CA2108748A1 - Self-supporting/self-centering filament - Google Patents
Self-supporting/self-centering filamentInfo
- Publication number
- CA2108748A1 CA2108748A1 CA 2108748 CA2108748A CA2108748A1 CA 2108748 A1 CA2108748 A1 CA 2108748A1 CA 2108748 CA2108748 CA 2108748 CA 2108748 A CA2108748 A CA 2108748A CA 2108748 A1 CA2108748 A1 CA 2108748A1
- Authority
- CA
- Canada
- Prior art keywords
- filament
- lamp
- lamp envelope
- end segments
- segment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000002775 capsule Substances 0.000 claims abstract description 20
- 238000000576 coating method Methods 0.000 claims abstract description 10
- 239000011248 coating agent Substances 0.000 claims abstract description 9
- 230000007704 transition Effects 0.000 claims description 13
- 239000011888 foil Substances 0.000 claims description 8
- 239000004020 conductor Substances 0.000 claims description 7
- 230000008878 coupling Effects 0.000 claims 2
- 238000010168 coupling process Methods 0.000 claims 2
- 238000005859 coupling reaction Methods 0.000 claims 2
- 238000000034 method Methods 0.000 description 11
- 230000008569 process Effects 0.000 description 8
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 7
- 229910052750 molybdenum Inorganic materials 0.000 description 7
- 239000011733 molybdenum Substances 0.000 description 7
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 5
- 230000005855 radiation Effects 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000003993 interaction Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- 241001279686 Allium moly Species 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002366 halogen compounds Chemical class 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01K—ELECTRIC INCANDESCENT LAMPS
- H01K1/00—Details
- H01K1/18—Mountings or supports for the incandescent body
- H01K1/24—Mounts for lamps with connections at opposite ends, e.g. for tubular lamp
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01K—ELECTRIC INCANDESCENT LAMPS
- H01K1/00—Details
- H01K1/02—Incandescent bodies
- H01K1/14—Incandescent bodies characterised by the shape
Landscapes
- Resistance Heating (AREA)
Abstract
ABSTRACT
SELF-SUPPORTING/SELF-CENTERING FILAMENT
A self-supporting/self-centering filament for a double-ended lamp envelope includes two inlead portions, an active center segment, two inactive end segments and two skip turns. The two end segments are attached to the inlead portions and contact an inner surface of the lamp envelope so that the filament is supported and centered within the lamp envelope. The two skip turns interconnect the end segments and the center segment. The end segments, the center segment and the skip turns have a coiled coil configuration and have a common central axis.
The filament is particularly useful in a tubular incandescent lamp capsule having an infrared reflective coating on its outer surface as the filament exhibits excellent self-supporting and self-centering characteristics.
SELF-SUPPORTING/SELF-CENTERING FILAMENT
A self-supporting/self-centering filament for a double-ended lamp envelope includes two inlead portions, an active center segment, two inactive end segments and two skip turns. The two end segments are attached to the inlead portions and contact an inner surface of the lamp envelope so that the filament is supported and centered within the lamp envelope. The two skip turns interconnect the end segments and the center segment. The end segments, the center segment and the skip turns have a coiled coil configuration and have a common central axis.
The filament is particularly useful in a tubular incandescent lamp capsule having an infrared reflective coating on its outer surface as the filament exhibits excellent self-supporting and self-centering characteristics.
Description
92-1-015 210~7~8 PATENT
SELF-SUPPORTING/S~LF-CENTERING FILAMENT
Field of the Invention This invention relates to tubular incandescent lamps and, more particularly, to a self-supporting, self-centering filament in a double-ended lamp capsule.
Backqround of the Invention Tubular incandescent halogen lamps include a helical filament axially mounted within a quartz lamp envelope. Filament supports attached to the filament support and center the filament within the lamp envelope. The ends of the lamp envelope are hermetically sealed, typically by press sealing.
Molybdenum foils electrically connect the filament through the seals to external electrical leads. The interior of the lamp envelope is typically filled with an inert gas and one or more halogen compounds.
It is important to center the filament within the lamp envelope to prevent undesired interactions between the filament and the walls of the lamp envelope. In addition, it is well known that for proper lamp performance, the spacing between coils of the filament must be precisely controlled. This is important because a slight change in filament length significantly changes the operating temperature of the filament. Any change in filament temperature will ., 92-1-015 ~1 n ~ 7 ~ 8 PATENT
have a dramatic effect on lamp performance and life.
In one particular lamp type, filament location i8 even more critical. This type of lamp is known as an infrared conserving lamp, which has a wavelength selective filter coating applied to a surface of the lamp envelope. A central region of the lamp envelope adjacent to the filament typically has a geometrically shaped section, such as an ellipsoid. The selective filter coating transmits visible radiation and reflects infrared radiation back to the filament. The reflected infrared radiation can significantly reduce the electrical power consumption of the lamp. In order to gain maximum benefit from the reflected infrared radiation, the filament must be very precisely centered on the axis of the lamp envelope.
Also, in order for the filament to perform at its design temperature, the filament length must be precisely controlled.
An important component of the tubular incandescent lamp capsule described above is the filament support used to support and center each end of the filament and to conduct electrical energy to the filament.
Filament supports for tu~ular incandescent lamps are disclosed in U.S. Patent No. 4,942,331 issued July 17, lg90 to Bergman et al; U.S. Patent No. 4,510,416 issued April 9, 1985 to Meade et al and U, S. Patent No. 4,959,585 issued September 25, 1990 to Hoegler et al. Filament supports are also disclosed in pending application Serial No. 07/815,004 filed December 27, 1991 and in pending application Serial No. 07/815,089 filed December 27, 1991. Factors involved in the 92-1-015 2 1 n~7~8 PAT~NT
design of filament supports include the requirement for easy insertion in a tubular lamp envelope, which may vary in inside diameter from lamp to lamp, the requirement for accurate centering of the filament over the life of the lamp and the requirement to maintain the filament at a predetermined length throughout the life of the lamp.
It is a general object of the present invention to provide improved tubular incandescent lamp capsules.
It is ano~her object of the present invention to provide a filament which exhibits accurate and stable self centering within a tubular incandescent lamp capsule.
It is a further object of the invention to provide a filament which is self supporting within a tubular incandescent lamp capsule.
It is yet another object of the present invention to provide filaments for tubular incandescent lamp capsules which are easy to manufacture and which are low in cost.
SummarY of the Invention According to the present invention, these and other objects and advantages are achieved in a self-supporting/self-centering filament for mounting in a double-ended lamp envelope. The filament comprises an active center segment, two inactive end segments, and two sXip turns. The two end segments contact an inner surface of the lamp envelope. The skip turns interconnect each end segment and the center segment, each skip turn providing axial spacing between the 92-1-015 ~ 1 n~7~8 center segment and the respective end segment. The end se~ments, the center segment and the skip turns have a coiled coil configuration and have a common central axis. In a preferred embodiment of the present invention, the end segments are coiled around a mandrel and the filament comprises a single length of wire.
According to another aspect of the invention, there is provided a lamp capsule comprising a light-transmissive lamp envelope including seals at opposite ends thereof, and having a central axis. The lamp capsule additionally comprises a coiled coil filament within the envelope having two inactive end segments, an active central segment, and skip turns interconnecting the end segments and the central segment. An inner surface of the lamp envelope contacts the end segments for retaining the filament within the lamp envelope such that the filament is centered within the lamp envelope.
In a preferred embodiment of the present invention, the lamp capsule further comprises foil conductors which pass through the seals and connect opposite ends of the filament to external leads. The lamp envelope further includes a central section having an infrared reflective coating thereon, transition sections located on either side of the central section, and parent tu~ing sections located between the transition sections and the seals. The filament central segment is located within the en~elope central section. The filament skip turns are located within the envelope transition sections. An inner surface of each parent 92-1-015 2 ~ 7 ~ 8 PATENT
tubing section contacts respective filament end segments for retaining the filament within the lamp envelope.
3rief Description of the Drawinqs For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the accompanying drawings which are incorporated herein by reference and in which:
FIG. 1 shows a tubular incandescent lamp capsule in accordance with the prior art;
FIG. 2 shows a filament of the present invention;
and FIG. 3 shows a tubular incandescent lamp capsule of the present invention incorporating the filament of FIG. 2.
Descri~tion of the Prior Art : A tubular incandescent lamp capsule in accordance with the prior art is shown in FIG. 1. A helically coiled filament 10 is mounted within a tubular lamp envelope 12. The filament 10 is supported at each end by filament supports 14 and 16. The filament supports 14 and 16 center the filament 10 on a central axis 20 of lamp envelope 12. Filament support 14 is electrically connected to an external lead 22 by a molybdenum foil conductor 24 which passes through a seal 26. Filament support 16 is electrically connected to an external lead 30 by a molybdenum foil conductor 32 which passes through a seal 34. Seals 26 92-1-015 ?1 n~ PATENT
and 34 hermetically seal the lamp envelope 12. An infrared reflective coating 36 is applied to the outside surface of the lamp envelope 12. Helical portions of filament supports 14 and 16 engage the inner surface of lamp envelope 12 and center filament 10 on axis 20. The filament supports 14 and 16 may be made from moly~denum and the filament 10 is made from tungsten. The filament supports 14 and 16 are welded to the filament 10.
Detailed Description of the Invention A filament in accordance with the present invention is shown in FIG. 2. A filament S0 has a "coiled coil" configuration (described below) with three coaxial segments: a center segment 52 and two end segments 54 and 56. The filament 50 has a central axis 58 along which the three segments are coaxially located. The center segment 52 is attached to end segments 54 and 56 through skip turns 60 and 62, respectively. Inlead portions 64 and 66 are located at opposite ends of the filament 50 and are connected to the end segments 54 and 56, respectively.
The "coiled coil" configuration of the filament 50, as will be appreciated by those skilled in the art, is so called because the filament preferably includes a single length of electrically conductive wire, such as tungsten, which is first wound in a helix about a first molybdenum mandrel. The resulting tungsten wire helix and molybdenum mandrel structure is then helically coiled about a pin, or second mandrel. The pin is preferably made of steel, 92-1-015 ~l n ~ 7 ~ 8 PATENT
but other materials are suitable. The pin i8 thereafter retracted from the structure leaving the first molybdenum mandrel in place with the tungsten wire wound helically therearound. The remaining structure is then chemically treated, preferably with an acid, to selectively remove (dissolve) portions of the first molybdenum mandrel. Portions of the filament are masked with an acid resistant coating such as wax, during the procedure, for protecting sections of the mandrel from the acid so that such protected sections of the mandrel remain in place after the process. This process yields a tungsten wire in the form of a double helically wound structure known as a "coiled coil" filament. Such a coiled coil configuration exhibits excellent self-centering and self-supporting characteristics.
During operation in an incandescent lamp, portions of the filament which surround remaining sections of the mandrel are electrically inactive. In other words, only the filament portions which surround removed sections of the mandrel are electrically active and will reach incandescence. In a preferred embodiment of the present invention, only the center segment of the filament is electrically active and reaches incandescence during operation. The end segments of the filament surround remaining sections of the mandrel and are electrically inactive during operation.
The skip turns 60 and 62 are formed by a short length of the filament, preferably within the range of lmm to 3mm in length, having a reduced number of ~`
92-1-0~5 ?,1 n ~ 7 'I ~ PATENT
_ ~ _ secondary turns per inch (TPI) in relation to the secondary Tpr of the other filament segments, thus, producing a gap between the segments. The s~ip turns readily define the three filament segments and aid in the mandrel section removal process. In addition, the skip turns provide accurate axial filament segment positioning within a double-ended envelope by providing axial spacing between the end segments 54 and 56 and the center segment 52. In doing so, the skip turns 60 and 62 provide separation between the electrically active and inactive filament segments during operation.
The filament wire of the present invention has a typical diameter of 0.002 inch, suitable for a typical lamp current of 0.5 amps. The primary turns of the filament have a typical diameter of 0.013 inch and the secondary turns of the filament have a typical diameter of 0.059 inch.
The end segments S4 and 56, may have the same or different number of secondary turns per inch as the center segment of the filament.
A double-ended, tubular incandescent lamp capsule incorporating the filament 50 of the present invention is shown in FIG. 3. The filament 50 is mechanically supported within a double-ended tubular lamp envelope 80, typically guartz. The envelope 80 and the filament 50 share a common central axis 82. The coiled coil configuration of the filament 50 offers structural stability for accurate self centering and self support.
92-1-OlS 2 I n (~ 7 ~ 8 The lamp envelope 80 includes the following sections: a central section 84, preferably two transition sections 86 and 88, connected to opposite ends of the central section 84, two filament support sections 90 and 92, connected to transition sections 86 and 88, respectively, and two press seal sections 94 and 96, located at opposite ends of the lamp envelope.
The central section B4 is preferably ellipsoidal in shape and includes an infrared reflective coating on the outer surface. Techniques for application of infrared reflective coatings are known in the art.
The central section 84 is geometrically shaped to optically optimize reflected infrared light rays onto the electrically active center segment 52 of the filament 50, for energy conservation.
The transition sections 86 and 88, which surround the filament skip turns 60 and 62, have a constant diameter and have an inside diameter slightly larger than the outside diameter of the skip turns such that a positive clearance exists between the filament S0 and envelope 80 in the transition sections 86 and 88.
This clearance is provided to prevent any deleterious interaction between the active portion of the filament 50 (center segment 52) and the lamp envelope 80 during lamp operation. ~ithin the transition sections 86 and 88, the filament 50 transitions from active to inactive through the sXip turns 60 and 62 due to the presence of the retained mandrels (not shown) in the end segments 54 and 56.
92-1-015 ~I n ~ 7~ 8 PATENT
The filament support sections 90 and 92 mechanically retain the filament end segments 54 and 56, respectively, serving to accurately position the filament 50 centrally within the central section 84.
The inside surfaces 97 and 98 of the filament support sections 90 and 92 contact the filament end segments 54 and 56, respectively. Because the end segments 54 and 56 are electrically inactive, no harmful interaction between the filament 50 and guartz lamp envelope occurs.
A "tacking" process, which shrinks the filament support sections 90 and 92 around the end segments 54 and 56, respectively, is used to create an intimate locking fit, thereby securing the filament 50 in a fixed position relative to the lamp envelope 80 during the lamp making process. During such process the filament 50 is placed within the lamp envelope 80.
Then, the filament 50 is axially positioned as desired and stretched using a calibrated measurement system and other process-specific hardware. When the desired filament location and stretch are established, the exterior of the filament support sections 90 and 92 of the lamp envelope 80 are locally heated with a torch.
The filament support sections 90 and 92 then collapse around the end segments 54 and 56, respectively, and secure the filament 50 in position after cooling.
Mechanical pressure may be applied to the filament support sections 90 and 92 to aid in collapsing such sections. The tacking process is described in more detail in U.S. patent application serial no.
07/814,739, filed December 27, 1991, entitled METHODS
92-1-015 ~ I n~7~8 PATEN$
FOR MOUNTING FILAMENTS IN TuauLAR INCANDESCEN~ LAMP
CAPSULES, which is herein incorporated by reference.
The filament inlead portions 64 and 66 are connected to external leads 100 and 102 by molybdemum foil conductors 104 and 106, respectively. The foil conductors 104 and 106 pass through the press seal sections 94 and 96, respectively, at opposite ends of the lamp envelope 80. The press seal sections 94 and 96 provide a hermetic seal between the quartz lamp envelope 80 and the foil conductors 104 and 106.
Electrical power is supplied to the filament 50 through the external leads lG0 and 102.
While there have been shown and described what are at present considered the preferred embodiments of the present invention, it will be obvious to those s~illed in the art that various changes and modifications may by made herein without departing from the scope of the invention as defined by the appended claims and equivalents thereto.
SELF-SUPPORTING/S~LF-CENTERING FILAMENT
Field of the Invention This invention relates to tubular incandescent lamps and, more particularly, to a self-supporting, self-centering filament in a double-ended lamp capsule.
Backqround of the Invention Tubular incandescent halogen lamps include a helical filament axially mounted within a quartz lamp envelope. Filament supports attached to the filament support and center the filament within the lamp envelope. The ends of the lamp envelope are hermetically sealed, typically by press sealing.
Molybdenum foils electrically connect the filament through the seals to external electrical leads. The interior of the lamp envelope is typically filled with an inert gas and one or more halogen compounds.
It is important to center the filament within the lamp envelope to prevent undesired interactions between the filament and the walls of the lamp envelope. In addition, it is well known that for proper lamp performance, the spacing between coils of the filament must be precisely controlled. This is important because a slight change in filament length significantly changes the operating temperature of the filament. Any change in filament temperature will ., 92-1-015 ~1 n ~ 7 ~ 8 PATENT
have a dramatic effect on lamp performance and life.
In one particular lamp type, filament location i8 even more critical. This type of lamp is known as an infrared conserving lamp, which has a wavelength selective filter coating applied to a surface of the lamp envelope. A central region of the lamp envelope adjacent to the filament typically has a geometrically shaped section, such as an ellipsoid. The selective filter coating transmits visible radiation and reflects infrared radiation back to the filament. The reflected infrared radiation can significantly reduce the electrical power consumption of the lamp. In order to gain maximum benefit from the reflected infrared radiation, the filament must be very precisely centered on the axis of the lamp envelope.
Also, in order for the filament to perform at its design temperature, the filament length must be precisely controlled.
An important component of the tubular incandescent lamp capsule described above is the filament support used to support and center each end of the filament and to conduct electrical energy to the filament.
Filament supports for tu~ular incandescent lamps are disclosed in U.S. Patent No. 4,942,331 issued July 17, lg90 to Bergman et al; U.S. Patent No. 4,510,416 issued April 9, 1985 to Meade et al and U, S. Patent No. 4,959,585 issued September 25, 1990 to Hoegler et al. Filament supports are also disclosed in pending application Serial No. 07/815,004 filed December 27, 1991 and in pending application Serial No. 07/815,089 filed December 27, 1991. Factors involved in the 92-1-015 2 1 n~7~8 PAT~NT
design of filament supports include the requirement for easy insertion in a tubular lamp envelope, which may vary in inside diameter from lamp to lamp, the requirement for accurate centering of the filament over the life of the lamp and the requirement to maintain the filament at a predetermined length throughout the life of the lamp.
It is a general object of the present invention to provide improved tubular incandescent lamp capsules.
It is ano~her object of the present invention to provide a filament which exhibits accurate and stable self centering within a tubular incandescent lamp capsule.
It is a further object of the invention to provide a filament which is self supporting within a tubular incandescent lamp capsule.
It is yet another object of the present invention to provide filaments for tubular incandescent lamp capsules which are easy to manufacture and which are low in cost.
SummarY of the Invention According to the present invention, these and other objects and advantages are achieved in a self-supporting/self-centering filament for mounting in a double-ended lamp envelope. The filament comprises an active center segment, two inactive end segments, and two sXip turns. The two end segments contact an inner surface of the lamp envelope. The skip turns interconnect each end segment and the center segment, each skip turn providing axial spacing between the 92-1-015 ~ 1 n~7~8 center segment and the respective end segment. The end se~ments, the center segment and the skip turns have a coiled coil configuration and have a common central axis. In a preferred embodiment of the present invention, the end segments are coiled around a mandrel and the filament comprises a single length of wire.
According to another aspect of the invention, there is provided a lamp capsule comprising a light-transmissive lamp envelope including seals at opposite ends thereof, and having a central axis. The lamp capsule additionally comprises a coiled coil filament within the envelope having two inactive end segments, an active central segment, and skip turns interconnecting the end segments and the central segment. An inner surface of the lamp envelope contacts the end segments for retaining the filament within the lamp envelope such that the filament is centered within the lamp envelope.
In a preferred embodiment of the present invention, the lamp capsule further comprises foil conductors which pass through the seals and connect opposite ends of the filament to external leads. The lamp envelope further includes a central section having an infrared reflective coating thereon, transition sections located on either side of the central section, and parent tu~ing sections located between the transition sections and the seals. The filament central segment is located within the en~elope central section. The filament skip turns are located within the envelope transition sections. An inner surface of each parent 92-1-015 2 ~ 7 ~ 8 PATENT
tubing section contacts respective filament end segments for retaining the filament within the lamp envelope.
3rief Description of the Drawinqs For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the accompanying drawings which are incorporated herein by reference and in which:
FIG. 1 shows a tubular incandescent lamp capsule in accordance with the prior art;
FIG. 2 shows a filament of the present invention;
and FIG. 3 shows a tubular incandescent lamp capsule of the present invention incorporating the filament of FIG. 2.
Descri~tion of the Prior Art : A tubular incandescent lamp capsule in accordance with the prior art is shown in FIG. 1. A helically coiled filament 10 is mounted within a tubular lamp envelope 12. The filament 10 is supported at each end by filament supports 14 and 16. The filament supports 14 and 16 center the filament 10 on a central axis 20 of lamp envelope 12. Filament support 14 is electrically connected to an external lead 22 by a molybdenum foil conductor 24 which passes through a seal 26. Filament support 16 is electrically connected to an external lead 30 by a molybdenum foil conductor 32 which passes through a seal 34. Seals 26 92-1-015 ?1 n~ PATENT
and 34 hermetically seal the lamp envelope 12. An infrared reflective coating 36 is applied to the outside surface of the lamp envelope 12. Helical portions of filament supports 14 and 16 engage the inner surface of lamp envelope 12 and center filament 10 on axis 20. The filament supports 14 and 16 may be made from moly~denum and the filament 10 is made from tungsten. The filament supports 14 and 16 are welded to the filament 10.
Detailed Description of the Invention A filament in accordance with the present invention is shown in FIG. 2. A filament S0 has a "coiled coil" configuration (described below) with three coaxial segments: a center segment 52 and two end segments 54 and 56. The filament 50 has a central axis 58 along which the three segments are coaxially located. The center segment 52 is attached to end segments 54 and 56 through skip turns 60 and 62, respectively. Inlead portions 64 and 66 are located at opposite ends of the filament 50 and are connected to the end segments 54 and 56, respectively.
The "coiled coil" configuration of the filament 50, as will be appreciated by those skilled in the art, is so called because the filament preferably includes a single length of electrically conductive wire, such as tungsten, which is first wound in a helix about a first molybdenum mandrel. The resulting tungsten wire helix and molybdenum mandrel structure is then helically coiled about a pin, or second mandrel. The pin is preferably made of steel, 92-1-015 ~l n ~ 7 ~ 8 PATENT
but other materials are suitable. The pin i8 thereafter retracted from the structure leaving the first molybdenum mandrel in place with the tungsten wire wound helically therearound. The remaining structure is then chemically treated, preferably with an acid, to selectively remove (dissolve) portions of the first molybdenum mandrel. Portions of the filament are masked with an acid resistant coating such as wax, during the procedure, for protecting sections of the mandrel from the acid so that such protected sections of the mandrel remain in place after the process. This process yields a tungsten wire in the form of a double helically wound structure known as a "coiled coil" filament. Such a coiled coil configuration exhibits excellent self-centering and self-supporting characteristics.
During operation in an incandescent lamp, portions of the filament which surround remaining sections of the mandrel are electrically inactive. In other words, only the filament portions which surround removed sections of the mandrel are electrically active and will reach incandescence. In a preferred embodiment of the present invention, only the center segment of the filament is electrically active and reaches incandescence during operation. The end segments of the filament surround remaining sections of the mandrel and are electrically inactive during operation.
The skip turns 60 and 62 are formed by a short length of the filament, preferably within the range of lmm to 3mm in length, having a reduced number of ~`
92-1-0~5 ?,1 n ~ 7 'I ~ PATENT
_ ~ _ secondary turns per inch (TPI) in relation to the secondary Tpr of the other filament segments, thus, producing a gap between the segments. The s~ip turns readily define the three filament segments and aid in the mandrel section removal process. In addition, the skip turns provide accurate axial filament segment positioning within a double-ended envelope by providing axial spacing between the end segments 54 and 56 and the center segment 52. In doing so, the skip turns 60 and 62 provide separation between the electrically active and inactive filament segments during operation.
The filament wire of the present invention has a typical diameter of 0.002 inch, suitable for a typical lamp current of 0.5 amps. The primary turns of the filament have a typical diameter of 0.013 inch and the secondary turns of the filament have a typical diameter of 0.059 inch.
The end segments S4 and 56, may have the same or different number of secondary turns per inch as the center segment of the filament.
A double-ended, tubular incandescent lamp capsule incorporating the filament 50 of the present invention is shown in FIG. 3. The filament 50 is mechanically supported within a double-ended tubular lamp envelope 80, typically guartz. The envelope 80 and the filament 50 share a common central axis 82. The coiled coil configuration of the filament 50 offers structural stability for accurate self centering and self support.
92-1-OlS 2 I n (~ 7 ~ 8 The lamp envelope 80 includes the following sections: a central section 84, preferably two transition sections 86 and 88, connected to opposite ends of the central section 84, two filament support sections 90 and 92, connected to transition sections 86 and 88, respectively, and two press seal sections 94 and 96, located at opposite ends of the lamp envelope.
The central section B4 is preferably ellipsoidal in shape and includes an infrared reflective coating on the outer surface. Techniques for application of infrared reflective coatings are known in the art.
The central section 84 is geometrically shaped to optically optimize reflected infrared light rays onto the electrically active center segment 52 of the filament 50, for energy conservation.
The transition sections 86 and 88, which surround the filament skip turns 60 and 62, have a constant diameter and have an inside diameter slightly larger than the outside diameter of the skip turns such that a positive clearance exists between the filament S0 and envelope 80 in the transition sections 86 and 88.
This clearance is provided to prevent any deleterious interaction between the active portion of the filament 50 (center segment 52) and the lamp envelope 80 during lamp operation. ~ithin the transition sections 86 and 88, the filament 50 transitions from active to inactive through the sXip turns 60 and 62 due to the presence of the retained mandrels (not shown) in the end segments 54 and 56.
92-1-015 ~I n ~ 7~ 8 PATENT
The filament support sections 90 and 92 mechanically retain the filament end segments 54 and 56, respectively, serving to accurately position the filament 50 centrally within the central section 84.
The inside surfaces 97 and 98 of the filament support sections 90 and 92 contact the filament end segments 54 and 56, respectively. Because the end segments 54 and 56 are electrically inactive, no harmful interaction between the filament 50 and guartz lamp envelope occurs.
A "tacking" process, which shrinks the filament support sections 90 and 92 around the end segments 54 and 56, respectively, is used to create an intimate locking fit, thereby securing the filament 50 in a fixed position relative to the lamp envelope 80 during the lamp making process. During such process the filament 50 is placed within the lamp envelope 80.
Then, the filament 50 is axially positioned as desired and stretched using a calibrated measurement system and other process-specific hardware. When the desired filament location and stretch are established, the exterior of the filament support sections 90 and 92 of the lamp envelope 80 are locally heated with a torch.
The filament support sections 90 and 92 then collapse around the end segments 54 and 56, respectively, and secure the filament 50 in position after cooling.
Mechanical pressure may be applied to the filament support sections 90 and 92 to aid in collapsing such sections. The tacking process is described in more detail in U.S. patent application serial no.
07/814,739, filed December 27, 1991, entitled METHODS
92-1-015 ~ I n~7~8 PATEN$
FOR MOUNTING FILAMENTS IN TuauLAR INCANDESCEN~ LAMP
CAPSULES, which is herein incorporated by reference.
The filament inlead portions 64 and 66 are connected to external leads 100 and 102 by molybdemum foil conductors 104 and 106, respectively. The foil conductors 104 and 106 pass through the press seal sections 94 and 96, respectively, at opposite ends of the lamp envelope 80. The press seal sections 94 and 96 provide a hermetic seal between the quartz lamp envelope 80 and the foil conductors 104 and 106.
Electrical power is supplied to the filament 50 through the external leads lG0 and 102.
While there have been shown and described what are at present considered the preferred embodiments of the present invention, it will be obvious to those s~illed in the art that various changes and modifications may by made herein without departing from the scope of the invention as defined by the appended claims and equivalents thereto.
Claims (11)
1. A self-supporting/self-centering filament for mounting in a double-ended lamp envelope, comprising:
an active center segment;
two inactive end segments for contacting an inner surface of the lamp envelope; and a skip turn interconnecting each end segment and the center segment, each skip turn providing axial spacing between the center segment and the respective end segment;
wherein the end segments, the center segment and the skip turns have a coiled coil configuration and have a common central axis.
an active center segment;
two inactive end segments for contacting an inner surface of the lamp envelope; and a skip turn interconnecting each end segment and the center segment, each skip turn providing axial spacing between the center segment and the respective end segment;
wherein the end segments, the center segment and the skip turns have a coiled coil configuration and have a common central axis.
2. A filament as defined in claim 1 wherein the end segments are coiled around a mandrel.
3. A filament as defined in claim 2 wherein the filament comprises a single length of wire.
4. A filament as defined in claim 2 wherein the filament further comprises two inlead portions attached to the end segments.
5. A filament as defined in claim 1 wherein the coiled coil configuration includes primary and secondary turns and wherein the skip turns include less secondary turns per inch than the end segments and center segment.
6. A lamp capsule comprising:
a light-transmissive lamp envelope including seals at opposite ends thereof, and having a central axis;
a coiled coil filament within the lamp envelope, the filament including two inactive end segments, an active central segment, and skip turns interconnecting the end segments and the central segment, an inner surface of the lamp envelope contacting the end segments for retaining the filament within the lamp envelope such that the filament is substantially centered within the lamp envelope; and means for coupling electrical energy through the seals to the filament.
a light-transmissive lamp envelope including seals at opposite ends thereof, and having a central axis;
a coiled coil filament within the lamp envelope, the filament including two inactive end segments, an active central segment, and skip turns interconnecting the end segments and the central segment, an inner surface of the lamp envelope contacting the end segments for retaining the filament within the lamp envelope such that the filament is substantially centered within the lamp envelope; and means for coupling electrical energy through the seals to the filament.
7. A lamp capsule as defined in claim 6 wherein the coupling means includes foil conductors which pass through the seals and connect opposite ends of the filament to external leads.
8. A lamp capsule as defined in claim 7 wherein the central segment is the only electrically active segment of the filament.
9. A lamp capsule as defined in claim 6 wherein the lamp envelope includes:
a central section having an infrared reflective coating thereon and within which the filament central segment is located;
transition sections located on either end of the central section within which the filament skip turns are located; and filament support sections located between the transition sections and the seals, and having an inner surface contacting the filament end segments for retaining the filament within the lamp envelope.
a central section having an infrared reflective coating thereon and within which the filament central segment is located;
transition sections located on either end of the central section within which the filament skip turns are located; and filament support sections located between the transition sections and the seals, and having an inner surface contacting the filament end segments for retaining the filament within the lamp envelope.
10. A lamp capsule as defined in claim 8 wherein the lamp envelope includes:
a central section having an infrared reflective coating thereon and within which the filament central segment is located;
transition sections located on either end of the central section within which the filament skip turns are located; and filament support sections located between the transition sections and the seals, and having an inner surface contacting the filament end segments for retaining the filament within the lamp envelope.
a central section having an infrared reflective coating thereon and within which the filament central segment is located;
transition sections located on either end of the central section within which the filament skip turns are located; and filament support sections located between the transition sections and the seals, and having an inner surface contacting the filament end segments for retaining the filament within the lamp envelope.
11. Each and every novel feature or novel combination of features herein disclosed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US96550392A | 1992-10-23 | 1992-10-23 | |
| US7/965,503 | 1992-10-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2108748A1 true CA2108748A1 (en) | 1994-04-24 |
Family
ID=25510065
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2108748 Abandoned CA2108748A1 (en) | 1992-10-23 | 1993-10-19 | Self-supporting/self-centering filament |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0594183B1 (en) |
| CA (1) | CA2108748A1 (en) |
| DE (1) | DE69317726T2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5506471A (en) * | 1994-06-06 | 1996-04-09 | General Electric Company | Low glare infrared light source |
| JP2002026366A (en) | 2000-07-11 | 2002-01-25 | Sony Corp | Semiconductor device |
| US6465761B2 (en) | 2000-07-24 | 2002-10-15 | Asm America, Inc. | Heat lamps for zone heating |
| US6818864B2 (en) | 2002-08-09 | 2004-11-16 | Asm America, Inc. | LED heat lamp arrays for CVD heating |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL8004030A (en) * | 1980-07-14 | 1982-02-16 | Philips Nv | ELECTRIC LIGHT BULB. |
| NL8702516A (en) * | 1986-12-22 | 1988-07-18 | Gen Electric | BULB WITH DOUBLE SPIRALIZED BULB. |
| US4916353A (en) * | 1989-02-28 | 1990-04-10 | General Electric Company | Incandescent lamp utilizing cylindrical transparent heat mirror |
| US4942331A (en) * | 1989-05-09 | 1990-07-17 | General Electric Company | Filament alignment spud for incandescent lamps |
-
1993
- 1993-10-19 CA CA 2108748 patent/CA2108748A1/en not_active Abandoned
- 1993-10-21 DE DE1993617726 patent/DE69317726T2/en not_active Expired - Fee Related
- 1993-10-21 EP EP19930117103 patent/EP0594183B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE69317726T2 (en) | 1998-09-10 |
| EP0594183A1 (en) | 1994-04-27 |
| DE69317726D1 (en) | 1998-05-07 |
| EP0594183B1 (en) | 1998-04-01 |
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| Date | Code | Title | Description |
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| FZDE | Dead |