side, a plurality of switching elements respectively corresponding to the plurality of heaters, and a control circuit for controlling drive of the plurality of switching elements, wherein an electric current flows into the plurality of heaters by switching the plurality of switching elements in accordance with a control signal from the control circuit, said substrate further comprising: a constant electric current source, comprised of a MOS transistor, for supplying a constant electric current to the plurality of heaters; and a plurality of terminals which receive a control signal used to drive the plurality of heaters and are arrayed near another longer side opposite to arrangement positions of the plurality of heaters, wherein the plurality of switching elements, the control circuit, and the constant electric current source are arranged in order in a direction from the arrangement positions of the plurality of heaters to arrangement positions of the plurality of terminals.