Patent Publication Number: US-RE47425-E

Title: Lighting device having reflectors for indirect light emission

Description:
CROSS-REFERENCE TO RELATED APPLICATION APPLICATIONS 
     The presentThis application is a Reissue Application of prior U.S. Pat. No. 8,680,755 issued Mar. 25, 2014 (U.S. patent application Ser. No. 13/738,605 filed Jan. 10, 2013), which claims priority under 35 U.S.C. §119(e) of Korean Patent Application No. 10-2012-0048246 filed May 7, 2012, No. 10-2012-0055593 filed May 24, 2012, No. 10-2012-0055594 filed May 24, 2012, No. 10-2012-0055595 filed May 24, 2012, the subject matters of which whose entire disclosures are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The inventions relates to a lighting device. 
     2. Background 
     A light emitting diode (LED) is an energy device for converting electric energy into light energy. Compared with an electric bulb, the LED has higher conversion efficiency, lower power consumption and a longer life span. As there advantages are widely known, more and more attentions are now paid to a lighting apparatus using the LED. 
     The lighting apparatus using the LED are generally classified into a direct lighting apparatus and an indirect lighting apparatus. The direct lighting apparatus emits light emitted from the LED without changing the path of the light. The indirect lighting apparatus emits light emitted from the LED by changing the path of the light through reflecting means and so on. Compared with the direct lighting apparatus, the indirect lighting apparatus mitigates to some degree the intensified light emitted from the LED and protects the eyes of users. 
     SUMMARY 
     One embodiment is a lighting device. The lighting device includes: a heat sink which includes a base and a member extending from the base; a light source module which is disposed on a lateral surface of the member; and a reflector which is disposed on the member and has a disposition recess exposing the light source module. The at least two light source modules are provided and the light source module includes a terminal plate which electrically connects the at least two light source modules. The terminal plate is disposed on the reflector. 
     The reflector may have a shape corresponding to that of the member and wherein the reflector covers the member. The heat sink may comprise a receiver which passes through the base and the member. The reflector may comprise a lower portion having the disposition recess, and an upper portion disposed on the receiver. 
     The lighting device may further comprises a cover which is disposed on the reflector and is coupled to the heat sink. The upper portion of the reflector may have a surface convex toward the cover. An angle between the lateral surface of the member and a central axis of the lighting device may be equal to or greater than 0.3 degree and equal to or less than 3 degree. 
     The lateral surface of the member of the heat sink may be curved. The light source module may comprise a flexible substrate disposed on the curved surface and a light emitting diode disposed on the substrate. 
     The heat radiating fin may comprise an upper portion and a lower portion. A width of the upper portion of the heat radiating fin may increase with the approach to a lower portion of the base from an upper portion of the base. A width of the lower portion of the heat radiating fin may decrease with the approach to the lower portion of the base from the upper portion of the base. The upper portion of the heat radiating fin may be disposed under a light distribution area of light emitted from the light source module and not overlapped with the light distribution area. 
     A thickness of the heat radiating fin may be equal to or larger than 0.8 mm and is equal to or less than 3.0 mm. On the basis of a vertical axis passing through a center of the light emitting device, a maximum emission angle of the light emitting device may be defined by an angle between the vertical axis and a tangent line passing through both the center of the light emitting device and a contact point of the upper portion of the heat radiating fin. A plurality of the heat radiating fins may be disposed to surround the outer surface of the base of the heat sink and may be separated from each other at a predetermined interval. An interval between the outermost ends of the two adjacent heat radiating fins among the plurality of the heat radiating fins may be different from an interval between the innermost ends of the two adjacent heat radiating fins. 
     The light source module may comprise a substrate disposed on the lateral surface of the member of the heat sink, and the light emitting device disposed on the substrate. An area of the lateral surface of the member may be greater than that of the bottom surface of the substrate. The substrate may be disposed to lean more on the lower portion of the lateral surface of the member than the upper portion of the lateral surface of the member, so that a portion of the lateral surface of the member is exposed. 
     A distance from the uppermost portion of the member to the uppermost portion of the substrate may be equal to or greater than 3 mm and is equal to or less than 5 mm. The heat sink may comprise a receiver passing through the base and the member. The member may further comprise an extension part extending toward the receiver. 
     A length of the extension part may be equal to or greater than 10 mm and be equal to or less than 20 mm on the basis of the lateral surface of the member. A thickness of the member may be equal to or larger than 2.5 mm and be equal to or less than 5 mm. 
     Another embodiment is a lighting device. The lighting device includes: a heat sink including a base including a heat radiating fin, and a member which extends from the base and has at least one lateral surface; and a light source module disposed on the lateral surface of the member of the heat sink and comprising a light emitting device. The heat radiating fin may include an upper portion and a lower portion. A width of the upper portion of the heat radiating fin may increase with the approach to a lower portion of the base from an upper portion of the base. A width of the lower portion of the heat radiating fin may decrease with the approach to the lower portion of the base from the upper portion of the base. The upper portion of the heat radiating fin may be disposed under a light distribution area of light emitted from the light source module and not overlapped with the light distribution area. 
     The reflector may have a shape corresponding to that of the member and wherein the reflector covers the member. The heat sink may comprise a receiver which passes through the base and the member. The reflector may comprise a lower portion having the disposition recess, and an upper portion disposed on the receiver. 
     The lighting device may further comprises a cover which is disposed on the reflector and is coupled to the heat sink. The upper portion of the reflector may have a surface convex toward the cover. An angle between the lateral surface of the member and a central axis of the lighting device may be equal to or greater than 0.3 degree and equal to or less than 3 degree. 
     The lateral surface of the member of the heat sink may be curved. The light source module may comprise a flexible substrate disposed on the curved surface and a light emitting diode disposed on the substrate. 
     The heat radiating fin may comprise an upper portion and a lower portion. A width of the upper portion of the heat radiating fin may increase with the approach to a lower portion of the base from an upper portion of the base. A width of the lower portion of the heat radiating fin may decrease with the approach to the lower portion of the base from the upper portion of the base. The upper portion of the heat radiating fin may be disposed under a light distribution area of light emitted from the light source module and not overlapped with the light distribution area. 
     A thickness of the heat radiating fin may be equal to or larger than 0.8 mm and is equal to or less than 3.0 mm. On the basis of a vertical axis passing through a center of the light emitting device, a maximum emission angle of the light emitting device may be defined by an angle between the vertical axis and a tangent line passing through both the center of the light emitting device and a contact point of the upper portion of the heat radiating fin. A plurality of the heat radiating fins may be disposed to surround the outer surface of the base of the heat sink and may be separated from each other at a predetermined interval. An interval between the outermost ends of the two adjacent heat radiating fins among the plurality of the heat radiating fins may be different from an interval between the innermost ends of the two adjacent heat radiating fins. 
     The light source module may comprise a substrate disposed on the lateral surface of the member of the heat sink, and the light emitting device disposed on the substrate. An area of the lateral surface of the member may be greater than that of the bottom surface of the substrate. The substrate may be disposed to lean more on the lower portion of the lateral surface of the member than the upper portion of the lateral surface of the member, so that a portion of the lateral surface of the member is exposed. 
     A distance from the uppermost portion of the member to the uppermost portion of the substrate may be equal to or greater than 3 mm and is equal to or less than 5 mm. The heat sink may comprise a receiver passing through the base and the member. The member may further comprise an extension part extending toward the receiver. 
     A length of the extension part may be equal to or greater than 10 mm and be equal to or less than 20 mm on the basis of the lateral surface of the member. A thickness of the member may be equal to or larger than 2.5 mm and be equal to or less than 5 mm. 
     Further another embodiment is a lighting device. The lighting device includes: a heat sink including a base and a member disposed on the base; a light source module disposed on the member of the heat sink; a housing which is disposed in the base of the heat sink and inside the member of the heat sink and is formed of a material having electrical insulation; and a power supply which is received inside the housing and supplies electrical power to the light source module. The housing includes an upper housing and a lower housing. The upper housing is surrounded by the member of the heat sink. The lower housing is surrounded by the base of the heat sink. The upper housing receives an upper portion of the power supply, and wherein the lower housing receives the rest portion of the power supply. 
     The heat sink may comprise a receiver which passes through the base and the member, the receiver of the heat sink may be a through-hole. The through-hole may have a shape corresponding to that of the housing. 
     The through-hole may comprise an upper portion defined by the member of the heat sink, and a lower portion defined by the base of the heat sink. A space volume of the upper portion of the through-hole may be different from that of the lower portion of the through-hole. The lower housing may comprise a molding part for fixing the power supply. 
     The reflector may have a shape corresponding to that of the member and wherein the reflector covers the member. The heat sink may comprise a receiver which passes through the base and the member. The reflector may comprise a lower portion having the disposition recess, and an upper portion disposed on the receiver. 
     The lighting device may further comprise a cover which is disposed on the reflector and is coupled to the heat sink. The upper portion of the reflector may have a surface convex toward the cover. An angle between the lateral surface of the member and a central axis of the lighting device may be equal to or greater than 0.3 degree and equal to or less than 3 degree. 
     The lateral surface of the member of the heat sink may be curved. The light source module may comprise a flexible substrate disposed on the curved surface and a light emitting diode disposed on the substrate. 
     The heat radiating fin may comprise an upper portion and a lower portion. A width of the upper portion of the heat radiating fin may increase with the approach to a lower portion of the base from an upper portion of the base. A width of the lower portion of the heat radiating fin may decrease with the approach to the lower portion of the base from the upper portion of the base. The upper portion of the heat radiating fin may be disposed under a light distribution area of light emitted from the light source module and not overlapped with the light distribution area. 
     A thickness of the heat radiating fin may be equal to or larger than 0.8 mm and is equal to or less than 3.0 mm. On the basis of a vertical axis passing through a center of the light emitting device, a maximum emission angle of the light emitting device may be defined by an angle between the vertical axis and a tangent line passing through both the center of the light emitting device and a contact point of the upper portion of the heat radiating fin. A plurality of the heat radiating fins may be disposed to surround the outer surface of the base of the heat sink and may be separated from each other at a predetermined interval. An interval between the outermost ends of the two adjacent heat radiating fins among the plurality of the heat radiating fins may be different from an interval between the innermost ends of the two adjacent heat radiating fins. 
     The light source module may comprise a substrate disposed on the lateral surface of the member of the heat sink, and the light emitting device disposed on the substrate. An area of the lateral surface of the member may be greater than that of the bottom surface of the substrate. The substrate may be disposed to lean more on the lower portion of the lateral surface of the member than the upper portion of the lateral surface of the member, so that a portion of the lateral surface of the member is exposed. 
     A distance from the uppermost portion of the member to the uppermost portion of the substrate may be equal to or greater than 3 mm and is equal to or less than 5 mm. The heat sink may comprise a receiver passing through the base and the member. The member may further comprise an extension part extending toward the receiver. 
     A length of the extension part may be equal to or greater than 10 mm and be equal to or less than 20 mm on the basis of the lateral surface of the member. A thickness of the member may be equal to or larger than 2.5 mm and be equal to or less than 5 mm. 
     A portion of the cover and a portion of the heat sink may have a shape suitable to couple the cover to the heat sink. 
     The lighting device according to the invention is capable of performing optimum omni-directional light distribution. 
     The lighting device according to the invention is capable of enhancing heat radiation performance. 
     The lighting device according to the invention is capable of blocking electrical contact between a light source module and a heat sink. 
     The lighting device according to the invention is capable of removing a dark portion which may be generated in a cover. 
     The lighting device according to the invention has good workability in assemblage or manufacture. 
     The lighting device according to the invention is capable of improving light-extraction efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Arrangements and embodiments may be described in detail with reference to the following drawings in which like reference numerals refer to like elements and wherein: 
         FIG. 1  is a top perspective view of a lighting device according to an embodiment; 
         FIG. 2  is a bottom perspective view of the lighting device shown in  FIG. 1 ; 
         FIG. 3  is an exploded perspective view of the lighting device shown in  FIG. 1 ; 
         FIG. 4  is an exploded perspective view of the lighting device shown in  FIG. 2 ; 
         FIG. 5  is a front view showing that the lighting device shown in  FIG. 1  does not include a cover; 
         FIG. 6  is a front view showing that the lighting device shown in  FIG. 1  does not include a cover and a reflector; 
         FIG. 7  is a cross sectional view of a heat sink alone shown in  FIG. 2 ; 
         FIG. 8  is a plan view of the heat sink shown in  FIG. 2 ; and 
         FIG. 9  is a perspective view of a housing alone shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     The invention will be now disclosed making reference to the enclosed drawings and disclosing more than one embodiment. A skilled in this art will easily understand that the invention is not limited to a single embodiment but that some features and functional characteristics may be in common to the various embodiments so that some of the inventive features of different embodiments may even be merged and combined even if not explicitly reported in the corresponding description. 
     A thickness or a size of each layer may be magnified, omitted or schematically shown for the purpose of convenience and clearness of description. The size of each component may not necessarily mean its actual size. 
     It should be understood that when an element is referred to as being ‘on’ or “under” another element, it may be directly on/under the element, and/or one or more intervening elements may also be present. When an element is referred to as being ‘on’ or ‘under’, ‘under the element’ as well as ‘on the element’ may be included based on the element. 
     An embodiment may be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a top perspective view of a lighting device according to an embodiment.  FIG. 2  is a bottom perspective view of the lighting device shown in  FIG. 1 .  FIG. 3  is an exploded perspective view of the lighting device shown in  FIG. 1 .  FIG. 4  is an exploded perspective view of the lighting device shown in  FIG. 2 .  FIG. 5  is a front view showing that the lighting device shown in  FIG. 1  does not include a cover.  FIG. 6  is a front view showing that the lighting device shown in  FIG. 1  does not include a cover and a reflector. 
     Referring to  FIGS. 1 to 6 , the lighting device according to the embodiment may include a cover  100 , a light source module  200 , a reflector  300 , a heat sink  400 , a housing  500 , a power supply  600  and a socket  700 . Hereafter, the components will be described in detail respectively. 
     &lt;Cover  100 &gt; 
     The cover  100  has a bulb shape with an empty interior. The cover  100  also has a partial opening  130  of which a portion has been opened. 
     The cover  100  is optically connected to the light source module  200 . For example, the cover  100  may diffuse, scatter or excite light emitted from the light source module  200 . 
     The cover  100  is coupled to the heat sink  400 . For this, a portion of the cover  100  and a portion of the heat sink  400  may have a shape suitable to couple the cover  100  to the heat sink  400 . For example, the cover  100  may include a coupler  110 . The coupler  110  may be inserted into a coupling recess  490  of the heat sink  400 . The coupler  110  may have a screw thread-shaped coupling structure. A screw recess-shaped structure corresponding to the screw thread-shaped coupling structure is formed in the coupling recess  490 , thereby making it easier for the cover  100  and the heat sink  400  to be coupled to each other. Therefore, workability can be enhanced. 
     The thickness of the cover  100  may have a value within a range between 1 mm and 2 mm. 
     The cover  100  may be made of a light diffusing polycarbonate (PC) for the purpose of prevent a user from feeling glare caused by the light emitted from the light source module  200 . Further, the cover  100  may be made of any one of glass, plastic, polypropylene (PP) and polyethylene (PE). 
     The inner surface of the cover  100  may be anti-corrosion treated. Moreover, a predetermined pattern may be applied to the outer surface of the cover  100 . With this feature the light emitted from the light source module  200  can be scattered. Accordingly, the user is able to avoid the glare. 
     The cover  100  may be manufactured by a blow molding process for the sake of uniform light distribution of omni-directional light. In the blow molding process, the diameter of the opening  130  of the cover  100  may be from 3 mm to 20 mm. 
     Embossing pattern may be formed on the surface of the cover  100 . Preferably, the embossing pattern may be formed on the surface of the cover  100  close to the partial opening  130 . This structure can improve the scatter of light. 
     In a modified embodiment, the cover  100  may include a plurality of protrusions (un-drawn). The heat sink  400  may have a plurality of recesses whose position corresponding to those of the plurality of protrusions of the cover  100 . The plurality of protrusions may be shaped suitable to be inserted and locked into the plurality of recesses of the heat sink  400 . For example, the tips of the protrusions may be trapezoidal so that the protrusions can be locked in the recesses of the heat sink  400 . Due to the structure, workability can be enhanced. 
     &lt;Light Source Module  200 &gt; 
     The light source module  200  emits a predetermined light. 
     A plurality of the light source modules  200  may be provided. Specifically, the light source module  200  may include a first light source module  200 a, a second light source module  200 b and a third light source module  200 c. 
     The first to the third light source modules  200 a,  200 b and  200 c may respectively include a substrate  210 a and a light emitting device  230 a disposed on the substrate  210 a. 
     The substrate  210 a may be formed by printing a circuit pattern on an insulator. For example, the substrate  210 a may include a general printed circuit board (PCB), a metal core PCB, a flexible PCB, a ceramic PCB and the like. The surface of the substrate  210 a may be formed of a material capable of efficiently reflecting light. The surface of the substrate  210 a may be coated with a color capable of efficiently reflecting light, for example, white, silver and the like. 
     A predetermined hole  215 a may be formed in the center of the substrate  210 a. The hole  215 a may be a reference point for arranging the light emitting devices  230 a. A screw may be inserted into the hole  215 a in order to fix the substrate  210 a to the heat sink  400 . The screw can serve as a thermal path, so the heat transfer from the substrate  210 a to the heat sink  400  can improve. 
     At least one light emitting device  230 a may be disposed on one side of the substrate  210 a. In  FIG. 3 , a plurality of the light emitting devices  230 a may be disposed on one side of the substrate  210 a. The light emitting device  230 a may be a light emitting diode chip emitting red, green and blue light or a light emitting diode chip emitting ultraviolet light. Here, the light emitting diode chip may have a lateral type or a vertical type and may emit blue, red, yellow or green light. 
     A lens may be disposed on the light emitting device  230 a. The lens is disposed to cover the light emitting device  230 a. The lens is able to adjust an emission angle or a direction of light emitted from the light emitting device  230 a. The lens may be a hemispherical shape and may be made of a light transmitting resin like silicone resin or epoxy resin without an empty space. The light transmitting resin may wholly or partially include a distributed fluorescent material. 
     When the light emitting device  230 a is a blue light emitting diode, the fluorescent material included in the light transmitting resin may include at least one selected from a group consisting of a garnet material (YAG, TAG), a silicate material, a nitride material and an oxynitride material. 
     Though natural light (white light) can be created by allowing the light transmitting resin to include only yellow fluorescent material, the light transmitting resin may further include a green fluorescent material or a red fluorescent material in order to improve a color rendering index and to reduce a color temperature. 
     When the light transmitting resin is mixed with many kinds of fluorescent materials, an addition ratio of the color of the fluorescent material may be formed such that the green fluorescent material is more used than the red fluorescent material, and the yellow fluorescent material is more used than the green fluorescent material. The garnet material, the silicate material and the oxynitride material may be used as the yellow fluorescent material. The silicate material and the oxynitride material may be used as the green fluorescent material. The nitride material may be used as the red fluorescent material. The light transmitting resin may be mixed with various kinds of the fluorescent materials or may be configured by a layer including the red fluorescent material, a layer including the green fluorescent material and a layer including the yellow fluorescent material, which are formed separately from each other. 
     The light source module  200  may include a terminal plate  250 . The first to the third light source modules  200 a,  200 b and  200 c may be electrically connected to each other by means of the terminal plate  250 . For example, the first to the third light source modules  200 a,  200 b and  200 c may be electrically connected in series to each other through use of the two terminal plates  250 . 
     The terminal plate  250  may be made of a conductive metallic material. For instance, the terminal plate  250  may be made by using any one of copper, nickel and zinc plating or the compound comprising at least two selected from copper, nickel and zinc plating. For the purpose of manufacturing the light source module  200 , the terminal plate  250  may be made of a metallic material which is easily bent. By using the terminal plate  250 , the workability for installing the light source module  200  in the heat sink  400  can be improved and the light source modules are more stably connected to each other than they are connected by using a wire. 
     Preferably, the thickness of the terminal plate  250  may be from 0.1 mm to 0.5 mm. If the thickness is less than 0.1 mm, the terminal plate  250  would be easily snapped in the manufacturing process or by an external shock. If the thickness is more than 0.5 mm, the terminal plate  250  can be difficult to bend. 
     The light source module  200  is disposed in the heat sink  400 . Specifically, the substrates  210 a of the first to the third light source modules  200 a,  200 b and  200 c may be disposed on an outer lateral surface  411  of a member  410  of the heat sink  400 . The laterally arranged light source modules  200 a,  200 b, and  200 c can improve the performance of omni-directional light by scattering the light uniformly throughout the cover  100 . 
     &lt;Reflector  300 &gt; 
     The reflector  300  is coupled to the heat sink  400 . Specifically, the reflector  300  may be coupled to the member  410  of the heat sink  400 . 
     The reflector  300  has a shape corresponding to that of the member  410  of the heat sink  400 . Also, the reflector  300  may have a shape covering the member  410  of the heat sink  400 . Specifically, the reflector  300  may include an upper portion  310  and a lower portion  330 . The upper portion  310  is disposed on the top surface of the member  410  of the heat sink  400 . The lower portion  330  is disposed on the lateral surface of the member  410  of the heat sink  400 . In other words, the lower portion  330  may extend from the periphery of the upper portion  310  along the lateral surface of the member  410 . The upper portion  310  may be substantially perpendicular to the lower portion  330 . 
     The upper portion  310  of the reflector  300  may include a flat surface or a surface convex toward the cover  100 . When the upper portion  310  of the reflector  300  includes the convex surface, there is an advantage of reducing dark portions which may be generated in the uppermost portion of the cover  100 . 
     The reflector  300  may have a coupling means suitable to be coupled to the heat sink  400 , and the heat sink  400  may have a corresponding coupling means. For example, the upper portion  310  of the reflector  300  may have at least one hole  371 , and the top surface of the member  410  of the heat sink  400  may have at least one hole  471  at the corresponding position of the holes of the upper portion  310  of the reflector  300 . Both holes can be fastened by a fastening means, such as screw. But, the coupling means of the reflector  300  and the heat sink  400  is not limited thereto. 
     The minimum distance from the upper portion  310  of the reflector  300  to the uppermost portion of the cover  100  may be equal to or greater than 15 mm. If the distance from the upper portion  310  of the reflector  300  to the inner surface of the cover  100  is less than and not equal to 15 mm, the dark portion may be generated in the uppermost portion of the cover  100 . When the minimum distance from the upper portion  310  of the reflector  300  to the inner surface of the cover  100  is equal to or greater than 15 mm, the dark portion can be remarkably reduced and density of the dark portion can be more reduced. 
     The reflector  300  may have a disposition recess  335 . The disposition recess  335  may be formed in the lower portion  330  of the reflector  300 . The light source module  200  disposed in the member  410  of the heat sink  400  may be disposed in the disposition recess  335 . Specifically, the substrate  210 a of the light source module  200  may be disposed in the disposition recess  335 . While the reflector  300  is disposed on the member  410  of the heat sink  400 , the disposition recess  335  prevents the reflector  300  from being disposed on the light source module  200 . 
     The reflector  300  may be made of white polycarbonate (PC) which easily reflects the light emitted from the light source module  200  and has thermal resistance. The reflector  300  is able to raise light-extraction efficiency of the lighting device according to the embodiment. 
     The reflector  300  may be made of a material having electrical insulation. The reflector  300  may be disposed between the member  410  of the heat sink  400  and the terminal plate  250  of the light source module  200 . Such a reflector  400  is able to block electrical contact between the terminal plate  250  and the heat sink  400 . 
     A surface treatment process is performed on the surface of the reflector  300 , so that the light from the light source module  200  is scattered and a user is able to avoid the glare. 
     The side surfaces of the substrates  210 a of the light source module  200 a may be arranged in parallel to the inner side of the disposition recess  335 . At least one side surfaces of the substrates  210 a may contact with the inner side of the disposition recess  335  when they are assembled. 
     The lower portion  330  of the reflector  300  may have a guide  381  through which the light source modules  200  are provided electric power from the power supply  600 . The guide  381  may be a recess extended from the disposition recess  335  of the reflector  300 . Alternatively, the guide  381  may be a hole formed on the surface between the disposition recess  335  and the upper portion  310  of the reflector  300 . 
     &lt;Heat Sink  400 &gt; 
     The light source module  200  is disposed on the heat sink  400 . The heat sink  400  receives heat from the light source module  200  and radiates the heat. The heat sink  400  is coupled to the cover  100  and receives the power supply  600  and the housing  500 . 
       FIG. 7  is a cross sectional view of the heat sink alone shown in  FIG. 2 . 
     Referring to  FIGS. 1 to 7 , the heat sink  400  may include the member  410 , a base  430  and a heat radiating fin  450 . 
     The member  410  may extend upward from the upper portion of the base  430 . The member  410  may be integrally formed with the base  430  or may be formed separately from the base  430  and bonded or coupled to the base  430 . 
     The member  410  may have a cylindrical shape. The light source module  200  is disposed on the outer surface of the cylindrical member  410 . 
     The member  410  has the lateral surface  411  on which the light source module  200  is disposed. The member  410  has the lateral surface  411  of which the number is the same as the number of the light source modules  200 . For example, the member  410  may have three lateral surfaces  411  on which the first to the third light source modules  200 a,  200 b and  200 c are disposed respectively. The three lateral surfaces  411  may come in surface contact with the bottom surfaces of the substrates  210 a of the first to the third light source modules  200 a,  200 b and  200 c. For this purpose, the three lateral surfaces  411  may be flat. However, there is no limit to this. The three lateral surfaces  411  may be curved. In this case, the substrates  210 a may be flexible substrates. 
     The lateral surface  411  may be, as shown in  FIG. 7 , substantially parallel with a central axis “X” of the lighting device according to the embodiment. Here, an angle between the lateral surface  411  and the central axis “X” may be from 0.3 degree to 3 degree. If the angle between the lateral surface  411  and the central axis “X” is from 0 degree to 0.3 degree, front light distribution characteristic is deteriorated. That is to say, a dark spot may be generated at the topmost portion of the cover  100 . If the angle between the lateral surface  411  and the central axis “X” is greater than 3 degree, omni-directional distribution characteristic is deteriorated. 
     The area of the lateral surface  411  is, as shown in  FIG. 6 , greater than that of the bottom surface of the substrate  210 a and is disposed to lean on the lower portion of the lateral surface  411  instead of the central portion of the lateral surface  411 . Therefore, the substrate  210 a is not disposed on the upper portion of the lateral surface  411 . When the lateral surface  411  includes a portion on which the substrate  210 a is not disposed, heat generated from the light source module  200  is transferred from the member  410  not only to the base  430  but also the upper portion of the member  410 . Accordingly, the temperature of the light source module  200  can be rapidly reduced. As a result, it is possible to improve heat radiation performance of the lighting device according to the embodiment. 
     Here, a distance “a” from the uppermost portion of the lateral surface  411  to the uppermost portion of the substrate  210 a may be from 3 mm to 5 mm. If the distance “a” is less than 3 mm, remarkable heat radiation effect is not obtained. If the distance “a” is greater than 5 mm, the dark portion generated in the uppermost portion of the cover  100  becomes thicker. 
     The thickness of the member  410  may be from 2.5 mm to 5 mm. If the thickness of the member  410  is less than 2.5 mm, heat radiation performance is degraded. If the thickness of the member  410  is greater than 5 mm, the material cost of the heat sink  400  is increased and an interior space for receiving the power supply  600  is reduced. 
     The member  410  may include an extension part  413 . The extension part  413  may extend from the uppermost portion of the member  410  toward a receiver  470 . Since the heat generated from the light source module  200  may be transferred more to the upper portion of the member  410  by the extension part  413  and the heat transferred to the extension part  413  can cause heat convection in the receiver  470 , the temperature of the light source module  200  can be rapidly reduced. Therefore, it is possible to improve heat radiation performance of the lighting device according to the embodiment. Here, the length of the extension part  413  may be from 10 mm to 20 mm on the basis of the lateral surface  411 . The extension part  413  having a length less than 10 mm has no great influence on heat radiation performance improvement. The extension part  413  having a length greater than 20 mm does not allow the power supply  600  and the light source module  200  to be easily connected to each other. 
     In a modified embodiment, the extension part  413  may be formed separately from the uppermost portion of the member  410  and bonded or coupled to the uppermost portion of the member  410 . 
     The base  430  is disposed under the member  410 . The base  430  and the member  410  may be integrally formed with each other. 
     A plurality of the heat radiating fins  450  may be disposed on the outer surface of the base  430 . The plurality of the heat radiating fins  450  may project outward from the outer surface of the base  430 . The base  430  and the plurality of the heat radiating fins  450  may be integrally formed with each other or may be formed separately from each other and coupled to each other. 
     The heat radiating fin  450  may have an upper portion and a lower portion. The width of the upper portion of the heat radiating fin  450  increases with the approach to the lower portion of the base  430  from the upper portion of the base  430 . The width of the upper portion can be defined, for example, as the distance from a point of the heat radiating fin  450  located near the receiver  470  to a point on the outer periphery of the hear radiating fin  450  where the hypothetical line connecting the two points is substantially perpendicular to the outer surface of the base  430 . When the width of the upper portion of the heat radiating fin  450  increases with the approach to the lower portion of the base  430  from the upper portion of the base  430 , the omni-directional distribution characteristic of the lighting device according to the embodiment can be enhanced. This is because the light emitted from the light source module  200  is not blocked by the upper portion of the heat radiating fin  450 . This will be described in more detail with reference to  FIG. 6 . To describe the structure in a different way, each of the heat radiating fin  450  has a triangular shape where first vertex of the triangle is located near one portion of the body close to the member  410 , second vertex of the triangle is located near the opposite portion of the body close to the housing  550 , and the third vertex of the triangle protrudes outward from the receiver  470 . 
     Referring to  FIG. 6 , the upper portion of the heat radiating fin  450  may be formed in consideration of the light emitted from the light source module  200 a. Specifically, the upper portion of the heat radiating fin  450  may be formed in consideration of a light distribution area “L” of the light emitted from the light source module  200 a. In other words, the upper portion of the heat radiating fin  450  may be disposed under the light distribution area “L” of the light source module  200 a, or the upper portion of the heat radiating fin  450  may be disposed in such a manner as not to be overlapped with the light distribution area “L” of the light source module  200 a. 
     The emission angle of the light source module  200 b and the upper portion of the heat sink  400  may have the following relation. On the basis of a vertical axis “G” passing through the center of a light emitting device  230 b, the maximum emission angle “Z” of the light emitting device  230 b may be defined by an angle between the vertical axis “G” and a tangent line “C” passing through both the center of the light emitting device  230 b and a contact point of the upper portion of the heat radiating fin  450 . When the maximum emission angle “Z” of the light emitting device  230 b is defined in this manner, the omni-directional light distribution characteristic of the lighting device according to the embodiment can be enhanced. Here, the maximum emission angle “Z” may be from 50 degree to 80 degree. If the maximum emission angle “Z” is less than 50 degree, omni-directional light distribution meeting a standard specification cannot be obtained. If the maximum emission angle “Z” is greater than 80 degree, it is not possible to obtain a sufficient area for radiating the heat. 
     In the definition of the maximum emission angle “Z” of the light emitting device  230 b, the vertical axis “G” may pass through the center of a substrate  210 b instead of the center of the light emitting device  230 b. In other words, the vertical axis “G” may pass through a hole  215 b of the substrate  210 b. 
       FIG. 8  is a plan view of the heat sink  400  shown in  FIG. 2 . 
     Referring to  FIG. 8 , the heat radiating fin  450  may project perpendicularly to the outer surface of the base  430 . 
     The heat radiating fin  450  may become thinner from the outer surface of the base  430  to the outside. The thickness of the heat radiating fin  450  may be from 0.8 mm to 3.0 mm. If the thickness of the heat radiating fin  450  is less than 0.8 mm, the heat radiating fin  450  is difficult to be formed and an expected heat radiation effect cannot be obtained. If the thickness of the heat radiating fin  450  is larger than 3.0 mm, an interval between two adjacent heat radiating fins is reduced, so that when the heat sink  400  is powder-coated, a desired coating process cannot be performed between the two adjacent heat radiating fins. 
     The plurality of the heat radiating fins  450  may be separated from each other at a predetermined interval. Here, an interval between the outermost ends of the two heat radiating fins  450  may be from 6 mm to 7 mm, and an interval between the innermost ends of the two heat radiating fins  450  may be from 4 mm to 6 mm. When the interval between the outermost ends of the heat radiating fins  450  is different from the interval between the innermost ends of the heat radiating fins  450 , heat radiation performance can be improved and a powder coating process can be performed with ease to the innermost end of the heat radiating fin  450 . 
     The heat sink  400  has a receiver  470  for receiving the housing  500  thereinside. The receiver  470  may be a through-hole passing through the member  410  and the base  430  of the heat sink  400 . The through-hole  470  may be defined by a portion surrounded by the member  410  and a portion surrounded by the base  430 . The upper portion of the through-hole  470  is surrounded by the member  410 . The lower portion of the through-hole  470  is surrounded by the base  430 . The shape of the upper portion of the through-hole  470  is different from the shape of the lower portion of the through-hole  470 . Specifically, the upper portion of the through-hole  470  may have a volume less than that of the lower portion of the through-hole  470 . When the volume of the upper portion of the through-hole  470  is less than that of the lower portion of the through-hole  470 , even after the housing  500  is received in the through-hole  470  of the heat sink  400 , the housing  500  cannot fall into the upper portion of the through-hole  470 , which is surrounded by the member  410 . Moreover, there is an advantage of improving the assemblability of the lighting device according to the embodiment. 
     The heat sink  400  may be formed of a metallic material or a resin material which has excellent heat radiation efficiency. The heat sink  400  may be formed of a material having high thermal conductivity (generally, greater than 150 Wm −1 K −1 , and more preferably, greater than 200 Wm −1 K −1 ), for example, copper (thermal conductivity of about 400 Wm −1 K −   1 ), aluminum (thermal conductivity of about 250 Wm −1 K −1 ), anodized aluminum, aluminum alloy and magnesium alloy. Also, the heat sink  400  may be formed of a metal loaded plastic material like polymer, for example, epoxy or thermally conductive ceramic material (e.g., aluminum silicon carbide (AlSiC) (thermal conductivity of about 170 to 200 Wm −1 K − ). 
     In a modified embodiment, at least one heat radiating fin  450  may have a different measure from other heat radiating fin  450 . Particularly, the heat radiating fin  450  having different measure may have an additional area protruding toward the cover  100 . The additional area is shaped such that the cover  100  can be coupled to the heat sink  400 . Preferably, the number of the at least one heat radiating fin  450  may be three, and the three heat radiating fin  450  may be uniformly arranged on the circumference of the heat sink  400 . In other words, the distance between each of the three heat radiating fin  450  may be approximately identical. 
     &lt;Housing  500 &gt; 
       FIG. 9  is a perspective view of the housing alone shown in  FIG. 2 . 
     Referring to  FIGS. 1 to 9 , the housing  500  is disposed within the heat sink  400 . Specifically, the housing  500  may be disposed in the receiver  470  of the heat sink  400 . 
     The housing  500  has an appearance corresponding to that of the receiver  470  of the heat sink  400 . The inside of the housing  500  has a space for receiving the power supply  600 . 
     The housing  500  receives the power supply  600  thereinside and protects the power supply  600 . The housing  500  prevents the heat radiated from the heat sink  400  from being transferred to the power supply  600 , thereby preventing the temperature rise of many parts  610  of the power supply  600 . 
     The housing  500  may include an upper housing  510  and a lower housing  550 . The upper housing  510  and the lower housing  550  are coupled to each other and may receive the power supply  600  thereinside. 
     The upper housing  510  is disposed between the member  410  of the heat sink  400  and the upper portion of the power supply  600 . Since the upper housing  510  is disposed behind the light source module  200  which generates the most heat in the heat sink  400 , the amount of the temperature rise of the parts  610  of the power supply  600  can be reduced. 
     The lower housing  550  is disposed between the base  430  of the heat sink  400  and the lower portion of the power supply  600 . Here, a silicone molding process may be performed on the inside of the lower housing  550  in order to fix the lower portion of the power supply  600 . The lower housing  550  may be coupled to the socket  700  to which an external electric power is applied. 
     The housing  500  may be formed of a material having excellent electrical insulation and thermal resistance. For example, the housing  500  may be formed of polycarbonate (PC). 
     &lt;Power Supply  600 &gt; 
     Referring to  FIG. 3 , the power supply  600  may include a support plate  630  and many parts  610  mounted on the support plate  630 . The many parts  610  may include, for example, a DC converter converting AC power supply supplied by an external power supply into DC power supply, a driving chip controlling the driving of the light source module  200 , an electrostatic discharge (ESD) protective device for protecting the light source module  200 , and the like. However, there is no limit to this. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to affect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.