JP2007096207A - Led light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for miniaturizing an LED light emitting device and improving heat dissipation thereof. <P>SOLUTION: An LED device includes a thermally conductive frame for mounting an LED chip, a pair of lead frames to which the electrodes of the LED chip are connected, and a reflector covering a part of the thermally conductive frame and a part of the lead frame and forming a cup-like reflecting surface around the LED chip wherein the light exit direction of the LED chip is substantially perpendicular to the elongating direction of the lead frame. Exposed portion of the thermally conductive frame is a heat sink having a LED light source in which a fitting portion is formed, and a portion engaging with the fitting portion of the LED light source. The heat sink is arranged substantially in parallel with the lead frame and provided with a protrusion secured to a wiring board to which the lead frame is secured. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an LED light emitting device. Specifically, the present invention provides a technique related to the downsizing and improvement of heat dissipation of an LED light emitting device.

  In a backlight of a liquid crystal display or the like, an LED is used as a light source for obtaining planar light (or linear light). In the configuration of the edge light system generally adopted, the light from the LED light source is introduced from the end face (edge) of the light guide plate and taken out from the upper surface of the light guide plate. In such an edge light system, an LED light source is disposed in the vicinity of the end face of the light guide plate in order to efficiently introduce light into the light guide plate. Along with this, wiring boards and connectors on which the LED light source is mounted are also arranged in the vicinity of the end face of the light guide plate, but there are many cases where sufficient space for arranging the wiring boards and connectors cannot be secured. Design becomes very difficult.

On the other hand, with the increase in brightness of the LED light source, a positive heat dissipation measure is required. Conventionally, as a heat dissipation measure, a method of installing a heat sink via a heat conductive material such as a metal layer behind the LED light source is generally used (see, for example, Patent Documents 1 to 3).
JP 2004-265626 A Special Table 2004-528698 JP 2005-513815 A

  However, in the conventional heat sink mounting structure, it is difficult to mount the heat sink while positioning the LED light source.

  An object of the present invention is to provide an LED lamp capable of improving the positional accuracy of the LED lamp by simply fixing the LED lamp to another member and appropriately illuminating the target portion.

In order to achieve the above object, the invention described in claim 1
An LED chip;
A thermally conductive frame on which the LED chip is mounted;
A pair of lead frames to which the electrodes of the LED chip are connected;
A reflector that covers a part of the thermally conductive frame and a part of the lead frame and forms a cup-shaped reflective surface around the LED chip;
The light emitting direction of the LED chip is substantially perpendicular to the extending direction of the lead frame;
An LED light source in which the exposed portion of the heat conductive frame forms a fitting portion;
A heat sink having an engaging portion that engages with the fitting portion of the LED light source,
The gist of the invention is that the heat sink includes a mounting region that is disposed substantially in parallel with the lead frame and is fixed to a wiring board to which the lead frame is fixed.

  According to this configuration, since the heat sink and the LED light source are both fixed to the wiring board, and the heat sink and the LED light source are engaged in the vicinity of the reflector, the LED light source and the heat sink can be fixed to the wiring board with high accuracy while being easily integrated.

  The LED light-emitting device according to claim 2 is characterized in that the engaging portion of the heat sink is a groove, and the fitting portion of the thermally conductive frame has a convex structure that engages with the groove. .

  According to this configuration, the LED light source and the heat sink can be easily engaged.

  The LED light-emitting device according to claim 3, wherein the thermally conductive frame is arranged as a leg extending from the reflector, and the leg is inserted into a groove formed as the engaging portion of the heat sink. To do.

  According to this configuration, since the heat conductive frame of the LED light source can be formed only by pressing the plate material, the LED light source can be easily manufactured, and the LED light source and the heat sink can be easily engaged.

  ADVANTAGE OF THE INVENTION According to this invention, the position accuracy of an LED light-emitting device improves by fixing an LED light-emitting device with a wiring board easily, and the LED light-emitting device which can illuminate the target site | part appropriately can be provided.

Hereafter, each element which comprises this invention is demonstrated.
(LED chip)
The kind of LED chip is not particularly limited, and an arbitrary configuration can be adopted. For example, an LED chip including a group III nitride compound semiconductor layer can be used. Group III nitride compound semiconductor is represented by the general formula _{Al X Ga Y In 1-X} -Y N (0 ≦ X ≦ 1,0 ≦ Y ≦ 1,0 ≦ X + Y ≦ 1), AlN, GaN and It includes a so-called binary system of InN, a so-called ternary system of Al _x Ga _1-x N, Al _x In _1-x N, and Ga _x In _1-x N (where 0 <x <1).

  The group III nitride compound semiconductor may contain an arbitrary dopant. As the n-type impurity, silicon (Si), germanium (Ge), selenium (Se), tellurium (Te), carbon (C), or the like can be used. As the p-type impurity, magnesium (Mg), zinc (Zn), beryllium (Be), calcium (Ca), strontium (Sr), barium (Ba), or the like can be used. Although the group III nitride compound semiconductor can be exposed to electron beam irradiation, plasma irradiation or furnace heating after doping with p-type impurities, it is not essential.

  Group III nitride compound semiconductors include metalorganic vapor phase epitaxy (MOCVD), well-known molecular beam crystal growth (MBE), halide vapor phase epitaxy (HVPE), sputtering, ion plating. It can also be formed by a ting method or the like.

  The material of the substrate on which the group III nitride compound semiconductor layer is grown is not particularly limited as long as the group III nitride compound semiconductor layer can be grown. For example, sapphire, gallium nitride, spinel, silicon, silicon carbide, Examples of the substrate material include zinc oxide, gallium phosphide, gallium arsenide, magnesium oxide, manganese oxide, and a group III nitride compound semiconductor single crystal. Among these, it is preferable to use a sapphire substrate, and it is more preferable to use the a-plane of the sapphire substrate.

  The emission color of the LED chip is appropriately selected according to the purpose. For example, it is selected according to a desired emission color such as blue, red, and green. A plurality of LED chips can also be used. In that case, it is possible to combine a plurality of different types of LED chips as well as a combination of the same types of LED chips. For example, one type or two or more types of LED chips having different emission colors are used so that white light is finally obtained.

  In one embodiment of the present invention, an LED chip and a phosphor are used in combination. Then, white light is obtained by mixing (mixing) the light of the LED chip and the fluorescence generated from the phosphor using a part of the light of the LED chip. For example, the phosphor is contained in a sealing member described later.

  The kind of fluorescent substance is not specifically limited, It can employ | adopt regardless of an organic type and an inorganic type. Phosphors having various fluorescent colors can be adopted. For example, phosphors having red, green, or blue fluorescent colors, which are the three primary colors of light, as well as phosphors that fluoresce intermediate colors thereof (for example, yellow fluorescent materials) Body). A plurality of phosphors can be used in combination. For example, a red phosphor, a green phosphor, and a blue phosphor can be mixed and used.

The LED chip is mounted on the thermally conductive frame so that its optical axis is perpendicular to the direction of extension of the lead frame. As a result, in the LED light emitting device of the present invention, light is emitted in a direction perpendicular to the legs of the lead frame.
(Thermal conductive frame)
The thermally conductive frame functions as a heat sink for dissipating heat from the LED chip. The thermally conductive frame includes a region where the LED chip is mounted. A part of the heat conductive frame is covered with a reflector. That is, it is configured integrally with the reflector. In the heat conductive frame, a portion protruding from the reflector, that is, an exposed portion (fitting portion) becomes a heat transfer portion to the heat sink, and the heat of the LED is transferred to the heat sink there. In order to achieve efficient heat transfer, the proportion of the fitting portion should be increased.

  Examples of the material of the heat conductive frame include aluminum, aluminum alloy, copper, and copper alloy.

(heatsink)
The protrusions fixed to the wiring board formed in the mounting area of the heat sink are preferably formed at two places on the left and right. According to such a form, when mounting the device, the fixing to the wiring board can be performed at a total of four locations including the tips of the pair of lead frames and the fixing protrusions of the heat sinks. Therefore, since the fixing to the wiring board by the mounting area of each heat sink and the fixing by the lead are performed by substantially four fixing points of the reflector as the light emitting source, mounting with higher reliability can be achieved. As a result, the apparatus can be mounted in a stable posture, and mounting accuracy and mounting reliability are improved.

Examples of the heat sink material include aluminum, aluminum alloy, copper, and copper alloy.
(Lead frame)
The LED light-emitting device of the present invention includes a pair of lead frames. The electrode of the LED chip is electrically connected to the lead frame. A part of the lead frame is covered with a reflector.

The LED light-emitting device of the present invention is suitable as a light source for a backlight using a light guide plate, taking advantage of the feature that the light emission direction is perpendicular to the extension direction of the lead frame. When used in such applications, the light guide plate is disposed in parallel with a predetermined interval with respect to the wiring board on which the LED light emitting device is mounted. That is, the light guide plate is disposed on the optical axis of the LED light emitting device. In order to realize such an arrangement mode, the length of the lead leg of the LED light-emitting device is preferably made longer than that of a normal LED light-emitting device.
(Reflector)
The reflector (reflecting member) covers a part of the heat conductive frame and a part of the pair of lead frames, and forms a cup-shaped reflecting surface around the LED chip. The reflecting surface reflects light emitted from the LED chip laterally or obliquely upward, and changes the direction of the light in the light extraction direction. The cup shape here refers to a shape surrounding a space where the area of the cross section perpendicular to the optical axis of the LED chip increases continuously or stepwise from the bottom side toward the light extraction direction of the light emitting device. The shape of the reflecting surface is not particularly limited as long as such a condition is satisfied.

  The material for forming the reflector is not particularly limited, and an appropriate material can be selected and used from metals, alloys, synthetic resins, and the like. However, the surface facing the LED chip, that is, the reflecting surface is required to be reflective to the light of the LED chip. For example, the reflector can be made of a resin having a high light reflectance such as a white resin. Resin-made reflectors have the advantage of being easy to mold.

On the other hand, when a material that does not have high reflectivity for the light of the LED chip is selected as the material of the reflector, a layer having a high reflectance is formed at least on the surface of the region that becomes the reflective surface. Such a reflective layer can be made of, for example, one or more metals selected from Al, Ag, Cr, Pd, and the like, or alloys thereof. In particular, the reflective layer is preferably made of Al or an alloy thereof. For the formation of the reflective layer, methods such as vapor deposition, coating, and printing can be employed. In particular, according to the vapor deposition method, a reflective layer having a uniform thickness and a smooth surface can be easily formed. The reflective layer does not necessarily have to be formed on the entire inner peripheral surface of the cup-shaped part, but is emitted laterally or obliquely upward from the LED chip so that the effect of improving the luminous efficiency by the reflective layer is maximized. It is preferable to provide a reflection layer on the entire area irradiated with the light.
(Sealing member)
The cup-shaped portion of the reflector may be filled with a material for sealing the LED chip. The sealing member thus formed is provided mainly for the purpose of protecting the LED chip from the external environment. As a material for the sealing member, it is preferable to adopt a material that is transparent to the light of the LED chip and is excellent in durability, weather resistance, and the like. For example, an appropriate material can be selected from silicone (including silicone resin, silicone rubber, and silicone elastomer), epoxy resin, urea resin, glass and the like in relation to the emission wavelength of the LED chip. When the light of the LED chip contains light in a short wavelength region, ultraviolet degradation is a problem. Therefore, it is preferable to employ a material having high resistance to ultraviolet degradation such as silicone.

  As the material of the sealing member, an appropriate material is adopted in consideration of the light transmittance of the LED chip, the hardness in the cured state, the ease of handling, and the like.

  A phosphor can also be contained in the sealing member. By using the phosphor, part of the light from the LED chip can be converted into light having a different wavelength, and the emission color of the light emitting device can be changed or corrected. Any phosphor can be used as long as it can be excited by light from the LED chip, and the light emission color, durability, and the like of the light emitting device are considered in the selection. The phosphor may be uniformly dispersed in the sealing member or may be localized in a part of the region. For example, by localizing the phosphor in the vicinity of the LED chip, the light emitted from the LED chip can be efficiently irradiated onto the phosphor.

  A plurality of types of phosphors can be combined and contained in the sealing member. In this case, a phosphor that emits light when excited by light from the LED chip can be used in combination with a phosphor that emits light when excited by light from the phosphor.

  A light diffusing material can be contained in the sealing member to promote the diffusion of light within the sealing member, thereby reducing light emission unevenness. In particular, in the configuration using a phosphor as described above, such a light diffusing material is used in order to promote the color mixture of the light from the LED chip and the light from the phosphor and reduce the unevenness of the emission color. preferable.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(First embodiment)
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment in which an LED light emitting device of the invention is embodied will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing a first embodiment of the present invention, and FIG. 2 is a sectional view thereof.

  The LED light emitting device includes an LED light source 10 and a heat sink 20. The LED light source 10 is composed of a white resin reflector 11 having good light reflectivity, a metallic thermal conductive frame 13, and a gallium nitride compound semiconductor fixed on the thermal conductive frame 13 with a transparent paste (adhesive). LED chip 16, a pair of leads 14 for supplying power to the LED chip, and a seal made of silicone filling a concave portion of the reflector 11 and covering part of the pair of leads 14 of the LED chip 16 and the heat conductive frame 13 Made of resin 12.

  The heat sink 20 includes a main body 21, two protrusions 22 projecting downward from the lower end of the main body 21, and a groove 23 into which a part of the heat conductive frame 13 of the LED light source 10 provided on one surface of the main body 21 is inserted. And radiating fins 24 provided on the other surface of the main body 21.

  A fitting portion 15 having a substantially triangular cross section is formed on a surface of the heat conductive frame 13 where the reflector 11 is not formed, in a groove 23 having substantially the same cross section as the fitting portion 15 of the heat conductive frame 13 provided on the heat sink 20. It has a structure to be inserted.

  As the LED chip 16 of the LED light source 10, one emitting blue light is used, and Ce: YAG phosphor is dispersed and mixed in the sealing resin 12 made of silicone. For this reason, when the LED chip 16 emits blue light, the phosphor dispersed and mixed in the sealing resin 12 absorbs part of the blue light, converts the color into yellow light, and converts the remaining blue light and yellow light. White light is emitted by mixing colors.

  As shown in FIG. 2, the LED light emitting device has holes 32 and 33 for fixing the leads 14 and the protrusions 22 provided on the wiring board 30 with the fitting portion 15 of the LED light source 10 and the groove 23 of the heat sink 20 inserted. Insert into and fix with solder etc.

  For this reason, since the four places of the protrusion 22 of the heat sink 20 and the lead 14 of the LED light source 10 serve as fixing points to the wiring board 30, the direction of light emitted from the reflector 11 is stabilized.

(Second Embodiment)
Hereinafter, a second embodiment of the LED light-emitting device of the present invention will be described in detail with reference to the drawings.

    FIG. 3 is a perspective view showing a second embodiment of the present invention.

  The LED light emitting device includes an LED light source 50 and a heat sink 60. The LED light source 50 is made of a white resin reflector 51 with good light reflectivity, a metallic heat conductive frame 53, and a gallium nitride compound semiconductor fixed on the heat conductive frame 53 with a transparent paste (adhesive). An LED chip and a pair of leads 54 for supplying power to the LED chip, and a sealing resin 52 made of silicone filled in the concave portion of the reflector 51 and covering a part of the pair of leads 54 of the LED chip and the heat conduction frame 53 .

  The heat sink 60 includes a main body 61, two protrusions 62 protruding downward from the lower end of the main body 61, and a groove 63 into which a part of the heat conductive frame 53 of the LED light source 50 provided on one surface of the main body 61 is inserted. And radiating fins 64 provided on the other surface of the main body 61.

  On the surface of the heat conduction frame 53 where the reflector 51 is not formed, there is a step with the heat conduction frame main body 55, and a fitting portion 56 that extends in the width direction of the reflector 51 is formed. It has a structure that is inserted into a groove 63 having substantially the same cross section as the fitting portion 56 of the conductive frame 53.

  The LED chip of the LED light source 10 is one that emits near-ultraviolet light, and the sealing resin 52 made of silicone has a red phosphor, blue phosphor, green that uses near-ultraviolet light as excitation light. The phosphor is dispersed and mixed. For this reason, when the LED chip emits near-ultraviolet light, each phosphor dispersed and mixed in the sealing resin 52 absorbs near-ultraviolet light, converts the color into red, blue, and green, and emits white light by color mixture of light. To do.

  The LED light-emitting device of 2nd Embodiment is used by the method as shown in FIG. 2 similarly to 1st Embodiment.

The perspective view which showed the 1st Embodiment of this invention Sectional drawing which showed the 1st Embodiment of this invention The perspective view which showed the 2nd Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... LED light source, 11 ... Reflector, 13 ... Heat conduction frame, 15 ... Fitting part, 20 ... Heat sink, 22 ... Protrusion.

Claims (3)

An LED chip;
A thermally conductive frame on which the LED chip is mounted;
A pair of lead frames to which the electrodes of the LED chip are connected;
A reflector that covers a part of the thermally conductive frame and a part of the lead frame and forms a cup-shaped reflective surface around the LED chip;
The light emitting direction of the LED chip is substantially perpendicular to the extending direction of the lead frame;
An LED light source in which the exposed portion of the heat conductive frame forms a fitting portion;
A heat sink having an engaging portion that engages with the fitting portion of the LED light source,
The LED heat-emitting device, wherein the heat sink is disposed substantially in parallel with the lead frame and includes a mounting region fixed to a wiring board to which the lead frame is fixed.   2. The LED light emitting device according to claim 1, wherein the engaging portion of the heat sink is a groove, and the fitting portion of the thermally conductive frame has a convex structure that engages with the groove.   2. The LED light emitting device according to claim 1, wherein the thermally conductive frame is disposed as a leg extending from the reflector, and the leg is inserted into a groove formed as the engaging portion of the heat sink.

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