Augmented reality display having liquid crystal variable focus element and roll-to-roll method and apparatus for forming the same
A display device includes a waveguide assembly comprising a waveguide configured to outcouple light out of a major surface of the waveguide to form an image in the eyes of a user. An adaptive lens assembly has a major surface facing the output surface and a waveplate lens and a switchable waveplate assembly. The switchable waveplate assembly includes quarter-wave plates on opposing sides of a switchable liquid crystal layer, and electrodes on the quarter-wave plates in the volume between the quarter-wave plates. The electrodes can selectively establish an electric field and may serve as an alignment structure for molecules of the liquid crystal layer. Portions of the adaptive lens assembly may be manufactured by roll-to-roll processing in which a substrate roll is unwound, and alignment layers and liquid crystal layers are formed on the substrate as it moves towards a second roller, to be wound on that second roller.
1. A display device comprising:
a waveguide assembly comprising a waveguide configured to output light to display an image; and
an adaptive lens assembly having a major surface facing a major surface of the waveguide, the adaptive lens assembly comprising:
a waveplate lens comprising a liquid crystal polymer layer; and
a switchable waveplate assembly comprising:
a first substrate and a second substrate defining a volume therebetween, wherein the first substrate is a first quarter-wave plate and the second substrate is a second quarter-wave plate, and wherein the first substrate and the second substrate are composed of a non-liquid crystal material that is optically transmissive and pliable;
a liquid crystal layer disposed within the volume;
a first set of guides for aligning liquid crystal molecules of the liquid crystal layer, the first set of guides comprising a first electrode pattern disposed in the volume and directly on the first substrate; and
a second set of guides for aligning the liquid crystal molecules of the liquid crystal layer, the second set of guides comprising a second electrode pattern disposed in the volume and directly on the second substrate;
wherein the first electrode pattern and the second electrode pattern extend into the liquid crystal layer and are configured to selectively apply an electric field, and
wherein the first electrode pattern and the second electrode pattern are configured to:
cause a first orientation of the liquid crystal molecules of the liquid crystal layer when the electric field is not applied, to cause the adaptive lens assembly to provide a first optical power, and
cause a second orientation of the liquid crystal molecules when the electric field is applied, to cause the adaptive lens assembly to provide a second optical power that is different than the first optical power.
2. The display device of claim 1 , wherein at least one of the first electrode pattern and the second electrode pattern comprises an array of parallel conductors.
3. The display device of claim 1 , wherein at least one of the first electrode pattern and the second electrode pattern comprises a wire mesh.
4. The display device of claim 1 , wherein the waveplate lens and the switchable waveplate assembly constitute an adaptive lens subassembly, wherein the adaptive lens assembly comprises a plurality of adaptive lens subassemblies, each adaptive lens subassembly comprising:
a waveplate lens; and
a switchable waveplate assembly.
5. The display device of claim 1 , further comprising an other adaptive lens assembly on the opposite side of the waveguide assembly from the adaptive lens assembly, wherein the other adaptive lens assembly comprises an associated waveplate lens and an associated switchable waveplate assembly.
6. An adaptive lens assembly comprising:
a waveplate lens comprising a liquid crystal polymer layer;
a switchable waveplate assembly comprising:
a first substrate and a second substrate defining a volume therebetween, wherein the first substrate is a first quarter-wave plate and the second substrate is a second quarter-wave plate, and wherein the first substrate and the second substrate are composed of a non-liquid crystal material that is optically transmissive and pliable;
a liquid crystal layer disposed within the volume;
a first set of guides for aligning liquid crystal molecules of the liquid crystal layer, the first set of guides comprising a first electrode pattern disposed in the volume and directly on the first substrate; and
a second set of guides for aligning the liquid crystal molecules of the liquid crystal layer, the second set of guides comprising a second electrode pattern disposed in the volume and directly on the second substrate;
wherein the first electrode pattern and the second electrode pattern extend into the liquid crystal layer and are configured to selectively apply an electric field, and
wherein the first electrode pattern and the second electrode pattern are configured to:
cause a first orientation of the liquid crystal molecules of the liquid crystal layer when the electric field is not applied, to cause the switchable waveplate assembly to provide a first optical power, and
cause a second orientation of the liquid crystal molecules when the electric field is applied, to cause the switchable waveplate assembly to provide a second optical power that is different than the first optical power.
7. The adaptive lens assembly of claim 6 , wherein at least one of the first electrode pattern and the second electrode pattern comprises an array of parallel conductors.
8. The adaptive lens assembly of claim 6 , wherein at least one of the first electrode pattern and the second electrode pattern comprises a wire mesh.
9. The adaptive lens assembly of claim 6 , wherein the adaptive lens assembly further comprises an alignment layer disposed between the waveplate lens and the first quarter-wave plate, wherein the alignment layer at least partially determines orientations of the liquid crystal molecules in the liquid crystal polymer layer.
10. The adaptive lens assembly of claim 6 , wherein the waveplate lens comprises an other liquid crystal polymer layer on the liquid crystal polymer layer.
11. The adaptive lens assembly of claim 6 , wherein the waveplate lens and the switchable waveplate assembly constitute an adaptive lens subassembly, wherein the adaptive lens assembly comprises a plurality of adaptive lens subassemblies, each adaptive lens subassembly comprising:
a waveplate lens; and
a switchable waveplate assembly.
12. The display device of claim 1 , wherein the switchable waveplate assembly further comprises an optically transmissive cap material comprising a metal or an ionic compound overlying at least a portion of the first electrode pattern or the second electrode pattern.
13. The display device of claim 12 , wherein the cap material comprises an anti-reflective coating.
14. The adaptive lens assembly of claim 6 , wherein the first electrode pattern and the second electrode pattern each comprise:
a layer disposed on the first or second substrate and comprising a plurality of protrusions extending into the volume; and
a layer of conductive material conformally disposed on at least a portion of the plurality of protrusions.
15. The adaptive lens assembly of claim 6 , wherein the switchable waveplate assembly further comprises an optically transmissive cap material comprising a metal or an ionic compound overlying at least a portion of the first electrode pattern or the second electrode pattern.
16. The adaptive lens assembly of claim 15 , wherein the cap material comprises an anti-reflective coating.
17. The display device of claim 1 , wherein:
the first orientation of the liquid crystal molecules causes the adaptive lens assembly to provide substantially zero optical power when the electric field is not applied, and
the second orientation of the liquid crystal molecules causes the adaptive lens assembly to provide a positive optical power or a negative optical power when the electric field is applied.
18. The display device of claim 17 , wherein the display device is configured to be worn by a user, and wherein:
the adaptive lens assembly is on a user side of the waveguide assembly and the second orientation of the liquid crystal molecules causes the adaptive lens assembly to provide the negative optical power when the electric field is applied, or
the adaptive lens assembly is on a world side of the waveguide assembly and the second orientation of the liquid crystal molecules causes the adaptive lens assembly to provide the positive optical power when the electric field is applied.
19. The display device of claim 1 , wherein the adaptive lens assembly has an overall thickness between about 1 mm and about 3 mm.
20. The adaptive lens assembly of claim 6 , wherein the adaptive lens assembly has an overall thickness between about 1 mm and about 3 mm.