Janszen 1949 Details Hits: 7377 Filed: October 5, 1949U.S. Patent 2,631,196Granted: October 5, 1953 Arthur A. Janszen, Cambridge, Mass."Electrostatic Loud-Speaker"Referenced by Walker and Williamson in U.S. Pats. 3,008,013 & 3,008,014.