JPH06124778A - Induction heating cooking device - Google Patents

Abstract

PURPOSE:To provide an induction heating cooking unit by which work to optimize a temperature control level of a load caused by a microcomputer can be carried out easily by an external circuit of the microcomputer. CONSTITUTION:A microcomputer 11 has two-system input terminals 11a and 11b, A/D converters 11c and lid and memories 11e, 11f and 11g, and controls an output quantity of an inverter 12 to carry out induction heating on a heating coil 12a, and corrects memory control temperature data by an external correcting means 17. One ends of resistors R24 and R25 are connected respectively to two-system output terminals 11i and 11j of a microcomputer 11, and the other ends are connected to the output end of the external correcting means 17, and a correction quantity changing means 21 is arranged to change output voltage of the external correcting means 17 by turning on and off switches 21 and 22 composed of a transistor or the like inside of the microcomputer 11.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an induction heating cooker.

[0002]

2. Description of the Related Art In recent years, induction heating cookers have been able to adjust the heating output freely by detecting the temperature of the pan by providing a temperature detecting element in the vicinity of the pan of the load, taking advantage of its good heating response. There is an increasing number of things that control the temperature so that cooking can be done.

However, in the induction heating cooker, an element which cannot be understood unless the electric circuit parts are incorporated in the main body and the product is completed, that is, the influence of the main body structure, for example, the influence of electric noise due to the distance from the heating coil, Alternatively, there is a possibility that the temperature control cannot be properly performed due to the influence of the difference in the temperature propagation coefficient from the load to the temperature detection element due to the mounting position of the temperature detection element, and it is necessary to change the control temperature at the final stage of product development. In that case, it takes a long time for the microcomputer to be made into a semiconductor and mask, and it takes time to change the microcomputer. That is, since it takes a lot of development days to change the program contents in the microcomputer, it is the current situation that a great deal of labor and time are spent in the implementation error in the product development process.

Therefore, an induction heating cooker in which the control temperature value can be changed from the outside of the microcomputer has been proposed, and the conventional induction heating cooker will be described below.

FIG. 3 is a block diagram of a conventional induction heating cooker having a temperature control function using a microcomputer.

In FIG. 3, 1 is an input terminal of one system and 5
Microcomputer equipped with a system output terminal, 2 is an inverter drive circuit, 3 is an inverter, 4 is a commercial power source, 5
Is a rectifier circuit, 6 is a load pan, 7 is a DC power supply, and Comp is a comparator, which compares the voltage at the V + and V− points and outputs High when the V− point has a lower potential than the V + point. In the opposite case, Low is output and the output result is input to the input 1 terminal of the microcomputer 1. R1
0 to R16 are resistors, and in particular, the resistors R13 to R16 change the voltage at the V + point by opening or closing the switches SW11 to SW14 formed by transistors or the like in the microcomputer 1.
Reference numeral 8 denotes a thermistor for measuring the temperature of the pan 6 of the load. The thermistor 8 has a resistance value which decreases as the temperature rises. The output voltage Vdd of the DC power supply 7 is set to the thermistor 8
The power source divided by the resistance value of
Is given to. That is, when the temperature rises, the voltage at the V-point also rises.

The operation of the induction heating cooker configured as described above will be described below. The microcomputer 1 outputs a signal for driving the inverter 3 from the output 1 terminal to the inverter drive circuit 2. Receiving the drive signal, the inverter 3 exchanges the direct current obtained by rectifying the commercial power source 4 by the rectifier circuit 5 with a high frequency alternating current, applies a high frequency current to the heating coil 3a, and applies the high frequency magnetic flux generated thereby to the pan 6 of the load. Then, the load pot 6 is heated. First, since the switches SW11 to SW14 are all in the OFF state, the potential at the V + point of the comparator Comp is pulled up to the output voltage Vdd of the DC power supply 7. After this, the microcomputer 1 first closes the switch SW11. Then, the voltage at the V + point becomes the voltage Vdd divided by the resistors R12 and R13, and this voltage is compared with the voltage at the V− point by the comparator Comp. Next, the switch SW11 is turned off and the switch SW12 is turned on. In this way, the switch SW11 sequentially turns on and O
By continuing the FF, the temperature of the pot 6 with the current load is retrieved. For example, when the switch SW13 is turned on,
The voltage at the V + point is a voltage obtained by dividing the voltage Vdd by the combined series resistance value of the resistors R13 to R15 and the resistor R12. At this time, when the voltage at the V− point becomes higher than the voltage at the V + point and the output of the comparator Comp is inverted, the microcomputer 1 determines that the temperature measured by the thermistor 8 at that time is that of the resistors R13 to R15. It is determined that the temperature is set by the combined series resistance. If the temperature is within the control target range, the heating output is adjusted from the output 1 terminal to the inverter 3 and the heating coil 3a through the inverter drive circuit 2 to maintain the temperature, and if it is not within the target range, the heating is continued. The microcomputer 1 outputs a control signal. By repeating this series of operations, the temperature of the pan 6 of the load is controlled.

[0008]

However, in the configuration of the conventional induction heating cooker shown in FIG. 3 described above, at least one output terminal and one resistor are required for setting and changing each control temperature. However, the number of parts is increased, the number of terminals of the microcomputer is increased, and the cost is increased.

Although the load control temperature can be changed from the outside of the microcomputer, the resistances connected to the output terminals of the microcomputer for setting the control temperature are not independent and affect each other. Even if one control temperature is changed, all the resistances must be changed, and the resistance element is generally manufactured with discrete values, so to obtain the desired control temperature. There was a problem that it took a lot of time and effort to design and check the subtle temperature setting.

The present invention solves the above problems and provides an induction heating cooker capable of finely adjusting a temperature control level of a load by a microcomputer and easily performing an operation of optimizing a set heating control temperature. The purpose is to do.

[0011]

The first means of the present invention for solving the above problems includes a heating coil, an inverter for converting direct current into high frequency alternating current, and supplying high frequency current to the heating coil, An inverter drive circuit for controlling the inverter, a temperature measuring means for outputting a signal according to a temperature of a load heated by a magnetic flux generated from the heating coil, an A / D converter and a memory are integrally molded by an insulating member. At the same time, the control temperature data is stored in the memory, the output signal of the temperature measuring means is converted into a digital signal by the A / D converter, and the digital signal is compared with the control temperature data of the memory. For outputting a control signal to the inverter drive circuit, and a path different from the signal of the temperature measuring means to the microcomputer. An external correction means for providing a correction signal from the outside, is that where the structure comprises an inner correction means for correcting the temperature control data of the memory in response to the correction signal of the external compensation means incorporated in the microcomputer.

The second means is that in the first means, the microcomputer is provided with a correction amount changing means for changing the correction signal level of the external correcting means.

[0013]

According to the first means, the induction heating cooker according to the present invention includes the heating coil and the inverter for converting the direct current into the high frequency alternating current and supplying the high frequency current to the heating coil. Induction heating of a load such as a pan by the magnetic flux generated from the coil enables cooking with a good heating response, which is a characteristic of induction heating.

Further, the temperature measuring means for outputting an output signal according to the temperature of the load to be heated, the A / D converter and the memory are integrally formed by an insulating member and the control temperature data is stored in the memory. And a microcomputer for converting the output signal of the temperature measuring means into a digital signal by an A / D converter and comparing it with the control temperature data of the memory, and outputting the control signal to the inverter drive circuit according to the comparison result. Since it is possible to perform complicated automatic cooking corresponding to the temperature change of the load, it is possible to reduce the number of parts of the control unit and downsize it.

Further, as in the conventional case, a plurality of switchable reference levels are provided, the reference level is compared with the output of the temperature measuring means, and the reference level is switched by a microcomputer to detect the load temperature, The inverter is controlled based on the detection result to control the temperature of the load, and external correction means for externally supplying a correction signal to the microcomputer through a path different from the signal of the temperature measurement means is provided, and the microcomputer is responsive to the correction signal. Since the internal correction means incorporated in the microcomputer is configured to correct the temperature control data in the memory, it is possible to change the output of the external correction means even after the program is incorporated and the microcomputer is integrated into a semiconductor. The control temperature value of the load due to induction heating can be easily changed. That is, if the correction amount for the contents of the memory by the internal correction unit according to the output of the external correction unit is preset by the program, the external correction unit is a simple circuit for dividing the voltage of the DC power supply by resistance division, for example. The output can also be configured, and the control temperature value of the load can be easily changed by changing the resistance division ratio, for example.

According to the second means, since the microcomputer is provided with the correction amount changing means for changing the correction signal level of the external correction means, the output level of the external correction means is changed by the program installed in the microcomputer. Since it is possible to arbitrarily variably control, a plurality of temperature correction amounts can be set, and various control temperature data can be easily changed, more detailed temperature control can be performed.

[0017]

【Example】

(Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first exemplary embodiment of the present invention.

In FIG. 1, reference numeral 11 denotes two systems of A / D conversion input terminals 11a and 11b and A / D converters 11c and 11d.
And a microcomputer having three memories 11e, 11f and 11g and one output terminal 11h, 12 is an inverter including a switching element, and 12a is an inverter 1
A heating coil for performing induction heating by the high frequency current output from 2, 13 is an inverter control circuit that drives the switching elements in the inverter 12 and controls the output amount of the inverter 12 by the output of the microcomputer 11, 14 is a direct current A power source, 15 is a heating load pan, R21 to 23 are resistors, 16a is a thermistor of a temperature detecting element for measuring the temperature of the load pan 15, and 16 is the resistance value of the thermistor 16a and the resistance R21. The temperature measuring means 17 converts the voltage value into a voltage value and outputs it to the A / D input 1 terminal 11a of the microcomputer 11. Reference numeral 17 is an A / D conversion input of the voltage obtained by dividing the output voltage Vdd of the DC power supply 14 by the resistors R22 and R23. It is an external correction means for outputting to the two terminals 11b. The internal correction means 18 is the first memory 1
Early 180, 190, 200, described in 1e,
The control temperature data corresponding to 210 ° C. is copied to the rewritable second memory 11f, and the control temperature data of the second memory 11f is corrected according to the temperature correction program in the third memory 11g. A power source, 20 is a rectifier circuit.

The operation of the induction heating cooker configured as described above will be described. Microcomputer 1
In No. 1, the control temperature data of the first memory 11e is copied to the second memory 11f immediately after reset release. Then, the output signal of the external correction means 17 is converted into an A / D conversion input 2 terminal 1
1b, the A / D converter 11d converts it into a digital signal, and based on this data, the data in the second memory 11f is corrected by the correction program in the third memory 11g, and then stored in the second memory 11f. I remember it again. Next, the microcomputer 11 selects one of the four control temperatures stored in the second memory 11f by a program and causes the temperature measuring means 16 to select the thermistor 16a.
The temperature value of the pot 15 of the load measured by the A / D converter input 1 terminal 11a is read and converted into a digital signal by the A / D converter 11c, and the control temperature data stored in the second memory 11f. Comparator 1 with the temperature selected from
If it is less than 1k, the signal for driving the inverter 12 is output to the inverter drive circuit 13 1 terminal 11
It is output from h and drives the switching element of the inverter 12 to heat the pan 15 of the load. Where the inverter 12
Converts the direct current obtained by rectifying the commercial power supply 19 by the rectifier circuit 20 into a high frequency alternating current. Then, the microcomputer 11 converts the load temperature data obtained by converting the temperature value of the pan 15 of the load measured by the thermistor 16a into a digital value in the same manner as the above-mentioned temperature selected from the control temperature data stored in the second memory 11f. In the following cases, a signal for reducing the output amount of the inverter 12 or stopping the drive is output from the output 1 terminal 11h to the inverter drive circuit 13 to reduce the output amount of the inverter 12 or stop the drive.

In the present embodiment, in the correction program of the third memory 11g, the voltage read using the A / D conversion input 2 terminal 11b is 1 / the output voltage Vdd of the DC power supply 14.
0 at 2 ° C, 10 ° C at Vdd, -10 at 0V
The temperature is corrected. Since the resolution of the A / D converter 11d is 8 bits, that is, 256 units, the resolution per correction temperature 1 ° C. has a width of about 12 units, and the external correction means 17 is provided.
The influence of variations in the resistors R22 and R23 of
Accurate temperature correction is possible. In addition, the control temperatures stored in the first memory 11e are four points (180, 19).
However, due to the influence of the body configuration, that is, the influence of electrical noise due to the distance from the heating coil, or the difference in the temperature propagation coefficient from the load to the temperature sensing element due to the temperature sensing element mounting position, etc. When the temperature measured by the temperature measuring means 16 deviates from the temperature of the actual load pan 15 due to the influence, all four control temperatures must be corrected by the same amount. At that time, the resistance value of the external correction means 17 is changed to change the voltage input to the A / D exchange input 2 terminal 11b, and the desired temperature correction amount is converted by the correction program of the third memory 11g to obtain 4 points. You can modify everything at once. Therefore, the control temperature can be easily changed even in the final stage of product development in which the main body configuration is determined.

As described above, according to this embodiment, the microcomputer 1 is provided through a path different from the detection signal of the thermistor 16a.
External change means 17 and internal change means 18 for giving a signal to 1
By providing the above, it is possible to perform shift correction for a plurality of control temperatures all at once, and it is possible to perform accurate temperature correction.

(Embodiment 2) A second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

2 differs from FIG. 1 in that the two output terminals 11i and 11j of the microcomputer 11 are provided.
One end of each of the resistors R24 and R25 is connected to, and the other end is connected to the output end of the external correction means 17, and the switches SW21 and 22 composed of transistors and the like inside the microcomputer 11 are turned on / off, This is to add the correction amount changing means 21 for changing the output voltage of the external correcting means 17 to a predetermined voltage by grounding or disconnecting.

The operation of the induction heating cooker configured as described above will be described. The heating control of the inverter 12 is exactly the same as in the first embodiment. The feature of the second embodiment is that a plurality of correction amounts can be set by the correction amount changing means 21. In this embodiment, the two switches SW21 to 22 are assigned to deep-fried food and heat retention, respectively. That is, when cooking fried food, switch SW2
1. To keep warm, switch SW22 is turned on.

In the microcomputer 11, as in the first embodiment, immediately after the reset is released, the first memory 11e is released.
The control temperature data of is copied to the second memory 11f. At this time, four points (18 points) of fried food are stored in the second memory 11f.
0,190,200,210 ℃) and 1 point of heat retention (80
C) control temperature data is retained. And first of all
Then, the switch SW21 is turned on and the output signal of the external correction means 17, that is, the voltage obtained by dividing the voltage Vdd by the combined resistance value of the resistors R23 to R24 and the resistor R22 is A / D.
Read into the conversion input 2 terminal 11b, A / D converter 11d
Is converted into a digital signal, and based on this data, a correction program in the third memory 11g shift-corrects the four control temperatures for fried food and is stored again in the second memory 11f. Next, the switch SW22 is turned on, and one point of heat retention is shift-corrected as in the fried food cooking. Then, the microcomputer 11 appropriately selects one of the five control temperatures stored in the second memory 11f by correction by the program. Since the operation thereafter is exactly the same as that of the first embodiment, its explanation is omitted. In this way, greatly different control temperatures, such as around 200 ° C. and around 100 ° C., can be independently and finely and accurately corrected simply by changing the values of the two resistors R24 and R25.

As described above, since the internal correction amount changing means 21 is provided, it is possible to set a plurality of correction amounts, so that more detailed and complicated temperature control corresponding to the temperature of the load is performed. be able to. Further, when the influence of the main body configuration is small at the final stage of product development and correction is unnecessary, it is not necessary to insert the resistors R24 to R25, so that the circuit can be simplified.

In this embodiment, the first memory 1 is previously set.
The control temperature stored in 1e is corrected by the output of the external correction means 17. However, the output value of the external correction means 17 is not a value corresponding to the shift width but a value corresponding to a different control temperature. May be changed.
Furthermore, the temperature data for correction is not absolute temperature,
For example, the temperature range data required for automatic cooking may be used.

[0028]

As is apparent from the above embodiments, according to the present invention, an inverter including a heating coil for converting a direct current into a high frequency alternating current and supplying a high frequency current to the heating coil, and the inverter is controlled. An inverter drive circuit,
A temperature measuring means for outputting a signal according to the temperature of a load heated by the magnetic flux generated from the heating coil;
The control temperature data is stored in the memory while being integrally molded by an insulating member including a converter and a memory, and the output signal of the temperature measuring means is converted into a digital signal by the A / D converter to control the memory. A microcomputer for comparing with temperature data and outputting a control signal to the inverter drive circuit according to the comparison result, and an external correction for giving a correction signal to the microcomputer from outside by a path different from the signal of the temperature measuring means. Means and internal correction means for correcting the temperature control data of the memory according to the correction signal of the external correction means built in the microcomputer, it is possible to cook with a good heating response. It is possible to perform complicated automatic cooking corresponding to the temperature change of the load and to reduce the size by reducing the number of parts of the control unit. It is possible to, control the temperature values of the load that is set by the microcomputer can be easily changed in the circuit of the microcomputer external, can be obtained easily induction heating cooker of design and development.

Further, since the microcomputer is provided with the correction amount changing means for changing the correction signal level of the external correction means, the output level of the external correction means can be variably controlled by a program installed in the microcomputer. It is possible to set multiple temperature correction amounts, and various control temperature data can be changed easily. Therefore, it is possible to provide an induction heating cooker that can easily and precisely control temperature in a short development period. Is something that can be done.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an induction heating cooker according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an induction heating cooker according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional induction heating cooker.

[Explanation of symbols]

 11 Microcomputer 11c, 11d A / D converter 12 Inverter 12a Heating coil 13 Inverter drive circuit 14 DC power supply 15 Load pan 16 Temperature measuring means 17 External correction means 18 Internal correction means 21 Correction amount changing means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Yamashita 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. An inverter that includes a heating coil, converts direct current into high frequency alternating current, and supplies a high frequency current to the heating coil, an inverter drive circuit that controls the inverter, and a magnetic flux generated from the heating coil. Temperature measuring means for outputting a signal according to the temperature of the load
A / D converter memory is integrally formed by an insulating member, control temperature data is stored in the memory, the output signal of the temperature measuring means is converted into a digital signal by the A / D converter, and the output signal of the memory is stored. A microcomputer for comparing with the control temperature data and outputting a control signal to the inverter drive circuit according to the comparison result; and an external for giving a correction signal from the outside to the microcomputer through a path different from the signal of the temperature measuring means. An induction heating cooker configured to include a correction unit and an internal correction unit that is built in the microcomputer and that corrects the temperature control data of the memory according to a correction signal of the external correction unit. 2. The induction heating cooker according to claim 1, wherein the microcomputer includes correction amount changing means for changing a correction signal level of the external correcting means.