Patent ID: 8002372

Claim:
A liquid pump, comprising: a liquid storage unit having liquid chambers for trapping at least two types of liquids, wherein each liquid chamber corresponds to one of said at least two types of liquids; a coupling member which connects to each liquid chamber of the liquid storage unit; a pressure adjusting mechanism, connected to the coupling member, for alternately switching an internalc pressure of each liquid chamber between a negative pressure and a positive pressure; an inlet pipe having an inlet valve capable of passing liquid only in one direction, for passing the liquid to one of the liquid chambers; an outlet pipe having an outlet valve capable of passing the liquid only in one direction, for passing the liquid from said one of the liquid chambers; and a pass resistance variable mechanism which adjusts an amount of the liquid trapped in said one of the liquid chambers depending on a level of the liquid in said one of the liquid chambers, wherein the pass resistance variable mechanism comprises a level following member and an ink liquid intake, and wherein the level following member follows the level of the liquid in said one of the liquid chambers and then moves, thereby varying an open area of the ink liquid intake.