JPH0113358Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high frequency heating device having an electronic control circuit equipped with a microcomputer.

Configuration of conventional example and its problems Figure 1 shows a conventional example, in which the high-frequency heating device 1
is equipped with a door 2 that can be opened and closed freely, and is equipped with a high frequency generator, hereinafter referred to as a magnetron 3.
The high frequency waves generated from the waveguide 4 are sent into the heating chamber 26 through the waveguide 4. The high-frequency heating device 1 is connected to an AC power source via a power cable 5.
100V is supplied. A gap-type lightning surge absorption element unit 8 wrapped in a tube made of vinyl chloride or the like is attached to one side of the AC line, and the other side is connected to a metal chassis 9 with screws or the like. A gap-type lightning surge absorption element 1 of a high-frequency heating device is equipped with an electronic control circuit printed circuit board 6 equipped with a microcomputer 7.
9 was not mounted on the same printed circuit board as the electronic control circuit printed circuit board 6, but was incorporated into a lead sensor harness or the like. This is because the microcomputer 7 malfunctions due to noise when the gap type lightning surge absorption element 19 discharges due to induced lightning, etc.
This was to prevent a situation in which, in the worst case scenario, the high frequency would automatically oscillate and there was a combustible substance in the heating chamber 26, a fire would occur, resulting in an extremely dangerous situation.

Furthermore, when the gap-type lightning surge absorption element 19 is incorporated into a lead sensor harness etc., since it is attached to the primary power supply line, it must be insulated from the primary power supply line and protected against vibration and shock, which is one of the costs. It was a contributing factor.

Purpose of the invention The present invention solves the above-mentioned conventional drawbacks.
The purpose of this study is to improve the safety of a high-frequency heating device having an electronic control circuit equipped with a microcomputer against induced lightning, and to improve the performance of the electronic control circuit against noise.

Structure of the Invention In order to achieve the above object, the high-frequency heating device of the present invention has a lightning surge absorption element mounted on an electronically controlled printed circuit board, and a line on the ground side of the microcomputer on the outer periphery of the electronically controlled printed circuit board. This line and the shear line to the main body of the heating chamber of the lightning surge absorption element are separated and independent.
When a gap-type lightning surge absorption element is installed, the noise generated when lightning surge is absorbed and discharged causes malfunctions such as automatic oscillation and erroneous display.
This has the effect of completely eliminating those malfunctions and erroneous displays.

Furthermore, since the lightning surge absorption element is placed on the printed circuit board, the printed circuit board itself is made of an insulating material such as phenol, so there is no need to add an insulating cover, and the above-mentioned absorption element can be soldered onto the printed circuit board. Because of this, it also has the effect of being resistant to vibrations, drops, etc.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings.

In FIG. 2, a metal chassis 9 of a high-frequency heating device 1 includes a magnetron 3, which is a high-frequency generator, and the high-frequency output generated from the magnetron 3 is sent into a heating chamber 26 through a waveguide 4. The fan motor 10 is used to cool the magnetron 3 and the high voltage transformer 11 with air.

There is a resin operation panel 12 on the front of the high-frequency heating device 1, and a metal support plate 13 that supports the electronic control circuit printed circuit board 6 is attached to the operation panel 12. Support plate 1
3 is completely electrically connected to the main body chassis 9 of the heating chamber 26. In addition, the operation panel 12 has
There is a touch-type flat keyboard switch 14, and the signals obtained therefrom are inputted to a connection 15 of the electronic control circuit printed circuit board 6.

FIG. 3 is a view of the electronic component mounting surface of the electronic control circuit printed circuit board 6, in which one of the primary power lines for AC 100V power supplied by the connector 16 is connected to the primary input of the low voltage transformer 17, and the other is connected to the primary input of the low voltage transformer 17. , are supplied to a resistor 18 and communicated with a gap-type lightning surge absorption element 19.

FIG. 4 shows the copper foil pattern part of the electronic control circuit printed circuit board 6, and one side power line of the microcomputer 7 is connected to the printed circuit board 6.
Pattern A is placed on the outer periphery of the
There are 21. The gap-type lightning surge absorption element 19 has a pattern B that constitutes another ground line.
It is connected to 20. Pattern A21 is screw A
23, and is electrically connected to the metal support plate 13 by screws B24. Furthermore, the pattern B20 is provided independently of the pattern A21, and is fastened and electrically connected to the metal support plate 13 by screws C22.

Here, when an induced lightning surge voltage of several KV enters the connector 16 in the high frequency heating device 1 through the power cable 5, a gap-type lightning surge absorption element is activated through the resistor 18 of several ohms, and the surge voltage is regulated. When the voltage reaches the above level, discharge starts and falls from the metal support plate 13 to the metal chassis 9 through the pattern B20. Since the surge current change at this time is quite large (in other words, it is a fairly high frequency), pattern A21 and pattern B2 are used.
0, pattern A21 and pattern B20 are both made of copper foil with a thickness of about 35 μm, so sufficient current cannot flow through them, and due to the surge current change, the pattern becomes impedance. Because the power line is shared with the power line on one side of the microcomputer 7, the microcomputer 7 may malfunction or run out of control, and the power relay 25 may sometimes turn on automatically. It also caused magnetron 3 to oscillate. However, according to this configuration, the pattern A21 of the power supply line on one side of the microcomputer 7 and the pattern B20 of the lightning surge absorption element 19 are separated from each other, so the above-mentioned influence does not occur at all, and the ground line, for example, Even when an induced lightning surge occurs, it remains completely stable in terms of potential.

Also, connect the power line on one side of the microcomputer 7 to the screw A23 through the pattern A21.
Since the screws 24 and screws 24 are dropped onto the metal chassis 9 at multiple locations, the impedance to high frequencies can be made extremely low, and even if an induced lightning surge causes the lightning surge absorption element to discharge and generate high frequency noise. However, the microcomputer 7 is not affected at all and remains stable.

Effects of the invention As described above, according to the invention, the following effects can be obtained.

(1) The grounding of the lightning surge absorbing element mounted on the electronic control printed circuit board to the main body chassis and the grounding of the microcomputer are separated, so high frequency noise caused by induced lightning surge current does not affect the microcomputer. There is no

(2) The ground line of the microcomputer is provided on the outer periphery of the printed circuit board, so it can be grounded to the main body chassis, which has multiple cylinders.
Since the impedance to high frequencies can be made extremely small, the effects of high frequency noise generated when the lightning surge absorption element discharges, high frequency noise emitted from the magnetron, high frequency noise emitted from the power relay, etc. are completely eliminated.

(3) Since the lightning surge absorption element is mounted on the electronic control printed circuit board, there is no need to perform treatments such as insulation covers compared to when it is installed on the lead sensor harness, and it is resistant to drop vibrations. This will improve quality and reduce costs.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional perspective view of a conventional high-frequency heating device, Fig. 2 is a side sectional view of a high-frequency heating device showing an embodiment of the present invention, and Fig. 3 is an electronic control circuit of the same embodiment. FIG. 4 is a diagram showing the component mounting surface of the printed circuit board, and FIG. 4 is a diagram showing the copper foil pattern side of the electronically controlled printed circuit board. 3... Magnetron (high frequency generator), 6...
... Electronic control circuit printed circuit board, 7 ... Microcomputer, 9 ... Main body chassis, 19 ... Lightning surge absorption element, 21 ... Pattern A (ground),
20...Pattern B (earth), 26...Heating chamber.

Claims (1)

[Scope of utility model registration request] A heating chamber, a high frequency generator that supplies high frequency waves to the heating chamber, and an electronic control circuit printed circuit board equipped with a microcomputer that controls high frequency output, and a primary power supply line on the electronic control circuit printed circuit board, A gap-type lightning surge absorption element is inserted between the main body chassis of the heating chamber, and a grounding line of the microcomputer is arranged on the outer periphery of the electronic control circuit printed circuit board, and A high frequency heating device that is connected to the main body chassis and is separated from a ground line of the microcomputer and a ground line that has a connection portion of the lightning surge absorbing element to the main body chassis.