JP2003325329A - rice cooker - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To convert into high frequency power by an inverter circuit,
In a rice cooker in which an inner pot is induction-heated by a heating coil,
With a simple adjustment, a power fluctuation factor due to a variation in circuit constant or the like is removed, and stable performance is obtained even when a power supply voltage changes. SOLUTION: An inner pot 19 for holding a food is heated by a heating coil 2.
0 and induction heating by applying high-frequency power to the inner pan 1
The temperature of the food in 9 is detected by the temperature detecting means 21. Based on the value obtained by the current detection means 25 for measuring the current supplied from the commercial power supply 22, the current control means 26 controls the current to a predetermined current value, and the power supply voltage detection means 27 controls the power supply voltage. Measure and power control means 2
8, the power is controlled to be constant by lowering the power supply current by an amount corresponding to the power supply voltage being higher than the predetermined voltage value, and how much the predetermined voltage value of the voltage changing means 30 that changes the predetermined voltage value is changed. The input means 29 is configured to input.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker in which high frequency power is converted by an inverter circuit and an inner pot is induction-heated by a heating coil.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a rice cooker which has good cooking performance and can be manufactured more efficiently.

Conventionally, this type of rice cooker has been constructed as shown in FIG. Hereinafter, description will be given with reference to FIG.

As shown in FIG. 9, an inner pot 1 is filled with a food and is heated by a heating coil 2 by electromagnetic induction (hereinafter referred to as IH). The commercial power supply 3 supplies alternating current to the diode bridge 4 and is rectified by the diode bridge 4.
The inverter circuit including the smoothing capacitor 5, the resonance capacitor 6, the switching element 7, and the heating coil 2 causes
Generates high frequency power for H.

The power value is controlled by controlling the power supply current. First, a power supply current is input to the primary side of the current transformer 8, the output value of the secondary side of the current transformer 8 is divided by a resistor, rectified by a diode bridge 9, smoothed by a capacitor 10, and a positive input of a comparator 11. Input to the terminal. Comparator 1
1 compares this input value with a predetermined voltage input to the negative input terminal, and if the input value is smaller than the predetermined voltage, low output is performed, and if it is larger, high output is performed.

The IC 12 and the IC 13 control the IH so that the power supply current is constant so that the power supply current is increased when the comparator 11 is low output and the power supply current is decreased when the comparator 11 is high output.

For the detection of the power supply voltage, half-wave rectification is performed from the commercial power supply 3 by the diode 14, the voltage is divided by the resistance such as the variable resistance 15, and the capacitor 17 is supplied via the transistor 16.
Is smoothed and input to the microcomputer 18.

When the power supply voltage becomes higher, the power naturally increases, but when the power becomes higher, there is a problem in cooking performance such as spillage and strong burning of rice. Therefore, the power supply voltage becomes high. If it does, the power supply current value is reduced accordingly and the power is kept constant.

For example, in the case of a rice cooker having an electric power of 1200 W, the power source current is 12.0 A when the power source voltage is 100 V.
The power is 1200 W, but the power supply voltage is 11
When 0V is detected by the microcomputer 18, the microcomputer 18 changes the voltage on the negative terminal side of the comparator 11 by the DA output to change the power supply current to 1
Reduced to 0.9A, 110V x 10.9A = 1199
The processing is performed so that W and power are almost constant.

[0010]

In such a conventional rice cooker which performs a process of changing the power supply current value according to the power supply voltage to make the electric power constant, the power supply voltage is accurately detected to some extent. Although it is necessary, since the input value to the microcomputer 18 fluctuates due to noise, variations in circuit constants, etc., the fluctuation is suppressed by adjusting the resistance value of the variable resistor 15 to ensure accuracy. .

However, the adjustment of the variable resistor 15 is time-consuming in manufacturing the rice cooker, and a more efficient adjustment method has been awaited.

The present invention solves the above-mentioned problems of the prior art. It is easy to manufacture and can eliminate the factors of power fluctuation due to variations in circuit constants by easy adjustment. Stable performance even when the power supply voltage changes. The aim is to get a rice cooker.

[0013]

In order to achieve the above object, the present invention induction-heats an inner pot containing a food by a heating coil and detects the temperature of the food in the inner pot by a temperature detecting means. , A DC power source obtained by rectifying the commercial power source is converted into a high frequency power by an inverter circuit, and the current is controlled by the current control unit based on the value obtained by the current detection unit that measures the current supplied from the commercial power source. Control so that the current value, the power supply voltage detection means to measure the power supply voltage, the power control means to reduce the power supply current by the amount of the power supply voltage is higher than a predetermined voltage value to control the power constant, The input means is used to input how much the predetermined voltage value of the voltage changing means for changing the predetermined voltage value is changed.

With this, it is possible to remove the factors of power fluctuation due to variations in circuit constants, etc., by easy adjustment,
A rice cooker that is easy to manufacture and has stable performance even when the power supply voltage changes can be obtained.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is an inner pot in which a food is put, a temperature detecting means for detecting the temperature of the food in the inner pan, and an induction heating of the inner pan. A heating coil and a DC power supply obtained by rectifying a commercial power supply,
An inverter circuit for converting the DC power supply into high frequency power, a current detection means for measuring a current supplied from a commercial power supply, and a current control based on a value obtained by the current detection means so that the current has a predetermined current value. Current control means, a power supply voltage detection means for measuring the power supply voltage, a power control means for constantly controlling the power by lowering the power supply current by the amount of the power supply voltage higher than a predetermined voltage value, and the predetermined power supply means. The power control means is provided with a voltage changing means for changing the voltage value and an input means for inputting how much the predetermined voltage value is changed, and the power control means is a power source for the power supply voltage higher than the predetermined voltage. The operation to keep the power constant by lowering the current is performed.
In order to obtain the same electric power when AC 100V is applied when 10V is applied, the power supply current must be reduced by 10V AC.

However, if 110V AC is applied by the power supply voltage detecting means due to variations in circuit constants and the like, the power correction does not work normally and the power value may show an abnormal value. In such a case, the power value indicates a normal value by changing the predetermined voltage value of the power control means by the voltage changing means by the input from the input means (in this case, lowering by 1 V AC). As described above, the variation in the circuit constant can be absorbed, and the adjustment can be easily performed.

According to a second aspect of the present invention, in addition to the first aspect of the present invention, display means for displaying the detection value of the power supply voltage detection means is added. While it can be adjusted, it can be adjusted more easily.

According to a third aspect of the present invention, in the above-mentioned first aspect of the invention, the input means is adapted to be input by a switch. It is possible to change the predetermined voltage value used by the power control means by key input,
It can be easily adjusted.

According to a fourth aspect of the present invention, in the above first aspect of the invention, a terminal connecting portion is provided so that an electric signal can be input, and the input means inputs the electric signal from the terminal connecting portion. By providing a terminal connection portion to which an electric signal can be input, the predetermined voltage value used by the electric power control means can be changed by an electric signal from the equipment from the outside, and it can be easily adjusted. it can.

According to a fifth aspect of the present invention, in the first aspect of the present invention, a radio signal receiving means is provided, and the input means inputs the radio signal from the radio signal receiving means. By providing the wireless signal receiving means, the predetermined voltage value used by the power control means can be changed by an external wireless signal, and the adjustment can be easily performed.

According to a sixth aspect of the present invention, in the first aspect of the present invention, there is provided a heating test mode in which water is put in an inner pot to heat and boil, and the power supply voltage is a predetermined value used by the power control means. Voltage is higher than the above voltage, the strength of heating is judged from the temperature rise time of the water in the heating test mode, and the voltage correction means for changing the predetermined voltage value used by the power control means is added from the result. If the power supply voltage is higher than the predetermined voltage used by the power control means due to the temperature rise time of water, the strength of heating is judged, and from the result, the power supply voltage detection means accurately detects the power supply voltage, Alternatively, since it is not accurately detected due to variations in circuit constants, etc., it is determined whether the power value is within the standard value, and the predetermined voltage value used by the voltage correction unit is changed to change the power value. It can be due to variations in adjustments to correct for variations in power value.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) As shown in FIG. 1, an inner pot 19
Puts a cooking product, and induction heating is performed by the heating coil 20. The temperature of the food in the inner pan 19 is detected by the temperature detecting means 21. The AC voltage supplied from the commercial power supply 22 is rectified to obtain the DC power supply 23, and the inverter circuit 24
A DC voltage is supplied to generate high frequency power for IH.

The current detection means 25 detects the power supply current, and the current control means 26 controls the inverter circuit 24 based on the detected current value so that the power supply current becomes constant at a predetermined value, thereby controlling the power value. It is carried out. The power supply voltage detection means 27 detects the power supply voltage supplied from the commercial power supply 22, and the power control means 28 operates to keep the power constant by lowering the power supply current by the amount that the power supply voltage becomes higher than a predetermined voltage. To do.

If the detected value of the power supply voltage detecting means 27 deviates from the normal value due to variations in circuit constants, the electric power correction by the electric power control means 28 does not work normally, and the electric power value shows an abnormal value. In such a case, by changing the predetermined voltage value of the power control means 28 by the voltage changing means 30 by the input from the input means 29, the power value is adjusted so as to show a normal value. ,
It is possible to easily absorb a shift due to variations in circuit constants.

Further, at the time of the adjustment, by displaying the detection value of the power supply voltage detection means 27 on the display means 31, the adjustment can be performed while watching the detection value of the power supply voltage detection means 27, so that the adjustment becomes easier. .

FIG. 2 is a specific circuit diagram. In FIG. 2, the cooking product is put in the inner pot 19 and induction heating is performed by the heating coil 20. The thermistor 32 constitutes the temperature detecting means 21, and the temperature of the food in the inner pot 19 is detected by inputting the partial pressure of the thermistor 32 and the resistance to the AD input of the microcomputer 33. Commercial power supply 2
The AC voltage is supplied from 2 and is rectified by the diode bridge 34 to obtain the DC power supply 23.

The inverter circuit 24 includes the smoothing capacitor 3
5, the resonance capacitor 36, the switching element 37, and the heating coil 20. The inverter circuit 24 generates high-frequency power for IH.

The current transformer 38 is the current detecting means 2
5, the power supply current is input to the primary side thereof, the output value of the secondary side of the current transformer 38 is divided by a resistor, rectified by the diode bridge 39, smoothed by the capacitor 40, and the positive input of the comparator 41. Input to the terminal. The comparator 41 compares the input value with the voltage input to the minus input terminal, and outputs a high output when the input value on the plus input terminal side is larger than that on the minus input terminal side, and a low output when the input value is smaller.

The IC 42 and the IC 43 control the IH so that the power supply current is constant so that the power supply current is increased when the comparator 41 is low output and is decreased when the comparator 41 is high output.

To detect the power supply voltage, half-wave rectification is performed from the commercial power supply 22 by the diode 44, the voltage is divided by a resistor, smoothed by the capacitor 46 via the transistor 45, and input to the microcomputer 33. When the power supply voltage becomes high, the microcomputer 33 performs a process of keeping the power constant by lowering the power supply current value accordingly. The liquid crystal display element 47 constitutes the display means 31.

The operation of the above configuration will be described. First,
Considering the operation when there is no variation in circuit constants,
When the power supply voltage is 100 V, the microcomputer 33
If the voltage V1 is input to the microcomputer 33 and the voltage V2 is input to the microcomputer 33 when the power supply voltage is 110 V, the power supply voltage is 1
The operation of reducing the power supply current at 10 V by (V2-V1) is performed.

However, if the power supply voltage is 110V, the input voltage will be V if the circuit constants vary.
In the case of 2 + α, a process of reducing the power supply current by (V2 + α−V1) is performed, which causes a deviation from the power supply current that is actually reduced by (V2-V1).

Therefore, the power value at 110V is also (V2 + α-V1-α) by adjusting V1 to V1 + α while observing the power value at 110V.
Since (= V2-V1), it is possible to eliminate a shift due to variations in circuit constants.

By displaying the input value of the power supply voltage to the microcomputer 33 on the liquid crystal display element 47, the adjustment can be performed while observing the input value of the microcomputer 33, and the adjustment becomes easier.

(Embodiment 2) As shown in FIG. 3, the switches 48 and 49 constitute the input means 29. The switches 48 and 49 change how much a predetermined voltage value used as the power control means 28 changes. I'm trying to enter what to do. Other configurations are the same as those in the first embodiment, and the same reference numerals are given and the description thereof is omitted.

The operation of the above configuration will be described. The adjustment can be performed by increasing the predetermined voltage used by the microcomputer 33 as the power control means 28 by the input from the switch 48 and decreasing it by the input from the switch 49. By using the switch 48 and the switch 49 as the input means 29, adjustment can be facilitated by inputting the switch from the outside.

(Embodiment 3) As shown in FIG. 4, the terminal connecting portions 50 and 51 constitute the input means 29 and are adapted to input an electric signal. As shown in FIG. 5, the terminal connecting portion 50 is mounted on the substrate 52, and the terminal connecting portion 50 is attached.
There is a small hole on the top and the adjustment equipment 5
An electric signal can be input to the terminal connecting portion 50 by inserting the needle-shaped adjusting input terminal 54 protruding from the terminal 3 and bringing it into contact with the terminal connecting portion 50. Other configurations are the same as those in the first embodiment, and the same reference numerals are given and the description thereof is omitted.

The operation of the above configuration will be described. By the input from the terminal connection unit 50, the microcomputer 33 increases a predetermined voltage used as the power control unit 28,
The adjustment can be performed by lowering it by the input from the terminal connecting portion 51.

In this way, the terminal means 5 is connected to the input means 29.
The use of 0 and 51 facilitates the adjustment using the equipment by the electric signal input from the outside.

(Embodiment 4) As shown in FIG. 6, the radio antenna 55 and the radio IC 56 constitute radio signal receiving means, and are adapted to input radio signals. Other configurations are the same as those in the first embodiment, and the same reference numerals are given and the description thereof is omitted.

The operation of the above configuration will be described. Adjustment can be performed by raising or lowering a predetermined voltage used by the microcomputer 33 as the power control means 28 by a signal from the antenna 55.
By using wireless as the input means, adjustment from the outside can be easily performed.

(Embodiment 5) As shown in FIG. 7, the voltage correction means 57 corrects the predetermined voltage value used by the power control means 28 and is larger than the predetermined voltage used by the power control means 28. At the voltage, put water in the inner pot 19,
It is operated in a heating test mode in which it is heated and boiled, the temperature rise of the water at that time is measured by the temperature detection means 21, and the predetermined voltage value used by the power control means 28 is corrected from the result. Other configurations are the same as those in the first embodiment, and the same reference numerals are given and the description thereof is omitted.

The operation of the above configuration will be described. Figure 8
Is an example of a temperature graph at the time of boiling water at a voltage higher than a predetermined voltage used by the power control unit 28, and shows a curve like B in the case of just right power, but shows a curve like B in the case of too high power. A curve like A is shown because it boils quickly, and a curve like C is shown because it takes time to boil when the power is too small. Therefore, in the case of A or C, the voltage correction means 57 changes the predetermined voltage used by the power control means 28 to realize an appropriate power. The correction range is determined by the time required for boiling.

In this embodiment, one temperature detecting means is used, but it goes without saying that the same effect can be obtained by using a plurality of temperature detecting means to increase the temperature.

[0046]

As described above, according to the invention described in claim 1 of the present invention, an inner pot for containing a food, a temperature detecting means for detecting the temperature of the food in the inner pan, and the inner A heating coil for induction heating the pot, a DC power supply obtained by rectifying a commercial power supply, an inverter circuit for converting the DC power supply to high frequency power, a current detection means for measuring a current supplied from the commercial power supply, Current control means for controlling the current to a predetermined current value based on the value obtained from the current detection means, power supply voltage detection means for measuring the power supply voltage, and the amount by which the power supply voltage becomes higher than the predetermined voltage value. Since it comprises a power control means for controlling the power to a constant level by lowering the power supply current, a voltage changing means for changing the predetermined voltage value, and an input means for inputting how much the predetermined voltage value is changed. , It is possible to eliminate the variation factors of the power due to variation in the circuit constant at ease Do adjustment,
A rice cooker that is easy to manufacture and has stable performance even when the power supply voltage changes can be obtained.

Further, according to the invention described in claim 2, since the display means for displaying the detection value of the power supply voltage detection means is added, it is possible to adjust while watching the detection value of the power supply voltage detection means. It can be easily adjusted.

According to the third aspect of the invention, since the input means is input by the switch, the power control means is used by key input from the outside by inputting by key input as the input means. The predetermined voltage value to be applied can be changed and can be easily adjusted.

According to the invention of claim 4, the terminal connecting portion is provided so that the electric signal can be input, and the input means inputs the electric signal from the terminal connecting portion. By providing the terminal connection part for inputting, it is possible to change the predetermined voltage value used by the power control means by an electric signal from the outside, and it can be easily adjusted.

According to the invention of claim 5, the radio signal receiving means is provided, and the input means receives the radio signal from the radio signal receiving means. Therefore, the power control is performed by the radio signal from the outside. The predetermined voltage value used by the means can be varied and can be easily adjusted.

Further, according to the invention of claim 6, there is provided a heating test mode in which water is put in an inner pot to heat and boil, and when the power supply voltage is higher than a predetermined voltage used by the power control means. The strength of heating is determined from the temperature rise time of water in the heating test mode, and the voltage correction means for changing the predetermined voltage value used by the power control means is added from the result, so that the temperature rise time of water is It is possible to automatically correct fluctuations in power value due to fluctuations in circuit constants, fluctuations in power value adjustment, and the like, which makes it easy to manufacture and to obtain a rice cooker with stable performance even when the power supply voltage changes.

[Brief description of drawings]

FIG. 1 is a block diagram of a rice cooker according to a first embodiment of the present invention.

[Fig. 2] Partial block circuit diagram of the rice cooker

FIG. 3 is a partially block circuit diagram of a rice cooker according to a second embodiment of the present invention.

FIG. 4 is a partially block circuit diagram of a rice cooker according to a third embodiment of the present invention.

[Figure 5] Side view of the main part of the rice cooker

FIG. 6 is a partially block circuit diagram of a rice cooker according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram of a rice cooker according to a fifth embodiment of the present invention.

FIG. 8 is a time chart showing the temperature rise of water in the rice cooker.

FIG. 9 is a circuit diagram in which a conventional rice cooker is partially blocked.

[Explanation of symbols] 19 inner pot 20 heating coil 21 Temperature detection means 22 Commercial power supply 23 DC power supply 24 Inverter circuit 25 Current detection means 26 Current control means 27 Power supply voltage detection means 28 Power control means 29 Input means 30 voltage changing means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 6/12 335 H05B 6/12 335 F term (reference) 3K051 AA01 AC03 AC07 AC09 AC33 AD04 AD13 AD15 AD40 CD14 CD40 4B055 AA03 BA29 BA62 CA71 CD01 CD02 CD41 CD51 CD72 CD73 CD80 DB14

Claims (6)

[Claims] Claim: What is claimed is: 1. An inner pot for holding food, a temperature detecting means for detecting the temperature of the food in the inner pot, a heating coil for inductively heating the inner pan, and a direct current obtained by rectifying a commercial power source. A power supply, an inverter circuit for converting the DC power supply into high frequency power, a current detection means for measuring a current supplied from a commercial power supply, and a current having a predetermined current value based on a value obtained by the current detection means. A current control means for controlling the power supply voltage, a power supply voltage detection means for measuring the power supply voltage, and a power control means for constantly controlling the power by lowering the power supply current by the amount by which the power supply voltage becomes higher than a predetermined voltage value, A rice cooker comprising voltage changing means for changing the predetermined voltage value and input means for inputting how much the predetermined voltage value is changed. 2. The rice cooker according to claim 1, further comprising display means for displaying a detection value of the power supply voltage detection means. 3. The rice cooker according to claim 1, wherein the input means is a switch. 4. The rice cooker according to claim 1, wherein a terminal connecting portion is provided so that an electric signal can be input, and the input means inputs the electric signal from the terminal connecting portion. 5. The rice cooker according to claim 1, further comprising wireless signal receiving means, wherein the input means inputs the wireless signal from the wireless signal receiving means. 6. A heating test mode in which water is put in an inner pot to heat and boil, and heating is performed from the temperature rise time of water in the heating test mode when the power supply voltage is higher than a predetermined voltage used by the power control means. 2. The rice cooker according to claim 1, further comprising voltage correction means for judging the strength of the electric power, and changing the predetermined voltage value used by the electric power control means from the result.