Method and apparatus using a combination of quantum dot-containing films with optical filter films for signage and illumination applications
An illuminated sign comprises a source of blue light; a quantum dot-containing film that produces green light when illuminated by the source of blue light; and, a patterned blue cutoff filter in optical communication with the quantum dot-containing film configured to allow a mixture of excess blue light from the source of blue light and green light from the quantum dot-containing film to pass through the pattern. The mixture of blue light and green light produces a pseudo white light. The illuminated sign may thus comprise pseudo white letters and/or graphics on a luminous green background.
1. An illuminated sign comprising:
a source of blue light;
a quantum dot-containing film that, when illuminated by the source of blue light, produces solely green light and passes a portion of the blue light therethrough; and
a blue cutoff filter having one or more openings for the transmission of light therethrough, the blue cutoff filter in optical communication with the quantum dot-containing film and configured to allow:
a mixture of excess blue light from the source of blue light and green light from the quantum dot-containing film to pass through the one or more openings of the blue cutoff filter; and
green light to pass through portions of the blue cutoff filter that are not the one or more openings.
2. The illuminated sign recited in claim 1 wherein the source of blue light is a plurality of blue-emitting light emitting diodes [LEDs].
3. The illuminated sign recited in claim 1 wherein the quantum dot-containing film comprises heavy metal-free quantum dots.
4. The illuminated sign recited in claim 1 wherein the one or more openings in the blue cutoff filter comprises one or more selectively deposited absorptive dyes on a transparent film.
5. The illuminated sign recited in claim 1 , further comprising a yellow filter disposed between the quantum dot-containing film and the blue cutoff filter.
6. The illuminated sign recited in claim 5 , further comprising a neutral-density filter disposed on portions of the blue cutoff filter that do not comprise the openings.
7. An illuminated sign comprising:
a source of blue light;
a quantum dot-containing film that produces green light and red light when illuminated by the source of blue light; and
a blue cutoff filter having one or more openings for the transmission of light therethrough, the blue cutoff filter in optical communication with the quantum dot-containing film and configured to allow:
a mixture of excess blue light from the source of blue light and green light together with red light from the quantum dot-containing film to pass through the one or more openings of the blue cutoff filter; and
green light and red light to pass through portions of the blue cutoff filter that are not the one or more openings.
8. The illuminated sign recited in claim 7 wherein the red light in the quantum dot-containing film is produced by red-emitting quantum dots in the film.
9. The illuminated sign recited in claim 7 wherein the red light in the quantum dot-containing film is produced by a red-emitting phosphor.
10. The illuminated sign recited in claim 9 wherein the red-emitting phosphor is K 2 SiF 6 :Mn 4+ (KSF).
11. The illuminated sign recited in claim 7 wherein the source of blue light is a plurality of blue-emitting light emitting diodes [LEDs].
12. The illuminated sign recited in claim 7 wherein the quantum dot-containing film comprises heavy metal-free quantum dots.
13. The illuminated sign recited in claim 7 wherein the one or more openings in the blue cutoff filter comprises one or more selectively deposited absorptive dyes on a transparent film.
14. The illuminated sign recited in claim 7 wherein the mixture of excess blue light from the source of blue light and green light together with red light from the quantum dot-containing film is a pseudo white light.
15. The illuminated sign recited in claim 7 , further comprising a yellow filter disposed between the quantum dot-containing film and the blue cutoff filter.
16. The illuminated sign recited in claim 15 , further comprising a neutral-density filter disposed on portions of the blue cutoff filter that do not comprise the openings.