(19)

(11)

EP 0 651 878 A1

(12)

(43) Date of publication: 10.05.1995 Bulletin 1995/19 (21) Application number: 93915538.0 (22) Date of filing: 19.07.1993

(51) International Patent Classification (IPC):  G01L 23/ 16( . ) H01T 13/ 40( . ) G01L 23/ 22( . ) (86) International application number: PCT/AU1993/000359 (87) International publication number: WO 1994/002817 (03.02.1994 Gazette 1994/04)

(84) Designated Contracting States: DE ES FR GB IT SE (30) Priority: 20.07.1992 AU 1992PL03603 (71) Applicant: INVENT ENGINEERING PTY. LTD. Sylvania, NSW 2224 (AU)	(72) Inventors: MITCHELL, William, Richard Sylvania Waters, NSW 2224 (AU) MITCHELL, Steven James Marrsfield, NSW 2122 (AU) (74) Representative: Jochem, Bernd, Dipl.-Wirtsch.-Ing.  Patentanwalt, Staufenstrasse 36 D-60323 Frankfurt am Main D-60323 Frankfurt am Main (DE)