Head-mounted display device and method of changing light transmittance of the same

1. A method of changing a light transmittance of a head-mounted display device including a display and an optical lens, the method comprising:

identifying an application displayed on the display of the head-mounted display device in front of a portion of the optical lens;

identifying a first light transmittance based on a type of the application or a type of a content of the application;

changing, by a processor, a light transmittance of the optical lens to the first light transmittance; and

displaying the content of the application on the display while the light transmittance of the optical lens is maintained in the first light transmittance.

2. The method of claim 1 , further comprising:

identifying a supply voltage corresponding to the first light transmittance,

wherein the supply voltage is supplied to a light transmission unit included in the head-mounted display device.

3. The method of claim 2 , wherein the light transmission unit includes one of an electrochromic unit, a suspended particle unit, a liquid crystal unit, a photochromic unit, and a thermochromic unit.

4. The method of claim 1 , wherein identifying the first light transmittance includes identifying the first light transmittance further based on information of the application.

5. The method of claim 1 , wherein identifying the first light transmittance includes identifying the first light transmittance further based on at least one of a program manager that manages a life cycle of the application, and an application specification file that includes information of the application.

6. The method of claim 5 , wherein the program manager includes an activity manager or a package manager.

7. The method of claim 1 , wherein the first light transmittance is changeable by a user input.

8. The method of claim 1 , further comprising changing a visibility of the content included in the application to a first visibility corresponding to the first light transmittance.

9. The method of claim 1 , wherein the first light transmittance is changeable in a range from 5% to 95%.

10. The method of claim 1 , further comprising providing at least one of a visual feedback and an auditory feedback to indicate the changing of the light transmittance of the optical lens.

11. A head-mounted display device, comprising:

a display;

a light transmission unit configured to adjust a light transmittance of an optical lens included in the head-mounted display device; and

a controller configured to:

identify an application displayed on the display of the head-mounted display device in front of a portion of the optical lens;

identify a first light transmittance based on a type of the application or a type of a content of the application,

change the light transmittance of the optical lens to the first light transmittance, and

display the content corresponding to the application on the display while the light transmittance of the optical lens is maintained in the first light transmittance.

12. The head-mounted display device of claim 11 , wherein the controller is further configured to supply a supply voltage corresponding to the first light transmittance from a power supply to the light transmission unit.

13. The head-mounted display device of claim 11 , wherein the light transmission unit includes one of an electrochromic unit, a suspended particle unit, a liquid crystal unit, a photochromic unit, and a thermochromic unit.

14. The head-mounted display device of claim 11 , wherein the light transmission unit includes an electrochromic unit, wherein the electrochromic unit includes:

a first Indium Tin Oxide (ITO) layer;

an electrochromic layer on the first ITO layer, wherein a light transmittance of the electrochromic layer is changeable via a supply voltage;

an electrolyte layer on the electrochromic layer;

a second ITO layer on the electrolyte layer; and

a plurality of electrodes connected with the first ITO layer and the second ITO layer, respectively, wherein the supply voltage is input to the plurality of electrodes.

15. The head-mounted display device of claim 11 , wherein the light transmission unit is bonded to one of a front surface and a rear surface of the optical lens.

16. The head-mounted display device of claim 11 , wherein a screen of the content displayed on the display is smaller than the optical lens.