Active matrix liquid crystal display device with independent potentials applied to the opposing electrode and the transistor side conductive light shielding film

• US 5,859,677 A
• Filed: 01/31/1996
• Issued: 01/12/1999
• Est. Priority Date: 01/31/1995
• Status: Expired due to Term

• Current Assignee: Gold Charm Limited (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Watanabe, Makoto, Nakashima, Koji, Sukegawa, Osamu
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Parker, Kenneth
• Application Number:
  US08/594,169
• Time in Patent Office: 1,077 Days
• Field of Search: 349/38, 349/39, 349/43, 349/44, 349/46, 349/112, 345/92
• US Class Current: 349/38
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• 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 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 2201/128 field shaping

Abstract

The active matrix type liquid crystal display device has a plurality of liquid crystal elements. Each liquid crystal element has a transistor section, a transistor side conductive light shielding film electrically connected to the transistor section, and a liquid crystal element having an opposing electrode coupled to the transistor section. There are a first potential terminal connected to the opposing electrode and a second potential terminal connected to the transistor side conductive light shielding film with a potential applied by the first potential terminal being independent from a potential applied by the second potential terminal. With this arrangement, the lateral field components around the pixel portion, which become a cause for the reverse tilt of the liquid crystal, are relatively reduced with respect to the vertical field components, thus reducing the disclination and providing excellent display characteristics without residual images.

Claims

1. An active matrix type liquid crystal display device having a plurality of liquid crystal elements, each of said liquid crystal elements comprising:

a transistor section having a gate electrode, a gate insulating film, a semiconductor film, a source electrode, a drain electrode, and a passivation insulating film;

a first conductive light shielding film electrically coupled to said transistor section and having an open portion;

a pixel electrode formed over said open portion of said first conductive light shielding film and electrically connected to said source electrode of said transistor section;

a liquid crystal layer formed on said passivation insulating film;

an opposing electrode formed on said liquid crystal layer; and

a means to apply to said first conductive light shielding film a potential independent of a potential applied to said opposing electrode

wherein, during operation of said first conductive light shielding film, a voltage of said first conductive light shielding film is capable of being different from a voltage of said opposing electrode, thereby, reducing disclination in said liquid crystal elements.

2. The active matrix type liquid crystal display device according to claim 1, in which said means to apply a potential comprises a first potential terminal connected to said opposing electrode and a second potential terminal connected to said first conductive light shielding film.

3. The active matrix type liquid crystal display device according to claim 1, wherein a load voltage applied to said first conductive light shielding film is several tens of volts lower than an off-set voltage applied to said opposing electrode.

4. The active matrix type liquid crystal display device according to claim 3, which further comprises a second conductive light shielding film disposed on said passivation insulating film on a back channel at said transistor section, and a contact hole provided in an insulating film layer disposed on said first conductive light shielding film, said second conductive light shielding film and said first conductive light shielding film being electrically inter-connected through said contact hole.