Liquid crystal display and method of driving the same

• US 20070115400A1
• Filed: 09/13/2006
• Published: 05/24/2007
• Est. Priority Date: 11/23/2005
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Mobile Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kim, Ghang, Kim, Do, Park, Ji, Hwang, Won, Heo, Hae
• Granted Patent: US 7,633,572 B2
• Time in Patent Office: Days
• US Class Current: 349/43
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence

Abstract

A liquid crystal display (LCD) includes a first substrate having an array of wiring lines and pixel regions. The pixel regions have pixel electrodes, thin film transistors with drain electrodes, and storage capacitors. The LCD also includes a second substrate having color filters, black matrices, opened regions to receive external light positioned in regions in which the black matrices are not positioned, and transparent common electrodes. Liquid crystal is between the first and second substrates. The opened regions correspond to first regions in which the drain electrodes and the pixel electrodes are connected and second regions in which the storage capacitors are positioned. In one embodiment, the liquid is driven in a normally white mode when the LCD is driven in a transmissive mode, and is driven in a normally black mode when the LCD is driven in a reflective mode.

Claims

1. A liquid crystal display comprising:

a first substrate having an array of wiring lines and pixel regions, the pixel regions having pixel electrodes, thin film transistors having drain electrodes, and storage capacitors positioned therein;

a second substrate having color filters in regions corresponding to the pixel regions, black matrices between the color filters, opened regions to receive external light positioned in regions in which the black matrices are not positioned, and transparent common electrodes on the color filters and the black matrices; and

a liquid crystal layer between the first substrate and the second substrate,

wherein the opened regions correspond to first regions in which respective ones of the drain electrodes and the pixel electrodes are connected to each other and second regions in which the storage capacitors are positioned in the pixel regions of the first substrate.

2. The liquid crystal display as claimed in claim 1, wherein a first orientation layer and a second orientation layer are on internal surfaces of the first substrate and the second substrate, respectively.

3. The liquid crystal display as claimed in claim 2, wherein the first orientation layer and the second orientation layer are oriented to be anti-parallel so that the liquid crystal layer between the orientation layers is in an electrically controlled birefringence (ECB) mode.

4. The liquid crystal display as claimed in claim 1, wherein the phase difference value of the liquid crystal layer is set as λ

/2.

5. The liquid crystal display as claimed in claim 1, further comprising a first polarizer and a second polarizer arranged on external surfaces of the first substrate and the second substrate, respectively, so that transmission axes of the first polarizer and the second polarizer intersect each other.

6. The liquid crystal display as claimed in claim 5, wherein a polarization film for generating λ

/2 polarization is used as each of the first polarizer and the second polarizer.

7. The liquid crystal display as claimed in claim 1, further comprising a backlight that is a light source device adapted to supply light during operation of the liquid crystal display in a transmissive mode under the first substrate.

8. The liquid crystal display as claimed in claim 1,

wherein the array of wiring lines comprises gate wiring lines and data wiring lines crossing the gate wiring lines at the pixel regions,

wherein the thin film transistors further comprise gate electrodes, source electrodes, and active layers,

wherein the source electrodes are connected to respective ones of the data wiring lines, and

the gate electrodes are connected to respective ones of the gate wiring lines.

9. The liquid crystal display as claimed in claim 8, wherein the storage capacitors comprise:

first electrodes aligned in parallel to the gate wiring lines; and

an insulating layer and second electrodes integrated with the drain electrodes and sequentially positioned on respective ones of the first electrodes.

10. A method of driving a liquid crystal display having liquid crystal comprising:

selectively driving the liquid crystal display in a transmissive mode and in a reflective mode,

wherein the liquid crystal is driven in a normally white mode when the liquid crystal display is driven in the transmissive mode, and

wherein the liquid crystal is driven in a normally black mode when the liquid crystal display is driven in the reflective mode.

11. The method as claimed in claim 10, further comprising providing the liquid crystal display comprising:

providing a first substrate having an array of wiring lines and pixel regions, the pixel regions having pixel electrodes, thin film transistors having drain electrodes, and storage capacitors positioned therein;

providing a second substrate having color filters in regions corresponding to the pixel regions, black matrices between the color filters, opened regions to receive external light positioned in regions in which the black matrices are not positioned during the operation of the liquid crystal display in a reflective mode, and transparent common electrodes on the color filters and the black matrices; and

providing the liquid crystal between the first substrate and the second substrate,

wherein the opened regions correspond to first regions in which respective ones of the drain electrodes and the pixel electrodes are connected to each other and second regions in which the storage capacitors are positioned in the pixel regions of the first substrate.

12. The method as claimed in claim 11, further comprising providing a first polarizer and a second polarizer arranged on external surfaces of the first substrate and the second substrate, respectively, so that transmission axes of the first polarizer and the second polarizer intersect each other.

13. The method as claimed in claim 12, wherein a polarization film for generating λ

/2 polarization is used as each of the first polarizer and the second polarizer.

14. The method as claimed in claim 11, further comprising setting a phase difference value of the liquid crystal as λ

/2.

15. The method as claimed in claim 14, further comprising applying a signal voltage that makes the phase difference value of the liquid crystal λ

/4 during operation of the liquid crystal display in the reflective mode as a maximum signal voltage.