Turning film having variable pitch
A light-redirecting article has a width and a length and has a light-redirecting surface with a plurality of light-redirecting structures elongated along the length of the light-redirecting article and arranged side-by-side. Each light-redirecting structure has a first side surface oriented away from a normal to the light-redirecting article at a first angle and a second side surface oriented away from a normal to the light-redirecting article at a second angle. The first and second side surfaces meet at an apex. The cross-sectional shape of each light-redirecting structure has at least one convex surface. For at least two adjacent light-redirecting structures, over the length of the at least two adjacent light-redirecting structures, the widthwise pitch between apexes of the adjacent light-redirecting structures varies by more than +/−3%.
1 . A light-redirecting article having a width and a length, comprising:
a light-redirecting surface comprising a plurality of light-redirecting structures elongated along the length of the light-redirecting article and arranged side-by-side,
wherein each light-redirecting structure comprises:
(i) a first side surface oriented away from a normal to the light-redirecting article at a first angle;
(ii) a second side surface oriented away from a normal to the light-redirecting article at a second angle,
wherein the cross-sectional shape of each light-redirecting structure has at least one convex surface;
wherein the first and second side surfaces meet at an apex; and
wherein, for at least two adjacent light redirecting structures, over the length of the adjacent light redirecting structures the widthwise pitch between apexes of the adjacent light-redirecting structures varies by more than +/−3%.
2 . The light-redirecting article of claim 1 wherein the apex is a flat surface.
3 . The light-redirecting article of claim 1 wherein the light-redirecting article comprises a layer integral with a film substrate.
4 . The light-redirecting article of claim 1 wherein the light-redirecting structures are applied to a substrate layer.
5 . The light-redirecting article of claim 1 wherein at least two adjacent light-redirecting structures have substantially the same height.
6 . The light-redirecting article of claim 1 wherein all of the light-redirecting structures have substantially the same height.
7 . The light-redirecting article of claim 1 wherein the widthwise pitch between the apexes of the adjacent light-redirecting structures increases and decreases in a random pattern over the length of the light-directing surface.
8 . The light redirecting article of claim 7 wherein the pitch between the apexes of the adjacent light-redirecting structures increases and decreases by more than +/−3% in a random pattern over the length of the element.
9 . The light-redirecting article of claim 1 wherein at least two adjacent light-redirecting structures extend along a substantially sinusoidal path over the length of the light-directing surface.
10 . The light-redirecting article of claim 1 wherein the first angle is between 1 and 25 degrees from normal.
11 . The light-redirecting article of claim 1 wherein the convex curvature is spherical.
12 . A method of manufacture of a light-redirecting article comprising:
a) rotating a cylinder;
b) scribing the rotating cylinder with a tool to form adjacent scribe marks having a pitch that, over one full rotation of the cylinder, varies by more than +/−3%; and
c) forming the light-redirecting article using the scribed cylinder in an injection roll molding process.
13 . The method of manufacturing of claim 12 wherein the resulting light redirecting article has a width and a length, comprising:
a light-redirecting surface comprising a plurality of light-redirecting structures elongated along the length of the light-redirecting article and arranged side-by-side,
wherein each light-redirecting structure comprises:
(i) a first side surface oriented away from a normal to the light-redirecting article at a first angle;
(ii) a second side surface oriented away from a normal to the light-redirecting article at a second angle,
wherein the cross-sectional shape of each light-redirecting structure has at least one convex surface ; wherein the first and second side surfaces meet at an apex; and wherein, for at least two adjacent light redirecting structures, over the length of the adjacent light redirecting structures the widthwise pitch between apexes of the adjacent light-redirecting structures varies by more than +/−3%.
14 . The method of manufacture according to claim 12 wherein scribing the rotating cylinder comprises tracing a substantially sinusoidal path with a scribing tool.
15 . A display apparatus comprising
a) a light source;
b) a light guiding plate for directing light from the light source outward from an output surface, over a range of angles;
c) a light-redirecting article for accepting the light from the light guiding plate, the light redirecting article having a width and a length, comprising:
a light-redirecting surface comprising a plurality of light-redirecting structures elongated along the length of the light-redirecting article and arranged side-by-side,
wherein each light-redirecting structure comprises:
(i) a first side surface oriented away from a normal to the light-redirecting article at a first angle;
(ii) a second side surface oriented away from a normal to the light-redirecting article at a second angle,
wherein the cross-sectional shape of each light-redirecting structure has at least one convex surface;
wherein the first and second side surfaces meet at an apex; and
wherein, for at least two adjacent light redirecting structures, over the length of the adjacent light redirecting structures the widthwise pitch between apexes of the adjacent light-redirecting structures varies by more than +/−3%.
the light-redirecting article providing illumination thereby; and,
d) a light gating device for modulating the incident illumination from the light-redirecting article.
16 . The display apparatus of claim 15 wherein the apexes of the light redirecting structures are a flat surface.
17 . The display apparatus of claim 15 wherein the light-redirecting article is integral with a film substrate.
18 . The display apparatus of claim 15 wherein the light-redirecting structures of the light redirecting article are applied to a substrate layer.
19 . The display apparatus of claim 15 wherein the at least two adjacent light-redirecting structures of the light redirecting article have substantially the same height.
20 . The display apparatus of claim 15 wherein all of the light-redirecting structures of the light redirecting article have substantially the same height.
21 . The display apparatus of claim 15 wherein the widthwise pitch between the apexes of the adjacent light-redirecting structures increases and decreases in a random pattern over the length of the light-directing surface.
22 . The display apparatus of claim 21 wherein the pitch between the apexes of the adjacent light-redirecting structures increases and decreases by more than +/−3% in a random pattern over the length of the light-directing surface.
23 . The display apparatus of claim 15 wherein the apex angles of the at least two adjacent light-redirecting structures of the light redirecting article extend along a substantially sinusoidal path along the length of the light-directing surface.
24 . The display apparatus of claim 15 wherein the first angle of the light redirecting structure is between 1 and 25 degrees from normal.
25 . The display apparatus of claim 15 wherein the convex curvature of the cross-sectional shape of each light-redirecting structure is spherical.