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:
Nov. 21, 1989
Filed:
Apr. 06, 1987
Andre Hecq, Nalinnes, BE;
Glaverbel, Brussels, BE;
Abstract
Light transmitting glass has at least one surface area which is matted by surface pits. That surface area has a population of merging or contiguous surface pits, the pits being of such small area and profile that clearly legible typed characters of 10-pitch size are still clearly legible when viewed through such matted surface area when that surface is held at a distance of 10 cm from the said characters. At least one matted surface area may be occupied by a population of surface pits which are of such small size that a disk having a diameter of 10 micrometer cannot be placed thereon without overlapping at least two pits. In order to produce such glass, the surface area is etched with a solution of a salt of hydrofluoric acid to leave a substantially contiguous population of fluorine-containing crystals, those crystals are removed to leave the surface area with a population of merging or contiguous surface pits, and the resulting pitted surface area is treated to remove a superficial stratum therefrom in order to leave the surface area occupied by a population of merging or continguous surface pits which are of such small size that a disk having a diameter of 10 micrometer cannot be placed thereon without overlapping at least two pits. The preferred etching medium is aqueous potassium bifluoride, and the superficial stratum removal is preferably effected by chemical polishing, e.g., using a solution containing hydrofluoric acid.