JP5315826B2 - Induction heating rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable rice cooker capable of preventing induced electromotive voltage generated in a speaker coil thereby capable of preventing the breakage of sound generating means when actuating a heating coil. <P>SOLUTION: The induction heating rice cooker includes: a sound signal output means 11 for receiving the output of a control means 9 for controlling an inverter circuit 2 for supplying high frequency current to the heating coil 1 and for outputting the sound signal to the speaker 10; a switch circuit 17 for receiving the signal of the control means to close or open a power source circuit to a sound output means; and a speaker closing means 13 for closing or opening the signal path from the sound signal output means to the speaker. The control means closes the power source path of the sound signal output means by the switch circuit and closes the signal path from the sound signal output means to the speaker by a speaker close means when not outputting sound, and further the control means opens the power source path of the sound signal output means by the switch circuit when outputting sound. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an induction heating rice cooker and an induction heating cooker used for general household or business use.

Conventionally, in a cooking device equipped with a voice notification, there is one that reduces power consumption and prevents speaker noise by supplying power to a voice output unit including a voice synthesizer only for a specific period (for example, Patent Document 1).
JP 59-4828

  However, when trying to realize an induction heating rice cooker with the conventional configuration, when a high-frequency current flows through the heating coil, a high-frequency magnetic field from the heating coil propagates to the winding of the speaker, and the winding of the speaker When the induced electromotive voltage is generated and the power of the audio signal output means is off, the induced electromotive voltage exceeds the maximum voltage rating of the audio signal output means, and the audio signal output means is destroyed. .

  When the power of the audio signal output means is on, the output terminal of the audio signal output means is fixed to the intermediate potential of the power supply, high, or low, so that the winding of the speaker Even if an induced electromotive voltage is generated, the maximum voltage rating of the audio signal output means is not exceeded, so that the audio signal output means is not broken by the induced electromotive voltage of the speaker. There was a need to keep the means powered on.

  In this case, noise is generated from the speaker due to the problem that power is consumed even when no sound is output, and the high-frequency magnetic field generated when a high-frequency current flows through the heating coil cannot be saved. It became a problem.

  Further, in order to turn off the power of the audio signal output means and prevent the audio signal output means from being destroyed, it is necessary to reduce the induced electromotive voltage generated in the winding of the speaker. In order to reduce the induced electromotive voltage, the speaker needs to be sufficiently separated from the heating coil, so that the speaker cannot be disposed in the vicinity of the heating coil, the effective space cannot be used, and the size of the device is reduced. There was a problem that it was difficult to convert.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a safe, compact and energy-saving induction heating rice cooker in which an audio signal output means is not broken even if a speaker is arranged in the vicinity of a heating coil. .

In order to solve the conventional problems, an induction heating rice cooker according to the present invention includes a heating coil for induction heating a pan, an inverter circuit for supplying a high-frequency current to the heating coil, and a control means for controlling the inverter circuit. A speaker, an audio signal output unit that outputs an audio signal to the speaker in response to the output of the control unit, and a switch circuit that receives or outputs a signal from the control unit and cuts off or conducts a power path to the audio output unit , Having speaker blocking means for blocking or conducting a signal path from the audio signal output means to the speaker, and the control means cuts off the power supply path of the audio signal output means by the switch circuit when no sound is output. together with, as induced electromotive force in the windings of the speaker at a high-frequency magnetic field to the heating coil is not also applied to the audio signal output means to generate The cut off a signal path to the loudspeaker from the audio signal output means in said speaker blocking means, wherein, when outputting the audio, as well as conducting the power supply path of the audio signal output means in the switching circuit, The speaker blocking means connects a signal path between the speaker and the audio signal output means, and the audio signal output means outputs an audio signal storage circuit that outputs previously stored audio data as a signal, and a signal of the audio signal storage circuit A filter circuit for attenuating a predetermined high frequency component and a predetermined low frequency component, and an audio signal amplifier circuit for amplifying the output signal of the filter circuit, wherein the switch circuit is at least a power source for the audio signal amplifier circuit The path is cut off or conducted, and the speaker cut-off means cuts off the signal path between the speaker and the audio signal output means. Thereafter, a resistor is connected between the input terminal and the ground potential so that the input terminal of the speaker is not opened, and a series circuit of a capacitor and a resistor is arranged in a current path from the audio signal output means to the speaker, Both ends of the speaker are connected in parallel to the resistor, and after the control means brings the switch circuit into a conductive state, the speaker cutoff means brings the series circuit of the capacitor and resistor and the signal path of the speaker into a conductive state. It is.

Thus, when the power of the audio signal output means is turned off, even if an induced electromotive voltage is generated in the winding of the speaker by a high-frequency magnetic field in the heating coil, the speaker cutoff means connects the input terminal of the speaker to the audio. Since it is cut off from the output terminal of the signal output means, the maximum rated voltage of the audio signal output means is not exceeded, and a highly reliable induction heating rice cooker can be provided. Furthermore, since the current path of the speaker is energized in a state where the power of the audio signal output means is turned on, the charging current of the capacitor flows before connecting the current path of the speaker, It is possible to prevent the capacitor charging current from being output as noise sound from the speaker.

  The induction heating rice cooker according to the present invention prevents the audio signal output means from being destroyed even if an induction electromotive force is generated in the speaker by the magnetic field of the heating coil when the power supply of the audio signal output means is stopped. it can.

  An induction heating type rice cooker according to a first aspect of the present invention includes a heating coil for induction heating a pan, an inverter circuit for supplying a high frequency current to the heating coil, a control means for controlling the inverter circuit, a speaker, and the control means. Audio signal output means for outputting an audio signal to a speaker in response to the output of the control circuit, a switch circuit for receiving a signal from the control means and blocking or conducting a power supply path to the audio output means, and the audio signal output means A speaker shut-off means for shutting off or conducting a signal path to a speaker; and when the control means does not output sound, the switch circuit shuts off the power supply path of the sound signal output means and the speaker shut-off means The signal path from the audio signal output means to the speaker is interrupted, and the control means uses the switch circuit to output sound when the audio signal is output. When the power path of the audio signal output means is turned off by conducting the power path of the audio signal output means and connecting the signal path of the audio signal output means with the speaker by the speaker cutoff means, An induced electromotive voltage is generated in the winding of the speaker by a high-frequency magnetic field, but since the speaker shut-off means shuts off the speaker input terminal from the output terminal of the sound signal output means, the maximum of the sound signal output means The rated voltage is not exceeded, the destruction of the audio signal output means can be prevented, and the power of the audio signal output means can be turned off, so that power saving can be realized.

  In addition, since the induced electromotive voltage can be prevented from destroying the audio signal output means, the speaker can be arranged in the vicinity of the heating coil, and an induction heating rice cooker having a compact audio function is provided. it can.

Further, in particular, the audio signal output means, attenuating the audio signal storage circuit for outputting a predetermined frequency components higher than a predetermined or lower frequency component of the signal of the audio signal storage circuit voice data stored in advance as a signal The filter circuit and an audio signal amplifier circuit that amplifies the output signal of the filter circuit, and the switch circuit cuts off or conducts at least the power supply path of the audio signal amplifier circuit, thereby reducing the power supply voltage of the audio signal amplifier circuit. It can be set regardless of the power supply voltage of the control means or the audio signal storage circuit, it becomes possible to increase the power input to the speaker, and the volume can be increased so that even a user with a bad ear or noise during cooking Can hear the voice.

  In addition, when no sound is output, the power supply to the sound signal amplifier circuit is stopped. Therefore, even if a high frequency magnetic field of the heating coil is superimposed on the input portion of the sound signal amplifier circuit as noise, No noise sound is output.

Furthermore, in particular After blocking the signal path of loudspeaker and the audio signal output means in said speaker blocking means, by the input terminal of the speaker is connected a resistor between the input terminal and the ground potential so as not to open, the heating coil Even if an induced electromotive force is generated in the coil of the speaker due to electromagnetic induction that occurs when the pan is induction-heated, the induced electromotive force can be consumed by this resistance. It is possible to prevent an overvoltage from being applied, and it is possible to prevent a failure of the speaker or the speaker blocking means.

Furthermore, in particular arranged a series circuit of a capacitor and a resistor in the current path to the speaker from the speech signal output unit, both ends of the speaker is connected in parallel to the resistor, after the control means has a switching circuit in a conductive state, a speaker Since the interruption means makes the signal path of the speaker and the series circuit of the capacitor and the resistor conductive, the current path of the speaker is energized in a state where the power of the audio signal output means is activated. The capacitor charging current flows before the speaker current path is connected, and the capacitor charging current can be prevented from being output as noise from the speaker.

  Therefore, it is possible to provide an induction heating rice cooker having an easy-to-listen voice guide that does not cause discomfort to the user.

In the second invention, particularly after the speaker shut-off means of the first invention shuts off the signal circuit between the speaker and the series circuit composed of the capacitor and the resistor, the control means shuts off the switch circuit, thereby shutting off the switch circuit. Further, it is possible to prevent the power supply voltage of the sound signal generating means from fluctuating and the voltage fluctuation from being heard as noise noise to the user.

  Therefore, it is possible to provide an induction heating rice cooker having an easy-to-hear voice guide that does not give the user unpleasant feeling when the power of the voice signal output means is turned off.

  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)
In FIG. 1, reference numeral 1 denotes a heating coil for heating a pan, which is composed of a litz wire bundled with copper wires having a small wire diameter, although not particularly shown.

  Reference numeral 2 denotes an inverter circuit, which is composed of an IGBT semiconductor switching element (not shown), a diode reversely connected to the semiconductor switching element, a heating coil and a resonance capacitor that constitutes a resonance circuit. High frequency current is supplied to the heating coil 1 by switching at high frequency.

  The diode bridge 3, the choke coil 4, and the capacitor 5 rectify the commercial power supply 6 and supply power to the inverter circuit 2.

  Reference numeral 7 denotes an input means, which is composed of a plurality of momentary switches, and the user can select the rice cooking method, the start or stop of rice cooking, and the like.

  Reference numeral 8 denotes a display means, which is composed of a liquid crystal display or LED, and displays the contents set by the user, the state of the rice cooker during cooking, during reservation, and the elapsed time of cooking.

  Reference numeral 9 denotes control means, which is not particularly shown, and is composed of a microcomputer, a thermistor for measuring the temperature of the pan, a current transformer for detecting the value of the current supplied from the commercial power source 6, and the like. In response to the input signal of the switch constituting the unit 7, the set content is displayed on the LCD, or the inverter circuit 2 is controlled to be turned on / off to operate the rice cooking sequence and the heat retention sequence set by the input unit 7.

  Reference numeral 10 denotes a speaker, which uses a type in which a coil and a magnet are used, and the coil is vibrated by a current flowing in the winding and a magnetic field of the magnet.

  In the present embodiment, the impedance of the speaker is made larger than 8Ω in order to reduce the current flowing through the speaker. One input terminal of the speaker 10 is connected to the ground potential.

  Reference numeral 11 denotes an audio signal output means, which is constituted by a memory (not shown) that stores audio data as 4-bit data and a DA converter that converts a digital signal output from the memory into an analog signal.

  In this embodiment, the memory and the DA converter are configured separately, but may be configured by a speech synthesis IC in which the two are combined into one IC.

  Reference numeral 12 denotes a DC component cutting capacitor that prevents a DC voltage from being applied to the speaker 10.

  Reference numeral 13 denotes speaker blocking means, which is configured by an IC generally referred to as an analog switch, and blocks or conducts a signal path from the capacitor 12 to the speaker 10.

  When the control means 9 outputs a high or low signal, the analog switch is turned on / off and connected to or disconnected from the input terminal of the speaker 10.

  In the present embodiment, an analog switch is used as the speaker cutoff means 13, but this is an example and is not limited.

  The resistors 18 and 19 are connected to fix the potential of the capacitor 12 and the speaker 10 when the speaker blocking means 13 is blocking the signal path.

  Reference numeral 14 denotes a driving means, which is not particularly shown, but in the present embodiment, it is composed of a push-pull circuit composed of a PNP transistor and an NPN transistor, and receives the on / off signal from the control means 9 to constitute the inverter circuit 2. Turn on and off.

  Reference numeral 15 denotes a first DC power source, which is composed of a switching power source, which rectifies the commercial power source 6 and converts the rectified DC power source of about 141V into a DC power source of about 20V.

  The output voltage 20V of the first DC power supply 15 is a voltage necessary for turning on the IGBT, and is supplied to the IGBT via the driving means 14, and the IGBT is turned on.

  Reference numeral 16 denotes a second DC power supply, which is not particularly shown, and has an emitter follower circuit configuration including an NPN transistor and a Zener diode.

  The voltage of the second DC power supply 16 is about 5V, which serves as a power source for the microcomputer constituting the control means 9 and the audio signal output means 11.

  Reference numeral 17 denotes a switch circuit, which is not particularly shown in the figure, and is composed of a PNP transistor and an NPN transistor. The switch circuit 17 is turned on / off in response to a signal from the control means 9 and outputs an audio signal from the first DC power supply 15. The current path to the means 11 is interrupted or conducted, and the audio signal output means 11 is turned on / off.

  FIG. 2 shows the configuration of the main part of the rice cooker, and in order to simplify the drawing, lead wires for electrical connection and screws for fixing components are omitted.

  A lid (32) covering the upper surface of the body (main body) 31 of the rice cooker is installed to be openable and closable. The housing portion 33 of the body 31 has a heating coil 1 configured in a spiral shape at the bottom, and a ferrite core 34 is arranged on the outer peripheral side of the heating coil 1.

  The heating coil 1 is a winding having a center at substantially the center of the bottom of the pan 35.

  The pan 35 is made of a clad steel plate made of a magnetic material such as stainless steel, iron, or copper. And this pan 35 is detachably accommodated by placing the flange protruding outward from the upper end opening in a state where it floats from the upper end of the accommodating portion 33.

  Therefore, the pan 35 has a gap between it and the storage portion 33 when stored.

  The lid heating plate 36 detachably provided on the lid 32 is formed of a metal such as stainless steel. Although not particularly shown in FIG. 1, reference numeral 37 denotes a lid heating coil, which is built in the lid 32, and in the present embodiment, the lid heating plate 36 is induction-heated. However, this is only an example, and the lid heating coil 37 may be a heater.

  Reference numeral 38 denotes a first circuit board, a switch constituting the input means 7, an LCD constituting the display means 8, an LED, a microcomputer constituting the control means 9, a voice synthesis IC constituting the voice signal output means 11, and a capacitor. 12 etc. are mounted.

  Reference numeral 39 denotes a second circuit board, which is not particularly shown, on which components constituting the inverter circuit 2, a diode bridge 3, a choke coil 4, a capacitor 5, and the like are mounted.

  Reference numeral 40 denotes a retractable power cord storage unit, which is electrically connected to the second circuit board 39 via a lead wire.

  The power cord storage unit 40 can wind up the power cord using a stopper and a spring.

  Reference numeral 41 denotes a temperature detection means, which is not particularly shown in FIG. 1, and is composed of a thermistor and is arranged at the approximate center of the bottom of the pan 35.

  Since the resistance value of the thermistor changes depending on temperature, a voltage dividing circuit is configured by the thermistor and a resistor having a predetermined resistance value, and a predetermined voltage is supplied to both ends of the voltage dividing circuit, thereby the resistance value of the thermistor. Can be converted to analog voltage.

  The microcomputer constituting the control means 9 shown in FIG. 1 estimates the temperature from this analog voltage using a built-in AD converter.

  Although not particularly shown, the first circuit board 38 and the second circuit board 39 are electrically connected by lead wires to realize the circuit configuration shown in FIG.

  As shown in FIG. 2, the speaker 10 is arrange | positioned using the clearance gap formed between the body 31 of the rice cooker, and the heating coil 1, and the output surface is arrange | positioned downward.

  Note that the direction and location of the speaker 10 are not particularly limited, and the output surface may be faced upward, or may be placed on the lid 32 if there is a space.

  FIG. 3 shows a timing chart of the main part at the time of voice output in the rice cooker of the present embodiment.

  (1) shows the voltage waveform of the commercial power source 6.

  (2) shows a waveform that outputs high or low in synchronization with 0 V of the commercial power supply 6 (not particularly shown in FIG. 1).

  (3) shows the on (conductive) and off (cut off) states of the switch circuit 17.

  (4) shows the power supply voltage waveform of the audio signal output means 11.

  (5) shows a transmission signal waveform from the control means 9 to the audio signal output means 11.

  (6) shows ON (conduction) and OFF (blocking) of the speaker blocking means 13.

  (7) indicates the input voltage of the speaker 10.

  (8) shows the on / off state of the IGBT constituting the inverter circuit 2 (on / off state of the driving means 14).

  FIG. 4 shows an operation waveform of each part when a high-frequency current flows through the heating coil 1 in the rice cooker of the present embodiment.

  (1) shows the envelope of the high-frequency current flowing through the heating coil 1.

  (2) shows an induced electromotive voltage waveform generated in the speaker 10 when a high-frequency current flows through the heating coil 1.

This waveform shows the induced electromotive voltage waveform when the speaker shut-off means 13 is turned on.

  (3) shows an induced electromotive voltage waveform generated in the speaker 10 when a high-frequency current flows through the heating coil 1.

This waveform shows an induced electromotive voltage waveform when the speaker cutoff means 13 is turned off.

  About the induction heating type rice cooker of this Embodiment, an operation | movement and an effect | action are demonstrated using FIGS.

  First, when the user operates a switch (input means 7) provided on the first circuit board 39 of FIG. 2, the control means 9 detects a signal from the input means 7.

  Then, at T0 in FIG. 3, the control unit 9 turns on the switch circuit 17 in synchronization with the zero voltage of the commercial power supply 6 and supplies a DC voltage to the audio signal output unit 11.

  At the same time, the control means 9 outputs an ON signal to the speaker shut-off means 13 in synchronization with the zero voltage of the commercial power supply 6, so that the speaker shut-off means 13 is in a conducting state so that a signal can be input to the speaker 10.

  Note that the amount of change at the time of rising of the DC voltage to the audio signal output means 11 may be applied to the speaker 10 via the capacitor 12 and output as noise noise.

  Thereafter, at T2 in FIG. 3, the control unit 9 transmits the volume setting data to the audio signal output unit 11 in synchronization with the zero voltage of the commercial power source 6.

  Thereafter, at T3 in FIG. 3, the control unit 9 transmits address data indicating predetermined audio data to the audio signal output unit 11 in synchronization with the zero voltage of the commercial power supply 6.

  Then, at T4 in FIG. 3, the memory constituting the audio signal output unit 11 outputs predetermined audio digital data to the DA converter based on the transmission data from the control unit 9, and this DA converter outputs the analog voltage. Is output to the speaker 10 via the capacitor 12.

  When an audio signal is input, the speaker 10 vibrates, and this vibration becomes sound and notifies the user of the sound. At this time, the DC component of the audio signal output from the DA converter is removed by the capacitor 12.

  At T5 in FIG. 3, according to the menu set by the input means 7, the control means 9 starts the on / off control of the IGBT constituting the inverter circuit 2 via the drive means 14, supplies high frequency power to the heating coil 1, Heat the pan.

  At T6 in FIG. 3, the audio output ends, and the output voltage of the second DC power supply 16 returns to the original value.

  After that, at T8 in FIG. 3, the control means 9 shuts off the switch circuit 17, stops the power supply to the audio signal output means 11, turns off the speaker shut-off means 13, turns off the input terminal of the speaker 10 and the capacitor 12 Block the signal path.

  Thereafter, the heating coil 1 continues to operate according to a predetermined rice cooking sequence for heating the pan and cooking rice.

In the absence of the speaker shut-off means 13, when the power supply to the audio signal output means becomes 0V, the induced electromotive voltage generated in the speaker 10 when the high frequency current flows through the heating coil 1 exceeds the power supply voltage of the audio signal output means 11, A current flows through the protection diode of the DA converter constituting the audio signal output means 11, and a voltage waveform in which the induced electromotive voltage of the speaker 10 is clamped is output to the terminal of the speaker 10 as shown in FIG. The speaker 1 using the speaker blocking means 13
When the signal path between the zero input terminal and the capacitor 12 is cut off, the induced electromotive voltage of the speaker 10 is not applied to the audio signal output means 11.

  Further, when the signal path between the speaker 10 and the capacitor 12 is blocked by the speaker blocking means 13, the induced electromotive voltage is consumed by the resistor 19 in the circuit consisting only of the speaker 10 and the resistor 19, so that the induced electromotive voltage generated in the speaker 10 is small. Thus, the voltage rating of components such as the analog switch constituting the speaker cutoff means 13 can be reduced.

  Further, since the power supply to the audio signal output means 11 is also stopped, the power consumption is reduced, and the heat generation of the first DC power supply 15 and the second DC power supply 16 can be suppressed.

  In this embodiment, since the control means 9 stores the time of the audio data in advance, the switch circuit 17 is shut off when a predetermined time has elapsed from that time.

  The reason why the interruption timing of the switch circuit 17 is made sufficiently later than the time of the sound data is that the speed of the sound signal output from the sound signal output means 11 varies.

  As described above, when sound is not output, by providing speaker blocking means for blocking the signal path between the speaker input terminal and the sound signal output means, an induced electromotive voltage generated in the speaker when a high-frequency current flows through the heating coil. Can be prevented from being applied to the audio signal output means, so that even if the power supply voltage of the audio signal output means is turned off, the induced electromotive voltage of the speaker does not exceed the maximum rating of the audio signal output means, It is possible to provide an energy-saving rice cooker that does not have a failure.

  Moreover, since the induced electromotive voltage generated in the speaker can be prevented, the speaker can be disposed in the vicinity of the heating coil, and a compact rice cooker can be realized.

(Embodiment 2)
In FIG. 5, reference numeral 51 denotes an audio signal output means, which is a memory 52 (audio signal storage circuit) that stores audio data as 4-bit data, a DA converter 53 that converts a digital signal output from the memory 52 into an analog signal, A high-pass filter 54 that attenuates a low-frequency component of the output signal of the DA converter 53, a filter circuit 56 that includes a low-pass filter 55 that attenuates a high-frequency component, and audio that amplifies the output voltage of the filter circuit 56 at a predetermined magnification The signal amplifying circuit 57 is configured.

In the present embodiment, the high-pass filter 54 is configured by a series circuit of a resistor and a capacitor, and the low-pass filter 55 is configured by a parallel circuit of a resistor and a capacitor. However, this is an example. It may be used to form a digital filter.

  Further, in the present embodiment, the memory 52 and the DA converter 53 are configured separately, but may be configured by a speech synthesis IC in which the two are combined into one IC.

  The audio signal amplifying circuit 57 includes an operational amplifier IC integrated into a circuit and a plurality of resistors.

  Reference numeral 58 denotes a second DC power supply, which is not particularly shown, and is constituted by an emitter follower circuit using an NPN transistor, and supplies a DC power supply of about 5 V to the memory 52 and the DA converter 53.

  Reference numeral 59 denotes a third DC power source, which is not particularly shown, and has the same emitter follower circuit configuration as the second DC power source 58, and the output voltage is about 10V.

When the switch circuit 60 becomes conductive, the third DC power supply 59 is supplied with power from the first DC power supply 15 and outputs a DC voltage of about 10V. In the present embodiment, the third DC power supply 59 supplies a DC voltage to the operational amplifier constituting the audio signal amplifier circuit 57.

  A switch circuit 60 receives a signal from the control means 9 and conducts or interrupts a current path from the first DC power supply 15 to the third DC power supply 59.

  Since the circuit configuration of the switch circuit 60 is the same as that of the switch circuit of FIG. 1, the description thereof is omitted here.

  The other structure is the same as the rice cooker of the 1st form of this invention, and the concrete description uses the thing of Embodiment 1. FIG.

  As described above, in the present embodiment, the audio signal output means 51 includes the memory 52, the DA converter 53, the filter circuit 56, and the audio signal amplifier circuit 57, thereby increasing the power supply voltage of the audio signal amplifier circuit 57. In addition, the voltage input to the speaker 10 can be increased.

  Further, by providing the filter circuit 56, noise noise at the time of DA conversion and noise noise included in the audio data are reduced, so that it is possible to output a voice that is easy to hear.

  Further, when no sound is output, the switch circuit 60 turns off the current path from the first DC power supply 15 to the third DC power supply 59, so that a current flows through the third DC power supply 59 and the audio signal amplifier circuit 57. Power consumption can be saved.

  In addition, since no power is supplied to the speaker 10, noise noise can be prevented.

  As in the first embodiment of the present invention, when the sound signal amplification circuit 57 is powered off, the speaker blocking means 13 blocks the input path of the speaker 10 and the signal path of the sound signal amplification circuit 57. Even if a high frequency current flows through the coil 1 and a high frequency magnetic field is generated, the induced electromotive voltage generated in the winding of the speaker 10 does not exceed the maximum rating of the audio signal amplification circuit 57.

  Accordingly, it is possible to provide a highly reliable rice cooker that can output an easy-to-listen sound with little noise sound at a large volume and can save power.

(Embodiment 3)
FIG. 6 shows a timing chart of the main part at the time of sound output of the rice cooker in the third embodiment of the present invention. In addition, since the principal part circuit structure of the rice cooker of this Embodiment is the same as that of FIG. 5, the description here uses the thing of Embodiment 1. FIG.

  (1) shows the voltage waveform of the commercial power source 6.

  (2) shows a waveform that outputs high or low in synchronization with 0 V of the commercial power supply 6 (not particularly shown in FIG. 1).

  (3) shows the on (conducting) and off (cut off) states of the switch circuit 60.

  (4) shows the output voltage waveform of the third DC power supply 59.

  (5) shows a transmission signal waveform from the control means 9 to the audio signal output means 51.

  (6) shows ON (conduction) and OFF (blocking) of the speaker blocking means 13.

  (7) indicates the input voltage of the speaker 10.

  (8) shows the on / off state of the IGBT constituting the inverter circuit 2 (on / off state of the driving means 14).

  About the induction heating type rice cooker of this Embodiment, operation | movement and an effect | action are demonstrated using FIG.2, FIG.5, FIG.6.

  First, when the user operates a switch (input means 7) provided on the first circuit board 39 of FIG. 2, the control means 9 detects a signal from the input means 7.

  Then, at T0 in FIG. 6, the control means 9 turns on the switch circuit 60 in synchronization with the zero voltage of the commercial power supply 6, activates the third DC power supply 59, and applies a DC voltage to the audio signal amplifier circuit 57. Supply.

  The fluctuation at the rising of the DC voltage is applied to the speaker 10 via the capacitor 18 and may be output as a noise sound.

  However, in the present embodiment, when the speaker blocking means 13 is turned off, signal input to the speaker 10 is prevented, and noise noise is reduced.

  Thereafter, at T1 in FIG. 6, the control means 9 outputs an off signal to the speaker shut-off means 13 in synchronization with the zero voltage of the commercial power supply 6, and the speaker shut-off means 13 is turned off and inputs a signal to the speaker 10. Will be able to.

  Thereafter, at T2 in FIG. 6, the control unit 9 transmits the volume setting data to the audio signal output unit 51 in synchronization with the zero voltage of the commercial power source 6.

  Thereafter, at T3 in FIG. 6, the control unit 9 transmits address data indicating predetermined audio data to the audio signal output unit 51 in synchronization with the zero voltage of the commercial power supply 6.

Then, at T4 in FIG. 6, the memory 52 outputs predetermined audio digital data to the DA converter 53 based on the transmission data from the control means 9, and the DA converter 53 converts the audio signal into an analog voltage. And the audio signal is input to the speaker 10 via the filter circuit 56, the audio signal amplifier circuit 57, and the capacitor 12.

  When an audio signal is input, the speaker 10 vibrates, and this vibration becomes sound and notifies the user of the sound.

  At this time, the low frequency component of the audio signal is attenuated by the high pass filter 54, and the high frequency component is attenuated by the low pass filter 55. The attenuated audio signal is amplified by the audio signal amplification circuit 57, and the DC component of the amplified audio signal is removed by the capacitor 12.

  When the audio signal is output, the voltage of the third DC power supply 59 drops by about 0.2V, but the voltage of the second DC power supply 58 does not change, so that the reference voltage of the AD converter constituting the control means 9 Does not fluctuate.

  Therefore, it is possible to prevent the influence on the detection means using the AD converter, such as the temperature detection of the pan, the detection of the input current, and the voltage detection of the commercial power source.

  At T5 in FIG. 6, according to the menu set by the input means 7, the control means 9 starts on / off control of the IGBT constituting the inverter circuit 2 via the drive means 14, supplies high frequency power to the heating coil 1, Heat the pan.

  At T6 in FIG. 6, the audio output ends, and the output voltage of the third DC power supply 59 returns to the original value.

  At T7 in FIG. 6, the control unit 9 outputs an off signal to the speaker blocking unit 13, and the speaker blocking unit 13 sets the signal path between the input terminal of the speaker 10 and the capacitor 12 to a blocking state.

  After that, at T8 in FIG. 6, the control means 9 turns off the switch circuit 60 and cuts off the current path from the first DC power supply 15 to the third DC power supply 59, so that the third DC power supply 59 Stop power supply.

  The output voltage of the third DC power supply 59 gradually decreases. This voltage change may be applied to the speaker 10 via the capacitor 12 to generate a noise sound.

  However, in the present embodiment, since the speaker blocking means 13 blocks the signal path between the input terminal of the speaker 10 and the capacitor 12, no signal is input to the speaker 10 and no noise sound is generated.

  Therefore, no noise sound is generated when the power of the audio signal amplification circuit 57 is turned on and off, and the user can be prevented from feeling uncomfortable due to the noise sound.

  At this time, when there is no speaker shut-off means 13, when the power supply to the audio signal amplifier circuit 57 becomes 0 V, the induced electromotive voltage generated in the speaker 10 when a high-frequency current flows through the heating coil 1 is the power supply voltage of the audio signal amplifier circuit 57. Current flows through the protection diode of the operational amplifier IC constituting the audio signal amplification circuit 57, and a voltage waveform in which the induced electromotive voltage of the speaker 10 is clamped is output to the terminal of the speaker 10 as shown in FIG. However, when the input terminal of the speaker 10 and the capacitor 12 are blocked using the speaker blocking means 13, it is possible to prevent an induced electromotive voltage from being applied to the audio signal amplification circuit 57.

  In addition, since the third DC power supply 59 is stopped, the power supply to the audio signal amplifier circuit 57 is also stopped, power consumption is reduced, and the first DC power supply 15 and the third DC power supply 59 are not connected. Heat generation can be suppressed.

  In this embodiment, since the control means 9 stores the time of the audio data in advance, the switch circuit 60 is shut off when a predetermined time has elapsed from that time.

  The reason why the switching timing of the switch circuit 60 is made sufficiently later than the time of the audio data is that the speed of the audio signal output from the audio signal output means 51 varies.

  As described above, when the power of the audio signal amplifier circuit 57 is turned on / off, the speaker cutoff means 13 is turned off, thereby preventing the fluctuation voltage of the power supply voltage from being applied to the speaker 10 via the capacitor 12. Therefore, it is possible to prevent the noise from being emitted from the speaker 10.

  Further, when not outputting sound, by providing speaker blocking means 13 for blocking the signal path of the input terminal of the speaker 10 and the capacitor 12, the induced electromotive voltage generated in the speaker 10 when a high-frequency current flows through the heating coil 1. Since application to the audio signal amplifier circuit 17 can be prevented, the induced electromotive voltage of the speaker 10 exceeds the maximum rating of the audio signal amplifier circuit 17 even when the power supply voltage of the audio signal amplifier circuit 17 is turned off. This makes it possible to provide a power-saving rice cooker that is free from breakdowns.

  Moreover, since the induced electromotive voltage generated in the speaker 10 can be prevented, the speaker 10 can be disposed in the vicinity of the heating coil 1 and a compact rice cooker can be realized.

(Embodiment 4)
FIG. 7 shows a circuit configuration of a main part of an induction heating rice cooker according to the fourth embodiment of the present invention.

  A resistor 81 and a capacitor 82 constitute a high-pass filter 93 that attenuates a low-frequency component, and a resistor 83 and a capacitor 84 constitute a low-pass filter 94 that attenuates a high-frequency component.

  The first amplifier circuit includes an operational amplifier 85, a high-pass filter 93, and a low-pass filter 94. The first amplifier circuit attenuates low-frequency components and high-frequency components of the output of the DA converter 53, and inverts and amplifies signals in other frequency bands. Yes.

  The amplification factor of the first amplifier circuit is determined by the ratio of the resistor 83 to the resistor 81.

  The second amplifier circuit includes an operational amplifier 86, a resistor 87, and a resistor 88, and inverts and amplifies the output of the first amplifier circuit.

  The amplification factor of the second amplifier circuit is determined by the ratio of the resistor 87 and the resistor 88.

  In the present embodiment, the ratio between the resistor 87 and the resistor 88 is 1, and the purpose is to invert the output of the first amplifier circuit.

  The output terminal of the operational amplifier 85 is connected to one terminal of the speaker 10 via the first speaker blocking means 89.

  The output terminal of the operational amplifier 86 is connected to the other terminal of the speaker 10 via the second speaker blocking means 90.

  The first speaker blocking means 89 is connected to one input terminal of the speaker 10 to connect or block the input terminal of the speaker 10 and the ground potential.

  The second speaker blocking means 90 is connected to the other input terminal of the speaker 10 to connect or block the speaker input terminal and the ground potential.

  The power of the memory 52 (voice storage circuit) and the DA converter 53 constituting the audio signal output means 92 is supplied from a third DC power supply 95.

  The third DC power supply 95 has a configuration of an emitter follower circuit similar to the third DC power supply 59 of the rice cooker of FIG. 5, but the output voltage is about 5V.

  The resistors 96 and 97 both have one terminal connected to the input terminal of the speaker 10 and the other terminal connected to the ground potential.

  The reason why the resistor 96 and the resistor 97 are connected in this way is that the first speaker blocking means 89 and the second speaker blocking means 90 input the speaker 10 when the signal path of the speaker 10, the operational amplifier 85, and the operational amplifier 86 is blocked. This is because the terminal is stabilized at the ground potential, and even if an induced electromotive voltage is generated in the coil of the speaker 10 by the magnetic field of the heating coil 1, energy due to the induced electromotive voltage can be consumed via the resistor 96 and the resistor 97.

  About another structure, it is the same as that of the main circuit diagram of the rice cooker of FIG. 5, and the thing of Embodiment 1, 2 is used for specific description.

  By performing inverting amplification using two operational amplifiers as shown in FIG. 7, almost the same voltage as the power supply voltage of the operational amplifiers 85 and 86 can be applied to the speaker 10. Can be made the same as the power supply voltage of the memory 52 (audio signal storage circuit) and the DA converter 53.

  Accordingly, the power of all the components constituting the audio signal output unit 92 can be turned off, so that power saving can be realized.

  Further, since the rise of the output voltage of the two operational amplifiers is almost the same, the noise sound is not applied to the speaker 10 when the power supply of the operational amplifiers 85 and 86 is turned on, which may cause discomfort to the user. Absent.

  In addition, since the high-pass filter 93, the low-pass filter 94, and the operational amplifier 85 constitute the first amplifier circuit, it is possible to reduce the number of parts for the filter circuit and to implement a compact audio output means.

  As described above, in this embodiment, by using the two operational amplifiers 85 and 86 so that the voltage almost the same as the power supply voltage can be output, one power supply for the components constituting the audio signal output means 92 is shared. It can be turned on and off.

  Thereby, it is possible to realize power saving when no sound is output.

Further, when the power of the audio signal output means 92 is off, the first speaker blocking means 89
And the second speaker shut-off means 90 are turned on, and both of the input terminals of the speaker 10 are connected to the ground potential, so that the induced electromotive voltage generated in the speaker winding can be reduced, and the audio signal even when the power is turned off. The output means 92 is not destroyed, and high reliability can be obtained.

(Embodiment 5)
FIG. 8: has shown the timing chart of the principal part at the time of the audio | voice output of the induction heating type rice cooker in the 5th Embodiment of this invention. Since the circuit configuration is the same as in FIG. 7, the specific description uses Embodiments 1 to 4.

  (1) shows the voltage waveform of the commercial power source 6.

  (2) shows a waveform that outputs high or low in synchronization with 0 V of the commercial power supply 6 (not particularly shown in FIG. 7).

  (3) shows the on (conducting) and off (cut off) states of the switch circuit 60.

  (4) shows the output voltage waveform of the third DC power supply 95.

  (5) shows a transmission signal waveform from the control means 9 to the audio signal output means 92.

  (6) shows the on (conducting) and off (blocking) states of the first speaker blocking means 89 and the second speaker blocking means 90.

  (7) shows the output voltage waveform of the operational amplifier 85.

  (8) shows the output voltage waveform of the operational amplifier 86.

  (9) shows the voltage waveform across the speaker 10.

  (10) shows the on / off state of the IGBT constituting the inverter circuit 2 (the on / off state of the driving means 14).

  About the induction heating type rice cooker of this Embodiment, an operation | movement and an effect | action are demonstrated using FIG.2, FIG.7, FIG.8.

  First, when the user operates a switch (input means 7) provided on the first circuit board 39 of FIG. 2, the control means 9 detects a signal from the input means 7.

Then, at T0 in FIG. 8, the control means 9 outputs an off signal to the first speaker shutoff means 89 and the second speaker shutoff means 90 in synchronization with the zero voltage of the commercial power supply 6, and the input of the speaker 10 The signal path between the terminal and the operational amplifier 85 and the operational amplifier 86 is made conductive, so that a signal can be input to the speaker 10.

  Thereafter, at T 1 in FIG. 8, the switch circuit 60 is turned on, the third DC power supply 95 is activated, and a DC voltage is supplied to the audio signal output means 92. Although the output voltages of the operational amplifier 85 and the operational amplifier 86 fluctuate when the DC voltage rises, since the output voltages of the two operational amplifiers are the same, the voltage across the speaker 10 becomes 0 V, and no sound is output from the speaker 10.

The power supply voltage is input to the operational amplifier 85 and the operational amplifier 86 with the first speaker cutoff unit 89 and the second speaker cutoff unit 90 turned off, and then the first speaker cutoff unit 89 and the second speaker cutoff are performed. Even when the means 90 is turned on, the fluctuation of the voltage across the speaker 10 is 0 V, and the same effect can be obtained.

  Thereafter, at T2 in FIG. 8, the control unit 9 transmits the volume setting data to the audio signal output unit 92 in synchronization with the zero voltage of the commercial power supply 6.

  Thereafter, at T3 in FIG. 8, the control unit 9 transmits address data indicating predetermined audio data to the audio signal output unit 92 in synchronization with the zero voltage of the commercial power supply 6.

  Then, at T4 in FIG. 8, the memory 52 outputs predetermined audio digital data to the DA converter 53 based on the transmission data from the control means 9, and the DA converter 53 converts the audio signal into an analog voltage. And an audio signal is input to the speaker 10 via the first amplifier circuit and the second amplifier circuit.

  As a sound signal input to the speaker 10, a voltage difference between the output voltages of the operational amplifier 85 and the operational amplifier 86 is input. When an audio signal is input, the speaker 10 vibrates, and this vibration becomes sound and notifies the user of the sound.

  When the audio signal is output, the voltage of the third DC power supply 95 decreases by about 0.2 V, but the voltage of the second DC power supply 58 does not change, so that the reference voltage of the AD converter that constitutes the control means 9 Does not fluctuate.

  Therefore, it is possible to prevent the influence on the detection means using the AD converter, such as the temperature detection of the pan, the detection of the input current, and the voltage detection of the commercial power source.

  At T5 in FIG. 8, according to the menu set by the input means 7, the control means 9 starts on / off control of the IGBT constituting the inverter circuit 2 via the drive means 14, supplies high-frequency power to the heating coil 1, Heat the pan.

  At T6 in FIG. 8, the audio output ends, and the output voltage of the third DC power supply 95 returns to the original value.

  At T7 in FIG. 8, the control means 9 turns off the switch circuit 60, cuts off the current path from the first DC power supply 15 to the third DC power supply 95, and supplies power to the third DC power supply 95. Stop.

  The output voltage of the third DC power supply 95 gradually decreases. This voltage change may be applied to the speaker 10 via the operational amplifier, resulting in noise.

  However, in the present embodiment, since the output voltages of the two operational amplifiers 85 and 86 are the same, the voltage across the speaker 10 does not fluctuate, and no noise sound is generated from the speaker 10.

  Therefore, no noise sound is generated when the power of the audio signal output means 92 is turned on and off, and the user can be prevented from feeling uncomfortable due to the noise sound.

  Thereafter, at T8 in FIG. 8, the control unit 9 outputs an ON signal to the first speaker blocking unit 89 and the second speaker blocking unit 90, and the first speaker blocking unit 89 is connected to one input terminal of the speaker 10. The signal path of the operational amplifier 85 is cut off, and the second speaker cut-off means 90 puts the signal path of the other input terminal of the speaker 10 and the operational amplifier 86 into a cut off state.

  If the first speaker shut-off means 89 and the second speaker shut-off means 90 are not provided and the power supply to the audio signal output means 92 is 0 V, induction that occurs in the speaker 10 when a high-frequency current flows through the heating coil 1 The electromotive voltage exceeds the power supply voltage of the operational amplifier 85 and the operational amplifier 86, a current flows through the protective diodes of the operational amplifiers 85 and 86, and a voltage waveform in which the induced electromotive voltage of the speaker 10 is clamped as shown in FIG. However, since the first speaker blocking unit 89 and the second speaker blocking unit 90 are used to block the signal path of the input terminal of the speaker 10, the operational amplifier 85, and the operational amplifier 86, the operational amplifier 85 and the operational amplifier 86. Therefore, it is possible to prevent an excessive induced electromotive voltage from being applied.

  In addition, since there are the resistor 96 and the resistor 97, even if an induced electromotive force is generated in the speaker 10, the induced electromotive force is consumed through the resistor 96 and the resistor 97. Therefore, the voltage generated at both ends of the speaker 10 is As a result, the maximum rated voltage of the first speaker cutoff unit 89 and the second speaker cutoff unit 90 can be reduced.

  Further, since the third DC power supply 95 is stopped, the power supply to the audio signal output means 92 is also stopped, power consumption is reduced, and the first DC power supply 15 and the third DC power supply 95 generate heat. Can be suppressed.

  In the present embodiment, since the control means 9 stores the time of the audio data in advance, the switch circuit 60 is turned off when the predetermined time has elapsed from that time, and the first DC power supply 15 supplies the first time. The current path to the third DC power source 95 is cut off.

  The reason why the OFF timing of the switch circuit 60 is made sufficiently later than the time of the sound data is that the speed of the sound signal output from the sound signal output means 92 varies.

  As described above, when the audio signal amplifier circuit is configured by using the first amplifier circuit and the second amplifier circuit, the first speaker blocking means 89 and the second amplifier circuit are connected while the power is input to the audio signal amplifier circuit. The second speaker shut-off unit 89 and the second speaker shut-off unit 90 are turned off while the speaker shut-off unit 90 is turned on and the power of the audio signal amplifier circuit is turned off. Since an induced electromotive voltage generated in the speaker 10 when a high-frequency current flows can be reduced from being applied to the output terminals of the operational amplifier 85 and the operational amplifier 86, the induction of the speaker can be achieved even when the power supply voltage of the audio signal amplifier circuit is turned off. The electromotive voltage does not exceed the maximum rating of the audio signal amplifier circuit, and a power-saving rice cooker that does not have a failure can be provided.

(Embodiment 6)
FIG. 9 shows a timing chart of the main part at the time of sound output of the induction heating rice cooker in the sixth embodiment of the present invention. Since the circuit configuration is the same as that in FIG. 7, the description here uses the one in the previous embodiment.

  (1) shows the voltage waveform of the commercial power source 6.

  (2) shows a waveform that outputs high or low in synchronization with 0 V of the commercial power supply 6 (not particularly shown in FIG. 7).

  (3) shows the on (conducting) and off (cut off) states of the switch circuit 60.

  (4) shows the output voltage waveform of the third DC power supply 95.

  (5) shows a transmission signal waveform from the control means 9 to the audio signal output means 92.

  (6) shows the on (conducting) and off (blocking) states of the first speaker blocking means 89 and the second speaker blocking means 90.

  (7) shows the output voltage waveform of the operational amplifier 85.

  (8) shows the output voltage waveform of the operational amplifier 86.

  (9) shows the voltage waveform across the speaker 10.

  (10) shows the on / off state of the IGBT constituting the inverter circuit 2 (the on / off state of the driving means 14).

  About the induction heating type rice cooker of this Embodiment, an operation | movement and an effect | action are demonstrated using FIG.2, FIG.9, FIG.9.

  First, in FIG. 9, the user has already operated a switch (input means 7) provided on the first circuit board 39 of FIG. 2 to perform a predetermined rice cooking operation.

  That is, the control means 9 controls the inverter circuit 2 via the drive means 14, supplies a high-frequency current to the heating coil 1, and induction-heats the pan. In the above state, it is assumed that the user has pressed a switch constituting the input means 7.

  Then, at T0 in FIG. 9, the control means 9 outputs an ON signal to the first speaker cutoff means 89 and the second speaker cutoff means 90 in synchronization with the zero voltage of the commercial power supply 6, and the input of the speaker 10 The signal path between the terminal, the operational amplifier 85 and the operational amplifier 86 is made conductive, so that a signal can be input to the speaker 10.

  Thereafter, at T 1 in FIG. 9, the switch circuit 60 is turned on, the third DC power supply 95 is activated, and a DC voltage is supplied to the audio signal output means 92. Although the output voltages of the operational amplifier 85 and the operational amplifier 86 fluctuate when the DC voltage rises, since the output voltages of the two operational amplifiers are the same, the voltage across the speaker 10 becomes 0 V, and no sound is output from the speaker 10.

  Thereafter, at T2 in FIG. 9, the control unit 9 transmits the volume setting data to the audio signal output unit 92 in synchronization with the zero voltage of the commercial power source 6.

  At this time, the control means 9 outputs an off signal to the drive means 14 and stops the operation of the inverter circuit 2.

  When the control means 9 finishes transmitting the volume setting data to the audio signal output means 92, the control means 9 outputs an on / off signal to the drive means 14 in synchronization with the zero voltage of the commercial power supply 6 at T3 in FIG. The operation of the inverter circuit 2 is started.

  Thereafter, at T4 in FIG. 9, the control unit 9 transmits address data indicating predetermined audio data to the audio signal output unit 92 in synchronization with the zero voltage of the commercial power source 6. At this time, the control means 9 outputs an off signal to the drive means 14 and stops the operation of the inverter circuit 2.

  Then, at T5 in FIG. 9, the memory 52 outputs predetermined audio digital data to the DA converter 53 based on the transmission data from the control means 9, and the DA converter 53 converts the audio signal into an analog voltage. And an audio signal is input to the speaker 10 via the first amplifier circuit and the second amplifier circuit.

  As a sound signal input to the speaker 10, a voltage difference between the output voltages of the operational amplifier 85 and the operational amplifier 86 is input.

  When an audio signal is input, the speaker 10 vibrates, and this vibration becomes sound and notifies the user of the sound.

  When the audio signal is output, the voltage of the third DC power supply 95 decreases by about 0.2 V, but the voltage of the second DC power supply 58 does not change, so that the reference voltage of the AD converter that constitutes the control means 9 Does not fluctuate.

  Therefore, it is possible to prevent the influence on the detection means using the AD converter, such as the temperature detection of the pan, the detection of the input current, and the voltage detection of the commercial power source.

  At T6 in FIG. 9, the control means 9 outputs an on / off signal to the drive means 14 in synchronization with the zero voltage of the commercial power supply 6, and starts the operation of the inverter circuit 2 again.

  At T7 in FIG. 9, the audio output ends, and the output voltage of the third DC power supply 95 returns to the original value.

  At T8 in FIG. 9, the control means 9 turns off the switch circuit 60, cuts off the current path from the first DC power supply 15 to the third DC power supply 95, and supplies power to the third DC power supply 95. Stop.

  The output voltage of the third DC power supply 95 gradually decreases. This voltage change may be applied to the speaker 10 via the operational amplifier, resulting in noise.

  However, in the present embodiment, since the output voltages of the two operational amplifiers 85 and 86 are the same, the voltage across the speaker 10 does not fluctuate, and no noise sound is generated from the speaker 10.

  Therefore, no noise sound is generated when the power of the audio signal output means 92 is turned on and off, and the user can be prevented from feeling uncomfortable due to the noise sound.

  Thereafter, at T9 in FIG. 9, the control means 9 outputs an off signal to the first speaker blocking means 89 and the second speaker blocking means 90, and the first speaker blocking means 89 and the second speaker blocking means 90 are The signal path of the input terminal of the speaker 10 and the operational amplifier 85 and operational amplifier 86 is cut off.

  If the first speaker shut-off means 89 and the second speaker shut-off means 90 are not provided and the power supply to the audio signal output means 92 is 0 V, induction that occurs in the speaker 10 when a high-frequency current flows through the heating coil 1 The electromotive voltage exceeds the power supply voltage of the operational amplifier 85 and the operational amplifier 86, a current flows through the protective diodes of the operational amplifiers 85 and 86, and a voltage waveform in which the induced electromotive voltage of the speaker 10 is clamped as shown in FIG. If the input terminal of the speaker 10 and the signal path of the operational amplifier 85 and the operational amplifier 86 are blocked using the first speaker cutoff means 89 and the second speaker cutoff means 90, the operational amplifier 85 and the operational amplifier 86 It is possible to prevent an excessive induced electromotive voltage from being applied to the output terminal.

  Further, since the third DC power supply 95 is stopped, the power supply to the audio signal output means 92 is also stopped, power consumption is reduced, and the first DC power supply 15 and the third DC power supply 95 are connected. Heat generation can be suppressed.

  In the present embodiment, since the control means 9 stores the time of the audio data in advance, the switch circuit 60 is turned off when the predetermined time has elapsed from that time, and the first DC power supply 15 supplies the first time. The current path to the third DC power source 95 is cut off. The reason why the OFF timing of the switch circuit 60 is made sufficiently later than the time of the sound data is that the speed of the sound signal output from the sound signal output means 92 varies.

  As mentioned above, in the rice cooker of this Embodiment, since the control means 9 stops operation | movement of the inverter circuit 2 when transmitting a signal to the audio | voice signal output means 92, the noise when the inverter circuit 2 operate | moves is generated. It can be prevented from being superimposed on the transmission signal, and a predetermined sound can be output reliably.

  As described above, the induction heating rice cooker according to the present invention can prevent the induced electromotive voltage generated in the winding of the speaker from destroying the sound output means and can turn off the power of the sound output means. Therefore, it can be applied to uses such as induction heating cookers.

Main part circuit diagram of rice cooker in Embodiment 1 of the present invention Typical sectional drawing of the rice cooker in Embodiment 1-6 of this invention. Timing chart at the time of voice output of rice cooker in Embodiment 1 of the present invention Main part operation waveform diagram of rice cooker in Embodiment 1 of the present invention Main part circuit diagram of rice cooker in Embodiment 2, 3 of this invention Timing chart at the time of voice output of rice cooker in Embodiment 3 of the present invention Main part circuit diagram of rice cooker in Embodiment 4, 5, 6 of this invention Timing chart during voice output of rice cooker in embodiment 5 of the present invention Timing chart at the time of voice output of rice cooker in Embodiment 6 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating coil 2 Inverter circuit 9 Control means 10 Speaker 11 Audio | voice signal output means 12 Capacitor 13 Speaker interruption | blocking means 17 Switch circuit

Claims (2)

A heating coil for inductively heating the pan, an inverter circuit for supplying a high-frequency current to the heating coil, a control means for controlling the inverter circuit, a speaker, and outputting an audio signal to the speaker in response to the output of the control means An audio signal output unit; a switch circuit that receives or outputs a signal from the control unit; interrupts or conducts a power path to the audio output unit; and a speaker cutoff that interrupts or conducts a signal path from the audio signal output unit to the speaker. And when the control means does not output sound, the switch circuit cuts off the power supply path of the sound signal output means, and an induction electromotive voltage is generated in the winding of the speaker by a high-frequency magnetic field in the heating coil. so as not to be applied to the audio signal output unit also, the speaker from the speech signal output means by the speaker interrupting means When the control means outputs a sound, the control circuit conducts the power supply path of the sound signal output means by the switch circuit, and the speaker shut-off means connects the speaker and the sound signal output means. The audio signal output means connects an audio signal storage circuit that outputs audio data stored in advance as a signal, a predetermined high frequency component and a predetermined low frequency component of the audio signal storage circuit. A filter circuit for attenuating; and an audio signal amplifying circuit for amplifying an output signal of the filter circuit, wherein the switch circuit cuts off or conducts at least a power supply path of the audio signal amplifying circuit, and the speaker cut-off means turns off the speaker. So that the input terminal of the speaker is not opened after the signal path of the audio signal output means is blocked. A resistor is connected between the terminal and the ground potential, a series circuit of a capacitor and a resistor is arranged in a current path from the audio signal output means to the speaker, and both ends of the speaker are connected in parallel to the resistor, and the control means An induction heating rice cooker in which, after the switch circuit is turned on, the speaker shut-off means brings the series circuit of the capacitor and resistor and the signal path of the speaker into a conductive state. The induction heating rice cooker according to claim 1, wherein the control means shuts off the switch circuit after the speaker shut-off means shuts off the signal path between the speaker and the series circuit composed of a capacitor and a resistor.

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