JPH05121152A - Electromagnetic induction heater - Google Patents

Abstract

(57) [Summary] [Purpose] The size of the yoke is determined and the heating temperature is controlled.
The heating temperature control can be adjusted independently for each size, and the heating control can be optimized for each size. [Structure] A detection circuit 17 for detecting a current flowing through the heating coil 8 and a control circuit 18 for determining the size of a hair curler by the output of the detection circuit 17 are provided. When heating the small curler, the control circuit 18 outputs a size discrimination signal 29 for the small curler.
Is set to the H level, the switching element 15 is driven by the drive pulse width generation circuit 22, and a current flows through the heating coil 8. This current is input to the control circuit 18 via the resistor 16 and the detection circuit 17, and the detection voltage determines that the curler is small.
In the case of a small curler, the heating is continued as it is, and when the detection voltage reaches a predetermined voltage, the control circuit 18 determines that the heating is completed and stops the induction heating by the heating coil 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic induction heater for heating a hair curler by electromagnetic induction.

[0002]

2. Description of the Related Art The temperature control of an object to be heated of a conventional electromagnetic induction heater is performed by detecting the temperature of the object to be heated.

[0003]

However, there are many structural restrictions because it is necessary to ensure that the object to be heated is in contact with the temperature sensor and that the temperature sensor is insulated by a seal or the like. Further, in the case where the yoke, which is the heating body of the object to be heated, is covered with an object having poor heat conduction such as plastic, there is a problem that the temperature of the yoke cannot be directly detected and reliable temperature control cannot be performed. ..

The present invention has been provided in view of the above-mentioned points, and an object to be heated having a plurality of types of yokes of different sizes is electromagnetically heated, and the electric resistance, current or voltage by the electromagnetic induction heating of the yoke is provided. The change in the size of the yoke is detected and the heating temperature is controlled, the insulation and structure are easy, and the heating temperature control can be adjusted independently for each size by the size-determined signal, which is optimal for each size. It is an object of the present invention to provide an electromagnetic induction heater capable of controlling heating.

[0005]

SUMMARY OF THE INVENTION The present invention is an electromagnetic induction heater for electromagnetically heating an object to be heated having a plurality of types of yokes of different sizes, and the electric resistance, current or current due to the electromagnetic induction heating of the yoke as a load. Detecting means for detecting a change in voltage, a control circuit for discriminating the size of the yoke and heating temperature control by a signal from the detecting means, and the above-mentioned heating temperature control for each size by a size discriminating signal from the control circuit. And an adjusting means for independently adjusting.

Further, in claim 2, the adjusting means changes the offset amount of the drive pulse width of the heating means, whereby the heating amount for each size is independently adjusted. .. Further, in claim 3, a temperature sensor for detecting the temperature of the heating coil and the ferrite core, a temperature correction circuit for controlling the driving pulse width of the heating means by the output of the temperature sensor, and an offset amount of the temperature correction circuit are set. Adjustment means for independently adjusting each size is provided to adjust the offset amount of the drive pulse width.

Further, in claim 4, the adjustment for each size of each hair curler is carried out for two hair curler sizes, one having a small driving pulse width and the other having a large driving pulse width, and the others are omitted.

[0008]

Thus, the size and temperature of the object to be heated can be detected without providing any special detecting means, and the electromagnetic induction heating can be used to efficiently and safely heat the object.
Further, according to the second aspect, even if there are variations in characteristics due to the heating coil or the switching element for a plurality of types of objects to be heated, the adjustment can be performed individually and independently, which facilitates the adjustment.

According to a third aspect of the present invention, after adjusting the characteristic variations of the heating coil, the switching element and the like other than those due to the difference in the type of the object to be heated, those due to the difference in the type of the object to be heated, that is, the drive pulse width. The adjustment range can be set optimally and it is easy to adjust because only the difference due to
The adjustment of the characteristic variation depending on the type of the object to be heated is provided in the temperature correction circuit of the heating coil and the ferrite core, and the efficiency is good.

Further, according to the present invention, the adjustment of each hair curler for each size is performed for two hair curler sizes, one having a small driving pulse width and the other having a large driving pulse width, and the others are omitted, whereby the temperature adjustment becomes easy. ..

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the present invention, the application of the embodiment to a hair curler will be described. In FIG. 4, an electromagnetic induction heater 2 for a hair curler 1 is provided with an annular hair curler insertion portion 5 in a part of a main body 4 in which a storage case 3 for the hair curler 1 and the like is detachable, and an electromagnetic induction heating device is provided in a central portion thereof. The heating body 6 is vertically installed, and the hair curler 1 is removably inserted into the peripheral portion of the heating body 6 so that the hair curler 1 can be heated efficiently.

As shown in FIG. 4, the heating element 6 has a heating coil 8 for electromagnetic induction heating wound around a ferrite core 7 so that the hair curler 1 can be heated. As shown in (a), (b), and (c) of FIG. 5, the hair curler 1 includes a small curler 1a, a middle curler 1b, and a large curler 1c, each of which has a cylindrical body 9 having a different diameter. The cylindrical yoke 10 of 1 is internally formed.

A cloth material 11 for heat insulation is attached to the outer peripheral surface of the yoke 10, and a comb portion 12 made of a synthetic resin material is attached to the periphery so that the hair can be easily wound at regular intervals. FIG. 1 shows an electric circuit configuration, in which a heating coil 8, a switching element 15, and a current detection resistor 16 are connected to a commercial power supply 13 via a rectifying bridge 14. A detection circuit 17 is connected to the resistor 16 and is input as a detection voltage to a control circuit 18 including a microcomputer or the like.

In the drive pulse width generation circuit 22, an output corresponding to the drive pulse width is input from the control circuit 18 to the differential amplifier 22a of the drive pulse width generation circuit 22 via the D / A converter 20 and the resistor 21. , Triangular wave generator 2
The output B of 4 and the output A of the differential amplifier 22a are compared by the comparator 23, and the drive pulse C is output via the switching element 25.

The output waveforms A, B and C of the respective parts of the drive pulse width generating circuit 22 are as shown in FIG. Where t ₀
Is the oscillation period, and tp is the drive pulse width. t ₀ is constant (about 40 μS), and tp changes according to the input. The output C is input to the driver 27 via the resistor 26 and drives the switching element 15. Further, a switching element 28 is connected to a connection point between the resistor 26 and the driver 27 so that the control circuit 18 can control ON / OFF of the driver 27 and thereafter. Further, the curler size determination signals 29 to 30 are output to the control circuit 18 according to the size of each hair curler 1, drive each switching element 32 to 34, and connect the resistor 38 and each volume 35 to 3 to each other.
The voltage adjusted in 7 is input to the differential amplifier 22 a of the drive pulse width generation circuit 22. Incidentally, the adjusting means is constituted by the resistor 38 and the respective volumes 35 to 37.

The signal from the heating switch 19 is the control circuit 1
It is entered in 8. Further, the detection voltage output of the detection circuit 17 and the temperature of the yoke 10 of each hair curler 1 when each hair curler 1 is heated by the driving pulse for the small curler 1a are shown in FIG.
The characteristics are as shown in. Next, the operation of the above configuration will be described. When the small curler 1a of the hair curler 1 is inserted into the hair curler insertion portion 5 and the heating switch 19 is pressed, it is detected that the control circuit 18 has pressed the driving pulse width data for the small curler 1a to the D / A converter 20. The size discrimination signal 29 is output at the H level and the size discrimination signal 3 is output.
0 and 31 are set to L level.

Therefore, the switching element 32 is turned on, the switching elements 33 and 34 are turned off, the voltage divided by the resistor 38 and the volume 35, and the D / A converter 2
The output of 0 is the differential amplifier 22 of the drive pulse width generation circuit 22.
Then, the oscillation signal having the driving pulse width for the small curler 1a is output. This output C is input to the driver 27 via the resistor 26 (at this time, the switching element 28 is turned off by the control circuit 18), the switching element 15 is driven, and a current flows through the heating coil 8. This current is input to the control circuit 18 as a detection voltage via the resistor 16 and the detection circuit 17. As for the detection voltage at this time, the temperature of the yoke 10 of the hair curler 1 is around room temperature,
If it is Ta, the value becomes Va. In the control circuit 18, since the detection voltage Va is between V ₁ and V _{2 in} FIG. 3, it is determined to be the small curler 1a.

In the case of the small curler 1a, the heating is continued as it is, and when the temperature of the yoke 10 of the small curler 1a is heated to Tb and the detected voltage becomes Vb, the control circuit 18 judges that the heating is completed. Then, the switching element 28 is turned on to prevent the drive pulse from being applied to the driver 27, and the induction heating by the heating coil 8 and the switching element 15 is stopped.

In this case, the drive pulse width is controlled to
The heat retaining operation may be performed so that the temperature of the yoke 10 of the hair curler 1 is kept constant. Next, the case of the middle curler 1b of the hair curler 1 will be described. Also in this case, first, the drive pulse data for the small curler 1a is transferred to the D / A converter 2
0 and outputs the size determination signal 29 at H level,
The size discrimination signals 30 and 31 are set to L level.

In the drive pulse width generation circuit 22, the oscillation signal of the drive pulse width for the small curler 1a is output as described above, the switching element 15 is heated via the driver 27, and the current flows through the heating coil 8. Detection voltage Va 'becomes as shown in FIG. 3 at this time, since the between V ₃ and V _2, to determine the control circuit 18 is a middle Carla 1b, and drive pulse width data for medium Carla 1b D / A converter 2
In addition to outputting 0, the size determination signal 30 is set to H level and the size determination signals 29 and 30 are set to L level.
The switching element 33 is turned on, the switching element 32,
34 is turned off, the voltage divided by the resistor 38 and the volume 36 and the output of the D / A converter 20 are input to the drive pulse width generation circuit 22, and the drive pulse for the middle curler 1b is switched via the driver 27. The element 15 is driven and an electric current is passed through the heating coil 8.

At this time, the detection voltage obtained by the resistor 16 and the detection circuit 17 shows almost the same characteristic as that of the small curler 1a (not shown), the middle curler 1b is heated, and as shown in FIG. When the temperature reaches a detection voltage of Tb, the control circuit 18 turns on the switching element 28 to stop heating. The same applies to the large curler 1c. After the size discrimination, the large curler 1c is driven with the drive pulse width for the large curler 1c, and the size discrimination signal 31 is set to the H level and the size discrimination signals 29 and 30 are set to the L level.

Here, the driving pulse width data for each hair curler size is as follows:
The detection voltages are set to be almost the same, that is, the heating powers are almost the same. By doing so, the same capacity rating can be used for each hair curler size, and the heating time can be shortened as much as possible. When the detection voltage is V ₁ or more and V ₄ or less at the time of size determination, the heating operation is not performed because a foreign matter is inserted or a hair curler is not inserted.

Here, the size discrimination signals 29 to 30 are used to individually switch the offset input to the differential amplifier 22a of the drive pulse width generating circuit 22 for each hair curler size. Even if the variation in the detection voltage characteristic for each hair curler size in the drive pulse width for each hair curler size is different due to the variation in characteristics of the switching element 15, etc., the volume 35 to 37 should be adjusted for each hair curler size. This makes it possible to adjust to the characteristics expected for all hair curler sizes.

(Second Embodiment) FIG. 6 shows a second embodiment. The difference from the previous embodiment is the following point. That is, the detection voltage characteristic changes depending on the temperature characteristics of the heating coil 8 and the ferrite core 7. Therefore, in order to eliminate the influence of this temperature characteristic, the temperature of the ferrite core 7 is detected through the temperature sensor 40 and the amplifier 42, and the D / A converter 2
Correct by adding to 0 output. The correction amount is determined by the gain of the amplifier 42 and the ratio of the resistors 43 and 21.

Here, by controlling the switching elements 49 to 51 by the size discrimination signals 52 to 54, the offset amount of the temperature correction circuit 39 is individually and independently adjusted for each hair curler size, and thus the drive pulse width is adjusted. The offset amount of can also be adjusted. In the adjustment, after adjusting the characteristic variations of the heating coil 8, the switching element 15 and the like by the drive pulse offset by the volume 55 with a certain drive pulse width, each hair curler size drive pulse width for each hair curler size is adjusted. By adjusting the volumes 46 to 48 individually and independently, it is possible to eliminate the characteristic variation for each size.

In this case, among the volumes 46 to 48 in which the volume 55 is adjusted by the drive pulse for the small curler 1a, the volume for the small curler 1a can also be used as a fixed resistor. At this time, the small curler 1a is not independently adjusted, but there is no practical problem. In this way, by dividing the overall adjustment (volume 55) and the adjustment for each hair curler size (volumes 46 to 48), the former adjustment range can be widened and the latter adjustment range can be narrowed. This is because the latter has variations due to the drive pulse width,
That is, this is because there is only the variation in the frequency characteristics, and the variation is smaller than the former. Therefore, the adjustment is easier than in the previous embodiment. Moreover, since it can be used also as the temperature correction circuit 39, there is no need to provide a separate circuit, and the efficiency is good.

Here, in both of the above two embodiments, the switching element and the volume are inserted on the power source side of the resistance division.
It may be inserted on the ground side. Which one should be inserted should be placed in the wider voltage range with respect to the required voltage. This is because variations in ON voltage of the switching element and influence of temperature characteristics can be reduced. Further, since the adjustment for each hair curler size is considered to be a variation in the frequency characteristic mainly derived from the drive pulse width, the variation generally becomes larger as the drive pulse width is different. That is, the difference between the small curler 1a and the large curler 1c is larger than the difference between the small curler 1a and the middle curler 1b. Therefore, the small curler 1a and the middle curler 1b may be adjusted by one, and only the large curler 1c may be adjusted separately.

In the case of the second embodiment, the volume 55 also serves to adjust the small curler 1a and the middle curler 1b, the size discrimination signal 52 is used for the small curler 1a, the size discrimination signal 53 is used for the middle curler 1b, and the size discrimination signal 54. For the large curler 1c, the size discriminating signals 52 and 53 are commonly used so that when the small curler 1a and the medium curler 1b are discriminated, the L level is set, and when the large curler 1c is set to the H level, the switching elements 49 and 50 are set. One is used, and the volumes 46 and 47 are used as one fixed resistor. Here, the size determination signal 54 for the large curler 1c, the switching element 51, and the volume 48 are the same as before.

Although the current of the yoke 10 is detected as a method of detecting the electromagnetic induction heating of the yoke 10, a method of detecting a change in the electric resistance of the yoke 10 or a voltage may be used.

[0030]

As described above, the present invention is an electromagnetic induction heater for electromagnetically heating an object to be heated having a plurality of types of yokes of different sizes. Detecting means for detecting a change in voltage, a control circuit for discriminating the size of the yoke and heating temperature control by a signal from the detecting means, and the above-mentioned heating temperature control for each size by a size discriminating signal from the control circuit. Since it has an adjusting means for adjusting independently, it is possible to detect the size and temperature of the object to be heated without providing special detecting means, and to heat safely by electromagnetic induction heating with high thermal efficiency. This is an effect that can be achieved.

Further, in the present invention, the adjusting means changes the offset amount of the drive pulse width of the heating means, whereby the heating amount for each size is adjusted independently. Therefore, even if there are variations in the characteristics of the heating coil or the switching element for a plurality of types of objects to be heated, the adjustments can be made individually and independently, which facilitates the adjustment.

Further, in claim 3, a temperature sensor for detecting the temperature of the heating coil and the ferrite core, a temperature correction circuit for controlling the drive pulse width of the heating means by the output of the temperature sensor, and a temperature correction circuit for the temperature correction circuit. Provided with adjusting means for independently adjusting the offset amount for each size,
Since the offset amount of the drive pulse width is adjusted, after adjusting the characteristic variations of the heating coil, switching element, etc. other than those due to the difference in the type of object to be heated, The adjustment range can be set optimally because it is possible to adjust only due to the difference, that is, due to the difference in the drive pulse width, and it is easy to adjust. Since the adjustment is provided in the temperature correction circuit of the heating coil and the ferrite core, the efficiency is good.

Further, in the present invention, the adjustment of each hair curler for each size is performed for two hair curler sizes, one having a small driving pulse width and the other having a large driving pulse width, and the others are omitted, whereby the temperature adjustment becomes easy. ..

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an operation waveform diagram of the above.

FIG. 3 is a diagram showing a relationship between a temperature of a yoke and a detected voltage in the above.

FIG. 4 is a cutaway front view of the electromagnetic induction heater of the above.

FIG. 5 (a) is a cutaway front view of the same small curler, (b).
Fig. 3 is a cutaway front view of the above-mentioned middle curler, and (c) is a cutaway front view of the above-mentioned large curler.

FIG. 6 is a circuit diagram of a second embodiment of the above.

[Explanation of symbols]

 1 Hair Curler 7 Ferrite Core 8 Heating Coil 10 Yoke 18 Control Circuit 39 Temperature Correction Circuit

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[Procedure amendment]

[Submission date] December 2, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

A cloth material 11 for moisturizing is attached to the outer peripheral surface of the yoke 10, and a comb portion 12 made of a synthetic resin material is attached to the periphery of the yoke 10 so that the hair can be easily wound at regular intervals. FIG. 1 shows an electric circuit configuration, in which a heating coil 8, a switching element 15, and a current detection resistor 16 are connected to a commercial power supply 13 via a rectifying bridge 14. A detection circuit 17 is connected to the resistor 16 and is input as a detection voltage to a control circuit 18 including a microcomputer or the like.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

Here, in the above two embodiments , the switch
The power supply side of the resistor divider and the
Or is good to insert into the soil side throat Chilla is, it is better to put the wide end of the voltage range for the required voltage. This is because variations in ON voltage of the switching element and influence of temperature characteristics can be reduced. Further, since the adjustment for each hair curler size is considered to be a variation in the frequency characteristic mainly derived from the drive pulse width, the variation generally becomes larger as the drive pulse width is different. That is, the difference between the small curler 1a and the large curler 1c is larger than the difference between the small curler 1a and the middle curler 1b. Therefore, small carla 1a, medium carla 1b
It is also possible to use one adjustment for both and adjust only the large curler 1c separately.

Claims (4)

[Claims] 1. An electromagnetic induction heater for electromagnetically heating an object to be heated having a plurality of types of yokes of different sizes, and detecting means for detecting changes in electric resistance, current or voltage due to electromagnetic induction heating of a yoke as a load. And a control circuit for discriminating the size of the yoke and controlling the heating temperature by a signal from the detecting means, and an adjusting means for independently adjusting the heating temperature control for each size by the size discriminating signal from the control circuit. An electromagnetic induction heater characterized by comprising. 2. The adjusting means changes the offset amount of the drive pulse width of the heating means, thereby independently adjusting the heating amount for each size. Electromagnetic induction heater. 3. A temperature sensor for detecting the temperature of the heating coil and the ferrite core, a temperature correction circuit for controlling the drive pulse width of the heating means by the output of the temperature sensor, and an offset amount of this temperature correction circuit for each size. 3. The electromagnetic induction heater according to claim 2, further comprising adjusting means for independently adjusting each of them to adjust the offset amount of the drive pulse width. 4. The electromagnetic induction according to claim 1, wherein the adjustment for each hair curler size is performed for two hair curler sizes, one having a small driving pulse width and the other having a large driving pulse width, and the others are omitted. Heater.