JP2013077472A - Light guide body, lighting device equipped with the same, and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide body with improved concealment properties of its optical deflection elements and capable of alleviating luminance unevenness.SOLUTION: On a first main face of the light guide body, unit shapes of a plurality of optical deflection elements for deflecting light inside the light guide body toward a second main face are formed, and micro unevenness parts finer than a size of the unit shape of the optical deflection element are provided on the surface of each unit shape of the optical deflection element, whereby, concealment properties are improved to have the optical deflection elements hardly recognized, and that, scattering properties are improved to lessen deviation of luminance distribution derived from faint height errors of the unit shape and alleviate luminance unevenness.

Description

  The present invention relates to a light guide used mainly for illumination light path control, an illumination device, and a display device.

  In recent large-sized liquid crystal televisions, flat display panels and the like, a direct type illumination device and an edge light illumination device are mainly used. In the direct type illumination device, a plurality of cold cathode tubes and LEDs (Light Emitting Diodes) are regularly arranged as light sources on the back surface of the panel. A light diffusing plate is used between the image display element such as a liquid crystal panel and the light source so that a cold cathode tube or LED as a light source is not visually recognized.

  On the other hand, in an edge light type lighting device, a plurality of cold-cathode tubes and LEDs are arranged on an end face of a translucent plate called a light guide plate. In general, light that efficiently enters incident light that is incident from an end surface of the light guide plate onto a surface (light deflection surface) opposite to the light emission surface (surface that faces the image display element) of the light guide plate. A deflection element is formed. At present, the light deflection element formed on the light deflection surface is generally one in which white ink is printed in the form of dots (for example, Patent Document 1). However, since the light incident on the white dots is diffusely reflected almost omnidirectionally, the light extraction efficiency to the exit surface side of the light guide plate is low. Light absorption by white ink cannot be ignored.

  Therefore, recently, a method of forming the unit shape 32 of the light deflection element by the microlens on the light deflection surface of the light guide plate by the ink jet method, a method of forming the unit shape 32 of the light deflection element by the laser ablation method, A method of forming a unit shape 32 of a light deflection element composed of a V-shaped or U-shaped groove on the surface of the light and various other shapes and forming it on the light deflection surface of the light guide plate (Patent Document 2), etc. Proposed. These methods use reflection, refraction, and transmission due to the difference in refractive index between the resin of the light guide plate and air at the portion of the light deflection element unit shape 32 on the light deflection surface of the light guide plate, unlike printing with white ink. Therefore, light absorption hardly occurs. Therefore, a light guide plate having a higher light extraction efficiency than that of white ink can be obtained.

JP-A-1-241590 JP 2000-89033 A

  However, in the method of forming the unit shape 32 of the light deflection element on the light deflection surface of the light guide plate, such as a microlens, a V-shape or a U-shape, the incident light is reflected directionally unlike white ink. Therefore, a local light / dark difference occurs. That is, the concealability is deteriorated and the light deflection element is easily visually recognized. This is because, in the unit shape 32 of the light deflection element, as shown in FIG. 7, the incident light is reflected in a directional direction, so that the condensing part, that is, the bright part and the dark part are emphasized. Therefore, in order to improve the concealment property, as shown in FIG. 8, the unit shape 32 of the light deflection element is made small (fine) to make the unit that causes local contrast difference small, so that the light deflection element is visually recognized. Possible ways to make it difficult.

However, in order to realize the above-described method, it is necessary to reduce the formation deviation of the unit shape 32 of the light deflection element in the step of forming the light deflection element. For example, height 50μm
It is assumed that there is a design error (target value) in the unit shape 32 of the light deflection elements of 5 μm and 5 μm and an actually measured height error of 1 μm. There is a problem that the unit shape 32 of the optical deflection element having a height of 50 μm, which is the former, has a deviation of 2%, while the unit shape 32 of the optical deflection element having the height of 5 μm, is displaced by 20%. That is, when the unit shape 32 of the light deflection element is made small (fine), the influence of macroscopic fine deviation increases and luminance unevenness becomes large, so that there is a problem that desired optical characteristics cannot be obtained.

  The present invention has been made in order to solve the above-described conventional problems, and improves the concealment of the light deflection element, and eliminates the luminance unevenness caused by the minute height error of the unit shape 32 of the light deflection element. The purpose is to reduce.

  As means for solving the above-mentioned problems, the present invention is a light-transmitting light guide, and the light guide has a first main surface and a second main surface facing the first main surface. And a plurality of light sources facing at least one side end surface of the four side end surfaces are connected in the extending direction of the side end surface. The unit shape of a plurality of light deflection elements for deflecting light in the light guide toward the second main surface side is formed on the first main surface, and the unit shape of the light deflection element is A light guide having a fine uneven portion finer than a unit shape of the light deflection element on a surface.

  Moreover, this invention is said light guide, Comprising: The unit shape of the said optical deflection | deviation element of a said 1st main surface is a convex circular structure, It is a light guide characterized by the above-mentioned.

  Moreover, this invention is said light guide, Comprising: The unit shape of the said optical deflection | deviation element of a said 1st main surface is a concave circular structure, It is a light guide characterized by the above-mentioned.

  Moreover, this invention is said light guide, Comprising: The fine uneven | corrugated width | variety of the said fine uneven | corrugated | grooved part is 0.2 micrometer or more and 5 micrometers or less, It is a light guide characterized by the above-mentioned.

  Moreover, this invention is said light guide, Comprising: The depth of the said fine uneven | corrugated | grooved part is 2 micrometers or less, It is a light guide characterized by the above-mentioned.

  Moreover, this invention is said light guide, Comprising: It is a light guide which arrange | positioned the cylindrical-shaped structure continuously in the one-dimensional direction in the optical element of the 2nd main surface of the said light guide.

  Moreover, this invention is an illuminating device carrying said light guide.

  Moreover, this invention is a display apparatus provided with said illuminating device.

  According to the invention described in the present invention, by providing fine uneven portions on the surface of the unit shape of the light deflection element, the concealability can be improved, the light deflection element becomes difficult to be visually recognized, and the scattering property is increased. Has the effect of improving. Therefore, there is no need to reduce the unit shape of the light deflection element, and there is an effect that it is possible to prevent an increase in luminance unevenness due to a minute height error that occurs when the unit shape of the light deflection element is reduced.

It is explanatory drawing of the illuminating device of the edge light system of this invention. It is explanatory drawing which shows a part of light guide 7 of this invention. It is sectional drawing of the unit shape 32 of the optical deflection | deviation element which shows a convex-shaped circular structure. It is sectional drawing of the unit shape 32 of the optical deflection | deviation element which shows a concave circular structure. It is a front view of the 1st main surface 7a of the light guide 7 of this invention. It is sectional drawing of the unit shape 33 of the optical deflection | deviation element which has a fine uneven | corrugated | grooved part. It is explanatory drawing which showed simply the incident optical path from the light source 6, and an emitted optical path. It is explanatory drawing which showed simply the incident optical path from the light source 6, and an emitted optical path. 2 is a perspective view of a mold 30. FIG. It is sectional drawing of the unit shape 33 of the optical deflection | deviation element which has a fine uneven | corrugated | grooved part. It is sectional drawing which linearized the shape tangent of the unit shape 33 of the light deflection | deviation element which has a fine uneven | corrugated | grooved part. It is explanatory drawing of the method of transcribe | transferring and forming the metal mold | die 30 to the sheet | seat of the light guide 7. FIG. It is the description which showed the formation method of the optical deflection | deviation element 18 to the circumferential direction. It is the description which showed the formation method of the optical deflection | deviation element 18 to an axial direction.

Hereinafter, the light guide and the light guide plate refer to the same thing.
The light guide of the present invention will be described with reference to FIG. The display device 1 of the present invention includes a lighting device 3 and a liquid crystal panel 2. In FIG. 1, the display device 1 displays an image toward an observer who is in the direction F, and causes the observer to observe.

  The illuminating device 3 plays a role of entering the light emitted from the light source 6 and deflecting it to the emitted light K toward the liquid crystal panel 2. The light guide 7 is housed in the housing 5 of the lighting device 3. A reflective sheet is provided between the light guide 7 and the housing 5. The light from the light source is incident on the side end face 7L of the light guide. The light is deflected by the light deflection element 18 on the first main surface 7a and is emitted from the second main surface 7b. When the second main surface 7 b has the optical element 19, the light is emitted from the optical element 19. The light then passes through the diffusion sheet 8, the prism sheet 20, and the polarization separation sheet 28, and is emitted toward the observer in the direction F as emission light K from the illumination device.

  FIG. 2 is an explanatory view showing a part of the light guide 7 of the present invention. It has a side end surface 7L on which light is incident, a first main surface 7a, and a second main surface 7b. The first main surface 7a is formed with a light deflection element 18 composed of a plurality of dot-shaped light deflection element unit shapes 32, and the second main surface 7b has an optical element 19. The side end surface where no light is incident is 7S. The light deflection elements 18 are dots arranged on the mirror surface of the first main surface a. The optical element 19 is a lens arranged without gaps.

  The light guide 7 is made of a transparent resin such as acrylic, polycarbonate, polystyrene, AS resin, or MS resin. The light guide 7 is formed into a square resin plate by injection molding, extrusion molding, or casting.

(Light deflection element 18)
The light deflection element 18 is formed by a unit shape 32 of a plurality of three-dimensional dot-shaped light deflection elements formed on the surface of the first main surface 7a, and is formed in various dot shapes such as a convex shape and a concave shape. be able to. In other words, the dot shape of the unit shape 32 of the light deflection element can be formed in the shape of a hemispherical dot, a pyramidal dot, a cube, or the like. From the viewpoint of being hard to be damaged, a concave shape is preferable, and it is more preferable that the dot is a concave dot having a height difference from the first main surface 7a of 5 μm or more and 70 μm or less. If it is less than 5 μm, it is too shallow to prevent scratches, and if it is deeper than 70 μm, it is very difficult to remove if foreign matter has entered. The light deflection element 18 differs in the size, shape, and arrangement interval of the dots of the unit shape 32 of the light deflection element depending on the distance from the light source.

(Optical element 19)
The optical element 19 formed on the second main surface 7b has various materials and shapes. For example, the optical element 19 can be formed of a lens formed of a UV curable resin on the second main surface 7b.

  The optical element 19 can also be formed by a concave lens having a second main surface 7b formed by machining.

  The optical element 19 can be formed of a concave or convex lens created on the second main surface 7b by a mold. The lens may be formed in a mold when the light guide 7 is formed, or may be formed in a heated mold after formation. The lens can be formed into a prism lens, a lenticular lens, a trapezoid lens, or the like well known in the art. In the case of forming a lenticular lens, as shown in FIG. 2, an optical element 19 in which cylindrical structures are continuously arranged in a one-dimensional direction is formed.

  Alternatively, the optical element 19 is not essential when considering the function of the light guide 7. In that case, the second main surface 7b is merely a flat surface, and the optical element 19 can be omitted.

  Unlike the unit shape 32 of the light deflection element, the optical element 19 is formed without gaps. Therefore, if the optical element 19 is present, no problem occurs when the protective film is peeled off from the second main surface 7b. That is, from the viewpoint of easy removal of the protective film, it is more preferable to have the optical element 19.

(Fine irregularities in the unit shape of the light deflection element 18)
Next, the unit shape 32 of the light deflection element 18 of the light guide 7 according to the present invention will be described. The unit shape 32 of the light deflection element 18 is formed on the first main surface 7a of the light guide 7 on the desired convex circular dot-shaped structure as shown in FIG. 3 or the desired shape as shown in FIG. A concave circular dot-shaped structure is formed. By arranging the unit shapes 32 of the light deflecting elements continuously in a two-dimensional direction, the light deflecting elements 18 that efficiently guide incident light incident from the end face to the exit surface are formed.

  The unit shape 32 of the light deflection element is a dot-like structure such as a desired circular structure, but the surface thereof is finer than the size of the unit shape 32 of the light deflection element as shown in FIG. By providing the fine uneven portion, the unit shape 33 of the light deflection element having the fine uneven portion is formed. By doing so, there is an effect that the concealability of the light deflection element 18 is improved and luminance unevenness can be reduced. In the conventional unit shape 32 of the light deflection element, as shown in FIG. 7, incident light is reflected in a directional direction, so that there is a problem that a condensing part, that is, a bright part and a dark part are emphasized. On the other hand, in the unit shape 33 of the light deflection element having the fine uneven portion of the present embodiment, the fine uneven portion finer than the unit shape size of the light deflection element is provided on the surface of the unit shape of the light deflection element. Thus, there is an effect that luminance unevenness can be reduced.

(Fine unevenness width 32)
It is desirable that the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness be 0.2 μm or more and 5 μm or less. The reason is that formation is difficult when the fine unevenness width 34 is 0.2 μm or less, and measurement is difficult. Further, if the fine unevenness width 34 is 5 μm or more, there arises a problem that the desired optical characteristics designed cannot be obtained, and also the luminance is lowered, and further, the concealing property, which is a problem, is lowered, and the light deflection is reduced. This is because the problem that the element 18 can be visually recognized occurs.

(Fine unevenness depth 35)
The depth 35 of the fine uneven portion of the unit shape 33 of the light deflection element having the fine uneven portion is defined by the difference between the height of the highest convex portion and the height of the lowest convex portion of the fine uneven portion as shown in FIG. To do. The depth 35 of the fine irregularities is desirably 2 μm or less. The reason is that if the depth 35 of the fine uneven portion of the unit shape 33 of the light deflection element having the fine uneven portion is 2 μm or more, the designed desired optical characteristics cannot be obtained, and the brightness is lowered. This is because there arises a problem that it can be visually recognized as a luminance unevenness which is a problem.

(Manufacturing method of the light guide 7)
Below, the manufacturing method which manufactures the light guide 7 using the metal mold | die 30 is demonstrated.
(Mold 30)
First, the manufacturing method of the metal mold | die 30 used as the base material of the light guide 7 is demonstrated. As shown in FIG. 9, a substantially cylindrical mold 30 is used as the mold 30. On the surface of the mold 30, an optical structure forming part 31 for forming a base for forming the mold of the light deflection element 18 is formed as follows.

Next, a method for processing a mold for the light deflection element 18 on the surface of the mold 30 will be described.
(Processing of the mold in the circumferential direction)
First, a die is processed in the circumferential direction on the surface of the die 30 as follows. In this case, as shown in FIG. 13, a cutting tool 40 having a desired shape is pressed against a mold processing machine (lens shape forming machine), and the mold 30 is rotated while the cutting tool 40 is oscillated in the front-rear direction. The mold for the unit shape 32 of the light deflection element is processed on the surface of the mold 30 while moving in the axial direction. In this processing, the surface of the mold 30 is processed while the cutting tool 40 is oscillated in the front-rear direction, whereby the mold for the unit shape 32 of the light deflection element formed on the mold 30 is shown in FIG. Thus, fine irregularities finer than the width of the unit shape 32 of the light deflection element are formed, and finally, a mold for the unit shape 33 of the light deflection element having the fine irregularities is formed.

(Processing in the axial direction of the mold)
Next, the mold is processed in the axial direction on the surface of the mold 30. In this case, as shown in FIG. 14, a cutting tool 40 having a desired shape is attached to a mold processing machine (lens shape forming machine), and the mold 30 is not rotated while the cutting tool 40 is oscillated in the front-rear direction. The mold for the unit shape 33 of the light deflection element having the fine irregularities on the surface of the mold 30 is processed while moving in the axial direction.

  The surface shape of the mold 30 is transferred to the sheet of the light guide 7 as shown in FIG. 12, so that the light deflection element having the fine irregularities as shown in FIG. A unit shape 33 can be formed.

  Next, with reference to FIG. 11, the unit shape 33 of the light deflection element having the fine irregularities thus manufactured will be described. FIG. 11 is a diagram in which the shape tangent line 36 of the unit shape 32 of the curved light deflection element as shown in FIG. 10 is linearized. The shape tangent line 36 represents a line having an average height (depth) obtained by averaging the heights of the fine convex portions and the concave portions. The concavo-convex line shown in FIG. 11 represents the fine concavo-convex provided on the initial shape tangent 36 of the unit shape 32 of the light deflection element, that is, the shape tangent of the unit shape 33 of the light deflection element.

(Fine uneven width 34 of the unit shape 33 of the light deflection element having fine uneven portions)
The fine uneven width 34 of the unit shape 33 of the light deflection element having the fine uneven portions indicates a portion generally called a pitch, and is shown in FIG.
(Depth 35 of the fine uneven part of the unit shape 33 of the light deflection element having the fine uneven part)
The depth 35 of the fine uneven portion of the unit shape 33 of the light deflection element having the fine uneven portion is defined by the difference between the height of the highest convex portion and the height of the lowest convex portion of the fine uneven portion as shown in FIG. To do.

(Molding material for light guide)
Next, the molding material of the light guide 7 will be described. As the molding material of the light guide 7 when the light guide 7 is formed by molding with the mold 30, a material having light transmittance with respect to the wavelength of light emitted from the light source unit is used. For example, a plastic material that can be used for the optical member can be used. Examples of this material include polyester resins, acrylic resins, polycarbonate resins, polystyrene resins, MS (acrylic and styrene copolymer) resins, polymethylpentene resins, thermoplastic resins such as cycloolefin polymers, or polyester acrylates and urethanes. Examples thereof include transparent resins such as radiation curable resins made of oligomers such as acrylates and epoxy acrylates, or acrylates.

  The light guide 7 may have a single-layer structure or a multi-layer structure, and may include a transparent layer. And the light guide 7 is shape | molded and manufactured by pouring the above materials into a metal mold | die and solidifying it.

(Material to be molded by UV curing the light guide)
Further, the light guide 7 may be manufactured by being molded by a UV curing method. When the light guide 7 is molded by the UV curing method, a UV curable resin is applied onto the base portion which is a sheet-like base material, a mold 30 having a desired shape is pressed, and then UV irradiation is performed to form the base portion. And a light guide 7 composed of optical protrusions and optical elements. As the sheet-like substrate, PET (polyethylene terephthalate), polycarbonate, acrylic, polypropylene films and the like well known in the art can be used.

  In addition, although the typical preparation example about the light guide 7 was demonstrated, if the optical characteristic of this embodiment can be achieved, it can also be produced using materials, structures, processes other than the above. is there.

  In the manufacturing method of the mold 30 which is a base for producing the light guide 7, a manufacturing method of the mold 30 in which the mold for the light deflection element 18 to the mold 30 is formed by a cutting method will be described.

(Processing the mold for the optical deflection element 18 in the circumferential direction of the mold 30)
First, as shown in FIG. 13, a mold for the light deflection element 18 in the circumferential direction of the mold 30 was formed. For this purpose, as shown in FIG. 13, a cutting tool 40 having a desired shape is attached to a mold processing machine (lens shape forming machine), and the shaft 30 is rotated while the mold 30 is rotated while the cutting tool 40 is oscillated in the front-rear direction. A mold for the light deflection element 18 was processed on the surface of the mold 30 while moving in the direction.

(Processing of the mold for the light deflection element 18 in the axial direction of the mold 30)
Next, as shown in FIG. 14, a mold for the optical deflection element 18 in the axial direction of the mold 30 was formed. For this purpose, as shown in FIG. 14, a cutting tool 40 having a desired shape is attached to a mold processing machine (lens shape forming machine), and the mold 30 is not rotated while the cutting tool 40 is oscillated in the front-rear direction. A mold for the light deflection element 18 was processed on the surface of the mold 30 while moving in the axial direction.

  In this way, the mold for the light deflection element 18 is formed on the surface of the mold 30 by processing in the circumferential direction and the axial direction of the mold 30. The surface shape of the mold 30 is transferred to the sheet of the light guide 7 as shown in FIG. 12, so that the light deflection element having the fine irregularities as shown in FIG. A unit shape 33 can be formed.

Example 1
As setting values, the width of the unit shape 32 of the light deflection element is 50 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness is 0.2 μm, and the depth 35 of the fine unevenness is 0.5 μm or less. A mold 30 was prepared.

(Example 2)
Next, the width of the unit shape 32 of the light deflection element is 50 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness is 2.5 μm, and the depth 35 of the fine unevenness is 0.5 μm or less. A mold 30 was produced.

(Example 3)
Next, the width of the unit shape 32 of the light deflection element is 50 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness is 2.5 μm, and the depth 35 of the fine unevenness is 1.0 μm or less. A mold 30 was produced.

Example 4
Next, the width of the unit shape 32 of the light deflection element is 50 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness is 3.0 μm, and the depth 35 of the fine unevenness is 1.5 μm or less. A mold 30 was produced.

(Example 5)
Next, the width of the unit shape 32 of the light deflection element is 50 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness portion is 3.0 μm, and the depth 35 of the fine unevenness portion is 2.0 μm or less. A mold 30 was produced.

(Example 6)
Next, the width of the unit shape 32 of the light deflection element is 100 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness is 3.0 μm, and the depth 35 of the fine unevenness is 1.5 μm or less. A mold 30 was produced.

(Example 7)
Next, the width of the unit shape 32 of the light deflection element is set to 100 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness portion is set to 5.0 μm, and the depth 35 of the fine unevenness portion is set to 2.0 μm or less. A mold 30 was produced.

(Example 8)
Next, the width of the unit shape 32 of the light deflection element is 200 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness portion is 5.0 μm, and the depth 35 of the fine unevenness portion is 2.0 μm or less. A mold 30 was produced.

Example 9
Next, the width of the unit shape 32 of the light deflection element is 200 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness portion is 0.2 μm, and the depth 35 of the fine unevenness portion is 0.5 μm or less. A mold 30 was produced.

(Comparative Example 1)
Next, as a comparative example, the width of the unit shape 32 of the light deflection element is 50 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness is 6.0 μm, and the depth 35 of the fine unevenness is 2.0 μm. The following mold 30 was produced.

(Comparative Example 2)
Next, as a comparative example, the width of the unit shape 32 of the light deflection element is 50 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness is 2.5 μm, and the depth 35 of the fine unevenness is 3.0 μm. The following mold 30 was produced.

(Comparative Example 3)
Next, as a comparative example, the width of the unit shape 32 of the light deflection element is 50 μm, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness is 6.0 μm, and the depth 35 of the fine unevenness is 5.0 μm.
A mold 30 having a size of m or less was produced.

Next, a method for producing the light guide 7 will be described.
In this experiment, a sheet of the light guide 7 was produced by an extrusion method. FIG. 12 shows a schematic view of the extruder 37. The produced mold 30 was installed in an extruder 37, and the mold 30 was installed on one of the forming rolls 38 for extruding the light guide sheet from a gap close to the pair of forming rolls 38. A thermoplastic polycarbonate resin was melted and extruded by an extruder 37. The extruded thermoplastic polycarbonate light guide 7 sheet was molded by the forming roll 39 before being cooled and cured. Thereby, the light guide 7 having a desired shape was obtained. The thickness of the light guide 7 was all 320 μm.

  All the light guides 7 are produced by an extrusion method using a thermoplastic polycarbonate resin. The thermoplastic polycarbonate resin used in the present invention has an elastic modulus E of 2400 MPa and a specific gravity of 1.2 g / cm 3. This light guide 7 has a very good transfer rate from the mold 30 and a shaping rate of 99% or more.

Then, each evaluation method of the obtained light guide 7 is demonstrated.
(Concealment evaluation)
The obtained light guide body 7 composed of the unit shape 33 of the light deflection element having fine uneven portions was mounted on an LED edge light type liquid crystal television and evaluated for concealment. The method for evaluating the concealment was set to (◯) when the light deflection element 18 was not visually recognized by visual inspection, and (X) when it was visually recognized. The evaluation results are shown in Table 1. In addition, since visual difference produced an individual difference, it was implemented by three experts, and even if one person had (x) evaluation, it evaluated as (x). That is, (◯) evaluation is completely coincident.

(Luminance unevenness evaluation)
The obtained light guide body 7 composed of the unit shape 33 of the light deflection element having fine uneven portions was mounted on an LED edge light type Sony 40-inch liquid crystal television and evaluated by a luminance measuring machine. The luminance measurement points are 9 points that are intersections of 3 vertical rows and 3 horizontal columns. If the variation is less than the conventional light guide (○), if the variation is higher or the same value (×). .

Table 1 is a concealment evaluation, luminance unevenness evaluation, and result list.

  Therefore, since the condition (◯), which is the evaluation result shown in Table 1, is the effective value of the present invention, the fine unevenness width 34 of the unit shape 33 of the light deflection element having the fine unevenness is 0.2 μm or more and 5 μm or less. It is desirable to make it. The depth 35 of the fine uneven portion of the unit shape 33 of the light deflection element having the fine uneven portion is desirably 2 μm or less.

  In the embodiment, the fine unevenness width 34 or the fine unevenness depth 35 of the unit shape 33 of the light deflection element having the fine uneven portions is formed at regular intervals, but the present invention needs to be arranged at regular intervals. There is no. Specific examples include unequal arrangement and randomness.

DESCRIPTION OF SYMBOLS 1 ... Display apparatus 2 ... Liquid crystal panel 3 ... Illumination device 5 ... Case (reflective sheet)
6 ... light source 7 ... light guide 7a ... first main surface 7b ... second main surface 7L ... side end surface (light incident surface)
7S ... side end face 8 ... diffusion sheet 9, 10 ... polarizing plate 11 ... liquid crystal panel 18 ... light deflection element 19 ... optical element 20 ... prism sheet 23 ... base Material 23a ... Light exit surface 23b ... Light incident surface 24 ... Prism lens 28 ... Polarization separation sheet 30 ... Mold 31 ... Optical structure forming part 32 ... Light deflection Element unit shape 33 ... Unit unit shape 34 of light deflection element having fine irregularities ... Fine irregularity width 35 ... Depth of minute irregularities 36 ... Shape tangent 37 ... Extruder 38 ..Forming roll A
39 ... Forming roll B
40: Cutting tool K: Light emitted from the illumination device F: Direction of the observer

Claims (8)

A translucent light guide,
The light guide has a first main surface, a second main surface facing the first main surface,
Having four side end surfaces connecting the first main surface and the second main surface;
A plurality of light sources facing at least one side end surface of the four side end surfaces,
Arranged side by side in the extending direction of the side end face,
The first main surface is formed with a unit shape of a plurality of light deflecting elements for deflecting light in the light guide body toward the second main surface side,
A light guide having a fine concavo-convex portion finer than a unit shape dimension of the light deflection element on a surface of the unit shape of the light deflection element. The light guide according to claim 1,
The light guide body, wherein the unit shape of the light deflection element on the first main surface is a convex circular structure. The light guide according to claim 1,
A light guide body, wherein a unit shape of the light deflection element on the first main surface is a concave circular structure. The light guide according to any one of claims 1 to 3,
The light guide, wherein the fine unevenness width of the fine unevenness part is 0.2 μm or more and 5 μm or less. The light guide according to any one of claims 1 to 3,
A light guide having a depth of the fine unevenness of 2 μm or less. The light guide according to any one of claims 1 to 5,
A light guide in which a cylindrical structure is continuously arranged in a one-dimensional direction on the optical element of the second main surface of the light guide.   The illuminating device which mounts the light guide as described in any one of Claims 1 thru | or 6. A display device comprising the illumination device according to claim 7.