Backlit Devices with Multiwall Sheets and Methods of Making the Same

1 . A backlit device, comprising:

a multiwall sheet having a viewing side, wherein the multiwall sheet comprises;

polymer walls; and

a rib that intersects at least two of the walls, wherein the rib comprises a non-linear geometry; and

a light source located on a side of the multiwall sheet opposite the viewing side, wherein the light source is configured to direct light at the multiwall sheet.

2 . The device of claim 1 , wherein an outer wall of the multiwall sheet comprises indentations, and wherein the light source is disposed adjacent to the indentations.

3 . The device of claim 1 , comprising a hiding power of 0 to about 2.

4 . The device of claim 1 , wherein rib comprises a different composition than at least one of the walls.

5 . The device of claim 1 , wherein the rib has a different thickness than the walls.

6 . The device of claim 5 , wherein the rib thickness is about 25% to about 80% of a wall thickness.

7 . The device of claim 1 , wherein the rib is textured.

8 . The device of claim 1 , comprising no diffusing sheet between the multiwall sheet and the light source.

9 . The device of claim 1 , wherein the multiwall sheet has a weight of less than or equal to 2 kg/m 2 .

10 . The device of claim 1 , further comprising a collimating sheet located on the viewing side of the multiwall sheet.

11 . The device of claim 10 , further comprising a liquid crystal display, wherein the collimating sheet is located between the viewing side of the multiwall sheet and the liquid crystal display.

12 . The device of claim 1 , wherein the rib has a ratio of amplitude to period of about 0.6 to about 5.4.

13 . The device of claim 1 , further comprising further comprising a recycling polarizer sheet, wherein the recycling polarizer sheet is located between the viewing side of the multiwall sheet and the liquid crystal display.

14 . A backlit device, comprising:

a multiwall sheet having a viewing side, wherein the multiwall sheet comprises;

walls, wherein an outer wall on the viewing side has a wall transmission; and

a rib that intersects at least two of the walls, wherein the rib has a rib transmission that is greater than the wall transmission as determined in accordance with ASTM D1003-00; and

a light source located on a side of the multiwall sheet opposite the viewing side, wherein the light source is configured to direct light at the multiwall sheet.

15 . A backlit device, comprising:

a multiwall sheet having a viewing side, wherein the multiwall sheet comprises;

polymer walls; and

a rib that intersects at least two of the walls, wherein the rib comprises a textured surface; and

a light source located on a side of the multiwall sheet opposite the viewing side, wherein the light source is configured to direct light at the multiwall sheet.

16 . The device of claim 15 , wherein the textured surface is on the viewing side.

17 . A backlit device, comprising:

a multiwall sheet having a viewing side, wherein the multiwall sheet comprises;

polymer walls; and

a rib that intersects at least two of the walls, wherein the rib comprises a sinusoidal geometry;

a light source located on a side of the multiwall sheet opposite the viewing side, wherein the light source is configured to direct light at the multiwall sheet;

an liquid crystal display located on the viewing side of the multiwall sheet; and

a collimating sheet located between the liquid crystal display and the multiwall sheet.

18 . The device of claim 17 , further comprising a diffuser sheet located between the multiwall sheet and the collimating sheet.

19 . A backlit device, comprising:

a multiwall sheet having a viewing side, wherein the multiwall sheet comprises;

polymer walls; and

a rib that intersects at least two of the walls;

wherein the multiwall sheet has a weight of less than or equal to 1.9 kg/m 2 ;

a light source located on a side of the multiwall sheet opposite the viewing side, wherein the light source is configured to direct light at the multiwall sheet; and

a collimating sheet located on the viewing side of the multiwall sheet;

wherein the device has a hiding power of 0 to about 2.0.

20 . A method for making a backlit device, comprising:

locating a multiwall sheet between a light source and a collimating sheet, wherein the multiwall sheet comprises polymer walls and a rib that intersects at least two of the walls.

21 . The method of claim 20 , further comprising coextruding the multiwall sheet and a diffuser sheet.

22 . The method of claim 20 , further comprising disposing a liquid crystal display on a side of the collimating sheet opposite the multiwall sheet.