Patent ID: 8128206

Claim:
A liquid ejection head substrate comprising: an element row including a plurality of elements that are provided in a row, where each of the elements generates energy used to eject a liquid; a plurality of drive circuits that is provided in correspondence with the plurality of elements, and that drives and controls the plurality of elements; a logic signal output unit configured to externally transmit a signal used to drive the plurality of elements; a signal line that connects the logic signal output unit to the plurality of drive circuits and that is provided along a direction in which the element row is provided; a substrate having a face provided with the element row, the plurality of drive circuits, the logic signal output unit, and the signal line; and a heating portion configured to generate heat used to heat the substrate, wherein the heating portion is provided so as not to overlap the signal line with reference to a direction perpendicular to the face, and provided on an area defined between the signal line and the element row so that the area and a part of the heating portion overlap each other.