Sheet for use for projection screen, light diffusion sheet and projection screen
First Claim
1. A light diffusion sheet or film, the light diffusion sheet or film having formed thereon a plurality of unit lenses, one-dimensionally or two-dimensionally, wherein the unit lens is substantially trapezoidal in cross section, a lower bottom of the trapezoid is a light incidence portion and an upper bottom thereof is a light emission portion, the unit lens is formed of a material having a prescribed refractive index of N1, and a surface of the light incidence portion has an embossed portion located thereon;
- a portion, a cross section of which is triangular and located between adjacent two of the unit lenses, is formed using a material having a refractive index N2 lower than N1 and includes light absorption particles having an average particle size of from {fraction (1/30)} to ⅔
of a height or an opening width of a groove of the light emission portion, or a material having a refractive index lower than N1 and colored; and
when it is assumed that θ
represents an angle defined by the slant of the trapezoid with respect to a normal line to the light emission portion, a relationship holds true that is expressed as sin(90°
−
θ
)>
N2/N1 and N1<
1/sin (2θ
).
1 Assignment
0 Petitions
Accused Products
Abstract
Provided is a light diffusion sheet or film capable of preventing the reflection of an external light that has entered from a light emission surface and also capable of obtaining a high gain. Also provided is a projection screen using the light diffusion sheet or film. The light diffusion sheet or film has formed thereon, either one-dimensionally or two-dimensionally, a plurality of unit lenses. The unit lens is substantially trapezoidal in cross section. The lower bottom of the trapezoid is made to be a light incidence portion and the upper bottom thereof is made to be a light emission portion. The unit lens is formed using a material having a prescribed refractive index N1. One portion, the cross section of which is triangular and located between an adjacent two of the unit lenses, is formed using a material having a refractive index N2 lower than refractive index N1 and having added thereto light absorption particles. When it is assumed that T represents the length of the upper bottom of the trapezoid; H represents the height of the upper bottom thereof; and θ represents the angle defined by the slant of the trapezoid with respect to a line normal to the light emission portion, the following relationships apply:
and the surface of the light incidence portion has performed thereon embossing processing.
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Citations
11 Claims
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1. A light diffusion sheet or film, the light diffusion sheet or film having formed thereon a plurality of unit lenses, one-dimensionally or two-dimensionally, wherein the unit lens is substantially trapezoidal in cross section, a lower bottom of the trapezoid is a light incidence portion and an upper bottom thereof is a light emission portion, the unit lens is formed of a material having a prescribed refractive index of N1, and a surface of the light incidence portion has an embossed portion located thereon;
-
a portion, a cross section of which is triangular and located between adjacent two of the unit lenses, is formed using a material having a refractive index N2 lower than N1 and includes light absorption particles having an average particle size of from {fraction (1/30)} to ⅔
of a height or an opening width of a groove of the light emission portion, or a material having a refractive index lower than N1 and colored; and
when it is assumed that θ
represents an angle defined by the slant of the trapezoid with respect to a normal line to the light emission portion, a relationship holds true that is expressed as sin(90°
−
θ
)>
N2/N1 and N1<
1/sin (2θ
).
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2. A light diffusion sheet or film, the light diffusion sheet or film having formed thereon a plurality of unit lenses, one-dimensionally or two-dimensionally, wherein the unit lens is substantially trapezoidal in cross section, a lower bottom of the trapezoid is a light incidence portion and an upper bottom thereof is a light emission portion, the unit lens is formed of a material having a prescribed refractive index of N1, and a surface of the light incidence portion has an embossed portion located thereon;
a portion, a cross section of which is triangular and located between adjacent two of the unit lenses, is formed using a material having a refractive index N2 lower than N1 and includes light absorption particles or a material having a refractive index lower than N1 and colored; and
when it is assumed that θ
represents an angle defined by the slant of the trapezoid with respect to a normal line to the light emission portion, a relationship holds true that is expressed as sin(90°
−
θ
)>
N2/N1 and N1<
1/sin (2θ
), wherein components of light are diffused 3°
or more by an embossed portion which comprises 20% or more of the light incidence surface.
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3. A light diffusion sheet or film, the light diffusion sheet or film having formed thereon a plurality of unit lenses, one-dimensionally or two-dimensionally, wherein the unit lens is substantially trapezoidal in cross section, a lower bottom of the trapezoid is a light incidence portion and an upper bottom thereof is a light emission portion, the unit lens is formed of a material having a prescribed refractive index of N1, and a surface of the light incidence portion has an embossed portion located thereon;
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portion, a cross section of which is triangular and located between adjacent two of the unit lenses, is formed using a material having a refractive index N2 lower than N1 and includes light absorption particles or a material having a refractive index lower than N1 and colored; and
when it is assumed that θ
represents an angle defined by the slant of the trapezoid with respect to a normal line to the light emission portion, a relationship holds true that is expressed as sin(90°
−
θ
)>
N2/N1 and N1<
1/sin (2θ
), wherein an area of the embossed portion comprises 20% or more of the light incidence surface, and satisfies a relationship of sin(90°
−
(sin−
1(N3*sin(2ω
)/N1)+θ
))<
N2/N1, when it is assumed that ω
represents components of an angle, in a same direction as θ
, defined by the slant of the embossed portion with respect to the light incidence surface, and N3 represents the refractive index of the material forming the embossed portion, wherein a configuration of a section, as sectioned by a plane perpendicular to the light emission portion, of the light incidence is in a shape of a chipped piece of an ellipse or/and a chipped piece of a polygon.
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4. A light diffusion sheet or film, the light diffusion sheet or film having formed thereon a plurality of unit lenses, one-dimensionally or two-dimensionally, wherein the unit lens is substantially trapezoidal in cross section, a lower bottom of the trapezoid is a light incidence portion and an upper bottom thereof is a light emission portion, the unit lens is formed of a material having a prescribed refractive index of N1, and a surface of the light incidence portion has an embossed portion located thereon;
-
a portion, a cross section of which is triangular and located between adjacent two of the unit lenses, is formed using a material having a refractive index N2 lower than N1 and includes light absorption particles or a material having a refractive index lower than N1 and colored; and
when it is assumed that θ
represents an angle defined by the slant of the trapezoid with respect to a normal line to the light emission portion, a relationship holds true that is expressed as sin(90°
−
θ
)>
N2/N1 and N1<
1/sin (2θ
), wherein components of light are diffused 20°
or more when the embossed portion comprises 20% or less of the light incidence surface.
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5. A light diffusion sheet or film, the light diffusion sheet or film having formed thereon a plurality of unit lenses, one-dimensionally or two-dimensionally, wherein the unit lens is substantially trapezoidal in cross section, a lower bottom of the trapezoid is a light incidence portion and an upper bottom thereof is a light emission portion, the unit lens is formed of a material having a prescribed refractive index of N1, and a surface of the light incidence portion has an embossed portion located thereon;
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a portion, a cross section of which is triangular and located between adjacent two of the unit lenses, is formed using a material having a refractive index N2 lower than N1 and includes light absorption particles having an average particle size of from {fraction (1/30)} to ⅔
of a height or an opening width of a groove of the light emission portion or a material having a refractive index lower than N1 and colored; and
when it is assumed that θ
represents an angle defined by the slant of the trapezoid with respect to a normal line to the light emission portion, a relationship holds true that is expressed as sin(90°
−
θ
)>
N2/N1 and N1<
1/sin (2θ
);
whereina Fresnel lens is disposed on an image light side of the light diffusion sheet or film. - View Dependent Claims (6, 7, 8)
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9. A light diffusion sheet or film, the light diffusion sheet or film having formed thereon a plurality of unit lenses, one-dimensionally or two-dimensionally, wherein the unit lens is substantially trapezoidal in cross section, a lower bottom of the trapezoid is a light incidence portion and an upper bottom thereof is a light emission portion, the unit lens is formed of a material having a prescribed refractive index of N1, and a surface of the light incidence portion has an embossed portion located thereon;
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a portion, a cross section of which includes at least three sides, located between adjacent two of the unit lenses, is formed using a material having a refractive index N2 lower than N1 and includes light absorption particles having an average particle size of from {fraction (1/30)} to ⅔
of a height or an opening width of a groove of the light emission portion, or a material having a refractive index lower than N1 and colored; and
when it is assumed that θ
represents an angle defined by the slant of the trapezoid with respect to a normal line to the light emission portion, a relationship holds true that is expressed as sin(90°
−
θ
)>
N2/N1 and N1<
1/sin (2θ
).- View Dependent Claims (10, 11)
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Specification