Search

KR-20260068118-A - Resin light guide for display, image display device, and method for manufacturing a resin light guide for display

KR20260068118AKR 20260068118 AKR20260068118 AKR 20260068118AKR-20260068118-A

Abstract

The purpose is to provide a resin light guide for a display, such as a head-mounted display, which has good appearance and image quality, and the solution is a resin light guide for a display comprising a methacrylate resin composition, wherein the absolute value of the orientation degree of the methacrylic acid ester monomer unit in the methacrylate resin composition is 0.10 to 0.25, and the PV value of the effective area surface where image light is guided is 100 μm or less.

Inventors

  • 야마하타 유타
  • 다다 유타카
  • 미카와 노리코

Assignees

  • 아사히 가세이 가부시키가이샤

Dates

Publication Date
20260513
Application Date
20241029
Priority Date
20231227

Claims (14)

  1. A resin light guide for displays comprising a methacrylate-based resin composition, and The absolute value of the orientation degree of the methacrylic acid ester monomer unit in the methacrylic resin composition of the above-mentioned resin light guide for display is 0.10 to 0.25, and A resin light guide for displays, wherein the PV value of the effective area surface where image light is guided is 100 μm or less.
  2. A resin light guide for a display according to claim 1, wherein the absolute value of the photoelastic modulus of the methacrylate-based resin composition included in the resin light guide for a display is 10× 10⁻¹² Pa⁻¹ or less.
  3. A resin light guide for displays according to claim 1 or 2, wherein the weight average molecular weight of the methacrylate-based resin composition is 110,000 to 170,000.
  4. A resin light guide for a display, wherein, in claim 1 or 2, the glass transition temperature (Tg) of the methacrylate resin composition is 115℃ to 150℃.
  5. A resin light guide for a display, wherein the absolute value of the in-plane phase difference in claim 1 or 2 is 10 nm or less.
  6. A resin light guide for a display, wherein, in claim 1 or 2, the methacrylic resin composition comprises a methacrylic resin having a structural unit having a ring structure.
  7. A resin light guide for a display according to claim 6, wherein the structural unit having the ring structure comprises at least one structural unit selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, a glutarimide-based structural unit, an aromatic vinyl structural unit, a dicyclic vinyl structural unit, and a lactone ring structural unit.
  8. A resin light guide for a display, wherein, in claim 6, the structural unit having the above-mentioned ring structure comprises a structural unit derived from an N-substituted maleimide monomer.
  9. A resin light guide for a display, having a thickness of 0.8 mm or less, in accordance with claim 1 or 2.
  10. A resin light guide for a display, wherein, in claim 1 or 2, at least one of the incident and exit portions of light is provided with a diffraction optical element.
  11. In paragraph 1 or 2, a part of the surface or a plurality of locations has a fine convex shape, A resin light guide for a display, having a fine convex shape with a line width of 0.10 to 2.00 μm.
  12. A light guide made of resin for a display, wherein the ratio of the line width to the height of the micro-convex shape (height)/(line width) is 0.10 to 1.50.
  13. An image display device having a resin light guide for display as described in paragraph 1 or 2.
  14. A method for manufacturing a resin light guide for a display by injection compression molding of a thermoplastic resin composition, Includes a resin filling process and a compression process, The temperature extending from the nozzle tip to the center of the injection molding machine cylinder is set to a temperature 120 to 180°C higher than the glass transition temperature (Tg) of the thermoplastic resin composition, and the mold temperature is set to a range of (Tg-80)°C to (Tg-35)°C with respect to the glass transition temperature (Tg) of the thermoplastic resin composition. A method for manufacturing a resin light guide for a display, characterized by adjusting each condition of the injection speed and filling time in the resin filling process, the compression distance, compression time and compression pressure in the compression process, and the compression delay time and cooling time set between the resin filling process and the compression process to satisfy (1) and (2) below. (1) The absolute value of the in-plane phase difference of the resin light guide for the display is 10 nm or less. (2) In the above resin light guide for display, the PV value of the effective area surface where image light is guided is 100 μm or less.

Description

Resin light guide for display, image display device, and method for manufacturing a resin light guide for display The present invention relates to a resin light guide for a display, an image display device, and a method for manufacturing a resin light guide for a display. Recently, AR (augmented reality) displays have been commercialized, which guide light emitted from an image display element to the observer's eyeball via a waveguide and allow the observer to view an image using a diffractive optical element. Since AR (augmented reality) displays are image display devices that are mounted on a head, they are required to be small, thin, lightweight, and cause minimal discomfort when mounted. Therefore, for the purpose of weight reduction, attempts are being made to convert conventional glass light guides into resins, and the following Patent Document 1 and Patent Document 2 disclose light guides produced by injection molding. FIG. 1 is a schematic diagram for evaluating the clarity of a display image of a resin light guide for a display in an embodiment. Figure 2 is a schematic diagram of the PV value of a light guide when measuring. Figure 3 is a drawing of a micro-convex shape measured with an atomic force microscope. FIG. 4 is a schematic diagram for evaluating the polarization retention degree of a resin light guide for a display in an embodiment. Hereinafter, forms for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail; however, the present invention is not limited to the description below and can be implemented with various modifications within the scope of its gist. (Resin light guide for displays) The resin light guide for a display according to the present embodiment (hereinafter also simply referred to as "resin light guide" or "light guide") is, It includes a methacrylate resin composition, The degree of orientation of the methacrylic acid ester monomer unit in the above methacrylate resin composition is 0.10 to 0.25, and It is characterized by the PV value of the effective area plane where the image light is guided being 100 μm or less. Here, the display in the resin light guide for a display of the present invention may include display devices such as head-mounted displays, wearable displays, and automotive displays. The degree of orientation of the methacrylic acid ester monomer units in the methacrylic resin composition included in the light guide of the present embodiment is 0.10 to 0.25, preferably 0.11 to 0.20, more preferably 0.12 to 0.15, and even more preferably 0.12 to 0.13. When the degree of orientation of the methacrylic acid ester monomer units is within the above range, the orientation birefringence is suppressed, thereby suppressing the birefringence of the light guide and preventing a deterioration in image quality. In addition, when the degree of orientation is within the above range, the strength is appropriate, so when the light guide is released from the mold during molding, no cracks occur, and a light guide with a good appearance can be obtained. As a method for controlling the degree of orientation described above, as described below, methods such as controlling the weight-average molecular weight of the resin included in the light guide, or values such as the mold temperature or injection speed during injection molding, may be cited. In addition, the degree of orientation can be measured by the method described in the embodiments described below. The light guide body of the present embodiment has a PV value of the effective area surface through which image light is guided, which is 100 μm or less, preferably 95 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. Since a smaller PV value tends to result in a light guide body with higher flatness, a good appearance with suppressed bending or thickness non-uniformity, and excellent image quality, a smaller PV value is preferable. As mentioned above, a smaller PV value is preferable, but from the perspective of manufacturing an efficient light guide body, a PV value of 3 μm or more is acceptable. Furthermore, the effective area surface refers to each surface used to guide image light, and the PV value of the effective area surface refers to the PV value of each surface used to guide image light. As a method for controlling the above-mentioned PV value, it can be controlled by the mold temperature or molding conditions during the molding of the resin, as described below. For example, if the mold temperature is excessively high, warping occurs, and the PV value tends to deteriorate. In addition, the PV value can be measured by the method described in the embodiments described below. If a portion having a diffraction function is attached to the surface of the light guide, the PV value can be obtained by measuring the surface excluding said portion. In addition, if a portion having a diffraction function is not attached to the surfac