Patent ID: 6837575

Claim:
An ink supply unit for an ink jet recording apparatus, having: a supporting member including a valve seat; and a membrane valve including: a thick portion at a periphery of the membrane valve, a portion including an ink passing port in a center of the membrane valve, opposing the valve seat, and a thin membrane portion interconnecting the thick portion and the portion including the ink passing port, said thin membrane portion being concentric around the center of the membrane valve, wherein said thick portion of said membrane valve is supported by said supporting member, and said ink passing port of said membrane valve selectively contacting said valve seat, wherein when ink is provided to said membrane valve, said ink passing port comes into contact with or separates from the valve seat correspondingly to a differential pressure of ink across said membrane valve, and wherein the thin membrane portion of the membrane valve has an angled portion that is concentric with respect to the ink passing port.