Refrigerator and method of controlling the same

1. A refrigerator comprising:

a body comprising a storage chamber;

a door that is coupled to the body so as to open/close the storage chamber;

a display that is disposed in at least one region of the door and is configured to be converted between a transparent mode and a display mode, the display comprising a first electrode, a second electrode and photonic crystals, which are filled between the first electrode and the second electrode and of which states vary according to an electric field applied to the photonic crystals;

a controller that controls the display to display at least one among a text, an image, and color when the display is in the display mode; and

an insulation member disposed on a rear surface of the display, the insulation member comprising a first transparent substrate, a second transparent substrate and at least one spacer formed between the first transparent substrate and the second transparent substrate to form a space between the first transparent substrate and the second transparent substrate, the space being in a vacuum state,

wherein the controller controls the display to be converted into a reflection mode, a display mode, a transparent mode and an opaque mode based on a selection by a user, and

wherein each of the reflection mode, the display mode, the transparent mode and the opaque mode are different from each other.

2. The refrigerator of claim 1 , wherein the display is a reflective display that does not comprise a light source therein.

3. The refrigerator of claim 1 , wherein in the opaque mode a memo is input by the photonic crystals in the display.

4. The refrigerator of claim 1 , wherein in the reflection mode the display is used as a mirror by the photonic crystals.

5. The refrigerator of claim 1 , further comprising an illumination unit disposed in the storage chamber,

wherein the controller controls the display to turn on the illumination unit when the display is in a transparent mode.

6. The refrigerator of claim 3 , further comprising an input unit to which selection of the reflection mode, the transparent mode, the display mode or the opaque mode is input,

wherein the controller controls the display to be converted into the reflection mode, the transparent mode, the display mode or the opaque mode according to selection input to the input unit.

7. The refrigerator of claim 6 , wherein the display displays the memo input by a user in the opaque mode.

8. The refrigerator of claim 7 , wherein the input unit is configured so that selection of reset is further input to the input unit, and

the controller deletes the memo displayed on the display when selection of reset is input to the input unit.

9. The refrigerator of claim 7 , further comprising a touch panel disposed on a front surface of the display,

wherein the memo is input through the touch panel.

10. The refrigerator of claim 9 , further comprising a memory device for storing the input memo.

11. The refrigerator of claim 1 , wherein, if a reference time elapses after the display is converted into the transparent mode, the controller converts the display into the display mode.

12. The refrigerator of claim 1 , further comprising a sensing sensor that senses a user's access to the refrigerator,

wherein, if the user's access to the refrigerator is sensed, the controller converts the display into the transparent mode, and if it is sensed that the user is distant from the refrigerator, the controller converts the display into the display mode.

13. The refrigerator of claim 1 , further comprising a circular polarizer disposed behind the display.

14. The refrigerator of claim 13 , wherein the circular polarizer comprises a quarter wavelength plate and a linear polarizer.