LIGHT GUIDE PLATE AND IMAGE DISPLAY DEVICE

• Main Author: SHIMIZU KAZUE
• Format: Patent
• Language: English; Japanese
• Published: 07.09.2023
• Subjects: BLASTING; HEATING; LIGHTING; MECHANICAL ENGINEERING; NON-PORTABLE LIGHTING DEVICES; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLEEXTERIORS; WEAPONS

To improve image quality by suppressing loss due to Fresnel reflection.SOLUTION: A light guide plate at least comprises: an incident diffraction grating that diffracts incident light into a light guide plate; a substrate that guides the light diffracted by the incident diffraction grating into the light guide plate through total internal reflection; and a function portion that transmits and/or reflects the incident light. When a refractive index of the substrate is nb, transmittance T0 of 0-order transmitted light of the function portion at substantially the center of an area of the angle of view where the light is to be guided satisfies the following formula (1): T0>1-(nb-1)2/(nb+1)2 ...(1)SELECTED DRAWING: Figure 2 【課題】フレネル反射による損失の抑制により画質を向上させること。【解決手段】入射される光を導光板内部に回折する入射回折格子と、前記入射回折格子が前記導光板内部に回折した前記光を内部全反射して導光する基板と、入射される前記光を透過若しくは反射又はその両方を行う機能部と、を少なくとも備えており、前記基板の屈折率をｎｂとするとき、導光する画角エリアの略中心における前記機能部の０次透過光の透過率Ｔ０が、次の式（１）を満たす、導光板を提供する。Ｔ０＞１－（ｎｂ－１）２／（ｎｂ＋１）２・・・（１）【選択図】図２