KR20080077386A - Light guide member, planar light source device provided with the light guide member, and display apparatus using the planar light source device - Google Patents

Abstract

It is an object to provide a light guide member that is laminated on the upper face of a luminous device mounting substrate on which a luminous device such as an LED has been mounted. In the light guide member, a luminance at the section directly over the luminous device is lowered, a luminance distribution on a light emission face of the light guide plate can be uniformed, a nonuniformity in luminance and an unevenness of colors can be decreased, a utilization efficiency of a light can be increased, and a high luminance can be implemented. In addition, it is an object to provide a light guide member, a planar light source device provided with the light guide member, and a display apparatus using the planar light source device, which can be thinned and miniaturized as a planar light source device using the light guide member. A light guide plate, which is laminated on the upper face of a luminous device mounting substrate on which a luminous device is mounted and which is for diffusing and guiding upward a light emitted from the luminous device, is characterized by comprising a light reflecting portion formed on the bottom face of the light guide member in an area other than an area near around the luminous device.

Description

LIGHT GUIDE MEMBER, PLANAR LIGHT SOURCE DEVICE PROVIDED WITH THE LIGHT GUIDE MEMBER, AND DISPLAY APPARATUS USING THE PLANAR LIGHT SOURCE DEVICE}

                          Cross Reference to Related Application

This application is subject to 35 USC§119 of Provisional Application No. 60 / 748,191, filed December 8, 2005 and 35 / C, No. 60 / 789,128, filed April 5, 2006, pursuant to 35 USC §111 (b). e) an application filed under 35 USC § 111 (a) claiming benefit under (1).

The present invention relates to a light guide member, a surface light source device and a display device using the surface light source device. In particular, the present invention provides a light guide member; A surface light source device which is used as a light source such as an advertisement lamp, an illumination, and a back light for a liquid crystal display, and has a light guide member that can uniformly diffuse and guide light from a light emitting element upwardly; And a display device such as a liquid crystal display device using this surface light source device.

In recent years, display apparatuses using a surface light source device (backlight) for irradiating light from the back or side surface of a panel such as a liquid crystal display have been widely used. Conventionally, the mainstream of the backlight light source for liquid crystal displays has become the so-called edge light type in which a cold cathode tube as a light source is disposed on the edge surface of the chassis for thinning and low power consumption of the device.

As such an edge light type backlight source, a light source having the configuration shown in Fig. 24 is used.

More specifically, for the edge light type backlight light source 100, the cold cathode tube 104 is disposed on the edge portion of the chassis 102. The light guide member 106 is disposed on the side of the cold cathode tube 104, and the diffusion sheet 108 is disposed over the upper surface of the light guide member 106, thereby constituting the backlight light source 100.

A reflecting portion 116 is formed under the light guide member 106, which is produced by a minute non-uniform structure or by drawing a dot shape with, for example, white ink. Furthermore, the liquid crystal panel 110 is laminated on the upper surface of the diffusion member 108 of the backlight light source 100, thereby constituting the liquid crystal display device 112.

For the edge light type backlight light source 100, the cold cathode tube 104 becomes a light source, so that light emitted from the cold cathode tube 104 enters into the side portion of the light guide member 106.

Light entering the light guiding member 106 is formed under the light guiding member 106 and is formed by a minute non-uniform structure, for example, by reflecting a dot shape with white ink. The diffusion is repeated between the top surfaces 118 with repeated reflections. Light is then guided uniformly upward from the top surface 118 of the light guide member 106.

By the above configuration, the light is uniformly diffused by the diffusion member 108, thereby reducing the nonuniformity in terms of the brightness of the liquid crystal panel 110.

However, the demand for the enlargement of the liquid crystal display has increased in recent years, and this edge light type backlight light source 100 has a limitation in improving the uniformity in brightness and brightness.

Therefore, application of direct lighting type light to large liquid crystal displays is under consideration.

However, in the case where the cold cathode tube described above is used as a direct light source, the cold cathode tube is relatively large, so that the thickness of the liquid crystal display becomes large. In addition, color reproducibility and responsiveness of the cold cathode tube are not satisfactory, and there is a problem that an afterimage phenomenon occurs.

Recently, the luminous efficiency of the light emitting device has been greatly improved, and the application of the light emitting device as a light source is in progress. In particular, when a light emitting diode (LED) is used as a backlight light source (surface light source) for a liquid crystal display, it is expected to achieve excellent color reproduction and high-speed response and to achieve high quality images.

Therefore, conventionally, a direct backlight light source in which a plurality of LEDs are arranged at a constant pitch under the liquid crystal panel has been proposed.

As such a direct backlight source, a light source having the configuration shown in Fig. 25 is proposed.

More specifically, for the direct backlight light source 200, a plurality of LED lamps 206 are arranged at a constant pitch in a certain array pattern on the bottom of the chassis 202.

A diffuser member 208 is disposed above the top surface of the chassis 202 at a distance from the LED lamp 206, and a prism sheet 210 is disposed above the top surface of the diffuser member 208, thereby providing a backlight light source ( 200).

Reflecting portions 214 made of a reflective sheet or the like are formed on the bottom 204 and side surfaces 212 of the chassis 202.

For the direct backlight light source 200 configured as described above, when light is generated from the LED lamp 206, the emitted light moves directly toward the diffusion sheet 208. In addition, the emitted light is also reflected by the reflecting portion 214 on the bottom 204 and side 212 of the chassis 202 and travels toward the diffusion sheet 208.

Light entering the diffusion sheet 208 is then diffused in the diffusion sheet 208 and directed in a vertical direction by passing through a prism sheet 210 on the top surface of the diffusion sheet 208. Light then enters a liquid crystal panel (not shown) disposed over the top surface of the prism sheet 210.

Moreover, the light emitted from the LED lamp 206 is mixed in the space between the LED lamp and the diffusion sheet 208. This mixing is then facilitated by diffusion in diffuser plate 208, thereby achieving uniform brightness and uniform chromaticity.

Moreover, in general, the brightness in the section directly above the LED lamp 206 is higher than in other sections. Therefore, uniformity in terms of brightness can be further improved by increasing the diffusivity of the diffusion sheet 208 in the section directly above the LED lamp 206.

For a conventional direct backlight backlight 200, the diffusion sheet 208 is placed away from the LED lamp 206 to equalize the brightness and chromaticity as described above. However, even in this case, the above means are insufficient to solve the problem of higher luminance in the section immediately above the LED lamp 206.

Recently, color mixing has been carried out (without using monochromatic LEDs), in particular by using a plurality of color (RGB) LED lamps consisting of LEDs of three primary colors of red, green and blue. In this case, in some cases, mixed color may be insufficient and color nonuniformity may be found.

Thus, in order to reduce the nonuniformity in terms of luminance and the nonuniformity of color, the diffusivity of the diffusion sheet 208 in the section immediately above the LED lamp 206 is further increased as described above.

Further, in Patent Document 1 (Japanese Laid-Open Patent Publication No. 2001-42782), a so-called lighting curtain, such as a gray print layer having light translucency, is in some cases an LED lamp in order to reduce the brightness in the section immediately above the LED lamp. Placed directly above.

However, the above means lowers the utilization efficiency of light.

In addition, when the diffusion sheet 208 is made further away from the LED lamp 206, the nonuniformity in terms of luminance and the nonuniformity of color may be reduced. However, this method increases the thickness of the backlight, which is not preferable for flat panel displays.

As a result, Patent Document 2 (Japanese Laid-Open Patent Publication No. 1998-82915) proposes a surface light source device 300 as shown in FIG.

More specifically, in the surface light source device 300, the light guide member 306 is laminated on the upper surface of the light emitting element mounting substrate 308 on which the LED lamp 302 is mounted. A recess 304 for the LED lamp housing is formed in the light guide member 306 at a position corresponding to the LED lamp 302 in a narrower manner in a section whose width is deeper from the surface of the light guide member.

Furthermore, a reflecting portion 312 made of a reflective sheet or the like is formed on the bottom surface 310 of the light guide member 306 except for the section corresponding to the recess 304 for the LED lamp housing.

With the above arrangement, as shown in Fig. 26, the light B1 emitted from the LED lamp 302 is guided with the upper surface 314 of the light guiding member 306 as shown by the arrow B2. The reflection is diffused repeatedly between the reflecting portions 312 formed on the bottom surface 310 of the member 306, and is uniformly guided upward from the upper surface 314 of the light guide member 306.

As a result, the light is uniformly diffused by the diffusion sheet (not shown) formed on the upper surface of the light guide member 306, thereby preventing the occurrence of nonuniformity in terms of luminance and A uniform luminance distribution in the light emission plane is achieved.

As a result, the surface light source device 300 disclosed in Patent Document 2 is thinner than a conventional device, has less color nonuniformity, and can improve luminance.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-42782

[Patent Document 2] Japanese Patent Publication No. 1998-82915

In the surface light source device 300 described in Patent Document 2, an attempt is made to uniformize the luminance. However, as shown in Fig. 26, in the surface light source device 300, the light emitted from the LED lamp 302 is reflected by the reflecting portion 312 just near the LED lamp 302 as shown by the arrow B3. ) Is emitted and guided upward from the top surface 314 of the light guide member 306.

As a result, the amount of light emitted from the top surface 314 of the light guiding member 306 in the section directly above the LED lamp 206 is large, as shown by the dashed-dotted line in the graph of FIG. Is insufficient to solve the problem of higher luminance in the section immediately above the LED lamp 206.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a light guide member laminated on an upper surface of a light emitting element mounting substrate on which a light emitting element such as an LED lamp is mounted. In the light guiding member, the luminance in the section immediately above the light emitting element can be lowered, the luminance distribution on the light emitting surface of the light guiding member can be uniform, the nonuniformity in color and the nonuniformity of color can be reduced, and the use of light Efficiency can be increased and high brightness can be achieved. In addition, the surface light source device using the light guide member can be further thinned and downsized.

Furthermore, another object of the present invention is a surface light source device in which the nonuniformity in color and the nonuniformity in color can be reduced, the light use efficiency can be increased, and high brightness can be realized, and a display device using the surface light source device. To provide. In addition, the surface light source device and the display device can also be thinned and miniaturized.

The inventors of the present invention have studied to solve the above problem. As a result, the inventors of the present invention have invented a light guide member, a surface light source device provided with the light guide member, and a display device using the surface light source device according to the present invention.

More specifically, the present invention includes the following aspects (1) to (16), for example.

(1) a light guide member which is disposed on an upper surface of a light emitting element mounting substrate on which a light emitting element is mounted and diffuses and guides the light emitted from the light emitting element upward;

A light reflecting portion formed on the bottom surface of the light guide member at a position not near the light emitting element;

A light guide member comprising a section in which light reflection is not formed on the bottom of the light guide member at a position near the light emitting element.

(2) In the above aspect (1), the recess for the light emitting element in the light guide member at a position corresponding to the light emitting element,

A light guiding member on a part of the surface on the concave portion of the concave portion for the light emitting element further comprises a light guide member.

(3) The light guide member according to the aspect (2) above, wherein the light semitransmissive portion on the surface of the concave portion is formed at a position above the light emitting element.

(4) The light guide member according to any one of the above aspects (1) to (3), wherein the region near the light emitting element is an area up to a constant distance from the light emitting element.

(5) In any of the above aspects (1) to (4), in the section closer to the light emitting element, the dot-shaped light reflecting region in the region near the light emitting element so that the dot density of the light reflecting portion is lower. The light guide member further comprises.

(6) The light guide member according to the above aspect (1), further comprising a light semitransmissive portion at a position on the upper surface of the light guide member corresponding to the light emitting element.

(7) The light guide member according to the aspect (6) above, wherein the light semitransmissive portion is formed on the upper surface of the light guide member at a position directly above the light emitting element.

(8) The light guiding member according to the above aspect (7), wherein the light semitransmissive portion is formed on the upper surface of the light guiding member in the vicinity of the light emitting element up to a predetermined distance from the light emitting element.

(9) The region near any one of the above aspects (1) to (8), wherein a plurality of light emitting elements mounted on the light emitting element mounting substrate are arranged apart and no light reflecting portion is formed. A light guide member, characterized in that it is disposed at a plurality of positions on the bottom surface of the light guide member corresponding to the light emitting element.

(10) In the above aspect (9), the distance between adjacent light emitting elements of the plurality of light emitting elements is D and a constant distance from the light emitting element to the peripheral edge of the region near the light emitting element in which no light reflecting portion is formed. When is d, D / 4 is d or more, The light guide member characterized by the above-mentioned.

(11) The light emitting element mounted on the light emitting element mounting substrate according to any one of the above aspects (1) to (10) is a unit light emitting element in which various kinds of light emitting elements having different light emission colors are combined The light guide member comprised by the said light emitting element in which the light reflection part is not formed is formed corresponding to the unit light emitting element.

(12) In any of the above aspects (2) to (5), the light emitting element mounted on the light emitting element mounting substrate is constituted by a unit light emitting element in which various kinds of light emitting elements having different light emitting colors are combined. And the recess for the light emitting element is formed corresponding to the unit light emitting element.

(13) A surface light source device, wherein a light guide member as defined in any one of the above aspects (1) to (12) is disposed on an upper surface of a light emitting element mounting substrate on which a light emitting element is mounted.

(14) The plane light source device according to the aspect (13) above, wherein the light emitting element is a light emitting diode.

(15) A display device comprising a display portion disposed on an upper surface of a surface light source device as defined in aspect (13) or aspect (14) above.

(16) The display device according to aspect (15) above, wherein the display portion is a liquid crystal panel.

The light guide member related to the present invention emits light in such a manner that the intensity of diffusion upward from the bottom of the light guide member near the light emitting element is smaller than the intensity of diffusion upward from the bottom of the light guide member provided with the light reflecting portion in the peripheral section thereof. And a light reflecting portion formed on the bottom surface of the light guide member at a position not near the element, and a section not formed on the bottom surface of the light guide member at a position near the light emitting element. As a result, the luminance in the section immediately above the light emitting element can be lowered, the luminance distribution on the light emitting surface of the light guide member can be uniform, the nonuniformity in color and the nonuniformity of color can be reduced, and the light utilization efficiency It can be increased and high brightness can be realized.

According to an embodiment of the present invention, the light semitransmissive portion is formed at a position on the upper surface of the light guide member corresponding to the light emitting element, or has a function of reflecting and diffusing onto the surface on the concave portion of the recess for the light emitting element formed in the light guide member. The light transflective portion is formed. As a result, since the light emitted from the light emitting element is diffusely reflected by the light semitransmissive portion, the increase in the luminance in the section immediately above the light emitting element is suppressed, and the luminance distribution on the light emitting surface of the light guide member can be made uniform. The nonuniformity in color and the nonuniformity in color can be reduced, the light use efficiency can be increased, and high brightness can be realized.

Moreover, when the light guide member is used as the surface light source device, the luminance distribution can be uniform, the nonuniformity in color and the nonuniformity in color can be reduced, the light utilization efficiency can be increased, and high brightness can be realized. And the device can be thinned and miniaturized.

Furthermore, by the surface light source device using such a light guiding member, since the luminance in the section immediately above the light emitting element is lowered, the luminance is uniform, high brightness can be realized, color unevenness does not occur, and the chromaticity is the surface light source device. Is uniform for the entire surface.

As a result, when the surface light source device related to the present invention is used as a display device, in particular, as a backlight for a liquid crystal display, a display device having a thin and high quality image can be obtained.

Fig. 1 is a diagram showing the overall configuration of a typical liquid crystal display device to which this embodiment is applied.

Fig. 2 is a plan view showing a first embodiment of the surface light source device according to the present invention to which the light guide member according to the present invention is applied.

3 is a partially enlarged cross-sectional view showing the configuration along the A-A line shown in FIG.

4 is a graph showing the distance from the LED and the relative luminance in the horizontal direction.

Fig. 5 is a plan view schematically showing the shape of a region near the light emitting element in which the light reflecting portion is not formed with respect to the light guide member according to the present invention.

Fig. 6 is a plan view schematically showing the shape of a region near the light emitting element in which the light reflecting portion is not formed with respect to the light guide member according to the present invention.

Fig. 7 is a schematic sectional view showing the second embodiment of the surface light source device related to the present invention.

8 is a plan view showing a third embodiment of the present invention to which a light guiding member according to still another embodiment of the present invention is applied.

FIG. 9 is a partially enlarged sectional view showing a configuration along a line A-A shown in FIG.

Fig. 10 is a plan view showing a fourth embodiment of the surface light source device according to the present invention to which the light guiding member according to another embodiment of the present invention is applied.

Fig. 11 is a plan view showing a fifth embodiment of the surface light source device according to the present invention to which the light guiding member according to another embodiment of the present invention is applied.

Fig. 12 is a plan view showing a sixth embodiment of the surface light source device according to the present invention to which the light guiding member according to the present invention is applied.

FIG. 13 is a partially enlarged sectional view showing a configuration along a line A-A shown in FIG.

Fig. 14 is a plan view schematically showing the shape of a region near the light emitting element in which the light reflecting portion is not formed with respect to the light guide member related to the present invention.

Fig. 15 is a plan view schematically showing the shape of a region near the light emitting element in which the light reflecting portion is not formed with respect to the light guide member according to the present invention.

Fig. 16 is a schematic sectional view showing the seventh embodiment of the surface light source device related to the present invention.

Fig. 17 is a plan view showing an eighth embodiment of a surface light source device according to the present invention to which a light guiding member according to still another embodiment of the present invention is applied.

Fig. 18 is a plan view showing the surface light source device related to the present invention to which the light guide member according to Embodiment 1 of the present invention is applied.

Fig. 19 is a plan view showing a surface light source device according to the present invention to which a light guiding member according to Embodiment 2 of the present invention is applied.

Fig. 20 is a plan view showing a surface light source device according to the present invention to which a light guiding member according to Embodiment 3 of the present invention is applied.

Fig. 21 is a plan view showing a surface light source device according to the present invention to which a light guiding member according to Comparative Example 1 of the present invention is applied.

Fig. 22 is a plan view showing a surface light source device according to the present invention to which a light guiding member according to Comparative Example 2 of the present invention is applied.

Fig. 23 is a graph showing the distance from the light emitting element 14 and the relative luminance in the horizontal direction related to the Examples and Comparative Examples of the present invention.

Fig. 24 is a schematic sectional view showing a conventional edge light type backlight light source.

Fig. 25 is a schematic sectional view showing a conventional direct backlight type light source.

Fig. 26 is a schematic sectional view showing a conventional surface light source device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a diagram showing the overall configuration of an example of a liquid crystal display device to which this embodiment is applied. In the liquid crystal display device to which the present embodiment is applied, an LED substrate (light emitting element mounting substrate) as a substrate on which a backlight frame 51 surrounding a light emitting portion and a plurality of light emitting diodes (LEDs) 53 which are solid light emitting elements are arranged as a light source ( There is provided a direct backlight device (backlight) 50 comprising a 52. The backlight device 50 is provided with a light guide member (plate or sheet) 54 on the LED substrate (mounting substrate) 52. The light guide member characterized by the present invention is enclosed in a backlight frame (chassis) 51.

The difference from the conventional direct type backlight device shown in Fig. 25 is that the light guiding member is disposed in the space between the light emitting diode and the diffusion member (plate). In addition, the space between the light emitting diode and the diffusion member (plate) can be reduced without increasing the thickness of the backlight. A diffusing member (plate or sheet) 55 for scattering and diffusing light to realize uniform brightness over the entire surface, and a prism sheet 56, 57, which is a diffraction grating film having a forward focusing effect, are provided on the light guide member. It is arranged as a stack of compensation sheets. Furthermore, the liquid crystal display module 60 includes liquid crystals on two glass substrates and polarizing plates (polarization filters) 62 and 63 which are laminated on each glass substrate of the liquid crystal panel 11 to limit light wave vibrations in any direction. The liquid crystal panel 61 which is interposed by is provided. Furthermore, the liquid crystal display device is provided with a peripheral member such as a driving LSI although this is not shown in the figure.

The liquid crystal panel 61 includes many kinds of parts although these are not shown in the figure. For example, liquid crystal panels are provided with two glass substrates, display electrodes, active elements such as thin film transistors, liquid crystals, spacers, sealants, alignment films, common electrodes, protective films, and color filters although they are not shown in the figure.

Moreover, any component unit of the backlight device 50 can be selected. For example, only a unit of the backlight frame 51 provided with the LED substrate 52 may be referred to as a backlight device (backlight), and an optical compensation sheet such as the diffusion member 53 and the prism sheets 54 and 55. Flow-through forms that do not include laminates of can be implemented.

The backlight frame 51 has a chassis structure made of a material such as aluminum, magnesium, iron, or a metal alloy thereof. Moreover, a white polyester film or the like having high reflection performance is adhered to the inner surface of the chassis structure, thereby including a function as a reflecting portion. The chassis structure is provided with a rear portion formed corresponding to the size of the liquid crystal display module 60 and side surfaces surrounding four sides of the rear portion. If necessary, heat sink structures such as cooling fins that dissipate heat are formed in the back or side portions in some cases.

Fig. 2 is a plan view showing a first embodiment of the surface light source device according to the present invention to which the light guide member according to the present invention is applied. 3 is a partially enlarged cross-sectional view showing a configuration along the line A-A in FIG.

2 and 3, the surface light source device 10 related to the present invention is shown as a whole.

As shown in FIG. 3, the surface light source device 10 according to the present invention is provided with a light emitting element mounting substrate 12, and a light emitting element 14 such as an LED is placed on the upper surface of the light emitting element mounting substrate 12. As shown in FIG. Is mounted on.

As shown in Fig. 2, a plurality of light emitting elements 14 are arranged on a top surface of the light emitting element mounting substrate 12 in a certain pitch in an array pattern.

Furthermore, the light guide member 16 made of transparent resin or the like is disposed on the upper surface of the light emitting element mounting substrate 12. As shown in Fig. 3, a recess 20 for a light emitting element is formed on the bottom surface 18 of the light guide member 16 at a position corresponding to the light emitting element 14, and the light emitting element 14 is a light emitting element. It is accommodated in the dragon recess 20.

The shape of the recess 20 for the light emitting element may be appropriately modified into a dome shape, a hemispherical shape, a conical shape, and the like.

A wiring pattern made of copper or the like is formed on the light emitting element mounting substrate 12, thereby controlling the light emission of the light emitting element 14 although it is not shown in the figure.

The light guiding member 16 is formed on the bottom surface of the light guiding member 16 at a position which is not near the light emitting element 14, and the light reflecting portion 22 is adjacent to the light emitting element 14. And a section that is not formed on the bottom surface of the light guide member 16 at the position at. Therefore, the intensity of diffusion upward from the bottom of the light guide member 16 near the light emitting element 14 is upward from the bottom of the light guide member 16 provided with the light reflecting portion 22 in its peripheral section. Is less than the strength of.

More specifically, in this embodiment, as shown in Figs. 2 and 3, the light reflecting portion 22 made of white paint or the like has the bottom surface of the light guide member 16 except for the region near the light emitting element 14. It is formed below almost the entire surface of 18.

As shown in Fig. 26, for the conventional surface light source device 300, as shown by arrow B, the light emitted from the LED lamp 302 is a reflecting portion immediately near the LED lamp 302. Guided upward from the top surface 314 of the light guide member 306 in a manner reflected by 312 and diffusely reflected.

As a result, as shown by the dashed-dotted line in the graph of FIG. 4, in the conventional surface light source device 300, from the upper surface 314 of the light guide member 306 in the section immediately above the LED lamp 302. The amount of light emitted and the brightness in the section directly above the LED lamp 302 is higher.

On the other hand, in the surface light source device 10 according to the present embodiment, since the light reflecting portion 22 is not formed near the light emitting element 14, as shown by the arrow C in FIG. Light emitted from the element 14 is totally reflected by the bottom face 18 of the light guide member 16 near the light emitting element 14 and guides directly between the top surface 26 and the bottom face 18 of the light guide member 16. do. Light is not guided upward from the upper surface 26 of the light guide member 16 by diffuse reflection.

As shown by arrow C in Fig. 3, the light reaching the light reflecting portion 22 is diffusely reflected upward from the light guide member 16 by diffusion reflection.

With the above configuration, as described above, the intensity of diffusion upward from the bottom of the light guide member 16 near the light emitting element 14 is upward from the bottom of the light guide member 16 in its peripheral section. Is less than the intensity of diffusion.

With this arrangement, as shown by the dotted lines in the graph of FIG. 4, the luminance around the section immediately above the light emitting element 14 is reduced compared to the conventional backlight light source and the luminance outside the section is compared to the conventional backlight light source. Increase, thereby improving uniform brightness.

The region 24 in the vicinity of the light emitting element 14 in which the light reflecting portion 22 is not formed is circular in this embodiment so that the distance from the light emitting element 14 to any edge of the region is constant. The shape of this area is not limited to the above shape. As shown in Fig. 5, the shape of this region is elliptical [Fig. 5 (A)], rectangular [Fig. 5 (B)], triangular [Fig. 5 (C)], arcuate [Fig. 5 (D)], polygonal. Or other shapes.

In addition, the periphery of the region 24 near the light emitting element from the center of the region 24 near the light emitting element 14 where the light reflecting portion 22 is not formed, that is, the light emitting element 14 as shown in FIG. The distance d1 to the edge is a solid line in the graph of FIG. 4 in which the luminance corresponds to the kind and luminance of the light emitting element 14, the kind and thickness of the light guide member 16, and the kind and film thickness of the light reflecting portion 22. It can be specified in a manner that can be nearly uniform, as shown by. The above area is not particularly limited.

For example, when the light emitting element 14 is an LED, the light guide member 16 is a transparent resin plate and has a thickness of 3 mm, the light reflecting portion 22 is white paint and has a thickness in the range of 5 to 100 μm. The distance d1 from the light emitting element 14 to the peripheral edge of the area near the light emitting element can be approximately 40 mm.

Moreover, as shown in FIG. 2, the distance between adjacent light emitting elements of the plurality of light emitting elements 14 is D and is constant from the center of the light emitting element 14 to the peripheral edge of the region 24 near the light emitting element. In the case where the distance is d, it is preferable that D / 4 is not less than d.

The light emitting element 14 is not particularly limited, but for example, an LED is preferable for a backlight light source of a liquid crystal display, since satisfactory color reproducibility, fast response and high quality images can be realized.

Although monochromatic LEDs can be used as LEDs, unit light emitting elements in which a plurality of kinds of light emitting elements having different emission colors are combined, such as LED chips of three primary colors of red, green and blue, that is, LED chips R emitting red light, green Packages of the so-called three-in-one type, in which the light emitting LED chip (G) and the blue light emitting LED chip (B) are used, can be suitably used. It is generated by mixing the colors.

As the light emitting element 14, an LED in which a hemispherical lens is provided on a molded packaged product in which the LED is sealed with a mold resin or an upper surface thereof can be used.

Even when a plurality of kinds of light emitting elements 14 having different light emitting colors are combined to be used in a three-in-one form, as shown in Fig. 6, the shape of the region 24 near the light emitting element 14 is In addition to the circular shape as shown in the embodiment of FIG. 2, the elliptical shape [Fig. 6 (A)], rectangle [Fig. 6 (B)], triangle [Fig. 6 (C)], It may be arcuate (Fig. 6 (D)), polygonal or other shape.

In this case, although this is not shown in the figure, the unit light emitting element is one R, two G and one B unit or two in addition to one R, one G and one B unit as described above. May be units of R, 2 G and 1 B, and the combination is not particularly limited.

Moreover, the unit light emitting element is not limited to three colors of red, green and blue as described above. For example, LED chips having so-called intermediate colors such as yellow, orange and cyan may be installed on one substrate to constitute LED chips of four, five or more colors.

Moreover, the light guide member 16 is not particularly limited when light propagates in the light guide member 16, and acrylic resin, polycarbonate resin, liquid crystal polymer and polystyrene resin may be used for the light guide member 16, for example. have. Members having a relatively thick plate shape or a relatively thin sheet shape may be suitably used individually or may be used stacked.

The shape of the recess 20 for the light emitting element is not particularly limited and may be, for example, conical, pyramidal, circular cylindrical, prismatic or hemispherical.

Moreover, the light reflecting layer 22 is not particularly limited and may be made of, for example, a metal foil such as aluminum foil, a metal thin film such as aluminum, gold, silver and platinum, or a white ink.

In the case of metal foils such as aluminum foils, the metal foils may be bonded by a transparent adhesive. Moreover, in the case of metal thin films such as aluminum, gold, silver and platinum, the metal thin films can be formed by methods such as vapor deposition, sputtering and electroless plating. Further, in the case of white ink, for example, an acrylic resin containing titanium dioxide may be used, and the acrylic resin may be coated by a method such as a dispenser, spray coating, powder coating, roll coater, curtain flow coater and paintbrush. .

Among the above means, coating of white ink is preferred from the viewpoint of ease of operation.

In this case, the thickness of the white ink is preferably in the range of 5 to 100 mu m in consideration of the light reflection effect.

Light diffusing agents such as resin beads and glass beads can be mixed in the white ink, thereby improving the degree of light diffusion.

Furthermore, in the second embodiment shown in FIG. 7, instead of forming the light emitting element recesses 20 on the light guide member 16 side, the light emitting element recesses 28 are provided with the light emitting element mounting substrate 12. The reflection portion 30 may be formed between the light emitting element mounting substrate 12 and the light guide member 16 through the insulating layer 21.

In this embodiment, a plurality of light emitting elements 14 are arranged on a top surface of the light emitting element mounting substrate 12 in a certain pitch in an array pattern. However, the number of light emitting elements 14 (one light emitting element is of course possible) and the arrangement shape thereof are not particularly limited and may be appropriately modified. For example, the light emitting elements 14 may also be arranged in a concentric circle pattern or in a staggered pattern.

The surface light source device 10 constructed as described above in accordance with the present invention is used as a light source such as advertising lamps, illumination and backlight for liquid crystal displays. For example, in the case where the surface light source device is used as a backlight for a liquid crystal display, as shown in Fig. 1, the liquid crystal display device arranges the liquid crystal panel on the upper surface of the light guide member 16 through the diffusion sheet and the prism sheet. Can be configured.

FIG. 8 is a plan view showing a third embodiment of a surface light source device related to the present invention to which a light guide plate according to still another embodiment of the present invention is applied. FIG. 9 is a partially enlarged sectional view showing a configuration along a line A-A shown in FIG.

Since the configuration of the surface light source device 10 related to the present embodiment is basically equivalent to the surface light source device 10 shown in Figs. 2 and 3, the elements equivalent to those described previously are similarly assigned with reference numerals. Detailed description of equivalent elements is omitted.

As shown in Figs. 8 and 9, with respect to the surface light source device 10 according to the present embodiment, the light transflective portion 32 in a circular shape is formed of the light guide member 16 corresponding to the light emitting element 14. It is further formed at a location on the top surface, ie in the area including the section in which the light emitting element 14 projects upward.

The shape of the light semitransmissive portion 32 is not particularly limited. The light transflective part 32 is circular in this embodiment so that the distance from the light emitting element 14 to all the edges of the light transflective part 32 is uniform, but the shape of the light transflective part is not limited to the above shape. Do not. Although not shown in the figure, similar to the shape of the area 24 near the light emitting element 14, the shape of the light transflective portion may be oval, rectangular, triangular, arcuate, polygonal or other shape.

Furthermore, the distance d2 from the light semitransmissive portion, i.e., the light emitting element 14 as shown in Fig. 9, to the peripheral edge of the light semitransmissive portion 32, has the luminance and the kind of the light emitting element 14 and the light guide member ( 16 corresponds to the kind and thickness of the light reflecting portion 22 and the kind and film thickness of the light reflecting portion 22 and the distance d1 from the light emitting element 14 to the peripheral edge of the region 24 near the light emitting element 14. It can be specified in a way that can be nearly uniform as shown by the solid line in the graph of. The above distance d2 is not particularly limited.

For example, when the light emitting element 14 is an LED, the light guide member 16 is a transparent resin plate and has a thickness of 3 mm, the light reflecting portion 22 is white paint and has a thickness in the range of 5 to 100 μm. The distance d1 from the light emitting element 14 to the peripheral edge of the region 24 near the light emitting element 14 is 40 mm, and the distance d2 from the light emitting element is preferably in the range of 2 to 30 mm. Is in.

The light semitransmissive portion 32 is for partial reflection of light emitted from the light emitting element 14 and the reflectance of the light is preferably in the range of 50 to 95% and more preferably in the range of 80 to 95%.

Moreover, the light semitransmissive portion 32 is not particularly limited and may be made of, for example, a metal thin film such as aluminum, gold, silver and platinum, or a white ink.

In the case of metal thin films such as aluminum, gold, silver and platinum, the metal thin films can be formed by methods such as vapor deposition, sputtering and electroless plating. Moreover, in the case of white ink, for example, an acrylic resin containing titanium dioxide can be used, and the acrylic resin can be coated by a method such as a dispenser and printing.

Among the above means, the coating of the white ink is easy and preferable in consideration of the operating characteristics.

When both the light transflective part 32 and the light reflecting part 22 are made of white ink, the film thickness of the light transflective part 32 is thinly adjusted so that a part of the light is transmitted in the light transflective part, The film thickness of the reflecting portion 22 is adjusted thick so that no light is transmitted through the light reflecting portion.

With the above configuration, as shown by arrow D in Fig. 9, the light guided from the light emitting element 14 to the upper surface of the light guiding member 16 directly above the light emitting element 14 is the light semitransmissive portion. Passes and attenuates 32, thereby reducing the brightness in this section.

With the above arrangement, as shown by the solid line in the graph of FIG. 4, the luminance around the section immediately above the light emitting element 14 is associated with the conventional backlight light source and the embodiment shown in FIGS. 2 and 3. It is reduced compared to the surface light source device 10, thereby obtaining a uniform brightness.

Fig. 10 is a plan view showing a fourth embodiment of the surface light source device according to the present invention to which the light guiding member according to another embodiment of the present invention is applied.

Since the configuration of the surface light source device 10 related to the present embodiment is basically equivalent to the surface light source device 10 shown in Figs. 2 and 3, the elements equivalent to those described previously are similarly assigned with reference numerals. Detailed description of equivalent elements is omitted.

In the surface light source device 10 according to the present embodiment, as shown in FIG. 10, a light scattering dot pattern is formed in the region 24 near the light emitting element 14 on the bottom surface 18 of the light guide member 16. do.

The light scattering dot pattern is formed in a lower manner in a section where the dot density of the light reflecting portion in the dot shape is closer to the light emitting element.

As described above, by forming a dot pattern in the area 24 near the light emitting element 14 on the bottom surface 18 of the light guide member 16, the area 24 and the light reflecting portion (near the light emitting element 14) ( The gap in diffusion intensity at the boundary between 22) can be alleviated.

The dot printing pattern is not particularly limited, but the dot printing pattern has a center at a position directly above the light emitting element 14 and the intensity of diffusion upward from the light guide member 16 is minimum at the center of the dot pattern and is further around. It is a larger circular pattern in close proximity.

Such light scattering dots may be formed by dot printing of scattering ink or by integral molding with the light guiding member 16.

The scattering ink is not particularly limited and for example ink containing resin beads or glass beads or the white ink described above can be used.

In the surface light source device 10 having such a configuration, the luminance around the section immediately above the light emitting element 14 is reduced, thereby obtaining a uniform luminance.

Even in this case, in the fifth embodiment shown in Fig. 11, similarly to the surface light source device 10 related to the embodiment shown in Figs. 8 and 9, the light semitransmissive portion 32 having a circular shape is formed of a light emitting element. It may be formed at a position on the upper surface of the light guide member 16 corresponding to (14), that is, at a position just above the light emitting element 14.

Although the light scattering dot pattern is formed in the region 24 in the vicinity of the light emitting element 14 on the bottom face 18 of the light guide member 16 in this embodiment, the minute non-uniform shape also reduces the intensity of diffusion instead of the dot shape. It may be formed on the bottom surface 18 of the light guide member 16 to control.

Fig. 12 is a plan view showing a sixth embodiment of the surface light source device according to the present invention to which the light guiding member according to another embodiment of the present invention is applied. FIG. 13 is a partially enlarged sectional view showing a configuration along a line A-A shown in FIG.

Since the configuration of the surface light source device 10 related to this embodiment is basically the same as that of the surface light source device 10 shown in Figs. 2 and 3, the same reference numerals are given to the elements equivalent to those previously described. .

12 and 13, the surface light source device 10 related to the present invention is shown as a whole.

As shown in FIG. 13, the surface light source device 10 according to the present invention is provided with a light emitting element mounting substrate 12, and a light emitting element 14 such as an LED is placed on the upper surface of the light emitting element mounting substrate 12. As shown in FIG. Is mounted on.

As shown in Fig. 12, a plurality of light emitting elements 14 are arranged on a top surface of the light emitting element mounting substrate 12 in a certain pitch in an array pattern.

Furthermore, the light guide member 16 made of transparent resin or the like is disposed on the upper surface of the light emitting element mounting substrate 12. As shown in Fig. 13, a recess 20 for a light emitting element is formed on the bottom 18 of the light guide member 16 at a position corresponding to the light emitting element 14, and the light emitting element 14 is a light emitting element. It is accommodated in the dragon recess 20.

The shape of the recess 20 for the light emitting element may be appropriately modified into a dome shape, a hemispherical shape, a conical shape, and the like. A wiring pattern made of copper or the like is formed on the light emitting element mounting substrate 12, thereby controlling the light emission of the light emitting element 14 although it is not shown in the figure.

Furthermore, the light guide member 16 has the intensity of diffused light upward from the bottom of the light guide member 16 near the light emitting element 14 of the light guide member 16 provided with the light reflecting portion 22 on its peripheral section. It is constructed in such a manner that it is smaller than the intensity of diffused light upward from the bottom face.

More specifically, in the present embodiment, as shown in Figs. 12 and 13, the light reflecting portion 22 having a function of reflecting and diffusing light has a light guide member 16 except for the region near the light emitting element 14. It is formed on the bottom face 18 of).

Furthermore, as shown in Fig. 13, it has a function of reflecting and diffusing light on the surface on the recess of the recess 20 for the light emitting element at a position above the light emitting element 14, and a part of the light is transmitted (light Transmittance: approximately 10 to 50%) The light transflective portion 11 is formed.

Here, the "position on the light emitting element" means at least in an area where the opposing light emitting element 14 (including the lens 13 when the lens is formed) protrudes upward, that is, in the section immediately above the light emitting element 14. It means the area that contains a part. Fig. 13 corresponds to the case where the light semitransmissive portion 11 is formed in a region almost equivalent to the entire region immediately above the light emitting element 14 (lens 13) on the surface of the recessed portion 20 for the light emitting element. do.

However, the light semitransmissive portion 11 may be disposed at a position corresponding to the light emitting element 14 in the surface on the recess of the light emitting element recess 20 in the light guide member 16. More specifically, the light semitransmissive layer 11 is not only located above the light emitting element 14 as described above (it is not necessary to form a layer on the entire surface directly above the light emitting element), but also the light emitting element. Comprising a position immediately above the light emitting element 14 in a range in which the light emitted from the light emitting element 14 and the light diffused and reflected by the light semitransmissive portion 11 are emitted to the outside from the recess 20 for the light emitting element. It can be formed in a larger area.

Further, the range in which the light semitransmissive portion 11 is formed, i.e., the distance d3 from the light emitting element 14 as shown in Fig. 13 to the peripheral edge of the light semitransmissive portion 11, has a high luminance. Type and brightness, type and thickness of light guide member 16, type and film thickness of light reflecting portion 22, distance from light emitting element 14 to peripheral edge of region 24 near light emitting element 14 (d1) and corresponding to the shape of the recess 20 for the light emitting element can be specified in a manner that can be almost uniform as shown by the solid line in the graph of FIG. The above range is not particularly limited.

A lens 13 is formed on the light emitting element 14 in a section fitted into the recess 20 for the light emitting element. However, it is of course also possible not to form any lenses 13.

As shown in Fig. 26, for the conventional surface light source device 300, as shown by the arrow B, the light emitted from the LED lamp 302 is a reflective layer immediately near the LED lamp 302. Guided upward from the top surface 314 of the light guide member 306 in a manner reflected by 312 and diffusely reflected.

As a result, for the conventional surface light source device 300, as shown by the dashed line in the graph of FIG. 4, the upper surface 314 of the light guide member 306 in the section directly above the LED lamp 302. The amount of light emitted from and the luminance in the section directly above the LED lamp 302 is higher.

On the other hand, for the surface light source device 10 according to the present embodiment, the light semitransmissive portion 11 is formed on the surface of the recessed portion of the light emitting element 20 in the light guide member 16. As a result, as shown in Fig. 13B, the light E1 emitted from the light emitting element 14 and from the section in which the light transflective part 11 is not present is guided as shown by the arrow E2. Reflected at the upper surface 26 of the member 16, the reflection is repeated between the upper surface 26 and the bottom surface 18 of the light guide member 16. Then, the light reaches the light reflecting portion 22 as shown by arrow E3 in Fig. 13A, and as shown by arrows C1 to C3 in Fig. 13A. Diffused and reflected. Finally, light is diffused and reflected upward from the light guide member.

Moreover, the light D emitted directly upward from the light emitting element 14 is reduced by the light semitransmissive portion 11. As a result, the light emitted from the upper surface of the light guide member 16 is reduced.

As a result, the luminance at the position immediately above the light emitting element 14 in the light guide member 16 can be suppressed.

Furthermore, since the light reflecting portion 22 is not formed on the bottom surface of the light guiding member near the light emitting element 14, as shown by arrow E1 in FIG. 13, the light emitted from the light emitting element 14 As shown by arrow E2, it is totally reflected by the bottom face 18 of the light guide member 16 near the light emitting element 14 and is directly between the top surface 26 and the bottom face 18 of the light guide member 16. You are guided. Light is not guided upward from the upper surface 26 of the light guide member 16 by diffuse reflection.

Light reaching the light reflecting portion 22 as shown by arrow E3 in FIG. 13 is diffusely reflected upward from the light guide member 16 by diffuse reflection as shown by arrows C1 to C3. do.

With the above configuration, as described above, the intensity of diffusion upward from the bottom of the light guide member 16 near the light emitting element 14 is determined by the light guide member provided with the light reflecting portion 22 in its peripheral section. It is smaller than the intensity of diffusion upward from the bottom face.

With the above configuration, as shown by the dotted line in the graph of FIG. 4, the luminance around the section immediately above the light emitting element 14 is reduced compared to the conventional backlight light source and the luminance at the outside of the section is instead conventional. It is increased compared to the backlight light source, thereby improving the uniform brightness.

The region 24 near the light emitting element 14 in which the light reflecting portion 22 is not formed has a circular shape in this embodiment so that the distance from the light emitting element 14 to any edge of the region is constant. The shape of the area is not limited to the above shape. As shown in Fig. 14, this shape is elliptical [Fig. 14 (A)], rectangular [Fig. 14 (B)], triangular [Fig. 14 (C)], arcuate [Fig. 14 (D)], polygonal or other It may be shaped.

Furthermore, from the region 24 near the light emitting element 14 where the light reflecting portion 22 is not formed, that is, from the light emitting element 14 as shown in FIG. 13 to the peripheral edge of the region 24 near the light emitting element. The distance d1 is represented by a solid line in the graph of FIG. 4 in which the luminance corresponds to the kind and luminance of the light emitting element 14, the kind and thickness of the light guide member 16, and the kind and film thickness of the light reflecting portion 22. It can be specified in such a way that it can be nearly uniform as shown. The above distance is not particularly limited.

For example, when the light emitting element 14 is an LED, the light guiding member 16 is a transparent resin plate and has a thickness of 3 mm, the light reflecting layer 22 is white paint and has a thickness in the range of 5 to 100 μm. The distance d1 from the light emitting element 14 to the peripheral edge of the region 24 in the vicinity of the light emitting element may be approximately 40 mm.

Furthermore, when the distance between the centers of adjacent light emitting elements of the plurality of light emitting elements 14 is D and the constant distance from the light emitting element 14 to the peripheral edge of the region 24 near the light emitting element is d, D It is preferable that / 4 is d or more.

The light emitting element 14 is not particularly limited, but for example, an LED is preferable for a backlight light source of a liquid crystal display, since satisfactory color reproducibility, high speed response, and high quality images can be realized.

Although monochromatic LEDs can be used as LEDs, unit light emitting elements in which a plurality of kinds of light emitting elements having different emission colors are combined, for example, LED chips of three primary colors of red, green and blue, that is, LED chips R emitting red light It is preferable to use a so-called three-in-one package in which the LED chip G emitting green light and the LED chip B emitting blue light are used, and a white color is generated by mixing these colors.

Even when a plurality of kinds of light emitting elements 14 having different light emitting colors are combined to be used in a three-in-one form, as shown in Fig. 15, the shape of the region 24 near the light emitting element is also an LED chip. In addition to the circle as shown in the embodiment of Fig. 12, the elliptical shape [Fig. 15 (A)], rectangle [Fig. 15 (B)], triangle [Fig. 15 (C)], and arch shape [Fig. 15 (D)], polygonal or other shape.

In this case, this is not shown in the figure, but the unit light emitting element is composed of one piece R, two pieces G and one piece R, one piece G and one piece B as described above. It may be a unit of one piece B or two pieces of R, two pieces of G and one piece of B, and the combination is not particularly limited.

Moreover, the unit light emitting element is not limited to three colors of red, green and blue as described above. For example, LED chips having so-called intermediate colors such as yellow, orange and cyan may be installed on one substrate to constitute LED chips of four, five or more colors.

Moreover, the light guide member 16 is not particularly limited when light propagates in the light guide member 16, and acrylic resin, polycarbonate resin, liquid crystal polymer and polystyrene resin may be used for the light guide member 16, for example. have.

Moreover, the light semitransmissive portion 11 has a function of reflecting and diffusing light and is not particularly limited in the case where a part of the light is transmitted within the light semitransmissive portion 11 (light transmittance: approximately 10 to 50%), for example Metal foils such as aluminum foil, metal thin films such as aluminum, gold, silver and platinum, or white ink.

Further, the light reflecting portion 22 is not particularly limited as long as it has a function of reflecting and diffusing light, and may be made of, for example, white ink.

Furthermore, a rubber molding in which a diffusion material made of titanium dioxide is mixed may be bonded to the inner surface of the recess 20 for the light emitting element, or may be printed on the inner surface of the recess 20 for the light emitting element. Or it can be blasted to form this.

In the case of metal foils such as aluminum foils, the metal foils may be bonded by a transparent adhesive. Moreover, in the case of metal thin films such as aluminum, gold, silver and platinum, the metal thin films can be formed by methods such as vapor deposition, sputtering and electroless plating. Further, in the case of white ink, for example, an acrylic resin containing titanium dioxide can be used, and the acrylic resin can be coated by a method such as a dispenser and printing.

Among the above means, the coating of the white ink is easy and preferable in consideration of the operating characteristics.

When both the light transflective part 11 and the light reflecting part 22 are made of white ink, the film thickness of the light transflective part 11 is thinly adjusted so that a part of the light is transmitted in the light transflective part, and the light reflection The film thickness of the part 22 is adjusted thick so that no light is transmitted in the light reflecting part.

Light diffusing agents such as resin beads and glass beads can be mixed in the white ink, thereby improving the light diffusing coefficient.

The shape of the recess for the light emitting element is not particularly limited and may be, for example, conical, pyramidal, circular cylindrical, prismatic or hemispherical.

In the case where the lens 13 is provided in the light emitting element 14, the lens 13 is not particularly limited in the case of having a surface which is transparent and has a specified curvature. For example, the lens 13 may be made of silicone resin or epoxy resin.

Furthermore, in the seventh embodiment shown in Fig. 16, a recess 28 for a light emitting element can be formed on the light emitting element mounting substrate 12 side, and the reflecting portion 30 forms the insulating layer 21. It may be formed between the light emitting element mounting substrate 12 and the light guide member 16.

In this embodiment, a plurality of light emitting elements 14 are arranged on a top surface of the light emitting element mounting substrate 12 in a certain pitch in an array pattern. However, the number of light emitting elements 14 (one light emitting element is of course possible) and the arrangement shape thereof are not particularly limited and may be appropriately modified. For example, the light emitting elements 14 may also be arranged in a concentric circle pattern or in a staggered pattern.

The surface light source device 10 constructed as described above in accordance with the present invention is used as a light source such as advertising lamps, illumination and backlight for liquid crystal displays. For example, in the case where the surface light source device is used as a backlight for a liquid crystal display, as shown in Fig. 1, the liquid crystal display device arranges the liquid crystal panel on the upper surface of the light guide member 16 through the diffusion sheet and the prism sheet. Can be configured.

Fig. 17 is a plan view showing an eighth embodiment of a surface light source device according to the present invention to which a light guiding member according to still another embodiment of the present invention is applied.

Since the configuration of the surface light source device 10 related to the present embodiment is basically equivalent to the surface light source device 10 shown in Figs. 2 and 3, the elements equivalent to those described previously are similarly assigned with reference numerals. Detailed description of equivalent elements is omitted.

In the surface light source device 10 according to the present embodiment, as shown in FIG. 17, as in the fourth embodiment, a light scattering dot pattern is formed on the bottom surface 18 of the light guide member 16. Is formed in the region 24 in the vicinity of the light emitting element 14.

The light scattering dot pattern is formed in a lower manner in a section where the dot density of the light reflecting portion in the dot shape is closer to the light emitting element.

By forming the dot pattern as described above, the difference in diffusion intensity at the boundary between the region 24 near the light emitting element 14 and the light reflecting portion 22 can be alleviated.

The dot printing pattern is not particularly limited, but the dot printing pattern has a center at a position directly above the light emitting element 14 and the intensity of diffusion upward from the light guide member 16 is minimum at the center of the dot pattern and is further around. It is a larger circular pattern in close proximity.

Such light scattering dots may be formed by printing of scattering ink or by integral molding with the light guide member 16.

The scattering ink is not particularly limited and for example ink containing resin beads or glass beads or the white ink described above can be used.

In the surface light source device 10 having such a configuration, the luminance around the section immediately above the light emitting element 14 is reduced, thereby obtaining a uniform luminance.

The light scattering dot pattern is formed in the region 24 in the vicinity of the light emitting element 14 on the bottom face 18 of the light guide member 16 in this embodiment, but the minute uneven shape also controls the intensity of the diffused light instead of the dot shape. It may be formed on the bottom surface 18 of the light guide member 16 to.

Example

(Example 1)

The unit light emitting element, in which the red, green, and blue LED chips of the 1 W class are combined as the light emitting element, is arranged in an array pattern as shown in FIG. 2 on the light emitting element mounting substrate 12 having a width of 115 mm by a length of 135 mm. Is placed.

A transparent plate made of an acrylic resin having a width of 115 mm × length of 135 mm and a thickness of 3 mm is prepared as the light guide member 16. A light emitting element recess 20 having a hemispherical shape having a radius of 2.5 mm is formed on the bottom face 18 of the light guide member 16 at a position just above the center of each light emitting element 14.

A white paint made of acrylic resin containing 50% titanium dioxide (solid material only) is coated on the bottom 18 of the light guide member 16 by spray coating in such a way that the film thickness is 100 μm. The light reflection part 22 is formed.

In this case, the light reflecting portion 22 is formed in a region other than the region 24 in the vicinity of the light emitting element 14. The region 24 near the light emitting element is formed in such a manner that the distance d1 from the center of the light emitting element 14 to the peripheral edge of the region 24 near the light emitting element is 40 mm (Fig. 18).

The distance D between adjacent light emitting elements 14 is 180 mm.

The transparent plate made of acrylic resin is then laminated and fixed in such a manner that the recess 20 for the light emitting element faces the light emitting element 14, thereby obtaining the surface light source device 10 according to the present invention (Fig. 3).

Subsequently, currents of 280 mA (red), 360 mA (green) and 120 mA (blue) are applied to the red LED, the green LED and the blue LED, respectively.

Thereby, the relative luminance is then used at a distance of 0.5 mm from the position O on the upper surface of the diffuser plate at a pitch of 0.5 cm in the horizontal direction by using a spectroradiometer CS-1000A (manufactured by Konica Minolta). Is measured. Relative luminance is measured with diffuser plate PC9391-50HLW (manufactured by Teijin Limited) disposed at 25 mm on the resin light guide member related to the present invention.

The measured results are in Table 1 and in the graph of FIG.

(Example 2)

A surface light source device 10 related to the present invention as shown in Fig. 19 is obtained similarly to Embodiment 1 except for the following features.

More specifically, as shown in Figs. 8 and 9, the circular light transflective portion 32 corresponds to the light emitting element 14 at the position on the upper surface of the light guide member 16, i.e., the light emitting element 14 ) Is further formed at the position just above.

A white paint made of acrylic resin containing 50% titanium dioxide (solid material only) is sprayed from the light emitting element 14 to the peripheral edge of the light transflective part 32 by spray coating in a manner of film thickness of 20 μm. It is coated on the upper surface of the light guide member with the distance d2 being 5 mm, thereby forming the light transflective part 32.

By this, the relative luminance is then measured at a distance of 0.5 mm from the position O on the upper surface of the diffuser plate directly above the light emitting element 14 at a pitch of 0.5 cm in the horizontal direction similarly to the first embodiment.

The measured results are in Table 1 and in the graph of FIG.

(Example 3)

A surface light source device 10 related to the present invention as shown in Fig. 20 is obtained similarly to Embodiment 1 except for the following features.

More specifically, the light semitransmissive portion 11 is formed on the surface on the recess of the recess 20 for the light emitting element.

A white paint made of acrylic resin containing 50% titanium dioxide is coated by spray coating in a manner that the film thickness is 20 占 퐉, thereby forming the light semitransmissive portion 11.

The range in which the light transflective portion 11 is formed, that is, the projection distance d3 from the center of the light emitting element 14 to the peripheral edge of the light transflective portion 11, shows that red, green, and blue LED chips are shown in FIG. It is approximately 1.8 mm to cover almost as shown.

A white paint made of acrylic resin containing 50% titanium dioxide is coated on almost the entire surface of the bottom 18 of the light guide member 16 by spray coating in such a manner that the film thickness is 200 μm, whereby light The reflecting portion 22 is formed.

In this case, the light reflecting portion 22 is formed in a region other than the region 24 in the vicinity of the light emitting element 14. The region 24 near the light emitting element is formed in such a manner that the distance d1 from the center of the light emitting element 14 to the peripheral edge of the region 24 near the light emitting element is 40 mm (Fig. 20).

The transparent plate made of acrylic resin is then laminated and fixed in such a manner that the recess 20 for the light emitting element faces the light emitting element 14, thereby obtaining the surface light source device 10 according to the present invention (Fig. 13).

Subsequently, currents of 280 mA (red), 360 mA (green) and 120 mA (blue) are applied to the red LED, the green LED and the blue LED, respectively.

Thereby, the relative luminance is then measured at a distance of 0.5 mm from the position O on the upper surface of the diffuser plate directly above the light emitting element 14 at a pitch of 0.5 cm in the horizontal direction.

The measured results are in Table 1 and in the graph of FIG.

(Comparative Example 1)

A surface light source device 10 as shown in Fig. 21 is obtained similarly to Embodiment 1 except for the following features.

More specifically, as shown in Fig. 21, the white paint made of acrylic resin containing 50% titanium dioxide (solid material only) is recessed for the light emitting element by spray coating in a manner that the film thickness is 100 m. It is coated on the entire surface of the bottom face 18 of the light guide member 16 except for (20), thereby forming the light reflecting portion 22. In this case, as in the first embodiment, the circularly shaped region 24 in the vicinity of the light emitting element in which the light reflecting portion 22 is not formed is substantially not formed, and 5 corresponds to the size of the light emitting element 14. Only a small missing portion 34 having a circular shape corresponding to the recess 20 for the light emitting element in a state having a diameter of mm is formed.

Thereby, the relative luminance is then measured at a distance of 0.5 mm from the position O on the upper surface of the diffuser plate directly above the light emitting element 14 at a pitch of 0.5 cm in the horizontal direction.

The measured results are in Table 1 and in the graph of FIG.

(Comparative Example 2)

A surface light source device 10 as shown in Fig. 22 is obtained similarly to Embodiment 1 except for the following features.

More specifically, as shown in Fig. 22, the white paint made of acrylic resin containing 50% of titanium dioxide (solid material only) is recessed for a light emitting element by spray coating in a manner that the film thickness is 100 m. It is coated on the entire surface of the bottom face 18 of the light guide member 16 except for (20), thereby forming the light reflecting portion 22. In this case, as in the first embodiment, the circularly shaped region 24 in the vicinity of the light emitting element in which the light reflecting portion 22 is not formed is substantially not formed, and 5 corresponds to the size of the light emitting element 14. Only a small missing portion 34 having a circular shape corresponding to the recess 20 for the light emitting element in a state having a diameter of mm is formed.

A white paint made of acrylic resin containing 50% titanium dioxide (solid material only) is sprayed from the light emitting element 14 to the peripheral edge of the light transflective part 32 by spray coating in a manner of film thickness of 20 μm. The distance d2 is coated on the upper surface of the light guide member, thereby forming the light transflective portion 32. In this case, the light semitransmissive portion 32 is formed in such a manner that its size is 4 mm in diameter smaller than the above defective portion 34 (Fig. 22).

Thereby, the relative luminance is then measured at a distance of 0.5 mm from the position O on the upper surface of the diffuser plate directly above the light emitting element 14 at a pitch of 0.5 cm in the horizontal direction.

The measured results are in Table 1 and in the graph of FIG.

Distance (cm) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 0 100 100 100 100 100 0.5 95.1 98 100 96.6 101.6 One 90.3 95.3 100 87.9 93 1.5 84.2 91 96.3 77.9 77.2 2 75.8 85.4 90.8 67.5 64.6 2.5 66 77.3 85.1 57 52.5 3 57.4 70 77.5 48 40.4 3.5 49.4 61 70 40 32.8 4 42 54.6 60.7 35 28 4.5 37.8 48.7 54.8 31 24.2 5 33.1 44 48 27 21.6

Table 1 and Fig. 23 show that the relative luminance at the outer side with respect to the position immediately above the light emitting element 14 is increased and uniform luminance is increased for the surface light source device 10 related to the present invention (example) compared to the comparative example. It has been found that it can be improved. In addition, the mixed color of RGB is also improved.

As mentioned above, although the preferred embodiment of the present invention has been described, the present invention is not limited to this embodiment, and various changes and modifications can be made without departing from the scope of the present invention. For example, the light guide member and the surface light source device related to the present invention are useful for mounting a plurality of light emitting elements having different light emission colors, but it is also possible to mount white light emitting elements that do not require mixing.

Claims (16)

A light guide member disposed on an upper surface of a light emitting element mounting substrate on which a light emitting element is mounted, and configured to diffuse and guide light emitted from the light emitting element upward; A light reflecting portion formed on a bottom surface of the light guide member at a position other than the light emitting element; And a section in which a light reflecting portion is not formed on a bottom surface of the light guiding member at a position near the light emitting element. The method of claim 1, A recess for a light emitting element in the light guide member at a position corresponding to the light emitting element; The light guide member further including the light semi-transmissive part on the surface part on the recessed part for said light emitting element. The method of claim 2, And the light transflective portion on the surface on the concave portion is formed at a position on the light emitting element. The method according to any one of claims 1 to 3, The light guide member is an area near the light emitting element, which is an area up to a constant distance from the light emitting element. The method according to any one of claims 1 to 4, The light guide member further includes a dot-shaped light reflecting portion in an area near the light emitting element so that the dot density of the light reflecting portion is lower in the section closer to the light emitting element. The method of claim 1, And a light semitransmissive portion at a position on an upper surface of the light guide member corresponding to the light emitting element. The method of claim 6, And the light transflective portion is formed on the upper surface of the light guide member at a position directly above the light emitting element. The method of claim 7, wherein The light transflective member is formed on the upper surface of the light guide member near the light emitting element at a predetermined distance from the light emitting element. The method according to any one of claims 1 to 8, A plurality of light emitting elements mounted on the light emitting element mounting substrate are disposed apart and a region near the light emitting element in which no light reflecting portion is formed is disposed at a plurality of positions of the bottom surface of the light guide member corresponding to the light emitting element. Light guide member. The method of claim 9, D / 4 when the distance between adjacent light emitting elements of the plurality of light emitting elements is D and the constant distance from the light emitting element to the peripheral edge of the region in the vicinity of the light emitting element in which the light reflecting portion is not formed is d / 4 Is a light guide member which is d or more. The method according to any one of claims 1 to 10, The light emitting element mounted on the light emitting element mounting substrate is constituted by a unit light emitting element in which various kinds of light emitting elements having different light emitting colors are combined, and an area near the light emitting element where no light reflecting portion is formed is the unit light emitting unit. The light guide member formed corresponding to an element. The method according to any one of claims 2 to 5, The light emitting element mounted on the light emitting element mounting substrate is constituted by a unit light emitting element in which various kinds of light emitting elements having different light emitting colors are combined, and the concave portion for the light emitting element is formed to correspond to the unit light emitting element. . The surface light source device of any one of Claims 1-12 arrange | positioned on the upper surface of the light emitting element mounting substrate in which the light emitting element is mounted. The method of claim 13, And said light emitting element is a light emitting diode. A display device comprising a display portion disposed on an upper surface of the surface light source device according to claim 13. The method of claim 15, And the display unit is a liquid crystal panel.

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