TWI390762B - Light emitting diode light source - Google Patents

Description

Light-emitting diode source

The present invention relates to light emitting diode (LED) light sources that can be used in illumination or liquid crystal backlights.

In recent years, the luminous efficiency of the light-emitting diode element has been remarkably improved, and the application of illumination has been improved. In particular, when a light-emitting diode is used as a backlight source for a liquid crystal display, good color reproducibility and high-speed reactivity can be obtained, and a high level of image quality is expected. Moreover, since mercury is not used, it is not harmful to the environment, and the use of interior lighting or headlights for automobiles is also progressing.

When the light-emitting diode is used as a light source for illumination or a light source for backlight, it is necessary to mount a plurality of light-emitting diode elements on the same planar substrate to form a planar light source.

In the past, a so-called "bullet-type" LED bulb or a "top view" type LED bulb was arranged in two dimensions on a plane to obtain a planar light source. However, in this manner, the light-emitting diode elements are mounted one by one in individual packages, which is disadvantageous in terms of cost. Moreover, since the thermal impedance of the package is large, there is also a problem that heat generated by the light-emitting diode element is difficult to efficiently dissipate heat.

When the cannonball type LED bulb or the overhead type LED bulb is arranged at a certain interval in a plane, the bulb is brighter directly above, and the middle of the bulb and the bulb is relatively dark. Therefore, in order to average the brightness, a diffusion plate is required, and the distance between the bulb and the diffusion plate must be 30 mm or more (Japanese Patent Laid-Open Publication No. 2004-233957 (Patent Document 1), JP-A-2000-329940 (Patent Document 2)). Therefore, it is difficult to reduce the brightness and the thickness of the backlight unit.

Among them, a method for solving the former problem has recently been developed in which a highly thermally conductive material such as aluminum is bonded to the back side as a heat dissipating substrate, and the light emitting diode element is directly placed thereon. Heat dissipation substrate. Fig. 6 shows an example of this.

In the example of FIG. 6, the light-emitting diode element 1 is directly placed on the heat-dissipating substrate 3 exposed on the opening 4 of the circuit board 2. Further, the plurality of light-emitting diode elements 1 are each coated with the molding resin 5, and a nickel-plated reflecting plate 6 is formed around the molding resin. In this manner, since heat generated by the light-emitting diode element 1 is conducted to the direct heat-dissipating substrate 3, heat dissipation is improved.

However, in terms of the distribution of the emitted light, it is still identical to the planar light source in which the above-described projectile-type LED or the top-view LED is planarly arranged in a quadratic manner, and there is no improvement.

On the other hand, since a direct-type backlight source for a liquid crystal television requires a large amount of light, a so-called "high-power LED" having a power consumption of 1 W or more is used. Since the high-power LED corresponds to a large amount of heat generated by one chip, the interval between the wafers must be at least 5 mm, preferably 10 mm or more. However, if the interval between the wafers is 5 mm or more, there is a problem that uneven brightness is increased.

Further, in the backlight for a liquid crystal display, three primary colors, that is, three kinds of blue, green, and red LEDs are generally used; if high-power LEDs are arranged at intervals of 5 mm or more, not only the brightness is uneven, but also the mixed colors of the three colors are not Sufficient, there is a problem as a white light source (for example, " Thoroughly inspect high-brightness LED combination and mounting technology", Electronic Journal 97 ^{t h} Technical Symposium, p. 73, issued in February 2005 [Non-Patent Document 1]).

[Patent Document 1] JP-A-2004-233957 (Patent Document 2) JP-A-2000-329940

[Non-Patent Document 1] Electronic Journal 97 ^{t h} Technical Symposium, 73 pages (issued in February 2005)

An object of the present invention is to provide an LED light source which has high front luminance, excellent uniformity of luminance and chromaticity, and can be made thinner.

As a result of continuous research by the present inventors, it has been obtained that "the molding resin which does not cause the complex light-emitting diode element (hereinafter referred to as "LED element") is formed separately for each LED element, and is slid across the plural The LED element can thereby achieve a more uniform brightness distribution of a light source disposed at a distance of 5 mm or more and a secondary element, and can achieve a more easily mixed color when a light source of a different color is used, and the present invention has been completed. That is, the present invention contains, for example, the following items: 1. A light-emitting diode light source, which is a light source for mounting a plurality of light-emitting diode elements to the same circuit substrate, characterized in that a mold (Mold) resin is spanned. It is set to cover a plurality of light-emitting diode elements.

2. The light-emitting diode light source according to claim 1, wherein the distance between the light-emitting diode elements is 5 mm or more.

3. The light-emitting diode light source according to claim 1 or 2, wherein a reflector is formed on the upper portion of the light-emitting diode element.

4. The light-emitting diode light source according to claim 3, wherein the reflective system is a metal foil, a metal film or a white ink.

5. The light-emitting diode light source of claim 4, wherein the metal film is formed by any one of steaming, sputtering, or electroplating.

6. The light-emitting diode light source according to claim 1, wherein the surface of the mold resin is formed into a concave-convex shape.

7. The light-emitting diode light source according to claim 1, wherein the resin film having the uneven shape formed on the surface is laminated on the molding resin.

8. The light-emitting diode light source according to claim 6 or 7, wherein the uneven shape is a quadrangular pyramid.

9. The light-emitting diode light source according to claim 8, wherein the quadrangular pyramid has a bottom edge of 2 mm or less and a height of 1/2 or less of the bottom edge.

10. The light-emitting diode light source according to claim 6, wherein the total surface area of the uneven shape of the surface of the mold resin is 10 to 100% of the surface of the molded resin.

A method of manufacturing a light-emitting diode light source according to claim 1, wherein a mold frame of a resin film is provided on a peripheral portion of the circuit board, and the mold is filled in the mold frame. The resin is cast and the cross-over is made into a plurality of light-emitting diode elements.

A display device, which is characterized in that the light-emitting diode light source according to any one of claims 1 to 10 is used.

A lighting device characterized by using the light-emitting diode light source according to any one of claims 1 to 10.

A liquid crystal display comprising the illumination device according to claim 13 of the patent application.

The LED light source of the present invention is provided with a light source with a spacing of 5 mm or more and a secondary element arrangement, but the brightness distribution thereof can be more uniform, and when different color light sources are used, color mixing can be more easily performed. Further, since the front surface of the light source is uniform in brightness and brightness, and the color mixture is excellent, it can be used for applications such as display devices and illumination devices.

The LED light source of the present invention is a light source in which a plurality of light emitting diode elements are mounted on the same circuit substrate, and is characterized in that the mold resin is bridged over the plurality of light emitting diode elements.

The light-emitting diode elements used in the present invention can be selected depending on the use of the light source. For example, if it is used as a backlight source for a liquid crystal display, it is preferable that the color reproduction range is wider. For example, a plurality of light-emitting diode elements of blue, green, and red are provided on the same substrate.

Further, in the case of a white light source for illumination, in addition to the above-described blue, green, and red colors, a light-emitting diode element of a so-called intermediate color such as yellow or orange may be provided on the same substrate, or blue or A white light source composed of a combination of a near-ultraviolet light-emitting diode element and a phosphor is preferable.

The arrangement interval of the light-emitting diode elements is not particularly limited; however, when a high-brightness high-power element of 1 W or more is used, the heat generation of the element is remarkable. If the arrangement is too close, the local temperature rise of the arrangement space is more obvious. However, the component and the substrate are endangered, and therefore, the distance between the components is preferably 5 mm or more.

It is preferable that the substrate on which the plurality of light-emitting diode elements are provided is composed of a circuit board and a heat-dissipating substrate. The circuit substrate forms a substrate that is electrically connected to the circuit of the light-emitting diode element, and connects the cathode and the anode of the light-emitting diode element. As a method of obtaining a circuit board, for example, a copper foil is bonded to an insulating resin substrate, and the copper foil is etched into a circuit shape. The insulating resin substrate is, for example, a glass epoxy resin (Epoxy) substrate.

The light-emitting diode element is placed in an opening provided with a through hole to expose the heat-dissipating substrate to the circuit board. In this case, it is preferable that the light-emitting portion of the light-emitting diode element protrudes from the surface of the circuit board. Therefore, the thickness of the circuit board should be determined depending on the size of the light-emitting diode element. However, it is preferably 0.1 mm or less, and particularly preferably 50 μm or less.

The heat-dissipating substrate is formed by bonding a substrate having a high thermal conductivity to a side of a circuit board on which a circuit is not formed, and the purpose of which is to dissipate heat generated by the light-emitting diode element. The material of the heat dissipation substrate is, for example, a metal or a highly thermally conductive ceramic. Metals such as aluminum, copper, stainless steel and the like are preferred. High thermal conductivity ceramics such as aluminum nitride are preferred.

The method of disposing a plurality of light-emitting diode elements on a substrate is preferable from the viewpoint of heat dissipation, and the components are not directly packaged in the package, so that the so-called bare chip and the heat-dissipating substrate are directly The method of setting up for contact. Specifically, a through hole is formed in a portion of the circuit board on which the light emitting diode element is provided, and when the circuit board and the heat dissipating substrate are bonded, the heat dissipating substrate is exposed at the through hole, and the opening portion is formed in the opening portion. The upper light emitting diode element is disposed on the heat dissipation substrate. The adhesive means at this time is preferably one having a lower thermal resistance, such as a silver paste, a thermal grease, or the like.

The die-cast resin is preferably a thermosetting transparent resin, particularly preferably a transparent epoxy resin (Epoxy). Transparent epoxy resin, for example, diglycidyl ether of bisphenol A, 2,2-bis(4-glycidyloxy cyclohexyl) Propane), 3,4-epoxycyclohexylmethyl-3,4-epoxyhexane carboxylate, cyclohexene ethylene oxide, Vinylcyclohexene dioxide), 2-(3,4-epoxycyclohexane)-5,5-spiro-(3,4-epoxycyclohexane)-1,3-dioxane (2-(3, 4-epoxycyclohexane)-5,5-spiro-(3,4-epoxycyclohexane)-1,3-dioxane), bis(3,4-epoxycyclohexyl)adipate , 1,2-cyclopropane dicarboxylic acid bisglycidyl ester, triglycidyl isocyanurate, monoallyldiglycidyl isocyanurate, Epoxy resin such as diallylmonoglycidyl isocyanurate, hexahydrophthalic anhydride, methylhexahydrogen Anhydride (methyl hexahydrophthalic anhydride), trialkyl tetrahydrophthalic anhydride (trialkyl tetrahydrophthalic anhydride), (meth water soluble biotinylated (nadic) an acid anhydride) and the like to be made cured. These epoxy resins and hardeners may be used singly or in combination of plural kinds.

The die-cast resin is coated with a plurality of bare wafers, and the method of arranging them is applied, for example, by a coater (dispenser), or by placing a frame around the substrate to fill the resin, and by using a doctor blade or the like. After smoothing, it is hardened and the like. Other methods include forming and adhering on a substrate, for example, using a metal mold.

The molding resin is applied across a plurality of light-emitting diode elements coated on a substrate. Here, the term "crossing to cover" refers to a state in which a plurality of light-emitting diode elements are integrally formed and covered, that is, a state in which a molding resin covering each of the light-emitting diode elements is continuously integrated.

It is also possible to change the color by adding a phosphor required to change the wavelength to the molding resin for the purpose of the light source. The phosphor is an organic phosphor such as an inorganic phosphor such as a yttrium aluminum garnet (YAG) fluorite, a rhodamine or a coumarin.

In order to improve the uniformity of brightness and chromaticity, it is also possible to add a scattering body to the molding resin. Scattered bodies such as acrylic beads, aluminum powder, and the like.

Further, since the refractive index of the mold-cast resin layer in the present invention is larger than that of air, it also functions as a light guide. That is, since a certain proportion of the light emitted from the plurality of LED elements propagates due to total reflection inside the mold resin layer, the brightness is more uniform, and the color mixture is promoted when the colors are different. Therefore, when a diffusion plate required for uniformizing the brightness is provided, the distance can be shortened to 10 mm, and the backlight can be made thinner.

Further, by the formation of the unevenness (wrinkle) on the surface of the molded resin or the formation of the scattered body, the light which is uniformized or mixed can be more efficiently emitted outside the resin.

Further, the LED light source of the present invention preferably has a reflector formed directly above the light-emitting diode element. For example, the reflectance (measured by a portable reflectance meter CM-53P type manufactured by Murakami Color Research Co., Ltd.) is 95% or more, or 97% or more of a regular reflector or a diffuse reflector.

The shape of the reflector may be determined according to the shape of the LED component, but it is preferably a circular plate, and the diameter thereof is preferably 1 to 10 times longer than the length of one side of the LED component, especially 2 to 5 times. optimal.

The material of the reflector is, for example, a metal foil such as aluminum foil, or a metal film such as aluminum, gold, silver or platinum, or the like. A metal foil such as aluminum foil can be attached by a transparent adhesive. Metal films such as aluminum, gold, silver, and platinum can be formed by a pattern of a metal mask by evaporation, sputtering, electroless plating, or the like. Further, white ink (acrylic resin containing titanium oxide or the like) can be applied by a coater or a printing method. Among these methods, the application of white ink is simpler, and therefore it is preferable.

Further, the LED light source of the present invention is preferably formed by forming irregularities (wrinkles) on the surface of the mold resin. The unevenness (wrinkle) shape of the surface of the molded resin is, for example, a hemispherical shape, a rectangular parallelepiped shape, a conical shape, a polygonal pyramid shape, or the like. Preferably, it is a polygonal pyramid, and particularly a quadrangular pyramid is preferred. The shape of the quadrangular pyramid is preferably 2 mm or less at the bottom and 1/2 or less at the bottom. By forming the unevenness (wrinkle) shape on the surface of the molded resin, the efficiency of extracting light from the molding resin can be improved, and as a result, the brightness of the light source can be expected to be improved.

It is preferable that the shape of the convex portion starting from the quadrangular pyramid is formed adjacent to each other. The sum of the areas of the bottoms of the convex shape is preferably at least 10% or more of the area of the surface on which the shape is formed, and more preferably 50% or more.

The method of forming the unevenness (wrinkle) shape may be performed by applying irregularities (wrinkles) directly onto the molding resin or by laminating a resin film having a concave-convex (wrinkle) shape on the molding resin.

The LED light source of the present invention can be applied to a light source for illumination, a backlight source for a liquid crystal display, or the like. As a light source for illumination, a blue light-emitting diode having a dominant wavelength of 420 mm to 480 mm is used as a light-emitting diode element, and a part of the blue light is absorbed, and a phosphor emitting a longer-wavelength fluorescent light is used. It is preferable to add an appropriate amount to the mold resin to form a white light source having high color rendering properties. When a light source for a backlight for a liquid crystal display is used, a diode that emits light of at least three colors of red, green, and blue is used.

Hereinafter, the present invention will be specifically described by way of examples, but the invention is not limited to the examples described below.

First embodiment

As shown in the schematic plan view of Fig. 1 and the A-A cross-sectional view of Fig. 1 of the second drawing, the heat dissipating substrate 3 is an aluminum substrate having a size of 80 × 120 mm and a thickness of 1.2 mm; and the heat dissipating substrate On the other hand, an insulating adhesive resin film having a thickness of 20 μm and a copper foil having a thickness of 18 μm on one side was attached to each other to fabricate a circuit board 2 having a thickness of about 30 μm. A circuit pattern is formed by etching on the copper foil portion. Further, in the case where the light-emitting diode element (LED wafer) 1 is provided, six (three × 2 segments) 5 mm square through-opening portions 4 are punched out.

Next, silver phosphor (TC-3600, manufactured by Hitachi Chemical Co., Ltd.) was used, and six light-emitting diode elements 1 were placed on the opening of the circuit board to form an LED substrate. The size of the light-emitting diode element 1 is 1 mm square, and is arranged in two rows from left to right in order of red (TOA-1000, manufactured by Showa Denko Co., Ltd.), green (manufactured by ITSWELL Co., Ltd.), and blue (manufactured by ITSWLL Co., Ltd.). Then, on the LED substrate, a frame having the same outer shape as the LED substrate and having a polypropylene sheet of 2 mm thick (opening portion: 70 mm × 90 mm) was provided, and a transparent epoxy resin was used as a coater. 5 (manufactured by SANYU REC Co., Ltd., NLD-L-645) was dropped into a frame, and then cured at 130 ° C to form a resin mold portion 5. Next, after being placed on the LED substrate, a metal mask for positioning an opening having a diameter of 2 mm is placed directly above the light emitting diode element (LED wafer), and an ion laminator is used ( I-B3) A platinum film having a thickness of 10 nm was formed to form a reflector 7 to form a light source. Reflectivity of reflector 7 measured by Murakami Color Technology Research Institute Co., Ltd. Portable Reflectance Meter CM-53P (measurement optical system: 0° vertical illumination 45° circumference light; light source: tungsten lamp) It is 95%.

The heat-dissipating substrate side of the obtained four LED light sources was bonded to the aluminum plate having a thickness of 1.2 mm as shown in the pattern diagram of Fig. 3 with a high thermal conductivity 矽 grease (manufactured by Shin-Etsu Chemical Co., Ltd., Oil compound G-751). A bottom surface of a box type container for a backlight of 270×200 mm and a depth of 30 mm was formed. Then, a reflective film (TORAY Co., Ltd., LUMRIROR) is attached to the surface of the LED substrate other than the resin molding portion 5 of the LED substrate and the inner surface of the backlight container. Then, a distance of 10 mm was used, and a polycarbonate (Polycarbonate) diffusion plate (PANLITE) having the same outer dimensions as the backlight container was used as a cover to produce a backlight unit. All blue LED components are energized at 300 mA, and all green and red LED components are energized at 350 mA; and for the luminance and chromaticity coordinates of the nine locations shown in Figure 4, The measurement was carried out using a spectroradiometer (spectroscopic type) CS-1000S manufactured by KONICA-MINOLTA HOLDINGS Co., Ltd. The average luminance is about 6000 cd/m ² , and the luminance unevenness ({(maximum measure - minimum brightness) / average brightness} x 100%) is about 13%. Moreover, the average of the chromaticity coordinates is x=0.31, y=0.30, and the chromaticity unevenness (the difference between the maximum value and the minimum value of the chromaticity coordinates in the uniform chromaticity diagram) is Δu=0.005, Δv= 0.005.

Second embodiment

The backlight unit was produced in the same manner as in the first embodiment except that the reflective system was formed by applying a gloss ink (MIR-9100, manufactured by Imperial Ink Co., Ltd.) to a thickness of 30 μm. The measurement similar to that of the first embodiment was carried out, and it was found that the reflectance of the reflector 7 was 97%.

As a result of performing the same lighting test as in the first embodiment, the average luminance was 11,000 cd/m ² and the luminance unevenness was 13%. Further, the average of the chromaticity coordinates is x = 0.31, y = 0.30, and the chromaticity unevenness is Δu = 0.005, Δv = 0.004.

Third embodiment

An acrylic resin plate (size: 70 mm × 90 mm, thickness: 1 mm) having a quadrangular pyramid-shaped convex portion having a bottom edge of 2 mm and a height of 1 mm was integrally formed, and was attached to the four LEDs produced in the first embodiment. On the resin molding part of the light source. As a result of performing the same lighting test as in the first embodiment, the average luminance was 15600 cd/m ² and the luminance unevenness was 15%. Further, the average of the chromaticity coordinates is x = 0.31, y = 0.30, and the chromaticity unevenness is Δu = 0.005, Δv = 0.004.

In any of the above-described first to third embodiments, the resin molding portion 5 is protruded from the surface of the LED substrate. However, as shown in FIG. 5, the height of the resin molding portion 5 may be set on the LED substrate. The thickness of the reflecting plate 6 on the outer periphery is the same, that is, the surface of the reflecting plate 6 and the surface of the resin molding 5 are approximately one plane, and another embodiment. Here, the reflector 7 can be formed as appropriate in the same manner as in the first embodiment and the second embodiment directly above the light-emitting diode element (LED wafer). Further, although not shown, a seat can be provided on the heat dissipation substrate 3. In this seat The interior of the light-emitting diode component is mounted on the base Inside, a resin molding portion 5 which is slightly planar with respect to the surface of the heat-radiating substrate 3 is formed to cover the light-emitting diode element as another embodiment. At this time, it is preferable that the arrangement interval of the adjacent light-emitting diode elements is 5 mm or more.

1. . . Light-emitting diode component

2. . . Circuit substrate

3. . . Heat dissipation substrate

4. . . Circuit board opening

5. . . Resin molding (molding resin)

6. . . Reflector forming plate

7. . . Reflector

Fig. 1 is a schematic plan view showing an LED light source of an embodiment of the present invention.

Fig. 2 is a sectional view taken along line A-A of Fig. 1.

Figure 3 is a schematic plan view of a backlight using the light source of the present invention.

Fig. 4 is a plan view showing the position at which the brightness is measured.

Fig. 5 is a schematic cross-sectional view showing an LED light source according to another embodiment of the present invention.

Figure 6 is a schematic cross-sectional view of a conventional LED light source.

1. . . Light-emitting diode component

2. . . Circuit substrate

3. . . Heat dissipation substrate

4. . . Circuit board opening

5. . . Resin molding (molding resin)

7. . . Reflector

Claims (11)

A light-emitting diode light source is a light source for mounting a plurality of light-emitting diode elements to the same circuit substrate, characterized in that a mold (Mold) resin is spanned to cover a plurality of light-emitting diode elements, and a light-emitting diode A reflector is formed on the upper portion of the body member, and any one of a reflective metal foil, a metal film, or a white ink is formed, and the metal film is formed by any one of steaming, sputtering, or plating. The light-emitting diode light source according to claim 1, wherein the distance between the light-emitting diode elements is 5 mm or more. The light-emitting diode light source according to the first aspect of the invention, wherein the surface of the die-cast resin has an uneven shape. The light-emitting diode light source according to the first aspect of the invention, wherein the resin film having the uneven shape on the surface is laminated on the mold resin. The light-emitting diode light source according to claim 3, wherein the uneven shape is a quadrangular pyramid. The light-emitting diode light source according to claim 5, wherein the quadrangular pyramid has a bottom side of 2 mm or less and a height of 1/2 or less of the bottom side. The light-emitting diode light source according to the third aspect of the invention, wherein the total surface area of the uneven shape of the surface of the mold resin is 10 to 100% of the surface of the mold resin. A method of manufacturing a light-emitting diode light source according to the first aspect of the invention, characterized in that a molded frame of a resin film is provided on a peripheral portion of a circuit board, and a mold resin is filled in the mold frame. The cross-over is set to cover a plurality of light-emitting diode elements. A display device characterized by using the light-emitting diode light source according to any one of claims 1 to 7. An illumination device characterized by using the light-emitting diode light source according to any one of claims 1 to 7. A liquid crystal display comprising the illumination device described in claim 10 of the patent application.