JP2002350615A - Assembly of diffusing member, surface light source device and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the illumination light uniform in the normal direction and in the oblique direction of a light exiting face. SOLUTION: A plurality of fluorescent lamps 3 are disposed in the back face side of the assembly of a diffusing member, a reflecting member 4 is disposed below the fluorescent lamps 3, and a diffusing sheet 5 is disposed in the exiting side (upper face side) of the assembly of the diffusing member. The assembly 2 of the diffusing member has a three-layer structure including a first layer 8 to a third layer 10, each layer composed of a plurality of diffusing member blocks. A plurality of holes 13, 16 each having a circular cross section are formed on the stacking faces of the layers, while the holes 13 shifted by a half of the pitch from the holes 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various image display devices such as a liquid crystal television, a liquid crystal monitor, a car navigation device, an advertisement display device, and the like, and an image display portion such as a liquid crystal display panel formed in a planar shape from the back side. The present invention relates to a surface light source device for illuminating, and more particularly, to a technique of arranging a light source on the back side of a diffusion member assembly constituting the surface light source device.

[0002]

2. Description of the Related Art For example, as shown in FIG. 11, a surface light source device 30 for illuminating a liquid crystal display panel of a liquid crystal monitor from the back side has a plurality of fluorescent lamps 32 arranged on the back side of a diffusion plate 31, and this fluorescent lamp 32 is provided. The light from the lamp 32 is diffused by the diffusion plate 31 and emitted as planar illumination light.

However, such a surface light source device 30 is brightest immediately above the fluorescent lamp 32, and the fluorescent lamps 32, 3
2 has the problem that the middle portion is darkest, and light emitted from the diffusion plate 31 in a planar manner is bright and dark (uneven brightness).

Therefore, conventionally, in order to make the light from the fluorescent lamp 32 as uniform as possible and emit the light from the diffusion plate 31,
A light-shielding film (light-shielding pattern) 33 is formed on the back side of the diffusion plate 31 and at a portion facing the fluorescent lamp 32 to suppress light emitted from a portion immediately above the fluorescent lamp 32.
It was designed to promote the emission of light from between the 32 spaces.

[0005]

However, in such a conventional surface light source device 30, although the luminance of the light emitted in the direction normal to the exit surface of the diffuser plate 31 can be made uniform, the diffuser plate 31 is not required. When viewed from an oblique direction with respect to the normal direction of the light exit surface, no light shielding film 33 is located between the observation position and the fluorescent lamp 32, and light from the fluorescent lamp 32 is blocked by the light shielding film 33. Instead, the light exits from the diffusion plate 31. As a result, when viewed from a direction oblique to the normal direction of the emission surface of the diffusion plate 31, there is a problem that the difference in brightness of the emitted light is emphasized and the illumination quality is reduced.

Accordingly, the present invention provides a diffusion member assembly capable of equalizing illumination light in a normal direction and an oblique direction of an emission surface, a surface light source device having the diffusion member assembly, and the surface light source. It is an object to provide an image display device provided with the device.

[0007]

According to a first aspect of the present invention, there is provided a diffusion member assembly for diffusing and emitting light from a light source disposed on a back surface side, wherein the first member comprises at least one diffusion member block. At least one of a layer and a second layer composed of one or more diffusion member blocks superimposed on the first layer, and at least one of the superposed surfaces of the first layer and the second layer. It is characterized by forming a large number of concave portions.

According to a second aspect of the present invention, there is provided a diffusion member assembly for diffusing and emitting light from a light source disposed on a back surface side,
At least a first layer made of one or more diffusion member blocks and a second layer made of one or more diffusion member blocks superimposed on the first layer, wherein the second layer of the first layer A plurality of first recesses are formed on a surface of the second layer facing the first layer, and a second recess located between the first recesses is formed on a surface of the second layer facing the first layer. It is characterized by being formed in large numbers.

According to a third aspect of the present invention, in the first or second aspect, the diffusion member block forming the first layer and the diffusion member block forming the second layer are formed in different sizes. The abutting position of each diffusion member block in the first layer and the abutting position of each diffusion member block in the second layer do not overlap with each other.

According to a fourth aspect of the present invention, there is provided a diffusion member assembly for diffusing and emitting light from a light source disposed on a back surface side,
A first layer composed of one or more diffusion member blocks, a second layer composed of one or more diffusion member blocks superimposed on the first layer, and one or more diffusion member blocks superimposed on the second layer And at least one of the overlapping surfaces of the first layer and the second layer is provided with a large number of first recesses, and the second layer and the third layer are formed. At least one of the superposed surfaces with the second layer
Are formed, and the second concave portion is arranged so as to be located between the first concave portions.

According to a fifth aspect of the present invention, there is provided a diffusion member assembly for diffusing and emitting light from a light source disposed on a back surface side,
A first layer composed of one or more diffusion member blocks, a second layer composed of one or more diffusion member blocks superimposed on the first layer, and one or more diffusion member blocks superimposed on the second layer At least a third layer made of
On the surface of the first layer facing the second layer, a large number of first concave portions having a substantially semicircular cross section are formed. A second concave portion having a substantially semicircular cross section is formed on a surface of the second layer facing the first layer and at a position corresponding to the first concave portion. A third concave portion having a substantially semicircular cross section is formed on a surface of the second layer facing the third layer so as to be located between the second concave portions. A fourth concave portion having a substantially semicircular cross section is formed on a surface of the third layer facing the second layer and at a position corresponding to the third concave portion.

According to a sixth aspect of the present invention, in the invention of the fourth or fifth aspect, the diffusion member block constituting the first layer and the diffusion member block constituting the second layer are formed to have different sizes. The abutting position of each diffusion member block of the first layer and the abutting position of each diffusion member block of the second layer do not overlap. Further, according to the present invention, the diffusion member block forming the second layer and the diffusion member block forming the third layer are formed to have different sizes, and the diffusion member blocks of the second layer are abutted. The position and the abutting position of each diffusion member block of the third layer do not overlap.

According to a seventh aspect of the present invention, in the diffusion member assembly according to any one of the first to sixth aspects, the light source is a rod-shaped fluorescent lamp, and the recess is formed linearly along the longitudinal direction of the fluorescent lamp. It is characterized by becoming.

According to an eighth aspect of the present invention, in the diffusion member assembly according to any one of the first to seventh aspects, all of the concave portions are filled with a light-transmitting substance having a refractive index different from that of the diffusion member block. It is characterized by.

According to a ninth aspect of the present invention, in the diffusion member assembly according to any one of the first to seventh aspects, a light transmitting material having a refractive index different from that of the diffusion member block is filled in a part of the plurality of concave portions. It is characterized by becoming.

According to a tenth aspect of the present invention, there is provided a surface light source device according to any one of the first to ninth aspects, wherein the light from the light source is located on the back side of the diffusion member assembly. A reflecting member that reflects the back side of the diffusion member assembly,
It is characterized by having.

According to an eleventh aspect of the present invention, in the surface light source device according to the tenth aspect, at least one diffusion sheet is disposed on an emission surface side of the diffusion member assembly.

According to a twelfth aspect of the present invention, there is provided an image display device comprising:
A surface light source device according to claim 10 or 11, and an image display unit illuminated by the surface light source device are provided.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an external perspective view of a surface light source device according to an embodiment of the present invention. Also,
FIG. 2 is an exploded perspective view of the surface light source device of FIG. Also,
FIG. 4 is a sectional view taken along line AA of FIG.

(Schematic Configuration of Surface Light Source Device and Image Display Device) As shown in these drawings, the surface light source device 1 according to the present embodiment has A plurality of rod-shaped fluorescent lamps (light sources) 3 are provided on the lower side of FIG.
Are arranged at predetermined intervals, and the reflecting member 4 is arranged below the fluorescent lamps 3. This reflection member 4
Is adapted to reflect light from the fluorescent lamp 3 to the back side of the diffusion member assembly 2. Then, a diffusion sheet 5 is arranged on the emission surface side (upper side) of the diffusion member assembly 2,
The light emitted from the diffusion member assembly 2 is diffused by the diffusion sheet 5. As shown in FIG.
An image display that illuminates the liquid crystal display panel 6 with planar light emitted from the surface light source device 1 by arranging the liquid crystal display panel (image display unit) 6 on the diffusion sheet 5 of the surface light source device 1 in an overlapping manner. The device 7 is configured.

(Diffusion Member Assembly) The diffusion member assembly has a three-layer structure from a first layer 8 to a third layer 10. The first layer 8 has a shape corresponding to the planar shape of the liquid crystal display panel 6 by combining six diffusing member blocks 8a to 8f, which are rectangular plate-like bodies, as shown in FIG. It is formed in a square plate shape. That is, the first layer 8 arranges two diffusion member blocks 8a to 8f vertically and three horizontally (a total of six in two rows and three columns), and closely contacts the side surfaces of the diffusion member blocks 8a to 8f. By doing so, it is formed in a square plate shape.

As shown in FIG. 3, the second layer 9
Fifteen diffusion member blocks 9a to 9 which are square plate-like bodies
9o is formed in a square plate shape corresponding to the planar shape of the liquid crystal display panel 6 by combining them. That is, the second layer 9 has three diffusion member blocks 9a to 9o arranged vertically and five horizontally (a total of 15 arranged in 3 rows and 5 columns), and the side surfaces of the diffusion member blocks 9a to 9o are closely arranged. By doing so, it is formed in a square plate shape. The butting positions of the respective diffusion member blocks 9a to 9o of the second layer 9 do not overlap with the butting positions of the respective diffusion member blocks 8a to 8f of the first layer 8.

The third layer 10 is formed in a rectangular plate shape corresponding to the planar shape of the liquid crystal display panel 6 by combining two diffusion member blocks 10a and 10b which are rectangular plate members. I have. That is, the third layer 10 is formed in a square plate shape by arranging two diffusion member blocks 10a and 10b side by side and bringing the side surfaces of both diffusion member blocks 10a and 10b into close contact. The butting position of the two diffusion member blocks 10a and 10b of the third layer 10 is determined by the respective diffusion member blocks 9a of the second layer 9.
-9o are not overlapped.

Here, each of the diffusion member blocks 8a to 8f, 9a to 9o, and 9a to 9o of each layer from the first layer 8 to the third layer 10 is formed.
10a to 10b are acrylic resins (P
MMA), polycarbonate (PC), cycloolefin resin, or the like, is formed into a desired shape by injection molding.

FIG. 5 is a partially enlarged view of the diffusion member assembly 2 shown in FIG. FIG. 6 is a partially enlarged view showing the diffusion member assembly 2 shown in FIG. 5 in an exploded manner into respective layers from a first layer 8 to a third layer 10.

As shown in these figures, the surfaces of the diffusion member blocks 8a to 8f of the first layer 8 facing the diffusion member blocks 9a to 9o of the second layer 9 have a substantially semicircular cross section. Many concave portions 11 are formed at regular intervals. Also, the second
The surfaces of the diffusion member blocks 9a to 9o of the first layer 8 opposed to the diffusion member blocks 8a to 8f of the first layer 8 have a substantially semicircular cross section opposed to the first recess 11 of the first layer 8. A large number of two concave portions 12 are formed at equal intervals. As a result, when the diffusion member blocks 8a to 8f of the first layer 8 and the diffusion member blocks 9a to 9o of the second layer 9 are brought into close contact with each other, the first
The concave portion 11 and the second concave portion 12 form a hole portion 13 having a substantially circular cross section.

Diffusion member blocks 9a to 9o of the second layer 9
On the surface of the third layer 10 facing the diffusion member blocks 10a and 10b, a third concave portion 14 having a substantially semicircular cross section is positioned between the second concave portions 12 and Many are formed at the same pitch P as the formation pitch. Also, the surfaces of the diffusion member blocks 10a and 10b of the third layer 10 facing the diffusion member blocks 9a to 9o of the second layer 9 have substantially a cross section facing the third concave portion 14 of the second layer 9. A large number of semicircular fourth recesses 15 are formed at equal intervals. As a result, when the diffusion member blocks 9 a to 9 o of the second layer 9 and the diffusion member blocks 10 a and 10 b of the third layer 10 are brought into close contact with each other, the cross section is formed by the third concave portion 14 and the fourth concave portion 15. A substantially circular hole 16 is formed. The pitch P between the recesses 11, 12, 14, 15 is preferably determined in the range of 2R ≦ P ≦ 4R, where R is the radius of the recesses 11, 12, 14, 15.

Here, when viewed from above the diffusion member assembly 2 (from the direction B in FIG. 4) or in an oblique direction (C and D in FIG. 4).
When viewed from the direction), a void formed in the overlapping surface of the second layer 9 and the third layer 10 is located between the void portions 13 formed in the overlapping surface of the first layer 8 and the second layer 9. The hole 16 is located (in other words, the hole 16 is shifted by a half pitch with respect to the hole 13). In the diffusion member assembly 2, air exists in the holes 13 and 16.
The diffusion member blocks (8a... 10b) and the holes 13,
16 has a large difference in the refractive index of light (for example, PMMA
Has a refractive index of about 1.49 and PC has a refractive index of 1.59.
In addition, since the cross-sectional shape of the holes 13 and 16 is substantially circular, light from the fluorescent lamp 3 is effectively diffused in the holes 13 and 16 when the light passes through the diffusion member assembly 2. You. That is, not only when the diffusion member assembly 2 is viewed from above (direction B in FIG. 4) but also when viewed obliquely from above (directions C and D in FIG. 4), the light from the fluorescent lamp 3 Since the light is uniformly diffused in the holes 13 and 16, the brightness of the emitted light is made uniform, and a difference in the brightness of the emitted light is less likely to occur.

In this embodiment, adjacent diffusion member blocks (8a to 8f, 9a to 9o, 10
When a to 10b are bonded together to be integrated, it is desirable to use an adhesive (for example, an epoxy resin-based adhesive) having a refractive index substantially the same as that of the diffusion member block (8a... 10b). .

(Reflection Member) As shown in FIGS. 1 and 2 and FIG. 4, the reflection member 4 is made of a resin material such as white polyethylene terephthalate (PET) having excellent light reflectivity, or a metal plate such as a stainless steel plate. The light from the fluorescent lamp 3 is effectively reflected to the back surface side of the light guide plate assembly 2.

(Diffusion Sheet) As shown in FIGS. 1 and 2 and FIG. 4, the diffusion sheet 5 can be used to roughen the surface of a PET sheet or the like having excellent light transmittance, Forming a light diffusion pattern with an ink having
A light diffusing substance is contained therein, so that a diffusing member assembly 2
Effectively diffuses the light emitted from the As a result, when the surface light source device 1 is viewed from the exit surface direction of the diffusion sheet 5, the first
Butting portions (divided portions from the first layer 8 to the third layer 10) of the diffusion member blocks (8a to 8f, 9a to 9o, 10a to 10b) of each layer from the layer 8 to the third layer 10 Less noticeable.

(Function / Effect of this Embodiment) In the surface light source device 1 according to this embodiment as described above, the light of the fluorescent lamp 3 is reflected directly or by the reflection member 4 and When the light enters from the lower surfaces of the diffusion member blocks 8 a to 8 f of the first layer 8, the incident light propagates through the diffusion member blocks 8 a to 8 f of the first layer 8 in the first layer 8.
And concave portions 11, 1 formed on the superposed surface of the second layer 9 and
Refraction occurs at the interface with 2 (hole 13). Here, the cross-sectional shape of the hole 13 is substantially circular, and air exists inside the hole 13, and the inside of the hole 13 and the diffusion of the first and second layers 8, 9 are diffused. Member blocks 8a-
Since the refractive index of light is largely different from that of 9o, the first layer 8
The light propagating in the diffusion member blocks 8a to 8f is uniformly diffused.

Then, the light that is not diffused and diffused by the holes 13 formed in the overlapping surface of the first layer 8 and the second layer 9 is diffused by the diffusion member blocks 9a to 9b of the second layer 9.
When the light propagates through 9o, it undergoes refraction at the interface between the concave portions 14 and 15 (hole portions 16) formed on the superposed surface of the second layer 9 and the third layer 10. Here, the holes 16 formed in the overlapping surface of the second layer 9 and the third layer 10 are:
Since the hole 13 is similar to the hole 13 formed between the first layer 8 and the second layer 9 described above, the light propagating in the second layer 9 is uniformly diffused in the hole 16. You. That is, the void portion 1 formed on the overlapping surface of the second layer 9 and the third layer 10
6 can diffuse light that could not be diffused by the holes 13 formed in the overlapping surface of the first layer 8 and the second layer 9. FIG. 10 conceptually shows a typical optical path of light diffused by the refraction at the interface with the holes 13 and 16.

Therefore, the light emitted from the diffusion member assembly 2 is oblique to the normal direction (B direction in FIG. 4) as well as the normal direction (B direction in FIG. 4). Direction). That is, in the surface light source device 1 of the present embodiment, the emitted light from the diffusion member assembly 2 does not cause uneven brightness depending on the viewing direction, and the illumination quality is improved.

The light emitted from the diffusion member assembly 2 passes through the diffusion sheet 5 and is used as illumination light for the liquid crystal display panel 6. Here, the adjacent diffusion member blocks of each layer cannot be sufficiently adhered to each other, and abnormal light emission such as generation of streak-like bright lines is observed when an optical interface exists along the boundary. However, extraordinary light emission generated at the butting portion of each of the diffusion member blocks 8a to 8f of the first layer 8 is diffused by the second layer 9, the third layer 10, and the diffusion sheet 5, and the second layer 9 Each diffusion member block 9
The extraordinary light emission generated at the butting portions a to 9o is the third layer 1
The extraordinary light which is diffused by the diffusion sheet 5 and the abutting portion between the diffusion member blocks 10a and 10b of the third layer 10 is diffused by the diffusion sheet 5 and is caused by the abutting portion of each diffusion member block 8a. The resulting abnormal light emission becomes inconspicuous. As a result, the surface light source device 1 according to the present embodiment can illuminate the liquid crystal display panel 6 with bright and uniform light, and the display on the liquid crystal display panel 6 becomes easy to see.

The surface light source device 1 according to the present embodiment
Since it is not necessary to form a light-shielding film (light-shielding pattern) as in the conventional example, light is not absorbed by the light-shielding film, and the emitted light luminance can be increased.

The surface light source device 1 according to the present embodiment
Is a multi-layer structure of the diffusion member assembly 2 into first to third layers 8 to 10, and each of the layers 8 to 10 is divided into a plurality of diffusion member blocks 8a to 8
f, 9a to 9o and 10a to 10b, the diffusion member assembly 2 can be increased by increasing the number of small diffusion member blocks 8a.
Can be easily enlarged. Therefore, according to the present embodiment, the diffusion member blocks 8a
..The size of the liquid crystal display panel 6 (the size of the display screen) is small while the mold for injection molding 10b is small.
Irrespective of this, the injection molding die of the diffusion member blocks 8a... 10b can be used in common, so that the surface light source device 1 for a large screen can be easily manufactured without increasing the size of the manufacturing equipment. .

The surface light source device 1 according to the present embodiment
Since the inside of the holes 13 and 16 of the diffusion member assembly 2 is an air layer, the overall weight can be reduced.

In the diffusion member assembly 2 according to the present embodiment, each of the layers 8 to 10 has a plurality of diffusion member blocks 8a.
10b, each diffusion member block 8a
... Since 10b is small and injection molding is easy, molding defects are unlikely to occur, and the product yield is good.

[Second Embodiment] FIG. 7 is an enlarged side view showing a part of a diffusion member assembly 2 according to a second embodiment of the present invention.

In this embodiment, as shown in FIG. 7, a large number of first concave portions 20 having a substantially semicircular cross section are formed on any one of the superposed surfaces of the first layer 8 and the second layer 9. Further, the second concave portion 21 having a substantially semicircular cross section is formed in the second layer 9 and the third layer 1.
A large number are formed on any one of the superimposed surfaces with zero. In addition, each layer of the first layer 8 to the third layer 10 is
As in the first embodiment, a plurality of diffusion member blocks 8a to 10b are combined (see FIG. 3).

That is, the first example of this embodiment is shown in FIG.
As shown in (a), a first recess 20 is formed on the surface of the first layer 8 facing the second layer 9, and a second recess 21 is formed.
Is formed on the surface of the third layer 10 facing the second layer 9, and the second recess 21 is located between the first recesses 20. (In other words, the second recess 21 is shifted by a half pitch with respect to the first recess 20).

A second example of the present embodiment is shown in FIG.
As shown in (b), a first concave portion 20 is formed on a surface of the second layer 9 facing the first layer 8, and a second concave portion 21 is formed.
Is formed on the surface of the second layer 9 facing the third layer 10, and the second concave portion 21 is located between the first concave portions 20, 20. .

A third example of this embodiment is shown in FIG.
As shown in (c), the first concave portion 20 is formed on the surface of the second layer 9 facing the first layer 8, and the second concave portion 21 is formed.
Is formed on the surface of the third layer 10 facing the second layer 9, and the second recess 21 is located between the first recesses 20. .

A fourth example of the present embodiment is shown in FIG.
As shown in (d), the first concave portion 20 is formed on the surface of the first layer 8 facing the second layer 9, and the second concave portion 21 is formed.
Is formed on the surface of the second layer 9 facing the third layer 10, and the second concave portion 21 is located between the first concave portions 20, 20. .

Also in the present embodiment having such a configuration, the light from the fluorescent lamp 3 can be diffused by the concave portions 20 and 21, and the light can be uniformly emitted from the emission surface of the diffusion member assembly 2. Therefore, it is possible to effectively prevent the occurrence of uneven brightness of the emitted light depending on the observation direction.

Also, in the present embodiment, the same effect as in the first embodiment can be obtained.

[Third Embodiment] FIG. 8 is a side view showing, on an enlarged scale, a part of a diffusion member assembly 2 according to a third embodiment of the present invention.

In the present embodiment, the diffusion member assembly 2 is
And the second layer 9 and the first layer 8 and the second layer 9.
A large number of concave portions 22 are formed on at least one of the overlapping surfaces of the layers 9. Note that the first layer 8 and the second layer 9 of the present embodiment are configured by combining a plurality of diffusion member blocks 8a to 8f and 9a to 9o as in the above-described embodiments. ing.

That is, the first example of this embodiment is shown in FIG.
As shown in (a), the concave portions 22 are formed so as to face the overlapping surface of the first layer 8 and the second layer 9. In the second example, as shown in FIG.
A large number of concave portions 22 are formed on the surface of the first layer 8 facing the second layer 9. The third example is shown in FIG.
As shown in (c), a large number of recesses 22 are formed on the surface of the second layer 9 facing the first layer 8. The concave portions 22 of the first to third examples are formed continuously with a smooth curve, and the adjacent concave portions 22 are connected to each other with a smooth curve. Therefore, the cross-sectional shape of the surface forming the concave portion 22 has a substantially corrugated shape.

In the fourth example, as shown in FIG. 8D, a large number of concave portions 22 each having a substantially semicircular cross section are formed on each superposed surface of the first layer 8 and the second layer 9. The recess 22 of the second layer 9 is located between the recesses 22 of the first layer 8.

The diffusing member assembly 2 according to the present embodiment can also diffuse the light from the fluorescent lamp in the concave portion 22, and can effectively prevent the occurrence of luminance unevenness depending on the viewing direction. .

Since the diffusion member assembly 2 according to the present embodiment has a small number of layers, the surface light source device 1 and the image display device 7 including the surface light source device 1 are made thinner and lighter. be able to.

[Other Modifications] Each of the above-described embodiments exemplifies a mode in which air exists in the recesses 11 to 12, 14 to 15, and 20 to 22. However, the present invention is not limited to this. ~ 12, 14 ~ 15, 20 ~ 22 may be filled with a light transmissive substance having a refractive index different from that of the diffusion member blocks 8a ... 10b. Also, the recess 11
The light-transmitting substance to be filled in the layers 12 to 14, 14 and 20 to 22 is a material obtained by mixing and dispersing fine particles having a different refractive index from the same or different material as the diffusion member blocks 8a to 10b. There may be. The light-transmitting substance may be filled in all of the concave portions 11 to 12, 14 to 15, and 20 to 22 or may be partially filled.

Further, in each of the above-described embodiments, the concave portions 11 to 12, 14 to 15, and 20 to 22 each having a cross-sectional shape continuously formed in a substantially semicircular shape or a smooth curve have been exemplified. Instead, any concave portion having a cross-sectional shape capable of diffusing light may be used, and a concave portion having a substantially triangular cross-section or a concave portion having another cross-sectional shape may be used.

In each of the above embodiments, the diffusion member assembly 2 is composed of three or two layers. However, the present invention is not limited to this, and the diffusion member assembly 2 may be formed of four or more layers. It may be a multilayer structure.

In each of the above embodiments, as shown in FIG. 9, the recesses 11 to 12, 14 to 15, and 20 to 22 are formed linearly along the longitudinal direction of the fluorescent lamp. However, the present invention is not limited to this, and for example, a mode in which a large number of concave portions are formed in a dot shape may be adopted.

In each of the above embodiments, the pitch at which the recesses (holes) are formed is fixed. However, the pitch at which the pitches are formed varies depending on the relative position with respect to the light source disposed on the back side. May be changed.

[0060]

As described above, according to the present invention, the diffusion member assembly for diffusing and emitting light from the light source disposed on the back side is a multilayer structure, and is formed on at least one of the superposed surfaces of the respective layers. Since the light can be evenly diffused by the recessed portion, it is possible to effectively suppress the occurrence of luminance unevenness depending on the observation direction, and it is possible to effectively suppress not only the normal direction of the emission surface but also the normal direction of the emission surface. The luminance distribution of the emitted light in the oblique direction can be made uniform, and the illumination quality can be improved.

Further, according to the present invention, since the concave portion formed on at least one of the superposed surfaces of the respective layers of the diffusion member assembly diffuses light, it is not necessary to form a light shielding pattern on the diffusion member as in the conventional example. The luminance of the emitted light can be increased by at least the amount of light not absorbed by the light shielding pattern.

Therefore, in the surface light source device provided with the diffusion member assembly according to the present invention, the illumination light for illuminating the image display unit is made uniform and the brightness is increased. As a result, in the image display device provided with such a surface light source device, the display image on the image display unit is bright and easy to see.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a surface light source device according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the surface light source device of FIG. 1;

FIG. 3 is an exploded plan view showing the diffusion member assembly according to the first embodiment of the present invention.

FIG. 4 is a sectional view taken along line AA of FIG. 1;

FIG. 5 is a partially enlarged view of the diffusion member assembly shown in FIG. 4;

FIG. 6 is an exploded partial view showing the diffusion member assembly shown in FIG. 5;

FIG. 7 is a partially enlarged view of a diffusion member assembly according to a second embodiment of the present invention.

FIG. 8 is a partially enlarged view of a diffusion member assembly according to a third embodiment of the present invention.

FIG. 9 is a perspective view showing a shape of a concave portion formed in each layer of the diffusion member assembly.

FIG. 10 is a view conceptually showing a typical optical path of light diffused by a refraction action at an interface with a hole.

FIG. 11 is an enlarged side view showing a part of a conventional surface light source device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Surface light source device, 2 ... Diffusion member assembly, 3 ... Fluorescent lamp (light source), 4 ... Reflection member, 5 ... Diffusion sheet,
6 liquid crystal display panel (image display unit), 7 image display device, 8 first layer, 9 second layer, 10 third
Layers, 8a to 8f, 9a to 9o, 10a to 10b ... diffusion member blocks, 11, 12, 14, 15, 20, 2
1,22 ... recess

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (reference) // F21Y 103: 00 F21S 1/00 E

Claims (12)

[Claims] 1. A diffusion member assembly for diffusing light from a light source disposed on a back surface side and emitting the light, wherein the first layer includes at least one diffusion member block, and is overlapped with the first layer. At least a second layer made of one or more diffusion member blocks, wherein a large number of concave portions are formed on at least one of the overlapping surfaces of the first layer and the second layer. Diffusion member assembly. 2. A diffusion member assembly for diffusing and emitting light from a light source disposed on a back surface side, wherein the first layer includes one or more diffusion member blocks, and is superimposed on the first layer. A second layer comprising at least one diffusion member block, wherein a plurality of first recesses are formed on a surface of the first layer facing the second layer; Of the first layer on the surface facing the first layer
A diffusion member assembly comprising a plurality of second concave portions formed between the concave portions. 3. A diffusion member block forming the first layer and a diffusion member block forming the second layer are formed in different sizes, and abutting positions of the diffusion member blocks of the first layer are set. 3. The diffusion member assembly according to claim 1, wherein an abutting position of each diffusion member block of the second layer does not overlap. 4. 4. A diffusion member assembly for diffusing and emitting light from a light source disposed on a back surface side, wherein the first layer includes one or more diffusion member blocks, and is overlapped with the first layer. At least a second layer made of one or more diffusion member blocks and a third layer made of one or more diffusion member blocks superimposed on the second layer, wherein the first layer and the second layer A large number of first concave portions are formed on at least one of the overlapping surfaces with
A plurality of second concave portions are formed on at least one of the overlapping surfaces of the first layer and the third layer, and the second concave portions are arranged so as to be located between the first concave portions. Diffusion member assembly. 5. A diffusion member assembly for diffusing and emitting light from a light source disposed on a back surface side, wherein the first layer includes one or more diffusion member blocks, and is superimposed on the first layer. At least a second layer made of one or more diffusion member blocks and a third layer made of one or more diffusion member blocks superimposed on the second layer, wherein the second layer of the first layer A large number of first concave portions having a substantially semicircular cross section are formed on a surface facing the first layer, and a surface of the second layer facing the first layer and at a position corresponding to the first concave portion is formed. Forming a second concave portion having a substantially semicircular cross section, and forming a third concave portion having a substantially semicircular cross section on the surface of the second layer facing the third layer so as to be located between the second concave portions. A concave portion of the third layer is formed on a surface of the third layer facing the second layer, and at a position corresponding to the third concave portion, Diffusing member assembly which is characterized by comprising forming a fourth recess surface substantially semi-circular. 6. A diffusing member block constituting the first layer and a diffusing member block constituting the second layer are formed in different sizes, and abutting positions of the respective diffusing member blocks of the first layer. And the abutting positions of the respective diffusion member blocks of the second layer do not overlap each other, and the diffusion member blocks constituting the second layer and the diffusion member blocks constituting the third layer have different sizes. 6. The abutting position of each diffusion member block of the second layer and the abutting position of each diffusion member block of the third layer are formed so as not to overlap with each other. 7. Diffusion member assembly. 7. The diffusion according to claim 1, wherein the light source is a rod-shaped fluorescent lamp, and the recess is formed linearly along a longitudinal direction of the fluorescent lamp. Member assembly. 8. The diffusion member assembly according to claim 1, wherein a light-transmitting substance having a refractive index different from that of the diffusion member block is filled in all of the concave portions. 9. The diffusion member according to claim 1, wherein a part of the plurality of recesses is filled with a light-transmitting substance having a refractive index different from that of the diffusion member block. Assembly. 10. A diffusing member assembly according to claim 1, further comprising: a light source disposed on a back side of the diffusing member assembly for transmitting light from the light source to a back side of the diffusing member assembly. A surface light source device, comprising: 11. The surface light source device according to claim 10, wherein at least one diffusion sheet is disposed on an emission surface side of the diffusion member assembly. 12. An image display device comprising: the surface light source device according to claim 10; and an image display unit illuminated by the surface light source device.