Thorn Emi Appliances Limited

Thorn Domestic Appliances (electrical) Limited

Stephen J Newton

Peter W Crossley

Alex L Halberstadt

David Wellcome

Bernard F Fellerman

Geoffrey I Bell

Abdul H Patel

Susan M Crocker

A heating unit includes two tubular tungsten-halogen lamps, each having a tungsten filament. The lamps are supported within a ring of ceramic fibre material and the unit is preferably mounted beneath an infra-red-transmissive cooktop to define a hotplate area of a cooking hob. A control circuit provides a range of discrete power outputs of the lamps, each power output corresponding to a power control setting set by a user of the cooking hob. The circuit includes a phase control circuit for switching power to the lamps at a predetermined phase angle to achieve one or more of the lower power outputs.

Heating apparatus

A microwave oven consists of an oven cavity containing a turntable, a source of microwave energy and a waveguide for directing microwave energy into the oven cavity. Two lamp units accommodate tungsten-halogen lamps for browning food cooked by the microwave energy. To inhibit arcing through the lamps due to exposure to the microwave energy, support coils supporting the filament of each lamp are each formed from an incomplete turn of the coil to inhibit arcing between adjacent regions thereof. Other modifications to the lamps and/or the units may also be provided to protect the lamps from exposure to the microwave energy.

Microwave oven having a source of infra-red radiation

An electric cooker or cooking hob has a ceramic plate 2 on which there are a number of hot plate areas each heated by a respective annular heating element 4 disposed within an insulating housing 7. A temperature dependent resistor 9 is disposed below the hot plate area at the center of focus of a reflector 8 which is arranged to focus radiant energy from the hot plate area onto the resistor 9 while at the same time shielding the resistor 9 from direct radiation from the electric heating element 4. The signal derived from the resistor 9 is a measure of the temperature of the hot plate and can be used to provide a thermal tripping function to prevent over-heating of the hot plate area and/or to carry out closed loop control of the temperature of the hot plate area. The reflector 8 may be replaced by a shield which shields the resistor 9 from direct heating by the heater. A further annular heating element surrounding the element 4 may be provided, with the control circuitry enabling either the element 4 alone or element 4 plus the outer element to be energized.

Cooking apparatus

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Haslemere, United Kingdom

Stephen J Newton