US 2015/0306875 A1
WO 2015/163487 A1
Inkjet head that circulates ink
Ricoh Printing Systems America, Inc.
The benefits of circulating ink through the actuator chambers of ink jet printheads is now well known. The chambers are easily and quickly primed, air bubbles can be displaced, inks with a tendency for pigment settling or separation can be used, and fresh ink is brought to the nozzles reducing the requirements for nozzle maintenance.
Ink passes from an inlet manifold 302 through passageway 225 into the actuator chamber 221. In this design a second passageway 223 close to the nozzle allows ink to return to a separate manifold 304. Ink being supplied to the printhead is fed under a positive pressure, and a negative pressure is applied to the return path.
Overall though, the average pressure is slightly negative by arranging the negative pressure to be higher than the positive. Therefore there is enough differential pressure to achieve the continuous flow through the actuator chambers and a net negative pressure at the meniscus.
The ink flow paths and pressure chambers within the printhead are made up from a stack of etched stainless steel plates that are bonded together. Note that as the inlet and outlet manifolds are both the same side of the actuator chambers, then the overall width of the printhead is minimised.