JP2011150872A - High-frequency heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency heating device, especially one in daily use, with power consumption at standby not negligible, and requiring a power synchronizing signal. <P>SOLUTION: The device is provided with a heating chamber to house a cooked object, a high-frequency generating device generating high frequencies to the heating chamber, a power source noise filter circuit for decreasing power source noise generated by the high-frequency generating device, a power source synchronized detection circuit connected to both ends of the power source for detecting information of power source frequencies, and a printed board 1 retaining electric components and making electric connection. A power source noise filter circuit component and the power source synchronized detection circuit are mounted on the same printed board 1, and the power source synchronized detection circuit is to be used as a discharge channel of a charge stored at both ends of a capacitor structuring the above noise filter circuit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a high-frequency heating device, and more particularly to a configuration that reduces power consumption during standby and improves safety during service.

  FIG. 6 shows a circuit diagram of the entire conventional high-frequency heating apparatus. A magnetron 102 that heats food is connected from a commercial power source via a high-voltage power source 101 that performs power control. In addition, a current fuse 103 that cuts off the current at the time of overcurrent is attached. Similarly, a low voltage transformer 105 for supplying a predetermined voltage is connected from a commercial power source to a control circuit 104 which is a control means for controlling the high frequency heating device. The low-voltage transformer 105 is inserted with a thermal fuse 106 for preventing a rare short circuit caused by abnormal heat generation due to a short circuit failure of the secondary side output of the low-voltage transformer.

  One of the secondary outputs of the low-voltage transformer 105 is provided with a power supply synchronization detection circuit 107. By detecting the power supply frequency of the commercial power supply via the winding of the low-voltage transformer 105, the power supply phase and the commercial frequency are detected. Information necessary for controlling the high-frequency heating device is obtained. This information is used by a microcomputer constituting the control circuit 104 for time measurement and control of the input phase of a relay or the like. By controlling the relay input phase, it is possible to suppress the consumption of relay contacts as much as possible.

  Further, a temperature switch 108 is attached to one side of a power supply line to the low-voltage transformer 105. The temperature switch 108 is attached to detect abnormal heat generation of the electrical components of the high-frequency heating device and stop the operation. In the case of FIG. 6, when the temperature switch 108 operates, the supply of power to the low-voltage transformer 105 is cut off, and the operation of the device is stopped by stopping the operation of the control circuit 104.

  On the other hand, the high-frequency generator generates noise from the high-voltage power supply 101 and the magnetron 102 when generating a high frequency, and transmits the noise to the power plug through the internal wiring. As a result, noise is transmitted to other electrical devices connected to the same outlet via the power plug, and when other electrical devices are equipped with a microcomputer, malfunctions occur due to the noise of the high-frequency heating device. It has developed into social problems such as resetting and turning off the power, or in the worst case, causing an unsafe operation such as the microcomputer program not running out of control due to runaway of the microcomputer program.

  Therefore, it has become necessary to attach a power supply noise filter circuit 109 that reduces noise generated from the high-voltage power supply 101 and the magnetron 102 when the high-frequency heating device generates high-frequency. Noise generated by the high-frequency heating device includes a normal mode that propagates between lines and a common mode that propagates between both lines and the ground. An example of a circuit diagram of a power supply noise filter circuit for reducing them is shown in FIG. Common mode choke coil 120 for reducing low-frequency common noise, line-to-line capacitor 121 for reducing low-frequency normal mode noise, line ground for reducing high-frequency common and normal mode noise It is comprised by three types of electrical components of the interposition capacitor | condenser 122 (for example, refer patent document 1).

In the case of the high-frequency heating device of FIG. 6, since the electric charge stored at both ends of the capacitor between the lines 121 is discharged through the primary winding of the low-voltage transformer 105, the power is immediately supplied even when the user unplugs the power plug. The voltage between the plug terminals is reduced to prevent electric shock. However, when the thermal fuse 106 built in the low-voltage transformer 105 is activated when the high-frequency heating device fails due to some cause, the discharge path of the inter-line capacitor 121 is cut off, so that a voltage remains at both ends of the power plug, resulting in an electric shock. The danger remains. The same applies when the temperature switch 108 operates.

  Further, the same danger remains when the wiring connecting the power supply noise filter circuit and the temperature switch 108 or the low-voltage transformer 105 is disconnected for some reason. In order to reduce such a risk, a discharge resistor 124 is generally inserted into the power supply noise filter circuit 123 improved as shown in FIG.

  Furthermore, recently, development of devices that are friendly to the global environment has been desired, and in particular for home appliances that are used on a daily basis, legislation concerning power consumption has been promoted. Among them, the standby power that is not in operation is said to be 10% to 20% of the total power consumption, and is attracting particular attention. Considering the actual usage of the high-frequency heating device, in order to minimize the power consumption of the non-operation time, that is, the standby time, from the actual cooking time using high-frequency heating, heaters, etc. Switching power supplies are being replaced.

  Furthermore, a high-frequency heating device has been developed that reduces the load on the control circuit as much as possible and further reduces power consumption when unnecessary (see, for example, Patent Document 2). In the case of the switching power supply 125, the power of the commercial power source once smoothed with a diode and a capacitor is converted by the switching element and the transformer, so that the commercial frequency information is detected on the secondary side of the transformer like a low-voltage transformer. Therefore, a power supply synchronization detection circuit 126 using a photocoupler as shown in FIG. 9 is generally used for information necessary for controlling the power supply phase and the high-frequency heating device of the commercial frequency.

Japanese Patent No. 2864879 Japanese Patent No. 3397197

  However, in addition to the power consumed by the low-voltage transformer or switching power supply 125, which is the power supply of the control circuit, and the power supply synchronization detection circuit 126, a temperature switch 108 installed as a safety device and a temperature fuse 106 built in the low-voltage transformer 105 are provided. In order to suppress the voltage remaining at the terminal of the power plug even when it operates, a discharge resistor is required in addition to the low-voltage transformer 105 that also functions as a discharge circuit during normal use. It was the composition to do.

  The present invention provides a high-frequency heating device that is safe even during normal use, an assumed failure state, and at the time of repair service, reduces power consumption of unnecessary equipment, and does not incur unnecessary costs. .

The present invention relates to a heating chamber for storing an object to be cooked, a high frequency generator for generating a high frequency in the heating chamber, a power noise filter circuit for reducing power noise generated by the high frequency generator, and both ends of a power source. And a first power supply synchronization detection circuit for detecting information on the power supply frequency and a printed circuit board for holding and electrically connecting the electric components, and the power noise filter circuit component and the first power supply synchronization detection on the same printed circuit board. The first power supply synchronization detection circuit is used as a discharge path for charges stored at both ends of a capacitor of a serial connection body of a first switch and a capacitor provided at both ends of the power supply constituting the noise filter circuit. It was set as the structure using.

  According to the high-frequency heating device of the present invention, since the electric charge of the capacitor is discharged using the power consumption of the first power supply synchronization detection circuit, a dedicated discharge resistor is not required. Also, by configuring the power supply noise filter circuit and the first power supply synchronization detection circuit on the same board, a capacitor discharge path is ensured regardless of whether internal wiring is disconnected or disconnected, a thermal fuse, or a temperature switch is activated. Therefore, safety is compatible. Further, since the capacitor can be disconnected from the power source by the first switch, the power consumption can be further reduced by turning off the first switch.

  Further, according to the present invention, the power supply synchronization detection circuit is composed of a resistor, a photocoupler, and a diode for protecting the photocoupler.

  According to the power supply synchronization detection circuit of the present invention, since it can be configured with a space saving only by adding a connection portion of a diode, a photocoupler, and a signal line, the size of the printed circuit board on which the conventional power supply noise filter circuit is mounted is not much. Since it is not necessary to increase the size, the possibility of sharing the mounting structure of the printed circuit board on the main body increases, and the design can be standardized. In addition, since the light emitting element of the photocoupler in series with the conventional discharge resistor and the diode are inserted in parallel in the opposite direction to the light emitting element, the operation of the primary circuit of the discharge circuit is the same as the conventional one, so the conventional power noise filter performance Has almost no effect. Further, since the electrical coupling with the control circuit is insulated by the photocoupler, it can be configured with almost no influence of noise from the control circuit side.

  In addition, the present invention is configured to include a second power supply synchronization detection circuit that is connected to both ends of the power supply and detects information on the power supply frequency, separately from the first power supply synchronization detection circuit.

  By providing the second power supply synchronization detection circuit of the present invention, it is possible to detect the power supply frequency information even when the first switch is turned off. Further, since the second power supply detection circuit is independent of the discharge path of the capacitor, the second power supply detection circuit can be set to a value larger than the resistance constituting the first power supply synchronization detection circuit. Electric power can be reduced.

  Moreover, the high-frequency heating device of the present invention has a configuration in which the control means is arranged on the same printed circuit board.

  According to the high-frequency heating device of the present invention, it is possible to reduce the number of connection terminals for connecting with a lead wire or the like by configuring a control circuit as a control means on the same printed circuit board.

  According to the present invention, it is possible to reduce the resistance for discharging a capacitor disposed between lines provided for noise suppression while considering safety during service, and to reduce power consumption. Can do.

The perspective view of the printed circuit board of the high frequency heating apparatus in Example 1 of this invention Circuit diagram of printed circuit board in Embodiment 1 of the present invention The circuit diagram of the whole high frequency heating device in Example 1 of the present invention. Circuit diagram of printed circuit board in Embodiment 2 of the present invention The circuit diagram of the whole high frequency heating apparatus in Example 2 of the present invention Circuit diagram of conventional high-frequency heating device Circuit diagram of conventional power supply noise filter circuit Circuit diagram of conventional improved power supply noise filter circuit Circuit diagram of a conventional power supply synchronization detection circuit using a photocoupler

  A first invention includes a heating chamber for storing an object to be cooked, a high frequency generator for generating a high frequency in the heating chamber, a power noise filter circuit for reducing power noise generated by the high frequency generator, and both ends of a power source. And a first power supply synchronization detection circuit for detecting power frequency information and a printed circuit board for holding and electrically connecting electric components, the power supply noise filter circuit component and the first power supply on the same printed circuit board The first power supply synchronization is used as a discharge path for the electric charge stored at both ends of the capacitor of the series connection body of the first switch and the capacitor connected in series to the power supply constituting the noise filter circuit. The detection circuit is used.

  According to the high-frequency heating device of the present invention, since the electric charge of the capacitor is discharged using the power consumption of the first power supply synchronization detection circuit, a dedicated discharge resistor is not required. Also, by configuring the power supply noise filter circuit and the first power supply synchronization detection circuit on the same board, a capacitor discharge path is ensured regardless of whether internal wiring is disconnected or disconnected, a thermal fuse, or a temperature switch is activated. Therefore, safety is compatible. Further, since the capacitor can be disconnected from the power source by the first switch, the power consumption can be further reduced by turning off the first switch.

  In the second aspect of the invention, the power supply synchronization detection circuit is constituted by a resistor, a photocoupler, and a diode for protecting the photocoupler.

  According to the power supply synchronization detection circuit of the present invention, since it can be configured with a space saving only by adding a connection portion of a diode, a photocoupler, and a signal line, the size of the printed circuit board on which the conventional power supply noise filter circuit is mounted is not much. Since it is not necessary to increase the size, the possibility of sharing the mounting structure of the printed circuit board on the main body increases, and the design can be standardized. In addition, since the light emitting element of the photocoupler in series with the conventional discharge resistor and the diode are inserted in parallel in the opposite direction to the light emitting element, the operation of the primary circuit of the discharge circuit is the same as the conventional one, so the conventional power noise filter performance Has almost no effect. Further, since the electrical coupling with the control circuit is insulated by the photocoupler, it can be configured with almost no influence of noise from the control circuit side.

  In addition, the third invention is configured to include a second power supply synchronization detection circuit that is connected to both ends of the power supply and detects information on the power supply frequency, separately from the first power supply synchronization detection circuit.

  By providing the second power supply synchronization detection circuit of the present invention, it is possible to detect the power supply frequency information even when the first switch is turned off. Further, since the second power supply detection circuit is independent of the discharge path of the capacitor, the second power supply detection circuit can be set to a value larger than the resistance constituting the first power supply synchronization detection circuit. Electric power can be reduced.

  The high-frequency heating device according to the fourth aspect of the invention has a configuration in which the control means is disposed on the same printed circuit board.

  According to the high-frequency heating device of the present invention, it is possible to reduce the number of connection terminals for connecting with a lead wire or the like by configuring a control circuit as a control means on the same printed circuit board.

  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)
1 is a perspective view of a printed circuit board of a high-frequency heating device according to Embodiment 1 of the present invention. FIG. 2 is a circuit diagram of the printed circuit board according to Embodiment 1 of the present invention. As shown in FIG. 2, the printed circuit board 1 includes a common mode choke coil 2 for reducing low-frequency common noise and a line-to-line capacitor 3 for reducing low-frequency normal mode noise. Three types of electrical components, a line-to-ground capacitor 4 to reduce noise in both high-frequency common and normal modes, a printed circuit board mounted clip-type fuse holder 6 with a current fuse 5, and power from a commercial power source Tab terminal 7 for connecting the power supply line for supplying power to the input side of the printed wiring of the printed circuit board 1, and the tab terminal for connecting the output side of the printed circuit of the printed circuit board 1, the control circuit for the high frequency heating device and the high frequency generator 8, a resistor 9a constituting a first power supply synchronization detection circuit, a photocoupler 10a, and a photocoupler 10a as shown in FIG. In order to reduce the low-frequency normal mode noise, the diode 11a for protecting the terminal on the light emitting side, the tab terminal 12a for connecting the output signal of the first power supply synchronization detection circuit and the control board 18 as the control means. A relay 13 constituting a first switch for disconnecting one side connected to the power source of the line-to-line capacitor 3, a tab terminal 14 for extracting a signal from a coil side terminal of the relay 13, and a printed wiring on the back surface of the printed circuit board 1. Soldered and electrically connected.

  About the high frequency heating apparatus comprised as mentioned above, the operation | movement is demonstrated using the circuit diagram of the whole high frequency heating apparatus in Embodiment 1 of this invention shown in FIG.

  In FIG. 3, food is heated from a commercial power source via a printed circuit board 1 in which a power noise filter circuit and a first power synchronization detection circuit are arranged on the same substrate, via a relay 20 for controlling power and a high voltage transformer 15. A magnetron 16 is connected. Similarly, a control board 18 to which power is supplied and a power supply circuit 19 of the control board 18 are connected to the output side of the printed board 1 through a temperature switch 17.

  Further, the output signal of the first power supply synchronization detection circuit from the printed board 1 is connected to the control board 18 using a lead wire or the like. In addition, the connection signal to the coil side terminal of the relay 13 that can turn on / off the supply of commercial power from the printed circuit board 1 to the inter-line capacitor 3 and the first power supply synchronization detection circuit uses a lead wire or the like. Connected. The microcomputer constituting the control board 18 is used for time measurement of the high-frequency heating apparatus and control of the input phase of the relay, etc. based on the information of the power supply phase and the commercial frequency obtained from the first power supply synchronization detection circuit. Information is used.

  The temperature switch 17 is attached in order to detect abnormal heat generation of electrical components of the high-frequency heating device and stop the operation. For example, it is possible to attach to the high voltage transformer 15 and detect the occurrence of a rare short of the high voltage transformer 15 in advance. In the case of the circuit configuration of the present invention, even when the temperature switch 17 is operated, the discharge path of the inter-line capacitor 3 is ensured regardless of the operation of the temperature switch 16, so that even if the power plug is removed, the discharge is immediately performed. Therefore, even if there is an opportunity to touch the printed circuit board 1 at the time of service, the risk of electric shock is reduced. Further, by providing the relay 13, information on the power supply phase and the commercial frequency is required. For example, in a standby state other than the cooking operation mode, the relay 13 is turned off to be consumed by the first power supply synchronization detection circuit. Power to be reduced.

(Embodiment 2)
FIG. 4 is a circuit diagram of the printed circuit board according to Embodiment 2 of the present invention. FIG. 5 is a circuit diagram of the entire high-frequency heating device according to Embodiment 2 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the second embodiment, in addition to the first power supply synchronization detection circuit, a second power supply synchronization detection circuit that is connected to both ends of the power supply and detects information on the power supply frequency is provided. As shown in FIG. 4, the second power supply synchronization detection circuit includes a resistor 9b, a photocoupler 10b, and a diode 11b for protecting the light emitting side terminal of the photocoupler 10b. A tab terminal 12b for connecting the output signal and the control board 18 which is a control means is provided.

  Since the resistor 9b of the second power supply synchronization detection circuit is independent of the discharge path of the inter-line capacitor 3, it can be increased to the maximum resistance value at which the power supply synchronization detection circuit can operate. By doing so, the power consumed by the second power supply synchronization detection circuit can be minimized. Since the resistor 9a of the first power supply synchronization detection circuit affects the discharge time of the inter-line capacitor 3, if it is made too large, it takes too much discharge time and cannot satisfy the original purpose of preventing electric shock.

  Further, by providing the second power supply synchronization detection circuit, even when the relay 13 is turned off, information on the commercial frequency can be obtained and time can be measured, for example, a clock can be displayed.

  Further, by configuring the control board 18 and the printed board 1 of the second embodiment on the same board, connection terminals and connection lead wires for connecting the control board 18 and the printed board 1 are provided. Can be reduced.

  As described above, according to the present invention, in particular, it can be used for household appliances and the like that are used daily, the power consumption during standby cannot be ignored, and a power supply synchronization signal is required.

DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Common mode choke coil 3 Line capacitor 4 Line earth capacitor 5 Current fuse 6 Clip type fuse holder 7, 8, 12a, 13 Tab terminal 9a Resistance 10a Photocoupler 11a Diode

Claims (7)

A heating chamber for storing the cooking object, a high frequency generator for generating a high frequency in the heating chamber, a power noise filter circuit for reducing power noise generated by the high frequency generator, and a power source frequency connected to both ends of the power source A first power supply synchronization detection circuit for detecting information and a printed circuit board for holding and electrically connecting electrical components, and mounting a power supply noise filter circuit component and the first power supply synchronization detection circuit on the same printed circuit board A high frequency using the first power supply synchronous detection circuit as a discharge path of charges stored at both ends of the capacitor of the serial connection body of the first switch and the capacitor provided at both ends of the power supply constituting the noise filter circuit Heating device. The high-frequency heating device according to claim 1, wherein the power supply synchronization detection circuit includes a resistor, a photocoupler, and a diode for protecting the photocoupler. The high frequency heating apparatus according to claim 2, further comprising a second power supply synchronization detection circuit connected to both ends of the power supply for detecting information on the power supply frequency. The high-frequency heating device according to claim 3, wherein a resistance value of a resistor of the second power supply synchronization detection circuit is larger than a resistance of the first power supply synchronization detection circuit. The high-frequency heating apparatus according to claim 1, further comprising a control unit that controls the high-frequency heating apparatus, wherein the control unit measures time based on information on a power supply frequency of the power supply synchronization detection circuit. The high-frequency heating apparatus according to claim 1, wherein the control means turns off the first switch when information from the first power supply synchronization detection circuit is unnecessary. 7. The high frequency heating apparatus according to claim 5, wherein the control means is disposed on the same printed circuit board.