Electric heating – Microwave heating – Enclosed cavity structure
Reexamination Certificate
2002-07-17
2003-12-02
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
Enclosed cavity structure
C219S758000, C219S702000, C219S715000, C219S719000, C126S29900R
Reexamination Certificate
active
06657172
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a high frequency heating apparatus equipped with an oven hood, which owns a function capable of ventilating gas generated from another heat-cooking apparatus installed under a main body of the own high frequency heating apparatus, and is arranged to convert electric power into high frequency electric power with employment of a semiconductor element.
2. Description of the Related Art
Conventionally, as this sort of appliance, such a high frequency heating apparatus having a construction capable of converting electric power into high frequency electric power with employment of a semiconductor element has not yet been proposed. However, there is merely provided a heating appliance having a ventilation means and an arrangement for supplying high frequency electric power by way of an LC resonant circuit constituted by a heavy weight object.
FIG. 7
represents an appliance having the conventional arrangement.
In
FIG. 7
, reference numeral
1
shows a heating chamber for storing thereinto an object to be heated, reference numeral
2
represents a power supply apparatus having an LC resonant circuit arrangement which heats the object to be heated, and reference numeral
3
shows a ventilation means for ventilating gas generated from another heat-cooking apparatus installed under a main body of the conventional appliance. Also, reference numeral
4
indicates an illumination means for illuminating the above-described another heat-cooking apparatus by using light, which is installed under the main body of this conventional appliance.
Additionally, in microwave ovens corresponding to high frequency heating apparatus, various technical ideas have be taken in order to shorten heating time. For instance, as described in Japanese Laid-open Unexamined Patent Publication No. Hei-2-227988, while peripheral temperatures of the respective elements such as a magnetron are detected, since maximum output power higher than the normal continuous maximum output power is generated for a time period until the detected temperatures reach the safety limiting temperatures of the respective elements, such a technical idea is made that the heating time is shortened while the safety characteristics of the respective elements are secured.
However, in usual homes, these microwave ovens are normally used under the power supply having the rated power of 100V/15A due to the Japanese indoor electric wiring system, so that power consumption of these microwave ovens should be suppressed lower than, or equal to 1.5 KW.
Referring now to
FIGS. 16A
,
16
B, and
16
C, power consumption of a microwave oven which constitutes a conventional general-purpose high frequency heating apparatus will be explained.
In
FIGS. 16A
,
16
B, and
16
C, an abscissa shows time “t”, and an ordinate indicates power consumption “W”.
FIG. 16A
shows an overall power consumption of the microwave oven. Similarly,
FIG. 16B
indicates electric power “W
1
” which is consumed so as to oscillate electromagnetic waves from a magnetron corresponding to an electromagnetic wave radiation unit employed in the microwave oven.
FIG. 16C
indicates other power consumption, namely power consumption “
2
W” of a cooling means (for example, fan), an illumination means (lamp), and a food mounting means (turn table). Although the power consumption “W
2
” shown in
FIG. 16C
is substantially constant irrespective of a time elapse, the electric power W
1
which is consumed so as to oscillate the electromagnetic waves and is represented in
FIG. 16B
is slightly changed, depending upon temperatures of the magnetron and the control method. In this case, this power consumption W
1
is slightly decreased from a stating time “0” of the heating operation up to time “t
6
”, and then, becomes constant after this time “t
6
”. Since
FIG. 16A
is the entire power consumption of the microwave oven, this power consumption becomes “W
1
+W
2
”. Now, in such a case that general-purpose microwave ovens are employed, these microwave ovens are usually used under the power supply having the rated power of 100V/15A. Thus, the power consumption of these microwave ovens is suppressed lower than, or equal to 1.5 KW. Within this power consumption of 1.5 KW, electric power of the fan (10 W), the lamp (30 W), and the turn table (10 W) is consumed other than the oscillation of the electromagnetic waves. Furthermore, as to the oscillation of the electromagnetic waves, since the actual power consumption is changed into the electromagnetic waves at an efficiency of approximately 50 to 60%, high frequency output power defined from 500 W to 700 W are mainly used so as to heat foods.
However, since the high frequency electric power cannot be controlled in a linear manner in the above-explained conventional appliance as shown
FIG. 7
, this appliance is designed by that a total value of maximum rated electric power of the respective electric components does not exceed an upper limit value which is determined with respect to entire power consumption of this conventional appliance.
In other words, even when the ventilation means and/or the illumination means are not operated, the total power consumption thereof is not added to the high frequency electric power used to heat the object to be heated. Also, since the power control operation performed when the heat cooking operation is carried out is realized by interrupting constant high frequency output power, the proper high frequency output power cannot be supplied in response to heating conditions of the object to be heated during the cooking operation, which may cause fluctuations in cooking performance to be extended. Furthermore, the LC power supply is a heavy weight object having a weight of approximately 10 KG including a high voltage transformer and a high voltage capacitor. Moreover, in the case that this heavy-weight appliance whose gravity center is considerably deviated qn the side of the electric chamber is installed, installation works thereof are necessarily required by conducting a plurality of workers. Therefore, there is a problem as to a safety characteristic with respect to such an aspect that after the heavy-weight appliance whose gravity center is deviated is installed, since a strength of a wall plane is not sufficiently large, such a heavy weight appliance is not fixed under stable condition.
Futhermore, in the above-explained conventional arrangement, since the power consumption used other than the oscillation of the electromagnetic waves is continuously constant after the heating operation is commenced, there is an upper limit in electric power which is used to oscillate the electromagnetic waves. Therefore, there is a problem that the heating time cannot be shortened.
Also, inversely in order secure a large amount of electric power so as to oscillate the electromagnetic waves, if the cooling means such as the fan is eliminated, then another problem will occur. Namely, reliability of the microwave oven is deteriorated, for instance, the break down of the electromagnetic wave radiation unit such as the magnetron occurs due to the temperature increase. Also, if the illumination means such as the lamp is eliminated, then there is another problem that the progressive degrees of the heating operation cannot be observed outside this microwave oven. When the food mounting means such as the turn table is eliminated, the food cannot be uniformly heated. As a result, there is another problem that the quality of the cooking result is fluctuated.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above-described problems of the prior art, and therefore, has an object to provide a high frequency heating apparatus capable of deriving maximum high frequency electric power from a limited power consumption regulating value, capable of deriving cooking performance in maximum, and also capable of largely improving an installation workability of an appliance and a safety characteristic of fixing the appliance after the insta
Inada Ikuhiro
Ishiguro Toshiyuki
Matsuda Masato
Migaki Fumihiko
Yamauchi Masato
Leung Philip H.
Pearne & Gordon LLP
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