US4425527A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical filters comprising pyrolyzed polyimide films and lamp
Assignee: Osram Sylvania Inc
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Filing: 1981-06-22
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Granted: 1984-01-10
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Expires: 2001-06-22
Abstract
Abstract Selective optical absorption filters which transmit infrared light and absorb or partially reflect visible light comprise thin films of partially pyrolyzed polymeric aromatic pyromellitimides. The filters are characterized by a metallic luster and maximum light transmittance above about 2 μm wavelength. A lamp is disclosed having a reflective filter disposed behind the filament to reflect visible light forward through the front portion of the lamp while transmitting infrared light rearward through the back portion of the lamp.
Inventors
- 👤 Enid K. Sichel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:29
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1067; C08G73/1071; C08G73/1075; C08G73/1082; H; H01; H01J; H01J61/00; H01J61/02; H01J61/38; H01J61/40
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
67 words
An infrared light transmissive, visible light absorptive optical filter comprising a film of the thermal decomposition product formed by heating an aromatic polymeric pyromellitimide at a temperature of between about 600° C. to about 700° C. for a period of between about 2 to 6 hours in an inert gas atmosphere, said film of thermal decomposition product characterized by maximum light transmittance above about 2 μm wavelength.
Claim 2
Dependent Claim
67 words
An infrared light transmissive, visible light absorptive optical filter comprising a film of the thermal decomposition product formed by heating an aromatic polymeric pyromellitimide at a temperature of between about 600° C. to about 700° C. for a period of between about 2 to 6 hours in an inert gas atmosphere, said film of thermal decomposition product characterized by maximum light transmittance above about 2 μm wavelength.
Claim 3
Dependent Claim
27 words
An optical filter in accordance with claim 1 wherein said polymeric polymellitimide has the repeating unit ##STR1## wherein A is selected from the group consisting of ##STR2##
Claim 4
Dependent Claim
36 words
An optical filter in accordance with claim 2 comprising a film of said thermal decomposition product of a thickness less than about 10 μm on a substrate transparent to light of wavelengths less than 5 μm.
Claim 5
Dependent Claim
17 words
An optical filter in accordance with claim 2 wherein said polymeric pyromellitimide has the repeating unit ##STR3##
Claim 6
Dependent Claim
17 words
An optical filter in accordance with claim 3 having a visible light reflectance of at least 15%.
Claim 7
Dependent Claim
111 words
In a lamp comprising an incandescent filament, a selective optical absorption filter in back of and in reflecting relationship to said filament to reflect visible light directly through the forward portion of the lamp and transmit infrared radiation, an enclosing light-transmitting envelope around said filament and said filter, the improvement wherein said selective optical absorption filter comprises a film of the thermal decomposition product formed by heating a polymeric pyromellitimide at a temperature of about 600° C. to about 700° C. for a period of about 2 to 6 hours in an inert gas atmosphere said film of thermal decomposition product characterized by maximum light transmittance above about 2 μm wavelength.
Claim 8
Dependent Claim
111 words
In a lamp comprising an incandescent filament, a selective optical absorption filter in back of and in reflecting relationship to said filament to reflect visible light directly through the forward portion of the lamp and transmit infrared radiation, an enclosing light-transmitting envelope around said filament and said filter, the improvement wherein said selective optical absorption filter comprises a film of the thermal decomposition product formed by heating a polymeric pyromellitimide at a temperature of about 600° C. to about 700° C. for a period of about 2 to 6 hours in an inert gas atmosphere said film of thermal decomposition product characterized by maximum light transmittance above about 2 μm wavelength.
Claim 9
Dependent Claim
26 words
A lamp in accordance with claim 6 wherein said polymeric pyromellitimide has the repeating unit: ##STR4## wherein A is selected from the group consisting of: ##STR5##
Claim 10
Dependent Claim
41 words
A lamp in accordance with claim 7 wherein said selective optical absorption filter comprises a film of said thermal decomposition product of thickness less than about 10 μm on a substrate transparent to light of wavelengths less than about 5 μm.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-01-09 | 1987-07-11 | 1988-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-09 | 1991-07-11 | 1992-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-09 | 1995-07-11 | 1996-01-10 | $7700.00 | Window Closed / Lapsed |