US4934829A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of determining resonant lengths of microwave shielding material
Assignee: General Mills Marketing Inc
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Filing: 1989-04-10
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Granted: 1990-06-19
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Expires: 2009-04-10
Abstract
Abstract A food container for use in a microwave oven is disclosed. The container contains a plurality of food substances, and employs a metal shield to shield at least one of the food substances from microwave radiation. Arcing and other problems associated with the use of metal shielding are avoided by proper selection of the geometry of the metal shield. The metal shield is preferably looped in a manner which provides some electrical inductance, and the ends of the metal shield are overlapped and separated by a dielectric material to provide some electrical capacitance. The geometry of the shield is selected so that the inductance and the capacitance in effect form a "tuned circuit" which minimizes problems associated with resonance and which eliminates arcing.
Inventors
- 👤 Dan J. Wendt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:33
CPC Classifications
B; B65; B65D; B65D81/00; B65D81/34; B65D81/3446; B65D81/3453; B65D2581/00; B65D2581/34; B65D2581/3401; B65D2581/3429; B65D2581/3431; B65D2581/3437; B65D2581/3439; B65D2581/344; B65D2581/3441; B65D2581/3471; B65D2581/3472; B65D2581/3486; B65D2581/3489
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
79 words
A method of determining resonant lengths of microwave shielding material, comprising the steps of: constructing a laminate test strip including a length of conductive shielding material, a strip of lossy material, and a strip of temperature indicating material; and, irradiating the laminate test strip with microwave radiation for a predetermined period of time to determine the heating response of the laminate test strip, whereby the amount of heating provides an indication of a resonant length of said test strip.
Claim 2
Independent Claim
79 words
A method of determining resonant lengths of microwave shielding material, comprising the steps of: constructing a laminate test strip including a length of conductive shielding material, a strip of lossy material, and a strip of temperature indicating material; and, irradiating the laminate test strip with microwave radiation for a predetermined period of time to determine the heating response of the laminate test strip, whereby the amount of heating provides an indication of a resonant length of said test strip.
Claim 3
Dependent Claim
21 words
The method according to claim 1, further comprising the step of: selecting cellulose acetate for the strip of temperature indicating material.
Claim 4
Independent Claim
105 words
A method of determining resonant lengths of microwave shielding material, comprising the steps of: constructing a plurality of laminate test strips having a plurality of different lengths of conductive shielding material, each length of conductive shielding material being bonded to a strip of lossy material and a strip of a temperature sensitive indicator; irradiating the laminate test strips with microwave radiation for a predetermined period of time; evaluating relative temperature indications of the temperature sensitive indicators of the strips to determine resonant lengths of conductile shielding material which provide the maximum relative temperature indication of the amount of heating of the irradiated laminated test strips.
Claim 5
Independent Claim
105 words
A method of determining resonant lengths of microwave shielding material, comprising the steps of: constructing a plurality of laminate test strips having a plurality of different lengths of conductive shielding material, each length of conductive shielding material being bonded to a strip of lossy material and a strip of a temperature sensitive indicator; irradiating the laminate test strips with microwave radiation for a predetermined period of time; evaluating relative temperature indications of the temperature sensitive indicators of the strips to determine resonant lengths of conductile shielding material which provide the maximum relative temperature indication of the amount of heating of the irradiated laminated test strips.
Claim 6
Dependent Claim
29 words
The method according to claim 3, further comprising the step of: determining resonant lengths of conductive shielding material by measuring the lengths which provide the maximum relative temperature indication.
Claim 7
Dependent Claim
37 words
The method according to claim 4, further comprising the step of: constructing a shielded food container for heating food in a microwave oven by avoiding resonant lengths in conductive shielding material used to shield the food container.
Claim 8
Dependent Claim
22 words
The method according to claim 3, further comprising the step of: selecting cellulose acetate for the strip of a temperature sensitive indicator.
Claim 9
Dependent Claim
24 words
The method according to claim 6, wherein: the lengths of conductive shielding material have a width that is substantially less than a half wavelength.
Claim 10
Dependent Claim
18 words
The method according to claim 3, wherein: the lengths of conductive shielding material have a substantially uniform width.
Claim 11
Dependent Claim
24 words
The method according to claim 3, wherein: the lengths of conductive shielding material have a width that is substantially less than a half wavelength.
Claim 12
Dependent Claim
13 words
The method according to claim 9, wherein: the conductive shielding material is aluminum.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-18 | 1993-12-18 | 1994-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-18 | 1997-12-18 | 1998-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-18 | 2001-12-18 | 2002-06-19 | $7700.00 | Window Closed / Lapsed |