KR100751793B1 - Driving circuit of microwave range and driving method thereof - Google Patents

Abstract

A method and a circuit for driving a microwave oven are provided to prevent a fire by detecting overheat from a low voltage converter and stopping an operation of the microwave oven. A circuit for driving a microwave oven includes a low voltage transformer(10), a rectifier(12), a thermistor(18), a constant voltage unit(14), and a microcomputer(16). The low voltage transformer receives a commercial AC voltage and generates a low voltage. The rectifier rectifies a DC voltage from an AC voltage dropped through the low voltage transformer. The thermistor is arranged to be close to the rectifier. A resistance of the thremistor is varied by a peripheral temperature such that the rectified voltage is varied. The constant voltage unit generates a constant voltage from the DC voltage outputted from the thermistor. The microcomputer receives the constant voltage and controls the microwave oven. The microcomputer determines an overheat state of the rectifier based on a current variation of the DC voltage, which is outputted from the constant voltage unit.

Description

The driving circuit of the microwave oven and its driving method {DRIVING CIRCUIT OF MICROWAVE RANGE AND DRIVING METHOD THEREOF}

1 is a perspective view showing a general microwave oven.

2 is a circuit diagram illustrating a low voltage conversion unit of a general microwave oven.

3 is a circuit diagram illustrating a low voltage converter of a driving circuit of a microwave oven according to the present invention.

4 is a flowchart illustrating a method of driving a microwave oven according to the present invention.

   -Explanation of symbols for the main parts of the drawings-

10: low pressure transformer

12: rectifier

14: constant voltage section

16: micom

18: thermistor

20: heat sink

The present invention relates to a driving circuit of a microwave oven and a driving method thereof, and more particularly, a heat sink is added to a low voltage converter to generate a low voltage used in a control circuit of a microwave oven to prevent overheating and to prevent a low voltage converter. The present invention relates to a driving circuit of a microwave oven and a method of driving the same so as to stop the driving of the microwave oven by detecting an overheat generated in the to prevent damage and fire of the control circuit.

Various kinds of apparatuses have been proposed to date as heating apparatuses for heating foods. The most primitive heating device is a container in contact with the heat source integrated, it is possible to cook the food by putting the contents to be cooked in such a container and applying heat.

In addition, many types of cooking apparatuses that use electric energy directly or indirectly have been developed. As an example, a microwave oven using microwaves as a heating source may be mentioned. A microwave oven is a cooking apparatus that generates microwaves using electricity to infiltrate a cooking object and heat the cooking object by causing molecular motion therein.

In such a microwave oven, according to the intention of the user, various conditions such as output and cooking time of the microwave are appropriately adjusted according to the intention of the user. In addition, the microwave oven provides a user convenience by displaying the user's operation state and the operation state according to the number or letters.

In general, a microwave oven is a device for heating / cooking food using microwaves, and as shown in FIG. There is a key input unit 9 for inputting a cooking menu, a cooking time, an output level, and a start of cooking, and a door 3 for opening and closing the cooking chamber 5 is hinged to one side of the main body 1. .

In order to generate microwaves in such a microwave oven, a high voltage is required, while a low voltage power is required in a control circuit for performing control according to cooking conditions input through a key input unit. The conversion unit is provided.

2 is a circuit diagram illustrating a low voltage converter of a general microwave oven.

As shown here, a low voltage transformer for receiving a commercial AC power and stepping down to a low voltage, a rectifying unit for rectifying the AC power stepped down through the low voltage transformer into a DC power source, and stabilizing the DC power rectified in the rectifying unit to stabilize the constant voltage. It is composed of a constant voltage unit for generating, and a microcomputer that receives the stable voltage output from the constant voltage unit to control the operation of the microwave oven.

Through the low voltage converter configured as described above, the commercial AC power is input to receive a stable DC power of a low voltage required by the control circuit to perform various controls.

However, since the low voltage transformer, rectifier and constant voltage of the low voltage converter generates a lot of heat, if the heat generated efficiently is not cooled, the peripheral control circuit may be damaged, resulting in malfunction and fire risk due to overheating. There is a problem.

The present invention was created to solve the above problems, an object of the present invention is to add a heat sink to the low voltage conversion unit for generating a low voltage used in the control circuit of the microwave oven to prevent overheating as well as low voltage conversion unit The present invention provides a driving circuit of a microwave oven and a method of driving the same so as to stop the driving of the microwave oven by detecting an overheat generated in the to prevent damage and fire of the control circuit.

The present invention for achieving the above object is a low-voltage transformer for stepping down to a low voltage to receive a commercial AC power, a rectifying unit for rectifying the AC power stepped down through the low-voltage transformer to a DC power, and installed in close proximity to the rectifier Inputs the thermistor for varying the voltage of the DC power rectified by the rectifier, the constant voltage part for generating the constant voltage by stabilizing the DC power output from the thermistor, and the stable voltage output from the constant voltage part. In addition to controlling the operation of the microwave oven, it is characterized by including a microcomputer to control the occurrence and operation of the error by determining the overheating state of the rectifier based on the change in the current value of the DC power output from the constant voltage unit.

The present invention is characterized in that the heat sink is installed around the rectifying portion.

In addition, according to the present invention, a method of driving a microwave oven includes measuring a current value of an input low voltage, calculating a temperature value corresponding to the measured current value, and whether the calculated temperature value exceeds a set reference temperature. And determining, and generating an error when the reference temperature is exceeded and stopping the operation of the microwave oven.

The present invention made as described above determines the overheat state of the low voltage converter for generating a low voltage used in the control circuit of the microwave oven through the change in the current value by the thermistor installed in the DC power input terminal generates an error in the event of overheating Stop the microwave oven to prevent accidents.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings, and the same parts as in the prior art use the same reference numerals and names. In addition, the present embodiment is not intended to limit the scope of the present invention, but is presented by way of example only and those skilled in the art will be capable of many modifications within the technical spirit of the present invention.

3 is a block diagram illustrating a low voltage conversion unit of the microwave driving circuit according to the present invention.

Low-voltage transformer for stepping down to low voltage by receiving commercial AC power, Rectifier for rectifying AC power stepped down by low-voltage transformer to DC power, and rectifier is installed in close proximity to the rectifier to change the resistance value according to the ambient temperature In addition to controlling the operation of the microwave oven by receiving a thermistor for varying the voltage of the rectified DC power supply, a constant voltage unit for generating a constant voltage by stabilizing the DC power output from the thermistor, and a stable voltage output from the constant voltage unit. It includes a microcomputer to control the occurrence and operation of the error by determining the overheating state of the rectifier based on the change of the current value of the DC power output from the constant voltage unit.

In addition, a heat sink is installed around the rectifying part to dissipate heat generated to prevent overheating.

Therefore, when measuring the current value of the DC voltage input from the microcomputer as the DC voltage rectified by the rectifier is applied to the microcomputer through the thermistor which is installed close to the rectifier and the resistance value varies according to the ambient temperature. The value can be grasped and the resistance value can be used to calculate the ambient temperature.

As such, when the temperature is determined by the current value at the voltage input terminal without receiving the temperature sensor value through a separate port, the microcomputer not only generates an error but also stops the operation of the microwave oven when it is determined to be above the set reference temperature. This prevents the fire and damage to the peripheral devices.

The driving method of the microwave oven according to the present invention made as described above will be described with reference to the flowchart shown in FIG. 4.

First, when the commercial power is applied, the low voltage converted DC power is input to the microcomputer. Then, the current value of the DC power input from the microcomputer is measured (S10).

The resistance value of the thermistor can be determined based on the measured current value, and thus the ambient temperature can be calculated (S12).

It is determined whether the reference temperature set on the basis of the calculated temperature is exceeded (S14).

In the present exemplary embodiment, when it is about 56 ° C. or higher, it is determined that other devices can be destroyed, thereby generating an error and stopping the operation of the microwave oven, thereby preventing the destruction of the device and preventing a fire due to overheating (S16). .

As described above, the present invention not only prevents overheating by adding a heat sink to a low voltage converter that generates a low voltage used in the control circuit of the microwave, but also stops driving the microwave by detecting an overheat generated from the low voltage converter. There is an advantage to prevent damage to the control circuit and fire.

Claims (3)

Low voltage transformer for receiving commercial AC power and stepping down to low voltage, A rectifying unit for rectifying the AC power stepped down by the low voltage transformer into a DC power source; A thermistor installed in proximity to the rectifier to vary a resistance value according to ambient temperature to vary the voltage of the DC power rectified by the rectifier; A constant voltage unit for generating a constant voltage by stabilizing the DC power output from the thermistor; In addition to controlling the operation of the microwave oven by receiving a stable voltage output from the constant voltage unit, and to determine the overheating state of the rectifier based on the change in the current value of the DC power output from the constant voltage unit to control the occurrence of error and operation Micom A driving circuit of a microwave oven, characterized in that consisting of. The drive circuit according to claim 1, wherein a heat sink is installed around the rectifying portion. Measuring a current value of an input low voltage; Calculating a temperature value corresponding to the measured current value; Determining whether the calculated temperature value exceeds a set reference temperature; Generating an error when the reference temperature is exceeded and stopping the operation of the microwave oven Driving method of a microwave oven, characterized in that consisting of.

Images