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EP-4174559-B1 - DISPLAY APPARATUS PROVIDING EXPANDED EYE BOX

EP4174559B1EP 4174559 B1EP4174559 B1EP 4174559B1EP-4174559-B1

Inventors

  • SEO, WONTAEK
  • YANG, DAEHO
  • KIM, SUNIL
  • Shin, Bongsu
  • SUNG, GEEYOUNG

Dates

Publication Date
20260506
Application Date
20220601

Claims (13)

  1. A display apparatus (10) comprising: an image generator (110) configured to generate an image by using light; a holographic optical element (130) configured to, when a single image is incident on the holographic optical element, output a plurality of images corresponding to the single image at spatially different points by focusing the single image on the spatially different points; and an image deflector (120) provided in an optical path between the image generator (110) and the holographic optical element (130), and configured to deflect the image received from the image generator (110) to the holographic optical element (130), wherein at least one of the image generator (110), the image deflector (120), and the holographic optical element (130) is biaxially driven to adjust a deflection direction of the image deflector (120), wherein, when the single image is incident on the holographic optical element (130) in an adjusted deflection direction, the holographic optical element (130) focuses the plurality of images so that a center of the plurality of images is adjusted corresponding to the adjusted deflection direction.
  2. The display apparatus of claim 1, wherein the plurality of images are focused on an identical plane or on an identical focal plane; and/or wherein a distance between the plurality of images focused by the holographic optical element (130) is equal to or greater than a user's pupil size; and/or wherein a distance between the plurality of images focused by the holographic optical element (130) is 2 mm to 10 mm; and/or wherein the single image and the plurality of images have substantially identical optical characteristics; and/or wherein the image generator (110) is integrated with the image deflector (120); and/or further comprising a head-mounted display.
  3. The display apparatus of claim 1 or 2, wherein the holographic optical element (130) is configured such that: when the single image is incident on the holographic optical element (130) in a first direction, the holographic optical element (130) focuses the plurality of images such that a center of the plurality of images is at a first position; and when the single image is incident on the holographic optical element (130) in a second direction that is different from the first direction, the holographic optical element (130) focuses the plurality of images such that the center of the plurality of images is at a second position that is different from the first position.
  4. The display apparatus of claim 3, wherein the first position and the second position are located on an identical focal plane.
  5. The display apparatus of claim 3, wherein a distance between the first position and the second position is greater than or equal to a user's pupil size.
  6. The display apparatus of any of claims 1-5, further comprising an optical system (150) comprising one or more lenses, wherein the optical system (150) is provided between the image generator (110) and the image deflector (120) and configured to cause all light included in the image output from the image generator (110) to be incident on the image deflector (120).
  7. The display apparatus of any of claims 1-6, wherein the holographic optical element (130) comprises: a first surface (S1) on which the single image is incident and from which the plurality of images are output; and a second surface (S2) which is opposite to the first surface and on which external light corresponding to an external environment is incident.
  8. The display apparatus of any of claims 1-7, further comprising a processor (140) configured to adjust a deflection direction of the image deflector (120) by controlling at least one of the image generator (110), the image deflector (120), and the holographic optical element (130).
  9. The display apparatus of claim 8, wherein the processor (140) is further configured to apply a distortion compensation algorithm to image information, which is used by the image generator to generate the image, to compensate for image shape distortion caused by a biaxial drive mechanism of the at least one of the image generator (110), the image deflector (120), and the holographic optical element (130).
  10. The display apparatus of claim 9, wherein the distortion compensation algorithm is performed by inversely transforming a mapping algorithm that maps pixel position information included in the image information to pixel position information included in the plurality of images focused by the holographic optical element.
  11. The display apparatus of any of claims 8-10, further comprising an eye tracking sensor configured to track a user's gaze, wherein the processor (140) is configured to control at least one of the image generator (110), the image deflector (120), and the holographic optical element (130) based on tracking results received from the eye tracking sensor (160).
  12. The display apparatus of any of claims 8-11, wherein the processor (140) is further configured to periodically vary the deflection direction with time by controlling at least one of the image generator (110), the image deflector (120), and the holographic optical element (130).
  13. The display apparatus of any of claims 1-12, wherein the image generator (110) comprises: a plurality of light sources (112a) each configured to emit light; and a spatial light modulator (114) configured to generate the image using the light emitted from at least one of the plurality of light sources (112a).

Description

BACKGROUND 1. Field The present disclosure relates to a display apparatus providing an extended eye box. 2. Description of the Related Art Head-mounted displays (HMDs), which may be worn on the head in front of the eyes like glasses to view images, have reached the commercialization stage and are being widely used in the entertainment industry. In addition, HMDs have been developed into forms applicable in the medical, educational, and industrial fields. HMDs are used in various applications such as virtual reality (VR) and augmented reality (AR). In addition, methods for expanding a field of view or a view region (eye box) of an HMD in which users view images have been continuously researched. Examples thereof may be found in the article by KIM SEONG-BOK ET AL: "Optical see-through Maxwellian near-to-eye display with an enlarged eyebox" OPTICS LETTERS, vol. 43.no. 4. Further examples may be found in patent application EP3296797A1 or US 2020/142355 A1. SUMMARY One or more example embodiments provide display apparatuses capable of providing expanded eye boxes or expanded fields of view. According to an aspect of an example embodiment, a display apparatus as defined in claim 1 is provided. The display apparatus includes: an image generator configured to generate an image by using light; a holographic optical element configured, when a single image is incident on the holographic optical element, output a plurality of images corresponding to the single image at spatially different points by focusing the single image on the spatially different points; and an image deflector provided in an optical path between the image generator and the holographic optical element, and configured to deflect the image received from the image generator to the holographic optical element. The plurality of images may be focused on an identical plane or on an identical focal plane. A distance between the plurality of images focused by the holographic optical element may be equal to or greater than a user's pupil size. A distance between the plurality of images focused by the holographic optical element may be about 2 mm to about 10 mm. The single image and the plurality of images may have substantially identical optical characteristics. The holographic optical element is configured such that: when the single image is incident on the holographic optical element in a first direction, the holographic optical element focuses the plurality of images such that a center of the plurality of images is at a first position; and when the single image is incident on the holographic optical element in a second direction that is different from the first direction, the holographic optical element focuses the plurality of images such that the center of the plurality of images is at a second position that is different from the first position. The first position and the second position may be located on an identical focal plane. A distance between the first position and the second position may be greater than or equal to a user's pupil size. The display apparatus may further include an optical system including one or more lenses, wherein the optical system may be provided between the image generator and the image deflector and configured to cause all light included in the image output from the image generator to be incident on the image deflector. The holographic optical element may include: a first surface on which the single image is incident and from which the plurality of images are output; and a second surface which is opposite to the first surface and on which external light corresponding to an external environment is incident. The image generator may be integrated with the image deflector. The display apparatus may further include a processor configured to adjust a deflection direction of the image deflector by controlling at least one of the image generator, the image deflector, and the holographic optical element. The at least one of the image generator, the image deflector, and the holographic optical element is biaxially driven to adjust the deflection direction. The processor may be further configured to apply a distortion compensation algorithm to image information, which is used by the image generator to generate the image, to compensate for image shape distortion caused by a biaxial drive mechanism of the at least one of the image generator, the image deflector, and the holographic optical element. The distortion compensation algorithm may be performed by inversely transforming a mapping algorithm that maps pixel position information included in the image information to pixel position information included in the plurality of images focused by the holographic optical element. The display apparatus may further include an eye tracking sensor configured to track a user's gaze, wherein the processor may be configured to control at least one of the image generator, the image deflector, and the holographic optical element based on tracking resu