Dynamically controlled focal plane for optical waveguide-based displays

Abstract

Embodiments of the disclosure provide systems and methods for providing a dynamically variable focal plane in a waveguide-based display. Generally speaking, embodiments described herein provide an optical system that allows variable control of the focal length of the image emerging from the display engine into the waveguide. This can be a dynamic system that is controlled based upon the content being projected on the display. For a stereoscopic system, individual control of each eye can be provided. More specifically, embodiments comprise an electrically tunable lens element interposed between the output of the projection engine and the optical waveguide and a control unit to dynamically the tunable lens element to vary the focal length of the images provided to the waveguide display.

What is claimed is: 
     
         1 . A display device comprising:
 a projection display engine generating images;   a waveguide display element receiving the generated images from the projection display engine and rendering the received images on a surface of the waveguide display element visible to a user of the display device;   a variable lens element disposed between the waveguide display element and the projection display engine, the variable lens element adapted to adjust a focal plane of the images rendered on the surface of the waveguide display element visible to a user; and   an electronic control unit electronically coupled with the variable lens element and adapted to control adjustment of the focal plane of the images rendered on the surface of the waveguide display element visible to a user.   
     
     
         2 . The display device of  claim 1 , wherein adjustment of the focal plane of the images rendered comprises a static adjustment based on a user input. 
     
     
         3 . The display device of  claim 1 , wherein adjustment of the focal plane of the images rendered comprises a dynamic adjustment based on a content of the images rendered on the surface of the waveguide display element visible to the user. 
     
     
         4 . The display device of  claim 1 , wherein the waveguide display element comprises a stereoscopic display and wherein the variable lens element independently adjusts the focal plane of images rendered for each eye of the user. 
     
     
         5 . The display device of  claim 1 , further comprising a projection display engine focusing lens disposed adjacent to the projection display engine and wherein the variable lens element is disposed between the waveguide display element and the projection display engine focusing lens. 
     
     
         6 . The display device of  claim 1 , wherein the variable lens element is disposed adjacent to both the waveguide display element and the projection display engine. 
     
     
         7 . The display device of  claim 1 , further comprising an eye tracking system and wherein the electronic control unit receives eye tracking data or instructions from the eye tracking system and controls the variable lens element to adjust the focal plane of the images rendered on the surface of the waveguide display element visible to the user based on the received eye tracking data or instructions. 
     
     
         8 . The display device of  claim 1 , further comprising an Inertial Measurement Unit (IMU) and wherein the electronic control unit receives information or instructions from the IMU indicating a movement of the user and controls the variable lens element to adjust a level of zoom and the focal plane of the images rendered on the surface of the waveguide display element visible to the user based on the received information or instructions from the IMU indicating a movement of the user. 
     
     
         9 . The display device of  claim 1 , wherein the variable lens element comprises a deformable lens having three or more control locations, wherein the electronic control unit maintains a predefined set of control parameters, and wherein the electronic control unit causes the variable lens element to apply a nonuniform force to the deformable lens through the three or more control locations based on the set of control parameters causing the deformable lens to compensate for assembly pitch and yaw misalignments of the variable lens element. 
     
     
         10 . The display device of  claim 1 , further comprising one or more temperature sensors, wherein the electronic control unit maintains a predefined set of temperature correction curves for one or more of the projection display engine, variable lens element, or waveguide display element over a range of operating conditions, wherein the electronic control unit receives electronic input from the one or more temperature sensors and applies one or more temperature correction curves of set of temperature correction curves to a lens control function, the lens control function adjusting the variable lens element and compensating for a temperature indicated by the received electronic input from the one or more temperature sensors based on the applied one or more temperature correction curves. 
     
     
         11 . A control system of a display device, the control system comprising:
 a processor; and   a memory coupled with and readable by the processor and storing therein a set of instructions which, when executed by the processor, causes the processor to control a variable lens element of the display device disposed between a waveguide display element of the display device and a projection display engine of the display device, wherein the processor of the control system controls the variable lens element by:   receiving one or more images generated by the projection display engine and rendered by the waveguide display element on a surface of the waveguide display element visible to a user of the display device;   determining a focal plane for the images rendered on the surface of the waveguide display element visible to the user of the display device based at least in part on content of the received one or more images; and   controlling the variable lens element to adjust rendering of the images on the surface of the waveguide display element visible to the user of the display device based on the determined focal plane.   
     
     
         12 . The control system of  claim 11 , wherein the display device further comprises an eye tracking system and wherein controlling the variable lens element further comprises:
 receiving eye tracking data or instructions from the eye tracking system; and   adjusting the focal plane of the images rendered on the surface of the waveguide display element visible to the user based on the received eye tracking data or instructions.   
     
     
         13 . The control system of  claim 11 , wherein the display device further comprises an Inertial Measurement Unit (IMU) and wherein the controlling the variable lens element further comprises:
 receiving information or instructions from the IMU indicating a movement of the user; and   controlling the variable lens element to adjust a level of zoom and the focal plane of the images rendered on the surface of the waveguide display element visible to the user based on the received information or instructions from the IMU indicating a movement of the user.   
     
     
         14 . The control system of  claim 11 , wherein the variable lens element comprises a deformable lens having three or more control locations, wherein the electronic control unit maintains a predefined set of control parameters, and wherein the electronic control unit causes the variable lens element to apply a nonuniform force to the deformable lens through the three or more control locations based on the set of control parameters causing the deformable lens to compensate for assembly pitch and yaw misalignments of the variable lens element. 
     
     
         15 . The control system of  claim 11 , wherein the display device further comprises one or more temperature sensors, wherein the electronic control unit maintains a predefined set of temperature correction curves for one or more of the projection display engine, variable lens element, or waveguide display element over a range of operating conditions, and wherein controlling the variable lens element further comprises:
 receiving electronic input from the one or more temperature sensors; and   applying one or more temperature correction curves of set of temperature correction curves to a lens control function, the lens control function adjusting the variable lens element and compensating for a temperature indicated by the received electronic input from the one or more temperature sensors based on the applied one or more temperature correction curves.   
     
     
         16 . A method for controlling a display device, the method comprising:
 receiving, by a control unit of the display device, one or more images generated by a projection display engine of the display device and rendered by a waveguide display element of the display device on a surface of the waveguide display element visible to a user of the display device;   determining, by the control unit of the display device, a focal plane for the images rendered on the surface of the waveguide display element visible to the user of the display device based at least in part on content of the received one or more images; and   controlling, by the control unit of the display device, a variable lens element of the display device, the variable lens element disposed between the projection display device and the waveguide display element and wherein the variable lens element adjusts rendering of the images on the surface of the waveguide display element visible to the user of the display device based on the determined focal plane.   
     
     
         17 . The method of  claim 16 , wherein the display device further comprises an eye tracking system and wherein controlling the variable lens element further comprises:
 receiving eye tracking data or instructions from the eye tracking system; and   adjusting the focal plane of the images rendered on the surface of the waveguide display element visible to the user based on the received eye tracking data or instructions.   
     
     
         18 . The method of  claim 16 , wherein the display device further comprises an Inertial Measurement Unit (IMU) and wherein the controlling the variable lens element further comprises:
 receiving information or instructions from the IMU indicating a movement of the user; and   controlling the variable lens element to adjust a level of zoom and the focal plane of the images rendered on the surface of the waveguide display element visible to the user based on the received information or instructions from the IMU indicating a movement of the user.   
     
     
         19 . The method of  claim 16 , wherein the variable lens element comprises a deformable lens having three or more control locations, wherein the electronic control unit maintains a predefined set of control parameters, and wherein the electronic control unit causes the variable lens element to apply a nonuniform force to the deformable lens through the three or more control locations based on the set of control parameters causing the deformable lens to compensate for assembly pitch and yaw misalignments of the variable lens element. 
     
     
         20 . The method of  claim 16 , wherein the display device further comprises one or more temperature sensors, wherein the electronic control unit maintains a predefined set of temperature correction curves for one or more of the projection display engine, variable lens element, or waveguide display element over a range of operating conditions, and wherein controlling the variable lens element further comprises:
 receiving electronic input from the one or more temperature sensors; and   applying one or more temperature correction curves of set of temperature correction curves to a lens control function, the lens control function adjusting the variable lens element and compensating for a temperature indicated by the received electronic input from the one or more temperature sensors based on the applied one or more temperature correction curves.