Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
2001-08-02
2004-03-23
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
C349S143000, C349S144000, C349S192000
Reexamination Certificate
active
06710825
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device and a defect repairing method for the same.
Recently, liquid crystal display devices have been practically used in the fields of OA equipment and AV equipment owing to their advantages in compactness, small weight and size and small consumption power. In particular, an active matrix liquid crystal display device including a switching element (active device) in each picture element is capable of producing a fine dynamic display and hence is used as a display for a variety of equipment.
In an active matrix liquid crystal display device, picture elements are composed of picture element electrodes provided in the form of a matrix, a counter electrode opposing the picture element electrodes and a liquid crystal layer disposed therebetween. Each of a plurality of picture elements is controlled in its display state in accordance with an electric signal supplied through the switching element.
In an active matrix liquid crystal display device, short-circuit may be caused between the picture element electrode and the counter electrode or the like due to a conducting debris mixed in the liquid crystal layer. A normal voltage cannot be applied to a picture element in which the short-circuit through the picture element electrode is caused, resulting in a display defect that desired display cannot be obtained.
As a method for repairing a display defect, Japanese Laid-Open Patent Publication No. 4-178622 discloses a defect repairing method in which a photoresist including a black pigment is applied on the face of a glass substrate and a shield film is formed by exposing and curing a portion of the photoresist positioned on merely a picture element suffering from a display defect, so as to change a bright defect into an opaque point (dark defect). An dark defect is less visually recognized than a bright defect and hence merely slightly affects the display quality.
The present inventors have, however, found that a display defect cannot be effectively repaired by the defect repairing method disclosed in Japanese Laid-Open Patent Publication No. 4-178622.
In the defect repairing method of Japanese Laid-Open Patent Publication No. 4-178622, the entire picture element suffering from a bright defect is covered with a shield film formed so as to change the entire picture element into an opaque point, and therefore, the entire picture element having the display defect cannot make contribution to the display.
SUMMARY OF THE INVENTION
The present invention was devised in consideration of the aforementioned conventional problem, and an object is providing a liquid crystal display device capable of repairing a display defect without sacrificing an entire picture element having the display defect and providing a defect repairing method employed in the liquid crystal display device.
The object is achieved by first and second liquid crystal display devices and defect repairing methods for these devices described below.
The first liquid crystal display device of this invention includes a first substrate; a second substrate; a liquid crystal layer disposed between the first substrate and the second substrate; a plurality of picture element regions for producing a display; and in each of the plurality of picture element regions, a picture element electrode provided on a face of the first substrate facing the liquid crystal layer and a switching element electrically connected to the picture element electrode, and the picture element electrode includes a plurality of sub-picture element electrodes and a plurality of contact portions each for mutually electrically connecting at least some of the sub-picture element electrodes, and at least one of the plurality of sub-picture element electrodes is electrically connected to the switching element via a plurality of connection paths. Thus, the aforementioned object can be achieved.
The first liquid crystal display device preferably further includes a counter electrode provided on the second substrate and opposing the picture element electrode with the liquid crystal layer sandwiched therebetween, and preferably, the picture element electrode is composed of a solid portion including the plurality of sub-picture element electrodes and the plurality of contact portions, and a plurality of openings, and in each of the plurality of picture element regions, the liquid crystal layer is formed into a plurality of liquid crystal domains each in a radially-inclined orientation state correspondingly to the plurality of openings and the solid portion by inclined electric fields generated at respective edge portions of the plurality of openings of the picture element electrode when a voltage is applied between the picture element electrode and the counter electrode, whereby producing a display by changing orientation states of the plurality of liquid crystal domains in accordance with the applied voltage.
Preferably, at least some of the plurality of openings have substantially the same shape and the same size, and form at least one unit lattice arranged so as to have rotational symmetry.
Preferably, each of the at least some of the plurality of openings is in a rotationally symmetrical shape.
Alternatively, each of the at least some of the plurality of openings may be in a substantially circular shape.
Each region of the solid portion surrounded with the at least some of the plurality of openings may be in a substantially circular shape.
Preferably, in each of the plurality of picture element regions, a total area of the plurality of openings of the picture element electrode is smaller than an area of the solid portion of the picture element electrode.
The liquid crystal display device preferably further includes a protrusion within each of the plurality of openings, and preferably, a cross-sectional shape of the protrusion taken in a plane direction of the substrate is the same as a shape of the corresponding opening, and a side face of the protrusion has orientation-regulating force for orienting liquid crystal molecules of the liquid crystal layer in the same direction as an orientation-regulating direction obtained by the inclined electric field.
In the first defect repairing method for a liquid crystal display device of this invention, the liquid crystal display device includes a first substrate; a second substrate; a liquid crystal layer disposed between the first substrate and the second substrate; a plurality of picture element regions for producing a display; and in each of the plurality of picture element regions, a picture element electrode provided on a face of the first substrate facing the liquid crystal layer and a switching element electrically connected to the picture element electrode, the picture element electrode being composed of a plurality of sub-picture element electrodes and a plurality of contact portions for mutually electrically connecting at least some of the plurality of sub-picture element electrodes, and at least one of the plurality of sub-picture element electrodes being electrically connected to the switching element via a plurality of connection paths, and the defect repairing method includes the steps of specifying a picture element region having a display defect among the plurality of picture element regions and specifying a sub-picture element electrode suffering from short-circuit among the plurality of sub-picture element electrodes in the specified picture element region; and electrically disconnecting the specified sub-picture element electrode from the switching element with keeping electrical connection between the at least one of the plurality of sub-picture element electrodes and the switching element by cutting off a contact portion connected to the specified sub-picture element electrode among the plurality of contact portions. Thus, the aforementioned object can be achieved.
The second liquid crystal display device of this invention includes a first substrate; a second substrate; a liquid crystal layer disposed between the first substrat
Kubo Masumi
Maekawa Kazuhiro
Ochi Takashi
Ogishima Kiyoshi
Yamamoto Akihiro
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
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