An ink jet printer with ink flowing through an ink chamber and over an ink ejection port leading to a nozzle has a deflection surface such as a chamfer at the junction of the chamber and the ejection port to inhibit debris from entering the port.

A hollow cylindrical support for a plurality of flow-through inkjet print heads has two folded wall sections cooperating to define elongate inlet and outlet ink manifolds, one wall section being thermally conducting so as to promote heat transfer along the length of the support, the other wall section being thermally insulating so as to inhibit heat transfer between the inlet and outlet manifolds. The thermally insulating section serves to trap a boundary layer of fluid, for example in a cavity wall or cellular material.

An ink supply system for a droplet deposition apparatus wherein the pressure at the nozzle is controlled by a remote point, said remote point being positioned in parallel with said print head. The flow restrictions in the printhead arm and the pressure control arm of the circuit being selected to achieve this.

An injet printhead is formed by a multistage process: grooves are formed on the base of a block of piezoelectronic material, and a conductor is applied thereto. Conducting tracks are deposited on a substrate with matching spacing, such that the base and piezoelectric material can be joined giving a desired electrical connection. Channels are cut into the top of the piezoelectric block to intersect with the grooves, forming ink chambers, and these are provided with electrodes in electrical contact with the tracks. Cover plates are added to the assembly to provide a manifold and nozzles.

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.