Patent ID: 7172268

Claim:
An ink jet head base body in which a heat accumulation layer, a heater generating heat energy used for discharging ink, and a protection film protecting the heater are sequentially formed on a substrate, the ink jet head base body in which a total thickness of a portion above from the heater in the protection film ranges from 0.2 Î¼m to 0.6 Î¼m, a heat resistance value of the portion above from the heater in the protection film ranges from 5Ã—10 âˆ’9 m 2 Â·K/W to 50Ã—10 âˆ’9 m 2 Â·K/W, and the heat resistance value of a portion below from the heater in the heat accumulation layer is not lower than double the heat resistance value of the portion above from the heater in the protection film.