Electric resistance heating devices – Heating devices – Radiant heater
Patent
1999-03-11
2000-09-26
Jeffery, John A.
Electric resistance heating devices
Heating devices
Radiant heater
392435, 392418, 219521, 219543, 219385, 99389, A47J 3708
Patent
active
061252344
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The instant invention is related to an electrical apparatus for the thermal processing of foodstuff, enabling the grilling, cooking, reheating or keeping warm of foodstuff, via a heating body implementing the Joule effect.
2. Description of Background and Relevant Information
Heating food via electrical means, such as by micro-waves, induction, or still by the Joule effect is becoming increasingly more common.
It is known that electrical toasters currently in use generally have a casing, open at its upper part, inside of which are arranged at least one pair of parallel plates between which the bread to be toasted can be inserted. Generally, these plates hold an assembly of resistances that are either exposed or covered in a quartz sheathing. The bread itself can be placed in a vertically mobile support such that the bread slices are automatically ejected from the casing after a pre-determined heating interval, or after a pre-determined temperature has been attained. The toasting action consists of toasting the external surface of a slice of bread, whereas the inner volume remains soft, but hot. In electrical toasters, energy is produced by the Joule effect as a result of current passing through the resistances. The energy thus released is transmitted via radiation over each of the surfaces of the bread according to a factor that is proportionate to the fourth power of the absolute temperature in accordance with the laws of Stephan and Boltzman.
But for safety reasons, access to the heating resistances is naturally restricted and it is impossible to follow the progress of the operation without interrupting the toasting process, in order to stop it at just the right time.
SUMMARY OF THE INVENTION
The main object of the instant invention is to overcome this disadvantage and to allow a visual monitoring of the progress of the bread inserted into the toaster, or of any other food processed in the same way, by increasing visibility without reducing the heating surface. In addition, the reduction of the number of parts naturally decreases manufacturing costs and boosts reliability.
According to the invention, the electrical apparatus for the thermal processing of foodstuff having a support frame in which at least one heating element is mounted, is characterized in that said heating element is constituted of an electrical resistance, connected to a source of electrical current, adjacent to at least one transparent substrate that is mechanically and heat resistant.
The mechanically and heat resistant substrate can be made from a monolithic glass plate or a laminated glass plate or a polymer plate. The electrical resistance can be affixed on a transparent substrate, inserted between two transparent substrates, or be constituted of a planar conducting coating arranged on a plate.
The continuous electrically resistant coating is advantageously a transparent semi-conducting oxide coating, especially tin oxide doped with antimony or fluorine or indium oxide doped with tin, the resistant coatings emitting, in the temperature range of the thermal processing, a radiation whose wave length is on the order of 7 microns.
Glass plates coated on one of their surfaces with a thin, transparent electro-conducting coating having low emissivity and being infra-red reflecting are available commercially, the conducting coating generally being tin oxide doped with antimony or fluorine, or indium oxide doped with tin, and deposited in a thickness of 0.2 and 0.5 microns, for example, 0.3 to 0.4 microns. Surface resistivity can range from a few .OMEGA./.quadrature. to a few hundred .OMEGA./.quadrature., for example, 10 to 100 .OMEGA./.quadrature.. The conducting coating behaves like an electrical resistance whose value is a function of the length/width ratio. Due to the passage of current, this coating gets heated and also heats the glass plate or, more generally, the substrate. It has been noted that when the surface resistance of the glass (non-coated with a coating) is on the or
REFERENCES:
patent: 2564677 (1951-08-01), Davis
patent: 2564706 (1951-08-01), Mochel
patent: 2777044 (1957-01-01), Lytle
patent: 3737624 (1973-06-01), Eilenberger
patent: 3919441 (1975-11-01), Horiki
patent: 4346651 (1982-08-01), Schickedanz
patent: 4713530 (1987-12-01), Schittenhelm et al.
patent: 4791862 (1988-12-01), Hoffmann
patent: 4970375 (1990-11-01), Schittenhelm et al.
patent: 5119467 (1992-06-01), Barsky et al.
patent: 5138938 (1992-08-01), McClean
patent: 5896808 (1999-04-01), Graur
patent: 5960702 (1999-10-01), Thiriat et al.
Patent Abstracts of Japan, vol. 004, No. 038 (C-004), Mar. 27, 1980, of Japanese Patent Application No. 55 010466 (Seiko Epson Corp.), dated Jan. 24, 1980.
Jeffery John A.
Robot-Coupe(S.N.C.)
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