The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 12, 1989
Filed:
Dec. 09, 1988
Hitoshi Kageyama, Osaka, JP;
Minolta Camera Kabushiki Kaisha, Osaka, JP;
Abstract
An optical filter used for a color image reader in order to adjust each amount of red, green and blue rays into constant ratio and to cutoff the rays of the near infrared radiation, the optical filter having a heat absorbing optical glass substrate and first and second interference films formed on the opposite sides of the substrates. The first interference film has three to eleven layers wherein a first layer immediately adjacent to the substrate has an optical thickness of .lambda./4 or .lambda./8 and a last layer farthest from the substrate has an optical thickness of .lambda./8, and said second interference film has thirteen to twenty-three layers wherein each of a first layer, second layer and third layer formed closest to the substrate in this order has an optical thickness greater than .lambda./4 and a last layer farthest from the substrate has an optical thickness of .lambda./8.