KR102729182B1 - Microwave oven having improved fault display structure - Google Patents

Abstract

The present invention relates to a microwave oven with an improved fault indication structure. In addition, a microwave oven according to an embodiment of the present invention includes an inverter substrate including a power supply unit which outputs an AC voltage, a rectifier unit which rectifies the AC voltage output from the power supply unit into a DC voltage, a smoothing unit which smoothes the DC voltage rectified by the rectifier unit, a switching unit which converts the DC voltage smoothed by the smoothing unit into an AC voltage through a switching operation and outputs it, a transformer which receives the AC voltage output from the switching unit and outputs a high-voltage AC voltage and a filament voltage, a DC converter unit which converts the high-voltage AC voltage output from the transformer into a high-voltage DC voltage, and a fault detection unit which emits light based on the filament voltage output from the transformer, and a magnetron which receives the high-voltage DC voltage and the filament voltage from the inverter substrate and outputs microwaves for heating food.

Description

MICROWAVE OVEN HAVING IMPROVED FAULT DISPLAY STRUCTURE

The present invention relates to a microwave oven with an improved fault indication structure.

In general, a microwave oven is a device that heats and cooks food inside a cooking chamber using microwaves as the main heating source, and includes a high voltage transformer and a magnetron.

Here, a high-voltage transformer generates a predetermined high voltage to drive a magnetron, and the magnetron emits high-frequency (approximately 2.45 GHz) microwaves into a cooking chamber (i.e., a closed space) containing food. In addition, the microwaves emitted from the magnetron vibrate water molecules contained in the food, and molecular friction heat is generated by the vibration of the water molecules, so that the food contained in the cooking chamber is heated and cooked.

In these microwave ovens, an inverter method is generally applied to control the operation of the magnetron.

Here, referring to Fig. 1, a conventional inverter type microwave oven is illustrated.

Figure 1 is a block diagram illustrating a conventional inverter-type microwave oven.

For reference, Fig. 1 is a drawing disclosed in Republic of Korea Publication No. 10-2004-0069430, and the drawing symbols used in Fig. 1 are applied only to Fig. 1.

Referring to FIG. 1, a conventional microwave oven includes a power input unit (10) for receiving and outputting AC power, an input voltage detection unit (40) for detecting an input voltage level of the power input unit (10), an inverter module (30) for receiving AC power from the power input unit (10), converting it into a high voltage of a DC level, outputting a PWM signal for driving a magnetron (20), and supplying the converted DC high voltage to the magnetron (20) according to the PWM signal, and a microcomputer (50) for controlling the inverter module (30) by receiving a voltage level detected by the input voltage detection unit (40), converting it into a recognizable signal form, and then outputting a control signal to reduce the PWM signal output of the inverter module (30) for a preset period of time if the voltage level corresponding to the converted signal is higher than a preset voltage.

In addition, the inverter module (30) is composed of a rectifier and smoother unit (31, 32) that rectifies and smoothes an AC voltage input from a power input unit (10) and outputs a DC voltage, a control unit (36) that outputs a PWM signal of a pulse level corresponding to a control signal of a microcomputer (50), a switching unit (33) that performs a switching operation on a DC voltage provided from the rectifier and smoother unit (31, 32) according to the PWM signal output from the control unit (36), and a boosting and amplifying unit (34, 35) that boosts and amplifies the DC voltage output through the switching unit (33) and outputs it to the magnetron (20).

Here, the microcomputer (50) detects the input voltage level inside the system based on the input voltage level provided from the input voltage detection unit (40), and outputs a control signal (Power Control Signal) to the inverter module (30) according to the detected input voltage level.

Accordingly, the conventional microwave oven prevents the inverter module (30) from being damaged due to overvoltage by reducing the PWM signal level in the inverter module (30) when overvoltage is detected.

However, in conventional microwave ovens, not only is there no component for detecting whether the inverter module (30) is broken, but there is also no component for visually indicating whether the inverter module (30) is broken, so there is a problem that it is difficult for a worker (i.e., a repairman) to determine whether the inverter module (30) is broken (or normal). In addition, since it is difficult for a worker to determine whether the inverter module (30) is broken, there is an increased possibility that the repair period for the inverter module (30) will be missed, and as a result, there is a problem that internal components of the microwave oven, including the inverter module (30), may be damaged or a fire may occur due to a malfunction of the inverter module (30).

An object of the present invention is to provide a microwave oven that visually indicates whether an inverter board is broken.

The purpose of the present invention is not limited to the purpose mentioned above, and other purposes and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. In addition, it will be easily understood that the purposes and advantages of the present invention can be realized by the means and combinations thereof indicated in the patent claims.

A microwave oven according to the present invention comprises: a power supply unit which outputs an AC voltage; a rectifier unit which rectifies the AC voltage output from the power supply unit into a DC voltage; a smoothing unit which smoothes the DC voltage rectified by the rectifier unit; a switching unit which converts the DC voltage smoothed by the smoothing unit into an AC voltage through a switching operation and outputs it; a transformer which receives the AC voltage output from the switching unit and outputs a high-voltage AC voltage and a filament voltage; a DC converter unit which converts the high-voltage AC voltage output from the transformer into a high-voltage DC voltage; an inverter board equipped with a fault detection unit which emits light based on the filament voltage output from the transformer; and a magnetron which receives the high-voltage DC voltage and the filament voltage from the inverter board and outputs microwaves for heating food.

The above transformer includes a primary stage having a primary coil that receives an AC voltage output from a switching unit, a secondary coil in which a high-voltage AC voltage is induced by the AC voltage provided to the primary coil, and a secondary stage having a heating coil in which a filament voltage is induced by the AC voltage provided to the primary coil.

The above DC converter includes a high-voltage capacitor and a high-voltage diode connected between the secondary coil and the magnetron, and the high-voltage AC voltage induced in the secondary coil is converted into a high-voltage DC voltage through the high-voltage capacitor and the high-voltage diode and provided to the magnetron.

The above fault detection unit is connected between the heating coil and the magnetron, and includes an overvoltage prevention diode, a current limiting resistor, and a light emitting element connected in series with each other, and the filament voltage induced in the heating coil is provided to the magnetron through the fault detection unit.

When the filament voltage induced in the heating coil is outside the preset normal filament voltage range, the light emitting element is turned off, and when the filament voltage induced in the heating coil is within the preset normal filament voltage range, the light emitting element is turned on.

If a failure occurs in the above inverter board, the light emitting element is turned off regardless of whether the magnetron is driven, and if no failure occurs in the inverter board, the magnetron is driven normally and the light emitting element is turned on.

The above light emitting element is mounted on the lower surface of the inverter substrate.

The insulation distance between the first and second terminals is 8 mm or more.

The number of turns of the secondary coil is larger than the number of turns of the primary coil, and the number of turns of the heating coil is smaller than the number of turns of the primary coil.

Further comprising a control unit for controlling the switching operation of the switching unit, wherein the output level of the magnetron is adjusted based on the switching operation of the switching unit.

The above rectifier is connected to the power supply, the smoothing unit is connected to the rectifier, the switching unit is connected to the smoothing unit, the transformer is connected to the switching unit, the DC conversion unit and the fault detection unit are connected to the transformer, and the magnetron is connected to the DC conversion unit and the fault detection unit.

The microwave oven according to the present invention visually indicates whether the inverter board is broken, so that the operator can easily determine whether the inverter board is broken. Furthermore, since the operator can easily determine whether the inverter board is broken, the broken inverter board can be repaired in a timely manner, thereby minimizing the possibility of damage to internal components of the microwave oven and fire caused by malfunction of the inverter board.

In addition to the effects described above, specific effects of the present invention are described below together with specific matters for carrying out the invention.

Figure 1 is a block diagram illustrating a conventional inverter-type microwave oven.
Figure 2 is a perspective view illustrating a microwave oven according to an embodiment of the present invention.
Figure 3 is a circuit diagram explaining an inverter board equipped in the microwave oven of Figure 2.
Figure 4 is a circuit diagram specifically explaining some components of Figure 3.

The above-mentioned objects, features and advantages will be described in detail below with reference to the attached drawings, so that those with ordinary skill in the art to which the present invention pertains can easily practice the technical idea of the present invention. In describing the present invention, if it is judged that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

When it is described below that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between each component, or that each component may be "connected," "coupled," or "connected" through another component.

Hereinafter, a microwave oven according to an embodiment of the present invention will be described with reference to FIGS. 2 to 4.

Fig. 2 is a perspective view illustrating a microwave oven according to an embodiment of the present invention. Fig. 3 is a circuit diagram illustrating an inverter board provided in the microwave oven of Fig. 2. Fig. 4 is a circuit diagram specifically illustrating some components of Fig. 3.

First, referring to FIG. 2, a microwave oven (1) according to an embodiment of the present invention may include a main body (10) in which a cooking chamber (11) providing a cooking space is formed, and a door (20) mounted on the main body (10) to open and close the cooking chamber (11).

Specifically, a cooking chamber (11) that is opened forward is formed in the main body (10), and a space for cooking can be exposed through the opened front. Although not shown in the drawing, a magnetron (500 in FIG. 2) and other components that enable cooking of food accommodated in the cooking chamber (11) can be provided inside the main body (10).

The door (20) is rotatably mounted on the main body (10) and can open and close the cooking chamber (11). In addition, the door (20) in a closed state can form part of the front exterior of the microwave oven (1).

And the main body (10) may be equipped with an operation panel (12). The operation panel (12) may be formed on the front of the main body (10) on the side of the cooking chamber (11), and may include a number of buttons (121) and knobs for user operation, a display (122) for indicating the operation status, etc. For reference, even if the door (20) is closed, the operation panel (12) is not shielded by the door (20).

Next, referring to FIGS. 3 and 4, the microwave oven (1) may further include various components that enable cooking of food accommodated in the cooking chamber (11).

For reference, FIG. 4 is a circuit diagram specifically explaining some components of FIG. 3 (e.g., a DC converter (400) and the connection relationship between components, etc.), so FIG. 3 and FIG. 4 will be described together.

Specifically, the microwave oven (1) may include a power supply unit (100), an inverter board (IV), a control unit (300), and a magnetron (500).

The power supply (100) can output AC voltage.

Specifically, the power supply unit (100) can output an AC voltage and provide it to an inverter board (IV; in particular, a rectifier unit (150)), and may be, for example, a commercial power supply (commercial power of 220 V).

The inverter substrate (IV) may be equipped with a rectifier (150), a smoother unit (200), a switching unit (250), a transformer (350), a direct current converter (400), and a fault detection unit (450).

First, the rectifier (150) can rectify the AC voltage supplied from the power supply (100) into a DC voltage.

Specifically, the rectifier (150) is connected to the power supply (100) and the smoothing unit (200), rectifies the AC voltage supplied from the power supply (100) into a DC voltage, and can provide the rectified DC voltage to the smoothing unit (200).

The smoothing unit (200) can smooth the DC voltage rectified in the rectifying unit (150).

Specifically, the smoothing unit (200) is connected to the rectifying unit (150) and the switching unit (250), smoothes the DC voltage provided from the rectifying unit (150), and can provide the smoothed DC voltage to the switching unit (250).

Here, smoothing the DC voltage may include reducing the ripple of the DC voltage, and the smoothing unit (200) may include, for example, a DC link capacitor.

The switching unit (250) can convert the DC voltage smoothed by the smoothing unit (200) into an AC voltage through a switching operation and output it.

Specifically, the switching unit (250) is connected to the smoothing unit (200) and the transformer (350), and converts the smoothed DC voltage provided from the smoothing unit (200) into an AC voltage (e.g., resonant voltage) through a switching operation, and can provide the converted AC voltage to the transformer (350).

In addition, the switching unit (250) can have its switching operation controlled by the control unit (300). That is, the switching unit (250) can perform a switching operation based on a switching signal provided from the control unit (300).

For reference, the switching unit (250) may include two switching elements (not shown), and the two switching elements may be alternately turned on and off by a switching signal provided from the control unit (300).

Additionally, an AC voltage can be generated by the switching operation of these two switching elements, and the generated AC voltage can be applied to a transformer (350).

The transformer (350) can receive the AC voltage output from the switching unit (250) and output a high-voltage AC voltage and a filament voltage.

Specifically, the transformer (350) is connected to the switching unit (250), the DC conversion unit (400), and the fault detection unit (450), and generates a high-voltage AC voltage and a filament voltage based on the AC voltage provided from the switching unit (250), and provides the generated high-voltage AC voltage to the DC conversion unit (400) and the generated filament voltage to the fault detection unit (450).

In addition, the transformer (350) may include a first stage equipped with a primary coil (352) that receives an AC voltage output from a switching unit (250), a second stage equipped with a secondary coil (354) in which a high-voltage AC voltage is induced by the AC voltage provided to the primary coil (352), and a second stage equipped with a heating coil (356) in which a filament voltage is induced by the AC voltage provided to the primary coil (352).

Here, the insulation distance between the first stage and the second stage can be 8 mm or more. This insulation distance is to prevent problems that may be caused by a high-voltage DC voltage (e.g., a DC voltage of 8 kV) provided from the DC converter (400) to the magnetron (500), and it is necessary to secure an insulation distance of at least 1 mm per size of the DC voltage of 1 kV.

That is, in the embodiment of the present invention, since the insulation distance between the first stage and the second stage is secured to be 8 mm or more, a problem that may occur when a DC voltage of 8 kV or more is applied to the magnetron (500) can be prevented.

For reference, an insulation distance of 8 mm or more is secured between the first and second stages. For example, an insulation distance of 8 mm or more can also be secured between the primary coil (352) provided in the first stage and a component (e.g., a fault detection unit (450)) connected to the second stage.

In addition, the number of turns of the secondary coil (354) may be greater than the number of turns of the primary coil (352), and the number of turns of the heating coil (356) may be smaller than the number of turns of the primary coil (352). Accordingly, the magnitude of the voltage induced in the secondary coil (354) may be greater than the magnitude of the voltage applied to the primary coil (352), and the magnitude of the voltage induced in the heating coil (356) may be smaller than the magnitude of the voltage applied to the primary coil (352).

For reference, the primary coil (352), secondary coil (354), and heating coil (356) illustrated in FIG. 3 are merely symbolic representations of each coil, and the number of turns of each coil illustrated in the drawing does not necessarily mean the actual number of turns.

In addition, the filament voltage is a voltage supplied to the filament of the magnetron (500) and may have a voltage size of, for example, 3.3 V. In addition, when the filament voltage is supplied to the magnetron (500), the filament of the magnetron (500) is heated and thermal electrons are emitted from the filament.

Meanwhile, the DC converter (400) can convert the high-voltage AC voltage output from the transformer (350) into a high-voltage DC voltage.

Specifically, the DC converter (400) is connected to the transformer (350) and the magnetron (500), converts the high-voltage AC voltage provided from the transformer (350) into a high-voltage DC voltage, and can provide the converted high-voltage DC voltage to the magnetron (500).

In addition, the DC converter (400) includes a high-voltage capacitor (HC1, HC2) and a high-voltage diode (HD1, HD2) connected between the secondary coil (354) and the magnetron (500), and the high-voltage AC voltage induced in the secondary coil (354) can be converted into a high-voltage DC voltage through the high-voltage capacitor (HC1, HC2) and the high-voltage diode (HD1, HD2) and provided to the magnetron (500).

Here, the number of high-voltage capacitors (HC1, HC2) and high-voltage diodes (HD1, HD2) may be changed, but for convenience of explanation, in the embodiment of the present invention, as illustrated in FIG. 4, it will be explained as an example that the number of high-voltage capacitors (HC1, HC2) and high-voltage diodes (HD1, HD2) is 2 each.

For reference, when the microwave oven (1) is initially operated, the magnitude of the high-voltage DC voltage increases to 8 kV and then decreases. Then, the magnitude of the high-voltage DC voltage increases again to 4 kV, and the high-voltage DC voltage that has reached 4 kV is supplied to the magnetron (500), thereby enabling high-frequency output (i.e., microwave output) of the magnetron (500).

Meanwhile, the fault detection unit (450) can emit light based on the filament voltage output from the transformer (350).

Specifically, the fault detection unit (450) is connected to the transformer (350) and the magnetron (500), and can emit light based on the filament voltage provided from the transformer (350).

In addition, the fault detection unit (450) is connected between the heating coil (356) and the magnetron (500), and includes an overvoltage prevention diode (454), a current limiting resistor (452), and a light emitting element (456) that are connected in series with each other, and the filament voltage induced in the heating coil (356) can be provided to the magnetron (500) through the fault detection unit (450).

Here, the light emitting element (456) may include, for example, an LED (Light Emitting Diode), and, unlike other components, may be mounted on the lower surface (i.e., the back surface) of the inverter substrate (IV) to improve process and design convenience. Accordingly, the worker can easily mount the light emitting element (456) on the inverter substrate (IV) separately from the other components. Furthermore, since the light emitting element (456) is mounted on the lower surface of the inverter substrate (IV) unlike other components, if a hole (not shown) is formed in a portion overlapping the light emitting element (456) in the main body (10 of FIG. 2) on which the inverter substrate (IV) is installed, the worker can easily visually determine whether the light emitting element (456) is emitting light through the hole.

Additionally, the light emitting element (456) can be turned on or off depending on the filament voltage induced in the heating coil (356).

That is, when the filament voltage induced in the heating coil (356) is outside the preset normal filament voltage range (for example, a voltage value within the error range based on 3.3 V), the light emitting element (456) is turned off, and when the filament voltage induced in the heating coil (356) is within the preset normal filament voltage range, the light emitting element (456) can be turned on.

For reference, if the filament voltage induced in the heating coil (356) is outside the preset normal filament voltage range, this may mean that a failure has occurred in the inverter board (IV) (i.e., a defect has occurred in a component or wire included in the inverter board (IV)).

On the other hand, the fact that the filament voltage induced in the heating coil (356) is within the preset normal filament voltage range may mean that no failure has occurred in the inverter board (IV) (i.e., normal operation of a component or wire included in the inverter board (IV)).

Accordingly, when a failure occurs in the inverter substrate (IV), the light emitting element (456) is turned off regardless of whether the magnetron (500) is driven, and when a failure does not occur in the inverter substrate (IV), the magnetron (500) is driven normally and the light emitting element (456) can be turned on.

Here, the fact that the light emitting element (456) is turned off regardless of whether the magnetron (500) is driven when a failure occurs in the inverter substrate (IV) means that the magnetron (500) can be driven even if a failure occurs in some parts of the inverter substrate (IV), and that the light emitting element (456) is turned on or off depending on the filament voltage induced in the heating coil (356) regardless of whether the magnetron (500) is driven.

In this way, whether the light-emitting element (456) emits light is determined based on whether the inverter substrate (IV) is faulty, and the worker can easily visually determine whether the inverter substrate (IV) is faulty based on whether the light-emitting element (456) emits light.

Meanwhile, the control unit (300) can control the switching operation of the switching unit (250) as described above.

Specifically, the switching operation of the switching unit (250) can be controlled according to the switching signal of the control unit (300), and the output level of the magnetron (500) can be adjusted based on the switching operation of the switching unit (250).

Additionally, the control unit (300) may include, for example, a microprocessor and may generate various switching signals through a PWM (Pulse Width Modulation) function.

The magnetron (500) can receive high-voltage direct current voltage and filament voltage from the inverter board (IV) and output microwaves for heating food.

Specifically, the magnetron (500) is connected to a fault detection unit (450) and a direct current conversion unit (400), and the output level of the magnetron (500) can be adjusted based on the switching operation of the switching unit (250).

For reference, the filament voltage induced in the heating coil (356) is provided to the magnetron (500) through the fault detection unit (450), and the high-voltage alternating current voltage induced in the secondary coil (354) can be converted into a high-voltage direct current voltage through the direct current conversion unit (400) and provided to the magnetron (500).

As described above, the microwave oven (1) according to the embodiment of the present invention visually indicates whether the inverter board (IV) is broken, so that the operator can easily determine whether the inverter board (IV) is broken. Furthermore, since the operator can easily determine whether the inverter board (IV) is broken, the broken inverter board can be repaired in a timely manner, thereby minimizing the possibility of damage to internal components of the microwave oven and occurrence of fire due to malfunction of the inverter board (IV).

Although the present invention has been described with reference to the drawings as examples, it is obvious that the present invention is not limited to the embodiments and drawings disclosed in this specification, and that various modifications can be made by those skilled in the art within the scope of the technical idea of the present invention. In addition, even if the effects according to the configuration of the present invention were not explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be recognized.

100: Power supply 150: Rectifier
200: Smoothing section 250: Switching section
300: Control unit 350: Transformer
400: DC converter 450: Fault detection unit
500: Magnetron

Claims (11)

A power supply that outputs AC voltage;
An inverter substrate equipped with a rectifier for rectifying the AC voltage output from the power supply unit into a DC voltage, a smoothing unit for smoothing the DC voltage rectified by the rectifier unit, a switching unit for converting the DC voltage smoothed by the smoothing unit into an AC voltage through a switching operation and outputting it, a transformer for receiving the AC voltage output from the switching unit and outputting a high-voltage AC voltage and a filament voltage, a DC conversion unit for converting the high-voltage AC voltage output from the transformer into a high-voltage DC voltage, and a fault detection unit for emitting light based on the filament voltage output from the transformer; and
It includes a magnetron that receives the high-voltage direct current voltage and the filament voltage from the inverter board and outputs microwaves for heating the food.
The above transformer,
A primary stage having a primary coil that receives the AC voltage output from the above switching unit,
A secondary coil in which the high-voltage AC voltage is induced by the AC voltage provided to the primary coil, and a secondary stage including a heating coil in which the filament voltage is induced by the AC voltage provided to the primary coil,
The above fault detection unit is connected in parallel to both ends of the heating coil, and turns off the light emission regardless of whether the magnetron is driven when the filament voltage induced in the heating coil is out of the preset normal filament voltage range.
Microwave oven.
delete In the first paragraph,
The above DC converter includes a high-voltage capacitor and a high-voltage diode connected between the secondary coil and the magnetron,
The high voltage AC voltage induced in the secondary coil is converted into the high voltage DC voltage through the high voltage capacitor and the high voltage diode and provided to the magnetron.
Microwave oven.
In the first paragraph,
The above fault detection unit is connected between the heating coil and the magnetron, and includes an overvoltage prevention diode, a current limiting resistor, and a light emitting element connected in series with each other.
The filament voltage induced in the heating coil is provided to the magnetron through the fault detection unit.
Microwave oven.
In paragraph 4,
When the filament voltage induced in the heating coil falls within the preset normal filament voltage range, the light emitting element is turned on.
Microwave oven.
In paragraph 4,
If a failure occurs in the above inverter board, the light emitting element is turned off regardless of whether the magnetron is driven.
If there is no failure in the above inverter board, the magnetron operates normally and the light emitting element is turned on.
Microwave oven.
In paragraph 4,
The above light emitting element is mounted on the lower surface of the inverter substrate.
Microwave oven.
In the first paragraph,
The insulation distance between the first and second blocks is 8 mm or more.
Microwave oven.
In the first paragraph,
The number of turns of the above secondary coil is greater than the number of turns of the above primary coil,
The number of turns of the above heating coil is smaller than the number of turns of the above primary coil.
Microwave oven.
In the first paragraph,
Further comprising a control unit for controlling the switching operation of the switching unit,
The output level of the above magnetron is adjusted based on the switching operation of the above switching unit.
Microwave oven.
In the first paragraph,
The above rectifier is connected to the above power supply,
The above smoothing part is connected to the above rectifying part,
The above switching unit is connected to the above smoothing unit,
The above transformer is connected to the above switching unit,
The above DC converter and the above fault detection unit are connected to the transformer,
The above magnetron is connected to the DC converter and the fault detection unit.
Microwave oven.