Transflective liquid crystal display
A single-gap transflective LCD panel having a voltage divider in each sub-pixel for reducing the voltage potential across part of the liquid crystal layer in the sub-pixel. In a normally-black LCD panel, the voltage divider is used to reduce the voltage potential across the liquid crystal layer in the reflection area. In a normally-white LCD panel, the voltage divider is used to reduce the voltage potential across the liquid crystal layer in the transmission area. The voltage divider comprises two poly-silicon resistor segments connected in series between a data line and a common line via one or more switching elements controlled by a gate line signal. With poly-silicon resistor segments being disposed in the reflection area below the reflective electrode, the optical quality of the upper electrode and the transmissive electrode is not affected by the voltage divider.
1. A method for improving optical characteristics of a single-gap transflective liquid crystal display panel having a plurality of pixels, at least some of the pixels having a transmission area and a reflection area, wherein the transmission area comprises a transmissive electrode and the reflection area comprises a reflective electrode, said method comprising the steps of:
providing a first voltage level to the transmissive electrode to achieve a transmittance in the transmission area;
providing a second voltage level to the reflective electrode to achieve a reflectance in the reflection area, the second voltage level having a voltage ratio in relation to the first voltage level; and
adjusting the voltage ratio so that a ratio of the reflectance to the transmittance is achievable within a predetermined range, wherein the step of adjusting the voltage ratio comprising disposing a voltage divider in each of said pixels for adjusting the voltage ratio.
2. The method of claim 1 , wherein the liquid crystal display panel is a normally-black display panel, and wherein the voltage divider is operatively connected to the reflective electrode for adjusting the second voltage level so that the voltage ratio is smaller than 1.
3. The method of claim 1 , wherein the liquid crystal display panel is a normally-white display panel, and wherein the voltage divider is operatively connected to the transmissive electrode for adjusting the first voltage level so that the voltage ratio is greater than 1.
4. The method of claim 1 , wherein the voltage divider is made of poly-silicon disposed in the reflection area.
5. A single-gap transflective liquid crystal display panel having a plurality of pixels, at least some of the pixels having a transmission area and a reflection area, said display panel comprising:
a transmissive electrode disposed in the transmission area in each of said pixels, the transmissive electrode operatively connected to a first voltage level to achieve a transmittance in the transmission area;
a reflective electrode disposed in the reflection area in each of said pixels, the reflective electrode operatively connected to a second voltage level to achieve a reflectance in the reflection area, the second voltage level having a voltage ratio in relation to the first voltage level; and
a voltage divider disposed in each of said pixels for adjusting the voltage ratio such that a ratio of the reflectance to the transmittance is achievable within a predetermined range.
6. The display panel of claim 5 , wherein the liquid crystal display panel is a normally-black display panel, and wherein the voltage divider is operatively connected to the reflective electrode for adjusting the second voltage level so that the voltage ratio is smaller than 1.
7. The display panel of claim 6 , wherein the voltage divider comprises at least two resistor segments made of poly-silicon, and the reflective electrode is operatively connected to the voltage divider between the resistor segments, said display panel further comprising
a storage capacitor in each of said pixels, operatively connected to the voltage divider between the resistor segments.
8. The display panel of claim 7 , further comprising
a further storage capacitor operatively connected to the transmissive electrode.
9. The display panel of claim 7 , wherein each of said pixels is associated with a data line and a gate line, and wherein the resistor segments comprise a first resistor segment and a second resistor segment, said display panel further comprising:
a first switching element controllable by the gate line, the first switching element operatively connected between the data line and the transmissive electrode;
a second switching element controllable by the gate line, the second switching element operatively connected between the data line and first resistor segment; and
a third switching element controllable by the gate line, the third switching element operatively connected between the second resistor segment and a common line of the display panel.
10. The display panel of claim 7 , further comprising
a further reflective electrode in each of said pixels electrically separated from the reflective electrode, wherein the further reflective electrode is operatively connected to the transmissive electrode.
11. The display panel of claim 5 , wherein the liquid crystal display panel is a normally-white display panel, and wherein the voltage divider is operatively connected to the transmissive electrode for adjusting the first voltage level so that the voltage ratio is greater than 1.
12. The display panel of claim 11 , wherein the voltage divider comprises at least two resistor segments made of poly-silicon, and the transmissive electrode is operatively connected to the voltage divider between the resistor segments, said display panel further comprising
a storage capacitor in each of said pixels, operatively connected to the voltage divider between the resistor segments.
13. The display panel of claim 12 , further comprising
a further storage capacitor operatively connected to the reflective electrode.
14. The display panel of claim 12 , wherein each of said pixels is associated with a data line and a gate line, and wherein the resistor segments comprise a first resistor segment and a second resistor segment, said display panel further comprising:
a first switching element controllable by the gate line, the first switching element operatively connected between the data line and the reflective electrode;
a second switching element controllable by the gate line, the second switching element operatively connected between the data line and first resistor segment; and
a third switching element controllable by the gate line, the third switching element operatively connected between the second resistor segment and a common line of the display panel.
15. The display panel of claim 5 , wherein the voltage divider comprises at least two resistor segments.
16. The display panel of claim 5 , wherein the resistor segments are made of poly-silicon disposed substantially in the reflection area.