Textured surfaces for display applications
A substrate with a textured surface is disclosed. The substrate may be, for example, a light emitter comprising a light guide, for example a backlight element for use in a display device, wherein a surface of the light guide, for example a glass substrate, is configured to have a textured surface with a predetermined RMS roughness and a predetermined correlation length of the texture. A plurality of light scatter suppressing features can be provided on the textured surface. Textured surfaces disclosed herein may be effective to reduce electrostatic charging of the substrate surface. Methods of producing the textured surface are also disclosed.
1. A substrate comprising at least one textured major surface comprising a figure of merit FOM in a range from greater than zero to about 0.78, wherein FOM is calculated as
FOM
=
CA
·
δ
m
N
×
∑
i
=
1
N
1
Δ
i
m
and
Δ
i
=
{
h
t
-
h
i
+
δ
h
i
≤
h
t
h
t
+
δ
h
i
>
h
t
,
where δ represents a minimum distance between a contacted area of the textured major surface with a contact plane for which 0.1≤δ≤10 nm, Δ represents the extent of separation from the contact plane, CA is the contact area given by the number of pixels for which h i ≥h t , h i represents the surface height data for N surface height elements, h t represents a threshold height defining the contribution of uppermost heights on the textured surface that come into contact with the contact plane for which 0.5≤h t ≤0.999, and m weights the importance of separation distance for pixels not contacting the contact plane for which m is a whole number in a range from 2 to 6.
2. The substrate according to claim 1 , wherein the substrate comprises a transmittance equal to or greater than 94%.
3. The substrate according to claim 1 , wherein the substrate comprises a haze equal to or less than 6%.
4. The substrate according to claim 3 , wherein the haze is equal to or less than 1%.
5. The substrate according to claim 1 , wherein an average roughness R a of the textured surface is 0.4≤R a ≤10 nm.
6. The substrate according to claim 1 , wherein a correlation length T of the surface texture is equal to or less than 150 nm.
7. The substrate according to claim 6 , wherein an RMS roughness R q of the textured surface is 5 nm≤R q ≤75 nm.
8. The substrate according to claim 1 , wherein the substrate is a glass substrate.
9. The substrate according to claim 1 , wherein m is 2.
10. The substrate according to claim 1 , wherein m is 6.
11. The substrate according to claim 1 , wherein 0.1≤δ≤2 nm.
12. The substrate according to claim 11 , wherein 0.5≤δ≤2 nm.
13. The substrate according to claim 1 , wherein 0.75≤h t ≤0.99.
14. The substrate according to claim 1 , wherein 0.7≤h t ≤0.9.
15. The substrate according to claim 1 , wherein the FOM is in a range from 0.22 to 0.77.
16. The substrate according to claim 15 , wherein the FOM is in a range from 0.61 to 0.77.
17. The substrate according to claim 1 , wherein the substrate comprises a transmittance in a range from greater than 94% to 100%.