JP2012216555A - Light-emitting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin light-emitting source with a small volume which can show a light source larger than an actual size.SOLUTION: The light-emitting structure is composed of a light-emitting film incorporating a light-emitting element which has a plurality of pieces of heat resistant films with a conductive part formed on the front surface, a plurality of light-emitting elements to be jointed to the conductive part, an underlayer film to which a plurality of pieces of heat resistant films are pasted, and a diffraction grating film which is incorporated with an interval from the light-emitting element on a light-emitting face side of the light-emitting elements of the light-emitting film incorporating the light-emitting elements. The underlayer film has an inferior heat resistance to the heat resistant films.

Description

  The present invention relates to a light emitting material in which a diffraction grating film is assembled to a light emitting film in which a light emitting element is incorporated.

  In recent years, light emitting diodes (LEDs) have been used as alternatives to light sources such as light bulbs, fluorescent lamps, and cathode ray tubes. The light-emitting diode has a lifetime of 50,000 hours or more (half-life) and is therefore suitable for a light source used for a long time. In addition, it has advantages such as low power and low heat generation compared with a light bulb or the like.

  A light source substrate that emits light in a planar shape using a light emitting diode includes a structure in which a plurality of light emitting diodes are arranged with a lead frame on a hard substrate and bonded with solder. Resin, aluminum, or the like is used for the hard substrate. As the light emitting diode, a so-called cannonball type is used.

  There is also a light source substrate in which a plurality of light emitting diodes are arranged on a flexible substrate. The surface of the flexible substrate is wired with copper foil or the like. By using a flexible substrate as the light source substrate, the degree of freedom of installation location is increased. For example, a PET (Polyethylene terephthalate) film is used as the flexible substrate.

  When a certain number of light sources are caused to emit light, that fixed number of light sources is necessary. In addition, rear combination lamps for automobiles, etc., have a diffraction effect so that the cover can be seen from several times to several tens of times by placing a cover with a diamond cut in an acrylic molded product in front of a light source such as a single light bulb. It is the target. The rear combination lamp is a combination of a lamp (a stop lamp, a tail lamp, a blinker lamp, a vehicle width lamp, etc.) as a light source and a cover (lens) at the rear of an automobile or the like. However, there is a drawback that the volume of the rear combination lamp is increased depending on the distance from the light source to the cover and the shape of the light source itself such as a light bulb. Therefore, when attaching to the rear part of a motor vehicle, there is a problem that a trunk becomes narrow.

Japanese Patent Laid-Open No. 9-274455

  An object of the present invention is to provide a thin light-emitting source having a small volume, which makes the light source appear larger than its actual size.

The present invention employs the following means in order to solve the above problems.
That is, the aspect of the present invention is
A plurality of heat-resistant films having conductive portions formed on the surface;
A plurality of light emitting elements bonded to the conductive portion;
A base film to which the plurality of heat-resistant films are attached;
A light-emitting element built-in light-emitting film comprising:
A diffraction grating film assembled at a predetermined interval from the light emitting element on the light emitting surface side of the light emitting element of the light emitting element built-in light emitting film,
A light emitting structure comprising:

  According to the present invention, when the light emitted from the light emitting element is viewed through the diffraction grating, the light appears as a plurality of lights.

  ADVANTAGE OF THE INVENTION According to this invention, it is a thin light emission source with a small volume, Comprising: The thin light emission source which makes a light source appear larger than an actual magnitude | size can be provided.

It is sectional drawing of the light emitting diode built-in light emitting film in embodiment of this invention. It is a figure which shows the wiring pattern of the light emitting diode built-in light emitting film in embodiment of this invention. It is the figure which has arrange | positioned the light emitting diode to the wiring pattern of FIG. 1 shows a circuit diagram of an embodiment of the present invention. The top view of the light emitting diode built-in light emitting film in embodiment of this invention is shown. It is a figure which shows the modification of the wiring pattern which has arrange | positioned the light emitting diode shown in FIG. It is a figure which shows the manufacturing method of the light emitting diode built-in light emitting film in embodiment of this invention. It is a figure which shows the cross section of the diffraction grating film concerning embodiment of this invention. It is a figure which shows the pattern (arrangement | positioning) of the diffraction grating in a diffraction grating film. It is a figure which shows the modification of the pattern of the diffraction grating shown in FIG. It is a figure which shows the modification of the pattern of the diffraction grating shown in FIG. It is a figure explaining the manufacturing method of the diffraction grating film concerning embodiment of this invention. It is a figure which shows the cross section of the light emitting structure concerning embodiment of this invention. It is a figure explaining the conditions of interference of diffracted light. It is a figure which illustrates the position where the light of a light emitting diode interferes with a diffracted light on a diffraction grating film. It is a figure which illustrates the position where the light of a light emitting diode interferes with a diffracted light on a diffraction grating film. It is a figure which illustrates the position where the light of a plurality of light emitting diodes interferes on a diffraction grating film. It is a figure which illustrates the position where the light of a plurality of light emitting diodes interferes on a diffraction grating film. It is a figure which illustrates the position where the light of a light emitting diode interferes with a diffracted light on a diffraction grating film. It is a figure which illustrates the position where the light of a plurality of light emitting diodes interferes on a diffraction grating film.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration of the embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.

Embodiment
A light emitting structure according to an embodiment of the present invention includes a light emitting film incorporating a light emitting diode and a diffraction grating film.

(Light-emitting diode built-in light-emitting film)
<Constitution>
FIG. 1 is a view showing a cross section of a light emitting film incorporating a light emitting diode according to an embodiment of the present invention. A plurality of heat-resistant PI (polyimide) films 4 are bonded on a non-heat-resistant PET (polyethylene terephthalate) film 5 (corresponding to the base film of the present invention) as a base film. On the PI film 4, a copper foil as a conductive material is bonded, and a wiring pattern is formed from the copper foil. The light emitting diode 1 is disposed on the copper foil, and each terminal of the light emitting diode 1 and the copper foil are electrically connected by the solder 2. The light emitting diode may be a single color or a white one.

  Instead of the PI film, an organic film such as a PPS (polyphenylene sulfide) film, a heat resistant urethane film, or a liquid crystal polymer film can be used as the heat resistant film. Further, an organic film such as a PP (polypropylene) film, a PE (polyethylene) film, a PS (polystyrene) film, or a PMMA film can be used as the base film instead of the PET film.

  FIG. 2 is a diagram showing a wiring pattern formed of a copper foil on the heat-resistant PI film 4. Two substantially parallel conductive portions 3 are formed on the PI film 4. The interval between the two substantially parallel conductive portions 3 is matched to the interval between the pair of terminals of the light emitting diode 1. On the substantially parallel conductive portion 3, solder 2 is placed at an opposed position at an interval. The light emitting diode 1 is disposed at a position where the solder 2 is placed. A conductive portion 3 for connecting to a power source is further formed at one end of the substantially parallel conductive portion 3. In FIG. 2, among the substantially parallel conductive parts 3, a conductive part 3A connected to the positive electrode of the power source is formed above the left side, and a conductive part connected to the negative electrode of the power source is formed below the right side. 3B is formed. FIG. 3 is a diagram in which the light emitting diodes 1 are arranged in the wiring pattern of FIG. A plurality of light emitting diodes 1 are arranged in one row.

  FIG. 4 is a diagram illustrating an electrical circuit according to the embodiment. A plurality of light emitting diodes 1 are electrically connected in parallel and connected to a power source. By connecting the light emitting diodes 1 in parallel, even if one light emitting diode 1 fails and is disconnected, the light emission of the other light emitting diodes 1 is not affected. In order to cause the light emitting diode 1 to emit light uniformly, an electric resistance or a low voltage device can be connected in parallel with the light emitting diode 1.

  FIG. 5 is a view in which the PI film 4 to which the light emitting diode 1 is bonded is bonded to the PET film 5. The rows of light emitting diodes 1 bonded to the PI film 4 are arranged so as to be substantially parallel to each other. Each PI film 4 in FIG. 5 constitutes the circuit in FIG. For example, the PI film 4 is arranged so that the upper conductive portion 3A on the PI film 4 is a positive electrode and the lower conductive portion 3B is a negative electrode. The electrodes having the same polarity are connected and connected to the power source. At this time, the light emitting diodes 1 are connected in parallel.

<Modification>
FIG. 6 is a diagram showing a modification of the wiring pattern shown in FIG. As shown in FIG. 3, instead of arranging the light emitting diodes 1 in one row on the PI film 4, the light emitting diodes 1 are arranged in a plurality of rows on the PI film 4 in the example of FIG. Even in this arrangement, the light emitting diodes 1 are electrically connected in parallel. Also in this case, in order to cause the light emitting diode 1 to emit light uniformly, an electric resistance or a low voltage device can be connected in parallel with the light emitting diode 1.

<Production method>
With reference to FIG. 7, the manufacturing method of the light emitting diode built-in light emitting film which concerns on embodiment of this invention is demonstrated. The conductive copper foil and the heat-resistant PI film 4 are bonded with an adhesive. The thickness of the copper foil is preferably 4 to 20 μm. As the adhesive, thermoplastic adhesives such as PMMA (Polymethyl methacrylate), polyester, and urethane are used. A wiring pattern as shown in FIG. 2 or the like is formed by etching on the copper foil side of the bonded composite film by a masking method. Solder 2 is attached to the position on the wiring pattern where the light emitting diode 1 is disposed. The solder 2 preferably uses no lead. The light emitting diode 1 is placed on the position where the solder 2 is attached. The light emitting diode 1 is preferably a light emitting diode chip (surface mount type light emitting diode). By using the light emitting diode chip, it can be made thinner than using a bullet-type light emitting diode. If necessary, elements such as electric resistance can be arranged in the same manner. The number and position of the light emitting diodes 1 to be arranged can be freely selected according to the purpose of use. A flux is applied to the terminal of the element such as the light emitting diode 1. By using the flux which is a welding agent, it becomes easy to attach solder.

  The composite film on which the light-emitting diode 1 is mounted is placed in a reflow furnace. When the solder 2 is melted, the conductive portion 3 of the wiring pattern and the light emitting diode 1 are electrically connected. Since the heat resistant PI film 4 is used, the film is not deformed in the reflow furnace. The PI film 4 bonded to the light emitting diode 1 is taken out from the reflow furnace. The PI film 4 and the PET film 5 are joined with an adhesive. Instead of the PET film 5, another general-purpose plastic film can be used. The conductive part 3 of the PI film 4 is appropriately electrically connected to complete the light emitting diode built-in light emitting film.

(Diffraction grating film)
<Constitution>
FIG. 8 is a view showing a cross section of the diffraction grating film according to the embodiment of the present invention. The diffraction grating film includes a PET film 302 as a base film and a plurality of cylindrical PMMA films bonded to the PET film 302.

  FIG. 9 is a diagram showing a diffraction grating pattern (arrangement) in the diffraction grating film 200. As shown in FIG. 9, a cylinder 211 that is a diffraction grating is arranged on a lattice point of a square lattice. The diameter of the cylinder is preferably about 0.1 μm or more and about 10 μm or less. Further, the height of the cylinder is preferably about 1.0 to about 1.5 times the diameter of the cylinder. The distance between the center of the cylinder and the center of the cylinder adjacent to the cylinder is preferably about 2.5 times or less the diameter of the cylinder. This distance is the grating interval (period) of the diffraction grating.

  FIG. 10 is a diagram showing a modification of the pattern of the diffraction grating shown in FIG. As shown in FIG. 9, instead of arranging the cylinders on the lattice points of the square lattice, in the example of FIG. 10, the cylinders are arranged on the lattice points of the triangular lattice. By arranging in this way, it is expected that diffracted light appears in a direction different from the case of a square lattice.

  FIG. 11 is a diagram showing a modification of the diffraction grating pattern shown in FIG. As shown in FIG. 9, a square column is used instead of a column. In addition to this, instead of a cylindrical circle, the cross section may be a closed curve such as an ellipse, a triangle, a square, or other polygons (including a rectangle or a polygon with rounded corners).

<Production method>
With reference to FIG. 12, the manufacturing method of the diffraction grating film concerning embodiment of this invention is demonstrated. A UV (Ultra Violet, ultraviolet) curable coating 301 (PMMA) is applied to the surface of the PET film 302 (FIG. 12A). A UV curable coating 301 is applied and a mask 303 is applied to pattern the film in a desired arrangement. Patterning can be performed by applying an electron beam resist, patterning with an electron beam, and developing. Alternatively, a photoresist can be used. Thereafter, the UV curing paint 301 is cured by irradiating UV from the surface side where the mask 303 is provided (FIG. 12B). By washing the uncured portion with an acid, a diffraction grating film having a desired pattern can be obtained (FIG. 12C). Moreover, a diffraction grating film can also be created by forming a cylinder by etching or hot pressing.

  Instead of the PET film 302, another general-purpose plastic film can be used.

(Light emitting structure)
<Constitution>
FIG. 13 is a view showing a cross section of the light emitting structure according to the embodiment of the present invention. The diffraction grating film 200 is assembled on the light emitting surface side of the light emitting diode of the light emitting diode built-in light emitting film 220 with a predetermined distance from the light emitting diode 221. The diffraction grating film 200 is fixed to the light emitting diode built-in film 220 with resin, metal, or other appropriate material. The light emitted from the light emitting diode 221 is visually recognized from the outside through the diffraction grating film 200. By using a light emitting diode chip (surface mount type light emitting diode) as the light emitting diode, it is possible to make it thinner.

  FIG. 14 is a diagram for explaining the conditions for interference of diffracted light. It is assumed that light emitted from the light emitting diode in the direction of the angle θ interferes with the diffraction grating film 200. The condition under which the diffracted light interferes with the diffraction grating film 200 is expressed as (Equation 1).

d: Grating spacing of the diffraction grating θ: Angle formed by the light direction and the normal of the surface of the diffraction grating film m: Arbitrary integer λ: Wavelength of light from the light emitting diode The optical path difference of light emitted in almost the same direction is Interference occurs when the wavelength becomes an integral multiple of the wavelength (λ) of the light source. From this equation, the direction (angle) of light with which the diffracted light interferes is determined. Here, sin θ in (Expression 1) is expressed as (Expression 2).

L: Distance between the light emitting surface and the diffraction grating film x: Distance from the center of the light emitting surface from the leg of the perpendicular line dropped on the diffraction grating film The distance (L) between the light emitting surface and the diffraction grating film and the diffraction grating By adjusting the grating interval (d), the position where the diffracted light interferes in the diffraction grating film can be arbitrarily determined.

The distance from the surface of the diffraction grating film to the observer is the distance between the light emitting surface and the diffraction grating film (
L) is very large. Therefore, interference due to the optical path difference of the light emitted from the diffraction grating film can be ignored.

  FIG. 15 is a diagram illustrating positions where diffracted light interferes on the diffraction grating film. A diffraction grating film having a square grating is used. When the light emission of the light emitting diode is observed through the diffraction grating film, the light 101 is directly seen on the center of the diffraction grating film, and the interference 102 of a plurality of diffracted lights is seen around it. The light emitting surface of the light emitting diode 221 has a certain area. Therefore, the position where the diffracted light interferes also has a certain area. The distance (x in FIG. 14) between the center of the direct light and the center of the position where the diffracted light interferes is made equal to the diameter of the light emitting surface of the light emitting diode. By doing so, the area of the light source can be made to appear pseudo large. The distance between the center of the direct light and the center of the position where the diffracted light interferes (x in FIG. 14) can be determined by adjusting the distance between the light emitting surface and the diffraction grating film (L in FIG. 14).

  FIG. 16 is a diagram illustrating positions where diffracted light interferes on the diffraction grating film. When the light emission of the light emitting diode is observed through the diffraction grating film, the direct light 101 is seen in the center on the diffraction grating film, and the interference 102 due to the diffracted light is seen a little away from the light 101. The distance (L in FIG. 14) between the light emitting surface and the diffraction grating film is made longer than in the case of FIG. By doing so, one light source can appear to have a plurality of light sources on the diffraction grating film.

  FIG. 17 is a diagram illustrating positions where light from a plurality of light emitting diodes interferes on the diffraction grating film. The light emitting diodes are arranged on lattice points of a square lattice. The lattice spacing of the square lattice is about three times the diameter of the light emitting surface of the light emitting diode. A diffraction grating film having a square grating is used. The distance between the light emitting surface and the diffraction grating film (L in FIG. 14) and the lattice spacing of the diffraction grating (d in FIG. 14) are adjusted in the same manner as in FIG. By doing so, almost the entire surface of the diffraction grating film can be made to emit light with fewer light emitting diodes.

  FIG. 18 is a diagram illustrating positions where light from a plurality of light emitting diodes interferes on the diffraction grating film. The light emitting diodes are arranged on triangular lattice points. The lattice spacing of the triangular lattice is about three times the diameter of the light emitting surface of the light emitting diode. A diffraction grating film having a square grating is used. The distance between the light emitting surface and the diffraction grating film (L in FIG. 14) and the lattice spacing of the diffraction grating (d in FIG. 14) are adjusted in the same manner as in FIG. By doing so, the gap can be made smaller and almost the entire surface of the diffraction grating film can emit light.

  FIG. 19 is a diagram illustrating positions where diffracted light interferes on the diffraction grating film. When the light emission of the light emitting diode is observed through the diffraction grating film, the direct light 101 is seen in the center on the diffraction grating film, and the interference 102 due to the diffracted light is seen a little away from the light 101. A diffraction grating film having a triangular grating is used. By doing so, the area of the light source can be made to appear pseudo large. By using a triangular diffraction grating film, the intensity of interference of diffracted light around the direct work can be made more uniform. The distance between the center of the direct light and the center of the position where the diffracted light interferes (x in FIG. 14) can be determined by adjusting the distance between the light emitting surface and the diffraction grating film (L in FIG. 14).

FIG. 20 is a diagram illustrating positions where light from a plurality of light emitting diodes interferes on the diffraction grating film. The light emitting diodes are arranged on triangular lattice points. The lattice spacing of the triangular lattice is about three times the diameter of the light emitting surface of the light emitting diode. A diffraction grating film having a triangular grating is used. The distance between the light emitting surface and the diffraction grating film (L in FIG. 14) and the lattice spacing of the diffraction grating (d in FIG. 14) are adjusted in the same manner as in FIG. By doing so, almost the entire surface of the diffraction grating film can be made to emit light more uniformly with fewer light emitting diodes.

(Effect of this embodiment)
According to the embodiment of the present invention, it is possible to make the light emitting source appear larger by disposing the diffraction grating film at an appropriate distance from the light emitting diode. In addition, a plurality of light emission sources can be shown. Furthermore, the use of a surface-mounted light emitting diode can make the light emitting structure thinner.

According to the light emitting structure of the embodiment of the present invention, since a light emitting diode chip and a flexible film are used, a thinner light emitting light source can be provided. Therefore, the light-emitting diode-embedded light-emitting film of the present invention can be expected to have a wide range of uses as a light source that replaces a surface light emitter and an advertising fluorescent lamp. In addition, since the light emitting diode has low power consumption and long life, the light source device using the light emitting structure according to the embodiment of the present invention can reduce the maintenance work.

  In addition, the light emitting structure of the present embodiment uses an expensive PI film for a part necessary for soldering, and uses a general-purpose plastic film that is less heat resistant than the PI film but is inexpensive for other parts. A light-emitting film incorporating a light-emitting diode with a large area can be manufactured at low cost. That is, the soldering of the light emitting diode is automated by soldering the light emitting diode to the conductive pattern on the PI film in a reflow furnace. Furthermore, after soldering is completed, an inexpensive material with poor heat resistance can be used by attaching the PI film to a general-purpose plastic film such as PET.

  The light emitting structure of the present embodiment can be expected to be used for a rear combination lamp, a room lamp, a foot lamp, a meter panel and the like of an automobile. As a general light source, it can be used as an interior decoration lamp or a display lamp.

  In addition, since a product is produced based on a film, it is possible to produce a light source that is very light and inexpensive, has a long life, hardly generates heat, and is friendly to the environment.

1 Light emitting diode (LED)
2 Solder 3 Conductive part 3A Conductive part (+)
3B Conductive part (-)
4 Heat resistant film (PI film)
5 Base film (PET film)
DESCRIPTION OF SYMBOLS 101 Direct light 102 Diffracted light 200 Diffraction grating film 201 Diffraction grating film 202 Diffraction grating film 203 Diffraction grating film 211 Cylinder 212 Square pillar 220 Light emitting diode built-in light emitting film 221 Light emitting diode 301 UV curable paint 302 PET
303 Mask

Claims (6)

A plurality of heat-resistant films having conductive portions formed on the surface;
A plurality of light emitting elements bonded to the conductive portion;
A base film to which the plurality of heat-resistant films are attached;
A light-emitting element built-in light-emitting film comprising:
A diffraction grating film assembled on the light emitting surface side of the light emitting element of the light emitting element built-in light emitting film with a predetermined distance from the light emitting element, and
The said base film is a light emitting structure which is a film in which heat resistance is inferior to the said heat resistant film. The light-emitting structure according to claim 1, wherein the heat-resistant film is a polyimide film, PPS, a heat-resistant urethane film, or a liquid crystal polymer film. The light emitting structure according to claim 1, wherein the light emitting element is a light emitting diode. The light emitting structure according to any one of claims 1 to 3, wherein the base film is a polyethylene terephthalate film, a PP film, a PE film, a PS film, or a PPMA film. The diffraction grating film is composed of a polyethylene terephthalate film and PMMA.
The light emitting structure according to any one of claims 1 to 4. The diffraction grating film has a diffraction grating of a square grating or a triangular grating,
The light emitting structure according to any one of claims 1 to 5.

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