US 4,337,414 A · Compact fluorescent lamp having convoluted tubular envelope of tridimensional configuration, method of making such envelope, and lighting unit incorporating such lamp

Abstract

A fluorescent lamp of high brightness and compact size is provided by forming the envelope from vitreous tubing that is bent upon itself in such a manner that the envelope has either five or seven U-shaped sections which are disposed in tridimensional array and define a single convoluted discharge channel. The U-shaped sections are so oriented that the tubular legs of the U's are positioned in side-by-side columnar relationship with each other and the sealed ends of the tubing are located adjacent one another. The lamp thus has an arc length that is more than six or eight times as long as the overall height dimension of the convoluted envelope and generates light in a very efficient manner. The retrobent fluorescent lamps are combined with a protective housing, a base structure and operating circuits of various types to provide convection-cooled lamp units that are small enough to be used in table lamps and similar lighting fixtures but have light outputs in excess of 1,500 lumens and efficacies in the order of 60 lumens per watt. Various arrangements for including the ballast and other circuit components either as integral parts of the lamp unit or as separate components which are housed in the lighting fixture and thus permitting the lamp units to be used as direct replacements for incandescent type lamps are disclosed. Method of manufacturing the various multi-U-bent envelopes from a single piece of glass tubing employing arcuate molding components and sequential bending operations are also disclosed.

Claims21

Dependent claims

In an electric discharge lamp that contains a pair of spaced electrodes and an ionizable medium which sustains an arc discharge between the electrodes when the lamp is energized, the improvement comprising;

a sealed tubular envelope of light-transmitting material having six substantially straight segments that are joined by five curved segments and together therewith form five generally U-shaped sections that merge with one another and define a single discharge channel of convoluted configuration,
four of the conjoined generally U-shaped sections of said envelope being arranged in paired relationship and constituting two generally S-shaped sections that are disposed in different planes and are connected by the fifth generally U-shaped section,
each of the generally U-shaped sections being so oriented that (a) the discharge channel is terminated by two of the substantially straight segments and (b) all of the substantially straight segments extend in the same general direction in columnar array and thus provide a light source that is tridimensional and of compact size.

In the manufacture of an electric lamp, the method of forming vitreous tubing that is initially substantially straight into a lamp envelope of convoluted configuration that has five conjoined U-bent segments, which method comprises the steps of;

heating a predetermined length of such substantially straight vitreous tubing in a manner such that the end portions thereof are rigid and the portions thereof which are to be reshaped are uniformly softened sufficiently to be bent without fracturing or collapsing,
placing a first arcuate mold means against a heat-softened central portion of the tubing,
gripping the rigid end portions of said tubing and swinging them toward one another along a common plane until the heat-softened central portion of the tubing is bent around said first mold means through an arc such that the tubing is U-shaped and the first U-bent segment is formed,
placing a second mold means of arcuate configuration against heat-softened medial parts of each of the leg portions of the U-shaped tubing and, while maintaining the gripped end portions of the tubing stationary, swinging the said first-formed U-bent segment and the first mold means through an arc of approximately 180.degree. along a path which is substantially normal to the plane of the first bending operation and thereby simultaneously bending both of the heat-softened medial parts of said leg portions around the second mold means and forming an additional pair of U-bent segments which are aligned with one another and position the neck of the first-formed U-bent segment proximate the gripped end portions of the tubing,
placing a third arcuate mold means against heat-softened parts of both legs of the tubing at a predetermined location near the gripped end portions of the tubing and, while maintaining the three previously-formed U-bent segments and associated mold means stationary, swinging each of the gripped end portions through an arc of approximately 180.degree. in a direction which is opposite to that in which the second bending operation was performed and along paths which are also substantially normal to the plane of the first bending operation and thereby simultaneously bending the heat-softened parts of said legs around the third mold means and forming two additional U-bent segments in the tubing which are aligned with one another and position the gripped end portions of the tubing adjacent the second-formed pair of U-bent segments, and then
cooling the resulting multi-U-bent tubular envelope to rigidify and set the vitreous tubing in its convoluted configuration and removing said first, second and third mold means.

3 more elements

In the manufacture of an electric lamp, the method of forming vitreous tubing that is initially substantially straight into a lamp envelope of compact convoluted configuration that has seven conjoined U-bent segments, which method comprises the steps of;

heating a predetermined length of such substantially straight vitreous tubing in a manner such that the end portions thereof are rigid and the portions thereof which are to be reshaped are uniformly heated sufficiently to be bent without fracturing or collapsing,
placing a first arcuate mold means against a central portion of the tubing which has been heat-softened,
gripping the rigid end portions of said tubing and swinging them toward one another along a common plane until the heat-softened central portion of the tubing is bent around said first mold means through an arc such that the tubing is U-shaped and the first U-bent segment is formed,
placing a second mold means of arcuate configuration against heat-softened medial portions of each of the leg segments of the U-shaped tubing and, while maintaining the gripped end portions of the tubing stationary, swinging the first-formed U-bent segment and first mold means through an arc of approximately 180.degree. along a path which is substantially normal to the plane of the first bending operation and thereby simultaneously bending both of the heat-softened medial portions of the leg segments around said second mold means and forming an additional pair of U-bent segments in the tubing which are aligned with one another and position the neck of the first-formed U-bent segment proximate the gripped end portions of the tubing,
placing (a) a third arcuate mold means against heat-softened parts of both legs of the tubing at a location between the neck of the first-formed U-bent segment and the second-formed pair of U-bent segments and (b) a fourth arcuate mold means against heat-softened parts of both legs of the tubing at a predetermined location proximate but spaced from the gripped end portions of the tubing,
swinging the gripped end portions of the tubing and first-formed U-bent segment in opposite directions through arcs of approximately 180.degree. along paths that lie in a common plane and thereby bending the respective heat-softened parts of the tubing legs around the said third and fourth mold means and forming them into two pairs of aligned U-bent segments that position the gripped end portions of the tubing and the first-formed U-bent segment adjacent but on opposite sides of the second-formed pair of U-bent segments, and then
cooling the resulting multi-U-bent tubular envelope to rigidify and set the vitreous tubing in its convoluted configuration and removing said first, second, third and fourth mold means.

4 more elements

heating a predetermined length of such substantially straight vitreous tubing in a manner such that the end portions thereof are rigid and the portions of the tubing which are to be reshaped are uniformly heated sufficiently to be bent without fracturing or collapsing,
placing a first arcuate mold means against a heat-softened central portion of the tubing,
gripping the rigid end portions of said tubing and swinging them toward one another along the common plane until the heat-softened central portion of the tubing is bent around said first mold means through an arc such that the tubing is U-shaped and the first U-bent segment was formed,
placing second and third mold means of arcuate configuration against heat-softened medial parts of each of the leg portions of the U-shaped tubing and, while maintaining the first-formed U-bent segment of the tubing stationary, swinging the gripped end portions of the tubing in the same direction through arcs of approximately 180.degree. along paths which are substantially normal to the plane of the first bending operation and thereby simultaneously bending both of the heat-softened medial parts of the leg portions around the second and third mold means and forming second and third U-bent segments which are aligned with one another and position the gripped end portions of the tubing proximate the neck of the first-formed U-bent segment,
placing fourth and fifth arcuate mold means in contact and bridging relationship with heat-softened medial parts of the four respective leg portions of the second and third U-bent segments and, while maintaining the first-formed U-bent segment stationary, swinging the second-formed and third-formed U-bent segments of the tubing in opposite directions through arcs of approximately 180.degree. and thereby simultaneously bending the said medial parts of the four leg portions of the tubing around the fourth and fifth mold means and forming four additional U-bent segments that are arranged in pairs and position the second-formed and third-formed U-bent segments on opposite sides of the first-formed U-bent segment, and then
cooling the resulting multi-U-bent tubular envelope to rigidify and set the vitreous tubing in its convoluted configuration and removing said first, second, third, fourth and fifth mold means.

3 more elements

Dependencies are inferred from the claim text.

Compact fluorescent lamp having convoluted tubular envelope of tridimensional configuration, method of making such envelope, and lighting unit incorporating such lamp

Life of this patent

Compact fluorescent lamp having convoluted tubular envelope of tridimensional configuration, method of making such envelope, and lighting unit incorporating such lamp

Life of this patent

Abstract

Claims21