DISPLAY DEVICE

• US 20090207330A1
• Filed: 10/15/2008
• Published: 08/20/2009
• Est. Priority Date: 02/15/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kim, Sung-Woon, Kim, Hee-Seop, Chai, Chong-Chul, Jung, Mee-Hye, Jung, Kwang-Chul
• Granted Patent: US 8,179,489 B2
• Time in Patent Office: Days
• US Class Current: 349/39
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/13606 having means for reducing parasitic capacitance
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G09G 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52

Abstract

A display device includes a pixel electrode that includes a first sub-pixel electrode and a second sub-pixel electrode, a first thin film transistor connected to the first sub-pixel electrode, a second thin film transistor connected to the second sub-pixel electrode, an assistance capacitor connected to the first sub-pixel electrode, and a third thin film transistor connected to the assistance capacitor and the second sub-pixel electrode. The third thin film transistor includes a gate electrode, a source electrode overlapping the gate electrode and connected to the second sub-pixel electrode, and a drain electrode connected to the assistance capacitor, and a parasitic capacitance between the gate electrode and the drain electrode is equal to or less than a parasitic capacitance between the gate electrode and the source electrode.

Claims

1. A display device comprising:

a pixel electrode that includes a first sub-pixel electrode and a second sub-pixel electrode;

a first thin film transistor connected to the first sub-pixel electrode;

a second thin film transistor connected to the second sub-pixel electrode;

an assistance capacitor connected to the first sub-pixel electrode; and

a third thin film transistor connected to the assistance capacitor and the second sub-pixel electrode,

wherein the third thin film transistor comprises a gate electrode, a source electrode overlapping the gate electrode and connected to the second sub-pixel electrode, and a drain electrode connected to the assistance capacitor, and

wherein a parasitic capacitance between the gate electrode and the drain electrode is equal to or less than a parasitic capacitance between the gate electrode and the source electrode.

2. The display device of claim 1, wherein an overlapping area between the gate electrode and the drain electrode is equal to or less than the overlapping area between the gate electrode and the source electrode.

3. The display device of claim 2, wherein the drain electrode is extended in a first direction with a bar shape.

4. The display device of claim 3, wherein the source electrode encloses the drain electrode.

5. The display device of claim 4, wherein the source electrode comprises a first portion overlapping the gate electrode and extended in the first direction, and a second portion overlapping the gate electrode, connected the first portion, and extended in a second direction perpendicular to the first direction.

6. The display device of claim 5, wherein the source electrode further comprises a third portion overlapping the gate electrode, connected to the second portion, and parallel to the first portion.

7. The display device of claim 6, wherein the first to third portions substantially form a “

U”

shape opened toward the drain electrode.

8. The display device of claim 2, wherein a ratio of the overlapping area between the gate electrode and the drain electrode, and the overlapping area between the gate electrode and the source electrode, is in a range of about 1:

1 to about 1;

5.

9. The display device of claim 1, further comprising:

a first gate line connected to the first and second thin film transistors;

a second gate line connected to the third thin film transistor, and neighboring the first gate line; and

a data line connected to the first and second thin film transistors.

10. The display device of claim 9, further comprising:

a storage electrode line overlapping the pixel electrode; and

a fourth thin film transistor connected to the first gate line, the storage electrode line, and the assistance capacitor.

11. A display device comprising:

a first liquid crystal capacitor;

a first storage capacitor coupled with the first liquid crystal capacitor in parallel;

a second liquid crystal capacitor;

a second storage capacitor coupled with the second liquid crystal capacitor in parallel;

a first thin film transistor connected to the first liquid crystal capacitor;

a second thin film transistor connected to the second liquid crystal capacitor;

an assistance capacitor connected to the first liquid crystal capacitor; and

a third thin film transistor connected between the assistance capacitor and the second liquid crystal capacitor,

wherein a capacitance of the assistance capacitor is in a range of about 10% to about 50% of the sum of a capacitance of the first liquid crystal capacitor and a capacitance of the first storage capacitor.

12. The display device of claim 11, further comprising:

a first gate line connected to the first and second thin film transistors;

a second gate line connected to the third thin film transistor and neighboring the first gate line; and

a data line connected to the first and second thin film transistors.

13. The display device of claim 12, further comprising:

a storage electrode line; and

a fourth thin film transistor connected to the first gate line, the storage electrode line, and the assistance capacitor.

14. The display device of claim 11, wherein the third thin film transistor comprises a gate electrode connected to the second gate line, a source electrode connected to the second liquid crystal capacitor, and a drain electrode connected to the first liquid crystal capacitor through the assistance capacitor;

and

wherein a parasitic capacitance between the gate electrode and the drain electrode is equal to or less than a parasitic capacitance between the gate electrode and the source electrode.

15. The display device of claim 14, wherein an overlapping area between the gate electrode and the drain electrode is equal to or less than an overlapping area between the gate electrode and the source electrode.

16. The display device of claim 15, wherein the drain electrode has a bar shape and the source electrode comprises a substantially “

U”

shaped portion that encloses the drain electrode.

17. The display device of claim 15, wherein the drain electrode includes a facing portion and a connecting portion both having a bar shape.

18. The display device of claim 17, wherein the source electrode comprises a substantially “

U”

shaped portion that encloses the facing portion.

19. The display device of claim 17, wherein the source electrode includes a first portion perpendicular to the second gate line and a second portion parallel to the second gate line, and wherein the source electrode encloses a portion of the facing portion.

20. The display device of claim 17, wherein the facing portion is perpendicular to the second gate line and the source electrode is parallel to the facing portion.