U.S. Philips Corporation

Sander Slegt

Jacob H Botma

Hendricus J Duipmans

Robin K Moore

Tjerk K Bij De Leij

A heating element for a liquid heating vessel, comprises a metal substrate, an insulating layer provided over the substrate, and an electrically conductive heating track provided over the insulating layer. The heating track comprises a path extending between two contact pads, the heating track defining regions of relatively high density of track portions and regions of relatively low density of track portions. The contact pads are located in regions of relatively low density, and the layout of the heating track is designed such that in the event of thermal overheating of the element, the heating track ruptures at one of a predetermined set of locations in high density regions of the heating track. The heating track itself thereby functions as a thermal fuse.

Heating element with regions of high/low density

An immersion heating element comprises first and second heat conducting substrates defining top and bottom surfaces of the heating element. An electrically insulating layer is provided on one side of each substrate, and the two substrates are mounted together with the insulating layers facing each other and with a resistive heating track sandwiched between the insulating layers. This structure avoids the need for a thick protective insulating layer over the heating track.

Immersion heating element sandwiched between two substrates

A liquid heating vessel, such as a kettle, enables user selection of the temperature to which the liquid is to be heated. A thermal sensor is provided which is responsive to the temperature of the heating element. During the heating cycle, the operation of the heating element is interrupted, and temperature samples are obtained as the element cools. Analysis of the temperature decay function of the heating element during the interruption enables the liquid volume to be estimated, as well as the time required to heat the liquid to the selected temperature.

Heating vessel and method of controlling the heating element of such a

A heating element 2 comprises a substantially planar substrate 4 having a heating track or tracks 8 and a thermal sensor 10, in the form of a track or discrete component, disposed on one side of the substrate 4. The thermal sensor 10 is separated from the heating track 8 by a locally thinner portion 12 of the substrate 4. The sensor 10 may be located in, or surrounded by, the thinner portion 12.

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Leek, Netherlands

Sander Slegt