US3898977A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid crystal door window shutter arrangement for self-cleaning cooking oven
Assignee: White Westinghouse Corp
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Filing: 1974-01-28
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Granted: 1975-08-12
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Expires: 1994-01-28
Abstract
Abstract A pyrolytic self-cleaning oven door is provided having a window comprising a liquid crystal material, disposed between an inner surface and an outer surface of the window. The liquid crystal serves as an optical shutter. The shutter arrangement affects a change in light transmission therethrough in accordance with the temperature in the oven. The shutter is in a substantially opaque state when the oven is at a pyrolytic self-cleaning temperature and in a substantially transparent state, when the oven is at a temperature below a pyrolytic self-cleaning range.
Inventors
- 👤 Robert Draper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:28
CPC Classifications
F; F24; F24C; F24C15/00; F24C15/02; F24C15/04
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
99 words
In a pyrolytic self-cleaning cooking oven, said oven having an opening thereinto; a door for closing said opening, said door having a window therein; means including a liquid crystal material associated with said window for providing an optical shutter operative at elevated temperatures in said oven corresponding to a heat-cleaning temperature range; and said means permitting transmission of light sufficient for viewing through said window when the temperature of said oven is below the heat cleaning range and excluding transmission of light sufficient for viewing through said window when the temperature of said oven is in a heat-cleaning range.
Claim 2
Dependent Claim
99 words
In a pyrolytic self-cleaning cooking oven, said oven having an opening thereinto; a door for closing said opening, said door having a window therein; means including a liquid crystal material associated with said window for providing an optical shutter operative at elevated temperatures in said oven corresponding to a heat-cleaning temperature range; and said means permitting transmission of light sufficient for viewing through said window when the temperature of said oven is below the heat cleaning range and excluding transmission of light sufficient for viewing through said window when the temperature of said oven is in a heat-cleaning range.
Claim 3
Dependent Claim
49 words
In the oven of claim 1 wherein: said liquid crystal material comprises a cholesteric liquid crystal; and said means includes two mutually opposed linearly polarizing light filters with the polarity of each being generally perpendicular with respect to the other, and wherein said liquid crystal material is disposed therebetween.
Claim 4
Dependent Claim
56 words
In the oven of claim 2 wherein: said liquid crystal material is of a character that it responds to temperatures transmitted to it during normal cooking in said oven to rotate light passing therethrough; and to temperatures transmitted to it during pyrolytic cleaning operations of said oven, to provide substantially negligible rotation of said light therethrough.
Claim 5
Dependent Claim
23 words
In the oven of claim 1 wherein: said liquid crystal material comprises a nematic liquid crystal material confined between spaced apart electrode layers.
Claim 6
Dependent Claim
82 words
In the oven of claim 4 wherein: said means for providing an optical shutter further includes: a circuit having a voltage source for serially cOnnecting said layers of said conducting material with said nematic liquid crystal material and switch means for completing said circuit, and means for moving said switch means to a closed position in response to said oven being in a heat-cleaning operation whereby said liquid crystal transforms into a turbid state preventing transmission of sufficient light for viewing therethrough.
Claim 7
Dependent Claim
32 words
In the oven of claim 5 wherein: said voltage source comprises a thermopile, a portion of which is substantially exposed to the elevated temperature of said oven to generate said voltage means.
Claim 8
Dependent Claim
96 words
In an improved open door for a pyrolytic self-cleaning oven having a window for normally viewing the interior of an oven and means for obstructing viewing therethrough during a heat-cleaning cycle and wherein the improvement comprises: said means for obstructing viewing includes a pair of opposed parallel spaced panes associated with said window and said space between said panes contains a conditionally responsive liquid crystal material of a character that responds to said oven being at heat-cleaning temperatures to alter the transmission of light through said panes in a manner to prevent viewing through said window.
Claim 9
Dependent Claim
96 words
In an improved open door for a pyrolytic self-cleaning oven having a window for normally viewing the interior of an oven and means for obstructing viewing therethrough during a heat-cleaning cycle and wherein the improvement comprises: said means for obstructing viewing includes a pair of opposed parallel spaced panes associated with said window and said space between said panes contains a conditionally responsive liquid crystal material of a character that responds to said oven being at heat-cleaning temperatures to alter the transmission of light through said panes in a manner to prevent viewing through said window.
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) | 1978-08-11 | 1979-02-10 | 1979-08-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-11 | 1983-02-10 | 1983-08-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-11 | 1987-02-10 | 1987-08-12 | $7700.00 | Window Closed / Lapsed |