JP2013157143A - Power supply synchronization circuit and heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply synchronization circuit detecting a synchronization signal synchronized with a supply power, capable of reducing power consumption at standby without using a complicated structure nor a special member.SOLUTION: A power supply synchronization circuit 4 comprises: a first circuit C1 in which resistor parts Rv1 and Rv2 with variable resistance values, an input part 61 of insulation type signal communication means 6 communicating current flowing in a circuit as a signal to the other circuit, and a diode 8 for protecting the input part 61, are connected; a second circuit C2 connecting between an output part 62 of the insulation type signal communication means 6 and control means 5; and resistance adjustment means 7 adjusting the resistance values of the resistor parts on the basis of a control signal from the control means 5.

Description

  The present invention relates to a cooking device equipped with a radio wave generator, and more particularly to a power supply synchronization circuit that can reduce power consumption during standby.

  The cooking device has a so-called microwave function in which microwaves are applied to the article to be heated contained in the heating chamber, the moisture inside the article to be heated is vibrated, and heated by the frictional heat. Is almost. Such a heating cooker includes a radio wave generator that generates the microwave and a control circuit that controls the entire heating cooker including the radio wave generator.

  Further, the heating cooker converts alternating current from a commercial power source into high-voltage alternating current, supplies the radio wave generator with a high-voltage power supply circuit, converts alternating current from the commercial power source into low-voltage direct current, and the control circuit And a low-voltage power supply circuit for supplying to the power supply. In a conventional cooking device, the low-voltage power supply circuit includes a low-voltage transformer, and generates a direct current using the low-voltage transformer.

  In recent years, household appliances that are used on a daily basis, such as heating cookers, have been required to save power, and in some countries, laws related to power consumption have been promoted. In the heating cooker as described above, in order to meet such a demand for power saving, the low-voltage power supply circuit is switched from one using a low-voltage transformer to one using a switching power supply circuit with low power consumption. is there.

  The control circuit acquires a synchronization signal synchronized with the alternating current from the commercial power source in order to suppress an inrush current in the radio wave generator. In the case where a low-voltage power supply circuit using the low-voltage transformer is provided, a synchronization signal synchronized with the power supply phase of the commercial power supply and the commercial frequency is obtained from the secondary side of the low-voltage transformer. However, in the case of using a switching power supply circuit, since the alternating current from the commercial power supply is smoothed once and then converted using a switching element or the like, a synchronization signal cannot be obtained from the switching power supply circuit.

  Thus, a power supply synchronization circuit that uses a photocoupler to acquire a synchronization signal synchronized with an alternating current from a commercial power supply has been proposed. FIG. 6 is a diagram showing an electrical connection of a conventional power supply synchronization circuit. As shown in FIG. 6, the power supply synchronization circuit includes a photocoupler 6 that insulates a circuit C91 through which the same alternating current as the alternating current supplied to the high-voltage power supply circuit 2 flows from a circuit C92 through which the direct current from the switching power supply circuit 91 flows. ing. That is, the photocoupler 6 includes a light emitting diode 61 and a light receiving element (phototransistor) 62. The light emitting diode 61 of the photocoupler 6 is connected to the circuit C91, and the phototransistor 62 is connected to the circuit C92. By using the coupler 6, the circuit C91 and the circuit C92 are electrically insulated.

  The circuit C91 is a circuit through which alternating current from a commercial power source flows, and is supplied with alternating current of about 100V to about 240V. The circuit C91 includes two terminals T91 and T92, and an alternating current is applied to the terminals T91 and T92. In the circuit C91, the resistor Rp, the light emitting diode 61, and the rectifying diode 8 are connected in series from the terminal T91 side. The resistor Rp is a resistor for determining the current supplied to the light emitting diode 61. The light emitting diode 61 has an anode side terminal connected to the resistor Rp. The cathode of the light emitting diode 61 and the anode of the rectifying diode 8 are connected, and the anode of the rectifying diode 8 is connected to the terminal T92.

  In the circuit C91 having this configuration, the current is rectified by the rectifying diode 8, and a current flows only from the terminal T91 side toward the terminal T92 side. That is, the light emitting diode 61 emits light during a half cycle in which the terminal T91 is at a higher voltage than the terminal T92.

  The circuit C92 is supplied with direct current from the switching power supply circuit 91, and the switching power supply circuit 91 is connected to the collector of the phototransistor 62. A control circuit 95 is connected to the emitter of the phototransistor 62. In the photocoupler 6, the phototransistor 62 is an element in which a current flows from the collector to the emitter when detecting light of a certain intensity or more emitted from the light emitting diode 61. A resistor Rs is connected to the wiring connecting the emitter of the phototransistor 62 and the control circuit 95. As a result, when the collector-emitter becomes conductive, a current is drawn from the switching power supply circuit 91 and a synchronization signal (voltage) is input to the control circuit 95.

  In the circuit C91, since the light emitting diode 61 emits light for half a period of commercial power, the phototransistor 62 causes a current to flow from the collector to the emitter during a half period synchronized with the commercial power. By using such a power supply synchronization circuit provided with the photocoupler 6, the control circuit 95 acquires a square-wave synchronization signal in which the half-wavelength of the alternating current of the commercial power supply is Hi and the remaining half-wavelength is Lo (for example, JP, 2011-60566, A). The synchronization signal is used not only for driving the radio wave generator but also for controlling a device (for example, a door opening / closing detection switch or a clock) that continues to operate even during standby such as a clock or an input unit.

  The control circuit 95 can control the radio wave generator more accurately as the synchronization between the synchronization signal and the AC of the commercial power supply is more accurate. In order to increase the accuracy of synchronization between the synchronization signal and the AC of the commercial power supply, the circuit C91 is configured so that when forward power begins to flow through the light emitting diode 61, the light immediately becomes light that can be detected by the phototransistor 62 ( Resistance Rp and the like).

JP 2011-60566 A

  In the power supply synchronization circuit shown in FIG. 6, alternating current from a commercial power supply is applied to the circuit C91 even when the heating operation is not performed (during standby). Therefore, in the power supply synchronization circuit, the same synchronization signal as that during the heating operation (load operation) is generated even during standby. Since the cooking device is equipped with a device that requires a synchronization signal even during standby such as a clock, generation of the synchronization signal cannot be stopped. And the electric power (standby electric power) consumed at the time of the generation | occurrence | production of a synchronizing signal is the hindrance of power saving.

  Therefore, the present invention is a power supply synchronization circuit that detects a synchronization signal synchronized with supply power, and can reduce power consumption during standby without using a complicated structure or special member, and heating. The purpose is to provide a cooker.

  In order to achieve the above object, the present invention provides a resistance section having a variable resistance value, an input section of an insulated signal transmission means for transmitting a current flowing through the circuit to another circuit as a signal, and protection of the input section. A first circuit to which an AC is applied and an alternating current is applied; a second circuit to which an output of the insulated signal transmission means and a control means are connected and a direct current is applied; the first circuit; A resistance adjusting unit that insulates the second circuit and adjusts a resistance value of the resistance unit based on a control signal from the control unit, wherein the control unit is connected to the insulation type signal transmission unit. A power supply synchronization circuit for detecting a synchronization signal synchronized with the alternating current from the power supply is provided.

  According to this configuration, it is possible to change the value of the current flowing through the first circuit by switching the resistance value of the resistance unit. Further, the accuracy of the signal transmitted to the second circuit is changed by changing the value of the current flowing through the first circuit. Therefore, by adjusting the resistance value of the resistance section by the resistance adjusting means, the synchronization accuracy of the synchronization signal detected by the control means with respect to the alternating current from the power source can be adjusted. Further, the current value can also be adjusted by adjusting the resistance value of the resistance portion by the resistance adjusting means.

  Thereby, by adjusting the resistance value of the resistance section by the resistance adjusting means, it is possible to adjust the accuracy of the synchronization signal and reduce the power consumption.

  In the above configuration, the insulating signal transmission means may be a photocoupler, the input unit may be a light emitting diode, and the output unit may be a phototransistor.

  According to this configuration, when the current flowing through the first circuit is large, the synchronization accuracy of the synchronization signal with respect to the alternating current from the power source is high, and when the current is small, the synchronization accuracy of the synchronization signal with respect to the alternating current from the power source is suppressed. As a result, a synchronization signal with high synchronization accuracy can be acquired only when the control means is necessary, and a synchronization signal with low power consumption can be acquired at other times. Can be suppressed.

  In the above configuration, the resistance unit includes a first resistance unit and a second resistance unit having a resistance value smaller than that of the first resistance unit and in parallel with the first resistance unit, and the resistance adjusting unit. May include an insulation switch that switches between conduction and non-conduction of the second resistance unit based on a control signal from the control means.

  In the above configuration, the insulation switch includes a relay, and the relay is arranged such that a contact is in series with the second resistance portion and parallel to the first resistance portion, and the contact is not contacted. A solenoid to be operated may be included in the second circuit.

  In the above configuration, a switching element may be connected to the solenoid, and the switching element may control on / off of a current flowing through the solenoid based on a control signal from the control means.

  In the above configuration, the apparatus including the power supply synchronization circuit includes a radio wave generator that generates high-frequency and high-voltage power and generates microwaves, and a high-voltage power supply circuit that supplies high-frequency and high-voltage power to the radio wave generator, The first circuit is connected in parallel with the high-voltage power supply circuit, and the control means generates the radio wave so that the second resistance unit is in a non-conductive state when the radio wave generator is stopped. A heating cooker that controls the insulation switch so that the second resistance portion is in a conductive state during a load operation when the machine is operating can be mentioned.

  According to the present invention, a power supply synchronization circuit capable of adjusting the accuracy of a synchronization signal synchronized with an alternating current supplied as necessary and reducing power consumption during standby without using a complicated structure or a special member. Can be provided.

  Moreover, by adjusting the accuracy of the synchronization signal, it is possible to provide a heating cooker that can reduce power consumption during standby without degrading the accuracy of the operation of a device with a highly accurate synchronization signal. it can.

It is a perspective view of an example of the cooking-by-heating machine concerning the present invention. It is a block diagram which shows the electrical connection of the heating cooker concerning this invention. It is a figure which shows the electrical connection of an example of the heating cooker shown in FIG. It is a timing chart which shows the commercial power supply at the time of standby, a synchronous signal, etc. It is a timing chart which shows a commercial power source, a synchronous signal, etc. at the time of load operation. It is a figure which shows the electrical connection of the conventional power supply synchronous circuit.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an example of a heating cooker according to the present invention, and FIG. 2 is a block diagram showing an electrical connection of the heating cooker according to the present invention.

  As shown in FIG. 1, the cooking device A includes a heating chamber Hr and a door Dr. The heating cooker A is provided with a door Dr provided at a front opening, and stores an article to be heated (heating article) in the heating chamber Hr by opening the door Dr. In the heating cooker A, the article to be heated is placed on the turntable TT disposed inside the heating chamber, the door Dr is closed, and the article to be heated is cooked while rotating the turntable TT.

  Each part of the heating cooker A will be described with reference to the drawings. As shown in FIG. 2, the cooking device A includes a switching power supply circuit 1, a high voltage power supply circuit 2, a radio wave generator 3, a heater Ht, a steam generator Vp, a power supply synchronization circuit 4, an input unit It, a display unit Mt, a door. An open / close detection switch Os, a clock Wt, a control circuit 5 and the like are provided.

  The heating cooker A is supplied with AC from a commercial power source. In the cooking device A, there are those that are driven by alternating current such as the radio wave generator 3, the heater Ht, and the steam generator Vp, and those that are operated by direct current such as the input unit It, the door open / close detection switch Os, and the control circuit 5. include. The switching power supply circuit 1 is a circuit that converts alternating current from a commercial power supply into direct current and supplies the direct current to a device driven by direct current. The switching power supply circuit 1 outputs a voltage (for example, 5V) for generating a control signal and a driving voltage (for example, 12V) of a DC-driven device.

  The switching power supply circuit 1 is a circuit that converts an alternating current supplied from a commercial power supply into a direct current by switching a switching element provided therein. The switching power supply circuit 1 has a conventionally well-known circuit configuration, and a detailed description of the circuit configuration is omitted.

  The radio wave generator 3 includes a microwave generator called a magnetron (not shown). The magnetron generates microwaves when high-frequency and high-voltage power is supplied. The radio wave generator 3 also includes an antenna (not shown) for irradiating microwaves into the cooking chamber of the heating cooker A. The radio wave generator 3 is used for a microwave function that heats an article to be heated housed in the heating chamber Hr using microwaves.

  The heater Ht is a device that generates infrared rays when energized. The heater Ht is used for an oven function for heating the article to be heated by irradiating the article to be heated contained in the heating chamber Hr with infrared rays. Furthermore, the steam generator Vp is a device that generates water by heating water with a heater. The steam from the steam generator Vp is filled in the heating chamber Hr and used for a steam heating function for heating the article to be heated. The radio wave generator 3, the heater Ht, and the steam generator Vp may be referred to as a heating device. In the heating cooker A, the heating device (the radio wave generator 3 in the following description) operates. The time (when cooking is performed) is the load operation, and the time when the heating device is stopped is the standby time.

  The commercial power supply supplies alternating current (for example, a voltage of about 100 V to 240 V (single-phase three-wire), frequency 50 Hz or 60 Hz in Japan). As described above, since the radio wave generator 3 is driven at high frequency and high pressure, it cannot be driven as it is from the commercial power source. Therefore, the high-voltage power circuit 2 converts alternating current from a commercial power source into high-frequency and high-voltage power necessary for generating a microwave with the radio wave generator 3. The high voltage power supply circuit 2 may include an inverter circuit. Since the high-voltage power supply circuit 2 is also a well-known circuit, a detailed description of the circuit configuration is omitted.

  The control circuit 5 is an electronic circuit for controlling devices provided in the cooking device A such as the radio wave generator 3, the heater Ht, and the steam generator Vp. The control circuit 5 includes an arithmetic processing unit such as a microcomputer (not shown), and controls the above-described devices based on signals from the input unit It, the door open / close detection switch Os, the watch Wt, and the like. .

  The input unit It is a user interface for accepting input by the user, and includes a switch such as a button. The input unit It can select which of the microwave function, the oven function, and the steam heating function is used, the selection of a cooking procedure provided in advance, the heating time in each function, and the setting of the target temperature. . Such setting information is transmitted to the control circuit 5. The display unit Mt includes a display device such as a liquid crystal display device, and displays the current state of the cooking device (the selected heating function, temperature, time, etc.).

  The door open / close detection switch Os is a switch for detecting whether the door Dr is open or closed. Currently, many cooking devices are configured to turn on the cooking device A by opening and closing the door Dr. And when the door Dr is an open state or a closed state continuously for a fixed time, and there is no operation input to the input part It during that time, it becomes the structure by which the power supply of a heating cooker is turned off. Therefore, the control circuit 5 detects the opening / closing of the door by supplying power to the door opening / closing detection switch Os at regular intervals and detecting whether the switch is on or off.

  Further, there is a case where an operation is input to the input unit It while the power is continuously turned on with the door Dr closed. Also in this case, in order to ensure that the operation input at the input unit It is performed, the control circuit 5 supplies power to the input unit It at regular intervals, like the door opening / closing detection switch Os. A signal from the input unit It is detected.

  As a period during which the control circuit 5 scans the door opening / closing detection switch Os, it is preferable that the opening / closing operation of the door by the user can be detected without delay. And since the alternating current from a commercial power supply is an alternating current of the frequency with little variation (it does not exist at all), the control circuit 5 determines the scanning timing using the alternating current frequency from a commercial current. Further, the control circuit 5 outputs a clock pulse as a reference of operation to the timepiece Wt, and this clock pulse is also determined based on the frequency of alternating current from the commercial current.

  In addition, when the start-up timing of the radio wave generator 3 overlaps with a certain timing of AC from the commercial power supply (for example, timing when the AC voltage from the AC power supply rises), the radio wave generator 3 instantaneously increases from several tens to one hundred times of normal operation. Exceeding current (rush current) may flow. Therefore, the control circuit 5 needs to drive the radio wave generator 3 at a timing at which no inrush current is generated based on the AC power supply phase and frequency from the commercial power supply.

  Therefore, in the cooking device A, the control circuit 5 includes a power supply synchronization circuit 4 that transmits a control circuit 5 that acquires a synchronization signal synchronized with an alternating current from a commercial power supply. The control circuit 5 detects the phase and frequency of alternating current from the commercial power source from the synchronization signal in order to drive the radio wave generator 3 safely and stably during load operation (to suppress the inrush current described above). ing. Further, the control circuit 5 generates a pulse serving as an operation reference of the timepiece Wt based on the frequency of the commercial power source acquired from the synchronization signal.

  During a load operation in which the radio wave generator 3 is driven, the control circuit 5 determines the drive timing of the radio wave generator 3 based on the power phase and power frequency of the commercial power source in order to suppress the inrush current. For this reason, at the time of load operation, the synchronization signal is required to have at least an accuracy capable of detecting the power supply phase and the power supply frequency of the commercial power supply.

  On the other hand, during standby, the control circuit 5 operates the door open / close detection switch Os, the input unit It, the clock Wt, and the like based on the synchronization signal, but the synchronization signal is accurate enough to detect the frequency of the commercial power supply. Is enough. That is, in the heating cooker A, the synchronization signal acquired by the control circuit 5 is required to have high accuracy capable of detecting the power supply phase and the power supply frequency during load operation, and may be accurate enough to detect the power supply frequency during standby. .

  Next, details of the power supply synchronization circuit of the heating cooker having the above configuration will be described with reference to the drawings. FIG. 3 is a diagram showing an electrical connection of an example of the heating cooker shown in FIG. In addition, although only the radio wave generator 3 is shown as a heating device in the heating cooker A shown in FIG. 3, actually, similarly to FIG. 2, a heater Ht and a steam generator Vp are also provided.

  As shown in FIG. 3, the cooking device A according to the present invention includes resistors Rc, Rs, in addition to the switching power supply circuit 1, the high voltage power supply circuit 2, the radio wave generator 3, the power supply synchronization circuit 4, and the control circuit 5 described above. A first terminal T1 and a second terminal T2 are provided. And in the heating cooker A, it is connected to the commercial power source (alternating current power source) via the 1st terminal T1 and the 2nd terminal T2, and alternating current is supplied from the commercial power source. In addition, as shown in FIG. 3, the AC from the commercial power supplied via the first terminal T <b> 1 and the second terminal T <b> 2 is also supplied to the high-voltage power circuit 2. That is, it can be said that the power supply synchronization circuit 4 is synchronized with the alternating current supplied from the commercial power supply and is synchronized with the alternating current supplied to the high voltage power supply circuit 2.

  The switching power supply circuit 1 includes a first terminal 11 that outputs a 5V voltage for a control signal and a second terminal 12 that outputs a 12V voltage for driving an electronic device.

  The power supply synchronization circuit 4 includes a first resistor Rv1, a second resistor Rv2, a photocoupler 6, a relay 7, a rectifying diode 8, and a switching element Q1. As shown in FIG. 3, a first circuit C1 to which an alternating current from a commercial power supply is applied and a second circuit C2 to which a direct current from the switching power supply circuit 1 is applied are provided. The first circuit C1 and the second circuit C2 are insulated by a photocoupler 6 and a relay 7.

  The first circuit C1 includes a first resistor Rv1, a second resistor Rv2, a photocoupler 6, a relay 7, and a rectifying diode 8. As shown in FIG. 1, one terminal of the first resistor Rv1 is connected to the first terminal T1, and the other terminal is connected to an anode of a light emitting diode 61 (described later) included in the photocoupler 6.

  The cathode of the light emitting diode 61 is connected to the anode of the rectifying diode 8, and the cathode of the rectifying diode 8 is connected to the second terminal T2. The light emitting diode 61 and the rectifying diode 8 have a forward direction from the first terminal T1 side to the second terminal T2 side, and current flows only in this direction. The rectifying diode 8 is a diode that does not damage the light emitting diode 61 even when a reverse bias is applied by an alternating current supplied from a commercial power source.

  The first circuit C1 includes a bypass circuit provided with a second resistor Rv2 so as to be in parallel with the first resistor Rv1. In this bypass circuit, the second resistor Rv2 and the contact 71 of the relay 7 are arranged in series. That is, in the bypass circuit, one of the second resistors Rv2 is connected between the first terminal T1 and the first resistor Rv1, and the terminal on the opposite side of the contact 71 from the second resistor Rv2 is connected to the first resistor Rv1. It is connected between the light emitting diodes 61.

  When comparing the first resistance Rv1 and the second resistance Rv2, the first resistance Rv1 is larger than the second resistance Rv2. The resistance values of the first resistor Rv1 and the second resistor Rv2 are set such that most of the current flowing through the first circuit C1 flows to the second resistor Rv2 side when the contact 71 is closed. Since the first resistor Rv1 has a larger resistance value than the second resistor Rv2, the current flowing through the second resistor Rv2 is larger than the current flowing through the first resistor Rv1.

  That is, a small current flows through the light emitting diode 61 when the contact 71 is open, and a larger current flows through the light emitting diode 61 than when the contact is open when the contact 71 is closed.

  On the other hand, the second circuit C2 includes a phototransistor 62 of the photocoupler 6, a switching element Q1, and a coil 72 of the relay 7. Here, the photocoupler 6 will be described. The photocoupler 6 is an element including a light emitting diode 61 and a phototransistor 62 that receives light from the light emitting diode 61. When the light emitting diode 61 emits light and the phototransistor 62 receives the light, the collector-emitter of the phototransistor 62 becomes conductive, and current flows from the collector of the phototransistor 62 to the emitter.

  In the second circuit C <b> 2, the collector of the phototransistor 62 is connected to the first terminal 11, and the emitter is connected to the control circuit 5. A grounded resistor Rs is connected to the wiring between the phototransistor 62 and the control circuit 5. This resistor Rs is a resistor for drawing a current from the first terminal 11 of the switching power supply circuit 1 when the collector-emitter of the phototransistor 62 becomes conductive. That is, since the resistor Rs is provided, a current flows between the collector and the emitter of the phototransistor 62. In addition, since the resistor Rs is provided, a voltage (an input voltage, which will be described later) having the same waveform as the current flowing through the phototransistor 62 is input to the control circuit 5.

  The photocoupler 6 will be further described. The light emitting diode 61 is an element whose amount of light varies depending on the magnitude of current, and the amount of emitted light increases as the current increases. On the other hand, in the phototransistor 62, the current flowing from the collector to the emitter is proportional to the amount of received light until the amount of received light reaches a constant value, and when the amount exceeds a certain value, the current value becomes constant. As shown in FIG. 3, since the voltage applied to the collector of the phototransistor 62 is constant, the current flowing between the collector and the emitter of the phototransistor 62 is proportional to the magnitude of the current flowing through the light emitting diode 61.

  In order to cause a constant current to flow between the collector and the emitter of the photodiode 62, the current (threshold value Is) that flows through the light emitting diode 61 is determined by the configuration of the photocoupler 6, and the first circuit C 1 of the power supply synchronization circuit 4. It is a constant value regardless of the magnitude of the current flowing through the. That is, when the current flowing through the light emitting diode 61 is equal to or greater than the threshold Is, the current flowing between the collector and emitter of the phototransistor 62 is constant.

  That is, in the power supply synchronization circuit 4, the current flowing between the collector and the emitter of the phototransistor 62 increases until the current flowing through the light emitting diode 61 reaches the threshold value Is. The current flowing between the collector and the emitter of the phototransistor 62 maintains a constant value until the current flowing through the light emitting diode 61 exceeds the threshold Is and reaches a peak and then reaches the threshold Is again. When the current flowing through the light emitting diode 61 becomes smaller than the threshold value Is, the current flowing between the collector and the emitter of the phototransistor 62 also decreases.

  As described above, the current flowing between the collector and the emitter of the phototransistor 62 is extracted by the resistor Rs, converted into a voltage by the resistor Rs, and input to the control circuit 5. The control circuit 5 detects the synchronization signal based on this input voltage. More specifically, the control circuit 5 includes a circuit that compares the input voltage with another comparison voltage. When the input voltage is higher than the comparison voltage, the synchronization signal is at the Hi level, and when the input voltage is lower, the synchronization signal is assumed to be at the Lo level. Is detected.

  In the second circuit C2, the collector of the switching element Q1 (here, npn-connected bipolar transistor) is connected to the second terminal 12 of the switching power supply circuit 1 and the emitter is connected to one terminal of the solenoid 72 of the relay 7. ing. A grounded resistor Rc is connected to the other terminal of the solenoid 72. A control signal (current signal) from the control circuit 5 is input to the base of the switching element Q1.

  The resistor Rc is a resistor for drawing current from the second terminal 12 of the switching power supply circuit 1 when the collector-emitter of the switching element Q1 is in a conductive state (when a Hi level signal is input to the base). . Further, the resistor Rc is also a resistor for preventing an overcurrent from flowing through the switching element Q1 and the solenoid 72. Note that the contact 71 of the relay 7 is normally open, and the contact 71 is closed when a current is supplied to the solenoid 72.

  In the switching element Q1, when a Hi level control signal is input from the control circuit 5 to the base, the collector-emitter becomes conductive, and a current flows from the collector to the emitter. This current is supplied to the solenoid 72 of the relay 7 and the contact 71 is closed. That is, the contact 71 of the relay 7 is opened and closed by the control circuit 5.

  Next, the operation of the cooking device A and the synchronization signal will be described with reference to the drawings. FIG. 4 is a timing chart showing the commercial power supply, the synchronization signal, and the like during standby, and FIG. 5 is a timing chart showing the commercial power supply, the synchronization signal, etc. during load operation.

  As described above, in the heating cooker A, the control circuit 5 detects the synchronization signal synchronized with the AC from the commercial power supply not only during the load operation but also during the standby. The synchronization signal is required to have synchronization accuracy capable of detecting the power supply phase and the power supply frequency during load operation, but may be any synchronization accuracy sufficient to detect the power supply frequency during standby. Therefore, FIG. 4 shows the voltage of the commercial power supply, the voltage after half-wave rectification, the control signal during standby and load operation, the current flowing through the first circuit C1, the input voltage input to the control circuit 5, and the synchronization signal. ing.

  AC (voltage 100V to 240V) having an accurate cycle (50 Hz or 60 Hz in Japan) flows through the commercial power supply (here, AC is 60 Hz and 200 V). In the power supply synchronizing circuit 4, an alternating current having such an accurate period is applied between the first terminal T1 and the second terminal T2. Here, when the voltage at the first terminal T1 is higher than the voltage at the second terminal T2, in other words, when the voltage is such that current flows in the forward direction of the light emitting diode 61 and the rectifying diode 8, it is positive. The alternating current has a sine wave shape as shown in FIG.

  When such an alternating current is applied to the first terminal T1 and the second terminal T2, the first circuit C1 is provided with the rectifying diode 8 and is thus half-wave rectified. That is, as shown in FIG. 4, only the forward voltage of the rectifying diode 8 is applied to the first circuit C1 in a half cycle in which the alternating current from the commercial power supply is positive, that is, the remaining half cycle (reverse voltage). The voltage is “0” during the period during which is applied. When such a half-wave rectified voltage is applied, a current flows through the first circuit C1 (that is, the light emitting diode 61) only while the alternating current from the commercial power supply is positive.

  The current flowing through the light emitting diode 61 repeats increasing / decreasing in accordance with the waveform of the half-wave rectified voltage. At this time, if the resistance value is large, the current value becomes small, and the fluctuation (increase / decrease) in current becomes moderate. When the fluctuation of the current is moderate, the period from the start of the current flow to the threshold Is and the period from the threshold Is to the no current flow become longer. Since an input voltage proportional to such a current is input to the control circuit 5, in the synchronization signal detected by the control circuit 5, the Hi level period is shorter and deviated from the AC positive period from the commercial power supply. (Ie, the synchronization accuracy is low). On the other hand, when the resistance is small, that is, when the current fluctuates suddenly, the period of Hi level of the synchronization signal approaches the period of positive AC from the commercial power supply (high synchronization accuracy).

  For this reason, in the power supply synchronization circuit 4, the contact 71 of the relay 7 is opened during standby when the synchronization signal does not require high accuracy, and a voltage is applied only to the first resistor Rv1, and high accuracy is required for the synchronization signal. During the load operation, the contact 71 of the relay 7 is closed, and a voltage is applied to the combined resistance (the resistance value is significantly lower than the first resistance Rv1) in which the first resistance Rv1 and the second resistance Rv2 are connected in parallel. I am doing so.

  Next, the current flowing through the first circuit C1 during load operation and standby will be described. As described above, a signal that can detect the frequency of the commercial power supply (a signal having a lower synchronization accuracy than that during load operation) is sufficient as the synchronization signal during standby.

  Therefore, during standby, the control circuit 5 sets the control signal input to the base of the switching element Q1 to Lo and opens the contact 71. At this time, in the first circuit C1, a voltage is applied to the first resistor Rv1. The current I1 flowing through the light emitting diode 61 has a waveform that peaks at the same timing as the rectified voltage, as shown in FIG. The first resistor Rv1 has a larger resistance value than the second resistor Rv1, and the current I1 becomes smaller.

  During standby, current flows through the first resistor Rv1 having a large resistance value in the first circuit C1, so that the current I1 flowing through the light emitting diode 61 has a low maximum value, and the current value gradually increases or decreases. For this reason, the time from the rise of the current I1 to the threshold Is is long, and the standby current I1 slowly increases and decreases (see FIG. 4).

  From this, the current flowing between the collector and the emitter of the phototransistor 62 gradually increases until the current I1 reaches the threshold value Is from the rise, and a constant current value continues to flow while the threshold value Is is exceeded. And when it becomes smaller than the threshold Is, it gradually decreases until the fall. Note that the current flowing between the collector and the emitter of the phototransistor 62 is determined by the voltage (here, 5 V) shared from the first terminal 11 of the switching power supply circuit 1 and the resistance value of the resistor Rs.

  As described above, the current flowing between the collector and the emitter of the phototransistor 62 is drawn out to the resistor RS, and the input voltage having the same waveform as the current flowing between the collector and the emitter is input to the control circuit 5. (See FIG. 4). The input voltage input to the control circuit 5 varies between 0V and 5V. That is, the current I1 flowing through the first circuit C1 reaches 5 V until it reaches the threshold Is and becomes smaller than the threshold Is.

  Then, the control circuit 5 compares the input voltage with the comparison voltage Vs. Then, the control circuit 5 detects the synchronization signal at the Lo level when the input voltage is lower than the comparison voltage, and the synchronization signal at the Hi level when the input voltage is higher (see FIG. 4). As shown in FIG. 4, the standby synchronization signal has a large difference between the positive period of AC from the commercial power supply and the Hi level.

  Even with such a synchronization signal, the control circuit 5 can accurately detect the frequency of the commercial power supply. The door opening / closing detection switch Os, the input unit It, the clock Wt, and the like that are operating during standby need only be able to detect only the frequency, and even such a synchronization signal can be used sufficiently. In addition, since the voltage I1 flowing through the light emitting diode 61 (that is, the first circuit C1) when the commercial power is applied to the first resistor R1 is smaller than the current I2 during load operation described later, the first during standby The electric power consumed by the circuit C1 can be suppressed as compared with the load operation. Note that the threshold Is is determined by the performance of the light emitting diode 61 and the phototransistor 62. The first resistor Rv1 of the first circuit C1 is determined so that the maximum value of the current when the commercial voltage is applied exceeds the threshold Is.

  On the other hand, at the time of load operation, the control circuit 5 requires a synchronization signal that is synchronized accurately to such an extent that the power supply phase and power supply frequency of the commercial power supply can be detected. As shown in FIG. 5, when the current flowing through the light emitting diode 61 is increased, the time from the rising of the current to the threshold Is is shortened. Therefore, the control circuit 5 inputs a Hi level control signal to the base of the switching element Q1. Thereby, the current from the switching power supply circuit 1 flows between the collector and the emitter of the switching element Q1. Since the current flows to the solenoid 72, the contact ¥ 71 is closed. As a result, the half-wave rectified voltage causes a current to flow through the combined resistance of the first resistor Rv1 and the second resistor Rv2 connected in parallel. The combined resistance is smaller than the resistance value of the first resistor Rv1 because the resistance value of the second resistor Rv2 is larger than the first resistor Rv1 (differing in digit). Therefore, the current I2 flowing through the light emitting diode 61 is larger than that during standby (see FIG. 5).

  Since the current I2 flowing through the light emitting diode 61 during the load operation increases rapidly, the current I2 becomes larger than the threshold Is immediately after the rise. For this reason, the current flowing between the collector and the emitter of the phototransistor 62 rises at substantially the same timing as the rise of the half-wave rectified voltage. An input voltage having the same waveform as the current waveform is input to the control circuit 5.

  The control circuit 5 detects the synchronization signal by comparing the input voltage with the comparison voltage Vs. That is, if the input voltage is lower than the comparison voltage Vs, the control circuit 5 determines the Lo level, and if the input voltage is higher, the control circuit 5 determines the Hi level and detects the synchronization signal (see FIG. 5). As shown in FIG. 5, the synchronization signal during the load operation has almost no deviation between the positive period of AC from the commercial power supply and the Hi level period.

  That is, as shown in FIG. 5, the synchronization signal during the load operation reaches the Hi level at almost the same timing as the start of the AC cycle supplied from the commercial power supply, and goes to the Lo level at almost the same timing as the polarity is switched. Becomes a square wave. By using this synchronization signal, the control circuit 5 can accurately detect the AC power phase and power frequency of the AC from the commercial power source. Since the control circuit 5 controls the radio wave generator 3 based on the information on the power supply phase and the power supply frequency, it is possible to suppress the occurrence of an inrush current or the like.

  By providing the power supply synchronization circuit 4 having such a configuration, it is possible to detect a synchronization signal synchronized with an alternating current from a commercial power supply during load operation with accuracy necessary for controlling a device that operates during load operation, and during standby The accuracy of the synchronization signal can be reduced to a system necessary for controlling a device that operates during standby, and power consumption can be reduced. Thereby, the safety and stability of the operation during the load operation can be ensured, and the power consumption during standby can be reduced.

  In the above configuration, each of the first resistor Rv1 and the second resistor Rv2 of the power supply synchronization circuit 4 may be configured by one resistor (element), or a configuration including a plurality of resistors (elements). It is good. Further, since the current I1 flowing through the first circuit C1 during standby is determined by the resistance value of the first resistor Rv1, it is better to make it as large as possible. However, since the synchronization signal does not become Hi level unless the current I1 becomes equal to or higher than the threshold value Is, the resistance value of the first resistor Rv1 should be as large as possible within the range where the current I1 is larger than the threshold value Is. preferable.

  The second resistor Rv2 is preferably as small as possible because the current flowing through the first circuit C1 during load operation is determined by the combined resistance (parallel) with the first resistor Rv1. However, the upper limit of the current is determined for the light emitting diode 61 and / or the rectifying diode 8 and is damaged when a current exceeding the upper limit flows. Therefore, the resistance value of the second resistor Rv2 is as large as possible in a range where the current I2 flowing through the combined resistor of the first resistor Rv1 and the second resistor Rv2 is smaller than the upper limit of the current of the light emitting diode 61 and the rectifying diode 8. It is preferable to use one.

  In the above configuration, a photocoupler is employed as an element that transmits a signal between the first circuit C1 and the second circuit C2 and insulates each circuit. While maintaining the above, it is possible to widely employ elements having a structure capable of transmitting signals.

  In each of the above-described embodiments, a bipolar transistor is used as an example of the switching element Q1, but the present invention is not limited to this, and switching elements such as FETs, IGBTs, and thyristors can also be used. An element that can supply current to the solenoid 72 of the relay 7 with a control signal from the control circuit 5 can be widely used. Moreover, although the relay 7 is used as a member which changes the resistance of the 1st circuit C1 in the control circuit 5, it is not limited to this, You may utilize elements, such as SSR. A control signal from the control circuit 5 that can control on / off of the circuit can be widely used.

  In the above configuration, the first circuit C1 includes the first resistor Rv1 and the second resistor Rv2 connected in parallel, and the relay 7 combines the first resistor Rv1 or the combined resistance of the first resistor Rv1 and the second resistor Rv2. However, the present invention is not limited to this, and a variable resistor is attached to the first circuit C1, and an element (switch) for switching the resistance value of the variable resistor is used instead of the relay 7. The structure provided may be sufficient.

  Moreover, in the said embodiment, although switching of the precision of a synchronizing signal is performed by whether the radio wave generator 3 is driven, it is not limited to this, A heater Ht, the steam generator Vp, or other Even in the heating apparatus, when a highly accurate synchronization signal is required, a highly accurate synchronization signal may be acquired.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention.

  This power supply synchronization circuit is not only a heating cooker but also requires a high-accuracy synchronization signal during load operation, and a device that only needs to detect a synchronization signal that can detect the power supply frequency during standby, for example, a rice cooker, a television It can be employed in a receiver, a disk device or the like. Furthermore, it can be widely used for home appliances using a remote controller.

A Heating cooker 1 Switching power supply circuit 2 High voltage power supply circuit 3 Radio wave generator 4 Power supply synchronization circuit 5 Control circuit 6 Photocoupler 61 Light emitting diode 62 Phototransistor 7 Relay 71 Contact 72 Solenoid 8 Rectifying light emitting diode Rv1 First resistor Rv2 Second Resistor Rc, Rs Resistor (for current drawing)
Vp Steam generator Ht Heater It Input part Mt Display part Os Door open / close detection switch Wt Clock

Claims (6)

An AC power from a power source is connected by connecting a resistance portion having a variable resistance value, an input portion of an insulating signal transmission means for transmitting a current flowing through the circuit to another circuit as a signal, and a protection diode for the input portion. A first circuit to which is applied;
A second circuit for connecting the output portion of the insulated signal transmission means and the control means to which a direct current is applied;
The first circuit and the second circuit are insulated from each other, and a resistance adjusting unit that adjusts a resistance value of the resistance unit based on a control signal from the control unit is provided.
The power supply synchronization circuit, wherein the control means detects a synchronization signal synchronized with an alternating current from the power supply based on an output from the insulated signal transmission means. The insulated signal transmission means is a photocoupler,
The power supply synchronization circuit according to claim 1, wherein the input unit is a light emitting diode, and the output unit is a phototransistor. The resistance portion includes a first resistance portion and a second resistance portion having a resistance value smaller than that of the first resistance portion and in parallel with the first resistance portion,
3. The power supply synchronization circuit according to claim 1, wherein the resistance adjusting unit includes an insulation switch that switches conduction / non-conduction of the second resistance unit based on a control signal from the control unit. The isolation switch includes a relay;
The relay is arranged such that a contact is in series with the second resistance portion and parallel to the first resistance portion, and a solenoid for operating the contact in a non-contact manner is included in the second circuit. Item 4. The power supply synchronization circuit according to Item 3. A switching element is connected to the solenoid,
5. The power supply synchronization circuit according to claim 4, wherein the switching element controls on / off of a current flowing through the solenoid based on a control signal from the control means. A radio wave generator that generates high-frequency and high-voltage power and generates microwaves;
A high-voltage power supply circuit for supplying high-frequency high-voltage power to the radio wave generator;
A heating cooker including the power supply synchronization circuit according to any one of claims 1 to 5,
The first circuit is connected in parallel with the high-voltage power supply circuit;
The control means is configured such that the second resistor unit is in a load operation when the radio wave generator is operating so that the second resistor unit is in a non-conductive state when the radio wave generator is stopped. The heating cooker characterized by controlling the said insulation switch so that it may be in a conduction | electrical_connection state.

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