JP4651787B2 - Light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light-emitting device that can uniformly emit light on a light-emitting surface of a light guide incident from an LED element that is a point light source, and is used for a liquid crystal backlight, a panel meter, a display lamp, a surface-emitting switch, and the like. .
[0002]
[Prior art]
In recent years, light-emitting devices that emit light from LED elements that are point light sources in a planar shape have been used as light sources such as liquid crystal backlights. The light emitting device is configured to allow light from the light emitting diode to enter from the light incident end face of the light guide plate and to emit light from the entire upper surface of the light guide plate. In this light emitting device, it is important to output light uniformly from the upper surface (light emitting surface), and various structures have been proposed to realize this uniformity. An example of such a light emitting device is shown in the schematic plan view of FIG. The light emitting device of FIG. 7 includes a light guide plate 71 made of a transmissive resin, an LED element 74 disposed opposite to the light incident end face of the light guide plate, and a light emitting surface so as to emit light from the upper surface side of the light guide plate. And reflectors (not shown) provided on the side and bottom surfaces excluding the light incident end face.
[0003]
In the light emitting device of FIG. 7, a semi-cylindrical notch 75 is formed on the light incident end face of the light guide plate so that light is uniformly dispersed and incident in a direction parallel to the upper surface of the light guide plate. In this way, the surface emission in which the light incident from the LED element is emitted from the upper surface is made uniform.
[0004]
[Problems to be solved by the invention]
However, it is not sufficient at present when more uniform and high luminance light emission is required. In particular, when a light-emitting element (LED element) with higher emission luminance is used as a point light source, the problem is that it is difficult to achieve both the uniform surface emission and the higher luminance because there is a trade-off between the above-described configurations alone. was there. Therefore, an object of the present invention is to provide a light emitting device that solves the above-described problems and is more uniform and capable of emitting light with high luminance.
[0005]
[Means for Solving the Problems]
As a result of various experiments, the present inventors have formed a notch having a specific shape on one end surface of the light guide to diffuse light incident from one end surface of the light guide more widely in the light guide, It has been found that light can be emitted more uniformly and with high brightness from the light emitting surface, and the present invention has been achieved.
[0006]
That is, the light emitting device of the present invention includes a light guide having a first main surface, a second main surface facing the first main surface, and a light incident end surface, and a reflector disposed on the second main surface of the light guide. And a light emitting part disposed to face the light incident end face Light emitting diode And the light guide has a plurality of notches on the light incident end surface. The light emitting device emits light from the light incident portion through the light incident end surface and emits the light from the first main surface. And the plurality of notches have substantially the same distance and width from the light incident end surface to the deepest portion, Center of light incident end face The angle formed with the light incident end face of the light guide increases as the distance from the , Far from the center of the light incident end face The angle formed by the first surface and the light incident end surface of the light guide is reduced. , Near the center of the light incident end face And a second surface.
Thereby, the light incident from the light source through the notch formed on the one end surface of the light guide can be refracted in the direction according to the angle of the second surface and the first surface of the notch, so that it is wider. Light can be diffused in the direction, and uniform and high luminance surface light emission can be achieved.
[0007]
The light-emitting device of the present invention includes a light guide having a first main surface, a second main surface opposite to the first main surface, and a light incident end surface, and a reflection disposed on the second main surface of the light guide. And a light emitting part disposed to face the light incident end face Light emitting diode A light-emitting device that causes light from the light-emitting portion to be incident from the light-incident end surface and to be emitted from the first main surface, wherein the light guide is located on the light-incident end surface at the center of the light-emitting portion. A plurality of cutouts formed from surfaces with different angles as they move away from each other, and each of the plurality of cutouts has substantially the same distance and width from the light incident end surface to the deepest portion. As the distance from the center of the light emitting part increases, the deepest part shifts in the direction away from the center. It is characterized by that. Thereby, the light from a light emission part can be refracted in the direction according to the angle of the surface which comprises a notch.
[0008]
In the present invention, the notches can be formed such that adjacent notches are separated from each other via a plane. In this way, a flat surface can be formed between the notches. As a result, out of the light incident on the light incident end face, the light incident from the first surface and the second surface constituting the notch is refracted and diffused in the lateral direction, and the light incident from the flat surface is incident. Since the light can be propagated in the direction perpendicular to the end face, uniform and high luminance surface light emission can be achieved in a light-emitting device using a light guide having a relatively long shape (for example, a rectangle with a light incident end face having a short side). Can do.
[0009]
In the present invention Light emitting diode Can use an LED element including a semiconductor element and a fluorescent material that can absorb light from the semiconductor element and emit light having a longer wavelength than the absorbed light. As a result, light of an arbitrary wavelength can be emitted in a planar shape by a combination of a semiconductor element and a fluorescent material, and surface emission with excellent color mixing (emission color uniformity) by the above-described cutout of the light incident end face. Can be obtained.
[0010]
In the present invention Light emitting diode Can be configured to emit white light, which is a mixed color of light generated by the semiconductor element and light generated by the fluorescent material, from the first main surface of the light guide. Thereby, uniform and high brightness white surface light emission suitable for a liquid crystal backlight or the like can be obtained.
[0011]
In the light emitting device of the present invention, the semiconductor element is a nitride semiconductor element, and the phosphor is activated by Ce. ₂ O ₃ ・ 5 / 3Al ₂ O ₃ Ni-containing CaO-Al activated by Eu, Cr ₂ O ₃ -SiO ₂ It can be set as the fluorescent substance selected from these. Thereby, it is possible to provide a light emitting device that is simple, has high luminance, and is capable of emitting light with high reliability.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The light emitting device of the present invention introduces light emitted from a light source into a light guide to emit light in a planar shape. This light-emitting device can select the shape of the light guide to be used according to its application and purpose. For example, when used for a backlight of a liquid crystal such as a personal computer, a substantially rectangular flat light guide is used. In addition, when used for a backlight of an automobile panel meter or the like, a light guide having a shape corresponding to the design is used.
Hereinafter, a light emitting device according to an embodiment of the present invention will be described with reference to the drawings.
[0013]
As shown in FIGS. 1 and 2, the light-emitting device according to the embodiment of the present invention includes a light guide body 11 having at least a first main surface and a second main surface facing each other, and a second light guide body. A reflector 12 provided on the main surface and a light source 14 disposed opposite to one end surface of the light guide are provided. The light emitted from the emission surface of the light emitting unit of the light source is introduced into the light guide through the light incident end surface 11a, which is one end surface of the light guide, and then is emitted from the first main surface, which is the light emission surface. .
[0014]
Here, in particular, the light guide 11 of the light emitting device of the present embodiment has a plurality of cutouts 15 having different shapes on the light incident end surface 11a facing the emission surface of the light emitting portion of the light source 14. The plurality of cutouts 15 respectively include a first surface 15a that increases in angle with the light incident end surface of the light guide as it moves away from the center of the surface facing the emission surface of the light emitting unit, and the emission of the light emitting unit. And a second surface 15b having a smaller angle with the light incident end surface of the light guide as it moves away from the center of the surface facing the surface, and as viewed from the light emitting surface of the light guide Uniform and high luminance surface light emission can be achieved by suppressing unevenness in luminance near the light incident end face.
[0015]
More specifically, in the light emitting device according to the present embodiment, the light source 14 includes, for example, a support body made of a resin-formed body and two LED elements 13 arranged in a recess formed on the side surface thereof. This LED element 13 is a semiconductor element disposed in a recess of a resin package having a lead electrode and molded by a translucent resin containing a phosphor, and its emission surface becomes flat as shown in FIG. Is molded as follows.
[0016]
In the present embodiment, the light guide 11 is formed into a substantially rectangular flat plate shape using, for example, injection molding using a translucent resin, and the light incident end face facing the light source 14 is shown in FIGS. 1 and 2. Thus, a plurality of cutouts 15 are formed along the longitudinal direction of the light incident end face. The light source 14 includes two LED elements 13, and a plurality of notches are respectively formed in regions having substantially the same width as the width of the light emitting portion of the LED element 13.
In the present embodiment, one notch has a triangular prism shape formed of two side walls that extend substantially perpendicularly from the first main surface to the second main surface. Here, of the two side walls constituting the cutout, the side wall far from the center of the region facing the emission surface of the light emitting portion is defined as the first surface 15a, and the side wall near the center is defined as the second surface 15b. And
The width of each notch and the depth 15d (the distance between the light incident end face 14 and the deepest part 15c) of the deepest part 15c (the part cut deepest with respect to the light incident end face) are substantially the same. The positions of 15c are different. The width of one notch is preferably smaller than one third of the width of the LED element, and is preferably formed as small as possible in accordance with the accuracy of the mold or the like. In addition, the depth of one notch can be set to an arbitrary depth, but if it is too deep, a thick air layer is provided before the light from the light source reaches the light guide, and light is lost. In some cases, there are cases where the effective light emitting area is narrowed depending on the form of the light emitting device, and these must be taken into consideration.
[0017]
In addition, the notch located at the center of the plurality of notches formed in the region facing the emission surface of the light emitting part is formed so that the deepest part 15c is at the center of the width of the notch, so that the light emitting surface When viewed from, it becomes an isosceles triangle. That is, the angle formed between the first surface and the light incident end surface is equal to the angle formed between the second surface and the light incident end surface. The other notches are formed such that the deepest portion 15c is shifted in the direction of the separation as the distance from the center of the emission surface of the light emitting portion increases. By doing so, the angles formed by the first and second surfaces constituting the cutout and the light incident end surface are changed so as to be larger or smaller than the light incident end surface, respectively. Note that the shape of all the cutouts does not have to be different from each other, for example, the center three of the seven cutouts are the same shape, and the two at both ends are different in shape from the center three. May be. When the number of notches facing the light emitting part is an even number, it is not necessary to form an isosceles triangular notch, and the angle of the side wall of the notch is changed in the same manner as described above depending on the position from the center of the light emitting part. .
[0018]
In the light emitting device of the present embodiment configured as described above, a plurality of cutouts having different shapes are formed on the light incident end face of the light guide, and thus the following operational effects are obtained.
That is, the light emitted from the light source 14 has two side walls (the first surface 15a and the first surface 15a and the first main surface 15a formed on the light incident end surface 11a of the light guide 11 and extending almost perpendicularly from the first main surface to the second main surface. It is incident on a notch 15 having a second surface 15b). The light incident on the cutout is introduced into the light guide through the two surfaces, and is refracted or reflected at an angle corresponding to the angle of the side wall.
For example, light directly incident on the first surface 15a out of light from the light source has an incident angle smaller than the total reflection angle with respect to the first surface 15a (an angle formed between the light traveling direction and the surface normal). When incident, the light enters the light guide at a refraction angle corresponding to the incident angle. In addition, light incident on the first surface 15a at an incident angle larger than the total reflection angle is reflected toward the second surface 15b without being introduced into the light guide. Of the light reflected from the first surface 15a toward the second surface 15b, light incident at an incident angle smaller than the total reflection angle is introduced from the second surface 15b into the light guide. Also, when the light from the light source is directly incident on the second surface 15b, it is reflected or refracted according to the incident angle with respect to the side wall as described above.
Here, the refraction in the case where light is incident on a triangular prism-shaped notch with the same positional relationship between the light source and the notch but with a different shape (that is, the angle between the side wall and the light incident end face is different) is shown in FIG. Shown in a) and (b). In the case of FIG. 3B in which the angle formed between the first surface 35a on which light is incident and the light incident end surface 31a is larger than that in FIG. 3A, the lateral direction (in this case) is larger than that in FIG. It can be seen that the light is refracted in the direction toward the side surface of the light guide. This is because even if light is emitted from the light source at the same angle, the angle of refraction changes because the angle of incidence changes as the angle of the side wall changes. As a result, the light can be refracted as shown in FIG. 3B, so that the light can be propagated between the light sources and also in a portion having a low light emission luminance such as a corner portion of the light guide, and uniform and high luminance. The surface emission can be obtained.
In addition, since the first surface 35a and the second surface 35b constituting the notch are flat, for example, compared with a cylindrical notch having the same width and depth (the side wall is a curved surface), the light source and the side wall Since the distance between the two becomes shorter and the air layer can be reduced, the loss of light can be reduced. Next, a modified example of the present invention will be described.
[0019]
(Modification 1)
As shown in FIG. 4, the light emitting device of Modification 2 according to the present invention except that a plurality of notches 415 having a third surface 415 e are formed between the first surface 415 a and the second surface 415 b. The configuration is the same as that of the embodiment. Since the angles formed by the first surface and the second surface of each notch and the light incident end surface are changed in the same manner as in the embodiment, the light from the light source diffuses widely in the lateral direction as in the embodiment. Is done. The angle, width, and the like of the third surface 415e (or the fourth surface or the like may be added thereto) may be arbitrary, and may not be provided in all the notches. Since the third surface has a smaller angle with the light incident end surface than the first surface and the second surface, the light distribution in the direction far from the light incident end surface can be increased.
[0020]
(Modification 2)
As shown in FIG. 5, the light emitting device of Modification 2 according to the present invention is implemented except that a plurality of cutouts 515 having a curved surface 515f are formed between the first surface 515a and the second surface 515b. It is configured in the same way as the form. Since the angles formed by the first and second surfaces of each notch and the light incident end surface are changed in the same manner as in the embodiment, the light from the light source is laterally changed in the same manner as in the embodiment. Widely spread. The first surface and the second surface constituting the notch are in contact with each other via the curved surface 515f, so that the notch can be easily taken out from the mold when the width of the notch is narrow and the width of the deepest portion is narrowed. it can.
[0021]
(Modification 3)
As shown in FIG. 6, the light emitting device of Modification 3 according to the present invention is configured in the same manner as the light emitting device of the embodiment except that triangular notches 615 are formed apart from each other. The shape of each notch 615 can be changed as in the embodiment. By forming adjacent notches 615 apart, a surface (flat portion) 611g perpendicular to the light emitted from the light source and surfaces 615a and 615b inclined with respect to the light emitted are formed on the light incident end surface. Will be. The side walls 615a and 615b of the notch 615 can refract light and diffuse widely in the lateral direction, but the flat portion 611g propagates light toward the opposite side of the light incident end face without refracting incident light in the lateral direction. Can do. With this configuration, in the case of a light emitting device using a relatively long light guide (a rectangle having a light incident end face as a short side), light is propagated to a portion far from the light incident end face. And surface emission with more uniform luminance can be obtained. The ratio of the notch 615 to the flat surface 611g (the ratio in the region facing the light emitting surface of the light emitting part) is about 1: 2 to 2: 1 in terms of area, although it depends on the shape and size of the light guide plate. preferable. Further, all the cutouts may not be formed apart from each other, and some of them may be formed in contact with each other.
[0022]
As described above with reference to the embodiment, the light emitting device of the present invention forms a plurality of cutouts having different shapes on the light incident end face of the light guide and configures the cutouts according to the positions to be formed. Incident light can be diffused more widely in the light guide by changing the angle formed between the two surfaces and the light incident end surface, so that unevenness in light emission can be suppressed and surface light emission with high luminance can be obtained.
[0023]
As described above, the light-emitting device of the present invention can be configured so that incident light can be diffused more effectively by selecting the most appropriate shape of the notch according to the shape of the light guide. In this case, if the number of notches is increased to increase the side wall, light can be diffused in a more complicated manner, and the uniformity of brightness can be improved. However, the mold structure becomes complicated, and as a result, the mold is manufactured. There may be a problem that the shape of the end face of the light guide is not constant. Therefore, it is preferable to select the shape to be used in consideration of the manufacturing conditions in addition to the required specifications depending on the purpose of use.
[0024]
That is, since various shapes can be selected in the present invention, which shape of the cutout is selected depends on the target performance, restrictions on manufacturing the mold (manufacturing accuracy and manufacturing cost), molding accuracy, etc. Can be determined through comprehensive consideration.
[0025]
Hereinafter, preferred materials and the like regarding each element in the light emitting device according to the present invention will be described.
(Light guide)
As the material used for the light guide in the present invention, it is preferable to use a material excellent in light transmittance and moldability, and examples thereof include acrylic resins, polycarbonate resins, cycloolefin polymers, polystyrene resins, functional norbornene resins, and the like. It is done. These light guide materials have different refractive indexes, but the light diffusion can be controlled by selecting the angle and number of notches formed on the light incident end face of the light guide. It can be applied to any refractive index material. The shape of the light guide can be any shape depending on the application.
[0026]
(light source)
In the light emitting device of the present invention, the light source includes one or two or more LED elements, and in order to position and fix the LED element and the notch formed on one end surface of the light guide plate so as to face each other, for example, resin The light emitting surface of the LED element is arranged on a support made of a molded body so as to face the light incident end surface of the light guide. The LED element has a semiconductor element and a translucent resin that covers the semiconductor element. The translucent resin absorbs light generated from the semiconductor element and generates light having a wavelength different from that of the absorbed light. The fluorescent substance to be contained can be contained. When the light generated from the semiconductor element is ultraviolet light, a phosphor that is excited by the ultraviolet light to generate ultraviolet light or visible light can be used, or a semiconductor element capable of emitting visible light, and the semiconductor element A fluorescent material that absorbs visible light from the light source and can emit visible light having a longer wavelength than that may be combined. That is, in the present invention, it is possible to emit mixed colors of various tones by using a semiconductor element in combination with a phosphor. Furthermore, color mixing can also be improved by making light enter from the above-mentioned notch.
[0027]
(Semiconductor element)
The semiconductor element that can be used here is a nitride compound semiconductor (general formula In _i Ga _j Al _k N, where 0 ≦ i, 0 ≦ j, 0 ≦ k, i + j + k = 1), and various types include InGaN and GaN doped with various impurities. This semiconductor element is formed by growing a semiconductor such as InGaN or GaN as a light emitting layer on a substrate by MOCVD or the like. Examples of the semiconductor structure include a homostructure, a heterostructure, or a double heterostructure having a MIS junction, a PIN junction, a pn junction, or the like. The nitride semiconductor layer can have various emission wavelengths depending on the material and the degree of mixed crystal. Moreover, it can also be set as the single quantum well structure and multiquantum well structure which formed the semiconductor active layer with the thin film which produces a quantum effect.
[0028]
(Phosphor)
Examples of the phosphor used in the light emitting device of the present invention include a photoluminescence phosphor that emits light when excited by visible light or ultraviolet light. As a specific example of a photoluminescence phosphor, YAG (YAG such as YAG: Ce, which is a phosphor capable of emitting yellow light by blue light emission from a nitride compound semiconductor element) ₂ O ₃ ・ 5 / 3Al ₂ O ₃ ) Series phosphors. In the present invention, the YAG phosphor is to be interpreted particularly broadly, and is substituted with at least one element selected from Y, Lu, Sc, La, Gd and Sm, or a part or the whole of aluminum is replaced. , And are used to include a phosphor that emits a fluorescent action that substitutes either or both of Ga and In. This YAG phosphor is obtained as follows. First, a solution obtained by dissolving a rare earth element of Y, Gd, and Ce in an acid in a stoichiometric ratio is reacted with oxalic acid to form a coprecipitation compound, and the coprecipitation compound is baked to obtain a coprecipitation oxide. A fired product obtained by mixing and baking this coprecipitated oxide and aluminum oxide can be washed, separated and dried, and a YAG phosphor can be obtained through a sieve. Using this phosphor, white light emission (including white color in JIS Z8110 system color name) can also be obtained by mixing the light from the semiconductor element and the light from the phosphor.
[0029]
Similarly, phosphors capable of emitting red light by blue light emission include nitrogen-containing CaO-Al activated by Eu and / or Cr. ₂ O ₃ -SiO ₂ A phosphor (oxynitride fluorescent glass) is mentioned. This phosphor is obtained by melting, in a nitrogen atmosphere, a mixture of a rare earth raw material mixed with a raw material such as aluminum oxide, yttrium oxide, silicon nitride and calcium oxide in a nitrogen atmosphere, and is washed, separated, dried, and obtained through a sieve. be able to. As a result, an excitation spectrum having a peak at 450 nm and a Ca—Al—Si—N-based oxynitride fluorescent glass activated by Eu and / or Cr capable of emitting red light by blue light having a peak at about 650 nm are obtained. be able to.
[0030]
The peak of the emission spectrum can be continuously shifted from 575 nm to 690 nm by increasing or decreasing the nitrogen content of the Ca—Al—Si—N-based oxynitride fluorescent glass activated with Eu and / or Cr. it can. Similarly, the excitation spectrum can be shifted continuously. Therefore, by combining light from a gallium nitride compound semiconductor containing GaN or InGaN doped with impurities such as Mg and Zn and light of a phosphor of about 580 nm, a white system similar to that of a YAG phosphor is obtained. Can emit light.
[0031]
【Example】
Example 1
The light-emitting device of Example 1 of the present invention is an example using the light guide shown in FIG. 1 used in the embodiment. Polycarbonate is used as the material of the light guide, and the mold for forming the light guide is formed in two places where seven triangular columnar notches having two side walls are arranged. In addition, the mold is manufactured so as to be subjected to an unevenness (texture) process for improving the uniformity of light emitted to the second main surface of the light guide. The light guide is molded by first setting the molding temperature to 280 ° C. and melting the polycarbonate while the injection pressure is 1000 kgf / cm. ² The mold temperature is injection molded at 100 ° C. And after cooling for 45 seconds, it takes out from a metal mold | die. In this way, a light guide was formed. One end face of the obtained light guide is formed with two triangular columnar cutouts arranged in two places, and the total width of the five cutouts is formed to be approximately the same width as the LED element. Has been. Each notch has the same width, and the center of the notch located at the center of the five notches is substantially opposite to the center of the LED element. The notch in the center is an isosceles triangle as viewed from the light emitting surface, and the angle formed by the first and second surfaces and the light incident end surface is about 75 degrees. Each of the other cutouts has a first surface and a second surface with different angles, and the angle formed between the second surface (the surface far from the center of the light emitting portion) and the light incident end surface as the distance from the center increases. Are changed to 80 degrees, 85 degrees, and 90 degrees, and the angle formed between the first surface (the surface near the center of the light emitting portion) and the light incident end surface is changed to 70 degrees, 65 degrees, and 60 degrees.
The light guide thus obtained is provided with a reflection sheet except for the first main surface for extracting light in a planar shape from the light guide and the end surface for introducing light into the light guide. In addition, an SMD type light emitting diode having two LED elements made of nitride semiconductor and capable of emitting white light is disposed on the end face of the light guide without the reflection sheet. When a current is passed through the LED element of the light-emitting device thus obtained, light is incident from the end face of the light guide and can be emitted in a planar shape from the first main surface of the light guide. The formed light-emitting device emits light uniformly without deterioration in light emission luminance even between the corners on the incident end face side and between the light sources as compared with other portions, and the light emission luminance can be improved.
[0032]
(Example 2)
Acrylic resin is used as a material for the light guide, and a die having six notches having a third surface as shown in FIG. 4 on the end surface of the light guide is formed at two locations. Molding temperature is 250 ° C, injection pressure is 1100kgf / cm ² The light emitting device of the present invention is formed in the same manner as in Example 1 except that the mold temperature is 80 ° C. and the cooling time is about 30 seconds. In the light emitting device obtained in this way, when a current is passed through the LED element to cause planar light emission, the light emission brightness is uniform and the light emission brightness is not inferior even when compared to other portions between the corners on the incident end face side and the light source. Thus, more uniform planar light emission can be obtained.
[0033]
(Example 3)
Acrylic resin is used as the material of the light guide, and seven notches are formed at two locations where the first and second surfaces are in contact with the end surface of the light guide through a curved surface as shown in FIG. Mold is used, molding temperature is 250 ° C., injection pressure is 1100 kgf / cm ² The light emitting device of the present invention is formed in the same manner as in Example 1 except that the mold temperature is 80 ° C. and the cooling time is about 30 seconds. In the light emitting device obtained in this way, when a current is passed through the LED element to cause planar light emission, the light emission brightness is uniform and the light emission brightness is not inferior even when compared to other portions between the corners on the incident end face side and the light source. Thus, more uniform planar light emission can be obtained.
[0034]
Example 4
Acrylic resin is used as the material of the light guide, and a mold is used in which notches formed with six notches separated from each other as shown in FIG. Molding temperature is 250 ° C, injection pressure is 1100kgf / cm ² The light emitting device of the present invention is formed in the same manner as in Example 1 except that the mold temperature is 80 ° C. and the cooling time is about 30 seconds. In the light emitting device obtained in this way, when a current is passed through the LED element to cause planar light emission, the light emission brightness is uniform and the light emission brightness is not inferior even when compared to other portions between the corners on the incident end face side and the light source. Thus, more uniform planar light emission can be obtained.
[0035]
(Comparative Example 1)
Similarly, as a comparative example, a light emitting device is formed in the same manner as in the example except that a semicylindrical cutout is formed on the end face of the light guide as shown in FIG. In this light-emitting device, when a current was passed through the LED element to emit light in a planar shape, the periphery of the LED element was slightly bright and the corner on the incident end face side was dark, and uniform surface emission could not be obtained. . In addition, the luminance of other portions was not sufficient.
[0036]
【The invention's effect】
As described above, the light emitting device of the present invention can obtain light emission luminance comparable to that of other portions even at the corner on the incident end face side that is likely to be dark. Thereby, the light emitted from the LED element and incident on the light guide can be emitted from the light guide uniformly and with high brightness.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a light emitting device according to an embodiment of the present invention.
FIG. 2 is a schematic plan view of the light emitting device according to the embodiment.
FIGS. 3A and 3B are schematic plan views for explaining light refraction at a notch in a light guide end face in the light emitting device of the present invention. FIGS.
FIG. 4 is a schematic plan view of a light guide body of a light emitting device of a first modification according to the present invention.
FIG. 5 is a schematic plan view of a light guide body of a light emitting device of a second modification according to the present invention.
FIG. 6 is a schematic plan view of a light guide body of a light emitting device of a third modification according to the present invention.
FIG. 7 is a schematic plan view of a light emitting device of a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11, 71 ... Light guide, 11a ... Light incident end surface of a light guide, 11b ... Side surface of a light guide, 12 ... Reflector, 13, 73 ... LED element, 14 * ..Light source, 15, 35, 415, 515, 615, 75 ... notch, 15a, 35a, 415a, 515a, 615a ... first surface of notch, 15b, 35b, 415b, 515b, 615b 2nd surface of notch, 15c, 35c ... Deepest part of notch, 415e ... 3rd surface of notch, 515f ... Curved surface of notch, 611g ... Light guide The flat part of the light incident end face of the body.

Claims (6)

A light guide having a first main surface and a second main surface facing the first main surface, and a light incident end surface, a reflector disposed on the second main surface of the light guide, and facing the light incident end surface A light-emitting diode having a light- emitting portion arranged as described above, and a light-emitting device that causes light from the light-emitting portion to be incident from the light incident end surface and emitted from the first main surface,
The light guide has a plurality of notches on the light incident end face,
Each of the plurality of notches has substantially the same distance and width from the light incident end surface to the deepest portion, and an angle formed with the light incident end surface of the light guide as the distance from the center of the light incident end surface increases. The angle formed by the first surface far from the center of the light incident end surface and the light incident end surface of the light guide becomes smaller , and the second near the center of the light incident end surface becomes smaller. A light-emitting device comprising: A light guide having a first main surface and a second main surface facing the first main surface, and a light incident end surface, a reflector disposed on the second main surface of the light guide, and facing the light incident end surface A light-emitting diode having a light- emitting portion arranged as described above, and a light-emitting device that causes light from the light-emitting portion to be incident from the light incident end surface and emitted from the first main surface,
The light guide has a plurality of notches formed on surfaces of the light incident end face that are different in angle as the distance from the center of the light emitting unit increases.
Said plurality of notches state, and are approximately the same distance and width from each of the light incident end face to the deepest, away from the center of the light emitting portion, that is provided so that the deepest portion thereof away direction is deviated A light emitting device characterized by that.   The light-emitting device according to claim 1, wherein the notches are adjacent to each other through a plane. 4. The light emitting diode according to claim 1, comprising: a semiconductor element; and a fluorescent material capable of absorbing light from the semiconductor element and emitting light having a longer wavelength than the absorbed light. The light-emitting device of description.   Each of the plurality of notches has a third surface between the first surface and the second surface, and the first surface and the second surface are flat surfaces, The light emitting device according to claim 1, wherein the third surface is a curved surface. 6. The light emitting device according to claim 1 , wherein the cutout formed in a central portion of the light incident end face is a cutout recessed inward of the light guide .

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