ELECTROWETTING DISPLAY DEVICE AND DRIVING METHOD THEREOF

• US 20130215095A1
• Filed: 07/27/2012
• Published: 08/22/2013
• Est. Priority Date: 02/17/2012
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: SHIN, Sang Min, PARK, Mun-Soo, HUA, Chang Ku, KIM, Woo Song, CHOI, Uk Chul, LEE, So-Hyun
• Granted Patent: US 9,494,788 B2
• Time in Patent Office: Days
• US Class Current: 345/212
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 3/348 based on the deformation of a fluid drop, e.g. electrowetting

Abstract

A display device includes a first electrode, a second electrode, a third electrode, a lyophobic layer, a first liquid, and a second liquid, where the lyophobic layer is lyophobic to the second liquid. A method of driving the display device includes: providing a first potential difference between the first electrode and the third electrode to thereby cause the first liquid to begin moving toward the second electrode; providing a second potential difference between the second electrode and the third electrode while reducing the first potential difference to thereby cause the first liquid to move toward the first electrode; and removing the second potential difference to thereby cause the first liquid to slow down in its movement toward the first electrode or to stop in its movement toward the first electrode.

Claims

1. A method of driving a display device, where the display device comprises a first electrode having a respective first surface disposed in a first area, a second electrode having a respective second surface disposed in a second area, the second electrode being spaced apart from the first electrode, a lyophobic layer provided over the respective first and second surfaces of the first and second electrodes, a third electrode spaced apart from, above, and facing the lyophobic layer, a first body of a first liquid disposed in a space between the lyophobic layer and the third electrode, and a second body of a second liquid also disposed in the space, the liquid of the second body of liquid being immiscible with the liquid of the first body of liquid, the lyophobic layer being lyophobic with respect to the second liquid, the method comprising:

providing a first potential difference between the first electrode and the third electrode, causing the first liquid to move toward the second area;

providing a second potential difference between the second electrode and the third electrode while reducing the first potential difference, causing at least part of the first liquid to start spreading movement towards the first area; and

removing the second potential difference, causing the at least part of the first liquid to slow down in the spreading movement toward the first area or to stop the spreading movement toward the first area.

2. The method of claim 1, wherein the first liquid entirely covers the second area.

3. The method of claim 1, wherein the providing of the second potential difference comprises:

applying a substantially constant voltage signal to the third electrode; and

applying a pulse-including voltage signal including at least one pulse to the second electrode.

4. The method of claim 3, wherein the pulse-including voltage signal comprises at least two pulses.

5. The method of claim 1, wherein there is substantially no potential difference between the second electrode and the third electrode during the providing of the first potential difference.

6. The method of claim 5, wherein

a first voltage signal applied to the first electrode has a first value in the providing of the first voltage difference and has a second value different from the first value in the providing of the second potential difference and in the removing of the second potential difference, and

a second voltage signal applied to the second electrode has a third value closer to the second value than to the first value in the providing of the first voltage difference, has a fourth value different from the third value or swings between the third value and the fourth value in the providing of the second potential difference, and has the third value in the removing of the second potential difference,

a third voltage signal applied to the third electrode maintains the third value during the providing of the first voltage difference, during the providing of the second potential difference, and during the removing of the second potential difference.

7. The method of claim 6, wherein the fourth value is substantially the same as the first value.

8. The method of claim 6, wherein the first, second and fourth value is disposed polarity wise at a same side apart from the third value.

9. The method of claim 1, wherein the first liquid forms as a coalesced single body of the first liquid during the providing of the second potential difference and during the removing of the second potential difference.

10. A method of driving a display device, where the display device has a first electrode, a second electrode spaced apart from the first electrode, a lyophobic layer disposed on the first and second electrodes, a third electrode spaced apart from and facing the lyophobic layer, a first liquid disposed in a space between the lyophobic layer and the third electrode, and a second liquid disposed in the space, the second liquid being immiscible with the first liquid, the lyophobic layer being lyophobic relative to the second liquid, the method comprising:

providing a first potential difference between the first electrode and the third electrode to thereby display a first luminance;

providing a second potential difference between the second electrode and the third electrode while reducing the first potential difference to thereby transition from displaying the first luminance to displaying a second luminance different from the first luminance; and

removing the second potential difference before completing the transition.

11. The method of claim 10, wherein the first liquid covers an entire area of the second electrode.

12. The method of claim 10, wherein the providing of the second potential difference comprises:

applying a substantially constant voltage to the third electrode; and

applying a pulse-including voltage including at least one pulse to the second electrode.

13. The method of claim 10, wherein there is substantially no potential difference between the second electrode and the third electrode during the providing of the first potential difference.

14. A method of driving a display device including a first electrode, a second electrode spaced apart from the first electrode, a lyophobic layer on the first and second electrodes, a third electrode facing the lyophobic layer, a first liquid disposed in a first part of a space between the lyophobic layer and the third electrode, and a second liquid disposed in a second part of the space, the second liquid being immiscible with the first liquid, the lyophobic layer being lyophobic relative to the second liquid, the method comprising:

providing an electric field that is stronger in a first region between the first electrode and the third electrode than in a second region between the second electrode and the third electrode to thereby cause the first liquid to move to the second region while the second liquid is caused to move into the first region;

providing an electric field in the second region that is stronger than a field, if any, present in the first region to thereby cause a movement of the first liquid toward the first region; and

providing an electric field weaker in the second region than in the first region before the movement of the first liquid toward the first region stops, thereby slowing down or stopping the movement of the first liquid toward the first region.

15. A method of driving a display device including a first electrode coupled to be supplied with a first voltage signal, a second electrode spaced apart from the first electrode and coupled to be supplied with a second voltage signal, a lyophobic layer disposed on the first and second electrodes, a third electrode spaced apart from and facing the lyophobic layer and coupled to be supplied with a third voltage signal, a first liquid disposed in a part of a space between the lyophobic layer and the third electrode, and a second liquid disposed in another part of the space, the second liquid being immiscible with the first liquid, the lyophobic layer being lyophobic to the second liquid, the method comprising:

making both the second voltage signal and the third voltage signal have a first value while making the first voltage signal have a second value different from the first value to thereby display an initial optical gray level;

changing the first voltage signal from the second value to a third value and the second voltage signal from the first value to a fourth value different from the first value while maintaining the first value of the third voltage signal so as to thereby provide a transition from the initial optical gray level to a different target gray level, the third value being closer to the first value than the second value; and

returning the second voltage signal from the fourth value to the first value while maintaining values of the first voltage signal and the third voltage signal before completing the transition.

16. The method of claim 15, wherein the fourth value is substantially the same as the second value.

17. A method of driving a display device including a first electrode, a second electrode spaced apart from the first electrode, a lyophobic layer on the first and second electrodes, a third electrode facing the lyophobic layer, a first liquid in a space between the lyophobic layer and the third electrode, and a second liquid in the space, the second liquid being immiscible with the first liquid, the lyophobic layer being lyophobic to the second liquid, the method comprising:

providing a first potential difference between the first electrode and the third electrode to thereby display a first gray;

providing a second potential difference between the second electrode and the third electrode while reducing the first potential difference; and

removing the second potential difference to thereby display a second gray different from the first gray,

wherein a time duration for the providing of the second potential difference is shorter than a time duration for the transition from the first gray to the second gray without removing the second potential difference.

18. A display device comprising:

a first panel;

a second panel facing the first panel;

a first liquid disposed in part of a space between the first panel and the second panel; and

a second liquid disposed in another part of the space between the first panel and the second panel, the second liquid being immiscible with the first liquid,

wherein the first panel comprises;

a first substrate;

a first gate line and a second gate line on the first substrate;

a first data line and a second data line crossing the first gate line and the second gate line;

a first thin film transistor connected to the first gate line and the first data line;

a second thin film transistor connected to the second gate line and the second data line;

a first electrode connected to the first thin film transistor;

a second electrode connected to the first thin film transistor and spaced apart from the first electrode;

a lyophobic layer on the first electrode and the second electrode; and

a partition wall on the lyophobic layer and containing the first liquid in a confinement area bounded by the partition wall, where each of the first gate line and the second gate line passes through the confinement area enclosed by the partition wall, and

the second panel comprises;

a second substrate facing the first substrate; and

a third electrode on the second substrate.

19. The display device of claim 18, wherein at least one portion of the partition wall is spaced apart from the first electrode and the second electrode.

20. The display device of claim 18, wherein the second electrode is smaller in area than a minimum area that is occupiable by the first liquid.