(19)

(11)

EP 0 457 881 A1

(12)

(43) Date of publication: 27.11.1991 Bulletin 1991/48 (21) Application number: 91900864.0 (22) Date of filing: 06.12.1990

(51) International Patent Classification (IPC):  G02B 3/ 00( . ) G03B 17/ 06( . ) G03B 11/ 00( . ) (86) International application number: PCT/GB1990/001898 (87) International publication number: WO 1991/009340 (27.06.1991 Gazette 1991/14)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU NL SE (30) Priority: 07.12.1989 GB 19890027644 06.07.1990 GB 19900014934 (71) Applicant: HOUGHTON, John, Ernest Goole, North Humberside DN14 6QL (GB)	(72) Inventor: HOUGHTON, John, Ernest Goole, North Humberside DN14 6QL (GB) (74) Representative: Jones, Colin, et al  H.L. Cottrell & Co. Suite 1, Kings Building South Church Side Hull North Humberside HU1 1RR Hull North Humberside HU1 1RR (GB)