News Column

Researchers Submit Patent Application, "Liquid Crystal Display Device", for Approval

July 15, 2014



By a News Reporter-Staff News Editor at China Weekly News -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors OUGIICHI, Kimitoshi (Mobara, JP); Imayama, Hirotaka (Mobara, JP), filed on February 27, 2014, was made available online on July 3, 2014.

The patent's assignee is Panasonic Liquid Crystal Display Co., Ltd.

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a liquid crystal display device in which liquid crystal molecules are aligned by an electric field generated by two electrodes stacked via an insulating layer.

"Conventionally, liquid crystal display devices are classified into ones of a vertical electric field system and ones of a horizontal electric field system. A liquid crystal display device of the horizontal electric field system may obtain wider viewing angle characteristics compared with those of a liquid crystal display device of the vertical electric field system. Among liquid crystal display devices of the horizontal electric field system, ones in which a pixel electrode and a common electrode are stacked via an insulating layer, one of the electrodes having slits formed therein and the other of the electrodes being in the shape of an even plane without an opening, are used when high transmittance is required. This is because an arc-like electric flux is distributed to the vicinity of the center of the electrode having the slits formed therein so as to connect the pixel electrode and the common electrode which are in different layers.

"By the way, examples of the electrode having slits formed therein include a comb electrode in which one ends of the slits are closed while the other ends are open, and an electrode in which both the ends of the slits are closed. Further, in a multi-domain liquid crystal display device, such slits in the electrode are inflected. When an electric field is generated by an electrode having slits formed therein and an electrode in the shape of an even plane without an opening, an electric field in the vicinity of ends in a longitudinal direction of the slits or in the vicinity of inflected portions of the slits is distributed in such a way that control of the alignment of the liquid crystal molecules is difficult. Therefore, a region in which the alignment of the liquid crystal molecules cannot be controlled (hereinafter, referred to as domain) is generated in the vicinity of the ends in the longitudinal direction of the slits or in the vicinity of the inflected portions of the slits. The domain is responsible for lowering the transmittance in the liquid crystal display device. Accordingly, as disclosed in, for example, Japanese Patent Application Laid-open No. 2008-276172, a liquid crystal display device which reduces such a domain has been proposed."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "In the liquid crystal display device disclosed in Japanese Patent Application Laid-open No. 2008-276172, the number of ends of slits is reduced by providing the slits so as to extend continuously over a plurality of pixels. In other words, in the liquid crystal display device, the domain is reduced by reducing the number of ends of slits which are responsible for generation of the domain.

"However, in the liquid crystal display device disclosed in Japanese Patent Application Laid-open No. 2008-276172, not all the ends of slits are eliminated, and thus, the problem that a domain generated in the vicinity of ends of slits lowers the transmittance is not solved.

"The present invention has been made in view of the above, and an object of the present invention is to provide a liquid crystal display device which improves the transmittance.

"In order to solve the above-mentioned problem and to achieve the object, according to a first aspect of the present invention, there is provided a liquid crystal display device, including a pixel electrode; and a common electrode generating an electric field to align liquid crystal molecules in cooperation with the pixel electrode; and an insulating layer which is stacked between the pixel electrode and the common electrode; wherein one of the pixel electrode and the common electrode included slits formed therein, and the insulating layer is formed so as to increase in thickness from a vicinity of ends in a longitudinal direction of the slits toward the ends.

"Further, in the liquid crystal display device according to the first aspect of the present invention, the insulating layer may be formed so as to gradually increase in thickness from the vicinity of the ends in the longitudinal direction of the slits toward the ends.

"Further, in the liquid crystal display device according to the first aspect of the present invention, the insulating layer may be processed to be inclined in advance so as to increase in thickness from the vicinity of the ends in the longitudinal direction of the slits toward the ends.

"Further, in the liquid crystal display device according to the first aspect of the present invention, the vicinity of the ends in the longitudinal direction of the slits may be a domain generating region.

"Further, in order to solve the above-mentioned problem and to achieve the object, according to a second aspect of the present invention, there is provided a liquid crystal display device, including a pixel electrode; a common electrode generating an electric field to align liquid crystal molecules in cooperation with the pixel electrode; and an insulating layer which is stacked between the pixel electrode and the common electrode; wherein one of the pixel electrode and the common electrode includes slits formed therein, and the slits are inflected, and the insulating layer is formed so as to increase in thickness from a vicinity of inflected portions of the slits toward the inflected portions.

"Further, in the liquid crystal display device according to the second aspect of the present invention, the insulating layer may be formed so as to gradually increase in thickness from the vicinity of the inflected portions of the slits toward the inflected portions.

"Further, in the liquid crystal display device according to the second aspect of the present invention, the insulating layer may be processed to be inclined in advance so as to increase in thickness from the vicinity of the inflected portions of the slits toward the inflected portions.

"Further, in the liquid crystal display device according to the second aspect of the present invention, the vicinity of the inflected portions may be a domain generating region.

"Further, in order to solve the above-mentioned problem and to achieve the object, according to a third aspect of the present invention, there is provided a liquid crystal display device, including a pixel electrode; a common electrode generating an electric field to align liquid crystal molecules in cooperation with the pixel electrode; and an insulating layer which is stacked between the pixel electrode and the common electrode; wherein one of the pixel electrode and the common electrode includes slits formed therein the slits are inflected, and the insulating layer is formed so as to increase in thickness from a vicinity of ends in a longitudinal direction of the slits toward the ends and is formed so as to increase in thickness from a vicinity of inflected portions of the slits toward the inflected portions.

"Further, in the liquid crystal display device according to the third aspect of the present invention, the insulating layer may be formed so as to gradually increase in thickness from the vicinity of the ends in the longitudinal direction of the slits toward the ends and so as to gradually increase in thickness from the vicinity of the inflected portions of the slits toward the inflected portions.

"Further, in the liquid crystal display device according to the third aspect of the present invention, the insulating layer may be processed to be inclined in advance so as to increase in thickness from the vicinity of the ends in the longitudinal direction of the slits toward the ends and so as to increase in thickness from the vicinity of the inflected portions of the slits toward the inflected portions.

"Further, in the liquid crystal display device according to the third aspect of the present invention, the vicinity of the ends in the longitudinal direction of the slits and the vicinity of the inflected portions may be domain generating regions.

"Further, in the liquid crystal display device according to the present invention, the one of the pixel electrode and the common electrode including the slits formed therein may be a comb electrode, and one of the ends in the longitudinal direction of the slits may be open while another end is closed.

"Further, in the liquid crystal display device according to the present invention, the ends in the longitudinal direction of the slits may be closed.

"In the liquid crystal display device according to the present invention in which the pixel electrode and the common electrode are stacked via the insulating layer, the slits are formed in one of the pixel electrode and the common electrode, and the liquid crystal molecules are aligned by an electric field generated by the pixel electrode and the common electrode, the insulating layer is formed so as to increase in thickness from the vicinity of the ends in the longitudinal direction of the slits toward the ends, to thereby lower the intensity of the electric field in the vicinity of the ends in the longitudinal direction of the slits. Because of the lowered intensity of the electric field, the liquid crystal molecules are normally aligned around the ends in the longitudinal direction of the slits and thus suppress enlargement of a domain which is generated by the electric field in the vicinity of the ends in the longitudinal direction of the slits. Therefore, the domain reduces, and, as a consequence, the transmittance may be improved.

"Further, in the liquid crystal display device according to the present invention in which the pixel electrode and the common electrode are stacked via the insulating layer, the slits are formed in one of the pixel electrode and the common electrode, and the liquid crystal molecules are aligned by an electric field generated by the pixel electrode and the common electrode, the slits are formed so as to be inflected, and the insulating layer is formed so as to increase in thickness from the vicinity of the inflected portions of the slits toward the inflected portions, to thereby lower the intensity of the electric field in the vicinity of the inflected portions of the slits. Because of the lowered intensity of the electric field, the liquid crystal molecules are normally aligned around the inflected portions of the slits and thus suppress enlargement of a domain which is generated by the electric field in the vicinity of the inflected portions of the slits. Therefore, the domain reduces, and, as a consequence, the transmittance may be improved.

"Further, in the liquid crystal display device according to the present invention in which the pixel electrode and the common electrode are stacked via the insulating layer, the slits are formed in one of the pixel electrode and the common electrode, and the liquid crystal molecules are aligned by an electric field generated by the pixel electrode and the common electrode, the slits are formed so as to be inflected, the insulating layer is formed so as to increase in thickness from the ends in the longitudinal direction of the slits toward the ends, and the insulating layer is formed so as to increase in thickness from the vicinity of the inflected portions of the slits toward the inflected portions, to thereby lower the intensity of the electric field in the vicinity of the ends in the longitudinal direction of the slits and in the vicinity of the inflected portions. Because of the lowered intensity of the electric field, the liquid crystal molecules are normally aligned around the ends in the longitudinal direction of the slits and around the inflected portions and thus suppress enlargement of a domain which is generated by the electric field in the vicinity of the ends in the longitudinal direction of the slits and in the vicinity of the inflected portions. Therefore, the domain reduces, and, as a consequence, the transmittance may be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

"In the accompanying drawings:

"FIG. 1 is a schematic view illustrating a structure of a liquid crystal display device according to a first embodiment of the present invention;

"FIG. 2 is a detailed explanatory diagram of a structure of a liquid crystal display panel illustrated in FIG. 1;

"FIG. 3 is a cross-sectional view of the liquid crystal display panel taken along the line A1-A2 of FIG. 2;

"FIG. 4 is a detailed explanatory diagram of a structure of a liquid crystal display panel of a liquid crystal display device according to a second embodiment of the present invention;

"FIG. 5 is a cross-sectional view of the liquid crystal display panel taken along the line B1-B2-B3 of FIG. 4;

"FIG. 6 is a detailed explanatory diagram of a structure of a liquid crystal display panel of a liquid crystal display device according to a third embodiment of the present invention;

"FIG. 7 is a cross-sectional view of the liquid crystal display panel taken along the line C1-C2-C3 of FIG. 6;

"FIG. 8 is a detailed explanatory diagram of a structure of a liquid crystal display panel of a liquid crystal display device according to a fourth embodiment of the present invention; and

"FIG. 9 is a cross-sectional view of the liquid crystal display panel taken along the line D1-D2-D3 of FIG. 8."

For additional information on this patent application, see: OUGIICHI, Kimitoshi; Imayama, Hirotaka. Liquid Crystal Display Device. Filed February 27, 2014 and posted July 3, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5148&p=103&f=G&l=50&d=PG01&S1=20140626.PD.&OS=PD/20140626&RS=PD/20140626

Keywords for this news article include: Asia, Japan, Panasonic Liquid Crystal Display Co. Ltd.

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Source: China Weekly News


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