Electric heating – Microwave heating – With control system
Reexamination Certificate
2002-02-26
2003-05-13
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
With control system
C219S749000, C219S756000, C219S748000, C374S149000
Reexamination Certificate
active
06563097
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a microwave oven. More specifically, the present invention relates to a microwave oven that can apply localized heat in a specific location in said heating chamber.
A conventional microwave oven described in Japanese Patent Number 2,894,250 seeks to provide localized heating in the location where food is placed in a heating chamber. More specifically, the placement location of food is determined based on the distribution of temperature increases in the heating chamber when the entire heating chamber is evenly heated. Localized heat is applied to this location.
If it is determined that multiple food items are placed in the heating chamber, this microwave oven performs localized heating at the center of the multiple food placement positions.
However, energy efficiency in this microwave oven is reduced if multiple food items are placed in the heating chamber. Thus, it could not be said that appropriate heating was being provided. The central position of the multiple food placement positions are located where no food is present. Thus, the food items absorb microwaves from the magnetron at a reduced rate compared to when heating is applied in a localized manner to a position where food is present.
Also, if multiple items of food are placed and localized heating is applied to just one of the food items, there may be insufficient heating of the food items at other locations. Sequentially applying localized heat to each of the multiple food placement positions can lead to longer preparation time, and may not result in appropriate heating.
OBJECTS AND SUMMARY OF THE INVENTION
The object of the present invention is to overcome the above problems and to provide a microwave oven that can heat all food in an appropriate manner even when food items are simultaneously placed at multiple locations in a heating chamber.
According to one aspect of the present invention, a microwave oven includes: a heating chamber for holding food; a magnetron for producing microwaves to heat the food; an irradiation antenna guiding the microwaves from the magnetron to the heating chamber; and an antenna controller that, when the magnetron is performing a heating operation, controls the irradiation antenna in an alternating manner between a first mode wherein the microwaves from the magnetron are guided over an entirety of the heating chamber and a second mode wherein the microwaves are guided to a specific area in the heating chamber.
As a result, the microwave oven provides localized heat for a food item placed in a specific location in the heating chamber while also heating food items placed at other locations in the heating chamber.
Thus, if food items are placed at multiple locations in the heating chamber at the same time, the microwave oven can still heat all food items appropriately.
Also, it is preferable for the microwave oven of the present invention to further include a placement position determining module determining a placement position for a food item that is to be heated in a localized manner inside the heating chamber. The specific area is the placement position of the food item to be heated in a localized manner.
As a result, heating by the microwave oven is performed according to the locations where food is placed.
Also, it is preferable for the microwave oven of the present invention to further include a temperature detector detecting temperature at a plurality of locations in the heating chamber. The placement position determining module determines that the placement position of the food item to be heated in a localized manner is the location that has a maximum temperature increase value within a predetermined time when the magnetron is performing the heating operation and the irradiation antenna is being controlled in the first mode.
As a result, the position of the food for which localized heat is to be applied is determined without requiring the user to select which food item to be heated in a localized manner and does not require the user to enter the location of the food in the microwave oven.
Thus, the microwave oven is made easier to use.
Also, it is preferable for the microwave oven of the present invention to further include an antenna rotation module for rotating the irradiation antenna. The antenna control module controls the irradiation antenna in the first mode by rotating the antenna rotation module and in the second mode by stopping the irradiation antenna at a predetermined position which directs the irradiation toward a detected food item.
This allows the irradiation antenna to be controlled in the first mode and the second mode easily.
Also, it is preferable in the microwave oven of the present invention for the antenna controller to select between a full heating mode wherein an entirety of the heating chamber is heated by controlling the irradiation antenna in the first mode and a localized heating mode wherein localized heating of the specific location in the heating chamber is performed by alternately controlling the irradiation antenna between the first mode and the second mode.
As a result, heating is performed for the entire heating chamber or localized heating is performed for a specific location. Also, when a specific location is to be heated in a localized manner, food items placed in other locations are still heated appropriately.
Also, it is preferable for the microwave oven of the present invention to further include a temperature detector which detects temperatures at a plurality of locations in the heating chamber. The antenna controller determines whether to control the irradiation antenna using the full heating mode or the localized heating mode depending on a temperature increase value within a predetermined time of a location detected by the temperature detector as having a lowest temperature when the magnetron begins heating.
As a result, whether or not to provide control for localized heating is determined based on whether identical temperatures are detected within a region that is judged to be suited for localized heating.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.
REFERENCES:
patent: 2909635 (1959-10-01), Haagensen
patent: 5986249 (1999-11-01), Yoshino et al.
patent: 6169277 (2001-01-01), Feher et al.
patent: 3-129695 (1991-06-01), None
patent: 9-027389 (1997-01-01), None
Kitagawa Hiroyasu
Taino Kazuo
Tanaka Kazuko
Yamane Yoshiko
Leung Philip H.
Sanyo Electric Co,. Ltd.
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