GB1424888A - Microwave oven - Google Patents

Abstract

1424888 Oven doors LITTON INDUSTRIES Inc 20 June 1973 [26 June 1972 27 Sept 1972] 29395/73 Heading F4W [Also in Divisions A4 and H3-H5] The door of a microwave oven is a laminate, of a perforated metal sheet and at least one transparent support panel, of greater size than the access opening of the oven. The perforated metal sheet 24 is preferably aluminium which has been bonded on to the support panel 22 which is preferably glass. The surface of the aluminium sheet opposite the glass is coated with silicone enamel 25, and the aluminium is formed with a plurality of holes 27 over the central part of the door to allow the inside of the oven to be seen, the holes having been etched using the enamel as a mask. The enamel is applied by a silk screen process. The hole diameter is of a size sufficiently small to prevent escape of microwave energy, e.g. 0À04 inch diameter in an aluminium layer 0-002 inch thick. Around the edge of the laminate is a metal frame 23 forming the periphery of the door. A microwave choke 17 is provided around the oven opening and comprises a mass of dielectric material 18 held in a groove 19 to which a narrow gap leads from the inner edge 41 of the oven. A ridge 42 prevents the closed door from closing this gap. A microwave absorbent gasket 28 is mounted around the periphery of the glass panel and contacts ridge 43 of the oven when the door is shut; it is made of a conductive polymer vinyl compound or a conductive silicone rubber. In an alternative embodiment an aluminium sheet in the form of a perforated foil is sandwiched between two glass panels there being layers of transparent epoxy resin bonding material between the aluminium and the glass, Fig. 5, not shown. In a further embodiment a layer of transparent plastics material is used in place of the inner glass panel of the embodiment of Fig. 5.