Anzeigevorrichtung für Flüssigkeitsheizgeräte

A liquid heating device, such as a kettle or hot water jug, having visual temperature indication means in the form of a series of light emitters which are arranged to be lit progressively as liquid is heated in the appliance. The appliance is provided with a thick film heating element having positive temperature coefficient resistor (PTCR) portions which develop varying voltages as the heating element heats up in use, and these voltages are used to trigger the operation of respective diodes of an LED array so that the array lights up progressively as the temperature rises. The LEDs range in colour from green (cold) through yellow/orange (warm) to red (hot) and can illuminate a sight glass of the vessel or the vessel contents in which case the vessel wall has at least a portion which is transparent or translucent. The main heating element of the device may be in series (as shown) or in parallel (Figure 2) with a parallel arrangement of PTCR's and associated fixed resistors.