COLOR TUNING FOR ELECTROPHORETIC DISPLAY DEVICE
The present invention is directed to color tuning methods for electrophoretic display devices. For example, a color tuning agent may be added to a composition for forming a display cell structure or a primer layer. Alternatively, a separate color tuning layer may be added to a display device. Further, a color tuning agent may be added to an electrophoretic display fluid. The color tuning methods are useful for adjusting the color temperature of a display device.
1 . A method for adjusting color temperature of a display device, comprising:
(i) forming a color tuning layer in a display device from a color tuning composition comprising a leuco dye, and
(ii) irradiating the color tuning layer to cause the leuco dye to change from colorless to a colored form,
wherein the change of a* or b* in the L*,a*,b* color space system of the colors displayed by the display device, after step (ii), is less than 5.
2 . The method of claim 1 , further comprising adding a color protection layer to prevent active radiation absorption by the leuco dye to further change its color.
3 . The method of claim 1 , wherein the leuco dye is selected from the group consisting of triarylmethane compounds, bisphenylmethane compounds, xanthene compounds, and thiazine compounds.
4 . The method of claim 1 , wherein the leuco dye is crystal violet lactone, malachite green lactone, leuco base fuchsin, or p-nitrobenzoyl leuco methylene blue.
5 . The method of claim 1 , wherein the color tuning composition further comprises a photo oxidative agent or photo acid generator.
6 . The method of claim 1 , wherein the color tuning composition further comprises a dispersant.
7 . The method of claim 1 , wherein the leuco dye has a concentration of less than 5% by weight in the color tuning composition.
8 . The method of claim 1 , wherein the leuco dye is in a sub-micron size when in a dispersed state.
9 . The method of claim 1 , wherein the color tuning layer is a display cell structure.
10 . The method of claim 1 , wherein the color tuning layer is a primer layer.
11 . The method of claim 1 , wherein the color tuning layer is an adhesive layer, antiglare coating or hard coating.
12 . The method of claim 1 , wherein the color tuning layer is a separate layer formed on a substrate layer.
13 . The method of claim 1 , wherein the color tuning layer is a plastic substrate.
14 . The method of claim 1 , wherein the color tuning composition further comprises a polymer carrier.