JP2006162718A - Diffusion light-condensing member and surface light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diffusion light-condensing member which can be easily constituted and lightly constituted in weight by a simple configuration, and a surface light source device. <P>SOLUTION: The surface light source device 10 includes a flatly arranged light source 11 and the flat diffusion light-condensing member 13 arranged above the light source. The diffusion light-condensing member 13 is integrally constituted, successively from the light source side, with a diffusion layer 14 provided with a diffusion function, a low-refractive index layer 15, and a light-condensing layer 16 provided with a light-condensing function. The surface light source device 10 is so constituted that the low-refractive index layer 15 is composed of material having the refractive index lower than that of the diffusion layer 14 and the light-condensing layer 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface light source device for backlighting a transmissive display device such as a liquid crystal panel.

  Conventionally, a transmissive display device such as a liquid crystal panel performs back illumination using a surface light source device from the back in order to obtain a brighter screen display. In particular, in the case of color liquid crystal panels used in personal computers and liquid crystal televisions, the aperture ratio due to the drive circuit is restricted and the light transmittance is reduced due to the color filter. It has become.

  Generally, such a surface light source device for back illumination is classified into a so-called side edge type and a direct type depending on the arrangement of light sources. In particular, a surface light source device for back-lighting a large display device such as a large television of 20 inches or more, for example, is a direct type that does not require a light guide plate and can be easily reduced in weight by being hollow. Is often used.

Such a direct type surface light source device is configured, for example, as shown in FIG.
In FIG. 4, the surface light source device 1 includes at least one, in the illustrated case, four linear light sources 2, a reflective surface 3 disposed below each linear light source 2, a linear light source 2 and a reflective surface 3. Is formed of a diffusion plate 4, a diffusion sheet 5, and a prism sheet 6 which are sequentially arranged above the substrate.

  The linear light source 2 is composed of, for example, a cold cathode tube or the like, and is arranged in parallel with each other at equal intervals so as to irradiate light on the entire upper light emitting surface A.

  The reflection surface 3 is configured as a diffuse reflection surface made of, for example, white paint or a foamed resin sheet, and is disposed below each linear light source 2 and emitted downward or sideward from the corresponding linear light source 2. The reflected light is reflected upward in the emission direction.

  The diffusing plate 4 is made of, for example, a translucent plate having a light diffusing pattern formed on the surface.

  The diffusion sheet 5 is prepared by adding and mixing a light diffusing agent in a resin serving as a base material. For example, a light diffusing agent such as calcium carbonate and titanium oxide, a partially crosslinked polymer fine particle, or a non-conductive polymer is added to a polycarbonate resin. It is formed by adding and mixing a fusible acrylic polymerization element, titanium oxide and a silicon compound.

  The prism sheet 6 is formed by injection molding, 2P method, compression molding, or the like from a transparent resin (for example, acrylic, polycarbonate, etc.) at least in the visible light region so as to have a microprism on the surface.

According to the surface light source device 1 configured as described above, when each linear light source 2 is turned on, the light emitted from each linear light source 2 is reflected directly or by the reflecting surface 3 and diffused by the upper diffusion plate 4. Then, the light is further diffused by the diffusion sheet 5, condensed by the prism sheet 6, and emitted upward.
As a result, various display devices (not shown) such as a liquid crystal panel disposed above the light emitting surface A are back-lit.
At that time, the light emitted from each linear light source 2 is diffused or condensed when passing through the diffusing plate 4, the diffusing sheet 5, and the prism sheet 6, thereby obtaining a back illumination with uniform brightness as a whole. Will be.

By the way, in Patent Document 1, a plurality of linear light sources arranged in parallel to each other, a semi-cylindrical reflector arranged below each linear light source, a diffusion plate and light arranged above the linear light source There is disclosed a liquid crystal display device provided with a back illumination device made of an optical film having a diffusing or condensing function.
According to this configuration, each linear light source and the corresponding reflector are configured as an integral type, and are configured to be detachable by sliding in the longitudinal direction. Thereby, replacement | exchange of a linear light source can be performed easily.

Further, Patent Document 2 includes a plurality of linear light sources arranged in parallel to each other, a reflecting plate arranged below the diffusion plate, a diffusion plate arranged above the diffusion plate, and a diffusion sheet arranged thereon. An illumination device comprising a prism sheet is disclosed.
According to this configuration, a gap is provided above the diffusion plate, or the diffusion sheet and / or the prism sheet is adhered to the upper surface of the diffusion plate, and the light-transmitting sheet is adhered to the lower surface of the diffusion plate. It has become. As a result, since the upper and lower surfaces of the diffusion plate are in direct contact with the outside air or sealed, there is no difference in temperature and humidity between the upper and lower surfaces, so the diffusion plate is deformed into a concave or convex shape with respect to the upper side. There is nothing to do. Therefore, the occurrence of uneven brightness in the back illumination due to the deformation of the diffusion plate can be suppressed.
JP-A-11-002813 JP-A-11-223812

However, for example, in the conventional surface light source device 1 shown in FIG. 4, in order to diffuse the light from the linear light source 2 and obtain uniform brightness, the diffusion plate 4 and the diffusion sheet 5 are necessary. The prism sheet 6 is necessary for improving the luminance.
For this reason, the diffusion plate 4, the diffusion sheet 5 and the prism sheet 6 are sequentially disposed above the linear light source 2, and the number of parts increases, the assembly process becomes complicated, and the cost increases. End up.
In addition, since the number of parts increases, the weight increases, particularly when used as a backlight for a large display device, which is against the request for weight reduction of the display device itself. .

On the other hand, in the above backlight device for a liquid crystal display device in Patent Document 1, an optical sheet is disposed above the diffusion plate, and this optical sheet is simply laminated above the diffusion plate. As a result, the number of parts similarly increases.
Further, in the above-described lighting device in Patent Document 2, a diffusion sheet and / or a prism sheet are arranged above the diffusion plate, and the diffusion sheet and / or the prism sheet are spaced above the diffusion plate. Although they are arranged in close contact with each other so as not to touch the outside air, they are not particularly integrated with the diffusion plate.
Therefore, in the illumination devices in these Patent Documents 1 and 2, the number of parts is similarly increased, and the assembly process is complicated, resulting in an increase in cost and an increase in weight.
The purpose of disposing the diffusion sheet and / or the prism sheet with a space above the diffusion plate is to make the environmental conditions of the upper surface and the lower surface of the diffusion plate the same, and the diffusion plate due to temperature difference or humidity difference. This is to prevent the convex or concave deformation.

Furthermore, these optical films or diffusion sheets and / or prism sheets are bonded to the diffusion plate, or optical materials having a two-layer structure consisting of a diffusion layer and a prism layer are integrated by using materials having substantially the same refractive index. Even if it is molded, the light condensing function by the prism is suppressed, and as a result, the meaning of the prism shape is lost.
On the other hand, when the concentration of the diffusing agent contained in the diffusion layer is lowered, the light condensing function is relatively improved, but the diffusion function is lowered accordingly.

  In view of the above, an object of the present invention is to provide a diffusion condensing member and a surface light source device that can be easily and lightly configured with a simple configuration.

  According to the first aspect of the present invention, the object is a substantially flat diffusing and condensing member which is disposed above a flatly arranged light source and constitutes a surface light source device, wherein the diffusing and condensing member is In order from the light source side, a diffusion layer having a diffusion function, a low refractive index layer, and a light collection layer having a light collection function are integrally formed, and the low refractive index layer includes the diffusion layer and the light collection layer. This is achieved by a diffusing and condensing member, characterized in that it consists of a lower refractive index material.

In the first aspect, light incident on the diffusion layer from below can be reliably diffused by the diffusion layer, and the low refractive index layer is disposed on the diffusion layer, whereby the diffusion layer The light incident on the low refractive index layer from the upper surface of the light is refracted in a direction in which the exit angle is diffused more than the incident angle due to the difference in refractive index, and the diffusion function of the diffusion layer is sufficiently exhibited. Become.
In addition, since the light passing through the low refractive index layer and entering the condensing layer is similarly incident at a relatively large incident angle, the condensing function is similarly sufficiently exhibited.

Accordingly, while maintaining the diffusion function and the light condensing function of the conventional diffusion layer and the separate light condensing layer, the diffusion layer and the light condensing layer are integrally formed with the low refractive index layer interposed therebetween. Since the number of parts is one, the number of parts is small, and the assembly is simple. Therefore, the part cost and the assembly cost are reduced.
Accordingly, the surface light source device can be configured with a simple configuration in which the diffusing and condensing member is simply disposed on the light source, and the number of parts constituting the surface light source device can be reduced, and the assembly process is simple. Thus, the parts cost and the assembly cost are reduced, and the entire surface light source device can be configured to be lightweight.

The diffusion condensing member according to the second aspect of the present invention is the diffusion condensing member according to the first aspect, wherein the diffusion layer is composed of a resin material in which a diffusing agent is added and mixed in a base material. Features.
In this second aspect, a diffusion function is provided by adding and mixing a diffusing agent in the base material.

The diffusion condensing member according to the third aspect of the present invention is the diffusion condensing member according to the first or second aspect, wherein the condensing layer is made of a resin material that is transparent at least in the visible light region, The upper surface and / or the lower surface has an optically processed shape for providing a light collecting function.
The diffusion condensing member according to the fourth aspect of the present invention is the diffusion condensing member according to the third aspect, wherein the optically processed shape is a quadratic curve such as a triangle, a trapezoid, a parabola, an elliptic arc, or a combination thereof. The cross-sectional shape is a prism shape swept in a direction perpendicular to the cross-section.
A diffusion condensing member according to a fifth aspect of the present invention is the diffusion condensing member according to the third aspect, wherein the optically processed shape is a lens array having a micropolygonal pyramid and an aspherical shape. .
A diffusion condensing member according to a sixth aspect of the present invention is the diffusion condensing member according to the third aspect, wherein the optically processed shape is coated with substantially spherical fine particles made of a transparent material such as resin or glass. It is characterized by being granted.

  In the third to sixth aspects, the upper and / or lower surfaces of the transparent material are preferably swept in a direction perpendicular to the cross section of a cross section of a quadratic curve such as a triangle, trapezoid or parabola, elliptic arc, or a combination thereof. By providing an optically processed shape that is applied by applying substantially spherical fine particles made of a transparent material such as a resin or glass, or a prism array, or a micro polygonal pyramid, an aspherical lens array It has a light collecting function.

A diffusion condensing member according to a seventh aspect of the present invention is the diffusion condensing member according to any one of the first to sixth aspects, wherein the low refractive index layer is a base constituting the diffusion layer and the condensing layer. It is characterized by being composed of a medium having a refractive index lower than that of the material and transparent at least in the visible light region.
In the seventh embodiment, a diffusion medium having a three-layer structure can be easily formed by providing a low refractive index transparent medium such as resin, glass, and air between the diffusion layer and the light collecting layer. An optical member can be configured.

A diffusion condensing member according to an eighth aspect of the present invention is the diffusion condensing member according to the seventh aspect, wherein the low refractive index layer is sealed between the diffusion layer and the condensing layer. It is a hollow part.
In the eighth aspect, the low refractive index layer is formed by the hollow portion defined between the diffusion layer and the light collecting layer, thereby reducing the cost of the three-layer structure with less material. The member can be configured.

According to the ninth aspect of the present invention, the object is to provide a flat light source, and the diffusion condensing member according to any one of the first to eighth aspects disposed above the light source. This is achieved by a surface light source device characterized by including.
In this ninth aspect, the surface light source device is configured by combining with the light source using the diffusion condensing member according to each aspect described above, so that the number of parts can be reduced and the assembly is easily performed. The part cost and the assembly cost can be reduced, and the surface light source device suitable for the back lighting of a large display device can be realized by reducing the overall weight.

  As described above, according to the present invention, the conventional diffusing plate, the optical member having the diffusing function and the condensing function are integrated with each other and configured as one part, so that the part cost and the assembly cost are reduced. In addition, when a surface light source device is configured in combination with a light source, the parts cost and assembly cost are reduced while maintaining the diffusion function and the light collecting function, and the weight can be further reduced. An optimum surface light source device can be provided as a back lighting device for the device.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 3.
The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. As long as there is no description of the effect, it is not restricted to these aspects.

1 and 2 show a configuration of an embodiment of a surface light source device according to the present invention.
1 and 2, the surface light source device 10 includes at least one, in the illustrated case, four linear light sources 11, a reflecting surface 12 disposed below each linear light source 11, the linear light source 11 and And a diffusing and condensing member 13 disposed above the reflecting surface 12.

  The linear light source 11 is composed of, for example, a cold cathode tube or the like, and is arranged flat in parallel with each other at equal intervals so as to irradiate light on the entire upper light emitting surface A.

  The reflection surface 12 is configured as a diffuse reflection surface made of, for example, white paint or a foamed resin sheet, and is disposed below each linear light source 11 and emitted downward or laterally from the corresponding linear light source 11. The reflected light is reflected upward in the emission direction.

  The diffusion condensing member 13 has a three-layer structure as shown in detail in FIG.

The diffusion layer 14 has a diffusion function and is generally composed of a resin material in which a diffusion agent is added and mixed in a base material.
Specifically, the diffusion layer 14 is formed of a resin material in which a transparent resin such as a polycarbonate resin is used as a base material and fine particles such as crosslinked polymethyl methacrylate are added and mixed.

The condensing layer 16 is made of a resin material that is transparent at least in the visible light region, such as polycarbonate resin, and has an optically processed shape 16a on its upper surface and / or lower surface, in the illustrated case, the upper surface. ing.
The optically processed shape 16a is a prism array obtained by sweeping a cross-sectional shape of a quadratic curve such as a triangle, trapezoid, parabola, elliptical arc, or a combination thereof in a direction perpendicular to the cross-section, or a micropolygonal, aspherical lens array. Alternatively, it is formed by applying spherical fine particles made of a transparent material such as resin or glass.

  On the other hand, the low refractive index layer 15 is composed of a medium having a lower refractive index than the diffusion layer 14 and the condensing layer 16 and a transparent medium at least in the visible light region, most preferably a sealed air layer. In the case of illustration, it is configured as a hollow portion sealed between the diffusion layer 14 and the light collecting layer 16.

  In the case shown in the drawing, the diffusion condensing member 13 having such a three-layer structure is sealed by the diffusion layer 14 and the condensing layer 16 by a molding method such as gas injection molding, two-color molding, or die slide molding. By defining the low refractive index layer 15 as a hollow portion, it can be easily integrally formed.

  The surface light source device 10 according to the embodiment of the present invention is configured as described above. When power is supplied to each linear light source 11 from the outside, each linear light source 11 is turned on, and light emitted from each linear light source 11 is emitted. Directly or after being reflected by the reflecting surface 12, the light is incident on the upper diffusion condensing member 13.

The light incident on the diffusion condensing member 13 is first diffused by the diffusion layer 14, then exits from the diffusion layer 14 and enters the low refractive index layer 15. At this time, since the light is incident on the low refractive index layer 15 made of a medium having a lower refractive index from the diffusion layer 14, the emission angle becomes larger than the incident angle at the interface between the diffusion layer 14 and the low refractive index layer 15. The diffusion effect by the layer 14 will be increased.
Further, the light incident on the condensing layer 16 from the low refractive index layer 15 is condensed based on the optically processed shape 16 a of the condensing layer 16 and then emitted upward from the upper surface of the condensing layer 16. become.

As a result, various display devices (not shown) such as a liquid crystal panel disposed above the light emitting surface A are back-lit.
At that time, the light emitted from each of the linear light sources 11 is sufficiently diffused and collected by the diffusing and condensing member 13, whereby a uniform and high luminance back illumination is obtained as a whole.

  In this case, in order to diffuse and condense the light emitted from the linear light source 11, the diffused light collecting member 13, which is an integrated part, is used, so that the surface light source device 10 is configured. The number of parts can be reduced, the parts cost and assembly cost can be reduced, and the diffusion condensing member 13 and the surface light source device 10 can be reduced in weight. For example, the backlight such as a large liquid crystal panel can be reduced in weight. Can fully respond to the request.

In the embodiment described above, the condensing layer 16 of the diffusing and condensing member 13 includes the optically processed shape 16a only on the upper surface thereof, but is not limited thereto, and optical processing is performed only on the lower surface or on the upper and lower surfaces. The shape 16a may be provided.
In the above-described embodiment, the low refractive index layer 15 is made of air as a hollow portion, but is not limited to this, and is made of an appropriate medium including other similar gases, liquids, and solids. It is clear that it is good.

Thus, according to the present invention, it is possible to provide a diffusion condensing member and a surface light source device that can be easily and lightly configured with a simple configuration.
The surface light source device according to the present invention can be used as an illumination device such as a liquid crystal panel backlight, a back illumination such as a translucent sign printed on a transparent film, etc., or a desktop spot illumination.

It is a schematic sectional drawing which shows the structure of one Embodiment of the surface light source device by this invention. It is a schematic perspective view which shows the external appearance of the surface light source device of FIG. It is sectional drawing of the diffusion condensing member used with the surface light source device of FIG. It is a schematic sectional drawing which shows the structure of an example of the conventional surface light source device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Surface light source device 11 Linear light source 12 Reflecting surface 13 Diffusion condensing member 14 Diffusion layer 15 Low refractive index layer (hollow part)
16 Condensing layer

Claims (9)

A substantially flat diffusion condensing member that is arranged above a flatly arranged light source and constitutes a surface light source device,
The diffusion condensing member is composed of a diffusion layer having a diffusing function, a low refractive index layer, and a condensing layer having a condensing function in order from the light source side,
A diffusion condensing member, wherein the low refractive index layer is made of a material having a lower refractive index than the diffusion layer and the condensing layer.   2. The surface light source device according to claim 1, wherein the diffusion layer is made of a resin material in which a diffusing agent is added and mixed in a base material.   The condensing layer is made of a transparent resin material at least in the visible light region, and has an optically processed shape for providing a condensing function on the upper surface and / or the lower surface thereof. The surface light source device according to claim 1 or 2.   The optically processed shape is a prism shape obtained by sweeping a cross-sectional shape of a triangle, trapezoid or parabola, a quadratic curve such as an elliptical arc, or a combination thereof in a direction perpendicular to the cross-section. The surface light source device described.   4. The surface light source device according to claim 3, wherein the optically processed shape is a micropolygonal pyramid, aspherical lens array.   4. The surface light source device according to claim 3, wherein the optically processed shape is provided by applying substantially spherical fine particles made of a transparent material such as resin or glass.   The low-refractive index layer is made of a transparent medium at least in the visible light region having a lower refractive index than that of the base material constituting the diffusion layer and the light-collecting layer. The surface light source device according to any one of the above.   The surface light source device according to claim 7, wherein the low refractive index layer is a sealed hollow portion defined between the diffusion layer and the light collection layer.   A surface light source device comprising: a light source arranged flatly; and the diffusion condensing member according to claim 1 arranged above the light source.

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