(19)

(11)

EP 0 020 493 A1

(12)

(43) Date of publication: 07.01.1981 Bulletin 1981/01 (21) Application number: 79901332.0 (22) Date of filing: 26.09.1979

(51) International Patent Classification (IPC):  H05B 41/ 392( . ) (86) International application number: PCT/US1979/000785 (87) International publication number: WO 1980/000776 (17.04.1980 Gazette 1980/08)

(84) Designated Contracting States: DE GB NL SE (30) Priority: 26.09.1978 US 19780945842 (71) Applicant: CONTROLLED ENVIRONMENT SYSTEMS INC. Rockville, MD 20850 (US)	(72) Inventor: WIDMAYER, Don F. Bethesda, MD 20014 (US) (74) Representative: Gold, Tibor Z., et al  Stephenson Harwood One, St. Paul's Churchyard London EC4M 8SH London EC4M 8SH (GB)