Patent EP0272089A2 successfully refreshed from Google Patents.
EP0272089A2
Expired / Lapsed
EP
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Monitoring the heating of microwave-heated bodies
Assignee: Rio Tinto Alcan International Ltd
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Filing: 1987-12-15
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Granted: —
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Expires: 2007-12-15
Abstract
Abstract For determining the attainment of a desired heated condition, referred to as "doneness", of a body of food or other material heated in a microwave oven, there is provided a device including an indicator that changes appearance at a predetermined temperature, mounted on an outwardly-facing major surface of a thin-gauge metal element (22) which is disposed in the oven so as to receive heat from the body. The metal element may be mounted on the lid (18) or other wall of a container (10) holding the body (11) in the oven (not shown); the lid may be microwave-transmissive and may hold the metal element (22) spaced above the body (11). The indicator may include a multilayer structure (28) which has the property of undergoing an observable change of appearance upon attaining a predetermined elevated temperature. In use, the device is placed in a microwave oven together with the body (11) and is observed visually, for detection of the change of appearance, which occurs when the indicator reaches a temperature corresponding to adequate doneness of the body (11).
Inventors
- 👤 Richard Mackay Keefer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 22:32
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/64; B; B65; B65D; B65D81/00; B65D81/34; B65D81/3446; G; G01; G01K; G01K11/00; G01K3/00; G01K3/02; G01K3/04
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
164 words
A system for indicating the doneness of a body of material heated by microwave energy, said system comprising a thin electrically conductive metal element having first and second opposed extended surfaces; indicator means disposed on the first surface of the element for producing a visually observable change of appearance upon being heated to a predetermined elevated temperature or upon being maintained at such temperature for a predetermined time; and means for supporting the element in substantially fixed relation to the body, when the body is disposed in a microwave oven for heating by microwave energy, such that the element is also disposed in the oven with the indicator means positioned to be externally visible, and such that the element receives heat from the body by conduction and/or radiation as the body is heated by microwave energy; the dimensions of the element and the disposition of the indicator means thereon being such as substantially to shield the indicator means from temperature-elevating irradiation by mircrowave energy.
Claim 2
Independent Claim
164 words
A system for indicating the doneness of a body of material heated by microwave energy, said system comprising a thin electrically conductive metal element having first and second opposed extended surfaces; indicator means disposed on the first surface of the element for producing a visually observable change of appearance upon being heated to a predetermined elevated temperature or upon being maintained at such temperature for a predetermined time; and means for supporting the element in substantially fixed relation to the body, when the body is disposed in a microwave oven for heating by microwave energy, such that the element is also disposed in the oven with the indicator means positioned to be externally visible, and such that the element receives heat from the body by conduction and/or radiation as the body is heated by microwave energy; the dimensions of the element and the disposition of the indicator means thereon being such as substantially to shield the indicator means from temperature-elevating irradiation by mircrowave energy.
Claim 3
Dependent Claim
21 words
A system as claimed in claim 1, wherein said indicator means undergoes a physical change upon attaining said predetermined elevated temperature.
Claim 4
Dependent Claim
26 words
A system as claimed in claim 2, wherein said indicator means includes a substance that undergoes a change of state upon attaining said predetermined elevated temperature.
Claim 5
Dependent Claim
81 words
A system as claimed in claim 3, wherein said indicator means comprises a first layer characterised by a visually distinctive colour, applied to the first surface of the element, and a second layer outwardly covering the first layer and comprising said substance, said second layer being substantially opaque at temper atures below said predetermined temperature so as to mask said first layer, but becoming substantially transparent, so as to reveal said first layer, when said substance undergoes said change of state.
Claim 6
Dependent Claim
20 words
A system as claimed in claim 4, wherein said second layer comprises a substance that melts at said predetermined temperature.
Claim 7
Dependent Claim
41 words
A system as claimed in claim 5, wherein said second layer further comprises a substantially opaque porous web, extending over said first layer and in intimate contact with said substance, that becomes substantially transparent when wetted by melting of said substance.
Claim 8
Dependent Claim
30 words
A system as claimed in claim 1, wherein said indicator means comprises a layer of a substance that undergoes a visually observable chemical change upon attaining said predetermined elevated temperature.
Claim 9
Independent Claim
22 words
A system as claimed in any one of the preceding claims, wherein said second surface of said element is a heat-reflective surface.
Claim 10
Independent Claim
22 words
A system as claimed in any one of the preceding claims, wherein said second surface of said element bears a heat-absorptive coating.
Claim 11
Independent Claim
54 words
A system as claimed in any one of the preceding claims, wherein said supporting means includes a sheet-like dielectric member transmissive to microwave energy and having opposed major surfaces respectively facing inwardly toward and outwardly away from said body, and wherein said element is secured to the outwardly facing surface of said dielectric member.
Claim 12
Dependent Claim
15 words
A system as claimed in claim 10, wherein said element is a metal foil member.
Claim 13
Independent Claim
40 words
A system as claimed in any on of the preceding claims, wherein said supporting means comprises a container having a wall structure for at least partially enclosing said body, and wh rein said element is included in said wall structure.
Claim 14
Dependent Claim
49 words
A system as claimed in claim 12, wherein said wall structure includes a lid for the container, said lid comprising a member of dielectric material transmissive to microwave energy, and having inner and outer major surfaces, and wherein said element is disposed at the outer surface of said lid.
Claim 15
Dependent Claim
23 words
A system as claimed in claim 13, wherein said element is a metal foil island bonded to the outer surface of said lid.
Claim 16
Dependent Claim
26 words
A system as claimed in claim 14, further including a body of material to be heated by microwave energy, said body being disposed in said container.
Claim 17
Dependent Claim
15 words
A system as claimed in claim 15, wherein said lid is spaced from said body.
Claim 18
Independent Claim
74 words
A system as claimed in either one of claims 15 or 16, wherein said container, including said element, and said body co-operatively define a microwave field pattern that determines the rapidity of heating of various regions of said body, such that at least one region of said body heats more slowly than another region of said body, and wherein said element is disposed on said lid in directly overlying relation to said one region.
Claim 19
Independent Claim
169 words
A method of determining the doneness of a body of material heated by microwave energy, said method comprising placing, in a microwave oven for heating, said body together with a thin electrically conductive metal element having first and second opposed extended surfaces and bearing on its first surface indicator means for producing a visually observable change of appearance upon being heated to a predetermined elevated temperature or maintained at such temperature for a predetermined time, said element being supported in the oven, in substantially fixed relation to the body with the indicator means positioned to be externally visible, such that the element receives heat from the body by conduction and/or radiation when the body is heated, the dimensions of the element and the disposition of the indicator means thereon being such as substantially to shield the indicator means from temperature-elevating irradiation by microwave energy; and, while energising the oven to heat the body with microwave energy, observing the indicator means to detect the occurrence of said change of appearance.
Claim 20
Independent Claim
169 words
A method of determining the doneness of a body of material heated by microwave energy, said method comprising placing, in a microwave oven for heating, said body together with a thin electrically conductive metal element having first and second opposed extended surfaces and bearing on its first surface indicator means for producing a visually observable change of appearance upon being heated to a predetermined elevated temperature or maintained at such temperature for a predetermined time, said element being supported in the oven, in substantially fixed relation to the body with the indicator means positioned to be externally visible, such that the element receives heat from the body by conduction and/or radiation when the body is heated, the dimensions of the element and the disposition of the indicator means thereon being such as substantially to shield the indicator means from temperature-elevating irradiation by microwave energy; and, while energising the oven to heat the body with microwave energy, observing the indicator means to detect the occurrence of said change of appearance.
Claim 21
Dependent Claim
23 words
A method according to claim 18, further including the step of terminating the heating of the body when said change of appearance occurs.
References Cited (Backward Citations)
No citation records indexed.
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