Method of making arc tubes
AssigneeAdvanced Lighting Technologies, Inc.
InventorsJuris Sulcs, Abbas Lamouri
Life of this patent
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Abstract
The present invention is directed to methods of making arc tubes for high intensity discharge lamps. The bottom portion of the light emitting chamber of the arc tubes is flattened in an area between the electrodes to reduce the distance between the bottom wall of the arc tube and the arc, and to increase the surface area of the pool of condensed halides during operation of a metal halide lamp. The flattened bottom of the arc tubes may be generally planar, slightly arcuate longitudinally and/or transversely, or slightly v-shaped longitudinally and/or transversely. The top portion of the arc tube conforms generally to the shape of the arc during operation of the lamp.
Claims40
A method of making an arc tube chamber intermediate tubular end portions comprising the steps of:
- (a) providing a tube of vitreous material;
- (b) heating a portion of the tube sufficiently to soften it in a predetermined area;
- (c) axially compressing the tube to force the softened material in the heated area radially inward and outward around the circumference of the tube to thereby thicken the tube wall in the heated area;
- (d) repeating step (b) and step (c) in areas of the tube proximate to the previously thickened tube wall at least one additional time to thereby thicken the wall of the tube over an axial distance approximating the length of the desired chamber;
- (e) heating the thickened wall area of the tube;
- (f) positioning a mold having a surface defining a chamber cavity of a desired shape over the heated thickened wall area, the chamber cavity defining surface having a portion for defining a canoe-shaped portion of the arc tube chamber;
- (g) internally pressurizing the tube to expand the heated thickened area of the tube against the internal wall of the mold cavity to thereby form a chamber in the tube;
- and
- (h) removing the mold from the chamber to thereby provide an arc tube chamber intermediate open tubular end portions.
A mold for forming a bulbous arc tube chamber intermediate tubular end portions in a formed body arc tube, said mold defining a cavity having a flattened portion extending over 50% or more of the maximum length of the cavity.
A method of making an arc tube chamber intermediate tubular end portions comprising the steps of:
- (a) providing a tube of vitreous material;
- (b) heating a portion of the tube sufficiently to soften it in a predetermined area;
- (c) axially compressing the tube to force the softened material in the heated area radially inward and outward around the circumference of the tube to thereby thicken the tube wall in the heated area;
- (d) repeating step (b) and step (c) in areas of the tube proximate to the previously thickened tube wall at least one additional time to thereby thicken the wall of the tube over an axial distance approximating the length of the desired chamber;
- (e) heating the thickened wall area of the tube;
- (f) positioning a mold having an elongated chamber cavity over the heated thickened wall area, the chamber cavity having a flattened portion extending between about 50% and about 80% of the maximum length of the cavity;
- (g) internally pressurizing the tube to expand the heated thickened area of the tube against the internal wall of the mold cavity to thereby form a chamber in the tube;
- and
- (h) removing the mold from the chamber to thereby provide an arc tube chamber intermediate open tubular end portions.
A mold for forming an elongated bulbous chamber intermediate tubular end portions in an arc tube, said mold having a surface defining a cavity for molding a canoe-shaped portion of the chamber.
A method of making an arc tube having a bulbous chamber disposed between tubular end portions comprising the steps of:
- providing a tube of vitreous material;
- and
- forming a bulbous chamber in the tube having a lateral cross-section at the central portion thereof formed by first and second circular portions, the ratio the radius of curvature of the first portion to the radius of curvature of the second portion being between about 1.5 and about 5.
A method of making an arc tube having a bulbous chamber disposed between tubular end portions comprising the steps of:
- providing a tube of vitreous material;
- and
- forming a bulbous chamber in the tube having a lateral cross-section at the central portion thereof formed by a circular arc of between about 220 degrees and 340 degrees and a non-curved portion.
A method of making a horizontally burning HID arc tube comprising the steps of:
- providing a tube of vitreous material;
- and
- forming a light emitting chamber in said tube having an upper portion longitudinally conforming generally to the shape of the arc to be drawn in the chamber and a canoe-shaped lower portion.
A method of making an arc tube for a horizontally burning HID arc tube comprising the steps of:
- (a) providing a tube of vitreous material;
- (b) heating a portion of the tube sufficiently to soften it in a predetermined area;
- (c) axially compressing the tube to force the softened material in the heated area radially inward and outward around the circumference of the tube to thereby thicken the tube wall in the heated area;
- (d) repeating step (b) and step (c) in areas of the tube proximate to the previously thickened tube wall at least one additional time to thereby thicken the wall of the tube over an axial distance approximating the length of the desired chamber,
- (e) heating the thickened wall area of the tube;
- (f) positioning a mold having a surface defining a cavity for molding a chamber having a portion longitudinally conforming generally to the shape of the arc to be drawn in the chamber opposite of a canoe-shaped portion;
- (g) internally pressurizing the tube to expand the heated thickened area of the tube against the internal wall of the mold cavity to thereby form a chamber in the tube;
- and
- (h) removing the mold from the chamber to thereby provide an arc tube chamber intermediate open tubular end portions.
A method of making an arc tube for an HID lamp comprising the steps of:
- providing a tube of vitreous material;
- and
- forming a bulbous chamber intermediate the end portions of the tube, the chamber having a flattened portion extending over 50% or more of the maximum length of the chamber.
Dependencies are inferred from the claim text.