Droplet deposition apparatus comprises 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, and means for generating a fluid flow into the inlet manifold, through each chamber in the array and into the outlet manifold, the fluid flow through each chamber being sufficient to prevent foreign bodies in the fluid from lodging in the orifice. Each chamber is associated with means for effecting droplet ejection from the orifice simultaneously with the fluid flow through the chamber. The resistance to flow of one of the inlet and outlet manifolds is chosen such that the pressure at a fluid inlet to any chamber in the array varies between any two chambers by an amount less than that which would give rise to significant differences in droplet ejection properties between these two chambers.
Droplet deposition apparatus comprises 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, and means for generating a fluid flow into the inlet manifold, through each chamber in the array and into the outlet manifold, the fluid flow through each chamber being sufficient to prevent foreign bodies in the fluid from lodging in the orifice. Each chamber is associated with means for effecting droplet ejection from the orifice simultaneously with the fluid flow through the chamber. The resistance to flow of one of the inlet and outlet manifolds is chosen such that the pressure at a fluid inlet to any chamber in the array varies between any two chambers by an amount less than that which would give rise to significant differences in droplet ejection properties between these two chambers.