Liquid crystal display device

• US 6,891,588 B2
• Filed: 04/16/2002
• Issued: 05/10/2005
• Est. Priority Date: 04/16/2001
• Status: Expired due to Term

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Kawachi, Genshirou, Hasegawa, Atsushi, Nagata, Tetsuya, Miyazawa, Toshio
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): Wang, George Y.
• Application Number:
  US10/122,214
• Publication Number:
  US 20020149724A1
• Time in Patent Office: 1,120 Days
• Field of Search: 349/113, 349/114
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs

Abstract

In a liquid crystal display device having a transmissive display region and a reflective display region within a unit pixel, the present invention disposes an optical reflection layer having an almost rectangular planar shape as extended in the unit pixel elongate direction at substantially a central portion midway between two neighboring signal electrodes, defines almost rectangular regions between the optical reflection layer and two signal electrodes adjacent thereto as the transmissive display region in the unit pixel, and forms a pixel electrode at a level spaced from that of the optical reflection layer by a dielectric film so as to cover the entire surface of the unit pixel, so that power consumption of the liquid crystal display device is reduced while image quality thereof is improved.

Claims

1. A transflective type liquid crystal display device comprising a pair of transparent substrates and a liquid crystal layer interposed between the pair of transparent substrates, wherein:

one of the pair of transparent substrates has a plurality of parallel scan electrodes extending in a first direction and being provided along a second direction intersecting the first direction, a plurality of parallel signal electrodes extending in the second direction and being provided in the first direction, and a plurality of pixel regions each surrounded by a pair of the plurality of scan electrodes adjacent to each other and a pair of the plurality of signal electrodes adjacent to each other, formed on its principal surface facing the liquid crystal layer respectively,

respective one of the plurality of pixel regions is provided with a liquid crystal drive electrode receiving an image signal from one of the plurality of signal electrodes through an active element as controlled by one of the plurality of scan electrodes, and an optical reflective layer being less in area than the liquid crystal drive electrode and reflecting incident light from another of the pair of substrates to the another of the pair of substrates, and a common electrode covered by the optical reflective layer below the optical reflective layer,

the optical reflective layer extends in a longitudinal direction of the respective one of the plurality of pixel regions below the liquid crystal drive electrode being spaced from the pair of the plurality of signal electrodes which are extended in the longitudinal direction of the respective one of the plurality of pixel regions and is electrically connected to the liquid crystal drive electrode, and

the liquid crystal drive electrode is formed above both areas provided between the optical reflective layer and the pair of the plurality of signal electrodes as well as above the optical reflective layer to let light pass from the one of the pair of substrates to liquid crystal layer through the areas and the liquid crystal drive electrode itself, and

the common electrode is electrically isolated from both the liquid crystal drive electrode and the optical reflective layer and is spaced from the optical reflective layer by an insulating layer to form a charge storage capacitance for the liquid crystal drive electrode together with the optical reflective layer.

2. A transflective type liquid crystal display device comprising a first transparent substrate and a second transparent substrate between which a liquid crystal layer is interposed, wherein:

the first transparent substrate has a plurality of scan electrodes extending in a first direction and being arranged along a second direction intersecting the first direction, a plurality of signal electrodes extending in the second direction and being arranged in the first direction, and a plurality of pixel regions, each formed on its principal surface facing the liquid crystal layer,

each of the plurality of pixel regions is surrounded by a pair of the plurality of scan electrodes adjacent to each other and a pair of the plurality of signal electrodes adjacent to each other, and is elongated in the second direction to have a length along this direction greater than that along the first direction,

respective one of the plurality of pixel regions is provided with an active element receiving an image signal from one of the plurality of signal electrodes and being controlled by one of the plurality of scan electrodes, a liquid crystal drive electrode receiving the image signal from the active and applying a voltage corresponding to the image signal to the liquid crystal layer, an optical reflective layer being disposed under the liquid crystal drive electrode and reflecting incident light thereon from the second substrate to the liquid crystal layer through the liquid crystal drive electrode, and a common electrode below and covered by the optical reflective layer,

the optical reflective layer is spaced apart from each of the pair of the plurality of signal electrodes to provide areas permitting light to pass from the first transparent substrate to the liquid crystal layer at both sides thereof extended along the pair of the signal electrodes and is electrically connected to the liquid crystal drive electrode,

each of the areas is provided between each side of the optical reflective layer and one of the pair of the signal electrodes and is covered by the liquid crystal layer drive electrode to let the light passing through the areas be transmitted into the liquid crystal through the liquid crystal drive electrode, and

the common electrode is electrically isolated from both the liquid crystal drive electrode and the optical reflective layer and is spaced from the optical reflective layer by an insulating layer to form a charge storage capacitance for the liquid crystal drive electrode together with the optical reflective layer.

3. The transflective type liquid crystal display device according to claim 2, wherein the plurality of scan electrodes are disposed below the insulating layer to be same layers as that of the common electrode, and the common electrode is made of a material utilized for the plurality of scan electrodes.

4. The transflective type liquid crystal display device according to claim 2, wherein both of the first transparent substrate and the second transparent substrate are glass substrates and the liquid crystal drive electrode is made of indium tin oxide or indium-zinc oxides.

5. The transflective type liquid crystal display device according to claim 2, further comprising a back-light unit radiating light to the liquid crystal layer through the first transparent substrate,

wherein the plurality of signal electrodes are disposed on the insulating layer to be same layers as that of the optical reflective layer,

the optical reflective layer is made of a material utilized for the plurality of signal electrodes, and

both the plurality of signal electrodes and the optical reflective layer are covered with an insulating film.

6. The transflective type liquid crystal display device according to claim 2, further comprising a back-light unit radiating light to the liquid crystal layer through the first transparent substrate,

wherein the light from the back-light unit passes through the areas spacing the optical reflective layer apart from the pair of the plurality of signal electrodes in the each of the plurality of pixel regions.

7. The transflective type liquid crystal display device according to claim 2, wherein the optical reflective layer has an almost rectangular planar shape extending in the second direction.