1 OVEN ELEMENT CONTROLLER Technical Field [0001] The present invention relates generally to controllers for controlling the heat emitted by heating elements and, in particular, to a controller for controlling the heat emitted by multiple heating elements within a thermally insulated chamber, such as an oven. Background [0002] An oven is an appliance used for the heating, baking or drying of substances, and is most commonly used for cooking meals. Using an electric oven to cook a meal has been a way of life since the first half of the 20th century when they were first introduced on a mass scale. [0003] A typical oven has an enclosed cooking chamber, and heating elements contained therein. Typically a lower hearing element is provided, which is used to heat the oven from below. This lower heating element is commonly used for baking and roasting. The oven may also be provided with a top heating element used to heat the oven from above, which is typically used for grilling. In order to provide faster, more-even cooking, a heating element having a fan may also be provided. The fan circulates the heat in the cooking chamber. [0004] The heating elements are typically controlled by the temperature controlled switch, known as a thermostat, and a selector switch. The selector switch selects the type of cooking, which dictates which heating elements are to be used. The thermostat controls the heating elements in an attempt to maintain a pre-set temperature. In electric ovens, as the temperature inside the chamber increases beyond the pre-set temperature, power to the heating element(s) is cut. The temperature gradually decreases to a point below the pre-set temperature when power to the heating element is restored, again allowing the temperature to rise. [0005] In the prior art the user's control is limited to setting the pre-set temperature and selecting which element or elements are to be powered. A need exists for an alternative arrangement for controlling the heating elements. Summary [0006] According to an aspect of the present invention, there is provided a controller for controlling a plurality of heating elements within a chamber, the controller comprising: 2 a variable energy controller associated with each of the plurality of heating elements, each variable energy controller having a user input means for receiving a setting of an amount of energy to be supplied to the associated heating element, and for controlling the amount of energy supplied to the associated heating element based upon the setting; a temperature sensor within the chamber for sensing a temperature within the chamber; and a temperature controller having a further user input means for receiving a temperature setting, the temperature controller switching the energy supplied by the variable energy controllers based upon the temperature within the chamber and the temperature setting, whereby the temperature within the chamber is controlled by the temperature controller, and the amount of heat emitted by respective heating elements while the temperature within the chamber is below the temperature setting is controlled by the respective variable energy controllers. [0007] Other aspects of the invention are also disclosed. Brief Description of the Drawings [0008] At least one embodiment of the present invention will now be described with reference to the drawings, in which: [0009] Fig. 1 is a schematic diagram of a cooking chamber, heating elements within the cooking chamber, and a controller according to the present disclosure for controlling the heating elements; and [0010] Fig. 2 shows a control panel for the controller shown in Fig. 1. Detailed Description [0011] Fig. 1 is a schematic diagram of a cooking chamber 200, and heating elements 210, 220 and 230 within the cooking chamber 200. The cooking chamber 200 includes therein a top hearing element 210, a bottom heating element 230, and a heating element 240 having a fan associated therewith.
3 [0012] A controller 250 is also provided for controlling the heating elements 210, 220 and 230. More particularly, the controller 250 controls the power provided from the alternating current (AC) power source 240 to the heating elements 210, 220 and 230 in the manner described in detail below. [0013] The controller 250 includes a potentiometer 212, 222 and 232 associated with each of the heating elements 210, 220 and 230 respectively. More particularly, each of the potentiometers 212, 222 and 232 has an associated variable power circuit 211, 221 and 231 which controls the amount of power provided to the associated heating element 210, 220 and 230. A further potentiometer 245 is provided which is associated with a temperature control circuit 241. [0014] Fig. 2 shows a control panel 100 for the controller 250 shown in Fig. 1. The control panel 100 has element control knobs 110, 120 and 130 for adjusting the potentiometers 212, 222 and 232 (Fig. 1) respectively, and a temperature control knob 140 for adjusting the potentiometer 245 (Fig. 1). [0015] Potentiometer 245 controls a temperature at which temperature control circuit 241 opens an associated relay 242, thereby disconnecting the heating elements 210, 220 and 230 from the AC power source 240. The temperature is sensed using a temperature sensor (not illustrated) positioned within the chamber 200. As the temperature gradually decreases to a point below the temperature set using potentiometer 245, control circuit 241 again closes the relay 242, thereby restoring power to the heating elements 210, 220 and 230, again allowing the temperature to rise. Accordingly, potentiometer 245 is used to control the temperature within the cooking chamber 200. Temperature control circuits are known in the art and are therefore not described to circuit level. [0016] Each variable power circuit 211, 221 and 231 controls the amount of power provided to the associated heating element 210, 220 and 230. Variable power circuits are also known in the art and therefore not described to circuit level. Each variable power circuit 211, 221 and 231 includes a triac and diac arrangement (not illustrated) with the diac switching current across itself after a specified potential difference, controllable using the respective potentiometer 212, 222 and 232, is reached across it. Accordingly, the diac is conductive while the AC voltage remains below a certain voltage level, and becomes non-conductive as soon as the AC voltage crosses that voltage level. While the diac is conductive the triac which connected in series with the respective heating element 210, 220 and 230 is also conductive. Similarly, while the diac is 4 non-conductive the triac disconnects power to the respective heating element 210, 220 and 230. The conduction of the triac only for a specified section of the input AC voltage curve results in a voltage output from the respective variable power circuit 211, 221 and 231 which is an AC voltage chopped into smaller sections, thereby reducing the root mean square (RMS) of the power delivered to the respective heating element 210, 220 and 230. [0017] Accordingly, the which temperature control circuit 241 merely provides power to the variable power circuits 211, 221 and 231 when the temperature inside the cooking chamber 200 is below the pre-set temperature adjusted using the temperature control knob 140, and cuts power to the variable power circuits 211, 221 and 231 when the temperature inside the cooking chamber 200 is above that pre-set temperature. While power is provided to the variable power circuits 211, 221 and 231, each of the variable power circuits 211, 221 and 231 controls the amount of power provided to its associated heating element 210, 220 and 230, with the amount of power being set using element control knobs 110, 120 and 130 respectively. Accordingly, the user is able to, by adjusting the respective element control knobs 110, 120 and 130, separately control the amount of heat emitted from the respective heating element 210, 220 and 230, while the temperature within the cooking chamber 200 is set using the temperature control knob 140. [0018] The foregoing describes only some embodiments of the present invention, and modifications and/or changes can be made thereto without departing from the scope of the invention, the embodiments being illustrative and not restrictive.