JPH084673B2 - Induction heating iron - Google Patents

Description

TECHNICAL FIELD The present invention relates to an induction heating iron used in general households.

2. Description of the Related Art FIG. 9 shows a sectional view of an induction heating iron according to the related art. In FIG. 9, reference numeral 1 is an iron body, and 2 is an ironing board for inductively heating the iron body 1. The ironing board 2 includes a heating coil 3 wound in a spiral shape, an inverter 4 that supplies a high-frequency current to the heating coil 3, a receiver 15 that receives radio waves from the iron body 1 and adjusts the output of the inverter 4, a heating coil. It is composed of felt 5 covering the upper part of 3. The iron body 1 includes an iron base 6, a coupling coil 7 magnetically coupled to the heating coil 3, a power supply circuit 8 for generating a DC power supply from the coupling coil 7, and a power supply circuit 8.
The control circuit 9 consumes electric power from.

FIG. 10 is a top view of a conventional ironing board.
As shown in FIG. 10, the coupling coil 7 is provided inside the ironing board and on the upper surface of the iron base 6.

FIG. 11 is a circuit diagram of a circuit provided inside the conventional iron body 1. In FIG. 11, the power supply circuit 8
Is a coupling coil 7, a full-wave rectifier 10, a smoothing capacitor
It is composed of 11. The output of the power supply circuit 8 is connected to the control circuit 9 to supply power to the control circuit 9. The control circuit 9 is connected to a thermistor 12 for detecting the temperature of the iron base 6 and a transmitter 13 that sends out radio waves, and the output of the transmitter 13 is connected to a transmitting antenna 14. The control circuit 9 outputs the temperature information obtained by the thermistor 12 to the transmitter 13, and the radio wave modulated by the temperature information is output from the transmission antenna 14.

The operation of the conventional induction heating iron having the above structure will be described.

In the ironing board, the iron base 6 is induction-heated by the high frequency alternating magnetic field generated from the heating coil 3, and at the same time, a part of the magnetic field from the heating coil is picked up by the coupling coil 7 to generate a current. Since the output voltage of the coupling coil 7 oscillates at a high frequency like the heating coil 3, the rectifier
It is converted into direct current by 10, smoothed by the smoothing capacitor, and output to the control circuit 9. The control circuit 9 detects the temperature of the iron base 6 by a signal from the thermistor 12, and outputs a signal corresponding to the signal to the transmitter 13. The transmitter 13 has about 30 signals modulated by the signal from the control circuit 9.
A radio wave of 0 MHz is output from the antenna 14, the radio wave is received by the receiver 15 provided inside the ironing board, and when the temperature of the iron base 6 is high, the output of the inverter 4 is reduced. As a result, the heating coil 3
The heating power is reduced, and the temperature of the iron base is constantly controlled to a substantially constant value.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above conventional technique, the voltage output from the power supply circuit to the control circuit is unstable, and if it is attempted to stabilize it, there is a problem that a large power loss occurs. there were.

That is, when the engagement state between the heating coil and the coupling coil changes and the output voltage value changes significantly, the voltage of the smoothing capacitor becomes unstable, and an unstable power supply voltage is also supplied to the control circuit. There was a problem to be done.

In addition, even if the position of the iron body changes, an average power supply voltage is applied to the control circuit. When heated in a place close to the heating coil for a long time, the smoothing capacitor is overcharged, an overvoltage is applied to the smoothing capacitor and the control circuit, and in some cases, there is a problem of destruction.

Another conventional technique uses a series regulator as shown in FIG.

FIG. 12 is a circuit diagram of the power supply circuit 8, in which a rectifier 10 and a smoothing capacitor 11 are connected to the output of the coupling coil 7, and then a series regulator 15 is connected. With this configuration, when a constant voltage is output to the control circuit 9, when the coupling coil and the heating coil are well coupled,
Since the output voltage of the coupling coil 7 becomes very high, the voltage of the smoothing capacitor also becomes high, and the series regulator 15
Power loss becomes extremely large, and temperature rise due to heat generation from the series regulator becomes a problem.

When a switching regulator is used instead of the series regulator, there is a problem in that the loss becomes small but the circuit becomes extremely complicated.

The present invention has been made in view of the above problems,
The structure of the power supply circuit is relatively simple, and the output voltage of the power supply circuit is efficiently stabilized.

Means for Solving the Problems Means for solving the above problems comprises an iron body and an ironing board having a heating coil for inductively heating the iron body, and the iron body supplies power to a control circuit and the control circuit. A power supply circuit, the power supply circuit is connected to the heating coil or the power supply coil provided on the ironing board, a coupling coil magnetically coupled to the heating coil, a resonance capacitor connected in parallel to the coupling coil, and the coupling coil. The induction heating iron has a rectifier, a smoothing capacitor, and a short-circuiting unit, and the short-circuiting unit short-circuits the coupling coil when the voltage of the smoothing capacitor is a predetermined value or more.

The induction heating iron according to the present invention having the above-described structure,
The output voltage can be efficiently stabilized with a relatively simple power supply circuit configuration.

Embodiment FIG. 1 is a sectional view of an induction heating iron according to an embodiment of the present invention. In FIG. 1, 21 is an iron body, and 23 is an ironing board including a heating coil 22 for induction heating the iron body 21. Ironing board 23 is a heating coil
22 is provided with a heating inverter 29 for supplying a high frequency current, a receiver 32 for receiving radio waves from the iron body 1, a power supply coil 26, and a power supply inverter 28 for supplying a current to the power supply coil 26. The iron main body 21 includes an iron base 70 / control circuit 24, a thermistor 30 that informs the control circuit 24 of the temperature of the iron base 70, a transmitter 31 that emits radio waves modulated by a signal from the control circuit 24, and a control circuit 24.
Has a power supply circuit 25 for supplying power, and the power supply circuit 25 has a coupling coil 27 magnetically coupled to a power supply coil 26 provided in the ironing board 23. FIG. 2 is a top view showing the coupling between the power supply coil 26 and the coupling coil 27, and FIG.
It is a B arrow line view of FIG. As shown in FIGS. 2 and 3, the power supply coil 26 includes a U-shaped ferrite core 34.
The coupling coil 27 is wound around a rod-shaped ferrite core 35. FIG. 4 is a circuit diagram of the inside of the iron body 21. As shown in FIG. 4, the power supply circuit 25 includes a coupling coil 27, a resonant capacitor 6 connected to both ends of the coupling coil, a diode rectifier 7 connected to an intermediate terminal of the coupling coil, a smoothing capacitor 38 and a short-circuiting means. It consists of 39. The short-circuit means 39 is a resistor 41, a resistor 43, a resistor 44, a Zener diode 42, a comparator 45, and a Zener diode.
46, transistor 49, resistors 48 and 47 for driving transistor 49, resistor 52 for hysteresis operation of comparator 45, Zener diode 53, thyristor 54 for short-circuiting both ends of resonant capacitor 36, and drive of thyristor 54 The resistor 50 and the resistor 51, and the thyristor 54 are configured by a capacitor 55 for preventing erroneous turning on due to noise or the like. The control circuit 24 outputs the output Vb of the power supply circuit 25.
The temperature information obtained from the thermistor 30 is connected to the transmitter 25
I am sending it to. The transmitter 25 transmits the radio wave modulated by the signal from the control circuit 24 to the ironing board.

The operation of the above induction heating iron will be described below with reference to the waveform chart of FIG.

FIG. 5A is a waveform diagram of the voltage Va generated in the resonance capacitor 36, and FIG. 5A is a voltage across the smoothing capacitor 38.
Waveform of Vb (= output voltage), Figure 5 (c) is a thyristor
FIG. 7 is a waveform diagram of the gate voltage Vc of 54. During the time up to T1, the voltage Vb of the smoothing capacitor 38 is still low, and the potential of the negative input terminal is lower than the potential of the positive input terminal of the comparator 45, so the output of the comparator 45 is in the open collector state. The transistor 49 is turned off, and the gate voltage Vc of the thyristor 54 is almost zero. Therefore, the resonance capacitor 36 is connected to the coupling coil 27.
In parallel resonance state, a high frequency high voltage Va is generated in the resonance capacitor 36. At time T1, when Vb = V1 (threshold voltage) is reached, the voltage of the negative input terminal of the comparator 45 becomes higher than the voltage of the positive input terminal, so that the output voltage of the comparator 45 is pulled low and the transistor 49 is turned on. Turn on. Therefore, the gate voltage Vc of the thyristor 54 also increases and the thyristor 54 turns on. Then, since the coupling coil 27 is short-circuited by the thyristor 54, Va becomes almost zero volt. When the coupling coil 27 is short-circuited, the smoothing capacitor 38 also stops charging, and is discharged by the current supplied from the smoothing capacitor 38 to the control circuit 24, so that Vb continues to decrease. Further, when the transistor 49 is turned on, the minus input terminal of the comparator 45 is pulled up via the diode 53 and the resistor 52, so that hysteresis occurs,
Next, the output of the comparator 45 shifts to the open collector state when Vb = V2. Vb = at time T2
When the voltage reaches V2, the output of the comparator 45 becomes the open collector state again, the transistor 49 is turned off, and Vc becomes almost zero volt. Since a high-frequency alternating current constantly flows through the coupling coil 27, when Vc = 0, the thyristor 54 is immediately turned off. Therefore, the resonance state is entered again, the smoothing capacitor 38 is charged, and the power supply current is also supplied to the control circuit 24.

As described above, in this embodiment, when the thyristor 54 is turned on, when the coupling coil 27 is short-circuited, the resonant capacitor 36 is also short-circuited. Therefore, although a slight loss occurs at that time, a stable power supply voltage can be supplied to the control circuit 24 fairly efficiently.

In this embodiment, a dedicated power supply coil is provided, but the same effect is obtained when the magnetic field from the heating coil that heats the iron body during ironing is received as described in the related art. Can be mentioned.

It should be noted that when the coupling coil 27 is short-circuited, the current of the dedicated power supply coil tends to increase, but in a normal induction heating iron, the gap between the coupling coil and the power supply coil is about 5 mm. Therefore, the increase of the current can be made much smaller than the exciting current, so that there is no problem.

 Next, a second embodiment of the present invention will be described.

FIG. 6 is a circuit diagram of the inside of the iron body of the induction heating iron according to the second embodiment of the present invention. In FIG. 6, the phase detection circuit 56, the D flip-flop 62, the resistor 61, the resistor 63, and the resistor 64 are added to the above embodiment. The phase detection circuit 56 outputs high when the voltage of the coupling coil 27 is negative or zero, and the D flip-flop 62 determines whether the voltage generated in the resistor 61 is the output voltage of the phase detection circuit 56. It is read when Vd rises and is output from the output terminal Q.

The operation of the above structure will be described with reference to FIG. FIG. 7A is a waveform diagram of the voltage Va of the coupling coil 27 and the resonance capacitor 36, FIG. 7A is a waveform diagram of the output voltage Vd of the phase detection circuit 56, and FIG. 7C is a waveform diagram of the voltage Ve applied to the resistor 61. , (D) are waveform diagrams of the gate voltage Vf of the thyristor 54. As shown in (a), Vd becomes high only when Va <0, and as shown in (c), Ve rises to high regardless of Va. In this embodiment, the state of Ve at the moment when Vd rises to high is read by the action of the D flip-flop 62, so that Vf rises to high when Vf is almost zero.

Therefore, in the present embodiment, although the number of circuit components is slightly increased and becomes complicated as compared with the first embodiment, the loss due to the short-circuiting of the resonance capacitor does not occur, so that the first embodiment It is possible to realize a highly efficient power supply circuit with less loss than in the case of.

In this embodiment, the example using the D flip-flop is shown, but substantially the same effect can be obtained by using, for example, an AND circuit instead of the D flip-flop.

Next, another example of the coupling coil is shown in FIG. In FIG. 8, two coupling coils are provided at the same position, one of which 27
The resonance capacitor 36 and the short circuit 39 are provided in a, and the rectifier 37, the smoothing capacitor and the control circuit 24 are connected to the other 27b.

Also in this embodiment, an effect equivalent to that using the above-mentioned intermediate terminal is obtained, and the amount of copper used for the winding is slightly increased, but the processing of the enameled wire is simplified.

Further, even if the resonance capacitor, the rectifier, and the short-circuit means are connected to the three coupling coils provided at the same position, the equivalent operation is performed.

It should be noted that in each of the embodiments, a slight ripple voltage is generated at the output of the power supply circuit, so a series regulator or the like may be provided for further stabilization if necessary. Can be kept to a small value.

EFFECTS OF THE INVENTION As is apparent from the above embodiments, the induction heating iron of the present invention comprises an iron body and an ironing board having a heating coil for inductively heating the iron body, and the iron body has a control circuit and the control circuit. A power supply circuit for supplying power to the circuit, wherein the power supply circuit is a coupling coil magnetically coupled to the heating coil or a power supply coil provided in the ironing board; a resonance capacitor connected in parallel to the coupling coil; and the coupling. A rectifier connected to the coil, a smoothing capacitor, and a short-circuiting means, and the short-circuiting means short-circuits the coupling coil when the voltage of the smoothing capacitor is equal to or higher than a predetermined value. With the configuration, the output voltage of the power supply circuit can be efficiently stabilized.

[Brief description of drawings]

FIG. 1 is a sectional view of an induction heating iron according to a first embodiment of the present invention, FIG. 2 is a top view of a power supply coil and a coupling coil thereof, and FIG. 3 is a view taken in the direction of arrow B of FIG. 4 is the first
FIG. 5 is an internal circuit diagram of the iron body of the induction heating iron shown in FIG. 5, FIG. 5 is an operation waveform diagram thereof, and FIG. 6 is a circuit of the iron body of the induction heating iron according to the second embodiment of the present invention. FIG. 7 is an operation waveform diagram thereof, FIG. 8 is a circuit diagram showing another example of a coupling coil provided inside the iron body of the induction heating iron of the present invention, and FIG. FIG. 10 is a cross-sectional view of the induction heating iron, FIG. 10 is a top view of the conventional induction heating iron, FIG. 11 is a circuit diagram inside the iron body of the conventional induction heating iron, and FIG. FIG. 6 is a circuit diagram in the case where a series regulator is provided in the iron body of the induction heating iron of the technique of FIG. 21 …… Iron body, 22 …… Heating coil, 23 …… Ironing board, 24 …… Control circuit, 25 …… Power supply circuit, 26 …… Power supply coil, 27 ・ 27a ・ 27b …… Coupling coil, 36 …… Resonance Capacitor, 37 ... Rectifier, 38 ... Smoothing capacitor, 39 ...
... shorting means.

Claims (1)

[Claims] 1. An iron main body and an ironing board having a heating coil for inductively heating the iron main body, wherein the iron main body has a control circuit and a power supply circuit for supplying power to the control circuit, and the power supply circuit includes the heating circuit. A coil or a coupling coil magnetically coupled to a power supply coil provided on the ironing board, a resonance capacitor connected in parallel to the coupling coil, a rectifier and a smoothing capacitor connected to the coupling coil, and a short-circuit means, The short circuit means is an induction heating iron for short-circuiting the coupling coil when the voltage of the smoothing capacitor is equal to or higher than a predetermined value.