Differential Ultraviolet curing using external optical elements

1. An ink curing system, comprising:

at least one array of solid state light emitters in a package having a window;

a patterned external optical element arranged adjacent to the window, the patterned external optical element forming an optical pattern on a print substrate when illuminated by light from the solid state light emitters;

said optical pattern comprising a first gradient in a process direction, wherein the process direction is parallel to a direction in which the print substrate moves relative to the at least one array of solid state light emitters, and a second gradient perpendicular to the process direction;

a printer arranged to deposit ink onto the print substrate, the ink being curable by optically patterned light, the array of solid state light emitters arranged adjacent to the print substrate such that the optically patterned light from the array contacts the ink, the patterned external optical element arranged between the at least one array of solid state light emitters and the print substrate to allow for variability of curing; and the patterned external optical element comprising a patterned external optical element directly adjacent to the window, said patterned external optical element comprising a patterned film on the window.

2. The ink curing system of claim 1 , wherein the patterned external optical element comprises an offset patterned external optical element, wherein a gap exists between the offset patterned external optical element and the window.

3. The ink curing system of claim 1 , wherein the patterned film comprises a dither pattern randomly generated using a noise function.

4. The ink curing system of claim 1 , wherein the patterned film comprises a first patterned surface comprising a first pattern and a second patterned surface comprising a second pattern, wherein the first pattern is different from the second pattern.

5. The ink curing system of claim 1 , wherein the patterned external optical element comprises a first portion with the patterned film and a second portion with a clear unpatterned surface.

6. An ink curing system, comprising:

at least one array of solid state light emitters in a package having a window;

a patterned external optical element arranged adjacent to the window, the patterned external optical element forming an optical pattern on a print substrate when illuminated by light from the solid state light emitters;

said optical pattern comprising a first gradient in a process direction, wherein the process direction is parallel to a direction in which the print substrate moves relative to the at least one array of solid state light emitters, and a second gradient perpendicular to the process direction;

a printer arranged to deposit ink onto the print substrate, the ink being curable by optically patterned light, the array of solid state light emitters arranged adjacent to the print substrate such that the optically patterned light from the array contacts the ink, the patterned external optical element arranged between the at least one array of solid state light emitters and the print substrate to allow for variability of curing; and

the patterned external optical element comprising a patterned external optical element directly adjacent to the window, said patterned external optical element comprising a patterned coating on the window.

7. The ink curing system of claim 6 , wherein the patterned external optical element comprises an offset patterned external optical element, wherein a gap exists between the offset patterned external optical element and the window.

8. The ink curing system of claim 6 , wherein the patterned coating comprises a dither pattern randomly generated using a noise function.

9. The ink curing system of claim 6 , wherein the patterned coating comprises a first patterned coating comprising a first pattern and a second patterned coating comprising a second pattern, wherein the first pattern is different from the second pattern.

10. The ink curing system of claim 6 , wherein the patterned external optical element comprises a first portion with the patterned coating and a second portion with a clear unpatterned coating.

11. An ink curing system, comprising: at least one array of solid state light emitters in a package having a window; a patterned external optical element arranged adjacent to the window, the patterned external optical element forming an optical pattern on a print substrate when illuminated by light from the solid state light emitters; said optical pattern comprising a first gradient in a process direction, wherein the process direction is parallel to a direction in which the print substrate moves relative to the at least one array of solid state light emitters, and a second gradient perpendicular to the process direction; a printer arranged to deposit ink onto the print substrate, the ink being curable by optically patterned light, the array of solid state light emitters arranged adjacent to the print substrate such that the optically patterned light from the array contacts the ink, the patterned external optical element arranged between the at least one array of solid state light emitters and the print substrate to allow for variability of curing; and the patterned external optical element comprising of a patterned external optical element directly adjacent to the window, said patterned external optical element comprising a patterned surface on the window.

12. The ink curing system of claim 11 , wherein the patterned external optical element comprises an offset patterned external optical element, wherein a gap exists between the offset patterned external optical element and the window.

13. The ink curing system of claim 11 , wherein the patterned surface comprises a dither pattern randomly generated using a noise function.

14. The ink curing system of claim 11 , wherein the patterned surface comprises a first patterned surface comprising a first pattern and a second patterned surface comprising a second pattern, wherein the first pattern is different from the second pattern.

15. The ink curing system of claim 11 , wherein the patterned external optical element comprises a first portion with the patterned surface and a second portion with a clear unpatterned surface.