Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-06-04
2004-12-14
Flynn, Nathan J. (Department: 2826)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S096000, C349S064000, C349S095000, C359S599000, C359S615000, C359S494010, C359S506000, C359S453000, C359S490020, C359S247000
Reexamination Certificate
active
06831714
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a protective diffusion film provided on the light outgoing surface side of a lens film, and more particularly to a protective diffusion film, a process for producing the same, a surface light source device, and a liquid crystal display device, which have been improved in scratch resistance.
2. Background Art
FIG. 5
is a cross-sectional view of a liquid crystal display device
135
provided with a surface light source device
120
which is an edge-type flat light source as an example of a surface light source device using a conventional protective diffusion film.
The surface light source device
120
comprises, for example, a light source
121
, a light guide plate
122
, reflection film
124
, a light diffusive film
125
, a lens film
140
, and a protective diffusion film
110
.
The light guide plate
122
is surface light projection means, and has a light source
121
on its side end and, on its non-light-outgoing surface remote from a light outgoing surface
122
a
, a dot pattern
123
for diffusing light from the light source
121
and directing the light to a light outgoing direction. The reflection film
124
is provided on the non-light-outgoing surface side of the light guide plate
122
, and functions to block off light beams which go out to unnecessary directions and, at the same time, to reflect and return light beams to a predetermined direction.
A lens film
140
is disposed on the light outgoing surface
122
a
side of the light guide plate
122
through a diffusing plate
125
, which diffuses light to conceal the dot pattern
123
, in such a manner that the lens film
140
on its prism surface faces the light outgoing surface side.
A protective diffusion film
110
is provided on the light outgoing surface side of the lens film
140
. This protective diffusion film:
110
prevents the prism
140
a
and the liquid crystal display device
133
from coming into direct contact and being scratched with each other, for example, due to vibration in transit. The protective diffusion film
110
also has the effect of slight light diffusion for concealing stripes of the prism
140
a
in the lens film
140
, a spacer (not shown), and the like. To this end, the protective diffusion film has been formed by incorporating, in a dispersed state, organic or inorganic beads as a light diffusing agent into a transparent resin substrate, or by coating an ink containing organic or inorganic beads as a diffusing agent onto a transparent resin substrate.
A transmission liquid crystal display device
133
comprising a liquid crystal layer
130
sandwiched between a lower substrate
132
and an upper substrate
131
is provided on the light outgoing side of the surface light source device
120
, and the liquid crystal display device
133
is illuminated from backside by the surface light source device
120
.
Since, however, .the protective diffusion film
110
used in the above-described conventional device uses beads as a diffusing agent, the beads disadvantageously scratch the lens film
140
and the liquid crystal display device
133
.
Another problem of the conventional device is such that the beads separate from the film and the separated beads enter between the prisms
140
a
in the lens film
140
and thus cause a change in optical characteristics or create a shadow.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a protective diffusion film, which does not scratch a lens film and a liquid crystal display device, does not become a refuse source or the like, and also has a suitable level of concealment effect, a process for producing the same, a surface light source device, and a liquid crystal display device.
The above object of the present invention can be attained by the following means. In this connection, it should be noted that although, for facilitating the understanding of the present invention, the present invention will be described using reference characters corresponding to embodiments of the present invention, the present invention is not limited to this.
Specifically, the protective diffusion film according to the first aspect of the present invention is a protective diffusion film (
10
) for use in a surface light source device (
20
) provided with a lens film (
40
), wherein said protective diffusion film (
10
) is provided on a light outgoing surface of the lens film, said protective diffusion film (
10
) comprising:
a transparent substrate layer (
11
); and
a protective diffusion layer (
13
A,
13
B) which is provided on the transparent substrate layer in its surface at least on the lens film side, has fine concaves and convexes on its surface, protects members which come into contact with the protective diffusion film, and is light diffusive.
According to a preferred embodiment of the present invention, the protective diffusion film (
10
) has a haze of 15 to 50.
According to a preferred embodiment of the present invention, the surface of the protective diffusion layer (
13
A,
13
B) has a ten-point mean roughness Rz of 0.5 to 6 &mgr;m.
According to a preferred embodiment of the present invention, the number of profile peaks in the concaves and convexes in the protective diffusion layer (
13
A,
13
B) is 2 to 15 as measured under conditions of a reference length of 0.8 mm and a count level of ±0.1 &mgr;m.
According to a preferred embodiment of the present invention, the number of profile peaks is counted by a Pc
1
method.
According to a preferred embodiment of the present invention, the protective diffusion layer (
13
A,
13
B) contains a cured product of an ionizing radiation-curable resin (
82
).
The protective diffusion film according to the second aspect of the present invention is a protective diffusion film (
10
) for use in a surface light source device (
20
) provided with a lens film (
40
), wherein said protective diffusion film (
10
) is provided on a light outgoing surface of the lens film, said protective diffusion film comprising:
a transparent substrate layer (
11
);
a first protective diffusion layer (
13
B) which is provided on the transparent substrate layer in its surface on the lens film side, has fine concaves and convexes on its surface, protects members which come into contact with the protective diffusion film, and is light diffusive; and
a second protective diffusion layer (
13
A) which is provided on the transparent substrate layer in its side remote from the first protective diffusion layer, has fine concaves and convexes on its surface, protects members which come into contact with the protective diffusion film, and is light diffusive.
According to a preferred embodiment of the present invention, the protective diffusion film (
10
) has a haze of 15 to 50.
According to a preferred embodiment of the present invention, the surface of the first protective diffusion layer (
13
B) and/or the surface of the second protective diffusion layer (
13
A) has a ten-point mean roughness Rz of 0.5 to 6 &mgr;m.
According to a preferred embodiment of the present invention, the number of profile peaks in the concaves and convexes in the first protective diffusion layer (
13
B) or the second protective diffusion layer is 2 to 15 as measured under conditions of a reference length of 0.8 mm and a count level of ±0.1 &mgr;m.
According to a preferred embodiment of the present invention, the number of profile peaks in the concaves and convexes in the second protective diffusion layer (
13
A) or the first protective diffusion layer provided on the side opposite to the first protective diffusion layer (
13
B) or the second protective diffusion layer is 10 to 40 as measured under conditions of a reference length of 0.8 mm and a count level of ±0.1 &mgr;m.
According to a preferred embodiment of the present invention, the number of profile peaks is counted by a Pc
1
method.
According to a preferred embodiment of the present invention, the protective diffusion layer (
13
A,
13
B) contains a cured product of an i
Arakawa Fumihiro
Masaki Tadahiro
Suga Taiji
Dai Nippon Printing Co. Ltd.
Erdem Fazli
Flynn Nathan J.
Parkhurst & Wendel L.L.P.
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