JOHN E TREMBLAY
Sheet Metal in Burlington, MA

5049404, Sep 17, 1991

Dec 9, 1988

7/282011

Semyon Kisler - Needham MA
William J. Timson - Belmont MA
John E. Tremblay - Burlington MA

Polaroid Corporation - Cambridge MA

B05D 104, B05B 5035

427 30

An electrostatic coating method and apparatus are provided that are capable of applying an extremely thin and virtually constant thickness coating to a substrate, and includes a coating applicator having an opening formed of dielectric material through which coating material flows for coating purposes. The coating material supplied to the applicator is pressurized to maintain a substantially constant volume of coating material at the applicator opening output and is vibrated in the vicinity of the applicator opening to provide a uniform flow of coating material to the applicator output, to stabilize the shape of the coating material at the applicator output and to preclude changes in coating material flow rate caused by electrostatic field induced coating material dryout. An electrostatic field of predetemined magnitude is established between the coating material surface and the adjacent substrate to thereby extract minute, uniform size particles from coating material at the applicator opening and subsequently deposit an ultra-thin layer of these particles on the adjacent substrate as the substrate moves past the applicator opening. In dielectric substrate coating applications where a relatively thick coating layer is required, an electrostatic charge is established on the dielectric substrate, at a remote location, before the substrate is coated in order to neutralize the electrostatically charged coating material so that such coatings can be electrostatically applied.