JP2005207731A - High frequency heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems wherein damage due to abnormal temperature rise are given to components of a high frequency heating device and foods are overheated when a microcomputer is malfunctioned. <P>SOLUTION: The high frequency heating device comprises a PTC element 104 connected in series to a coil portion 103 of a relay 101. Thereby, when the microcomputer 4 is malfunctioned to continuously supply electric power to the coil portion 103, the PTC element 104 is also continuously heated, and when a temperature reaches a trip point, the power supply to the coil portion 103 is cut off. Thus, the PTC element 104 with power supply cut off has temperature drop, and when a resetting temperature is reached, the power supply to the coil portion 103 is restarted. As a result, the heating of foods is discontinuously operated without depending on the control of the microcomputer, damages are less given to the components of the high frequency heating device, and the foods are prevented from being overheated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-frequency heating device having a function of connecting a PTC element or a PTC element and a resistance element in series with a coil portion of a relay and intermittently heating food without depending on control of a microcomputer. .

  Conventionally, this type of high-frequency heating apparatus has a configuration in which a temperature sensor detects a temperature change of a resistance element used in a power supply circuit, and a microcomputer stops high-frequency heating by the output of the temperature sensor (for example, Patent Document 1). reference).

  In addition, there is a configuration in which a temperature sensor detects a temperature change of the magnetron, and a microcomputer stops high-frequency heating by the output of the temperature sensor (for example, see Patent Document 2).

  FIG. 5 shows a conventional high-frequency heating device described in Patent Document 1. In FIG. As shown in FIG. 5, an inverter 1, an inverter transformer 2 that boosts the output of the inverter 1, a high-voltage circuit 3 that supplies boosted power to the magnetron, a microcomputer 4 that controls the drive of the inverter 1, a commercial The power supply circuit 6 is configured to receive power from the power supply 5 and the temperature sensor 8 disposed so as to be in contact with the resistance element 7 used in the power supply circuit 6. A temperature change of the resistance element 7 used in the power supply circuit 6 is detected by the temperature sensor 8 and transmitted to the microcomputer 4. If the output of the temperature sensor 8 is equal to or higher than the set value, the microcomputer 4 stops the operation of the inverter 1.

FIG. 6 shows a conventional high-frequency heating device described in Patent Document 2. As shown in FIG. As shown in FIG. 6, it is composed of a magnetron 9, a temperature sensor 8, and a microcomputer 4. The microcomputer 4 controls the operation time of the magnetron 9 based on the temperature information of the magnetron 9 output from the temperature sensor 8.
JP 2001-110561 A Japanese Patent Laid-Open No. 7-57868

  However, in the conventional configuration, the temperature sensor detects the temperature change of the temperature detection object such as the resistance element and the magnetron, and the microcomputer controls the inverter and the magnetron based on the output of the temperature sensor. If the computer malfunctions, control of the inverter and magnetron becomes impossible, the inverter and magnetron abnormally rise in temperature, causing damage to the components of the high-frequency heating device, and the heated food becomes overheated, In the worst case, food may catch fire. In addition, when a microcomputer malfunctions, it is often difficult for the user to determine whether the microcomputer is malfunctioning or operating normally, and an odor that occurs after the high-frequency heating device has received considerable damage. In addition, there is a problem that the user often notices abnormalities due to abnormal sounds.

  The present invention solves the above-described conventional problems, and even if the microcomputer malfunctions by providing the function of intermittently heating the food without depending on the control of the microcomputer, the high-frequency heating device is extremely damaged. An object of the present invention is to provide a high-frequency heating device that is small and can prevent overheating of the food being heated.

  In order to solve the above-mentioned conventional problems, the high-frequency heating device of the present invention is a high-frequency heating device equipped with a microcomputer having a function of intermittently heating food without depending on the control of the microcomputer. It is.

  As a result, it is possible to intermittently heat the food regardless of the control of the microcomputer, so that even if the microcomputer malfunctions, the damage to the components of the high-frequency heating device such as the inverter and magnetron is extremely small, and It is also possible to prevent overheating of the food being heated.

  The high-frequency heating device of the present invention includes a power source unit that drives a magnetron for heating food and an electrothermal heating unit, a relay that includes an open / close unit and a coil unit that supplies power to the power unit, and a coil unit of the relay. A PTC element or a temperature switch is provided in series, and the PTC element or the temperature switch is configured to be able to intermittently operate the heating of food by cutting off the power supply to the coil portion of the relay.

  When the magnetron or the electrothermal heating means is operated, the coil portion of the relay is energized in order to supply power to the power supply unit, a closed circuit is formed by the relay opening / closing means, and the magnetron or the electrothermal heating means operates. At the same time, the PTC element connected in series with the coil portion of the relay is also energized. Similarly, when the microcomputer malfunctions and the food continues to be heated, the PTC element is in an energized state. The PTC element has a characteristic that the resistance rapidly increases when the temperature exceeds the trip point. When a current flows through the PTC element, the temperature of the PTC element rises due to Joule heat, and when the temperature exceeds the trip point, the PTC element Interrupts the current by a sudden increase in resistance. When the current is interrupted by the PTC element, the current in the coil part of the relay connected in series with the PTC element is also interrupted, the relay opening / closing means cannot form a closed circuit, and power cannot be supplied to the power source part. The heating operation stops. The temperature of the PTC element that no longer flows current decreases with time, and when it reaches a certain return temperature, the resistance decreases rapidly, the current flows again, the relay coil part is energized, and the relay switching means forms a closed circuit. Then, the food heating operation starts again. In other words, by providing a PTC element in series with the coil portion of the relay, it is possible to intermittently heat the food without depending on the control of the microcomputer, so even if the microcomputer malfunctions, high-frequency heating such as an inverter or magnetron The damage given to the components of the apparatus is extremely small, and overheating of the food being heated can be prevented. Similar effects can be obtained by using a temperature switch in the same manner as described above.

  The high-frequency heating device of the present invention has a function of intermittently heating food without depending on the control of the microcomputer. Since the heating of food is intermittently operated even if the microcomputer malfunctions, the high-frequency heating device The damage to the component parts is extremely small, and overheating of the heated food can be prevented.

  In the first invention, the PTC element can be attached simultaneously with the assembly of the printed circuit board, and the wiring can be simplified by printing on the printed circuit board, and the printed circuit board is divided along the perforation when the high-frequency heating apparatus is assembled. In addition, the PTC element can be arranged at an optimum place in the air path of the cooling air generated by the cooling means. As a result, since the cooling efficiency of the PTC element is improved, a decrease in the temperature of the PTC element after the trip point is exceeded can be promoted, and the non-operation time of the intermittent operation can be shortened.

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

(Embodiment 1)
FIG. 1 shows a schematic circuit diagram of a main part of a high-frequency heating device according to a first embodiment of the present invention.

  In FIG. 1, a relay 101 includes an opening / closing means 102 and a coil unit 103, a PTC element 104 is connected in series with the coil unit 103, and the microcomputer 4 is configured to control power supply to the coil unit 103. Furthermore, the opening / closing means 102 of the relay 101 is configured to perform an opening / closing operation of a circuit including the commercial power supply 5 and the power supply unit 105.

  About the high frequency heating apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, in order to heat food with a high-frequency heating device, the microcomputer 4 supplies power to the coil portion 103 of the relay 101. The coil unit 103 supplied with power closes the opening / closing means 102 to form a closed circuit including the commercial power source 5 and the power source unit 105, and the power source unit 105 supplied with power from the commercial power source 5 is a magnetron (not shown). Or an electric heating means (not shown) is driven to heat the food. Here, when the microcomputer 4 malfunctions and the power supply to the coil unit 103 of the relay 101 is continued even if the heating time intended by the user is exceeded, the PTC element 104 connected in series to the coil unit 103 is connected to the PTC element 104 connected in series. Since the current flows, the PTC element 104 continues to generate heat due to Joule heat, and when the temperature exceeds the trip point, the PTC element 104 cuts off the current due to a sudden increase in resistance. When the current is cut off by the PTC element 104, the current of the coil part 103 of the relay 101 connected in series with the PTC element 104 is also cut off, and the switching means 102 of the relay 101 is a closed circuit including the commercial power supply 5 and the power supply part 105. The food heating operation stops. Further, the temperature of the PTC element 104 in which the current stops flowing decreases with time, and when the temperature reaches a certain return temperature, the resistance rapidly decreases, the current flows again, the coil portion 103 of the relay 101 is energized, and the relay 101 is opened and closed. The means 102 forms a closed circuit and the food heating operation starts again.

  As described above, in the present embodiment, since the PTC element 104 is provided in series with the coil portion 103 of the relay 101, the heating of food can be intermittently operated without depending on the control of the microcomputer 4. Even if 4 malfunctions, damage to the components of the high-frequency heating apparatus is extremely small, and overheating of the food being heated can be prevented.

In FIG. 1, power supply to the coil unit 103 of the relay 101 is described as +18 V as an example, but it is needless to say that the operating voltage of the coil unit 103 of the relay 101 actually used.

  FIG. 2 shows that the resistance element 7 can be added to the PTC element 104 in series by connecting the resistance element 7 together with the PTC element 104 to the coil portion 103 of the relay 101 of the present embodiment. The time at which 104 reaches the trip point can be manipulated. That is, since the amount of heat generated by the resistance element 7 varies depending on the resistance value, the time for the PTC element 104 to reach the trip point can be set in advance by increasing or decreasing the resistance value of the resistance element 7. That is, it is possible to set the time for shifting the heating of the food from the continuous operation to the intermittent operation without depending on the control of the microcomputer 4 by the high-frequency heating device.

  FIG. 3 shows the PTC element of this embodiment as a temperature switch 106. Since the temperature switch 106 does not self-heat due to Joule heat unlike the PTC element, By thermally coupling, the temperature of the component can be accurately detected. That is, by thermally coupling with a component that is easily destroyed by temperature by continuous operation, the component is protected, or the outer temperature protection that the user can easily touch without noticing that the microcomputer 4 is malfunctioning. And so on.

(Embodiment 2)
FIG. 4 is an enlarged view of the main part of the printed circuit board of the high-frequency heating device according to the second embodiment of the present invention.

  In FIG. 4, the relay 101, the PTC element 104, and the resistance element 7 are arranged on the same printed circuit board 107, and the printed circuit board 107 has a perforation 108 between the PTC element 104 and the relay 101.

  About the high frequency heating apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  A perforation 108 is provided so that the relay 101 and the PTC element 104 can be separated, the printed circuit board 107 is divided along the perforation 108 when the high-frequency heating apparatus is assembled, and the PTC element 104 is cooled by cooling means (not shown). It can be placed in the best location of the wind path. As a result, since the cooling efficiency of the PTC element 104 is improved, the temperature drop of the PTC element 104 after exceeding the trip point can be promoted, and the non-operation time of the intermittent operation can be shortened. That is, the non-operation time at the intermittent operation can be set by changing the arrangement of the PTC element 104.

  As described above, the high-frequency heating device according to the present invention can intermittently heat the food without depending on the control of the microcomputer. Therefore, when the microcomputer malfunctions, the component parts of the high-frequency heating device Can be extremely reduced, and overheating of the food can also be prevented.

  Furthermore, the present invention is not limited to a high-frequency heating device, and can also be developed as a protection device when a microcomputer of a device controlled by a microcomputer and a relay malfunctions.

1 is a schematic circuit diagram of a main part of a high-frequency heating device using a PTC element according to Embodiment 1 of the present invention. 1 is a schematic circuit diagram of a main part of a high-frequency heating device using a PTC element and a resistance element according to Embodiment 1 of the present invention. 1 is a schematic circuit diagram of a main part of a high-frequency heating device using a temperature switch according to Embodiment 1 of the present invention. The principal part enlarged view of the printed circuit board of the high frequency heating apparatus in Embodiment 2 of this invention Schematic circuit diagram of a conventional high-frequency heating device Schematic circuit diagram of a conventional high-frequency heating device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inverter 2 Inverter transformer 3 High voltage circuit 4 Microcomputer 5 Commercial power supply 6 Power supply circuit 7 Resistance element 8 Temperature sensor 9 Magnetron 101 Relay 102 Opening and closing means 103 Coil part 104 PTC element 105 Power supply part 106 Temperature switch 107 Printed circuit board 108 Perforation

Claims (1)

A high-frequency heating apparatus in which a PTC element is disposed on the same printed circuit board as a relay, the printed circuit board is provided with a perforation capable of separating the PTC element and the relay, and the PTC element and the relay are separated by the perforation.

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