US 12,436,427 B1
Uniformly polarized backlight
Mikko Juhola, Muurla (FI); and Petri Savolainen, Espoo (FI)
Assigned to Distance Technologies Oy, Helsinki (FI)
Filed by Distance Technologies Oy, Helsinki (FI)
Filed on Apr. 22, 2025, as Appl. No. 19/185,889.
Int. Cl. G02F 1/1335 (2006.01)
CPC G02F 1/133607 (2021.01) [G02F 1/133514 (2013.01); G02F 1/133528 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A backlight unit for a liquid crystal display device, the backlight unit comprising an array of light-emitting elements, wherein a given light-emitting element comprises:
a light source configured to emit light rays laterally relative to an optical axis of the backlight unit, wherein the light rays are emitted laterally in at least one direction;
a collimator arranged on an optical path of light rays emitted in an individual one of the at least one direction, to collimate the light rays;
a first prism arranged on said optical path after the collimator, configured to reflect a given portion of the collimated light rays having one of a first polarization orientation and a second polarization orientation along the optical axis of the backlight unit and to transmit another portion of the collimated light rays having another of the first polarization orientation and the second polarization orientation;
a half-wave plate arranged on said optical path after the first prism, configured to rotate a polarization orientation of the another portion of the collimated light rays from the another of the first polarization orientation and the second polarization orientation to the one of the first polarization orientation and the second polarization orientation; and
a second prism arranged on said optical path after the half-wave plate, configured to reflect the another portion of the collimated light rays having the one of the first polarization orientation and the second polarization orientation along the optical axis of the backlight unit.