KR100220967B1 - Method of controlling relay phase of microwave oven - Google Patents

Abstract

Relay phase control method of microwave oven to minimize the trauma to the high voltage transformer by appropriately adjusting the phase delay value of the high voltage transformer relay when the high voltage transformer relay is operated after various other relays are activated. Is disclosed. The relay phase control method of the microwave includes determining whether it is time to drive the magnetron; Determining when the grill or convection relay is activated when it is time to drive the magnetron; Driving the high voltage transformer relay by compensating for a delay time of a predetermined high voltage transformer relay when the reel or the convection relay is not activated; And when the grill or convection relay is activated, adjusting the delay time according to the number of activated relays, and driving the high voltage transformer relay according to the adjusted delay time. To operate in the best possible state (ie with minimal trauma).

Description

Relay phase control method of microwave oven

The present invention relates to a relay phase control method of a microwave oven, and more particularly, a microwave relay configured to actively adjust a phase delay value of a relay for a high voltage transformer depending on whether another relay is activated when a relay for a high voltage transformer is driven. It relates to a phase control method.

Advances in science and technology have led to great innovation in the kitchen, and many cooking utensils are available to assist housewives in their kitchens.

One such cooker is a microwave oven (microwave oven), which is different from cookware using heat conduction heating methods such as briquettes and gas tables and cookware using heat radiation heating methods such as electric ovens. The high-frequency electricity is applied to a microwave oscillating tube called magnetron to quickly cook food placed on a turntable (or tray).

As shown in FIG. 1, a general microwave oven includes a rotating dish 1 for placing food to be cooked and a rotating ring 2 installed in an annular shape on the bottom of the rotating dish 1, as shown in FIG. And a door 4 for preventing the external emission of electromagnetic waves generated during the cooking process, and an operation panel 5 having a plurality of buttons for key input according to a user's preference, and the door ( On the inner side of 4), a door lock safety device 4a is installed to fix the door 4 to the main body, and the central portion of the door 4 is a viewing window 4b through which the cooking progress can be seen. The inner side of the door (that is, the part which comes into contact with the main body) is provided with an electromagnetic wave absorber 4c which prevents leakage of electromagnetic waves.

In addition, the internal circuit configuration of the above-described conventional microwave oven, as shown in Figure 2, removes the noise generated in the power cord 10 and the microwave oven, which serves as a power input line (line filter) 11) a power supply for inputting the power of the microwave oven with; A microcomputer 13 for controlling the overall operation of the microwave oven according to a signal input from the operation panel 5 while receiving power from the low voltage transformer 12; A high voltage transformer 14 generating a secondary voltage of about 2100V when a primary voltage of 110V / 220V is input, a high voltage capacitor 15 that produces 4KV by half-wave doubling about 2100V, and a high voltage diode ( 16) and a high voltage section having a magnetron 17 for oscillating with a half-wave double voltage to emit electromagnetic waves; A tray motor (Gear Motor) (18), a high-voltage transformer (14), a high-voltage capacitor (15), and a high-pressure that rotate the rotating plate (1) to prevent hot spots and produce an electromagnetic wave dispersion effect to evenly cook food. A fan motor / tray motor unit having a fan motor 19 for cooling heat generated when the diode 16 and the magnetron 17 are operated, thereby improving the performance of the microwave oven; When the door (4) is opened during the microwave operation, the high frequency in the cooking chamber (3) can be emitted to the outside safety switch unit to shut off the power to prevent electromagnetic leakage to the outside; The heater 28 is operated when performing the grill function.

On the other hand, the safety switch unit is automatically turned off when the temperature of the magnetron 17 exceeds the set value and stops the magnetron operation, and automatically turns off when the temperature of the heater 28 exceeds the set value, the heater operation A micro switch (for example, a primary safety switch) that is turned on and off by a grill switch 27 for stopping and a hook (door lock safety device 4a) installed in the door 4 when the door 4 is opened and closed. 21), the secondary safety switch 22, the door open detection switch 26, the monitor switch 29 and the like, and the relay (e.g., start relay 23, output adjustment) by the microcomputer 13 Relay 24, heater relay 25, etc.). Typically, when the door 4 is closed, the monitor switch 29 is turned off, and the primary and secondary safety switches 21 and 22 remain on, and when the cooking starts, the interior lamp 30 is turned on. .

Referring to the general cooking operation of the microwave oven configured as described above are as follows.

First, a voltage 110V or 220V of a predetermined value from the power supply unit is transformed by the low voltage transformer 12 and then applied to the microcomputer 13 as a power source of the microcomputer 13, in which the user (operator) Place the food to be cooked on the rotating dish 1 of the cooking chamber 3, close the door 4 completely, and set the desired cooking menu and time and output (cooking heating temperature) using the buttons on the operation panel 5. When the cooking start command is inputted, the microcomputer 13 turns on the start switch 23 and turns on the output control switch 24, so that the rotary plate 1 is rotated by the tray motor 18. At the same time, a fan (not shown) is rotated by the fan motor 19, and the magnetron 17 uses the high voltage generated by the high voltage transformer 14, the high voltage capacitor 15, and the high voltage diode 16. Ultra-high frequency through waveguide (not shown) into cooking chamber 3 The food in the cooking chamber 3 is cooked by releasing.

A general microwave oven operating as described above includes a microwave having a simple function of cooking with only a microwave with only the magnetron 17; Means a microwave cooking function using only the magnetron 17, a grill cooking function using only the heater 28, the heater 28 and the fan (convection fan installed separately from the cooling fan). The magnetron 17 and the heater to perform a fast cooking function using the magnetron 17 and the heater 28 at the same time in order to quickly and quickly cook the grilled type, and the cooking function using the (28) can be classified into a multi-functional microwave oven. The microcomputer 13 of such a microwave oven has a delay time obtained by repetitive experiments for phase control of a high voltage transformer relay to be used in a current model (i.e., The time until the relay contact is actually connected when the relay active power is applied to the relay coil for the high voltage transformer is stored as data.

However, the delay time for the high-voltage transformer phase obtained as described above is normally applicable only when activating the high-voltage transformer relay only. After the contact of another relay (ie, a grill relay, a convection relay, etc.) is connected, When the high voltage transformer is activated, the relay operating voltage (for example, DC 12V) drops and the set delay time does not match.

In other words, the AC voltage of the predetermined value applied to the low voltage transformer 12 is transformed into the constant low voltage (eg, sine wave; see also the third (a)) by the low voltage transformer 12 and then through the diode. The rectified and periodic square wave (see also third (b)) is input to the external interrupt port (INT port) of the microcomputer 13, and the external interrupt signal (square wave) is periodically input by the microcomputer 13 in this manner. Under the condition, when the high voltage transformer relay 24 is activated after the fan coater 19 and the heater 28 and the convection relay are sequentially activated under the control of the microcomputer 13, the third (c) to the third As exemplarily shown in FIG. 3 (f), they do not operate at the same time with each other, but operate sequentially with a slight delay time.

In this case, the delay time (ㅿ t; see also 3 (f)) of the last-operated high voltage transformer is different from the delay time when only the high voltage transformer is activated by the DC voltage change. If the trauma is applied to the high voltage transformer, the service life of the product is shortened.

Accordingly, the present invention has been made to solve the above-mentioned problems. When the high voltage transformer is driven after the various relays are activated, the present invention appropriately adjusts the phase delay value of the high voltage transformer relay. It is an object of the present invention to provide a relay phase control method of a microwave oven to minimize the trauma to the transformer.

In order to achieve the above object, a relay phase control method of a microwave oven according to the present invention includes determining whether it is time to drive a magnetron; Determining when the grill or convection relay is activated when the magnetron is to be driven; Driving the high voltage transformer relay by compensating for a delay time of a predetermined high voltage transformer relay when the reel or the convection relay is not activated; And when the grill or convection relay is activated, adjusting the delay time according to the number of activated relays, and driving the high voltage transformer relay according to the adjusted delay time.

According to the present invention, by controlling the delay time of the high-voltage transformer to be compensated according to the activation of the grill or the convection relay, the high-voltage transformer can be operated in the best state (that is, the state of trauma is minimized).

1 is a view showing the appearance of a typical microwave oven.

2 is an internal circuit diagram of a general microwave oven.

3 is a signal waveform diagram for explaining a problem caused by a relay operation of a general microwave oven.

4 is a diagram showing the configuration of a relay phase control apparatus for a microwave oven to which the present invention is applied.

5 is a flowchart illustrating a relay phase control method of a microwave oven according to the present invention.

* Explanation of symbols for main parts of the drawings

1: rotating plate 2: rotating ring

3: cooking chamber 4: door

5: operation panel 10: power cord

11: line filter 12: low voltage transformer

13: microcomputer 14: high voltage transformer

15: high voltage capacitor 16: high voltage diode

17: magnetron 18: tray motor

19: fan motor 20: magnetron temperature switch

21,22: Safety switch 23: Start relay

24: output control relay 25: heater relay

26: door open detection switch 27: grill switch

28: heater 29: monitor switch

30: high light 32: regulator

34: microcomputer 36: relay for convection

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

4 is a view showing the configuration of a relay phase control apparatus for a microwave oven employed as an embodiment of the present invention. The embodiment of the present invention is a low voltage transformer 12, a bridge diode (BD), a regulator 32, a microcomputer ( 34), switching transistors Q1, Q3, Q4, high voltage transformer relay 24 (output regulating relay), heater relay 25 (also referred to as grill relay in the embodiment of the present invention), and convection relay 36. The same components as those described in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

The regulator 32 is transformed into a low voltage in the low voltage transformer 12, and the voltage rectified by the bridge diode BD to a DC voltage (e.g., about DC 12V for relay driving) is made into a predetermined constant voltage (e.g., about 5V). Switching is applied to the microcomputer 34, for example, the base is grounded through the zener diode ZD, the collector is connected to the output terminal of the bridge diode BD, and the emitter is connected to the input terminal of the microcomputer 34. The transistor Q2 and a capacitor C2 provided between one side of the emitter of the switching transistor Q2 and the ground may be formed.

The switching transistor Q1 has a base connected to one end of the bridge diode BD via a diode D1 and a resistor R1, and a collector is connected to a power supply of about 5V, and an external interrupt port INT of the microcomputer 34 is connected. and a periodic square wave (see also third (b)) to the external interrupt port (INT port) by an on / off operation.

The microcomputer 34 controls the operation of the entire microwave oven on the basis of the key input signal from the operation panel 5, while the other relays 25 and 36 are turned on / off when the high voltage transformer relay 24 is driven. The phase delay value of the relay 24 is adjusted accordingly.

The switching transistor Q3 has a base connected to the output port P1 of the microcomputer 34 via a resistor R2 and a high voltage transformer relay 24 connected to the emitter, and under the control of the microcomputer 34. Will activate (24).

The switching transistor Q4 has a base connected to the output port P2 of the microcomputer 34 via a resistor R3 and a heater relay 25 connected to the emitter, and under the control of the microcomputer 34, the relay ( 25) will be activated.

The switching transistor Q5 has a base connected to the output port P3 of the microcomputer 34 via a resistor R4 and a convection relay 36 connected to the emitter, and under the control of the microcomputer 34 a relay ( 36) will be activated.

Next, the relay phase control method of the microwave oven according to the present invention will be described based on the device configured as described above.

In the flowchart of FIG. 5, once there is a key input from the operation panel 5 (step 50), the microcomputer 34 grasps the currently input key signal to determine whether the magnetron should be operated. As a result of the determination, when the magnetron does not need to be operated (NO in step 52), the output port P1 is brought into a low level state, and thus the switching transistor Q3 is not conducting, so that the high voltage transformer relay 24 Will remain off.

However, when the magnetron is to be operated (YES in step 52), it is determined whether the heater relay 25 (the grill relay) or the convection relay 36 is already activated, and as a result, the heater relay 25 ) And the delay time (e.g., set to 10 msec) for the preset high-voltage transformer relay 24 only if the convection relay 36 is not activated (NO in step 56). When the counter counts back step by step (step 58), and the counter counted delay time becomes "0" (YES in step 60), the microcomputer 34 conducts the switching transistor Q3 so that the high voltage transformer relay 24 ) Is activated (step 62).

However, when the heater relay 25 or the convection relay 36 is already activated as a result of the determination in step 56, the microcomputer 34 calculates a predetermined subtraction value according to the number of the activated relays and is preset. The delay time for the high voltage transformer 24 is subtracted (step 64). For example, the subtraction value is set to 2 msec when only one of the two relays 25 and 36 is preactivated, and is set to 4 msec when both relays 25 and 36 are preactivated.

Therefore, after 2 (msec) or 4 (msec) is subtracted from the delay time (for example, set to 10 msec) for the preset high voltage transformer 24, the process returns to the step 58 described above and after and When the delay time is " 0 ", the high voltage transformer relay 24 is activated. Therefore, the high voltage transformer has the best position (e.g., the position where the inrush current is the smallest). Points to be crossed).

On the other hand, the present invention is not limited only to the above-described embodiments, but may be modified and modified without departing from the scope of the present invention. For example, in the embodiment of the present invention, compared to the relay for the high voltage transformer, the number of relays that can be pre-activated is set and described as two, but the subtraction value may vary as the number of relays increases.

According to the present invention as described above, since the delay time of the high-voltage transformer is variablely adjusted according to whether or not the other relay is activated when the high-voltage transformer is driven, the high-voltage transformer is in the best state (that is, the state in which the trauma is minimized). It will work on.

Claims (1)

Determining whether it is time to drive the magnetron; Determining when the grill or convection relay is activated when the magnetron is to be driven; Driving the high voltage transformer relay by compensating for a delay time of a predetermined high voltage transformer relay when the reel or the convection relay is not activated; And when the grill or convection relay is activated, adjusting the delay time according to the number of activated relays, and driving the high voltage transformer relay according to the adjusted delay time. Relay phase control method of microwave oven.