Patent ID: 7128406

Claim:
Droplet deposition apparatus comprising: an array of fluid chambers, each chamber communicating with an orifice for droplet ejection, a common fluid inlet manifold and a common fluid outlet manifold; each chamber so connected with said inlet manifold and said outlet manifold as to enable a fluid flow from said inlet manifold, through each chamber in said array and into said outlet manifold, said fluid flow through each chamber being sufficient to prevent foreign bodies in the fluid from lodging in the orifice; and each chamber being associated with a piezolelectric actuator for effecting droplet ejection from said orifice simultaneously with said fluid flow through the chamber; wherein the flow through each chamber is at least ten times greater than the maximum fluid flow of droplets ejected through the orifice of the chamber, and the resistance to flow of said inlet and outlet manifolds is chosen such that a negative static pressure at the orifice of any chamber in the array due to the flow varies between any two chambers by an amount less than that which would give rise to significant differences in droplet ejection properties between said two chambers in the array.