US 12,228,731 B2
Light guide element and image display apparatus
Hiroshi Sato, Minamiashigara (JP); Katsumi Sasata, Minamiashigara (JP); and Yukito Saitoh, Minamiashigara (JP)
Assigned to FUJIFILM Corporation, Tokyo (JP)
Filed by FUJIFILM Corporation, Tokyo (JP)
Filed on May 25, 2022, as Appl. No. 17/824,219.
Application 17/824,219 is a continuation of application No. PCT/JP2020/041805, filed on Nov. 10, 2020.
Claims priority of application No. 2019-212856 (JP), filed on Nov. 26, 2019.
Prior Publication US 2022/0283434 A1, Sep. 8, 2022
Int. Cl. G02B 27/01 (2006.01); F21V 8/00 (2006.01); G02B 5/18 (2006.01)
CPC G02B 27/0101 (2013.01) [G02B 5/1814 (2013.01); G02B 6/0026 (2013.01); G02B 6/005 (2013.01)] 25 Claims
OG exemplary drawing
 
1. A light guide element comprising:
a light guide plate; and
a first A incidence diffraction element, a first B incidence diffraction element, a second A incidence diffraction element, a second B incidence diffraction element, a first A emission diffraction element, a first B emission diffraction element, a second A emission diffraction element, and a second B emission diffraction element that are provided in the light guide plate,
wherein the first A incidence diffraction element, the first B incidence diffraction element, the first A emission diffraction element, and the first B emission diffraction element diffract light in the same wavelength range,
the second A incidence diffraction element, the second B incidence diffraction element, the second A emission diffraction element, and the second B emission diffraction element diffract light in the same wavelength range,
the first A incidence diffraction element and the second A incidence diffraction element diffract incident light in different directions to be incident into the light guide plate,
the first B incidence diffraction element and the second B incidence diffraction element diffract incident light in different directions to be incident into the light guide plate,
the first A emission diffraction element emits light that is diffracted by the first A incidence diffraction element and propagates in the light guide plate from the light guide plate,
the first B emission diffraction element emits light that is diffracted by the first B incidence diffraction element and propagates in the light guide plate from the light guide plate,
the second A emission diffraction element emits light that is diffracted by the second A incidence diffraction element and propagates in the light guide plate from the light guide plate,
the second B emission diffraction element emits light that is diffracted by the second B incidence diffraction element and propagates in the light guide plate from the light guide plate,
a period of a diffraction structure of the first A incidence diffraction element is different from periods of diffraction structures of the second A incidence diffraction element and the second B incidence diffraction element,
a period of a diffraction structure of the first B incidence diffraction element is different from the periods of the diffraction structures of the second A incidence diffraction element and the second B incidence diffraction element,
a period of a diffraction structure of the first A emission diffraction element is different from periods of diffraction structures of the second A emission diffraction element and the second B emission diffraction element,
a period of a diffraction structure of the first B emission diffraction element is different from the periods of the diffraction structures of the second A emission diffraction element and the second B emission diffraction element,
the first A emission diffraction element, the first B emission diffraction element, the second A emission diffraction element, and the second B emission diffraction element are disposed at overlapping positions in a plane direction of a main surface of the light guide plate,
a periodic direction of the diffraction structure of the first A emission diffraction element intersects with a periodic direction of the diffraction structure of the second A emission diffraction element and a periodic direction of the diffraction structure of the second B emission diffraction element, and
a periodic direction of the diffraction structure of the first B emission diffraction element intersects with the periodic direction of the diffraction structure of the second A emission diffraction element and the periodic direction of the diffraction structure of the second B emission diffraction element.