Patent ID: 8677932

Claim:
A feed system for continuously feeding measured doses of source material to a vapor deposition apparatus, said feed system comprising: a bulk material hopper; an upper dose receptacle disposed to receive source material from said hopper; a transfer mechanism disposed downstream of said upper dose receptacle, said transfer mechanism configured to transfer the source material to a downstream deposition head while isolating the deposition conditions within the deposition head and blocking upstream diffusion of sublimated source from said vapor deposition apparatus to said feed system; a metering mechanism operatively disposed upstream of said transfer mechanism and positioned between said upper dose receptacle and said transfer mechanism, said metering mechanism further comprising: a receiver disposed to receive source material supplied from said upper dose receptacle, said receiver having an outlet; a discharge port axially offset from said receiver outlet; a reciprocating delivery member having a passage defined therethrough, wherein the passage defines a volume; a controllable drive device configured to move said reciprocating delivery member in a reciprocating path between a load position wherein said passage is aligned with and below said receiver outlet and a discharge position wherein said passage is aligned with and above said discharge port, wherein the controllable drive device is configured to move said reciprocating delivery member in the reciprocating path at a reciprocating rate; and a stroke limiter disposed on said delivery member at a location to detect an overfill condition of said receiver; wherein the amount of source material transferred from said upper dose receptacle to said transfer mechanism is a function of the volume of said passage and the reciprocating rate of said delivery member in said metering mechanism.