Coating apparatus – With means to apply electrical and/or radiant energy to work... – Electrostatic and/or electromagnetic attraction or...
Reexamination Certificate
2001-07-11
2003-10-07
Crispino, Richard (Department: 1734)
Coating apparatus
With means to apply electrical and/or radiant energy to work...
Electrostatic and/or electromagnetic attraction or...
C118S623000
Reexamination Certificate
active
06630027
ABSTRACT:
The present invention relates to devices for delivering or electrostatically charging powder particles, especially for use in a device for electro-attractive deposition.
The inventors, or associates working with the inventors, have described a number of techniques and devices useful for applying measured amounts of particles onto a substrate. Such depositions make it possible to deposit controlled amounts of, for example, a pharmaceutical onto spatially resolved areas of a substrate. These techniques have typically deposited charged particles or grains onto a substrate mounted on a device, which can be called an electrostatic chuck, that provides the electrical field that attracts the particles or grains. The particles or grains are typically charged, though attraction can occur through polarizations of the particles or grains. The electrostatic chuck has electrode pads that are polarized to create the attractive force. Adjacent electrodes, of a different potential, can be used to shape the attractive field or steer particles or grains away from undesired locations. A cut-away view of one such electrostatic chuck is illustrated in FIG.
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. Once attracted to a given location, grains or particles can induce an image force in nearby conductors, which image force can be a powerful contributor to the forces retaining the grains or particles. Other retentive forces include other charge and charge redistribution induced forces, packing forces and Van der Waals forces.
Further improvements in the methods and devices used to delivery the particles to the substrate, and to charge the particles, are desirable, as tools to improve electro-attractive deposition, or provide further options for use in appropriate contexts. The inventors here provide new methods and devices for these purposes.
SUMMARY OF THE INVENTION
The invention provides a re-circulating particle feed apparatus comprising: a conduit (preferably circular) of dimensions suitable for circulating gas with suspended particles; a deposition station comprising an opening onto the conduit, into which opening an electrostatic chuck fits, with a deposition surface of the chuck available to the interior of the conduit; and a propulsion device for maintaining fluid and particle circulation through the conduit, wherein the propulsion device is adapted to maintain fluid and particle circulation at a rate that brings a deposition effective amount of particles within a range of electro-attractive influence at the deposition station.
Additionally, the invention provides a reciprocating particle feed apparatus comprising: a deposition chamber; a deposition station comprising an opening onto the deposition chamber, into which opening an electrostatic chuck fits, with a deposition surface of the chuck available to the interior of the conduit, the dimensions of the deposition chamber suitable for presenting a deposition effective amount of particles suspended therein within a range of electro-attractive influence at the deposition station; and at least one piston device comprising a piston and an expansion chamber connected to the deposition chamber, the piston device for maintaining particle suspension in the deposition chamber.
Further, the invention provides a particle feed apparatus comprising: a cylindrical deposition chamber having a center axis; and a deposition station comprising an opening onto the deposition chamber, into which opening an electrostatic chuck fits, with a deposition surface of the chuck available to the interior of the conduit, the dimensions of the deposition chamber suitable for presenting a deposition effective amount of particles suspended therein within a range of electro-attractive influence at the deposition station; wherein the center axis is centered with, and orthogonal to, the opening.
REFERENCES:
patent: 3991710 (1976-11-01), Gourdine et al.
patent: 4109027 (1978-08-01), Crose
patent: 4314669 (1982-02-01), Moos
patent: 5083710 (1992-01-01), McLoughlin et al.
patent: 5213271 (1993-05-01), Uribe et al.
patent: 5660532 (1997-08-01), Castel
patent: 6143082 (2000-11-01), McInerney et al.
patent: 6227769 (2001-05-01), Wilson et al.
patent: 6444033 (2002-09-01), O'Mara et al.
Crispino Richard
Dechert LLP
Delsys Pharmaceutical Corporation
Lazor Michelle Aewedo
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