JP5413021B2 - Cooker - Google Patents

Description

  The present invention relates to a cooking device used in general homes, restaurants and offices.

  Conventionally, for heater control such as a resistance load of a cooking appliance, heating is generally performed by controlling conduction with an AC power source and a relay having a contact with the heater. At this time, when using a system in which the relay contact is mechanically closed by a magnetic force of an iron core or the like magnetized by a DC magnetic flux generated by passing a DC current through the exciting coil, the relay contact is driven from the microcomputer output port. There is disclosed a configuration in which a transistor (drive circuit) that passes a current through an exciting coil is driven by a DC to close a relay contact depending on the output logical value, that is, the presence or absence of a DC voltage.

Japanese Patent Laid-Open No. 11-297467

  However, in the conventional configuration, when the control circuit is mounted on the printed wiring board and is electrically connected by the wiring of the printed wiring board, in the unlikely event that the drive signal system is located near the source side, If the printed wiring path from the computer output port to the transistor in the drive circuit malfunctions, breaks down, or adheres to foreign matter, causing a DC voltage to be continuously output, the control circuit is normal. There was a problem that the relay contact kept closing regardless of the normal operation.

  The present invention solves the above-described conventional problems, and uses two relay contacts provided on both ends of each of the resistance loads for connection between the AC power source and the resistance load. When the resistance load is not energized, the AC power source is connected to the resistance load. By disconnecting both ends of the relay, even if one of the relays or the drive circuit breaks down and the contact continues to close, the other relay releases the connection between the resistive load and the AC power A state in which a resistive load is continuously energized due to runaway or latch-up of the microcomputer when the microcomputer is used to drive a relay and energize a resistive load while preventing unintended continuous energization of the load Even if it becomes, it aims at providing a heating cooker with higher safety | security by making one relay surely non-conducting.

In order to solve the conventional problem, a cooking device of the present invention includes a heating unit and a control unit that has a microcomputer and controls the operation of the heating unit, and the heating unit includes a resistance load and Each of the resistive loads is connected to both ends of the first and second relays having contacts, and the series body and the AC power source are connected in parallel, and the control unit includes the AC power source. to obtain operating power from the first relay and has a first drive means and second drive means for each driving the second relay, when energizing the resistive load of the first relay The second relay is made conductive / non-conductive after being driven to turn on and off, thereby changing the heating output of the resistance load, and the first drive means is a predetermined output outputted by the microcomputer. Of period and predetermined amplitude The first relay is driven based on the voltage stored in the charging circuit consisting of the second capacitor after the DC voltage is removed through the differential circuit consisting of the resistor and the first capacitor. and said second drive means, the drive signal transfer, to drive the second relay with only a DC signal, a voltage which has been stored in said second capacitor to stop application of the pulse voltage The first load is discharged to stop the driving of the first relay, and the resistance load is made non-conductive .

Thus, the connection between the AC power source and the resistive load is configured by using two relay contacts provided at both ends of the resistive load, and by disconnecting the both ends of the resistive load from the AC power source when the resistive load is not energized. In use, the resistive load can be completely disconnected from the AC power source, and even if one of the relays or the drive circuit breaks down and the contact continues to close, the other relay connects the resistive load to the AC power source. When the resistance load is released to prevent unintentional continuous energization, or when the microcomputer is used to drive the relay and the resistance load is energized, the microcomputer runs away or latches up to the second drive means. The input becomes the second relay conduction logic, and the input to the first driving means becomes a DC signal or a pulse signal greatly deviating from a predetermined period, and the first relay It can be reliably rendered non-conductive. In addition, a predetermined cycle and
Then, the application of the pulse voltage with a predetermined amplitude is stopped, the electric charge stored in the charging circuit is discharged, the conduction of the final stage transistor or the like is interrupted, and the excitation of the exciting coil is stopped, thereby The connection end can be opened.

The heating cooker of the present invention connects an AC power source and a resistive load with two excitation-type relays having contact points as connection ends, and a driving method for one of the relays uses a periodic pulse voltage such as a rectangular wave as a differentiation circuit. Since the drive is based on the voltage obtained by charging the voltage from which the DC component has been removed in the circuit, malfunction or failure occurs in the printed wiring path of the drive signal system including the microcomputer in the stage before the differentiation circuit. Or, when a problem such as adhesion of foreign matter occurs and the DC voltage continues to be output, the drive signal is not transmitted to the final stage of the first drive means, and the connection end of the first relay Can be disconnected to disconnect the AC power supply and the resistive load. In addition, by stopping the application of a pulse voltage with a predetermined period and a predetermined amplitude, the charge stored in the charging circuit is discharged, the conduction of the transistor at the final stage is cut off, and the excitation of the excitation coil is stopped, The connection end of the first relay can be opened.

The block diagram of the heating cooker in Embodiment 1 of this invention FIG. 6 is an operation waveform (steady state) diagram of each part of the driving unit according to the first embodiment of the present invention. FIG. 6 is an operation waveform (at the start of operation) of each part of the driving unit according to Embodiment 1 of the present invention.

The first invention includes a heating unit, and a control unit for controlling the operation of the heating unit has a microcomputer, the heating unit is connected respectively with a resistive load across said resistive load, the contacts consists of a series of a first relay and a second relay provided with, said series body and an AC power source connected in parallel, the control unit obtains the operating power from the AC power source, the first relay and the second has a first driving means and second driving means each for driving the relay, when energizing the resistive load the second after a conductive state by driving the first relay The heating output of the resistive load is varied by turning on and off the relay of the relay, and the first driving means applies a pulse voltage having a predetermined period and a predetermined amplitude output from the microcomputer. Resistor and first condenser After through the differentiating circuit to remove DC components consisting of the first relay is driven based on the voltage stored in the charging circuit of a second capacitor, said second drive means, the drive signal For transmission, the second relay is driven using a DC signal, and the application of the pulse voltage is stopped and the voltage stored in the second capacitor is discharged to stop the driving of the first relay. The resistance load is configured to be non-conductive . As a result, the control unit obtains an operating power source by being connected to the AC power source, so that the first and second relays are driven according to the drive command of the control unit to control energization of the resistive load and heat the object to be heated. be able to. For driving the first relay, a pulse voltage having a predetermined period and a predetermined amplitude is applied by the first driving means, and a direct current component is removed through a differential circuit composed of a resistor and a first capacitor. Then, based on the voltage stored in the charging circuit composed of the second capacitor, the transistor provided in the final stage is made conductive, so that the current flows through the exciting coil of the first relay. Close the connection end of the relay, stop applying the pulse voltage with a predetermined period and amplitude, discharge the charge stored in the charging circuit, cut off the conduction of the final stage transistor, etc., and excite the excitation coil By stopping, the connection end of the first relay can be opened. In driving the second relay, unlike the driving of the first relay, the transistor provided in the final stage is made conductive by the DC driving signal by the second driving means, so that the second relay is driven. By passing a current through the exciting coil, the connection end of the second relay is closed, the application of the DC drive signal is stopped, the conduction of the transistor in the final stage is cut off, and the excitation of the exciting coil is stopped. The connection end of the second relay can be opened. Furthermore, when the control circuit is mounted on the printed wiring board and electrically connected by the wiring of the printed wiring board, the printed wiring in the previous stage should be different from the differential circuit of the drive signal system of the first relay. When a malfunction such as malfunction or failure in the path, or adhesion of foreign matter occurs and the DC voltage continues to be output, the DC signal is not transmitted by the differentiation circuit. Is stopped, and the connection end of the first relay can be kept open. In addition, when the drive circuit is operated by programming such as a microcomputer, the frequency and duty ratio of the pulses output to the drive circuit are reduced below a specified level due to programming defects or microcomputer runaway. Even in this case, the voltage of the charging circuit can be prevented from reaching the driving voltage of the final stage transistor, so that the driving of the final stage transistor and the like is stopped, and the connection end of the first relay is maintained in the open state. be able to.

2nd invention is provided with the heating part and the control part which controls the operation | movement of the said heating part, The said heating part is connected to the both ends of a resistive load and the said resistive load, respectively, The 1st provided with the contact It consists of a series body of a relay and a second relay, and the series body and an AC power source are connected in parallel, and the control unit obtains an operating power source from the AC power source, and the first relay and the second relay A first driving means and a second driving means for driving the relays, respectively, and when energizing the resistance load, the first relay is driven to be in a conductive state and then the second relay is turned on; By making the heating load non-conductive, the heating output of the resistance load is varied, and the first driving means applies a pulse voltage having a predetermined cycle and a predetermined amplitude in which the pulse waveform is rectangular, and the resistance and the first The DC component is removed through a differentiation circuit consisting of capacitors. After that, the first relay is driven based on the voltage stored in the charging circuit composed of the second capacitor, and the second driving means uses the DC signal to transmit the driving signal to the second relay. The control unit includes a monitoring unit that drives the relay and monitors the amplitude or cycle of the pulse voltage input to the first driving unit, and the control unit detects the pulse voltage detected by the monitoring unit. When the amplitude or cycle of the second driving means deviates from a predetermined range, the second driving means opens the second relay and stops energizing the resistance load . As a result, the square wave is a waveform that a digital IC such as a microcomputer can output relatively easily by turning on and off the transistor of the output terminal by internal programming, so the number of components of the first driving means increases. The differential circuit of the first driving means can be suppressed even if a malfunction occurs in which the output terminal of the microcomputer is fixed to the DC voltage output state due to destruction of the output terminal of the microcomputer or runaway of the program. However, since the DC voltage component is removed and the charge circuit is not charged, the driving of the first relay is stopped, and the connection between the resistance load of the heating unit and the AC power supply can be disconnected. In addition, when the pulse voltage input to the first driving means is generated by using programming of the microcomputer or the like, the microcomputer monitors the amplitude or period of the pulse voltage output by itself. The pulse voltage output terminal is broken or a failure occurs in the pulse voltage generation program, so that it is possible to detect an unintentional pulse voltage application to the first driving means or an abnormality in the output pulse voltage, If it is determined that there is an abnormality, the output of the DC drive signal to the second drive means is stopped, the second relay is made non-conductive, and the AC power source and the resistive load are not affected regardless of the state of the first relay. The conduction can be cut off.

A third invention is, in particular, the first or second aspect of the invention, placed on the printed circuit board part of the control unit comprising at least the first relay the first driving means, said printed circuit board It forms an electrical connection of the components in the printing wires and the signal leads than said stage subsequent to the differential circuit of the first driving means, the former-stage electrical connection path from said differentiating circuit the pulse voltage is applied Is configured to be long. As a result, even if there is a problem such as adhesion of foreign matter to the printed wiring of the printed wiring board or the electronic components mounted on the wiring board, the printed wiring path before the first relay drive signal system differentiation circuit Is longer than the printed wiring path at the subsequent stage, that is, the signal path transmitted by the pulse voltage is as long as possible with respect to the entire signal path related to the driving of the first relay, and the signal path transmitted by the DC voltage is By making it as short as possible, it is possible to reduce the risk that the first relay due to the adhering foreign matter becomes an unintended driving state, and it is possible to prevent the resistance load from being unintentionally energized.

  Embodiments of a heating cooker according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment of the present invention. FIG. 2 is an operation waveform diagram of each part at the time of steady operation of the first driving means in the embodiment of the present invention, the horizontal axis indicates the time passage, and FIG. 3 is the first driving means in the embodiment of the present invention. In the operation waveform diagram of each part at the start of the operation, the horizontal axis indicates the passage of time.

  In FIG. 1, an AC power source 1 is connected in parallel with a series body of a contact that is a connection end of a first relay 2, a contact that is a connection end of a resistance load 3 a and a second relay 4.

  The control unit 5 includes a control power supply circuit 10 that generates an operation voltage from the voltage of the AC power supply 1, and a microcomputer 11 that operates with the power supply voltage generated by the control power supply circuit 10, and drives the first relay 2 by excitation. The first driving means 12 and the second driving means 17 for driving the second relay 4 by excitation. The first driving means 12 converts a rectangular pulse having a predetermined period and a predetermined amplitude output from the microcomputer 11 into a voltage from which a DC component has been removed by a differentiation circuit 13 including a first capacitor 13a and a resistor 13b. Is held by the charging circuit 14 including the second capacitor 14a, and the first transistor 15 in the final stage is made conductive by this charging voltage, and a current is passed through the exciting coil 2a of the first relay 2 so that the first The relay 2 is driven. The second drive means 17 applies the binary DC voltage signal output from the microcomputer 11 to the second transistor 18 at the final stage, and turns on the second transistor 18 to activate the exciting coil 4a of the second relay 4. To drive the second relay 4. The monitoring means 19 monitors the input signal to the differentiation circuit 13 of the first driving means 12. In addition, the notification means 16 including a display element such as an LED or a buzzer performs notification and display according to the operation state of the control unit 5 to indicate the operation state of the device to the user.

  About the heating cooker comprised as mentioned above, the operation | movement and an effect | action are demonstrated.

  When the voltage of the AC power supply 1 is applied to the control unit 5, the control power supply circuit 10 starts to operate and a control power supply is generated. The microcomputer 11 starts operation by this control power supply. At this time, the resistance load 3a is disconnected from the AC power source 1 by the first relay 2 and the second relay 4, so that a fault such as leakage due to insulation deterioration of the resistance load 3a does not continue when the device is not used. ing.

  When the user starts a heating operation of the heating unit 3 so as to heat an object to be heated (not shown) by operating a switch or the like (not shown), the first driving unit 12 causes the first relay to operate. 3, a rectangular wave having a minimum amplitude of 5 V with a reference value of 0 V of the control power supply as a reference, a period of about 2 ms, and a duty ratio of about 50% as shown in FIG. Output from the terminal. Since the rectangular wave is a waveform that can be output relatively easily by turning on and off the transistor of the output terminal by programming inside the microcomputer 11, the increase in the number of components of the driving means is suppressed. When this rectangular wave is applied to the differentiating circuit 13, a voltage as shown in FIG. 3 (3c) in which the DC component of the rectangular wave is removed by the first capacitor 13a and the resistor 13b is generated in the resistor 13b. . This voltage is stored in the second capacitor 14a connected in the reversely blocked state by the diode, and increases as shown in FIG. 3 (3d). In this embodiment, when the voltage reaches about 2.5V, the first capacitor The transistor 15 is turned on to pass a current through the exciting coil 2a, and the contact that is the connection end of the first relay 2 is closed. Further, each part waveform in FIG. 3 becomes stable as shown in FIG. 2 when a sufficient time has elapsed. When the supply of the rectangular wave is stopped, the voltage stored in the capacitor 14a is discharged. When the voltage is less than about 2.5V, the transistor 15 is turned off, and the contact which is the connection end of the first relay 2 Becomes open.

In this embodiment, after the first relay 2 is closed, after a predetermined time, about 500 ms later (the delay time until the relay 2 contact is closed from the open state and the response delay of the first drive circuit 12). The operation proceeds to driving the second relay 4 at a time sufficiently larger than the sum of the time. This is because when the contact of the first relay 2 is closed, a zero current closing operation is performed to suppress the generation of an arc, thereby extending the life of the contact of the first relay 2 or reducing the contact capacity. The cost of the equipment is reduced by using an arc resistance generated only at the contact point of the second relay 4 so that arc resistance and contact capacity are enhanced only at the contact point of the second relay 4. The drive of the second relay 4 is a binary voltage of direct current from the other terminal of the microcomputer 11, which is 5V and 0V in the present embodiment, the drive is stopped at 0V, and the drive is driven at 5V. To do. When the microcomputer 11 outputs 5 V, the second transistor 18 in the final stage of the second driving means 17 is turned on, current flows through the second exciting coil 4a, and the contact that is the connection end of the second relay 4 is closed. Then, the resistance load 3a is energized. By controlling the opening and closing of the second relay 4, the heating power to the heated object is controlled by changing the energization amount of the resistance load 3 a.

  As described above, the first driving means 12 is configured to maintain the conduction of the first transistor 15 in the final stage with the voltage obtained as a result of passing through the differentiation circuit 13 and the charging circuit 14 starting from the rectangular pulse. Therefore, a signal abnormality at a stage before the differentiation circuit 13, for example, a DC voltage state including 0V of a driving pulse output due to runaway of the microcomputer 11, or the control unit 5 is arranged on the printed wiring board, and the printed wiring is electrically In the case where the connection is formed, the DC voltage to the differentiating circuit 13 due to malfunction or failure in the printed wiring path upstream of the differentiating circuit of the drive signal system of the first relay 2 or the occurrence of a defect such as adhesion of foreign matter. In the output state, the first transistor 15 in the final stage is not driven, and the connection end of the first relay 2 is kept open. It is, increases the safety of the equipment.

  In the present embodiment, the control circuit 5 is mounted on the printed wiring board to form the electrical connection of the components, and further the printed wiring path preceding the differentiation circuit 13 of the drive signal system of the first relay 2. Is longer than the printed wiring path in the subsequent stage (including the differentiation circuit 13 and realized by mounting the subsequent circuit in the immediate vicinity of the first relay 2). 2) The risk of unintentional closing will be reduced and the safety of the equipment will be further enhanced.

  The monitoring means 19 determines that a problem has occurred on the drive circuit side of the first relay 2 if there is a difference greater than a predetermined value from the period or amplitude of the pulse voltage output from the microcomputer 11. Then, the driving of the other second relay 4 energizing the resistance load 3a is stopped and the energization to the resistance load 3a is also stopped. Thereby, the microcomputer 11 may detect that the signal output terminal of the microcomputer 11 is deviated from the pulse voltage normally output due to destruction of the signal output terminal or program latch-up, and the possibility that the microcomputer 11 is not destroyed. By operating the output of the drive signal output terminal to the second relay 4 with 0V, that is, the drive stop state to open the contact of the second relay 4, the safety of the device is enhanced.

  As described above, according to the present embodiment, the first relay 2 is connected to the AC power source 1 and the resistive load 3a by the first relay 2 and the second relay 4 having the contact point as the connection end. Is driven based on a voltage obtained by charging a periodic pulse voltage such as a rectangular wave with a voltage obtained by removing a DC component in the differentiating circuit 13. Thus, when a malfunction such as malfunction or failure occurs in the printed wiring path of the drive signal system, or a foreign matter adheres to the DC voltage, the final stage of the first drive means 12 is reached. The drive signal is not transmitted to the first transistor 15, the connection end of the first relay 2 is opened, the connection between the AC power supply 1 and the resistance load 3a is cut off, and the safety of the device can be improved.

  In this embodiment, the number of heating units is one. However, the same effect can be obtained even when a plurality of heating units are provided. In this case, the first relay is used in common and the corresponding (resistive) load and the same are used. Needless to say, if the other end of the load is connected to the AC power supply by another relay in series, the same effect can be obtained while the configuration of the first driving means 12 remains one.

  The heating cooker of the present invention has a resistive load that uses electrical energy as a heating unit, and is useful when the embodiment is implemented using a microcomputer or a printed wiring board. In addition to the electric heating cooker to be used, it can be applied to an electric cooker such as an oven microwave oven equipped with a sheath heater for roaster, an IH cooking heater equipped with a radiant heater, a sheathed heater for oven, and the like.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 1st relay 3 Heating part 3a Resistive load 4 2nd relay 5 Control part 12 1st drive means 13 Differentiation circuit 13a 1st capacitor | condenser 13b Resistance 14 Charging circuit 14a 2nd capacitor | condenser 17 2nd capacitor | condenser Drive means 19 Monitor means

Claims (3)

A heating unit, and a control unit for controlling the operation of the heating unit has a microcomputer, the heating unit is connected respectively with a resistive load across said resistive load, the first relay having a contact and consists of a series of a second relay, said series body and an AC power source connected in parallel, the control unit obtains the operating power from the AC power source, said first relay and said second relay First driving means and second driving means for driving each of the first and second driving means. When energizing the resistance load, the first relay is driven to be in a conductive state, and then the second relay is turned on / off. By making the heating load variable, the heating output of the resistance load is varied, and the first driving means applies a pulse voltage having a predetermined period and a predetermined amplitude output from the microcomputer , and the resistance and the first Differential consisting of capacitors After removal of the DC component through the road, said first relay is driven based on the voltage stored in the charging circuit of a second capacitor, said second drive means, the drive signal transfer, The second relay is driven using a DC signal, the application of the pulse voltage is stopped, the voltage stored in the second capacitor is discharged, and the driving of the first relay is stopped to stop the resistance. A cooking device configured to turn off the load . A heating unit, and a control unit for controlling the operation of the heating unit, the heating unit is connected respectively with a resistive load across said resistive load, the first relay and a second relay provided with contacts consists of a series of a, said series body and an AC power source connected in parallel, the control unit obtains the operating power from the AC power source, the respectively driving said first relay and said second relay Having a driving means and a second driving means, when energizing the resistance load, the first relay is driven to be in a conductive state, and then the second relay is turned on / off. The heating output of the resistive load is varied, and the first driving means applies a pulse voltage having a predetermined period and a predetermined amplitude in which the pulse waveform is rectangular, and a differential circuit comprising a resistor and a first capacitor After removing the DC component through Driving the first relay based on the voltage stored in the charging circuit composed of a capacitor, the second drive means, the drive signal transfer, to drive the second relay with a DC signal, has a monitoring means for monitoring the amplitude or period of the pulse voltage by the control unit is input to said first drive means, wherein the control unit, amplitude or period of the pulse voltage in which the monitoring means has detected When the value falls outside the predetermined range, the cooking device wherein the second driving means is configured to stop the power supply to the second of said resistive load relay in the open state. At least placing a portion of the control unit including the said first relay the first drive means to the printed circuit board, forming an electrical connection of the components in the printed circuit and the signal leads of the printed circuit board and, wherein said than stage subsequent to the differential circuit of the first driving means, heating according to claim 1 or 2 pulse voltage is configured to be longer the former-stage electrical connection path from said differentiating circuit is applied Cooking device.

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