EP0348156A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Improvements relating to microwave heating
Assignee: Rio Tinto Alcan International Ltd
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Filing: 1989-06-20
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Granted: —
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Expires: 2009-06-20
Abstract
Abstract A container (10) for heating a substance, e.g. food, in a microwave oven has a bottom (12) transparent to microwave energy. The container is supported on a stand (22) that contains one or more electrically conductive plates (32) (or apertures in an electrically conductive sheet) that generate at least one mode of microwave energy of higher order than the fundamental modes. The stand (22) also serves to support the container (10) above the higher order mode generating plates (or apertures) so that the undersurface of the substance is spaced from them by a uniform predetermined distance. The arrangement has the known features of "bottom heating", i.e. taking advantage of the natural heat flow in the substance, while achieving more uniform heating of the substance by virtue of the higher order mode or modes. As an alternative to or in addition to the generation of higher order modes, the stand may embody elements that modify the microwave pattern in a manner that enhances the coupling of microwave energy into the undersurface of the substance to be heated.
Inventors
- 👤 Bryan Cobley Hewitt
- 👤 Melville Douglas Ball
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 04:39
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/64; H05B6/647; H05B6/6491; H05B6/6494; B; B65; B65D; B65D81/00; B65D81/34; B65D81/3446; B65D81/3453; B65D2581/00; B65D2581/34; B65D2581/3437; B65D2581/3439; B65D2581/344; B65D2581/3441; B65D2581/3486; B65D2581/3494
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
74 words
A stand for use with a container having at least one portion transparent to microwave energy including a bottom on which there is supported an undersurface of a substance to be heated, said stand comprising: (a) means for modifying a microwave field pattern to which said container is exposed, and (b) means for supporting the container spaced above said modifying means so that said undersurface is a predetermined distance from said field modifying means.
Claim 2
Dependent Claim
74 words
A stand for use with a container having at least one portion transparent to microwave energy including a bottom on which there is supported an undersurface of a substance to be heated, said stand comprising: (a) means for modifying a microwave field pattern to which said container is exposed, and (b) means for supporting the container spaced above said modifying means so that said undersurface is a predetermined distance from said field modifying means.
Claim 3
Dependent Claim
36 words
A stand according to claim 1, wherein the modifying means comprises means for generating a microwave field pattern having at least one mode of microwave energy of higher order than the fundamental modes of such energy.
Claim 4
Dependent Claim
35 words
A stand according to claim 2, wherein said modifying means is planar and said supporting means is dimensioned to support a flat bottom of the container lying in a plane parallel to said modifying means.
Claim 5
Dependent Claim
27 words
A stand according to claim 3, wherein said modifying means comprises at least one plate of electrically conductive material lying in a plane parallel to said bottom.
Claim 6
Dependent Claim
30 words
A stand according to claim 3, wherein said modifying means comprises an array of a plurality of plates of electrically conducting material lying in a plane parallel to said bottom.
Claim 7
Dependent Claim
30 words
A stand according to claim 3, wherein said modifying means comprises at least one aperture in a sheet of electrically conductive material lying in a plane parallel to said bottom.
Claim 8
Dependent Claim
34 words
A stand according to claim 3, wherein said modifying means comprises an array of a plurality of apertures in a sheet of electrically conductive material lying generally in a plane parallel to said bottom.
Claim 9
Dependent Claim
40 words
A stand according to claim 7, wherein at least one of said apertures is in a portion of said sheet located at a distance from said undersurface different from the distance of the remainder of said sheet from said undersurface.
Claim 10
Dependent Claim
19 words
A stand according to claim 2, wherein said modifying means comprises portions having different electrical thicknesses from one another.
Claim 11
Dependent Claim
16 words
A stand according to claim 9, wherein said portions have different physical thicknesses from one another.
Claim 12
Dependent Claim
16 words
A stand according to claim 9, wherein said portions have different dielectric constants from one another.
Claim 13
Dependent Claim
18 words
A stand according to claim 2, wherein said modifying means comprises portions having different lossinesses from one another.
Claim 14
Dependent Claim
30 words
A stand according to claim 1, wherein said container has portions reflective of microwave energy, said at least one transparent portion being principally constituted by the bottom of the container.
Claim 15
Dependent Claim
15 words
A stand according to claim 13, wherein said container has reflective side walls and lid.,
Claim 16
Dependent Claim
22 words
A stand according to claim 1, wherein the stand includes upwardly extending, conductive outer portions for shielding side walls of the container.
Claim 17
Dependent Claim
19 words
A stand according to claim 1, wherein said predetermined distance is in the range of 3 to 30 mm.
Claim 18
Dependent Claim
26 words
A stand according to claim 16, wherein the space between the modifying means and the container bottom is air and said distance is approximately 15 mm.
Claim 19
Dependent Claim
26 words
A stand according to claim 16, wherein the space between the modifying means and the container bottom is polyethylene and said distance is approximately 10 mm.
Claim 20
Dependent Claim
31 words
A stand according to claim 16, wherein the space between the modifying means and the container bottom is glass and said distance is in the range from 7 to 10 mm.
Claim 21
Dependent Claim
18 words
A stand according to claim 4, including means for spacing said electrically conductive material from an oven floor.
Claim 22
Dependent Claim
28 words
A stand according to claim 1, wherein the modifying means comprises means for enhancing the coupling of microwave energy into the undersurface of the substance to be heated.
Claim 23
Dependent Claim
48 words
A stand according to claim 21, wherein said coupling enhancement means comprises a substrate of dielectric material with an array of conductive plates covering at least the majority of the surface area of said substrate, the substrate and the plates cooperatively providing a dielectric constant greater than 10.
Claim 24
Dependent Claim
18 words
A stand according to claim 22, wherein said predetermined distance is in the range 8 to 20 mm.
Claim 25
Dependent Claim
45 words
An assembly comprising: (a) a container having at least one portion transparent to microwave energy including a bottom on which there is to be supported an undersurface of a substance to be heated, and (b) a stand according to any one of the preceding claims.
Claim 26
Dependent Claim
73 words
A cooking vessel for use in a microwave oven, said vessel comprising a bottom portion and side walls, at least the bottom portion being made of a microwave transparent material, and means for modifying a microwave field pattern to which the vessel is exposed, said means extending across said bottom portion spaced a predetermined distance beneath an upper surface of said bottom portion for supporting an undersurface of a substance to be heated.
Claim 27
Dependent Claim
73 words
A cooking vessel for use in a microwave oven, said vessel comprising a bottom portion and side walls, at least the bottom portion being made of a microwave transparent material, and means for modifying a microwave field pattern to which the vessel is exposed, said means extending across said bottom portion spaced a predetermined distance beneath an upper surface of said bottom portion for supporting an undersurface of a substance to be heated.
Claim 28
Dependent Claim
15 words
A vessel according to claim 25, wherein said distance is no less than 3 mm.
Claim 29
Dependent Claim
16 words
A vessel according to claim 26, wherein said distance is between about 3 and 10 mm.
Claim 30
Dependent Claim
78 words
A cooking vessel for use in a microwave oven, said vessel comprising a bottom portion and side walls of microwave transparent material and a metallised layer extending at least across said bottom portion, said layer having apertures therein to provide means for generating a microwave field pattern having at least one mode of microwave energy of higher order than the fundamental modes of such energy, said means being spaced from the inside bottom surface by a predetermined distance.
Claim 31
Dependent Claim
78 words
A cooking vessel for use in a microwave oven, said vessel comprising a bottom portion and side walls of microwave transparent material and a metallised layer extending at least across said bottom portion, said layer having apertures therein to provide means for generating a microwave field pattern having at least one mode of microwave energy of higher order than the fundamental modes of such energy, said means being spaced from the inside bottom surface by a predetermined distance.
Claim 32
Dependent Claim
14 words
A vessel according to claim 28, wherein said layer extends up the side walls.
Claim 33
Independent Claim
62 words
A method of heating a substance by microwave energy, said method comprising the steps of (a) confining said substance in a container such that at least some of the energy enters the substance through an undersurface thereof, and (b) at a location beneath said undersurface modifying the microwave field pattern to which said container is exposed to improve the uniformity of heating.
Claim 34
Independent Claim
62 words
A method of heating a substance by microwave energy, said method comprising the steps of (a) confining said substance in a container such that at least some of the energy enters the substance through an undersurface thereof, and (b) at a location beneath said undersurface modifying the microwave field pattern to which said container is exposed to improve the uniformity of heating.
Claim 35
Dependent Claim
37 words
The method of claim 30, wherein said field pattern is modified to have at least one mode of microwave energy of higher order than the fundamental modes of such energy at a predetermined distance below said undersurface.
Claim 36
Dependent Claim
19 words
The method of claim 31, wherein the majority of all the microwave energy enters the substance through said undersurface.
Claim 37
Dependent Claim
16 words
The method of claim 31, wherein said undersurface is flat and said predetermined distance is uniform.
Claim 38
Independent Claim
66 words
A method of heating a substance by microwave energy, said method comprising the steps of (a) confining said substance in a container such that at least some of the energy enters the substance through an undersurface thereof, and (b) at a location beneath said undersurface modifying the microwave field pattern to which said container is exposed to enhance the coupling of microwave energy into said undersurface.
Claim 39
Independent Claim
66 words
A method of heating a substance by microwave energy, said method comprising the steps of (a) confining said substance in a container such that at least some of the energy enters the substance through an undersurface thereof, and (b) at a location beneath said undersurface modifying the microwave field pattern to which said container is exposed to enhance the coupling of microwave energy into said undersurface.
References Cited (Backward Citations)
No citation records indexed.
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