JP2013171664A - Planar light-emitting device, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar light-emitting device capable of preventing deterioration of light utilization efficiency even in case a large-size light source is used.SOLUTION: A planar light-emitting device 10 includes: a substrate 6; a light source 1 installed on a main surface 6a side of the substrate 6; a light guide 2 of a sheet shape in which light from the light source 1 is introduced from an edge part 2a; a detecting sensor 3 which is installed on an inner face 2c side of the light guide 2; and a light-shielding member 20 which is installed from an outer surface 2d of the light guide 2 to an outer surface 1b of the light source 1. The outer surface 1b of the light source 1 has a higher height position from the substrate 6 compared with the outer surface 2d of the light guide 2. The light-shielding member 20 has: a base part 24 of which an inner surface 24a is formed along the outer surface 2d of the light guide 2; and a high-position part 26 having an inner face 26a which is located at a position further separated from the substrate 6 compared with the inner surface 24a. An inner surface 26a of the high-position part 26 is opposed to the outer surface 1b of the light source 1.

Description

  The present invention relates to a planar light emitting device suitably used for operation buttons, key buttons, and the like of a mobile phone, a personal digital assistant (PDA), a personal computer, and the like, and a method for manufacturing the same.

A planar light emitting device having a function of illuminating operation keys or the like is used for a mobile phone or the like (see, for example, Patent Documents 1 to 3). As the planar light emitting device, there is a structure in which a side light emitting type light source is provided at an edge of a sheet-like light guide.
FIG. 16 shows an example of a planar light emitting device. The planar light emitting device 110 includes a substrate 6, a light source 101, a sheet-like light guide 2 into which light from the light source 101 is introduced, and a sheet switch. 3 and a light shielding member 120.
The sheet switch 3 includes a switch element 7 and a sheet body 8 that covers the switch element 7. The light guide 2 and the sheet body 8 of the sheet switch 3 are bonded to each other by the adhesive material 4.
The light shielding member 120 is a sheet body that prevents light leakage from a gap between the light source 1 and the light guide 2 and has a light shielding property. The light shielding member 120 is provided from the outer surface 2 d of the light guide 2 to the outer surface 101 b of the light source 101.
A keypad 12 having operation keys 11 is provided on the outer surface side (upper surface side) of the planar light emitting device 110.

  Light emitted from the emission surface 101a of the light source 101 and incident on the light guide 2 from the end surface 2b of the introduction edge 2a propagates in the surface direction of the light guide 2 while being reflected by both surfaces of the light guide 2. A part of the light in the light guide 2 is scattered by the light extraction unit 9 and emitted to the outside, whereby, for example, a position corresponding to the operation key 11 is displayed brightly.

JP 2007-53063 A JP 2007-305313 A Japanese Patent Laid-Open No. 2008-60058

In recent years, a planar light emitting device having a large area has been demanded in response to an increase in size of equipment. In order to ensure sufficient brightness even when the area is increased, it has been studied to use a high-brightness light source. High brightness type light sources are generally large.
FIG. 17 shows an example of a planar light emitting device using a large light source 1, and the light source 1 used in the planar light emitting device 110A is used in the planar light emitting device 110 of FIG. The height dimension is larger than that of the light source 101.

In the planar light emitting device 110A, since the outer surface 1b of the light source 1 is located higher than the outer surface 2d of the light guide 2, the light shielding member 120 is bent and deformed in the thickness direction.
For this reason, as shown in FIG. 18, the light shielding member 120 may be peeled off from the outer surface 2d of the light guide 2 by its own elastic repulsive force.
When the light shielding member 120 is peeled off, the light guide 2 in the portion including the introduction edge 2a is peeled off from the sheet switch 3 and the height position is changed. As a result, the light guide 2 is lost due to a loss in the introduction edge 2a. It is conceivable that the light introduction efficiency into the guide 2 is lowered and the light utilization efficiency is lowered.

In order to prevent the light guide 2 from being peeled off from the sheet switch 3, it is effective to increase the width of the adhesive material 4 (W4 in FIG. 17). In this case, the amount of light absorbed by the adhesive material 4 May increase, leading to a decrease in light utilization efficiency.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a planar light emitting device and a method for manufacturing the same that can prevent a decrease in light use efficiency even when a large light source is used.

The present invention relates to a substrate, a light source provided on the main surface side of the substrate, and a sheet-like light guide provided along the substrate, in which light from the light source is introduced from an edge and guided in a plane direction. And a detection sensor provided on the inner surface side which is the substrate side of the light guide, and a position from the outer surface of the light guide to a position facing the outer surface which is the surface opposite to the substrate side of the light source. A light shielding member, and the outer surface of the light source has a height position higher than the outer surface of the light guide, and the light shielding member has an inner surface which is a surface on the substrate side of the light guide. A base portion along the outer surface, and a high position portion having an inner surface at a position farther from the substrate than the inner surface of the base portion,
At least a part of the inner surface of the high position portion provides a planar light emitting device that faces the outer surface of the light source.
The height difference between the inner surface of the high position portion and the inner surface of the base portion can be set equal to or greater than the height difference between the outer surface of the light guide and the outer surface of the light source.
In the present invention, the inner surface of the high position portion and the inner surface of the base portion are formed through a step surface that is inclined with respect to the outer surface of the light guide, and the step surface is such that the light source and the light guide approach each other. It is preferable that the position in the separating direction is the same position as the edge of the light guide or a position where the distance from the light source is larger than the edge.
In the present invention, it is preferable that at least an outer peripheral portion of the light guide and the detection sensor are bonded with an adhesive material, and the adhesive material is formed at a position away from an edge portion of the light guide.
The inner surface of the light shielding member may have a light reflecting function.
The pressure-sensitive adhesive material preferably has a single-layer structure.

  The present invention provides a method for manufacturing the planar light emitting device, wherein the light shielding member uses the one in which the high position portion is formed in advance.

According to the present invention, since the light shielding member having the high position portion having the inner surface formed at a position higher than the inner surface of the base portion is used, the light shielding is performed even though the outer surface of the light source is higher than the outer surface of the light guide. No bending deformation is applied to the member. For this reason, it can prevent that the light shielding member peels from the outer surface of the light guide by its own elastic repulsive force.
Therefore, since the light guide is not peeled off from the detection sensor and the height position does not change, it is possible to prevent a reduction in luminance of the planar light emitting device due to a reduction in light introduction efficiency into the light guide.

It is sectional drawing which shows the planar light-emitting device which is embodiment of this invention. It is sectional drawing which expanded a part of planar light-emitting device of a previous figure. It is a top view which shows schematic structure of an example of a light guide. It is explanatory drawing which shows an example of the manufacturing method of a light shielding member. It is explanatory drawing following a previous figure. It is explanatory drawing following a previous figure. It is explanatory drawing which shows the manufacturing process of a planar light-emitting device. It is sectional drawing which shows the modification of a light shielding member. It is sectional drawing which shows the other modification of a light shielding member. It is sectional drawing which shows the further another modification of a light shielding member. It is sectional drawing which shows the modification of an adhesive material. It is sectional drawing which shows 2nd Embodiment of a planar light-emitting device. It is sectional drawing which shows an example of the membrane switch which can be used for this invention. It is a graph which shows the relationship between the width | variety of an adhesive material, and a brightness | luminance. It is a figure which shows the luminance distribution of a light guide. It is sectional drawing which shows an example of a planar light-emitting device. It is sectional drawing which shows the other example of a planar light-emitting device. It is sectional drawing which shows the planar light-emitting device of a previous figure.

Embodiments of the planar light emitting device according to the present invention will be described below.
(First embodiment)
FIG. 1 is a cross-sectional view showing a part of a planar light emitting device 10 according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a part of the planar light emitting device 10. FIG. 3 is a plan view showing an overall schematic configuration of an example of the light guide 2. In the following description, the height direction is the upper side in FIG. 1 and FIG. 2 (the direction away from the substrate 6).

As shown in FIG. 1, a planar light emitting device 10 (sensor device) includes a substrate 6, a light source 1, a sheet-like light guide 2 (light guide) into which light from the light source 1 is introduced, and a light guide. 2 is provided with a sheet switch 3 (detection sensor) disposed on the inner surface 2c (one surface) side, and a light blocking member 20 for preventing light leakage from a gap portion between the light source 1 and the light guide 2.
A keypad 12 having a plurality of operation keys 11 is provided on the outer surface side (upper surface side) of the planar light emitting device 10. The keypad 12 and the planar light emitting device 10 constitute a key switch module.

As the light source 1, a light emitting element such as a light emitting diode (LED) or a light emitter such as a cold cathode tube is used. For example, the light source 1 may have a configuration in which a light emitting element chip is built in a case, and light emitted from the light emitting element chip is emitted from an emission surface 1a on the side surface of the case. In the illustrated example, the light source 1 faces the end surface 2 b of the introduction edge 2 a of the light guide 2 with the emission surface 1 a directed to the side.
The light source 1 is connected to an electric circuit (not shown) formed on the main surface 6a (upper surface in FIG. 1; one surface of the substrate) of the substrate 6 by solder or the like.

The material constituting the light guide 2 is not particularly limited as long as it has optical transparency and can be deformed, but acrylic resin, urethane resin, polycarbonate resin, silicone resin (silicone resin). Any one selected from the group consisting of polystyrene resin, polyimide resin, polymethyl methacrylate (polymethyl methacrylate, PMMA) elastomer, and urethane acrylate is preferable.
In particular, acrylic resins and urethane resins are less susceptible to damage because of their elasticity, and are excellent in terms of durability.

The planar view shape of the light guide 2 is not particularly limited, and may be a substantially rectangular shape as shown in FIG. 3 or other shapes. The thickness of the light guide 2 is not particularly limited, and can be, for example, 0.01 to 10 mm, preferably 0.1 to 1 mm.
As shown in FIG. 1, the end surface 2 b of the introduction edge 2 a of the light guide 2 is located at a position separated from the emission surface 1 a of the light source 1. The end face 2b is preferably in a position close to the emission face 1a of the light source 1.
The light guide 2 is provided along the substrate 6. In FIG. 1, the light guide 2 is provided in parallel to the substrate 6.
The inner surface 2c of the light guide 2 is a surface on the substrate 6 side, which is the lower surface in FIG.

The substrate 6 is a printed wiring board such as a PCB (Printed Circuit Board) or an FPC (Flexible Printed Circuit).
The sheet switch 3 includes one or more switch elements 7 provided on the main surface 6 a of the substrate 6 and a sheet body 8 that covers the switch elements 7.
The switch element 7 includes a central contact portion 21 provided on the main surface 6 a of the substrate 6, a peripheral contact portion 22 provided on the outer peripheral side of the central contact portion 21, and a dome-shaped metal plate 23. The central portion of the metal plate 23 can be contacted / separated with respect to the central contact portion 21, and the central portion is elastically deformed downward and pressed against the central contact portion 21 by pressing by an operator, and The contact portion 22 can be conducted.

The sheet body 8 is made of a resin material such as PET (polyethylene terephthalate). An adhesive layer 17 made of acrylic resin, silicone resin (silicone resin) or the like is formed on the lower surface 8b side (surface on the substrate 6 side) of the sheet body 8.
A spacer 18 made of a resin material such as PET is interposed between the adhesive layer 17 and the main surface 6 a of the substrate 6. An adhesive layer 19 made of acrylic resin, silicone resin (silicone resin) or the like is formed on the lower surface side of the spacer 18. The spacer 18 is formed at a position where it does not interfere with the switch element 7.
The sheet body 8 is bonded to the main surface 6 a of the substrate 6 through the spacer 18 by the adhesive layers 17 and 19. Reference numeral 8 a denotes an outer edge portion of the sheet body 8.

The sheet switch 3 is provided on the inner surface 2 c side of the light guide 2, that is, between the light guide 2 and the substrate 6.
In the illustrated example, the sheet switch 3 corresponds to a “detection sensor”. However, in the present invention, the sheet switch 3 and the substrate 6 may be used as a “detection sensor”. In this case, the sheet switch 3 is a “detection sensor body”.

The sheet switch 3 is bonded to the light guide 2 via an adhesive material 4 formed between the inner surface 2c (one surface) of the light guide 2 and the upper surface 8c of the sheet body 8.
The adhesive 4 is in contact with the inner surface 2c of the light guide 2 and the upper surface 8c of the sheet body 8, and bonds them together.
The adhesive material 4 may have a three-layer structure in which an adhesive layer is formed on both surfaces of a transparent resin base material as a support material, or a one-layer structure (single layer structure) (homogeneous structure). However, a one-layer structure (single-layer structure) is preferable.

The adhesive material 4 having a single layer structure (single layer structure) does not use a base material, and is entirely formed of an adhesive material. The adhesive material 4 is preferably formed uniformly from one type of adhesive material.
Examples of such adhesive materials include acrylic resins, silicone resins (silicon resins), polyurethane resins, epoxy resins, natural rubber adhesives, and synthetic rubber adhesives.

By making the adhesive material 4 have a one-layer structure, light absorption in the adhesive material 4 can be reduced and the luminance of the planar light emitting device 10 can be improved as compared with the case where a three-layer adhesive material is used. Moreover, it can suppress that the brightness | luminance of the adhesive material 4 becomes high locally by absorption of light.
In addition, when the adhesive material 4 has a single-layer structure, it can be formed by coating, and therefore, the formation of the adhesive material 4 (misalignment, breakage, etc.) is less likely to occur than when the adhesive material is manually installed. Therefore, the manufacturing yield can be improved and the manufacturing cost can be reduced. Moreover, since a base material is not used, it is possible to form thinly without reducing adhesive force.

The adhesive material 4 may be transparent or opaque. The pressure-sensitive adhesive material 4 may be colorless, but a material exhibiting any color such as black or white can also be used.
When the pressure-sensitive adhesive material 4 exhibiting black is used, it is easy to absorb light, so that a phenomenon in which the luminance of the pressure-sensitive adhesive material 4 formation portion is locally high is less likely to occur, and a highly uniform luminance distribution is obtained. In order to color the adhesive material 4 in black, the adhesive material 4 may contain a black pigment (pigment or dye). Examples of black pigments include carbon black.

In order to obtain a uniform luminance distribution, it is also effective to give the adhesive material 4 a light reflecting function, that is, a function of reflecting light from the outside.
For example, the light reflecting function can be imparted to the adhesive material 4 by adding a filler containing a metal such as aluminum powder or silver powder to the adhesive material. By providing the adhesive material 4 with a light reflection function, light absorption in the adhesive material 4 can be reduced, and a highly uniform luminance distribution can be obtained.

Moreover, by making the refractive index of the adhesive material 4 lower than the refractive index of the light guide 2, light absorption in the adhesive material 4 can be suppressed, and the uniformity of the luminance distribution can be improved. Examples of the material for the low refractive index adhesive material 4 include acrylic resins and silicone resins (silicon resins).
Moreover, the refractive index of the adhesive material 4 can also be adjusted by adding the material which has the effect | action which reduces a refractive index to an adhesive material. Examples of the material having a function of reducing the refractive index include a silicone filler (silicon filler) and the like, and the refractive index of the adhesive material 4 can be lowered by adding this to the adhesive material, for example, an acrylic resin.
The refractive index difference (a value obtained by subtracting the refractive index of the adhesive material from the refractive index of the light guide) is preferably 0.05 or more. By making the refractive index difference within this range, absorption of light can be prevented and a more uniform luminance distribution can be obtained.
Further, an adhesive material having both the light reflecting function and a refractive index lower than that of the light guide 2 can be used.

  The thickness of the adhesive material 4 is not particularly limited, but 0.1 mm or less is preferable in that the surface light emitting device 10 is thinned. The thickness of the adhesive material 4 can be 0.01-0.1 mm, for example.

As shown in FIG. 3, the adhesive material 4 can be formed on at least the outer peripheral portion 13 of the light guide 2. For example, it can be formed in a substantially rectangular frame shape along the four side portions 14 (outer peripheral portion 13) of the light guide 2 having a rectangular shape in plan view shown in FIG. The width | variety (for example, W1 of FIG. 2) of the adhesive material 4 can be 0.5-1 mm, for example.
The adhesive material 4 may be formed not only on the outer peripheral portion 13 but also on other portions. Further, it may be formed only on a part of the outer peripheral portion 13.

  As shown in FIG. 1, the adhesive material 4 can be formed in a plan view region including an introduction edge 2 a into which light from the light source 1 is introduced. That is, the outer edge portion 4a of the adhesive material 4 can be formed to reach the introduction edge portion 2a in plan view. In FIG. 1, since the position of the outer edge 4a of the adhesive material 4 in the left-right direction coincides with the position of the introduction edge 2a in the left-right direction, the outer edge 4a reaches the introduction edge 2a in plan view.

  As shown in FIG. 1, a light extraction portion 9 is formed on the inner surface 2 c (surface on the sheet switch 3 side) of the light guide 2 at a predetermined position corresponding to the operation key 11, for example. The light extraction portion 9 can be formed on one or both surfaces of the light guide 2.

The light extraction unit 9 can be a plurality of microdot-like ink layers (hereinafter simply referred to as microdots) formed by printing, for example. 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.
As the ink constituting the fine dots, for example, white ink using titanium oxide as a pigment is suitable. The light extraction part may be a notch formed on the surface of the light guide 2 or a rough surface part formed by sandblasting or the like.
The outer surface 2d of the light guide 2 (upper surface in FIG. 1, the surface opposite to the substrate side) is the upper surface (surface, light emitting surface) of the planar light emitting device 10.

  The light extraction portion 9 is preferably formed in a region where the adhesive material 4 is not present. In the example shown in FIG. 1, the light extraction portion 9 is formed on the right side of the adhesive material 4.

  When light from the light source 1 enters the light guide 2 from the end surface 2b of the introduction edge 2a, the incident light L1 propagates through the light guide 2 while being repeatedly reflected between the inner surface 2c and the outer surface 2d of the light guide 2. . A part of the light L1 in the light guide 2 is scattered by the light extraction unit 9 and leaks to the outside as scattered light L2. Thereby, light can be emitted outside from the region where the light extraction portion 9 is formed, for example, the region corresponding to the operation key 11.

As shown in FIGS. 1 and 2, the light shielding member 20 is a sheet body having a light shielding property, and is formed from the outer surface 2 d of the light guide 2 to the outer surface 1 b of the light source 1 (the surface opposite to the substrate 6 side. (Upper surface).
The light shielding member 20 is made of a material having a light shielding property. For example, a resin such as polyurethane resin, polycarbonate resin, silicone resin (silicon resin), polystyrene resin, or various metal materials may be used. May be used.
In order to improve the light-shielding property, pigments can be contained in these materials, or a paint can be applied to the surface of a sheet made of these materials.
The color of the light shielding member 20 is not particularly limited as long as it has sufficient light shielding properties, and may be white having high reflectivity or black having high light absorption.

The light shielding member 20 can also be provided with a light reflecting function. For example, the reflective layer can be formed by vapor-depositing or applying a material containing metal such as aluminum or silver on the inner surface 20a of the light shielding member 20. Further, by forming the light shielding member 20 from a metal such as aluminum or silver, the light shielding member 20 can be provided with a light reflecting function.
By providing the light shielding member 20, light can be prevented from leaking from the gap between the light source 1 and the light guide 2, and the luminance distribution of the planar light emitting device 10 can be made uniform.
The inner surface 20 a on which the reflective layer is provided is the inner surface 24 a of the base portion 24 and the inner surface 25 a of the protruding portion 25. Reference numeral 20 b in FIG. 2 is an outer surface of the light shielding member 20.

The light blocking member 20 includes a flat plate-like base portion 24 that extends along the outer surface 2d of the light guide 2 and a protruding portion 25 that protrudes upward (in a direction away from the substrate 6) from the base portion 24.
An inner surface 24 a (surface on the substrate 6 side) of the base portion 24 is in contact with the outer surface 2 d of the light guide 2. The inner surface 24a is preferably bonded to the outer surface 2d. 1 and 2, the inner surface 24 a is parallel to the main surface 6 a of the substrate 6.

The protruding portion 25 includes a top plate portion 26 (high position portion) and a stepped portion 27 that hangs down from the periphery thereof.
The top plate portion 26 is formed in a flat plate shape, and is provided in parallel with the substrate 6 in FIG. The inner surface 26 a (the lower surface in FIG. 1) of the top plate portion 26 faces the outer surface 1 b of the light source 1. In FIG. 1, the center part of the inner surface 26a is in contact with the outer surface 1b.
The inner surface 26 a of the top plate portion 26 is at a higher position (a position farther from the substrate 6) than the inner surface 24 a of the base portion 24.
In FIG. 1, only the central portion of the inner surface 26a faces the outer surface 1b, but the entire inner surface 26a may face the outer surface 1b. Further, in FIG. 1, the projecting portion 25 has stepped portions 27 formed on the left and right edges of the top plate portion 26, but the stepped portion 27 may be formed only on one edge portion of the topplate portion 26. Good. That is, the projecting portion may have an L-shaped structure including a top plate portion and a step portion depending from one edge portion thereof.

On the inner surface 25 a side of the protruding portion 25, an accommodation recess 28 is formed that is recessed in the height direction with respect to the inner surface 24 a of the base portion 24.
The housing recess 28 is a recess composed of the inner surface 26 a of the top plate portion 26 and the inner surface (step surface 27 a) of the step portion 27, and preferably accommodates at least a part of the light source 1. 1 and 2, the upper part of the light source 1 is accommodated in the accommodating recess 28.
In this example, since the inner surface 26a is in contact with the outer surface 1b, the dimension (H1 in FIG. 2) in the height direction (vertical direction in FIGS. 1 and 2) of the receiving recess 28 (the inner surface of the high position portion and the base portion) The height difference between the outer surface and the inner surface is substantially equal to the protruding dimension of the outer surface 1b of the light source 1 relative to the outer surface 2d ("H2-H3" in FIG. 2) (the difference in height between the outer surface of the light guide and the outer surface of the light source). The shape of the light shielding member 20 is stable because the top plate portion 26 is supported by contacting (or close to) the light source 1.
2, H2 is the height of the outer surface 1b of the light source 1 from the surface on which the substrate 6 is installed, and H3 is the height of the outer surface 2d of the light guide 2 from the surface on which the substrate 6 is installed. is there.

A step surface 27a which is an inner surface (left surface in FIG. 2) of the step portion 27 is formed along the thickness direction of the substrate 6 (vertical direction in FIG. 2). The step surface 27a shown in FIG. 2 is a surface perpendicular to the outer surface 2d of the light guide 2. However, the present invention is not limited to this, and any surface that is inclined with respect to the outer surface 2d of the light guide 2 may be used.
For example, it may be an inclined surface that is inclined so as to rise as it approaches the top plate portion 26, and has an angle with respect to the outer surface 2d of more than 0 ° and less than 90 °. Note that “inclined with respect to the outer surface 2d” includes a case of being perpendicular to the outer surface 2d.

In FIG. 1 and FIG. 2, an inner surface 26a parallel to the main surface 6a of the substrate 6 and an inner surface 24a are formed continuously through a step surface 27a.
In this example, the position of the step surface 27 a in the left-right direction coincides with the position of the introduction edge 2 a of the light guide 2 in the left-right direction. In this figure, the left-right direction is a direction in which the light source 1 and the light guide 2 approach and separate from each other.

Next, an example of a method for manufacturing the light shielding member 20 will be described with reference to FIGS.
As shown in FIG. 4, a mold 60 having an inner surface side mold 61 and an outer surface side mold 62 is prepared.
The inner surface side mold 61 has an inner surface shape corresponding to the inner surface 20 a of the light shielding member 20. That is, the inner surface 61 a of the inner surface side mold 61 has a base portion forming surface 63 corresponding to the inner surface 24 a of the base portion 24, and an accommodating recess forming convex portion 64 that is formed to protrude from the base portion forming surface 63.
The housing recess forming convex portion 64 forms the housing concave portion 28 on the inner surface 20 a of the light shielding member 20, and is a convex portion having a shape corresponding to the inner surface of the housing concave portion 28.

The outer surface side mold 62 has an inner surface shape corresponding to the outer surface 20 b of the light shielding member 20. That is, the inner surface 62 a of the outer surface side mold 62 has a base portion forming surface 65 corresponding to the outer surface 24 b of the base portion 24, and a protruding portion forming concave portion 66 formed in a concave shape with respect to the base portion forming surface 65.
The protruding portion forming recess 66 forms the protruding portion 25 on the outer surface 20 b of the light shielding member 20, and is a recess having a shape conforming to the outer surface of the protruding portion 25.

As shown in FIG. 4, a flat light shielding member 20 </ b> A is disposed between the inner surface side mold 61 and the outer surface side mold 62.
Next, as shown in FIGS. 5 and 6, the light shielding member 20 </ b> A is sandwiched from above and below by the inner surface side mold 61 and the outer surface side mold 62, and protruded by pressing in the thickness direction by the housing recess forming convex portion 64. A portion 25 is formed.
The protruding portion 25 has a structure formed by plastically deforming the light shielding member 20A, and even when released from the pressing by the molds 61 and 62, the protruding portion 25 does not return to the original flat plate shape, and the shape is maintained.
The light shielding member 20 is not limited to the method of press-molding the flat light shielding member 20 </ b> A, and the light shielding member 20 is cured by pouring a resin material between the inner surface side mold 61 and the outer surface side mold 62. It may be formed.

  Next, as illustrated in FIG. 7, the planar light emitting device 10 illustrated in FIGS. 1 and 2 is obtained by installing the light shielding member 20 having the protruding portion 25 from the outer surface 2 d of the light guide 2 to the outer surface 1 b of the light source 1. .

In the planar light emitting device 10, since the light shielding member 20 having the housing recess 28 is used, the light shielding member 20 is bent and deformed even though the outer surface 1 b of the light source 1 is higher than the outer surface 2 d of the light guide 2. It is never added. For this reason, it can prevent that the light-shielding member 20 peels from the outer surface 2d of the light guide 2 by own elastic repulsive force.
Therefore, the light guide 2 is not peeled off from the sheet switch 3 and the height position does not fluctuate, and it is possible to prevent a decrease in light use efficiency due to a decrease in light introduction efficiency into the light guide 2. Accordingly, it is possible to prevent the luminance of the planar light emitting device 10 from decreasing.

About the reason which can prevent a brightness fall by using the light shielding member 20 which has the accommodation recessed part 28, the following estimation is possible.
As shown in FIG. 18, when the light shielding member 120 without the housing recess 28 is used, minute peeling from the light guide 2 occurs due to the elastic repulsive force of the light shielding member 120, and the peeled portion 120 a and the light guide are separated. The space 121 is formed between the outer surface 2d of the two and light absorption or leakage occurs in the space 121, so that the light use efficiency may be reduced.
On the other hand, as shown in FIG. 2, when the light shielding member 20 having the accommodating recess 28 is used, no deformation occurs because no force in the thickness direction is applied to the light shielding member 20. For this reason, peeling from the light guide 2 does not occur, and the light utilization efficiency does not decrease.
It is considered that this can prevent a decrease in luminance.

8 and 9 show a modification of the light shielding member 20. The light shielding members 20A and 20B are different from the light shielding member 20 shown in FIGS. 1 and 2 in the position of the step surface 27a in the left-right direction.
The stepped surface 27a of the light shielding member 20A shown in FIG. 8 is at a position where the distance from the light source 1 is larger than the introduction edge 2a of the light guide 2 with respect to the position in the left-right direction. That is, in FIG. 8, the step surface 27a is on the right side compared to the introduction edge 2a.
In this light shielding member 20A, since the step surface 27a is on the right side of the introduction edge 2a, part of the light L3 reflected by the step surface 27a is introduced into the light guide 2 from the outer surface 2d and used. Therefore, as in the light shielding member 20B shown in FIG. 9, the light use efficiency can be increased compared to the case where the stepped surface 27a is on the left side compared to the introduction edge 2a of the light guide 2.

FIG. 10 shows another modification of the light shielding member 20. In the light shielding member 20C of this example, the inner surface 26a of the top plate portion 26 is located at a position higher than the outer surface 1b of the light source 1 and is spaced from the outer surface 1b. It faces the outer surface 1b.
In this example, since the inner surface 26a is at a position higher than the outer surface 1b, the dimension (the height difference between the inner surface of the high position portion and the inner surface of the base portion) in the height direction (vertical direction in FIG. 10) of the housing recess 28 is It is larger than the protruding dimension in the height direction of the outer surface 1b of the light source 1 with respect to 2d (the difference in height between the outer surface of the light guide and the outer surface of the light source). Since the accommodating recess 28 has a sufficient height, the upper portion of the light source 1 can be reliably accommodated even if the height dimension of the light source 1 varies.

FIG. 11 shows a modification of the adhesive material 4, and the adhesive material 4 (4 </ b> A) of this example is formed at a position away from the introduction edge 2 a where the light from the light source 1 is introduced.
That is, the adhesive material 4 is formed inward (rightward in FIG. 11) from the introduction edge 2a of the light guide 2 by a distance W2. The distance W2 from the introduction edge 2a of the adhesive material 4 (the distance in the left-right direction between the introduction edge 2a and the outer edge 4a of the adhesive material 4) is, for example, 0.1 mm or more (for example, 0.1 to 0.5 mm). can do.
Since the adhesive material 4 is formed away from the introduction edge 2a, the absorption of the light emitted from the light source 1 into the adhesive material 4 can be reduced, and the introduction efficiency to the light guide 2 can be increased. Therefore, the brightness of the planar light emitting device 10 can be increased.
Further, since it is possible to enter the light guide 2 from the region (region 2f in FIG. 11) of the surface 2c of the light guide 2 from the introduction edge 2a to the outer edge 4a of the adhesive material 4, the light guide 2 can be incident on the light guide 2. The light introduction efficiency can be further increased.

Since the adhesive material 4 in this example does not reach the introduction edge 2a, light scattering at the introduction edge 2a can be suppressed and the luminance of the planar light emitting device 10 can be improved.
Further, the adhesive material 4 may absorb moisture and soften easily in a high humidity environment. However, if the adhesive material 4 is formed away from the introduction edge 2a, it is introduced even if the adhesive material 4 is fluidized. It does not reach the edge 2a. For this reason, it can prevent that the introduction efficiency of the light to the light guide 2 falls by the adhesive material 4 adhering to the end surface 2b.
When the pressure-sensitive adhesive 4 contains a water-soluble material (especially when the pressure-sensitive adhesive 4 has a single-layer structure), moisture absorption is likely to occur, so this structure is more effective.

(Second Embodiment)
FIG. 12 is a cross-sectional view showing a part of a planar light emitting device 40 according to the second embodiment of the present invention.
The planar light emitting device 40 is different from the planar light emitting device 10 shown in FIG. 1 in that a touch pad 30 (detection sensor) is used instead of the sheet switch 3.
The touch pad 30 includes an input sensor 31 and a resist layer 32 (covering resin layer) formed on one surface thereof.
The input sensor 31 is a sensor that detects the proximity or contact of a detection target such as a human finger. Here, the input sensor 31 is a capacitance type input sensor, and includes a wiring layer 34 provided on the main surface 33 a of the base material 33. Since the capacitance type input sensor 31 has a simple structure, it can be thinned.

  The base material 33 is a plate material made of a resin such as PET. The base material 33 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 34 has, for example, a plurality of electrodes 34a. Since the electrostatic capacitance between the detected object such as a human finger and the electrode 34a varies depending on the facing area and the separation distance between the detected object and the electrode 34a, the detected object and the electrode 34a are variable capacitance units. Form.
A change in the capacitance of the variable capacitance unit is detected by a detection means (not shown), and an input operation by the detection target, its position, and the like are grasped by a control unit (not shown) based on the detected value.

The wiring layer 34 can be formed, for example, by heating a silver paste containing silver particles after screen printing on the substrate 33. The wiring layer 34 may be formed by etching a copper foil laminated on the base material 33.
The resist layer 32 secures electrical insulation between the wiring layers 34 and prevents oxidation. The base layer 33 and the wiring layer 34 are disposed on one surface (the surface on the light guide 2 side) of the input sensor 31. Covered and formed. For example, a general-purpose solder resist can be used as the resist layer 32.

  In the illustrated example, the touch pad 30 corresponds to a “detection sensor”. However, in the present invention, the touch pad 30 and the substrate 33 may be used as a “detection sensor”. In this case, the touch pad 30 is a “detection sensor body”.

(Third embodiment)
In the present invention, a pressure-sensitive membrane switch (detection sensor) can be used instead of the sheet switch 3.
FIG. 13 shows an example of a membrane switch. In this membrane switch 50, an upper substrate 51 is provided on a lower substrate 52 having a lower electrode 54 formed on an opposing surface 52a, and the opposing surface 51a of the upper substrate 51 is provided. An upper electrode 53 is formed on the upper surface. The substrates 51 and 52 are separated from each other by a spacer 55.

The substrates 51 and 52 and the spacer 55 are made of a resin such as PET. The electrodes 53 and 54 can be formed by, for example, silver paste.
The upper surface 51b of the upper substrate 51 is bonded to a light guide (not shown) by an adhesive material (not shown).
In the membrane switch 50, when the upper substrate 51 is bent by the pressure of the detection target (human finger or the like), the upper electrode 53 comes into contact with the lower electrode 54, and these are conducted to detect an input operation or the like.

  In the illustrated example, the membrane switch 50 corresponds to a “detection sensor”. However, in the present invention, the membrane switch 50 and the lower substrate 52 may be used as a “detection sensor”. In this case, the membrane switch 50 is a “detection sensor body”.

Example 1
As shown in FIGS. 1 and 2, a planar light emitting device 10 using a light shielding member 20 having a housing recess 28 was produced.
The height H2 (see FIG. 2) of the outer surface 1b of the light source 1 from the surface on which the substrate 6 is installed is 300 μm, and the height H3 (see FIG. 2) of the outer surface 2d of the light guide 2 is 253 μm. The thickness of the light guide 2 is 100 μm. The dimension H1 in the height direction of the housing recess 28 was 100 μm.

The planar light emitting device 10 was subjected to the environmental test shown below.
The sample was placed in a high temperature condition (85 ° C.) for 200 hours and then placed in a low temperature condition (−40 ° C.) for 120 hours before being subjected to a thermal shock test. The thermal shock test is a test in which a cycle composed of a high temperature condition (85 ° C.) and a low temperature condition (−40 ° C.) (10 minutes each) is repeated 640 times.
The sample was then subjected to a temperature and humidity test. The temperature and humidity test is a test in which a cycle consisting of a high temperature condition (55 ° C.) and a low temperature condition (25 ° C.) (each 9 hours) is repeated six times under high humidity conditions (humidity 95%).
When the width of the adhesive material 4 (W1 in FIG. 2) was 0.3 to 1.0 mm, the presence or absence of peeling of the light guide 2 from the sheet switch 3 was examined. The results are shown in Table 1.

(Comparative Example 1)
As shown in FIG. 17, the same test as in Example 1 was performed using the planar light emitting device 110 </ b> A similar to that in Example 1 except that the light shielding member 120 without the housing recess 28 was used. The results are also shown in Table 1.

As shown in Table 1, in order to prevent the light guide 2 from peeling off in Comparative Example 1, it was necessary to set the width of the adhesive material 4 to 0.8 mm or more, whereas in Example 1, the adhesive material 4 Even when the width was 0.4 mm, the light guide 2 did not peel off.
FIG. 14 is a graph showing the relationship between the width of the adhesive material 4 and the luminance in the planar light emitting device 110A (see FIG. 17). The luminance here is an average of the light emitting areas 29 (25 locations in total) surrounded by a broken line in the luminance distribution of the light guide 2 shown in FIG. As shown in FIG. 14, when the width of the adhesive material 4 is reduced, the absorption of light in the adhesive material 4 can be reduced, so that the luminance tends to increase.
Based on the relationship between the width of the adhesive material 4 and the luminance shown in FIG. 14, when the width of the adhesive material 4 is set to 0.4 mm, the width of the adhesive material 4 is about 10 mm as compared with the case where the width of the adhesive material 4 is set to 0.8 mm. % Luminance can be improved.

(Example 2)
For the planar light emitting device 10 having the same configuration as in Example 1 (however, the width of the adhesive material 4 is 0.8 mm), the average, maximum value, minimum value of the light emitting regions 29 (25 in total) (see FIG. 15), and “Minimum value / maximum value” was examined. The results are shown in Table 2. “Minimum value / maximum value” is an index of luminance uniformity. The higher this value, the higher the uniformity.

(Comparative Example 2)
The same test as in Example 2 was performed on the planar light emitting device 110A having the same configuration as that of Comparative Example 1 (however, the width of the adhesive material 4 was 0.8 mm). The results are also shown in Table 2.

  As shown in Table 2, in Example 1 using the light shielding member 20 having the accommodating recess 28, an improvement in luminance of about 5% in average value was confirmed as compared with Comparative Example 1.

In addition, this invention is not limited to the above-mentioned embodiment, A various change is possible in the range which does not deviate from the summary of this invention. For example, the light shielding member 20 shown in FIG. 1 and the like has a protruding portion 25, and the inner surface side of the protruding portion 25 is a housing recess 28, but the light shielding member has a structure in which the outer surface is flat and the inner surface has a recess. There may be.

DESCRIPTION OF SYMBOLS 1 ... Light source, 1b ... Outer surface of light source, 2 ... Light guide, 2a ... Introduction edge part (edge part of light guide of the part into which the light from a light source is introduced), 2c ... Inner surface of light guide, 2d ... Outer surface of light guide, 3 ... Sheet switch (detection sensor), 4 ... Adhesive material, 6 ... Substrate, 6a ... Main surface, 10, 40 ... A planar light emitting device, 20 ... a light shielding member, 20a ... an inner surface of the light shielding member, 24 ... a base portion, 24a ... an inner surface of the base portion, 26 ... a top plate portion (high position portion), 26a ... Inner surface of top plate part, 27a ... Step surface, 30 ... Touch pad (detection sensor), 50 ... Membrane switch (detection sensor), H1 ... Dimension in height direction of receiving recess (Difference in height between the high position part and the base part).

Claims (7)

A substrate,
A light source provided on the main surface side of the substrate;
A sheet-like light guide that is provided along the substrate and in which light from the light source is introduced from an edge and guided in a plane direction;
A detection sensor provided on the inner surface side which is the substrate side of the light guide;
A light shielding member provided from the outer surface of the light guide to a position facing the outer surface, which is the surface opposite to the substrate side of the light source,
The outer surface of the light source is higher in height from the substrate than the outer surface of the light guide,
The light shielding member has a base portion whose inner surface which is a surface on the substrate side is along the outer surface of the light guide, and a high position portion which has an inner surface which is located farther from the substrate than the inner surface of the base portion,
At least a part of the inner surface of the high position portion is opposed to the outer surface of the light source.   The height difference between the inner surface of the high position portion and the inner surface of the base portion is equal to or greater than the height difference between the outer surface of the light guide and the outer surface of the light source. Planar light emitting device. The inner surface of the high position portion and the inner surface of the base portion are formed through a step surface that is inclined with respect to the outer surface of the light guide,
The step surface is a position in a direction in which the light source and the light guide approach and separate from each other at the same position as the edge of the light guide or a position where the distance from the light source is larger than the edge. The planar light-emitting device according to claim 1 or 2. At least the outer periphery of the light guide and the detection sensor are bonded with an adhesive material,
The planar light emitting device according to any one of claims 1 to 3, wherein the adhesive material is formed at a position away from an edge of the light guide.   The planar light-emitting device according to claim 1, wherein an inner surface of the light shielding member has a light reflecting function.   The planar light-emitting device according to claim 1, wherein the adhesive material has a single-layer structure. It is a manufacturing method of the planar light-emitting device of any one of Claims 1-6,
A method of manufacturing a planar light emitting device, wherein the light shielding member is formed with the high position portion formed in advance.