Optical device
An optical device capable of varying transmittance, such that can be used for various applications such as eyewear, for example, sunglasses or AR (augmented reality) or VR (virtual reality) eyewear, an outer wall of a building or a sunroof for a vehicle.
1. An optical device comprising:
first and second outer substrates disposed opposite to each other;
an active liquid crystal element film having an active liquid crystal layer which contains a liquid crystal compound and is capable of switching between a first oriented state and a second oriented state;
a polarizer; and
a same adhesive material existing between the first outer substrate and the active liquid crystal element film, between the active liquid crystal element film and the polarizer, between the polarizer and the second outer substrate, and on sides of the active liquid crystal element film;
wherein the active liquid crystal element film and the polarizer are positioned between the first and second outer substrates and are separately encapsulated by the same adhesive material,
wherein a dynamic friction coefficient between a surface of the active liquid crystal element film and the adhesive material is 0.5 or more and 5 or less,
wherein the active liquid crystal element film comprises two plastic films disposed opposite to each other and the active liquid crystal layer is between the two plastic films,
wherein each of the two plastic films has a coefficient of thermal expansion in a range of 10 ppm/K or more, and
wherein the adhesive material has a front phase difference in a range of 1 nm or more and an absolute value of a thickness direction phase difference in a range of 2 nm or more.
2. The optical device according to claim 1 , wherein the adhesive material is a thermoplastic polyurethane film.
3. The optical device according to claim 1 , wherein the active liquid crystal element film and the polarizer are disposed such that an angle formed by an average optical axis of the active liquid crystal layer in the first oriented state and a light absorption axis of the polarizer is in a range of 80 degrees to 100 degrees or 35 degrees to 55 degrees.
4. The optical device according to claim 1 , wherein the active liquid crystal element film further comprises spacers for maintaining an interval of the two base films between the two base films.
5. The optical device according to claim 1 , wherein each of the two plastic films has a coefficient of thermal expansion in a range of 55 ppm/K or more.
6. The optical device according to claim 1 , wherein each of the two plastic films further comprises a respective alignment film present on a side of the plastic film facing the active liquid crystal layer.
7. The optical device according to claim 6 , wherein an angle formed by alignment directions of the respective alignment films of the two plastic films is in a range of −10 degrees to 10 degrees, in a range of 80 degrees to 90 degrees, or in a range of 160 degrees to 200 degrees.
8. The optical device according to claim 6 , wherein a first one of the two plastic films is closer to the polarizer than a second one of the two plastic films, and wherein an angle formed by:
an alignment direction of the alignment film formed on the first base film; and
a light absorption axis of the polarizer
is in a range of 80 degrees to 100 degrees.
9. The optical device according to claim 1 , wherein the active liquid crystal element film is in a folded film form.
10. The optical device according to claim 1 , wherein the adhesive material has the front phase difference in a range of 2 nm or more.
11. The optical device according to claim 1 , wherein the adhesive material has an absolute value of the thickness direction phase difference in a range of 3 nm or more.
12. The optical device according to claim 1 , wherein the adhesive material has a Young's modulus in a range of 0.1 to 100 MPa.
13. An automobile comprising:
a body on which one or more openings are formed; and
the optical device of claim 1 attached to the openings.
14. The optical device according to claim 1 , wherein the adhesive material is applied to each of the first outer substrate, the active liquid crystal element film, the polarizer and the second outer substrate by an autoclave process.
15. The optical device according to claim 14 , wherein the first and second outer substrates are curved, and wherein a curvature of each of the first and second outer substrates is controlled to provide a restoring force to the adhesive material sufficient to avoid forming bubbles between the first and second outer substrates due to widening of the adhesive material during an autoclave process.