Facebook Patent | Scanned MicroLED array for waveguide display

Patent: Scanned MicroLED array for waveguide display

Publication Number: 10157559

Publication Date: 2018-12-18

Applicants: Facebook

Abstract

A waveguide display includes a source assembly, an output waveguide, and a controller. The source assembly includes a light source and an optics system. The light source includes source elements arranged in a 1D or 2D array that emit image light. The optics system includes a scanning mirror assembly that scans the image light to particular locations based on scanning instructions. The output waveguide receives the scanned image light from the scanning mirror assembly and outputs an expanded image light. In some embodiments, the waveguide display includes a source waveguide and the 1D array of source elements. The source waveguide receives a conditioned image light from the source assembly. The controller generates the scanning instructions and provides the scanning instructions to the scanning mirror assembly. In some embodiments, the controller provides the scanning instructions to an actuator assembly of the source waveguide.

Background

This disclosure relates generally to near-eye-displays, and in particular, to near eye displays including scanning MicroLED arrays.

In conventional display designs in near-eye-displays, the common factors considered are brightness, resolution/FOV, and compactness. In augmented reality (AR) applications using next generation displays, often a wideband source is preferable than single wavelength laser. MicroLEDs are a good choice for such displays due to their wide spectrum and high brightness. But the small array size in MicroLED technology limits a simple 2D display resolution to about 640.times.480. In addition, the display size is also large due to large pixel pitch and low fill factor of the array.

Summary

A waveguide display used as part of a virtual reality (VR) system, an augmented reality (AR) system, a mixed reality (MR) system, or some combination thereof. In some embodiments, the waveguide display may be included in an eye-wear comprising a frame and a display assembly that presents media to a user’s eyes. The display assembly includes a source assembly and an output waveguide. The source assembly includes a light source which emits image light to the output waveguide which expands the image light and outputs the expanded image light to the user’s eyes. In some embodiments, the display assembly includes the source assembly, the output waveguide and a source waveguide. The source waveguide is a long and narrow waveguide that expands the image light emitted by the source assembly to the output waveguide in one dimension.

The source assembly includes a light source, and an optics system. A controller controls one or more scanning components of the display assembly. In some embodiments, the controller controls the scanning of the source waveguide, which outputs the image light toward the output waveguide. In some embodiments, the controller controls one or more scanning mirrors, which outputs the image light toward the output waveguide.

The light source includes one or more source elements (e.g., microLEDs). The one or more source elements may emit light in the same wavelength range (e.g., all emit the same color). Alternatively, some source elements may emit light at different wavelength ranges than other source elements (e.g., one source emits in red, another emits in blue, and another emits in green). In some embodiments, a plurality of source elements forms an array. In some embodiments, the array is one dimensional, linear array of source elements. Alternatively, the array may be a two-dimensional array of source elements (e.g., a spare array). Additionally, in some embodiments, the array may be a curved array–which mitigates field curvature. Additionally, in some embodiments, each of the plurality of source elements may be in contact with an optical isolator (e.g., Aluminum film) that helps reduce optical interference between adjacent source elements.

The optics system includes one or more optical elements that condition (e.g., expand and/or collimate) light received from the light source. The optics system may also include one or more scanning mirrors (e.g. galvanometer mirror, MEMS mirror) that scan light received from the collimating lens. The one or more scanning mirrors may perform a scanning along one or two dimensions. The use of one dimensional arrays, sparse 2D arrays, and/or MicroLEDs also helps reduce design constraints for the scan angle and resonance frequency of the scanning mirror assembly. The scanning mirrors emit the scanned light to the output waveguide, such that a scanned image is ultimately output from the output waveguide. In some embodiments, the optics system does not include the one or more scanning mirrors.