US 11,947,149 B2
Reflective display with film-based lightguide frontlight including light turning film with coated surfaces
Anthony Nichol, Minneapolis, MN (US); and Zane Coleman, Elmhurst, IL (US)
Assigned to Azumo, Inc., Chicago, IL (US)
Filed by Azumo, Inc., Chicago, IL (US)
Filed on Nov. 28, 2022, as Appl. No. 18/059,413.
Application 18/059,413 is a continuation of application No. 17/630,849, granted, now 11,513,274, previously published as PCT/US2020/070341, filed on Jul. 31, 2020.
Claims priority of provisional application 62/881,792, filed on Aug. 1, 2019.
Prior Publication US 2023/0099260 A1, Mar. 30, 2023
Int. Cl. F21V 8/00 (2006.01)
CPC G02B 6/0028 (2013.01) [G02B 6/0016 (2013.01); G02B 6/0076 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A display comprising:
a. a reflective spatial light modulator having a reflective surface;
b. a lightguide comprising:
i). a core layer having opposing surfaces with a thickness not greater than 0.5 millimeters therebetween wherein light propagates by total internal reflection between the opposing surfaces;
ii). a first cladding layer having a first side optically coupled to the core layer and an opposing second side; and
iii). a light emitting region comprising a plurality of light extraction features arranged in a pattern that varies spatially in the light emitting region;
c. a light source positioned to emit light that propagates into the core layer, totally internally reflects within the core layer, and is extracted from the core layer by the plurality of light extraction features such that the light exits the core layer in the light emitting region into the first cladding layer; and
d. a light turning film optically coupled to the second side of the first cladding layer, the light turning film comprising a plurality of light turning features comprising a first surface and a second surface adjacent the first surface, the first surface of the light turning features directing the light extracted from the core layer by the plurality of light extraction features toward the reflective spatial light modulator, wherein the first surface comprises a coating of a first thickness of a first material with a first refractive index oriented at an angle between 5 degrees and 50 degrees relative to a direction perpendicular to a thickness direction of the light turning film, and the second surface is oriented at a non-zero angle to the direction orthogonal to the thickness direction of the light turning film and does not comprise a coating of the first material or comprises a coating of a second thickness of the first material less than the first thickness and less than 500 nanometers.