Patent ID: 8465132

Claim:
An image forming apparatus comprising: a recording head having a nozzle for discharging droplets of liquid; a first fluid flow path supplying the liquid to the recording head; a liquid tank storing the liquid; a second fluid flow path being in fluid communication with the liquid tank; a pressure adjusting valve allowing the first fluid flow path and the second fluid flow path to be in fluid communication with each other; and a third fluid flow path having a liquid feeding unit, the third fluid flow path allowing either the second fluid flow path or the liquid tank and the pressure adjusting valve to be in fluid communication with each other, wherein the pressure adjusting valve comprises: a tube member defining an internal fluid flow path of the pressure adjusting valve; a movable member movably disposed in the internal fluid flow path; 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, wherein the second throttling part is formed as a gap between an internal wall of the tube member and the movable member, a length of the gap varies in response to a flow rate of the liquid flowing in the first fluid flow path, an internal fluid resistance of the pressure adjusting valve varies in response to the flow rate of the liquid flowing in the first fluid flow path, the third fluid flow path is in fluid communication with the internal fluid flow path through a part of the pressure adjusting valve, the part being disposed between the first throttling part and the second throttling part, and when the liquid is discharged from the nozzle, the liquid is fed from the liquid tank to the recording head by the liquid feeding unit in a state where the recording head is in fluid communication with the liquid tank via the pressure adjusting valve.