JP2006156147A - Induction heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating device capable of reducing stand-by electric power without damaging misoperation resistance amount due to noises from outside wherein electric power consumption is reduced in stand-by state that a heating sequence is not carried out. <P>SOLUTION: A pan 1 is induction heated by a coil 2, an electrification control element 5 to control an electric current is driven by a drive circuit 7, and the pan 1 is heated by a control means 11 according to the heating sequence. A power supply current is supplied to the drive circuit 7 from a first power supply circuit 12, the power supply current is stepped down by a second power supply circuit 13 and supplied to an operating part 9 and the control means 11 or the like, and an output voltage of the first power supply circuit 12 is switched by a power supply voltage changing means 14. It is constituted so that a set value of the output voltage of the first power supply circuit 12 is switched to a second voltage set value which is set lower than the first voltage set value in the waiting state that the heating sequence is not carried out. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an induction heating apparatus that reduces power consumption in a standby state in which a heating sequence is not executed.

  Conventionally, this type of induction heating apparatus is configured as shown in FIG. 3 (see, for example, Patent Document 1). Hereinafter, the configuration will be described.

  As shown in FIG. 3, the circuit board 20 includes a control unit including a DC power supply circuit 22, a load component drive circuit 28, a start switch 29, a power supply control circuit 30, and a microcomputer 34.

  The DC power supply circuit 22 includes a diode 23 connected in series to the AC power supply 21 to rectify an AC current, an electrolytic capacitor 26 connected in series to the diode 23 to form a smooth DC high voltage, and a step-down chopper method. The switching power supply circuit 25 that obtains a DC low voltage by stepping down by the well-known method, and an electrolytic capacitor 27 that stabilizes the DC low voltage.

  The start switch 29 is connected to the switching power supply circuit 25 at both ends to start the switching operation of the DC power supply circuit 22 and is constituted by a normally open switch that cuts off current supply when not in operation.

  The power supply control circuit 30 maintains or stops the output state of power from the DC power supply circuit 22 and includes a transistor 31 that is a switching element. The transistor 31 has an emitter and a collector connected in parallel with the start switch 29, a base connected to the microcomputer 34 via a resistor 32, and is connected to the emitter side via a resistor 33.

In this configuration, when the microcomputer 34 determines that all the load components are not operating, the microcomputer 34 stops the output of power from the DC power supply circuit 22 via the power supply control circuit 30. As a result, power consumption during standby can be reduced.
JP 2000-287837 A

  However, in such a conventional configuration, when the output from the DC power supply circuit 22 is stopped, the supply of the power supply current to the drive circuit 28 is stopped, so that the internal potential becomes unstable, There is a problem that the output of the drive circuit 28 is erroneously output due to noise from the outside, and the load component operates. In particular, even among the load components, when an energization control element that conducts or interrupts the induction heating current malfunctions, the energization control element has a problem of being short-circuited within 1 millisecond and being destroyed.

  The present invention solves the above-described conventional problems, and an object thereof is to provide an induction heating apparatus capable of reducing standby power without impairing malfunction tolerance due to external noise.

  In order to achieve the above-mentioned object, the present invention inductively heats the bottom of the pan stored in the heating device body by a coil, drives an energization control element for controlling the current flowing in the coil by a drive circuit, and operates it by a control means An ON signal is output to the drive circuit to heat the pan according to the heating sequence specified in the section, and the power supply current is supplied from the first power supply circuit to the drive circuit, and the current is supplied from the first power supply circuit. The voltage is reduced by the second power supply circuit, the power supply current is supplied to the operation unit, the control means, etc., and the output voltage of the first power supply circuit is switched by the power supply voltage changing means. In the standby state where the sequence is not executed, the set value of the output voltage of the first power supply circuit is switched from the first voltage set value to the second voltage set value set lower than that. One in which was configured to replace.

  As a result, in the standby state, the output voltage of the first power supply circuit can be set to the second voltage set value lower than the first voltage set value, and the current consumption of the drive circuit can be reduced by reducing the power supply voltage. As a result, the overall standby power can be reduced. In this state, since the power supply current is applied to the drive circuit, the trigger terminal of the energization control element has a stable potential and does not impair malfunction tolerance due to external noise.

  The induction heating device of the present invention can reduce standby power at a low cost and without reducing external noise immunity by reducing the output voltage of the first power supply circuit in the standby state.

  A first invention includes a pan housed in a heating device body, a coil for induction heating the bottom of the pan, an energization control element for controlling a current flowing through the coil, and a drive circuit for driving the energization control element A control means for outputting an ON signal to the drive circuit for heating the pan in accordance with a heating sequence designated by the operation part, and a first power supply circuit for supplying a power supply current to the drive circuit A second power supply circuit that supplies current from the first power supply circuit and steps down the voltage to supply power supply current to the operation unit, the control means, and the like, and a power supply that switches an output voltage of the first power supply circuit Voltage changing means, and the power supply voltage changing means changes the set value of the output voltage of the first power supply circuit from the first voltage set value to the set value in the standby state where the heating sequence is not executed. The output voltage of the first power supply circuit can be set to a second voltage set value lower than the first voltage set value in the standby state. As the power supply voltage is lowered, the current consumption of the drive circuit can be reduced, and the overall standby power can be suppressed. In this state, since the power supply current is applied to the drive circuit, the trigger terminal of the energization control element has a stable potential and does not impair malfunction tolerance due to external noise.

  According to a second aspect of the present invention, in the first aspect of the invention, there is provided time-counting means for measuring the elapsed time from the start of the standby state in which the heating sequence is not executed, and the power supply voltage changing means sets the time-measurement time of the time-measurement means When the value is exceeded, the output voltage of the first power supply circuit is switched from the first voltage setting value to the second voltage setting value set lower than that, and the elapsed time after the start of the standby state When the set value of the clock means is exceeded, the current consumption of the drive circuit can be reduced by setting the output voltage of the first power supply circuit to the second voltage set value lower than the first voltage set value and lowering the power supply voltage. As a result, overall standby power can be reduced. In this state, since the power supply current is applied to the drive circuit, the trigger terminal of the energization control element has a stable potential and does not impair malfunction tolerance due to external noise.

  According to a third aspect, in the first aspect, when the user performs an operation on the operation unit during standby, the setting value of the output voltage of the first power supply circuit is changed from the second voltage setting value to the second voltage setting value. Wake-up means for returning to the voltage setting value of 1 is added, and elements with high power consumption that receive power supply from the first power supply circuit, such as a buzzer that rings in response to a user's operation and an LED that lights up. Can be prepared for driving.

  According to a fourth aspect of the present invention, in the second aspect of the present invention, when the user performs an operation on the operation unit during standby and after the output voltage of the first power supply circuit reaches the second voltage setting value. And a wake-up means for returning the set value of the output voltage of the first power supply circuit from the second output voltage set value to the first output voltage set value, and ringing in response to a user operation. For example, it is possible to prepare for driving an element with high power consumption that receives power supply from the first power supply circuit, such as a buzzer to be turned on or an LED to be lit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a partial block circuit diagram of the induction heating apparatus according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the pan 1 is housed in a heating device main body (not shown), and the bottom of the pan 1 is heated by induction heating with a coil 2. A resonance capacitor 3 is connected in parallel to the coil 2. The inverter power supply unit 4 is supplied with current from the commercial power supply 41, and full-wave rectifies by the diode bridge 42, and supplies the direct current smoothed by the capacitor 43 to the coil 2. The energization control element 5 controls the current flowing through the coil 2, and a reflux diode 6 is connected to the energization control element 5 in parallel.

  The drive circuit 7 outputs a drive signal having a specified voltage to the trigger terminal 51 of the energization control element 5 to make the energization control element 5 conductive. A microcomputer (hereinafter referred to as a microcomputer) 8 controls heating in accordance with a sequence stored in a memory 81 mounted therein, and the operation unit 9 includes a switch 91 and a resistor 92, and the switch 91 is turned on.・ Off is input to the microcomputer 8. The microcomputer peripheral circuit 10 includes a buzzer 101, an LED 102, and the like.

  The control means 11 is built in the microcomputer 8 and outputs an on / off signal to the drive circuit 7. The first power supply circuit 12 supplies a power supply current to the drive circuit 7 and the microcomputer peripheral circuit 10, and the second power supply circuit 13 receives a current supply from the first power supply circuit 12 and steps down to reduce the microcomputer 8 and A power supply current is supplied to the operation unit 9.

  The drive circuit 7 drives the energization control element 5 and is composed of transistors 701 to 704 and resistors. When the control means 11 outputs a high signal, the transistor 701 is turned on, and the base of the transistor 702 is the collector of the transistor 701. And is turned off because the base potential is lowered as the transistor 701 is turned on. As a result, the collector of the transistor 702, that is, the potential of the transistor 703 rises, the transistor 703 becomes conductive, current is supplied to the trigger terminal 51 of the energization control element 5, and the potential of the trigger terminal 51 rises, thereby energizing control. The element 5 is made conductive.

  When the control means 11 outputs a low signal, the operations of the transistors 701 to 704 are reversed, the transistor 704 is turned on, current is drawn from the trigger terminal 51 of the energization control element 5, and the potential of the trigger terminal 51 is grounded. The energization control element 5 is kept off while being kept at the level. Since the potential of the trigger terminal 51 of the energization control element 5 is maintained at the ground level by maintaining the transistor 704 on, the energization control element 5 is not erroneously fired due to external noise.

  The first power supply circuit 12 performs half-wave rectification of the commercial power supply 41 using the diode 121 and the resistor 122 and charges the electrolytic capacitor 123. The power supply HIC 124 switches the electric charge of the electrolytic capacitor 123 with an internal semiconductor, resonates with the coil 125 and the reflux diode 126, and smoothes it with the electrolytic capacitor 127.

  The Zener diode 128 and the photocoupler 129 are a feedback circuit of this power supply voltage, and the output voltage of the first power supply circuit 12 is higher than the specified value of the Zener voltage of the Zener diode 128 and the built-in light emitting diode forward voltage of the photocoupler 129. At this time, the built-in light-emitting diode of the photocoupler 129 emits light, and the phototransistor built in the package is turned on, the switching of the semiconductor in the power supply HIC 124 is stopped, the supply of current to the coil 125 is stopped, and the electrolysis is performed. As the electric charge of the capacitor 127 is consumed, the output voltage of the first power supply circuit 12 decreases.

  On the other hand, when the output voltage of the first power supply circuit 12 is lower than the specified value of the Zener voltage of the Zener diode 128 and the built-in light emitting diode forward voltage of the photocoupler 129, the built-in light emitting diode of the photocoupler 129 does not emit light. The phototransistor built in the package does not conduct, and the power source HIC 124 continues to switch the internal semiconductor. Due to resonance of the coil 125 and the freewheeling diode 126, the electrolytic capacitor 127 is charged, and the first The output voltage of the power circuit 12 increases.

  The output voltage of the first power supply circuit 12 needs to match the characteristics of the trigger terminal 51 of the energization control element 5 and is 20 V here.

  The power supply by the first power supply circuit 12 is indicated by “V” 120 in this figure, and is connected to the drive circuit 7, the microcomputer peripheral circuit 10, and the second power supply circuit 13 to supply a power supply current. ing.

  The second power supply circuit 13 forms a drop-type constant voltage circuit by the transistor 131, the resistor 132, and the Zener diode 133. The voltage of 20V supplied from the first power supply circuit 12 is stepped down to 5V, and the electrolytic capacitor 134 is connected. Charge.

  In this drawing, the output of the second power supply circuit 13 is indicated by “VDD” 130, and a current is supplied from the first power supply circuit 12, and a power supply current of 5 V is supplied to the microcomputer 8 and the operation unit 9. Supply.

  The second power supply circuit 13 is not directly supplied with current from the commercial power supply 41, but is supplied with direct current that has been stepped down to 20V by the first power supply circuit 12, thereby suppressing heat generation due to stepping down. The insulation distance is relaxed and the arrangement is compact.

  The power supply voltage changing means 14 switches the output voltage of the first power supply circuit 12, and sets the output voltage set value of the first power supply circuit 12 to the first voltage in a standby state where the heating sequence is not executed. It is configured to switch from the set value to the second voltage set value set lower than that. That is, the Zener diode 128, the Zener diode 141, and the transistor 142 are voltage setting units. When the set value of the output voltage of the first power supply circuit 12 during the heating sequence is the first voltage set value, the transistor 142 is turned off. Then, the Zener diode 128 and the Zener diode 141 are inserted in a voltage feedback loop of the power supply HIC 124 in a state of being connected in series.

  When switching to the second voltage setting value in the standby state where the heating sequence is not executed, the transistor 142 is turned on, both ends of the Zener diode 141 are short-circuited, and only the Zener diode 128 is included in the feedback loop of the power supply HIC 124. Is inserted. In the present embodiment, the Zener diode 128 and the Zener diode 141 are selected so that the first voltage setting value is 20V and the second voltage setting value is 10V.

  Immediately after switching the set value of the output voltage of the first power supply circuit 12 from the first voltage set value to the second voltage set value, it takes time to consume charges, and the voltage across the electrolytic capacitor 127 is There is a possibility that an overcurrent flows through the Zener diode 128, which is the first voltage setting value of 20V and originally has a rated voltage of about 10V. In order to prevent this, a resistor 143 is inserted in the collector of the transistor 142.

  The power supply voltage changing function 144 is a function for outputting an on / off signal to the transistor 142 in order to switch the set value of the output voltage of the first power supply circuit 12 in the microcomputer 8 according to the state of the induction heating device.

  The output of the power supply voltage changing function 144 has two types of low impedance corresponding to the first voltage set value and high impedance corresponding to the second voltage set value. When the output is low, the transistor 142 is turned off and high. When the impedance is output, the transistor 142 is turned on by a current supplied from the resistor 145. In a state other than standby, such as when the heating sequence is being executed, the power supply voltage changing function 144 outputs low.

  The time measuring means 15 measures the elapsed time after the induction heating device finishes the heating sequence and enters the standby state, and the wake-up means 16 is operated by the user through the operation unit 9 during standby. Is performed, the set value of the output voltage of the first power supply circuit 12 is returned from the second voltage set value to the first voltage set value, and details thereof will be described later.

  The operation and action of the above configuration will be described. When the user presses the switch 91 of the operation unit 9 to start the heating sequence, the microcomputer 8 sends a high signal to the drive circuit 7 from the control means 11 built in the microcomputer 8 according to the sequence installed in the memory 81. In response to this, the drive circuit 7 outputs a drive signal to the trigger terminal 51 of the energization control element 5, conducts the energization control element 5, energizes the coil 2, and heats the pot 1.

  Here, in a standby state where the heating sequence is not executed, the power supply voltage changing function 144 outputs high, the transistor 142 constituting the power supply voltage changing means 14 is turned on, both ends of the Zener diode 141 are short-circuited, and the power supply HIC124 In this feedback loop, only the Zener diode 128 is inserted, and the second voltage in which the set value of the output voltage of the first power supply circuit 12 is set lower than the first voltage set value (20V). Switch to the set value (10V). Thereby, the current consumption of the drive circuit 7 can be reduced.

  Further, the LED 101 and the buzzer 102 constituting the microcomputer peripheral circuit 10 are supplied with a power supply current from the first power supply circuit 12, and the voltage setting value of the first power supply circuit 12 is 10V, which is the second voltage setting value. Then it does not work properly. For this reason, the entire standby power can be suppressed.

  In the present embodiment, the output voltage of the first power supply circuit 12 in the standby power reduction state in the standby state is set to 10 V (second voltage setting value). It is a value with a sufficient margin with respect to the output voltage of 5V, a sufficient current flows through the resistor 132 of the second power supply circuit 13, and a sufficient current flows through the base of the transistor 131 and the Zener diode 133. The output voltage 5V of the second power supply circuit 13 has sufficient stability and current supply capability.

  Therefore, in the circuit of the microcomputer peripheral circuit 9 connected to the second power supply circuit 13, the output voltage of the first power supply circuit 12 is the second voltage set value in the standby power reduction state in the standby state. There is no risk of malfunction even when the voltage is 10V.

  Further, in the drive circuit 7, even when the output voltage of the first power supply circuit 12 is 10V which is the second voltage setting value, each of the transistors 701 to 704 is normally maintained in the on / off state. Yes.

  The transistor 704 connected to the trigger terminal 51 of the energization control element 5 is also kept on and the trigger terminal 51 is fixed to the ground level. Even if noise enters from the outside, the energization control element 5 There is no false firing.

  Note that even when the second voltage setting value of the first power supply circuit is set to 4 V, which is a value equal to or lower than 5 V, which is the output voltage of the second power supply circuit 13, the resistor 132 constituting the second power supply circuit 13 is used. On the other hand, since no current flows through the Zener diode 133 below the Zener voltage, the base current of the transistor 131 can be secured, and the output voltage of the second power supply circuit 13 is about 3.5V. Thus, the microcomputer 8 and the microcomputer peripheral circuit 9 can maintain the operation state.

  Since the drive circuit 7 is also supplied with 4V as a power source, as described above, the transistor 704 connected to the trigger terminal 51 of the energization control element 5 is also kept on, and the trigger terminal 51 is fixed to the ground level. Even if noise enters from the outside, the energization control element 5 will not be falsely fired.

  Further, in this state, the standby power becomes a further lower value because the output voltages of the first power supply circuit 12 and the second power supply circuit 13 are further lowered as compared with the above embodiment.

  As described above, in the present embodiment, the power supply voltage changing unit 14 sets the output voltage setting value of the first power supply circuit 12 to the first voltage setting value in the standby state in which the heating sequence is not executed. Since it is configured to switch from (20 V) to the second voltage set value (10 V) set lower than that, the current consumption of the drive circuit 7 is reduced due to the decrease in the output voltage of the first power supply circuit 12 in the standby state. Can be reduced, and as a result, the entire standby power can be suppressed. In this state, since the power supply current is applied to the drive circuit 7, the potential of the trigger terminal 51 of the energization control element 5 is stabilized, and the malfunction tolerance due to noise from the outside is not impaired.

(Embodiment 2)
The time measuring means 15 shown in FIG. 1 measures the elapsed time after the induction heating device finishes the heating sequence and enters the standby state, and the power supply voltage changing means 14 sets the time measured by the time measuring means 15. When the value is exceeded, the output voltage of the first power supply circuit 12 is switched from the first voltage setting value to the second voltage setting value set lower than the first voltage setting value. Other configurations are the same as those of the first embodiment.

  The operation and action of the above configuration will be described with reference to FIG. In addition, since the operation | movement which induction-heats the pan 1 is the same as the said Embodiment 1, description is abbreviate | omitted.

  In step 150 of FIG. 2, the timekeeping time is reset to 0, and in step 151 it is determined whether or not it is in a standby state. If not in the standby state, the process returns to step 150 and the timekeeping time is continuously reset to zero. If it is in the standby state in step 15, the process proceeds to step 152 and time is measured. When the measured time exceeds the set time T in step 153, a signal is output to the power supply voltage changing function 144 in step 154, and the power supply voltage changing function 144 turns on the transistor 142 constituting the power supply voltage changing means 14, As in the first embodiment, the set value of the output voltage of the first power supply circuit 12 is switched from the first voltage set value (20V) to the second voltage set value (10V) set lower than that. As a result, the current consumption of the drive circuit 7 can be reduced, and as a result, the overall standby power can be suppressed.

  As described above, in the present embodiment, the power supply voltage changing unit 14 changes the output voltage of the first power supply circuit 12 from the first voltage set value when the time measured by the time measuring unit 15 exceeds the set value. Since it is configured to switch to the second voltage setting value set lower than that, when the elapsed time after the start of the standby state exceeds the setting value of the time measuring means 15, the output voltage of the first power supply circuit 12 is changed to the first voltage setting value. By setting the second voltage setting value lower than the voltage setting value and lowering the power supply voltage, the current consumption of the drive circuit 7 can be reduced, and as a result, the overall standby power can be suppressed. In this state, since the power supply current is applied to the drive circuit 7, the potential of the trigger terminal 51 of the energization control element 5 is stabilized, and the malfunction tolerance due to noise from the outside is not impaired.

(Embodiment 3)
The wakeup means 16 shown in FIG. 1 outputs a signal to the power supply voltage changing function 144 and sets the output voltage of the first power supply circuit 12 when the user operates the operation unit 9 during standby. The value is returned from the second voltage setting value to the first voltage setting value. Other configurations are the same as those of the first embodiment.

  The operation and action of the above configuration will be described. In addition, since the operation | movement which induction-heats the pan 1 is the same as the said Embodiment 1, description is abbreviate | omitted.

  When the set value of the output voltage of the first power supply circuit 12 enters the standby power reduction state and is the second voltage set value, when the user presses the switch 91 of the operation unit 9, it is detected, The power supply voltage changing function 144 outputs a signal, and the power supply voltage changing function 144 outputs low to the transistor 142, and switches the set value of the output voltage of the first power supply circuit 12 to the first voltage set value of 20V. .

  Immediately after the operation of the switch 91, the power supply voltage changing function 144 that has received a signal from the wake-up means 16 returns the output voltage setting value of the first power supply circuit 12 to the first voltage setting value of 20V. The lighting of the LED 101 and the sounding of the buzzer 102 that occur immediately after the operation 91 is completed can operate normally immediately after the lighting and sounding.

  In the present embodiment, the wake-up unit 16 sets the output voltage setting value of the first power supply circuit 12 to the second voltage setting when the user operates the operation unit 9 during standby. The value is returned to the first voltage setting value, but the user operates the operation unit 9 during standby and after the output voltage of the first power supply circuit 12 reaches the second voltage setting value. When the operation is performed, the set value of the output voltage of the first power supply circuit 12 may be returned from the second output voltage set value to the first output voltage set value, and the same operation and effect can be obtained. Can do.

  As described above, the induction heating device according to the present invention reduces the standby power at a low cost and without reducing the noise immunity by reducing the output voltage of the first power supply circuit in the standby state. Therefore, it is useful as an induction heating device that reduces power consumption in a standby state where the heating sequence is not executed.

Circuit diagram in which the induction heating apparatus according to Embodiment 1 of the present invention is partially blocked Main part operation | movement flowchart of the induction heating apparatus in Embodiment 2 of this invention A partial block diagram of a conventional induction heating device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pan 2 Coil 5 Current supply control element 7 Drive circuit 9 Operation part 11 Control means 12 1st power supply circuit 13 2nd power supply circuit 14 Power supply voltage change means

Claims (4)

A pan housed in the heating device body, a coil for induction heating the bottom of the pan, an energization control element for controlling the current flowing in the coil, a drive circuit for driving the energization control element, an operation unit, Control means for outputting an ON signal to the drive circuit for heating the pan in accordance with a heating sequence designated by the operation unit, a first power supply circuit for supplying a power supply current to the drive circuit, and the first A second power supply circuit that supplies current from the power supply circuit to step down the voltage and supplies the power supply current to the operation unit, the control means, and the like; and power supply voltage changing means that switches an output voltage of the first power supply circuit The power supply voltage changing means sets the output voltage set value of the first power supply circuit lower than the first voltage set value in a standby state where the heating sequence is not executed. Induction heating apparatus configured to switch the voltage setting value. A time measuring means for measuring an elapsed time from the start of the standby state in which the heating sequence is not executed, and the power supply voltage changing means outputs the output of the first power supply circuit when the time measured by the time measuring means exceeds a set value; The induction heating device according to claim 1, wherein the voltage is switched from the first voltage set value to a second voltage set value set lower than the first voltage set value. Wake-up means is added to return the set value of the output voltage of the first power supply circuit from the second voltage set value to the first voltage set value when the user operates on the operation unit during standby. The induction heating apparatus according to claim 1. When the user performs an operation on the operation unit during standby and after the output voltage of the first power supply circuit reaches the second voltage setting value, the setting value of the output voltage of the first power supply circuit The induction heating apparatus according to claim 2, further comprising a wake-up unit that returns the first output voltage set value to the first output voltage set value.

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