JP2009302186A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To conduct heat of a light emission module to a heat dissipation member with more efficiency. <P>SOLUTION: The light emitting device includes a substrate 10, a reflector 12 which is provided on a first surface 11 of the substrate 10 and has a plurality of openings 13 formed, LEDs 14 disposed in the openings 13 of the reflector 12 respectively, a heat sink 2 in contact with a second surface 16 of the substrate 10 on the opposite side from the first surface 11, and a screw 31 which penetrates the substrate 10 such that one end reaches the reflector 12 and the other end reaches the heat sink 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting device, and more particularly, to a light emitting device provided with a heat radiating means.

  In recent years, many light-emitting devices using light-emitting elements such as light-emitting diodes (hereinafter sometimes referred to as “LEDs”) as light sources have been developed. Some of these light emitting devices are provided with heat radiating means such as a heat sink in order to maintain the temperature of the light emitting element below a predetermined temperature.

For example, in Patent Document 1, a back surface of a substrate on which a plurality of light emitting elements are two-dimensionally arranged and a surface of a heat sink are brought into contact with each other, and a convex portion formed on the back surface of the substrate is formed on the surface of the heat sink. A light emitting device inserted in a concave part is described. In Patent Document 1, since an air layer or an insulator having a much higher thermal resistance than the heat sink is not interposed between the back surface of the substrate and the heat sink surface, heat is directly transmitted from the substrate to the heat sink, which is more efficient. Describes that heat can be dissipated. Further, it is described that, by inserting the convex portion into the concave portion, more heat can be released to the heat sink from the portion where the convex portion side wall and the concave portion side wall are in contact with each other. Patent Document 1 describes that the convex portion is preferably formed of the same material as the coating resin layer covering the light emitting element.
JP 2002-33011 A ([0023] [0027] [0030] FIG. 1)

  Certainly, not only the back surface of the substrate and the surface of the heat sink are brought into contact but also the heat transfer efficiency to the heat sink is improved by inserting the convex portion formed on the back surface of the substrate into the concave portion formed on the surface of the heat sink. However, in the light emitting device disclosed in Patent Document 1, the convex portion formed on the back surface of the substrate is made of resin, and the thermal conductivity is not necessarily high.

  An object of the present invention is to realize a light emitting device having a structure capable of more efficiently transferring heat of a light emitting module to a heat radiating member on the assumption that a reflector is provided around the light emitting element.

  The light emitting device of the present invention includes a substrate, a reflector provided on the first surface of the substrate, in which a plurality of openings are formed, a light emitting element disposed in each of the openings of the reflector, and a first of the substrate The heat-dissipating member is in contact with the second surface opposite to the surface, and the heat-transfer member passes through the substrate, has one end reaching the reflector, and the other end reaching the heat-dissipating member.

  According to the present invention, the heat of the light emitting module is efficiently transferred to the heat dissipation member via the heat transfer member.

(Embodiment 1)
Hereinafter, an example of an embodiment of a light emitting device of the present invention will be described in detail with reference to FIG. FIG. 1 is a schematic cross-sectional view showing the structure of the light emitting device according to this embodiment.

  The light emitting device according to the present embodiment includes a light emitting module 1 and a heat sink 2 as a heat radiating member that radiates heat of the light emitting module 1.

  The light emitting module 1 includes a substrate 10, a reflector 12 provided on the first surface 11 of the substrate 10, and an LED 14 disposed in an opening 13 formed in the reflector 12. The substrate 10 is one of basic members constituting the light emitting module 1. In addition, the substrate 10 serves as a heat transfer unit that transfers heat generated from the LED 14 to the heat sink 2 and also serves as a heat release unit that dissipates heat generated from the LED 14 into the air. From the viewpoint of heat transfer and heat dissipation, the material of the substrate 10 is preferably a metal material having high thermal conductivity, such as aluminum (239 W / mk), copper (392 W / mk), or alloys thereof. Is suitable.

  Although not shown in the drawing, the insulating layer, the wiring layer, and the protective layer are laminated in this order on the first surface 11 of the substrate 10. The insulating layer is formed of an insulating material such as a glass epoxy resin obtained by dispersing glass fibers in an epoxy resin. The wiring layer is a layer made of a wiring pattern drawn on the insulating layer. The wiring pattern is drawn with a conductive material (for example, copper). The protective layer is formed of an insulating material such as a heat resistant resin. Further, the protective layer is etched in a predetermined pattern, and the lower wiring layer is partially exposed.

  A reflector 12 is provided on the first surface 11 of the substrate 10 (more specifically, the surface of the protective layer). The reflector 12 is a metal member made of aluminum, copper, or an alloy thereof. A plurality of (two in this example) openings 13 are formed adjacent to the reflector 12, and the LEDs 14 are disposed in the openings 13. Furthermore, the inner peripheral surface of each opening 13 of the reflector 12 is a tapered surface that is inclined so as to expand outwardly as the distance from the substrate 10 increases. In other words, each opening 13 in which the LED 14 is disposed has a mortar shape that increases in diameter as it leaves the substrate 10 (upward).

  Further, each opening 13 is filled with a transparent resin 15 containing a fluorescent material (not shown) that is excited by light emitted from the LED 14 and emits light having a wavelength different from that of the light emitted from the LED 14. Therefore, the light emitted from the LED 14 and wavelength-converted by the fluorescent material is directly emitted to the outside of the opening 13, is reflected by the inner peripheral surface of the opening 13 and is emitted to the outside of the opening 13. That is, the inner peripheral surface of the opening 13 serves as a reflecting surface. Therefore, the light reflectance may be increased by applying a white paint on the inner peripheral surface of the opening 13.

  The heat sink 2 has a flat mounting surface 21 on which the light emitting module 1 is mounted, and a plurality of fins 22 project from a surface opposite to the mounting surface 21. The heat sink 2 is made of aluminum, magnesium, copper, iron, or an alloy thereof. The light emitting module 1 is mounted on the mounting surface 21 of the heat sink 2 and integrated with the heat sink 2. Specifically, the light emitting module 1 is mounted on the heat sink 2 such that the second surface 16 (the surface opposite to the first surface 11) of the substrate 10 is in close contact with the mounting surface 21 of the heat sink 2.

  Further, the reflector 12, the substrate 10 and the heat sink 2 are formed with through holes 30 penetrating them, and the light emitting module 1 and the heat sink 2 are fixed by metal screws 31 screwed into the through holes 30. Has been. More specifically, a female screw is formed on the inner peripheral surface of the through hole 30, and a male screw formed on the shaft portion of the screw 31 is screwed to the female screw on the inner peripheral surface of the through hole. . As a result, the heat of the light emitting module 1 is transmitted through the path of the reflector 12 → the screw 31 → the heat sink 2. In other words, the heat of the light emitting module 1 is transmitted to the heat sink 2 without passing through the substrate 10. Of course, the heat of the light emitting module 1 is also transmitted through the path of the reflector 12 → the substrate 10 → the heat sink 2. However, contact thermal resistance exists between the reflector 12 and the substrate 10 and between the substrate 10 and the heat sink 2. Therefore, in the light emitting device of the present example capable of transferring heat to the heat sink 2 without going through the substrate 10, the heat of the light emitting module 1 can be more efficiently transferred to the heat sink 2 and dissipated.

  Further, the main heat source of the light emitting module 1 is the LED 14. Therefore, in the light emitting device of this example, the screw 31 is passed between the two openings 13 in which the LEDs 14 are arranged. More specifically, the screw 31 is penetrated in the position equidistant from each LED14. Thereby, the heat generated from each LED 14 is more efficiently transmitted to the heat sink 2 via the screw 31. In addition, the position through which the screw 31 passes is the center of the substrate 10 and the second surface 16 of the substrate 10 and the mounting surface 21 of the heat sink 2 are not fixed. In other words, the substrate 10 is fixed to the heat sink 2 by one screw 31 penetrating the center. Therefore, when the substrate 10 expands due to heat, the substrate 10 expands outward with the penetration position of the screw 31 as the center. That is, even if the thermal expansion coefficients of the substrate 10 and the heat sink 2 are different, the expansion of the substrate 10 is not hindered, and problems such as warpage of the substrate 10 and a decrease in adhesion with the heat sink 2 do not occur.

  From the description so far, the screw 31 has at least two roles of a role as a fixing member that integrates the light emitting module 1 and the heat sink 2 and a role as a heat transfer member that transmits heat of the light emitting module 1 to the heat sink 2. You should be able to understand that

  In the light emitting device according to this embodiment, the screw 31 is screwed into the through hole 30 from the light emitting module 1 side to the heat sink 2 side, but is screwed from the heat sink 2 side to the light emitting module 1 side. May be. The screw 31 may be a tapping screw. In this case, it is not necessary to previously form a female screw on the inner peripheral surface of the through hole 30.

  Further, heat radiation grease or the like may be applied between the second surface 16 of the substrate 10 and the mounting surface 21 of the heat sink 2. When the thermal expansion coefficients of the substrate 10 and the heat sink 2 are substantially the same, or when the fixing strength between the substrate 10 and the heat sink 2 is important, the second surface 16 of the substrate 10 and the mounting surface 21 of the heat sink 2 are bonded. It may be fixed with an agent or the like. In the light emitting device according to the present embodiment, all of the reflector 12, the substrate 10, and the screw 31 are made of metal in order to increase the thermal conductivity as much as possible. However, it is not essential to make all of the metal.

(Embodiment 2)
Hereinafter, another example of the embodiment of the light emitting device of the present invention will be described in detail with reference to FIG. FIG. 2 is a schematic cross-sectional view showing the structure of the light emitting device according to this embodiment. The basic structure of the light-emitting device according to this embodiment is the same as that of the light-emitting device according to Embodiment 1. Therefore, the same components as those of the light-emitting device according to Embodiment 1 are denoted by the same reference numerals in FIG.

  In the light emitting module 1 constituting the light emitting device according to the present embodiment, a through hole 40 penetrating the substrate 10 and the reflector 12 is formed, and a protrusion protruding from the mounting surface 21 of the heat sink 2 in the through hole 40. Part 41 is inserted. The convex portion 41 is integrally formed as a part of the heat sink 2. Therefore, the heat of the light emitting module 1 is transmitted from the reflector 12 to the entire heat sink 2 via the convex portion 41 to be dissipated. That is, also in the light emitting device according to the present embodiment, the heat of the light emitting module 1 is transferred to the heat sink 2 without passing through the substrate 10.

  Moreover, the convex part 41 has penetrated between the two opening parts 13 in which LED14 is arrange | positioned similarly to the screw 31 shown in FIG. More specifically, the convex portion 41 penetrates the substrate 10 and the reflector 12 at a position equidistant from each LED 14, and the position coincides with the center of the substrate 10.

  In the light emitting device according to the present embodiment, the peripheral portions of the substrate 10 and the heat sink 2 are fixed by fixing screws 42. The second surface 16 of the substrate 10 and the mounting surface 21 of the heat sink 2 may be fixed with an adhesive or the like together with the fixing screw 42 or instead of the fixing screw 42. Further, heat radiation grease or the like may be applied between the second surface 16 of the substrate 10 and the mounting surface 21 of the heat sink 2.

  On the other hand, it is also possible not to fix the board | substrate 10 and the heat sink 2 with a screw | thread or an adhesive agent. In this case, the substrate 10 and the heat sink 2 are connected only by the convex portion 41 penetrating the center of the substrate 10. That is, even if the thermal expansion coefficients of the substrate 10 and the heat sink 2 are different, the expansion of the substrate 10 is not hindered.

(Embodiment 3)
Hereinafter, another example of the embodiment of the light emitting device of the present invention will be described in detail with reference to FIG. FIG. 3 is a schematic cross-sectional view showing the structure of the light emitting device according to this embodiment. The basic structure of the light-emitting device according to this embodiment is the same as that of the light-emitting device according to Embodiment 1. Therefore, the same components as those of the light emitting device according to the first embodiment are denoted by the same reference numerals in FIG.

  In the light emitting module 1 constituting the light emitting device according to the present embodiment, a through hole 50 penetrating the substrate 10 and the heat sink 2 is formed, and a convex portion 51 protruding from the bottom surface of the reflector 2 in the through hole 50. Has been inserted. The convex portion 51 is integrally formed as a part of the reflector 2. Therefore, the heat of the light emitting module 1 is transmitted to the heat sink 2 via the convex portion 51 and radiated. That is, also in the light emitting device according to the present embodiment, the heat of the light emitting module 1 is transferred to the heat sink 2 without passing through the substrate 10.

  Moreover, the convex part 52 is arrange | positioned between the two opening parts 13 in which LED14 is arrange | positioned similarly to the screw 31 shown in FIG. More specifically, the convex portion 52 penetrates the substrate 10 and reaches the heat sink 2 at a position equidistant from each LED 14, and the position coincides with the center of the substrate 10.

  In the light emitting device according to the present embodiment, the peripheral portions of the substrate 10 and the heat sink 2 are fixed by fixing screws 42. The second surface 16 of the substrate 10 and the mounting surface 21 of the heat sink 2 may be fixed with an adhesive or the like together with the fixing screw 42 or instead of the fixing screw 42. Further, heat radiation grease or the like may be applied between the second surface 16 of the substrate 10 and the mounting surface 21 of the heat sink 2.

  On the other hand, it is also possible not to fix the board | substrate 10 and the heat sink 2 with a screw | thread or an adhesive agent. In this case, the substrate 10 and the heat sink 2 are connected only by the convex portion 51 that penetrates the center of the substrate 10. That is, even if the thermal expansion coefficients of the substrate 10 and the heat sink 2 are different, the expansion of the substrate 10 is not hindered.

1 is a schematic cross-sectional view illustrating a structure of a light emitting device according to Embodiment 1. FIG. 6 is a schematic cross-sectional view showing a structure of a light emitting device according to Embodiment 2. FIG. 6 is a schematic cross-sectional view showing a structure of a light emitting device according to Embodiment 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting module 2 Heat sink 10 Board | substrate 11 1st surface 12 Reflector 13 Opening part 14 LED
31 Screw 41, 51 Convex part

Claims (7)

A substrate,
A reflector provided on a first surface of the substrate and having a plurality of openings;
A light emitting element disposed in each of the openings of the reflector;
A heat dissipating member in contact with the second surface opposite to the first surface of the substrate;
A light emitting device comprising: a heat transfer member penetrating the substrate, having one end reaching the reflector and the other end reaching the heat dissipation member.   The light-emitting device according to claim 1, wherein the reflector is made of metal.   The light-emitting device according to claim 1, wherein the heat transfer member is a metal screw for fixing the substrate and the heat dissipation member.   The light-emitting device according to claim 1, wherein the heat transfer member is a convex portion integrally formed with the heat dissipation member as a part of the heat dissipation member.   The light-emitting device according to claim 1, wherein the heat transfer member is a convex portion formed integrally with the reflector as a part of the reflector.   The light emitting device according to claim 1, wherein the one end of the heat transfer member reaching the reflector is disposed between the adjacent openings.   The light-emitting device according to claim 1, wherein the heat transfer member passes through a center of the substrate.

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