Patent Document

This application claims the benefit of Korean Patent Application No. 10-2011-0042253, filed on May 4, 2011 which is hereby incorporated in its entirety by reference as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments relate to a light emitting device module and a lighting system including the same. 
     2. Discussion of the Related Art 
     Light emitting devices, such as light emitting diodes (LEDs) and laser diodes (LDs), which use a Group III-V or Group II-VI compound semiconductor material, may render various colors such as red, green, blue, and ultraviolet by virtue of development of thin film growth technologies and device materials. It may also be possible to produce white light having high efficiency using fluorescent materials or through color mixing. Further, the light emitting devices have advantages, such as low power consumption, semi-permanent lifespan, fast response time, safety, and environmentally friendly properties as compared to conventional light sources, such as fluorescent lamps and incandescent lamps. 
     Therefore, these light emitting elements are increasingly applied to transmission modules of optical communication units, light emitting diode backlights as a replacement for cold cathode fluorescent lamps (CCFLs) constituting backlights of liquid crystal display (LCD) devices, lighting apparatuses using white light emitting diodes as a replacement for fluorescent lamps or incandescent lamps, headlights for vehicles and traffic lights. 
     Light emitting device modules are widely used in lighting apparatuses and display apparatuses. Such a light emitting device module is mounted in a package body such that they are electrically connected. 
     SUMMARY OF THE INVENTION 
     Accordingly, the embodiments are directed to a light emitting device module and a lighting system including the same, which are capable of achieving an improvement in optical efficiency. 
     Additional advantages, objects, and features of the embodiments will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from the embodiments. The objectives and other advantages of the embodiments may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve this object and other advantages and in accordance with the purpose of the embodiments, as embodied and broadly described herein, a light emitting device module includes a substrate, at least one support disposed on a surface of the substrate, a heat transfer member disposed on the substrate and the support, the heating transfer member having a cavity formed in at least a portion of the heat transfer member, first conductive layer and second conductive layer contacting the heat transfer member via an insulating layer, the first conductive layer and the second conductive layer being electrically isolated from each other in accordance with exposure of the insulating layer or exposure of the heat transfer member, and at least one light emitting device electrically connected to the first conductive layer and the second conductive layer, contacting the at least one light emitting device is thermally contacted an exposed portion of the heat transfer member. 
     At least a portion of the support may contact the heat transfer member. 
     The substrate may be a bracket included in a lighting apparatus or a backlight unit. 
     The support may include a pattern formed at the bracket. 
     The pattern may include patterns respectively formed at the surface of the substrate contacting the heat transfer member and an opposite surface of the substrate. 
     The support may include a heat transfer layer formed on the substrate. The cross-sectional area of the support may be greatest in a side closest to the substrate. 
     The light emitting device module may further include at least one circuit board disposed on the heat transfer member. 
     The support may be disposed to correspond to the circuit board. 
     The support may support the heat transfer member outside the cavity. 
     At least two support may support the heat transfer member in at least two regions outside the cavity. 
     The support may have a trapezoidal shape. 
     In another aspect of the embodiments, a light emitting device module includes a heat transfer member having a cavity formed in at least a portion of the heat transfer member, at least one support for supporting the heat transfer member outside the cavity, first conductive layer and second conductive layer contacting the heat transfer member via an insulating layer, the first conductive layer and the second conductive layer being electrically separated from each other in accordance with exposure of the insulating layer or exposure of the heat transfer member, at least one light emitting device electrically connected to the first conductive layer and the second conductive layer, the at least one light emitting device is thermally contacted an exposed portion of the heat transfer member, and at least one circuit board disposed on the heat transfer member, the circuit board corresponds to the support. 
     At least two support may support the heat transfer member in at least two regions outside the cavity. 
     At least a portion of the support may contact the heat transfer member. 
     The support may include a heat transfer layer. 
     The support may have a trapezoidal shape. 
     In another aspect of the embodiments, a lighting system includes a light emitting device module including a substrate, at least one support disposed on a surface of the substrate, a heat transfer member disposed on the substrate and the support, the heating transfer member having a cavity formed in at least a portion of the heat transfer member, first conductive layer and second conductive layer contacting the heat transfer member via an insulating layer, the first conductive layer and the second conductive layer being electrically separated from each other in accordance with exposure of the insulating layer or exposure of the heat transfer member, and at least one light emitting device electrically connected to the first conductive layer and the second conductive layer, the at least one light emitting device is thermally contacted an exposed portion of the heat transfer member, a circuit board for supplying current to the light emitting device module, and an optical member for transmitting light emitted from the light emitting device module. 
     The substrate may be a bracket. The circuit substrate may correspond to the support. The optical member may be a light guide plate included in a backlight unit. 
     The substrate may be a bracket. The bracket may contact a heat dissipation unit included in a lighting apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the principle of the disclosure. In the drawings: 
         FIGS. 1A and 1B  are sectional views illustrating light emitting device modules according to first and second embodiments, respectively; 
         FIGS. 2 and 3  are plan views illustrating light emitting device arrays according to different embodiments; 
         FIG. 4  is a sectional view illustrating a light emitting device module according to a third embodiment; 
         FIG. 5A  is an enlarged view corresponding to a portion “F” of  FIG. 4 ; 
         FIGS. 5B to 5G  are enlarged views corresponding to the portion “F” of  FIG. 4  to illustrate different embodiments from that of  FIG. 5A ; 
         FIGS. 6A to 6I  are views illustrating a method for manufacturing the light emitting device module of  FIG. 4  in accordance with an exemplary embodiment; 
         FIGS. 7A to 7G  are views illustrating a method for manufacturing the light emitting device module of  FIG. 4  according to another embodiment; 
         FIG. 8  is a sectional view illustrating a light emitting device module according to an fourth embodiment; 
         FIG. 9  shows cross-sectional views respectively taken in directions corresponding to a longer axis and a shorter axis in the light emitting device module of  FIG. 4 ; 
         FIG. 10  is a sectional view illustrating a light emitting device module according to a fifth embodiment; 
         FIG. 11  is a sectional view illustrating a light emitting device module according to a sixth embodiment; 
         FIG. 12  is a perspective view illustrating a light emitting device module according to a seventh embodiment; 
         FIG. 13  is an exploded perspective view illustrating a lighting apparatus including the light emitting device module according to one of the above-described embodiments; and 
         FIG. 14  is a view illustrating a display apparatus including the light emitting device module according to one of the above-described embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments, examples of which are illustrated in the accompanying drawings. 
     In the following description of the embodiments, it will be understood that, when an element such as a layer (film), region, pattern, or structure is referred to as being “on” or “under” another element, it can be “directly” on or under another element or can be “indirectly” formed such that an intervening element may also be present. Also, terms such as “on” or “under” should be understood on the basis of the drawings. 
     In the drawings, dimensions of layers are exaggerated, omitted or schematically illustrated for clarity and description convenience. In addition, dimensions of constituent elements do not entirely reflect actual dimensions thereof. 
       FIGS. 1A and 1B  illustrate light emitting device modules according to first and second embodiments, respectively. 
     In the light emitting device module according to each embodiment, a light emitting device  240  is disposed in a cavity formed at a heat transfer member  210 . The light emitting device  240  may include a vertical light emitting device, a horizontal light emitting device, or a flip-chip type light emitting device. In these embodiments or other embodiments, the light emitting device  240  may be semiconductor light emitting device, for example light emitting diode. The heat transfer member  210  may be made of a material having excellent thermal conductivity. For example, copper (Cu) or aluminum may be used for the material of the heat transfer member  210 . 
     The light emitting device  240  may be disposed on a bottom of the cavity formed at the heat transfer member  210 . The cavity may have side walls extending vertically. In the illustrated embodiments, the side walls of the cavity are outwardly inclined as they extend upwardly such that the width of the cavity is increased as the cavity extends upwardly, when viewing in the drawings. 
     Although the heat transfer member  210 , which defines the cavity, is illustrated as being sharply bent, it may be bent in a streamlined shape. 
     An insulating layer  220  is formed over the heat transfer member  210 . The insulating layer  220  may be made of, for example, polyimide. The insulating layer  220  may be patterned to expose at least a portion of the heat transfer member  210  at the bottom of the cavity. That is, the insulating layer  220  may not be formed on at least a portion of the bottom of the cavity. 
     A first conductive layer  230   a  and a second conductive layer  230   b  are formed such that the insulating layer  220  is interposed between the heat transfer member  210  and the first conductive layer  230   a  and the second conductive layer  230   b . In accordance with this structure, the first conductive layer  230   a  the and second conductive layer  230   b , which supply current to the light emitting device  240 , are electrically insulated from the heat transfer member  210  by the insulating layer  220 . This will be described later 
     The first conductive layer  230   a  and the second conductive layer  230   b  may have the same shape as the insulating layer  220 . However, each of the first conductive layer  230   a  and the second conductive layer  230   b  may be formed to have an open region at a portion thereof adjacent to a circuit board  270 , so as to expose a portion of the insulating layer  220 . This will be described later. The first conductive layer  230   a  and the second conductive layer  230   b  may be made of a copper foil. 
     The light emitting device  240  is electrically connected to the first conductive layer  230   a  and the second conductive layer  230   b . This electrical connection may be achieved through bonding of wires  250  as in the illustrated embodiments. A resin layer  260  fills the cavity to protect the light emitting device  240  and wires  250 . A fluorescent substance is contained in the resin layer  260 . Accordingly, it may be possible to vary the wavelength of light emitted from the light emitting device  240 . 
     A portion of the heat transfer member  210  extends horizontally at a region around a top of the cavity. A circuit board  270  is connected to the horizontal portion of the heat transfer member  210  via the insulating layer  220  and the first conductive layer  230   a  and the second conductive layer  230   b.    
     The circuit board  270  may be coupled to the first conductive layer  230   a  and the second conductive layer  230   b  by a conductive adhesive  280 . The circuit board  270  may include a printed circuit board (PCB), a metal PCB (MPCB), or a metal core PCB (MCPCB). 
     As shown in a portion “A” of  FIG. 1A , the insulating layer  220  is partially exposed in a region between the cavity and the circuit board  270 . That is, the first conductive layer  230   a  and the second conductive layer  230   b  are not formed in the above-described region such that they are opened in the region to expose a portion of the insulating layer  220  corresponding to the region. In this case, the conductive adhesive  280  may also not be formed on the exposed portion of the insulating layer. 
     In the embodiment of  FIG. 1B , a reflective layer  235  is formed on the first conductive layer  230   a  and the second conductive layer  230   b  within the cavity. The reflective layer  235  may be made of a material capable of reflecting light emitted from the light emitting device  240  in order to send the reflected light to an outside of the cavity. A silver (Ag) may be coated over the reflective layer  235 . 
     The heat transfer member  210  may be coupled to a substrate  100  via an adhesive layer  110 . The substrate  100  may function as a body of the light emitting device module. When the substrate  100  is made of a metal, it may function as a bracket to support a light source module in a backlight unit or a lighting apparatus. 
     The adhesive layer  110  has excellent thermal conductivity. The adhesive layer  110  may bond the heat transfer member  210  to the substrate  100 . When the substrate  100  is made of a metal to function as a bracket, heat emitted from the light emitting device  240  is directly transferred to the substrate  100  because it is unnecessary to use a resin such as polyphthalamide (PPA) in the backlight unit or lighting apparatus. 
       FIGS. 2 and 3  are views illustrating light emitting device module arrays according to exemplary embodiments, respectively. 
     The above-described light emitting device module may be manufactured from an array of light emitting devices. That is, such a light emitting device array may be separated into individual light emitting device modules after being subjected to a process in which an insulating layer, a conductive layer, etc. are laminated over the heat transfer member.  FIG. 2  is a view illustrating a state in which the light emitting device array has not been separated into individual light emitting device modules.  FIG. 3  illustrates a structure in which a plurality of light emitting devices can be disposed in each cavity. 
       FIG. 4  is a sectional view illustrating a light emitting device module according to a third embodiment. 
     The light emitting device module according to this embodiment is similar to that of  FIG. 1 , except that the heat transfer member  210  has a step due to formation of a cavity, so that it is spaced apart from the substrate  100  in a region corresponding to the circuit board  270 , and a support  10  is formed at the substrate  100  to withstand the weight of the circuit board  270 , etc in the region. 
       FIG. 5A  is an enlarged view corresponding to a portion “F” of  FIG. 4 . 
     Referring to  FIG. 32A , the support  10  is formed at the substrate  100  in the region corresponding to the circuit board  270  in order to support the heat transfer member  210 . Practically, in one light emitting device module, supports  10  are provided in regions at opposite sides of the cavity, respectively. For simplicity of description, the following description will be given only in conjunction with the support  10  provided in the region at one side of the cavity. 
     The support  10  is disposed on the substrate  100  in a region where the heat transfer member  210  does not contact the substrate  100 . Referring to  FIG. 32A , three regions, namely, first to three regions, are defined. In the third region, the substrate  100  contacts the heat transfer member  210  via the adhesive layer  110 . Accordingly, it is unnecessary to dispose the support  10  in the third region. 
     In the second region, the heat transfer member  210  has an inclination. This inclination is caused by the fact that the heat transfer member  210  has different heights in a region where the cavity is formed and a region where the circuit board is disposed, while extending horizontally in the regions. 
     In the first region, the heat transfer member  210  is spaced apart from the substrate  100  by a certain distance. To this end, in the first region, the support  10  is formed on the substrate to contact the heat transfer member  210 , and thus to support the heat transfer member  210 . In this case, the support receives a load applied from the circuit board  270  to the heat transfer member  210 . Therefore, at least a portion of the support  10  should contact the heat transfer member  210 . 
     In the case of  FIG. 5A , the support  10  includes a first support portion  10   a  and a second support portion  10   b . The support  10  may include at least one support portion, taking into consideration the magnitude of load and the width of the first region. The support  10  may be formed of an elastic member to withstand the above-described load. The support  10  may also be made of a heat transferable material to function as a heat transfer layer capable of transferring heat generated from the circuit board  270  to the substrate  100 , which is made of a metal material. Such configurations may also be applied to the embodiments, which will be described later. 
     The height h of the support  10  may be equal to the sum of the height difference in the heat transfer member  210  and the height of the adhesive layer  110 . 
       FIGS. 5B to 5G  are enlarged views corresponding to the portion “F” of  FIG. 4  to illustrate different embodiments from that of  FIG. 5A . 
     In the embodiment of  FIG. 5B , the support  10  is formed in accordance with patterning of the substrate  100  in the region where the substrate  100  does not contact the heat transfer member  210 , namely, the first region. That is, in this embodiment, the support  10  is made of the same material as the substrate  100 . In this case, the substrate  100  is made of a metal, so that it may be possible to increase the area of the substrate  100  to absorb heat emitted from the circuit board  270 . 
     Similarly to the previous embodiment, the support  10  may include a first support portion  10   a  and a second support portion  10   b  in this embodiment. The support  10  may include at least one support portion, taking into consideration the magnitude of load and the width of the first region. 
     The embodiment of  FIG. 5C  is similar to the embodiment of  FIG. 5B , except that the substrate  100  has the same pattern at the upper and lower surfaces thereof. That is, when it is assumed that the direction of the substrate  100  to face the heat transfer member  210  is a first direction of the substrate  100 , and the direction opposite to the first direction is a second direction of the substrate  100 , the substrate  100  has the same pattern in the first and second directions. 
     The embodiments of  FIGS. 5B and 5C  are different in terms of manufacturing processes. That is, in the case of  FIG. 5B , the substrate  100  may be injection-molded to have the support  10 , whereas, in the case of  FIG. 5C , the substrate  100  is injection-molded without having the support  100 , and then pressed to form the support  10 . 
     The embodiment of  FIG. 5D  is similar to the embodiment of  FIG. 5C , except that the pattern forming the support  10  is subjected to a rounding process. That is, the support  10  has a round edge to prevent impact from being generated at a portion of the support  10  contacting the heat transfer member  210 . 
     In each embodiment of  FIGS. 5E to 5G , the support  10  is formed in accordance with patterning of the substrate  100 . The size or area of the support  10  in the direction of the support  10  contacting the heat transfer member  210  is smaller than that of the support  10  in the direction of the support  10  contacting the substrate  100 . For example, the support  10  has a shape similar to a trapezoidal shape. That is, the support  10  has a surface facing the heat transfer  210  member and another surface facing the substrate  100 , the cross-sectional area of the surface facing the heat transfer member  210  is less than the cross-sectional area of the surface facing substrate  100 . 
     The cross-sectional area of the support  10  may be greatest in a side closest to the substrate  100 . And, the cross-sectional area of the support  10  may be decreased in corresponding to a distance from the substrate  100 . 
     In the above-described structure, the support  10 , which has a trapezoidal shape, stably supports the heat transfer member  210 . The support  10  may be protruded from the substrate  100 , as in the structure of  FIG. 5A . The support  10  may also be formed by pressing the substrate  100  after injection molding thereof to respectively form patterns at two surfaces of the substrate  100 , as in the structure of  FIG. 5F . Alternatively, the patterns of the substrate  100  in the structure of  FIG. 32F  may be subjected to a rounding process to form the structure of  FIG. 5G . 
       FIGS. 6A to 6I  are views illustrating a method for manufacturing the light emitting device module of  FIG. 4  in accordance with an exemplary embodiment. 
     In accordance with the illustrated method, as shown in  FIG. 6A , the insulating layer  220  and a conductive layer  230  are first formed over a base substrate  290 . In this case, the insulating layer  220  may be fixed to the base substrate  290  by an adhesive  295 . 
     For the conductive layer  230 , which is bonded to the insulating layer  220 , a copper foil, to which a polyimide film is bonded, may be used. Since the polyimide film has a small thickness of, for example, 5 μm, it is very advantageous in terms of thermal resistance. 
     As shown in  FIG. 6B , a mask  300  is selectively formed on the conductive layer  230 . Using the mask  300 , the conductive layer  230  and insulating layer  220  are subsequently patterned. In this case, the conductive layer  230  may be divided into two portions, namely, the first conductive layer  230   a  and the second conductive layer  230   b.    
     The middle region of  FIG. 6C , from which the insulating layer  220 , etc. are removed, corresponds to the bottom of the cavity in  FIG. 4 . 
     As shown in  FIG. 6D , the base substrate  290  is then removed. Subsequently, the heat transfer member  210  is bonded to the insulating layer  220 . In this case, the bonding may be achieved using the previously-coated adhesive  295  or an additional adhesive  295 . The base substrate  290  is removed after functioning as a stiffener in the manufacturing procedure. 
     In this case, the insulating layer  220  and adhesive  295  form two layers between the heat transfer member  210  and each of the firs and second conductive layers  230   a  and  230   b . Since the polyimide of the insulating layer  220  function as an electrical insulator, and the adhesive  295  performs a bonding function, an optimal structure capable of achieving an improvement in heat transfer characteristics may be obtained. 
     Since the heat transfer member  210 , which has a metal structure thicker than the copper foil, supports the light emitting device  240 , it may be possible to achieve a remarkable enhancement in reliability. It is also unnecessary to achieve an increase in stiffness using a transparent resin. Accordingly, the material of the resin layer may be selected from more various materials, and thus, cost reduction may be achieved. 
     Furthermore, it may be possible to achieve a great enhancement in heat dissipation characteristics in accordance with a combination of the insulating layer  220  and adhesive  295 . For example, when only the insulating layer  220 , which is made of polyimide, is applied between each of the first conductive layer  230   a  and the second conductive layer  230   b , which is made of a copper foil having a thickness of, for example, 18 μm, and the heat transfer member  210 , which is made of a copper foil having a thickness of 125 μm, the insulating layer  220  is required to have a thickness of, for example, 20 to 30 μm, when tolerance and bonding force are taken into consideration. 
     However, when the insulating layer  220  is applied along with the adhesive  295 , it may be possible to reduce the thickness of the polyimide insulating layer  220 . This may be achieved by thinly coating polyimide over the conductive layer  230  made of a copper foil, to form the insulating layer  220 . Thus, the thickness of the polyimide insulating layer  220  may be reduced to 5 μm. Since the thin polyimide insulating layer  220 , which has a thickness of 5 μm, provides insulation characteristics, the adhesive  295  may achieve an enhancement in thermal conductivity. 
     Thereafter, a pressure is applied to the edges of the heat transfer member  210  to form a step at the heat transfer member  210 , as shown in  FIG. 6E . At this time, the insulating layer  220  and the first conductive layer  230   a  and the second conductive layer  230   b  are also stepped in the same manner as the heat transfer member  210 . 
     The above-described step may be formed using a method for pressing the heat transfer member  210  or the like. The step may be formed as the heat transfer member  210  is bent in a vertical direction or in a streamlined shape. 
     Thereafter, a pressure is applied to the heat transfer member  210  to bend the heat transfer member  210 , and thus to form the cavity. At this time, the insulating layer  220  and the first conductive layer  230   a  and the second conductive layer  230   b  are also bent. The cavity may have a shape in which the edges of the cavity have a curved shape or a shape in which the edges of the cavity have a point of inflection, as shown in  FIG. 31 . 
     The support, which will be described later, may have a height varying in accordance with the bending degree of the heat transfer member  210 . 
     Subsequently, the light emitting device  240  is mounted on the bottom of the cavity, as shown in  FIG. 6F . The light emitting device  240  is wire-bonded to the first conductive layer  230   a  and the second conductive layer  230   b  by the wires  250 . In this case, electrode pads  255  may be formed on the first conductive layer  230   a  and the second conductive layer  230   b . The wires  250  are bonded to the electrode pads  255 . 
     Thereafter, a resin layer  260  fills the cavity to protect the light emitting device  240  and wires  250 , as shown in  FIG. 6G . A fluorescent substance is contained in the resin layer  260 . Accordingly, it may be possible to vary the wavelength of light emitted from the light emitting device  240 . 
     Subsequently, the support  10  is prepared to be provided at the substrate  100 , as shown in  FIG. 66H . The support  10  may be prepared in the form of a separate member made of a material different from that of the substrate  100 , as in this embodiment, or in the form of a structure integral with the substrate  100 , as in other embodiments. An adhesive layer  110  is formed on the substrate  100  to bond the support  10  to the substrate  100 . 
     As shown in  FIG. 61 , the heat transfer member  210  is boned to the substrate  100  by the adhesive layer  110  while coming into contact with the substrate  100  via the support  10 . The shape in a portion “F” of  FIG. 61  has been described with reference to  FIG. 5A , etc. 
       FIGS. 7A to 7G  are views illustrating a method for manufacturing the light emitting device module of  FIG. 4  according to another embodiment of the present invention. 
     In this embodiment, the base substrate  290  is not used, different form the embodiment of  FIG. 6A , etc. Also, the insulating layer  220  may be fixed to the heat transfer member  210  without using the adhesive  295 . In this case, a material having a bonding property such as polyimide may be used for the insulating layer  220 . In other embodiments, the adhesive  295  may be dispensed with. 
     First, the heat transfer member  210  is prepared, as shown in  FIG. 7A . The heat transfer member  210  may be made of a material having excellent thermal conductivity. For example, copper (Cu) or aluminum (Al) may be used for the material of the heat transfer member  210 . 
     As shown in  FIG. 7B , the insulating layer  220  and the conductive layer  230  are fixed on the heat transfer member  210  by the adhesive  295 . 
     The conductive layer  230  is then patterned as shown in  FIG. 7C . In this case, the conductive layer  230  is partially removed to partially expose the insulating layer  220 . The conductive layer  230  is divided into first conductive layer  230   a  and the second conductive layer  230   b  by the region S where the insulating layer is exposed. 
     The process of partially removing the conductive layer  230  may be achieved using a mask, which is coated, as shown in  FIG. 7B , etc., to selectively remove a portion of the conductive layer  230 . Although opposite ends of the conductive layer  230  are not removed, namely, portions of the insulating layer  220  corresponding to the opposite ends are not exposed, in the illustrated embodiment, an open region, through which the insulating layer  220  is exposed, may be formed around the cavity, as shown in  FIG. 7C , etc. 
     Thereafter, a pressure is applied to the heat transfer member  210  to bend the heat transfer member  210 , and thus to define the cavity, as shown in  FIG. 7D . At this time, the insulating layer  220  and the first conductive layer  230   a  and the second conductive layer  230   b  are also bent. The cavity may be formed to have a shape in which the edges of the cavity have a curved shape, or a shape in which the edges of the cavity have a point of inflection. 
     The reflective layer  235  is then formed over the first conductive layer  230   a  and the second conductive layer  230   b , as shown in  FIG. 7E . The reflective layer  235  may be made of a material capable of reflecting light emitted from the light emitting device  240  in order to send the reflected light to an outside of the cavity. A silver (Ag) may be coated over the reflective layer  235 . 
     The light emitting device  240  is then disposed in the cavity of the heat transfer member  210 . Thus, a light emitting device module as shown in  FIG. 7F  is completely obtained. 
     When the heat transfer member  210  of the light emitting device module is bonded to the substrate  100  by the adhesive layer  110 , a light emitting device module as shown in  FIG. 7G  is completely obtained. Since it is unnecessary to form a package body using a polyphthalamide (PPA) resin, the effect of transferring heat emitted from the light emitting device  240  to the heat transfer member  210  is great. 
     In this case, the supports  10  are formed on the substrate  100  outside the cavity to support the load applied to the heat transfer member  210 . As described above, circuit boards (not shown) may be arranged on the first conductive layer  230   a  and the second conductive layer  230   b  corresponding to the supports  10 , respectively. 
     In a light emitting device module according to an eighteenth embodiment of  FIG. 8 , the light emitting device  240  is electrically connected to the first conductive layer  230   a  and the second conductive layer  230   b  without using wire bonding. That is, in this embodiment, the light emitting device  240  is of a flip-chip type so that it may be directly bonded to the first conductive layer  230   a  and the second conductive layer  230   b.    
     The above-described light emitting device module may be manufactured from an array of light emitting devices. That is, such a light emitting device array may be separated into individual light emitting device modules after being subjected to a process in which an insulating layer, a conductive layer, etc. are laminated over the heat transfer member. Each of the separated light emitting device modules is then bonded to the bracket. Alternatively, the separation into the individual light emitting device modules may be achieved after the bonding of the heat transfer member to the bracket. 
       FIG. 9  shows cross-sectional views respectively taken in directions corresponding to a longer axis and a shorter axis in the light emitting device module of  FIG. 4   a .  FIG. 9  omits illustration of the light emitting device, etc. 
     FIG.  9 (B-B′), which is a cross-sectional view taken in the longer axis direction of the light emitting device module, shows exposure of the heat transfer member  210  in a central portion of the cavity. However, in FIG.  9 (C-C′), which is a cross-sectional view taken in the shorter axis direction of the light emitting device module, the heat transfer member  210  is not exposed at the bottom of the cavity. That is, the heat transfer member  210  is exposed in a short-axis direction within the cavity. 
     Referring to FIG.  9 (B-B′), the supports  10  are formed between the substrate  100  and the heat transfer member  210  to support the weights of the circuit boards  270 , respectively. At the regions shown in FIG.  9 (C-C′), however, the circuit boards  270  are not disposed, so that the supports  10  may not be provided at the regions. 
       FIG. 10  is a sectional view illustrating a light emitting device module according to a fifth embodiment of the present invention. 
     In this embodiment, a plurality of light emitting devices  240  is disposed in the cavity. The light emitting devices are wire-bonded to one another by wires  250 . The light emitting devices  240  arranged at opposite side edges of the cavity are wire-bonded to the first conductive layer  230   a  and the second conductive layer  230   b  by wires  250 . 
     Similarly to the previous embodiments, the heat transfer member may be exposed at the central region C of the cavity. Each light emitting device  240  directly contacts the heat transfer member  210  exposed at the bottom of the cavity. 
     Circuit boards (not shown) may be disposed on the first conductive layer  230   a  and the second conductive layer  230   b  in regions outside the cavity, respectively. Supports  10  are disposed on the substrate  100  beneath the regions outside the cavity, respectively, to support the heat transfer member  210 . 
       FIG. 11  is a sectional view illustrating a light emitting device module according to a sixth embodiment of the present invention. 
     This embodiment is similar to the embodiment of  FIG. 10 , except that the heat transfer member  210  is not exposed at the bottom of the cavity. That is, the insulating layer  220  and the first conductive layer  230   a  and the second conductive layer  230   b  are completely disposed on the heat transfer member  210  in a region corresponding to the bottom of the cavity where the light emitting devices  240  are disposed. 
     In order to avoid short of current supplied to each light emitting device  240 , the first conductive layer  230   a  and the second conductive layer  230   b  are removed from a region C corresponding to a portion of the bottom of the cavity. Circuit boards (not shown) may be disposed on the first conductive layer  230   a  and the second conductive layer  230   b  in regions outside the cavity, respectively. Supports  10  are disposed on the substrate  100  beneath the regions outside the cavity, respectively, to support the heat transfer member  210 . 
       FIG. 12  is a perspective view illustrating a light emitting device module according to a seventh embodiment of the present invention. 
     In this embodiment, two light emitting devices  240  are disposed in the cavity. Wires are connected to two electrode pads  242  and  244  provided at each light emitting device  240 , respectively. The two light emitting devices  240  are connected to the first conductive layer  230   a  and the second conductive layer  230   b  by wires, respectively. The light emitting devices  240  are electrically connected to each other via a third conductive layer  258 , which is of an island type. 
     Electrode pads  255  are formed at each of the first conductive layer  230   a  and the second conductive layer  230   b  connected to respective light emitting devices  240  by wires. A resin layer  260  fills the cavity to protect the light emitting devices  240  and wires. 
     Similarly to the above-described embodiments, each of the first conductive layer  230   a  and the second conductive layer  230   b  is partially patterned in a region between the cavity and an external circuit board (not shown) to expose a portion of the insulating layer  220  in this embodiment. 
     Hereinafter, a lighting apparatus and a backlight unit will be described as an embodiment of a lighting system in which one of the above-described light emitting device module is arranged.  FIG. 13  is an exploded perspective view illustrating a lighting apparatus including the light emitting device module according to one of the above-described embodiments. 
     The lighting apparatus includes a light source  600  for projecting light, a housing  400  in which the light source  600  is mounted, a heat dissipation unit  500  to dissipate heat generated from the light source  600 , and a holder  700  for coupling the light source  600  and heat dissipation unit to the housing  400 . 
     The housing  400  includes a socket connection part  410  connected to an electric socket (not shown), and a body part  420  connected to the socket connection part  410 . The light source  600  is received in the body part  420 . A plurality of air holes  430  may be formed through the body part  420 . 
     Although a plurality of air holes  430  are formed through the body part  420  of the housing  400  in the illustrated case, a single air hole  430  may be formed through the body part  420 . Although the plural air holes  430  are circumferentially arranged, various arrangements thereof may be possible. 
     The light source  600  includes a circuit board  610  and a plurality of light emitting device modules  650  mounted on the circuit board  610 . Here, the circuit board  610  may be shaped to be fitted in an opening formed at the housing  400 . Also, the circuit board  610  may be made of a material having high thermal conductivity so as to transfer heat to the heat dissipation unit  500 , as will be described later. 
     The holder  700  is disposed under the light source  600 . The holder  700  includes a frame and air holes. Although not shown, an optical member may be disposed under the light source  600  so as to diffuse, scatter or converge light projected from the light emitting device modules  650  of the light source  600 . 
     The above-described lighting apparatus, which employs the above-described light emitting device modules according to one of the above-described embodiments, exhibits an improvement in brightness because it is possible to reduce the amount of light absorbed into the insulating layer of each light emitting device module after being emitted from the corresponding light emitting device. Also, since the distance between each of the first conductive layer (lead frame) and the light emitting device in each light emitting device module is appropriate, it may be possible to reduce the cost of materials used in wire boding and to secure convenience in the manufacturing process. 
       FIG. 14  is a view illustrating a display apparatus including the light emitting device module according to one of the above-described embodiments. 
     As shown in  FIG. 14 , the display apparatus according to the illustrated embodiment, which is designated by reference numeral  800 , includes a light source module, a reflective plate  820  provided on a bottom cover  810 , a light guide plate  840  disposed in front of the reflective plate  820  to guide light emitted from the light source module  830  to a front side of the display apparatus  800 , first and second prism sheets  850  and  860  disposed in front of the light guide plate  840 , a panel  870  disposed in front of the second prism sheet  860 , and a color filter  880  disposed in front of the panel  870 . 
     The light source module includes a circuit board  830  and light emitting device modules  835  mounted on the circuit board  830 . Here, a printed circuit board (PCB) may be used as the circuit board  830 . The light emitting device module  835  may have the above-described configuration. 
     The bottom cover  810  serves to receive the constituent elements of the display apparatus  800 . The reflective plate  820  may be provided as a separate element, as shown in  FIG. 14 , or may be provided as a material having high reflectivity is coated over a rear surface of the light guide plate  840  or a front surface of the bottom cover  810 . 
     Here, the reflective plate  820  may be made of material having high reflectivity and capable of being formed into an ultra thin structure. Polyethylene terephthalate (PET) may be used for the reflective plate  820 . 
     The light guide plate  840  serves to scatter light emitted from the light source module so as to uniformly distribute the light throughout all regions of a liquid crystal display apparatus. Therefore, the light guide plate  840  may be made of a material having high refractivity and transmissivity. The material of the light guide plate  840  may include polymethylmethacrylate (PMMA), polycarbonate (PC) or polyethylene (PE). 
     The first prism sheet  850  may be formed by coating with a polymer exhibiting light transmittance and elasticity over one surface of a base film. The first prism sheet  850  may have a prism layer having a plurality of three-dimensional structures in the form of a repeated pattern. Here, the pattern may be a stripe type in which ridges and valleys are repeated. 
     The second prism sheet  860  may have a similar structure to the first prism sheet  850 . The second prism sheet  860  may be configured such that the orientation direction of ridges and valleys formed on one surface of the base film of the second prism sheet  860  is perpendicular to the orientation direction of the ridges and valleys formed on one surface of the base film of the first prism sheet  850 . Such a configuration serves to uniformly distribute light transmitted from the light module and the reflective sheet  820  toward the entire surface of the panel  870 . 
     Although not shown, a protective sheet may be provided on each of the prism sheets  850  and  860 . The provision of the protective sheet may be achieved by forming a protective layer including light-diffusing particles and a binder at each surface of the base film in each of the prism sheets  850  and  860 . 
     The prism layer may be made of a polymer selected from the group consisting of polyurethane, styrene-butadiene copolymer, polyacrylate, polymethacrylate, polymethyl methacrylate, polyethyleneterephthalate elastomer, polyisoprene and polysilicon. 
     Although not shown, a diffusion sheet may be disposed between the light guide plate  840  and the first prism sheet  850 . The diffusion sheet is made of a polyester or polycarbonate-based material. The diffusion sheet may maximally increase a light projection angle through refraction and scattering of light incident from the display apparatus. 
     The diffusion sheet may include a support layer including a light diffusing agent, and first and second layers formed on a light emitting surface (in the direction of the first prism sheet) and a light incident surface (in the direction of the reflective sheet) The first and second layers do not include a light diffusing agent. 
     The support layer may include 0.1 to 10 parts by weight of a siloxane-based light diffusing agent having an average particle size of 1 to 10 μm and 1 to 10 parts by weight of an acryl-based light diffusing agent having an average particle size of 1 to 10 μm, based on 100 parts by weight of a resin including a mixture of a methacrylate-styrene copolymer and methacrylate methyl-styrene copolymer. 
     The first and second layers may include 0.01 to 1 part by weight of an ultraviolet absorbing agent and 0.001 to 10 parts by weight of an antistatic agent, based on 100 parts by weight of a methacrylate methyl-styrene copolymer resin. 
     The support layer of the diffusion sheet has a thickness of 100 to 10,000 μm. Each layer may have a thickness of 10 to 1,000 μm. 
     In the illustrated embodiment, the optical sheet may include a combination of the diffusion sheet, the first prism sheet  850  and the second prism sheet  860 . However, the optical sheet may include other combinations, for example, a microlens array, a combination of a diffusion sheet and a microlens array, and a combination of a prism sheet and a microlens array. 
     A liquid crystal display panel may be used as the panel  870 . Further, instead of the liquid crystal display panel  870 , other kinds of display devices requiring light sources may be provided. 
     The display panel  870  is configured such that a liquid crystal layer is located between glass substrates, and polarizing plates are mounted on both glass substrates so as to utilize polarizing properties of light. Here, the liquid crystal layer has properties between a liquid and a solid. That is, in the liquid crystal layer, liquid crystals which are organic molecules having fluidity like the liquid are regularly oriented, and the liquid crystal layer displays an image using change of such molecular orientation due to an external electric field. 
     The liquid crystal display panel used in the display apparatus is of an active matrix type, and uses transistors as switches to adjust voltage applied to each pixel. 
     The color filter  880  is provided on the front surface of the panel  870 , and transmits only an R, G or B light component of light projected from the panel  870  per pixel, thereby displaying an image. 
     The above-described lighting apparatus, which employs the above-described light emitting device modules according to one of the above-described embodiments, exhibits an improvement in brightness because it is possible to reduce the amount of light absorbed into the insulating layer of each light emitting device module after being emitted from the corresponding light emitting device. Also, since the distance between each of the first conductive layer (lead frame) and the light emitting device in each light emitting device module is appropriate, it may be possible to reduce the cost of materials used in wire boding and to secure convenience in the manufacturing process. 
     In the light emitting device module according to one of the embodiments of the present invention and the lighting system using the light emitting device, the insulating layer, which includes a polyimide film, is opened at the top of the cavity. Accordingly, the amount of light absorbed into the insulating layer after being emitted from the light emitting device is reduced, so that an enhancement in optical efficiency is achieved. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Technology Category: 5