Patent Publication Number: US-9429295-B2

Title: Lighting apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims the benefit of the Patent Korean Application No. 10-2012-0049195, filed in Korea on May 9, 2012, which is hereby incorporated by reference as if fully set forth herein. 
     BACKGROUND 
     1. Field 
     A lighting apparatus is disclosed herein. 
     2. Background 
     Lighting apparatuses are known. However, they suffer from various disadvantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: 
         FIG. 1  is a perspective view of a lighting apparatus according to an embodiment of the present disclosure; 
         FIG. 2  is an exploded perspective view of the lighting apparatus of  FIG. 1 ; 
         FIG. 3  is a sectional view of the lighting apparatus of  FIG. 1 ; and 
         FIG. 4  is a sectional view of a lighting apparatus according to one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A lighting apparatus is described herein with reference to the attached drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts, repetitive description of which will be omitted, and, for convenience of description, a size or a shape of a member may be shown exaggerated or not to scale, perfectly. 
     Moreover, though terms including ordinal numbers, such as first or second, can be used for describing various elements, the elements are not confined by the terms, but are used merely to distinguish one element from other elements. 
     Traditionally, various types of light sources have been used for lighting including discharge lamps, and fluorescent lamps. These light sources may be used for various applications such as domestic, landscape and industrial purposes. 
     Among the various types of light sources, resistive type light sources, such as the incandescent lamps, have problems of poor efficiency and substantial heat generation, the discharge lamps have problems of a high price and a high voltage, and the fluorescent lamps may be harmful to the environment due to its use of mercury. 
     In order to solve the drawbacks of the light sources, interest in a light emitting diode (LED) is increasing, which has advantages in efficiency, variety of colors, autonomy of design, and so on. The LED is a semiconductor device which emits light when a forward bias voltage is applied thereto. LED, may have a longer lifetime, lower power consumption, and electric, optical, and physical characteristics suitable for mass production. Hence, LED based light sources have replaced the incandescent lamps and the fluorescent lamps, in various applications. 
     However, the LED generates a large amount of heat during operation which may cause poor efficiency if the heat is not sufficiently dissipated away from the LED. In order to solve the problem, an LED based lighting apparatus may be provided with a heat sink. 
     However, the heat sink may increase the weight of the lighting apparatus as the heat sink is formed of metal, and may increase production costs. For example, increases in the size of the heat sink to improve performance may also increase the overall size of the lighting apparatus, as well as the amount of metal needed, hence increasing production costs. 
     Consequently, a heat sink structure is required, which can contribute to make the lighting apparatus slimmer and lighter, while providing effective dissipation of heat. Accordingly, an object of the present disclosure is to provide lighting apparatus which has improved heat dissipation while minimizing the amount of metal required for the heat sink. Another object of the present disclosure is to provide lighting apparatus which enables easy repair and replacement of components. 
       FIG. 1  is a perspective view of a lighting apparatus of one embodiment of the present disclosure,  FIG. 2  is an exploded perspective view of the lighting apparatus of  FIG. 1 , and  FIG. 3  is a sectional view of a lighting apparatus of  FIG. 1 . 
     The lighting apparatus  100  may include a heat sink  110 , a light emitting unit  120 , a housing  140 , an air flow generating unit  150 , an electronic module  160 , and a flow passage guide  170 . The light emitting unit  120  may include a substrate  121  and a plurality of LEDs  122  mounted on the substrate  121 . A heat sink  110  may have a first side  110   a  (mounting surface) on which the light emitting unit  120  may be mounted and a second side  110   b  (bottom surface) at an opposite position to the first side  110   a . The first side  110   a  may be an upper region of the heat sink  110  and the second side  110   b  may be a lower region of the heat sink  110 . A housing  140  may be mounted to the second side  110   b  to form a predetermined space (cavity). An electric module  160  may be arranged in the cavity. An air flow generating unit  150  (fan) may be arranged over the housing  140 , and a flow passage guide  170  may be arranged between the air flow generating unit  150  and the heat sink  110 . 
     In this instance, the heat sink  110  may have an air inlet  111  and an air outlet  112  provided adjacent to each other to pass through the first side  110   a  and the second side  110   b , respectively. The flow passage guide  170  may connect the air inlet  111  and an introduction portion  151  (inlet) of the air flow generating unit  150 , and the air outlet  112  and a discharge portion  152  (outlet) of the air flow generating unit  150 . 
     The light emitting unit  120 , the air outlet  112  and the air inlet  111  may be positioned at or about a center axis of the heat sink  110 . The air outlet  112  and air inlet  111  may be positioned to be concentric. The air inlet  111  and the air outlet  112  may have radial shapes, or rectangular shapes each having a predetermined curvature to surround the light emitting unit  120 , respectively. The light emitting unit  120 , the air outlet  112  and the air inlet  111  may be positioned at different heights relative to the heat sink  110 . 
     The lighting apparatus  100 , a first flow passage P 1  formed to connect the air inlet  111 , a space between the housing  140  and the electronic module  160 , and the inlet  151  of the fan  150 . A second flow passage P 2  may be formed to connect the outlet  152  of the fan  150 , a space between the second side  110   b  of the heat sink  110  and the fan  150 , and the air outlet  112 . A flow passage guide  170  may be arranged in the housing to partition the first flow passage P 1  and the second flow passage P 2 . The flow passage guide  170  may be referred to as a divider, partition or shroud. 
     Elements of the lighting apparatus  100  will be described, with reference to the attached drawings, in detail. 
     The light emitting unit  120  may include a substrate  121  and a plurality of LEDs  122  mounted on the substrate  121 . And, the light emitting unit  120  may have a surface provided with a reflective layer. The reflective layer may be a reflective film, a coating, or another appropriate reflective surface. The reflective film may have a plurality of holes for exposing the LEDs  122 , and it may enclose the entire surface of the light emitting unit  120  except the LEDs  122 . 
     The heat sink  110  has a function of dissipating heat from the light emitting unit  120  to an outside of the lighting apparatus  100 , and may be formed of a metal or resin having good heat conductivity. And, the heat sink  110  may have an outside circumferential surface provided with a plurality heat dissipation fins for increasing a surface area for heat dissipation. 
     The heat sink  110  may include the first side  110   a  with the light emitting unit  120  mounted thereon, and the second side  110   b  positioned opposite to the first side  110   a . The heat sink  110  may have the air inlet  111  and the air outlet  112  each formed to allow air to flow through the heat sink, e.g., between the first side  110   a  and the second side  110   b . The air inlet  111  and the air outlet  112  may be provided adjacent to each other. 
     The first side  110   a  (e.g., top side) of the heat sink  110  may be divided into a region having the light emitting unit  120  mounted therein and a region having the air inlet  111  and the air outlet  112  provided therein. The region having the light emitting unit  120  mounted therein may be a recess  113  formed on the first side  110   a  of the heat sink  110 . Moreover, the region having the air inlet  111  and the air outlet  112  provided therein may be sloped surfaces each having a predetermined slope angle. 
     Referring to  FIG. 2 , the heat sink  110  may include the recess  113  formed at the first side  110   a  to have the light emitting unit  120  provided thereon. The recess  113  may be defined by a side surface  115  (also referred to herein as a side  115  and side wall  115 ). A first side wall  116  (divider wall) may be positioned a prescribed distance from the side surface  115  of the recess  113 , and a second side wall  117  (outer wall) may be positioned spaced from the first side wall  116 . The first side wall  116  may be referred to as a partition as it partitions a space formed between the side wall  115  of the recess and the outer wall  117  of the heat sink  110 . 
     And, the heat sink  110  may include a connecting member  118  connecting the side  115  of the recess  113 , the first side wall  116  and the second side wall  117 . The connecting member  118  may extend in a radial direction of the heat sink  110  to connect the side of the recess  113 , the first side wall  116  and the second side wall  117 . The heat sink  110  may have one or more connecting members  118 . Each connecting member  118  may be positioned a prescribed distance from each other. The number and location of the connecting members  110  may be determined to maximize the size of the air passage or for aesthetic considerations. 
     The air inlet  111  and the air outlet  112  may span from the first side  110   a  to the second side  110   b  of the heat sink  110 . The air outlet  112  may be provided between the side  115  of the recess  113  and the first side wall  116 , and the air inlet  111  may be provided between the first side wall  116  and the second side wall  117 . 
     In detail, the air outlet  112  may be constructed of the side wall  115  of the recess  113 , the first side wall  116 , and the connecting member  118 . The air inlet  111  may be constructed of the first side wall  116 , the second side wall  117  and the connecting member  118 . That is, the light emitting unit  120  may be arranged at a center of the heat sink  110 , and the air outlet  112  and the air inlet  111  may be provided to surround the light emitting unit  120 . 
     As previously described, the light emitting unit  120 , the air outlet  112 , and the air inlet  111  may be positioned at or about a center axis of the heat sink  110  to be concentric relative to each other. For example, the air outlet  112  may be positioned around the light emitting unit  120  and the air inlet  111  may be positioned around the air outlet  112 . 
     And, the first side wall  116  may have a height greater than a height of the second side wall  117 , the side  115  (or side wall) of the recess  113  may have a height greater than a height of the first side wall  116 . The difference in height of the side walls  116  and  117  may make the height of the air inlet  111  and the air outlet  112  to be different. Such a structure may prevent interference between the air flowing into the heat sink and air flowing out of the heat sink even if the air inlet  11  and the air outlet  112  are positioned adjacent to each other. 
     The heat sink  110  may have a cylindrical shape. The recess  113  may be formed by the side wall  115  and a bottom surface  114 . The light emitting unit  120  may be mounted on the bottom surface  114  of the recess  113 , and a heat conductive pad  180  may be provided between the light emitting unit  120  and the bottom of the recess  113 . The heat conductive pad  180  may improve transfer of heat H from the light emitting unit  120  to the heat sink  110 . 
     The lens unit  130  (cover) may have a function of guiding a light from the light emitting unit  120  to an outside of the lighting apparatus  100 , and may include at least one condenser lens  132 . The lens unit  130  may be detachably mounted to the side  115  of the recess  113 . For this, the lens unit  130  may include hook portions  131  provided thereto, and the side  115  of the recess  113  may have notch portions to receive the hooks  131 . 
     The housing  140  may be mounted at the second side  110   b  (e.g., bottom side) of the heat sink  110 . A predetermined space may be formed between the second side  110   b  of the heat sink  110  and the housing  140 . The electronic module  160  may be arranged in the housing  140  for supplying power to the light emitting unit  120 . And, the air flow generating unit  150  may be arranged between the second side  110   b  of the heat sink  110  and the electronic module  160 , and the flow passage guide  170  may be arranged between the air flow generating unit  150  and the second side  110   b  of the heat sink  110 . 
     The air flow generating unit  150  may be a fan, and the air flow generating unit  150  may be arranged to have the inlet portion  151  facing the electronic module  160  and the discharge portion  152  facing to the second side  110   b  of the heat sink  100 . The fan may be a conventional fan or a bladeless fan or air mover. Moreover, the housing  140  may be mounted to the second side wall  117 , and the flow passage guide  170  may be mounted to the first side wall  116 . 
     Referring to  FIG. 3 , the lighting apparatus  100  having above structure may have a first flow passage P 1  and a second flow passage P 2  formed therein. The first flow passage P 1  may be formed to connect the air inlet  111 , a space between the housing  140  and the electronic module  160 , and the inlet portion  151  of the fan  150 . The second flow passage P 2  may be formed to connect the outlet portion  152  of the fan  150 , a space between the second side  110   b  of the heat sink  110  and the fan  150 , and the air outlet  112 . 
     In the meantime, the flow passage guide  170  may separate the first flow passage P 1  and the second flow passage P 2 . The flow passage guide  170  may be referred to herein as a divider, partition, or shroud. The flow passage guide  170  may have a ring shape. The flow passage guide  170  may extend from the heat sink  110  to the fan  150 . For example, the flow passage guide  170  may be in contact with the first side wall  116  of the heat sink  110 , and in contact with the fan  150  at the outlet portion  152 . 
     And, the flow passage guide  170  may have a prescribed shape in which the diameter of the flow passage guide  170  decreases from the heat sink  100  to the fan  150 . For example, the diameter of the flow passage guide  170  may be greatest where it makes contact with the heat sink  110 , and smallest where it makes contact with the fan  150 . The flow passage guide  170  may have a bowl shape, cone shape, or the like. 
     The flow passage guide  170  may prevent the air introduced through the air inlet  111  from flowing to a space between the outlet portion  152  of the fan  150  and the second side  110   b  of the heat sink  110 . And, the flow passage guide  170  also prevents the air flowing through a space among the outlet portion  152  of the fan  150 , the second side  110   b  of the heat sink  110 , and the air flow generating unit  150  from flowing toward the air inlet  111 . In other words, the flow passage guide  170  divides the cavity inside the lighting apparatus  100  to form a portion of the first air flow passage P 1  and the second air flow passage P 2 . 
     If the fan  150  is put into operation, external air may be introduced to an inside of the housing  140  through the air inlet  111  of the heat sink  110 . In this instance, owing to the flow passage guide  170 , the external air may flow to the inlet portion  151  of the fan  150  through a space between the housing  140  and the flow passage guide  170 , e.g., a space at the electronic module  160  side. 
     When the light emitting unit  120  is operational, heat generated by the light emitting unit  120  may be transferred to the heat sink  100 . The fan  150  may be operated to force air to flow into the cavity along the first air flow passage P 1 . The fan  150  may blow air towards the heat sink  100 , forcing the air to flow out of the cavity along the second air flow passage P 2 . As the air circulates through the first and second air flow passages P 1 , P 2  heat is absorbed to improve the thermal efficiency of the heat sink  100 . 
     In more detail, upon supply of power to the light emitting unit  120 , the light emitting unit  120  may generate heat. The heat H may be transferred by conduction along the bottom  114  and the side wall  115  of the recess  113  of the heat sink  110 , and the first side wall  116 . The external air introduced through the air inlet  111  may absorb the heat as the external air passes through the first air flow passage P 1  along the first side wall  116  and the second side wall  117 . The air then flows to the inlet portion  151  of the fan  150 . 
     Then, the air discharged through the outlet portion  152  of the fan  150  may flow through the second air flow passage P 2  (e.g., a space among the second side  110   b  of the heat sink  110 , the fan  150 , and the flow passage guide  170 ), and, discharged to an outside of the lighting apparatus  100  through the air outlet  112  of the heat sink  110 . In this instance, the air absorbs heat as it flows through the second flow passage P 2  from the surfaces of the heat sink  110 . 
     The housing  140  may have a plurality of openings  141  (flow holes) provided therein. When the fan  150  is in operation, the external air may be introduced to the inside of the housing  140  through the openings  141 . The air may pass through the electronic module  160 , and flow to the inlet portion  153  of the fan  150 . The openings  141  may have a round shape, a rectangular shape, or another appropriate shape. Moreover, the openings  141  may be positioned on the surface of the housing  140  in close proximity to the inlet of the fan. 
     Owing to the fan  150 , the heat can be dissipated from the light emitting unit  120  and the electronic module  160  more effectively. For example, in a case where the fan  150  is driven at a rated voltage of 3.3V in the lighting apparatus  100  having above described structure, a temperature of the substrate  121  may be 65.5° C. or less, and an air temperature at a surface of the heat sink  110  may be 26.8° C. or less. 
     As has been described, the lighting apparatus  100  may improve dissipation of heat from the light emitting unit and the electronic module. Moreover, because the heat sink  110  is formed separately from the housing  140 , component and manufacturing costs may be reduced. The lighting apparatus  100  may also enable easy repair and replacement of components. 
       FIG. 4  is a sectional view of a lighting apparatus according to one embodiment of the present disclosure. In contrast to the embodiment of  FIGS. 1 to 3  as previously described, in this embodiment, the positions of an air inlet  211  and an air outlet  212  may be exchanged with each other. 
     In detail, the light emitting unit  120 , the air inlet  211  and the air outlet  212  may be positioned from a center axis of the heat sink  110 . The air inlet  211  and air outlet  212  may be formed concentrically with respect to the center axis of the heat sink  110 . In this instance, the air flow generating unit  150  (fan) may have the introduction portion  153  (inlet) arranged to face the heat sink  110 , and discharge portion  154  (outlet) may face the housing  140  has the electronic module  160 . 
     In such a configuration, the flow passage guide  170  arranged in the housing to partition a first flow passage P 3  and a second flow passage P 4 . The first flow passage P 3  may be formed to connect the air inlet  211 , a space between the second side  110   b  of the heat sink  110  and the fan  150 , and the introduction portion  153  of the fan  150 . The second flow passage P 4  may be formed to connect the discharge portion  154  of the fan  150 , a space between the housing  140  and the electronic module  160 , and the air outlet  212 . 
     As previously described, the heat sink  110  may include a recess  113  formed at the first side  110   a  of the heat sink  110 . The light emitting unit  120  may be mounted in the recess  113 , the heat sink  110  may further include a first side wall  116  positioned a prescribed distance from the side wall  115  of the recess  113 , and a second side wall  117  positioned a prescribed distance from the first side wall  116 . The first side wall  115  may be referred to as a partition and the second side wall  117  may form the exterior surface of the heat sink  110 . 
     In this instance, an air inlet  211  may be provided between the side wall  115  of the recess  113  and the first side wall  116 , and an air outlet  212  provided between the first side wall  116  and the second side wall  117 . That is, with respect to the embodiment of  FIGS. 1 to 3 , the air inlet  211  and the air outlet  212  are exchanged, and positions of the inlet  153  and the outlet  154  of the fan  150  are exchanged. 
     And, as previously described, the housing  140  may be mounted to the second side wall  117  and the flow passage guide  170  may be mounted to the first side wall  116 . The first side wall  116  may have a height greater than the second side wall  117 , and the side wall  115  of the recess  113  may have a height greater than a height of the first side wall  116 . That is, the light emitting unit  120 , the air outlet  212 , and the air inlet  211  may respectively be provided at positions having predetermined height differences. Hence, even if the air outlet  212  and the air inlet  211  are positioned adjacent to each other, interference between airflow through air inlet and air outlet may be reduced. 
     And, the flow passage guide  170  may partition the first flow passage P 3  and the second flow passage P 4 . The flow passage guide  170  (divider) may have a ring shape. The flow passage guide  170  may make contact with the first side wall  116  of the heat sink  110 , and may make contact with the inlet  153  of the fan  150 . 
     A process of heat H dissipation from the light emitting unit  120  will be described in detail with reference to  FIG. 4 . The heat H may be transferred along the bottom  114  and the side wall  115  of the recess  113 , and the first side wall  116  by conduction. The ambient air introduced to the lighting apparatus  100  through the air inlet  211  may absorb the heat as it flows along the side wall  115  of the recess  113  and the first side wall  116  and into the inlet  153  of the fan  150 . 
     Then, the air, discharged through the outlet  154  of the fan  150 , may flow through a space between the electronic module  160  and the housing  140 , and may be discharged through the air outlet  212  of the heat sink  110  and out of the lighting apparatus. In such a process, the heat may be dissipated from the electronic module more efficiently. 
     In summary, ambient air drawn into the housing  140  may transfer heat from the light emitting unit  120  to the outside as it flows through a space among the second side  110   b  of the heat sink  110 , the fan  150 , and flow passage guide  170 . Moreover, the air flow may also dissipate the heat from the electronic module  160  to the outside of the lighting apparatus as it flows through a space between the housing  140  and the electronic module  160 . 
     A lighting apparatus as broadly described and embodied herein may improve dissipation of heat from a light emitting unit and an electronic module. The amount of metal used in the heat sink may be reduced, thereby reducing costs. The lighting apparatus may also enable easy repair and facilitate replacement of components. 
     Additional advantages, objects, and features of the disclosure 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 practice of the disclosure. The objectives and other advantages of the disclosure 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 these objects and other advantages and in accordance with the purpose of the disclosure, a lighting apparatus as embodied and broadly described herein may include a body having a cavity, a plurality of LEDs, a substrate provided in the cavity and having a first surface and a second surface opposite the first surface, the plurality of LEDs provided on the first surface, a fan provided below the substrate to face the second surface, and a divider having a ring shape positioned on the fan to form a first air passage along the body and a second air passage along the substrate, wherein the first air passage may be in communication with a first side of the fan and the second air passage may be in communication with a second side of the fan. The lighting apparatus may further include an electric module provided in the cavity below the fan. The first and second air passages may be positioned to circumferentially surround an edge of the substrate. The divider may be positioned to extend from an opening of the cavity to the fan. 
     A heat sink may be provided over the fan, wherein the substrate may be positioned on a surface of the heat sink, and the first and second air flow passages are positioned to surround an outer circumference of the heat sink. The heat sink includes a first wall provided around the substrate, a second wall provided around the first wall, a third wall provided around the second wall, the first and second wall forming a portion of the second air flow passage and the second and third walls forming a portion of the first air flow passage. 
     The first, second, and third walls of the heat sink may be positioned concentric to a center axis of the body. The first, second, and third walls of the heat sink may be positioned concentric to a center axis of the body. A height of the first, second, and third walls of the heat sink may be different. Moreover, the first side wall may have a height higher than a height of the second side wall, and the side of the recess may have a height higher than the height of the first side wall. 
     The third wall of the heat sink may be mounted to an upper surface of the body and the divider may be connected to the heat sink to extend from the second wall of the heat sink to the fan. A width of the divider may decrease from the heat sink to the fan. A width of the divider may be greatest at the distal end connected to the heat sink and smallest at the distal end connected to the fan. 
     The heat sink and the body may be integrally formed. The lighting apparatus may further include a lens detachably mounted to the first wall of the heat sink. Moreover, the body includes a plurality of openings formed on a side surface of the body. 
     The fan may be configured to generate air flow from the first air passage to the second air passage to blow air towards the heat sink. The fan may be configured to generate air flow from the second air passage to the first air passage to blow air away from the heat sink. The lighting apparatus may further include an electric module provided below the fan, wherein the fan blows air toward the electric module. 
     In one embodiment, a lighting apparatus including a body, a heat sink provided over the body, a light emitting module mounted on the heat sink, and a fan provided below the heat sink in the body, wherein the heat sink includes a first surface provided around the light emitting module, a second surface provided around a circumference of the first surface and positioned a prescribed distance from the first surface, and a third surface provided around a circumference the second surface and positioned a prescribed distance from the second surface, wherein the fan circulates the air in the body from a first channel formed between the first and second surfaces to a second channel formed between the second and third surfaces. 
     In one embodiment, a lighting apparatus may include a light emitting unit having a substrate and a plurality of LEDs mounted on the substrate, a heat sink having a first side with the light emitting unit mounted thereon and a second side at an opposite position to the first side, a housing mounted to the second side to form a predetermined space, an air flow generating unit arranged in the housing, and a flow passage guide arranged between the air flow generating unit and the heat sink. 
     In this instance, the heat sink may have an air inlet and an air outlet provided adjacent to each other each to pass through the first side and the second side, the flow passage guide may connect the air inlet and the introduction portion, and the air outlet and the discharge portion of the air flow generating unit. The light emitting unit, the air outlet, and the air inlet may be positioned, in that order, in above order in a direction moving away from a center axis of the heat sink. The air outlet and the air inlet may have radial shapes to surround the light emitting unit, respectively. And, the light emitting unit, the air outlet, and the air inlet may be provided at positions having predetermined height differences in a length direction of the heat sink, respectively. 
     The air flow generating unit may have the discharge portion arranged to face the second side of the heat sink, and the housing may have an electronic module arranged on an introduction portion side of the air flow generating unit. The flow passage guide may be arranged in the housing to partition a first flow passage and a second flow passage, wherein the first flow passage is formed to connect the air inlet, a space between the housing and the electronic module, and the introduction portion of the air flow generating unit, and the second flow passage is formed to connect the discharge portion of the air flow generating unit, a space between the second side of the heat sink and the air flow generating unit, and the air outlet. 
     The heat sink may include a recess formed in the first side to have the light emitting unit arranged thereon, a first side wall positioned spaced from the side of the recess, and a second side wall positioned spaced from the first side wall. In this instance, the air outlet may be provided between the side of the recess and the first side wall, and the air inlet may be provided between the first side wall and the second side wall. 
     The housing may be mounted to the second side wall, and the flow passage guide may be mounted to the first side wall. The flow passage guide may have a cross section, an area of which becomes smaller as the flow passage guide goes from the first side wall toward the air flow generating unit. The flow passage guide may have a region with a largest diameter in contact with the first side of the heat sink, and a region with a smallest diameter in contact with the air flow generating unit. Moreover, the first side wall may have a height higher than a height of the second side wall, and the side of the recess may have a height higher than the height of the first side wall. The lighting apparatus may further include a lens unit detachably mounted to the side of the recess. The housing may have a plurality of flow holes provided therein. 
     In one embodiment, the light emitting unit, the air inlet, and the air outlet may be provided to position in above order in a direction moving away from a center axis of the heat sink. The air flow generating unit may have the introduction portion arranged to face the second side of the heat sink, and the housing has the electronic module arranged on a discharge portion side of the air flow generating unit. 
     The flow passage guide may be arranged in the housing to partition a first flow passage and a second flow passage, wherein the first flow passage is formed to connect the air inlet, a space between the second side of the heat sink and the air flow generating unit, and the introduction portion of the air flow generating unit, and the second flow passage is formed to connect the discharge portion of the air flow generating unit, a space between the housing and the electronic module, and air outlet. 
     The heat sink may include a recess formed in the first side to have the light emitting unit arranged thereon, a first side wall positioned spaced from the side of the recess, and a second side wall positioned spaced from the first side wall. In this instance, the air inlet may be provided between the side of the recess and the first side wall, and the air outlet may be provided between the first side wall and the second side wall. 
     The housing is mounted to the second side wall, and the flow passage guide may be mounted to the first side wall. The first side wall may be formed to have a height higher than a height of the second side wall, and the side of the recess may have a height higher than the height of the first side wall. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.