JPH0455438Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to the improvement of high-frequency heating devices such as microwave ovens, and more specifically, uses an inverter circuit in the power supply device and generates high-frequency power by the inverter circuit. The present invention relates to an improvement of a high-frequency heating device configured to boost the voltage using a step-up transformer to drive a magnetron.

<Prior art> Figure 2 is a basic electrical circuit diagram of a conventional high-frequency heating device, in which 1 is a clear ocean current, 2 and 3 are a chiyoke coil and a smoothing capacitor that constitute a smoothing circuit, 4,
5, 6, and 7 are resonant capacitors that constitute the inverter circuit, a step-up transformer for driving the magnetron, a switching element, and a diode; 8 is a control circuit that controls the driving of the switching element 6; 9 is a secondary winding of the step-up transformer 5; This is a winding for heating the filament of the magnetron 12. Reference numerals 10 and 11 are high-voltage capacitors and high-voltage diodes that constitute a magnetron drive circuit. And 13 is a high voltage choke that prevents excessive rush current.

The filament heating winding 9 is wound around the magnetron driving transformer 5 and is switched by the switching element 6 to supply filament heating power.

The filament heating power supplies Nf/Np·Vp=Vf by the voltage of the primary winding a of the step-up transformer 5 for driving the magnetron.

Nf: Number of filament heating windings (T) Np: Number of primary windings (T) Vp: Primary winding voltage (V) Vf: Filament voltage (V) <Problems that the invention attempts to solve> Filament heating power Since a large amount of power is required when the magnetron starts oscillating, extra power is supplied to heat the filament even when the magnetron oscillates in a stable state. Therefore, there were problems such as deterioration of the filament wire of the magnetron 12 and poor efficiency of the magnetron 12.

<Issues to be solved> High-voltage choke 1 installed in the magnetron drive circuit
3 as a primary winding, and a filament heating control transformer 15 having a secondary winding as a filament heating control coil 14 provided in a filament heating circuit that heats the filament of the magnetron 12. Try to reduce the filament heating voltage.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a basic electrical circuit diagram of the high-frequency heating device of the present invention, and the same parts as in the conventional example are given the same reference numerals for explanation.

The feature of this invention is that the high-pressure chain yoke 13 is
A filament heating control transformer 15 is provided whose secondary winding is the filament heating control coil 14 provided in the filament heating circuit, and the filament heating voltage is reduced in accordance with the output voltage of the high-voltage yoke 13. be.

The voltage induced in the filament heating control coil 14, which is the secondary winding of the filament heating control transformer 15, by the voltage generated in the high voltage yoke 13 is Vf'=Nf'/Nco×Vco.

Nf': Number of windings in the heating control coil (T) Nco: Number of windings in the high-voltage choke (T) Vco: High-voltage choke voltage (V) Vf': Induced voltage in the heating control coil (V) Then, the magnetron 12 oscillates. Sufficient filament heating power is supplied until the start of heating, and at the same time the magnetron 12 oscillates and current flows through the magnetron 12, an induced voltage is generated in the heating control coil 14.
If the wires are connected as shown in FIG. 1 so that Vf' is generated and the voltage Vf of the filament heating winding 9 of the step-up transformer 5 is reduced, sufficient filament heating power can be supplied until the magnetron 12 starts oscillating. , when the magnetron 12 oscillates, excess filament heating power can be reduced.

<Effects> According to the present invention, excess filament power during magnetron oscillation can be reduced to prevent filament deterioration and improve magnetron efficiency.

[Brief explanation of the drawing]

FIG. 1 is a basic electrical circuit diagram of the high frequency heating device of the present invention, and FIG. 2 is a conventional basic electrical circuit diagram. Symbols: 13...high-voltage choke, 14...filament heating control coil, 15...filament heating control transformer.

Claims (1)

[Claims for Utility Model Registration] A clear stream smoothing circuit that smoothes a commercial power supply to produce a clear stream power supply, an inverter circuit composed of a step-up transformer for driving a magnetron, a resonant capacitor, a diode, a semiconductor switching element, etc., and the semiconductor switching device. In a high-frequency heating device comprising a drive circuit for driving an element, a control circuit for controlling the drive circuit, a magnetron drive circuit, and a magnetron, a high-voltage chiyoke provided in the magnetron drive circuit is used as a primary winding, and a filament of the magnetron is used as a primary winding. A filament heating control transformer whose secondary winding is a filament heating control coil provided in a filament heating circuit for heating the filament is provided, and the filament heating voltage is reduced in accordance with the output voltage of the high-voltage yoke. heating device.