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EP-3822706-B1 - HEAD MOUNTED DISPLAY WITH LIGHTGUIDE AND HOLOGRAPHIC ELEMENT

EP3822706B1EP 3822706 B1EP3822706 B1EP 3822706B1EP-3822706-B1

Inventors

  • CAKMAKCI, OZAN
  • QIN, YI

Dates

Publication Date
20260506
Application Date
20201113

Claims (10)

  1. A head mounted display (HMD) (100) comprising: a micro-display (202); a lightguide (204); a holographic element (206) coupled to the lightguide (204) to transmit light provided to the holographic element (206) from the micro-display (202) via the lightguide (204);and a polarization film (317) coupled to the holographic element (206), wherein the polarization film (317) is configured to receive light from the holographic element (206), and wherein the polarization film (317) is configured to transmit light having a first polarization and to reflect light having a second polarization; and wherein the polarization film (317) is further configured to change the second polarization of the reflected light to the first polarization.
  2. The HMD (100) of claim 1, wherein the holographic element (206) is configured to reflect light based on a first angle of incidence.
  3. The HMD (100) of claim 2, wherein the holographic element is configured to transmit light based on a second angle of incidence.
  4. A head mounted display (HMD) (100) comprising: a micro-display (202); a lightguide (204) to receive light from the micro-display (202); and a holographic element (206) to transmit light from the lightguide (204) based on an angle of incidence of the light; and a polarization film (317) coupled to the holographic element (206), wherein the polarization film (317) is configured to receive light from the holographic element (206), and wherein the polarization film (317) is configured to transmit light having a first polarization and to reflect light having a second polarization; and wherein the polarization film (317) is further configured to change the second polarization of the reflected light to the first polarization.
  5. The HMD (100) of claim 4, wherein the first polarization is a first circular polarization and the second polarization is a second circular polarization.
  6. The HMD (100) of any one of claims 1 to 5, wherein the holographic element (206) is a volume type holographic element.
  7. The HMD (100) of any one of claims 1 to 6, wherein an optical configuration of the holographic element (206) is independent of a substrate geometry of the holographic element (206).
  8. A method, comprising: generating display light at a micro-display (202); transmitting light from the micro-display (202) to a holographic element (206) via a lightguide (204); transmitting light to a viewing region (104, 310) via the holographic element (206); wherein transmitting light to the viewing region (104, 310) comprises transmitting light from the holographic element (206) to a polarization film (317), wherein the polarization film (317) is configured to transmit light having a first polarization and to reflect light having a second polarization, wherein the polarization film (317) is configured to change the second polarization of the reflected light to the first polarization.
  9. The method of claim 8, wherein the holographic element (206) is configured to reflect light based on a first angle of incidence.
  10. The method of claim 9, wherein the holographic element (206) is configured to transmit light based on a second angle of incidence.

Description

BACKGROUND The present disclosure relates to a head-mounted display as well as a corresponding method. Head mounted display (HMD) systems provide a way to visually immerse a user in a virtual reality (VR) or augmented reality (AR) environment, or to display other content to a user in a convenient way. Some HMD systems include a micro-display that emits an image via a set of light rays. The light rays are coupled to an optical path of the HMD and that directs the light rays to the eye of the user. However, conventional HMD systems have limitations that can negatively impact the viewer experience. For example, the optical path of a conventional HMD includes components having a relatively large or bulky form factor, thereby limiting the design of the overall form factor for the HMD. Patent application US 2018/120 563 A1 refers to a near-eye display device including a holographic display system which comprises a light source configured to emig light that is converging or diverging, a waveguide configured to be positioned in a field of view of a user's eye, and a digital dynamic hologram configured to receive the light, and project the light into the waveguide such that the light propagates through the waveguide. From patent application US 2019/331 922 A1 a head-mounted display apparatus configured to measure the user eyesight by using an active element and correct the eyesight by adjusting a focal point is known. Patent application WO 2018/146 326 A1 refers to a light-guide device and a display device for representing scenes. BRIEF DESCRIPTION OF THE DRAWINGS The solution is set out in the appended set of claims. The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference symbols in different drawings indicates similar or identical items. FIG. 1 is a diagram of an HMD system including a lightguide and a holographic element to control provision of light to a user's eye in accordance with some embodiments.FIG. 2 is a block diagram illustrating a portion of the HMD of FIG. 1 including the multifocal module in accordance with some embodiments.FIG. 3 is a diagram illustrating a portion of the HMD of FIG. 1 including the lightguide and holographic element in accordance with some embodiments.FIG. 4 is a diagram illustrating operation of the holographic element of FIG. 3 in accordance with some embodiments. DETAILED DESCRIPTION FIGs. 1-4 illustrate systems and techniques for employing a holographic element in the optical path of an HMD to direct light to a user's eye. The HMD includes a micro-display, a lightguide, and a holographic element coupled to the lightguide. The holographic element is coupled to a polarization film, and together the element and film reflect and transmit light of different polarities in a specified pattern to assist the lightguide in directing light to the user's eye. For example, the hologram and polarization film can be configured to pass R-polarized light and reflect L-polarized light, thereby directing light from the waveguide along a specified path. The holographic element has a relatively small form factor, thereby supporting more flexible and comfortable HMD designs. To illustrate, conventional HMD designs typically employ multiple optical elements, such as mirrors and lenses, to direct light from a lightguide to a user's eye. These optical elements are relatively bulky, thereby requiring the HMD to employ a large form factor and limiting the placement of the optical elements to a few locations of the HMD form, such that the overall form factor of the HMD is uncomfortable for the user. For example, the optical elements may be placed near a user's eye, or in a user's peripheral vision, thereby distracting the user. The optical elements may also be relatively heavy, so that wearing the HMD induces fatigue in the user. In contrast, a holographic element is relatively small and light as compared to conventional optical elements, and thus allows for more flexible and comfortable HMD designs. FIG. 1 illustrates an HMD 100 in accordance with some embodiments. In the depicted example the HMD 100 has an eyeglass form factor and includes two see-through eyepieces 102 and 103 that each provide image light to a user in a viewing region (e.g. viewing region 104) along with a view of the surrounding environment. The image light may be augmented reality data that provides information of one or more objects in the surrounding environment. Additionally, the image light provides other information to the user such as text messages, email messages, phone call information, etc. The HMD 100 includes electronics and a micro-display (not shown at FIG. 1) to project the image light to the user. The electronics are either coupled to a secondary electronics device, such as a computer or cell phone, that provides the data for generating the image light, or the electronics i