The invention relates to a heater or similar devices, which has at least one elongated resistor, such as a heating resistor, a series resistor, a luminous resistor, etc. Radiant heaters are preferably used for cooking appliances for the heating of a hotpoint, oven muffle or the like. The radiant heater appropriately forms an operably closed, preassembled unit, which can be fixed as a whole to a corresponding device, e.g. a hob, a muffle wall, etc.
In place of a resistor it is also possible to provide some other elongated component, which in particular in an appropriate manner influences the action or operation of the heater (e.g. the direction and distribution of the heating power which is given off). This component can have one or more retaining portions, support legs, etc., which can be separate or integrated therewith by one-part construction or the like and which is used for optionally reciprocal supporting with a single mating surface or mating surfaces facing one another.
As opposed to supporting with substantially only one edge face, it is advantageous to provide a much larger surface support, whose support region can also be spaced from an outer or peripheral edge face, which corresponds to at least 3, 10, 30 or 60 times the width of the edge face and which can only be 4/100 to 1/10 mm. The support leg can be uninterrupted over at least a 1/4, a 1/3 or 1/2 the length or substantially the entire length of the component and therefore e.g. forms a strip-like marginal zone of the component, whose longitudinal edge forms the end apex of the support leg.
Instead of or in addition thereto there can also be spaced, succeeding support legs. If the particular support leg is not manufactured from a flat or foil-like starting material by separating or cutting along its edge boundary, but instead e.g. by permanent bending deformation from a wire-like material, then it can be in the form of a bow or part ring or in the form of a portion of a coil. In particular if the cross-section of this starting material is not polygonal, e.g. rectangular or square, but is instead circular, flat oval or elliptical, the support area is at a distance from the linear apex of the edge boundary corresponding to at least the minimum or maximum cross-sectional thickness of the starting material, said spacing being measured approximately at right angles to the edge boundary. In each case the support leg is advantageously flat to the extent that its width or length is at least 2, 4 or 30 times greater than said material thickness.
Constructionally the heater is appropriately arranged in such a way that on its heating side is visible from the outside at least one component or resistor at least over part of its length if said heating side is not displaced or concealed by a cooking utensil or the like. On said heating side the heater or the resistor is advantageously shielded by a translucent cover, e.g. a glass ceramic plate and is protected by it against direct contact. However, the component can also be provided with longitudinal portions or substantially over its entire length in completely flush, embedded or encapsulated form.
The smaller the material thickness of the starting material or the further said material thickness is below 1, 0.5, 0.1 or even 0.05 mm, the lower its strength, particularly its bending, buckling, tensile, tearing or thermal strength, particularly if it is regularly exposed to greatly differing temperatures of more than 200.degree. or 500.degree. to 1000.degree. C. However, the strength is not only important during operation, but also before and during assembly, because then particularly high mechanical stresses or loads can occur. No protection is provided against such loads if following the insertion of the support leg in its operating position an end portion is bent at right angles for positive fixing, because only then is a certain stiffening obtained through the angular shape. In this operating position the non-prefabricated bend together with the transversely projecting end leg forms the end apex at the free end of the support leg.
The so-called glow pattern of a resistor which can be seen by the human eye and which is operated in the visible infrared radiation range, is dependent on numerous factors, e.g. the electrical operating power, cross-sectional changes of the resistor, its thermal coupling or also the shape of the resistor to the extent that this influences the current flow. If the heating resistor, e.g. as in German Patent 2 551 137, is constructed as a meander-shaped flat material strip, then there are power concentrations in the vicinity of the springing in ends of the meander cutouts. Therefore projections, which face the springing in ends on the outer edges of the meander projections have no visible influence on the glow pattern in the case that said resistor is operated in the visible radiation range.