Low power consumption transflective liquid crystal displays
View Patent ↗Techniques are provided to drive a normally white or mixed mode LCD with low voltages and low power consumption. A sub-pixel in the LCD may comprise a reflective part and a transmissive part. The cell gap for a liquid crystal layer in the sub-pixel may provide at least a half-wave phase retardation. A driving voltage range with a maximum voltage at a low value may be used to drive the reflective part and the transmissive part of the sub-pixel to various levels of brightness.
1. A transflective liquid crystal display comprising a plurality of sub-pixels, each sub-pixel comprising:
a reflective part, comprising:
first portions of a first retardation film, a first polarizing layer, a bottom substrate layer, a top substrate layer, and a common electrode portion, wherein the top substrate layer is opposite to the bottom substrate layer;
a reflective layer adjacent to the bottom substrate layer;
a reflective-part liquid crystal layer portion of a liquid crystal layer between the bottom substrate layer and the top substrate layer;
a transmissive part, comprising:
second portions of the first retardation film, the first polarizing layer, the bottom substrate layer, the top substrate layer, and the common electrode portion;
a transmissive-part liquid crystal layer portion of the liquid crystal layer between the bottom substrate layer and the top substrate layer;
wherein a transmissive-part cell gap of the transmissive-part liquid crystal layer portion is configured as a plate of at least a half-wavelength or more in a voltage-off state of the transmissive-part liquid crystal layer portion;
wherein said each sub-pixel is normally-white at a voltage-off state.
2. The transflective liquid crystal display according to claim 1 , wherein the transmissive-part liquid crystal layer portion is configured to be driven to a transmissive display state by 1.0 volt at maximum to 2.7 volts at maximum.
3. The transflective liquid crystal display according to claim 1 , wherein the reflective-part liquid crystal layer portion is configured to be driven to a reflective display state by 1.0 volt at maximum to 2.7 volts at maximum.
4. The transflective liquid crystal display according to claim 1 , wherein the reflective-part liquid crystal layer portion comprises liquid crystal molecules that are homogeneously aligned along a second direction in the voltage-off state of the reflective-part liquid crystal layer portion.
5. The transflective liquid crystal display according to claim 1 , wherein the transmissive part further comprises a portion of a second retardation film.
6. The transflective liquid crystal display according to claim 1 , wherein the reflective part further comprises an over-coating layer adjacent to one of the bottom substrate layer and the top substrate layer, wherein the over-coating layer is between the bottom substrate layer and the top substrate layer, and wherein a reflective-part cell gap of the reflective-part liquid crystal layer portion is a plate of a half-wavelength or more in a voltage-off state of the reflective-part liquid crystal layer portion.
7. The transflective liquid crystal display according to claim 1 , wherein a reflective-part cell gap of the reflective-part liquid crystal layer portion is equal to the transmissive-part cell gap.
8. The transflective liquid crystal display according to claim 1 , wherein the reflective-part liquid crystal layer portion is configured to be driven to a reflective display state by a first voltage and wherein the transmissive-part liquid crystal layer portion is configured to be driven to a transmissive display state by the first voltage.
9. The transflective liquid crystal display according to claim 1 , wherein the reflective-part liquid crystal layer portion is configured to be driven to a reflective display state by a first voltage and wherein the transmissive-part liquid crystal layer portion is configured to be driven to a transmissive display state by a second, different, voltage.
10. The transflective liquid crystal display according to claim 1 , wherein the sub-pixel further comprises at least one color filter that covers at least a portion of the transmissive part sub-pixel.
11. The transflective liquid crystal display according to claim 10 , wherein the sub-pixel is a part of a composite pixel, and wherein the composite pixel comprises another sub-pixel that is configured to express a different color than the sub-pixel.
12. The transflective liquid crystal display according to claim 1 , wherein a normal direction of the bottom substrate layer is parallel to the first direction or to the second direction.
13. The transflective liquid crystal display according to claim 1 , wherein the sub-pixel further comprises one or more orientation films and wherein one or more of the first direction and the second direction are along a rubbing direction of at least one of the one or more orientation films.
14. The transflective liquid crystal display according to claim 1 , wherein optical birefringence of the liquid crystal layer is electrically controllable.
15. The transflective liquid crystal display according to claim 1 , wherein the first retardation film has an azimuth angle of θ h , wherein the transmit-part liquid crystal layer portion has an azimuth angle of θ q , and wherein the azimuth angles satisfy one of: 60≦4θ h −2θ q ≦120, or −120≦4θ h −2θ q ≦−60.
16. The transflective liquid crystal display according to claim 1 , wherein the reflective part comprises a reflective electrode, wherein the transmissive part comprises a transmissive electrode, and wherein the sub-pixel comprises a switching element that is configured to control whether the reflective electrode is electrically connected to the transmissive electrode.
17. The transflective liquid crystal display according to claim 1 , wherein the reflective part comprises a reflective electrode, wherein the transmissive part comprises a transmissive electrode, wherein the common electrode is located on a first side of the liquid crystal layer, and wherein the transmissive electrode and the reflective electrode are located on a second opposing side of the liquid crystal layer.
18. The transflective liquid crystal display according to claim 1 , wherein the sub-pixel further comprises a light recycling film between the bottom substrate layer and a backlight unit that redirects backlight from the reflective part to the transmissive part.
19. The transflective liquid crystal display according to claim 18 , wherein the light recycling film is configured to turn incident light of any polarized state into redirected light with a particular polarization state.
20. The transflective liquid crystal display according to claim 1 , wherein the transmissive part liquid crystal layer portion comprises homogeneously aligned liquid crystal molecules.
21. A computing device, comprising:
one or more processors;
a transflective liquid crystal display comprising a plurality of sub-pixels, each sub-pixel comprising:
a reflective part, comprising:
first portions of a first retardation film, a first polarizing layer, a bottom substrate layer, a top substrate layer, and a common electrode portion, wherein the top substrate layer is opposite to the bottom substrate layer;
a reflective layer adjacent to the bottom substrate layer;
a reflective-part liquid crystal layer portion of a liquid crystal layer between the bottom substrate layer and the top substrate layer;
a transmissive part, comprising:
second portions of the first retardation film, the first polarizing layer, the bottom substrate layer, the top substrate layer, and the common electrode portion;
a transmissive-part liquid crystal layer portion of the liquid crystal layer between the bottom substrate layer and the top substrate layer;
wherein a transmissive-part cell gap of the transmissive-part liquid crystal layer portion is configured as a plate of at least a half-wavelength or more in a voltage-off state of the transmissive-part liquid crystal layer portion;
wherein said each sub-pixel is normally-white at a voltage-off state.
22. The computer device according to claim 21 , wherein the transmissive-part liquid crystal layer portion is configured to be driven to a transmissive display state by 1.0 volt at maximum to 2.7 volts at maximum.
23. The computer device according to claim 21 , wherein the reflective-part liquid crystal layer portion is configured to be driven to a reflective display state by 1.0 volt at maximum to 2.7 volts at maximum.
24. The computer device according to claim 21 , wherein the reflective-part liquid crystal layer portion comprises liquid crystal molecules that are homogeneously aligned along a second direction in the voltage-off state of the reflective-part liquid crystal layer portion.
25. The computer device according to claim 21 , wherein the transmissive part further comprises a portion of a second retardation film.
26. The computer device according to claim 21 , wherein the reflective part further comprises an over-coating layer adjacent to one of the bottom substrate layer and the top substrate layer, wherein the over-coating layer is between the bottom substrate layer and the top substrate layer, and wherein a reflective-part cell gap of the reflective-part liquid crystal layer portion is a plate of a half-wavelength or more in a voltage-off state of the reflective-part liquid crystal layer portion.
27. The computer device according to claim 21 , wherein a reflective-part cell gap of the reflective-part liquid crystal layer portion is equal to the transmissive-part cell gap.
28. The computer device according to claim 21 , wherein the sub-pixel further comprises a light recycling film between the bottom substrate layer and a backlight unit that redirects backlight from the reflective part to the transmissive part.
29. A method of fabricating a transflective liquid crystal display, comprising:
providing a plurality of pixels, a pixel comprising:
a reflective part, comprising:
first portions of a first retardation film, a first polarizing layer, a bottom substrate layer, a top substrate layer, and a common electrode portion, wherein the top substrate layer is opposite to the bottom substrate layer;
a reflective layer adjacent to the bottom substrate layer;
a reflective-part liquid crystal layer portion of a liquid crystal layer between the bottom substrate layer and the top substrate layer;
a transmissive part, comprising:
second portions of the first retardation film, the first polarizing layer, the bottom substrate layer, the top substrate layer, and the common electrode portion;
a transmissive-part liquid crystal layer portion of the liquid crystal layer between the bottom substrate layer and the top substrate layer;
wherein a transmissive-part cell gap of the transmissive-part liquid crystal layer portion is configured as a plate of at least a half-wavelength or more in a voltage-off state of the transmissive-part liquid crystal layer portion;
wherein said each sub-pixel is normally-white at a voltage-off state.
30. The method according to claim 29 , wherein the transmissive-part liquid crystal layer portion is configured to be driven to a transmissive display state by 1.0 volt at maximum to 2.7 volts at maximum.
31. The method according to claim 29 , wherein the reflective-part liquid crystal layer portion is configured to be driven to a reflective display state by 1.0 volt at maximum to 2.7 volts at maximum.