Patent ID: 9671612
Date: 2017-06-06
CPC Classifications: G02B,G02F

Claim:
1. A Head Mounted Display (“HMD”) comprising: a display module to generate image light; an optical combiner for combining the image light with external scene light, wherein the optical combiner includes a reflective element coupled to receive the image light and to direct the image light towards an eyeward region; a tunable lens positioned to receive the image light and configured to adjust a focal length of the tunable lens to focus the image light at varying focus depths; and control circuitry configured to output a focus signal to control adjusting the focal length of the tunable lens, to control the display module to include at least a first image and a second image in the image light, and to select a first focal length of the tunable lens when the first image is included in the image light and a second focal length of the tunable lens when the second image is included in the image light, the first focal length being different from the second focal length, wherein the control circuitry is configured to control the display module to display the first image with the tunable lens at the first focal length during a first time period, display no image as the tunable lens is adjusted from the first focal length to the second focal length during a second time period, and display the second image with the tunable lens at the second focal length during a third time period, and wherein the control circuitry is configured to control the display module to display the first image and the second image towards the eyeward region and to superimpose the first image on the second image.