Liquid crystal display device

• US 7,830,345 B2
• Filed: 02/13/2006
• Issued: 11/09/2010
• Est. Priority Date: 02/15/2005
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shibasaki, Masakazu, Tsuda, Hideaki, Tasaka, Yasutoshi, Nakanishi, Yohei, Yoshida, Hidefumi, Kamada, Tsuyoshi
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Edwards; Carolyn R
• Application Number:
  US11/352,412
• Publication Number:
  US 20070024556A1
• Time in Patent Office: 1,730 Days
• Field of Search: 345 88-100
• US Class Current: 345/88
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• 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 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G02F 2203/30 Gray scale

Abstract

One picture element is divided into first and second sub-picture element regions. A sub-picture element electrode connected directly (not via capacitive coupling) to a source electrode of a TFT is placed in the first sub-picture element region and a sub-picture element electrode capacitively coupled to a control electrode connected to a source electrode is placed in the second sub-picture element region. A transparent resin film is formed in the first sub-picture element region and this makes a liquid crystal layer thickness in the second sub-picture element region thicker than that of the first sub-picture element region.

Claims

1. A liquid crystal display device formed of first and second substrates placed opposite to each other and a liquid crystal filled in a space between these substrates while one picture element is being divided into at least first and second sub-picture element regions, comprising:

a first sub-picture element electrode formed in the first sub-picture element region on the first substrate and applied with a first voltage in accordance with display signals;

a second sub-picture element electrode formed in the second sub-picture element region on the first substrate and applied with a second voltage lower than the first voltage; and

a common electrode formed on the second substrate and opposed to the first and second sub-picture element electrodes while interposing a liquid crystal layer in between,

wherein a liquid crystal layer thickness of the second sub-picture element region is thicker than that of the first sub-picture element region.

2. The liquid crystal display device according to claim 1, wherein a transparent insulating film with a thickness corresponding to a difference in the liquid crystal layer thicknesses of the first and second sub-picture element regions is formed in the first sub-picture element region.

3. The liquid crystal display device according to claim 1, wherein protrusions for alignment control made of a dielectric are formed on the second substrate.

4. The liquid crystal display device according to claim 1, wherein the liquid crystals have negative dielectric anisotropy.

5. The liquid crystal display device according to claim 1, wherein data bus lines supplied with the display signals, gate bus lines supplied with scanning signals, a thin film transistor driven by the scanning signals by connecting a drain electrode to the data bus lines, and a control electrode connected to a source electrode of the thin film transistor are formed on the first substrate, and

wherein the first sub-picture element electrode is electrically connected to the source electrode of the thin film transistor and the second sub-picture element electrode is capacitively coupled to the control electrode.

6. The liquid crystal display device according to claim 5, wherein a color filter of any one color of red, green and blue is formed for each picture element on the second substrate and at least two or more of these color filters are laminated to form a shading film in a part opposite to the gate bus lines, the data bus lines and the thin film transistor.

7. The liquid crystal display device according to claim 6, wherein a transparent insulating film and protrusions made of a dielectric are laminated on the shading film to form spacers in positions opposite to parts where the gate bus lines and the data bus lines on the second substrate intersect.

8. The liquid crystal display device according to claim 6, wherein the liquid crystal layer thicknesses of the red picture element placed with the red color filter and of the green picture element placed with the green color filter are thicker than that of the blue picture element placed with the blue color filter.

9. The liquid crystal display device according to claim 1, comprising:

a first viewing angle compensation film for offsetting a liquid crystal layer retardation in the first sub-picture element region; and

a second viewing angle compensation film for offsetting a liquid crystal layer retardation in the second sub-picture element region,

wherein the first and second viewing angle compensation films have mutually different compensation capabilities.

10. The liquid crystal display device according to claim 9, wherein the first and second viewing angle compensation films are formed on a surface of the liquid crystal layer side on the second substrate.

11. The liquid crystal display device according to claim 1, wherein polarizing plates are respectively placed on surfaces of the first and second substrates present in the sides opposite to the liquid crystal layer and absorption axes of these polarizing plates are mutually perpendicular.

12. The liquid crystal display device according to claim 1, wherein the first and second sub-picture element electrodes are substantially coplanar.