Illumination device and display device

Patent metadata

Field	Value
Publication number	US-9523810-B2
Application number	US-201414228519-A
Country	US
Kind code	B2
Filing date	Mar 28, 2014
Priority date	Sep 29, 2011
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

In an illumination device of the invention, as an arrangement interval of light deflection elements in a first direction discontinuously varies, an arrangement interval in a first direction becomes small with increased distance from an incidence face, where one of regions adjacent to each other which is close to the incidence face is referred to as a first region, the other of the regions which is away from the incidence face is referred to as a second region, as the arrangement interval of the light deflection elements in a second direction discontinuously varies at a boundary between the first region and the second region, the arrangement interval of part of the first region which is closest to the incidence face is smaller than the arrangement interval of part of the second region which is closest to the boundary.

First claim

What is claimed is:

1. An illumination device comprising:
a transmissive light guide body having a first main surface, a second main surface that is located on the opposite side of the first main surface, and four side end faces that connect the first main surface to the second main surface, at least one of the four side end faces being an incidence face;
a plurality of light sources that are provided in a first direction, in which the incidence face extends, so as to face the incidence face;
a plurality of light deflection elements that are independently provided on the first main surface, deflects light, which is incident to the incidence face and is introduced into the inside of the light guide body, to be directed to the second main surface, the light deflection elements being in a concave or convex scattered arrangement; and
an optical path control element that is provided on the second main surface, extends in a second direction substantially orthogonal to the first direction, and regulates an optical path of the light that is introduced into the inside of the light guide body, wherein
a density D of the light deflection elements, which represents the number of the light deflection elements being present per unit area, that increases with an increase in a distance in the second direction from the incidence face to the position at which the light deflection elements are arranged,
an arrangement pattern of the light deflection elements is separated into a plurality of regions in the second direction,
in one region, an arrangement interval of the light deflection elements in the first direction is substantially constant, an arrangement interval of the light deflection elements in the second direction varies to be small with increased distance from the incidence face,
in between the regions, as the arrangement interval of the light deflection elements in the first direction discontinuously varies, the arrangement interval in the first direction becomes small with increased distance of the region from the incidence face,
where the region which is close to the incidence face is referred to as a first region, the region which is away from the incidence face is referred to as a second region,
as the arrangement interval of the light deflection elements in the second direction discontinuously varies at the boundary between the first region and the second region, the arrangement interval of part of the first region which is closest to the boundary is smaller than the arrangement interval of part of the second region which is closest to the boundary,
regarding the density D of the light deflection elements which represents the number of the light deflection elements being present per unit area, a function of reciprocal number 1/D(y) of a density function D(y) based on a distance y from the incidence face to a position at which the light deflection elements are provided is represented by mainly summing two functions of a first function F(y) and a second function S(y),
the first function F(y) monotonically decreases with respect to the distance y, and
while the second function S(y) repeatedly decreases and increases several times with respect to the distance y, an absolute value of a maximum amplitude value of each cycle thereof monotonically decreases.

2. The illumination device according to claim 1 , wherein
a maximum value of the distance y is represented as Ymax, and
variation in differential value dF(y)/dy of the first function F(y) is less than or equal to twice the average value of the differential value dF(y)/dy in a range of 0<y/Ymax<0.9.

3. The illumination device according to claim 1 , wherein
a distance from the incidence face to a side end face that is located opposite to the incidence face is represented as L, and
a decrease-and-increase repetition period of the second function S(y) is in a range of 0.7×L/2.5 to 1.2×L/2.5.

4. The illumination device according to claim 1 , wherein
where a position at which the differential value dS(y)/dy of the second function S(y) becomes 0 is represented as yλi (i=1, 2, . . . n),
0.01× F ( yλi )<| S ( yλi )|<0.1× F ( yλi )

is satisfied.

5. The illumination device according to claim 1 , wherein
where: a maximum angle formed between the first main surface and a tangential line of a cross-sectional shape, which is obtained by cutting the light deflection element by a face that is perpendicular to the first main surface and parallel to the first direction, is represented as θd; a maximum angle formed between the first main surface and a tangential line of a cross-sectional shape by cutting the optical path control element by a face that is perpendicular to the first main surface and parallel to the first direction is represented as θL; and a refractive index of the light guide body is represented as n,
the maximum angle θL of the optical path control element satisfies the range defined by the following Formula (1)

(

Equation
⁢

⁢
1

)

Sin

-
1

⁡

(

1
n

)

-

θ
⁢

⁢
d

≤

θ
⁢

⁢
L

≤

π
2

-

2
⁢
θ
⁢

⁢
d

+

Sin

-
1

⁡

(

1
n

)

.

Form

Assignees

• Toppan Printing Co Ltd

Inventors

• Nakagome Tomohiro
• Kimura Kazuki

Classifications

• G02B6/0036 Primary

  2-D arrangement of prisms, protrusions, indentations or roughened surfaces · CPC title

• G02B6/0061

  to provide homogeneous light output intensity · CPC title

• G02B6/0053

  Prismatic sheet or layer; Brightness enhancement element, sheet or layer · CPC title

• G02B6/0033 Primary

  Means for improving the coupling-out of light from the light guide · CPC title