Liquid crystal cells – elements and systems – Particular structure – Holder – support – frame – or housing
Reexamination Certificate
1999-04-20
2002-06-25
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Holder, support, frame, or housing
C349S058000, C349S150000
Reexamination Certificate
active
06411353
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device (hereinafter, referred to as “LCD”), and particularly to an LCD with its upper and lower cases clamped together by crimping portions of one of the upper and lower cases at the other.
LCDs have been widely adopted as display devices capable of displaying a high-definition color image used for notebook computers and display monitors.
LCDs are of the following two types. One is a simple matrix type LCD which uses a liquid crystal panel having a liquid crystal layer sandwiched between a pair of substrates each having a plurality of electrodes parallel with each other on its inner surface with the electrodes on one of the pair of the substrates intersecting the electrodes on the other of the pair. The other is an active matrix type LCD which uses a liquid crystal panel having a switching element for selecting each of a plurality of picture elements on one of a pair of substrates sandwiching a liquid crystal layer therebetween.
The active matrix type LCD is further classified into two types: one is a so-called vertical electric field type LCD (commonly called a TN active matrix type LCD) using a liquid crystal panel in which electrodes for selecting picture elements are formed on each of a pair of upper and lower substrates; and the other is a so-called horizontal electric field type LCD (commonly called an in-plane switching (IPS) type LCD) using a liquid crystal panel in which electrodes for selecting picture elements are formed on only one of a pair of upper and lower substrates.
The liquid crystal panel of the former TN active matrix type LCD is configured such that liquid crystal molecules are aligned to twist by 90° between a pair of substrates and a pair of polarizers are attached on the outer surfaces of the upper and lower substrates of the liquid crystal panel such that their absorption axes are in a cross-Nicol arrangement and the absorption axis of the entrance-side polarizer is parallel or perpendicular to a direction of rubbing a liquid crystal molecule alignment film adjacent to the entrance-side polarizer.
In such a TN active matrix type LCD, when no voltage is applied to the liquid crystal layer, incident light is linearly polarized through the entrance-side polarizer. The linearly polarized light propagates along the twisted liquid crystal molecules of the liquid crystal layer, and if the transmission axis of the exit-side polarizer conforms to the azimuthal angle of the linearly polarized light, the linearly polarized light entirely goes out of the exit-side polarizer to form a white image (so-called normally open mode).
When a voltage is applied to the liquid crystal layer, directors of unit vectors each indicating the mean alignment direction of the molecular axis of each of liquid crystal molecules of the liquid crystal layer are made perpendicular to the substrate plane, and they conform to the absorption axis of the exit-side polarizer because the azimuthal angle of the entrance-side linearly polarized light is not changed, thereby leading to a black image (see “Basis and Application of Liquid Crystal” published by Kougyo Chousa Kai in 1991).
On the other hand, for the IPS type LCD in which electrodes for selecting picture elements and electrode lines are formed on only one of a pair of substrates and the liquid crystal layer is switched in a plane parallel to the substrate by applying a voltage between two adjacent electrodes (a picture element electrode and a counter electrode) on the substrate, the polarizers are disposed so that a black image is formed when no voltage is applied to the liquid crystal layer (so-called normally close mode).
In the IPS type LCD, molecules of the liquid crystal layer are parallel to the substrate and in a homogeneous alignment. In the case where no voltage is applied to the liquid crystal layer, directors of the liquid crystal layer in a plane parallel to the substrate are parallel to the arrangement direction of the electrodes or inclined therefrom at a small angle. On the other hand, in the case where a voltage is applied to the liquid crystal layer, the direction of the directors of the liquid crystal layer is shifted in the direction perpendicular to the arrangement direction of the electrodes along with the applied voltage to the liquid crystal layer, and when the direction of the directors of the liquid crystal layer is inclined by 45° toward the electrode lines with respect to the direction of the directors of the liquid crystal molecules in the case where no voltage is applied to the liquid crystal layer, the liquid crystal layer turns the azimuthal angle of the plane of vibration of the polarized light by 90° like a half-wave plate. At this time, since the transmission axis of the exit-side polarizer conforms to the azimuthal angle of the plane of vibration of the polarized light, the polarized light going out of the exit-side polarizer forms a white image.
The IPS type LCD is advantageous in that the hue and contrast are less changed even if the viewing angle is changed, to increase an acceptable range of viewing angles (see Japanese Patent Laid-open No. Hei 5-505247).
A color-filter method is mainly used to manufacture the above-described LCDs of a full color type. In this method, a picture element equivalent to one dot of color display is divided into three parts, and three color filters equivalent to three primary colors, that is, red (R), green (G) and blue (B) are assigned to the above three divided parts of the picture element.
The present invention can be applied to the above-described various kinds of LCDs, and hereinafter, the present invention will be briefly described by example of the TN active matrix type LCD.
As described above, in a liquid crystal display element (also called liquid crystal panel) constituting part of the TN active matrix type LCD (hereinafter, referred to simply as “active matrix LCD”), a plurality of gate lines extending in an X direction and arranged in a y direction, and drain lines insulated from the gate lines, extending in the y direction and arranged in the x direction are formed on the surface, on the liquid crystal layer side, of one of two transparent insulating substrates (made from glass or the like) oppositely disposed with a liquid crystal layer put therebetween.
Each of areas enclosed by these gate lines and drain lines constitutes a picture element area in which a thin film transistor (TFT) as a switching element and a transparent picture element electrode are formed.
When a scanning signal is supplied to the gate line, the thin film transistor is turned on, and in such a state, a video signal is supplied to the picture element electrode from the drain line via the thin film transistor thus turned on.
Not only the drain lines but also the gate lines extend to the periphery of the substrate to form external terminals, and a video driver circuit and a gate scanning driver circuit, that is, a plurality of driver ICs (semiconductor integrated circuits) constituting the video driver circuit and gate scanning driver circuit are mounted at the periphery of the substrate in such a manner as to be connected to the associated external terminals. That is to say, a plurality of tape carrier packages on each of which the driver ICs are mounted are mounted at the periphery of the substrate.
In such a substrate, however, since the TCPs on each of which the driver ICs are mounted are mounted at the periphery of the substrate, the area of a region (usually called a frame border) between the display area composed of intersections between the gate lines and drain lines of the substrate and the outer edges of the substrate becomes large, so that it becomes difficult to satisfy a requirement to reduce the outer size of the liquid crystal display module in which the liquid crystal display element is integrated with an illuminating light source (backlight) and other optical components.
To solve such a problem, that is, to satisfy the requirement against high density mounting of a liquid crystal dis
Hasegawa Kaoru
Kobayashi Kengo
Toriyama Yoshio
Yarita Katsuhiko
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Nguyen Hoan
Sikes William L.
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