Electric heating – Microwave heating – With control system
Reexamination Certificate
2001-12-13
2004-04-13
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
With control system
C219S754000, C219S749000, C219S494000, C374S149000, C099S325000
Reexamination Certificate
active
06720541
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a high-frequency heating apparatus for heating a single object and for simultaneously heating a plurality of objects which have different temperatures at the start of heating or different heat absorbing capacities, and also to a heating method.
BACKGROUND ART
Examples of conventional apparatuses of this kind are disclosed in the Unexamined Japanese Patent Application Publication Nos. Hei6-201137 and No. Hei9-27389 and control the heating of objects based on a detection signal from a temperature detection means.
FIGS. 22 and 23
show a combination of a temperature detection means
2
for an object
1
being heated, which is described in the Unexamined Japanese Patent Application Publication No. Hei6-201137, and a mounting table
3
.
FIG. 22
shows an apparatus which includes amounting table
3
mounted with an object
1
and adapted to be rotated and a temperature detection means
2
for the object
1
. An infrared sensor is used for the temperature detection means
2
, and the radius segment of the rotatable mounting table
3
is taken as an angle of view.
FIG. 23
shows an apparatus in which the infrared sensor is swung by a drive means
4
so that the radius segment of the mounting table
3
defines a view angle. In either case, temperature detection means
2
is situated above a heating chamber
5
.
According to the Unexamined Japanese Patent Application Publication No. Hei9-27389, as shown in FIG.
24
and
FIG. 25
, the apparatus has a plurality of power feed portions
11
a
,
11
b
for supplying high frequency electromagnetic wave and alternately switches between these power feed portions to perform concentrated or distributed heating to eliminate temperature variations. This apparatus is intended to heat a single object.
In
FIGS. 24 and 25
, the apparatus has a temperature detection means
13
for an object
12
being heated, a plurality of power feed portions
11
a
,
11
b
for feeding high frequencies to a heating chamber
14
, and a distribution change means
15
for changing the positions of the power feed portions
11
. There are a plurality of power feed portions
11
and they are alternately switched on to perform concentrated or distributed heating thereby eliminating temperature variations. When the peripheral portion of the object
12
on a rotating table
16
becomes hot, the power feed portion
11
a
is opened to switch to the concentrated heating of the central part. When the central part of the object
12
on the rotating table
16
becomes hot, the power feed portion
11
b
is opened to switch to the distributed heating over a wide area.
Further, the same official gazette also discloses another apparatus which, as shown in
FIGS. 26
to
28
, has a combination of a temperature detection means
18
for an object
17
and amounting table
19
that does not rotate, with an infrared sensor as the temperature detection means
18
arranged to take the entire mounting table
19
as its view angle. The apparatus also includes a shield plate
21
formed with an opening as a power feed portion
20
a
and a shield plate
22
formed with an opening as a power feed portion
20
b
. The shield plates
21
,
22
are rotated in combination. When the peripheral portion of an object
17
becomes hot, the rotation combination is switched so that the central part of the power feed portion
20
a
is open. When the central part of the object
17
becomes hot, the rotation combination is switched so that the peripheral part of the power feed portion
20
a
is open. The power feed portions
20
a
,
20
b
are situated immediately below a bottom surface wall of the mounting table
19
and the temperature detection means
18
is situated above a top surface wall of a heating chamber
23
.
That is, the apparatus of the Unexamined Japanese Patent Application Publication No. Hei6-201137 uses a combination of the rotating table and the temperature detection means, which takes almost the radius segment of the rotating table as its view angle. The apparatus of the Unexamined Japanese Patent Application Publication No. Hei9-27389 has a plurality of power feed portions for supplying a high-frequency radiation and performs local heating by selecting one of the power feed portions and uniform heating by alternately turning them on. Further, the other apparatus of the Unexamined Japanese Patent Application Publication No. Hei9-27389 combines the non-rotating mounting table
19
with the temperature detection means which takes almost the entire mounting table
19
as the angle of view.
DISCLOSURE OF INVENTION
However, the conventional configurations all heat the objects under the same condition (same temperature, same kind and same heat absorbing capacity). Hence, the angle of view of the temperature detection means does not matter much.
When the heating that applies a high frequency radiation to all objects is combined with the heating that high-frequency-heats a particular object concentratedly as in this embodiment, new problems arise in realizing the simultaneous heating of a plurality of objects having different temperatures at the start of heating or different heat absorbing capacities to the same temperature, not possible with the conventional high-frequency heating apparatus.
That is, when a plurality of objects are heated simultaneously, if a temperature difference between the objects being heated is detected, the rotation of the mounting table is stopped so that the lower-temperature object is situated near the power feed portion for concentrated heating by the high-frequency radiation. Hence, the temperature of the object on the mounting table near the power feed portion must be able to be detected by the temperature detection means. In the case of the temperature detection means which uses roughly a radius segment of the mounting table at a particular location as its angle of view, if the positions of the power feed portion and the temperature detection means are not appropriate, the temperature of the object cannot be detected.
Further, one of the apparatus disclosed in the Japanese Patent Application Publication No. Hei9-27389 basically performs heating by rotating the mounting table to heat the objects evenly and, when temperature variations occur, the heating mode is switched to a concentrated heating or distributed heating to eliminate the temperature variations. Another apparatus basically performs heating by moving the power feed portion, rather than rotating the mounting table, to heat the objects evenly and, when temperature variations occur, the apparatus switches the power feed portion to the central or peripheral one to effect the concentrated heating and thereby eliminate the temperature variations. With these conventional apparatus, however, the power feed portion is moved and rotated and a waveguide
24
and power feed portions
20
a
,
20
b
are located at positions directly connected to a high-frequency generation means
25
where the electric field intensity is very strong. Moving the waveguide
24
and power feed portions formed of a metal (they are difficult to fabricate using materials other than metals) at positions exposed to a strong electric field will easily result in such phenomena as heating and spark due to electric field concentrations. Hence, the practical use of this arrangement is very difficult to realize.
Further, when a plurality of objects with different heat absorbing capacities, such as milk in a large cup and milk in a small cup, are to be heated simultaneously by the conventional apparatus of these arrangements, it is likewise not possible to simultaneously heat a plurality of objects to the same temperatures.
The present invention has been accomplished to solve the problems described above and provide a high-frequency heating apparatus and a heating method which can eliminate the necessity of moving and rotating the power feed portion and which can not only heat a single object to an appropriate temperature but also simultaneously heat a plurality of objects in different states having diff
Fujishita Kazuo
Fukumoto Akemi
Mizuta Isao
Nobue Tomotaka
Takizaki Takesi
Leung Philip H.
Matsushita Electric - Industrial Co., Ltd.
Pearne & Gordon LLP
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