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EP-4500262-B1 - ACCOMMODATION INTEGRATED FOLDING LENS ASSEMBLY

EP4500262B1EP 4500262 B1EP4500262 B1EP 4500262B1EP-4500262-B1

Inventors

  • CHENG, Hsien-Hui
  • LU, Lu
  • WANG, XUAN

Dates

Publication Date
20260506
Application Date
20230323

Claims (15)

  1. A device, comprising: a display element (204); a lens assembly (202, 525, 702) coupled with the display element and comprising: a first polarization selective reflector (215, 225) and a second polarization selective reflector each configured to be switchable between operating in an active state and operating in a non-active state; and a polarization non-selective partial reflector disposed between the first polarization selective reflector and the second polarization selective reflector; and a controller (216, 540) configured to: control (410), during a first time period, the display element to display a first virtual object, the first polarization selective reflector to operate in the active state, and the second polarization selective reflector to operate in the non-active state; and control (420), during a second time period, the display element to display a second virtual object, the first polarization selective reflector to operate in the non-active state, and the second polarization selective reflector to operate in the active state.
  2. The device of claim 1, wherein the first time period and the second time period are a first sub-frame and a second sub-frame of a same display frame of the display element, respectively.
  3. The device of claim 1 or 2, wherein the first virtual object and the second virtual object are associated with a first vergence distance and a second vergence distance, respectively, the first vergence distance being different from the second vergence distance.
  4. The device of claim 3, wherein during the first time period, the lens assembly is configured to form a first image of the first virtual object displayed on the display element at a first image plane associated with a first accommodation distance, and during the second time period, the lens assembly is configured to form a second image of the second virtual object displayed on the display element at a second image plane associated with a second accommodation distance, the second accommodation distance being different from the first accommodation distance; preferably wherein: the first accommodation distance is substantially equal to the first vergence distance, and the second accommodation distance is substantially equal to the second vergence distance.
  5. The device of any one of the preceding claims, wherein at least one of the first polarization selective reflector or the second polarization selective reflector includes a reflective polarization volume hologram, PVH, element or a cholesteric liquid crystal, CLC, element; and/or wherein the first polarization selective reflector and the second polarization selective reflector are configured with at least one of different optical powers or different axial distances to the polarization non-selective partial reflector.
  6. The device of any one of the preceding claims, wherein the first polarization selective reflector operating in the active state is configured to reflect an input light having a first polarization, and transmit an input light having a second polarization that is orthogonal to the first polarization, and the second polarization selective reflector operating in the active state is configured to reflect an input light having the second polarization, and transmit an input light having the first polarization.
  7. The device of any one of the preceding claims, wherein each of the first polarization selective reflector operating in the non-active state and the second polarization selective reflector operating in the non-active state is configured to transmit an input light independent of a polarization of the input light.
  8. The device of any one of the preceding claims, wherein the lens assembly further comprises: a first polarizer (213) disposed between the first polarization selective reflector and the display element; and a second polarizer (223), the second polarization selective reflector being disposed between the polarization non-selective partial reflector and the second polarizer, wherein the first polarizer and the second polarizer are configured to block input lights having orthogonal polarizations.
  9. The device of any one of the preceding claims, wherein the lens assembly further comprises a transmissive lens (247) configured to converge an image light received from the second polarization selective reflector, and the second polarization selective reflector (225) is disposed between the polarization non-selective partial reflector and the transmissive lens.
  10. The device of any one of the preceding claims, wherein during the first time period: the first polarization selective reflector operating in the active state is configured to transmit a first image light having a first polarization toward the polarization non-selective partial reflector, the first image light forming the first virtual object; the polarization non-selective partial reflector is configured to reflect a first portion of the first image light back to the first polarization selective reflector as a second image light having a second polarization that is orthogonal to the first polarization; the first polarization selective reflector operating in the active state is configured to reflect the second image light back to the polarization non-selective partial reflector as a third image light having the second polarization; the polarization non-selective partial reflector is configured to transmit a portion of the third image light as a fourth image light having the second polarization toward the second polarization selective reflector; and the second polarization selective reflector operating in the non-active state is configured to transmit the fourth image light having the second polarization; and preferably wherein during the second time period: the first polarization selective reflector operating in the non-active state is configured to transmit a fifth image light having the first polarization toward the polarization non-selective partial reflector, the fifth image light forming the second virtual object; the polarization non-selective partial reflector is configured to transmit a portion of the fifth image light as a sixth image light having the first polarization toward the second polarization selective reflector; the second polarization selective reflector operating in the active state is configured to reflect the sixth image light back to the polarization non-selective partial reflector as a seventh image light having the first polarization; the polarization non-selective partial reflector is configured to reflect a portion of the seventh image light back to the second polarization selective reflector as an eighth image light having the second polarization; and the second polarization selective reflector operating in the active state is configured to transmit the eighth image light having the second polarization.
  11. A method (400), comprising: during a first time period (410), controlling, by a controller (216, 540), a display element (204) to display a first virtual object, a first polarization selective reflector (215, 225) disposed at a first side of a polarization non-selective partial reflector facing the display element to operate in an active state, and a second polarization selective reflector disposed at a second side of the polarization non-selective partial reflector to operate in a non-active state; and during a second time period (420), controlling, by the controller, the display element to display a second virtual object, the first polarization selective reflector to operate in the non-active state, and the second polarization selective reflector to operate in the active state.
  12. The method of claim 11, wherein the first time period and the second time period are a first sub-frame and a second sub-frame of a same display frame of the display element, respectively.
  13. The method of claim 11 or 12, wherein the first virtual object and the second virtual object are associated with a first vergence distance and a second vergence distance, respectively, and the first vergence distance is different from the second vergence distance; and preferably wherein a combination of the first polarization selective reflector, the second polarization selective reflector, and the polarization non-selective partial reflector disposed between the first polarization selective reflector and the second polarization selective reflector form a lens assembly (202, 525, 702), and preferably wherein the method further comprises: during the first time period, forming, by the lens assembly, a first image of the first virtual object displayed on the display element at a first image plane associated with a first accommodation distance that is substantially equal to the first vergence distance; and during the second time period, forming, by the lens assembly, a second image of the second virtual object displayed on the display element at a second image plane associated with a second accommodation distance that is substantially equal to the second vergence distance.
  14. The method of any one of claims 11 to 13, wherein at least one of the first polarization selective reflector or the second polarization selective reflector includes a reflective polarization volume hologram, PVH, element or a cholesteric liquid crystal, CLC, element; and/or wherein the first polarization selective reflector and the second polarization selective reflector are configured with at least one of different optical powers or different axial distances to the polarization non-selective partial reflector.
  15. The method of any one of claims 11 to 14, further comprising: during the first time period, controlling, by the controller, the display element to output a first image light forming the first virtual object; controlling, by the controller, the first polarization selective reflector to operate in the active state to transmit the first image light having a first polarization toward the polarization non-selective partial reflector; reflecting, by the polarization non-selective partial reflector, a first portion of the first image light back to the first polarization selective reflector as a second image light having a second polarization that is orthogonal to the first polarization; controlling, by the controller, the first polarization selective reflector to operate in the active state to reflect the second image light back to the polarization non-selective partial reflector as a third image light having the second polarization; transmitting, by the polarization non-selective partial reflector, a portion of the third image light as a fourth image light having the second polarization toward the second polarization selective reflector; and controlling, by the controller, the second polarization selective reflector to operate in the non-active state to transmit the fourth image light; and during the second time period, controlling, by the controller, the display element to output a fifth image light forming the second virtual object; controlling, by the controller, the first polarization selective reflector to operate in the non-active state to transmit the fifth image light having the first polarization toward the polarization non-selective partial reflector; transmitting, by the polarization non-selective partial reflector, a portion of the fifth image light as a sixth image light having the first polarization toward the second polarization selective reflector; controlling, by the controller, the second polarization selective reflector to operate in the active state to reflect the sixth image light back to the polarization non-selective partial reflector as a seventh image light having the first polarization; reflecting, by the polarization non-selective partial reflector, a portion of the seventh image light back to the second polarization selective reflector as an eighth image light having the second polarization; and controlling, by the controller, the second polarization selective reflector to operate in the active state to transmit the eighth image light.

Description

TECHNICAL FIELD The present disclosure generally relates to optical devices and, more specifically, to an accommodation integrated folding lens assembly. BACKGROUND An artificial reality system, such as a head-mounted display ("HMD") or heads-up display ("HUD") system, generally includes a near-eye display ("NED") system in the form of a headset or a pair of glasses. The NED system may be configured to present content to a user via an electronic or optic display disposed, for example, about 10-20 mm in front of the eyes of a user. The NED system may display virtual objects or combine images of real objects with virtual objects, as in virtual reality ("VR"), augmented reality ("AR"), or mixed reality ("MR") applications. It is often desirable to make NEDs that are compact and light-weight, and have a high resolution, a large field of view ("FOV"), and a small form factor. A NED may include a light source (e.g., a display element) configured to generate an image light, and a lens assembly configured to direct the image light towards eyes of the user. To achieve a compact size and light weight while maintaining satisfactory optical characteristics, the lens assembly may be designed to fold the optical path from the display element to the eye. US 11,243,397 B2 describes an optical assembly that includes a partial reflector that is optically coupled with a first polarization volume holographic element. The partial reflector is capable of receiving first light having a first circular polarization and transmitting a portion of the first light having a first circular polarization. The first polarization volume holographic element is configured to receive the first portion of the first light and reflect the first portion of the first light as second light having the first circular polarization. The partial reflector is capable of receiving the second light and reflecting a first portion of the second light as third light having a second circular polarization opposite to the first polarization. The first polarization volume holographic element is configured to receive the third light having the second circular polarization and transmit the third light having the second circular polarization. SUMMARY According to a first aspect of the present disclosure there is provided a device comprising: a display element; a lens assembly coupled with the display element and comprising: a first polarization selective reflector and a second polarization selective reflector each configured to be switchable between operating in an active state and operating in a non-active state; and a polarization non-selective partial reflector disposed between the first polarization selective reflector and the second polarization selective reflector; and a controller configured to: control, during a first time period, the display element to display a first virtual object, the first polarization selective reflector to operate in the active state, and the second polarization selective reflector to operate in the non-active state; and control, during a second time period, the display element to display a second virtual object, the first polarization selective reflector to operate in the non-active state, and the second polarization selective reflector to operate in the active state. In some embodiments, the first time period and the second time period may be a first sub-frame and a second sub-frame of a same display frame of the display element, respectively. In some embodiments, the first virtual object and the second virtual object may be associated with a first vergence distance and a second vergence distance, respectively, the first vergence distance may be different from the second vergence distance. In some embodiments, during the first time period, the lens assembly may be configured to form a first image of the first virtual object displayed on the display element at a first image plane associated with a first accommodation distance, and during the second time period, the lens assembly may be configured to form a second image of the second virtual object displayed on the display element at a second image plane associated with a second accommodation distance, the second accommodation distance may be different from the first accommodation distance. In some embodiments, the first accommodation distance may be substantially equal to the first vergence distance, and the second accommodation distance may be substantially equal to the second vergence distance. In some embodiments, at least one of the first polarization selective reflector or the second polarization selective reflector may include a reflective polarization volume hologram ("PVH") element or a cholesteric liquid crystal ("CLC") element. In some embodiments, the first polarization selective reflector and the second polarization selective reflector may be configured with at least one of different optical powers or different axial distances to the polarization non-selective partial refle