# US 10,481,401 B2 · Systems, devices, and methods for eyebox expansion in wearable heads-up display > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,481,401 B2 - Document ID: US10481401B2 - Status: Granted - Kind: B2 - Application number: 15/970,645 - Filed: 2018-05-03 - Published: 2018-11-08 - Granted: 2019-11-19 - Earliest claimed: 2017-05-04 - Assignees: North Inc. - Applicants: North Inc. - Inventors: Ian Andrews; Joshua Moore - Web page: https://patentgrep.com/patent/US10481401B2 ## CPC - G02B 27/0172: {characterised by optical features} - G02B 27/0179: {Display position adjusting means not related to the information to be displayed} - G03H 1/024: {Hologram nature or properties} - H04N 9/3135: {Driving therefor} - H04N 9/3161: {using laser light sources (using laser beams scanning the display screen H04N9/3129)} - H04N 9/3164: {using multiple light sources} - H04N 9/317: {Convergence or focusing systems (electronic adjustment of convergence H04N9/3185; convergence or focusing arrangements for cathode ray tubes H04N9/28; means for automatic focusing of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/53)} - H04N 9/3173: {wherein the projection device is specially adapted for enhanced portability} - G02B 26/0833: {the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD (G02B26/0825 takes precedence; micromechanical devices in general B81B)} - G02B 2027/0112: {comprising device for genereting colour display} - G02B 2027/0174: {holographic} - G02B 2027/0178: {Eyeglass type (eyeglass details G02C)} - H04N 9/3105: {for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators (simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10)} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G03H: HOLOGRAPHIC PROCESSES OR APPARATUS (holograms, e.g. point holograms, used as ordinary optical elements G02B5/32; producing stereoscopic or other three-dimensional effects G02B30/00; diffraction-grating systems G02B27/44; systems using moiré fringes G02B27/60; optical logic elements G02F3/00; stereo-photography G03B35/00; photosensitive materials or processes for photographic purposes G03C; {stereo-photographic or similar processes G03C9/00}; apparatus for processing exposed photographic materials G03D; analogue computers performing mathematical operations with the aid of optical elements G06E3/00; authentication by radiation, of concealed information carried by holograms or diffraction gratings G06K19/16; holographic storage G11B7/0065, G11C13/04; {stereoscopic or other three dimensional effects in television systems H04N13/00}) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Systems, devices, and methods for eyebox expansion in wearable heads-up displays (WHUD) are described. A WHUD includes a support structure, a scanning laser projector (SLP), a split mirror, an optical splitter, and a holographic combiner. When the WHUD is worn on the head of a user the holographic combiner is positioned in a field of view of the user. The SLP scans light signals onto the split mirror which reflects the light signals onto the optical splitter. The optical splitter redirects the light signals towards the holographic combiner such that subsets of the light signals originate from spatially-separated virtual positions. The holographic combiner redirects the light to the eye resulting in spatially-separated exit pupils. The spatial separation of the exit pupils results in an expanded eyebox. The indirect path of light from SLP to optical splitter enables a smaller and therefore more aesthetically desirable design for the WHUD. ## Claims ### Claim 1 A method of operating a wearable heads-up display (WHUD) when the WHUD is worn on a head of a user, the WHUD including a scanning laser projector having a scan range, a split mirror having at least two non-coplanar reflective surfaces, an optical splitter, and a holographic combiner, the method comprising: generating light signals by the scanning laser projector; scanning the light signals towards the split mirror across the scan range by the scanning laser projector; directing the light signals towards the optical splitter by the split mirror; directing the light signals towards the holographic combiner by the optical splitter, wherein the optical path of a respective light signal from the optical splitter to the holographic combiner is determined by a respective point of incidence and angle of incidence of the respective light signal at the optical splitter; and directing the light signals to at least two exit pupils at or proximate an eye of the user by the holographic combiner. ### Claim 2 (depends on 1) The method claim 1 wherein the scanning laser projector includes a red laser diode, a green laser diode, a blue laser diode, a beam combiner, and at least one controllable mirror, and wherein generating light signals by the scanning laser projector further includes: generating red laser light by the red laser diode; generating green laser light by the green laser diode; and generating blue laser light by the blue laser diode; wherein the method further includes: combining the red laser light, green laser light, and blue laser light into aggregate light signals; and wherein: scanning the light signals towards the split mirror across the scan range by the scanning laser projector further includes scanning the light signals towards the split mirror by the at least one controllable mirror. ### Claim 3 (depends on 1) The method of claim 1 wherein directing the light signals towards the optical splitter by the split mirror further includes: directing the light signals towards respective distinct and non-overlapping regions of the optical splitter by each respective non-coplanar reflective surface of the split mirror. ### Claim 4 (depends on 1) The method of claim 1 wherein directing the light signals towards the optical splitter by the split mirror further includes: directing respective discrete sets of light signals towards the optical splitter by each respective non-coplanar reflective surface of the split mirror. ### Claim 5 (depends on 1) The method of claim 1 wherein scanning the light signals towards the split mirror across the scan range by the scanning laser projector further includes: scanning at least 90% of the light signals onto the split mirror by the scanning laser projector. ### Claim 6 (depends on 1) The method of claim 1 further including: receiving at least 90% of the reflected light signals from the split mirror by the optical splitter. ### Claim 7 (depends on 1) The method of claim 1 wherein the optical splitter includes at least two non-coplanar surfaces, and wherein: directing the light signals towards the optical splitter by the split mirror includes directing a first set of light signals towards a first non-coplanar surface of the optical splitter by a first non-coplanar surface of the split mirror and directing a second set of light signals towards a second non-coplanar surface of the optical splitter by a second non-coplanar surface of the split mirror. ### Claim 8 (depends on 7) The method of claim 7 wherein directing the light signals towards the holographic combiner by the optical splitter includes: directing the first set of light signals towards the holographic combiner by the first non-coplanar surface of the optical splitter; and directing the second set of light signals towards the holographic combiner by the second non-coplanar surface of the optical splitter. ### Claim 9 (depends on 8) The method of claim 8 wherein directing the light signals to at least two exit pupils at or proximate an eye of the user by the holographic combiner includes: directing the first set of light signals to a first exit pupil by the holographic combiner; and directing the second set of light signals to a second exit pupil by the holographic combiner.