In-plane switched active retarder for stereoscopic display systems
View Patent ↗Polarization modulation with in-plane switching of liquid crystals (LCs) may be used in active retarder stereoscopic display systems where viewers wear passive eyewear to see isolated left and right eye images. Embodiments of the present disclosure may include nematic LC or fast switching ferroelectric liquid crystal (FLC), depending on the desired performance.
1. A method of providing stereoscopic images, the method comprising:
directing polarized light from a display along a light path towards an in-plane liquid crystal modulator, wherein the in-plane liquid crystal modulator comprises at least one liquid crystal cell having substantially no out-of-plane retardance;
receiving the polarized light at the at least one liquid crystal cell;
switching the at least one liquid crystal cell between first and second in-plane orientations sequentially to provide modulated light having first and second states of polarization, respectively; and
transmitting the modulated light having the first state of polarization at a left analyzer of eyewear and transmitting the modulated light having the second state of polarization at a right analyzer of the eyewear;
wherein the modulated light having the first state of polarization is operable to form a left image and the modulated light having the second state of polarization is operable to form a right image; and
wherein the left analyzer comprises a left inverse retarder and a left polarizer layer optically following the left inverse retarder, and the right analyzer comprises a right inverse retarder and a right polarizer layer optically following the right inverse retarder, wherein the left and right inverse retarders each comprise a retardance substantially inverse to an in-plane retardance of the at least one liquid crystal cell and have substantially no out-of-plane retardance.
2. The method of claim 1 , wherein directing polarized light comprises outputting the left image and the right image sequentially from the display and switching the at least one liquid crystal cell synchronously.
3. A stereoscopic system, comprising:
a display operable to provide polarized light along a light path;
an in-plane liquid crystal modulator disposed in the light path, wherein the in-plane liquid crystal modulator comprises at least one liquid crystal cell having an in-plane retardance and substantially no out-of-plane retardance, the at least one liquid crystal cell being operable to receive the polarized light and to switch between first and second in-plane orientations sequentially to provide modulated light having first and second states of polarization, respectively; and
eyewear comprising a left analyzer and a right analyzer, wherein the left analyzer comprises a left inverse retarder and a left polarizer layer optically following the left inverse retarder, and the right analyzer comprises a right inverse retarder and a right polarizer layer optically following the right inverse retarder, wherein the left and right inverse retarders each comprise a retardance substantially inverse to the in-plane retardance of the at least one liquid crystal cell and have substantially no out-of-plane retardance;
wherein, when the at least one liquid crystal cell is in the first in-plane orientation, the left analyzer is operable to receive the modulated light having the first state of polarization and to transmit light comprising a left image; and
wherein, when the at least one liquid crystal cell is in the second in-plane orientation, the right analyzer is operable to receive the modulated light having the second state of polarization and to transmit light comprising a right image.
4. The stereoscopic system of claim 3 , wherein the left and right inverse retarders comprise first and second optical axes, respectively, the first and second optical axes being substantially orthogonal to each other.
5. The stereoscopic system of claim 3 , wherein the polarized light comprises an input polarization direction, and the left and right polarizers of the eyewear are substantially oriented orthogonally to the input polarization direction.
6. The stereoscopic system of claim 3 , wherein the at least one liquid crystal cell has an in-plane retardance of a half wave, and the stereoscopic display system further comprises a passive quarter wave retarder disposed in the light path, the passive quarter wave retarder optically following or preceding the in-plane liquid crystal modulator.
7. The stereoscopic display system of claim 3 , wherein the stereoscopic display system further comprises a passive retarder disposed in the light path.
8. The stereoscopic display system of claim 7 , wherein the passive retarder comprises a stack of passive retarder films.
9. The stereoscopic display system of claim 7 , wherein the passive retarder is disposed in the light path between the display and the in-plane liquid crystal modulator.
10. The stereoscopic display system of claim 9 , wherein the stereoscopic display system further comprises a second passive retarder disposed in the light path, the second passive retarder optically following the in-plane liquid crystal modulator.
11. The stereoscopic display system of claim 7 , wherein the passive retarder optically follows the in-plane liquid crystal modulator.
12. The stereoscopic display system of claim 3 , wherein the display comprises an output polarizer.
13. The stereoscopic display system of claim 3 , wherein the at least one liquid crystal cell has an in-plane retardance of a quarter wave.
14. The stereoscopic display system of claim 13 , wherein the first and second in-plane orientations are substantially aligned at 90° relative to each other.
15. The stereoscopic display system of claim 3 , wherein the at least one liquid crystal cell has an in-plane retardance of a half wave, and the stereoscopic display system further comprises a passive quarter wave retarder disposed in the light path, the passive quarter wave retarder optically following or preceding the in-plane liquid crystal modulator.
16. The stereoscopic display system of claim 15 , wherein the first and second in-plane orientations are substantially aligned at 45° relative to each other.
17. The stereoscopic display system of claim 3 , wherein the first and second in-plane orientations are symmetrically aligned relative to a polarization direction of the polarized light.
18. The stereoscopic display system of claim 3 , wherein the in-plane liquid crystal modulator comprises segments operable to be addressed separately.
19. The stereoscopic display system of claim 3 , wherein the at least one liquid crystal cell comprises ferroelectric liquid crystals.
20. The stereoscopic display system of claim 3 , wherein the at least one liquid crystal cell comprises nematic liquid crystals.