Liquid ejection head and printing apparatus

A printing apparatus comprising:

• a liquid ejection head;
• a conveyance unit configured to convey a printing medium relative to the liquid ejection head;
• and
• a liquid supply unit configured to supply liquid to the liquid ejection head, wherein the printing apparatus forms an image on the printing medium by ejecting the liquid supplied from the liquid supply unit from an ejection port of the liquid ejection head to the printing medium, wherein
• the liquid ejection head includes
• a first substrate having a first surface and a second surface, the first surface being flat and provided with an ejection port for ejecting liquid, the second surface being opposite from the first surface and provided with a drive element and
• a second substrate joined to the second surface of the first substrate and forming a pressure chamber between the second substrate and the second surface of the first substrate, the pressure chamber being configured to be supplied with the liquid,
• a portion of the first substrate that forms the pressure chamber forms a diaphragm plate to be displaced by the drive element and is configured to eject the liquid in the pressure chamber from the ejection port upon displacement of the diaphragm plate,
• the second surface of the first substrate has an uneven shape including the drive element, and
• compared to a first region of the diaphragm plate where the ejection port is provided, a second region of the diaphragm plate surrounding the first region has low rigidity.