Liquid crystal display device

• US 8,767,159 B2
• Filed: 04/20/2012
• Issued: 07/01/2014
• Est. Priority Date: 05/18/2007
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kimura, Hajime
• Primary Examiner(s): CHEN, WEN YING PATTY
• Application Number:
  US13/451,619
• Publication Number:
  US 20120249907A1
• Time in Patent Office: 802 Days
• Field of Search: 349/144, 349/48, 349/147, 349/41, 349/38
• US Class Current: 349/144
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/136295 Materials; Compositions; Manufacture processes
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G09G 2300/0443 with several sub-pixels for the same colour in a pixel, not specifically used to display gradations G09G3/364 takes precedence
• CPC Class Codes: G09G 2300/0447 for multi-domain technique to improve the viewing angle in a liquid crystal display, such as multi-vertical alignment [MVA]
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• 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 2320/10 Special adaptations of display systems for operation with variable images
• CPC Class Codes: G09G 2320/106 Determination of movement vectors or equivalent parameters within the image
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 2340/16 : Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/2022 : using sub-frames
• CPC Class Codes: G09G 3/3233 : with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3648 : using an active matrix G09G3/367 - G09G3/3696 take precedence
• 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 27/12 : the substrate being other than a semiconductor body, e.g. an insulating body

Abstract

To improve viewing angle characteristics by varying voltage which is applied between liquid crystal elements. A liquid crystal display device in which one pixel is provided with three or more liquid crystal elements and the level of voltage which is applied is varied between the liquid crystal elements is varied. In order to vary the level of the voltage which is applied between the liquid crystal elements, an element which divides the applied voltage is provided. In order to vary the level of the applied voltage, a capacitor, a resistor, a transistor, or the like is used. Viewing angle characteristics can be improved by varying the level of the voltage which is applied between the liquid crystal elements.

Claims

1. A liquid crystal display device comprising a pixel comprising:

a first transistor comprising a first gate, a first source and a first drain;

a second transistor comprising a second gate, a second source and a second drain;

a first capacitor comprising a first terminal and a second terminal;

a second capacitor comprising a third terminal and a fourth terminal;

a first liquid crystal element comprising a first electrode and a second electrode;

a second liquid crystal element comprising a third electrode and a fourth electrode,

a third transistor comprising a third gate, a third source and a third drain; and

a third liquid crystal element comprising a fifth electrode and a sixth electrode,

wherein one of the first source and the first drain is electrically connected to a first line,

wherein the other of the first source and the first drain is electrically connected to one of the first terminal and the second terminal,

wherein the first gate is electrically connected to a second line;

wherein one of the second source and the second drain is electrically connected to the first line,

wherein the other of the second source and the second drain is electrically connected to the other of the first terminal and the second terminal,

wherein the second gate is electrically connected to the second line,

wherein the other of the first terminal and the second terminal is electrically connected to one of the third terminal and the fourth terminal,

wherein one of the first electrode and the second electrode is electrically connected to the one of the first terminal and the second terminal,

wherein the other of the first electrode and the second electrode is electrically connected to a third line,

wherein one of the third electrode and the fourth electrode is electrically connected to the third line,

wherein the third gate is electrically connected to the second line,

wherein one of the third source and the third drain is electrically connected to the other of the third terminal and the fourth terminal,

wherein one of the fifth electrode and the sixth electrode is electrically connected to the other of the third terminal and the fourth terminal,

wherein the other of the fifth electrode and the sixth electrode is electrically connected to the third line, and

wherein each of the first transistor, the second transistor, and the third transistor comprises an oxide semiconductor.

2. The liquid crystal display device according to claim 1, wherein the oxide semiconductor includes a-InGaZnO.

3. The liquid crystal display device according to claim 1,

wherein each of the first transistor, the second transistor, and the third transistor comprises a gate insulating film having a stacked-film structure, and

wherein the gate insulating film comprises at least one of a silicon oxide film, a silicon nitride film, and a silicon oxynitride film.

4. The liquid crystal display device according to claim 1, wherein each of the first transistor, the second transistor, and the third transistor comprises a first semiconductor layer, and a second semiconductor layer over the first semiconductor layer.

5. The liquid crystal display device according to claim 1, wherein one of the first electrode and the second electrode, one of the third electrode and the fourth electrode, and one of the fifth electrode and the sixth electrode have an opening.

6. The liquid crystal display device according to claim 1, wherein one of the first electrode and the second electrode, one of the third electrode and the fourth electrode, and one of the fifth electrode and the sixth electrode have a comb-shaped.

7. The liquid crystal display device according to claim 1, further comprising a light-blocking film overlapping with the first transistor, the second transistor and the third transistor.

8. The liquid crystal display device according to claim 1,

wherein each of the first source, the first drain, the second source, the second drain, the third source and the third drain comprises a conductive layer having a stacked-layer structure, and

wherein the conductive layer comprises at least one element selected from a group consisting Ti, Mo, Ta, Cr, W, Al, Nd, Cu, Ag, Au, Pt, Nb, Si, Zn, Fe, Ba, and Ge.

9. The liquid crystal display device according to claim 1, wherein the other of the third electrode and the fourth electrode is electrically connected to the other of the second source and the second drain.

10. The liquid crystal display device according to claim 1, wherein the other of the third source and the third drain is electrically connected to a fourth line.

11. A liquid crystal display device comprising a pixel comprising:

a first transistor comprising a first gate, a first source and a first drain;

a second transistor comprising a second gate, a second source and a second drain;

a first capacitor comprising a first terminal and a second terminal;

a second capacitor comprising a third terminal and a fourth terminal;

a first liquid crystal element comprising a first electrode and a second electrode;

a second liquid crystal element comprising a third electrode and a fourth electrode,

a third transistor comprising a third gate, a third source and a third drain; and

a third liquid crystal element comprising a fifth electrode and a sixth electrode,

wherein one of the first source and the first drain is electrically connected to a first line,

wherein the other of the first source and the first drain is electrically connected to one of the first terminal and the second terminal,

wherein the first gate is electrically connected to a second line;

wherein one of the second source and the second drain is electrically connected to the first line,

wherein the other of the second source and the second drain is electrically connected to the other of the first terminal and the second terminal,

wherein the second gate is electrically connected to the second line,

wherein the other of the first terminal and the second terminal is electrically connected to one of the third terminal and the fourth terminal,

wherein one of the first electrode and the second electrode is electrically connected to the one of the first terminal and the second terminal,

wherein the other of the first electrode and the second electrode is electrically connected to a third line,

wherein one of the third electrode and the fourth electrode is electrically connected to the third line,

wherein the third gate is electrically connected to the second line,

wherein one of the third source and the third drain is electrically connected to the other of the third terminal and the fourth terminal,

wherein one of the fifth electrode and the sixth electrode is electrically connected to the other of the third terminal and the fourth terminal,

wherein the other of the fifth electrode and the sixth electrode is electrically connected to the third line, and

wherein each of the first transistor, the second transistor, and the third transistor comprises ZnO.

12. The liquid crystal display device according to claim 11,

wherein each of the first transistor, the second transistor, and the third transistor comprises a gate insulating film having a stacked-film structure, and

wherein the gate insulating film comprises at least one of a silicon oxide film, a silicon nitride film, and a silicon oxynitride film.

13. The liquid crystal display device according to claim 11, wherein each of the first transistor, the second transistor, and the third transistor comprises a first semiconductor layer, and a second semiconductor layer over the first semiconductor layer.

14. The liquid crystal display device according to claim 11, wherein one of the first electrode and the second electrode, one of the third electrode and the fourth electrode, and one of the fifth electrode and the sixth electrode have an opening.

15. The liquid crystal display device according to claim 11, wherein one of the first electrode and the second electrode, one of the third electrode and the fourth electrode, and one of the fifth electrode and the sixth electrode have a comb-shaped.

16. The liquid crystal display device according to claim 11, further comprising a light-blocking film overlapping with the first transistor, the second transistor and the third transistor.

17. The liquid crystal display device according to claim 11,

wherein each of the first source, the first drain, the second source, the second drain, the third source and the third drain comprises a conductive layer having a stacked-layer structure, and

wherein the conductive layer comprises at least one element selected from a group consisting Ti, Mo, Ta, Cr, W, Al, Nd, Cu, Ag, Au, Pt, Nb, Si, Zn, Fe, Ba, and Ge.

18. The liquid crystal display device according to claim 11, wherein the other of the third electrode and the fourth electrode is electrically connected to the other of the second source and the second drain.

19. The liquid crystal display device according to claim 11, wherein the other of the third source and the third drain is electrically connected to a fourth line.