Title of Invention

MICROWAVE OVEN WITH TURNTABLE & SWINGABLE ELECTRICAL HEATER

Abstract

This invention is related to a microwave oven which has the first heating means installed at an upper portion of a cooking chamber and the second heating means installed at a lower portion of the cooking chamber, such that a structure of the microwave oven is simplified. Particularly, the invention includes a main body having a door and a cooking chamber insulated from a microwave, a magnetron installed in the main body for generating the microwave and providing the microwave to an inside of the cooking chamber, a first heating means installed at an upper portion of the cooking chamber for heating an upper portion of food, and a second heating means installed at a lower portion of the cooking chamber for heating a lower portion of the food.

Full Text

SPECIFICATION 1. TITLE OF THE INVENTION Microwave Oven 2. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front-sectional view of a general microwave oven. FIG. 2 is a cross-sectional view of a microwave oven according to the present invention. FIG. 3 is a cross-sectional view of the first heating means. FIG. 4 is a sectional view taken along lines A-A of FIG. 3. FIG. 5 is a perspective and exploded view of the second heating means according to the present invention. FIG. 6 is a top-sectional view of the microwave according to the present invention. *Description of the reference numbers designated at several portions of the drawings 10: main body 10a: rear plate of body 11: cooking chamber 11a: ceiling plate of cooking chamber 11b: floor plate of cooking chamber 11c: side plate of cooking chamber 11d: rear plate of cooking chamber 12: door 13: turntable 14: guide 15: motor 17: magnetron 20: first heating means 21: heater 22: bushing 23: bracket 23a: protrusion 25: guiding plate 25 a: groove 30: second heating means 31: thermal-radiating hole 32: case 33: heater 40, 41: thermal insulation layer 50: bio-ceramic 3. DETAILED DESCRIPTION OF THE PRESENT INVENTION The present invention is related to a microwave oven, more particularly to a microwave oven which has the first heating means installed at an upper portion of a cooking chamber and the second heating means installed at a lower portion of the cooking chamber, such that a structure of the microwave oven is simplified. Generally, as shown in FIG. 1, a microwave oven includes a main body 1, a cooking chamber 2, and a turntable 3. The main body 1 substantially has a rectangular shape. The cooking chamber 2 is formed in the main body 1 to prevent a propagation of microwave. And, the turntable 3 on which food is put is rotated by a motor 4 installed in the cooking chamber 2. Further, the microwave oven includes a magnetron 5, a high voltage transformer 7, a cooling fan 6, a heater 8, and a hot blown air heater 8a. The magnetron 5 generates a high frequency wave and provides the high frequency wave into the cooking chamber 2. The high voltage transformer 7, which is installed in the main body 1, applies a high voltage to the magnetron 5. The cooling fan 6 is installed in the main body 1 for cooling the magnetron 5 and the high voltage transformer 7. The heater 8 and the hot blown air heater 8a are respectively installed at an upper portion and a rear portion of the cooking chamber 2 to cook food with hot air. The above prior microwave oven allows a user to cook food by various cooking methods that, for example, include an oven cooking in which only the magnetron 5 is used, a grill cooking in which food is heated by both the heater 8 and the hot blown air heater 8a, and convection cooking in which the oven and a grill are operated simultaneously. That is, in the oven cooking, when the magnetron 5 is operated such that food is put on the turntable 3, the high frequency wave oscillates in the cooking chamber 2. At this time, the food is heated as the high frequency wave is directly propagated into the food. In the grill cooking, the food is grilled by the heater 8. Also, when the hot blown air heater 8a is driven, air is provided to the hot blown air heater 8a by a fan. As the air passes through the hot blown air heater 8a, the air is converted into a hot blown air. Then, the hot blown air is introduced into the cooking chamber 2 through a hot blown air circulating hole 8d, such that the food in the cooking chamber 2 is indirectly grilled. However, since lower portions of the food are not heated, the grill cooking has the defect that the food is not uniformly grilled. That is, since the heater 8 is placed over the food when the food is on the turntable 3, the lower portions of the food are not exposed to the heater 8. Therefore, it is a problem that the food is grilled partially. Also, in the convection cooking, a width between the turntable 3 and a bottom plate 9 of the cooking chamber is so narrow that a sufficient quantity of the hot blown air generated by the hot blown air heater 8a is not introduced into the cooking chamber 2. So, in case of foods, such as bread, cookie, etc., cooked particularly by the hot blown air, the bottoms of the foods are not heated. For overcoming the above problem, while cooking food, the food must be made turned over. Recently, there has been proposed a technique for grilling food uniformly in which a grill at which the food is fixed is rotated. However, the prior technique has resulted in structural complexity. Also, it is very dangerous to turn the food over during cooking because the temperature in the cooking chamber during cooking is very high. On the other hand, the hot blown air heater 8a is operated in the convection cooking. While the hot blown air is introduced into the cooking chamber 2, if external air enters the cooking chamber 2, the temperature in the cooking chamber 2 may decrease. Thus, a suction hole 8b is formed at a side wall of the cooking chamber 2. The suction hole 8b is either opened or closed by a damper 8c so that external air can not enter. This causes the structure to be complicated and curtails the production efficiency for reasons of assembling the damper 8c and the suction hole 8b. Further, since the heater 8 is fixed on the upper portion of the cooking chamber 2, it is difficult to clean up the ceiling of the cooking chamber 2. That is, when cooking foods and the cooking chamber 2 is splattered with oil causing contamination or it becomes sooty by smoke, though it is possible to clean up the bottom and the side walls of the cooking chamber 2, it is difficult to clean up the ceiling because of obstruction by the heater 8 fixed at the ceiling. Also, when a height of food is low, this structure is very inefficient since it takes much more heat to cook the food distant from the heater 8. Further, since it takes up a larger space to install the hot blown air heater 8a at the back of the rear plate of the cooking chamber 2, this structure is restricted in space and is not economical. Taking the above problems into consideration has resulted in this invention, and one object of this invention is to provide a microwave oven of which structure is simplified. The microwave oven includes a first heating means installed at an upper portion of a cooking chamber for heating an upper portion of food and a second heating means installed at a lower portion of the cooking chamber for heating a lower portion of the food which is placed on a turntable. It is another object of the present invention to provide a microwave oven which can separate the first heating means from the ceiling of the cooking chamber by allowing the first heating means to pivot, such that it is possible to clean the cooking chamber and to transfer the first heating means closer to a low level of food for cooking the food with a small amount of heat. In order to achieve the above objects, the present invention includes a main body having a cooking chamber which is opened or closed by a door, a magnetron for generating a high frequency microwave and outputting the high frequency microwave to the inside of the cooking chamber, a first heating means installed at an upper portion of the cooking chamber for heating an upper portion of food, and a second heating means installed at an lower portion of the cooking chamber for heating a lower portion of the food. Preferred embodiments of the present invention will be illustrated below with reference to the accompanying drawings. FIG. 2 is a cross-sectional view of a microwave oven according to the present invention. In FIG. 2, the microwave oven includes a main body 10, a cooking chamber 11, a door 12, and a turntable 13. The main body 10 is substantially rectangular shaped. The cooking chamber 11 is formed in the main body 10. The cooking chamber 11 has an openning on the front side through which food is inputted to or outputted from the cooking chamber 11. The door 12 is installed at the opened front side to open or close the cooking chamber 11. When the door 12 is closed and microwaves are generated, the door 12 prevents the microwaves from escaping the cooking chamber 11 to the outside. The turntable 13 on which food is put is mounted on a floor plate of the cooking chamber 11 and able to rotate. On the other hand, the turntable 13 is driven by a motor 15 which is installed at a motor fixing bracket 15b. A rotary shaft 15a of the motor 15 is connected with a bearing 16 installed at the central portion of the turntable 13, such that a turning effect of the motor 15 is transferred to a guide 14. Further, the plurality of wheels are radially installed at a lower surface of the guide 14. The turntable 13 is mounted on the guide 14. The first heating means 20 is installed at an upper portion of the cooking chamber 11. The second heating means 30 is installed under the inside of the main body 10 to heat a lower portion of food. The second heating means 30 heats the lower surface of the turntable 13 which is in contact with the guide 14, such that the food on the turntable 13 is indirectly heated. Upper and lower surfaces of the turntable 13 and the guide 14 are coated with a bio-ceramic material 50, respectively. The bio-ceramic coatings are heated to radiate far-infrared rays as the second heating means 30 heats the lower surface of the turntable 13. When the far- infrared rays are radiated to the food on the turntable, the food is activated to cause the lower surface of food to be heated uniformly, such that the cooking efficiency is improved. Thermal insulation layers 40 and 41 are formed by charging a ceiling plate 11a and a rear plate lid of the cooking chamber with air, such that a thermal loss is reduced while the first and second heating means 20 and 30 operate. FIG. 3 is a cross-sectional view of the first heating means, and FIG. 4 is a sectional view taken along lines A-A of FIG. 3. The first heating means 20 includes a heater 21, a bushing 22, a bracket 23, a guiding plate 25, and a protrusion 23a. The heater 21 heats up when electric power is applied to the heater 21. The bushing 22 is formed at one side end of the heater 21 and allows the heater 21 to be able to pivot thereon. The bracket 23 fixes the bushing 22 on a side plate 11c of the cooking chamber to pivot thereon. The bracket 23 is fixed on the side plate 11c by means of a fixing screw 24a. The protrusion 23a is formed at one side of the bracket 23 to be locked into a pair of grooves 25a which are formed at one side of the guiding plate 25 at an angle. That is, when the protrusion 23a is inserted into an upper groove 25a, the heater 21 is level with the ceiling plate 11a of the cooking chamber. And, when the protrusion 23a is inserted into a lower groove 25a, the heater 21 becomes more distant from the ceiling plate 11a of the cooking chamber, such that it is easy to clean the ceiling plate 11a. Furthermore, when the heater 21 is lowered in position, efficiency to heat a lower level of food improves. Also, the bracket 23 is upwardly inclined toward the guide plate 25, such that the protrusion 23a adheres closely to the grooves 23. FIG. 5 is a perspective and exploded view of the second heating means according to the present invention. The second heating means includes a plurality of thermal-radiating holes 31, a case 32 and a heater 33. The plurality of thermal-radiating holes 31 are formed at the floor plate 11b of the cooking chamber. The plurality of thermal-radiating holes 31 are formed to prevent small fragments from inputting to the second heating means when cleaning the floor plate 11b of the cooking chamber toward the lower surface of the guide 14. The case 32 is fixed on the lower surface of the floor plate 11b of the cooking chamber to surround the plurality of thermal-radiating holes 31. The heater 33 is installed in the case 32 to be heated by applying electric power thereto. On the other hand, a pair of hooking projections 32b are formed at a rear portion of an upper end of the case 32. The pair of hooking projections 32b are coupled with a pair of hooking jaws 34 formed on the floor plate 11b of the cooking chamber. A forward portion of the upper end is fixed on the floor plate 11b of the cooking chamber by a screw 35. The heater 33 is substantially U-shaped. The heater 33 is inserted into a hole 32a which is formed at one side of the case 32, and is fixed on the case 32. FIG. 6 is a top-sectional view of the microwave according to the present invention. In FIG. 6, a magnetron is installed at one side plate 11c of the cooking chamber for generating a high frequency microwave and providing the microwave into the cooking chamber 11. A fan 18 and a motor 19 are installed at the rear plate 11d of the cooking chamber 11 for blowing air into the cooking chamber 11. And, the side plate 11c of the cooking chamber 11c has a plurality of holes 11e through which the blowing air is introduced to the cooking chamber 11. In the above construction according to the present invention, when the door 12 is closed after food is placed on the turntable 13, the cooking chamber 11 is sealed from the outside. At this time, the plurality of thermal-radiating holes 31 formed at the floor plate 11b of the cooking chamber are covered by the case 32, such that leakage of microwave is prevented. When the magnetron 17 is operated, the microwave is emitted into the cooking chamber 11 to propagate into the food. The microwave causes the food to be activated, such that the food is cooked. On the other hand, as the bearing 16 is rotated by the motor 15, the guide 14 is rotated with the turntable 13. Since the turntable 13 rotates, the microwave is uniformly applied to the food, such that cooking efficiency improves. Upon putting food on the turntable 13 closely adhering to the guide 14 in a grill cooking, when the first heating means 20 is operated, upper portions of the food are heated by the heater 21 heating. At this time, when the second heating means 30 is operated, the lower portion of turntable 13 is heated through the guide 14 by the heater 33 heating. That is, when the heater 33 is heated, thermal air spreads through the plurality of thermal-heating holes 31 into the cooking chamber 11, such that the turntable 13 which is placed over the plurality of thermal-heating holes 31 is heated. When the turntable 13 is heated, the lower portion of the food put on the turntable 13 is heated to cook the food uniformly. Since, the turntable 13 is rotated, and at the same time the thermal air passes through the plurality of thermal-heating holes 31, the lower portion of the food is not heated partially. As the lower surface of the turntable 13 is heated by the heater 33, the bio-ceramic 50 coated on the lower surface is heated to generate a far-infrared. The far-infrared is radiated into the food, such that the cooking efficiency improves. Further, according to the present invention, it is possible to cook various menus. That is, in convection cooking, it is possible to operate either the heater 21 at the upper portion and the magnetron 17 or the heater 33 at the lower portion and the magnetron 17. And, the convection cooking may be performed by operating the magnetron 17 and the two heaters 21 and 33 at the same time. On the other hand, in grill cooking, it is possible to control the cooking state of food by selectively operating the heater 33 at the lower portion. Further, only by operating the heater 33 at the lower portion, fermentation of food is possible. That is, since the heater 33 at the lower portion heats the lower surface of the turntable 13, the food on the turntable 33 is indirectly heated to make it possible to ferment the food. After completing the grill cooking and when cleaning the cooking chamber 11, since the heater 21 can be moved away from the ceiling plate 11a by rotating the heater 21 step by step, the cooking chamber 11 can be conveniently cleaned. It is possible to cook the food with efficiency by controlling the position of heater 21 according to the height of food, such that thermal efficiency is improved. As above mentioned, according to the present invention, during grill cooking, the upper and lower portions of food are uniformly grilled by selectively operating the lower heater while the upper heater is operated. Since there is no need of a barbecue function to rotate food whole, the structure of the microwave oven is simplified. And, the microwave oven according to the present invention has the effect of providing various cooking methods, such as food fermentation using only the lower heater. Further, while prior microwave oven needs a space for installing a thermal-blown air heater at a rear portion of a cooking chamber, a microwave oven according to the present invention does not need any space for installation, such that a reduction infthe volume of the microwave oven occurs. 4. What is claimed is: 1. A microwave oven comprising: a main body 10 having a door 12 and a cooking chamber 11 insulated from a microwave; a magnetron 17 installed in the main body 10 for generating the microwave and providing the microwave to an inside of the cooking chamber 11; a first heating means 20 installed at an upper portion of the cooking chamber 11 for heating an upper portion of food; and a second heating means 30 installed at a lower portion of the cooking chamber 11 for heating a lower portion of the food. 2. The microwave oven as claimed in claim 1, further comprising a thermal insulation layer 40 which is formed by charging a ceiling plate 11a of the cooking chamber with air for shutting off heat from the first heating means 20; and a thermal insulation layer 41 which is formed by charging a rear plate 11d of the cooking chamber with air for shutting off heat from the second heating means 30. 3. The microwave oven as claimed in claim 1, further comprising a turntable 13 which is installed at a lower portion of an inside of the cooking chamber 11 for placing food thereon; a motor 15 which is installed at a lower portion of the cooking chamber 11 of the main body 10 for rotating the turntable 13; and a guide 14 which is fixed at a lower portion of the turntable 13, the guide 14 having a plurality of wheels 14a which are radially formed. 4. The microwave oven as claimed in claim 3, further comprising a bio-ceramic 50 coated on a lower surface and an upper surface of the turntable 13, the bio-ceramic 50 for radiating a far-infrared when the bio-ceramic is heated by the second heating means 30. 5. The microwave oven as claimed in claim 1, wherein said first heating means 20 includes a bushing 22 installed at a bracket 23 to be rotatable, the bracket fixed on the side plate 11c of the cooking chamber; a heater 21 formed at an upper portion of the inside of the cooking chamber 11 and connected with the bushing 22, the heater 21 heated when electric power is applied to the heater 21; a guiding plate 25 fixed on the bushing 22, the guide plate 25 being in contact with the bracket 23, the guiding plate 25 having a pair of grooves 25a formed at an upper and lower sides of one side surface thereof, respectively; and a protrusion 23a formed at an upper side of the bracket 23 and locked into the pair of grooves 25a. 6. The microwave oven as claimed in claim 3, wherein said second heating means includes a plurality of thermal-radiating holes 31 formed at a floor plate 11b of the cooking chamber 11, wherein an opening direction of the plurality of thermal-radiating holes 31 is toward the turntable 13; a case 32 adhered to the floor plate 1 lb to surround the plurality of thermal-radiating holes 31; and a heater 33 installed inside of the case 32, the heater 33 heated when electric power is applied to the heater 33. ABSTRACT This invention is related to a microwave oven which has the first heating means installed at an upper portion of a cooking chamber and the second heating means installed at a lower portion of the cooking chamber, such that a structure of the microwave oven is simplified. Particularly, the invention includes a main body having a door and a cooking chamber insulated from a microwave, a magnetron installed in the main body for generating the microwave and providing the microwave to an inside of the cooking chamber, a first heating means installed at an upper portion of the cooking chamber for heating an upper portion of food, and a second heating means installed at a lower portion of the cooking chamber for heating a lower portion of the food.

Documents:

2030-CAL-1996-ASSIGNMENT.pdf

2030-CAL-1996-CORRESPONDENCE 1.1.pdf

2030-CAL-1996-CORRESPONDENCE.pdf

2030-CAL-1996-EXAMINATION REPORT.pdf

2030-CAL-1996-FORM 1.pdf

2030-CAL-1996-FORM 3.pdf

2030-CAL-1996-FORM 5.pdf

2030-CAL-1996-FORM 6.pdf

2030-CAL-1996-FORM 9.pdf

2030-CAL-1996-GRANTED-ABSTRACT.pdf

2030-CAL-1996-GRANTED-CLAIMS.pdf

2030-CAL-1996-GRANTED-DESCRIPTION (COMPLETE).pdf

2030-CAL-1996-GRANTED-DRAWINGS.pdf

2030-CAL-1996-GRANTED-FORM 1.pdf

2030-CAL-1996-GRANTED-FORM 2.pdf

2030-CAL-1996-GRANTED-LETTER PATENT.pdf

2030-CAL-1996-GRANTED-SPECIFICATION.pdf

2030-CAL-1996-OTHERS.pdf

2030-CAL-1996-PA.pdf

2030-CAL-1996-PRIORITY DOCUMENT.pdf

2030-CAL-1996-REPLY TO EXAMINATION REPORT.pdf

2030-CAL-1996-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf