EP0981265A1 - Four à micro-ondes comportant une sécurité protégeant le transformateur haute tension - Google Patents
Four à micro-ondes comportant une sécurité protégeant le transformateur haute tension Download PDFInfo
- Publication number
- EP0981265A1 EP0981265A1 EP99302489A EP99302489A EP0981265A1 EP 0981265 A1 EP0981265 A1 EP 0981265A1 EP 99302489 A EP99302489 A EP 99302489A EP 99302489 A EP99302489 A EP 99302489A EP 0981265 A1 EP0981265 A1 EP 0981265A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- voltage transformer
- rectifying
- power
- microwave oven
- current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
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Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/66—Circuits
- H05B6/666—Safety circuits
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/66—Circuits
- H05B6/68—Circuits for monitoring or control
Definitions
- the present invention relates to a microwave oven including a high-voltage transformer and overcurrent protection means for protecting the high-voltage transformer from an initial overcurrent condition, the overcurrent protection means comprising a resistor in series between a power in terminal and a primary winding of the high-voltage transformer and a relay in parallel with the resistor.
- FIG. 2 is a circuit diagram of a known power control circuit of a microwave oven.
- the microwave oven has a power supply part 101, a high-voltage transformer 109 for stepping up the normal voltage from the power supply part 101 to a high level and a magnetron 110 for generating microwaves which is powered from the output of high-voltage transformer 101.
- a thermal switch 103 responsive to the temperature in the cooking chamber (not shown), a door switch 105 responsive to opening and closing of the oven door (not shown) and a monitor switch 107 for controlling supply of power to said high-voltage transformer 109 on the basis of the states of the thermal and door switches 103, 105 are connected between the power supply part 101 and the high-voltage transformer 109.
- the thermal switch 103 is disposed between the power supply part 101 and the monitor switch 107
- the door switch 105 is disposed between the power supply part 101 and the high-voltage transformer 109.
- An overcurrent protection relay 121 connected in series between the door switch 105 and the high-voltage transformer 109.
- An overcurrent protection resistance unit 123 is connected in parallel with the overcurrent protection relay 121.
- the coil 115 of the relay 121 is connected in parallel with the monitor switch 107.
- the monitor switch 107 has a bypass connecting node 131 and a branch connecting node 133.
- the bypass connecting node 131 is a point on a bypass line 130 disposed between the relay coil 115 and the high-voltage transformer 109, for supplying power from said power supply part 101 to the bypass line 130.
- the branch connecting node 133 is a point on the line connected to the high-voltage transformer 109 for supplying power to the relay coil 115 and the high-voltage transformer 109.
- the thermal and door switches 103, 105 are closed.
- the moving contact of the monitor switch 107 contacts the branch connecting node 133 and the power supply part 101 is connected in series with the overcurrent protection resistance unit 123 and the high voltage transformer 109. Therefore, the initial current supplied from said power supply part 101 is reduced by the overcurrent protection resistance unit 123.
- the relay coil 115 is energised and the overcurrent protection relay 121 is closed.
- an overcurrent protection relay is operated when AC power is applied.
- the AC power changes regularly and periodically. Therefore, the known microwave oven has a shortcoming in that the operation of the overcurrent protection relay becomes unstable.
- a microwave oven according to the present invention is characterised by rectifying means for rectifying current input to the oven for energising the coil of the relay.
- an oven according to the present invention includes smoothing means for smoothing the output of the rectifying circuit.
- the rectifying means comprises a bridge rectifier and the smoothing means comprises a capacitor in parallel with said coil.
- resistor means is included for reducing the voltage of the current to be rectified by the rectifying means.
- a microwave oven has a power supply part 1, a magnetron 10 for generating microwaves and a high-voltage transformer 9 for stepping up mains voltage to a high level.
- a thermal switch 3 responsive to the temperature in the cooking chamber (not shown) and a door switch 5 responsive to opening and closing of the oven door (not shown) and a monitor switch 7 for controlling the supply of power to the high-voltage transformer 9 on the basis of the states of the thermal and door switches 3, 5 are connected between said power supply part 1 and the high-voltage transformer 9.
- the thermal and door switches 3, 5 are connected in series between the power supply part 1 and the high-voltage transformer 9.
- the power control device further comprises an overcurrent protection relay 21 disposed in series between the thermal and door switches 3, 5, an overcurrent protection resistance unit 23 connected in parallel with the overcurrent protection relay 21, and a rectifying part 8 for rectifying the current from the power supply part 1.
- the rectifying part 8 has at least one voltage-controlled resistor 13, a bridge diode 11 connected to said voltage-controlled resistor 13, a capacitor 17 connected in parallel with the bridge diode 11, and the coil 15 of the overcurrent protection relay 21.
- the monitor switch 7 has a bypass connecting node 31 and a branch connecting node 33.
- the bypass connecting node 31 is a point on a bypass line 30 disposed between the relay coil 15 and the high-voltage transformer 9.
- the branch connecting node 3 is a point on the line connected to the high-voltage transformer 9 for supplying power to the relay coil 15 and the high-voltage transformer 9.
- the thermal and door switches 3, 5 are closed.
- the moving contact of the monitor switch 7 contacts the branch connecting node 33. Because the current supplied from the power supply part 1 passes through the overcurrent protection resistance unit 23, the initial current is reduced and at the same time, the current branched to said rectifying part 8 is rectified so that stable current is supplied to the relay coil 15. This causes the overcurrent protection relay 21 to close shortly after current begins to flow through the primary winding of the high-voltage transformer 9.
- the high-voltage transformer is protected from an initial overcurrent condition and the overcurrent protection relay is controlled by induction energy generated from the relay coil by use of a stable current.
- the inrush relay is controlled by a stable current, and thus, the reliability is improved.
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Control Of High-Frequency Heating Circuits (AREA)
- Emergency Protection Circuit Devices (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1019980033738A KR100271362B1 (ko) | 1998-08-20 | 1998-08-20 | 전자렌지의 전원제어장치 및 전원제어방법 |
KR3373898 | 1998-08-20 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0981265A1 true EP0981265A1 (fr) | 2000-02-23 |
EP0981265B1 EP0981265B1 (fr) | 2004-06-30 |
Family
ID=19547701
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99302489A Expired - Lifetime EP0981265B1 (fr) | 1998-08-20 | 1999-03-30 | Four à micro-ondes comportant une sécurité protégeant le transformateur haute tension |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0981265B1 (fr) |
KR (1) | KR100271362B1 (fr) |
DE (1) | DE69918380T2 (fr) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150146459A1 (en) * | 2012-10-31 | 2015-05-28 | Zte Corporation | High-voltage protection circuit, high-voltage protection method and power supply |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20010081569A (ko) * | 2000-02-16 | 2001-08-29 | 윤종용 | 전자렌지의 전원제어장치 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1239789A (en) * | 1968-10-31 | 1971-07-21 | Dysona Ind Ltd | Improvements relating to microwave ovens |
FR2066097A5 (fr) * | 1970-10-12 | 1971-08-06 | Matsushita Electric Ind Co Ltd | |
US4556773A (en) * | 1981-03-20 | 1985-12-03 | Matsushita Electric Industrial Co., Ltd. | High frequency heating appliance having protection against rush currents |
FR2765040A1 (fr) * | 1997-06-19 | 1998-12-24 | Daewoo Electronics Co Ltd | Circuit de protection vis-a-vis des courants de demarrage, notamment pour four a micro-ondes |
-
1998
- 1998-08-20 KR KR1019980033738A patent/KR100271362B1/ko not_active IP Right Cessation
-
1999
- 1999-03-30 DE DE69918380T patent/DE69918380T2/de not_active Expired - Lifetime
- 1999-03-30 EP EP99302489A patent/EP0981265B1/fr not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1239789A (en) * | 1968-10-31 | 1971-07-21 | Dysona Ind Ltd | Improvements relating to microwave ovens |
FR2066097A5 (fr) * | 1970-10-12 | 1971-08-06 | Matsushita Electric Ind Co Ltd | |
US4556773A (en) * | 1981-03-20 | 1985-12-03 | Matsushita Electric Industrial Co., Ltd. | High frequency heating appliance having protection against rush currents |
FR2765040A1 (fr) * | 1997-06-19 | 1998-12-24 | Daewoo Electronics Co Ltd | Circuit de protection vis-a-vis des courants de demarrage, notamment pour four a micro-ondes |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150146459A1 (en) * | 2012-10-31 | 2015-05-28 | Zte Corporation | High-voltage protection circuit, high-voltage protection method and power supply |
US9343951B2 (en) * | 2012-10-31 | 2016-05-17 | Zte Corporation | High-voltage protection circuit, high-voltage protection method and power supply |
Also Published As
Publication number | Publication date |
---|---|
EP0981265B1 (fr) | 2004-06-30 |
DE69918380D1 (de) | 2004-08-05 |
KR100271362B1 (ko) | 2000-11-01 |
DE69918380T2 (de) | 2005-08-11 |
KR20000014346A (ko) | 2000-03-06 |
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