JPS60170190A - Heater - 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 The present invention relates to a microcomputer (hereinafter referred to as a "microcomputer").
The present invention relates to a control circuit and a control method for a heating device equipped with a heating device (hereinafter referred to as "heating device").

Conventional configurations and their problems In recent years, heating devices such as microwave ovens have become more functional and self-contained, and as a result, an increasing number of devices are equipped with microcomputers. In such a situation,
Due to the effects of static electricity, power supply noise, airborne noise, etc.
Due to a "runaway" caused by a malfunction in the control circuit or an error or loss of function in the program counter in the microcomputer, the power supply to the heating means suddenly starts, and the stop switch is not accepted, making it impossible to stop the heating. There have been concerns about such accidents.

FIG. 1 is a main body view of a microwave oven as an example of a heating device equipped with the microcomputer. On the front of the main body 1, there is a door body 2 which is pivotally supported so that it can be opened and closed, and an operation panel 5 which has a display part 4, etc., which is composed of keys 3 and a fluorescent display tube for inputting various commands to the control system. is provided. Reference numeral 6 denotes a start switch for instructing the start of cooking, and numeral 7 denotes a stop switch for instructing to stop cooking.

Now, FIG. 2 is a circuit diagram showing a conventional example of a control circuit for such a heating device. When a command to start cooking is input to the microcomputer 8 by pressing the start switch 6, the microcomputer 8 closes the time relay 10 and turns on the heating means 1.
1, a relay control signal R1 is output to make transistor 9, which is a switching element, conductive.

Reference numeral 12 denotes a temperature setting circuit, which is input to the microcomputer J1, and inside the microcomputer 8, the temperature setting information is converted into digital information. Reference numeral 13 denotes a temperature detection circuit, which converts the current temperature information into digital information within the microcomputer 8, compares it with temperature setting information, and controls the relay control signal R1.

The relay control signal R1 will be explained using FIGS. 3 and 4. Fig. 3 shows the normal state, and Fig. 4 shows the abnormal state. Fig. 3 shows that when the start switch 6 is pressed, a high signal is input to the microcomputer 1, and the relay control signal R is
1 to High and start heating. ! , When the reset switch 7 is pressed during heating, a high signal is input to the microcomputer input 2, and the relay control signal R1'
Set to 1LOW and stop heating.

Next, as shown in FIG. 4, due to static electricity, power supply noise, and radio wave noise, the relay control signal R1 becomes High level even though the start switch is not pressed, and heating is started. This is a runaway of the microcomputer, and even if you press the stop switch, the relay control signal R1 cannot be brought to the LOW level.It will become a continuous heating state, and if it continues for a long time, the temperature of the heating device 1 will rise and a fire may occur. This can lead to a very dangerous situation. Recently, with the advancement of automation and the use of microcomputers to perform extremely complex sequences, malfunctions due to such noise tend to increase and become a major problem.

Purpose of the Invention The present invention solves the above-mentioned conventional problem of entry. Even if the microcomputer goes out of control and the device becomes continuously heated, pressing the stop switch will definitely stop the heating and prevent a dangerous situation. The purpose is to

Structure of the Invention In order to achieve the above object, the heating device of the present invention
a heating chamber in which a hot object is placed; a switching means for supplying power to the heating means; a microcomputer for controlling the operation of the switching means; a reset circuit for returning the microcomputer to its initial state; The device is equipped with an operating section consisting of a group of switches for commanding settings, starts, and stops, and is configured to operate the reset circuit by pressing the stop switch, so that static electricity, power supply noise, and radio noise can cause the microcomputer to run out of control. However, even if it is in a continuous heating state, pressing the stop switch will ensure that the heating stops and there will be no danger.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 5, the reset circuit 14 for returning the microcomputer to its initial state has a second
A stop switch 7' is provided and interlocked with the stop switch 7. Here, the signal to the 1NiT terminal is a reset signal, and Vss is the power supply of the microcomputer. This reset signal will be explained using FIG. 6. Now, after a time T after the reset signal reaches a high level, that is, near V8B, the microcomputer returns to its initial state, that is, all outputs become LOW level.

Further, after time T2, the microcomputer operates for the first time based on the program and starts controlling each input/output terminal. Therefore, no matter what the microcomputer is doing at a certain point in time, if the reset signal goes high, the microcomputer returns to its initial state. Normally, this reset signal becomes High level when the power to the heating device 1 is fully turned on and when the power is turned off. By means of the pin provided between the second stop switch 7''ziNiT terminal and VssO, when the stop switch 7 is pressed, the second stop switch 7' is pressed, and the reset signal is output to Vss, that is, It becomes High level and the microcomputer can be returned to its initial state.As shown in Figure 7, static electricity,
The microcontroller may run out of control due to power supply noise, radio wave noise, etc.
Even if the start switch is not pressed, the relay control signal R
1 becomes High level and heating is started, if the stop switch 7 is pressed, the second stop switch 7' operates in conjunction with the stop switch 7, and the reset signal goes High. level, the microcomputer can be returned to its initial state, the relay control signal R1kLOW can be forced, and the heating can be stopped.

As described above, according to this embodiment, a second stop switch interlocked with the stop switch 7 is provided between one input terminal (i N i T ) and the other input terminal (Vss) of the reset circuit microcomputer. The extremely simple structure of providing 7' has the effect of preventing runaway of the microcomputer due to static electricity, power supply noise, radio wave noise, etc., and dangerous conditions such as continuous heating.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) It is possible to prevent the microcomputer from running out of control, for example, from a dangerous situation such as continuous heating.

(2) Many components such as capacitors were used at the input/output terminals of microcomputers as a noise countermeasure for microcomputers.
A second kill switch? 'ff: With the simple configuration of providing it, it has become possible to significantly reduce costs.

(31) (With 21, the number of parts on the control printed board was reduced, and the manufacturing process was shortened.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a microwave oven as an example of a heating device, Fig. 2 is a control circuit diagram of a conventional example, Fig. 3 is a timing chart of a conventional normal state, and Fig. 4 is a conventional abnormal state. FIG. 5 is a timing chart of the control circuit of the present invention, FIG. 6 is a timing chart of the reset signal and microcomputer output signal, and FIG. 7 is a timing chart of the control circuit of the present invention when an abnormality occurs. 6...Start switch, 7...Stop switch, 8
... Microcomputer, 9 ... Transistor (switching means), 10 ... Time relay, 11 ... Heating means, 12 ... Temperature setting circuit, 13 ... Temperature detection circuit, 14 ... ...Reset circuit, 7'...Second stop switch. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 31! ! Fig. 4 Fig. 5 Exit 1K 6 Fig. 7

Claims (1)

[Claims] A heating area for placing an object to be heated, a heating means connected to the heating chamber, a switching means for supplying power to the heating means, a microcomputer for controlling the operation of the switching means, and the microcomputer. and an operation section consisting of a group of switches for instructing the microcomputer to set, start, and stop cooking, and by pressing the stop switch, the reset circuit is fully operated. A heating device with a configuration.