Electrophoretic display and driving method thereof
View Patent ↗An electrophoretic display according to an exemplary embodiment of the present invention may include: a first substrate, a first electrode formed on the first substrate, a second electrode spaced apart from the first electrode, a second substrate facing the first substrate, and a plurality of charged particles arranged between the first substrate and the second substrate, pairs of the charged particles having different polarities. Each charged particle has at least two threshold voltages, where the threshold voltages are voltage magnitudes below which a voltage applied across the first and second electrodes does not move the associated charged particle. The pixels may represent any one of colors such as red, green, blue, white, and black by including two charged particles of different colors in one pixel and changing the attractive and repulsive force threshold voltages of each of two charged particles of different colors contained in the pixel.
1. An electrophoretic display, comprising:
a first substrate having a horizontal surface;
a first electrode formed on the horizontal surface of the first substrate;
a second substrate overlapping the first substrate;
an opaque material layer that is disposed on the first electrode and completely covers the first electrode;
barrier walls formed between the first substrate and the second substrate, the barrier walls defining pixels;
a second electrode spaced apart from the first electrode and formed on a vertical surface of a barrier wall of the barrier walls, the vertical surface of the barrier wall and the second electrode extending not parallel to the horizontal surface of the first substrate;
a plurality of charged particles arranged between the first substrate and the second substrate, pairs of the charged particles having different polarities;
an upper light blocking layer formed on the second substrate in a region to entirely cover the pairs of the charged particles when the pairs of the charged particles are attracted to the second electrode,
wherein each charged particle of the charged particles has at least two threshold voltages, and
wherein the opaque material layer and the upper light blocking layer together cover an entire area of a pixel.
2. The electrophoretic display of claim 1 , further comprising:
a barrier wall arranged between the first substrate and the second substrate and having an opening that exposes the first electrode.
3. The electrophoretic display of claim 2 , wherein:
the plurality of charged particles includes colored charged particles and white charged particles.
4. The electrophoretic display of claim 3 , wherein the opaque material layer is a lower light blocking layer formed on the first electrode.
5. The electrophoretic display of claim 4 , wherein:
the colored charged particles include red, green, and blue charged particles.
6. The electrophoretic display of claim 4 , wherein:
the colored charged particles include cyan, magenta and yellow charged particles.
7. The electrophoretic display of claim 3 , wherein:
the upper light blocking layer corresponds to the second electrode.
8. The electrophoretic display of claim 3 , wherein:
the colored charged particles are positively charged and the white charged particles are negatively charged.
9. The electrophoretic display of claim 8 , wherein:
the at least two threshold voltages of the colored charged particles include a repulsive force threshold voltage and an attractive force threshold voltage, and the repulsive force threshold voltage is different from the attractive force threshold voltage.
10. The electrophoretic display of claim 8 , wherein:
the at least two threshold voltages of the white charged particles include a repulsive force threshold voltage and an attractive force threshold voltage, and the repulsive force threshold voltage is different from the attractive force threshold voltage.
11. The electrophoretic display of claim 8 , wherein:
the at least two threshold voltages include a repulsive force threshold voltage and an attractive force threshold voltage of the colored charged particles, and a repulsive force threshold voltage and an attractive force threshold voltage of the white charged particles, and
the repulsive force threshold voltage and the attractive force threshold voltage of the colored charged particles are different from the repulsive force threshold voltage and the attractive force threshold voltage of the white charged particles, respectively.
12. The electrophoretic display of claim 6 , wherein:
the colored charged particles are negatively charged and the white charged particles are positively charged.
13. The electrophoretic display of claim 12 , wherein:
the at least two threshold voltages of the colored charged particles include a repulsive force threshold voltage and an attractive force threshold voltage, and the repulsive force threshold voltage is different from the attractive force threshold voltage.
14. The electrophoretic display of claim 12 , wherein:
the at least two threshold voltages of the white charged particles include a repulsive force threshold voltage and an attractive force threshold voltage, and the repulsive force threshold voltage is different from the attractive force threshold voltage.
15. The electrophoretic display of claim 12 , wherein:
the at least two threshold voltages include a repulsive force threshold voltage and an attractive force threshold voltage of the colored charged particles, and a repulsive force threshold voltage and an attractive force threshold voltage of the white charged particles, and
the repulsive force threshold voltage and the attractive force threshold voltage of the colored charged particles are different from the repulsive force threshold voltage and the attractive force threshold voltage of the white charged particles, respectively.
16. The electrophoretic display of claim 3 , wherein:
the second electrode is formed on the first substrate.
17. The electrophoretic display of claim 3 , wherein:
the second electrode is formed on the second substrate.
18. The electrophoretic display of claim 2 ,
wherein the opaque material layer is a white reflecting layer formed on the first electrode, and
wherein the plurality of charged particles includes colored charged particles and black charged particles.
19. The electrophoretic display of claim 18 , wherein:
the colored charged particles include red, green, and blue charged particles.
20. The electrophoretic display of claim 18 , wherein:
the colored charged particles include cyan, magenta, and yellow charged particles.
21. The electrophoretic display of claim 18 , wherein:
the upper light blocking layer corresponds to the second electrode.
22. The electrophoretic display of claim 18 , wherein:
the colored charged particles are positively charged and the black charged particles are negatively charged.
23. The electrophoretic display of claim 22 , wherein:
the at least two threshold voltages of the colored charged particles include a repulsive force threshold voltage and an attractive force threshold voltage, and the repulsive force threshold voltage is different from the attractive force threshold voltage.
24. The electrophoretic display of claim 22 , wherein:
the at least two threshold voltages of the black charged particles include a repulsive force threshold voltage and an attractive force threshold voltage, and the repulsive force threshold voltage is different from the attractive force threshold voltage.
25. The electrophoretic display of claim 22 , wherein:
the at least two threshold voltages include a repulsive force threshold voltage and an attractive force threshold voltage of the colored charged particles, and a repulsive force threshold voltage and an attractive force threshold voltage of the black charged particles, and
the repulsive force threshold voltage and the attractive force threshold voltage of the colored charged particles are different from the repulsive force threshold voltage and the attractive force threshold voltage of the black charged particles, respectively.
26. The electrophoretic display of claim 2 , wherein:
the plurality of charged particles includes at least two of red, green, and blue charged particles.
27. A method of driving an electrophoretic display comprising a plurality of pixels and barrier walls defining the pixels and formed between opposing first and second substrates, a pixel of the plurality of pixels containing a plurality of positive charged particles and a plurality of negative charged particles both positioned between a first electrode formed on a horizontal surface of the first substrate and a second electrode that is spaced apart from the first electrode and formed on a vertical surface of a barrier wall of the barrier walls, wherein the vertical surface of the barrier wall and the second electrode extending not parallel to the horizontal surface of the first substrate, and each of the positive charged particles and the negative charged particles has at least two threshold voltages, the method comprising:
positioning the positive charged particles and the negative charged particles next to the second electrode to be entirely covered by an upper light blocking layer when substantially no grayscale voltage is applied to the first and second electrodes;
positioning the negative charged particles over the first electrode and positioning the positive charged particles next to the second electrode to be entirely covered by the upper light blocking layer by applying a first grayscale voltage to the first and second electrodes, the first grayscale voltage having a magnitude greater than an attractive force threshold voltage of the negative charged particles;
positioning the negative charged particles and the positive charged particles next to the second electrode to be entirely covered by the upper light blocking layer by applying a second grayscale voltage to the first and second electrodes, the second grayscale voltage having a magnitude greater than a repulsive force threshold voltage of the negative charged particles and lower than an attractive force threshold voltage of the positive charged particles;
positioning the positive charged particles over the first electrode and positioning the negative charged particles next to the second electrode to be entirely covered by the upper light blocking layer by applying a third grayscale voltage to the first and second electrodes, the third grayscale voltage having a magnitude greater than the attractive force threshold voltage of the positive charged particles;
positioning the negative charged particles and the positive charged particles next to the second electrode to be entirely covered by the upper light blocking layer by applying a fourth grayscale voltage to the first and second electrodes, the fourth grayscale voltage having a magnitude greater than the repulsive force threshold voltage of the positive charged particles and lower than the attractive force threshold voltage of the negative charged particles; and
displaying at least one of black and white using an opaque material layer that is disposed on the first electrode and completely covers the first electrode, wherein the opaque material layer and the upper light blocking layer together cover an entire area of a pixel.
28. The driving method of claim 27 , wherein
the opaque material layer is a lower light blocking layer formed on the first electrode, and wherein when the positive charged particles and the negative charged particles are positioned under the upper light blocking layer, the pixel has a black color.
29. The driving method of claim 27 , wherein
the opaque material layer is a white reflecting layer formed on the first electrode, and wherein when the positive charged particles and the negative charged particles are positioned under the upper light blocking layer, the pixel has a white color.
30. The driving method of claim 27 , wherein:
when the negative charged particles are positioned on the first electrode, the pixel has a color of the negative charged particles.
31. The driving method of claim 27 , wherein:
when the positive charged particles are positioned on the first electrode, the pixel has a color of the positive charged particles.