JPH0318319B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an induction heater that prevents noise.

Conventional Structure and Problems Conventionally, in induction heaters, the rectifier bridge, current transformer, and noise prevention capacitor were individually attached to a housing, and the connections between them were made using lead wires.

This requires a lot of work, and in the case of a current transformer, it is necessary to take the trouble of passing it through the core loop of the current transformer. Furthermore, when connecting each component, there was a problem in that radiated noise was generated due to the loops formed by the lead wires.

Purpose of the Invention The present invention solves the above-mentioned problems, and eliminates the trouble of connecting a noise prevention capacitor, a rectifier bridge with heat dissipation fins, and a current transformer with lead wires, and also shortens the lead wires and eliminates loops. By reducing the amount of noise, the radiation noise is reduced.

Structure of the Invention In the induction heater of the present invention, a rectifier bridge having radiation fins surrounding the top and side surfaces, a noise prevention capacitor, and a current transformer are provided on the same printed circuit board, and lead wires connecting each component are eliminated. By creating a thicker and shorter pattern, the radiation noise is reduced compared to the conventional one.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an AC power supply, 2 is a power switch, 3 is a fuse, 4, 7, and 8 are noise prevention capacitors provided between the AC power supply 1 and after full-wave rectification.
5 is an aluminum heat dissipation fin that surrounds the top and side surfaces of the rectifier bridge 6; 6 is a rectifier bridge that performs full-wave rectification of the AC power source 1; 9 is a chiyoke coil for a noise filter; 10 is a smoothing capacitor; 11 is a rectifier bridge 6; A heating coil is supplied after smoothing the full-wave rectified waveform, 12 is a resonant capacitor, 13 is a switching element, 14 is a ceramic plate 1
A heating coil 11 is located on the lower surface of the shield pattern applied to the back surface of the shield pattern. Reference numeral 15 indicates a leak terminal plate that is attached to the heat dissipation fin 5 and makes electrical contact with the shield pattern 14, 16 indicates a current transformer provided on one line of the AC power line, and 17 indicates noise prevention capacitors 4, 7, 8, rectifier bridge 6, and current. A printed circuit board with a transformer 16 attached thereto, and 19 a control circuit.

In the above configuration, the current transformer 16 has a primary side 22 through which a large alternating current flows, as shown in FIG.
The next side 21 has a structure in which a voltage induced by a large AC current is generated, and the rectifier bridge 6 is equipped with heat dissipation fins 5 that cover three sides of the rectifier bridge 6, as shown in FIG. Leak terminal board 15
is attached to the heat dissipation fin 5 as shown in FIG.
When assembled as a device, the leak terminal plate 15 is in electrical contact with the shield pattern 14 painted on the back surface of the plate 18, as shown in FIG.

The current transformer 16 having the structure shown in FIG.
7, and these components are electrically connected by a patterned copper foil 17' of a printed circuit board 17. With this configuration, each component can be housed in a small area, and the loop can be made smaller than the lead wire connection, thereby reducing radiation noise.

Furthermore, in this embodiment, the noise radiated from the heating coil 11 is absorbed by the shield pattern 14, flows through the leak terminal plate 15 to the heat dissipation fin 5, and through the noise prevention capacitor 7 to the terminal of the rectifying bridge 6, thereby creating a structure in which noise can be suppressed. It's getting old.
It is obvious that the capacitor 7 is unnecessary if the lead terminal plate 15 method described above is not adopted.

Note that the rectifier bridge 6 having the heat radiation fins 5 is attached to the printed circuit board 17, and since the copper foil 17' of the printed circuit board 17 and the heat radiation fin 5 face each other, the rectifier bridge 6 flowing to the copper foil 17' of the printed circuit board 17 The magnetic flux (noise) 23 generated from the input/output current is suppressed by the heat radiation fins 5.

Also, by leaving the pattern foil of the non-current portion (24 in FIG. 5) of the copper foil 17' of the printed circuit board 17,
The copper foil 24 of the printed circuit board also has the effect of shielding noise from components mounted on the same printed circuit board 17. In addition, the copper foil 1 of the live part of the printed circuit board 17
By increasing the area of 7', heat is radiated from the mounted components through the copper foil 17', and there is a cooling effect.
Further, since the rectifier bridge 6, the noise prevention filter section such as the capacitor, etc. can be patterned, the routing of the wiring becomes constant, and variations in noise characteristics due to mass production are reduced.

Since high-current, low-frequency components are mounted on the same printed circuit board, the terminal block and lead wires can be eliminated compared to conventional induction heaters, greatly improving work efficiency and assembling the equipment. It can be made compact and lightweight.

Effects of the Invention As described above, the induction heater of the present invention has a rectifying bridge, a noise prevention capacitor, and a current transformer on the same printed circuit board, eliminates the lead wires connecting each component, and uses a thick and short printed circuit board. By creating such a pattern, radiation noise can be reduced compared to the conventional lead wire system. In addition to the above configuration, the provision of a noise prevention capacitor and heat dissipation fins surrounding the rectifier bridge even after full-wave rectification makes it possible to significantly reduce radiation noise (about 70 decibels in actual measurements).
It is also possible to use a resin case for the heater housing, which makes it possible to reduce the overall weight and improve workability in assembling parts. It is. Furthermore, since power circuit components such as a rectifier bridge, current transformer, and noise prevention capacitor are provided on the printed circuit board, noise near the commercial AC power frequency can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an induction heater showing one embodiment of the present invention, Fig. 2 is a perspective view of the same current transformer, and Fig.
4 is a sectional view of the state of contact between the shield pattern and the leak terminal plate, and FIG. 5 is a sectional view of the heat radiation fin portion. 4, 7, 8... Noise prevention capacitor, 5... Heat radiation fin, 6... Rectifier bridge, 14... Shield pattern, 15... Leak terminal board, 16... Current transformer, 17... Printed circuit board.

Claims (1)

[Scope of Claims] 1. A rectifier bridge having heat radiation fins that performs full-wave rectification of AC power, a heating coil on the lower surface of the plate to which the full-wave rectified waveform of the rectifier bridge is supplied after smoothing, and one line of the AC power line. a current transformer installed in the
A noise prevention capacitor is provided between the AC power source and after full-wave rectification, and the rectifier bridge, current transformer, and noise prevention capacitor are provided on the same printed circuit board, and each of these components is connected to the patterned copper foil of the printed circuit board. An induction heater provided with heat radiation fins that are electrically connected and surround the top and side surfaces of the rectifying bridge. 2. The induction heater according to claim 1, wherein the radiation fins of the rectifier bridge are electrically contacted with the plate via the leakage terminal plate.