# US 4,398,077 A · Microwave cooking utensil

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- Number: US 4,398,077 A
- Document ID: US4398077A
- Status: Granted
- Kind: A
- Application number: 06/291,135
- Filed: 1981-08-07
- Granted: 1983-08-09
- Earliest claimed: 1980-10-06
- Assignees: Raytheon Company
- Inventors: George Freedman; Palmer P. Derby
- Web page: https://patentgrep.com/patent/US4398077A

## CPC

- H05B 6/6494: {for cooking}
- Y10S 99/14: Induction heating
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A microwave cooking utensil comprising a glass ceramic dish having a resistive film on the outside and a conductive layer covering substantially all of the inside to block the passage of microwave energy through the dish to the interior thereof. A conductive lid over the dish prevents the passage of microwave energy through the opening of the dish. During cooking, substantially all of the microwave energy is absorbed by the resistive film instead of the food so that searing temperatures are maintained.

## Claims

### Claim 1

A microwave oven cooking utensil comprising:
a microwave transparent dish having an opening for placing a food body therein;
a layer of resistive material positioned over at least a portion of the outside surface of said dish; and
means for substantially shielding the interior of said dish from microwave energy, said means comprising the combination of a conductive layer covering a substantial portion of the inside of said dish and a conductive lid removably positioned over said opening.

### Claim 2 (depends on 1)

The utensil recited in claim 1 wherein said microwave transparent dish comprises a glass ceramic material.

### Claim 3 (depends on 1)

The utensil recited in claim 1 wherein said resistive material comprises tin oxide.

### Claim 4 (depends on 1)

The utensil recited in claim 1 wherein said conductive layer comprises aluminum.

### Claim 5

A microwave oven cooking utensil comprising:
a microwave transparent dish having an opening for placing a food body therein;
a resistive layer covering at least a portion of the outside surface of said dish;
a conductive layer covering substantially all of the inside surface of said dish to block the passage of microwave energy through said dish to the interior thereof; and
a conductive lid removably positioned over said opening to block the passage of microwave energy through said opening to the interior of said dish.

### Claim 6 (depends on 5)

The utensil recited in claim 5 wherein said transparent dish comprises a glass ceramic material.

### Claim 7 (depends on 5)

The utensil recited in claim 5 wherein said resistive layer comprises tin oxide.

### Claim 8 (depends on 5)

The utensil recited in claim 5 wherein said conductive layer comprises aluminum.

### Claim 9

A microwave oven cooking utensil comprising:
a microwave transparent dish having an opening for placing a food body therein;
a resistive film covering at least a portion of the outside surface of said dish;
a conductive layer covering a substantial portion of the inside surface of said dish to block the passage of microwave energy through said dish to the interior thereof; and
a removable conductive lid covering said opening and overlapping said dish, said lid being substantially parallel with said conductive layer for a distance perpendicular to the perimeter of said lid around the perimeter of said lid wherein the parallel portions of said lid and said conductive layer provide suppression of microwave energy leakage through the gap therebetween to the interior of said dish.

### Claim 10 (depends on 9)

The utensil recited in claim 9 wherein said transparent dish comprises a glass ceramic material.

### Claim 11 (depends on 9)

The utensil recited in claim 9 wherein said conductive layer comprises aluminum.

### Claim 12

A microwave oven cooking utensil comprising:
a microwave transparent lid;
a layer of resistive material positioned over at least a portion of the outside surface of said lid;
a conductive layer adjacent to a substantial portion of the inside surface of said lid; and
a dish adapted for being covered by said lid, said dish being conductive to microwave energy for substantially shielding the interior of said dish from microwave energy when said lid is positioned over said dish.

### Claim 13 (depends on 12)

The utensil recited in claim 12 wherein said transparent lid comprises a glass ceramic material.

### Claim 14 (depends on 12)

The utensil recited in claim 12 wherein said resistive material comprises tin oxide.

### Claim 15 (depends on 12)

The utensil recited in claim 12 wherein said conductive layer comprises aluminum.