Asymmetric serrated edge light guide film having circular base segments

1. A planar light guide film for a backlight unit having at least one point light source, the light guide film comprising:

a light input surface for receiving light from the point light source;

a light redirecting surface for redirecting light received from the light input surface;

a light output surface for outputting at least the light redirected from the light redirecting surface;

wherein the light input surface further comprises a composite lens structure having a first and second circular tip segment each circular tip segment with a first contact angle, and a first and second circular base segment each circular base segment with a top and bottom contact angle, the contact angles of the circular base segments being greater than the contact angle of the circular tip segments; and

wherein the first and second circular tip segments satisfies the following equations:

y 1 =a 1 +√{square root over (( r 1 2 −x 2 ))}

y 2 a 2 +√{square root over (( r 2 2 −x 2 ))}

wherein x is a value in a direction of the light input surface, y 1 is a value in a light propagation direction, r 1 is a radius of the first circular tip segment, a 1 is a y-coordinate of a center of the first circular tip segment, y 2 is a value in the light propagation direction, r 2 is a radius of the second circular tip segment, a 2 is a y-coordinate of a center of the second circular tip segment, and the first and second circular base segments satisfies the following equations:

y 3 =b 3 +√{square root over (( r 3 2 −( x+a 3 ) 2 ))}

y 4 =b 4 +√{square root over (( r 4 2 −( x−a 4 ) 2 ))}

wherein y 3 is a value in the light propagation direction, r 3 is a radius of the first circular base segment, a 3 and b 3 are x- and y-coordinates respectively of a center of the first circular base segment, y 4 is a value in the light propagation direction, r 4 is a radius of the second circular base segment, and a 4 and b 4 are x- and y-coordinates respectively of a center of the second circular base segment, and each of the composite lens structures is randomly disposed along the light input surface.

2. The planar light guide film of claim 1 wherein the composite lens structure has a pitch P greater than or equal to 5 micrometers and less than or equal to 1 millimeter.

3. The planar light guide film of claim 2 wherein the composite lens structure has a gap G less than or equal to 0.9 times the pitch P.

4. The planar light guide film of claim 1 wherein the composite lens structure has a total height H greater than 3 micrometers and less than or equal to 1 millimeter.

5. The planar light guide film of claim 1 wherein the first circular tip segment of the composite lens structure has a contact angle A 1 greater than 0.1 degrees and less than or equal to 85 degrees.

6. The planar light guide film of claim 1 wherein the second circular tip segment of the composite lens structure has a contact angle A 2 greater than 0.1 degrees and less than or equal to 85 degrees.

7. The planar light guide film of claim 1 wherein contact angles A 1 and A 2 of the of the composite lens structure are not equal.

8. The planar light guide film as in any one of claims 5 - 7 wherein the composite lens structure further comprises contact angles A 31 , A 41 , A 32 , and A 42 wherein A 31 ≠A 41 , A 32 ≠A 42 and A 1 ≦A 31 , A 31 ≦A 32 , A 2 ≦A 41 , A 41 ≦A 42 .

9. A planar light guide film for a backlight unit having at least one point light source, the light guide film comprising:

a light input surface for receiving light from the point light source;

a light redirecting surface for redirecting light received from the light input surface;

a light output surface for outputting at least the light redirected from the light redirecting surface;

wherein the light input surface further comprises a composite lens structure having gaps there between, the lens structure having a first and second circular tip segment each circular tip segment with a first contact angle, and a first and second circular base segment each circular base segment with a top and bottom contact angle, the contact angles of the circular base segments being greater than the contact angle of the circular tip segments; and

wherein the first and second circular tip segments satisfies the following equation:

y 1 =a 1 +√{square root over (( r 1 2 −x 2 ))}

y 2 =a 2 +√{square root over (( r 4 2 −x 2 ))}

wherein x is a value in a direction of the light input surface, y 1 is a value in a light propagation direction, r 1 is a radius of the first circular tip segment, a 1 is a y-coordinate of a center of the first circular tip segment, y 2 is a value in the light propagation direction, r 2 is a radius of the second circular tip segment, a 2 is a y-coordinate of a center of the second circular tip segment, and the first and second circular base segments satisfies the following equations:

y 3 =b 3 +√{square root over (( r 3 2 −( x+a 3 ) 2 ))}

y 4 =b 4 +√{square root over (( r 4 2 −( x−a 4 ) 2 ))}

wherein y 3 is a value in the light propagation direction, r 3 is a radius of the first circular base segment, a 3 and b 3 are x- and y-coordinates respectively of a center of the first circular base segment, y 4 is a value in the light propagation direction, r 4 is a radius of the second circular base segment, and a 4 and b 4 are x- and y-coordinates respectively of a center of the second circular base segment, and each of the composite lens structures is randomly disposed along the light input surface.

10. The planar light guide film of claim 9 wherein the circular tip segment of the composite lens structure has a contact angle A 1 greater than 0.1 degrees and less than or equal to 85 degrees.

11. The planar light guide film of claim 9 wherein the second circular tip segment of the composite lens structure has a contact angle A 2 greater than 0.1 degrees and less than or equal to 85 degrees.

12. The planar light guide film of claim 9 wherein contact angles A 1 and A 2 of the of the composite lens structure are not equal.

13. The planar light guide film as in any one of claims 10 - 12 wherein the composite lens structure further comprises contact angles A 31 , A 41 , A 32 , and A 42 wherein A 31 ≠A 41 , A 32 ≠A 42 and A 1 ≦A 31 , A 31 ≦A 32 , A 2 ≦A 41 , A 41 ≦A 42 .

14. A planar light guide film for a backlight unit having at least one point light source, the light guide film comprising:

a light input surface for receiving light from the point light source;

a light redirecting surface for redirecting light received from the light input surface;

a light output surface for outputting at least the light redirected from the light redirecting surface;

wherein the light input surface further comprises a serrated lens structure that is provided only where the point light source is incident on the light input surface, the lens structure having a first and second circular tip segment each circular tip segment with a first contact angle, and a first and second circular base segment each circular base segment with a top and bottom contact angle, the contact angles of the circular base segments being greater than the contact angle of the circular tip segments; and

wherein the first and second circular tip segments satisfies the following equations:

y 1 =a 1 +√{square root over (( r 1 2 − 2 ))}

y 2 =a 2 +√{square root over (( r 2 2 −x 2 ))}

wherein x is a value in a direction of the light input surface, y 1 is a value in a light propagation direction, r 1 is a radius of the first circular tip segment, a 1 is a y-coordinate of a center of the first circular tip segment, y 2 is a value in the light propagation direction, r 2 is a radius of the second circular tip segment, a 2 is a y-coordinate of a center of the second circular tip segment, and the first and second circular base segments satisfies the following equations:

y 3 =b 3 +√{square root over (( r 3 2 −( x+a 3 ) 2 ))}

y 4 =b 4 +√{square root over (( r 4 2 −( x−a 4 ) 2 ))}

wherein y 3 is a value in the light propagation direction, r 3 is a radius of the first circular base gment, a 3 and b 3 are x- and y-coordinates respectively of a center of the first circular base segment, y 4 is a value in the light propagation direction, r 4 is a radius of the second circular base segment, and a 4 and b 4 are x- and y-coordinates respectively of a center of the second circular base segment, and each of the composite lens structures is randomly disposed only where the point light source is incident on the light input surface.