KR20000043265A - Method for detecting no-load of microwave oven - Google Patents

Abstract

PURPOSE: A detection method of no-load of a microwave oven is provided to secure stability of a microwave oven without extra cost for producing by detecting no-load state by the decision of a microcomputer according to the operation of a system at an initial driving of a microwave oven. CONSTITUTION: A fan motor is stopped for time F if time T is elapsed after deciding the elapse of time T that is the operation time of a magnetron at an initial driving of a microwave oven. The switching of a contact point of a cavity thermocouple while the fan motor is stopped is decided. Herein, no-load state of a microwave oven is decided easily by deciding the existence of power supply flowed in from the cavity thermocouple. The stability of a system is obtained. The increase of producing cost of a system is restrained because any additional device is not needed.

Description

No-load detection method of microwave oven

The present invention relates to a microwave oven, and more particularly, a microwave oven capable of detecting a no-load state at the initial operation of the microwave oven at the discretion of the microcomputer according to a system operation, thereby ensuring the stability of the microwave oven without increasing the unit price. It relates to a no-load detection method of.

In general, a microwave oven is composed of a device for generating a high temperature by using a high voltage. There is a magnetron as a key apparatus constituting such a construction, which results in the frequency of the high frequency generator 2.45GH _Z as in need of 4000V, the water molecules contained in food polarity switching by the magnetic field to be performed at a high speed ever. In addition, the self-temperature increase effect is obtained by the water molecules rapidly polarizing by this magnetic field, and many functions have been developed for easy cooking at home using the principle of the temperature increase effect. In addition, due to the high voltage high temperature driving method of the microwave oven, safety is required, and a number of safety devices are installed therefor.

Then, the configuration of the above-described general microwave oven is as follows.

1 is a view showing a part of the configuration of the microwave oven. Referring to FIG. 1, the conventional microwave oven uses a commercially-available commercial power source through the cavity summer 70 to shut off the power when the temperature of the high-room chamber is higher than a predetermined temperature when the system is operated, and the cavity summer 70 during normal operation. It consists of a low voltage transformer 71 for converting to a predetermined low voltage, and a system controller 72 for driving the system using a constant low voltage obtained through the low voltage transformer 71, the system controller 72 is the overall control system A high voltage transformer for applying a high voltage to the magnetron under the control of the microcomputer 80 for controlling, the relay controller 81 for controlling the power supply according to the voltage output from the microcomputer 80 and the system controller 72. 73).

In addition, a fuse 74 is connected to the front end of the cavity summer 70 to cut off the power of the system when an overvoltage or overcurrent occurs, and a power plug 75 for receiving power to the front of the fuse 74. Is connected to the low voltage transformer 71 is connected to the stable switch 76 is determined whether the power cut off according to the opening and closing of the door when the microwave oven is powered.

In addition, the system control unit 72 has a cavity lamp 77 for turning on the lamp in the chamber inside when the microwave oven is in operation, a gear motor 78 for turning the rotating plate to cook the food evenly, and food confection cooking. Or the fan motor 79 is used to lower the temperature of the electrical room is connected.

Hereinafter, the operation of the conventional microwave oven according to the above configuration will be described.

First, when commercial power is applied through the power plug 75, the commercial power is transmitted to the cavity summer 70 through the fuse 74. At this time, the cavity summer 70 transmits power due to continuous contact if it does not exceed a certain temperature of the chamber. Then, the power transmitted through the cavity summer 70 is supplied in parallel to the stable switch 76 and the low-voltage transformer 71, the power applied to the stable switch 76 is depending on whether the door is opened or closed. Power that is switched and applied to the low voltage transformer 71 induces a magnetic force generated in the primary coil to the secondary coil to generate a predetermined low voltage.

In addition, the low voltage generated from the secondary side of the low voltage transformer 71 is applied to the system control unit 72 and used for the rated control, which controls the relay control unit 81 according to the control signal of the microcomputer 80. Will be driven. In addition, the driving signal of the relay controller 81 drives the cavity lamp 77, the gear motor 78, and the fan motor 79 so that the food can be cooked evenly, and the cooking process can be confirmed from the outside. To make it work.

In addition, the fan motor 79 is a magnetron (not shown) driven at the time of cooking to suppress the temperature rise of the electric compartment and is operated together with the driving of the magnetron at a constant speed. Therefore, the outside air of the microwave oven is introduced into the electric compartment to perform air cooling.

As a result, the cavity summer 70 provided in the microwave is a predetermined safety device, and when the temperature of the chamber is higher than the reference value, the contact point is switched off to cut off the power applied to the system, but the chamber is not loaded. In one case, it is a very long time until the contact point of the cavity summer is switched, and a large number of components of the electrical equipment chamber are damaged during this time. The breakage of such components is caused by frequent on / off operation of the cavity summer, that is, the operation of the magnetron due to the off operation of the cavity summer at a no load and the on-contact of the cavity summer after a certain time, and the heat generated from the cavity summer. Due to the on / off contact switching time is shortened due to the continuous overheating caused by component breakage and fire, there is a problem that the need for a safety device is particularly required.

The present invention was created to solve the above problems, the object of the present invention is to ensure the safety of the system by detecting the no-load state of the microwave oven on the basis of the determination of the microcomputer without a separate circuit and device provided In addition, the present invention provides a method for detecting a no-load of a microwave oven in which a unit cost increase is suppressed.

The microwave no-load detection method according to an aspect of the present invention for achieving the above object includes a time-lapse determination process for determining whether the operating time of the magnetron has elapsed T time at the time of initial driving of the microwave; A fan motor stopping step of stopping the fan motor for F hours when the T time elapses in the time elapsed determination process; And a power detection determination process for determining whether the contact point of the cavity summer is switched during the fan motor stop process.

1 is a view for explaining the main functions of the conventional microwave oven.

Figure 2 is a block diagram showing an embodiment of the present invention.

3 is a flowchart for describing an operation state of the microcomputer of FIG. 2.

<Explanation of symbols for main parts of drawing>

10: micom 12: memory

14 timer 16: control unit

20: relay unit 22: fan motor

30: Cavity Summer M: Magnetron

HVT: High Voltage Transformer D: Diode

R: resistance

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing the main configuration of a microwave for explaining the present invention. FIG. 3 is a flowchart for explaining the microcomputer operation of FIG. 2. First, the microwave oven referring to FIG. 2 includes a microcomputer 10 for determining whether there is power AC flowing through the cavity summer 30, the cavity summer 30, and detecting a no-load state of the system. A relay unit 20 for supplying power to a plurality of driving elements by receiving the control signal of 10, a fan motor 22 and a high voltage transformer (HVT) connected to the relay unit 20, and It is composed of a magnetron (M) for receiving a high voltage from the high-voltage transformer (HVT) to perform cooking and a display unit (18) for displaying the determination of the microcomputer (10).

In addition, the microcomputer 10 stores a controller 16 that determines whether power is supplied through the cavity summer 30 through the first port P1, and a predetermined program for detecting a no-load state of the microwave oven. It consists of a memory 12 and a timer 14, the first port (P1) of the control unit 16 is provided with a reverse diode (D) and a pull-down resistor (R).

Hereinafter, the operation of the present invention according to the above configuration will be described.

For example, after the food is placed in the chamber of the microwave (step 1), when a cooking start key and a cooking function key (not shown) are input from the user, the microcomputer 10 detects a key signal currently input. . The key signal is decoded and compared with data stored in the memory 12, and a control signal for performing a cooking function is output according to the compared result. Then, the relay unit 20 performs an on / off operation according to a cooking process based on the control signal output from the microcomputer 10. This applies power to the high voltage transformer (HVT) to drive the magnetron (M), or controls the operation of the fan motor 22 (step 2).

At this time, the microcomputer 10 detects power flowing through the cavity summer 30. For example, the microcomputer 10 detects a predetermined power toward the anode side of the reverse diode D provided in the first port P1 of the controller 16. It is to judge the presence or absence of power by applying voltage. That is, when the power source AC is introduced through the cavity summer 30, the voltage through the cavity summer 30 is applied to the cathode side of the diode D, and then through the first port P1 of the controller 16. The controller 16 determines that the predetermined voltage (voltage smaller than the power source AC) that is supplied cannot be conducted to the pull-down resistor R through the diode D. Of course, when the cavity summer 30 is switched off and thus the power source AC is not supplied to the diode D, a predetermined voltage through the first port P1 flows to the pull-down resistor R, which is controlled by the controller 16. Is to be detected.

Therefore, when the control unit 16 detects the power AC flowing through the cavity summer 30, it is determined whether the minimum time for turning off the cavity summer when the predetermined time T-no load elapses from the timer 14. Judgment (step 3). If it is determined in step 3 that the time T has elapsed, the controller 16 transmits the fan motor 22 stop signal to the relay unit 20.

Then, the temperature of the chamber is raised up to a predetermined interval, and the cavity summer 30 is not switched off by the food placed in the chamber. At this time, the controller 16 recognizes that the time data supplied from the timer 14 has passed a predetermined time F, and then outputs a predetermined voltage to the first port P1. In addition, since the conduction state of the output voltage is detected, since the voltage is not conducted as the cavity summer 30 is not switched off, the controller 16 is currently being supplied to the first port P1. (Step 5). Therefore, the microcomputer 10 controls the normal microwave cooking function to be performed according to the key input signal from the user (step 6).

On the other hand, if the user wants to cook without placing food in the chamber, the microwave controls the fan motor 22 and the magnetron M to be driven to perform a normal cooking function in an initial state (step 1 , Step 2). The microcomputer 10 determines whether the time T has elapsed (step 3). When the predetermined time T has elapsed in step 3, the control unit 16 outputs the fan motor 22 stop signal to the relay unit 20 (step 4). In addition, the timer 14 determines whether a predetermined time F has elapsed, and when the time F has elapsed, a predetermined voltage is supplied to the first port P1 of the controller 16.

At this time, since the food is not placed in the chamber, the cavity summer 30 is switched off so that the voltage supplied through the first port P1 passes through the anode side of the diode D. It flows into the resistor (R). This causes the controller 16 to determine that the cavity summer 30 is off-switched, and determines that it is in a no-load state (step 5).

Thus, the microcomputer 10 displays a warning message according to a state in which the current food is not placed through the display unit 18 (step 7).

According to the present invention described above, after the predetermined time (T) at the time of initial driving of the microwave oven, the fan motor is turned off for a certain time (F) to determine the presence or absence of the power flowing from the cavity summer, thereby determining the no-load state of the microwave oven. As it can be easily determined, the stability of the system is secured, and an additional device is not required, and thus the manufacturing cost of the system can be suppressed.

As mentioned above, although this invention was demonstrated concretely by the above-mentioned Example, the no-load detection method of the microwave oven of this invention is not limited to this, The deformation | transformation and improvement are possible within the normal knowledge of a person skilled in the art.

Claims (2)

In the no-load detection method of the microwave oven, A time-lapse determination process for determining whether the operation time of the magnetron has elapsed T time at the time of initial driving of the microwave oven (step 3); A fan motor stop step (step 4) of stopping the fan motor for an F time when the T time elapses in the time elapsed determination process (step 3); And And a power detection determination process (step 5) for determining whether the contact point of the cavity summer is switched during the fan motor stop process (step 4). 2. The method of claim 1, wherein the T time is a minimum time that the cavity summer (30) is switched off in the no-load state of the microwave oven.