JP5422271B2 - Transformer-mounted substrate device for microwave oven - Google Patents

Description

  The present invention relates to a transformer-mounted substrate device for a microwave oven in which a transformer is mounted on a substrate and a winding terminal of the transformer is connected to a circuit on the substrate.

  In a high-frequency heating device such as a home microwave oven, in order to drive a magnetron, a commercial power supply is converted to direct current, and this direct-current power is converted into high-frequency power by a primary winding of a transformer, a resonant capacitor, and a switching element. A magnetron driving circuit composed of a high voltage capacitor, a high voltage diode or the like is provided on the secondary winding side.

  In the circuit described above, components other than the commercial power source and the magnetron are fixed to the substrate by soldering. In such a configuration, there is one in which a slit is formed so as to surround the connection portion in order to secure an insulation distance of the connection portion between the secondary winding terminal of the transformer and the high-voltage circuit pattern (Patent Document 1).

JP-A-5-335057

  By the way, when the above-described slit is provided, the substrate can be reduced in size, but it is necessary to increase it to some extent in order to secure a certain insulation distance. In this case, the portion surrounded by the slit may bend, and mechanical stress is applied to the connecting portion between the secondary winding terminal of the transformer and the high-voltage circuit pattern, and there is a possibility that a crack or the like may occur in the connecting portion. It was.

  The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the size of the substrate while providing good insulation by providing a slit in the substrate, as well as the secondary winding terminal of the transformer and the high voltage. An object of the present invention is to provide a transformer mounted substrate device for a microwave oven that can prevent mechanical stress from being applied to a connection portion with a circuit pattern.

  The present invention relates to a transformer-mounted substrate device of a microwave oven provided with a transformer on a substrate and a magnetron driving circuit which is a high voltage circuit for driving a magnetron on the secondary side of the transformer. A slit is formed so as to surround a high-voltage circuit pattern having a connection portion connected to a secondary winding terminal, and a fixing portion for fixing the transformer to the substrate is provided in a region surrounded by the slit of the substrate. The secondary winding terminal is connected to the connection portion of the high-voltage circuit pattern, and the transformer is fixed to the substrate by the fixing portion.

  According to the present invention, the slit is formed so as to surround the high voltage circuit pattern including the connection portion connected to the secondary winding terminal of the transformer, and the secondary winding of the transformer is formed in the connection portion of the high voltage circuit pattern. Since the terminals are connected, it is possible to reduce the size of the substrate while achieving good insulation between the high-voltage portion and other portions, and in addition, the region surrounded by the slit (hereinafter referred to as the slit inner region) of the substrate. Since the fixing part for fixing the transformer to the substrate is provided, and the transformer is fixed to the fixing part, the transformer can prevent bending of the area in the slit, and the secondary winding terminal of the transformer and the high-voltage circuit pattern It is possible to prevent mechanical stress on the connecting portion.

  The present invention can reduce the size of the substrate while providing good insulation by providing a slit in the substrate, and can prevent mechanical stress from being applied to the connection portion between the secondary winding terminal of the transformer and the high-voltage circuit pattern.

The partial top view of the board | substrate apparatus mounted with a transformer in the state which shows one Embodiment of this invention and the soldering surface of a board | substrate turns into an upper surface Partial perspective view of a transformer-mounted board device in a state where an electric component fixing surface of the board is an upper surface Plan view showing substrate sheet Diagram showing electrical configuration of microwave oven

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 4 schematically shows the electrical configuration of the microwave oven, which will be described below. The power supply device 1 is supplied with power from a pair of power supply lines 3 and 4 connected to a commercial AC power supply 2. This power supply device 1 includes a rectifier circuit 5 for full-wave rectification of the output of a commercial AC power supply 2, a smoothing reactor 6 and a smoothing capacitor 7 for smoothing the rectified output, and a smoothed DC output of an AC having a predetermined frequency. An inverter circuit 8 for converting the output is provided.

  The inverter circuit 8 has a configuration in which the primary winding 9a of the step-up transformer 9 which is a transformer is used as a resonance element, and a series circuit between the resonance capacitor 10 and the collector and emitter of the IGBT 11 in parallel with the smoothing capacitor 7. And the primary winding 9a of the step-up transformer 9 is connected to both ends of the resonant capacitor 10. The IGBT 11 is on / off controlled by the control device 18.

  Of the two secondary windings 9b, 9c of the step-up transformer 9, the cathode of the magnetron 12 is connected to both ends of the cathode secondary winding 9b which is one of the secondary windings. The anode is connected to the ground terminal. A voltage doubler rectifier circuit 13, which is a magnetron drive circuit, is connected to the other secondary winding 9 c side of the step-up transformer 9. This voltage doubler rectifier circuit 13 is formed by connecting in parallel a series circuit of two high-voltage capacitors 14 and 15 (high-voltage parts) and a series circuit of two high-voltage diodes 16 and 17 (high-voltage parts). The anode of the high-voltage diode 16 on the high potential side is connected to the cathode of the magnetron 12 (one terminal of the secondary winding for cathode 9b).

  A common connection point between the anode of the high-voltage diode 16, the other end of the high-voltage capacitor 14, and one terminal of the cathode secondary winding 9b is indicated by a symbol P3. Further, the common connection point of the high-voltage capacitors 14 and 15 is connected to one terminal 9c1 of the secondary winding 9c (the common connection point is indicated by symbol P1). Further, the common connection point of the high-voltage diodes 16 and 17 is connected to the other terminal 9c2 of the secondary winding 9c (the common connection point is indicated by P2). A common connection point between the other end of the high-voltage capacitor 15 and the cathode of the high-voltage diode 17 is indicated by a symbol P4.

  In this case, when power is supplied from the voltage doubler rectifier circuit 13 to the magnetron 12, the magnetron 12 oscillates to generate microwaves, and the microwaves rotate through a waveguide (not shown). It is configured to be diffused by the antenna and irradiated into the cooking chamber.

  The step-up transformer 9 has a substantially square shape in plan view (shown in part in FIG. 2 and shown in the bottom view in FIG. 1). The step-up transformer 9 includes a portion corresponding to the screw 29 and the screw 30 in FIG. The corresponding portion has a fixed portion (the fixed portion 9d corresponding to the screw 29 is shown in FIG. 2). That is, the fixed portion is on the diagonal line of the step-up transformer 9.

  In the electrical configuration described above, electrical components other than the AC power supply 2 and the magnetron 12 are mounted on the substrate 19 shown in FIGS. A structure in which electrical components are mounted on the substrate 19 is referred to as a microwave-equipped transformer-mounted substrate device 20. As shown in FIG. 3, the substrate 19 is obtained by dividing a substrate sheet 19 </ b> A in which a plurality of, for example, two substrates 19, 19 are connected by a joint 19 a that can be divided. Reference numeral 19b (see FIG. 1) is given to the side portion (divided side portion) on the divided side of the substrate 19.

  In FIG. 1, a soldering surface 19c of the substrate 19 is shown, and the surface opposite to the soldering surface 19c is an electric component fixing surface 19d (see FIG. 2). In FIG. 1, a conductor pattern for the power supply device 1 from the rectifier circuit 5 to the primary winding 9a of the step-up transformer 9 is formed on the left side portion of the GND conductor pattern 24 on the soldering surface 19c. Electric parts for the power supply device 1 other than the step-up transformer 9 are fixed to the electric part fixing surface 19d corresponding to the left portion.

  A plurality of conductor patterns for the voltage doubler rectifier circuit 13 are formed on the soldering surface 19 c of the substrate 19 on the right side of the GND conductor pattern 24. The electric components of the step-up transformer 9 and the voltage doubler rectifier circuit 13 are fixed to the electric component fixing surface 19d corresponding to the right portion.

The main conductor pattern on the soldering surface 19c of the substrate 19 will be described.
The conductor pattern 21 is a high voltage circuit pattern and constitutes the common connection point P1. The conductor pattern 21 includes a connection portion (consisting of a land with a through hole) 21 a connected to one pin-shaped terminal (secondary winding terminal) 9 c 1 of the secondary winding 9 c and one of the high-voltage capacitors 14. A connection portion 21b connected to the terminal and a connection portion 21c connected to one terminal of the high-voltage capacitor 15 are provided. In this case, the connecting portion 21a is located at the tip side of the in-slit region 19E.

  Another conductor pattern 22 constitutes the common connection point P2, and this conductor pattern 22 has a connection portion (consisting of a land with a through hole) 22a connected to one pin-shaped terminal of the high-voltage diode 16. It has a connection part 22b connected to one pin-shaped terminal of the high-voltage diode 17, and further has a connection part 22c connected to the other pin-shaped terminal 9c2 of the secondary winding 9c.

  The conductor pattern 23 constitutes the common connection point P3, and the conductor pattern 23 has a connection portion 23a connected to the other pin-shaped terminal of the high-voltage capacitor 14 and the other pin-shape of the high-voltage diode 16. A connecting portion 23b for connecting to the terminal. Further, the conductor pattern 23 is formed with connection portions 23c and 23d to which both terminals of the cathode secondary winding 9d are connected.

  The conductor pattern 25 is for connecting the other terminal of the high-voltage capacitor 15 and is electrically connected to the GND conductor pattern 24. A connection portion 24 a connected to the other pin-shaped terminal of the high-voltage diode 17 is provided at the lower end portion of the GND conductor pattern 24. Accordingly, the GND conductor pattern 24 constitutes the common connection point P4.

  Here, as shown in FIGS. 1 and 3, a slit 26 having a substantially C shape is formed in the substrate 19 so as to surround the conductor pattern 21. The slit 26 insulates the high voltage circuit portion from the low voltage circuit portion (relatively low pressure). A first screw insertion hole portion 27 as a fixing portion for fixing the fixed portion 9d of the step-up transformer 9 is formed in an in-slit region 19E that is an area surrounded by the slit 26 in the substrate 19. ing. A second screw insertion hole 28 is formed on the substrate 19 on the low voltage circuit side as another fixing portion for fixing the other fixed portion of the step-up transformer 9.

  One terminal 9c1 of the secondary winding 9c of the step-up transformer 9 is connected and fixed to the connection portion 21a of the conductor pattern 21 by soldering. The other terminal 9 c 2 of the secondary winding 9 c of the step-up transformer 9 is connected to the connection portion 22 c of the conductor pattern 22.

  In the step-up transformer 9, each fixed portion is screwed and fixed by screws (fixing means) 29 and 30 that pass through the first screw insertion hole portion 27 and the second screw insertion hole portion 28. .

  One end of the high-voltage capacitor 14 and one end of the high-voltage capacitor 15 are connected to connection portions 21b and 21c that are close to each other in the conductor pattern 21 in the slit inner region 19E. The other end portion of the high-voltage capacitor 15 is connected and fixed to the connection portion 23a of the conductor pattern 23 existing on the right side across the slit 26 with respect to the connection portion 21b. The connection portion 21c is connected and fixed to the connection portion 25a of the conductor pattern 25 existing on the left side (a part away from the other end portion of the high-voltage capacitor 14) across the slit 26.

  As a result, the high-voltage capacitors 14 and 15 are connected to the conductor pattern 21 in the slit inner region 19E with their one end portions close to each other, and the other end portions of the capacitors 14 and 15 straddle the slit 26. In addition, they are connected to other conductor patterns 23 and 25 at portions separated from each other. Accordingly, the high-voltage capacitors 14 and 15 have a substantially V-shaped arrangement, and are fixed to the substrate 19 across the slit 26 so that the top portion thereof is located in the in-slit region 19E.

  According to the present embodiment as described above, the slits 26 are formed on the substrate 19 so as to surround the conductor pattern 21 provided with the connection portion 21a connected to the secondary winding terminal 9c1 of the step-up transformer 9. Since the secondary winding terminal 9c1 of the step-up transformer 9 is connected to the connection portion 21a, the substrate can be reduced in size while achieving good insulation between the high-voltage portion and other portions. In addition, a screw insertion hole 27 which is a fixing portion for fixing the step-up transformer 9 to the substrate 19 is provided in an in-slit region 19E surrounded by the slit 26 of the substrate 19, and the substrate is formed at the screw insertion hole 27 portion. Since the step-up transformer 9 is fixed to 19, the vertical displacement of the in-slit region 19E can be regulated by the step-up transformer 9, thereby preventing the bending of the in-slit region 19E and the step-up transformer. It is possible to prevent mechanical stress from being applied to the connecting portion between the secondary winding terminal 9 c 1 of 9 and the connecting portion 21 a of the conductor pattern 21.

  Further, according to the present embodiment, the second screw insertion hole portion 28, which is a separate fixing portion other than the first screw insertion hole portion 27, is provided in a portion other than the in-slit region 19 E of the substrate 19. Are fixed to the substrate 19 by the two first screw insertion holes 27 and the second screw insertion holes 28, so that the step-up transformer 9 can be fixed to the substrate 19 stably and integrally. Therefore, it is possible to further ensure the prevention of bending of the in-slit region 19E.

  Further, according to the present embodiment, the first screw insertion hole 27 and the second screw insertion hole 28 are provided substantially on the diagonal line of the step-up transformer 9, and the step-up transformer 9 is fixed almost on the diagonal line thereof. As a result, the step-up transformer 9 can be fixed more stably and in an integrated manner, so that the prevention of bending of the in-slit region 19E can be further ensured.

  Further, according to the present embodiment, the one end portions of the high-voltage capacitors 14 and 15 which are two high-voltage components constituting a part of the voltage doubler rectifier circuit 13 which is a magnetron driving circuit are brought close to each other in the in-slit region 19E. Since the other end portions of the two high-voltage capacitors 14 and 15 are connected to the other conductor patterns 23 and 25 across the slit 26 and separated from each other, the high-voltage capacitors 14 and 15 are connected to the conductor pattern 21. The capacitors 14 and 15 have a so-called triangular beam structure and straddle the slit 26, which is more effective in preventing the bending of the in-slit region 19E.

  In addition, according to the present embodiment, the slit 26 is formed in a substantially C shape, and the connecting portion 21a of the conductor pattern 21 is provided at the distal end portion of the in-slit region 19E. 9c1 can be separated from the portion where there is no slit 26, that is, a portion where insulation is weak, and a long insulation distance can be ensured to further improve insulation.

  In addition, according to the present embodiment, the substrate 19 is configured by dividing the substrate 19 from a substrate sheet 19A in which a plurality of substrates 19 are connected so as to be divided, and the slit 26 is formed at a site opposite to the divided side portion 19b of the substrate 19. Therefore, it is possible to prevent a force from being applied to the slit 26 when the substrate 19 is divided, and it is possible to prevent a crack at the slit 26 portion of the substrate 19.

  In addition, this invention is not restricted to the said embodiment, You may implement as changed as follows. In the case where the substrate is supported by the resin holder, the resin holder may be provided with a portion that supports the vicinity of the slit in the in-slit region. If it does in this way, the bending of the area | region in a slit can further be prevented.

Further, another fixing portion for separately fixing the transformer may be formed in the resin holder, and the transformer may be directly fixed by the other fixing portion.
Further, the means for fixing the transformer may be engaged instead of screwing, and in this case, the fixing part and the separate fixing part may be an engaging hole or an engaging protrusion instead of the screw insertion hole part.

  In the drawings, 8 is an inverter circuit, 9 is a step-up transformer (transformer), 9c is a secondary winding, 12 is a magnetron, 13 is a voltage doubler rectifier circuit (magnetron driving circuit), 14 and 15 are high voltage capacitors (high voltage components), Reference numerals 16 and 17 are high-voltage diodes (high-voltage components), 19 is a substrate, 19E is a region in the slit, 20 is a substrate device mounted with a transformer, 21 is a conductor pattern (high-voltage circuit pattern), 21a is a connection portion, 26 is a slit, and 27 is a first Reference numeral 1 denotes a screw insertion hole (fixed part), 28 denotes a second screw insertion hole (separate fixing part), and 29 and 30 denote screws.

Claims (6)

In the transformer-equipped board device of the microwave oven provided with a magnetron driving circuit which is a high-voltage circuit for driving the magnetron on the secondary side of the transformer with the transformer on the substrate,
On the substrate, a slit is formed so as to surround a high voltage circuit pattern having a connection portion connected to the secondary winding terminal of the transformer,
A fixing portion for fixing the transformer to the substrate is provided in a region surrounded by the slit of the substrate,
Connecting the secondary winding terminal to the connecting portion of the high-voltage circuit pattern;
A transformer-mounted substrate device for a microwave oven, wherein the transformer is fixed to the substrate by the fixing portion.   2. The microwave oven according to claim 1, wherein another fixing portion other than the fixing portion is provided in a portion other than the region of the substrate, and the transformer is fixed to the fixing portion and the another fixing portion. Transformer-mounted board device.   3. The transformer-mounted substrate device for a microwave oven according to claim 2, wherein the fixing part and the separate fixing part are provided substantially on a diagonal line of the transformer, and the transformer is fixed on a substantially diagonal line thereof. . One end portions of two high-voltage components constituting a part of the magnetron driving circuit are brought close to each other and connected to the high-voltage circuit pattern in the region, and the other end portions of the two high-voltage components straddle the slit and are mutually connected. The transformer-mounted substrate device for a microwave oven according to any one of claims 1 to 3, wherein the substrate is connected to another high-voltage circuit pattern at a position separated from each other. The slit is substantially C-shaped, and the connecting portion of the high-voltage circuit pattern is provided in a portion of the substrate surrounded by the slit and away from a portion without the slit. The transformer mounting board | substrate apparatus of the microwave oven as described in any one of Claim 1 to 4. The substrate is divided from a rectangular substrate sheet in which two rectangular substrates are detachably connected, and the slit is formed in a portion opposite to the divided side portion of the substrate. The transformer-mounted substrate device for a microwave oven according to any one of claims 1 to 4, wherein the substrate device is a transformer.

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