JP2015213051A - Manufacturing method of surface light source and surface light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a surface light source capable of acquiring a surface light source having desired luminance, and a surface light source.SOLUTION: In a manufacturing method of a surface light source, light emission means is provided on a light emission surface of a tabular light guide body, and a light source is provided on a side surface. The light emission means uses a light guide body 10 equivalent to the light guide body. The light emission means 20 is provided with a uniform pattern on the light emission surface 14 of the light guide body 10. A light source 30 equivalent to the light source is provided on a light incident surface 15, and luminance emitting light from the light emission surface 14 of the light guide body 10 is measured, the pattern of the light emission means 20 is determined from the measured luminance, and the determined pattern is followed in the manufacturing method of a surface light source.

Description

  The present invention relates to a surface light source manufacturing method and a surface light source.

  Conventionally, liquid crystal display devices used in mobile phones, notebook computers, liquid crystal televisions, video cameras, etc., backlight keys for mobile phones, backlight keyboards for personal computers, display devices such as display switches for electrical equipment and vehicles, ceiling lights, etc. Light source devices used in interior lighting, lighting devices such as lighting signs, etc., are directly below, plate-shaped light guides in which a plurality of linear light sources such as fluorescent lamps and point light sources such as light emitting diodes are arranged in a housing There is an edge light system in which a linear light source or a point light source is arranged on the side of the body.

  An edge light type light source device usually uses a transparent material such as a rectangular acrylic resin plate as a light guide, and makes light from a light source disposed on the side surface incident on the light guide from the side surface (light incident surface). Incident light is emitted from the light exit surface by providing light exit means on the front surface (light exit surface) or back surface of the light guide, or by incorporating light diffusing particles in the light guide.

For example, Patent Document 1 proposes an edge light type surface light source in which a pattern is provided on the surface of a single-layer resin plate.
Patent Document 2 proposes an edge light type surface light source in which a pattern is provided on the surface of a resin laminate having a core-clad structure.

JP-A-5-196936 International Publication No. 2010/073726

  However, although the surface light sources described in Patent Document 1 and Patent Document 2 are improved in luminance, the improvement effect is not always sufficient. In particular, the optimization of the luminance for each location of the light emitting surface is not sufficient, and it is difficult to obtain a surface light source having a desired luminance.

  Accordingly, an object of the present invention is to provide a surface light source manufacturing method and a surface light source capable of obtaining a surface light source having desired luminance.

The present invention has the following aspects.
[1] A method of manufacturing a surface light source in which light emitting means is provided on a light emitting surface of a plate-like light guide, and a light source is provided on a side surface, wherein the light emitting means is a light guide equivalent to the light guide. The light emitting means is provided in a uniform pattern on the light emitting surface of the light guide, the light source equivalent to the light source is provided on the side surface, and the luminance emitted from the light emitting surface of the light guide is measured and measured. A method for manufacturing a surface light source, wherein a pattern of light emitting means is determined from luminance and the determined pattern is followed.
[2] The light emitting means is an aggregate of concave portions or convex portions, calculates a light emission rate P from the measured luminance, and calculates the light output rate P and the concave portions or convex portions per unit area of the light emitting surface. and the surface area S of the part, and a light emission ratio P _L for emitting the desired luminance, to determine a pattern of light emitting means, a method of manufacturing the surface light source according to [1].
[3] The method for manufacturing a surface light source according to [1] or [2], including the following steps A to G.
Step A: The light emitting means, which is an assembly of concave or convex portions, is provided in a uniform pattern on the light emitting surface of the plate-shaped light guide, the light source is provided on the side surface of the light guide, and the light emitting surface of the light guide Are measured at a plurality of positions at different distances L from the light source.
Step B: Of each luminance measured in Step A, the ratio of each luminance to the maximum value is calculated as a luminance ratio, and the light emission rate P is calculated from the logarithmic slope I of the luminance ratio with respect to the distance L from the light source. .
Process C: The said process A and the process B are performed about the light guide from which the surface area S of the recessed part or convex part which comprises a light-projection means differs.
Step D: calculate the surface area S of the concave portions or convex portions per unit area of the light emission surface is the surface area ratio S _P, to create a correlation function F of the light emitting rate P and the surface area ratio S _P.
Step E: dividing the entire amount of light emitted from the light source to the light guide determines the brightness desired to be emitted for each distance L from the light source, each distance L of light emitting rate P _L for emitting the luminance from the light source To calculate.
Step F: To determine the pattern of the correlation function F and the light emitting rate P _L, the light emitting means necessary to exit at a distance L from the light source.
Step G: Prepare a light guide equivalent to the light guide before the light emitting means used for measuring the luminance in Step A, and at each distance L from the side to the light exit surface of the light guide A light emitting means is provided according to the pattern determined in step F, and a light source equivalent to the light source used in step A is provided on the side surface of the light guide.

[4] A surface light source obtained by the method for manufacturing a surface light source according to any one of [1] to [3].
[5] A surface light source having a light source on the side surface of the light guide and emitting light from the light exit surface of the light guide, wherein the uniformity of the surface light source is 50% or more.
[6] The surface light source according to [5], wherein the amount of light emitted from the light exit surface of the light guide is 90% or more with respect to 100% of the total amount of light emitted from the light source.

According to the method for manufacturing a surface light source of the present invention, a surface light source having a desired luminance can be obtained.
The surface light source of the present invention has a desired luminance.

It is a figure which shows typically an example of the surface light source which provided the light source and the light emission means in the light guide in the process A, (a) is a top view, (b) is sectional drawing. It is a figure which shows typically the light guide used in Example 1, (a) is a top view, (b) is sectional drawing. It is a figure which shows typically the surface light source A obtained in Example 1, (a) is a top view, (b) is sectional drawing. 6 is a graph showing the luminance of the surface light source A, the surface light source B, and the surface light source C obtained in Example 1. 4 is a graph showing the logarithm of the luminance ratio of the surface light source A, the surface light source B, and the surface light source C obtained in Example 1. 4 is a graph showing a correlation function F of the surface light source A, the surface light source B, and the surface light source C obtained in Example 1. 3 is a plan view schematically showing how to provide light emitting means for obtaining a surface light source X in Example 1. FIG. 3 is a graph showing the luminance of the surface light source A, surface light source B, surface light source C, and surface light source X obtained in Example 1. It is a figure which shows typically the surface light source D obtained in Example 2, (a) is a top view, (b) is sectional drawing. It is a graph which shows the brightness | luminance of the surface light source D obtained in Example 2, the surface light source E, and the surface light source F. FIG. It is a graph which shows the logarithm of the luminance ratio of the surface light source D obtained in Example 2, the surface light source E, and the surface light source F. It is a graph which shows the correlation function F of the surface light source D obtained in Example 2, the surface light source E, and the surface light source F. It is a graph which shows the brightness | luminance of the surface light source D obtained in Example 2, the surface light source E, the surface light source F, and the surface light source Y. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments and drawings.
In this specification, “equivalent”, “same”, “uniform”, “constant”, etc. are described, but strictly “equivalent”, strictly “same”, strictly “uniform”, strictly “constant” It does not have to be "" and has a range that does not depart from the gist of the present invention.
2, 3, 7, and 9, the same components as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.
In addition, FIGS. 1 to 3, 7, and 9 may show the characteristic parts in an enlarged manner for the sake of convenience in order to make the characteristics easy to understand. May be different.

The present invention is a method of manufacturing a surface light source in which a light emitting means is provided on a light emitting surface of a plate-like light guide and a light source is provided on a side surface. The light emitting means uses a light guide equivalent to the light guide, the light emitting means is provided in a uniform pattern on the light emitting surface of the light guide, and the light source equivalent to the light source is provided on the side surface for guiding. The luminance emitted from the light emitting surface of the light body is measured, the pattern of the light emitting means is determined from the measured luminance, and the determined pattern is followed.
Here, determining the pattern of the light emitting means means determining the light emitting means to be an optimum pattern according to the use of the surface light source.

When the light emitting means is an aggregate of concave or convex portions, the pattern of the light emitting means, for example, calculates the light emission rate P from the measured luminance, and calculates the calculated light emission rate P and the unit area of the light emission surface. and the surface area S of the concave portions or convex portions per, is determined from the light emitting rate P _L for emitting the desired luminance. Specifically, since the pattern of the light emitting means is determined through the following steps A to F, the method for manufacturing a surface light source of the present invention preferably includes the following steps A to G.
Step A: The light emitting means, which is an assembly of concave or convex portions, is provided in a uniform pattern on the light emitting surface of the plate-shaped light guide, the light source is provided on the side surface of the light guide, and the light emitting surface of the light guide Are measured at a plurality of positions at different distances L from the light source.
Step B: Of each luminance measured in Step A, the ratio of each luminance to the maximum value is calculated as a luminance ratio, and the light emission rate P is calculated from the logarithmic slope I of the luminance ratio with respect to the distance L from the light source. .
Process C: The said process A and the process B are performed about the light guide from which the surface area S of the recessed part or convex part which comprises a light-projection means differs.
Step D: calculate the surface area S of the concave portions or convex portions per unit area of the light emission surface is the surface area ratio S _P, to create a correlation function F of the light emitting rate P and the surface area ratio S _P.
Step E: dividing the entire amount of light emitted from the light source to the light guide determines the brightness desired to be emitted for each distance L from the light source, each distance L of light emitting rate P _L for emitting the luminance from the light source To calculate.
Step F: To determine the pattern of the correlation function F and the light emitting rate P _L, the light emitting means necessary to exit at a distance L from the light source.
Step G: Prepare a light guide equivalent to the light guide before the light emitting means used for measuring the luminance in Step A, and at each distance L from the side to the light exit surface of the light guide A light emitting means is provided according to the pattern determined in step F, and a light source equivalent to the light source used in step A is provided on the side surface of the light guide.
Note that the light guide used for measuring the luminance in the process A and before the light emitting means is provided is also referred to as a “first light guide”, and according to the pattern determined in the process F in the process G. The light guide before the light emitting means is provided is also referred to as a “second light guide”.

(Process A)
In step A, the light emitting means, which is an assembly of concave portions or convex portions, is provided in a uniform pattern on the light emitting surface of the plate-shaped light guide (first light guide), and the light guide (first guide) is provided. In this step, a light source is provided on the side surface of the light body, and the luminance emitted from the light exit surface of the light guide (first light guide) is measured at a plurality of positions at different distances L from the light source.
For example, as shown in FIG. 1, the light emitting means 20 is uniformly provided on the light emitting surface 14 of the light guide (first light guide) 10, and the side surface of the light guide (first light guide) 10. A surface light source 1 is manufactured by providing a light source 30. The surface light source 1 shown in FIG. 1 has light emitting means 20 uniformly provided on the surface that becomes the light emitting surface 14 and the light source 30 provided on the side surface that becomes the light incident surface 15.

The light guide is not particularly limited as long as it guides light, and examples thereof include a single-layer light guide and a laminate having a core-clad structure.
A light guide (first light guide) 10 shown in FIG. 1 is a laminated body having a core-clad structure.

  The material of the single-layer light guide is not particularly limited as long as it has a high light transmittance. Examples thereof include acrylic resin, polycarbonate resin, alicyclic polyolefin resin, polyester resin, vinyl chloride resin, and glass. . Among these single-layer light guide materials, acrylic resins, polycarbonate resins, and alicyclic polyolefin resins are preferable, and acrylic resins and polycarbonate resins are more preferable because they are lightweight, excellent in transparency, and handleability.

  The thickness of the single-layer light guide is preferably 0.1 mm to 15 mm, and more preferably 0.2 mm to 10 mm. When the thickness of the single-layer light guide is 0.1 mm or more, the mechanical properties are excellent. Further, when the thickness of the single-layer light guide is 15 mm or less, the handleability is excellent.

A laminated body having a core-clad structure is, for example, a laminated body having clad layers 12 on both surfaces of a core layer 11 as shown in FIG.
The material of the core layer 11 and the clad layer 12 is not particularly limited as long as the refractive index is different and the light transmittance is high.
The difference in refractive index between the core layer 11 and the clad layer 12 is preferably 0.001 or more because incident light can propagate far away with little loss while totally reflecting the interface between the core layer 11 and the clad layer 12. 01 or more is more preferable.

The refractive index of the core layer 11 and the cladding layer 12 may be higher or lower, and can be appropriately selected according to the purpose of use.
When the refractive index of the core layer 11 is higher than the refractive index of the cladding layer 12, it is preferable because the core layer 11 can propagate far away with a small loss.
When the refractive index of the cladding layer 12 is lower than the refractive index of the core layer 11, it is preferable because the luminance of the surface light source is excellent with a small number of light emitting means.

  The material of the core layer 11 is not particularly limited as long as it has a high light transmittance, and examples thereof include acrylic resin, polycarbonate resin, alicyclic polyolefin resin, polyester resin, vinyl chloride resin, and glass. Among these materials for the core layer 11, acrylic resin, polycarbonate resin, alicyclic polyolefin resin, and glass are preferable, and acrylic resin, polycarbonate resin, and glass are more preferable because of being lightweight and excellent in transparency and handling.

  The thickness of the laminate having a core-clad structure is preferably 0.1 mm to 15 mm, and more preferably 0.2 mm to 10 mm. When the thickness of the laminate having the core-cladding structure is 0.1 mm or more, the mechanical properties are excellent. Further, when the thickness of the laminate having a core-cladding structure is 15 mm or less, the handleability is excellent.

The material of the clad layer 12 is not particularly limited as long as it has a high light transmittance and is different from the refractive index of the core layer 11, and can be appropriately selected according to the purpose of use.
When the refractive index of the core layer 11 is higher than the refractive index of the cladding layer 12 and an acrylic resin is used as the material of the core layer 11, examples of the material of the cladding layer 12 include a fluorine-containing olefin resin.
When the refractive index of the core layer 11 is higher than the refractive index of the cladding layer 12 and polycarbonate resin is used as the material of the core layer 11, examples of the material of the cladding layer 12 include fluorine-containing olefin resin and acrylic resin.
When the refractive index of the cladding layer 12 is higher than the refractive index of the core layer 11 and acrylic resin is used as the material of the core layer 11, examples of the material of the cladding layer 12 include glass.

  The thickness of the cladding layer 12 is preferably 1 μm to 500 μm, and more preferably 2 μm to 200 μm. When the thickness of the cladding layer 12 is 1 μm or more, light leakage of the laminate having the core-cladding structure can be suppressed. Further, when the thickness of the clad layer 12 is 500 μm or less, the productivity of a laminate having a core-clad structure is excellent.

The shape of the light guide is not particularly limited as long as it is a plate shape, and examples thereof include a polygonal shape such as a rectangle and a triangle; and a circular shape such as a perfect circle and an ellipse. Among these light guides, a polygonal shape is preferable and a rectangular shape is more preferable because light from a light source is easily incident and the processability is excellent.
The light guide may have light diffusing particles or bubbles as necessary.
Examples of the material for the light diffusing particles include a silicone resin, an acrylic resin, and a styrene resin. These light diffusion particles may be used alone or in combination of two or more.

The light guide may have a functional layer on the front surface (light output surface 14) or the back surface (surface opposite to the light output surface 14) as necessary.
As a functional layer, well-known functional layers, such as the light reflection layer 13, a design layer, a light-diffusion layer, etc. are mentioned, for example.
When the light reflecting layer 13 is provided on the light guide, as shown in FIG. 1, the light reflecting layer 13 is provided on the back surface of the light guide to reflect the light leaking from the clad layer 12 and enter the core layer 11 again. Can be made.

  Examples of the light reflecting layer 13 include a resin layer obtained by coating a resin that reflects visible light with a resin ink such as vinyl, polyester, acrylic, urethane, or epoxy; polyolefin resin, polyester resin, acrylic resin, or the like A resin plate or a resin film; paper such as cellulose; a metal plate such as aluminum, nickel, gold, platinum, chromium, iron, copper, indium, tin, silver, titanium, lead, zinc, or a metal thin film. Among these light reflecting layers 13, a resin layer obtained by coating a resin that reflects visible light with a resin ink is preferable because the reflectance can be easily adjusted.

The light reflecting layer 13 may have a pigment, light diffusing particles, or bubbles as necessary.
Examples of the pigment include white pigments such as titanium oxide, barium sulfate, calcium carbonate, and magnesium carbonate. These pigments may be used alone or in combination of two or more. Among these pigments, a white pigment is preferable because of its high reflectance with respect to the entire visible light region.
Examples of the material for the light diffusing particles include a silicone resin, an acrylic resin, and a styrene resin. These light diffusion particles may be used alone or in combination of two or more.

  The thickness of the light reflection layer 13 may be appropriately selected according to the reflectance of the light reflection layer 13 and the use of the light guide, but it is excellent in durability of the light guide and serves also as a protective film for the light guide. 10 μm to 500 μm are preferable, and 50 μm to 200 μm are more preferable.

  In step A, the light emitting means, which is an assembly of concave portions or convex portions, is provided in a uniform pattern on the light emitting surface of the light guide (first light guide). Here, providing the light emitting means in a uniform pattern means forming a plurality of concave portions or convex portions having the same shape on the light emitting surface at equal intervals.

As the light emitting means, an assembly of recesses 21 as shown in FIG. 1 is preferable because it is easy to design. The recess 21 preferably penetrates the cladding layer 12 on the light emitting surface 14 side and reaches the core layer 11.
Examples of the shape of the concave portion 21 include a conical shape, an elliptical cone shape, a pyramid shape, a spherical shape, and a line shape.

The surface area S of the concave portion or convex portion is not particularly limited as long as the surface area of each concave portion or convex portion constituting the light emitting means is the same, but is preferably selected from the range of 10 μm ^{2 to} 100 mm ² .

The depth of the concave portion or the height of the convex portion is not particularly limited as long as the depth of each concave portion or the height of the convex portion constituting the light emitting means is the same, but it is selected from the range of 0.1 μm to 1 mm. Is preferred. In the case where the light guide has a core-cladding structure as shown in FIG. 1, the depth of the recess 21 is preferably larger than the thickness of the cladding layer 12.
Here, the depth of the concave portion is a vertical distance from the opening portion of the arbitrary concave portion to the deepest portion, and the height of the convex portion is a vertical distance from the top portion to the bottom portion of the arbitrary convex portion. .

The pitch of the concave portions or the convex portions is not particularly limited as long as the pitch of the concave portions or the convex portions constituting the light emitting means is the same, but is preferably selected from the range of 1 μm to 10 mm.
Here, the pitch of a recessed part or a convex part is the distance from the center part of arbitrary recessed parts or a convex part to the central part of the recessed part or convex part adjacent to this.

  Examples of the method of providing the light emitting means include laser processing, sand blast processing, press processing, hot press processing, printing processing, etching processing, and electric discharge processing. Among these methods of providing the light emitting means, laser processing and printing processing are preferable, and laser processing is more preferable because of easy control and simple method.

Examples of the light source include a light source in which a plurality of point light sources such as LEDs are arranged, a linear light source, and the like.
When the light source is a light source in which a plurality of point light sources are arranged, it is preferable to provide the point light sources uniformly over the entire region in the width (w) direction of the light guide.
When the light source is a linear light source, it is preferable that the length of the light source and the length of the light guide in the width direction are uniform.
The light source may be provided on one side surface or on two opposing side surfaces. The side surface on which the light source is provided is called a light incident surface.

  The luminance emitted from the light exit surface of the light guide is measured with a luminance meter, a spectroradiometer, or the like at a plurality of positions at different distances L from the light source in the length (l) direction of the light guide.

(Process B)
In step B, the ratio of each luminance to the maximum value among the luminances measured in step A is calculated as the luminance ratio, and the light emission rate P is calculated from the logarithmic slope I of the luminance ratio with respect to the distance L from the light source. It is a process to do.
Step B is performed after step A.

Step B will be specifically described.
First, for each luminance measured in step A, it is converted into a luminance ratio with the maximum value of luminance being 1, and the logarithm is further taken.
Next, a two-dimensional graph is created with the distance L (mm) from the light source as the x-axis and the logarithm of the obtained luminance ratio as the y-axis.
Next, a range L1 (mm) to L2 (mm) of a distance L (mm) from the light source where the inclination is constant is determined from the obtained two-dimensional graph.
Next, the slope I (mm ⁻¹ ) of the logarithm I _{L1 to} I _L2 of the luminance ratio in the determined range L1 (mm) to L2 (mm) is calculated by the following mathematical formula (1).
Next, the light emission rate P (%) is calculated by the following mathematical formula (2). Ls (mm) represents a certain distance, and the light output rate P (%) is the light output rate per Ls (mm).
I = (I _L2 −I _L1 ) / (L2−L1) (1)
P = (1-10 ^{I · Ls} ) × 100 (2)

  The method of determining the range L1 (mm) to L2 (mm) of the distance L (mm) from the light source where the inclination is constant may be set as appropriate by checking the obtained two-dimensional graph. The ranges L1 to L2 are preferably selected from a range of 20% to 60% with respect to a range in which light is desired to be emitted (distance in the length direction of the light guide).

  Ls may be set as appropriate, but is preferably 1 mm to 100 mm, and more preferably 2 mm to 50 mm. Design is easy when Ls is 1 mm or more. Moreover, it is excellent in the uniformity of a surface light source as Ls is 100 mm or less.

(Process C)
Step C is a step of performing Step A and Step B for light guides having different surface areas S of concave portions or convex portions constituting the light emitting means.
Step C is performed after step B.
Step C may be performed at least once, but is preferably performed twice or more in order to increase the uniformity of the surface light source. Specifically, as the first light guide, one or more light guides having different surface areas S of the concave or convex portions constituting the light emitting means from the light guide used in the previous step A, preferably Prepare two or more, and perform step A and step B on these.

(Process D)
Step D is the calculated surface area S of the concave portions or convex portions per unit area of the light emission surface is the surface area ratio S _P, to create a correlation function F of the light emitting rate P and the surface area ratio S _P step is there.
The process D is performed after the process C.

Surface area ratio S _P output recesses or protrusions constituting the light emitting means is representative of the surface area of the recesses or protrusions per unit area of the light emitting surface S (mm ^2).
The surface area S (mm ² ) of the concave portion or convex portion per unit area of the light emitting surface is calculated from the surface area S (mm ² ) of the concave portion or convex portion per piece and the pitch (mm) of the concave portion or convex portion. be able to. For example, the unit area of the light exit surface is 1 mm ² , the pitch p _x (mm) of the recesses or projections in the length (l) direction of the light guide, and the recesses or projections in the width (w) direction of the light guide If the pitch _{p y} parts are 1mm together, the surface area S ^(mm 2) of the recesses or protrusions per one = the surface area ratio _{S P.}

Correlation function F, the light emitting ratio P calculated in Step B (%) in x-axis, the surface area ratio S _P output recesses or protrusions constituting the light emitting unit plots for the y-axis, minimizing the points plotted two A linear function approximated by multiplication (y = ax + b).

(Process E)
Step E divides the total amount of light incident on the light guide from the light source, determines the luminance to be emitted for each distance L from the light source, and determines the light emission rate P _L for emitting the luminance as the distance L from the light source. It is the process of calculating every.
The process E may be performed before the process A to the process D, may be performed after the process A to the process D, or may be performed between the process A to the process D.

By dividing the total amount of light incident on the light guide from the light source, the luminance utilization rate can be increased. The luminance utilization rate is the amount of light (%) emitted from the light exit surface of the light guide with respect to 100% of the total amount of light emitted from the light source.
The purpose of step E is to calculate a light emission rate P _L (ratio) for emitting a desired luminance for each distance L from the light source with respect to the total amount of light incident on the light guide from the light source. The total amount of light incident on the light guide from the light source may be a value of the total amount of light actually incident or a provisional numerical value.

The brightness desired to be emitted for each distance L from the light source may be uniform or high and low, and may be set as appropriate according to the use of the surface light source.
For example, when it is desired to obtain a surface light source having a high degree of uniformity, it is preferable to uniformly distribute the luminance desired to be emitted at every distance L from the light source.

The light emission rate P _L (%) for emitting the luminance to be emitted is calculated by dividing the luminance to be emitted by the total light amount emitted from the light source and multiplying by 100.

(Process F)
Step F is a step of determining the pattern of the correlation function F and the light emitting rate P _L, the light emitting means necessary to exit at a distance L from the light source.
Process F is performed after Process D and Process E.

By substituting the light emission rate P _L (%) obtained in step E for x of the correlation function F (y = ax + b) obtained in step D, the light emission means required for emission at the distance L from the light source The surface area ratio S _P (y of the correlation function F) can be calculated. Based on the surface area ratio S _P output light output means necessary to exit at a distance L from the light source, for each distance L from the light source, or to change the pitch of the light emitting means to vary the surface area of each light emitting means Thus, the pattern of the light emitting means can be determined.

Specifically, the surface area ratio S _P output light output means necessary to exit at a distance L from the light source, since they represent a surface area S (mm ²⁾ of the light emitting means per unit area, the surface area of the light output means provided S (Mm ² ), the pitch p _x (mm) in the length direction of the light guide of the provided light emitting means, and the pitch p _y (mm) in the width direction of the light guide of the provided light emitting means, ) Holds. Based on the following formula (3), the pattern of the light emitting means can be determined.
S _P = S / (p _x × p _y ) (3)

(Process G)
In step G, a light guide (second light guide) equivalent to the light guide (first light guide) used for measuring the luminance in step A before the light emitting means is prepared. The light emitting surface of the light guide (second light guide) is provided on the light output surface of the light guide (second light guide) according to the pattern determined in step F for each distance L from the side surface. In this step, a light source equivalent to the light source used in step A (that is, the light source provided in the first light guide) is provided on the side surface.

The surface light source obtained through the process A to the process G is provided with light emitting means having an optimum pattern according to the application on the light emitting surface, so that the luminance for each place of the light emitting surface is optimized, It has the desired brightness.
The surface light source obtained through the process A to the process G can increase the uniformity, specifically, the uniformity can be set to 50% or more. The uniformity is the ratio between the maximum value and the minimum value of the luminance within the range in which the surface light source is desired to be emitted.
The surface light source obtained through the process A to the process G can increase the luminance utilization rate, specifically, the luminance utilization rate can be 90% or more. The luminance utilization rate is the ratio of the amount of light emitted from the light emitting surface of the light guide to the total amount of light emitted from the light source, and the total amount of luminance in the range desired to be emitted by the surface light source is emitted from the surface light source. Calculate by dividing by the total amount of luminance and multiplying by 100.

  According to the method for manufacturing a surface light source of the present invention described above, a surface light source having a desired luminance can be obtained. Therefore, the surface light source obtained is, for example, a liquid crystal display device used for mobile phones, notebook computers, liquid crystal televisions, video cameras, etc., backlight keys for mobile phones, backlight keyboards for personal computers, display switches for electrical equipment and vehicles, etc. It can be suitably used for indoor lighting such as display devices and ceiling lights, and lighting devices such as lighting signs.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to an Example.

"Example 1"
(Manufacture of light guides)
Polycarbonate resin (trade name “Taflon LC2200”, manufactured by Idemitsu Kosan Co., Ltd., refractive index n ₁ = 1.585) as the material constituting the core layer, and acrylic resin (trade name “Acrypet VH000” as the material constituting the cladding layer , Manufactured by Mitsubishi Rayon Co., Ltd., refractive index n ₂ = 1.49), a laminate comprising a core layer and a clad layer laminated on both sides of the core layer was obtained by multilayer melt extrusion. The thickness of each clad layer was 10 μm, and the total thickness of the laminate was 0.7 mm.
The obtained laminate was cut into a rectangle having a width (w) of 210 mm and a length (l) of 605 mm, and four side surfaces were cut into mirror surfaces with a diamond tool. Next, the surface having the adhesive layer of the light reflecting layer (trade name “E241-WS”, manufactured by Sumilon Co., Ltd., white film) provided with an adhesive layer on one side is laminated on the back surface of the light emitting surface of the laminate. A light guide (first light guide) was obtained. A schematic diagram of the obtained light guide is shown in FIG.

(Process A)
Using a carbon dioxide laser processing device (model name “EMMLS-001”, manufactured by LTS) on the light exit surface of the obtained light guide, the surface area S is 0.0044 mm ² (approximately circle with a diameter of 75 μm), the recess depth is 25 [mu] m, the pitch p _y in the width direction of the pitch p _x and the light guide member in the longitudinal direction of the light guide body is provided with a light emitting means uniformly formed so that each becomes 1 mm. Then, 20 LEDs (trade name “NSSW157T”, manufactured by Nichia Corporation) were arranged as light sources on the side surface of the light guide at a pitch of 10 mm to obtain a surface light source A. A schematic view of the obtained surface light source A is shown in FIG.
The obtained surface light source A was made to emit light by applying a direct current of 18 V, 630 mA, and using a luminance meter (model name “BM-7A”, manufactured by Topcon Techno House Co., Ltd.), the distance L from the light source was 10 mm to 360 mm. With respect to the above area, the luminance in the normal direction of 36 points was measured in increments of 10 mm. The brightness of the luminance meter in the normal direction is measured by setting the luminance meter height from the surface light source A to 500 mm, the viewing angle to 2 °, and the center of the measurement circle of the luminance meter to coincide with the center of each region. Got. The luminance of the surface light source A is shown in FIGS.

(Process B)
The luminance shown in FIG. 4 was converted to a luminance ratio with the maximum value being 1, and the logarithm was further taken. Next, a two-dimensional graph was created with the distance L (mm) from the light source as the x axis and the logarithm of the obtained luminance ratio as the y axis. The results are shown in FIG.
From FIG. 5, the range L1 to L2 of the distance L from the light source where the inclination is constant was set to 200 mm to 360 mm. The slope I of the logarithm I _{L1 to} I _L2 of the luminance ratio in the range of the distance L from the light source of 200 mm to 360 mm was determined from the above formula (1), and was −0.00049 mm ⁻¹ . Ls was set to 10 mm, and the light emission rate P per 10 mm was determined from the above formula (2) and found to be 1.13%. The light emission rate P of the surface light source A is shown in Table 1.

(Process C)
A surface light source B was obtained in the same manner as the surface light source A except that the surface area S of the concave portion constituting the light emitting means was changed to 0.0250 mm ² (approximately ellipse having a major axis of 350 μm and a minor axis of 75 μm).
Separately, the surface light source C was obtained in the same manner as the surface light source A, except that the surface area S of the recesses constituting the light emitting means was 0.0550 mm ² (major ellipse having a major axis of 750 μm and a minor axis of 75 μm).
With respect to the obtained surface light source B and surface light source C, the luminance was measured in the same manner as the surface light source A, and the light emission rate P was obtained from the logarithmic slope I of the luminance ratio. The luminance of the surface light source B and the surface light source C is shown in FIGS. 4 and 8, the logarithm of the luminance ratio is shown in FIG. 5, and the light emission rate P is shown in Table 1.
The major axis is the width direction of the light guide, and the minor axis is the length direction of the light guide.

(Process D)
For the surface light source A, the surface light source B, and the surface light source C, the surface area S of the concave portion per unit area (1 mm ² ) of the light emitting surface is calculated from the surface area S and pitch of the concave portions constituting the light emitting means. was the rate _{S P.} Surface light source A, a surface light source B, and the surface area ratio S _P output surface light source C shown in Table 1.
Light emission ratio P calculated in Step B (%) in x-axis, the surface area ratio S _P output recess constituting the light output means was plotted for the y-axis. The results are shown in FIG. When the correlation function F was calculated by approximating the three plotted points by the least square method, y = 0.657x−0.00577.

(Process E)
The total amount of light incident on the light guide from the light source was temporarily set to 3000 cd / m ² , the total amount of light was equally divided, and the luminance desired to be emitted for each distance L from the light source was determined. Specifically, the total amount of light (3000 cd / m ² ) was divided into 30 equal parts, and the luminance desired to be emitted in 10 mm increments for the region where the distance L from the light source was 0 mm to 300 mm was determined to be 100 cd / m ² .
Next, a light emission rate P _L for emitting the luminance (100 cd / m ² ) desired to be emitted in each region was calculated. Specifically, the luminance to be emitted in each region was calculated by dividing the luminance by the total light amount emitted from the light source (luminance before attenuation in each region) and multiplying by 100. The calculated light emission rate P _L shown in Table 2. The luminance before attenuation in each region was obtained as follows.
In the case of this step, since the luminance to be emitted in 10 mm increments for the region where the distance L from the light source is 0 mm to 300 mm is determined to be 100 cd / m ² , the region L (region i) where the distance L from the light source is 0 mm to 10 mm. The luminance before attenuation is 3000 cd / m ² , and the luminance after attenuation is a value obtained by subtracting the luminance to be emitted from the luminance before attenuation in the region i, that is, 2900 cd / m ² . The luminance before attenuation in the region (region ii) where the distance L from the light source is 10 mm to 20 mm is the same value as the luminance after attenuation in the region i, that is, 2900 cd / m ² , and the luminance after attenuation is emitted from the luminance before attenuation in the region ii. A value obtained by subtracting the luminance to be obtained, that is, 2800 cd / m ² . Similarly, when the pre-attenuation luminance and the post-attenuation luminance are determined in increments of 10 mm in a region where the distance L from the light source is 0 mm to 300 mm, the luminance before attenuation in the region where the distance L from the light source is 290 mm to 300 mm is It was 100 cd / ^{m 2,} attenuation after the luminance is 0 cd / ^{m 2.} Table 2 shows the luminance before attenuation and luminance after attenuation in each region.

(Process F)
The x of the correlation function F (y = 0.00657x-0.00577) , by substituting the light emitting rate _{P L} calculated in step E, calculates the y of the correlation function F, which emits at a distance L from the light source and surface area ratio S _P output light emitting means necessary.
Light emitting means will be provided in step G, the surface area S is 0.0044mm ² (substantially circular in diameter 75 [mu] m), the aggregate of the recess depth of 25 [mu] m, the width direction of the light guide pitch _{p y} was a 0.1 mm, it was calculated pitch _{p x} in the longitudinal direction of the equation (3) from the light guide. The pitch p _x of the calculated longitudinal shown in Table 3.

(Process G)
A light guide body (second light guide body) equivalent to the light guide body (first light guide body) used for measuring the luminance in Step A before providing the light emitting means was prepared. Using a carbon dioxide laser processing apparatus (model name “EMMLS-001”, manufactured by LTS), the surface area S is set to be 0.00 for each distance L on the light emission surface of the prepared light guide (second light guide). 0044mm is ² (substantially circular with a diameter of 75 [mu] m), a recess depth of 25 [mu] m, 0.1 mm pitch _{p y} in the width direction of the light guide, Table 3 pitches _{p x} length direction of the light guide The light output means was provided. A schematic diagram of how to provide the light emitting means is shown in FIG.
Next, 20 LEDs (trade name “NSSW157T”, manufactured by Nichia Corporation) as light sources were arranged on the side surface of the light guide (second light guide) at a pitch of 10 mm to obtain a surface light source X. .

(Optical evaluation)
The obtained surface light source X was made to emit light by applying a direct current of 18 V, 630 mA, and using a luminance meter (model name “BM-7A”, manufactured by Topcon Technohouse Co., Ltd.), the distance L from the light source was 10 mm to 360 mm. With respect to the above area, the luminance in the normal direction of 36 points was measured in increments of 10 mm. The brightness of the luminance meter in the normal direction is measured by setting the luminance meter height from the surface light source X to 500 mm, the viewing angle to 2 °, and the luminance circle of the luminance meter to coincide with the center of each region. Got. The luminance of the surface light source X is shown in FIG.

At this time, the average value of the luminance when the distance L from the light source was 10 mm to 290 mm was defined as the luminance (cd / m ² ) of the surface light source X.
At this time, the ratio between the maximum value and the minimum value of the luminance when the distance L from the light source is 10 mm to 290 mm is calculated by the following mathematical formula (4), and the obtained value is defined as the uniformity (%) of the surface light source X. .
Further, at this time, the ratio of the total amount of luminance when the distance L from the light source is 10 mm to 290 mm and the total amount of luminance when the distance L from the light source is 10 mm to 360 mm is calculated by the following equation (5), and the obtained value is The luminance utilization factor (%) of the light source X was used.
Uniformity = {(minimum value of luminance) / (maximum value of luminance)} × 100 (4)
Luminance utilization rate = {(total amount of luminance at 10 mm to 290 mm) / (total amount of luminance at 10 mm to 360 mm)} × 100 (5)

Table 4 shows the luminance, uniformity, and luminance utilization factor of the surface light source X.
For the surface light source A, surface light source B, and surface light source C, the luminance, uniformity, and luminance utilization rate were calculated in the same manner as the surface light source X. These results are shown in Table 4.

The surface light source X obtained in Example 1 was excellent in average luminance and luminance utilization rate, and excellent in uniformity.
On the other hand, the surface light source A, the surface light source B, and the surface light source C provided with light emitting means with a uniform pitch were inferior in uniformity.

"Example 2"
(Manufacture of light guides)
Acrylic resin (trade name “Acrylite LX # 001”, manufactured by Mitsubishi Rayon Co., Ltd., refractive index n ₁ = 1.49, thickness = 3.0 mm) is used as the material of the single-layer light guide, and the width ( w) It was cut into a rectangle of 300 mm and length (l) 510 mm, and four side surfaces were cut into mirror surfaces with a diamond tool to obtain a light guide (first light guide).

(Process A)
Using a carbon dioxide laser processing device (model name “EMMLS-001”, manufactured by LTS) on the light exit surface of the obtained light guide, the surface area S is 0.0044 mm ² (approximately circle with a diameter of 75 μm), the recess depth is 60 [mu] m, the pitch p _x in the longitudinal direction of the light guide is 0.5 mm, the light emitting means uniformly formed so that the pitch p _y is 1mm in width direction of the light guide Provided. Next, a reflective sheet (trade name “E60”, manufactured by Toray Industries, Inc., with a thickness as a light reflecting layer on the surface opposite to the light emitting surface of the light guide with the dot surface (light emitting surface) of the light guide down. 188 μm). Further, 30 LEDs (trade name “NSSW157T”, manufactured by Nichia Corporation) were disposed as light sources on the side surface of the light guide at a pitch of 10 mm to obtain a surface light source D. A schematic diagram of the surface light source D obtained is shown in FIG.
The obtained surface light source D was caused to emit light by applying a current of DC 18V 630 mA, and using a spectroradiometer (model name “SR-3AR”, manufactured by Topcon Technohouse Co., Ltd.), the distance L from the light source was 10 mm to 360 mm. With respect to the above area, the luminance in the normal direction of 36 points was measured in increments of 10 mm. In addition, the height of the spectroradiometer from the surface light source D is 500 mm, the viewing angle is 2 °, the center of the spectroradiometer measurement circle is aligned with the center of each region, and the luminance of each region is measured. The brightness was obtained. The luminance of the surface light source D is shown in FIGS.

(Process B)
About the brightness | luminance shown in FIG. 10, it converted into the brightness | luminance ratio which makes the maximum value 1, and also took the logarithm. Next, a two-dimensional graph was created with the distance L (mm) from the light source as the x axis and the logarithm of the obtained luminance ratio as the y axis. The results are shown in FIG.
From FIG. 11, the range L1 to L2 of the distance L from the light source where the inclination is constant was set to 60 mm to 200 mm. When the slope I of the logarithm I _{L1 to} I _L2 of the luminance ratio in the range of the distance L from the light source of 60 mm to 200 mm was determined from the above formula (1), it was −0.01264 mm ⁻¹ . Ls was set to 10 mm, and the light emission rate P per 10 mm was determined from the above formula (2) and found to be 2.87%. Table 5 shows the light emission rate P of the surface light source D.

(Process C)
The surface light source E is operated in the same manner as the surface light source D except that the surface area S of the concave portion constituting the light emitting means is 0.0250 mm ² (approximately ellipse having a major axis of 350 μm and a minor axis of 75 μm) and the depth is 60 μm. Obtained.
Separately, the surface light source D is operated in the same manner as the surface light source D except that the surface area S of the concave portion constituting the light emitting means is 0.0550 mm ² (major ellipse having a major axis of 750 μm and a minor axis of 75 μm) and the depth is 60 μm. F was obtained.
With respect to the obtained surface light source E and surface light source F, the luminance was measured in the same manner as the surface light source D, and the light emission rate P was obtained from the logarithmic slope I of the luminance ratio. The luminance of the surface light source E and the surface light source F is shown in FIGS. 10 and 13, the logarithm of the luminance ratio is shown in FIG. 11, and the light emission rate P is shown in Table 5.
The major axis is the width direction of the light guide, and the minor axis is the length direction of the light guide.

(Process D)
For the surface light source D, the surface light source E, and the surface light source F, the surface area S of the concave portion per unit area (1 mm ² ) of the light emitting surface is calculated from the surface area S and pitch of the concave portions constituting the light emitting means. was the rate _{S P.} Surface light source D, a surface light source E, the surface area ratio S _P output surface light source F are shown in Table 5.
Light emission ratio P calculated in Step B (%) in x-axis, the surface area ratio S _P output recess constituting the light output means was plotted for the y-axis. The results are shown in FIG. When the correlation function F was calculated by approximating the three plotted points by the least square method, y = 0.00860x−0.01932.

(Process E)
The total amount of light incident on the light guide from the light source was temporarily set to 3000 cd / m ² , the total amount of light was equally divided, and the luminance desired to be emitted for each distance L from the light source was determined. Specifically, the total amount of light (3000 cd / m ² ) was divided into 30 equal parts, and the luminance desired to be emitted in 10 mm increments for the region where the distance L from the light source was 0 mm to 300 mm was determined to be 100 cd / m ² .
Next, a light emission rate P _L for emitting the luminance (100 cd / m ² ) desired to be emitted in each region was calculated. Specifically, the luminance to be emitted in each region was calculated by dividing the luminance by the total light amount emitted from the light source (luminance before attenuation in each region) and multiplying by 100. The calculated light emission rate P _L shown in Table 6. The luminance before attenuation in each region was determined in the same manner as in Example 1. Table 6 shows the luminance before attenuation and luminance after attenuation in each region.

(Process F)
The x of the correlation function F (y = 0.00860x-0.01932) , by substituting the light emitting rate _{P L} calculated in step E, calculates the y of the correlation function F, which emits at a distance L from the light source and surface area ratio S _P output light emitting means necessary.
Light emitting means will be provided in step G, the surface area S is 0.0250mm ² (approximately circular diameter 350 .mu.m), the aggregate of the recess depth of 60 [mu] m, the width direction of the light guide pitch _{p y} It was a 1 mm, were calculated pitch p _x in the longitudinal direction of the equation (3) from the light guide. The pitch p _x of the calculated longitudinal shown in Table 7.

(Process G)
A light guide body (second light guide body) equivalent to the light guide body (first light guide body) used for measuring the luminance in Step A before providing the light emitting means was prepared. Using a carbon dioxide laser processing apparatus (model name “EMMLS-001”, manufactured by LTS), the surface area S is set to be 0.00 for each distance L on the light emission surface of the prepared light guide (second light guide). 0250mm ² (be approximately circular with a diameter of 350 .mu.m), the recess depth is 60 [mu] m, 1.0 mm pitch _{p y} in the width direction of the light guide, table pitches _{p x} in the longitudinal direction of the light guide body 7 The light output means was provided. A schematic diagram of how to provide the light emitting means is shown in FIG.
Next, 30 LEDs (trade name “NSSW157T”, manufactured by Nichia Corporation) were disposed as light sources on the side surface of the light guide (second light guide) at a pitch of 10 mm to obtain a surface light source Y. .

(Optical evaluation)
The obtained surface light source Y was caused to emit light by applying a direct current of 18 V, 630 mA, and using a spectroradiometer (model name “SR-3AR”, manufactured by Topcon Technohouse Co., Ltd.), the distance L from the light source was 10 mm to For a 360 mm region, the luminance in the normal direction of 36 points was measured in increments of 10 mm. The height of the spectroradiometer from the surface light source Y is 500 mm, the viewing angle is 2 °, the center of the spectroradiometer measurement circle is aligned with the center of each region, and the brightness of each region is measured. The brightness was obtained. The luminance of the surface light source Y is shown in FIG.

At this time, the average value of the luminance when the distance L from the light source was 10 mm to 290 mm was defined as the luminance (cd / m ² ) of the surface light source Y.
At this time, the ratio between the maximum value and the minimum value of the luminance when the distance L from the light source is 10 mm to 290 mm is calculated by the above formula (4), and the obtained value is defined as the uniformity (%) of the surface light source Y. .
Further, at this time, the ratio of the total amount of luminance when the distance L from the light source is 10 mm to 290 mm and the total amount of luminance when the distance L from the light source is 10 mm to 360 mm is calculated by the above equation (5), and the obtained value The luminance utilization factor (%) of the light source Y was used.

Table 8 shows the luminance, uniformity, and luminance utilization factor of the surface light source Y.
For the surface light source D, the surface light source E, and the surface light source F, the luminance, the uniformity, and the luminance utilization rate were calculated in the same manner as the surface light source Y. These results are shown in Table 8.

The surface light source Y obtained in Example 2 was excellent in average luminance and luminance utilization rate and in uniformity.
On the other hand, the surface light source D, the surface light source E, and the surface light source F provided with light emitting means with a uniform pitch were inferior in uniformity.

  According to the method for manufacturing a surface light source of the present invention, a surface light source having a desired luminance can be obtained. Therefore, the surface light source obtained is, for example, a liquid crystal display device used for mobile phones, notebook computers, liquid crystal televisions, video cameras, etc., backlight keys for mobile phones, backlight keyboards for personal computers, display switches for electrical equipment and vehicles, etc. It can be suitably used for indoor lighting such as display devices and ceiling lights, and lighting devices such as lighting signs.

DESCRIPTION OF SYMBOLS 1 Surface light source 10 Light guide 11 Core layer 12 Cladding layer 13 Light reflection layer 14 Light emission surface 15 Light incident surface 20 Light emission means 21 Recess 30 Light source l Length of light guide w Width of light guide

Claims (6)

A method of manufacturing a surface light source in which a light emitting means is provided on a light emitting surface of a plate-like light guide and a light source is provided on a side surface,
The light emitting means uses a light guide equivalent to the light guide, the light emitting means is provided in a uniform pattern on the light emitting surface of the light guide, and the light source equivalent to the light source is provided on the side surface for guiding. A method of manufacturing a surface light source, comprising: measuring a luminance emitted from a light emitting surface of a light body; determining a pattern of light emitting means from the measured luminance; and following the determined pattern. The light emitting means is an assembly of concave or convex portions;
The light output rate P is calculated from the measured luminance, the calculated light output rate P, the surface area S of the concave or convex portion per unit area of the light output surface, and the light output rate P for emitting a desired luminance. _The method of manufacturing a surface light source according to claim 1, wherein a pattern of the light emitting means is determined from _L. The manufacturing method of the surface light source of Claim 1 or 2 including the following processes A-G.
Step A: The light emitting means, which is an assembly of concave or convex portions, is provided in a uniform pattern on the light emitting surface of the plate-shaped light guide, the light source is provided on the side surface of the light guide, and the light emitting surface of the light guide Are measured at a plurality of positions at different distances L from the light source.
Step B: Of each luminance measured in Step A, the ratio of each luminance to the maximum value is calculated as a luminance ratio, and the light emission rate P is calculated from the logarithmic slope I of the luminance ratio with respect to the distance L from the light source. .
Process C: The said process A and the process B are performed about the light guide from which the surface area S of the recessed part or convex part which comprises a light-projection means differs.
Step D: calculate the surface area S of the concave portions or convex portions per unit area of the light emission surface is the surface area ratio S _P, to create a correlation function F of the light emitting rate P and the surface area ratio S _P.
Step E: dividing the entire amount of light emitted from the light source to the light guide determines the brightness desired to be emitted for each distance L from the light source, each distance L of light emitting rate P _L for emitting the luminance from the light source To calculate.
Step F: To determine the pattern of the correlation function F and the light emitting rate P _L, the light emitting means necessary to exit at a distance L from the light source.
Step G: Prepare a light guide equivalent to the light guide before the light emitting means used for measuring the luminance in Step A, and at each distance L from the side to the light exit surface of the light guide A light emitting means is provided according to the pattern determined in step F, and a light source equivalent to the light source used in step A is provided on the side surface of the light guide.   The surface light source obtained by the manufacturing method of the surface light source as described in any one of Claims 1-3. A surface light source having a light source on the side surface of the light guide and emitting light from the light exit surface of the light guide,
A surface light source in which the uniformity of the surface light source is 50% or more.   The surface light source according to claim 5, wherein the amount of light emitted from the light emitting surface of the light guide is 90% or more with respect to 100% of the total amount of light emitted from the light source.

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