JPS60180088A - Electromagnetic induction cooking device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to an electromagnetic induction cooker.

(b) Prior art The inverter circuit of a conventional electromagnetic induction cooker was published in Japanese Patent Application Laid-Open No. 57
As shown in Publication No. 165992, once a trigger signal is input, oscillation starts, and after that, the oscillation detection circuit detects the oscillation state of the inverter circuit, and the self-excited oscillation circuit causes the inverter circuit to self-excited oscillation. Let me do it.

However, since the trigger signal for oscillation and startup of the inverter circuit is asynchronous, the switching element of the inverter circuit is in the OFF state, and when the trigger signal is input, abnormal noise may be generated from the load such as a pot or the switching element may be destroyed. Therefore, a circuit for stopping the starting circuit is required, making the entire circuit complex and expensive.

(C) Objective The present invention is intended to eliminate the above-mentioned drawbacks.

2) Structure In the present invention, the positive input terminal on the arithmetic comparator side is used as the input terminal for the half-wave rectified AC voltage Vcc of the AC power supply (1) via the half-wave rectifying diode, and the negative input terminal is used as the input terminal for the half-wave rectified AC voltage Vcc of the AC power supply (1). Voltage VD,
, a pulse of a predetermined width is generated from the output terminal of the arithmetic comparator (151) at predetermined time intervals, and the arithmetic comparator (151)
Connect a capacitor (21+) and a resistor (221+) to the output terminal of 19.
Connect the differentiating circuit (c) consisting of the following, and connect the negative side input terminal of the arithmetic comparator (to) to the negative side input terminal of the arithmetic comparator (to), and connect the positive side input terminal of the arithmetic comparator (to) to the inverter circuit (5). A constant diode (5) connected to the smoothing capacitor a@, clips the potential waveform at the positive input terminal of the arithmetic comparator.
) is connected to the positive input terminal.

(E) Embodiment An embodiment of the present invention will be explained based on the drawings. FIG. 1 shows an embodiment of the electromagnetic induction cooker according to the present invention, in which (1) is an AC power supply, (2) is a transformer, (3) is a rectifier circuit, (4) is a constant voltage circuit, and (5) is a In the inverter circuit, (6) is a drive circuit, (7) is an output adjustment circuit, and (8) is a starting circuit.

Since the inverter circuit (5) is already known, we will not discuss it in detail, but it includes a choke transformer (9), a smoothing capacitor αe, a heating coil (lυ), and a resonance capacitor (L2).
, damper diode Q3), switching transistor 791
It consists of 50 verses.

The configuration of the starting circuit (8) is as follows. Arithmetic comparator 0
The positive input terminal of 9 is connected to the connection point of resistors (16) and (17), and connected to the transformer (2) via a half-wave rectifier diode as the input of these resistors (16) (lη). Connect the side input terminal to the connection point of resistor (19(2(II),
The output terminal C of these resistors (connected as inputs to the constant voltage circuit (4), arithmetic comparator Q5) is connected to a differentiating circuit consisting of a capacitor (21) and a resistor (2).

Connect the negative input terminal d of the arithmetic comparator (goods) to the differential circuit (c), connect the positive input terminal to the connection point e of the resistor C2 (c26), and use it as an input to the resistor +25) (26). Connect to point f of the inverter circuit (5). Note that (5) is a constant voltage diode, and (281 is a resistor).

The operation of the present invention having the above configuration will be explained based on the timing chart of FIG. The potential at the positive input terminal a of the arithmetic comparator (151) is half-wave rectified by the half-wave rectifier diodes a, as shown in Figure 2 (1) A, and the potential at the negative input terminal A is as shown in the figure. Therefore, the potential at the output terminal C of the arithmetic comparator becomes as shown in FIG. 2 (2).

When the potential at the output terminal C of the arithmetic comparator αω is at the L level, the capacitor (21) of the differentiating circuit (c) is connected to the resistor (2
a.

It is charged to a constant power supply voltage V□ through the arithmetic comparator (151), and when the potential at the positive input terminal a of the arithmetic comparator (151) becomes higher than the potential at the negative input terminal A, an output signal is output from the output terminal C. However, the potential at output terminal C rises to constant power supply voltage VDD.

Therefore, the potential at the negative input terminal d of the arithmetic comparator (24) rises instantaneously as shown in FIG. 2(3)A. However, since the potential at the output terminal C of the arithmetic comparator α5) is at H level, the capacitor eυ resistance (2a
(A closed circuit is formed by 281, and the capacitor (2I)
The charge is discharged through the resistor (22) (2a), and the potential at the negative input terminal d of the arithmetic comparator (24) instantly drops to the constant power supply voltage vl,n.

Next, when the potential at the positive input terminal a of the arithmetic comparator becomes lower than the potential at the negative input terminal a, the arithmetic comparator α
The potential at output terminal C of No. 9 becomes L level. When the potential at the output terminal C of the arithmetic comparator a9 becomes L level, the resistor (2z), the capacitor (21J), and the arithmetic comparator (15
A charging current flows to the ground side of the arithmetic comparator (24), and the potential at the negative input terminal d of the arithmetic comparator (24) flows to the grounding side of the arithmetic comparator (Q), since the electrical charge of the capacitor (2υ) is zero. It becomes equal to the grounded voltage, and drops instantly as shown in Figure 2 (3) A, but immediately rises to the constant power supply voltage DD.In this way, the differentiator circuit @ is connected to the AC power supply. (
A trigger wave is applied to the negative input terminal of the arithmetic comparator 04) every half wave of 1).

-3, the potential at the positive input terminal e of the arithmetic comparator will be described next. The potential at point f of the inverter circuit (5) is as shown in Figure 2 (5) when the inverter circuit (5) is oscillating.
), but when the inverter circuit (5) stops oscillating, it is smoothed by the smoothing capacitor (00). The potential at point f of the inverter circuit (5) is clipped by the constant voltage diode (2'0) at the positive input terminal e of the arithmetic comparator (24), as shown in Figure 2 (3). .

Therefore, as soon as the potential at the positive input terminal e of the arithmetic comparator becomes higher than the potential at the negative input terminal d, the arithmetic comparator (24) is activated as shown in FIG. 2 (4). A pulse is emitted.

That is, when the inverter circuit (5) is oscillating, the starting pulse is not issued from the starting circuit (8), but only when the oscillation is stopped.

(F) Effect In the present invention, as described above, when the inverter circuit (5) is oscillating, the starting pulse is not issued from the starting circuit (8) and the inverter circuit (5) stops oscillating. However, since the oscillation state of the inverter circuit (5) is detected by the smoothness of the smoothing capacitor of the AC power supply (1), there is no need for a special oscillation detection circuit like in the past. First, the entire circuit is simple.

[Brief explanation of drawings]

FIG. 1 is an overall circuit diagram of an electromagnetic induction cooker according to the present invention;
FIG. 2 is a timing chart of the present invention. <1)...AC power supply, (5)...inverter circuit, (8)...starting circuit. Applicant: Sanyo Electric Co., Ltd. and 1 other representative: Patent attorney: Shizuo Sano

Claims (1)

[Claims] (1) An inverter circuit is formed of a smoothing capacitor, a damper diode, a transistor, a resonant capacitor, and a heating coil for smoothing the AC power waveform, and when the inverter circuit is in oscillation operation or stopped, the AC power waveform is determined by the smoothing capacitor. An electromagnetic induction cooking device characterized in that a starting pulse is emitted from a starting circuit when the inverter circuit stops oscillating operation by detecting a smoothness of .