Spherical laminated particle and liquid crystal display

Details Spherical laminated particle and liquid crystal display Spherical laminated particle and liquid crystal display

1999-08-27

2001-09-25

Thomas, Alexander S. (Department: 1772)

Stock material or miscellaneous articles

Liquid crystal optical display having layer of specified...

With bonding or intermediate layer of specified composition

C428S405000, C349S155000

Reexamination Certificate

active

06294230

ABSTRACT:

TECHNICAL FIELD
The present invention relates to spherical laminated particles having a specified compressive modulus and a liquid crystal display having the spherical laminated particles interposed as spacers between liquid crystal cell electrodes thereof.
BACKGROUND ART
Spacers are interposed between a pair of electrodes disposed in a liquid crystal cell of liquid crystal display and a liquid crystal substance is sealed in a space surrounded with the electrodes and spacers to thereby form a liquid crystal layer. When the thickness of this liquid crystal layer is not uniform, the image displayed on the liquid crystal cell becomes mottled and causes lighting-time contrast degradation. Therefore, the uniformity of the thickness of liquid layer inside the liquid crystal cell is desirable. Further, the uniformity of the thickness of the liquid crystal layer inside the liquid crystal cell is also required, when the displayed image is changed over at a high speed or when an image of large viewing angle is displayed.
Still further, for realizing a large-scope display free from mottles on the currently employed large-scope liquid crystal display device of STN mode, it is required in greater degree to uniformalize the thickness of the liquid crystal layer inside the liquid crystal cell.
It is common practice to interpose, in sparsely dispersed form, spherical particles of uniform size between electrodes of the liquid crystal cell, namely to employ spherical particles as interelectrode spacers of the liquid crystal cell, for uniformalizing the thickness of the liquid crystal layer inside the liquid crystal cell. Particles of an organic resin such as polystyrene and fine particles of silica are used as such spherical particles.
However, the use of organic resin particles such as polystyrene particles as the interelectrode spacers of the liquid crystal cell invites the problem that the organic resin particles are too soft to maintain the uniformity of the thickness of the liquid crystal layer inside the liquid crystal cell. For example, if nonuniform pressure is applied to the liquid crystal layer inside the liquid crystal cell, the spacers are deformed in accordance with the nonuniformity of the pressure to thereby disenable maintaining the uniformity of the thickness of the liquid crystal layer inside the liquid crystal cell.
On the other hand, when fine particles of silica are used as the interelectrode spacers of the liquid crystal cell, unsharpness of particle-size distribution of silica fine particles invites the problem that the thickness of the liquid crystal layer inside the liquid crystal cell is rendered nonuniform because of the smallness of the compressive deformation of the silica fine particles. Furthermore, when the liquid crystal display is exposed to low temperatures with void formation, namely low-temperature bubbling, another problem occurs between the liquid crystal layer and the electrode of the liquid crystal cell, because the thermal expansion coefficient of the liquid crystal layer is different from that of the spacers.
Consequently, for solving the above problems, various proposals have been made which comprise using fine particles having appropriate elasticity and mechanical recovery as the spacers.
For example, it has been proposed to employ fine particles composed mainly of an organic resin such as a vinyl plastic or a hybrid of inorganic material and organic material (see Japanese Patent Laid-open Publication No. 4(1992)-313727 and Japanese Patent Laid-open Publication No. 5(1993)-80343) and to employ fine particles of a hydrolyzate of an organosilicon compound such as tetraethoxysilane (see Japanese Patent Laid-open Publication No. 6(1994)-250193 and Japanese Patent Laid-open Publication No. 7(1995)-80343).
However, these fine particles are unsatisfactory as the interelectrode spacers of the liquid crystal cell because, when nonuniform load is applied to the liquid crystal layer, the particles are deformed in accordance with the nonuniformity of the load to thereby disenable maintaining the uniformity of the thickness of the liquid crystal layer.
OBJECT OF THE INVENTION
The present invention has been made with a view toward solving the problems encountered when the above conventional elastic particles are used as the spacers. It is the object of the present invention to provide spherical laminated particles each comprising a core particle having a specified compressive modulus and a laminate part disposed on a surface of the core particle, the laminate part having a compressive modulus which is smaller than that of the core particle, and to provide a liquid crystal display having the spherical laminated particles interposed as spacers.
SUMMARY OF THE INVENTION
The spherical laminated particles of the present invention are those each comprising a core particle and a laminate part disposed on a surface of the core particle,
wherein the laminate part has a compressive modulus which is smaller than that of the core particle.
With respect to these spherical laminated particles, it is preferred that the compressive modulus of the core particle be in the range of 200 to 6000 kg/mm
2
, and the compressive modulus of the spherical laminated particles be in the range of 50 to 1000 kg/mm
2
.
Further, with respect to these spherical laminated particles, it is preferred that the compressive modulus of the core particle be in the range of 200 to 6000 kg/mm
2
, and the compressive modulus of the laminate part be in the range of 50 to 1000 kg/mm
2
.
This core particle is preferably composed of a polysiloxane obtained by hydrolyzing an organosilicon compound represented by the following formula (I) and/or formula (II):
 Si(OR
1
)
4
  (I)
R
2
Si(OR
3
)
3
  (II)
wherein each of R
1
and R
3
represents a hydrogen atom or an organic group having 1 to 10 carbon atoms selected from among alkyl, alkoxyalkyl and acyl groups; and R
2
represents a group having 1 to 10 carbon atoms selected from among substituted or unsubstituted hydrocarbon groups.
It is especially preferred that the core particle be composed of a polysiloxane obtained by subjecting a mixture of an organosilicon compound represented by the above formula (I) and/or formula (II) and a silicic acid solution to hydrolysis and polymerization.
The laminate part is preferably composed of a hydrolyzate of one member or a mixture of at least two members selected from among compounds represented by the following formulae (II) to (IV):
wherein each of R
2
and R
3
is as defined above; each of R
4
and R
5
represents a group having 1 to 10 carbon atoms selected from among substituted or unsubstituted hydrocarbon groups; R
6
represents a hydrogen atom or an organic group having 1 to 10 carbon atoms selected from among alkyl, alkoxyalkyl and acyl groups; R
7
represents a propyl group or a butyl group; Y represents an organic group selected from among methyl, methoxy and ethoxy groups; M represents an element selected from among those of the Groups 2 to 15 of the periodic table; and m is an integer of 0 to 3 and n an integer of 1 to 4 provided that m+n is an integer of 2 to 4.
The liquid crystal display of the present invention comprises a liquid crystal cell fitted with a pair of electrodes between which the above spherical laminated particles of the present invention are interposed as spacers.


REFERENCES:
patent: 5231527 (1993-07-01), Takanashi et al.
patent: 2-022625 (1990-01-01), None
patent: 4-313727 (1992-11-01), None
patent: 5-080343 (1993-04-01), None
patent: 6-010928 (1994-02-01), None
patent: 06160866 (1994-06-01), None
patent: 6-160866 (1994-06-01), None
patent: 06250193 (1994-09-01), None
patent: 6-250193 (1994-09-01), None
patent: 7-080343 (1995-03-01), None
patent: 7-095165 (1995-10-01), None
patent: WO9206402 (1992-04-01), None

Affiliated with

Also associated with

Rating

Spherical laminated particle and liquid crystal display does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Spherical laminated particle and liquid crystal display, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spherical laminated particle and liquid crystal display will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2447757