JP2001051125A - Light guide plate and plane lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently emit light, to allow a bright and uniform luminance, to prevent generation of moire and to prevent generation of a bright line. SOLUTION: This light guide plate 2 has convex or concave dot parts 9 aligned continuously or side by side, parallel to an incident end face part 3, and arranged in parallel on a front face part 5 or a rear face part 6. A gap between first dots 9 and the succeeding dots 9 aligned continuously or side by side from the incident end face part 3 side is set to a value gotten by dividing a distance from the incident end face part 3 to the first dots 9 aligned continuously or side by side by (1.5-1.8)1/2, while a succeeding gap to a reflection end face part 4 direction is subsequently set to a value gotten by dividing the preceding gap by (1.5-1.8)1/2. Simultaneously, the dot parts 9 are dispersed in the gaps at random with a distribution amount of 0.2-1 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight or the like used for a liquid crystal display device or the like, in which convex or concave dots are arranged in parallel or in parallel with an incident end face of a light guide plate. The present invention relates to a light guide plate and a planar lighting device capable of realizing bright and uniform outgoing light by arranging or juxtaposed at predetermined intervals.

[0002]

2. Description of the Related Art As a conventional light guide plate, in order to uniformly emit light incident from an incident end face portion, dots of white ink or the like are printed on the back surface at a higher dot density as the distance from the incident end face portion increases, or the density of incident light increases. It is known that the dot area is increased as the distance from the end surface increases, and the entire light guide plate is made uniform by increasing the amount of reflected light from the dots.

Further, as a conventional light guide plate, convex and concave portions are randomly arranged on the front surface and the rear surface of the light guide plate, and the light is emitted to the surface and the like by using refraction and total reflection. It is also known that the more the light is distributed, the more refraction and total reflection are performed as the energy of the light is reduced to obtain uniform outgoing light over the entire light guide plate.

Further, a conventional light guide plate is disclosed in
The thing shown in 184920 gazette is known. This light guide plate is a type in which light sources are provided on both sides, but a plurality of V-grooves having prism surfaces on the back surface are arranged side by side, and the distance between the V-grooves increases as the distance from the light source increases. It compensates for the darkness of the part. Further, there is also known a method in which a distance Xn from an end-side fixed point of the n-th V-groove is applied at a V-groove interval that satisfies the formula of Xn = (a * n) ^{1 / c} + b.

[0005]

As a conventional light guide plate,
In order to uniformly emit the light incident from the incident end face, the dots such as white ink are printed on the back side with a higher dot density as the distance from the incident end face is increased, or the dot area is increased as the distance from the incident end face increases. In the case where the entire light guide plate is made uniform by increasing the amount of light reflected from the dots, there is a problem in conversion efficiency due to light energy loss due to light absorption due to scattering substances mixed in the white ink, and the size of the dot area is increased. There is a problem that pod density is limited.

Further, as a conventional light guide plate, convex and concave portions are randomly arranged on the front surface and the rear surface of the light guide plate, and the light is emitted to the surface or the like by using refraction or total reflection, and the incident end surface is used. If the light is distributed more as the distance from the light source increases and the refraction and total reflection increase as the energy of the light decreases to obtain uniform outgoing light over the entire light guide plate, the light from the light source is guided as shown in FIG. When the light enters the incident end face 33 of the light plate 32,
Assuming that the refraction angle is γ, the light travels in the light guide plate 32 within a range satisfying the equation of 0 ≦ | γ | ≦ sin ⁻¹ (1 / n). Light guide plate 32
Boundary surface (surface portion 35, between the air layer and the air layer (refractive index n ₀ = 1))
In the back surface part 36), sinC = (n ₀ / n) = (1 /
The critical angle can be expressed by the equation n). For example, since the refractive index of an acrylic resin, which is a resin material used for a general light guide plate 32, is about n = 1.49, the maximum value γ of the refraction angle and the critical angle α are γ = 42 ° and α = 42. °.

Further, the surface portion 35 of the light guide plate 32 having a thickness d
The length S1 of a light beam connecting point A and point B that repeat total internal reflection at a critical angle α of about 42 ° between
d / cos θ (where θ is the surface part 3
(Emission angle formed with the normal line of 5) It is more efficient to arrange a convex portion or a concave portion that breaks the critical angle at a point corresponding to the position such as point A or point B, and the light guide plate 32 has a wedge-like shape. However, the same can be said, and there is a problem in efficiency when convex portions and concave portions are randomly arranged on the front surface portion 35 and the rear surface portion 36 of the light guide plate 32.

Further, Japanese Patent Application Laid-Open No. 9-184920 discloses
The disclosed conventional light guide plate has a light source on both sides.
However, a plurality of V-grooves having a prism surface on the back side are juxtaposed.
Then, as the distance from the light source increases, the interval between the V grooves becomes smaller.
To compensate for the darkness of the part far from the light source,
Is the distance Xn from the fixed point on the end side, Xn = (a * n)
^{1 / c}When V-grooves are provided at V-groove intervals that apply to the formula + b
As described with reference to FIG.
At the point corresponding to the arrangement of the V groove parallel to the incident end face 33
When this occurs, abnormally high-luminance emission or V-grooves become
A bright line is generated in the vicinity of the incident end face 33 because of the parallelism.
There are challenges.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to connect a convex or concave dot portion on a front surface or a rear surface of a light guide plate in parallel with a light incident end surface in parallel. The distance of the first continuous or juxtaposed distance from the incident end face is 1.5 to
By dividing by the square root of 1.8 and sequentially dividing the next interval in the direction of the reflecting end face by the square root of 1.5 to 1.8, the incident interval near the light source is obtained. It is an object of the present invention to provide a light guide plate and a planar lighting device capable of obtaining uniform and bright light without generating a bright line in the vicinity.

[0010]

According to a first aspect of the present invention, there is provided a light guide plate having convex or concave dots formed on a front surface and / or a rear surface thereof in parallel with and parallel to an incident end surface. The distance of continuous or juxtaposed, and the distance of the serial or juxtaposed first from the incident end face is 1.
It is characterized in that it is divided by a square root of 5 to 1.8 and a value obtained by sequentially dividing the next interval in the direction of the reflection end face by the square root of 1.5 to 1.8.

According to the first aspect of the present invention, the light guide plate has a surface portion and / or
And a dot portion having a convex or / and a concave shape on the rear surface portion is continuously or juxtaposed in parallel with the incident end surface portion, and the interval of the continuous or juxtaposed distance is the distance of the first continuous or juxtaposed sequence from the incident end surface portion. Is divided by the square root of 1.5 to 1.8, and the next interval is set to 1.
Since the value is divided by the square root of 5 to 1.8, the light can be reflected or refracted efficiently.

Further, the light guide plate according to claim 2 is characterized in that the dot portions are randomly dispersed with a distribution amount of 0.2 to 1 ppm between the intervals.

In the light guide plate according to the second aspect of the present invention, the dot portions are randomly dispersed with a distribution amount of 0.2 to 1 ppm between the intervals. By disposing them side by side, the occurrence of moire is prevented, and the distribution amount is set to 0.
Since it is about 2 to 1 ppm, it does not obstruct the light emitted from the dot portions 9 which are inconspicuously arranged or juxtaposed, and furthermore, the surface portion 5
Since the projections and depressions formed on the back and back portions 6 and the like are not linear like grooves and prisms but are formed by the dot portions 9, it is possible to prevent the generation of bright lines.

Further, the flat lighting device according to claim 3 is
Convex or / and concave dots are formed on the surface or / and the back of the light guide plate in parallel or in parallel with the incident end face, and the interval of the continuous or juxtaposed first is set from the incident end face. The successively or arranged distances were divided by the square root of 1.5 to 1.8, and the next interval in the direction of the reflection end face was successively divided by the square root of 1.5 to 1.8. It is characterized by a value.

According to a third aspect of the present invention, in the flat lighting device, a convex or / and a concave dot portion is provided in parallel on the front surface portion and / or the rear surface portion of the light guide plate in parallel or parallel with the incident end surface portion. The distance to be provided or arranged side by side is divided by the square root of 1.5 to 1.8 from the incident end face first, and the next distance is successively set in the direction of the reflective end face to the immediately preceding distance. Is divided by the square root of 1.5 to 1.8, so that reflection and refraction can be performed efficiently.

According to a fourth aspect of the present invention, in the flat lighting device, a convex or / and a concave dot portion is provided on the front surface portion and / or the rear surface portion of the light guide plate in parallel or in parallel with the incident end surface portion. The distance between the continuous or juxtaposed portions is divided by the square root of 1.5 to 1.8 from the incident end face portion at the first time, and the next interval in the direction toward the reflective end face portion is successively reduced. The method is characterized in that the interval distance is a value obtained by dividing by a square root of 1.5 to 1.8, and that the interval distance is randomly distributed with a distribution amount of 0.2 to 1 ppm during the interval.

According to a fourth aspect of the present invention, in the flat illumination device, a convex or / and a concave dot portion is provided on the front surface portion and / or the rear surface portion of the light guide plate in parallel or in parallel with the incident end surface portion. The distance to be provided or arranged side by side is divided by the square root of 1.5 to 1.8 from the incident end face first, and the next distance is successively set in the direction of the reflective end face to the immediately preceding distance. Is divided by the square root of 1.5 to 1.8 and is randomly dispersed with a distribution amount of 0.2 to 1 ppm between the intervals. The arrangement or juxtaposition is broken to prevent the occurrence of moire. Further, since the distribution amount is about 0.2 to 1 ppm, it does not obstruct the light emitted from the dot portions 9 which are inconspicuously arranged or juxtaposed. The convex or concave shape on the back surface 6 etc. is a line like a groove or a prism In no Since consisting dot portion 9 can prevent the occurrence of bright lines.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

According to the present invention, convex or concave dot portions are provided on the front surface or the rear surface of the light guide plate in parallel or in parallel with the incident end face, and the interval of these continuous or juxtaposed is set to the incident end face. , The distance that was first connected or arranged side by side is divided by the square root of 1.5 to 1.8, and the next distance in the direction of the reflection end face is sequentially increased by the square root of 1.5 to 1.8. It is an object of the present invention to provide a light guide plate and a flat illumination device which can obtain uniform and bright light without generating a bright line near an incident end face near a light source.

FIG. 1 is a schematic perspective view of a flat lighting device according to the present invention.

The flat lighting device 1 shown in FIG. 1 includes a light guide plate 2, a light source 10, a reflector 11 and a reflector 12.

The light guide plate 2 is made of a transparent acrylic resin (PMMA) or polycarbonate (PC) having a refractive index of about 1.4 to 1.7, and is formed of an incident end face 3 for guiding light from the light source 10. A reflecting end face 4 located on the opposite side of the incident end face 3; side faces 7 and 8 connected to the incident end face 3 and the reflecting end face 4; a light emitting surface 5; 5 and a back surface portion 6 located on the opposite side.

The light guide plate 2 includes a front surface 5 and a rear surface 6.
A dot portion 9 having a convex shape, a concave shape, or the like is formed on the substrate. This
After the light from the light source 10 is incident on the incident end face 3,
≦ | γ | ≦ sin^-1Refraction within the range satisfying the expression (1 / n)
The light advances into the light guide plate 2 at an angle γ (γ = about ± 42 °). Soshi
The boundary surface between the front surface portion 5 and the back surface portion 6 (air layer (refractive index n
₀= 1)), sinC = (n₀/ N) = (1 / n)
Refracts light near the critical angle α (α = about 42 °) at
Then, the light is emitted to the outside, but as shown in FIG.
Total reflection is repeated between the front surface portion 5 and the rear surface portion 6 of the light guide plate 2
The length S1 of the light beam is S1 in the thickness d of the light guide plate 2.
= D / cos θ, where the position
Make sure that the convex and concave parts are located at the corresponding points.
The dot portions 9 having a convex shape, a concave shape, etc.
It is provided continuously or side by side on the back surface 6 or the like.

Further, the interval at which the dot portions 9 are continuously or juxtaposed is a distance obtained by dividing the distance at which the dot portions 9 are initially juxtaposed or juxtaposed by the square root of 1.5 to 1.8 from the incident end face portion 3. The dot portion 9 is provided as a value obtained by sequentially dividing the next interval in the direction of the reflection end face 4 by the square root of 1.5 to 1.8.

Table 1 shows the ratio when the arrangement of the dot portions 9 according to the present invention is divided by the square root of 1.65. Hereinafter, Tables 1 and 2 show the tendency of the distribution amount of dots when the horizontal axis 0 is the light incident portion (incident end surface portion 3) and is directed toward the reflective end surface portion 4.

[0026]

[Table 1]

Further, regarding the conventional light guide plate disclosed in Japanese Patent Application Laid-Open No. 9-184920, the distance between the V-grooves is n
The distance Xn from the fixed point on the end side of the V-th groove is Xn =
(A * n) As an example applied to the formula of ^{1 / c} + b,
Table 2 shows the ratio when a = 60, b = 130 and c = 3.

[0028]

[Table 2]

As described above, in the distribution table 1 according to the present invention and the conventional distribution table 2, the rise near the incident end face 3 is different, and the light guide plate 2 according to the present invention has the reflection and the near near the incident end face 3. As the distance from the incident end face portion 3 is increased without performing processing such as refraction, the distance is not completely linear, and the distance where the dot portions 9 are continuously or juxtaposed is divided by the square root of 1.5 to 1.8.
Light is emitted uniformly from the incident end face 3 to the reflective end face 4 and no bright line is generated near the incident end face 3.

Further, the light guide plate 2 includes a front surface portion 5 and a back surface portion 6.
0.2 to 1 between the intervals of the dot portions 9 such as convex or concave.
Since it is formed so as to be randomly dispersed with a distribution amount of ppm, even when densely connected or arranged side by side, partial connection or juxtaposition is broken to prevent the occurrence of moire, and the distribution amount is 0.2
Since it is about 1 ppm, it does not obstruct the light emitted from the dot portions 9 which are inconspicuous and continuous or juxtaposed, and furthermore, the convex or concave shape applied to the front surface portion 5 or the rear surface portion 6 is like a groove or a prism. Since it is not a linear shape but composed of dot portions 9, no bright line is generated.

The light source 10 has a linear shape such as a CFL (cold shadow tube). Direct light enters the light guide plate 2 from the incident end face 3 of the light guide plate 2, and other light is reflected by the reflector 11. The light enters the light guide plate 2 through the space between the light source 10 and the reflector 11.

The reflector 11 is made of a sheet or metal or the like on which a white insulating material or a metal such as aluminum is deposited. Is reflected, and the reflected light is again incident on the incident end face 3 of the light guide plate 2.

The reflector 12 may be a sheet in which a white material such as titanium oxide is mixed in a thermoplastic resin, a sheet of a thermoplastic resin on which a metal such as aluminum is deposited, a metal foil is laminated, or a sheet metal. Etc. This reflector 12 covers portions other than the incident end face portion 3 and the surface portion 5,
The light from the light source 10 reflects or diffusely reflects light other than the light emitted from the light guide plate 2 to the surface portion 5, and is again incident on the light guide plate 2 so that all the light from the light source 10 is emitted from the surface portion 5. .

As described above, according to the light guide plate and the flat lighting device of the present invention, the convex or concave dot portions are provided in parallel on the front surface portion or the rear surface portion of the light guide plate in parallel or parallel with the incident end face portion, and The distance to be continuously or juxtaposed is divided by the square root of 1.5 to 1.8 from the incident end face first, and the next interval in the direction of the reflection end face is set to the immediately preceding interval. The distance is a value obtained by dividing by a square root of 1.5 to 1.8, and the dot portions are randomly dispersed with a distribution amount of 0.2 to 1 ppm between intervals. Dots are not linear, such as grooves or prisms that emit bright lines with high brightness at positions on the front and back that coincide with light rays that repeat total internal reflection at about the critical angle in the light guide plate without being randomly arranged. To emit light efficiently and obtain bright and uniform brightness. It is possible to prevent the occurrence of bright lines while preventing occurrence of moire.

[0035]

As described above, in the light guide plate according to the first aspect, the convex or / and concave dots are formed on the front surface and / or the rear surface in parallel or in parallel with the incident end face. Then, the distance between the continuous or juxtaposed portions is divided by the square root of 1.5 to 1.8 from the incident end face portion first, and the next interval in the direction toward the reflective end face portion is sequentially shifted forward by one. Is a value obtained by dividing the distance by the square root of 1.5 to 1.8, the light can be efficiently reflected or refracted, and a bright and uniform luminance can be obtained.

In the light guide plate according to the second aspect of the present invention, the dot portions are randomly dispersed with a distribution amount of 0.2 to 1 ppm between the intervals, so that even when the dots are densely arranged or juxtaposed, they are partially connected. The arrangement or juxtaposition is broken to prevent the occurrence of moire. Further, since the distribution amount is about 0.2 to 1 ppm, it does not obstruct the light emitted from the dot portions 9 which are inconspicuously arranged or juxtaposed. The convex and concave portions formed on the back and back portions 6 and the like are not linear such as grooves and prisms but are formed by the dot portions 9, so that a stable and uniform light source can be obtained without generation of bright lines.

Further, the flat lighting device according to claim 3 is
Convex or / and concave dots are formed on the surface or / and the back of the light guide plate in parallel or in parallel with the incident end face, and the interval of the continuous or juxtaposed first is set from the incident end face. The successively or arranged distances were divided by the square root of 1.5 to 1.8, and the next interval in the direction of the reflection end face was successively divided by the square root of 1.5 to 1.8. Since it is a value, it can be efficiently reflected and refracted, and a bright and uniform luminance can be obtained.

According to a fourth aspect of the present invention, in the flat lighting device, a convex or / and a concave dot portion is provided on the front surface portion and / or the rear surface portion of the light guide plate in parallel or in parallel with the incident end face portion. The distance between the continuous or juxtaposed portions is divided by the square root of 1.5 to 1.8 from the incident end face portion at the first time, and the next interval in the direction toward the reflective end face portion is successively reduced. Since the interval distance is divided by a square root of 1.5 to 1.8 and is randomly dispersed with a distribution amount of 0.2 to 1 ppm between the intervals, even when densely connected or juxtaposed, partial The moire is prevented by disturbing the connection or juxtaposition, and since the distribution amount is about 0.2 to 1 ppm, it does not obstruct the light emitted from the dot section 9 which is inconspicuous or juxtaposed. The convex or concave shape applied to the portion 5 or the back surface 6 etc. Since consisting dot portion 9 instead of a linear, prevents occurrence of bright lines, it is possible to obtain a legible flat light source.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a flat lighting device according to the present invention.

FIG. 2 shows a conventional light guide plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Planar illumination device, 2, 32 ... Light guide plate, 3, 33 ... Incident end face part, 4 ... Reflection end face part, 5, 35 ... Surface part, 6, 36
.., Back side, 7, 8 side surface, 9 dot section, 10 light source, 11 reflector, 12 reflector, A, B point, d
... thickness, γ ... refraction angle, n ₀ , n ... refractive index, α ... critical angle,
θ: outgoing angle, S1: length of light beam.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // F21Y 103: 00 F term (reference) 2H038 AA55 BA06 2H091 FA14Z FA23Z FA41Z FB02 FB08 LA18 5G435 AA01 BB12 EE27 FF08 GG24 HH04

Claims (4)

[Claims] An incident end face for receiving light, a reflecting end face located on the opposite side of the incident end face, a surface emitting light from the incident end face, and a face opposite to the surface. A light guide plate comprising a rear surface portion located on the front surface portion and / or the rear surface portion of the light guide plate, wherein convex or / and concave dot portions are arranged in parallel or parallel to the incident end surface portion. The distance between the continuous or juxtaposed portions is divided by the square root of 1.5 to 1.8 from the incident end face first, and the next interval in the direction of the reflective end face is sequentially determined. A light guide plate, wherein a value obtained by dividing a previous interval distance by a square root of 1.5 to 1.8 is used. 2. The method according to claim 1, wherein the distance between the dots is 0.2.
The light guide plate according to claim 1, wherein the light guide plate is randomly dispersed in a distribution amount of １1 ppm. 3. A light source, an incident end face for guiding light from the light source, a reflective end face located on the opposite side to the incident end face, and a side face connected to the incident end face and the reflective end face A light guide plate having a surface portion for emitting light guided from the incident end surface portion, and a back surface portion located on the opposite side to the front surface portion; and reflecting light from the light source and re-entering the incident end surface portion. A flat illumination device comprising a reflector for causing the light guide plate to have a convex or / and a concave dot portion on the front surface portion and / or the rear surface portion in parallel or parallel to the incident end face portion. The distance of the continuous or juxtaposed arrangement is divided by the square root of 1.5 to 1.8 from the incident end face first, and the following distance is sequentially set in the direction of the reflective end face. The previous distance is 1. A flat illuminating device, wherein the value is obtained by dividing by a square root of 5 to 1.8. 4. A light source, an incident end face for guiding light from the light source, a reflective end face located on the opposite side to the incident end face, and a side face connected to the incident end face and the reflective end face A light guide plate having a surface portion for emitting light guided from the incident end surface portion, and a back surface portion located on the opposite side to the front surface portion; and reflecting light from the light source and re-entering the incident end surface portion. A flat illumination device comprising a reflector for causing the light guide plate to have a convex or / and a concave dot portion on the front surface portion and / or the rear surface portion in parallel or parallel to the incident end face portion. The distance of the continuous or juxtaposed arrangement is divided by the square root of 1.5 to 1.8 from the incident end face first, and the following distance is sequentially set in the direction of the reflective end face. The previous distance is 1. A flat illuminating device characterized in that a value obtained by dividing by a square root of 5 to 1.8 and a distribution amount of 0.2 to 1 ppm are randomly distributed between the intervals.