Films for display covers and display devices comprising the same

1. A display cover for coupling to a display device, the display cover comprising:

a perimeter portion comprising a first surface and a second surface; and

a film of polymeric material attached to at least one of the first surface or the second surface of the perimeter portion, the film comprising a central surface portion, an offset portion, and a peripheral portion, wherein the offset portion extends from the central surface portion, wherein the peripheral portion extends from the offset portion, wherein the peripheral portion includes a first array of prisms extending from an edge of the perimeter portion to a distance L, wherein the first array of prisms is offset from and positioned below the central surface portion of the film by an offset spacing dz, wherein the first array of prisms is offset from the central surface portion of the film by at least one step feature, and wherein the offset spacing dz is equal to (k*λ(n−1))±0.2 μm, where λ=540 nm, k is an integer greater than or equal to 1, and n is an index of refraction of the film.

2. The display cover of claim 1 , wherein the first array of prisms is offset from the surface of the film by a single step feature having a step height equal to the offset spacing dz.

3. The display cover of claim 2 , wherein the single step feature is positioned at an angle of 90 degrees with respect to the central surface portion of the film.

4. The display cover of claim 1 , wherein the first array of prisms is offset from the central surface portion of the film by a plurality of step features and a sum of a step height of individual ones of the plurality of step features is equal to dz.

5. The display cover of claim 1 , wherein k=1, and n≈1.5.

6. The display cover of claim 1 , wherein the first array of prisms is offset from and positioned below the central surface portion of the film by a graded portion that is oriented at an angle φ with respect to the central surface portion such that the central surface portion transitions into the first array of prisms over a distance.

7. A film of polymeric material comprising a central surface portion having a peripheral end, a graded portion having a central end and a peripheral end, and a peripheral portion, wherein the central end of the graded portion extends from the peripheral end of the central surface portion at an acute angle φ relative to the central surface portion, wherein the peripheral portion extends from the peripheral end of the graded portion, wherein the peripheral portion includes a first array of prisms offset from and positioned below the central surface portion of the film by the graded portion by an offset spacing dz, wherein the graded portion is oriented at the acute angle φ with respect to the central surface portion such that the surface transitions into the first array of prisms over a distance.

8. The film of claim 7 , wherein when the film is coupled to a display device, the angle φ is such that light passing through the graded portion of the film is offset by an amount dx which is equal to one pixel size of the display device.

9. The display cover of claim 1 , wherein:

each prism of the first array of prisms has a prism angle θ;

the first array of prisms is configured to shift a portion of an image produced by the display panel; and

the display cover comprises a central region bounded by the perimeter portion, wherein the first array of prisms is not present at the central region.

10. The display cover of claim 1 , wherein the film of polymeric material has at least one edge having a saw tooth pattern formed therein.

11. The display cover of claim 10 , wherein the film is aligned on the display cover such that an edge of each tooth of the saw tooth pattern is parallel with a diagonal of at least one corresponding sub pixel in the display device.

12. The display cover of claim 10 , wherein edges of the saw tooth pattern have a tooth angle which is equal to arctan (SDP), where SDP is a sub-duty pixel factor of the display device.

13. The display cover of claim 12 , wherein the SDP=⅓.

14. A film of polymeric material comprising a central surface portion, a plurality of step features, and a peripheral portion, wherein the plurality of step features is disposed between the central surface portion and the peripheral portion, wherein a first step feature of the plurality of step features is orthogonal to the central surface portion of the film, wherein a second step feature of the plurality of step features is orthogonal to the central surface portion of the film, and wherein the second step feature is offset from and positioned below the first step feature, and wherein the peripheral portion includes a first array of prisms offset from and positioned below the central surface portion of the film by the plurality of step features by an offset spacing dz.

15. The film of claim 14 , wherein at least one step feature of the plurality of step features is a step feature that is positioned at an angle of 90 degrees with respect to the central surface portion of the film.

16. The film of claim 14 , wherein a sum of a step height of individual ones of the plurality of step features is equal to dz.

17. The film of claim 14 , wherein the offset spacing dz is equal to (k*λ(n−1))±0.2 μm, where λ is a median wavelength of light transmitted through the film, k is an integer greater than or equal to 1, and n is an index of refraction of the film.

18. The film of claim 17 , wherein λ=540 nm, k=1, and n≈1.5.

19. The film of claim 7 , wherein when the film is coupled to a display device, the angle φ is such that light passing through the graded portion of the film is offset by an amount dx which is less than 1/10 of a pixel size of the display device.

20. The film of claim 7 , wherein a maximum height of the first array of prisms is offset from and positioned below a plane that intersects a midpoint of the graded portion and that extends parallel to the central surface portion.