KR100835155B1 - Light diffusion member assembly, surface light source device and image display apparatus - Google Patents

Abstract

The surface light source device 1 includes a plurality of fluorescent lamps 3 and a reflecting member 4 on the back side of the light diffusing member assembly 2, and a diffusion sheet 5 is arranged on the exit side. The light diffusing member assembly 2 has a three-layer structure, and each layer is composed of a plurality of diffusing member blocks 8a ... 8f, 9a ... 9o, 10a, 10b. Most of the light incident on the diffusion member block 8a and the like of the first layer 8 has concave portions 11 and 12 having substantially circular cross-sections formed on the overlapping surfaces of the first and second layers 8 and 9 in the propagation process. The refraction is effected by entering and exiting the hole 13), and the traveling direction is diversified to diffuse almost uniformly. Similarly, the concave portions 14 and 15 (hole portions 16 formed on the overlapping surface of the second layer 9 and the third layer 10 are also refracted and diffuse almost uniformly. Uniformity of brightness can be obtained not only in the normal direction (B direction) of the exit surface of the light diffusing member assembly 2 but also in the inclined directions (C, D direction). Since a light shielding film is unnecessary, the utilization efficiency of light is also high.

Surface light source device, diffuser block, recess

Description

Light diffuser assembly, surface light source device and image display device {LIGHT DIFFUSION MEMBER ASSEMBLY, SURFACE LIGHT SOURCE DEVICE AND IMAGE DISPLAY APPARATUS}

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 of the surface light source device shown in FIG. 1.

3 is an exploded plan view showing the light diffusing member assembly employed in the first embodiment of the present invention.

4 is a cross-sectional view along the line A-A in FIG.

FIG. 5 is a partially enlarged view of the light diffusing member assembly shown in FIG. 4. FIG.

FIG. 6 is a partially enlarged view illustrating an exploded view of the light diffusing member assembly shown in FIG. 5.

7 is a partially enlarged view showing four examples (a) to (d) of the light diffusing member assembly employed in the second embodiment of the present invention.

8 is a partially enlarged view of the light diffusing member assembly employed in the third embodiment of the present invention.

9 is a perspective view showing the shape of a recess formed in each layer of the light diffusing member assembly.

FIG. 10 is a diagram conceptually illustrating a representative optical path of light diffused by refraction at an interface with a hole. FIG.

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

* Description of the main parts of the drawings

1: surface light source device

2: light diffusing member assembly

3: fluorescent lamp (primary light source)

4: reflection member

5: Diffusion Sheet

6: LCD panel (image display unit)

7: image display device

8: first layer

9: the second layer

10: third layer

8a to 8f, 9a to 9o, 10a to 10b: diffusion member block

11, 12, 14, 15, 20, 21, 22: recess

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various image display devices such as liquid crystal televisions, liquid crystal monitors, car navigation systems, advertisement display devices, and surface light source devices for backlighting these image display units. The invention also relates to a light diffusing member assembly employed therein.

A surface light source device used for backlighting (illuminated from the back side, which is the same below) of an image display unit such as a liquid crystal display panel of a liquid crystal monitor is known of the type shown in FIG. Referring to FIG. 11, the surface light source device 30 includes a diffusion plate 31, and a plurality of fluorescent lamps 32 are disposed on the rear surface side thereof. Light from the fluorescent lamp 32 is diffused in the diffuser plate 31 to produce planar illumination light.

In general, in such a surface light source device 30, the luminance is increased directly above the fluorescent lamp 32, while the luminance is dropped at the middle portions of the fluorescent lamps 32 and 32, so that the illumination light from the diffuser plate 31 Luminance deviation) occurs.

In order to overcome this disadvantage, conventionally, a light shielding film (light shielding pattern) 33 is formed on the rear surface side of the diffuser plate 31 and in a portion opposite to the fluorescent lamp 32, and directly above the fluorescent lamp 32. By suppressing the light emitted from the light, the balance of luminance was obtained between the middle portions of the fluorescent lamps 32 and 32.

However, in such a conventional method, the luminance of the emitted light in the normal direction of the diffuser plate 31 exit surface is possible, but when viewed from the direction inclined with respect to the normal direction, between the observation position and the fluorescent lamp 32 The light shielding film 33 is not located at this position, and the light from the fluorescent lamp 32 enters the eye without being shielded by the light shielding film 33. As a result, when viewed from the direction inclined with respect to this normal direction, there existed a problem that the light quality difference was emphasized because the contrast difference of the emitted light was emphasized.

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

The present invention is first applied to a light diffusing member assembly that diffuses and emits light from a light source arranged on the rear surface side.

According to a basic feature of the invention, the light diffusing member assembly has at least a first layer and a second layer. The first layer includes at least one diffusion member block, and the second layer includes at least one diffusion member block overlapping the first layer, and the first layer and the second layer. Many recesses are formed in at least one of the overlapping surface of the surface.

About formation of a recessed part, many 1st recessed parts are formed in the surface which opposes the said 2nd layer of a said 1st layer, and the surface which opposes the said 1st layer of a said 2nd layer is between said 1st recessed parts. Many 2nd recessed parts may be formed so that it may be located.

Here, the diffusion member block constituting the first layer and the diffusion member block constituting the second layer are formed in different sizes, and the contact position of each diffusion member block of the first layer and the second layer are different. It is preferable that the abutting positions of the respective diffusion member blocks of do not overlap.

The light diffusing member assembly may be composed of three or more layers. In that case, the light diffusing member assembly has at least a first layer, a second layer, and a third layer, wherein the first layer is composed of at least one diffusion member block, and the second layer is the first layer. At least one diffusion member block overlapping the second layer, the third layer is composed of at least one diffusion member block overlapping the second layer. A plurality of first recesses are formed in at least one of the overlapping surfaces of the first layer and the second layer, and a plurality of second recesses are formed in at least one of the overlapping surfaces of the second layer and the third layer. In this case, the second concave portion is located between the first concave portion.

Or in the light-diffusion member assembly of the same 3-layered constitution, in the surface which opposes the said 2nd layer of the said 1st layer, many 1st recessed parts which are substantially semicircular in cross section are formed, and the said 1st of the said 2nd layer On the surface facing the layer, a second recess having a semicircular cross section is formed at a position corresponding to the first recess, and the second recess is formed on the surface facing the third layer of the second layer. A third concave portion having a substantially semicircular cross section is formed so as to be located therebetween, and a fourth concave portion having a substantially semi-circular cross section at a position corresponding to the third concave portion on a surface of the third layer facing the second layer. You may form.

In these three-layer light diffusing member assemblies, the diffusing member blocks constituting the first layer and the diffusing member blocks constituting the second layer are formed to have different sizes, so that each of the diffusing member blocks of the first layer is formed. While the abutment position and the abutment position of each of the diffusion member blocks of the second layer do not overlap, the diffusion member block constituting the second layer and the diffusion member block constituting the third layer are formed in different sizes. It is preferable to form such that the contact position of each diffusion member block of the second layer and the contact position of each diffusion member block of the third layer do not overlap.                         

In all the above-mentioned light diffusing member assemblies, the light source may be a rod-shaped fluorescent lamp. In this case, it is preferable that the recess is formed in a linear shape along the longitudinal direction of the fluorescent lamp.

In addition, the light transmitting material having a refractive index different from that of the diffusion member block may be filled in all or part of the recess.

Next, the present invention is applied to a surface light source device and an image display device. According to an aspect of the present invention, there is provided a surface light source device including an improved light diffusing member assembly and a reflecting member positioned on a rear surface side of the light diffusing member assembly to reflect light from the light source to a rear surface side of the light diffusing member assembly. Equipped with. Therefore, it is preferable that at least one diffusion sheet is arranged on the emission surface side of the light diffusing member assembly.

In addition, the image display device according to the present invention is constructed by combining the surface light source device configured in this way and an image display portion to which illumination light output from the surface light source device is supplied.

As described above, the features of the light diffusing member assemblies of all aspects, the surface light source device and the image display device using the same, will be described in more detail in the following embodiments.

Embodiment

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail with reference to drawings.

[First embodiment]

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 of the surface light source device shown in FIG. 1. 4 is sectional drawing along the line A-A line in FIG.

(Schematic Configuration of Surface Light Source Device and Image Display Device)

As shown in these figures, the surface light source device 1 according to the present embodiment has a plurality of light diffusing member assemblies 2 and a rear surface side (the lower surface side in FIGS. 1, 2 and 4). Rod-shaped fluorescent lamps (primary light source; 3), reflecting members 4 disposed below these fluorescent lamps 3, and arranged on the emitting side (upper side) of the light diffusing member assembly 2; The diffusion sheet 5 is provided.

The fluorescent lamps 3 are arranged in plural at predetermined intervals. The reflecting member 4 reflects the light from the fluorescent lamp 3 toward the rear surface side of the light diffusing member assembly 2. The diffusion sheet 5 diffuses the light emitted from the light diffusing member assembly 2. As shown in Fig. 4, the image display device 7 which is illuminated from the surface light source device 1 onto the surface is arranged by overlapping the image display portion (here, liquid crystal display panel; 6) on the diffusion sheet 5. do.

(Light diffusing member assembly)

The light diffusing member assembly 2 has a three-layer structure from the first layer 8 to the third layer 10. As shown in Fig. 3, the first layer 8 is formed by combining six rectangular plate-shaped diffusion member blocks 8a to 8f to form a rectangular plate shape having a size substantially corresponding to the planar shape of the liquid crystal display panel 6. It is formed. The diffusion member blocks 8a to 8f are arranged in two vertically and three horizontally (6 total of 2 rows and 3 columns). Side surfaces of each of the diffusion member blocks 8a to 8f are in close contact with each other.

Next, as shown in FIG. 3, the 2nd layer 9 combines 15 square plate-shaped diffuser member blocks 9a-9o, and the square of the magnitude | size corresponding substantially to the planar shape of the liquid crystal display panel 6 It is formed in plate shape. Three diffusion member blocks 9a to 9o are arranged vertically and five are arranged horizontally (15 in total of 3 rows and 5 columns). Side surfaces of each of the diffusion member blocks 9a to 9o are in close contact with each other.

The abutment positions (boundaries between adjacent diffusion member blocks; the same below) of each of the diffusion member blocks 9a to 9o of the second layer 9 are each of the diffusion member blocks 8a to 1 of the first layer 8. It is not overlapped at the contact position of 8f).

The third layer 10 is formed in a rectangular plate shape having a size substantially corresponding to the planar shape of the liquid crystal display panel 6 by combining two rectangular plate-shaped diffusion member blocks 10a and 10b. The 3rd layer 10 arrange | positions two diffusion member blocks 10a and 10b horizontally, and is formed in square plate shape by making the side surface of both the diffusion member blocks 10a and 10b adjoin.

The contact positions of the two diffusion member blocks 10a and 10b of the third layer 10 are not overlapped with the contact positions of the respective diffusion member blocks 9a to 9o of the second layer 9. .

Each of the diffusion member blocks 8a to 8f, 9a to 9o, and 10a to 10b of the first to third layers 8 to 10 has an acrylic resin (PMMA), a polycarbonate (PC), and a cycloolefin type having excellent light transmittance. It consists of injection molded objects, such as resin.                     

FIG. 5 is a partially enlarged view of the light diffusing member assembly 2 shown in FIG. 4. 6 is a partially enlarged view showing the light diffusing member assembly 2 shown in FIG. 5 decomposed into the respective layers from the first layer 8 to the third layer 10.

As shown in these figures, on the surface of the diffusion member blocks 8a to 8f that oppose the second layer 9 (diffusion member blocks 9a to 9o), the first concave portion 11 having a substantially semicircular cross section is provided. Many are formed at equal intervals. Moreover, in the surface which opposes the 1st layer 8 (diffusion member block 8a-8f) in the diffusion member blocks 9a-9o, the 2nd recess whose cross section which opposes the 1st recessed part 11 is substantially semi-circular is formed. A large number of portions 12 are formed at equal intervals.

Then, 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 overlap and closely contact each other, the first recess 11 and the second recess The part 12 forms the hole part 13 which has a substantially circular cross section.

Next, on the surface facing the third layer 10 (diffusing member blocks 10a, 10b) in the diffusing member blocks 9a to 9o, the third concave portion 14 having a substantially semicircular cross section is the second concave portion. A plurality of positions are formed at the same pitch P as the pitches of formation of the second concave portion 12 by taking positions corresponding to the positions between the two portions 12. Further, on the surface of the diffusion member blocks 10a and 10b that faces the second layer 9 (diffusion member blocks 9a to 9o), a fourth concave having a substantially semicircular cross section facing the third concave portion 14 is provided. A large number of portions 15 are formed at equal intervals.

Then, when the diffusion member blocks 9a to 9o of the second layer 9 and the diffusion member ash blocks 10a and 10b of the third layer 10 overlap and closely contact each other, the third recessed portion 14 and the fourth The recessed part 15 forms the hole part 16 whose cross section is substantially circular.

In addition, the pitch P between each recessed part 11, 12, 14, 15 should be set in the range of 2R <= P <= R if the radius of the recessed part 11, 12, 14, 15 is R. desirable.

It should be noted here that the first layer 8, when viewed from above the light diffusing member assembly 2 (in the B direction in FIG. 4) or when viewed in the inclined direction (the C and D directions in FIG. 4). ) And the hole part 16 which arises in the overlapping surface of the 2nd layer 9 and the 3rd layer 10 between the hole part 13 which arises in the overlapping surface of the 2nd layer 9. That is, the hole 16 is in a position shifted by half pitch with respect to the hole 13. Air is present in the holes 13 and 16.

Here, in the air present in the diffusion member blocks 8a ... 10b and the holes 13, 16, the refractive index of light is significantly different (for example, the refractive index of PMMA is about 1.49, and the refractive index of PC is 1.59). The refractive index of is approximately 1.0) and the cross-sectional shapes of the holes 13 and 16 are approximately circular, so that when the light from the fluorescent lamp 3 passes through the light diffusing member assembly 2, the holes 13, 16) effectively diffuses.

That is, not only when the light diffusing member assembly 2 is viewed from above (in the B direction in FIG. 4) but also when viewed from the top of the inclination (in the directions C and D in FIG. 4), the light from the fluorescent lamp 3 is formed in the hole portion. It spreads uniformly at (13, 16). Therefore, the luminance of the emitted light is uniform, so that the difference in the contrast of the emitted light does not easily occur.

In this embodiment, the adjacent diffusion member blocks 8a to 8f, 9a to 9o, and 10a to 10b of each layer may be bonded to each other to be integrated. In this case, it is preferable to use an adhesive (for example, an epoxy resin adhesive) having substantially the same refractive index as the diffusion member blocks 8a ... 10b.

(Reflective member)

As shown in Figs. 1 and 2 and 4, the reflective member 4 has a silver deposited layer on the inner surface of a resin material such as white polyethylene terephthalate (PET) having excellent light reflectivity or a metal plate such as a stainless steel sheet. It is formed with what was formed. A part of the light from the fluorescent lamp 3 is reflected by the reflecting member 4 and effectively reflected on the back surface side of the light guide plate assembly 2.

(Diffusion Sheet)

As shown in Figs. 1 and 2 and 4, the diffusion sheet 5 has a roughening of the surface, formation of a light diffusion pattern of light diffusing ink onto the surface, or the like for PET sheets having excellent light transmittance. It is composed of a member to which light diffusivity is imparted due to dispersion of light diffusing material in the furnace. Light emitted from the light diffusing member assembly 2 is diffused by the diffusion sheet 5.

As a result, when the surface light source device 1 is viewed from the emission surface direction of the diffusion sheet 5, the diffusion member blocks 8a to 8b and 9a to 9o of each layer up to the first to third layers 8 to 10 are obtained. , Abutment portions (dividing portions from the first layer 8 to the third layer 10) of 10a to 10b are prevented from being visible.

(Operation and Effect of the Present Embodiment)                     

The outline of the light behavior in this embodiment is as follows.

Light of the fluorescent lamp 3 is incident directly from the lower surface of the diffusion member blocks 8a to 8f of the first layer 8 of the light diffusing member assembly 2 after being reflected by the reflecting member 4. In the process of propagating the incident light in the diffusion member blocks 8a to 8f, the recesses 11 and 12 (holes 13) formed on the overlapping surface of the first layer 8 and the second layer 9. Refracting at the interface of.

The cross-sectional shape of the hole 13 is substantially circular, and air is present inside the hole 13. And in the air which exists in the hole part 13 and the diffuser block 8a-9o of the 1st and 2nd layer 8 and 9, the refractive index of light differs large. Therefore, the light propagating in the diffusion member blocks 8a to 8f diverges substantially in uniformly in the direction of travel due to refraction. In addition, some light is not diffused by the hole 13.

When these diffused and non-diffused light propagates in the diffusion member blocks 9a to 9o of the second layer 9, the concave formed in the overlapping surface of the second layer 9 and the third layer 10. Refracting is performed at the interface with the portions 14 and 15 (holes 16). The hole 16 is diffused almost uniformly by the same refractive action as the hole 13 described above. Thereby, the light which was not diffused in the hole 13 and most of it diffuses in the hole 16.

10 conceptually shows a representative optical path of light diffused by refraction in the holes 13 and 16.                     

In this way, the light emitted from the light diffusing member assembly 2 is equalized not only in the normal direction (the B direction in FIG. 4) of the emission surface but also in the inclination direction (the C and D directions in FIG. 4) with respect to the normal direction. This means that the light emitted from the light diffusing member assembly 2 does not easily generate luminance deviation even when viewed from an inclined viewing direction other than the front surface, whereby high illumination quality can be obtained. Light emitted from the light diffusing member assembly 2 passes through the diffusion sheet 5 to illuminate the liquid crystal display panel 6.

In addition, care is taken to ensure that adjacent diffusion block of each layer is in close contact with each other. If the adhesion is insufficient, an optical interface occurs along the boundary, and abnormal light emission such as a stripe-shaped bright line may be observed. However, even if such abnormal light emission generate | occur | produces, it is not easy in this embodiment.

For example, even if abnormal light emission has occurred at the abutting portion of each of the diffusion member blocks 8a to 8f of the first layer 8, this is the second layer 9, the third layer 10 and the diffusion sheet 5 ) Can be blurred by the diffusion action of). Further, even when abnormal light emission occurs at the abutting portion of each of the diffusion member blocks 9a to 9o of the second layer 9, it is diffused in the third layer 10 and the diffusion sheet 5. Moreover, even if abnormal light emission generate | occur | produced in the contact part of the diffusion member blocks 10a and 10b of the 3rd layer 10, it diffuses in the diffusion sheet 5 ,.

Moreover, the surface light source device 1 which concerns on this embodiment also has the feature that it is not necessary to form the light shielding film (light shielding pattern) like a conventional example. Since no light shielding film is used, the absorption loss of light can be prevented and the emitted light brightness can be increased.

And the surface light source device 1 which concerns on this embodiment is easy to change size. This multilayers the light diffusing member assembly 2 into the first to third layers 8 to 10 and each layer 8 to 10 into a plurality of diffusion member blocks 8a to 8f, 9a to 9o, and 10a to 10b. This is because the configuration is divided into. By increasing or decreasing the number of combinations of the small diffusion member blocks 8a ... 10b, the light exit area of the light diffusing member assembly 2 can be easily enlarged or reduced.

In the case where the diffusion member blocks 8a ... 10b are manufactured by injection molding, a large mold becomes unnecessary, and regardless of the size of the liquid crystal display panel 6 (the size of the display screen), the diffusion member blocks 8a. Injection mold can be shared. In addition, since each diffusion member block 8a ... 10b is small and easy to injection molding, no molding defect occurs and the yield of the product is good.

This simplifies the manufacturing equipment. For example, even when manufacturing the surface light source device 1 for a large screen, it can respond without preparing a large manufacturing equipment.

Moreover, in the surface light source device 1 which concerns on this embodiment, since the inside of the hole parts 13 and 16 of the light-diffusion member assembly 2 is an air layer, weight reduction of the total weight can be attained.

Second Embodiment

In FIG. 7, four examples (a) to (d) of the light diffusing member assembly 2 employed in the second embodiment are shown in a side view showing a part of them enlarged. As shown in these examples, in this embodiment, many 1st recessed parts 20 which are substantially semicircular in cross section are formed in either one of the overlapping surfaces of the 1st layer 8 and the 2nd layer 9. In addition, many 2nd recessed parts 21 with a substantially semicircular cross section are formed in either one of the overlapping surfaces of the 2nd layer 9 and the 3rd layer 10. As shown in FIG. The first to third layers 8 to 10 are configured by combining a plurality of diffusion member blocks 8a ... 10b as in the first embodiment (see FIG. 3).

In a 1st example, as shown to FIG. 7 (a), the 1st recessed part 20 is formed in the surface which opposes the 2nd layer 9 of the 1st layer 8, and the 2nd recessed part 21 is shown. ) Is formed on the side opposite to the second layer 9 of the third layer 10. And the 2nd recessed part 21 is located between the 1st recessed parts 20 and 20. FIG. That is, the 2nd recessed part 21 is shift | deviated with respect to the 1st recessed part 20 by half pitch.

In a 2nd example, as shown to FIG. 7 (b), the 1st recessed part 21 is formed in the surface which opposes the 1st layer 8 of the 2nd layer 9, and the 2nd recessed part ( 21 is formed on the surface opposite to the third layer 10 of the second layer 9. And the 2nd recessed part 21 is located between the 1st recessed parts 20 and 20. As shown in FIG.

In a 3rd example, as shown to FIG. 7 (c), the 1st recessed part 20 is formed in the surface which opposes the 1st layer 8 of the 2nd layer 9, and the 2nd recessed part 21 is shown. ) Is formed on the surface of the third layer 10 that faces the second layer 9. And the 2nd recessed part 21 is located between the 1st recessed parts 20 and 20. As shown in FIG.

In the fourth example, as shown in FIG. 7D, the first concave portion 20 is formed on a surface of the first layer 8 that faces the second layer 9, and the second concave portion 21. ) Is formed on the surface of the second layer 9 that faces the third layer 10. And the 2nd recessed part 21 is located between the 1st recessed parts 20 and 20. As shown in FIG.

In any of these examples, since the light from the fluorescent lamp 3 is diffused by the recesses 20 and 21, the light from the exit surface of the light diffusing member assembly 2 can be emitted almost uniformly. As a result, similarly to the first embodiment, it is possible to effectively prevent the occurrence of the luminance deviation of the emitted light in the observation direction. In addition, since it is the same as that of the 1st Embodiment about another effect, the repeated description is abbreviate | omitted.

[Third Embodiment]

In FIG. 8, the four examples (a)-(d) of the light-diffusion member assembly 2 employ | adopted in 3rd Embodiment are shown by the side view which expanded and showed a part. As shown in these examples, in the present embodiment, the light diffusing member assembly 2 is composed of the first layer 8 and the second layer 9, and the first layer 8 and the second layer 9 are formed. A large number of recesses 22 are formed in at least one of the overlapping surfaces of. In addition, similarly to each embodiment mentioned above, the 1st layer 8 and the 2nd layer 9 are comprised combining the some diffusion member block 8a-8f, 9a-9o.

In a 1st example, as shown to FIG. 8 (a), the recessed parts 22 and 22 oppose the overlapping surface of the 1st layer 8 and the 2nd layer 9, and are formed. In the 2nd example, as shown to FIG. 8 (b), many recessed parts 22 are formed in the surface which opposes the 2nd layer 9 of the 1st layer 8. In FIG. In addition, in the 3rd example, as shown to FIG. 8 (c), many recessed parts 22 are formed in the surface which opposes the 1st layer 8 of the 2nd layer 9. As shown to FIG. In addition, the recessed part 22 in these 1st-3rd examples is continuously formed in the smooth curved surface, and the adjacent recessed parts 22 and 22 are also connected by the smooth curved surface. The cross-sectional shape of the surface which forms the recessed part 22 becomes substantially wavy shape.

In the fourth example, as shown in Fig. 8 (d), a plurality of recesses 22 and 22 having substantially semicircular cross sections are formed in respective overlapping surfaces of the first layer 8 and the second layer 9, respectively. have. And the recessed part 22 of the 2nd layer 9 is located between the recessed parts 22 and 22 of the 1st layer 8. As shown in FIG.

In any of these examples, since the light from the fluorescent lamp 3 is diffused by the recesses 22, the light from the exit surface of the light diffusing member assembly 2 can be emitted almost uniformly. As a result, similarly to the first and second embodiments, it is possible to effectively prevent the occurrence of the luminance deviation of the emitted light in the observation direction. Since the light diffusing member assembly 2 according to the present embodiment has a small number of layers, the light diffusing member assembly 2 is advantageous in reducing the thickness and weight of the surface light source device 1 and the image display device 7 including the device 1. . In addition, since it is the same as that of the 1st Embodiment about another effect, the repeated description is abbreviate | omitted.

In addition, in each of the first to third embodiments described above, as shown in Fig. 9, the concave portions 11 to 12, 14 to 15, and 20 to 22 are formed linearly along the longitudinal direction of the fluorescent lamp. It is preferable.

[Other Modifications]

In the above-described embodiment, the following modifications are allowed, for example.                     

(i) In each embodiment mentioned above, the case where air exists in the recessed parts 11-12, 14-15, 20-22 was illustrated. However, the present invention is not limited to this. For example, the concave portions 11-12, 14-15, 20-22 may be filled with a light transmitting material having a refractive index different from that of the diffusion member blocks 8a ... 10b.

The light-transmitting material filled in the recesses 11 to 12, 14 to 15, and 20 to 22 incorporates fine particles having different refractive indices into the same or different materials as the diffusion member blocks 8a ... 10b. It may be dispersed.

In addition, the light transmissive substance may be filled in the whole of the recessed parts 11-12, 14-15, 20-22, and may be filled in a part of it.

(ii) In each of the above-described embodiments, cross-sectional recesses 11 to 12, 14 to 15, and 20 to 22 are continuously formed in a substantially semi-circular or smooth curve. However, this is only a preferable example. Generally, it may be a concave portion having a cross-sectional shape capable of diffusing light, and may be a concave portion having a substantially triangular cross section or a concave portion of another cross-sectional shape.

(iii) In each embodiment mentioned above, the light-diffusion member assembly 2 is comprised by three layers or two layers. However, the light diffusing member assembly 2 may be made into a multilayer structure having four or more layers by increasing the number of layers.

(iv) The linear arrangement of the recesses 11-12, 14-15, 20-22 as shown in FIG. 9 is an example. Alternatively, a plurality of concave portions may be formed in a dot shape.                     

(v) In each of the above-described embodiments, the formation pitch of the recesses (holes) is constant. However, you may change the formation pitch (density) according to the position with respect to the light source arrange | positioned at the back surface side.

As described above, in the present invention, light can be diffused and output almost uniformly by a light diffusing member assembly having a multilayer structure and having a concave portion having a light diffusing function on at least one of the overlapping surfaces of the layers. Therefore, it is possible to effectively suppress the occurrence of the luminance deviation along the observation direction, so that the luminance distribution of the emitted light in the oblique direction with respect to the normal direction of the exit surface is also uniform as well as the normal direction of the exit surface. As a result, high illumination quality can be maintained.

Further, in the present invention, since the concave portion formed in at least one of the overlapping surfaces of the respective layers of the light diffusing member assembly diffuses the light, there is no need to form the light shielding pattern in the diffusion member as in the prior art. As a result, absorption loss of light generated when the light shielding pattern is formed can be eliminated. Therefore, the emission light intensity can be efficiently increased.

Then, when the surface light source device having the light diffusing member assembly according to the present invention is used for illumination of the image display portion, it becomes uniform and efficient illumination to obtain a bright and easy to see display image.

Claims (12)

A light diffusing member assembly for diffusing and emitting light from a light source disposed on a back surface side, Has at least a first layer and a second layer, The first layer is composed of one or more diffusion member blocks, The second layer is composed of one or more diffusion member blocks overlapping the first layer, The at least one of the overlapping surfaces of the said 1st layer and said 2nd layer is formed with the light-diffusion member assembly characterized by the above-mentioned. A light diffusing member assembly for diffusing and emitting light from a light source disposed on a back surface side, Has at least a first layer and a second layer, The first layer is composed of one or more diffusion member blocks, The second layer is composed of one or more diffusion member blocks overlapping the first layer, A plurality of first recesses are formed on a surface of the first layer that faces the second layer, A light diffusing member assembly, wherein a plurality of second recesses are formed on a surface of the second layer that faces the first layer so as to be located between the first recesses. The method according to claim 1 or 2, The diffusion member block constituting the first layer and the diffusion member block constituting the second layer are formed in different sizes, and the contact position of each diffusion member block of the first layer and the angle of the second layer are different. The light diffusing member assembly, wherein the abutting positions of the diffusing member blocks do not overlap. A light-diffusion member assembly for diffusing and emitting light from a light source disposed on the back surface side, Has at least a first layer, a second layer and a third layer, The first layer is composed of one or more diffusion member blocks, The second layer is composed of one or more diffusion member blocks overlapping the first layer, The third layer is composed of one or more diffusion member blocks overlapping the second layer, A plurality of first recesses are formed in at least one of the overlapping surfaces of the first layer and the second layer, A plurality of second recesses are formed in at least one of the overlapping surfaces of the second layer and the third layer, And the second concave portion is located between the first concave portion. A light diffusing member assembly for diffusing and emitting light from a light source disposed on a back surface side, Has at least a first layer, a second layer, and a third layer, The first layer is composed of one or more diffusion member blocks, The second layer is composed of one or more diffusion member blocks overlapping the first layer, The third layer is composed of one or more diffusion member blocks overlapping the second layer, On the surface facing the second layer of the first layer, a plurality of first recesses having a substantially semicircular cross section are formed, On the surface facing the first layer of the second layer, a second recess having a semi-circular cross section is formed at a position corresponding to the first recess, On the surface facing the third layer of the second layer, a third recess having a semi-circular cross section is formed so as to be located between the second recesses, A light diffusing member assembly comprising a fourth recess having a semi-circular cross section formed at a position corresponding to the third recess in a surface of the third layer that faces the second layer. The method according to claim 4 or 5, The diffusion member block constituting the first layer and the diffusion member block constituting the second layer are formed in different sizes, The contact position of each diffusion member block of the said 1st layer and the contact position of each diffusion member block of a said 2nd layer do not overlap, The diffusion member block constituting the second layer and the diffusion member block constituting the third layer are formed in different sizes, And abutting positions of the respective diffusion member blocks of the second layer and abutting positions of the respective diffusion member blocks of the third layer are not overlapped. The method according to any one of claims 1, 2, 4 or 5, And the light source is a rod-shaped fluorescent lamp, and the recess is formed in a linear shape along the longitudinal direction of the fluorescent lamp. The method according to any one of claims 1, 2, 4 or 5, And a light-transmitting material having a refractive index different from that of the diffusion member block in the entire concave portion. The method according to any one of claims 1, 2, 4 or 5, And a light-transmitting material having a refractive index different from that of the diffusion member block in part of the plurality of recesses. The light diffusing member assembly according to any one of claims 1, 2, 4 or 5, And a reflecting member positioned at the back side of the light diffusing member assembly and reflecting light from the light source to the back side of the light diffusing member assembly. The method of claim 10, And at least one diffusion sheet is arranged on the emission surface side of the light diffusion member assembly. The surface light source device according to claim 10, And an image display unit illuminated by the surface light source device.

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