Microwave oven with multi-infrared sensors disposed at different distance intervals from the rotating table plane

• US 5,693,247 A
• Filed: 06/09/1995
• Issued: 12/02/1997
• Est. Priority Date: 06/11/1994
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Jung, Kwang Gyun, Bu, Jong Uk
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US08/488,930
• Time in Patent Office: 907 Days
• Field of Search: 219/711, 219/710, 219/510, 219/754, 374/149, 374/121, 374/126, 374/129, 374/130, 374/131, 374/133, 99/325
• US Class Current: 219/711
• CPC Class Codes: H05B 6/6455 the sensors being infrared detectors

Abstract

A microwave oven includes at least two sensors for detecting heat rays emitted from the food which is being heated, a signal processor for obtaining a precise surface temperature of food, irrespective of the deviation of distances between the sensors and food, using output signals from the sensors, and a controller for receiving the output signal of the signal processor to recognize the cooking status of the food and controlling the heating of the food in accordance with the recognized cooking status.

Claims

1. A microwave oven comprising:

a microwave generator;

a cooking chamber;

a rotating table at the bottom of the cooking chamber for supporting food;

at least two infrared sensors disposed at the top of the cooking chamber above the rotating table and at different distances from the plane of the rotating table;

a signal processor for obtaining a precise temperature of the food surface using output signals of said sensors, irrespective of the deviation of distances between said sensors and food; and

a controller for receiving the output signal of said signal processor to recognize the cooking status of the food and controlling the heating of the food in accordance with the recognized cooking status.

2. A microwave oven as claimed in claim 1 wherein said controller operates a predetermined second degree equation using the output signals of the respective sensors, compensates the deviation of distances between food and the respective sensors by the answer of said equation and detects the temperature of the food surface precisely.

3. A microwave oven as claimed in claim 2 wherein if two sensors are used, then the answer of the second degree equation is obtained by an equation (T1 T2)×

X1² +2×

T1×

X2×

X1+X2² ×

T1=0, where T1 and T2 are values measured by said first and second sensors, X1 is the distance between said first sensor and second sensor and X2 is the difference in distance between said first sensor and second sensor.

4. A microwave oven as claimed in claim 1 further comprising at least one reflection film for reflecting heat rays emitted from the food to then be incident onto said sensors in order to increase options in disposing said sensors.

5. A microwave oven as claimed in claim 4, wherein said reflection film is a half reflection film for reflecting a half of heat rays emitted from the food and transmits a residual half of the heat rays.

6. The microwave oven as recited in claim 1, wherein each of the infrared sensors is a thermopile type infrared sensor.