Method and device for compensating for color shift as a function of angle of view
View Patent ↗In one embodiment of the invention, a display is provided and includes a plurality of interferometric display elements. The display further includes at least one diffuser. Optical properties of the diffuser are selected to reduce color shift of the display when viewed from at least one angle.
1. A display comprising:
at least one interferometric modulator configured to reflect incident light, the at least one interferometric modulator having an optical response that depends at least in part on angle of view and wavelength of the incident light; and
a diffuser positioned in an optical path to the at least one interferometric modulator, the diffuser having an optical response that is substantially matched to the optical response of the interferometric modulator to maintain substantially the same composition of color at different angles of view.
2. The display of claim 1 , wherein the optical response of the diffuser depends at least in part on angle of view.
3. The display of claim 1 , wherein the diffuser comprises a non-lambertian diffuser.
4. The display of claim 1 , wherein the optical response of the diffuser falls off with angle of view.
5. The display of claim 1 , wherein the diffuser comprises a high gain diffuser.
6. The display of claim 5 , wherein the high gain diffuser has a full width at half maximum of between about 10° and 30°.
7. The display of claim 1 , wherein the diffuser comprises a low gain diffuser.
8. The display of claim 7 , wherein the low gain diffuser has a full width at half maximum of between about 60° and 100°.
9. The display of claim 1 , wherein the diffuser and interferometric modulator are configured to produce a combined optical response that reduces angular color shift to less than about 10 to 20 nanometers for an angle-of-view change of about 50 degrees.
10. A display comprising:
at least one interferometric modulator having a spectral responsivity that varies with angle of view, θ, such that color varies with angle of view; and
a non-lambertian diffuser positioned in an optical path to the at least one interferometric modulator, the non-lambertian diffuser having an optical response that varies with angle of view, said diffuser substantially reducing variation of color with angle of view.
11. The display of claim 10 , wherein the spectral responsivity of the interferometric modulator for a normal angle of view of 0° includes a spectral line that is centered about a non-visible wavelength and that extends into visible wavelengths.
12. The display of claim 11 , wherein the spectral line is centered in the infrared.
13. The display of claim 11 , wherein the spectral line is centered at a wavelength between about 700 to about 1000 nanometers.
14. The display of claim 11 , wherein said interferometric modulator together with said diffuser have a spectral responsivity for said normal angle of view having a spectral line centered in the visible wavelength range.
15. The display of claim 10 , wherein the diffuser comprises a high gain diffuser.
16. The display of claim 10 , wherein the diffuser comprises a low gain diffuser.
17. The display of claim 10 , wherein the optical response of the diffuser has a peak value at a non-zero angle of view for a normal angle of incidence.
18. The display of claim 17 , wherein the optical response of the diffuser has a peak value at an angle of view greater than about 5 degrees for light incident on the diffuser at an angle of incidence, θ i , of about 0°.
19. The display of claim 10 , wherein the optical response of the diffuser is dependent on angle of incidence of light on the diffuser.
20. The display of claim 19 , wherein the optical response of the diffuser is peaked at an angle of view that is unequal to the angle of incidence of the light on the diffuser.
21. The display of claim 20 , wherein said peaked angle of view is different for different angles of incidence.
22. The display of claim 10 , wherein to optical response of to diffuser further depends onto wavelength of light.