JP2008027757A - Optical plate body and light guide plate and reflecting plate using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical plate body having a new light diffusion pattern superior in diffusion efficiency, and a light guide plate and a reflecting plate using the same. <P>SOLUTION: The optical plate body 100 diffuses irradiation light 201 from side direction to a pattern face 110 in normal line direction. The light diffusion pattern 111 is made of an assembly of light diffusion patterns of at least one of a convex pattern and a concave pattern, and at least a part of the light diffusion pattern 113 out of the light diffusion patterns has a straight line shape portion in which a part of the outer periphery shape in plan view is formed in a straight line (chord to the following arc) and a circular arc shape portion in which the other part of the outer periphery shape in plan view is formed in a circular arc shape ( major arc with the central angle becoming 203-240°), and the straight line shape portion is arranged on the side nearer to the light source of the irradiation light 201 against the circular arc shape portion. The light guide plate and the reflecting plate are made of this optical plate body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical plate, and a light guide plate and a reflection plate using the same. More specifically, an optical plate having a novel light diffusion pattern excellent in diffusion efficiency, and a light guide plate and a reflection plate using the same.

  As a light guide plate, one having a light diffusion pattern on one surface of a plate is known. The light guide plate having the light diffusion pattern can emit light incident from the side surface in a normal direction with respect to the incident direction. By providing the light diffusion pattern, it is possible to prevent light from being simply transmitted from the incident side surface to the opposite surface, and to emit light in the normal direction. Furthermore, by making this light diffusion pattern a predetermined pattern shape, the luminance on the exit surface can be made more uniform over the entire surface. This is known, for example, in Patent Document 1 and Patent Document 2 below. However, conventionally, a perfect circular pattern is used as this light diffusion pattern (see FIG. 23).

JP 2005-1117023 A JP 08-328004 A

Patent Document 1 discloses a diffuser plate in which a dimming dot pattern is formed in a backlight device used for a liquid crystal screen or the like. This is excellent in that the light from the light source is uniformly transmitted over the entire surface of the backlight device, but it is not a configuration for diffusing the irradiation light from the side in the normal direction. On the other hand, Patent Document 2 is a backlight structure of a liquid crystal display device, which is a structure for emitting light from the side in a normal direction, and has a predetermined reflection pattern. Although it is excellent in terms of emitting light from the side more uniformly, it has not been studied to improve the emission efficiency in the normal direction (light diffusion efficiency).
The present invention has been made in view of the above-described conventional technology, and an object thereof is to provide an optical plate having a novel light diffusion pattern excellent in diffusion efficiency, and a light guide plate and a reflection plate using the same. To do.

The present invention is as follows.
(1) An optical plate that includes a pattern surface on which a light diffusion pattern is formed, and diffuses irradiation light from the side of the pattern surface in a normal direction with respect to the pattern surface,
The light diffusion pattern is composed of an aggregate of at least one light diffusion pattern of a convex pattern and a concave pattern provided on the pattern surface,
At least a part of the light diffusion pattern of the light diffusion pattern includes a linear shape part in which a part of the outer peripheral shape in plan view is formed in a straight line, and a circular part in the other part of the outer peripheral shape in plan view. An arcuate shape portion, and
The optical plate body, wherein the linear shape portion is disposed on a side closer to the light source of the irradiation light with respect to the arc shape portion.
(2) The arc-shaped portion is an arc having a central angle of 203 to 240 degrees,
The optical plate according to the above (1), wherein the linear shape portion is a string with respect to the arc.
(3) The convex pattern has a concave portion at the center,
The optical plate according to (1) or (2), wherein an inner peripheral shape of the convex pattern in plan view is circular or similar to the outer peripheral shape of the convex pattern.
(4) The concave pattern has a convex portion at the center,
The optical plate according to (1) or (2), wherein an inner peripheral shape of the concave pattern in plan view is circular or similar to the outer peripheral shape of the concave pattern.
(5) The optical plate according to any one of (1) to (4), wherein the light diffusion pattern is radially arranged with respect to the light source of the irradiation light.
(6) The optical plate according to any one of (1) to (5), wherein the light diffusion pattern has a staggered arrangement.
(7) Of the two light diffusion patterns that share the light source closest to the light source of the irradiation light, one light diffusion pattern disposed at a position closer to the light source and the one light When the other light diffusion pattern arranged farther from the light source than the diffusion pattern is viewed in plan, the size of each outer periphery is such that the one light diffusion pattern is larger than the other light diffusion pattern. The optical plate according to any one of (1) to (6), which is small.
(8) The optical plate according to any one of (1) to (7), wherein the optical plate has translucency, and the irradiation light is used for the optical from the side. A light guide plate, wherein the light guide plate is incident on the plate body, and the irradiated light is diffused and emitted in a normal direction with respect to the pattern surface.
(9) The light guide plate according to (8), comprising the convex pattern, wherein the convex pattern is made of a composite material having a translucent resin as a parent phase and quartz glass particles as a dispersed phase.
(10) The optical plate according to any one of (1) to (7), wherein the light diffusion pattern is formed of a light reflective metal film, and the irradiation light is in a normal direction with respect to the pattern surface. A reflector that is diffused and reflected.

According to the optical plate of the present invention, it is possible to provide a plate used for optical applications having excellent light diffusion efficiency. Particularly, the irradiation light irradiated from the side of the pattern surface on which the light diffusion pattern is formed can be diffused with high efficiency in the normal direction with respect to the pattern surface.
When the arc-shaped portion is formed of an arc having a central angle of 203 to 240 degrees, and the linear-shaped portion is formed of a chord with respect to the arc, higher light diffusion efficiency can be obtained.
When the convex pattern has a concave portion at the center and the inner peripheral shape is similar to the circular shape or the outer peripheral shape, and the concave pattern has a convex portion at the central portion, and the inner peripheral shape is circular or the outer peripheral shape. If they are similar, a higher diffusion efficiency can be obtained.
When the light diffusion pattern is arranged radially with respect to the light source of the irradiation light, the effect is more easily exhibited by having the linear shape portion, and higher light diffusion efficiency can be obtained.
When the light diffusion pattern has a staggered arrangement, light can be diffused without loss, and higher light diffusion efficiency can be obtained.
If the light diffusion pattern placed closer to the light source is smaller than the light diffusion pattern placed far from the light source, the light diffusion on the surface of the optical plate is made more uniform regardless of the distance from the light source. can do.
According to the light guide plate of the present invention, light incident from the side can be diffused with high efficiency in the direction normal to the pattern surface, and a light guide plate with high luminance can be obtained.
When a convex pattern is provided, and the convex pattern is made of a composite material containing a translucent resin as a parent phase and containing quartz glass particles as a dispersed phase, higher diffusion efficiency can be obtained.
According to the reflecting plate of the present invention, it is possible to obtain a reflecting plate that can reflect light irradiated from the side with high efficiency in the direction normal to the pattern surface.

[1] Optical plate body Hereinafter, the present invention will be described in detail with reference to FIGS.
The optical plate 100 of the present invention (see FIG. 1) includes a pattern surface 110 (back surface in FIG. 1) on which a light diffusion pattern 111 is formed, and emits irradiation light 201 from the side with respect to the pattern surface 110. An optical plate for diffusing in a normal direction with respect to the pattern surface 110, wherein the light diffusion pattern 111 is at least one of a convex pattern and a concave pattern provided on the pattern surface. The light diffusing pattern is an aggregate of light diffusing patterns, and at least a part of the light diffusing patterns 113 includes a linear shape part in which a part of the outer peripheral shape in a plan view is linearly formed, and the plan view An arc-shaped portion formed in a circular arc shape at the other part of the outer peripheral shape, and the linear shape portion is disposed on a side closer to the light source of the irradiation light with respect to the arc-shaped portion. And

That is, the optical plate of the present invention includes the pattern surface 110 on which the light diffusion pattern 111 is formed. In order to have this light diffusion pattern, the irradiation light 201 from the side with respect to the pattern surface 110 can be diffused in the normal direction with respect to the pattern surface 110.
(1) As schematically shown in FIG. 2, the irradiation light 201 from the side is incident on the optical plate 100a and then into the normal direction from the optical plate 100a. (2) diffusing and reflecting the irradiation light 201 from the lateral side on the surface of the optical plate 100b, as schematically shown in FIG. Either one of the functions can be performed, or both of these functions can be performed at the same time.
In addition, the said optical path is typical. It is not certain what light path the light is diffused in the normal direction. One reason is that the main diffusion direction of the light is not correct because the following linear shape portion is not exactly a vertically vertical surface, but is inclined slightly outward or inward in manufacturing or has fluctuations. It can be considered that the direction is linear. The normal direction represents not only a direction of 90 degrees with respect to the pattern surface but also a range of about 60 to 120 degrees.

The “light diffusion pattern 111” is an aggregate of light diffusion patterns 112 (including 113) and is a pattern capable of diffusing light.
The “light diffusion pattern 112” is a pattern capable of diffusing light. The light diffusion pattern 112 may be a convex pattern (see FIG. 8), a concave pattern (see FIG. 9), or a mixture of these. The convex pattern is a pattern protruding on the pattern surface of the optical plate, and the concave pattern is a pattern recessed on the pattern surface of the optical plate. The degree of unevenness of the convex pattern and the concave pattern is not particularly limited and is preferably set to an appropriate height or depth depending on the purpose and size of use of the optical plate. The depth is 1 to 30 μm (preferably 2 to 20 μm, more preferably 3 to 15 μm).

  Furthermore, at least a part of the light diffusion pattern is a light diffusion pattern having a specific shape having a linear shape portion and an arc shape portion. The “linearly shaped portion” is a portion in which a part of the outer peripheral shape in plan view is formed in a straight line shape. On the other hand, the “arc-shaped part” is a part in which the other part of the outer peripheral shape in plan view is formed in an arc shape. Hereinafter, the light diffusion pattern having the linear shape portion and the arc shape portion is also simply referred to as a “half moon pattern”.

  This half moon pattern may constitute all of the light diffusion pattern or only a part thereof. That is, the light diffusing pattern may consist only of a half moon pattern, or a half moon pattern may be provided in part. The ratio of the half moon pattern to the entire light diffusion pattern is not particularly limited, but the ratio of the number of half moon patterns to the number of all light diffusion patterns of the light diffusion pattern is 60% or more (more preferably 70% or more, More preferably, it is 85% or more, particularly preferably 100%. In the said range, the improvement effect of the light-diffusion performance by providing a half-moon pattern can be acquired.

  In the optical plate of the present invention, the half-moon pattern has a linear shape portion, so that a sufficient reflecting surface for irradiation light in each light diffusion pattern can be secured, and the light diffusion efficiency of the optical plate is improved. It is thought that. On the other hand, it is considered that the arc-shaped portion reflects reflected light from another light diffusion pattern located farther from the light source with respect to the half moon pattern and again reflects the other light diffusion pattern. In other words, a light-diffusing pattern that is a circular circle (perfect circle) has a larger reflection surface by having a linear portion, and can reflect light more efficiently in the normal direction. By having the arc-shaped portion, the light that has not been reflected by the linear-shaped portion is reflected again to the linear-shaped portion, thereby contributing to maximizing the effects of having the linear-shaped portion. (See FIG. 1). Moreover, the positional relationship between the linear shape portion and the arc shape portion requires that the linear shape portion is disposed on the side closer to the light source of the irradiation light with respect to the arc shape portion. This is considered necessary from each of the above roles.

  The specific shape of the arc (arc in plan view) in the arc-shaped portion in the half moon pattern is not particularly limited. That is, the arc shape can be a part of a perfect circle as shown in FIG. Further, as shown in FIG. 5, it can be a part of an ellipse. Furthermore, it can be a part of a parabola as shown in FIG. Furthermore, the shape which combined 2 or more types of these may be sufficient. Among these, a part of a perfect circle is particularly preferable. This is because more uniform reflection can be performed as compared to the case of other shapes, and unevenness is less likely to occur.

Further, as shown in FIGS. 4 to 6, a line segment P _A -P _S connecting the point P _A that bisects the arc A and the point P _S that bisects the straight line S is equal to the point P _S and the arc A Of the line segments connecting the upper points, the longest line segment is preferable. Namely, it is preferable that is located a linear portion and the arc-shaped portion so that the point P _A and the point P _S is disposed at the farthest position. When the linear shape portion and the arc shape portion are in this positional relationship, the light diffusion efficiency can be maximized.

In addition, as described above, since the linear shape portion and the circular arc shape portion are considered to have necessary functions, both of them are essential, but by optimizing the correlation between these sizes, Furthermore, the light diffusion efficiency can be improved. In particular, the arc constituting the arc-shaped portion is preferably a circular arc, and the arc is preferably a part of a perfect circle. Furthermore, the central angle of the arc (theta in Figure 4, the center of the circle and _{P C)} that is from 203 to 240 ° (length L / 2t = 0.6 to 0.75 in FIG. 7) preferable. In this range, particularly excellent light diffusion performance can be obtained. The reason is not clear, but it is recognized that the light diffusion performance tends to be highest when the central angle is 232.5 degrees (L / 2t = 0.72 in FIG. 7). The central angle is more preferably 215 to 240 degrees (L / 2t = 0.65 to 0.75 in FIG. 7), and 227 to 237 degrees (L / 2t = 0.70 to 0.74 in FIG. 7). ), Particularly preferably 230 to 235 degrees (L / 2t = 0.71 to 0.73 in FIG. 7). When the arc (superior arc) as described above is provided, a straight line when the linear shape portion is viewed in plan is a chord for the arc.
The central angle θ and L / 2t (the ratio of the semicircular diameter L to the diameter 2t) can be converted into each other by the following two equations.
θ = 2π− [2 × cos ⁻¹ {(L−t) / t}]
L / 2t = [cos {(2π−θ) / 2} / 2] +0.5

  Further, when the half moon pattern is a convex pattern, the convex pattern has a concave portion 116 (see FIGS. 10 and 12) in the center, and the inner peripheral shape when the convex pattern is viewed in plan view is The shape may be similar to the outer shape of a circular or convex pattern. That is, the case where the inner peripheral shape is a circle is the shape illustrated in FIG. 10 or a similar shape (the size of the circle is different, etc.). On the other hand, the case where the inner peripheral shape is similar to the outer peripheral shape of the convex pattern is the shape illustrated in FIG. 12 or a similar shape (the size of the similar shape is different, etc.). Further, when the half-moon pattern is a concave pattern, the concave pattern has a convex portion 117 (see FIGS. 11 and 13) in the center, and the inner peripheral shape when the concave pattern is viewed in plan view, The shape can be similar to a circular or concave outer peripheral shape. That is, the case where the inner peripheral shape is a circle is the shape illustrated in FIG. 11 or a similar shape (the size of the circle is different). On the other hand, the case where the inner peripheral shape is similar to the concave outer peripheral shape is the shape illustrated in FIG. 13 or a similar shape (the size of the similar shape is different, etc.). Among these inner peripheral shapes, a similar shape is preferable in both the convex pattern and the concave pattern. In this case, the inner peripheral shape also has a linear shape portion, and the reflection efficiency due to the linear shape portion is further improved.

When the convex pattern has a concave portion and the concave pattern has a convex portion, the light that could not be directly reflected by the linear shape portion can be reflected again. That is, when the planar view shape of the concave portion and the convex portion is circular, the outer peripheral shape functions as one light diffusion pattern, and the inner peripheral shape functions as another light diffusion pattern. Therefore, the convex pattern having the concave portion and the concave pattern having the convex portion each have two light diffusing patterns in one half-moon pattern, and can exhibit further excellent light diffusing ability.
Naturally, a concave portion is formed so as to have reflectivity in the convex pattern, and further, a convex portion is formed in the concave portion, thereby forming one light diffusion pattern corresponding to three light diffusion patterns. You can also. However, normally, each light diffusion pattern is a fine pattern, and it is difficult to form a triple or more shape.

  The correlation between the size of the outer peripheral shape and the inner peripheral shape is not particularly limited. For example, in the correlation between the outer peripheral length and the inner peripheral length, the inner peripheral length is 75% or less of the outer peripheral length (more preferably 5 to 65%). And more preferably 10 to 30%). In this range, it is possible to sufficiently obtain the effect of having the concave portion and the convex portion. In particular, when an LED of 2000 mcd or more is used as a light source, it is preferable that the inner circumference is small. That is, it is preferably 50% or less, and particularly preferably 10 to 30%. Moreover, when the circular arc shape part which comprises outer peripheral shape is a part of circle | round | yen, it may be concentric with an inner peripheral shape, and does not need to be concentric (namely, it may be eccentric).

Furthermore, the light diffusion pattern is an aggregate of light diffusion patterns. In the light diffusion pattern, the light diffusion patterns may be arranged in an aligned manner, may be arranged randomly, or may be aligned. It is also possible to have both a part arranged at random and a part arranged randomly. Among these, it is preferable that they are aligned. That is, the effect of using a half-moon pattern can be further improved by using an intended arrangement rather than randomly positioning.
Although this arrangement method is not particularly limited, for example, the light diffusion patterns can be aligned in a lattice pattern. That is, the optical plate can be provided with a light diffusion pattern arranged in a lattice pattern (see FIG. 14). When aligned in this grid pattern, the straight line connecting the vertices of adjacent light diffusion patterns (the point furthest from the light source—the point P _A in the half moon pattern) does not intersect the other light diffusion patterns (see FIG. 14).

Further, the light diffusion pattern can be aligned radially with respect to the light source. That is, the optical plate can be provided with light diffusing patterns arranged radially (see FIG. 15). When aligned in a radial pattern, the curve connecting the vertices of the adjacent light diffusion patterns (the point furthest from the light source—the point P _A in the half moon pattern) does not intersect the other light diffusion patterns (see FIG. 15).
When the light sources are located apart, a lattice shape is preferred, and when the light sources are located nearby, a radial shape is preferred. In particular, when aligned radially with respect to the light source, the light from the light source can be reflected particularly efficiently by the linear portion of the light diffusion pattern, and the diffusion efficiency can be improved.

The light diffusion pattern is particularly preferably arranged in a staggered manner. In the staggered arrangement, another light diffusing pattern is arranged between two adjacent light diffusing patterns that are the same distance from the light source. It means that the distance from the light source is arranged farther than the light diffusion pattern. FIG. 16 shows an example in which the light diffusion patterns are arranged in a lattice pattern and are staggered. In the case of this staggered arrangement, a straight line connecting apexes of adjacent light diffusion patterns (a point furthest from the light source—a point P _A in the half moon pattern) intersects with another light diffusion pattern (see FIG. 16). Further, FIG. 17 shows an example in which the light diffusion patterns are radially arranged and staggered. Also in this case, the curve connecting the vertices of the adjacent light diffusion patterns (the point farthest from the light source—the point P _A in the half moon pattern) intersects with the other light diffusion patterns (see FIG. 17).

Further, each light diffusing pattern may have the above-mentioned shape, but it is preferable to increase the size as the distance from the light source increases. That is, one of the two light diffusion patterns shared by the light source closest to the light source of the irradiated light and the light diffusion pattern arranged closer to the light source and the light source than the light diffusion pattern. When the other light diffusion pattern disposed at a distant position is viewed in plan, the size of each outer periphery is preferably such that one light diffusion pattern is smaller than the other light diffusion pattern. Such a light diffusion pattern is illustrated in FIG. 18 (FIG. 18 is arranged in a grid pattern, but can be arranged in a radial pattern, and can also be arranged in a staggered pattern).
In addition, although the said linear shape part of a half moon pattern is arrange | positioned with respect to the circular arc shape part at the side near the light source of irradiation light, for example, when there are two light sources, as shown in FIG. Can be placed back to back. The same applies when there are three or more light sources.

  In the optical plate of the present invention, in addition to the half-moon light diffusion pattern, other patterns can be used in combination with the half-moon pattern for the purpose of adjusting diffusion. Examples of other light diffusion patterns include a perfect light diffusion pattern, an elliptical light diffusion pattern, a triangular light diffusion pattern, and a rectangular light diffusion pattern. These may use only 1 type and may use 2 or more types together. Among these, it is preferable to use a perfect circular light diffusion pattern.

  The optical plate of the present invention may be translucent or non-translucent. When it is translucent, it can be used as a light guide plate, and can also be used as a reflection plate. On the other hand, when it is non-translucent, it can be used as a reflector. In addition, translucency is translucency with respect to irradiation light (a visible light, infrared rays, a far infrared ray, an ultraviolet ray etc. are included), and the transmissivity (thickness of 10 cm) is normally 85-95% with respect to the target light. Transmittance in the vertical direction).

  The method for producing the optical plate of the present invention is not particularly limited. That is, for example, the optical plate of the present invention is printed and pasted with a pattern to be the light diffusion pattern which is a separate body (may be the same material as the substrate or may be a different material) on the substrate, It can be added and formed by various methods such as plating. Further, the surface of the substrate can be formed to be missing by various methods such as cutting, etching, and die pressing so as to be the light diffusion pattern. Any one of these methods may be used, or two or more of them may be used in combination.

  The material constituting the optical plate of the present invention is not particularly limited. That is, an organic material and an inorganic material can be used. In the case where translucency with respect to visible light is required, a transparent resin (such as an acrylic resin, an epoxy resin, or a silicon resin), transparent glass, or the like can be used. In addition, in the optical plate body in which the light diffusion pattern is additionally formed on the substrate, the substrate and the light diffusion pattern may be the same material or different materials, but may be the same material. preferable. Even if the same material contains a light dispersant or the like as described later, the matrix of the substrate and the matrix of the light diffusion pattern are the same material (acrylic resins, epoxy resins, silicon resins, It is made of glass. This is because an optical interface between the substrate and the light diffusion pattern is hardly formed, and the effect of having the light diffusion pattern is more easily exhibited.

  Therefore, the optical plate can be an optical plate including a substrate made of acrylic resin and a light diffusion pattern made of acrylic resin printed on the surface of the substrate. Moreover, the board | substrate consisting of an acrylic resin and the light-diffusion pattern consisting of the acrylic resin containing the light dispersing agent printed and formed on the surface of this board | substrate can be provided. Quartz glass particles can be used as the light dispersant. Furthermore, an epoxy resin or a silicon resin can be used instead of the acrylic resin.

When quartz glass particles are used as the light dispersing agent, the quartz glass particles may be any particulate material made of quartz glass, but are preferably quartz glass particles containing impurities. As this impurity, an impurity containing at least one metal element selected from Al, Ti, Fe, Nb, Zr, Mn and Mo is preferable, and these oxides and / or double oxides are particularly preferable. That is, for example, Al ₂ O ₃ , TiO ₂ , Fe ₂ O ₃ , Nb ₂ O ₅ , ZrO ₂ , MnO _2, MoO _{2 and the} like can be mentioned. Although the content rate of the said impurity is not specifically limited, Usually, when the whole quartz glass particle is 100 mass%, 0.01-0.2 mass% (preferably 0.05-0. 2 mass%, more preferably 0.1 to 0.15 mass%) (when a plurality of elements are contained, the total amount in terms of oxide). Within this range, it is possible to most efficiently have translucency and light dispersibility. In addition, the oxide conversion is as follows: Al is Al ₂ O ₃ , Ti is TiO ₂ , Fe is Fe ₂ O ₃ , Nb is Nb ₂ O ₅ , Zr is ZrO ₂ , Mn is MnO ₂ , and Mo is MoO _2. To do.

  The size and shape of the quartz glass particles are not particularly limited, but the average particle size (maximum length) is 1 to 30 μm (more preferably 1 to 15 μm, still more preferably 2 to 10 μm, still more preferably 3 to 7 μm, Particularly preferably 4 to 6 μm, particularly preferably 4 to 5 μm). In this range, sufficient light dispersibility can be obtained while ensuring sufficient light transmission. The shape of the quartz glass particles is not particularly limited, but is usually spherical.

The content of the quartz glass particles is not particularly limited, but is 0.01 to 50% by mass (more preferably 1 to 45% by mass, still more preferably 10 to 45% by mass) when the entire light-transmitting resin is 100% by mass. And more preferably 20 to 43% by mass, particularly preferably 25 to 42% by mass, and particularly preferably 30 to 40% by mass).
Furthermore, the translucency in the quartz glass particles is a translucency for visible light, particularly 5% or more (more preferably 10 to 50%, still more preferably 20 to 60%) for light having a wavelength of 300 to 950 nm. ) Is preferable.

  In the case where the optical plate of the present invention is used as a light guide plate, and the parent phase constituting the optical plate is made of a translucent resin, the quartz glass particles are converted into the light diffusing material. It can be contained not only in the pattern but also in the optical plate itself. In this case, when the entire translucent resin is 100% by mass, the quartz glass particles are contained in a proportion of 0.2 to 0.4% by mass (more preferably 0.3 to 0.4% by mass). Is preferred.

  Moreover, visible light, infrared rays, far infrared rays, ultraviolet rays, or the like can be used as the irradiation light. Furthermore, examples of the light source of the irradiation light include LEDs, cathode tubes (cold cathode tubes, hot cathode tubes, black lights, etc.), light bulbs, and the like. These may use only 1 type and may use 2 or more types together.

When the optical plate 100 of the present invention is used, particularly when the optical plate 100 itself has translucency, the reflective layer 300 is provided on the surface opposite to the direction in which light is emitted or reflected (normal direction). It can be provided (see FIGS. 20 and 21). As the reflective layer 300, a metal film or the like can be used. As the metal constituting the metal film, Al, Ag, or the like can be used. These may use only 1 type and may use 2 or more types together.
Further, as described above, the light diffusion direction is not only the normal direction of 90 degrees with respect to the pattern surface, but is usually a normal direction of 60 to 120 degrees with respect to the pattern surface. The light direction can be changed to an optical path closer to 90 degrees with respect to the pattern surface, and the luminance from the front can be further improved. That is, the prism sheet can be used.

[2] Light guide plate The light guide plate of the present invention comprises the optical plate of the present invention, the optical plate has translucency, and the irradiated light is incident on the optical plate from the side. The light is diffused and emitted in the normal direction with respect to the pattern surface (see FIGS. 2 and 20).
As the optical plate in this light guide plate, an optical plate having translucency among the optical plates can be applied as it is. Furthermore, the light guide plate of the present invention is provided with a convex pattern, and the convex pattern is preferably made of a composite material containing a translucent resin as a parent phase and quartz glass particles as a dispersed phase. As the translucent resin, the translucent resin in the optical plate can be applied as it is. Further, the quartz glass particles in the optical plate can be applied as they are to the quartz glass particles.

[3] Reflector The reflector of the present invention is composed of the optical plate of the present invention, the light diffusion pattern is composed of a light reflective metal film, and the irradiated light is diffused and reflected in the normal direction to the pattern surface. (See FIGS. 3 and 21).
When used as this reflector, a convex pattern is usually used as the light diffusion pattern. Furthermore, it is preferable that this convex pattern has reflectivity with respect to irradiation light. For this reason, it is preferable to comprise a convex pattern from at least one of metal plating and metal foil.

Hereinafter, the present invention will be described specifically by way of examples.
(1) Manufacture of optical plate (light guide plate) UV curable acrylic resin ink is applied to the surface of a 300 mm x 400 mm acrylic resin plate (colorless and transparent, 10 cm thickness light transmittance 90%) by silk screen printing. It printed so that it might become a light-diffusion pattern which consists of the light-diffusion pattern of Experimental example 1-5, Then, it was made to harden | cure and the optical board was formed. The light diffusion pattern was formed according to the pattern list shown in FIGS. “2t” in FIGS. 24 to 31 is the diameter of the basic circle corresponding to twice the value of “t” in FIG. Further, “L” in FIGS. 24 to 31 is a side diameter corresponding to L in FIG. 7. Further, “X-axis position” indicates a relative shift position in the X-axis direction with respect to the previous light diffusion pattern having a smaller No, and “Y-axis position” in FIG. The relative shift position in the Y-axis direction with respect to the diffusion pattern is shown. Therefore, for example, the light diffusion pattern of Experimental Example 3 has one row of 135 half-moon patterns shown in FIGS. 28 and 29, and one row of half-moon patterns in the X-axis direction is shown in FIG. 32 in the Y-axis direction. Are formed over 132 rows at the Y-axis position shown in FIG. Further, adjacent rows in the Y-axis direction are staggered so as not to be coaxial in the X-axis direction.

That is, the light diffusion pattern in each experimental example is as follows.
Experimental Example 1 (Comparative product);
According to FIGS. 24, 25 and 32, perfect light diffusion patterns are arranged in a grid pattern and in a staggered arrangement.
Experimental Example 2 (product of the present invention);
According to FIGS. 26, 27 and 32, light diffusing patterns of five-minute circles are arranged in a grid pattern and in a staggered arrangement.
Experimental Example 3 (product of the present invention);
According to FIGS. 28, 29 and 32, the light diffusing patterns of 7-circles are arranged in a grid and in a staggered arrangement.
Experimental Example 4 (product of the present invention);
According to FIGS. 28, 29 and 32, the light diffusing patterns of the seven circles having the concave portions were arranged in a lattice pattern and in a staggered arrangement. Concave part is formed as a concentric circle with a circumference of 30-60% of the basic diameter (2t) (30% in the half-moon pattern with the smallest basic diameter and 60% in the half-moon pattern with the largest basic diameter) Is a recess).
Experimental Example 5 (product of the present invention);
According to FIGS. 30, 31, and 32, light diffusing patterns of octants are arranged in a lattice and staggered arrangement.

(2) Installation of LED Furthermore, the white plate of 800 mcd was used as the light source on the 400 mm side surface of each of the optical plates in Experimental Examples 1 to 5 obtained above, and the light source was 13 mm (31 at 13 mm intervals at both ends of 5 mm). The above LEDs were arranged and fixed in an arrangement). Six of these white LEDs were connected in series, and five sets (of which one set was seven in series) were connected in parallel, and 20 mA was applied to each set to emit light. Irradiation light from these white LED chips is incident from the side surface of the optical plate.

(3) Measurement of luminance All of the above LEDs were turned on, and the luminance at each of 15 locations a to o shown in FIG. 22 was measured using a luminance meter (model “LS-100” manufactured by Konica Minolta Holdings, Inc.). . In the measurement, a luminance meter was fixed 75 cm above the center of the optical plate, and the luminance at each measurement point was measured by sequentially focusing each measurement point a to o. The results are shown in Table 1. Furthermore, the average value was calculated and shown in Table 1.

(4) Results As a result of the measurement in (3) above, the average luminance of Experimental Example 1 using a perfectly circular light diffusion pattern that has been frequently used was 199 cd / m ² . On the other hand, it can be seen that the average luminance of Experimental Example 2 using the light diffusing pattern of a quintic circle is 221 cd / m ^2, which is improved by about 11%. Furthermore, as shown in Experimental Example 5, it can be seen that the average luminance in the case of an october is 219 cd / m ^2, which is improved by about 10%. From this result, it can be seen that the luminance can be improved by having the linearly shaped portion of the light diffusion pattern with respect to the perfect light diffusion pattern.

In addition, as shown in Experimental Example 3, the average luminance in the case of a 7.2 minute circle (without a concave portion) is 244 cd / m ^2, which is improved by about 23% compared with Experimental Example 1, and compared with Experimental Example 2. Is also improved by about 10%. From this result, it can be seen that the luminance can be further improved by controlling the size of the linear portion.
Further, as shown in Experimental Example 4, the average luminance in the case of a 7.2-divided circle and further having a perfect circular recess is 270 cd / m ^2, which is about 36% higher than Experimental Example 1 and is higher than that of Experimental Example 3. Even about 11% improvement. From this result, it can be seen that the luminance can be further improved by forming a reflective surface (concave portion) inside the light diffusion pattern in addition to the linear shape portion.
In addition, the variation in luminance between observation positions in Experimental Example 1 (the ratio of the difference between the maximum luminance and the minimum luminance to the maximum luminance) was 15.8%. In Experimental Example 2, it was 26.7%, in Experimental Example 3, it was 10.9%, in Experimental Example 4, it was 19.3%, and in Experimental Example 5, it was 28.5%. That is, it can be seen that in Experimental Examples 3 and 4, the variation in luminance tends to be reduced compared to the others.

  In addition, in this invention, it can restrict to what is shown to said specific Example, It can be set as the Example variously changed within the range of this invention according to the objective and the use.

It is a typical perspective view of an example which shows the outline of this optical board. It is explanatory drawing which shows typically an optical path at the time of using an example of this optical board as a light-guide plate. It is explanatory drawing which shows typically an optical path at the time of using an example of this optical board as a reflecting plate. It is explanatory drawing which shows the shape at the time of planarly viewing an example of a light-diffusion pattern. It is explanatory drawing which shows the shape at the time of planar view of the other examples of a light-diffusion pattern. It is explanatory drawing which shows the shape at the time of planarly viewing another example of a light-diffusion pattern. It is explanatory drawing explaining the shape of an example of a light-diffusion pattern. It is a perspective view which shows an example of a convex pattern typically. It is a perspective view which shows an example of a concave pattern typically. It is a perspective view which shows typically an example of the light-diffusion pattern which is a convex pattern and has a circular recessed part. It is a perspective view which shows typically an example of the light-diffusion pattern which is a convex pattern and has a recessed part with which an outer periphery shape and an inner peripheral shape become similar. It is a perspective view which shows typically an example of the light-diffusion pattern which is a concave pattern and has a circular convex part. It is a perspective view which shows typically an example of the light-diffusion pattern which is a concave pattern and has the convex part from which an outer periphery shape and an inner peripheral shape become similar. It is a typical top view which shows the state in which the light-diffusion pattern was arranged in the grid | lattice form. It is a typical top view which shows the state in which the light-diffusion pattern was aligned radially with respect to the light source. It is a typical top view which shows the state of an example by which the light-diffusion pattern is staggered arrangement | positioning. It is a typical top view which shows the state of the other example by which the light-diffusion pattern is staggered arrangement | positioning. It is explanatory drawing explaining the difference in the magnitude | size by the distance from the light source of a light-diffusion pattern. It is a typical top view showing a light diffusion pattern in case there are two or more light sources. It is a typical sectional view explaining an optical board provided with an integral reflective layer. It is a typical sectional view explaining an optical board provided with a separate reflective layer. It is explanatory drawing which shows the brightness | luminance measurement position which concerns on an Example. It is a typical perspective view which shows the outline | summary of the conventional light-diffusion pattern. It is a pattern list | wrist which shows the shape and X-axis position of the light-diffusion pattern which concerns on Experimental example 1 (perfect circle). It is a pattern list | wrist which shows the shape and X-axis position of the light-diffusion pattern which concerns on Experimental example 1 (perfect circle). It is a pattern list | wrist which shows the shape and X-axis position of the light-diffusion pattern which concerns on Experimental example 2 (5-part circle). It is a pattern list | wrist which shows the shape and X-axis position of the light-diffusion pattern which concerns on Experimental example 2 (5-part circle). It is a pattern list | wrist which shows the shape and X-axis position of the light-diffusion pattern which concern on Experimental example 3 (seventh circle) and Experimental example 4 (seventh circle with a recessed part). It is a pattern list | wrist which shows the shape and X-axis position of the light-diffusion pattern which concern on Experimental example 3 (seventh circle) and Experimental example 4 (seventh circle with a recessed part). It is a pattern list | wrist which shows the shape and X-axis position of the light-diffusion pattern which concerns on Experimental example 5 (eight-circle). It is a pattern list | wrist which shows the shape and X-axis position of the light-diffusion pattern which concerns on Experimental example 5 (eight-circle). It is a pattern list | wrist which shows the Y-axis position of the light-diffusion pattern common to Experimental Examples 1-5.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100: Optical board 110: Pattern surface 111: Light diffusion pattern 112: Light diffusion pattern 113: Half moon pattern (light diffusion pattern which has a linear shape part and an arc-shaped part) 114: Linear shape part 115 Arc-shaped portion, 116; concave portion, 117; convex portion, 100a; light guide plate, 100b; reflector, 200; light source, 201; optical path, 300;

Claims (10)

An optical plate that includes a pattern surface on which a light diffusion pattern is formed, and diffuses irradiation light from the side of the pattern surface in a normal direction to the pattern surface,
The light diffusion pattern is composed of an aggregate of at least one light diffusion pattern of a convex pattern and a concave pattern provided on the pattern surface,
At least a part of the light diffusion pattern of the light diffusion pattern includes a linear shape part in which a part of the outer peripheral shape in plan view is formed in a straight line, and a circular part in the other part of the outer peripheral shape in plan view. An arcuate shape portion, and
The optical plate body, wherein the linear shape portion is disposed on a side closer to the light source of the irradiation light with respect to the arc shape portion. The arc-shaped part is an arc having a central angle of 203 to 240 degrees,
The optical plate according to claim 1, wherein the linearly-shaped portion is a string with respect to the arc. The convex pattern has a concave portion at the center,
The optical plate according to claim 1 or 2, wherein an inner peripheral shape of the convex pattern in plan view is circular or similar to the outer peripheral shape of the convex pattern. The concave pattern has a convex portion at the center,
3. The optical plate according to claim 1, wherein an inner peripheral shape of the concave pattern in plan view is circular or similar to the outer peripheral shape of the concave pattern.   The optical plate according to claim 1, wherein the light diffusion patterns are arranged radially with respect to the light source of the irradiation light.   The optical plate according to claim 1, wherein the light diffusion pattern has a staggered arrangement.   Of the two light diffusion patterns that share the light source closest to the light source of the irradiation light, one light diffusion pattern disposed closer to the light source, and the one light diffusion pattern When the other light diffusion pattern disposed at a position far from the light source is viewed in plan, the size of each outer periphery is smaller in the one light diffusion pattern than the other light diffusion pattern. The optical plate according to any one of 1 to 6.   The optical plate according to any one of claims 1 to 7, wherein the optical plate has translucency, and the irradiation light is incident on the optical plate from the side, The light guide plate according to claim 1, wherein the irradiation light is diffused and emitted in a direction normal to the pattern surface.   The light guide plate according to claim 8, comprising the convex pattern, wherein the convex pattern is made of a composite material having a translucent resin as a parent phase and containing quartz glass particles as a dispersed phase.   The optical plate according to any one of claims 1 to 7, wherein the light diffusion pattern is made of a light reflective metal film, and the irradiation light is diffused and reflected in a normal direction to the pattern surface. A reflector characterized by that.

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