JP-7856330-B2 - Increased field of view for near-eye displays

JP7856330B2JP 7856330 B2JP7856330 B2JP 7856330B2JP-7856330-B2

Inventors

シュリキ，ロネン
ロネン，エイタン
シャーリン，エラド

Assignees

ルムスエルティーディー．

Dates

Publication Date: 20260511
Application Date: 20220321
Priority Date: 20210429

Claims (12)

An optical system for a near-eye display (NED), wherein the optical system is An optical guide optical element (LOE) including an optical transmission substrate, wherein the optical transmission substrate is A first main surface and a second main surface that are parallel to each other, An optical guide optical element having one or more optical input coupling elements configured to couple incident light into the optical transmission substrate, thereby confining the light between the first main surface and the second main surface by total internal reflection, and one or more optical output coupling elements configured to couple the light out of the substrate via the second main surface , A pair of polarization diffraction gratings distinct from the one or more optical output coupling elements , comprising a first polarization diffraction grating from the pair disposed on a first side surface of the optical transmission substrate corresponding to the first main surface, and a second polarization diffraction grating from the pair disposed on a second side surface of the optical transmission substrate corresponding to the second main surface, wherein the second polarization diffraction grating is disposed between the one or more optical output coupling elements and a position corresponding to the user's eye of the NED , The second polarization diffraction grating is configured to switch the polarization of the light from a first polarization to a second polarization different from the first polarization, so that the second polarization diffraction grating deflects the light with the first polarization in a first direction and the light with the second polarization in a second direction different from the first direction, and A projector configured to emit the aforementioned incident light, and configured to project an image frame divided into at least two subframes, A processor operably connected to the projector and the at least one switching polarizer, and configured to time-division multiplex the polarization of the light between the first polarization and the second polarization, synchronized with the projection of the first subframe and the second subframe from the at least two subframes, respectively, comprises : The projector is further configured to project a multicolor image, wherein in the multicolor image, light of a first color is projected only in a first field of view, and light of a second color different from the first color is projected only in a second field of view different from the first field of view , in an optical system.
The optical system according to claim 1, wherein the at least one switching polarizer is disposed between the projector and the first main surface such that the incident light switches between the first polarization and the second polarization before the light is coupled into the optical transmission substrate.
The optical system according to claim 1, wherein the at least one switching polarizing element includes a first switching polarizing element and a second switching polarizing element, the first switching polarizing element is disposed between the LOE and the first polarization diffraction grating, and the second switching polarizing element is disposed between the LOE and the second polarization diffraction grating.
The present invention comprises a second pair of polarization diffraction gratings, a third polarization diffraction grating from the second pair disposed on the first side surface of the optical transmission substrate corresponding to the first main surface, and a fourth polarization diffraction grating from the second pair disposed on the second side surface of the optical transmission substrate corresponding to the second main surface, The optical system according to claim 3, wherein the at least one switching polarizing element includes a third switching polarizing element and a fourth switching polarizing element, the third switching polarizing element is disposed between the first polarizing diffraction grating and the third polarizing diffraction grating, and the fourth switching polarizing element is disposed between the second polarizing diffraction grating and the fourth polarizing diffraction grating.
The optical system according to claim 1, wherein the at least one switching polarizing element includes first, second, and third switching polarizing elements, the first switching polarizing element is disposed between the LOE and the first polarization diffraction grating, the second switching polarizing element is disposed between the LOE and the second polarization diffraction grating, and the third switching polarizing element is disposed between the projector and the first polarization diffraction grating, and the first switching polarizing element is configured to synchronously switch the second switching polarizing element and the third switching polarizing element.
The optical system according to claim 1, comprising a processor operably connected to the projector and the at least one switching polarizing element, and configured to time-division multiplex the polarization of the light between the first polarization and the second polarization at least once into an image frame.
The optical system according to claim 1, wherein the first polarization diffraction grating divides unpolarized light incident thereon into several parts, and these parts are incident on the first main surface, propagate through the substrate, and are incident on a second polarization diffraction grating that deflects these parts to light having the same angular direction as the light incident on the first polarization diffraction grating.
An optical system for a near-eye display (NED), wherein the optical system is An optical guide optical element (LOE) including an optical transmission substrate, wherein the optical transmission substrate is A first main surface and a second main surface that are parallel to each other, An optical guide optical element having one or more optical input coupling elements configured to couple incident light into the optical transmission substrate, thereby confining the light between the first main surface and the second main surface by total internal reflection, and one or more optical output coupling elements configured to couple the light out of the substrate via the second main surface , Unlike the one or more optical output coupling elements, a first active transparent liquid crystal element disposed on a first side surface of the optical transmission substrate corresponding to the first main surface, wherein the first active transparent liquid crystal element is configured to switch the polarization of the light from a first polarization to a second polarization different from the first polarization, such that the first active transparent liquid crystal element deflects light of a first polarization in a first direction and light of a second polarization in a second direction different from the first direction, Optically, a second active transparent liquid crystal element is disposed adjacent to the second main surface between one or more optical output coupling elements and a position corresponding to the user's eye of the NED, wherein the second active transparent liquid crystal element is configured to switch the polarization of light incident on it in synchronization with the first active transparent liquid crystal element, A projector configured to emit the aforementioned incident light, and configured to project an image frame divided into at least two subframes, The system comprises a processor operably connected to the projector and the first active transparent liquid crystal element, and configured to time-division multiplex the polarization of the light between the first polarization and the second polarization, synchronized with the projection of the first subframe and the second subframe from the at least two subframes, respectively . The projector is further configured to project a multicolor image, wherein in the multicolor image, light of a first color is projected only in a first field of view, and light of a second color different from the first color is projected only in a second field of view different from the first field of view , in an optical system.
The optical system according to claim 8, comprising a processor operably connected to the projector and the first active transparent liquid crystal element, and configured to time-division multiplex the polarization of the light between the first polarization and the second polarization into an image frame at least once .
An optical system for a near-eye display (NED), wherein the optical system is A projector configured to emit light corresponding to an image, An optical guide optical element (LOE) including an optical transmission substrate, wherein the optical transmission substrate is A first main surface and a second main surface that are parallel to each other, An optical guide optical element having one or more optical input coupling elements configured to couple light from the projector into the optical transmission substrate, thereby confining the light between the first main surface and the second main surface by total internal reflection, and one or more optical output coupling elements configured to couple the light out of the substrate via the second main surface, A pair of polarization diffraction gratings distinct from the one or more optical output coupling elements, comprising a first polarization diffraction grating from the pair disposed between the projector and the first main surface, and a second polarization diffraction grating from the pair disposed between the second main surface and a position corresponding to the user's eye of the NED, The system comprises at least one switching polarizing element configured to switch the polarization of the light from a first polarization to a second polarization different from the first polarization, so that the second polarization diffraction grating deflects the light with the first polarization in a first direction and the light with the second polarization in a second direction different from the first direction, The projector is further configured to project an image frame divided into at least two subframes, The optical system further comprises a processor operably connected to the projector and the at least one switching polarizer, and configured to time-division multiplex the polarization of the light between the first polarization and the second polarization, synchronized with the projection of the first subframe and the second subframe from the at least two subframes, respectively. The projector is further configured to project a multicolor image, wherein in the multicolor image, light of a first color is projected only in a first field of view, and light of a second color different from the first color is projected only in a second field of view different from the first field of view, in an optical system.
The optical system according to claim 10, wherein the at least one switching polarizing element is disposed between the projector and the first polarization diffraction grating.
The optical system according to claim 10, wherein the at least one switching polarizing element includes first, second, and third switching polarizing elements, the first switching polarizing element is disposed between the LOE and the first polarization diffraction grating, the second switching polarizing element is disposed between the LOE and the second polarization diffraction grating, and the third switching polarizing element is disposed between the projector and the first polarization diffraction grating, and the first switching polarizing element is configured to synchronously switch the second switching polarizing element and the third switching polarizing element.

Description

This disclosure relates to an optical system for use in a NED having a relatively wide field of view (FOV). Near-eye displays (NEDs) are now a staple in augmented reality (AR) and virtual reality (VR) applications. Augmented reality displays typically include transparent or translucent displays that are close to the eyes, allowing the user to see their surroundings and simultaneously view virtual objects (e.g., text, graphics, video, etc.) that appear as part of and/or superimposed on the surrounding environment. NED devices often utilize optical waveguides to reproduce displayed virtual images that users can see in an augmented reality environment. These optical waveguides often present limitations on the performance and/or shape factors of such devices. In particular, in NED devices that utilize optical waveguides, such as head-mounted displays (HMDs), light propagates through the waveguide over a limited range of internal angles. Light propagating within the inner surface of the waveguide at a certain angle of incidence will travel within the waveguide and between its surfaces only if the angle of incidence relative to the surface normal is greater than a certain critical angle associated with the material from which the optical waveguide is fabricated. Light propagating at other angles of incidence will escape the optical waveguide. Therefore, the angular width of light in NED devices using optical waveguides is inherently limited by the optical waveguide. These, along with other factors inherent to optical waveguides, tend to limit the field of view (FOV) that can be supported by optical waveguide-based displays. Attempts to increase the field of view (FOV) of optical waveguide-based displays have traditionally come with size compromises. To improve the FOV, designers have had to make NED devices bulky and unwieldy, which is an undesirable attribute for consumers. Therefore, there is a need in this art for NEDs with improved FOV that are less bulky and easier to handle. This disclosure relates to an optical system for use in a NED having a relatively wide FOV. According to one embodiment, the optical system includes an optical guide optical element (LOE) including an optical transmission substrate. The optical transmission substrate includes a first principal surface and a second principal surface parallel to each other, one or more optical input coupling elements configured to couple incident light into the optical transmission substrate, thereby confining the light between the first principal surface and the second principal surface by total internal reflection, and one or more optical output coupling elements configured to couple light out of the substrate. In this embodiment, the optical system further includes a pair of complementary polarizing diffraction gratings. The first polarizing diffraction grating from this pair is disposed on a first side surface of the optical transmission substrate corresponding to the first principal surface, and the second polarizing diffraction grating from this pair is disposed on a second side surface of the optical transmission substrate corresponding to the second principal surface. In this embodiment, the optical system further includes at least one switching polarizing element configured to switch the polarization of light between a first polarization and a second polarization different from the first polarization, such that a second polarization diffraction grating deflects light of the first polarization in the first direction and light of the second polarization in the second direction different from the first direction. A polarization diffraction grating deflects polarized light from an image in two different directions according to a time-division multiplexing scheme. At a first time point, the first sub-image light, polarized with a first polarization, is deflected in the first direction. At a subsequent second time point, the second sub-image light, polarized with a second polarization, is deflected in the second direction. The effective combination of light deflected in the first direction and light deflected in the second direction by time-division multiplexing significantly expands the image's field of view (FOV). This technique enables the use of compact optical waveguides, projectors, and other components. Therefore, the present invention disclosed herein allows for an improved field of view (FOV) of the NED without significantly increasing their size. In one embodiment, the optical system includes a projector configured to emit polarized light in a direction centered on the normals of a first and a second main surface. In one embodiment, at least one switching polarizing element is disposed between the projector and the first main surface such that the incident light is switched between a first polarization and a second polarization before coupling to the optical transmission substrate. In one embodiment, at least one switching polarizing element