Active display alignment for multi-display device

1. An active display alignment system comprising:

a display alignment sensing assembly to receive a first signal output from a first display assembly, the display alignment sensing assembly being incorporated into a frame of a head mounted display (HMD) device at a position distal to a face of a user wearing the HMD device;

a waveguide to receive a second signal output from a second display assembly and to redirect the second signal to the display alignment sensing assembly, the display alignment sensing assembly including an optical sensor to receive a combined signal including the first signal and the second signal; and

a display alignment tracker stored in memory of a storage device, the display alignment tracker being executable to detect a positioning disparity between the first signal and the second signal within the combined signal and to output a rendering position adjustment instruction to correct for the detected positioning disparity.

2. The active display alignment system of claim 1 , wherein the display alignment sensing assembly includes a prism combiner positioned to receive the first signal from the first display assembly and the second signal from the waveguide, the prism combiner being configured to combine the first signal with the second signal to generate the combined signal.

3. The active display alignment system of claim 1 , wherein the waveguide is a surface relief grating (SRG) plate.

4. The active display alignment system of claim 1 , wherein the waveguide is an optical fiber.

5. The active display alignment system of claim 1 , wherein the display alignment tracker is further executable to:

determine a corrective adjustment to adjust a rendering position of at least one of the first display assembly and the second display assembly to correct for thermal influences on the waveguide, the combined signal being generated based on the corrective adjustment.

6. The active display alignment system of claim 1 , wherein the second signal received at the waveguide is unaffected by optical elements between the second display assembly and the waveguide.

7. The active display alignment system of claim 1 , wherein the second signal is intercepted by the waveguide while traveling in a first direction and the waveguide redirects the second signal in a direction substantially perpendicular to the first direction.

8. The active display alignment system of claim 1 , wherein the display alignment sensing assembly is adjacent to a region of the frame adapted to rest between an eye and a corresponding ear of the user wearing the HMD device.

9. A method comprising:

directing a first signal received as output from a first display assembly to a display alignment sensing assembly, the display alignment sensing assembly being incorporated into a frame of a head mounted display (HMD) device at a position distal to a face of a user wearing the HMD device;

redirecting a second signal received as output from a second display assembly through a waveguide and toward the display alignment sensing assembly, the display alignment sensing assembly including an optical sensor that receives a combined signal including both the first signal and the second signal;

detecting a positioning disparity between the first signal and the second signal within the combined signal; and

adjusting a rendering position for at least one of the first display assembly and the second display assembly based on the detected positioning disparity.

10. The method of claim 9 , wherein the display alignment sensing assembly includes a prism combiner positioned to receive the first signal from the first display assembly and the second signal from the waveguide, the prism combiner being configured to combine the first signal with the second signal to generate the combined signal.

11. The method of claim 9 , further comprising:

determining a corrective adjustment to reposition at least one of the first display assembly and the second display assembly to correct for thermal influences on the waveguide, the combined signal being generated based on the corrective adjustment.

12. The method of claim 9 , wherein the waveguide is a surface relief grating (SRG) plate.

13. The method of claim 9 , wherein the waveguide is an optical fiber.

14. The method of claim 13 , wherein the optical fiber has an end mated with an aperture in the first display assembly.

15. The method of claim 9 , wherein movement of the waveguide is fixed relative to the first display assembly and not fixed relative to the second display assembly.

16. A head-mounted display (HMD) device comprising:

a frame adapted for wearable attachment to a human head;

a display alignment sensing assembly mounted to the frame at a position distal to a face of a user wearing the HMD device, the first display alignment sensing assembly being positioned to receive a first signal propagating along an output path of a first display assembly;

a waveguide positioned to receive a second signal propagating along an output path of a second display assembly and to redirect the second signal to the display alignment sensing assembly, the display alignment sensing assembly including an optical sensor positioned to receive a combined signal including the first signal and the second signal; and

a display alignment tracker stored in memory and configured to detect a positioning disparity between the first signal and the second signal within the combined signal and to output a rendering position adjustment instruction to correct for the detected positioning disparity.

17. The HMD device claim 16 , wherein the waveguide is a surface relief grating (SRG) plate.

18. The HMD device of claim 16 , wherein the waveguide is an optical fiber.

19. The HMD device of claim 16 , wherein the first signal and the second signal are combined at a merge location proximal to a portion of the frame designed to rest between an eye and an ear of the human head.

20. The HMD device of claim 16 , wherein the second signal received at the waveguide is unaffected by optical elements between the second display assembly and the waveguide.