US Patent 7841678 Element substrate, printhead, head cartridge, and printing apparatus

This invention relates to an element substrate capable of confirming an electrical connection status before a printhead malfunctions. The element substrate is a substrate for a printhead, which is detachable from a printing apparatus and includes a plurality of printing elements, a logical circuit for controlling the printing elements, and a voltage application terminal for applying a driving voltage to drive the printing elements. The logical circuit is driven at a voltage lower than the driving voltage. The element substrate includes a connection status output circuit which outputs a signal reflecting the electrical connection status between the printhead and the printing apparatus on the basis of the driving voltage.