WO2009119870A1

WO2009119870A1 - Surface light source device and liquid crystal display device

Info

Publication number: WO2009119870A1
Application number: PCT/JP2009/056424
Authority: WO
Inventors: 森川雄市; 熊澤裕之
Original assignee: 住友化学株式会社
Priority date: 2008-03-25
Filing date: 2009-03-24
Publication date: 2009-10-01
Also published as: JP2009258707A; TW200947067A

Abstract

A surface light source device is constituted such that a plurality of light sources are arranged at an interval, a deflection structure plate (3) for deflecting light emitted from the light sources is arranged in front of the light sources, and a light diffusion sheet having a haze of 65% or more is arranged in front of the deflection structure plate, wherein the deflection structure plate (3) consists of a light transmission plate which is provided, on the light exit plane (3b), with an irregular shape portion (4) formed of a plurality of triangular protrusions (6) having a triangular cross-section, the left downward slopes (14) of the triangular protrusions (6) include a steep slope (16) having an inclination angle within a specific range and a gentle slope (17) having an inclination angle within a specific range, and the right downward slopes (15) of the triangular protrusions (6) include a steep slope (16) having an inclination angle within a specific range and a gentle slope (17) having an inclination angle within a specific range.

Description

LIGHT TEXTURE LIGHT SOURCE DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE

Technical field

The present invention relates to a surface light source device capable of emitting uniform light with less luminance unevenness and a liquid crystal display device capable of displaying an image with less luminance unevenness.

In the present invention, the “left-sloped slope” means a slope inclined obliquely downward toward the left from the apex of the triangular convex portion in a cross-sectional view of the deflection structure plate with the light exit surface up, `` Right-sloped slope '' means a slope that slopes diagonally downward from the apex of the triangular convex part to the right in the cross-sectional view of the deflection-oriented plate with the light exit surface up.

Background art

As a liquid crystal display device, for example, a configuration in which a surface light source device is disposed as a backlight on the lower surface side (back surface side) of an image display unit in which a pair of polarizing plates are disposed on both upper and lower surfaces of a liquid crystal cell is known. As the backlight surface light source device, there is known a surface light source device having a configuration in which a plurality of light sources are arranged in a lamp box and a light diffusion plate is arranged on the front side of these light sources (Japanese Patent Laid-Open No. 7). — 1 4 1 90 8 publication (see paragraphs 0 0 1 2 and Figure 1). As such a surface light source device, a device capable of uniformly illuminating the image display unit is required. Disclosure of the invention

By the way, the distance between adjacent light sources in the surface light source device is preferably set as long as possible from the viewpoint that the number of light sources can be reduced and power can be saved, and the distance between the light source and the light diffusion plate is It is preferable that the liquid crystal display device is set as short as possible in view of reducing the thickness of the liquid crystal display device.

However, in the conventional surface light source device, the interval between the light sources can be set long. Alternatively, if the distance between the light source and the light diffusing plate is set short, it is difficult to sufficiently diffuse the light from the plurality of light sources with the light diffusing plate, and this causes a problem that uneven brightness tends to occur.

The present invention has been made in view of such a technical background, and an object thereof is to provide a surface light source device that can emit uniform light with little unevenness in luminance. Another object of the present invention is to provide a liquid crystal display device capable of displaying a high-quality image with little luminance unevenness.

In order to achieve the above object, the present invention provides the following means.

[1] A plurality of light sources are spaced apart from each other, a deflection structure plate that changes the direction of light emitted from the light sources is disposed on the front side of these light sources, and light diffusion is performed on the front side of the deflection structure plate. A surface light source device in which a sheet is arranged,

^^ of the light diffusion sheet is 65% or more,

The deflection structure plate is composed of a light transmission plate having a concavo-convex shape portion formed by projecting a plurality of triangular convex portions having a triangular cross-sectional shape on the light exit surface,

When the inclination angle (acute angle) of the left slope of the triangular convex part with respect to the light incident surface is “XJ”, the slope of the left slope is α−3 ° ≤ with respect to the angle α obtained by the following equation (1). X≤ α + 3 °

3 ° XS ^ + S ^0, with respect to the steeply inclined surface where the relational expression is satisfied and the angle J3 obtained by the following equation (3)

There is a gently inclined surface where the relational expression of

When the inclination angle (acute angle) of the right slope of the triangular convex portion with respect to the light incident surface is “Y”, the slope of right slope is the angle α obtained by the following equation (1): — ά ≤ if ≥ α + 3

For a steeply inclined surface where the following relational expression holds and for the angle] 3 obtained by the following equation (3):] 3 — 3 ° ≤ Y≤ j3 + 3 °

A surface light source device characterized in that there is a slowly inclined surface where the relational expression of 'Formula (1)

(However, zo _'a is the angle that satisfies the following formula (2))

Sin (n · sin j _a ) 2 Tan 1 i ― 1 / 3—L

tan)… Formula (2) d, 8 r,

— 1 sin

D Tan 'Formula (3)

cos

(However, the angle is the angle that satisfies the following formula ( ₄₎ )

1

Sin— ¹ (n ■ sin) = Tan— ¹ (— tan j _b ) 'Equation (4)

a 8 (however, the formula (1) to formula (4), n: the refractive index of the triangular ridges, _L: distance between the centers of adjacent light sources, d: the center and the light incident surface of the deflecting structure plate of the light source Distance, t _: deflection thickness of the structural plate).

[2] The surface light source device according to [1], wherein the light diffusion sheet is an external diffusion light diffusion sheet.

[3] The surface light source device according to [1], wherein the light diffusion sheet is an internal diffusion light diffusion sheet.

[4] The surface light source device according to any one of [1] to [3], wherein two or more of the light diffusion sheets are disposed on a front side of the deflection structure plate.

[5] When the total projected area of the steeply inclined surface projected onto the light incident surface is “S a” and the total projected area of the gently inclined surface projected onto the light incident surface is “S b” , 0.9 ≤ S a / S b ≤ 3.0

The surface light source according to any one of 1 to 4 above, wherein the relational expression: apparatus.

[6] The total projected area obtained by projecting the steeply inclined surface on the left slope of the triangular convex part onto the light incident surface is “E”.

When the total value of the projected area obtained by projecting the steeply inclined surface on the right-downward slope of the triangular convex portion onto the light incident surface is “F”,

0. 9≤ E / F≤ 1. 1

And the relational expression

“G” is the total value of the projected areas obtained by projecting the gently inclined surfaces on the light-incident surface of the left-down slope of the triangular convex portion,

When the total value of the projected area obtained by projecting the gently inclined surface on the right-downward slope of the triangular convex portion onto the light incident surface is “H”,

0. 9≤G / H≤ 1. 1

The surface light source device according to any one of the preceding items 1 to 5, wherein the relational expression:

[7] The length of the inclined direction of the left-down slope of the triangular convex portion is projected onto the light incident surface, and the projected length is 10 to 500 μm, and the inclination direction of the right-down slope of the triangular convex portion 7. The surface light source device according to any one of the preceding items 1 to 6, wherein a projection length obtained by projecting the length of 1 to the light incident surface is 10 to 500 m.

[8] The surface light source device according to any one of [1] to [7], wherein the deflection structure plate includes light diffusing agent particles, and a light incident surface of the deflection structure plate is formed as a smooth surface.

[9] The surface light source device according to any one of [1] to [7], wherein a light incident surface of the deflection structure plate is formed on a mat surface.

[10] A liquid crystal display device, wherein the surface light source device according to any one of items 1 to 9 above is disposed on the back side of the liquid crystal panel.

In the invention of [1], when the angle of inclination (acute angle) of the lower left slope of the triangular convex portion provided on the light exit surface of the deflecting structure plate with respect to the light incident surface is “X”, the lower left slope is defined as the lower left slope. There is a steeply inclined surface where the relational expression 3 ° ≤Χ≤ α + 3 ° stands and a gentle inclined surface where the relational expression 3 ° ≤ X≤ i3 + 3 ° holds, and When the inclination angle (acute angle) of the right-down slope of the triangular convex part with respect to the light incident surface is “Υ”, For steep slopes where the relation of a—3 ° ≤Y≤ a + 3 ° holds as a slope, and β—3. Because there is a structure with a gently sloping surface where the relational expression ≤Υ≤ 3 + 3 ° holds, it is possible to increase the brightness in the front direction and emit uniform light with little unevenness in brightness. Can do. In addition, linear luminance unevenness is not substantially recognized. Further, since the shape of the concavo-convex shape portion is a triangular convex portion, the molding process is easy. In the present invention, as the downwardly inclined surface to the left, the one having the steeply inclined surface with the specific range of inclination angle and the specific range of the inclined angle is provided. There are those with gentle slopes, and there are steep slopes with the specific range of slope angles and gentle slope surfaces with the specific range of slope angles as the downward sloping slope. Four light source images (lamp images) are obtained. That is, four types of inclined surfaces (left-sloped steeply inclined surface, steeply-declining surface to the right, slow-sloping surface to the left, and gently-sloping surface to the right) correspond to each light source image. The present invention aims to design the arrangement (distribution) of these four light source images to be substantially uniform (substantially evenly spaced) in order to emit uniform light with little luminance unevenness. It is a thing. In this way, a and 0 are defined so that four light source images are completely evenly spaced between adjacent light sources. In addition to such a completely evenly spaced configuration, almost evenly spaced. In order to include some, the inclination angles X and Y are defined by extending the claims to the range of a ± 3 ° and j3 ± 3 °. '

Furthermore, in the present invention, since the light diffusing sheet having a haze of 65% or more is disposed on the front side of the deflecting structure plate, the brightness obtained by providing the deflecting structure plate with the characteristics described above. Can be further improved (light with less uneven brightness can be emitted).

In the invention of [2], since the external diffusion light diffusion sheet is used as the light diffusion sheet, it is possible to further improve the luminance in the substantially front direction.

In the invention of [3], since the internally diffusing light diffusing sheet is used as the light diffusing sheet, it is possible to further improve the uniformity of luminance when viewed from an oblique direction.

In the invention of [4], since two or more light diffusion sheets are arranged, the luminance is uniform. The property can be further improved.

In the invention of [5], a total value of the projected areas obtained by projecting the steeply inclined surface on the light incident surface is “S a”, and a total value of the projected areas projected on the lightly incident surface is “S b”. ”, A configuration in which the relational expression of 0.9 ≤ S a / S b ≤ 3.0 holds is adopted. In the steeply inclined surface and the gently inclined surface, the steeply inclined surface plays a role where the light quantity is relatively short of connecting the light source image at a position further away from the light source. In this invention [5], the amount of light equal to or greater than that of the gently inclined surface should be incident on the steeply inclined surface. , 0.9 ≤ S aZS b ≤ 3.0 is adopted, so that the brightness of each light source image can be made more uniform, which enables even light with less uneven brightness. Can be emitted.

In the invention of [6], the steeply inclined surface having the inclination angle in the specific range is formed in approximately the same proportion between the slope with the lower left slope and the slope with the lower right slope, and the gently inclined face with the inclination angle in the specific range is lowered to the left. Since the slope and the slope to the right are approximately the same, uneven brightness can be sufficiently suppressed.

In the invention of [7], it can be assumed that the ridges formed by the apexes of the triangular convex portions are not visually observed.

In the invention of [8], since the deflecting structure plate contains light diffusing agent particles and the light incident surface of the deflecting structure plate is formed as a smooth surface, the brightness in the substantially front direction can be further improved, and uneven brightness is also caused. It can be suppressed more sufficiently.

In the invention of [9], since the light incident surface of the deflecting structure plate is formed on the mat surface, it is possible to further improve the luminance in the substantially front direction and to sufficiently suppress the luminance unevenness.

In the invention of [10], a liquid crystal display device capable of realizing high-luminance and high-quality image display with little luminance unevenness is provided. Brief Description of Drawings

FIG. 1 is a schematic view showing an embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a perspective view showing the deflection structure plate used in FIG. FIG. 3 is a sectional view of the deflection structure plate (first embodiment) of FIG.

FIG. 4 is a cross-sectional view showing another embodiment (second embodiment) of the deflection structure plate. FIG. 5 is a sectional view showing still another embodiment (third embodiment) of the deflection structure plate.

FIG. 6 is a cross-sectional view showing still another embodiment (fourth embodiment) of the deflection structure plate.

FIG. 7 is a cross-sectional view showing still another embodiment (fifth embodiment) of the deflection structure plate.

FIG. 8 is a cross-sectional view showing still another embodiment (sixth embodiment) of the deflection structure plate.

FIG. 9 is a cross-sectional view showing still another embodiment (seventh embodiment) of the deflection structure plate.

FIG. 10 is a sectional view showing still another embodiment (eighth embodiment) of the deflection structure plate.

FIG. 11 is a cross-sectional view showing still another embodiment (a ninth embodiment) of the deflection structure plate.

Fig. 12 is a schematic plan view showing an example of four light source images (lamp images) between adjacent light sources. Explanation of symbols

1 ... Surface light source device

2 ... Light source

3 ... deflection plate

3 a… Back (light incident surface)

3 b… Front (light exit surface)

4 Uneven shape part

6… Triangle convex part

9 ... Light diffusion sheet

1 4… Left slope 1 5 ... Downhill slope

1 6… Steeply inclined surface

1… Slowly inclined surface

20 ... LCD panel

30 ... Liquid crystal display

X ... Inclination angle of the left-down slope

Y… Inclination angle of the downward slope-

Sa: Projected area obtained by projecting a steeply inclined surface onto the light incident surface

S b ... Projected area where a gently inclined surface is projected onto the light incident surface

E ... Projected area of the steeply inclined surface on the light-incident surface

F: Projected area obtained by projecting a steeply inclined surface on the light incident surface

G: Projected area of a lightly incident surface projected on a lightly inclined surface on the slope from the left

H: Projected area obtained by projecting a gently inclined surface on the light incident surface

U a: Projected length of the slanted length of the slope on the left side projected onto the light incident surface

Ub: Projected length of the slope of the right-sloped slope projected onto the light incident surface

η… Triangle convex part

L: Distance between centers of adjacent light sources

d: Distance between the center of the light source and the light incident surface of the deflection structure plate

t: Thickness of deflection structure plate (minimum value of distance between light incident surface and light emitting surface (minimum distance)) Embodiment for carrying out the invention

An embodiment of a liquid crystal display device according to the present invention is shown in FIG. In FIG. 1, (3 0) is a liquid crystal display device, (1 1) is a liquid crystal cell, (1 2) and (1 3) are polarizing plates, and (1) is a surface light source device (backlight). Polarizers (1 2) (1 3) are arranged on the upper and lower sides of the liquid crystal cell (1 1), respectively, and these constituent members (1 1) (1 2) (1 3) are used as liquid crystal as an image display unit. Panel (20) is constructed.

The surface light source device (1) is disposed on the lower surface side (back side) of the lower polarizing plate (13) of the liquid crystal panel (20). The surface light source device (1) includes a thin box-shaped lamp box (5) having a rectangular shape in plan view and an open upper surface (front surface), and the lamp A plurality of linear light sources (2) arranged in a box (5) spaced apart from each other, and a deflection structure plate (3) arranged above (front side) of the plurality of linear light sources (2) And a light diffusion sheet (9) disposed on the front side of the deflection structure plate (3). In the present embodiment, two light diffusion sheets (9) are arranged on the front side of the deflection structure plate (3). The deflection structure plate (3) is placed and fixed so as to close the open surface of the lamp box (5). In addition, a light reflecting layer (not shown) is provided on the inner surface of the lamp box (5).

As shown in FIGS. 2 and 3, the deflection structure plate (3) has a concave-convex shape portion (4) formed by projecting a plurality of triangular convex portions (6) having a triangular cross-sectional shape. (Light exit surface) (3b) A light transmitting plate provided on (3b). The other surface (light incident surface) (3 a) of the deflection structure plate (3) is formed on a flat surface. The flat surface is not particularly limited. For example, a smooth surface or a matte surface may be used. The deflecting structure plate (3) has a function of changing the direction of light incident on the light incident surface (3a) and emitting the light from the light emitting surface (3b).

A light emitting surface (4) formed with the ridge-shaped part (4) in the deflection structure plate (3)

3 b) is placed so that it is located on the front side (the LCD panel side) (see Fig. 1). That is, the surface (light incident surface) (3 a) of the deflecting structure plate (3) where the uneven portion (4) is not formed is disposed on the back side (so as to be on the light source side). (See Figure 1).

In the present embodiment, the triangular convex portion (6) is a convex portion (7) having a triangular cross-section extending along one direction parallel to the surface of the deflection structure plate (3). The plurality of protrusions (7) are formed so that their length directions are substantially parallel to each other (see FIG. 2).

In the present embodiment, a linear light source is used as the light source (2). The length direction of the linear light source (2) and the ridges (7) of the deflection structure plate (3) They are arranged so that their length directions are approximately the same.

In the present invention, the light incident surface (3 a of the lower left slope (1 4) of the triangular convex portion (6) is provided.

) When the inclination angle (acute angle) with respect to

For the angle α obtained by the following equation (1), 『3 ° ≤Χ≤α + 3 °

For a steeply inclined surface (1 6) for which the following relational expression holds, and for an angle β obtained by the following expression (3):

j3— 3 ° ≤Χ≤ + 3 °

There is a gentle slope (1 7) that satisfies the relational expression of

When the inclination angle (acute angle) of the triangular convex part (6) with respect to the right slope (1 5) with respect to the light incident surface (3 a) is “Y”, the right slope (1 5) is For the angle α found in (1),

<『3 ° ≤Υ≤ α + 3 °

For a steeply inclined surface (16) where the following relational expression holds, and for an angle determined by the following expression (3):

ー 3 ° ≤ Υ≤; 3 + 3 °

A structure with a gently sloping surface (17) that satisfies this relational expression is used. 1

Two fan one,

s ^m

'Formula (1)

os no 1 / "

(Where is an angle that satisfies the following formula (2))

m ~ n-sm z) 2 Tan ¹ _d (—-t-tan _Ja ) • Formula (2)

f ヽ

I

D Tan 'Formula (3)

cos one 1 / "So

(However, Λ is an angle that satisfies the following formula ( ₄₎ ) Sin— (71 · sin 7 ；)… Formula (4)

(Where, n is the refractive index of the triangular convex portion, L is the distance between the centers of adjacent light sources, d is the distance between the center of the light source and the light incident surface of the deflecting structure plate, in equations (1) to (4), t is the thickness of the deflection structural plate).

In the present embodiment (first embodiment), the deflection structure plate (3) has the steeply inclined surface (16) and the gently inclined surface (17) irregularly arranged on the light emitting surface (3b). A configuration that cannot be placed in is adopted (see Fig. 3).

In the surface light source device (1) according to the above configuration, four types of inclined surfaces (left-side steeply inclined surface-right-sided steeply inclined surface, left-sided gently inclined surface, and right-sided gently inclined surface) are adjacent to each other. Four light source images (lamp images) (40) can be obtained between the light sources (2). (Refer to Fig. 12). In the present invention, uniform light with less luminance unevenness can be emitted. Therefore, the arrangement (distribution) of these four light source images is designed to be substantially uniform (substantially evenly spaced), that is, four light source images (40) are placed between adjacent light sources (2). Α and are defined so that they are completely evenly spaced. Then, in addition to such a configuration that is completely evenly spaced, in order to include those that are roughly evenly spaced, for each of the tilt angle (acute angle) X and 範囲, a range of α ± 3 °,] 3 ± It is defined by extending the range to 3 °. Therefore, the surface light source device (1) can emit uniform light with little luminance unevenness toward the liquid crystal panel (20) while increasing the luminance in the substantially front direction.

Further, since the light diffusion sheet (9) is disposed on the front side of the deflection structure plate (3), the brightness obtained by the deflection structure plate (3) having the above-described configuration is uniform. The sex can be further enhanced.

In addition, the surface light source device (1) is relatively easy to produce and excellent in productivity because the shape of the concave and convex portion (4) is a triangular convex portion (6).

Further, according to the surface light source device (1), as is clear from the examples described later, the distance (L) between the centers of the adjacent light sources (2) and (2) is in the range of 10 to 7 Omm. And the distance between the center of the light source (2) and the light incident surface (3a) of the deflection structure plate (3) ( Even in a configuration in which d) is in the range of 2 to 30 mm, uniform light with little luminance unevenness can be emitted. Therefore, the surface light source device (1) of the present invention can save power because the number of light sources can be reduced as compared with the conventional surface light source device, and the light source (2) and the deflection structure plate (3) It is possible to make the device thinner even further because the interval can be designed shorter.

In the present invention, the light diffusing sheet (9) is not particularly limited. For example, an external diffusing light diffusing sheet, an internal diffusing light diffusing sheet, or an external diffusing and internal diffusing sheet. And a light diffusing sheet having both properties. Among these, it is preferable to use an externally diffusing light diffusing sheet from the viewpoint that the luminance in the substantially front direction can be further improved. Examples of the external diffusing light diffusing sheet include a light diffusing sheet provided with a light diffusing function by forming a sheet surface on a rough surface such as a mat surface. In this case, it is preferable to arrange the external diffusing light diffusing sheet so that the rough surface is located on the front side. Examples of the internally diffusive light diffusing sheet include a light diffusing sheet provided with a light diffusing function by dispersing and containing light diffusing particles (light diffusing agent) in the sheet.

Further, as the light diffusion sheet (9), one having a haze of 65% or more is used. As a result, the luminance uniformity of the surface light source device (1) can be sufficiently improved. In particular, it is particularly preferable that the ^^ size of the light diffusion sheet (9) is 75% or more. The ^^ is measured according to JIS K 7 1 3 6—2 00 0 and is a † ^ (cloudiness).

The number of light diffusion sheets (9) disposed on the front side of the deflection structure plate (3) is not particularly limited, and may be one, or may be two or more. In particular, it is preferable that two or more light diffusion sheets (9) are arranged. In this case, the luminance uniformity of the surface light source device (1) can be further improved. The upper limit of the number of light diffusing sheets (9) is usually about four.

The light diffusion sheet (9) may be disposed with a gap on the front side of the deflection structure plate (3), or may be disposed on the front side of the deflection structure plate (3). May be. Also, when two or more light diffusion sheets (9) are arranged, Adjacent light diffusing sheets (9) may be arranged with a gap between them, or may be arranged in an overlapping manner.

The thickness of the light diffusion sheet (9) is not particularly limited, but is usually in the range of 0.05 to 5 mm. Among these, those having a thickness of 0.1 to 3 mm are preferably used.

In the present invention, the deflection structure plate (3) includes a total value S a of projection areas obtained by projecting the steeply inclined surface (16) onto the light incident surface (3a), and the gently inclined surface (17). Between the total projected area S b projected onto the light incident surface (3 a)

0. 9≤ S a / S b≤ 3.0

It is preferable to adopt a configuration in which the following relational expression holds. In this case, the brightness of each light source image can be made more uniform, and thereby uniform light with less brightness unevenness can be emitted.

Further, a total value E of the projected areas obtained by projecting the steeply inclined surface (1 6) of the triangular convex portion (6) onto the light-incident surface (3 a) on the slanting left slope (14), and the triangular convex portion (6 ) Between the total projected area F of the sharply inclined surface (1 6) projected on the light incident surface (3 a),

0. 9≤ E / F≤ 1. 1

And the relational expression

A total value G of the projected areas obtained by projecting the gently inclined surface (17) on the lower left slope (14) of the triangular convex portion (6) onto the light incident surface (3a), and the triangular convex portion (6) Between the total value H of the projected area projected on the light incident surface (3 a) on the lightly inclined surface (1 7) on the slope with the lower right force S (15), 0.9 ≤ G / H ≤ 1. 1

It is preferable to adopt a configuration in which the relational expression is established. In this case, the steeply inclined surface (1 6) is formed in an approximately equal proportion between the left-sloped slope (1 4) and the right-sloped slope (1 5), and the gently sloped surface (17) Since the lower left slope (14) and the lower right slope (15) are formed at approximately the same ratio, uneven brightness can be sufficiently suppressed.

Further, the projection length (U a) obtained by projecting the length of the inclined surface of the triangular convex portion (6) in the inclined direction (14) onto the light incident surface (3 a) and the triangular convex portion (6) Projection length (U b) of the slope of the slope (1 5) on the right side of the projection onto the light incident surface (3 a)

Three Is preferably 10 to 500 μm. By setting to such a range, the ridge line by the vertex of the triangular convex part (6) is not visually observed.

Next, another specific configuration example of the deflection structure plate (3) will be described in order. That is, the structure shown in FIGS. 4 to 11 may be employed as the deflection structure plate (3).

(Second embodiment)

In the deflection structure plate (3) of the second embodiment shown in FIG. 4, the left slope (1 4) is formed by the steep slope (1 6) and the right slope (1 5) is the steep slope. Face (

1) The isosceles triangle-shaped first triangular convex part (6 A) and the lower left slope (1 4) are formed by the gentle slope (1 7) and the lower right slope ( 1 5) is an isosceles triangle shaped second triangular convex part (6 B) formed by the gently inclined surface (17), and a configuration in which one side (light emitting surface) is alternately arranged is adopted. Yes. In addition, S a = S b is established.

(Third embodiment) ''

In the deflection structure plate (3) of the third embodiment shown in FIG. 5, the left slope (1 4) is formed by the steep slope (1 6) and the right slope (1 5) is the gentle slope. Surface (

1 7) Triangular first triangular convex part (6 A) and left slope (1 4) are formed by the gentle slope (1 7) and right slope (1 5) A configuration is adopted in which the triangular second triangular ridges (6 Β) formed by the steeply inclined surfaces (16) are alternately arranged on one side (light exit surface). Further, S a = S b is established.

(Fourth embodiment)

In the deflection structure plate (3) of the fourth embodiment shown in FIG. 6, the left slope (1 4) is formed by the steep slope (1 6) and the right slope (1 5) is the steep slope. The isosceles triangle-shaped first triangular convex part (6 A) formed by the face (1 6) and the lower left slope (1 4) are formed by the gentle slope (1 7) and lower right The isosceles triangle-shaped second triangular convex part '(6 B), whose slope (15) is formed by the gently inclined surface (17), is irregularly arranged on one side (light emitting surface). The configuration is adopted. However, S a S b is established.

(Fifth embodiment)

Four In the deflection structure plate (3) of the fifth embodiment shown in FIG. 7, the left slope (14) is formed by the steep slope (16), and the right slope (15) is the steep slope. (1 6) is an isosceles triangle-shaped first triangular convex part (6A), and a lower left slope (14) is formed by the gentle slope (1 7) and a lower right slope (1 5) is an isosceles triangle shaped second triangular convex part (6B) formed by the gently inclined surface (17), and a configuration in which it is irregularly arranged on one side (light emitting surface) is adopted. ing . U a of the second triangular convex part (6 B)> U a of the first triangular convex part (6 A)> U a of the first triangular convex part (6 B)> U b of the first triangular convex part (6 A) This is a configuration where the relationship is established. Therefore, S a = S b is established.

(Sixth embodiment)

In the deflection structure plate (3) of the sixth embodiment shown in FIG. 8, the left slope (14) is formed by the steep slope (16), and the right slope (15) is the steep slope. (

1) The isosceles triangle-shaped first triangular convex part (6 A) and the lower left slope (14) are formed by the gentle slope (1 7) and the lower right slope (1 5) is an isosceles triangle shaped second triangular convex part (6 B) formed by the gently inclined surface (17) and is arranged irregularly on one side (light emitting surface). ing . For some first triangle protrusions (6 A), U a of the first triangle protrusion (6 A)> U a of the second triangle protrusion (6 B), Ub of the first triangle protrusion (6A) > This is the configuration in which the U b relation of the second triangular protrusion (6 B) is established. However, it is configured so that S a = S b holds.

(Seventh embodiment)

In the deflection structure plate (3) of the seventh embodiment shown in FIG. 9, the left slope (14) is formed by the steep slope (16) and the right slope (15) is the gentle slope. (

1 7) The triangular first triangular convex part (6 A) formed in step (7), the left slope (14) is formed by the steep slope (1 6), and the right slope (1 5) An isosceles triangular second triangular convex portion (6 B) formed by the steeply inclined surface (1 6) and a left slope (14) are formed by the gently inclined surface (17). The lower right slope (1 5) is the triangular third convex part (6 C) formed by the steep slope (1 6) and is arranged in this order from the left side on one side (light exit surface) The composition that is made

Five It has been adopted. U a of the first triangular convex part (6 A) = U a of the second triangular convex part (6 B) = U a of the third triangular convex part (6 C) = Ub of the first triangular convex part (6 A) -This is a configuration in which the relationship of U b of the second triangular convex part (6 B) = third triangular convex part (6 C) is established. However, it is configured so that S a / S b = 2.

(Eighth embodiment)

In the deflection structure plate (3) of the eighth embodiment shown in Fig. 10, the steeply inclined surface (16) and the gently inclined surface (17) are arranged randomly (irregularly) on one side (light emitting surface). The configuration is adopted. In addition, there is a steeply sloped downward slope (16) with a Ub different from Ub of the other slopes.

(Ninth embodiment).

In the deflection structure plate (3) of the ninth embodiment shown in Fig. 11, the steeply inclined surface (16) and the gently inclined surface (17) are arranged randomly (irregularly) on one side (light exit surface). The configuration is adopted. In addition, there is a steeply sloping surface (16) that has a lower left Ua that is different from Ua of the other 'inclined surface, and a steeply sloping rightward that has a Ub that is different from Ub of the other slanted surface. This is a configuration with surface (1 6).

In the present invention, the thickness (t) of the deflection structure plate (3) is not particularly limited, but is preferably set in the range of 0.1 to 10.0 mm. By setting the thickness in such a range, it is possible to further reduce the thickness while sufficiently suppressing the luminance unevenness. In particular, the thickness (t) of the deflecting structure plate (3) is more preferably set to 0.2 to 5.0 mm. The thickness (t) of the deflection structure plate (3) is the thickness of the thinnest part of the deflection structure plate (3) as shown in FIGS. The production method is not particularly limited, and examples thereof include an extrusion method, a press method, a cutting method, an injection molding method, and a method using an active energy curable resin composition. In the case of manufacturing by the extrusion method or the pressing method, for example, a deflection structure plate (3) is transferred by transferring the prism pattern to the surface of the deflection structure plate using a plate engraved with a prism pattern having a triangular cross section. ) Can be manufactured.

The deflection structure plate (3) may be a plate made of a light transmissive material. Anything can be used without particular limitation. Examples thereof include a glass substrate, an optical glass plate, a translucent resin plate, and the like. Examples of the translucent resin plate include an acrylic resin plate, a polycarbonate plate, a polystyrene plate, a cyclic polyolefin plate, an MS resin plate (methyl methacrylate-styrene copolymer resin plate), an ABS resin plate, AS resin plate (acrylonitrile monostyrene copolymer resin plate), polypropylene plate, styrene-methacrylic acid copolymer plate, styrene monomaleic anhydride copolymer plate, and the like. Among them, a light transmission plate having a refractive index of 1.45 to 1.60 is preferably used.

The deflection structure plate (3) is provided with a deflecting function for changing the direction of light by providing the light emitting surface (3b) with the concavo-convex shape portion (4) having the above characteristics. Light diffusion may be imparted to the plate itself as long as the effect is not significantly impaired. That is, for example, a light-transmitting resin such as acrylic resin, polystyrene particles that are light diffusing particles, resin particles such as silicone particles, calcium carbonate particles, barium sulfate particles, titanium oxide particles, and alumina particles. It may be a deflection structure plate formed by molding a composition containing particles, etc., or may be a deflection structure plate obtained by orientationally containing particles having refractive index anisotropy in an acrylic resin. good.

Further, the light source (2) is not particularly limited, and examples thereof include a linear light source such as a fluorescent tube, a neuron lamp, and a tungsten lamp, and a point light source such as a light emitting diode.

In the above embodiment (FIGS. 3 to 11), the triangular convex portion (6) of the deflecting structure plate (3) is a convex strip portion (7) extended along one direction parallel to the surface thereof. (One-dimensional type) (See Fig. 2) Force Not particularly limited to such a configuration. For example, the triangular protrusion (6) of the deflection structural plate (3) is parallel to the surface. It may be formed of ridges (7) extending along two different directions (for example, two directions orthogonal to each other) (that is, it may be a two-dimensional type).

In the above embodiment (FIGS. 3 to 11), the adjacent triangular protrusions (6) are configured to be continuous, but the invention is not particularly limited to such a continuous configuration. As long as the effect of the invention is not hindered, a flat surface may exist between adjacent triangular convex portions (6). In addition, as long as the effect of the present invention is not hindered, the concavo-convex shape portion (4) may have a configuration including a triangular convex portion other than the triangular convex portion (6) having the above characteristics. Good.

The surface light source device (1) and the liquid crystal display device (30) according to the present invention are not particularly limited to those of the above-described embodiment, and are within the scope of the claims, so long as they do not depart from their rigor. Any design changes are allowed. Example

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

(Light diffusion sheet A)

-^ 1z 8 9.7%, external diffusion light diffusion sheet with a thickness of 0.22 mm ("B S-042" manufactured by Eiwa Co., Ltd.)

(Light diffusion sheet B)

-^ Izu 8 9. 1%, external diffusion light diffusion sheet with a thickness of 0.205 mm (Ewa Co., Ltd. “: B S— 9 1 2”)

(Light diffusion sheet C)

-^ 1z 80.0%, Thickness 1. 85 mm Internal Diffuse Light Diffusing Sheet (For 100 parts by mass of MS resin with refractive index 1.53, refractive index 1.55, average particle size 1 2 Light diffusion sheet in which 6 parts by mass of m resin particles are dispersed)

(Light diffusion sheet D)

-^ 1z Internal diffused light diffusing sheet with a thickness of 47.9% and a thickness of 0.21 mm (ΓP B S-072 made by Eiwa Corporation)

The hazes of the light diffusion sheets A to D were measured using a HR-1 100 meter manufactured by Murakami Color Co., Ltd.

After extruding MS resin (methyl methacrylate-styrene copolymer resin: refractive index 1. 5 7) into a plate shape with an extruder, using a mold with a pattern to give a predetermined shape

8 A deflection structure plate (3) with the configuration shown in Fig. 4 was manufactured by hot pressing. That is, the tilt angle (acute angle) of the left-sloped slope (14) with respect to the light incident surface (3 a) is 66.7 1 ° (that is, the steeply sloped surface 16), and the light-incident surface (15) of the right-falling slope (15) 3 a) The light incident surface of the first triangular convex part (6A) with an isosceles triangle shape with an inclination angle (acute angle) of 66.71 ° (that is, a steeply inclined surface 16) and a left-sloped slope (14) The angle of inclination (acute angle) with respect to (3 a) is 3 7.86 ° (that is, the gently inclined surface 17), and the angle of inclination (acute angle) of the light-falling surface (1 5) with respect to the light incident surface (3 a) is 3 7. Thickness (t) of 2 mm, with the second triangular convex part (6 B) of isosceles triangle shape, which is 86 ° (ie, gently inclined surface 17), alternately arranged on one side (light exit surface) A deflection structure plate D (3) was manufactured (see Fig. 4).

In this deflection structure plate (3), the total value of the projected areas obtained by projecting the steeply inclined surface (16) onto the light incident surface (3a) is “S a”, and the gently inclined surface (17) This is a configuration in which the relational expression of S aZS b = l is established, where “S bj” is the total projected area projected onto the light incident surface (3a) (see Fig. 4).

In addition, the obtained deflection structure plate (3) is the total projected area obtained by projecting the steeply inclined surface (16) on the left-sloped slope (14) of the triangular convex part (6) onto the light incident surface (3a). Is “E”, and “F” is the total projected area of the sharply inclined surface (16) on the right slope (15) of the triangular convex part (6) projected onto the light incident surface (3a). When EZF = 1 is established, the total projected area of the lightly incident surface (3 a) projected from the lightly inclined surface (1 7) of the left-down slope (14) of the triangular convex part (6) is When “G” is assumed, and “H” is the total projected area of the lightly incident surface (3 a) projected from the lightly inclined surface (1 7) of the right-down slope (1 5) of the triangular convex part (6) , GZH = 1 holds (see Fig. 4).

In addition, in the obtained deflection structure plate (3), the projection length (U a) obtained by projecting the length of the slope of the left-down slope (14) of the triangular protrusion (6) onto the light incident surface is 30 μπι. Yes, the projection length (Ub) of the projection in the right direction slope (15) of the triangular convex part (6) projected onto the light incident surface (3a) was 3 (see Fig. 4).

Using the deflection structure plate D (3), a surface light source device (1) configured as shown in FIG. 1 was manufactured. Two light diffusion sheets A are placed on the front side of the deflecting structure plate (3), and the light source (2

9 ) Using a fluorescent tube, and setting the distance (d) between the center of the light source (2) and the light incident surface (3 a) of the deflecting structure plate to 10 mm, and the center of the adjacent light source (2) (2) The distance (L) was set to 35 mm. Therefore, in this configuration, the angle α obtained by the equation (1) is 66.71 °, and the angle obtained by the equation (3) is 37.886 ° (see Table 1). )

Examples 2-6, Comparative Examples 1-5>

A surface light source device was obtained in the same manner as in Example 1 except that various design conditions were set as shown in Table 2. The detailed structure of the deflection structure plate is shown in Table 1.

t

Investigate the arrangement (distribution) of the four light source images (40) appearing on the surface light source device constructed using each of the deflection structure plates (deflection structure plates D and E) (see Fig. 12) The distance between the four light source images (40) (that is, the distance 1 to 4) was obtained. These results Is shown in Table 1.

Moreover, the average brightness | luminance and brightness | luminance uniformity of each surface light source device of Examples 1-6 and Comparative Examples 1-5 were evaluated based on the following evaluation method. These results are shown in Table 2.

The average luminance and luminance uniformity of the surface light source device were measured using a multi-luminance meter (“Eye—Scale 3W, 4W” manufactured by I-System). In other words, each measurement spot (5 1 X 5 1 = 2 0 0 1) is specified as a measurement spot in the range of 60 mmX 6 Omm centered on the center of the front surface (light emitting surface) of the surface light source device. ), The average value of these luminances is defined as the average luminance (cd / m ² ), and among these measured luminances, the minimum luminance value is “C 1” and the maximum luminance value is “C”. 2 ”, luminance uniformity (%) = (C 1 / C 2) XI 0 0

The value obtained from the above formula was defined as the luminance uniformity.

As is apparent from Tables 1 and 2, the surface light source devices of Examples 1 to 6 of the present invention are set so that the inclination angle of the steeply inclined surface of the deflecting structural plate is in the range of α ± 3 °, and Since the tilt angle is set in the range of ± 3 °, the distance between the four light source images (spacing 1 to 4) is almost uniform, and in addition to the front side of the deflection structure plate ^ ^ Because a light diffusion sheet with a size of 65% or more is arranged, sufficiently high brightness uniformity was obtained.

On the other hand, although the inclination angle of the steeply inclined surface of the deflecting structure plate is set in the range of α ± 3 ° and the inclination angle of the gently inclined surface is set in the range of / 3 ± 3 °, the deflecting structure plate In Comparative Examples 1 and 4 in which no light diffusion sheet was disposed on the front side of the panel, sufficient brightness uniformity was not obtained. In Comparative Examples 2, 3, and 5 in which the haze of the light diffusion sheet is less than 65% even when the light diffusion sheet is disposed on the front side of the deflecting structure plate, sufficient luminance uniformity can be obtained in the same manner. There wasn't. Industrial applicability

The surface light source device of the present invention is suitably used as a pack light for a liquid crystal display device, but is not particularly limited to such applications.

Claims

[Claim 1] A plurality of light sources are arranged spaced apart from each other, a direction structure plate for changing the direction of light emitted from the light sources is disposed on the front side of these light sources, A surface light source device in which a light diffusing sheet is arranged on the front side, wherein the light diffusing sheet has a haze of 65% or more, and the deflection structure plate has a plurality of triangular protrusions having a triangular cross-sectional shape. The uneven portion formed is a light transmission plate provided on the light exit surface, and when the inclination angle (acute angle) of the lower left slope of the triangular convex portion with respect to the light incident surface is “X”, the left The falling slope is a steep slope where the relation of α—3 ° ≤Χ≤ α + 3 ° holds with respect to the angle α determined by the following equation (1), and is determined by the following equation (3): For the angle to be — 3. There is a gently inclined surface where the relation of X≤ iS + 3 ° holds, and when 'Y' is the inclination angle (acute angle) with respect to the light incident surface of the lower right slope of the triangular convex part, The right-downward slope is a steep slope where the relation of α—3 ° ≤Υ≤ α + 3 ° holds with respect to the angle α obtained by the following equation (1), and the following equation (3) A surface light source device characterized by the existence of a slightly inclined surface that satisfies the relational expression of J3—3 ° Y≤ j3 + 3 ° with respect to the angle obtained in (1). f ヽ a― Tan I j 'Equation (υ cos (where n is an angle that satisfies Eq. (2) below) Sin—1 (n · sin ja) 2 ja)' Equation (2) ヽ I 1 sin β-Tan 'Equation (3) cos ^ — 1 / w J (However, this is the angle that satisfies the following equation (4)) Sm—! (n 'sin jb) tan jb) -Equation (4)

(However, in Equations (1) to (4), n is the refractive index of the convex portion of the triangle, L is the distance between the centers of the adjacent light sources, and d. 'The distance between the center of the light source and the light incident surface of the deflection structure plate) T is the thickness of the deflection structural plate)

[Claim 2]

2. The surface light source device according to claim 1, wherein the light diffusion sheet is an external diffusion light diffusion sheet.

[Claim 3]

2. The surface light source device according to claim 1, wherein the light diffusion sheet is an internal diffusion light diffusion sheet.

[Claim 4]

The surface light source device according to any one of claims 1 to 3, wherein two or more of the light diffusion sheets are disposed on a front surface side of the deflection structure plate.

[Claim 5] When the total projected area of the steeply inclined surface projected onto the light incident surface is “S a” and the total projected area of the gently inclined surface projected onto the light incident surface is “S b”,

0. 9≤ S a / S b≤ 3.0

The surface light source device according to claim 1, wherein the following relational expression is satisfied.

[Claim 6]

“E” is the total value of the projected areas obtained by projecting the steeply inclined surface on the light-incident surface of the left-down slope of the triangular convex portion,

0. 9≤ E / F≤ 1. 1

And the relational expression

0. 9≤G / H≤ 1. 1

The surface light source device according to claim 1, wherein the relational expression:

[Claim 7]

The projected length obtained by projecting the length of the slope of the lower left slope of the triangular convex portion onto the light incident surface is 10 to 500 _μm , and the length of the slope of the right downward slope of the triangular convex portion is The surface light source device according to any one of claims 1 to 6, wherein a projection length obtained by projecting the light onto a light incident surface is 10 to 500 μm.

[Claim 8]

The deflection structure plate contains light diffusing agent particles, and the light incident surface of the deflection structure plate is a smooth surface. The surface light source device of any one of Claims 1-7 currently formed in.

[Claim 9]

The surface light source device according to claim 1, wherein a light incident surface of the deflection structure plate is formed on a mat surface.

[Claim 1 0]

10. A liquid crystal display device, wherein the surface light source device according to claim 1 is disposed on the back side of the liquid crystal panel.