KR100776863B1 - Surface light source unit and light guide using it - Google Patents

Abstract

A surface light source device of an edge light type that prevents a decrease in luminance of a light incident cross section side corner portion of a light guide light exit surface, and that does not deteriorate on display even when observed from an inclined direction, comprising: a primary light source 1, There is provided a surface light source device having a plate-shaped light guide 3 having a light incident end face 31, a light exit face 33, and a back face 34. Here, the frame 7 which covers the periphery of the light guide light emitting surface 33 and defines the effective light emitting portion F is provided. On the light diffusing light emitting surface 33, as a region other than the region corresponding to the light emitting portion of the primary light source 1, at least a part of the region close to the light incident end surface 31 or the side cross section adjacent thereto, In the general light diffusing region that occupies most of the region corresponding to the effective light emitting portion F, a high light diffusing region having high light diffusing property is formed. Most of the high light diffusing region is located outside the region corresponding to the effective light emitting portion F. As shown in FIG.

Description

Surface light source device and light guide used for this {SURFACE LIGHT SOURCE UNIT AND LIGHT GUIDE USING IT}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge light type surface light source device and a light guide for use therein, and more particularly to a surface light source device intended to reduce the confirmation of luminance unevenness and a light guide for use in the same. The surface light source device of the present invention is a display panel of various types of devices such as a backlight of a liquid crystal display device used as a monitor such as a portable notebook, a display unit such as a liquid crystal television or a video integrated liquid crystal television, or a portable telephone. Backlight of a relatively small liquid crystal display device used as an indicator, or backlight of a liquid crystal display device used as a signboard or a signboard in a station or a public facility, or a traffic display on a highway or a general road. It is suitable for the backlight of the liquid crystal display device used as display devices, such as these.

The liquid crystal display device is widely used as a monitor of a portable notebook or the like, or as a display unit such as a liquid crystal television or a video integrated liquid crystal television, and other various fields. The liquid crystal display device basically consists of a backlight and a liquid crystal display element. As a backlight, the edge light system is used a lot from the viewpoint of the compactness of a liquid crystal display device. Conventionally, as an edge light backlight, at least one cross section of a rectangular plate-shaped light guide is used as a light incidence cross section, and a linear or rod-shaped primary light source such as a straight tube fluorescent lamp is disposed in accordance with the light incidence cross section. It is widely used to introduce the light generated from the primary light source into the light guide from the light incidence end face of the light guide, and to emit it from the light output plane which is one of the two main surfaces of the light guide.

By the way, in recent liquid crystal display devices, the ratio of the display screen dimension with respect to the external size is made to be as large as possible, and to increase the display efficiency. Therefore, even in the surface light source device, the ratio of the size of the light emitting surface with respect to its external size is made as large as possible, that is, the structural portion ("liquid smoke") existing in the frame shape around the light emitting surface is also called. It is desired to make the dimensions of the () as small as possible. In that case, it is necessary to reduce the dimension of the linear or rod-shaped primary light source arranged along the light incident cross section of the light guide. Reduction of this dimension is achieved by reducing the width of the primary light source, i.e., slimming, on one side, and shortening the length of the primary light source, i.e., shorter than the opposing light guide cross section.

Nevertheless, when attempting to realize the reduction of the length of the primary light source, the following new problems arise. That is, a socket is attached to at least one end of the primary light source, and this end is a non-light emitting part which does not emit light in reality. For this reason, as a result of the said dimension reduction, a non-light emitting part exists in the position which opposes a light incidence end surface, and the amount of light which exits from the light exit surface of the corner part of the light guide body corresponding to this non-light emitting part becomes small, Luminance decreases, resulting in luminance unevenness.

In order to solve such a problem, for example, Japanese Patent Laid-Open No. 2002-169033 (Patent Document 1) discloses a region in which the luminance is relatively low on the light exit surface of the light guide plate, for example, both corners of the light incident side. It is disclosed to superimpose and install a minute square signal on the side edge. For example, Japanese Unexamined Patent Publication No. 2002-258057 (Patent Document 2) describes an average inclination angle near each corner where the luminance is relatively low on the light exit surface of the light guide, and the average inclination angle of the other portion. It is disclosed to make larger.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-169033

Patent Document 2: Japanese Patent Laid-Open No. 2002-258057

In both Patent Document 1 and Patent Document 2, a square time signal is formed or an average inclination angle is increased in a region where luminance decreases in the light exit surface or the light exit surface. Although it is possible to prevent the decrease in luminance at the corner portion of the light guide end face side of the light guide surface by this method, the rectangular time signal is observed when observed from the inclined direction with respect to the light exit face normal direction. It has been found that deterioration of the display image may be caused when forming an image, increasing the average inclination angle, or making one region stand out and shining, and when used as a backlight of a display device.

Here, in order to increase the ratio of the light emitting surface dimension with respect to the external size, the present invention prevents a decrease in the luminance of light guide end face side corners and the like of the light guide light exit surface caused by reducing the liquid lead dimension, An object of the present invention is to provide an edge light type surface light source device without deterioration of the display image even when observing from the inclined direction when used as a backlight. It is also an object of the present invention to provide a light guide for a surface light source device which is used in such a surface light source device and contributes to the realization of its characteristic function.

Summary of the Invention

According to the present invention, to solve the above problems,

It has a primary light source, the light incident surface which guides the light which generate | occur | produces from the said primary light source, and also the light incident cross section into which the light emitted from the said primary light source enters, the light exit surface which the guided light exits, and the back surface opposite to the said light exit surface. In the surface light source device provided with a light guide,

And a frame body covering the periphery of the light emitting surface of the light guide and defining an effective light emitting portion of the surface light source device, wherein at least one of the light emitting surface and the rear surface of the light guide has light diffusing property. At least one of the light emitting surface and the back surface having the light diffusing property is a region other than a region corresponding to the light emitting portion of the primary light source, and a region adjacent to the light incident cross section or a side cross section adjacent thereto. At least a portion of the light diffusing region having a high light diffusivity is formed in a general light diffusing region which occupies most of the region corresponding to the effective light emitting portion, and the high light diffusing region is mostly the effective light emitting portion. A surface light source device is provided, wherein the surface light source device is located outside the region corresponding to the region and / or within the low luminance region corresponding to the non-light emitting portion of the primary light source. .

In one aspect of the present invention, an intermediate light diffusive region having a light diffusivity in the middle of these regions is located between the high light diffusing region and the general light diffusing region. In one aspect of the present invention, at least a part of the high light diffusing region is located corresponding to at least one corner portion or the vicinity of the side of the light incident cross section of the light guide. In one aspect of the present invention, the light diffusivity is imparted by roughening at least one of the light exit surface and the back surface.

In one aspect of the present invention, the surface light source device is disposed on a light exit surface of the light guide member, and further includes a light deflection element on which the light exiting from the light exit surface is incident and a light exit surface on the opposite side thereof. It is equipped with more. In one aspect of the present invention, the optical deflecting element has a plurality of prism rows extending along the light incidence cross section of the light guide on the light incident surface and arranged in parallel with each other, wherein each of the prism rows It has a 1st prism surface into which light in the light exit surface of a light guide body enters, and a 2nd prism surface in which incident light is reflected internally.

In one aspect of the present invention, the primary light source has a linear shape and has a non-light emitting portion located at least on one end thereof facing the light incident cross section of the light guide. In one aspect of the present invention, at least a portion of the high light diffusing region is located corresponding to the non-light emitting portion of the primary light source.

In 1 aspect of this invention, the said high light-diffusion area | region is the average value of the inclination-angle measured by the super-depth shape measuring microscope of 8 degree | times or more and 25 degrees or less. In one aspect of the present invention, the high light-diffusion region has 30% or more of components having an inclination angle of 10 degrees or more in the frequency distribution of the inclination angle measured by a super-depth shape measuring microscope. In one aspect of the present invention, the high light diffusivity region has a Ra (center line average roughness) of 0.35 µm or more and 0.6 µm or less as measured by an ultra-depth shape measuring microscope. In 1 aspect of this invention, Rz (ten point average roughness) measured with the super-depth shape measuring microscope of the said high light-diffusion area | region is 3.5 micrometers or more and 12 micrometers or less.

In 1 aspect of this invention, the said average light-diffusion area | region is the average value of the inclination-angle measured by the super-depth shape measuring microscope of 4 degrees or more and 12 degrees or less. In 1 aspect of this invention, the said intermediate light-diffusion area | region is 5%-40% of components of the inclination-angle 10 degree or more in the frequency distribution of the inclination angle measured with the super-depth shape measuring microscope. In one aspect of the present invention, the intermediate light diffusive region has a Ra of 0.18 µm or more and 0.43 µm or less as measured by an ultra-depth shape measuring microscope. In one aspect of the present invention, the intermediate light diffusive region has a Rz of 1.6 µm or more and 4.0 µm or less as measured by an ultra-depth shape measuring microscope.

Effects of the Invention

According to the surface light source device of the present invention as described above, the light exit surface or the back surface of the light guide is a region other than the region corresponding to the light emitting portion of the primary light source, and is located in the light incident end surface or in a region adjacent to the side cross section adjacent thereto. At least a portion of the light diffusing region having a high light diffusing property is formed in the general light diffusing region which occupies most of the region corresponding to the effective light emitting portion, and most of the high light diffusing region is preferably all of the above. Since it is located outside the region corresponding to the effective light emitting portion and / or in the low luminance region corresponding to the non-light emitting portion of the primary light source, the primary light is opposed to the light incident end surface side corner portion of the light guide surface according to the reduction of the liquid smoke dimension. Even when the non-light emitting portion of the light source is located, the decrease in luminance at the effective light emitting portion close thereto is prevented, and as a backlight of the display device. The surface light source device of the edge light system which does not deteriorate the image quality at the time of observation of the display image from the inclination direction at the time of using, and the light guide body used for it are provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a typical partial notch partial perspective view which shows one Embodiment of the surface light source device by this invention.

FIG. 2 is a partially cutaway plan view of the surface light source device of FIG. 1.

3 is a schematic diagram showing the shape of light deflection by the light deflection element.

4 is a schematic partial cross-sectional view of a liquid crystal display device comprising the surface light source device and the transmissive liquid crystal display element of FIG. 1.

FIG. 5 is a schematic diagram showing a relationship between the primary light source and each light diffusing region of the light guide surface.

6 is an explanatory diagram of a low luminance region of a light guide corner portion;

It is explanatory drawing of the modification of a light guide.

8 is an explanatory diagram of a modification of the light guide.

9 is an explanatory diagram of a modification of the light guide.

It is explanatory drawing of the modification of a light guide.

It is explanatory drawing of the modification of a light guide.

It is explanatory drawing of the modification of a light guide.

It is explanatory drawing of the modification of a light guide.

It is explanatory drawing of the modification of a light guide.

Explanation of the sign

1: primary light source 1a: light emitting tube

1b: socket 2: light source reflector

3: light guide 4: light deflecting element

5 light reflecting element 7 frame

8: liquid crystal display element 31: light incident cross section

32: side cross-section 33: light exit surface

34: back side 41: light incident surface

42: light exit surface 81: image forming portion

82: frame portion A: general light diffusion region

B: high optically diffused region C: intermediate light diffused region

D: low luminance region F: effective light emitting portion

F ': area outside the effective light emitting part G: display part

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

BRIEF DESCRIPTION OF THE DRAWINGS It is a typical partial notch partial perspective view which shows one Embodiment of the surface light source device by this invention, and FIG. 2 is a partially notch top view. As shown in the drawing, the surface light source device of the present embodiment includes a light guide 3 having at least one side cross section as a light incident end face 31 and having one surface substantially orthogonal to the light exit face 33. ) And a linear primary light source 1 disposed opposite to the light incident end face 31 of the light guide 3 and covered with the light source reflector 2, and disposed on the light exit surface of the light guide 3. The light deflecting element 4, the light reflecting element 5 disposed opposite to the back surface 34 on the side opposite to the light exit surface 33 of the light guide 3, and the peripheral portion of the light deflecting element 4. It comprises the frame 7 which covers the periphery of the light exit surface of the light guide 3, and defines the effective light emission part F of a surface light source device by covering. The frame 7 constitutes a casing of the surface light source device.

The light guide 3 is arrange | positioned in parallel with XY surface, and has a rectangular plate shape as a whole. The light guide 3 has four cross sections, among which at least one side cross section of a pair of side cross sections parallel to the YZ plane is referred to as light incident cross section 31. The light incident end face 31 is disposed to face the primary light source 1, and the light generated from the primary light source 1 enters the light guide 3 from the light incident end face 31. In the present invention, for example, the light source may be disposed opposite to the other side end surface such as the side end surface 32 on the side opposite to the light incident end surface 31.

The two main surfaces that are substantially orthogonal to the light incident end face 31 of the light guide 3 are located substantially parallel to the XY plane, respectively, and one surface (the upper surface in the drawing) becomes the light exit surface 33. . At least one of the light exit surface 33 or the rear surface 34 of the light exit surface 33 is provided with a directional light exit mechanism comprising a rough surface, thereby guiding the light incident from the light incident end surface 31 into the light guide 3. The light having directivity is emitted from the light exit face 33 in the light incident end face 31 and in the plane (XZ plane) orthogonal to the light exit face 33. The angle which the direction (peak light) of the peak of the emission light intensity distribution in this XZ surface distribution makes with the light emission surface 33 is made into (alpha). In most of the effective light emission units F, the angle α is, for example, 10 degrees to 40 degrees, and the full width at half maximum of the emitted light intensity distribution is, for example, 10 to 40 degrees. The detail of the rough surface formed in the light output surface 33 or the back surface 34 of the light guide 3 is mentioned later.

In addition, in order to control the directivity in the surface (YZ surface) parallel to the primary light source 1 of the outgoing light from the light guide 3 to the main surface except that the directional light output mechanism is not provided, It is preferable to form a lens surface in which a plurality of lens rows are arranged which extend in a substantially vertical direction (X direction) with respect to 31). In the embodiment shown in FIG. 1, an array of a plurality of lens rows is formed on a light exit surface 33 and extends in a substantially vertical direction (X direction) with respect to the light incident end surface 31 on the back surface 34. A lens row forming surface is formed. In the present invention, the lens row forming surface may be formed on the light exit surface 33 and the rear surface 34 may be roughened, as opposed to the embodiment shown in FIG. 1.

As shown in FIG. 1, when the lens row forming surface is formed on the back surface 34 or the light output surface 33 of the light guide 3, as the lens row, a prism row and a lenticular lens extending substantially in the X-direction. Although a row, a V-shaped groove, etc. are mentioned, it is preferable to make the shape of a YZ cross section into a substantially triangular prism row.

In the present invention, when the prism row forming surface is formed on the back surface 34 of the light guide 3 as the lens row forming surface, the vertex angle is preferably in the range of 85 to 110 degrees. This makes it possible to properly collect the light emitted from the light guide 3 by setting the vertex angle in this range, and more preferably in the range of 90 to 100 degrees in order to improve the luminance as the surface light source device. to be.

In the light guide of the present invention, the top portion of the prism row is aimed at accurately producing a desired prism row shape, obtaining stable optical performance, and suppressing abrasion and deformation of the prism top at the time of assembly work or use as a light source device. You may form a flat part or a curved part in the

Moreover, in this invention, it uses together with the light output mechanism formed in the above-mentioned light output surface 33 or its back surface 34, The directional light output mechanism by mixing and disperse | distributing light-diffusing microparticles in a light guide body is provided. You may add.

The light incidence end face 31 is preferably roughened in order to adjust the area of light in the XY plane and / or in the XZ plane. As a method of forming a rough surface, a method of cutting with a ply tool or the like, a method of grinding with a grindstone, sandpaper, buff, or the like, a method of blasting, electric discharge, electropolishing, chemical polishing, or the like can be given. Examples of the blast particles used for blasting include spherical ones such as glass beads and polygonal ones such as alumina beads, but those using polygonal ones are preferable because they can form a rough surface having a great effect of widening light. . Anisotropic roughening surface can be formed by adjusting the cutting direction of cutting and polishing. In order to adjust the width of light in the XY plane, the machining direction in the Z direction can be adopted to form the near-surface irregularities in the Z direction, and in the Y direction to control the width of the light in the XZ plane. Can be used to form the near-surface irregularities in the Y direction. Although this roughening process can be performed directly to the light incidence cross section of a light guide, the part corresponded to the light incidence cross section of a metal mold | die, and can also transfer this at the time of shaping | molding.

As for the degree of roughening of the light incident cross section 31, in the light-guide thickness direction, the average inclination angle (theta) a is 1 degree-5 degrees, the center line average roughness (Ra) is 0.05-0.5 micrometer, and the ten point average roughness (Rz) is It is preferable that it is 0.5-3 micrometers. This is because by setting the degree of roughening of the light incident end face 31 in this range, it is possible to suppress the occurrence of light and dark bands on the light exit surface, and to make it difficult to see the bright and dark lines. Average inclination angle (theta) a becomes like this. More preferably, it is the range of 2 degrees-4.5 degrees, Especially preferably, it is the range of 2.5 degrees-3 degrees. Center line average roughness Ra becomes like this. More preferably, it is 0.07-0.3 micrometer, Especially preferably, it is the range of 0.1-0.25 micrometer. Ten-point average roughness Rz becomes like this. More preferably, it is the range of 0.7-2.5 micrometers, Especially preferably, it is the range of 1-2 micrometers. In the longitudinal direction, the degree of roughening of the light incident end surface 31 is, for the same reason as described above, the average inclination angle θa is 1 degree to 3 degrees, the center line average roughness Ra is 0.02 to 0.1 µm, and the ten point average. It is preferable that roughness Rz is 0.3-2 micrometers. The average inclination angle θa is more preferably in the range of 1.3 to 2.7 degrees, and particularly preferably 1.5 to 2.5 degrees. The centerline average roughness Ra is more preferably in the range of 0.03 to 0.08 µm, particularly preferably 0.05 to 0.07 µm. Ten-point average roughness Rz becomes like this. More preferably, it is 0.4-1.7 micrometers, Especially preferably, it is the range of 0.5-1.5 micrometers.

As the light guide 3, it is not limited to the shape shown in FIG. 1, The thing of various shapes, such as the wedge shape of a light incident cross section side, can be used.

The light deflecting element 4 is disposed on the light exit surface 33 of the light guide 3. The two main surfaces 41 and 42 of the optical deflecting element 4 are arranged in parallel with each other as a whole, and are respectively located in parallel with the XY plane as a whole. One of the main surfaces 41 and 42 (the main surface located on the light exit surface 33 side of the light guide 3) is called the light incident surface 41, and the other is called the light exit surface 42. The light exit surface 42 is a flat surface parallel to the light exit surface 33 of the light guide 3. The light incident surface 41 is a prism row forming surface in which a plurality of prism rows extending in the Y direction are arranged in parallel with each other. The prism row forming surface may be provided with a relatively narrow bottom flat portion (e.g., a flat portion having a width equal to or smaller than the X-direction dimension of the prism row) between adjacent prism rows, but it improves light utilization efficiency. From the above, it is preferable to arrange the prism rows continuously in the X direction without providing the bottom flat portion.

3, the shape of the optical deflection by the optical deflection element 4 is schematically shown. 3 shows an example of the traveling direction of peak light (light corresponding to the peak of the emitted light distribution) from the light guide 3 in the XZ plane. The peak light emitted obliquely from the light exit surface 33 of the light guide 3 at an angle α is incident on the first prism face of the prism row and totally internally reflected by the second prism face, so that the normal of the light exit surface 42 is almost normal. Eject in the direction of. In addition, within the YZ plane, a sufficient improvement in the luminance in the direction of the normal line of the light exit surface 42 can be achieved in a wide range of regions by the action of the prism heat of the light guide body 34 as described above.

The shape of the prism face of the prism array of the optical deflection element 4 is not limited to a single plane, but can be, for example, a cross-sectional convex polygonal shape or a convex curved shape, whereby high brightness and narrow field of view can be achieved. .

In the optical deflecting element 4, the top portion of the prism row is used for the purpose of accurately producing a desired prism shape, obtaining stable optical performance, and suppressing abrasion and deformation of the prism top portion at the time of assembly work or use as a light source device. The top flat portion or the top curved surface portion may be formed in the. In this case, the width of the top flat portion or the top curved surface portion is preferably 3 μm or less, from the viewpoint of suppressing the occurrence of a nonuniform pattern of luminance due to a decrease in luminance as a surface light source device or sticking phenomenon, more preferably. The width | variety of a top part flat part or a top part curved part is 2 micrometers or less, More preferably, it is 1 micrometer or less.

The primary light source 1 is a linear light source extending in the Y direction, and as the primary light source 1, for example, a fluorescent lamp or a cold cathode tube can be used. In this case, as shown in FIG. 1, the primary light source 1 can be provided not only in the case where it is opposite to one side end surface of the light guide 3, but also in the side end surface of the opposite side as needed.

The light source reflector 2 guides the light of the primary light source 1 to the light guide 3 with less loss LA. As the material, for example, a plastic film having a metal vapor deposition reflective layer on its surface can be used. As shown, the light source reflector 2 avoids the light deflecting element 4 from the outer edge of the light reflecting element 5 from the outer surface of the primary light source 1 to the light exit surface edge of the light guide 3. It is wound around wealth. The other light source reflector 2 may be wound around the exit surface of the light deflecting element 4 from the outer surface of the edge of the light reflection element 5 via the outer surface of the primary light source 1. It is also possible to attach the same reflecting member as the light source reflector 2 to the side cross section other than the light incident end face 31 of the light guide 3.

As the light reflection element 5, for example, a plastic sheet having a metal vapor deposition reflection layer on its surface can be used. In the present invention, it is also possible to use a light reflection layer formed by metal deposition or the like on the back surface 34 of the light guide 3 instead of the reflective sheet as the light reflection element 5.

The light guide 3 and the light deflecting element 4 of the present invention can be made of a synthetic resin having a high light transmittance. Examples of such synthetic resins include methacrylic resins, acrylic resins, polycarbonate resins, polyester resins, and vinyl chloride resins. In particular, methacryl resin is excellent and optimal in the height of light transmittance, heat resistance, mechanical properties, and molding processability. As such methacryl resin, it is resin which has methyl methacrylic acid (methacrylic acid) as a main component, and it is preferable that methyl methacrylic acid (methacrylic acid) is 80 weight% or more. In the case of forming a surface structure such as a rough surface or a hairline of the light guide 3, the light deflecting element 4 and the light diffusing element 6, or a surface structure such as a prism row or a lenticular lens row, a transparent synthetic resin plate May be formed by hot pressing using a mold member having a desired surface structure, or may be formed simultaneously with molding by screen printing, extrusion molding or injection molding. Moreover, it is also possible to form a structural surface using heat or a photocurable resin. Moreover, the rough surface which consists of active energy precurable resin on the surface of transparent base materials, such as a transparent film or sheet which consists of polyester resin, acrylic resin, polycarbonate resin, vinyl chloride resin, polymethacrylimide resin, etc. A structure or a lens array arrangement may be formed, and such sheets may be bonded together on a separate transparent substrate by a method such as bonding or fusion. As active energy precurable resin, a polyfunctional (meth) acryl compound, a vinyl compound, (meth) acrylic acid ester, an aryl compound, the metal salt of (meth) acrylic acid, etc. can be used.

Light emission of the surface light source device including the primary light source 1, the light source reflector 2, the light guide 3, the light deflecting element 4, the light reflecting element 5, and the frame 7 as described above. By arranging the transmissive liquid crystal display element 8 on the surface (light exit surface 42 of the optical deflection element 5), the liquid crystal display device comprising the backlight of the surface light source device of the present invention It is composed. The liquid crystal display element 8 has the image forming part 81 in which an image is formed, and the frame part 82 attached to the outer periphery. In the XY plane, the inner circumferential edge of the frame portion 82 exists at a position equal to or inside the outer circumferential edge of the effective light emitting portion F of the surface light source device. Therefore, the display portion G of the liquid crystal display device is defined by the frame portion 82. That is, in the XY plane, the display portion G is located at the same or inside the effective light emitting portion F. As shown in FIG. The liquid crystal display device is observed by an observer from above in FIG. 4.

Next, the rough surface which comprises the light output mechanism of the light guide 3 is demonstrated. FIG. 5 is a schematic diagram showing the relationship between the primary light sources 1 and the light diffusing regions of the light guide surface 33. The rough surface formed on the light exit surface 33 is not formed as if having a uniform diffusivity as a whole, but as described below, the specific region is formed as having a high light diffusivity.

That is, most of the effective light emitting portion F is formed as a general light diffusing region A such that the above light output characteristics can be obtained. Since the rough surface of the general light diffusing region A is designed to achieve a uniformity of luminance in the light exit surface 33, an ultra-depth shape measuring microscope (for example, Japanese It is preferable that the characteristic which concerns on the inclination-angle measured using VK-8500 (brand name) manufactured by Giens Corporation is as follows. That is, the average value of the inclination angle measured using the super-depth shape measuring microscope is 0.5 degree or more and 5.0 degrees or less, More preferably, they are 1.0 degree or more and 3.5 degrees or less. Moreover, in the frequency distribution of the inclination angle measured with the super-depth shape measuring microscope, the component of the inclination angle 10 degree or more is 5.0% or less, More preferably, it is 2.0% or less. Moreover, Ra (center line average roughness) measured with the super-depth shape measuring microscope is 0.05 micrometer or more and 0.3 micrometer or less, More preferably, they are 0.08 micrometer or more and 0.2 micrometer or less. Moreover, Rz (ten point average roughness) measured with the super-depth shape measuring microscope is 0.5 micrometer or more and 1.8 micrometer or less, More preferably, they are 0.8 micrometer or more and 1.6 micrometer or less.

The characteristics related to these inclination angles can be specified based on the roughness of the surface of the light guide 3 measured using an ultra-depth shape measuring microscope. As measurement conditions, measurement mode: a color super depth, DISTANCE 5 micrometers, pitch 0.01 micrometer are mentioned. Ra and Rz in a measurement range (for example, 149 micrometers x 112 micrometers) are read. For this measurement range, the inclination angle average value can be obtained by extracting a cross-sectional curve, for example, under a weight average of ± 12, obtaining an absolute value of the inclination angle at each measurement point, and averaging them. The frequency distribution of the inclination angle can be obtained from the measured value of.

By the way, as shown in FIG.2 and FIG.5, the primary light source 1 is located opposite to the light guide light-incident end surface 31, and is attached to the light-emitting tube 1a which light actually emits, and at least one end thereof. And the socket 1b positioned to face the light guide light incidence end face 31. The socket 1b is located corresponding to the corner portion on the side of the light incident end face of the light guide 3. Therefore, assuming that the light output mechanism is uniformly formed on the light exit surface of the light guide, a region where the amount of emitted light is relatively small (that is, the brightness is relatively low) is formed corresponding to the socket 1b of the primary light source. A typical example of this low luminance region is the vicinity of a corner portion on the light incident end face side corresponding to the socket 1b, and a side cross section adjacent to this corner part and parallel to the light incident end face.

With reference to FIG. 6, the low luminance area | region of a light guide corner part is demonstrated. A light shielding plate 100 having a pinhole, for example, having a diameter of 1 mm, is disposed between the primary light source light tube 1a and the light incidence end face 31 of the light guide (the light emitting mechanism is assumed to be uniform across the entire surface). Then, a light deflecting element (not shown in FIG. 6) is disposed on the light guide light exit surface, and the primary light source 1 is turned on. When this is observed from the light exit surface side, the outgoing light distributed almost symmetrically with respect to the normal of the light incidence end face 31 is seen. The angle of the area of this distribution (angle with respect to the normal line of the light incident end surface 31) is called phi. On the other hand, the luminance distribution of the primary light source 1 can obtain the luminance value L equivalent to the center of the light emitting tube over the entire length of the light emitting tube 1a, as shown in FIG. The luminance value suddenly decreases in the vicinity of the junction with the socket 1b. In this specification, a region where the luminance value is L / 2 or more is defined as a light emitting portion, and a region other than that is defined as a non-light emitting portion. As shown in FIG. 6, a low luminance region D is formed corresponding to the non-light emitting portion by using a line drawn out at the inclination angle φ from the light guide cross-section position corresponding to the boundary between the light emitting portion and the non-light emitting portion. do.

Here, in the embodiment of the present invention, as shown in FIG. 5, at the position of the light guide light exit surface 33 corresponding to the non-light emitting portion of the primary light source 1, the light is lighter than the general light diffusing region A. FIG. A high light diffusing region B having high diffusivity is formed. The high light diffusing region B is disposed corresponding to the low luminance region D shown in FIG. 6, but may not be exactly the same region. Most of the high light diffusing region B is located in the region F 'of the width w other than the region corresponding to the effective light emitting portion F. As shown in FIG. Here, most are said to mean that the area occupies 80% or more. When the portion of the high light diffusing region B is located in the region corresponding to the effective light emitting portion F, it is preferable that the portion overlaps with the low luminance region D. FIG. Since the low luminance region D has a small amount of light reaching, even if the high light diffusing region B is provided, it is difficult to confirm. However, the high light diffusing region B is preferably located in a region F 'outside of the region corresponding to the effective light emitting portion F.

As for the rough surface of the high light-diffusion area | region B, the average value of the inclination-angle measured using the super-depth shape measuring microscope is 8 degree | times or more and 25 degrees or less, More preferably, it is 10 degree | times or more and 20 degrees or less. Moreover, in the frequency distribution of the inclination angle measured by the super-depth shape measuring microscope, the component of the inclination angle of 10 degrees or more is 30% or more, More preferably, it is 40% or more, The component of the inclination angle 20 degrees or more is 2% or more and 18% or less, Furthermore, Preferably they are 6% or more and 10% or less. Moreover, Ra measured by the super-depth shape measuring microscope is 0.35 micrometer or more and 0.6 micrometer or less, More preferably, they are 0.4 micrometer or more and 0.6 micrometer or less. Moreover, Rz measured with the super-depth shape measuring microscope is 3.5 micrometers or more and 12 micrometers or less, More preferably, they are 4.0 micrometers or more and 10 micrometers or less.

In the present embodiment, an intermediate light diffusive region C having a light diffusivity intermediate between the light diffusivity of the high light diffusing region B and the light diffusing characteristic of the general light diffusing region A is formed. have. The intermediate light diffusing region C is located between the high light diffusing region B and the general light diffusing region A in the vicinity of the side cross section parallel to the light incident end face 31 of the light guide.

As for the rough surface of the intermediate light-diffusion region C, the average value of the inclination-angle measured using the super-depth shape measuring microscope is 4 degrees or more and 12 degrees or less, More preferably, it is 5 degrees or more and 10 degrees or less. Moreover, in the frequency distribution of the inclination angle measured by the super-depth shape measuring microscope, the component of the inclination angle of 10 degrees or more is 5% or more and 40% or less, More preferably, it is 5% or more and 30% or less, and the component of the inclination angle 20 degrees or more is 2% 18% or more, More preferably, they are 2% or more and 15% or less. Moreover, Ra measured by the super-depth shape measuring microscope is 0.18 micrometers or more and 0.43 micrometers or less, More preferably, they are 0.2 micrometers or more and 0.4 micrometers or less. Moreover, Rz measured with the super-depth shape measuring microscope is 1.6 micrometers or more and 4 micrometers or less, More preferably, they are 2.0 micrometers or more and 3.8 micrometers or less.

Since the high light diffusing region B and the intermediate light diffusing region C as described above exist, the light diffusivity in these regions can be enhanced, and thus the effective light emitting portion F is located in or near these regions. It is possible to increase the amount of emitted light in the region of the light exit surface portion corresponding to. Since most of the high light diffusing region B is located outside the region corresponding to the effective light emitting portion F or in the region corresponding to the low luminance region D, the high light diffusive region B is from the inclination direction when used as a backlight of the display device. Even at the time of observation, the presence is hardly noticeable and there is no deterioration of the display image.

Although the intermediate light diffusing region C is not as large as the light diffusing region B, the light diffusing effect is not as noticeable as the high light diffusing region B. Even if it is located in the corresponding area, there is no problem. The intermediate light diffusing region C is located between the high light diffusing region B and the general light diffusing region A, and the effect of making the presence of the high light diffusing region B inconspicuous. Have

As a method of roughening at the time of formation of the above-mentioned light-diffusion area | regions A, B, and C, grinding | polishing by a grindstone, sandpaper, buff, etc., blast processing, electrical discharge machining, electrolytic polishing, chemical polishing, etc. are mentioned. . Especially blasting is preferable. Examples of the blast particles used in the blasting process include spherical ones such as glass beads and polygonal ones such as alumina beads. By using spherical ones, a general diffusion region (C) having a relatively low light diffusivity is formed. By using a polygonal thing, the intermediate light-diffusion region C and the high light-diffusion region B which are comparatively high light diffusivity can be formed. Although this roughening process may be performed directly on the surface of a light guide body, you may process the transfer surface of a metal mold | die, and may transfer this at the time of shaping | molding.

Next, the modification of the light guide in the said embodiment is demonstrated, referring drawings. In addition, in these drawings, the same code | symbol is attached | subjected to the part etc. which have the same function as the said FIG.

In the example of FIG. 7, as the high light diffusing region B, a region portion B1 located at the corner of the light guide and a region portion B2 near the region portion B1 and corresponding to the primary light source light emitting portion. Is installing. The high light diffusing region portion B2 is located entirely in the region F '. By the presence of the high light diffusing region portion B2, the light diffusing property in this region can be increased, and a part of the light diffused here is an area corresponding to the low luminance region D or near the effective light emitting portion. It proceeds to the area | region of the light emission surface part corresponding to (F), and can increase the output light quantity here. In this example, the intermediate light diffusing region C is located at the entire boundary between the high light diffusing region B, in particular, the region portion B2 and the general light diffusing region A. FIG. Thereby, especially, presence of the area | region part B2 of the high light-diffusion area | region B can be made inconspicuous.

In the example of FIG. 8, all the high light-diffusion areas B are located in area F '. The shape of the intermediate light diffusing region C is different from the example of FIG. 7, and the area in the region corresponding to the effective light emitting portion F of the intermediate light diffusing region C is reduced. In the case where all of the low luminance regions exist in the region F ', such a configuration can be preferably used.

In the example of FIG. 9, the high light diffusing region B extends along the side cross section extending from the light guide corner portion corresponding to the socket 1a of the primary light source 1 adjacent to the light incident end face. I install it. The intermediate light diffusing region C is located at the entire boundary between the high light diffusing region B and the general light diffusing region A. FIG. In this example, in particular, the light reaching the side cross section is diffused, and the light is emitted from the light emitting surface portion near the area corresponding to the effective light emitting portion F, thereby increasing the amount of emitted light.

In the example of FIG. 10, although the lengths of the high light diffusing region B and the intermediate light diffusing region C are different from those of FIG. 9, essentially the same effect as that of the example of FIG. 9 can be obtained.

In the example of FIG. 11, although the shape of the high light-diffusion region B and the intermediate light-diffusion region C is different from the example of FIG. 9, the effect similar to the example of FIG. 9 can be acquired essentially.

In the example of FIG. 12, the high light-diffusion region B and the intermediate light-diffusion region C use the same form as the combination of the example of FIG. 8 and the example of FIG. 10, and the same as those of these examples. The working effect can be obtained.

In the example of FIG. 13, the shapes of the high light diffusing region B and the intermediate light diffusing region C are polygonal, so that the high light diffusing region B is entirely located in the region F '. have. While maintaining the function of diffusing light, the high light diffusivity region B is difficult to be identified.

In the example of FIG. 14, as the high light diffusing region B and the intermediate light diffusing region C, one having the same form as the example of FIG. 5, the example of FIG. 9, and the example of FIG. 11 is used. The same effect as that of these examples can be obtained.

In the description of the above embodiments, the arrangement of the high light diffusing region B and the intermediate light diffusing region C has been defined in relation to the effective light emitting portion F of the surface light source device, but the display portion of the liquid crystal display device is similarly applied. It can also be prescribed in relation to (G). That is, when the surface light source device is used as the backlight of the display device, since it is actually the display portion G, the arrangement of the high light diffusion region B and the intermediate light diffusion region C is shown in the display portion G. It is reasonable to prescribe in relation to In the XY plane, however, the display portion G of the liquid crystal display device is not actually located outside the effective light emitting portion F of the surface light source device, and thus the high light diffusion region B and the intermediate light diffusion characteristics If the area C is set so as to fall within a predetermined range in relation to the effective light emitting portion F, the display image quality does not deteriorate even if the liquid crystal display device may have excessive quality.

Example

Hereinafter, the present invention will be described by way of examples. In the present Example, the light guide body, surface light source device which were demonstrated in embodiment of FIGS. 1-6, 14, and the liquid crystal display device using the same were produced.

The blasting process was performed using the glass beads about the whole surface of the stainless steel plate of the effective area 230 mm x 290 mm and thickness 3 mm which mirror-finished. Subsequently, an acrylic resin shielding plate is disposed 20 mm apart from the stainless steel plate so as to cover a portion other than the spherical region near the short side side end portion close to both ends of one long side side of the surface of the stainless plate, and alumina beads The first blasting process was performed. Moreover, the acrylic resin shielding plate is arrange | positioned 20 mm apart from a stainless steel plate so that the part of the surface of the said stainless steel plate may cover parts other than the triangular area vicinity of the both corner part of the said one long side side, and a 2nd blast process will be carried out by alumina beads. Was run. Thus, the general light diffusing region A as shown in FIG. 14, the high light diffusing region B1 (the maximum dimension in the X direction 5.0 mm, the maximum dimension in the Y direction 4.0 mm: these dimensions are the same as those of the light guide 3). This is the dimension of the area formed including the X-direction short side and the Y-direction long side [hereafter, the same]), B2 (maximum dimension in the X direction 11.0 mm, Y dimension in 0.5 mm) and the intermediate light diffusing region C1 (maximum in the X direction) A transfer surface for transferring the light guide light exit surface having dimensions 7.5 mm, dimensions Y 7.0, and C2 (maximum dimensions 14 mm X, dimensions 3.5 mm Y) was formed. In addition, a transfer surface region corresponding to the high light diffusing region B2 and the intermediate light diffusing region C2 is formed by the first blasting process, and the high light diffusing region B1 and the second blasting process. A transfer surface region corresponding to the intermediate light diffusion region C1 was formed. On the other hand, the transfer surface for transferring the light-guide body back surface which consists of a prism row formation surface as shown in FIG. 1 is cut-processed to the surface of the other stainless plate of 230 mm x 290 mm of effective area and 3 mm of thickness which mirror-finished. Formed by. Prism rows of the prism row forming surfaces were a vertex angle of 100 °, a top end radius of curvature of 15 µm, and an array pitch of 50 µm. The direction in which the prism rows extend was perpendicular to the long side of the stainless plate.

By injection molding, using a mold made of the two stainless steel plates, the thickness was continuously changed from 2.2 mm to 0.7 mm over one long side and the other long side in a rectangle of short side 230 mm and long side 290 mm. The wedge-shaped light guide 3 was manufactured. The surface shape was measured at several positions in the light guide. The method of taking the coordinates of the position where the measurement was performed is as shown in FIG. In addition, one intersection of the X direction short side and the Y direction long side of the light guide 3 was made into the coordinate origin. Table 1 shows the measurement results of the surface shape of the light guide.

Table 1

A cold cathode tube 1 having a length of 290 mm having a non-light emitting portion having a length of 4 mm at both ends thereof so as to face a side cross-section (side cross-section having a thickness of 2.2 mm) corresponding to one long side of the light guide 3. Was disposed by covering with a light source reflector (silver reflecting film manufactured by Japan's Leco Corporation) (2). Moreover, the light-diffusion reflective film (E60 Japan Toraya Co., Ltd.) was affixed on the other side end surface, and the reflecting sheet 5 was arrange | positioned so as to oppose the prism row formation surface (back surface) 34. In this configuration, an area of 4 mm in length at both ends of the light guide light incident end face 31 faces the non-light emitting portion of the cold cathode tube 1, and the light intensity distribution of the light emitted from the light guide light exit surface 33 ( The maximum peak of (in XZ plane) was 70 degrees with respect to the light exit surface normal direction, and the full width at half maximum was 22.5 degrees.

On the other hand, using an acrylic ultraviolet curable resin having a refractive index of 1.5064, a plurality of prism rows whose one prism face is convex curved shape having a curvature radius of 1000 μm and the other prism face is planar shape are addressed in parallel at a pitch of 50 μm. The prism sheet | seat 4 which formed the prism heat forming surface 41 comprised in one surface of the polyester film of thickness 125micrometer was produced. The prism sheet forming surface is directed toward the light exit surface (mat surface) 33 side of the light guide 3, and the ridge lines of the prism row are parallel to the light incident end surface 31 of the light guide. On the light incident end face 31 of the light guide, the flat prism face of each prism row was placed.

The above structure was assembled to the frame 7 to manufacture a surface light source device. The width w of the region F 'shown in FIG. 5 was 1.5 mm.

With respect to the surface light source device manufactured as described above, the primary light source 1 is turned on and the effective light emitting part F is observed from the front and inclined directions by the naked eye. The phenomenon seen by floating was not confirmed.

Moreover, the liquid crystal display element 8 was arrange | positioned on the prism sheet 4, and the liquid crystal display device was manufactured. The outer periphery of the display part G shown in FIG. 4 is located 0.5 mm inside from the outer periphery of the effective light emission part F of the surface light source device in the whole periphery.

With respect to the liquid crystal display device manufactured as described above, the surface light source device was turned on to drive the liquid crystal display element, and the display portion G was observed from the front and inclined directions by visual observation. No visible phenomenon or the like was observed, and good display image quality could be obtained.

Claims (17)

It has a primary light source, the light incident surface which guides the light which generate | occur | produces from the said primary light source, and also the light incident cross section into which the light emitted from the said primary light source enters, the light exit surface which the guided light exits, and the back surface opposite to the said light exit surface. In the surface light source device provided with a light guide, And a frame body covering the periphery of the light emitting surface of the light guide and defining an effective light emitting portion of the surface light source device, wherein at least one of the light emitting surface and the rear surface of the light guide has light diffusing property. At least one of the light emitting surface and the back surface having the light diffusing property is a region other than a region corresponding to the light emitting portion of the primary light source, and a region adjacent to the light incident cross section or a side cross section adjacent thereto. At least a portion of the light diffusing region having a high light diffusivity is formed in a general light diffusing region which occupies most of the region corresponding to the effective light emitting portion, and the high light diffusing region is mostly the effective light emitting portion. Outside the region corresponding to and / or within the low luminance region corresponding to the non-light emitting portion of the primary light source. Surface light source device. The method of claim 1, An intermediate light diffusing region having a light diffusivity in the middle of these regions is located between the high light diffusing region and the general light diffusing region. Surface light source device. The method of claim 1, At least a part of the high light diffusing region is located corresponding to at least one corner portion or the vicinity of the side of the light incident cross section of the light guide. Surface light source device. The method of claim 1, The light diffusivity is imparted by roughening at least one of the light exit surface and the back surface. Surface light source device. The method of claim 1, The surface light source device further comprises an optical deflecting element disposed on the light exit surface of the light guide and having a light incident surface on which the light exiting from the light exit surface is incident and a light exit surface on the opposite side thereof. doing Surface light source device. The method of claim 5, The optical deflecting element has a plurality of prism rows extending along the light incidence cross section of the light guide on the light incident surface and arranged in parallel with each other, wherein each of the prism rows is formed at the light exit surface of the light guide. Characterized in that it has a first prism face on which light is incident and a second prism face on which inner light is reflected Surface light source device. The method of claim 1, The primary light source has a linear shape, and has at least one end portion a non-light emitting portion located opposite to the light incident cross section of the light guide. Surface light source device. The method of claim 7, wherein At least a portion of the high light diffusing region is located corresponding to the non-light emitting portion of the primary light source. Surface light source device. The method of claim 1, The said high light-diffusion area | region is the average value of the inclination-angle measured with the super-depth shape measuring microscope being 8 degree | times or more and 25 degrees or less, It is characterized by the above-mentioned. Surface light source device. The method of claim 1, The said high light-diffusion area | region is 30% or more of components of the inclination-angle 10 degree or more in the frequency distribution of the inclination-angle measured by the super-depth shape measuring microscope, It is characterized by the above-mentioned. Surface light source device. The method of claim 1, The high light-diffusion region has a Ra of 0.35 µm or more and 0.6 µm or less as measured by an ultra-depth shape measuring microscope. Surface light source device. The method of claim 1, In the said high light-diffusion area | region, Rz measured with the super-depth shape measuring microscope is 3.5 micrometers-12 micrometers, It is characterized by the above-mentioned. Surface light source device. The method of claim 2, The said intermediate light-diffusion area | region is the average value of the inclination-angle measured with the super-depth shape measuring microscope being 4 degree | times or more and 12 degrees or less, It is characterized by the above-mentioned. Surface light source device. The method of claim 2, The said intermediate light-diffusion area | region is the component of the inclination-angle distribution measured with the super-depth shape measuring microscope, The component whose inclination angle is 10 degree or more is 5% or more and 40% or less, characterized by the above-mentioned. Surface light source device. The method of claim 2, The intermediate light diffusive region has a Ra of 0.18 µm or more and 0.43 µm or less as measured by an ultra-depth shape measuring microscope. Surface light source device. The method of claim 2, The intermediate light diffusion region has Rz of 1.6 µm or more and 4.0 µm or less as measured by an ultra-depth shape measuring microscope. Surface light source device. The surface light source device of any one of Claims 1-16 is comprised. Light guide.

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