Claims
- 1. A filament for an electric lamp made from tungsten wire having a predetermined amount of impurities before annealing comprising annealed tungsten wire existing after removal from a base material on which it was annealed at an elevated temperature, the annealed wire having substantially the same impurities therein as was present in the wire before annealing.
- 2. A filament as in claim 1 wherein the wire is in coil form and the material from which it was removed comprised a mandrel around which the coil was wound.
- 3. A filament as in claim 2 wherein the wire was heavily drawn prior to annealing and being wound on the mandrel.
- 4. A filament as in claim 1 wherein the base material on which the wire was annealed contained iron and the wire has less than 15 parts per million (by weight) of iron constituting one of the impurities after removal from the base material.
- 5. A filament as in claim 2 wherein the mandrel contained iron and the wire has less than 15 parts per million (by weight) of iron constituting one of the impurities after removal from the mandrel.
- 6. A tungsten wire filament for an electric lamp produced by annealing at an elevated temperature the wire having a predetermined amount of impurities therein before annealing as the wire is held on a form, the wire having substantially no additional impurities introduced into it from the material of the form.
- 7. A tungsten wire filament as in claim 6 wherein the mandrel comprised the form and the wire was wound around the mandrel prior to annealing.
- 8. A tungsten wire filament as in claim 7 wherein the mandrel material included iron.
- 9. A tungsten wire filament as in claim 1 wherein the wire contains less than 15 parts per million (by weight) after annealing.
Parent Case Info
This application is a division of our prior copending application Ser. No. 223,607, filed Feb. 4, 1972, entitled "Reduced Impurity Filament For Electric Lamps", now U.S. Pat. No. 3,812,383, granted May 24, 1974 which is in turn a continuation-in-part of our prior application Ser. No. 66,275, filed Aug. 24, 1970, now U.S. Pat. No. 3,662,789, dated May 16, 1972, entitled "Mandrel For Manufacturing Filament Coils and Method for Manufacturing Filament Coils" both of which are assigned to the same assignee.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3341917 |
Oyabu et al. |
Sep 1967 |
|
3346761 |
Ackerman |
Oct 1967 |
|
3812393 |
Koo et al. |
May 1974 |
|
Divisions (1)
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Number |
Date |
Country |
Parent |
223607 |
Feb 1972 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
66275 |
Aug 1970 |
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