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US-12625361-B2 - Image display device

US12625361B2US 12625361 B2US12625361 B2US 12625361B2US-12625361-B2

Abstract

An image display device including a first optical element, multiple microlens arrays and a second optical element is provided. The first optical element receives a display image and generates multiple image beams parallel to each other. The microlens arrays respectively receive the image beams, deflect the image beams to generate multiple first light beams, and focuses the first light beams on a first focusing plane. The second optical element is disposed between the first focusing plane and a target area, receives the first light beams, deflects the first light beams to generate multiple second light beams, focuses the second light beams on a second focusing plane, and projects the second light beams to focus on the target area.

Inventors

  • Kuei-Chun LIU
  • Wei Chun CHEN

Assignees

  • HTC CORPORATION

Dates

Publication Date
20260512
Application Date
20230914

Claims (12)

  1. 1 . An image display device, comprising: a first optical element receiving a display image, and generating a plurality of image beams parallel to each other; a plurality of microlens arrays respectively receiving the image beams, deflecting the image beams to generate a plurality of first light beams, and focusing the first light beams on a first focusing plane; and a second optical element disposed between the first focusing plane and a target area, receiving the first light beams, deflecting the first light beams to generate a plurality of second light beams, focusing the second light beams on a second focusing plane, and projecting the second light beams to the target area.
  2. 2 . The image display device according to claim 1 , wherein the first optical element is a collimating lens.
  3. 3 . The image display device according to claim 1 , wherein the image beams are transmitted along an optical axis, and the second optical element comprises a focusing lens group disposed on the optical axis.
  4. 4 . The image display device according to claim 3 , wherein the focusing lens group comprises a biconvex lens, a plano-convex lens or a concavo-convex lens.
  5. 5 . The image display device according to claim 3 , wherein the second optical element further comprises: a reflector disposed on the optical axis, wherein the focusing lens group is between the reflector and the microlens arrays, and the reflector reflects the second light beams and focuses the second light beams on the second focusing plane.
  6. 6 . The image display device according to claim 5 , wherein an included angle greater than 0 and less than 180 degrees is formed between a connection line of the focusing lens group and a center point of the reflector and a connection line of the reflector and a center point of the target area.
  7. 7 . The image display device according to claim 3 , wherein the second optical element comprises: a beam splitter disposed on the optical axis to reflect the first light beams in a setting direction; and a concave mirror disposed in the setting direction, receiving the first light beams, generating the second light beams by reflecting the first light beams, and causing the second light beams to pass through the beam splitter and focus on the second focusing plane.
  8. 8 . The image display device according to claim 7 , wherein the second optical element comprises: a lens group disposed between the beam splitter and the microlens arrays.
  9. 9 . The image display device according to claim 7 , wherein an included angle between the optical axis and the setting direction is greater than 0 and less than 180 degrees.
  10. 10 . The image display device according to claim 1 , further comprising: an image projector configured to project the image beams of the image beam.
  11. 11 . The image display device according to claim 10 , further comprising: a controller coupled to the image projector, and adjusting a depth of field of a corresponding displayed object of each of the image beams by adjusting a position of each of the image beams projected on each of the microlens arrays.
  12. 12 . The image display device according to claim 1 , wherein each of the microlens array is composed of N times N microlenses, wherein N is an integer greater than or equal to 2.

Description

BACKGROUND Technical Field The invention relates to an image display device, and particularly relates to an image display device that may reduce vergence accommodation conflict (VAC). Description of Related Art In the real world, a way that human eyes measure a distance is through cooperation of two sets of physiological reactions: vergence and accommodation. Eyeball vergence represents rotation of human eyes, and when looking at a close object, both eyes will simultaneously rotate toward the bridge of the nose. If the object is farther away, an angle of rotation will become smaller. Eyeball accommodation means scaling of a crystalline lens, where human eyes may automatically adjust a focus, and through force exertion/relaxation of a ciliary muscle, a curvature of the crystalline lens is changed to focus light emitted by an object on the retina. However, in conventional augmented reality and virtual reality displays, binocular parallax is often used to create a three-dimensional sense for a user. A specifically calculated parallax image is received through the left and right eyes at the same time, thereby satisfying a vergence response. Such method cannot design different focusing planes for distant objects and near objects in the image, which means that any position in the image comes from the same focusing plane. Although this method results in correct response of the eyeball vergence to feel a distance of the object, since the image has only one focusing plane, the eyeball accommodation function will only focus on one position. Therefore, the two sets of physiological reactions will conflict, which may easily cause dizziness and nausea in some users, and such phenomenon is called vergence accommodation conflict. SUMMARY The invention provides an image display device, which may present both front and rear virtual images, so as to provide a better virtual and real integration experience. The invention provides an image display device including a first optical element, a plurality of microlens arrays and a second optical element. The first optical element receives a display image and generates a plurality of image beams parallel to each other. The microlens arrays respectively receive the image beams, deflect the image beams to generate a plurality of first light beams, and focuses the first light beams on a first focusing plane. The second optical element is disposed between the first focusing plane and a target area, receives the first light beams, deflects the first light beams to generate a plurality of second light beams, focuses the second light beams on a second focusing plane, and projects the second light beams to focus on the target area. Based on the above, the image display device of the invention uses the first optical element to focus the image beams on the first focusing plane for a first time, and uses the second optical element to focus the image beams on the second focusing plane for a second time to form a plurality of light point arrays to enter the human eye in multiple angles. When the human eye receives these image beams, it may focus the multiple image beams on the retina through the automatic accommodation function, and the brain may perceive a depth of the object in the image based on accommodation information, thereby creating the depth of the image and satisfying the accommodation function of the human eye, so as to reduce the discomfort that may be caused by convergence accommodation conflicts. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B are schematic diagrams of how a human eye produce a sense of depth of an image. FIG. 2A is a schematic diagram of an image display device according to an embodiment of the invention. FIG. 2B is a partial enlarged schematic diagram of an image display device 200. FIG. 2C a schematic diagram of a relationship between a microlens array and incident light. FIG. 3A is a schematic diagram of an image display device according to another embodiment of the invention. FIG. 3B is a schematic diagram of a human eye perceiving a depth of an image object in the embodiment of FIG. 3A. FIG. 4 is a schematic diagram of an image display device according to another embodiment of the invention. FIG. 5 is a schematic diagram of an image display device according to another embodiment of the invention. FIG. 6 is a schematic diagram of a plurality of light spots formed on a second focusing plane by an image display device according to an embodiment of the invention. DESCRIPTION OF THE EMBODIMENTS Referring to FIGS. 1A and 1B, FIGS. 1A and 1B are schematic diagrams of how a human eye produce a sense of depth of an image. A reason why the human eye may perceive depth is that in addition to binocular parallax, it may also obtain object distances through monocular accommodation. As shown in FIG. 1A and FIG. 1B, light rays emitted by objects O1 and O2 at different distances may enter the human eye 100 at different angles. An angle of a light ray 120 of the object O2 w