Over-the-range microwave oven and method of using the same

1. An over-the-range microwave oven comprising:

a housing;

an electric equipment chamber which is disposed in the housing, and includes a control panel and a drive unit;

a cooking chamber which is disposed in the housing and is controlled by the electric equipment chamber, and has an air inlet portion which is disposed at one side of the cooking chamber and into which outside air flows, and an opening and closing unit which is disposed at the other side of the cooking chamber, opposite the one side, that is opened and closed based on a flow rate of flowing air;

a heater unit which is disposed in a chamber selected from the group consisting of the electric equipment chamber and the cooking chamber; and

a duct unit in the housing and disposed outside the cooking chamber, wherein the opening and closing unit includes a discharge hole which is formed in a wall at the other side of the cooking chamber, and an opening and closing plate which is hingedly coupled outside the wall.

2. The over-the-range microwave oven of claim 1 , wherein the opening and closing plate is disposed above the discharge hole and closes the discharge hole using its own weight.

3. The over-the-range microwave oven of claim 1 , wherein the opening and closing plate is disposed at a lateral side of the discharge hole, and a flat spring is disposed at a position where the opening and closing plate is hingedly coupled, such that the discharge hole is closed by the restoring force of the flat spring.

4. The over-the-range microwave oven of claim 1 , wherein a motor is disposed at a position where the opening and closing plate is hingedly coupled, such that the opening and closing plate opens and closes the discharge hole by operation of the motor.

5. The over-the-range microwave oven of claim 1 , wherein the heater unit includes an electric heater which is disposed in the electric equipment chamber to correspond to the air inlet portion, and a fan which is disposed at the rear of the electric heater and allows air heated by the electric heater to flow to the air inlet portion.

6. The over-the-range microwave oven of claim 1 , wherein the heater unit includes a halogen lamp which is disposed on a surface selected from the group consisting of an upper surface of the cooking chamber, and a lateral side surface of the cooking chamber.

7. The over-the-range microwave oven of claim 6 , wherein two or more halogen lamps are disposed on the upper surface of the cooking chamber.

8. The over-the-range microwave oven of claim 6 , wherein two or more halogen lamps are disposed on one side surface or both lateral side surfaces of the cooking chamber.

9. The over-the-range microwave oven of claim 1 , further comprising:

a convection plate which is disposed on a food accommodating portion at the bottom of the cooking chamber and allows hot air flowing from the air inlet portion to flow upward.

10. The over-the-range microwave oven of claim 9 , wherein the convection plate includes:

a supporting portion which is supported on the bottom of the cooking chamber;

a concave portion which is supported by the supporting portion and is opened upward; and

a convection portion which is disposed on the concave portion so as to support food and that allows air flowing into the concave portion to flow upward.

11. The over-the-range microwave oven of claim 10 , wherein a reflective plate is disposed on an upper surface of the concave portion which faces the convection portion.

12. The over-the-range microwave oven of claim 11 , wherein the reflective plate comprises a ceramic coated layer.

13. The over-the-range microwave oven of claim 10 , wherein the convection portion includes a plurality of circular and concentric supporting ribs and a plurality of cross ribs which have one end connected at the center of the convection portion and the other end connected to the outermost supporting rib and are coupled to the plurality of supporting ribs.

14. The over-the-range microwave oven of claim 13 , wherein the plurality of cross ribs each curve in the same direction, and are disposed at equal intervals.