TECHNICAL FIELD
[0001] The present invention relates to an induction heating cooker.
BACKGROUND ART
[0002] Recently, in induction heating cookers, there is a machine type in which an infrared
sensor installed below a top plate detects a temperature of a cooking container such
as a pan placed on a top plate, and heating control is performed in accordance with
detected temperature information (e.g., see PTL 1).
[0003] FIG. 4 is a schematic diagram illustrating an example of a conventional induction
heating cooker. This conventional technology is described with reference to FIG. 4.
[0004] In FIG. 4, cooking container 10 for storing a cooking material is placed on top plate
20 configured by a non-magnetic body. Induction heating coil 30 generates an induction
field for inductively heating cooking container 10.
[0005] Infrared sensor 80 includes a photodiode, receives an infrared ray emitted from cooking
container 10 through top plate 20, and detects temperature information of cooking
container 10. Power supply and controller 50 adjusts a drive signal output from inverter
40, in accordance with the temperature information detected by infrared sensor 80,
and controls a high-frequency current generated by induction heating coil 30.
[0006] In the above configuration, a light receiving sensitivity wavelength region of infrared
sensor 80 is designed so as to overlap with an infrared ray transmission wavelength
region of top plate 20, and therefore infrared sensor 80 can detect the temperature
of cooking container 10 with good response. Power supply and controller 50 suitably
controls the temperature of cooking container 10 based on this detected result.
Citation List
Patent Literature
[0007] PTL 1: Unexamined Japanese Patent Publication No.
2005-63881
SUMMARY OF THE INVENTION
[0008] However, the infrared sensor is generally more expensive than a temperature sensor
having a simple configuration such as a thermistor, and therefore in an induction
heating cooker having a plurality of induction heating coils, when an infrared sensor
is provided in association with each of the induction heating coils, a total cost
increases.
[0009] In a case where heating control is performed by use of the infrared sensor, a controller
configured by a microcomputer needs to convert an output signal from the infrared
sensor into temperature information which can be used in control of a heating output.
Furthermore, the controller sometimes corrects the temperature information in accordance
with the temperature information of the infrared sensor.
[0010] Therefore, in order to perform a complicated process of performing heating control
by use of a current heating output and temperature information, the controller needs
to previously store data necessary for the process.
[0011] As a result, in the induction heating cooker that controls each inverter in accordance
with an output of each of the plurality of infrared sensors provided in association
with the plurality of induction heating coils, and drives each induction heating coil,
an expensive microcomputer having large storage capacity and high processing capacity
needs to be used as the controller, in order that the single controller controls all
of operation,
[0012] The present invention has been made in order to solve the above conventional problem.
[0013] An induction heating cooker of the present invention includes: a top plate for allowing
a cooking container to be placed; and first and second induction heating units that
are provided below the top plate, and inductively heat the cooking container.
[0014] Each of the first and second induction heating units includes: a plurality of induction
heating coils; a plurality of inverters that individually drive the plurality of induction
heating coils; a temperature detector that detects a temperature of the cooking container;
and a power supply and controller that supplies power to the inverters, and controls
the inverters in accordance with an output of the temperature detector.
[0015] In the first induction heating unit, the temperature detector has a first infrared
sensor that is an only infrared sensor, and the first infrared sensor is provided
in association with one of the induction heating coils provided at a foremost position.
In the second induction heating unit, the temperature detector has a second infrared
sensor that is an only infrared sensor, and the second infrared sensor is provided
in association with one of the induction heating coils provided at a rearmost position.
[0016] According to the present invention, it is possible to configure a lower cost induction
heating cooker enabling high accurate heating control by temperature detection with
good responsiveness, in spite of a configuration in which heating control is performed
by use of more expensive infrared sensors.
BRIEF DESCRIPTION OF DRAWINGS
[0017]
FIG. 1 is a schematic diagram illustrating a configuration of an induction heating
cooker according to a first exemplary embodiment.
FIG. 2 is a schematic diagram illustrating a configuration of an induction heating
cooker according to a second exemplary embodiment.
FIG. 3 is a schematic diagram illustrating a configuration of an induction heating
cooker according to a third exemplary embodiment.
FIG. 4 is a schematic diagram of a conventional induction heating cooker.
DESCRIPTION OF EMBODIMENTS
[0018] A first aspect of the invention includes: a top plate for allowing a cooking container
to be placed; and first and second induction heating units that are provided below
the top plate, and inductively heat the cooking container.
[0019] Each of the first and second induction heating units includes: a plurality of induction
heating coils; a plurality of inverters that individually drive the plurality of induction
heating coils; a temperature detector that detects a temperature of the cooking container;
and a power supply and controller that supplies power to the inverter, and controls
the inverter in accordance with an output of the temperature detector.
[0020] In the first induction heating unit, the temperature detector has a first infrared
sensor that is an only infrared sensor, and the first infrared sensor is provided
in association with one of the induction heating coils provided at a foremost position.
In the second induction heating unit, the temperature detector has a second infrared
sensor that is an only infrared sensor, and the second infrared sensor is provided
in association with one of the induction heating coils provided at a rearmost position.
[0021] According to the present invention, for example, in a case of an induction heating
cooker in which each of the first and second induction heating units has two induction
heating coils arranged at a front and a rear, and the first and second induction heating
units are arranged on right and left sides, in the first induction heating unit, the
infrared sensor is provided only in the front induction heating coil, and in the second
induction heating unit, the infrared sensor is provided only in the rear induction
heating coil.
[0022] A user simply uses the front induction heating coil of the first induction heating
unit in sauteing cooking in which lifting operation of a cooking container is often
performed, and simply uses the rear induction heating coil of the second induction
heating unit in simmering cooking in which the lifting operation of the cooking container
is hardly performed.
[0023] Thus, even a configuration, in which infrared sensors are not necessarily provided
in association with all induction heating coils, does not cause any practical problem.
Accordingly, according to the present invention, it is possible to configure a lower
cost induction heating cooker enabling high accurate heating control by temperature
detection with good responsiveness.
[0024] According to a second aspect of the invention, in the first aspect of the invention,
the first induction heating unit is provided with the infrared sensor below the top
plate, and the second induction heating unit is provided with the infrared sensor
above the top plate and behind the one of the induction heating coils provided at
the rearmost position.
[0025] According to the present invention, as to the second induction heating unit, the
top plate or the like does not exist between the infrared sensor and the cooking container,
and therefore there is less possibility that an infrared ray is attenuated before
reaching the infrared sensor.
[0026] Additionally, as to the second induction heating unit, the infrared sensor is disposed
at a further rear position with respect to the one of the induction heating coils
located at the rearmost position, and therefore there is less possibility that other
cooking container or the like is placed between the infrared sensor and the cooking
container, and an infrared ray is blocked.
[0027] Accordingly, according to the induction heating cooker of the present invention,
it is possible to more accurately perform temperature detection.
[0028] According to a third aspect of the present invention, in the first aspect of the
invention, each of the power supply and controllers has a function of automatic cooking
in which heating control is performed based on a predetermined sequence, one of the
power supply and controllers in the first induction heating unit performs the automatic
cooking by use of the one of the induction heating coils provided at the foremost
position, and another of the power supply and controllers in the second induction
heating unit performs the automatic cooking by use of the one of the induction heating
coils provided at the rearmost position.
[0029] Additionally, the power supply and controllers are configured such that a control
temperature for the automatic cooking in the second induction heating unit is lower
than a control temperature for the automatic cooking in the first induction heating
unit.
[0030] Generally, the sauteing cooking needs higher temperature heating than the simmering
cooking. According to the present invention, the sauteing cooking, in which the lifting
operation of the cooking container is often performed, and the high temperature heating
is needed, can be performed by use of the front induction heating coil of the first
induction heating unit.
[0031] The simmering cooking, in which the lifting operation of the cooking container is
hardly performed, and lower temperature heating is performed compared to the sauteing
cooking, can be performed by use of the rear induction heating coil of the second
induction heating unit.
[0032] Accordingly, it is possible to configure a lower cost induction heating cooker having
excellent operability and enabling high accurate heating control by temperature detection
with good responsiveness.
[0033] Hereinafter, exemplary embodiments of the present invention are described with reference
to drawings. In the following all drawings, the same or corresponding parts are denoted
by the same reference numerals, and overlapped descriptions are omitted.
(FIRST EXEMPLARY EMBODIMENT)
[0034] FIG. 1 is a schematic diagram of an induction heating cooker according to a first
exemplary embodiment of the present invention. With reference to FIG. 1, a configuration
of induction heating cooker 1 according to this exemplary embodiment is described.
In the following description, a side close to a user is represented as a front of
induction heating cooker 1, and a side far from the user is represented as a rear
of induction heating cooker 1.
[0035] As illustrated in FIG. 1, top plate 21 is configured by an electrical insulator such
as glass and ceramic, and configures an upper surface of induction heating cooker
1, for allowing cooking containers 11 and 12 such as pans to be placed.
[0036] Induction heating coil 31, induction heating coil 32, induction heating coil 33,
and induction heating coil 34 are formed in substantially the same shape, have the
same configuration, and are disposed below top plate 21 in a matrix of two rows and
two columns.
[0037] Power supply and controller 51 includes a DC power supply (not illustrated) for rectifying
and smoothing power from a commercial AC power supply, and supplies power to inverter
41 and inverter 42. Additionally, power supply and controller 51 outputs a drive signal
to inverter 41 to control inverter 41, and outputs a drive signal to inverter 42 to
control inverter 42.
[0038] Power supply and controller 52 includes a DC power supply (not illustrated) for rectifying
and smoothing power from a commercial AC power supply, and supplies power to inverter
43 and inverter 44. Additionally, power supply and controller 52 outputs a drive signal
to inverter 43 to control inverter 43, and outputs a drive signal to inverter 44 to
control inverter 44.
[0039] Inverter 41 receives the power and the drive signal from power supply and controller
51 to drive induction heating coil 31. Inverter 42 receives the power and the drive
signal from power supply and controller 51 to drive induction heating coil 32.
[0040] Inverter 43 receives the power and the drive signal from power supply and controller
52 to drive induction heating coil 33. Inverter 44 receives the power and the drive
signal from power supply and controller 52 to drive induction heating coil 34.
[0041] Infrared sensor 81 is a temperature detector configured from an InGaAs pin photodiode
and the like, and is provided near induction heating coil 31, for example, below a
clearance between winding wires located midway between a center and an outer periphery
of annular induction heating coil 31.
[0042] Infrared sensor 81 receives an infrared ray emitted from cooking container 11 placed
above induction heating coil 31 and entering through top plate 21, and outputs a voltage
corresponding to a temperature of cooking container 11.
[0043] Similarly, infrared sensor 82 is a temperature detector configured from an InGaAs
pin photodiode and the like, and is provided near induction heating coil 34, for example,
below a clearance between winding wires located midway between a center and an outer
periphery of annular induction heating coil 34.
[0044] Infrared sensor 82 receives an infrared ray emitted from cooking container 12 placed
above induction heating coil 34 and entering through top plate 21, and outputs a voltage
corresponding to a temperature of cooking container 12.
[0045] An advantage of using the infrared sensor is that thermal responsiveness is good
compared to a case where the temperature of cooking container 11 (or 12) transferred
through top plate 21 is detected by a thermistor or the like, and high accurate temperature
control is possible.
[0046] In this exemplary embodiment, induction heating coils 31 and 32, inverters 41 and
42, power supply and controller 51, and infrared sensor 81 configure induction heating
unit 61 equivalent to a first induction heating unit.
[0047] Induction heating coils 33 and 34, inverters 43 and 44, power supply and controller
52, and infrared sensor 82 configure induction heating unit 62 equivalent to a second
induction heating unit.
[0048] In induction heating unit 61, only infrared sensor 81 is provided as a temperature
detector. Infrared sensor 81 is provided in association with induction heating coil
31 located at a foremost position, among the induction heating coils included in induction
heating unit 61.
[0049] In induction heating unit 62, only infrared sensor 82 is provided as a temperature
detector. Infrared sensor 82 is provided in association with induction heating coil
34 located at a rearmost position, among the induction heating coils included in induction
heating unit 62.
[0050] In this exemplary embodiment, infrared sensor 81 is equivalent to a first infrared
sensor, and infrared sensor 82 is equivalent to a second infrared sensor.
[0051] In order to detect the temperatures of the cooking containers placed above induction
heating coils 32 and 33, temperature sensors that are not infrared sensors, for example,
thermistors may be provided in association with induction heating coils 32 and 33.
In this case, power supply and controllers 51 and 52 control inverters 42 and 43 in
accordance with outputs of the thermistors, respectively.
[0052] Each of power supply and controllers 51 and 52 has a function of automatic cooking
in which heating control is performed based on a predetermined sequence. Infrared
sensor 81 detects the temperature of cooking container 11 placed on induction heating
coil 31, so that power supply and controller 51 performs automatic cooking.
[0053] Infrared sensor 82 detects the temperature of cooking container 12 placed on induction
heating coil 34, so that power supply and controller 52 performs automatic cooking.
In this case, a control temperature for automatic cooking by power supply and controller
52 is set to be lower than a control temperature for the automatic cooking by power
supply and controller 51.
[0054] In this exemplary embodiment, induction heating cooker 1 has sauteing cooking and
simmering cooking as an automatic cooking menu.
[0055] A control temperature for the sauteing cooking is, for example, a temperature selected
from 140°C to 230°C. Power supply and controller 51 controls inverter 41 in accordance
with a temperature detected by infrared sensor 81 such that cooking container 11 is
maintained at the above control temperature.
[0056] Further, a control temperature for the simmering cooking is, for example, a temperature
less than 100°C. Power supply and controller 52 controls inverter 44 in accordance
with a temperature detected by infrared sensor 82 such that cooking container 12 is
maintained at the above control temperature.
[0057] Therefore, a user simply uses front induction heating coil 31 of induction heating
unit 61 in the sauteing cooking in which lifting operation of a frying pan is often
performed, and simply uses rear induction heating coil 34 of induction heating unit
62 in the simmering cooking in which lifting operation of a pan is hardly performed.
[0058] Thus, even a configuration in which infrared sensors are not necessarily provided
in association with all induction heating coils does not cause any practical problem.
Accordingly, according to the present invention, it is possible to configure a lower
cost induction heating cooker enabling high accurate heating control by temperature
detection with good responsiveness.
[0059] In this exemplary embodiment, InGaAs pin photodiodes are used as infrared sensors
81 and 82. However, any components capable of detecting temperatures of bottom surfaces
of cooking containers 11 and 12 by emitted infrared rays, such as silicon photodiodes
and thermopiles, may be employed.
[0060] As described above, according to this exemplary embodiment, it is possible to configure
a lower cost induction heating cooker enabling high accurate heating control by temperature
detection with good responsiveness, in spite of a configuration in which heating control
is performed by use of more expensive infrared sensors than thermistors.
(SECOND EXEMPLARY EMBODIMENT)
[0061] Hereinafter, a second exemplary embodiment of the present invention is described
with reference to FIG. 2. FIG. 2 is a schematic diagram illustrating a configuration
of an induction heating cooker according to this exemplary embodiment.
[0062] As illustrated in FIG. 2, induction heating cooker 2 has induction heating unit 61
disposed on a left side, and induction heating unit 63 disposed on a right side. Induction
heating unit 63 includes induction heating coil 33, induction heating coil 34, inverter
43, inverter 44, infrared sensor 83, and power supply and controller 52.
[0063] Infrared sensor 83 is installed behind induction heating coil 34 and above top plate
21, receives an infrared ray emitted from cooking container 12 placed above induction
heating coil 34, and outputs a voltage corresponding to a temperature of cooking container
12.
[0064] Power supply and controller 52 supplies power to inverters 43 and 44 to control inverter
43 and inverter 44. Additionally, infrared sensor 83 detects the temperature of cooking
container 12 placed on induction heating coil 34, so that power supply and controller
52 performs automatic cooking in which heating control is performed based on a predetermined
sequence.
[0065] In this exemplary embodiment, infrared sensor 81 is equivalent to the first infrared
sensor, and infrared sensor 83 is equivalent to the second infrared sensor.
[0066] This exemplary embodiment is different from the first exemplary embodiment in that
infrared sensor 83 is installed behind induction heating coil 34 and above top plate
21.
[0067] Infrared sensor 83 of this exemplary embodiment directly receives the infrared ray
emitted from the cooking container not through the top plate that absorbs the infrared
ray, and therefore can detect the temperature with high accuracy.
[0068] Further, in this exemplary embodiment, infrared sensor 83 is installed behind cooking
container 12, namely, installed on a side far from a user of cooking container 12,
and therefore there is less possibility that detection operation is obstructed by
the user even when infrared sensor 83 is installed above top plate 21.
[0069] Proper use for these two installation places as to the infrared sensor is, for example,
considered as follows.
[0070] The temperature of the bottom surface of cooking container 12 is higher than a temperature
of a side surface of cooking container 12 due to self-heating by induction heating.
Therefore, according to infrared sensor 82 installed below induction heating coil
34, as shown in the first exemplary embodiment, it is easy to measure a temperature
of the hottest part of cooking container 12. Accordingly, infrared sensor 82 of the
first exemplary embodiment is suitable for automatic cooking at a relatively high
control temperature.
[0071] On the other hand, infrared sensor 83 installed behind induction heating coil 34
and above top plate 21, as shown in this exemplary embodiment detects the temperature
of the side surface of cooking container 12. Therefore, infrared sensor 83 is not
suitable for the automatic cooking at the relatively high control temperature compared
to a case of the first exemplary embodiment.
[0072] However, infrared sensor 83 of this exemplary embodiment enables high accurate temperature
detection as described above, and therefore is suitable for high accurate automatic
cooking at a relatively low control temperature.
[0073] As a place of cooking container 12 whose temperature is detected by infrared sensor
83, for example, a side surface, to which heat of an inductively heated bottom is
unlikely to be transferred, or a vicinity of a boundary between top plate 21 and cooking
container 12 is conceived.
[0074] Particularly, in heating with high heating power, the temperature of the bottom surface
of cooking container 12 is higher than a temperature of a cooking material inside
cooking container 12 due to self-heating by induction heating.
[0075] However, when the temperature of the side surface of cooking container 12 is measured,
the temperature can be detected with relatively less influence of self-heating in
the bottom surface of cooking container 12, and the temperature of the cooking material
can be detected with higher accuracy.
[0076] On the other hand, the vicinity of the boundary between cooking container 12 and
top plate 21 often has a curved surface shape. Therefore, in a case where the temperature
of the vicinity of the boundary between cooking container 12 and top plate 21 is measured,
when this part is irradiated with an infrared ray in accordance with an ambient temperature
that is a noise component, the infrared ray of the noise component is mostly reflected
in a direction of top plate 21 due to the curved surface shape.
[0077] Top plate 21 has a high infrared ray emissivity (infrared ray emissivity = 1.0),
and therefore the infrared ray reflected by cooking container 12 is almost absorbed.
Accordingly, infrared sensor 83 does not detect the infrared ray of the noise component
by the ambient temperature, and influence of noise is hardly received.
[0078] An infrared ray in accordance with heat transferred from cooking container 12 to
top plate 21 due to heat conduction partially directly reaches infrared sensor 83
from top plate 21, and is partially reflected in the vicinity of the boundary between
cooking container 12 and top plate 21 to reach infrared sensor 83.
[0079] Accordingly, even in a case where stainless steel or the like, a temperature of which
is detected to be lower than an actual temperature only by the infrared ray that has
a low infrared ray emissivity, and directly reaches from cooking container 12, is
used as cooking container 12, the temperature of cooking container 12 is corrected
by an infrared ray in accordance with heat transferred to top plate 21, and can be
more accurately detected.
[0080] As described above, in this exemplary embodiment, infrared sensor 81 is provided
below top plate 21 with respect to induction heating coil 31 disposed on a front,
and infrared sensor 83 is provided above top plate 21 with respect to induction heating
coil 34 disposed at a rear.
[0081] According to this exemplary embodiment, when induction heating coil 31 is used, cooking
container 11 is easily lifted up and down, and automatic cooking (for example, sauteing
cooking) at a relatively high control temperature can be performed.
[0082] When induction heating coil 34 is used, even with a configuration where infrared
sensor 83 is provided above the top plate, it is possible to perform high accurate
automatic cooking (for example, simmering cooking) at a relatively low control temperature
without obstruction for temperature detection by infrared sensor 83.
[0083] In this exemplary embodiment, an InGaAs pin photodiode is used as infrared sensor
83. However, any components capable of detecting the temperature of the side surface
of cooking container 12 by an emitted infrared ray, such as a silicon photodiode and
a thermopile, may be employed.
(THIRD EXEMPLARY EMBODIMENT)
[0084] Hereinafter, a third exemplary embodiment of the present invention is described with
reference to FIG. 3. FIG. 3 is a schematic diagram illustrating a configuration of
induction heating cooker 3 according to this exemplary embodiment.
[0085] As illustrated in FIG. 3, induction heating cooker 3 has induction heating unit 64.
Induction heating unit 64 includes induction heating coil 31, induction heating coil
34, inverter 41, inverter 44, infrared sensor 81, infrared sensor 83, and power supply
and controller 53.
[0086] Power supply and controller 53 supplies power to inverters 41 and 44 to control inverter
41 and inverter 44.
[0087] Power supply and controller 53 has a function of automatic cooking in which a temperature
of cooking container 11 placed above induction heating coil 31 is detected by infrared
sensor 81, and heating control is performed based on a predetermined sequence. Similarly,
power supply and controller 53 has a function of automatic cooking in which a temperature
of cooking container 12 placed above induction heating coil 34 is detected by infrared
sensor 83, and heating control is performed based on a predetermined sequence.
[0088] In this exemplary embodiment, infrared sensor 81 is equivalent to the first infrared
sensor, and infrared sensor 83 is equivalent to the second infrared sensor.
[0089] This exemplary embodiment is different from the first and second exemplary embodiments
in that induction heating unit 64 including two induction heating coils 31 and 34
is provided, and infrared sensors 81 and 83 are provided in association with induction
heating coils 31 and 34 respectively.
[0090] Therefore, in a case of this exemplary embodiment, an expensive microcomputer having
large storage capacity and high processing capacity needs to be used as power supply
and controller 53 compared to a case of the first and second exemplary embodiments.
[0091] However, this exemplary embodiment is common to the second exemplary embodiment in
that infrared sensor 81 is provided below top plate 21 with respect to induction heating
coil 31 disposed on a front, and infrared sensor 83 is provided above top plate 21
with respect to induction heating coil 34 disposed at a rear.
[0092] Accordingly, according to this exemplary embodiment, when induction heating coil
31 is used, cooking container 11 is easily lifted up and down, and automatic cooking
(for example, sauteing cooking) at a relatively high control temperature can be performed,
similarly to the second exemplary embodiment.
[0093] Further, when induction heating coil 34 is used, even with a configuration where
infrared sensor 83 is provided above the top plate, it is possible to perform high
accurate automatic cooking (for example, simmering cooking) at a relatively low control
temperature without obstruction for temperature detection by infrared sensor 83.
INDUSTRIAL APPLICABILITY
[0094] As described above, the present invention is applicable to an induction heating cooker
for household or business use.
REFERENCE MARKS IN THE DRAWINGS
[0095]
1, 2, 3 induction heating cooker
10, 11, 12 cooking container
20, 21 top plate
30, 31, 32, 33, 34 induction heating coil
40, 41, 42, 43, 44 inverter
50, 51, 52, 53 power supply and controller
61, 62, 63, 64 induction heating unit
80, 81, 82, 83 infrared sensor