Contrast compensation of microdisplay panels including a high order waveplate
View Patent ↗A contrast compensator for improving the panel contrast of liquid crystal (LC) microdisplays having a high-order waveplate configured as an O-plate and supporting a thin film transistor layer is provided. The contrast compensator includes a counter high-order waveplate configured as an O-plate, which has a birefringence opposite in sign to a birefringence of the thin film transistor substrate.
1. A liquid crystal microdisplay comprising:
a liquid crystal microdisplay panel including a first substrate, a second substrate, and a liquid crystal layer disposed between the first and second substrates, the first substrate including a first multiple-order waveplate configured as an O-plate and supporting a thin film transistor layer; and,
a retarder compensator for compensating for spectral and angular linear retardance dispersions of the first substrate, the retarder compensator including a second multiple-order waveplate configured as an O-plate, the second multiple-order waveplate having a birefringence opposite in sign to a birefringence of the first multiple-order waveplate.
2. A liquid crystal microdisplay according to claim 1 , wherein a thickness and C-axis tilt angle of the second multiple-order waveplate are selected such that spectral and angular linear retardance dispersions of the second multiple-order waveplate substantially counteract the spectral and angular dispersions of the first multiple-order waveplate.
3. A liquid crystal microdisplay according to claim 2 , wherein the C-axis of the first multiple-order waveplate is oriented in a same tilt plane as a C-axis of the second multiple-order waveplate.
4. A liquid crystal microdisplay according to claim 3 , wherein the liquid crystal microdisplay panel is disposed between a polarizer and an analyzer, and wherein the tilt plane is substantially parallel to one of a transmission axis of the polarizer and a transmission axis of the analyzer.
5. A liquid crystal microdisplay according to claim 1 , wherein a C-axis of the first multiple-order waveplate is oriented in a same tilt plane as a C-axis of the second multiple-order waveplate.
6. A liquid crystal microdisplay according to claim 3 , wherein the first multiple-order waveplate comprises a high-order sapphire waveplate.
7. A liquid crystal microdisplay according to claims 6 , wherein the second multiple-order waveplate comprises a high-order quartz waveplate.
8. A liquid crystal microdisplay according to claim 1 , wherein the first multiple-order waveplate comprises a high-order sapphire waveplate.
9. A liquid crystal microdisplay according to claim 8 , wherein the second multiple-order waveplate comprises a high-order quartz waveplate.
10. A liquid crystal microdisplay according to claim 1 , wherein the retarder compensator comprises a trim retarder coupled to the second multiple-order waveplate.
11. A liquid crystal microdisplay according to claim 10 , wherein the trim retarder comprises at least one of a thin film birefringent layer and a thin-film form-birefringent layer deposited on the second multiple-order waveplate.
12. A liquid crystal microdisplay according to claim 11 , wherein the thin film birefringent layer and the thin-film form-birefringent layer are configured as one of an A-plate, a C-plate, and an O-plate.
13. A liquid crystal microdisplay according to claim 11 , wherein the thin film birefringent layer and the thin-film form-birefringent layer are configured as single layer A-plates.
14. A liquid crystal microdisplay according to claim 7 , wherein the retarder compensator comprises a trim retarder coupled to the second multiple-order waveplate.
15. A liquid crystal microdisplay according to claim 14 , wherein the trim retarder comprises at least one of a thin film birefringent layer and a thin-film form-birefringent layer deposited on the second multiple-order waveplate.
16. A liquid crystal microdisplay according to claim 15 , wherein the thin film birefringent layer and the thin-film form-birefringent layer are configured as one of an A-plate, a C-plate, and an O-plate.
17. A liquid crystal microdisplay according to claim 15 , wherein the thin film birefringent layer and the thin-film form-birefringent layer are configured as single layer A-plates.
18. A liquid crystal microdisplay according to claim 7 , wherein the first multiple-order waveplate is at least 200 microns thick, and the second multiple-order waveplate is at least 200 microns thick.
19. A liquid crystal microdisplay according to claim 1 , wherein the first multiple-order waveplate is at least 200 microns thick, and the second multiple-order waveplate is at least 200 microns thick.