US Patent 6942326 Ink tank

An ink tank comprises ink holding means capable of impregnating and retaining ink; and a housing for containing the ink holding means, with an ink supply port provided for the housing for supplying to the outside ink impregnated in the ink holding means, and an air inducing port for inducing the air outside into the housing. For this ink tank, the ink holding means further comprises a first ink holding member arranged on the inner face of the housing having the ink supply port open thereto, and a second ink holding member held closely to the first ink holding member, having smaller ink holding power than that of the first ink holding member, and the first ink holding member is essentially formed in the same shape as the shape of the inner face of the housing having the ink supply port open thereto, and substantially covers the inner face entirely, and grooves communicated with the ink supply port on the inner face of the housing having the ink supply port open thereto. With the structure thus arranged, ink can be filled in the second ink holding member almost uniformly on the entire abutting surface on the first ink holding member, thus making it possible to enhance the filling efficiency of ink when ink is filled.