Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-03-07
2004-05-25
Dudek, James (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S155000
Reexamination Certificate
active
06741318
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display module, particularly, to a liquid crystal display module which has a large screen and whose liquid crystal display panel is made to stand during the use of the module.
2. Description of the Related Art
A liquid crystal display panel, hereinafter referred to as an “LCD panel”, is excellent in that the panel is thin, lightweight and low in power consumption. Therefore, a liquid crystal display module, hereinafter referred to as an “LCD module”, having the LCD panel incorporated therein is used in various technical fields.
To be more specific, the LCD module is used mainly for television receivers and computer monitors. In such use, a sufficient in-plane uniformity of the cell gap is realized in general by utilizing columnar spacers formed on a substrate by employing photolithographic technology in place of the granular spacers. Also, in such a use, an LCD module in which a backlight of high brightness is arranged on the back side of an LCD panel is utilized in many cases. As a matter of fact, a high brightness LCD module having a brightness equal to or higher than 300 cd/m
2
is utilized.
BRIEF SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided a liquid crystal display module, comprising a liquid crystal display panel which comprises a pair of substrates facing each other, columnar spacers formed on at least one of the substrates and configured to provide a clearance between the substrates, and a liquid crystal material filling the clearance between the substrates, and a support member supporting the panel and configured to make the panel stand during use of the module, wherein, where temperature of the panel rises from 25° C. to 50° C., the spacers keep elastically deformed by pressure applied from the substrates.
According to a second aspect of the present invention, there is provided a liquid crystal display module, comprising a liquid crystal display panel which comprises a pair of substrates facing each other, columnar spacers formed on at least one of the substrates and configured to provide a clearance between the substrates, and a liquid crystal material filling the clearance between the substrates, and a support member supporting the panel and configured to make the panel stand during use of the module, wherein the spacers are elastically deformed at 25° C. by pressure applied from the substrates, and H
0
, H
1
, &bgr; and &Dgr;D
1
satisfy a relationship represented by an inequality:
H
0
−H
1
+25×&bgr;
H
0
>&Dgr;D
1
,
where H
0
represents a height of the spacers at 25° C. under a state that the pressure is removed, H
1
represents a height of the spacers at 25° C. under a state that the pressure is applied, &bgr; represents a linear expansion coefficient of the spacers, and &Dgr;D
1
represents an increase in distance between the substrates which is calculated from an increase in volume of the liquid crystal material caused by a temperature elevation from 25° C. to 50° C.
According to a third aspect of the present invention, there is provided a liquid crystal display module, comprising a liquid crystal display panel which comprises a pair of substrates facing each other, columnar spacers formed on at least one of the substrates and configured to provide a clearance between the substrates, and a liquid crystal material filling the clearance between the substrates, and a support member supporting the panel and configured to make the panel stand during use of the module, wherein the spacers are elastically deformed at 25° C. by pressure applied from the substrates, and H
0
, H
1
and &Dgr;D
1
satisfy a relationship represented by an inequality:
H
0
−H
1
>&Dgr;D
1
,
where H
0
represents a height of the spacers at 25° C. under a state that the pressure is removed, H
1
represents a height of the spacers at 25° C. under a state that the pressure is applied, and &Dgr;D
1
represents an increase in distance between the substrates which is calculated from an increase in volume of the liquid crystal material caused by a temperature elevation from 25° C. to 50° C.
The expression that the support member is configured to make the panel stand during use of the module includes the case where the support member is configured to make the panel stand all the time and the case where the support member is configured to make the panel lowered during nonuse of the module and to make the panel stand during use of the module. The expression that the panel stands implies that the angle made between the main surface of the panel and the direction of gravity falls within a range of 0° and 45°. Further, the linear expansion coefficient of the spacer implies the linear expansion coefficient of the columnar spacers in a direction perpendicular to the substrate surface. Still further, the height of the spacers implies the height based on the surface of that portion of the substrate on which the columnar spacers are formed and which is positioned in the region contributing to the display (pixel region).
The increase &Dgr;D in distance between the substrates which is calculated from the increase in volume of the liquid crystal material, represents the value obtained under the assumption that the space (or clearance) filled with the liquid crystal material is expanded by the expansion of the liquid crystal material in only the direction perpendicular to the substrate surface (thickness direction), and that the increase &Dgr;D is equal to the increase in length in the thickness direction of the space filled with the liquid crystal material. The height H
0
can be obtained by, for example, separating one substrate from the other substrate and by measuring the height of the columnar spacers at 25° C. Further, the height H
1
can be obtained by, for example, examining the cross-sectional structure of the liquid crystal display panel and is equal to the cell gap in the case where the columnar spacers are in contact with the both substrates.
In the first aspect, it is possible for the spacers to keep elastically deformed by the pressure applied from the substrates in the case where the temperature of the panel rises from 25° C. to 70° C.
In the second aspect, it is possible for H
0
, H
1
, &bgr; and &Dgr;D
2
to satisfy a relationship represented by an inequality:
H
0
−H
1
+45×&bgr;×
H
0
>&Dgr;D
2
,
where &Dgr;D
2
represents an increase in distance between the substrates which is calculated from an increase in volume of the liquid crystal material caused by a temperature elevation from 25° C. to 70° C.
Further, in the third aspect, it is possible for H
0
, H
1
and &Dgr;D
2
to satisfy a relationship represented by an inequality:
H
0
−H
1
>&Dgr;D
2
,
where &Dgr;D
2
represents an increase in distance between the substrates which is calculated from an increase in volume of the liquid crystal material caused by a temperature elevation from 25° C. to 70° C.
It is possible for the module according to any of the first to third aspects to further comprise a light source configured to permit the panel to be irradiated with light. In this case, it is possible for the highest temperature reached by the panel by continuously lighting the light source to be equal to or lower than 50° C. or to be equal to or lower than 70° C.
According to any of the first to third aspects, it is possible for the diagonal dimension of the effective display region of the panel to be equal to or longer than 12 inches, to be equal to or longer than 17 inches, to be equal to or longer than 30 inches, or to be equal to or longer than 40 inches.
Further, according to any of the first to third aspects, it is possible for the volume expansion coefficient of the liquid crystal material to fall within a range of 0.65×10
−3
° C.
−1
to 0.85×10
−3
° C.
−1
. Also, it is possible for the cell gap at 25° C. to be smaller than 4 &mgr;m.
REFERENCES:
patent: 5699139 (1997-12-01), Aastuen et al.
Dudek James
Kabushiki Kaisha Toshiba
Kim Richard H
Pillsbury & Winthrop LLP
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