Abstract:
A lighting device may be provided that comprises: a cover; a member comprising a first placement portion, a second placement portion and a guide disposed between the first placement portion and the second placement portion; a light source module disposed on the first placement portion; a heat sink comprising a first receiver and a second receiver, the first receiver being defined by a flat surface and a plurality of heat radiating fins extending from an edge portion of the flat surface; and a circuitry disposed in the second receiver; wherein the second placement portion is disposed in the first receiver, wherein a first portion of the guide is couple to the cover and a second portion of the guide is couple to the heat radiating fins of the heat sink, and wherein the guide is spaced apart from the flat surface, the guide contacts the heat radiating fins, and the guide is disposed on the heat radiating fins.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a Continuation Application of U.S. application Ser. No. 13/583,498 filled Sep. 7, 2012, which claims priority from PCT Application No. PCT/KR2012/006764 filed Aug. 24, 2012, which claims priority to Korean Patent Application No. 10-2011-0085481, filed Aug. 26, 2011, No. 10-2011-0117253, filed Nov. 11, 2011 and No. 10-2011-0117254, filed Nov. 11, 2011, the entireties of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    This embodiment relates to a lighting device. 
         [0004]    2. Background Art 
         [0005]    A light emitting diode (LED) is a semiconductor element for converting electric energy into light. As compared with existing light sources such as a fluorescent lamp and an incandescent electric lamp and so on, the LED has advantages of low power consumption, a semi-permanent span of life, a rapid response speed, safety and an environment-friendliness. For this reason, many researches are devoted to substitution of the existing light sources with the LED. The LED is now increasingly used as a light source for lighting devices, for example, various lamps used interiorly and exteriorly, a liquid crystal display device, an electric sign and a street lamp and the like. 
       Technical Problem 
       [0006]    The objective of the present invention is to provide a lighting device including a light source and a circuitry which are separable from each other. 
         [0007]    The objective of the present invention is to provide a lighting device of which the lifespan does not depend on the circuitry. 
         [0008]    The objective of the present invention is to provide a lighting device of any damaged one out of the light source and circuitry can be freely replaced. 
         [0009]    The objective of the present invention is to provide a lighting device of which the light source and circuitry can be independently produced and sold. 
         [0010]    The objective of the present invention is to provide a lighting device capable both of remarkably reducing defects caused by the destruction of a tap when a bolt is fastened to conventional power supply unit (PSU) housings of MR, PAR and a general bulb product and of remarkably reducing defects caused by crack. 
         [0011]    The objective of the present invention is to provide a lighting device capable of both reducing a manufacturing cost and an assembly lead time by removing parts. 
         [0012]    The objective of the present invention is to provide a lighting device capable of maintaining security for the design structure of the PSU housing because the PSU housing is fastened within a heat sink by a hook and is difficult to analyze. 
         [0013]    The objective of the present invention is to provide a lighting device which includes an inlet for injecting molding liquid to an inner case and causes the molding liquid to be injected into only heat generating parts, so that a manufacturing cost is reduced. 
         [0014]    While in the past a rubber cover is inevitably added in order to prevent water from leaking at the time of injecting the molding liquid, the objective of the present invention is to provide a lighting device which cures the molding liquid by using the rubber cover as JIG and removes the rubber cover, so that a manufacturing cost is reduced by removing parts. 
       Technical Solution 
       [0015]    One embodiment is a lighting device. The lighting device includes: a light source including: a member which includes a first placement portion and a second placement portion; a light source module which is disposed in the first placement portion; and a first terminal which is disposed in the second placement portion and is electrically connected to the light source module; and a heat sink including: a first receiver in which the second placement portion of the member is disposed; a second receiver in which a circuitry is disposed; and a second terminal which is disposed corresponding to the first terminal of the light source. 
         [0016]    The second placement portion of the member has a screw thread. The heat sink has a screw groove corresponding to the screw thread. 
         [0017]    The member has a catching projection. The heat sink has a catching groove which is coupled to the catching projection. 
         [0018]    The catching projection is disposed on the second placement portion of the member. The catching groove has an “L”-shape. 
         [0019]    The second placement portion of the light source includes an insulating portion surrounding the first terminal. The insulating portion prevents electrical short-cut between the first terminal and the member. 
         [0020]    The heat sink includes an insulating portion surrounding the second terminal. The insulating portion prevents electrical short-cut between the second terminal and the heat sink. 
         [0021]    The light source module includes a substrate and a light emitting device disposed on the substrate. The member has a cavity in which the substrate is disposed. 
         [0022]    The lighting device further includes a cover which is disposed over the light source module and is coupled to the member. 
         [0023]    The member further includes a guide disposed between the cover and the heat sink. 
         [0024]    The first terminal and the second terminal include a circular first electrode and a second electrode surrounding the first electrode, respectively. 
         [0025]    Another embodiment is a lighting device. The lighting device includes: a light source module; a heat sink in which the light source module is disposed and which has a receiver and an insertion recess disposed in the inner surface thereof defining the receiver; an inner case which is disposed in the receiver of the heat sink and has a hook coupled to the insertion recess; and a circuitry which is disposed within the inner case and supplies electric power to the light source module. 
         [0026]    The hook is disposed on both sides of the outer surface of the inner case respectively. 
         [0027]    The inner case has an opening. The hook extends toward the opening and projects in such a manner that the end of the hook is inclined. 
         [0028]    The inner case includes: a cylindrical receiver; a connection portion disposed under the receiver in such a manner as to have a diameter less than that of the receiver; and a level-difference portion connecting the receiver with the connection portion. 
         [0029]    The inner case has a guide projection disposed on the outer surface of the receiver in the longitudinal direction of the receiver. The heat sink has a guide groove disposed at a position corresponding to the position of the guide projection. 
         [0030]    The inner case has a guide groove disposed on the outer surface of the receiver in the longitudinal direction of the receiver. The heat sink has a guide projection disposed at a position corresponding to the position of the guide groove. 
         [0031]    Further another embodiment is a lighting device. The lighting device includes: a light source module; a heat sink in which the light source module is disposed and which has a receiver; an inner case which is disposed in the receiver of the heat sink and has at least one inlet for injecting molding liquid; and a circuitry which is disposed within the inner case and supplies electric power to the light source module. 
         [0032]    The inner case includes: a cylindrical receiver; a connection portion disposed under the receiver in such a manner as to have a diameter less than that of the receiver; and an inclined portion connecting the receiver with the connection portion and having an inlet is disposed therein. 
         [0033]    The inlet is sealed with silicone or resin material. 
         [0034]    The heat sink has an insertion recess. The inner case has a hook coupled to the insertion recess. 
       Advantageous Effects 
       [0035]    In a lighting device according to the embodiment, a light source and a circuitry of the lighting device can be separated from each other. 
         [0036]    In the lighting device according to the embodiment, the lifespan of the lighting device does not depend on the circuitry. 
         [0037]    In the lighting device according to the embodiment, any damaged one out of the light source and circuitry can be freely replaced. 
         [0038]    In the lighting device according to the embodiment, the light source and circuitry can be independently produced and sold. 
         [0039]    In the lighting device according to the embodiment, it is possible both to remarkably reduce defects caused by the destruction of a tap when a bolt is fastened to conventional PSU housings of MR, PAR and a general bulb product and to remarkably reduce defects caused by crack. 
         [0040]    In the lighting device according to the embodiment, it is possible to reduce a manufacturing cost and an assembly lead time by removing parts. 
         [0041]    In the lighting device according to the embodiment, it is possible to maintain security for the design structure of the PSU housing because the PSU housing is fastened within a heat sink by a hook and is difficult to analyze. 
         [0042]    In the lighting device according to the embodiment, an inlet for injecting molding liquid into an inner case is formed and causes the molding liquid to be injected into only heat generating parts, so that a manufacturing cost is reduced. 
         [0043]    While in the past a rubber cover is inevitably added in order to prevent water from leaking at the time of injecting the molding liquid, the lighting device according to the embodiment cures the molding liquid by using the rubber cover as JIG and removes the rubber cover, so that a manufacturing cost is reduced by removing parts. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0044]      FIG. 1  is a perspective view of a lighting device according to a first embodiment; 
           [0045]      FIG. 2  is an exploded perspective view of the lighting device shown in  FIG. 1 ; 
           [0046]      FIG. 3  is a perspective view showing that a light source and a circuitry of the lighting device shown in  FIG. 1  are separated from each other; 
           [0047]      FIG. 4  is a bottom perspective view of a heat sink shown in  FIG. 2 ; 
           [0048]      FIG. 5  is a view showing modified examples of a first terminal and a second terminal, each of which is shown in  FIGS. 2 and 3  respectively; 
           [0049]      FIG. 6  is a perspective view showing a modified example of the lighting device shown in  FIG. 2 ; 
           [0050]      FIG. 7  is a view showing another modified example of the lighting device shown in  FIG. 2 ; 
           [0051]      FIG. 8  is a view showing further another modified example of the lighting device shown in  FIG. 2 ; 
           [0052]      FIG. 9  is an exploded perspective view of a lighting device according to a second embodiment; 
           [0053]      FIG. 10  is an inner cross sectional view of a lighting device according to a third embodiment; 
           [0054]      FIG. 11  is a perspective view showing only an inner case shown in  FIG. 9 ; 
           [0055]      FIG. 12  is a perspective view showing a first modified example of the inner case shown in  FIG. 11 ; 
           [0056]      FIG. 13  is a perspective view showing a second modified example of the inner case shown in  FIG. 11 ; 
           [0057]      FIG. 14  is an inner cross sectional view of the lighting device according to the second embodiment shown in  FIG. 9 ; 
           [0058]      FIG. 15  is a perspective view of the inner case shown in  FIG. 9  which is turned upside down; 
           [0059]      FIG. 16  is a cross sectional view showing that molding liquid is injected into heat generating parts of the circuitry through an inlet of the inner case; and 
           [0060]      FIG. 17  is a perspective view of a rubber cover used to inject the molding liquid through the inlet of the inner case. 
       
    
    
     DETAILED DESCRIPTION 
       [0061]    A thickness or size of each layer is magnified, omitted or schematically shown for the purpose of convenience and clearness of description. The size of each component does not necessarily mean its actual size. 
         [0062]    In description of embodiments of the present invention, when it is mentioned that an element is formed “on” or “under” another element, it means that the mention includes a case where two elements are formed directly contacting with each other or are formed such that at least one separate element is interposed between the two elements. The “on” and “under” will be described to include the upward and downward directions based on one element. 
         [0063]    A lighting device according to various embodiments will be described with reference to the accompanying drawings. 
       First Embodiment 
       [0064]      FIG. 1  is a perspective view of a lighting device according to a first embodiment.  FIG. 2  is an exploded perspective view of the lighting device shown in  FIG. 1 .  FIG. 3  is a perspective view showing that a light source and a circuitry of the lighting device shown in  FIG. 1  are separated from each other.  FIG. 4  is a bottom perspective view of a heat sink shown in  FIG. 2 . 
         [0065]    Referring to  FIGS. 1 to 4 , the lighting device according to the first embodiment may include a cover  100 , a light source  200 , a heat sink  300 , a circuitry  400 , an inner case  500  and a socket  600 . Hereafter, the components will be described in detail respectively. 
         [0066]    The cover  100  has a bulb shape or a hemispherical shape. The cover  100  has an empty space and a partial opening. 
         [0067]    The cover  100  is coupled to the light source  200 . Specifically, the cover  100  may be coupled to a member  250  of the light source  200 . The cover  100  may be coupled to the member  250  by using an adhesive or various methods, for example, bolt-fastening, rotary coupling, hook coupling and the like. In the bolt-fastening method, the cover  100  and the member  250  are coupled to each other by using a bolt. In the rotary coupling method, the screw thread of the cover  100  is coupled to the screw groove of the member  250 . That is, the cover  100  and the member  250  are coupled to each other by the rotation of the cover  100 . In the hook coupling method, the cover  100  and the member  250  are coupled to each other by inserting and fixing the hook (for example, a protrusion, a projection and the like) of the cover  100  into the groove of the member  250 . 
         [0068]    The cover  100  is optically coupled to the light source  200 . Specifically, the cover  100  may diffuse, scatter or excite light emitted from the light source  200 . Here, the inner/outer surface or the inside of the cover  100  may include a fluorescent material so as to excite the light emitted from the light source  200 . 
         [0069]    The inner surface of the cover  100  may be coated with an opalescent pigment. Here, the opalescent pigment may include a diffusing agent diffusing the light. The roughness of the inner surface of the cover  100  may be larger than that of the outer surface of the cover  100 . This intends to sufficiently scatter and diffuse the light emitted from the light source  200 . 
         [0070]    The cover  100  may be formed of glass, plastic, polypropylene (PP), polyethylene (PE), polycarbonate (PC) and the like. Here, the polycarbonate (PC) has excellent light resistance, thermal resistance and rigidity. 
         [0071]    The cover  100  may be formed of a transparent material causing the light source  200  to be visible to the outside or may be formed of an opaque material causing the light source  200  not to be visible to the outside. 
         [0072]    The cover  100  may be formed by a blow molding process. 
         [0073]    The light source  200  may include at least one light source module  210  and the member  250 . 
         [0074]    The light source module  210  is disposed on the member  250  in such a manner as to emit light to the inner surface of the cover  100 . The member  250  may be coupled to the heat sink  300 . The member  250  coupled to the heat sink  300  is able to electrically connect the light source module  210  with the circuitry  400 . Hereafter, the light source module  210  and the circuitry  400  will be described in detail. 
         [0075]    The light source module  210  includes a substrate  211  and at least one light emitting device  215 . The light emitting device  215  is disposed on one side of the substrate  211 . As shown in the drawing, the two light source modules  210  may be provided. Otherwise, one or more than three light source modules  210  may be provided. 
         [0076]    The substrate  211  may be disposed on the member  250 . 
         [0077]    The substrate  211  may have a quadrangular plate shape. However, the substrate  211  may have various shapes without being limited to this. For example, the substrate  211  may have a circular plate shape or a polygonal plate shape. The substrate  211  may be formed by printing a circuit pattern on an insulator. For example, the substrate  211  may include a common printed circuit board (PCB), a metal core PCB, a flexible PCB, a ceramic PCB and the like. Also, the substrate  211  may include a chips on board (COB) allowing an unpackaged LED chip to be directly bonded to a printed circuit board. The substrate  211  may be formed of a material capable of efficiently reflecting light. The surface of the substrate  211  may have a color such as white, silver and the like capable of efficiently reflecting light. 
         [0078]    The surface of the substrate  211  may be coated with a material capable of efficiently reflecting light. The surface of the substrate  211  may be coated with a color capable of efficiently reflecting light, for example, white, silver and the like. 
         [0079]    The light emitting device  215  may be a light emitting diode chip emitting red, green and blue light or a light emitting diode chip emitting UV. Here, the light emitting diode chip may have a lateral type or vertical type and may emit blue, red, yellow or green light. 
         [0080]    The light emitting device  215  may have a fluorescent material. The fluorescent material may include at least any one selected from a group consisting of a garnet material (YAG, TAG), a silicate material, a nitride material and an oxynitride material. Otherwise, the fluorescent material may include at least any one selected from a group consisting of a yellow fluorescent material, a green fluorescent material and a red fluorescent material. 
         [0081]    The member  250  may include a first placement portion  251 , a guide  253  and a second placement portion  255 . Here, the first placement portion  251  may be the top surface of the member  250 . The second placement portion  255  may be the bottom surface of the member  250 . The first placement portion  251  and the second placement portion  255  may be separated by the guide  253 . 
         [0082]    The light source module  210  is disposed in the first placement portion  251 . Specifically, the substrate  211  of the light source module  210  may be disposed in the first placement portion  251 . The first placement portion  251  may have a cavity  251 - 1  into which the substrate  211  may be inserted. The depth of the cavity  251 - 1  may be the same as the thickness of the substrate  211 . A plurality of the cavities  251 - 1  may be provided according to the number of the substrates  211 . 
         [0083]    As shown in  FIG. 3 , a first terminal  270  is disposed in the second placement portion  255 . The first terminal  270  is a conductor through which electricity flows. 
         [0084]    The first terminal  270  may include a positive (+) electrode and a negative (−) electrode. Here, the positive (+) electrode and the negative (−) electrode are disposed apart from each other. The positive (+) electrode is connected to the positive (+) electrode of a second terminal  330 . The negative (−) electrode is connected to the negative (−) electrode of the second terminal  330 . 
         [0085]    The first terminal  270  is electrically connected to the light source module  210  disposed in the first placement portion  251 . The first terminal  270  may be electrically connected to the light source module  210  by using a wire. That is, one end of a wire may be connected to the first terminal  270 . The other end of the wire may be connected to the substrate  211  of the light source module  210 . 
         [0086]    The first terminal  270  may be electrically connected to the light source module  210  by the first terminal  270  itself, That is, one end of the first terminal  270  may be connected to the substrate  211  of the light source module  210 . The other end of the first terminal  270  may be disposed in the second placement portion  255 . 
         [0087]    The first terminal  270  directly contacts with the second terminal  330  of the heat sink  300 . Due to the direct contact between the first terminal  270  and the second terminal  330 , the first terminal  270  and the second terminal  330  may be electrically connected to each other. 
         [0088]    The guide  253  is disposed between the cover  100  and the heat sink  300 . The upper portion of the guide  253  is coupled to the cover  100 . The lower portion of the guide  253  is coupled to heat radiating fins  370  of the heat sink  300 . The first placement portion  251  and the second placement portion  255  may be separated by the guide  253 . 
         [0089]    The second placement portion  255  may be received in a first receiver  310  of the heat sink  300 . When the second placement portion  255  is received in the first receiver  310 , the first terminal  270  mechanically contacts with the second terminal  330 , and then the first terminal  270  and the second terminal  330  can be electrically connected to each other. 
         [0090]    The member  250  may be formed of a material having thermal conductivity. This intends that the member  250  rapidly receives heat generated from the light source module  210  and protects the light source module  210  from the heat. The member  250  may be formed of, for example, Al, Ni, Cu, Mg, Ag, Sn and the like and an alloy including the metallic materials. The member  250  may be also formed of thermally conductive plastic. The thermally conductive plastic is lighter than a metallic material and has a unidirectional thermal conductivity. 
         [0091]    The member  250  may include an insulating portion  290 . When the member  250  is made of a metallic material through which electricity flows, since the first terminal  270  is also a conductor, electrical short-cut may occur between the member  250  and the first terminal  270 . The insulating portion  290  prevents the electrical short-cut. The insulating portion  290  may be disposed in the second placement portion  255  of the member  250  in such a manner as to surround the first terminal  270 . 
         [0092]    The heat sink  300  receives the heat from the light source  200  and the circuitry  400  and radiates the heat. The heat sink  300  may be formed of Al, Ni, Cu, Mg, Ag, Sn and the like and an alloy including the metallic materials. The heat sink  300  may be also formed of thermally conductive plastic. The thermally conductive plastic is lighter than a metallic material and has a unidirectional thermal conductivity. 
         [0093]    The heat sink  300  may have the first receiver  310  and a second receiver  350 . 
         [0094]    The first receiver  310  may be formed by the heat radiating fins  370  and one side of the heat sink  300 . Specifically, the first receiver  310  may be determined by one side  311  of the heat sink  300  and one side  371  of the heat radiating fin  370 . Here, the one side  311  of the heat sink  300  and the one side  371  of the heat radiating fin  370  may be inclined with respect to each other or may be substantially perpendicular to each other. 
         [0095]    The first receiver  310  receives the second placement portion  255  of the member  250 . In this case, since the second placement portion  255  directly contacts with the one side  311  of the first receiver  310  and the one side  371  of the heat radiating fin  370 , the heat from the member  250  may be directly transferred to the heat sink  300  and the heat radiating fins  370 . 
         [0096]    The second terminal  330  is disposed in the first receiver  310 . The second terminal  330  is disposed on the one side  311  of the heat sink  300 . The second terminal  330  is a conductor and directly contacts with the first terminal  270  of the member  250 . Therefore, the second terminal  330  is electrically connected to the first terminal  270 . 
         [0097]    Like the first terminal  270 , the second terminal  330  may include a positive (+) electrode and a negative (−) electrode. The positive (+) electrode and the negative (−) electrode are disposed apart from each other. The positive (+) electrode is connected to the positive (+) electrode of the first terminal  270 . The negative (−) electrode is connected to the negative (−) electrode of the first terminal  270 . 
         [0098]    The second receiver  350  is disposed corresponding to the first receiver  310  of the heat sink  300 . The first receiver  310  is disposed on the second receiver  350 . Contrarily, the second receiver  350  is disposed under the first receiver  310 . 
         [0099]    The second receiver  350  may be a cavity formed in the other side of the heat sink  300 . The second receiver  350  has a predetermined depth in the direction of the first receiver  310 . The depth of the second receiver  350  may be greater than that of the first receiver  310 . The depth of the second receiver  350  may be changed according to the size of the circuitry  400 . 
         [0100]    The second receiver  350  receives the circuitry  400  and the inner case  500 . Specifically, the inner case  500  receives the circuitry  400 , and then the second receiver  350  receives the inner case  500 . 
         [0101]    The heat sink  300  may have the heat radiating fins  370 . The heat radiating fins  370  may extend from or may be connected to the outer surface of the heat sink  300 . The heat radiating fins  370  increase the heat radiating area of the heat sink  300 , thereby improving heat radiation efficiency. 
         [0102]    The one side  371  of the heat radiating fin  370 , together with the one side  311  of the heat sink  300  can determine the first receiver  310 . 
         [0103]    The guide  253  of the member  250  is disposed on the heat radiating fins  370 . The heat radiating fins  370  are able to directly receive heat from the guide  253 . 
         [0104]    The heat sink  300  may include an insulating portion  390 . When the heat sink  300  is made of a metallic material through which electricity flows, since the second terminal  330  is also a conductor, electrical short-cut may occur between the heat sink  300  and the second terminal  330 . The insulating portion  390  prevents the electrical short-cut. The insulating portion  390  may be disposed on the one side  311  of the heat sink  300  in such a manner as to surround the second terminal  330 . 
         [0105]    The circuitry  400  receives external electric power, and then converts the received electric power in accordance with the light source module  210  of the light source  200 . The circuitry  400  supplies the converted electric power to the light source  200 . 
         [0106]    The circuitry  400  is received in the heat sink  300 . Specifically, the circuitry  400  is received in the inner case  500 , and then, together with the inner case  500 , is received in the second receiver  350  of the heat sink  300 . 
         [0107]    The circuitry  400  may include a circuit board  410  and a plurality of parts  430  mounted on the circuit board  410 . 
         [0108]    The circuit board  410  may have a quadrangular plate shape. However, the circuit board  410  may have various shapes without being limited to this. For example, the circuit board  410  may have an elliptical plate shape or a circular plate shape. The circuit board  410  may be formed by printing a circuit pattern on an insulator. The circuit board  410  may include a metal core PCB, a flexible PCB, a ceramic PCB and the like. 
         [0109]    The circuit board  410  is electrically connected to the second terminal  330  of the heat sink  300 . The circuit board  410  may be electrically connected to the second terminal  330  by using a wire. That is, one end of a wire may be connected to the second terminal  330 . The other end of the wire may be connected to the circuit board  410 . 
         [0110]    The circuit board  410  may be electrically connected to the second terminal  330  by the second terminal  330  itself. That is, one end of the second terminal  330  may be directly connected to the circuit board  410 . The other end of the second terminal  330  may be, as shown in  FIG. 2 , disposed on the one side  311  of the heat sink  300 . 
         [0111]    The plurality of parts  430  may include, for example, a 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  210 , and an electrostatic discharge (ESD) protective device for protecting the light source module  210 . 
         [0112]    The inner case  500  receives the circuitry  400  thereinside. The inner case  500  may have a receiver  510  for receiving the circuitry  400 . The receiver  510  may have a cylindrical shape. The shape of the receiver  510  may be changed according to the shape of the second receiver  350  of the heat sink  300 . 
         [0113]    The inner case  500  is received in the heat sink  300 . The receiver  510  of the inner case  500  is received in the second receiver  350  of the heat sink  300 . 
         [0114]    The inner case  500  is coupled to the socket  600 . The inner case  500  may include a connection portion  530  which is coupled to the socket  600 . The connection portion  530  may have a screw thread corresponding to the screw groove of the socket  600 . The diameter of the connection portion  530  may be less than that of the receiver  510 . 
         [0115]    The inner case  500  is a nonconductor. Therefore, the inner case  500  prevents electrical short-cut between the circuitry  400  and the heat sink  300 . The inner case  500  may be made of a plastic or resin material. 
         [0116]    The socket  600  is coupled to the inner case  500 . Specifically, the socket  600  is coupled to the connection portion  530  of the inner case  500 . 
         [0117]    The socket  600  may have the same structure as that of a conventional incandescent bulb. The circuitry  400  is electrically connected to the socket  600 . The circuitry  400  may be electrically connected to the socket  600  by using a wire. Therefore, when external electric power is applied to the socket  600 , the external electric power may be transmitted to the circuitry  400 . 
         [0118]    The socket  600  may have a screw groove corresponding to the screw thread of the connection portion  530 . 
         [0119]      FIG. 5  is a view showing modified examples of the first terminal and the second terminal, each of which is shown in  FIGS. 2 and 3  respectively. 
         [0120]    Terminals  270 ′ and  330 ′ shown in  FIG. 5  are modified examples of the second terminal  330  shown in  FIG. 2  and the first terminal  270  shown in  FIG. 3 . 
         [0121]    Referring to  FIG. 5 , each of the first and the second terminals  270 ′ and  330 ′ may include a circular negative (−) electrode and a positive (+) electrode surrounding the negative (−) electrode. Contrarily, each of the first and the second terminals  270 ′ and  330 ′ may include a circular positive (+) electrode and a negative (−) electrode surrounding the positive (+) electrode. 
         [0122]    Though not shown separately in the drawing, the second terminal  330  shown in  FIG. 2  and the first terminal  270  shown in  FIG. 3  may have a shape which is inserted and fitted like a battery or may have a protruding shape which can be pushed inwardly. 
         [0123]      FIG. 6  is a perspective view showing a modified example of the lighting device shown in  FIG. 2 . 
         [0124]    In description of the lighting device according to the modified example shown in  FIG. 6 , only differences between the lighting device shown in  FIG. 6  and the lighting device shown in  FIGS. 1 to 4  will be described. 
         [0125]    A light source  200 ′ has a screw thread  255   a′.  Specifically, the screw thread  255   a′  may be disposed on a second placement portion  255 ′ of a member  250 ′. More specifically, the screw thread  255   a′  may be disposed on the lateral surface of the second placement portion  255 ′. 
         [0126]    The light source  200 ′ includes the first terminal  270 ′ shown in  FIG. 5 . 
         [0127]    A heat sink  300 ′ has a first receiver  310 ′. The first receiver  310 ′ may be a cavity which is determined by the lateral surface  313 ′ and bottom surface  311 ′ of the heat sink  300 ′. 
         [0128]    The heat sink  300 ′ has a screw groove  313   a′.  The screw groove  313   a′  is coupled to the screw thread  255   a′  of the light source  200 ′. The screw groove  313   a′  may be disposed on the lateral surface  313 ′ of the first receiver  310 ′. 
         [0129]    The heat sink  300 ′ includes the second terminal  330 ′ shown in  FIG. 5 . The second terminal  330 ′ may be disposed on the bottom surface  311 ′ of the heat sink  300 ′. 
         [0130]    In the lighting device shown in  FIG. 6 , the light source  200 ′ and the heat sink  300 ′ can be easily coupled to or separated from each other by rotating them through the use of the screw thread  255   a′  and the screw groove  313   a′.  Also, since the lighting device shown in  FIG. 6  includes the first and the second terminals  270 ′ and  330 ′ shown in  FIG. 5 , the light source  200 ′ and the heat sink  300 ′ can be easily electrically connected to each other without distinguishing between the positive (+) electrode and the negative (−) electrode. 
         [0131]      FIG. 7  is a view showing another modified example of the lighting device shown in  FIG. 2 . 
         [0132]    In description of the lighting device according to the another modified example shown in  FIG. 7 , only differences between the lighting device shown in  FIG. 7  and the lighting device shown in  FIGS. 1 to 4  will be described. 
         [0133]    A light source  200 ″ has a catching projection  253   a″.  The catching projection  253   a″  may be disposed on a guide  253 ″ of a member  250 ″. Specifically, the catching projection  253   a″  may project from the guide  253 ″ toward a heat sink  300 ″. 
         [0134]    The second placement portion  255 ″ of the light source  200 ″ includes the first terminal  270 ′ shown in  FIG. 5 . However, the first terminal  270 ′ may be the first terminal  270  shown in  FIG. 3  without being limited to this. 
         [0135]    The heat sink  300 ″ has a tap  320 ″. A first receiver  310 ″ may be determined by the tap  320 ″ and one side  311 ″ of the heat sink  300 ″. 
         [0136]    The tap  320 ″ has a catching groove  320   a″.  The catching projection  253   a″  of the light source  200 ″ is inserted into the catching groove  320   a″.    
         [0137]    The number of the catching grooves  320   a″  may correspond to the number of the catching projections  253   a″.    
         [0138]    The heat sink  300 ″ includes the second terminal  330 ′ shown in  FIG. 5 . However, the second terminal  330 ′ may be the second terminal  330  shown in  FIG. 2  without being limited to this. 
         [0139]    In the lighting device shown in  FIG. 7 , the light source  200 ″ and the heat sink  300 ″ can be easily coupled to or separated from each other by using the catching projection  253   a″  and the catching groove  320   a″.  Also, since the lighting device shown in  FIG. 7  includes the first and the second terminals  270 ′ and  330 ′ shown in  FIG. 5 , the light source  200 ″ and the heat sink  300 ″ can be easily electrically connected to each other without distinguishing between the positive (+) electrode and the negative (−) electrode. 
         [0140]      FIG. 8  is a view showing further another modified example of the lighting device shown in  FIG. 2 . 
         [0141]    In description of the lighting device according to the further another modified example shown in  FIG. 8 , only differences between the lighting device shown in  FIG. 8  and the lighting device shown in  FIG. 7  will be described. 
         [0142]    A light source  200 ′″ has a catching projection  255   a′″.  The catching projection  255   a′″  may be disposed on a second placement portion  255 ′″ of a member  250 ′. Specifically, the catching projection  255   a′″  may project from the lateral surface of the second placement portion  255 ′. Also, the catching projection  255   a′″  may project from the second placement portion  255 ′″ perpendicularly to a direction in which the light source  200 ′″ is coupled to a heat sink  300 ′″. 
         [0143]    The light source  200 ′ includes the first terminal  270 ′ shown in  FIG. 5 . However, the first terminal  270 ′ may be the first terminal  270  shown in  FIG. 3  without being limited to this. 
         [0144]    The heat sink  300 ′″ has a catching groove  320   a′″.  The catching projection  255   a′″  is inserted into the catching groove  320   a′″.  The catching groove  320   a″  may be bent in the form of “L”. As the catching projection  255   a′″  moves along the “L”-shaped catching groove  320   a′″,  the light source  200 ′″ may be coupled to the heat sink  300 ′″. 
         [0145]    The number of the catching grooves  320   a′″  may correspond to the number of the catching projections  255   a′″.    
         [0146]    The heat sink  300 ′″ includes the second terminal  330 ′ shown in  FIG. 5 . However, the second terminal  330 ′ may be the second terminal  330  shown in  FIG. 2  without being limited to this. 
         [0147]    In the lighting device shown in  FIG. 8 , the light source  200 ′″ and the heat sink  300 ′″ can be easily coupled to or separated from each other by using the catching projection  255   a″  and the catching groove  320   a′″.  Also, since the lighting device shown in  FIG. 8  includes the first and the second terminals  270 ′ and  330 ′ shown in  FIG. 5 , the light source  200 ′″ and the heat sink  300 ′ can be easily electrically connected to each other without distinguishing between the positive (+) electrode and the negative (−) electrode. 
       Second Embodiment 
       [0148]      FIG. 9  is an exploded perspective view of a lighting device according to a second embodiment. 
         [0149]    Referring to  FIG. 9 , the lighting device according to the second embodiment may include a cover  110 , a light source module  130 , a heat sink  140 , a circuitry  150 , an inner case  160  and a socket  170 . In the lighting device according to the second embodiment, the heat sink  140  and the inner case  160  are coupled to each other by a hook coupling method. 
         [0150]    The cover  110  is the same as the cover  100  shown in  FIG. 1  except for the fact that the cover  110  is directly coupled to the heat sink  140 . Therefore, the detailed descriptions of the same parts as those of the aforementioned embodiment will be omitted. 
         [0151]    The light source module  130  is the same as the light source module  210  shown in  FIG. 1  except for the fact that the light source module  130  is disposed on the heat sink  140 . Specifically, the light source module  130  includes a substrate  131  and a light emitting device  132 . The substrate  131  is the same as the substrate  211  shown in  FIG. 1 . The light emitting device  132  is the same as the light emitting device  215  shown in  FIG. 1 . 
         [0152]    The heat sink  140  may be formed of Al, Ni, Cu, Mg, Ag, Sn and the like and an alloy including the metallic materials. The heat sink  140  may be also formed of thermally conductive plastic. The thermally conductive plastic is lighter than a metallic material and has a unidirectional thermal conductivity. 
         [0153]    The heat sink  140  is able to improve heat radiation efficiency by coming in surface contact with the light source module  130 . Here, the heat sink  140  and the light source module  130  may be coupled to each other to come in surface contact with each other by using a structure like a screw, or may be coupled to each other by using an adhesive. 
         [0154]    The heat sink  140  has a flat portion  141  including a first base  141  a and a second base  141  b. Here, a level difference is formed between the first base  141  a and the second base  141   b.  Each of the first base  141  a and the second base  141   b  has a flat plate shape. The second base  141   b  has a seating portion  142  formed therein. The light source module  130  is installed in the seating portion  142 . A guide  143  is formed on the upper circumference of the heat sink  140 . A recess (not shown) into which the cover  110  is inserted is formed between the guide  143  and the first base  141   a.    
         [0155]    A plurality of heat radiating fins  144  are formed on the outer surface of the heat sink  140 . The heat radiating fins  144  may extend from or may be connected to the outer surface of the heat sink  140 . The heat radiating fins  144  increase the heat radiating area of the total heat sink  140 , thereby improving heat radiation efficiency. 
         [0156]    The lower inside of the heat sink  140  has a receiver for receiving the inner case  160 . The receiver may be a predetermined space. The receiver may be a recess or a groove which has a predetermined depth. 
         [0157]    An insertion recess (not shown, see reference numeral  147  of  FIG. 10 ) is formed within a receiver of the inner case  160 , that is, in the inner surface defining the receiver of the inner case  160 . A hook (see reference numeral  164  of  FIG. 11 ) of the inner case  160  is inserted into the insertion recess, so that the inner case  160  is fixed to the heat sink  140 . 
         [0158]    The inner case  160  is disposed within the lower portion of the heat sink  140  and is coupled to the socket  170 . The circuitry  150  is received in the inner case  160 . The circuitry  150  controls the power of the light source module  130  through the electrode terminal of the light source module  130 . 
         [0159]    As shown in  FIG. 11 , the inner case  160  includes the receiver  161 , a connection portion  162  and a level-difference portion  163 . The receiver  161  has a cylindrical shape. The connection portion  162  is formed under the receiver  161  in such a manner as to have a diameter less than that of the receiver  161 . The level-difference portion  163  connects the receiver  161  with the connection portion  162 . 
         [0160]    The inner case  160  may include the hook  164 . Specifically, the hook  164  may be formed on both sides of the outer surface of the receiver  161 . When the inner case  160  is disposed within the lower portion of the heat sink  140 , the hook  164  is coupled to the insertion recess (see reference numeral  147  of  FIG. 10 ) formed within the heat sink  140 . 
         [0161]    The inner case  160  may be variously changed as shown in  FIGS. 11 to 13 . Detailed descriptions of the modified examples of the inner case  160  will be provided in  FIGS. 11 to 13 . 
         [0162]    The inner case  160  may be formed of a nonconductor in order to prevent electrical short-cut between the circuitry  150  and the heat sink  140 . The inner case  160  may be made of a plastic or resin material. 
         [0163]    The circuitry  150  receives electric power from the socket  170  coupled to the lower portion of the inner case  160  and supplies the electric power to the light source module  130 . 
         [0164]    The circuitry  150  converts the received electric power in accordance with the driving voltage of the light emitting module  130 , and then supplies the converted electric power to the light source  130 . For this purpose, the circuitry  150  includes a Converter  153  which is disposed on a substrate  151  and converts AC power supply supplied through the socket  170  into DC power supply, a driving chip which controls the driving of the light source module  130 , and an electrostatic discharge (ESD) protective device for protecting the light source module  130 . 
         [0165]    The socket  170  is coupled to the inner case  160  and supplies electric power to the circuitry  150 . The socket  170  functions to support the lighting device. Like a socket of an incandescent bulb, a screw thread and a screw groove are formed on the outer surface of the socket  170 . The socket  170  is coupled to the inner case  160 , and then is electrically connected to the circuitry  150 . Here, the socket  170  may be connected to the circuitry  150  through a wire or may be directly connected to the circuitry  150 . 
         [0166]    In the lighting device according to the second embodiment, the hook  164  formed on both sides of the outer surface of the inner case  160  is coupled to the insertion recess formed within the heat sink  140 . Accordingly, it is possible to overcome defects caused by the destruction of a tap when a bolt is fastened to conventional power supply unit (PSU) housings of MR and PAR products and to overcome defects caused by crack. Here, the PSU is designated to include the heat sink  140  and the inner case  160  receiving the circuitry  150  therewithin. 
       Third Embodiment 
       [0167]      FIG. 10  is an inner cross sectional view of a lighting device according to a third embodiment. 
         [0168]    Like the lighting device according to the second embodiment shown in  FIG. 9 , in the lighting device according to the third embodiment shown in  FIG. 10 , when the inner case  160  is inserted into the inside of the lower portion of the heat sink  140 , the hook  164  of the inner case  160  is coupled to the insertion recess  147  formed within the heat sink  140 . However, the lighting device according to the third embodiment shown in  FIG. 10  is different from the lighting device according to the second embodiment shown in  FIG. 9  in that the light source module  130  is disposed within the upper portion of the heat sink  140 , and a lens  120  is disposed on the light source module  130 . 
         [0169]    Here, an undescribed reference numeral  144  represents a heat radiating fin formed on the outer surface of the heat sink  140 . An undescribed reference numeral  150  represents a circuitry received in the inner case  160 . 
       Inner Case  160   
       [0170]      FIG. 11  is a perspective view showing only an inner case shown in  FIG. 9 . 
         [0171]    Referring to  FIG. 11 , the inner case  160  includes the receiver  161 , the connection portion  162  and the level-difference portion  163 . The receiver  161  has a cylindrical shape. The connection portion  162  is formed under the receiver  161  in such a manner as to have a diameter less than that of the receiver  161 . The level-difference portion  163  connects the receiver  161  with the connection portion  162 . 
         [0172]    Here, the hook  164  is integrally formed on both sides of the outer surface of the receiver  161 . Specifically, the hook  164  may be disposed on the lower portion of the outer surface of the receiver  161 . However, the hook  164  may be disposed on the upper or central portion of the outer surface of the receiver  161  without being limited to this. 
         [0173]    The hook  164  may be disposed in an opening  165  formed in the outer surface of the inner case  160 . Specifically, the hook  164  may extend toward the opening  165  of the inner case  160 . The hook  164  may project in such a manner that the end of the hook  164  is inclined. 
         [0174]    When the inner case  160  is disposed within the lower portion of the heat sink  140 , the hook  164  is coupled to the insertion recess formed within the heat sink  140 . Therefore, the inner case  160  can be fixed to the heat sink  140  by the coupling of the hook  164  and the insertion recess. 
         [0175]    The hook  164  formed on both sides of the outer surface of the inner case  160  is coupled to the insertion recess formed within the heat sink  140 . Accordingly, it is possible to overcome defects caused by the destruction of a tap when a bolt is fastened to conventional power supply unit (PSU) housings of MR, PAR and a general bulb product and to overcome defects caused by crack. 
       First Modified Example of Inner Case 
       [0176]      FIG. 12  is a perspective view showing a first modified example of the inner case shown in  FIG. 11 . 
         [0177]    Referring to  FIG. 12 , like the inner case  160  shown in  FIG. 11 , an inner case  160 ′ includes the receiver  161 , the connection portion  162  and the level-difference portion  163 . Here, the inner case  160 ′ shown in  FIG. 12  further includes a guide projection  167 . 
         [0178]    The guide projection  167  may project from the outer surface of the receiver  161  and may be formed in the longitudinal direction of the receiver  161 . 
         [0179]    The guide projection  167  may have a hemispherical shape. However, the guide projection  167  may have a polygonal shape including a triangular shape, a quadrangular shape and the like. 
         [0180]    The guide projection  167  may be inserted into a guide groove (not shown) formed within the heat sink (see reference numeral  140  of  FIG. 9 ) in a sliding manner. Here, the guide groove (not shown) of the heat sink  140  is formed at a position corresponding to the position of the guide projection  167  of the inner case  160 ′. The guide groove (not shown) of the heat sink  140  may have a shape corresponding to the shape of the guide projection  167  of the inner case  160 ′. As such, the guide projection  167  may function to indicate a direction in which the inner case  160 ′ and the heat sink  140  are coupled to each other and where the inner case  160 ′ and the heat sink  140  are coupled to each other. 
         [0181]    When the guide projection  167  formed on the outer surface of the inner case  160 ′ is inserted in a sliding manner into the guide groove (not shown) formed within the heat sink  140 , the hook  164  formed on both sides of the outer surface of the inner case  160 ′ is automatically coupled to the insertion recess formed within the heat sink  140 . Accordingly, it is possible to overcome defects caused by the destruction of a tap when a bolt is fastened to conventional power supply unit (PSU) housings of MR, PAR and a general bulb product and to overcome defects caused by crack. 
       Second Modified Example of Inner Case 
       [0182]      FIG. 13  is a perspective view showing a second modified example of the inner case shown in  FIG. 11 . 
         [0183]    Referring to  FIG. 13 , like the inner case  160  shown in  FIG. 11 , an inner case  160 ″ includes the receiver  161 , the connection portion  162  and the level-difference portion  163 . Here, the inner case  160 ″ shown in  FIG. 13  further includes a guide groove  167 ′. 
         [0184]    The guide groove  167 ′ may be formed toward the inside of the receiver  161  in the longitudinal direction of the receiver  161 . 
         [0185]    The guide groove  167 ′ may have a hemispherical shape. However, the guide projection  167  may have a polygonal shape including a triangular shape, a quadrangular shape and the like. 
         [0186]    The guide groove  167 ′ may be inserted into a guide projection (not shown) formed within the heat sink (see reference numeral  140  of  FIG. 9 ) in a sliding manner. Here, the guide projection (not shown) of the heat sink  140  is formed at a position corresponding to the position of the guide groove  167 ′ of the inner case  160 ″. The guide projection (not shown) of the heat sink  140  may have a shape corresponding to the shape of the guide groove  167 ′ of the inner case  160 ″. As such, the guide groove  167 ′ may function to indicate a direction in which the inner case  160 ″ and the heat sink  140  are coupled to each other and where the inner case  160 ″ and the heat sink  140  are coupled to each other. 
         [0187]    When the guide groove  167 ′ formed on the outer surface of the inner case  160 ″ is inserted in a sliding manner into the guide projection (not shown) formed within the heat sink  140 , the hook  164  formed on both sides of the outer surface of the inner case  160 ″ is automatically coupled to the insertion recess formed within the heat sink  140 . Accordingly, it is possible to overcome defects caused by the destruction of a tap when a bolt is fastened to conventional power supply unit (PSU) housings of MR and PAR products and to overcome defects caused by crack. 
         [0188]      FIG. 14  is an inner cross sectional view of the lighting device according to the second embodiment shown in  FIG. 9 .  FIG. 15  is a perspective view of the inner case shown in  FIG. 9  which is turned upside down. 
         [0189]    Referring to  FIGS. 9 ,  14  to  15 , the inner case  160  includes an inlet  166 . The inlet  166  is a hole for injecting molding liquid to heat generating parts received within the inner case  160 . The inlet  166  may be formed in the level-difference portion  163 . 
         [0190]    The circuitry  150  is received within the inner case  160 . Molding liquid  210  is cured and then disposed around the Converter  153  of the circuitry  150 . Since the Converter  153  generates heat from the operation thereof, the molding liquid  210  surrounds the Converter  153  for the purpose of protecting other circuits from the generated heat and radiating the heat. 
         [0191]    The Converter  153  may be an AC-DC converter which changes a value of alternating current voltage or a value of alternating current. 
         [0192]    The molding liquid  210  is injected only around the internal heat generating parts, i.e., the Converter  153  through the inlet  166  formed in the inner case  160 , and then is cured. Through this, a manufacturing cost can be reduced by reducing the amount of the molding liquid used. 
         [0193]    More specifically, in the past, the molding liquid  210  was filled in the entire inside of the inner case  160  through the opening of the inner case  160 . As a result, a molding process was also performed on portions requiring no molding liquid. However, in the embodiment, after a rubber cover  200  is coupled to the opening of the inner case  160 , the molding liquid  210  is injected into only the Converter  153  through the inlet  166  and is cured, so that the amount of the molding liquid used can be reduced. 
         [0194]      FIG. 16  is a cross sectional view showing that the molding liquid is injected into the heat generating parts of the circuitry through the inlet of the inner case.  FIG. 17  is a perspective view of the rubber cover used to inject the molding liquid through the inlet of the inner case. 
         [0195]    The inner case  160  includes the receiver  161 , the connection portion  162  and the level-difference portion  163 . Here, the level-difference portion  163  is an inclined portion. The inlet  166  is formed in the inclined portion  163 . 
         [0196]    The inlet  166  is formed in the inclined portion  163  of the inner case  160  so as to surround only the Converter  153  by the molding liquid  210 . Further, for the sake of preventing the leakage of the molding liquid  210  being injected, the rubber cover  200  is provided in the opening of the receiver  161  of the inner case  160  in the form of JIG. After the molding liquid  210  is injected into the inner case  160  and is cured, the rubber cover  200  is removed. 
         [0197]    The rubber cover  200  includes a flat portion  201  and a border wall  203 . The flat portion  201  has a flat circular shape. The border wall  203  projects from the outer circumference of the flat portion  201  and is coupled to the outer surface of the receiver  161 . A recess  202  is formed in the flat portion  201 . When the rubber cover  200  is coupled to the opening of the receiver  161 , the projecting portion of the circuitry  150  is inserted into the recess  202 . 
         [0198]    A method for injecting the molding liquid  210  into the inside of the inner case  160  by using the rubber cover  200  and the inner case  160  having the inlet  166  formed therein will be described. 
         [0199]    First, the rubber cover  200  is coupled to the opening of the receiver  161  of the inner case  160 . Then, the inner case  160  is installed such that the inlet  166  faces upward (see  FIG. 16 ). Here, the heat generating parts received within the inner case  160 , i.e., the Converter  153  is, as shown in  FIG. 16 , positioned in the lower portion of the inner case  160 . 
         [0200]    Then, the molding liquid  210  is injected through the inlet  166  of the inner case  160 . Here, the molding liquid  210  is injected in such a manner as to sufficiently cover only the heat generating parts including the Converter  153 , which are received within the inner case  160 . 
         [0201]    Lastly, the molding liquid  210  is cured and then the rubber cover  200  is removed. 
         [0202]    In the foregoing molding method, after the molding liquid  200  injected through the inlet  166  is cured, the inlet  166  may be sealed by being molded with silicone or resin material. 
         [0203]    As such, in the lighting device according to the second embodiment, the inlet  166  used to inject the molding liquid  210  into the inner case  160  is formed and the molding liquid is injected into only the heat generating parts. Through this, a manufacturing cost can be reduced. Also, the rubber cover  200  is provided in the form of JIG and removed after the molding liquid is cured. As a result, a manufacturing cost can be reduced by removing the parts. 
         [0204]    Although embodiments of the present invention were described above, these are just examples and do not limit the present invention. Further, the present invention may be changed and modified in various ways, without departing from the essential features of the present invention, by those skilled in the art. For example, the components described in detail in the embodiments of the present invention may be modified. Further, differences due to the modification and application should be construed as being included in the scope and spirit of the present invention, which is described in the accompanying claims.