Electrets
Patent 4291245 Issued on September 22, 1981. Estimated Expiration Date: 
September 4, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
September 4, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3246627 3301707 3421930 3600216 3663265 Method of improving the reusability of an electrophotographic photosensitive plate Method of making a metallized video disc having an insulating layer thereon Method of polarizing a thermoplastic resin film Method of fabricating improved capacitors and transformers Stable electrets of styrene-type polymers InventorsAssigneeApplicationNo. 06/072303 filed on 09/04/1979US Classes:307/400, ELECTRETS264/104, FORMING ELECTRICAL ARTICLES BY SHAPING ELECTROCONDUCTIVE MATERIAL264/436, Producing permanently polarized dielectric (e.g., electret, etc.)264/81, GAS OR VAPOR DEPOSITION OF ARTICLE FORMING MATERIAL ONTO MOLD SURFACE427/100, Piezoelectric properties427/248.1, COATING BY VAPOR, GAS, OR SMOKE427/255.6, Organic coating applied by vapor, gas, or smoke427/295, Metal base427/350, Vacuum or reduced pressure utilized427/569, Plasma (e.g., corona, glow discharge, cold plasma, etc.)427/58, ELECTRICAL PRODUCT PRODUCED427/70, Nonmetallic coating formed by vapor deposition428/457, Of metal428/461, Next to addition polymer from unsaturated monomers428/900, MAGNETIC FEATURE428/913, MATERIAL DESIGNED TO BE RESPONSIVE TO TEMPERATURE, LIGHT, MOISTURE, ETC.428/929, Electrical contact feature428/934, Electrical process428/938Vapor deposition or gas diffusionExaminersPrimary: Herbert, Thomas J. Jr.Attorney, Agent or FirmInternational ClassesH01G 7/00 (20060101)H01G 7/02 (20060101) AbstractA process for preparing polymer electrets comprising the following steps:(a) providing a parylene film having one side affixed to a metal layer and grounding said metal layer;(b) charging the free side of the film with a direct current corona, the charge being of sufficient magnitude to convert the film to an electret;(c) providing p-xylylene monomer vapor in sufficient amount to coat the charged film; and(d) introducing the vapor from step (c) and the electret into a deposition zone, said zone being under vacuum and at a temperature at which the vapor will condense, whereby the electret is conformally coated with parylene.Field of SearchUMBRELLA-FRAME MAKING | |
