KR100283657B1 - Safety circuit of wall-mounted microwave oven - Google Patents

Abstract

A safety circuit of a wall-mounted microwave oven is disclosed. Disclosed is a wall-mounted microwave oven for controlling the output of a magnetron by varying the number of windings of a high-voltage transformer primary coil, the high output relay formed at the front end of the monitor switch, and the high output relay at the rear end of the monitor switch in series. A low output relay is formed and connected in parallel with the middle tap of the high-voltage transformer primary coil and a short prevention means interposed between the intermediate end and the rear end of the low output relay. The short prevention means is preferably composed of a resistor or a capacitor. Therefore, even when the door switch is abnormally, that is, even when the door is open, the high voltage transformer is not abnormally operated, thereby eliminating the risk of magnetron oscillation in the open state of the door.

Description

Safety circuit of wall-mounted microwave oven

The present invention relates to a safety circuit of a wall-mounted microwave oven, and more particularly, to a safety circuit of a wall-mounted microwave oven to control the output of the magnetron by varying the number of windings of the high-voltage transformer primary coil.

In general, the wall-mounted microwave oven, also known as OTR (over the range) model, is mainly installed on the upper side of the stove performs a cooking function and a hood function together. 1 and 2 are diagrams for explaining the installation and operating state of such a common wall-mounted microwave oven.

According to this, the hood lamp 12 is installed on the bottom surface of the cooking chamber 11 of the wall-mounted microwave oven 10, and the exhaust duct 14 is installed on the left and right sides of the cooking chamber 11. In addition, the ventilation motor 16 is installed in the center of the upper surface rear of the cooking chamber 11, and the ventilation fan 18 is arranged on the left and right sides of the ventilation motor 16. Therefore, the food lamp at the bottom thereof is illuminated using the hood lamp 12, and steam or smoke generated by the cooking of the stove 30 is sucked through the exhaust ducts 14 at the left and right sides of the microwave oven 10. The sucked steam or smoke is discharged to the exhaust passage 22 formed on the wall via the connecting pipe 20 by the rotation of the ventilation fan 18.

3 is a detailed circuit diagram of a conventional wall-mounted microwave oven. Here, the first and second alternating lines L1 and L2 receiving the AC power AC are connected to the primary coil 7a of the high voltage transformer HVT. A ventilation motor 16 and a hood lamp 12 for performing a hood function are connected in parallel between the first and second alternating lines L1 and L2, respectively, and each ventilation motor 16 is connected at each end. And first and second relays RY1 and RY2 for turning on / off the hood lamp 12 are connected. In addition, a cooking lamp CL and a fan motor FM for forming a cooking function are formed between the first and second alternating lines L1 and L2, and the cooking lamp CL and the fan motor FM are formed. The third relay RY3 for turning on / off is connected. In addition, the first switch line (L1) is connected in series with one side of the high-voltage transformer (HVT) primary coil (7a) of the door switch (SW1) on / off in accordance with the opening and closing of the door of the cooking chamber (11), A fifth relay RY5 is connected to the second alternating line L2 in series with the other side of the high voltage transformer HVT primary coil 7a. In addition, a fourth relay RY4 is connected to the primary coil 7a of the high voltage transformer HVT through an intermediate tap 7b, and the fourth relay RY4 is parallel to the fifth relay RY5. Leads to. In addition, a monitor switch SW2 is provided between the first alternating line L1 at the rear end of the door switch SW1 and the second alternating line L2 at the rear end of the fifth relay RY5. The magnetron (MGT) is connected to the secondary coil 7b of the high voltage transformer (HVT) through a high pressure fuse (H.V.FUSE), a high pressure capacitor (HVC), and a high voltage diode (HVD). The high voltage transformer HVT boosts the input voltage to a high voltage according to the number of turns of the coil and outputs the voltage. Therefore, the high voltage transformer HVT inputs an AC voltage through the primary coil 7a and boosts it to a high voltage of approximately 2000V through the secondary coil 8a. In addition, the high voltage diode HVD and the high voltage capacitor HVC double the high voltage to about 4000V and supply the same to the magnetron MGT. On the other hand, the magnetron (MGT) is preheated by the voltage supplied through the filament coil (8b), and then driven by a voltage of about 4000V supplied from the high voltage diode (HVD) and the high voltage capacitor (HVC) to emit microwaves of a predetermined frequency Done. Therefore, the food is heated / cooked by the microwaves emitted from the magnetron (MGT). The high voltage fuse (H.V.FUSE) cuts off the overcurrent on the side of the high voltage transformer (HVT) secondary coil 8a.

Looking at the action of the conventional wall-mounted microwave oven configured as described above, while the door is normally open, the door switch (SW1) is off, the monitor switch (SW2) is kept on while the door switch (SW1) as the door is closed Is turned on, and the monitor switch SW2 is turned off. Here, the monitor switch SW2 is a kind of safety device, and bypasses the AC power AC input while the door is open, thereby preventing the high voltage transformer HVT from operating. Meanwhile, when the cooking function is performed while the door is closed, the third relay RY3 is turned on to operate the cooking lamp CL and the fan motor FM. Here, the fourth relay RY4 is turned on and the fifth relay RY5 is kept off. Accordingly, the AC power source AC input to the first AC line L1 flows through the intermediate tap 7b of the primary coil 7a. This AC power source AC is guided to the secondary coil 8a to oscillate the magnetron MTG. When the ventilation function is performed in this state, that is, when the first relay RY1 or the second relay RY2 is turned on to operate the ventilation motor 16 or the hood lamp 12, the fourth relay RY4 is turned on. ) Is turned off and the fifth relay RY5 is turned on. Therefore, the number of turns of the primary coil 7a of the high voltage transformer HVT is increased to prevent the overcurrent from being applied to the primary coil 7a. At this time, the magnetron MTG of the secondary coil 8a Output decreases. On the other hand, when the first relay RY1 or the second relay RY2 is turned off, the fourth relay RY4 is turned on and the fifth relay RY5 is turned off. Therefore, since the number of turns of the primary coil 7a is reduced, the output of the magnetron MTG through the secondary coil 8a is relatively increased, thereby obtaining a high output. In addition, when the cooking function is additionally performed while the ventilation function is being performed first, the fourth and fifth relays RY4 and RY5 are alternately turned on and off, and thus, the first order of the high voltage transformer HVT. Since the number of windings of the coil 7a is varied, the output of the magnetron MTG is adjusted to prevent overcurrent.

However, in the conventional wall-mounted microwave oven, since the monitor switch is connected only to the fifth relay due to the circuit configuration, the fifth switch is in a state in which the door switch is abnormal, that is, the door switch is turned on even though the door is open. The abnormal operation of the high voltage transformer when the relay is turned on is blocked by the monitor switch, but the magnetron cannot be driven because the abnormal operation of the high voltage transformer when the fourth relay connected in parallel with the fifth relay is turned on cannot be blocked. There was a problem with concern.

The present invention is to solve the problems of the prior art as described above, its purpose is to change the number of windings of the primary coil of the high-voltage transformer in the wall-mounted microwave oven to control the output of the magnetron when the door switch is abnormal It is to provide a safety circuit for a wall-mounted microwave oven that prevents the high voltage transformer from operating abnormally.

1 and 2 are views for explaining the installation state of a typical wall-mounted microwave oven,

3 is a detailed circuit diagram of a conventional wall-mounted microwave oven,

Figure 4 is a detailed circuit diagram showing a safety circuit of the wall-mounted microwave oven according to a preferred embodiment of the present invention,

Figure 5 is a detailed circuit diagram showing a safety circuit of the wall-mounted microwave oven according to another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

7a: Primary coil 7b: Middle tap

100: short prevention means C10: condenser

HVT: High Voltage Transformer MGT: Magnetron

R10: Resistor RY10: High Output Relay

RY20: Low output relay SW2: Monitor switch

The safety circuit of the wall-mounted microwave oven of the present invention for achieving this purpose, in the wall-mounted microwave oven for controlling the output of the magnetron by varying the number of windings of the high-voltage transformer primary coil, the high output formed in front of the monitor switch A low output relay connected in series with the high output relay at the rear end of the monitor switch and connected in parallel with the middle tap of the high voltage transformer primary coil, and a short interposed between the middle tab and the low output relay at the rear end. Prevention means. The short prevention means is preferably composed of a resistor or a capacitor.

Therefore, even when the door switch is abnormally, that is, even when the door is open, the high voltage transformer is not abnormally operated, thereby eliminating the risk of magnetron oscillation in the open state of the door.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention, the same technology as the prior art will be described by applying the same reference numerals.

Figure 4 is a detailed circuit diagram showing a safety circuit of the wall-mounted microwave oven according to a preferred embodiment of the present invention, Figure 5 is a detailed circuit diagram showing a safety circuit of the wall-mounted microwave oven according to another embodiment of the present invention.

In FIG. 4, the first and second alternating lines L1 and L2 receiving the AC power AC are connected to the primary coil 7a of the high voltage transformer HVT. A ventilation motor 16 and a hood lamp 12 for performing a hood function are connected in parallel between the first and second alternating lines L1 and L2, respectively, and each ventilation motor 16 is connected at each end. And first and second relays RY1 and RY2 for turning on / off the hood lamp 12 are connected. In addition, a cooking lamp CL and a fan motor FM are connected between the first and second alternating lines L1 and L2, and the cooking lamp CL and the fan motor FM are connected to each other. The third relay RY3 for turning on / off is connected. In addition, the door switch SW1 which is turned on / off according to the opening and closing of the door of the cooking chamber 11 is connected to the first alternating line L1 in series to one side of the primary coil 7a of the high voltage transformer HVT. Same as technology.

However, the main feature of the present invention, the monitor switch (SW2) is connected between the first alternating line (L1) and the second alternating line (L2), the second alternating line (L2) in front of the monitor switch (SW2) The high output relay RY10 is formed. In addition, the second output line (L2) behind the monitor switch (SW1) is formed in series with the high output relay (RY10) in parallel with the middle tap (7b) of the high-voltage transformer (HVT) primary coil (7a). A low output relay RY20 connected to is provided. The apparatus further includes a short prevention means 100 interposed between the intermediate tab 7b and the rear end of the low output relay RY20. The short prevention means 100 is preferably composed of a resistor (R10), or as shown in Figure 5 composed of a capacitor (C10).

Looking at the operation of the present invention configured in this way in more detail as follows. While the door is open, the door switch SW1 is turned off and the monitor switch SW2 is turned on. As the door is closed, the door switch SW1 is turned on and the monitor switch SW2 is turned off. When the cooking function is performed while the door is closed as described above, the third relay RY3 is turned on to operate the cooking lamp CL and the fan motor FM. Here, the high output relay RY10 remains on and the low output relay RY20 remains off. Accordingly, the AC power source AC input to the first AC line L1 flows through the intermediate tap 7b of the primary coil 7a. This AC power source AC is guided to the secondary coil 8a to oscillate the magnetron MTG. When the ventilation function is performed in this state, that is, when the first relay RY1 or the second relay RY2 is turned on to operate the ventilation motor 16 or the hood lamp 12, the low output relay RY20 is turned on. ) Is turned on. Therefore, the number of turns of the primary coil 7a of the high voltage transformer HVT is increased to prevent the overcurrent from being applied to the primary coil 7a. At this time, the magnetron MTG of the secondary coil 8a Output decreases. Here, the resistor R10 interposed between the middle tab 7b and the rear end of the low output relay RY20 prevents a short between both ends. This resistor R10 may be comprised by the capacitor | condenser C10 as shown in FIG. On the other hand, when the first relay RY1 or the second relay RY2 is turned off, the low output relay RY20 is turned off again so that the number of turns of the primary coil 7a is reduced, so that the secondary coil 8a is relatively. The output of the magnetron (MGT) is increased through the high output can be obtained. Here, in the state in which an abnormality occurs in the door switch SW1, that is, in the state in which the door switch SW1 is turned on despite the door being opened, the monitor switch SW2 according to the circuit configuration of the present invention can Even if the relay RY10 or RY20 is turned on, the AC power AC input is bypassed so that the high voltage transformer HVT does not operate. Therefore, the high voltage transformer HVT is not abnormally operated, thereby eliminating the risk of magnetron (MGT) oscillation when the door is opened.

According to the safety circuit of the wall-mounted microwave oven according to the present invention as described above, the monitor switch bypasses the AC power input so that the high-voltage transformer is not operated even if any of the high output relay or the low output relay is turned on. Therefore, even when the door switch is in an abnormal state, that is, even when the door is open, the high voltage transformer is not abnormally operated, thereby eliminating the risk of magnetron oscillation in the open state of the door.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

Claims (3)

In the wall-mounted microwave oven that controls the output of the magnetron by varying the number of windings of the high-voltage transformer primary coil, A high output relay formed at the front end of the monitor switch; A low output relay formed in series with the high output relay at a rear end of the monitor switch and connected in parallel with an intermediate tap of the high voltage transformer primary coil; And And a short prevention means interposed between the intermediate tab and the rear end of the low output relay. 2. The safety circuit of a wall-mounted microwave oven according to claim 1, wherein said short prevention means comprises a resistor. 2. The safety circuit of a wall-mounted microwave oven according to claim 1, wherein said short prevention means comprises a condenser.