JPS592155B2 - induction heating cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an induction heating cooker equipped with an induction heating coil below a cooking plate made of a flat non-magnetic material. The present invention aims to provide a cooking display device.

In general, induction heating cookers are equipped with a ceramic cooking plate on the top of the main unit for placing cooking utensils, and a high-frequency current is supplied to the induction heating coil installed below the cooking plate. A pot placed in an electromagnetically coupled position is heated by the eddy current loss generated.

At this time, the cooking surface of an induction heating cooker is flat and warm, and unlike the top surface of a gas stove, it is safe and free of flames, but on the other hand, the user cannot directly see whether or not it is being heated. It was hot. For this reason, conventional induction heating cookers are equipped with a protection circuit to prevent them from operating with small objects such as spoons and knives, but if the small objects are large or a metal container made of iron is placed, There was a risk of heating and accidents such as burns. Furthermore, in the past, although a power-on display was provided, it was unclear whether or not the heating load was actually being heated. The structure of a conventional induction heating cooker will be explained below with reference to FIG. 1 and FIG.

In Fig. 1, 1 is the induction heating cooker main body, 2 is the main body 1
It is a flat cooking plate that constitutes the top plate and the surface on which cooking utensils are placed, and is made of a non-magnetic material such as ceramic. 3 is the power adjustment knob, 4 is the power switch,
Reference numeral 5 indicates an indicator lamp for indicating power-on, and reference numeral 6 indicates a plug for commercial power supply.

FIG. 2 shows a power supply circuit of the induction heating cooker shown in FIG. 1, and its circuit configuration will be explained together with its operation.

First, when the power switch 4 is closed, the commercial power supplied through the plug 6 is transferred to the capacitor □, the thyristor 8,
9, 10, 11, current increase rate suppression inductor 12a,
12b) It is sent to a frequency converter composed of a commutating capacitor 13 and an induction heating coil 14. If each thyristor is fired so that the firing order of the thyristors is 8 → 9 → 10 → 11 or 9 → 8 → 11 → 10 depending on the polarity of the power supply, the thyristors are placed in a position where they are electromagnetically coupled to the heating coil 14. The placed pot 15 is heated by the generated eddy current loss, and so-called induction heating becomes possible. Note that 5 is an indicator lamp when the power is turned on, and it is only turned on when the power switch 4 is turned on. As is clear from the above description, in the conventional configuration, it was not possible to display the presence or absence of the pot 15.

Furthermore, even if small items (knife, spoon), etc. were placed, it was not possible to determine whether an input was being entered. Furthermore, if a small object is placed on the converter, the converter may stop operating if the input current decreases, but it is impossible to determine whether or not the input to the small object has actually stopped. Therefore, in the event of an accident such as a burn, or during use, the operating state cannot be determined, creating a sense of anxiety and making the device inconvenient to use. The present invention has been made in view of the above-mentioned conventional drawbacks, and one embodiment of the present invention will be described below with reference to FIG. 3.

Note that the same numbers as in the conventional configuration described above will be used, and the explanation will be omitted.

First, the display circuit includes a DC power supply circuit consisting of a power rectifying diode 16, a current limiting resistor 17, a constant voltage element 18, and a smoothing capacitor 19, a current limiting resistor 20, a display element 21 (light emitting diode in the embodiment), transistor 22
, a base current limiting resistor 23, resistors 25 and 26 that provide a reference voltage for the programmable unijunction transistor 24 (hereinafter abbreviated as PUT), a base bias resistor 27 of the transistor 22, a diode 28, and a capacitor 2.
9, resistor 30, transistors 31, 32, 33, diode 34, resistors 35, 36, 37, 38, 39, 40,
an oscillation circuit consisting of 41 and 42, a magnetic switch 43,
It consists of a thyristor gate circuit 44 of the converter.

The display of the operating state in this circuit is configured such that when the pot 15 is placed, the display element 21 lights up continuously, and when the pot 15 is not placed, the display element 21 blinks.

That is, when the power switch 4 is turned on and the pot 15 is not present, the transistor 32 is turned on and the transistor 31 is also turned on, so that a charging current flows through the capacitor 29 via the resistor 30. (At this time, the transistor 33 is in the on state and no current is supplied to the base of the transistor 22.) Therefore, the potential of the capacitor 29 is the same as that of the resistor 25.
When the potential becomes higher than the voltage divided by PUT 26, the PUT 24 becomes conductive, leading the transistor 22 to conduct through the resistor 23, and the light emitting diode 21 blinks. Next, when the pot 15 is placed, the transistors 32 and 31 are turned off, and the transistor 33 is turned off, and the base current of the transistor 22 is supplied through the resistor 38, the diode 28, and the resistor 23, and the display element 21 lights up continuously. Let's die. As described above, after the power is turned on, if the pot 15 is present, the converter lights up continuously, and if the pot 15 is not present, it repeats blinking to display the operating state of the converter. In addition, if an input current detection circuit is installed to protect small items such as knives from accidents such as burns, and a means is added to open circuit A and stop the gate circuit 44 when the input current is below a certain level, the knife If the converter continues to operate even though there are small items such as, you can tell that it is heating up by continuously lighting it. Further, if the converter stops due to a small object hitting the converter, the display element 21 can repeatedly blink to indicate that induction heating is not being performed. As is clear from the above explanation, by displaying not only whether induction heating is being performed but also whether the power switch is turned on, it is possible to prevent items from being placed on the cooking plate by mistake. It is possible to provide a highly safe induction heating cooker that prevents burns and the associated risks of burns, and also has the advantage of being able to display the heating load status and power-on status using the same display element. It is something that produces fruit.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a general induction heating cooker, FIG. 2 is a power supply circuit diagram thereof, and FIG. 3 is a power supply circuit diagram of an induction heating cooker showing an embodiment of the present invention. 2... Cooking plate, 4... Power switch, 14... Heating coil, 15... Pan, 21... Display element, 43...Magnetic body switch.

Claims (1)

[Claims] 1. A magnetic path formed by a cooking plate made of a flat non-magnetic material, an induction heating coil installed below the cooking plate, a power switch, and cooking utensils placed on the cooking plate. a magnetic switch that is opened and closed by the
An oscillator that is brought into operation when the power switch is turned on, receives the magnetic switch as an input, causes the display element to light up continuously when the magnetic switch is closed, and causes the display element to flash when the magnetic switch is opened. An induction heating cooker comprising: