US Patent 9087471 Adaptive brightness control of head mounted display

A technique for adaptive brightness control of an eyepiece of a head mounted display (“HMD”) includes displaying a computer generated image (“CGI”) to an eye of a user from a viewing region of the eyepiece of the HMD. Image data is captured from an ambient environment surrounding the HMD. A brightness value is calculated for the ambient environment based at least in part upon the image data. A bias power setting is determined based at least in part upon the brightness value. The bias power setting is applied to an illumination source for generating the CGI and a brightness level of the CGI displayed to the eye of the user is controlled with the bias power setting.