# US 11,308,832 B2 · Head mounted display with mechanical scanning > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,308,832 B2 - Document ID: US11308832B2 - Status: Granted - Kind: B2 - Application number: 16/767,339 - Filed: 2019-10-02 - Published: 2021-01-07 - Granted: 2022-04-19 - Earliest claimed: 2018-10-05 - Assignees: Google Inc. - Applicants: Google LLC - Inventors: Matthew Valente; Konstantin Gromov; Kyle Skelton; John Fitch; Clayton Kimber; Ozan Cakmakci; Adrian Wong - Web page: https://patentgrep.com/patent/US11308832B2 ## CPC - G02B 27/0172: {characterised by optical features} - G09G 3/02: by tracing or scanning a light beam on a screen - G02B 27/0176: {characterised by mechanical features} - G02B 2027/0154: {with movable elements} - G02B 2027/0178: {Eyeglass type (eyeglass details G02C)} - G06F 3/147: using display panels - G09G 3/003: {to produce spatial visual effects} - G09G 2320/064: by time modulation of the brightness of the illumination source - G09G 2320/0646: Modulation of illumination source brightness and image signal correlated to each other - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A head mounted display (HMD) system includes a display for emitting light toward an eye-ward side of the system and which allows both ambient light and emitted light to reach an eye of a user. The system provides augmented reality (AR) based viewing and includes a rotatable substrate supporting a set of light emitting elements (301). Each light emitting element is oriented toward a world side of the HMD system. A rotatable reflective surface is positioned on the world side of the set of the light emitting elements. The reflective surface reflects emitted light toward a user eye. A motor, coupled to the rotatable substrate and the rotatable reflective surface, rotates these elements about a common axis and a display driver selectively activates the light emitting elements during this rotation in accordance with an illumination sequence so as to provide an image. ## Claims ### Claim 1 A head mounted display (HMD) system comprising: a substrate supporting a set of light emitting elements, wherein each light emitting element is oriented toward a world side of the HMD system; a reflective surface oriented toward a user eye; a motor coupled to the substrate and the reflective surface for motion of the substrate and reflective surface; and a display driver electrically coupled to the set of light emitting elements and configured to selectively activate the set of light emitting elements so as to generate an image during rotation of the substrate and the reflective surface around an optical axis of the HMD, wherein the optical axis is aligned with a user's eye. ### Claim 2 (depends on 1) The HMD system of claim 1, further comprising: a circular, transparent support for the reflective surface. ### Claim 3 (depends on 2) The HMD system of claim 2, wherein the circular, transparent support has a surface supporting the reflective surface, and wherein the reflective surface is spherically shaped with a center on an eye-ward side of the HMD system. ### Claim 4 (depends on 2) The HMD system of claim 2, wherein the circular, transparent support has a radius of curvature greater than 10 mm. ### Claim 5 (depends on 2) The HMD system of claim 2, wherein the center of the reflective surface is on the optical axis of the HMD system. ### Claim 6 (depends on 1) The HMD system of claim 1, wherein the light emitting elements are arranged in one column of light emitting elements along the substrate. ### Claim 7 (depends on 1) The HMD system of claim 1, wherein the light emitting elements are arranged in two columns of light emitting elements, and wherein the substrate supporting the light emitting elements is curved according to a constant or variable radius of curvature. ### Claim 8 (depends on 1) The HMD system of claim 1, further comprising: an outer housing substantially enclosing the substrate and the reflective surface, and wherein the reflective surface is positioned on the world side of the set of the light emitting elements. ### Claim 9 (depends on 8) The HMD system of claim 8, wherein a center of the substrate is on the optical axis of the HMD system. ### Claim 10 (depends on 1) The HMD system of claim 1, wherein the substrate has a surface supporting the light emitting elements and the surface is spherically shaped with a center on an eye-ward side of the HMD system. ### Claim 11 (depends on 1) The HMD system of claim 1, wherein the substrate has a spherically shaped surface supporting the light emitting elements and each of the light emitting elements is mounted substantially orthogonal to the spherically shaped surface. ### Claim 12 (depends on 1) The HMD system of claim 1, wherein power is supplied to the light emitting elements through induction. ### Claim 13 (depends on 1) The HMD system of claim 1, further comprising: a bearing assembly; and a rotatable housing, wherein the substrate and the reflective surface are each coupled to the rotatable housing, and wherein the rotatable housing is coupled to a portion of the bearing assembly for rotation by the motor. ### Claim 14 (depends on 13) The HMD system of claim 13, wherein the display driver is mounted to the rotatable housing, and wherein the bearing assembly includes one of an air-suspended bearing and a magnetically-suspended bearing. ### Claim 15 (depends on 13) The HMD system of claim 13, wherein the motor is a rim motor and rotation of the rotatable housing is actuated at a rim of the rotatable housing. ### Claim 16 (depends on 1) The HMD system of claim 1, further comprising: a drive belt coupled to the motor; a bearing assembly; and a rotatable housing having a surface feature to engage with the drive belt, wherein the substrate and the reflective surface are each coupled to the rotatable housing, and wherein the rotatable housing is rotated by operation of the drive belt and the motor. ### Claim 17 A method to generate an augmented reality image in a head mounted display (HMD) system, the method comprising: receiving an image signal by a display driver; generating light based on an illumination sequence by a set of light emitting elements controlled by the display driver, wherein the light emitting elements are disposed on a substrate and oriented toward a world side of the HMD; and rotating the substrate and a reflective surface around an optical axis of the HMD aligned with a user's eye, wherein the reflective surface is oriented toward an eye-ward side of the HMD and positioned on the world side of the set of the light emitting elements. ### Claim 18 (depends on 17) The method of claim 17, wherein the reflective surface is supported by a circular, transparent support. ### Claim 19 (depends on 17) The method of claim 17, further comprising: after receiving the image signal by the display driver, determining the illumination sequence for each element of the set of light emitting elements including at least one of a brightness and an illumination duration for each of the light emitting elements of the set of light emitting elements. ### Claim 20 (depends on 19) The method of claim 19, wherein each light emitting element includes at least two subcomponents, and wherein determining the illumination sequence for each element includes determining at least one of a brightness and an illumination duration for each subcomponent of each light emitting element of the set of light emitting elements. ### Claim 21 (depends on 20) The method of claim 20, wherein subcomponents of each light emitting element is positioned circumferentially with respect to one another, and wherein determining the illumination sequence for each light emitting element includes determining a timing offset for respective subcomponents of each light emitting element. ### Claim 22 (depends on 17) The method of claim 17, wherein determining the illumination sequence includes identifying an illumination duration for each of the light emitting elements based on a radial position of the respective light emitting element from a center of rotation. ### Claim 23 (depends on 17) The method of claim 17, wherein determining the illumination sequence includes identifying an illumination duration for each of the light emitting elements based on a rotational speed of the respective light emitting element around a center of rotation. ### Claim 24 (depends on 23) The method of claim 23, wherein rotating the substrate and the reflective surface includes determining a rotation speed based on the illumination sequence and rotating the rotatable substrate and the reflective surface based on the rotation speed. ### Claim 25 (depends on 17) The method of claim 17, wherein the substrate and the reflective surface are rotated at a substantially constant rotational speed. ### Claim 26 (depends on 17) The method of claim 17, wherein rotating the substrate and the reflective surface is performed by rotating a drive belt coupled to a motor and to a rotatable housing having an outer surface feature to engage with the drive belt. ### Claim 27 (depends on 17) The method of claim 17, wherein the substrate has a surface supporting the light emitting elements and the surface is spherically shaped with a center on an eye-ward side of the HMD.