Patent ID: 6988791

Claim:
An ejection head suitable for ejecting a liquid in the form of droplets, comprising: a nozzle plate made of silicon and having at least one ejection nozzle; a substrate or actuation support made of silicon and having at least one actuator for activating the ejection of said droplets of liquid through said at least one nozzle, said at least one ejection nozzle being arranged in front of said at least one actuator; a hydraulic circuit for containing and conveying said liquid inside said ejection head; and a junction which joins said nozzle plate and said substrate integrally together and which is arranged for being wetted by the liquid contained in said hydraulic circuit, said junction being produced by anodic bonding, an intermediate layer of glass which is arranged along the junction zone between said substrate and said nozzle plate, said intermediate layer of glass being preliminary deposited, during manufacturing of said ejection head, on an outer surface of said substrate for preparing it to be joined with a corresponding surface of silicon of said nozzle plate and therefore form said junction by means of said anodic bonding, and a conductive protection layer arranged adjacently to said layer of glass and extending over the area of said actuator for protecting it, said conductive protection layer extending also along the area of the junction between said substrate and said nozzle plate and having a portion which is arranged externally with respect to the junction zone, said portion being provided for allowing, during the manufacture of said ejection head, the electrical connection between said conductive layer and a counter-electrode of an appropriate anodic bonding machine adapted for producing said junction by applying a suitable potential between said substrate and said nozzle plate, whereby said ejection head presents a chemically inert structure and in particular a chemically inert junction in relation to a liquid prepared with a solvent that may be selected from a group consisting of an aliphatic or aromatic hydrocarbon, an aliphatic or aromatic alcohol, an ester, a glycol ester, a ketone and a lactone.