US 12,443,044 B2
Projection substrate and smart glasses
Tatsuo Inabata, Tokyo (JP); Susumu Tateoka, Tokyo (JP); Toshiaki Shozu, Tokyo (JP); and Satoshi Shiraga, Tokyo (JP)
Assigned to Cellid, Inc., Tokyo (JP)
Filed by Cellid, Inc., Tokyo (JP)
Filed on Mar. 21, 2024, as Appl. No. 18/613,024.
Application 18/613,024 is a continuation of application No. PCT/JP2021/034799, filed on Sep. 22, 2021.
Prior Publication US 2024/0231110 A1, Jul. 11, 2024
Int. Cl. G02B 27/01 (2006.01); G02B 27/09 (2006.01); G02B 27/10 (2006.01)
CPC G02B 27/0172 (2013.01) [G02B 27/0955 (2013.01); G02B 27/1086 (2013.01); G02B 2027/0178 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A projection substrate for projecting an image light onto a second surface while transmitting at least a part of light that entered from a first surface to the second surface opposite to the first surface, the projection substrate comprising:
an incident region that includes a diffraction grating in which a plurality of first grooves are formed with a first period;
a splitting region that includes a diffraction grating in which a plurality of second grooves are formed with a second period; and
an emission region that includes a diffraction grating in which a plurality of third grooves are formed with a third period; wherein
a projection light for causing the image light to be projected enters the incident region, and the incident region guides the incident projection light toward the splitting region,
the splitting region includes a plurality of first divided regions arranged in a traveling direction of the incident projection light, each having the second grooves with different depths, and the splitting region includes a first reflection region that reflects at least a part of light that has passed through the plurality of first divided regions to the plurality of first divided regions again,
the first reflection region is provided adjacent to the first divided region at a position furthest from the incident region on the same plane as the first divided region, and the first reflection region reflects light incident from the adjacent first divided region toward the adjacent first divided region, and
wherein the plurality of first divided regions guides a part of the projection light that entered from the incident region toward the emission region, and guides at least a part of the light reflected by the first reflection region to the emission region, and
the emission region guides at least a part of the projection light that entered from the splitting region and emits that part of the projection light as the image light from the second surface.