Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-05-26
2003-06-24
Kim, Robert H. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S113000
Reexamination Certificate
active
06583840
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Technical Field
This invention relates to a liquid crystal display element used for liquid crystal displays, optical shutters, and the like and to a producing method thereof.
(2) Description of the Prior Art
Liquid crystal panels used for the liquid crystal display elements, offering advantages of low-profile, weight saving, low voltage drive-ability and the like, are used for watches, electronic calculators, personal computers, personal word processors and the like.
The TN (Twisted Nematic) type liquid crystal panel is typically used therefore, adopting an operation mode in which electrodes are formed on upper and lower substrates so that liquid crystals can be allowed to switch with application of a vertical electric field vertical to the substrates.
On the other hand, a horizontal electric field application mode has been proposed for expanding the viewing angle of the liquid crystal panel. The horizontal electric field application mode in which pixel electrodes and common electrodes are formed on the same substrate so that liquid crystal molecules can be allowed to operate with application of a horizontal electric field. This application mode is called the IPS (In-Plane-Switching) mode or the comb electrode operation mode (Cf. Liquid Crystal Display Technique: Sangyo Tosho p42).
Modification of the IPS mode has also been proposed, including the FFS mode (Fringe Field Switching Mode) in which the distance between the electrodes is narrowed for driving the liquid crystals and the HS mode (Hybrid Switching Mode)(see
FIG. 57
) in which the electrodes are formed on the opposing substrate side to use an oblique electric field. In these modified modes also, the horizontal electric field is generated on a plane of the substrate. Accordingly, these oblique electric field application modes are also called herein the horizontal electric field application mode.
Shown in
FIGS. 1 and 2
are structural diagrams of a conventional IPS mode of liquid crystal panel. It is supposed herein that the liquid crystal molecules as are initially aligned in parallel to common electrode parts
6
. . . (or pixel electrode parts
8
. . . ) are aligned vertically to the common electrode parts
6
. . . (or the pixel electrode parts
8
. . . ) when a voltage is applied to the common electrode parts
6
. . . and the pixel electrode parts
8
. . . . It is to be noted that the same functional members as those of the present invention described below are designated by the same reference numerals.
In the conventional horizontal electric field application mode, since the common electrode parts
6
. . . and the pixel electrode parts
8
. . . have a flat plate-like shape and a square shape in section, the horizontal electric field is not applied so much to the liquid crystal molecules on the common electrode parts
6
. . . and the pixel electrode parts
8
. . . . Due to this, the conventional horizontal electric field application mode has the problem that the liquid crystals
12
are not allowed to fully operate with application of a voltage, as shown in FIG.
3
. Also, since the common electrode parts
6
. . . and the pixel electrode parts
8
. . . of the conventional horizontal electric field application mode are formed of metal such as Al, light is not allowed to pass through the parts over the electrode parts
6
. . . and
8
. . . . Although the liquid crystal molecules over the both electrode parts
6
. . . and
8
. . . are not allowed to operate, since light does not pass through the parts over those electrodes and thus those parts are invisible, this has not been treated as the problem so far.
In consideration of these problems, the method for suppressing reflection over the electrodes in the reflective liquid crystal panel by forming the both electrode parts from transparent conducting material has been proposed (C. Japanese Patent Application Laying open No. 9(1997)-61842). However, since the horizontal electric field is not fully applied to the liquid crystal molecules over the both electrode parts, as mentioned above, the liquid crystal molecules do not operate in the horizontal direction and no effect is produced by simply making the both electrode parts transparent.
Another method has been proposed (Cf. Japanese Patent Application Laying open No. 9(1997)-171194) in which the pixel electrode parts and the common electrode parts are formed into a curved form in section. This proposal aims to provide improved rising characteristics of the liquid crystals with continuous application of the electric field. This is because the vertical electric field is so strong that the horizontal electric field cannot fully be applied to the liquid crystals. However, substantial improvement in operation of liquid crystal molecules over the both electrode parts cannot be achieved by simply forming the both electrode parts into the curved section. Also, since this proposed method has no intention of making the both electrodes transparent, improvement in aperture ratio cannot be achieved, either. In addition, this method of forming the both electrode parts themselves into the curved form in section has the additional problem of production difficulty.
Further, still another method has been proposed (Cf. Japanese Patent Application Laying open No. 8(1996)-286211) in which one of the pixel electrode parts and the common electrodes are formed into an inverted V-shape such that reflection by the surfaces of the electrodes can allow incident light to be gathered into their apertures. However, since the electrodes require light to be gathered into the apertures, the electrodes cannot be formed by the transparent electrodes. On the contrary, they are formed of high reflectivity material such as Al, Cu or the like. Because of this, improved aperture ratio cannot be produced. Besides, since the light must be entered from a direction of an apex of the V-shape, this method involves many practical problems. In addition, since the reflective surfaces of the electrodes have an inverted V-shape or an inverted U-shape in section, as shown in
FIG. 4
, the outgoing angle (&thgr;0 of
FIG. 4
) is limited to a definite range by a cone angle &agr; of the inverted V shape or inverted U shape, so that the viewing angle is narrowed. In other words, according to the liquid crystal display element mentioned above, since the reflective surface having the inverted V-shaped or inverted U-shaped section produces directed reflected light and sets limits to the viewing angle, there remains the problem that the horizontal electric field application mode (IPS) cannot fully bring out its advantage of expanding the viewing angle.
Furthermore, yet another method has been proposed (Cf. Japanese Patent Application Laying open No. 9(1997)-258265) in which the pixel electrode parts and the common electrode parts are formed on top surfaces and slant surfaces of layer insulation films. However, this proposal described clearly that the both electrode parts are not made transparent. Also, this proposal is totally silent about improvement in speed of response.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a liquid crystal display element and a producing method thereof that can be intended to produce improved display characteristics by an application of horizontal electric field to liquid crystals over electrodes to a sufficient extent.
It is another object of the present invention to provide a liquid crystal display element and a producing method thereof that can produce a bright display by improvement in aperture ratio and also increased speed of response.
Further, it is still another object of the present invention to provide a liquid crystal display element and a producing method thereof that can produce a broad viewing angle.
The above-mentioned objects can be accomplished by the present invention which provides a liquid crystal display element comprising a liquid crystal panel which comprises a pair of substrates and liquid crystals sealed off in between the pair of subst
Inoue Kazuo
Kimura Masanori
Kumagawa Katsuhiko
Shiota Akinori
Yamakita Hiroyuki
Kim Robert H.
Parkhurst & Wendel L.L.P.
Rude Timothy L.
LandOfFree
Liquid crystal display element with comb electrodes having... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid crystal display element with comb electrodes having..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid crystal display element with comb electrodes having... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3086321