KR100240336B1 - Timer assembly of a microwave oven - Google Patents

Abstract

The present invention relates to a timer device for a microwave oven using a PTC thermistor. The present invention relates to a timer device for providing a driving force after a set time has elapsed, and to receive a driving force of the time motor 40 to switch the power supply voltage to an indoor lamp (60). ) Is connected to the first switch 20 and the first switch 20 provided to the fan motor 64 and the gear motor 62, and receives the driving force of the time motor 40 to receive the first switch 20. The second switch 30 for applying the power supply voltage of the high voltage drive unit 90 and the PTC thermistor 36 connected to the second switch 30 and interlocked with the second switch 30, the wiring process The manufacturing cost of the deletion can be reduced.

Description

Microwave timer device {TIMER ASSEMBLY OF A MICROWAVE OVEN}

The present invention relates to a microwave oven, and more particularly, to a timer device for a microwave oven using a PTC thermistor (Positive Temperature Coefficient thermistor).

As is well known, a microwave oven cooks food with friction heat generated by molecular motion by irradiating food with microwaves generated from a magnetron in a state in which food is placed in a cavity.

Such a microwave oven can be broadly divided into a key input unit, an oscillator, a high pressure unit, a control unit, a display unit, and a heating chamber.

The key input unit is composed of a key pad for setting a cooking time of the microwave oven and various automatic cooking menus, and the oscillation unit is composed of a magnetron generating high frequency, a waveguide leading the high frequency to the heating chamber, and a cooling fan cooling the magnetron.

The high voltage part is composed of a heater voltage required for the operation of the magnetron, a high voltage transformer (DC) for making a DC high voltage, a high voltage capacitor, a high voltage diode, etc., and the control part includes a time switch or a control circuit for controlling the heating time. The display unit is composed of light emitting elements for displaying various cooking times and cooking conditions.

Finally, the heating chamber is composed of a heating plate for heating the closed food, a turntable and a door for dispensing the food.

On the other hand, the above-described microwave oven is equipped with a timer having a function of turning on or off the state of the circuit when a predetermined time elapses, and a slowing relay for performing an effective operation of the timer.

The slow relay is connected between the time switch, which is a component of the timer, and the primary coil of the high voltage transformer of the microwave oven, and it does not operate immediately even if an external voltage is applied, and operates after a predetermined time (for example, 20 ms). .

Therefore, even if the time switch is turned on in the state in which the power supply is applied to the driving circuit of the microwave oven, since it does not operate immediately, it is possible to prevent overload of the driving circuit and damage of the microwave oven in advance.

1 shows a timer driving circuit diagram of a conventional microwave oven using such a slow relay.

In the figure, the timer unit 10 includes a first switch 20, a second switch 30, and a time motor 40, respectively.

The first switch 20 is connected to the power cord 80 and the second switch 30, the contact is turned on after a predetermined time by the drive of the time motor 40 having a plurality of gears (gear) By turning on / off, power is connected or disconnected to components such as a cavity lamp 60, a gear motor 62, and a fan motor 64 of a microwave oven.

The second switch 30 is connected between the first switch 20 and the high voltage transformer primary side coil (not shown) of the high voltage driver 90, and similarly to the first switch 20, the time motor 40 is driven. Is selectively turned on / off. That is, when the switch is off, the power is induced only by the above-described indoor light 60, the gear motor 62, the fan motor 64, and the like, and when the switch is on, the power is induced by the high pressure drive unit 90. Therefore, when the second switch 30 is turned on, cooking of food is possible by emitting high frequency from the magnetron (not shown) included in the high-pressure driving unit 90.

The time motor 40 has a plurality of rotating gears, and is automatically driven when time setting by a user's operation is completed, and when the predetermined time has elapsed, the first switch 20 and the second switch ( 30).

In addition, the slow relay unit 50 is composed of a slow relay 52 and a resistor 54, the slow relay 52 is a fixed time after the on operation of the second switch 30 due to the above-described operating characteristics When it passes, it turns on. Therefore, the over-current is consumed momentarily by the resistor 54 before the slow-down relay 52 is turned on.

As described above, the timer device of the conventional microwave oven is a very useful device for appropriately driving the high-pressure driving unit at a time desired by the user, and also preventing overload and short circuit.

However, the above-described apparatus has one disadvantage in terms of the manufacturing process of the microwave oven. That is, the slow relay 52 required for the efficient operation of the timer unit 10 belongs to a considerably high price.

Therefore, there is a problem in that the manufacturing cost of the microwave oven increases due to the mounting and wiring process of the slow relay unit 50.

Accordingly, an object of the present invention is to provide a timer device for a microwave oven to cut off the overload of the microwave by replacing an expensive slow relay.

In order to achieve the above object, the present invention provides a microwave motor driven by a high-pressure driving unit, an indoor lamp, a fan motor, and a gear motor according to an application of a power supply voltage. It is connected to the first switch and the first switch for supplying the power supply voltage to the indoor lamp, the fan motor and the gear motor, and is supplied with the driving power, and is supplied with the driving power of the time motor to apply the power supply voltage of the first switch to the high voltage driving unit. The second switch is connected to the second switch, and provides a microwave oven, characterized in that composed of a PTC that works with the second switch.

1 is a circuit diagram of a timer device of a microwave oven using a conventional slow-motion relay,

2 is a circuit diagram of a timer device for a microwave oven using a PTC thermistor according to the present invention;

3 is a detailed view of the second switch of FIG.

<Description of the code | symbol about the principal part of drawing>

10: timer unit 20: first switch

30: second switch 32: movable contact

34: fixed end 36: PTC thermistor

38: free end 40: time motor

50: slow motion relay 52: slow motion relay

54: resistance 60: room light

62: gear motor 64: fan motor

80: power cord 90: high pressure drive unit

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings.

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

2 is a circuit diagram of a timer device of a microwave oven using a PTC thermistor according to the present invention.

In the figure, the timer unit 10 includes a first switch 20, a time motor 40, and a second switch 30, respectively.

The first switch 20 connects the power cord 80 and the second switch 30, and the contact is turned on / off when a predetermined time elapses by driving the time motor 40 having a plurality of gears. , To connect or cut off the power to components such as the indoor lamp 60, the gear motor 62, the fan motor 64 of the microwave oven.

The time motor 40 has a plurality of rotating gears, and is automatically driven when time setting by a user's operation is completed, and when the predetermined time has elapsed, the first switch 20 and the second switch ( 30).

The second switch 30 is connected between the first switch 20 and the high voltage driver 90, and like the first switch 20, is selectively turned on / off by driving the time motor 40. That is, when the switch is off, the power is induced only by the above-described indoor light 60, the gear motor 62, the fan motor 64, and the like, and when the switch is on, the power is induced by the high pressure drive unit 90. Therefore, when the second switch 30 is turned on, cooking of food is possible by emitting high frequency from the magnetron connected to the high pressure driving unit 90.

On the other hand, the second switch 30 is provided with a PTC thermistor according to the present embodiment, the PTC thermistor has a function of delaying the connection of the high voltage induced in the high-voltage drive unit 90 due to its operation characteristics.

3 shows in detail a second switch 30 comprising such a PTC thermistor 36.

Prior to the description, the PTC thermistor 36 refers to a thermistor (static thermistor) in which the resistance value increases significantly when the temperature rises, unlike a general thermistor.

As shown in FIG. 3, the second switch 30 includes a PTC thermistor 36 according to the present embodiment, a movable contact 32 connecting / blocking a power supply voltage of the first switch 20, and a high voltage of a microwave oven. The fixed end 34 connected to the drive part 90, and the free end 38 which connects the PTC thermistor 36 are comprised.

In detail, the fixed end 34 of the second switch 30 is connected to the power line of the high voltage drive unit 90, and the free end 38 is connected between the movable contacts 32 of the second switch 30. It maintains a gap of spaced apart, for example, 4 mm.

That is, when the current is induced by the second switch 30, the free end 38 of the second switch 30 may have a predetermined time, for example, 20 to 20 seconds from the time when the movable contact 32 of the second switch 30 operates. After the delay of 400 msec is switched to the fixed end 34. Therefore, the connection of the high voltage induced in the high voltage driver 90 is delayed.

In summary, when the movable contact 32 of the second switch 30 presses the free end 38 by the driving force of the time motor 40, the free end 38 and the fixed end 34 are connected after a certain time. do. Therefore, the power supply voltage applied from the power cord 80 is induced to the high voltage driver 90 and the microwave is driven.

As described above, the present invention has the effect of reducing the manufacturing cost by eliminating the wiring process by attaching the PTC thermistor to the timer of the microwave oven instead of the expensive slow relay.

Claims (1)

In the timer apparatus of the microwave oven which the high-pressure drive unit 90, the indoor light 60, the fan motor 64 and the gear motor 62 is driven in accordance with the application of the power supply voltage, A time motor 40 for providing a driving force after the elapse of the set time; A first switch 20 which is switched by receiving the driving force of the time motor 40 to provide a power supply voltage to the indoor lamp 60, the fan motor 64, and the gear motor 62; A second switch 30 connected to the first switch 20 and receiving a driving force of the time motor 40 to apply a power supply voltage of the first switch 20 to the high voltage driver 90. But The second switch 30, A movable contact 32 connected to an output terminal of the first switch 20 and driven by a driving force of the time motor 40; A fixed end portion 34 connected to the high pressure driving portion 90; A PTC thermistor 36 connected to the fixed end 34; And a free end 38 connected to the PTC thermistor 36, and the movable contact 32 presses the free end 38 toward the fixed end 34 by the driving force of the time motor 40. And the movable contact (32) is connected to the free end (38) so that the free end (38) is sequentially connected to the fixed end (34).

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