Method for ablating a coded marking into a glass workpiece and product thereof
AssigneeRCA Corporation
InventorsJohn N. Bleacher, Barry M. Cushman
Life of this patent
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Abstract
A dark-colored undercoating is deposited on a desired surface area of a glass workpiece, and a light-colored overcoating is applied upon the undercoating, each coating being dried in less than about 60 seconds. Then a plurality of related marks is recessed through the overcoating by ablation, as with a laser beam. Each of the undercoating and the overcoating is comprised of pigment particles and an alkali silicate binder. Unlike the prior practice, the undercoating contains an operative proportion of mica particles, and the overcoating is essentially free from mica.
Claims10
In a method for producing a machine-readable coded marking in a surface of a glass workpiece, said method including
- (a) coating a selected surface area of said glass workpiece with an undercoating comprising a first aqueous suspension of first pigment particles and a first alkali silicate binder,
- (b) drying said undercoating,
- (c) coating said dry undercoating with an overcoating comprising a second aqueous suspension of second pigment particles and a second alkali silicate binder,
- (d) drying said overcoating, and
- (e) recessing a plurality of related marks through said overcoating by selectively ablating said overcoating with a laser beam,
- the improvement wherein said first suspension includes an operative proportion of mica particles, said proportion of mica being operative to reduce the tendency to spalling of said glass workpiece by said laser beam, and said second suspension is essentially free from mica particles.
In a workpiece comprising a glass main body, a thin undercoating on a portion of said body and an overcoating on said undercoating, said overcoating having a plurality of related marks recessed through said overcoating, said undercoating comprising first pigment particles and a first alkali silicate binder and said overcoating comprising second pigment particles and a second alkali silicate binder,
- the improvement wherein said undercoating contains an operative proportion of mica particles therein and said overcoating is essentially free of mica, said proportion of mica being operative to reduce the tendency to spalling of the glass workpiece while said marks are being recessed through said overcoating.
Dependencies are inferred from the claim text.