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Publication numberUS3493708 A
Publication typeGrant
Publication dateFeb 3, 1970
Filing dateNov 9, 1967
Priority dateNov 9, 1967
Publication numberUS 3493708 A, US 3493708A, US-A-3493708, US3493708 A, US3493708A
InventorsStewart C Johnson
Original AssigneeWestinghouse Electric Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Cooking apparatus
US 3493708 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

s. c. JoHNsoN 3,493,708

cooxINc APPARATUS piled Nov. 9. 1967 Feb. s, 1970 n/f /g/WM Stewart C. Johnson MZ 5 Claims ABSTRACT 0F THE DISCLOSURE Cooking Iapparatus of the type utilizing electromagnetic energy wherein a single source of energy is provided, which energy is coupled to the oven ca'vity, in part, unaltered and, in part, converted to energy at a higher frequency for the purpose of surface browning of certain foodstuffs.

BACKGROUND OF THE INVENTION This invention relates, in general, to cooking apparatus and, more particularly, to the type of apparatus which utilizes electromagnetic energy.

Heretofore, cooking with electromagnetic energy has not met with wholehearted acceptance. Whil'e this method is exceedingly fast, it does not produce the desired surface browning of foodstuffs which serves the dual purpose of sealing in the juices and creating an appetizing appearance.v

One solution to the problem is to provide at least t-wo energy sources, one operating at a frequency suitable for deep penetration of the foodstuff and the other operating at a higher frequency for shallow penetration. The obvious disadvantage of such an arrangement is the prohibitive cost of using two energy sources and associated controls.

Another solution to the problem is to provide a conventional oven heater element to Ibe operated in conjunction with the primary cooking source, therefore, the electromagnetic energy. While this solution is satisfactory from the standpoint of solving the surface browning problem, it adds; time to the overall cooking operation over that of cooking `with only electromagnetic energy and is, therefore, objectionable.

Accordingly, it is the general object of this invention to provide new and improved cooking apparatus of the type utilizing electromagnetic energy.

It is a more particular object of this invention to provide new and improved apparatus of the type employing electromagnetic energy in which such energy produces both deep and shallow cooking of foodstuffs.

Another object of this invention is to provide new and improved cooking apparatus having a single source for generating electromagnetic energy at one frequency and means cooperating therewith for altering at least some of energy emanating from the source to produce energy at a second frequency.

SUMMARY Briefly, the above-cited objects are accomplished by providing, in cooking apparatus having a source of electromagnetic energy, a harmonic generator utilizing a material having a planar anisotropy, which material is disposed in a magnetic field. Some of the energy is ex- United States Patent O icc posed to the generator for producing energy at a higher frequency than the fundamental frequency emitted from this source. Some of the energy at the fundamental frequency is coupled to the cooking cavity unaltered so that energy at boththe fundamental and the harmonic frequencies is coupled to the cavity along different waveguide sections.

Further objects and advantages of the present invention will become more apparent in view of the following detailed description and drawing forming a part thereof.

DESCRIPTION OF THE DRAWING The figure is a schematic representation of the invention, including an oven cavity.

Referring to the drawing, reference character 10 designates an oven cavity suitable for supporting foodstuff to 'be cooked. A container 11 is located within the oven for holding foodstuff 12 which is to be heated. An opening 13 in the cavity 10 provides access to the interior thereof through a suitable closure member of door 14.

A magnetron 16 provides electromagnetic energy to be coupled to the oven cavity 10 by a plurality of lwaveguide sections 17 and 18. The magnetron 16 comprises a plurality of anode vanes 19 and a control cathode 21. Energy emitted from the magnetron 16 at a typical 'frequency of 2450 mc. is coupled to the cavity 13, unaltered through the waveguide section 17.

A harmonic generator 22 (shown in block form) operatively associated with the waveguide section 18 serves to convert the energy transmitted to the oven cavity 10 through the waveguide section 18. This conversion is such as to produce energy at a frequency of 4900 mc. The effect of providing, simultaneously, energy at the specified frequencies is to produce shallow as well as deep cooking of foodstuffs utilizing a single energy source. Such :a generator, as disclosed in the Feb. 2, 1962 edition of Electronics, at pages 58-59, basically comprises a crystalline structure having planar anisotropy which structure is disposed in a D.C. magnetic field. The crystalline material is also disposed intermediate a screen and a tapered transition, the tapered transition acting as a short to reflect fundamental power back toward the energy source and the screen serving to reflect the second harmonic power in the direction of the cavity. It is intended to incorporate, in this specification by the above reference, the teachings disclosed therein.

Since it may be desirable to couple all of the energy from the source 16 to the oven cavity 10, a lbaffle 23 is provided which may be used to selectively close the entrance to the cavity section 18.

Since numerous changes may be made in the described apparatus and different embodiments of the invention may be made without departing from the spirit thereof, it is intended that all matter contained in the foregoing descriptive and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. Cooking apparatus comprising:

:a source of electromagnetic energy capable of producing energy at a first frequency,

a cavity in Iwhich foodstuffs is exposed to said energy,

means for coupling energy from the source to said cavity,

said coupling means including means for converting at least a portion of said rst frequency energy to a second frequency.

2. Cooking apparatus comprising:

a cavity in which foodstuffs can be exposed to electromagnetic energy, means for generating electromagnetic energy at a rst frequency for deep cooking of said foodstulfs,

means for converting at least a portion of said rst frequency energy to electromagnetic energy :at a second frequency for surface browning of said foodstuff.

3. Structure as specified in claim 2 wherein, said converting means comprises material having planar anisotropy and disposed in a magnetic field.

4. Structure as specified in claim 1, wherein sa'id coupling means comprises a pair of waveguide sections one of which passes energy at said first frequency and the other of which passes energy at said second frequency.

5. Structure as specified in claim 4, including means for blocking passage of energy tosaid cavity through said waveguide section passing energy at said second frequency.

References Cited OTHER REFERENCES Electronics, Feb. 2, 1962, pages 58-59.

15 JOSEPH v. TRUHE, Primary Examiner L. H. BENDER, Assistant Examiner

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2593067 *Feb 13, 1947Apr 15, 1952Raytheon Mfg CoHigh-frequency apparatus
US2790054 *Nov 12, 1954Apr 23, 1957Raytheon Mfg CoMode-shifting devices
US2895828 *Feb 6, 1958Jul 21, 1959Gen ElectricElectronic heating methods and apparatus
US2909635 *Jul 29, 1957Oct 20, 1959Raytheon CoElectronic oven systems
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3806689 *Dec 6, 1972Apr 23, 1974Us ArmyApparatus and method for heating simultaneously with microwaves of two widely different frequencies
US5237139 *Sep 3, 1991Aug 17, 1993Whirlpool International B.V.Microwave oven, a method for excitation of the cavity of a microwave oven, and a wave guide device for carrying out the method
US6441355 *Mar 20, 2001Aug 27, 2002Merrychef LimitedMicrowave heating using independently controllable internal and external antennae
U.S. Classification219/746
International ClassificationH05B6/80
Cooperative ClassificationH05B6/6402
European ClassificationH05B6/64A