Patent ID: 9266339
Filing Date: 2016-02-23
CPC Classification: B41J

Claim Text:
1. A printing element substrate in which an ejection opening for ejecting a liquid is provided, wherein the printing element substrate is provided with a liquid supply passage that is formed along a direction from a surface of the substrate at the opposite to a surface thereof where the ejection opening is provided to the surface where the ejection opening is provided, the liquid supply passage being shaped such that an area of a cross section along a direction perpendicular to the direction to the surface where the ejection opening is provided increases and after that, decreases, in the direction to the surface where the ejection opening is provided, and the liquid supply passage has an opening end of a rectangular shape on the surface of the substrate at the opposite to the surface on the side where the ejection opening is provided, and a recessed portion, which has a certain depth in a direction toward the surface on the side where the ejection opening is provided, is formed on a shorter side in the rectangular shape, wherein a plurality of the recessed portions are provided on the shorter side in the rectangular shape.