WO2012033206A1 - Planar light-emitting device and illumination module - Google Patents

Abstract

A planar light-emitting device is provided with a light source and a sheet-shaped light guide body which guides, in the surface direction, light that is introduced from the light source. A light extraction section is formed in the light guide body and scatters the light introduced from the light source such that the light is emitted from a surface side. The light extraction section comprises a plurality of dot-shaped ink layers formed by printing. The dot-shaped ink layers have an external diameter from 10 to 100 μm, a thickness from 0.5 to 10 μm, and contain at least 5 mass% of titanium oxide.

Description

Planar light emitting device and lighting module

The present invention relates to a planar light emitting device and an illumination module used for a mobile phone, a liquid crystal television, an in-vehicle room lamp, and the like.
This application claims priority on September 10, 2010 based on Japanese Patent Application No. 2010-203762 for which it applied to Japan, and uses the content here.

FIG. 37 shows an example of a planar light emitting device, and the planar light emitting device 201 includes a light source 202 and a sheet-like light guide 203. The light guide 203 is formed with a plurality of concave portions 204 as light extraction portions (see Patent Document 1).
However, the planar light emitting device 201 is not suitable for thinning because the formation of the recess 204 becomes difficult when the light guide 203 becomes thin.
FIG. 38 shows another example of the planar light emitting device. The planar light emitting device 211 includes a light source 212 and a sheet-like light guide 213. On the light guide 213, an irregular reflection pattern 214 as a light extraction portion is formed by printing (see Patent Document 2).
Since the irregular reflection pattern 214 includes a plurality of circular irregular reflection points 214 a having a diameter that increases with the distance from the light source 212, a light extraction amount can be secured even at a position far from the light source 212.

Utility Model Registration No. 2581308 Japanese Patent Laid-Open No. 5-134251

However, in the planar light-emitting device 211, if the irregular reflection point 214a has a large diameter, it is visually recognized as a local light-emitting point, causing unevenness in light emission, which causes a problem in terms of characteristics as a light-emitting device.
If a diffuser plate is used, light emission can be made uniform. In this case, since the light passes through the diffuser plate, the overall luminance level is lowered. In addition, it is difficult to reduce the thickness of the apparatus.
The present invention has been made in view of the above circumstances, and it is possible to achieve uniform light emission, increase the overall luminance, and achieve a reduction in thickness. The purpose is to provide.

The planar light-emitting device of the present invention includes a light source and a sheet-like light guide that is guided in a surface direction by introducing light from the light source, and the light source is provided on one surface of the light guide. A light extraction portion that scatters and emits light introduced from the light, and the light extraction portion includes a plurality of dot-like ink layers formed by printing, and the dot-like ink layer has an outer diameter of 10 to 100 μm. The thickness is 0.5 to 10 μm and contains 5% by mass or more of titanium oxide.
The titanium oxide is preferably a rutile type.
The plurality of dot-like ink layers are preferably arranged so that their centers are located at lattice points of an equilateral triangular lattice.
The plurality of dot-like ink layers are preferably arranged so that their centers are located at lattice points of a square lattice.
The illumination module of the present invention preferably includes the planar light emitting device and a touch pad.
A reflector that reflects light leakage from the light guide can be provided between the light guide and the touch pad.

According to the present invention, since the outer diameter of the dot-like ink layer constituting the light extraction portion is 10 to 100 μm, it is possible to prevent each dot-like ink layer from being visually recognized as a local light emitting point. For this reason, it is possible to prevent the occurrence of uneven light emission and improve the light emission characteristics.
Since uneven light emission does not occur, a diffuser plate is not necessary, so that the overall luminance level can be increased and the apparatus can be made thinner.
In addition, since the thickness of the dot-like ink layer is 0.5 to 10 μm, absorption by the ink layer can be suppressed, and sufficient scattered light can be obtained, which is advantageous in terms of increasing the brightness. Further, the durability of the dot ink layer can be increased.
In the present invention, the use of titanium oxide of 5% by mass or more can increase the light emission efficiency and further increase the luminance.

It is a figure which shows schematic structure of the illumination module of 1st Embodiment of this invention. It is a partial cross section figure which shows the principal part of the light source and light guide of the illumination module of a front figure. It is a figure which shows schematic structure of the illumination module of 2nd Embodiment of this invention. It is a schematic block diagram which shows an example of a resistive film type input sensor. It is a schematic block diagram which shows an example of a pressure-sensitive type membrane switch. It is sectional drawing which shows the principal part of the light guide which provided the protective layer. It is a graph which shows a test result. It is a graph which shows a test result. It is a graph which shows a test result. It is a graph which shows a test result. It is a schematic diagram which shows the planar light-emitting device of a previous figure. It is a top view which shows typically the example of arrangement | positioning of the micro dot which comprises a light extraction part. It is a top view which shows typically the other example of arrangement | positioning of the micro dot which comprises a light extraction part. It is a top view which shows typically the example of distribution of the micro dot which comprises a light extraction part. It is a side view which shows typically the 1st example of the micro dot which comprises a light extraction part. It is a side view which shows typically the 2nd example of the micro dot which comprises a light extraction part. It is a side view which shows typically the 3rd example of the micro dot which comprises a light extraction part. It is a graph which shows the test result about the influence which the density | concentration of the titanium oxide of the ink which comprises a light extraction part has on a brightness | luminance. It is a graph which shows the test result about the influence which the kind of titanium oxide of the ink which comprises a light extraction part has on a brightness | luminance. It is a figure which shows schematic structure of the illumination module using the example of the planar light-emitting device of this invention. It is sectional drawing which shows the principal part of the planar light-emitting device of a previous figure. It is sectional drawing which shows the touchpad of the illumination module of FIG. It is a figure which shows schematic structure of an example of the planar light-emitting device which does not provide the low refractive index layer. It is a figure explaining the behavior of the light in the planar light-emitting device shown to a previous figure. It is a top view which shows a simulation result. It is a figure which shows schematic structure of an example of the planar light-emitting device which provided the low refractive index layer. It is a figure explaining the behavior of the light in the planar light-emitting device shown to a previous figure. It is a top view which shows a simulation result. It is a figure explaining the behavior of the light in the planar light-emitting device which provided the low refractive index layer only in the one part area | region. It is a top view which shows a simulation result. It is a figure which shows schematic structure of 4th Embodiment of the illumination module of this invention. It is a figure which shows schematic structure of 5th Embodiment of the illumination module of this invention. It is a figure which shows schematic structure of other embodiment of the illumination module of this invention. It is a figure which shows schematic structure of 6th Embodiment of the illumination module of this invention. It is a figure which shows the decorative board of the illumination module of a previous figure, (A) is sectional drawing, (B) is a top view. It is a top view which shows typically the other example of distribution of the micro dot which comprises a light extraction part. It is sectional drawing which shows schematic structure of an example of the conventional planar light-emitting device. It is a top view which shows schematic structure of the other example of the conventional planar light-emitting device.

(First embodiment)
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a diagram showing a schematic configuration of an illumination module 10 according to the first embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing the main parts of the light source 2 and the light guide 3 of the illumination module 10.
In the following description, “upper and lower” refers to the upper and lower in FIG.

As shown in FIG. 1, the illumination module 10 is provided on the planar light emitting device 1, the reflective sheet 30 (reflector) provided on the lower surface side of the planar light emitting device 1, and the lower surface side of the reflective sheet 30. A touch pad 20 (detection sensor).

The planar light emitting device 1 includes a light source 2 and a sheet-like (or plate-like) light guide 3.
As the light source 2, a light emitting diode (hereinafter referred to as LED) (light emitting element) can be used.
The light source 2 is preferably a high-luminance type, for example, a light intensity of 50 mcd or more (preferably 1000 to 3000 mcd). The height dimension of the light source 2 (the vertical dimension in FIGS. 1 and 2) is, for example, 0.3 to 2 mm.
As shown in FIG. 2, the light source 2 is installed with the light emitting surface 2 a facing the end surface 3 e of the one end portion 3 c of the light guide 3.
In addition, the light emitting element used as the light source 2 is not limited to the LED but may be a cold cathode tube.

The light guide 3 is preferably made of a transparent light-transmitting resin and has flexibility.
As the light transmissive resin, urethane resin, acrylic resin, polycarbonate resin, silicone resin, polystyrene resin, polyimide resin, polymethyl methacrylate (PMMA) elastomer, urethane acrylate, or the like can be used.

The thickness of the light guide 3, that is, the thickness T <b> 1 shown in FIG. 2 is 0.5 mm or more (preferably 0.7 mm or more).
Accordingly, even when a high-luminance type large LED or the like that can cope with an increase in area is used as the light source 2, it is possible to increase the utilization efficiency of light from the light source 2. This is because if the thickness of the light guide 3 is in the above range (0.5 mm or more), the height of the end face 3e is sufficiently larger than the height dimension of the light source 2, and therefore the light guide 3 from the end face 3e. This is because the incidence rate of the light L can be increased. Accordingly, the luminance and illuminance can be increased, and the area of the light guide 3 can be increased.
On the other hand, when the thickness of the light guide 3 is less than the above range, when a high-luminance type light source is used, the light use efficiency may be reduced, and the luminance and illuminance may be insufficient.

The thickness T1 of the light guide 3 is 2 mm or less (preferably 1.5 mm or less).
If the light guide 3 is too thick, the detection sensitivity of the input sensor of the touch pad 20 is lowered, but by increasing the thickness of the light guide 3 to the above range (2 mm or less), the detection sensitivity of the input sensor is increased. Can do.
For example, in the case of using a capacitance type input sensor, it is possible to input at a position close to the input sensor by setting the thickness of the light guide 3 within the above range (2 mm or less). Sensitivity can be secured. In addition, when a resistance film type input sensor is used, since the light guide 3 is easily deformed by pressing by setting the thickness of the light guide 3 within the above range (2 mm or less), the detection sensitivity is increased. Can do.
In addition, by setting the thickness within the above range (2 mm or less), the light guide 3 can be provided with sufficient flexibility. Therefore, the degree of freedom of the shape of the light guide 3 is increased, and the light guide 3 is guided during assembly. Installation work of the light body 3 becomes easy. Further, even when the installation target is not flat (for example, when the installation target is conical), the installation can be performed without a gap. Further, the outer shape processing of the light guide 3 by VIC processing, mold processing, or the like is facilitated. Therefore, manufacturing workability is also improved.
From the above, by setting the thickness of the light guide 3 to 0.5 mm or more and 2 mm or less, sufficient luminance and illuminance can be obtained, and the detection sensitivity of the input sensor can be increased. Furthermore, manufacturing workability is also improved.

The thickness T1 of the light guide 3 can be substantially the same as the height H1 of the light source 2.
Although the thickness T1 and the height H1 may be different, the difference between the thickness T1 and the height H1 is preferably within ± 0.3 mm. Thereby, the incidence rate of light from the light source 2 to the light guide 3 can be increased.

As shown in FIG. 1, incident light is scattered on the lower surface 3 a (one surface, back surface) of the light guide 3 and is extracted (emitted) toward the upper surface 3 b (other surface, surface) side of the light guide 3. ) The light extraction part 4 can be formed. The light extraction unit 4 can display a target portion (for example, the operation key unit of the touch pad 20) brightly.
The light extraction unit 4 can be a plurality of microdot-like ink layers (hereinafter simply referred to as microdots) formed by printing, for example. The minute dots are convex portions that protrude downward from the lower surface 3a. The planar view shape of each minute dot may be arbitrary, such as a circle, an ellipse, or a polygon (such as a rectangle). The minute dots can be formed by a printing method such as a screen printing method, a gravure printing method, a pad printing method, or an ink jet printing method.
As the ink constituting the fine dots, for example, white ink using titanium oxide as a pigment is suitable.
In addition, the light extraction part 4 may be a rough surface part formed by a notch, sandblasting or the like formed on the surface of the light guide.

The fine dots 4a in the example shown in FIG. 12 are circular in plan view, have the same outer diameter, and are arranged in a matrix composed of a plurality of rows. Specifically, the minute dots 4a are arranged such that the center 4b is positioned at a lattice point 7a of the square lattice 7 (a square vertex formed by the square lattice 7).
The minute dots 4a in this example form a plurality of rows 4A, 4A,... Parallel to each other, and the arrangement direction (left-right direction in FIG. 12) positions of the minute dots 4a between adjacent rows 4A are the same.
If the micro dots 4a are arranged in contact with each other, there is a possibility that the luminance locally increases at the portion, and therefore it is preferable to arrange the micro dots 4a apart from each other.

The minute dots 4a may be arranged as shown in FIG. The minute dots 4a in this example are arranged so that the center 4b is positioned at a lattice point 8a of the equilateral triangle lattice 8 (the vertex of the equilateral triangle formed by the equilateral triangle lattice 8).
In this example, the positions of the minute dots 4a in the adjacent rows 4A are different from each other in the arrangement direction (left-right direction in FIG. 13).
In the arrangement shown in FIG. 13, since the minute dots 4a can be arranged densely, the amount of light extraction can be increased.

For example, if minute dots 4a having an outer diameter of 50 μm are arranged on the square lattice 7 shown in FIG. 12 with an interval of 5 μm between adjacent minute dots 4a, the area ratio of the minute dots 4a per unit area is 0.65. On the other hand, when arranged on the equilateral triangular lattice 8 shown in FIG. 13, the area ratio of the minute dots 4a per unit area is 0.75. According to the arrangement shown in FIG. 13, the area ratio of the minute dots 4a can be increased, so that the light extraction amount can be increased.

FIG. 14 is a plan view schematically showing an example of the distribution of the minute dots 4a in the light extraction unit 4. As shown in FIG.
In the example shown in this figure, the minute dots 4a have the same outer diameter and are basically arranged along the equilateral triangular lattice shown in FIG. 13, but the formation density changes according to the distance from the light source 2. is doing.
That is, among the four regions A1 to A4 having different distances from the light source 2, in the first region A1 that is farthest from the light source 2, the fine dots 4a are arranged along the equilateral triangular lattice shown in FIG. ing. Hereinafter, this arrangement is referred to as a first arrangement.
In the second region A2, the arrangement of the minute dots 4a is a second arrangement in which a predetermined number of minute dots 4a are omitted from the first arrangement. In the third region A3, the arrangement of the minute dots 4a is a third arrangement in which a predetermined number of minute dots 4a are further omitted from the second arrangement. In the fourth region A4, the arrangement of the minute dots 4a is a fourth arrangement in which a predetermined number of minute dots 4a are further omitted from the third arrangement. The positions of the minute dots 4a that are omitted in the second to fourth arrangements are selected so as not to concentrate locally.
Thus, by arranging the micro dots 4a so that the formation density increases as the distance from the light source 2 increases, a sufficient light extraction amount can be ensured even at a position away from the light source 2.
For this reason, the luminance can be made uniform.

As shown in FIG. 12, the outer diameter D1 of the minute dots 4a is 10 to 100 μm.
By setting the outer diameter D1 to 100 μm or less, it becomes difficult for the human eye to visually recognize the shape and size of each dot, so that each minute dot 4a is visually recognized as a local light emitting point. Can be prevented. For this reason, it is possible to prevent the occurrence of uneven light emission and improve the light emission characteristics.
Since no unevenness of light emission occurs, a diffuser plate is not necessary, so that the overall luminance level can be increased, which is advantageous in terms of thinning the apparatus.

In order to confirm the effect when the outer diameter is in the above range, a planar light emitting device 1 having microdots 4a having outer diameters of 100 μm and 150 μm was produced, and a test was performed in which a plurality of subjects were observed from a position 30 cm away. . As a result, 70% of the subjects were able to visually recognize the minute dots 4a having an outer diameter of 150 μm as light emission points, but most of the subjects were not able to visually recognize the minute dots 4a having an outer diameter of 100 μm as light emission points.
From this test result, it was confirmed that when the outer diameter of the minute dots 4a is 100 μm or less, the minute dots 4a are difficult to visually recognize as light emitting points.
In addition, by setting the outer diameter D1 to 10 μm or more, dots having a certain thickness or more can be printed stably, and a sufficient amount of light can be extracted from each minute dot 4a. . Thereby, the brightness | luminance of the light extraction part 4 whole can be raised.

In addition, when the minute dots are not circular, the outer diameter of the minute dots can be one of the maximum diameter, the minimum diameter, and the average diameter. For example, in an elliptical minute dot, the average value of the major axis and the minor axis can be set as the outer diameter. In the case of square micro dots, the average value of the maximum diameter and the minimum diameter can be set as the outer diameter.

As shown in FIG. 15, the thickness T2 (height) of the minute dots 4a is preferably 0.5 to 10 μm.
If the micro dots 4a are too thick, they are easily damaged by an external force. However, if the thickness T2 is 10 μm or less, the micro dots 4a can be prevented from being damaged and the durability can be improved.
If the micro dots 4a become too thick, the light absorbed by the micro dots 4a may increase and the loss may increase. However, by increasing the thickness T2 to 10 μm or less, an increase in loss can be prevented. .

As shown in FIG. 16, when the micro dots 4a become too thick, a large amount of scattered light indicated by arrows is emitted in a direction inclined with respect to the light guide 3, so that the user viewing the light guide 3 from the front side. However, if the thickness T2 is 10 μm or less, as shown in FIG. 15, scattered light with a relatively small inclination component can be obtained, so that the luminance can be increased.

If the micro dots 4a are too thin, sufficient scattered light may not be obtained. However, if the thickness T2 is 0.5 μm or more, a sufficient amount of filler 9 is included in the dots. It is possible to cause sufficient light scattering, increase the amount of extracted light, and improve the luminance.

As shown in FIG. 17A, if the micro dots 4a are too thin, the amount of the filler 9 contained in the ink constituting the micro dots 4a is reduced, and the interface of the micro dots 4a is that of the light guide 3. It tends to be almost parallel to the interface.
As shown in FIG. 17 (b), when light enters such a micro dot 4a, more light is directly reflected at the interface of the micro dot 4a and returned into the light guide 3, and the light scattering efficiency deteriorates. there is a possibility. Therefore, it is desirable that the minute dots 4a are not too thin, and a thickness of 0.5 μm or more is preferable.

15 to 17 exemplify the case of using light (indicated by solid line arrows) emitted from the scattered light on the surface side (upper side in the figure) on which the minute dots 4a are formed. When it is necessary to extract light to the side opposite to the surface on which 4a is formed (downward in the figure), downward light (indicated by a two-dot chain line) of scattered light can be used.
With respect to the light emitted to the surface opposite to the minute dots 4a (downward in the figure), by setting the thickness of the minute dots 4a within the above-mentioned range, scattered light with a small inclination component can be obtained and the luminance can be increased. Can do.
The illumination module shown in FIG. 1 has a structure in which light is extracted to the surface opposite to the surface (lower surface 3a) on which the minute dots 4a are formed. The illumination module (described later) shown in FIG. In this structure, light is extracted to the formed surface (upper surface 3b) side.

Further, when the light guide 3 is in close contact with the reflection sheet 30, there is a possibility that the propagation of light in the light guide 3 may be affected (see FIG. 20), but the thickness of the minute dots 4a is set within the above range (0.5 to 10 μm) and the outer diameter is in the above range (10 to 100 μm), a sufficiently large convex portion is formed on the lower surface 3 a of the light guide 3. It becomes difficult to adhere to the light, and adverse effects on the propagation of light in the light guide 3 can be prevented.

Further, in the planar light emitting device 1, since the light extraction portion 4 is formed by an ink layer formed by printing, the thin light guide 3 can be used unlike the case where the light extraction portion is formed by a concave portion. The thin light emitting device 1 can be reduced in thickness.
Moreover, since the light extraction part 4 can be formed by printing, manufacturing efficiency can be improved.

The ink constituting the minute dots 4a preferably contains titanium oxide. Since titanium oxide functions as a white pigment, the ink exhibits a white color. Titanium oxide also functions as a filler.
By using titanium oxide, the light emission efficiency in the planar light emitting device 1 can be increased.

FIG. 18 shows the brightness of the emitted light from the minute dots 4a by forming the minute dots 4a (area ratio 0.5) on the light guide 3 using ink containing rutile type titanium oxide having a concentration of 1 to 50% by mass. The result of having measured is shown.
As shown in this figure, a high luminance is obtained when the titanium oxide content is 5 mass% or more, particularly 5 to 50 mass%. Further, when the content is 10 to 40% by mass, higher luminance can be obtained.
From this result, it was confirmed that the luminous efficiency can be increased by adding titanium oxide to the ink constituting the minute dots 4a. When the titanium oxide content is 5 to 50% by mass or more, preferably 10 to 40% by mass or more, high luminance can be obtained.

Examples of titanium oxide added to the ink constituting the minute dots 4a include rutile type and anatase type, and rutile type titanium oxide is particularly preferable.
FIG. 19 is a graph showing the results of a comparative test between the rutile type and the anatase type. In this test, a minute dot 4a (area ratio 0.5) is formed on the light guide 3 using ink containing rutile or anatase type titanium oxide (20% by mass), and light emitted from the minute dot 4a. The brightness of was measured.
From this figure, it can be seen that when rutile type titanium oxide was used, a luminance about ²⁰ Cd / m ² higher than that obtained when anatase type titanium oxide was used was obtained. From this result, it can be seen that it is preferable to use rutile type titanium oxide from the viewpoint of improving luminance.

In order to emit white light, it is necessary to scatter the entire visible light evenly. Here, considering the relationship between the wavelength to be scattered and the particle size of titanium oxide, the particle size of titanium oxide is preferably 10 nm to 0.5 μm.

The reflection sheet 30 is a sheet material made of a resin such as PET (polyethylene terephthalate) for reflecting light leaked downward from the light guide 3 by the upper surface 30b and returning it to the light guide 3. . The reflective sheet 30 is desirably white from the viewpoint of reflectivity. The reflection sheet 30 is provided on the lower surface 3 a side of the light guide 3.

The touch pad 20 includes an input sensor 21 and a resist layer 22 (covering resin layer) formed thereon.
The input sensor 21 is a sensor that detects the proximity or contact of the detection target 25 such as a human finger. Here, the input sensor 21 is a capacitance type input sensor, and has a configuration in which the wiring layer 24 is provided on the upper surface 23 b of the substrate 23.
The substrate 23 is a plate material made of a resin such as PET. The substrate 23 may be a flexible substrate made of PEN (polyethylene naphthalate), polyimide, or the like, or a rigid substrate made of glass epoxy resin or the like.

The wiring layer 24 includes, for example, a plurality of electrodes 24a. When the detection object 25 such as a human finger approaches, an electrostatic capacity is formed between the detection object 25 and the electrode 24a, and this capacitance is an opposing area between the detection object 25 and the electrode 24a. And changes depending on the separation distance. For this reason, the to-be-detected body 25 and the electrode 24a form a variable capacitance part.
A change in the capacitance of the variable capacitance unit is detected by a detecting means (not shown), and an input operation by the detected body 25, its position, etc. are grasped by a control unit (not shown) based on the detected value.

The wiring layer 24 can be formed, for example, by heating a silver paste containing silver particles after screen printing on the substrate 23. The wiring layer 24 may be formed by etching a copper foil laminated on the substrate 23.
The resist layer 22 ensures electrical insulation between the wiring layers 24 and prevents oxidation. The resist layer 22 has an upper surface 23b of the substrate 23 and the wiring layer 24 on the upper surface (surface on the light guide 3 side) side of the input sensor 21. It is formed to cover. For example, a general-purpose solder resist can be used as the resist layer 22.

Since the capacitance type input sensor 21 employed in the touch pad 20 has a simple structure including one substrate 23 and a wiring layer 24, it is thinner than a sensor using a plurality of substrates. Is possible. The touch pad 20 can be made flexible by reducing the thickness.
Further, since the structure of the input sensor 21 is simple, the cost can be reduced and the assembling work can be facilitated.

In the illustrated example, the touch pad 20 employs a capacitive input sensor, but other methods such as a resistive film type input sensor may be employed. A pressure sensitive membrane switch can also be used. The resistance film type sensor and the membrane switch will be described later.

The light guide 3 and the reflection sheet 30 are bonded to each other by the adhesive layer 5 formed on the peripheral edge portion of the lower surface 3 a of the light guide 3.
The reflection sheet 30 and the touch pad 20 are bonded to each other by the adhesive layer 6 formed on the peripheral edge portion of the lower surface 30a of the reflection sheet 30.
For the adhesive layers 5 and 6, for example, an adhesive material such as an acrylic resin, a polyurethane resin, an epoxy resin, a urethane resin, a natural rubber adhesive material, or a synthetic rubber adhesive material can be used. As the adhesive layers 5 and 6, a so-called double-sided tape-like material in which an adhesive material layer coated with an adhesive material is formed on both surfaces of a sheet-like base material can be used.

As shown in FIGS. 2 and 11, the light L from the light source 2 enters the light guide 3 from the end surface 3e of the one end portion 3c, and is reflected on the upper surface 3b, the lower surface 3a, and the like toward the other end portion 3d. Propagate. Part of the incident light is scattered by the light extraction unit 4 and extracted to the upper surface 3b side.

In this illumination module 10, since the thickness of the light guide 3 is 0.5 mm or more and 2 mm or less, the thickness of the light guide 3 can be changed even when a large high-luminance light source 2 is used. Therefore, it is possible to increase the incident rate of light introduced into the light guide 3 through the end face 3e and increase the light utilization efficiency.
Moreover, since the planar light emitting device 1 is provided on the upper surface side (outer surface side) of the touch pad 20, light from the planar light emitting device 1 is not blocked by the touch pad.
Therefore, sufficient luminance and illuminance can be ensured even when the light guide 3 has a large area.
In the illumination module 10, the detection sensitivity of the input sensor 21 of the touch pad 20 can be increased by setting the thickness of the light guide 3 in the above range.
In addition, since the touch pad 20 is installed on the lower surface side (back surface side) of the planar light emitting device 1, it is not necessary to use an expensive transparent type touch pad 20. For this reason, cost reduction can be achieved.
Moreover, since the operations such as the outer shape processing and installation of the light guide 3 are facilitated in manufacturing the illumination module 10, the manufacturing workability is also improved.

(Second Embodiment)
FIG. 3 is a diagram showing a schematic configuration of the illumination module 40 according to the second embodiment of the present invention.
In the following description, portions common to the first embodiment may be denoted by the same reference numerals and description thereof may be omitted.
The illumination module 40 includes a planar light emitting device 1 and a touch pad 20 provided on the lower surface side of the planar light emitting device 1.
A resist layer 22 (covering resin layer) formed on the upper surface (surface on the light guide 3 side) of the input sensor 21 of the touch pad 20 is a reflection that reflects light leaked downward from the light guide 3 on the upper surface 22a. Functions as a body. The resist layer 22 is preferably made of a white material. As this white material, for example, a material containing titanium oxide as a pigment can be used. When a white material is used for the resist layer 22, the effect of reflecting the light leaked from the light guide 3 can be enhanced.
As the white material constituting the resist layer 22, for example, a material containing 20 to 30% by mass of an acrylate resin, 20 to 30% by mass of diethylene glycol monoethyl ether acetate, and 10 to 20% by mass of titanium oxide can be used.

In the illumination module 40, compared with the illumination module 10 of 1st Embodiment, since there is no reflective sheet 30 between the planar light-emitting device 1 and the touchpad 20, thickness reduction can be achieved. In addition, since an adhesive layer for adhering the reflective sheet 30 to the touch pad 20 is not necessary, the thickness can be further reduced.
Since there is no reflection sheet 30, input at a position close to the input sensor 21 is possible, so that the detection sensitivity of the input sensor 21 of the touch pad 20 can be further increased. Further, the flexibility of the illumination module 40 can be increased by reducing the thickness.
Further, by causing the resist layer 22 to function as a reflector, it is possible to reduce the thickness without reducing the reflection performance.
Moreover, since the structure is simpler than the illumination module 10 of the first embodiment, the number of parts is small, which is advantageous in terms of cost and manufacturing workability.

Since the capacitance type input sensor 21 employed in the touch pad 20 has a simple structure including one substrate 23 and a wiring layer 24, it is thinner than a sensor using a plurality of substrates. Is possible. Therefore, the illumination module 40 can be further reduced in thickness.

In FIG. 3, the capacitance type input sensor 21 is employed, but another method, for example, a resistance film type input sensor may be employed.
FIG. 4 shows an example of a touch pad using a resistance film type input sensor. The touch pad 60 (detection sensor) includes an upper substrate 61 having a transparent conductive film 63 formed on the opposing surface 61a, and an opposing surface. 62a, and a lower substrate 62 on which a transparent conductive film 64 is formed.
A plurality of dot spacers 66 are formed on the transparent conductive film 64 of the lower substrate 62. The upper substrate 61 and the lower substrate 62 are disposed so that the transparent conductive films 63 and 64 face each other with a space therebetween.
A reflective layer 65 (reflector) is formed on the upper surface 61 b of the upper substrate 61. The reflective layer 65 functions as a reflector that reflects light leaked downward from the light guide 3. If the white material is used for the reflective layer 65, the effect of reflecting the light leaked from the light guide 3 can be enhanced. Reference numeral 67 denotes an adhesive layer.
In the touch pad 60, for example, when the touch pad 60 is pressed downward by the detection target 25 (see FIG. 1), the upper substrate 61 is bent downward, and the transparent conductive films 63 and 64 are brought into contact with each other to be conductive. An input operation or the like is detected.

In the present invention, a pressure sensitive membrane switch (detection sensor) may be used instead of the touch pad 20.
FIG. 5 shows a pressure-sensitive membrane switch 70. The membrane switch 70 includes an upper substrate 71 having a wiring layer 73 and an upper electrode 76 formed on the opposing surface 71a, and a wiring layer 74 and a lower portion on the opposing surface 72a. And a lower substrate 72 on which an electrode 77 is formed.
The upper substrate 71 and the lower substrate 72 are arranged so that the electrodes 76 and 77 face each other with a space therebetween.
A resist layer 75 (covering resin layer) is formed on the upper surface 71 b of the upper substrate 71. The resist layer 75 functions as a reflector that reflects light leaked downward from the light guide 3. When the white material is used for the resist layer 75, the effect of reflecting the light leaked from the light guide 3 can be enhanced. Reference numeral 78 denotes an adhesive layer.
In the membrane switch 70, when the upper substrate 71 is bent downward by the pressure of the detection target 25 (see FIG. 1), the upper electrode 76 contacts the lower electrode 77, and these are electrically connected to detect an input operation or the like. .

The illumination modules 10 and 40 of the first and second embodiments have a structure in which an external force is easily applied to the light guide 3 because the planar light emitting device 1 is positioned on the outermost surface side (upper surface side).
FIG. 6 shows an example in which a structure for protecting the light guide 3 is provided. In this example, a protective layer 50 is provided on the upper surface 3 b of the light guide 3. The protective layer 50 is made of, for example, a fluororesin.
The protective layer 50 can prevent the upper surface 3b of the light guide 3 from being damaged or contaminated.

Next, the test result about the influence of the thickness of the light guide 3 in the illumination module 10 will be described.
(Test Example 1)
As shown in FIG. 1, a planar shape including a urethane-based resin light guide 3 (length 100 mm, width 50 mm) and a light source 2 (LED, height 0.6 mm, luminous intensity 2400 mcd) having a rectangular shape in plan view. The light emitting device 1 was produced.
The light source 2 has a configuration in which 21 LEDs are arranged at equal intervals along an edge portion that forms one long side of the light guide 3.
A reflective sheet 30 made of PET was installed on the lower surface side of the planar light emitting device 1.

(Test Example 2)
A planar light emitting device 1 similar to Test Example 1 was produced except that an LED having a height of 0.8 mm and a luminous intensity of 2500 mcd was used as the light source 2.

(Test Example 3)
A planar light emitting device 1 similar to Test Example 1 was produced except that an LED having a height of 1.2 mm and a luminous intensity of 1500 mcd was used as the light source 2.

For each test example, the luminance at the center of the upper surface 3b of the light guide 3 and the illuminance at a position 60 cm upward from the upper surface 3b were measured. Table 1 shows measurement results of luminance and illuminance, and luminous intensity contribution efficiency (efficiency in which the unit luminous intensity (1 cd) of the light source 2 contributes to illuminance (50 cm)). The luminous intensity contribution efficiency is also shown in FIG.

From Table 1 and FIG. 7, it can be seen that excellent results in luminance, illuminance, and luminous intensity contribution efficiency were obtained by setting the thickness of the light guide 3 to 0.5 mm or more.

(Test Example 4)
As shown in FIG. 1, the illumination module 10 using the touchpad 20 which employ | adopted the electrostatic capacitance type sensor was produced. The relative permittivity of the light guide 3 was 7 and the relative permittivity of the resist layer 22 was 27. The area of the light guide 3 was 0.0001 m ² , and the thickness of the resist layer 22 was 0.01 mm.
The touch pad 20 is formed by forming a wiring layer 24 (thickness 10 μm) using a silver paste on an upper surface 23b of a substrate 23 (thickness 75 μm) made of PET, and forming a resist layer 22 (thickness 30 μm) thereon. The configuration (total thickness 105 μm) was obtained.
FIG. 8 shows the result of examining the influence of the thickness of the light guide 3 on the capacitance.
As shown in this figure, when the thickness of the light guide 3 was 2 mm or less, a preferable capacitance (10 pF or more) was obtained.

(Test Example 5)
As shown in FIG. 4, the illumination module 10 was produced in the same manner as in Test Example 4 except that a touch pad 60 employing a resistive film type sensor was used.
The touch pad 60 includes an upper substrate 61 (total thickness 180 μm) on which a transparent conductive film 63 made of ITO is formed, and a lower substrate 62 (total thickness 180 μm) on which a transparent conductive film 64 made of ITO is formed. The reflection layer 65 (thickness 30 μm) was formed on the upper surface 61 b of the upper substrate 61 (total thickness 520 μm). The distance between the transparent conductive films 63 and 64 facing each other was 130 μm.
A downward load was applied to the light guide 3, and the load when the continuity of the transparent conductive films 63 and 64 was obtained was recorded as an ON load. FIG. 9 shows the result of examining the influence of the thickness of the light guide 3 on the ON load.
As shown in this figure, when the thickness of the light guide 3 was 2 mm or less, a preferable ON load (2 N or less) was obtained.

(Test Example 6)
As shown in FIG. 5, the illumination module 10 was produced in the same manner as in Test Example 4 except that a membrane switch was used.
The membrane switch 70 includes an upper substrate 71 (thickness 75 μm) on which a wiring layer 73 (thickness 10 μm) and an upper electrode 76 are formed, and a lower substrate 72 on which a wiring layer 74 (thickness 10 μm) and a lower electrode 77 are formed. (Thickness: 75 μm), and the reflective layer 75 (thickness: 30 μm) is formed on the upper surface 71 b of the upper substrate 71 (total thickness: 250 μm). The distance between the substrates 71 and 72 facing each other was 70 μm.
The influence of the thickness of the light guide 3 on the ON load was examined. The results are shown in FIG.
As shown in this figure, when the thickness of the light guide 3 was 2 mm or less, a preferable ON load (7 N or less) was obtained.

From the results of Test Examples 1 to 6, it was found that by setting the thickness of the light guide to 0.5 to 2 mm, sufficient luminance and illuminance can be secured and the detection sensitivity of the detection sensor can be increased.

(Third embodiment)
Next, a third embodiment of the present invention will be described. Parts common to the first embodiment or the second embodiment may be denoted by the same reference numerals and description thereof may be omitted.
FIG. 20 is a diagram illustrating a schematic configuration of the illumination module 110 according to the third embodiment of the present invention. FIG. 21 is a cross-sectional view showing a main part of the planar light emitting device 101. FIG. 22 is a cross-sectional view showing the touch pad 20.
The planar light emitting device 101 includes a light source 2, a sheet-shaped (or plate-shaped) light guide 3, and a low refractive index layer 104 formed on the lower surface 3 a (one surface) of the light guide 3. Yes.
As shown in FIG. 21, the light source 2 is installed with the light emitting surface 2 a facing the end surface 3 e of the one end 3 c of the light guide 3, and light can be incident on the light guide 3 from the end surface 3 e. The light from the light source 2 propagates from one end 3c of the light guide 3 toward the other end 3d (see FIG. 20) while being reflected on the upper surface 3b, the lower surface 3a, and the like of the light guide 3.
Hereinafter, the direction from the one end 3c toward the other end 3d (rightward in FIG. 20) may be referred to as a light guide direction X.

As shown in FIG. 21, the low refractive index layer 104 is a layer made of a material having a refractive index lower than that of the light guide 3, and for example, a fluororesin can be used.
The refractive index of the low refractive index layer 104 can be set according to the refractive index of the light guide 3. This refractive index is preferably as low as possible, and can be, for example, 1.4 or less (for example, 1 to 1.4).
The thickness of the low refractive index layer 104 can be set to 0.01 to 0.03 mm, for example.

The low refractive index layer 104 is formed only in a partial region (hereinafter, formation region A1) of the lower surface 3a of the light guide 3. A region where the low refractive index layer 104 is not formed is referred to as a non-formed region A2.
The formation area A1 and the non-formation area A2 are different from each other in the light guide direction X, and the non-formation area A2 is located farther from the light source 2 than the formation area A1.
In the illustrated example, the non-forming area A2 is adjacent to the forming area A1 in the light guide direction X. Specifically, the formation region A1 is a region within a predetermined distance in the light guide direction X from the one end 3c of the lower surface 3a of the light guide 3, and the non-formation region A2 is the other region, that is, low refraction. This is a region from the tip 104d in the light guide direction X of the index layer 104 to the other end 3d.

In the illustrated example, the entire non-forming area A2 is located farther from the light source 2 than the forming area A1, but at least a part of the non-forming area A2 is located farther from the light source 2 than the forming area A1. That's fine.

Incident light is scattered on the lower surface 104a (the surface opposite to the light guide 3 side) of the low refractive index layer 104 in the formation region A1 and the lower surface 3a of the light guide 3 in the non-formation region A2 to scatter the light guide 3. It is possible to form a light extraction portion 105 that is extracted (emitted) to the upper surface 3b (the other surface) side (see the arrow in FIG. 20).
20 and 21, the light extraction portion 105 is formed in the entire area of the lower surface 104a of the formation region A1 and the lower surface 3a of the non-formation region A2, but the light extraction portion 105 is formed in a partial region of the lower surfaces 3a and 104a. It may be formed. The light extraction unit 105 can be a plurality of microdot-like ink layers formed in a partial region of the lower surfaces 3a and 104a by printing, for example. The shape of each fine dot-shaped ink layer in plan view may be arbitrary, such as a circle, an ellipse, or a polygon (such as a rectangle).
The light extraction unit 105 may have the same configuration as the light extraction unit 4 of the first and second embodiments.

As shown in FIG. 22, the touch pad 20 includes an input sensor 21 and a resist layer 22 (covering resin layer) formed thereon. In the illustrated example, the input sensor 21 is a capacitance type input sensor, and has a configuration in which a wiring layer 24 is provided on the upper surface 23 b of the substrate 23.
A protective layer 50 made of, for example, a fluororesin can be provided on the upper surface 3 b of the light guide 3. The protective layer 50 can prevent the upper surface 3b of the light guide 3 from being damaged or contaminated.

The planar light emitting device 101 and the reflection sheet 30 are mutually attached by the adhesive layer 106 formed on the peripheral portion of the planar light emitting device 101 (the lower surface 104a of the low refractive index layer 104 and the peripheral surface of the lower surface 3a of the light guide 3). It is glued.
The reflective sheet 30 and the touch pad 20 are bonded to each other by an adhesive layer 107 formed on the lower surface 30 a of the reflective sheet 30.
For the adhesive layers 106 and 107, for example, an adhesive material such as an acrylic resin, a polyurethane resin, an epoxy resin, a urethane resin, a natural rubber adhesive material, or a synthetic rubber adhesive material can be used. As the adhesive layers 106 and 107, a so-called double-sided tape in which an adhesive material layer coated with an adhesive material is formed on both surfaces of a sheet-like substrate can be used.

As shown in FIG. 21, the light from the light source 2 enters the light guide 3 from the end surface 3e of the one end 3c.
In the formation region A1, the high-order mode light L1 (light with a large propagation angle) out of the light incident on the light guide 3 is low-order mode light L2 (with a small propagation angle) when entering the low refractive index layer 104. Light).
Since the low-order mode light L2 propagating through the low refractive layer 104 is difficult to be emitted to the outside even when scattered, the amount of light emitted to the outside (light extraction amount) in the light extraction unit 105 is kept low. Further, the light propagating through the low refractive layer 104 without being emitted to the outside is reconverted into the high-order mode light L1 by being incident on the light guide 3 again. For this reason, in the formation region A1, the loss of light that becomes a higher-order mode in the light guide 3 is suppressed. The light L2 in the low refractive index layer 104 is reflected by the lower surface 104a.
The light L2 becomes high-order mode light L1 again when entering the light guide 3, is reflected by the upper surface 3b of the light guide 3, and becomes low-order mode light L2 when entering the low refractive index layer 104. Then, the light is propagated in the right direction of FIG. 21 while repeating the process of reflecting on the lower surface 104a of the low refractive index layer 104.

In the non-formation region A2, the light L1 propagates toward the other end 3d while being reflected on the upper surface 3b, the lower surface 3a, and the like in the light guide 3 in the higher-order mode. Since higher-order mode light is easily emitted to the outside when scattered, the amount of light emitted to the outside (light extraction amount) in the light extraction unit 105 increases.
As described above, the light converted into the low-order mode is incident again on the light guide and re-converted into the high-order mode while maintaining the low-order mode even when scattered. That is, since the high-order mode light is not lost in the formation region A1, the light introduced into the non-formation region A2 contains a large amount of high-order mode light, so that the light extraction amount in the light extraction unit 105 can be increased.

In the planar light emitting device 101, the low refractive index layer 104 is formed only in a partial region of the lower surface 3a of the light guide 3, and the non-forming region A2 is located farther from the light source 2 than the forming region A1. The light extraction amount can be kept low in a region near the light source 2 and the light extraction amount can be increased in a region far from the light source 2. For this reason, it is effective in achieving uniform brightness.

Hereinafter, the function and effect of the planar light emitting device 101 will be described in detail with reference to FIGS.
(Test Example 7)
As shown in FIG. 23, a planar light emitting device 101A in which a light extraction portion 105 is formed on the upper surface 3b of the light guide 3 (refractive index 1.49) is assumed. The light guide 3 had a length of 50 mm, a width of 10 mm, and a thickness of 0.5 mm.
A symbol L illustrated in FIG. 24 indicates higher-order mode light (light having a large propagation angle) among the light incident on the light guide 3. The light L propagates toward the other end 3d while being reflected by the upper surface 3b, the lower surface 3a, etc. in the light guide 3. Since the high-order mode light has a large propagation angle, it is easily emitted outside the light guide 3 by scattering in the light extraction unit 105. For this reason, in the planar light emitting device 101A, the amount of light emitted from the light extraction unit 105 to the outside (light extraction amount) increases at a position close to the one end 3c.

FIG. 25A is a plan view showing a luminance distribution obtained by simulation. In this simulation, it is assumed that light from the light source 2 (input light quantity 0.55 (lm)) is incident on the light guide 3 from the end surface of the one end 3c. From this figure, it can be seen that in the planar light emitting device 101A, a portion where the light extraction amount is very large, that is, a so-called hot spot S1 is generated at a position near the one end 3c.
As shown in FIG. 25 (b), the luminance at a position 3 mm away from the one end 3c (first position P1) was 730 cd / m ² . The luminance at a position 28 mm away from the one end 3c (second position P2) was 64 cd / m ² .

(Test Example 8)
As shown in FIG. 26, the low refractive index layer 104 (refractive index 1.4) is formed over the entire upper surface 3 b of the light guide 3, and the light extraction portion 105 is formed on the upper surface 104 b of the low refractive index layer 104. A planar light emitting device 101B was assumed.
27 indicates high-order mode light (light having a large propagation angle) among the light incident on the light guide 3. When the light L1 enters the low refractive index layer 104, the light L1 is converted into low-order mode light L2 (light having a small propagation angle).
Even if the low-order mode light L2 is scattered, it is difficult to be emitted to the outside. Therefore, the amount of light emitted to the outside (light extraction amount) in the light extraction unit 105 is kept low. For this reason, in the planar light emitting device 101B, the loss of light that becomes a higher-order mode within the light guide 3 is suppressed. The light L2 in the low refractive index layer 104 is reflected by the upper surface 104b.
The light L2 becomes high-order mode light L1 again when entering the light guide 3, is reflected by the lower surface 3a of the light guide 3, and becomes low-order mode light L2 when entering the low refractive index layer 104. Then, the light is propagated in the right direction of FIG. 27 while repeating the process of reflecting on the upper surface 104b of the low refractive index layer 104.

FIG. 28 is a plan view showing a luminance distribution obtained by the same simulation as in Test Example 7. From this figure, it can be seen that in the planar light emitting device 101B, the hot spot S1 near the one end 3c is smaller than that in Test Example 7.
The luminance at the first position P1 (see FIG. 25B) was 407 cd / m ² . The luminance at the second position P2 was 18 cd / m ² .

(Test Example 9)
As shown in FIG. 29, the low refractive index layer 104 (refractive index 1.4) is formed only in a partial region (formation region A1) of the upper surface 3b of the light guide 3, and the low refractive index layer 104 in the formation region A1. A planar light emitting device 101C in which a light extraction portion 105 is formed on the upper surface 104b of the light guide 3 and the upper surface 3b of the light guide 3 in the non-formation area A2 is assumed. The formation region A1 is a region within a predetermined distance from the one end 3c.
In the formation region A1, the high-order mode light L1 is converted into the low-order mode light L2 when entering the low refractive index layer 104. Even if the low-order mode light L2 is scattered, it is difficult to be emitted to the outside. Therefore, the amount of light emitted to the outside (light extraction amount) in the light extraction unit 105 is kept low. For this reason, in the formation region A1, the loss of light that becomes a higher-order mode in the light guide 3 is suppressed. The light L2 in the low refractive index layer 104 is reflected by the upper surface 104b.
The light L2 becomes high-order mode light L1 again when entering the light guide 3, is reflected by the lower surface 3a of the light guide 3, and becomes low-order mode light L2 when entering the low refractive index layer 104. Then, the light is propagated in the right direction of FIG. 29 while repeating the process of reflecting on the upper surface 104b of the low refractive index layer 104.

In the non-formation region A2, the light L1 propagates toward the other end 3d while being reflected on the upper surface 3b, the lower surface 3a, etc. in the light guide 3 in the higher order mode. Since higher-order mode light is likely to be emitted to the outside when scattered, the amount of light emitted to the outside (light extraction amount) in the light extraction unit 105 increases.

FIG. 30 is a plan view showing the luminance distribution obtained by the same simulation as in Test Example 7.
The luminance at the first position P1 (in the formation region A1) (see FIG. 25B) was 407 cd / m ² . The luminance at the second position P2 (in the non-forming area A2) was 129 cd / m ² .
The luminance obtained in Test Examples 7 to 9 is shown in Table 2.

As shown in Table 2, in Test Examples 8 and 9 in which the low refractive index layer 104 is provided, the luminance at the first position P1 is lower than that in Test Example 7, and therefore the light source 2 can be obtained by using the low refractive index layer 104. It can be seen that the amount of light extraction at a position close to can be suppressed.
Moreover, in any test example, since the brightness | luminance in 2nd position P2 is lower than the brightness | luminance in 1st position P1, it was shown that light attenuates as it leaves | separates from the light source 2. FIG.
In Test Example 8 in which the low refractive index layer 104 was formed over the entire area of the light guide 3, the luminance at the second position P <b> 2 was lower than that in Test Example 7 and thus efficient by sandwiching the low refractive index layer 104. It can be seen that the light is confined to.
Since the luminance at the second position P2 in Test Example 9 is higher than that in Test Example 8, it can be seen that the light extraction amount at the second position P2 (non-forming region A2) can be increased.

From these test results, in Test Example 9 in which the low refractive index layer 104 is formed only in a partial region of the lower surface 3 a of the light guide 3, the light extraction amount is kept low in the region close to the light source 2 and the light source 2 It can be seen that the amount of light extraction can be increased in a distant area, so that the luminance can be made uniform.

In the example shown in FIG. 20, the planar light emitting device 101 is applied to the illumination module 110, but is not limited thereto, and can be applied to a liquid crystal television, an in-vehicle room lamp, and the like. Since the planar light emitting device 101 can make the luminance uniform, it is particularly effective in the case of an application requiring a large area.

(Fourth embodiment)
FIG. 31 is a diagram showing a schematic configuration of an illumination module 140 according to the fourth embodiment of the present invention.
The illumination module 140 includes a planar light emitting device 101 and a touch pad 20 provided on the lower surface side of the planar light emitting device 101.
The resist layer 22 formed on the upper surface (surface on the light guide 3 side) of the input sensor 21 of the touch pad 20 reflects the light leaking downward from the light guide 3 and returns it to the light guide 3. Function as. The resist layer 22 (coating resin layer) (see FIG. 22) of the touch pad 20 is preferably made of a white material. As this white material, a material containing titanium oxide as a pigment can be used.

In the illumination module 140, compared with the illumination module 110, since there is no reflective sheet 30 between the planar light emitting device 101 and the touch pad 20, the thickness can be reduced. Moreover, the detection sensitivity of the input sensor 21 of the touch pad 20 can be further increased. Further, since the structure is simple, it is advantageous in terms of cost and manufacturing workability.

(Fifth embodiment)
FIG. 32 is a diagram showing a schematic configuration of an illumination module 160 according to the fifth embodiment of the present invention.
The illumination module 160 has the same configuration as the illumination module 110 except for the planar light emitting device 161.
The planar light emitting device 161 is different from the planar light emitting device 101 in that the low refractive index layer 104 and the light extraction unit 105 are provided on the upper surface 3 b side of the light guide 3.
In the planar light emitting device 161, the low refractive index layer 104 is formed only in a partial region (formation region A1) of the upper surface 3b of the light guide 3. A light extraction portion 105 is formed on the upper surface 104b of the low refractive index layer 104 in the formation region A1 and the upper surface 3b of the light guide 3 in the non-formation region A2. The formation region A1 is a region within a predetermined distance from the one end 3c.

Even in the planar light emitting device 161, similarly to the planar light emitting device 101, the light extraction amount can be kept low in the formation region A1 close to the light source 2, and the light extraction amount can be increased in the non-formation region A2 far from the light source 2. The brightness can be made uniform.

Note that the light extraction portion may be an uneven portion such as a notch or a rough surface portion formed in the upper surfaces 3b and 104b. Nanoimprinting or sandblasting can be used for forming the rough surface portion.

In FIG. 1, the light extraction part 4 is provided on the lower surface 3a of the light guide 3. However, as shown in FIG. 33, the light extraction part 4 can also be provided on the upper surface 3b. Also in this example, part of the light in the light guide 3 can be extracted upward by the light extraction unit 4.

(Sixth embodiment)
FIG. 34 is a diagram showing a schematic configuration of a lighting module 80 according to the sixth embodiment of the present invention.
The illumination module 80 is such that a decorative plate 240 (cover plate) is provided on the upper surface 3b side of the light guide 3 and that the adhesive layer 6 is formed over the entire lower surface 30a of the reflective sheet 30. Different from the illumination module 10 of FIG.
The decorative plate 240 has a size that can cover substantially the entire light guide 3 in plan view, and is bonded to the upper surface 3b of the light guide 3 via an adhesive layer 241 provided on the peripheral edge.
The decorative board 240 is made of a resin material such as PET. It is preferable to use a transparent material for the decorative plate 240 so that the light emitted from the light guide 3 can be visually recognized from the outside.
By providing the decorative plate 240, the light guide 3 can be prevented from being scratched or contaminated, and the durability of the lighting module 80 can be enhanced.
In the illustrated example, the adhesive layer 6 is formed over the entire lower surface 30a of the reflective sheet 30, but the region where the adhesive layer 6 is formed is not limited to this, and only a part of the lower surface 30a (for example, only the peripheral portion). It may be formed.

As shown in FIGS. 35 (A) and 35 (B), in the lighting module 80, the decorative plate 240 is made of an opaque material, and the light from the light guide 3 can be visually recognized on the decorative plate 240 from the outside. An opening 242 can also be formed.
When the opening 242 has a shape representing a number, a character, a symbol, a figure, a pattern, or the like, light emission corresponding to the shape can be obtained. In the example shown in FIG. 35B, the opening 242 has a planar shape corresponding to the number “1”, and thus functions as a display indicating the number “1”.

FIG. 36 is a plan view schematically showing another example of the distribution of the minute dots 4a in the light extraction unit 4. FIG.
In the example shown in FIG. 36, unlike the arrangement along the equilateral triangular lattice shown in FIG. 14, the micro dots 4a are arranged along the square lattice (see FIG. 12). The closer to the light source 2, the lower the formation density of the minute dots 4a. For example, among the four areas A1 to A4 having different distances from the light source 2, the closer to the light source 2, the lower the density of the fine dots 4a.
Since the square lattice can arrange the fine dots 4a at a lower density than the regular triangle lattice, the amount of light extraction can be suppressed. For this reason, the arrangement of the minute dots 4a shown in FIG. 36 is suitable when a relatively low luminance is required.
In addition, since the arrangement directions of the minute dots 4a in the square lattice are two directions orthogonal to each other, a general-purpose moving mechanism is used when the method of forming the minute dots 4a by the inkjet printing method while moving the light guide 3 is used. You can use the manufacturing equipment you have.
Therefore, if the arrangement of the minute dots 4a shown in FIG. 36 is adopted, an inkjet printing method that does not require a printing plate can be used, and a general-purpose moving mechanism can be used, which facilitates manufacture.

DESCRIPTION OF SYMBOLS 1, 101, 161 Planar light-emitting device 2 Light source 3 Light guide 3a Lower surface (one surface)
3b Upper surface (the other surface)
4, 105 Light extraction part 4a Minute dot (dot ink layer)
4b Center of minute dots 7 Square lattice 8 Equilateral triangle lattice 8a Lattice points 10, 40, 80, 110, 140, 160 Illumination module 20, 60 Touch pad (detection sensor)
70 Membrane switch (detection sensor)
30 Reflective sheet (reflector)
50 Protective layer 104 Low refractive index layer X Light guide direction (direction in which light is guided)

Claims (6)

1. A light source;
   A sheet-like light guide that is guided in the surface direction by introducing light from the light source,
   A light extraction part that scatters and emits the introduced light from the light source is formed on any one surface (3a, 3b) of the light guide,
   The light extraction portion is composed of a plurality of dot-like ink layers formed by printing,
   The planar light-emitting device, wherein the dot-shaped ink layer has an outer diameter of 10 to 100 μm, a thickness of 0.5 to 10 μm, and contains 5% by mass or more of titanium oxide.
2. 2. The planar light emitting device according to claim 1, wherein the titanium oxide is a rutile type.
3. 3. The planar light emitting device according to claim 1, wherein the plurality of dot-like ink layers are arranged so that a center thereof is located at a lattice point of a regular triangular lattice.
4. The planar light emitting device according to claim 1 or 2, wherein the plurality of dot-like ink layers are arranged so that a center thereof is located at a lattice point of a square lattice.
5. An illumination module comprising: the planar light emitting device according to any one of claims 1 to 4; and a touch pad.
6. The illumination module according to claim 5, wherein a reflector that reflects light leakage from the light guide is provided between the light guide and the touch pad.

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