US3725698A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Moisture barrier for sealed beam headlamp construction
Assignee: Motors Liquidation Co
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Filing: 1971-03-02
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Granted: 1973-04-03
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Expires: 1991-03-02
Abstract
Abstract A sealed beam headlamp wherein the mating areas between component parts are structurally and hermetically joined by a plastic cement overlaid by a metallic moisture barrier, the latter establishing a tortuous moisture flow path of minimal cross section through the cement thereby reducing the rate of moisture diffusion into the lamp envelope and minimizing filament erosion due to ''''water cycle''''.
Inventors
- 👤 G Craig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:11
CPC Classifications
H; H01; H01K; H01K1/00; H01K1/28; F; F21; F21S; F21S45/00; F21S45/50; H01J; H01J5/00; H01J5/20; H01J5/22; H01J5/24; H01J2893/00; H01J2893/0033; H01J2893/0037; H01J2893/0038
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
123 words
A sealed beam lighting unit, comprising: a lens; a reflector; a light source assembly including a filament susceptible to premature burnout occasioned by water cycle erosion promoted by exposure to moisture; a first cement joint joining the lens and the reflector to define a lamp envelope; a second cement joint mounting the light source assembly on the reflector with the filament being positioned within said lamp envelope, said cement joints being formed of a water pervious material which creates a moisture diffusion path between atmosphere and the lamp envelope; and continuous circumferential metallic moisture barriers intimately contacting and overlying the cement joints to limit the entrant moisture diffusion paths therethrough thereby reducing the moisture diffusion rate and water cycle erosion of the filament.
Claim 2
Dependent Claim
124 words
A sealed beam lighting unit, comprising: a reflector member; a lens member, said members having mating peripheral flanges and interior surfaces defining a lamp envelope and being formed of moisture impervious materials; a filament carried in said lamp envelope having a shortened life caused by water cycle erosion promoted by moisture in said envelope; a plastic cement between said members radially outwardly terminating with a peripheral bead, said cement forming a sealed joint and establishing an entrant diffusion path through said bead for moisture entry into said lamp envelope; and a continuous circumferential metallic foil intimately surrounding said joints and extruding said bead at the joint into an elongated tortuous path along said flanges thereby reducing the moisture diffusion rate and prolonging filament life.
Claim 3
Dependent Claim
113 words
A sealed beam lighting unit comprising: a reflector; a lens, said lens and said reflector having interior surfaces establishing a lamp envelope therebetween; a light source assembly including a filament carried in said lamp envelope, said filament being susceptible to premature burnout due to water cycle erosion promoted by moisture in said lamp envelope; a plastic cement hermetically joining the lens to the reflector, said cement establishing a moisture diffusion path through which moisture can diffuse into said lamp envelope; and circumferentially continuous barrier means formed of a moisture impervious material intimately surrounding and exteriorally overlying said cement for reducing the entrant moisture path into the envelope thereby diminishing said water cycle erosion.
References Cited (Backward Citations)
US2314735A
Cited
US3010045A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |