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EP-4741892-A1 - LIGHT GUIDE DEVICE, OPTICAL MODULE, AND DISPLAY APPARATUS

EP4741892A1EP 4741892 A1EP4741892 A1EP 4741892A1EP-4741892-A1

Abstract

Embodiments of this application provide a light guide device, an optical module, and a display apparatus. The light guide device includes a substrate and a first grating region, a second grating region, and a third grating region disposed on the substrate. The first grating region is configured to couple light into the substrate and generate a first diffracted light that propagates toward the second grating region; the second grating region receives the first diffracted light and is able to generate a second diffracted light that propagates toward the third grating region; the third grating region receives the second diffracted light and is able to generate a third diffracted light that diffracts toward the second grating region; the second diffracted light and the third diffracted light undergo pupil expansion by the second grating region along two different dimensions and are coupled out.

Inventors

  • CHENG, XIN

Assignees

  • Goertek Optical Technology (Shanghai) Co., Ltd.

Dates

Publication Date
20260513
Application Date
20240703

Claims (10)

  1. A light guide device, characterized by comprising a substrate (4) and a first grating region (1), a second grating region (2) and a third grating region (3) disposed on the substrate (4); the first grating region (1) is configured to couple light into the substrate (4) and generate a first diffracted light (01) that propagates toward the second grating region (2); the second grating region (2) receives the first diffracted light (01) and is able to generate a second diffracted light (02) that propagates toward the third grating region (3), the third grating region (3) receives the second diffracted light (02) and is able to generate a third diffracted light (03) that diffracts toward the second grating region (2), the second diffracted light (02) and the third diffracted light (03) undergo pupil expansion by the second grating region (2) along two different dimensions and are coupled out.
  2. The light guide device according to claim 1, wherein a set angle θ2 is formed between the grating vector K1 direction of the first grating region (1) and the grating vector K3 direction of the third grating region (3), and 30°≤θ2≤150°.
  3. The light guide device according to claim 1, wherein the first grating region (1), the second grating region (2), and the third grating region (3) form a closed grating vector polygon, so that the exit angle of the light rays after being coupled out through the second grating region (2) is consistent with the initial incident angle.
  4. The light guide device according to claim 1, wherein a one-dimensional grating is provided in the second grating region (2).
  5. The light guide device according to claim 4, wherein a one-dimensional grating or a two-dimensional grating is provided in the first grating region (1).
  6. The light guide device according to claim 4, wherein a one-dimensional grating is provided in the third grating region (3).
  7. The light guide device according to any one of claims 1 to 6, wherein the light guide device is a diffraction optical waveguide lens; the first grating region (1), the second grating region (2), and the third grating region (3) are located on one surface of the substrate (4) along its own thickness direction; or, the first grating region (1), the second grating region (2), and the third grating region (3) are respectively disposed on two opposing surfaces of the substrate (4) along its own thickness direction.
  8. The light guide device according to claim 7, wherein the grating types of the first grating region (1), the second grating region (2), and the third grating region (3) include volume holographic gratings, surface relief gratings, or photonic crystals.
  9. An optical module, characterized by comprising: the light guide device according to any one of claims 1 to 8; and a light engine configured for projecting light onto the light guide device such that light projected by the light engine can cover the first grating region (1).
  10. A display apparatus, characterized by comprising: a housing; and the optical module according to claim 9, wherein the optical module is disposed in the housing.

Description

This application claims priority to Chinese patent application No. 202310828697.0 filed with CNIPA on April 16, 2024, and entitled "light guide device, optical module and display apparatus", which is hereby incorporated by reference in its entirety. TECHNICAL FIELD The embodiments of this application relate to the field of optical technology, and particularly to a light guide device, optical module, and display apparatus. BACKGROUND Display apparatus, such as head-mounted displays, are now widely used in the technology field, including augmented reality (AR) display apparatus. In the above display apparatus, a light guide device plays a crucial role, guiding light from the light source to the user's eyes. At present, the mainstream pupil expansion technical solution in diffraction waveguide solutions is the two-dimensional grating pupil expansion solution. Although the two-dimensional grating solution offers a compact layout, its complex optical structure design leads to high costs. Therefore, it has become a key research focus in this field to develop a light guide device that combines a compact layout and a simple design. SUMMARY The object of this application is to provide new technical solutions for a light guide device, an optical module, and a display apparatus. In a first aspect, embodiments of this application provide a light guide device. The light guide device includes a substrate and a first grating region, a second grating region, and a third grating region disposed on the substrate; The first grating region is configured to couple light into the substrate and generate a first diffracted light that propagates toward the second grating region; the second grating region receives the first diffracted light and is able to generate a second diffracted light that propagates toward the third grating region; the third grating region receives the second diffracted light and is able to generate a third diffracted light that diffracts toward the second grating region; the second diffracted light and the third diffracted light undergo pupil expansion by the second grating region along two different dimensions and are coupled out. Optionally, a set angle θ2 is formed between the grating vector K1 direction of the first grating region and the grating vector K3 direction of the third grating region, and 30°≤θ2≤150°. Optionally, the first grating region, the second grating region, and the third grating region form a closed grating vector polygon, so that the exit angle of the light rays after being coupled out through the second grating region is consistent with the initial incident angle. Optionally, a one-dimensional grating is provided in the second grating region. Optionally, a one-dimensional grating or a two-dimensional grating is provided in the first grating region. Optionally, a one-dimensional grating is provided in the third grating region. Optionally, the light guide device is a diffraction optical waveguide lens; The first grating region, the second grating region, and the third grating region are located on one surface of the substrate along its own thickness direction; or,the first grating region, the second grating region, and the third grating region are respectively disposed on two opposing surfaces of the substrate along its own thickness direction. Optionally, the grating types of the first grating region, the second grating region, and the third grating region include volume holographic gratings, surface relief gratings, or photonic crystals. In a second aspect, embodiments of this application provide an optical module. The optical module includes the light guide device according to the first aspect; anda light engine configured for projecting light onto the light guide device such that light projected by the light engine can cover the first grating region.In a third aspect, embodiments of this application provide a display apparatus. The display apparatus includes:a housing; andthe optical module according to the second aspect, wherein the optical module is disposed in the housing. The beneficial effects of this application are as follows: According to embodiments of this application, a light guide device is provided, which can be applied in augmented reality display apparatus. The design achieves effective in-coupling, directional propagation, pupil expansion and out-coupling of light through the coordinated operation of three grating regions. Compared with traditional light guide devices, the light guide device provided in this application has the characteristics of compact grating structure design and can make full use of the energy of light, thereby improving the propagation efficiency and utilization rate of incident light. Other features and advantages of the embodiments of the specification will become apparent from the following detailed description of exemplary embodiments of the specification with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS The drawings, which ar