Abstract The surface of an article, such as a glass envelope for an electric lamp, is provided with a decorative pattern or indicia by coating the article with a vitreous material that includes a substance (such as lead oxide) that undergoes a permanent change in color when heated under reducing conditions, subjecting the article to a laser beam and a reducing gas flame, and varying the position of the article relative to the beam at a speed and in a manner such that the beam scans the article and thereby melts preselected portions of the vitreous coating and changes the color of such portions. In the case of a vitreous or ceramic article that is susceptible to thermally-induced fracturing, the vitreous coating material is preferably deposited on the article in the form of a frit and the article is preheated to a temperature which is near or above its strain point, thus fusing the frit in place just before the glazed heated article is exposed to the reducing environment and laser beam. An apparatus and method for concurrently firing a glass frit on an article and color-etching the resulting glazed article with a laser having control means which includes a prototype article are also disclosed.
The method of claim 1 wherein said predetermined environment is one which is reactive in nature.
Claim 2
Dependent Claim
21 words
The method of claim 2 wherein said predetermined environment is reducing in nature and is produced by an impinging gas-rich flame.
Claim 3
Dependent Claim
69 words
The method of claim 1 wherein; said coated article is composed of a material that has a coefficient of thermal expansion such that it fractures when rapidly heated to a temperature above its strain point, said beam of corpuscular energy comprises a laser beam, and at least the portion of said coated article that is struck by the laser beam is preheated to a temperature near its strain point.
Claim 4
Dependent Claim
26 words
The method of claim 4 wherein; said article comprises a glass body, and said coating comprises a pigmented light-transmitting glaze that includes a fused glass frit.
Claim 5
Dependent Claim
80 words
The method of claim 5 wherein: said glass body comprises an envelope for an electric lamp, said light-transmitting glaze contains a white pigment, said predetermined environment is reducing in nature, and the fused glass frit constituent of said glaze contains lead oxide at least a portion of which is converted by the localized heating action of said impinging laser beam and said reducing environment into lead so that said indicia or pattern is defined by silvery-black regions in said glaze.
Claim 6
Dependent Claim
56 words
The method of claim 5 wherein: said glaze is formed by coating the glass body with a powdered pigment-glass frit mixture that is fired in situ by a gas flame, and the firing of said pigment-glass frit mixture and the preheating of the glass body near its strain point are concurrently effected by a gas flame.
Claim 7
Dependent Claim
32 words
The method of claim 7 wherein said gas flame is oxidizing in nature during the firing and preheating operation and is subsequently made reducing in nature during the laser-scanning and decorating operation.