Patent ID: 8272713

Claim:
An image forming apparatus comprising: a recording head having a nozzle for discharging droplets of liquid; a liquid tank that stores liquid to be supplied to the recording head; a first fluid flow path that supplies the liquid to the recording head; a second fluid flow path that is in fluid communication with the liquid tank; a pressure adjusting valve that allows fluid communication between the first fluid flow path and the second fluid flow path and that has an internal flow path resistance that varies depending upon a flow rate of liquid flowing through the first fluid flow path; a third fluid flow path that allows fluid communication between the second fluid flow path and the pressure adjusting valve or between the liquid tank and the pressure adjusting valve; a liquid feeding unit provided in the third fluid flow path; a cap member that is configured to cover a nozzle surface of the recording head; and a suction unit that is in fluid communication with the cap member, wherein when droplets of liquid are discharged through the nozzle, the recording head is in fluid communication with the liquid tank via the pressure adjusting valve, and the liquid feeding unit feeds the liquid from the liquid tank to the recording head, the pressure adjusting valve includes a tube member that defines an internal fluid flow path of the pressure adjusting valve; a movable member that is movably disposed in the internal fluid flow path, wherein the tube member and the movable member form a first throttling part disposed on a side of the first fluid flow path and a second throttling part disposed on a side of the second fluid flow path, the third fluid flow path is in fluid communication with a part between the first throttling part and the second throttling part, the movable member moves depending on the flow rate of liquid flowing in the first fluid flow path, a throttle value of the second throttling part varies depending on a movement of the movable member, and the movable member includes a sealing unit that seals the fluid communication between the first fluid flow path and the second fluid flow path when the cap member covers the nozzle surface of the recording head and a negative pressure is generated in a cap-member space formed between the cap member and the nozzle surface by driving the suction unit.