Patent Publication Number: US-2013250589-A1

Title: Luminaire and method of thermal radiation of the luminaire

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-066217, filed on Mar. 22, 2012; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relates generally to a luminaire and a method of thermal radiation of the luminaire. 
     BACKGROUND 
     As a method of thermal radiation of electronic components mounted on a circuit board in luminaires having light-emitting elements such as LEDs (Light Emitting Diodes) as light sources, for example, LED light bulbs or LED units, there is a method of covering the electronic components directly with a thermally-conductive medium. However, with the method of covering the electronic components with the thermally-conductive medium, a thermal radiation effect of the electronic components is low, and hence effective thermal radiation cannot be expected. 
     As a method of radiating heat from the electronic components mounted on the circuit board, there is a method of embedding the electronic components mounted on the circuit board into the thermally-conductive medium on the side of a mount surface of the circuit board where the electronic components are mounted. However, with the method of embedding the electronic components mounted on the circuit board into the thermally-conductive medium on the side of the mount surface of the circuit board where the electronic components are mounted, nothing more than radiating the heat generated by the electronic components on the side of the mount surface is performed. In addition, in this method, the amount of usage of the thermally-conductive medium is increased, and hence increase in cost results. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic cross-sectional view of an entire luminaire according to a first embodiment; 
         FIG. 1B  is an enlarged schematic cross-sectional view of a portion around a thermally-conductive medium of the luminaire according to the first embodiment; 
         FIG. 2A  is a schematic plan view of a circuit board according to the first embodiment; 
         FIG. 2B  is a perspective schematic drawing of the circuit board according to the first embodiment; 
         FIG. 3  is a schematic cross-sectional view for explaining an operation of the luminaire according to the first embodiment; 
         FIG. 4  is a schematic cross-sectional view of the luminaire according to a second embodiment; 
         FIG. 5  is a schematic cross-sectional view of the luminaire according to a first example of a third embodiment; 
         FIG. 6  is a schematic cross-sectional view of the luminaire according to a second example of the third embodiment; 
         FIG. 7  is a schematic cross-sectional view of the luminaire according to a fourth embodiment; 
         FIG. 8  is a schematic cross-sectional view of the luminaire according to a fifth embodiment; 
         FIG. 9  is a schematic cross-sectional view of the luminaire according to a sixth embodiment; 
         FIG. 10  is a schematic cross-sectional view of the luminaire according to a seventh embodiment; and 
         FIG. 11  is a schematic partial cross-sectional view of the luminaire according to an eighth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a luminaire includes: a light-emitting portion having a light-emitting element; a circuit board having a notch or a through hole; an electronic component mounted on a side of a second main surface opposite to a first main surface of the circuit board; a thermal radiator provided on a side of the first main surface and including the light-emitting portion disposed on the thermal radiator; a thermally-conductive medium disposed on the side of the first main surface of the circuit board and being in contact with the electronic component through the notch or the through hole, and capable of transferring heat generated by the electronic component to the side of the first main surface of the circuit board; and an outer frame member accommodating the light-emitting portion, the circuit board, the electronic component, and the thermally-conductive medium. 
     Referring now to the drawings, embodiments will be described. In the following description, the same members are designated by the same reference numerals, and description of the members described once will be omitted as needed. 
     First Embodiment 
       FIG. 1A  is a schematic cross-sectional view of an entire luminaire according to a first embodiment, and  FIG. 1B  is an enlarged schematic cross-sectional view of a portion around a thermally-conductive medium of the luminaire according to the first embodiment. 
     A luminaire  1  according to the first embodiment is a luminaire having a standardized cap such as GX53 or GH76p. 
     The luminaire  1  includes a light-emitting portion  20 , a circuit board  30  having a notch  31  or a through hole  32 , an electronic component  40  mounted on a side of a second main surface  30   b  opposite to a first main surface  30   a  of the circuit board  30 , a thermal radiator  10  provided on a side of the first main surface  30   a  and including the light-emitting portion  20  disposed on the thermal radiator  10 , a thermally-conductive medium  50  provided in the notch  31  or the through hole  32  from the side of the first main surface  30   a  of the circuit board  30  and coming into contact with the electronic component  40 , and an outer frame member  60  configured to accommodate the light-emitting portion  20 , the circuit board  30 , the electronic component  40 , and the thermally-conductive medium  50 . Heat generated by the electronic component  40  is allowed to be transferred to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50 . 
     The configuration of the luminaire  1  will be described further in detail. The luminaire  1  includes the thermal radiator  10  formed of a metal (for example, aluminum (Al)), the light-emitting portion  20  mounted on the thermal radiator  10 , and the circuit board  30  above the thermal radiator  10  at a predetermined distance from the thermal radiator  10  and the light-emitting portion  20 , that is, on a side of a light-emitting of the light-emitting portion  20 . The light-emitting portion  20  includes light-emitting elements. The light-emitting portion  20  includes a plurality of light-emitting elements such as LEDs (Light Emitting Diodes) which are arranged. The circuit board  30  includes the notch  31  or the through hole  32  at a mount position (for example, immediately below) of the electronic component  40 . 
     The luminaire according to the first embodiment is not limited to those employing the LEDs as the light-emitting elements. For example, luminaires employing light-emitting elements such as EL (Electro-Luminescence) or organic light-emitting diodes (OLEDs) as the light-emitting elements instead of the LEDs are also included in the scope of the first embodiment. 
     The luminaire  1  also includes the electronic component  40 . Assuming that the main surface of the circuit board  30  opposing the thermal radiator  10  is first main surface  30   a  and the main surface of the circuit board  30  opposite to the first main surface  30   a  is a second main surface  30   b , the electronic component  40  is mounted on the second main surface  30   b . Circuit patterns  35 , formed of a metal (for example, copper (Cu)), are formed on the first main surface  30   a  and the second main surface  30   b  of the circuit board  30 . Examples of the electronic component  40  include a coil, a transformer, a diode, a transistor, a resistance, or a capacitor. In  FIG. 1A , only one of the electronic components  40  is illustrated. However, the number of the electronic components  40  is not limited to one. 
     The luminaire  1  further includes the thermally-conductive medium  50 . The thermally-conductive medium  50  is provided on the side of the first main surface  30   a  of the circuit board  30 , and is in contact with the electronic component  40  via the notch  31  or the through hole  32 . The thermally-conductive medium  50  preferably has insulation properties. The thermally-conductive medium  50  is formed of a material having a coefficient of thermal conductivity higher than air. Examples of the materials of the thermally-conductive medium  50  include organic materials and inorganic materials. When resins are used as the material of the thermally-conductive medium  50 , for example, resins such as silicone resin, polyimide resin, and epoxy resin may be employed. 
     The luminaire  1  further includes the outer frame member (housing)  60  formed of a resin. The outer frame member  60  is in contact with the thermally-conductive medium  50 . The outer frame member  60  is configured to accommodate the light-emitting portion  20 , the circuit board  30 , the electronic component  40 , and the thermally-conductive medium  50 . The outer frame member  60  includes a bottom surface portion  60   b  and a side surface portion  60   w . The bottom surface portion  60   b  is interposed between the thermal radiator  10  and the circuit board  30 , and the bottom surface portion  60   b  is in contact with the thermal radiator  10 . That is, part of the thermal radiator  10  is in contact with the outside of the outer frame member  60 . 
     In other words, the thermal radiator  10  constitutes part of an outer shell of the luminaire  1 . The thermal radiator  10  may further constitute part of the outer frame member  60 . That is, the thermal radiator  10  is formed so as to cover an opening portion  60   h  which is provided so as to communicate the interior and the exterior of the outer frame member  60 . In the first embodiment, the thermal radiator  10  is mounted on the bottom surface portion  60   b  so as to close the opening portion  60   h  provided at a center of the bottom surface portion  60   b , so that the thermal radiator  10  constitutes part of the outer frame member  60 . 
     In addition, the luminaire  1  includes a reflector  70 , a translucent shielding member  80 , and an electrode pin  11 . With the provision of the reflector  70 , the electronic components  40  are arranged in a space  95  surrounded by the circuit board  30 , the outer frame member  60 , and the reflector  70 . The translucent shielding member  80  is provided so as to cover the reflector  70  and the light-emitting portion  20 . The translucent shielding member  80  allows passage of light emitted from the light-emitting portion  20  and simultaneously protects the light-emitting portion  20 . The electrode pin  11  functions as an electrode for supplying electric power to the electronic component  40 , or an electrode for supplying a light-modulating signal, or a grounding electrode. The electrode pin  11  and the thermal radiator  10  may be collectively referred to as a cap  12 . 
     When the luminaire  1  is viewed in the direction perpendicular to the main surfaces (the first main surface  30   a  or the second main surface  30   b ) of the circuit board  30 , the outline of the light-emitting portion  20  has a rectangular shape, and the outline of the thermal radiator  10  and the outline of the circuit board  30  have approximately a circular shape. The outer diameter of the light-emitting portion  20  is smaller than the outer diameter of the thermal radiator  10  and the outer diameter of the circuit board  30 . The outer diameter of the thermal radiator  10  is smaller than the diameter of the circuit board  30 . 
     In  FIG. 1 , a state in which the translucent shielding member  80  side is located on the upper side, and the thermal radiator  10  side is located on the lower side is illustrated. However, the position in which the translucent shielding member  80  side is located on the lower side, and the thermal radiator  10  side is located on the upper side is also applicable. 
       FIG. 2A  is a schematic plan view of the circuit board according to the first embodiment, and  FIG. 2B  is a perspective schematic drawing of the circuit board according to the first embodiment. 
     Illustrated in  FIG. 2A  is the side of the second main surface  30   b  of the circuit board  30 , and illustrated in  FIG. 2B  is the side of the first main surface  30   a  of the circuit board  30 . 
     The outline of the circuit board  30  has a circular shape and includes a hollow portion  30   h  at a center of the circuit board  30 . In other words, the circuit board  30  has an annular shape. A plurality of electronic components  40  (the electronic components  40   a  and  40   b ) are provided on the second main surface  30   b  of the circuit board  30 . Here, assuming that the side of the second main surface  30   b  is an upper side and the side of the first main surface  30   a  is a lower side, the notch  31  is provided under the electronic component  40   a  in the circuit board  30 , and the through hole  32  is provided under the electronic component  40   b  in the circuit board  30 . When the circuit board  30  is integrated in the luminaire, the light-emitting portion  20  is located under the hollow portion  30   h  of the circuit board  30 . 
     In the luminaire  1 , when the light-emitting portion  20  is caused to emit light, the light emitted from the light-emitting portion  20  reaches the translucent shielding member  80  or the reflector  70 . The light directly reaching the translucent shielding member  80  is radiated from the translucent shielding member  80  to the outside of the luminaire  1 . The light reaching the reflector  70  is also reflected by the reflector  70 , reaches the translucent shielding member  80  in time, and is radiated from the translucent shielding member  80  to the outside of the luminaire  1 . 
     Here, the annular circuit board  30  is arranged on the outside of the light-emitting portion  20  and is arranged in a space surrounded by the bottom surface portion  60   b  and the side surface portion  60   w  of the outer frame member  60  and the reflector  70 . Since the more the light-emitting portion  20  comes close to the thermal radiator  10 , the more thermal radiating efficiency of the light-emitting portion  20  increases, the light-emitting portion  20  in the first embodiment is disposed on the thermal radiator  10 , which is arranged on the lowermost side to the light-emitting portion  20 . The circuit board  30  is arranged on a side of the bottom surface portion  60   b  in order to secure flexibility of optical design of the reflector  70 , and the electronic components  40  are mounted on the side of the second main surface  30   b , that is, on the side where light goes out. In other words, the electronic components  40  are mounted on the surface of the circuit board  30  toward the opposite side to the direction of thermal radiation from the light-emitting portion  20  to the thermal radiator  10 . In the first embodiment, in this manner, a thermal radiation route from the electronic component  40  toward the thermal radiator  10  can be formed, concerning the luminaire that the electronic components  40  is mounted on the surface of the circuit board  30  toward the opposite side to the direction of a thermal radiation route of the light-emitting portion  20 . 
       FIG. 3  is a schematic cross-sectional view for explaining an operation of the luminaire according to the first embodiment. 
       FIG. 3  illustrates a state in which the thermally-conductive medium  50  is in contact with the outer frame member  60 , and the first main surface  30   a  of the circuit board  30 . 
     In order to cause the light-emitting portion  20  to emit light, driving of the electronic components  40  is necessary. When the electronic components  40  are driven, the electronic components  40  may generate heat. In order to elongate the lifetime of the luminaire or to avoid deterioration of characteristics, the heat generated by the electronic components  40  is preferably radiated to the outside of the luminaire  1  as much as possible. 
     In the luminaire  1 , the heat generated by the electronic components  40  is radiated from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  disposed in the notch  31  or the through hole  32  in contact with the electronic components  40 . 
     For example, in a route A in  FIG. 3 , the heat generated by the electronic components  40  is transferred from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  in contact with the electronic components  40  via the notch  31  or the through hole  32 . Subsequently, the heat is transferred to a portion, which is the thermal radiator portion in contact with the outside of the outer frame member  60 , via the thermally-conductive medium  50 , and is radiated to the portion of the thermal radiator  10  in contact with the outside of the outer frame member  60  (arrow A 1 ), and is also transferred to the outer frame member  60  and is radiated to the outer frame member  60  (arrow A 2 ). 
     In a route B, the heat generated by the electronic components  40  is transferred from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  disposed in the notch  31  or the through hole  32  in contact with the electronic components  40 . Subsequently, the heat is transferred to the outer frame member  60  via the thermally-conductive medium  50 , and is radiated to the outer frame member  60 . 
     In this manner, the heat generated by the electronic components  40  is radiated to the thermal radiator  10  or the outer frame member  60  efficiently via the thermally-conductive medium  50 . 
     Furthermore, the circuit patterns  35  are provided also on the side of the first main surface  30   a  of the circuit board  30 . If the thermally-conductive medium  50  and the circuit pattern  35  are in contact to each other, the heat is transferred along a route C in the drawing. 
     In the route C, the heat generated by the electronic components  40  is transferred from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  disposed in the notch  31  or the through hole  32 . In other words, the heat generated by the electronic components  40  is radiated to the circuit pattern  35  on the side of the first main surface  30   a  via the thermally-conductive medium  50 . 
     In this manner, the heat generated by the electronic components  40  is efficiently dispersed along the route A, the route B, and the route C. Consequently, the thermal radiating effect of the electronic components  40  is enhanced. 
     Also, the luminaire  1  does not require covering of the entire surfaces of the electronic components  40  on the side of the second main surface  30   b  of the circuit board  30  with the thermally-conductive medium  50 , or does not require embedding the electronic components  40  into the thermally-conductive medium  50 . Therefore, the amount of usage of the thermally-conductive medium  50  is significantly reduced, so that weight reduction and cost reduction of the luminaire are achieved. 
     In addition, with the enhancement of the thermal radiating effect of the electronic components  40 , so called heat accumulation can hardly occur within the space  95  surrounded by the circuit board  30 , the outer frame member  60 , and the reflector  70 . Accordingly, probability of occurrence of deterioration or deformation of the circuit board  30 , the outer frame member  60 , and the reflector  70  is reduced. Furthermore, with the enhancement of the thermal radiating effect of the electronic components  40 , the lifetime of the electronic components  40  is elongated. 
     Since efficient radiation of the heat from the electronic components  40  is achieved, increase in temperature of the light-emitting portion  20  is inhibited. Consequently, lowering of a light-emitting efficiency of the light-emitting portion  20  is inhibited and light-emission with a high efficiency and elongation of the lifetime of the light-emitting portion  20  are also achieved. 
     Furthermore, with the enhancement of the light-emitting efficiency of the light-emitting portion  20 , reduction in the number of the light-emitting elements such as the LEDs to be mounted on the light-emitting portion  20  is achieved. Consequently, reduction in power consumption and reduction in cost are achieved. 
     In the first embodiment, a method of thermal radiation of the luminaire  1  is also provided in addition to the luminaire  1 . 
     The method of thermal radiation of the luminaire is a method of radiating the heat generated by the electronic components  40  from the second main surface  30   b  to the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  disposed in the notch  31  or the through hole  32  in contact with the electronic components  40 . 
     In the method of thermal radiation of the luminaire, the notch  31  or the through hole  32  is provided at the mount position of the electronic components  40  in the circuit board  30 . 
     In the method of thermal radiation of the luminaire, the notch  31  or the through hole  32  is formed under the electronic components  40  in the circuit board  30 . 
     In the method of thermal radiation of the luminaire, at least parts of the electronic components  40  may be inserted into the notch  31  or the through hole  32  of the circuit board  30 . 
     In the method of thermal radiation of the luminaire, the outer frame member  60 , which is configured to accommodate the light-emitting portion  20 , the circuit board  30 , the electronic components  40 , and the thermally-conductive medium  50 , is further provided, the thermally-conductive medium  50  and the outer frame member  60  are brought into contact with each other. As a result, the heat generated by the electronic components  40  is radiated to the outer frame member  60  and the thermal radiator  10  via the thermally-conductive medium  50 . 
     In the method of thermal radiation of the luminaire, the heat generated by the electronic components  40  may be radiated to the portion of the thermal radiator from the outer frame member  60  via the thermally-conductive medium  50  by further using the thermal radiator  10  having the portion which is in contact with the outside of the outer frame member  60 . 
     In the method of thermal radiation of the luminaire, the thermal radiator  10  may be fixed to the outer frame member  60  by a fixing member  90  (described later). In this case, the thermally-conductive medium  50  is brought into contact with the fixing member  90 , and the heat generated by the electronic components  40  is radiated to the thermal radiator  10  via the thermally-conductive medium  50  and the fixing member  90 . Also, at this time, a thermal radiation route from the fixing member  90  to the outer frame member  60  may be formed. 
     In the method of thermal radiation of the luminaire, the circuit pattern is provided on the first main surface  30   a  of the circuit board  30 , the thermally-conductive medium  50  is brought into contact with the circuit pattern, and the heat generated by the electronic components  40  is transferred to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  and the circuit pattern. 
     In the method of thermal radiation of the luminaire, a configuration in which part of the thermal radiator  10  is inserted into the outer frame member  60  so as to penetrate through the outer frame member  60 , and part of the thermal radiator  10  exposed inside of the outer frame member  60  is brought into contact with the thermally-conductive medium  50  is also applicable. 
     Second Embodiment 
       FIG. 4  is a schematic cross-sectional view of the luminaire according to a second embodiment. 
     In a luminaire  2  according to the second embodiment, the thermal radiator  10  is fixed to the outer frame member  60  via the fixing member  90 , and the thermally-conductive medium  50  is in contact with the fixing member  90 , the outer frame member  60 , and the first main surface  30   a  of the circuit board  30 . Examples of the fixing member  90  include a metallic screw, for example. 
     In the luminaire  2  as well, the heat generated by the electronic components  40  is radiated from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  disposed in the notch  31  or the through hole  32  in contact with the electronic components  40 . 
     For example, in a route A in  FIG. 4 , the heat generated by the electronic components  40  is transferred from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  disposed in the notch  31  or the through hole  32  in contact with the electronic components  40 . Subsequently, the heat is discharged to the thermal radiator  10  (arrow A 1 ) and in addition is radiated to the outer frame member  60  (arrow A 2 ) via the thermally-conductive medium  50  and the fixing member  90 . 
     In a route B, the heat generated by the electronic components  40  is transferred from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  in contact with the electronic components  40  via the notch  31  or the through hole  32 . Subsequently, the heat is radiated to the outer frame member  60  via the thermally-conductive medium  50 . 
     In this manner, the heat generated by the electronic components  40  is radiated to the thermal radiator  10  and the outer frame member  60  efficiently via the thermally-conductive medium  50  and the fixing member  90 . 
     Circuit patterns  35  are provided also on the side of the first main surface  30   a  of the circuit board  30 . If the thermally-conductive medium  50  and the circuit pattern  35  are in contact to each other, the heat is transferred along a route C in the drawing. 
     In the route C, the heat generated by the electronic components  40  is transferred from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  filled in the notch  31  or the through hole  32 . In other words, the heat generated by the electronic components  40  is radiated to the circuit pattern  35  on the side of the first main surface  30   a  via the thermally-conductive medium  50 . 
     The heat generated by the electronic components  40  is efficiently dispersed along the route A, the route B, and the route C. In the luminaire  2 , since the fixing member  90  is provided, the thermal conducting efficiency is further enhanced. Consequently, the thermal radiating effect of the electronic components  40  is further enhanced. 
     First Example of Third Embodiment 
       FIG. 5  is a schematic cross-sectional view of the luminaire according to a first example of a third embodiment. 
       FIG. 5  illustrates a state in which a portion near the thermally-conductive medium  50  of a luminaire  3 A is enlarged. 
     In the luminaire  3 A according to the third embodiment, part of the thermal radiator  10  exposed inside of the outer frame member  60  is in contact with the thermally-conductive medium  50 . In  FIG. 5 , part of the thermal radiator  10  penetrates through the outer frame member  60 , and the penetrated part of the thermal radiator  10  is illustrated as a projecting portion  10   ta . The material of the projecting portion  10   ta  is, for example, aluminum. 
     In the luminaire  3 A, since the projecting portion  10   ta  is in direct contact with the thermally-conductive medium  50 , the heat generated by the electronic components  40  is transferred directly to the thermal radiator  10  via the thermally-conductive medium  50 . Therefore, the thermal radiating effect of the electronic components  40  is further enhanced. Since the part of the thermal radiator  10  penetrates through the outer frame member  60  and gets closer to the circuit board  30 , the amount of usage of the thermally-conductive medium  50  is further reduced correspondingly. Consequently, the manufacture of the luminaire at low cost is achieved. 
     Second Example of Third Embodiment 
       FIG. 6  is a schematic cross-sectional view of the luminaire according to a second example of the third embodiment. 
     In a luminaire  3 B illustrated in  FIG. 6 , the projecting portion  10   ta  which is the projecting part of the thermal radiator  10  is provided. However, the projecting portion  10   ta  does not penetrate through the outer frame member  60 . 
     By the projecting portion  10   ta  formed in this manner, the amount of usage of thermally-conductive medium may be reduced in comparison with the case where the thermal radiator  10  having a flat shape is thermally connected to the electronic components  40  via the thermally-conductive medium  50 . The outer frame member  60  may be positioned with respect to the projecting portion  10   ta . Here, the notch  31  or the through hole  32  is arranged so as to oppose the thermal radiator  10  on the inside of an outer periphery of the thermal radiator  10  and the projecting portion  10   ta  is arranged so as to oppose the notch  31  or the through hole  32 . In other words, the notch  31  or the through hole  32  is provided immediately below the electronic components  40 , and the projecting portion  10   ta  is provided immediately below the notch  31  or the through hole  32 . Accordingly, the amount of usage of the thermally-conductive medium  50  is reduced. 
     Fourth Embodiment 
       FIG. 7  is a schematic cross-sectional view of the luminaire according to a fourth embodiment. 
     In a luminaire  4  according to the fourth embodiment, at least part of the thermal radiator  10  is provided on the inside of the outer frame member  60 . Then, the thermally-conductive medium  50  is in contact with the thermal radiator  10  in the interior of the outer frame member  60 . 
     The heat generated by the electronic components  40  is transferred to the thermal radiator  10  via the thermally-conductive medium  50  in contact with the electronic components  40  via the interior of the notch  31  or the through hole  32 . In this manner, the thermal radiation from the electronic components  40  may be accelerated. 
     As shown in  FIG. 7 , if part  10 A of the thermal radiator  10  is exposed to the outside of the outer frame member  60 , the thermal radiating efficiency is further enhanced. However, the fourth embodiment is not limited to the configuration in which part of the thermal radiator is exposed to the outside as described above, and a configuration in which the entire part of the thermal radiator  10  is provided in the interior of the outer frame member  60  is also applicable. 
     According to the fourth embodiment, for example, if the thermal radiator  10  is formed of a metal such as aluminum and the outer frame member  60  is formed of a resin, the heat transferred from the electronic components  40  via the thermally-conductive medium  50  may be transferred to the thermal radiator  10  having a coefficient of thermal conductivity higher than the coefficient of thermal conductivity of the resin, so that the efficient thermal radiation is achieved. 
     Fifth Embodiment 
       FIG. 8  is a schematic cross-sectional view of the luminaire according to a fifth embodiment. 
     In a luminaire  5  according to the fifth embodiment, part of the thermal radiator  10  extending from the thermal radiator  10  is inserted into the notch  31  or the through hole  32 , and the corresponding part of the thermal radiator and the electronic components  40  are in contact with each other.  FIG. 8  illustrates the extending part of the thermal radiator  10  as a projecting portion  10   tb . The material of the projecting portion  10   tb  is, for example, aluminum. 
     In the luminaire  5 , the heat generated by the electronic components  40  is transferred from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the part (projecting portion  10   tb ) of the thermal radiator inserted into the notch  31  or the through hole  32 . In the luminaire  4 , since the projecting portion  10   tb  is in direct contact with the electronic components  40 , the heat generated by the electronic components  40  is directly radiated to the thermal radiator  10  via the projecting portion  10   tb  of the thermal radiator  10 . Therefore, the thermal radiating effect of the electronic components  40  is further enhanced. Also, since the thermally-conductive medium  50  is not used, the manufacture of the luminaire is achieved at low cost correspondingly. 
     Sixth Embodiment 
       FIG. 9  is a schematic cross-sectional view of the luminaire according to a sixth embodiment. 
     In a luminaire  6  according to the sixth embodiment, the part of the thermal radiator  10  extending from the thermal radiator  10  is inserted into the notch  31  or the through hole  32  in the same manner as the fifth embodiment. 
     In the sixth embodiment, the thermally-conductive medium  50  is interposed between the thermal radiator  10  and the electronic components  40 . In this configuration, thermal contact between the thermal radiator  10  and the electronic components  40  is improved, and hence transfer of the heat to the thermal radiator  10  is accelerated. 
     In the sixth embodiment, even when the thickness of the thermally-conductive medium  50  is decreased, the thermal contact between the thermal radiator  10  and the electronic components  40  may be maintained desirably. In other words, the desirable thermal radiation is realized while using a small amount of the thermally-conductive medium  50 . 
     Seventh Embodiment 
       FIG. 10  is a schematic cross-sectional view of the luminaire according to a seventh embodiment. 
     In a luminaire  7  according to the seventh embodiment, at least part of the electronic components  40  (the electronic component  40   b ) is inserted into the notch  31  or the through hole  32  of the circuit board  30 . 
     In the luminaire  7 , since at least the part of the electronic component  40   b  is inserted into the notch  31  or in the through hole  32 , the electronic component  40   b  gets closer to the thermal radiator  10  correspondingly. Therefore, the thermal radiating effect of the electronic components  40  is further enhanced. 
     In  FIG. 10 , a state in which the electronic component  40   b  is embedded into the thermally-conductive medium  50  is illustrated. However, a configuration in which the electronic component  40   b  is not embedded into the thermally-conductive medium  50  and an upper surface of the thermally-conductive medium  50  is brought into contact with a lower surface  41  of the electronic component  40   b  is also applicable. 
     Eighth Embodiment 
       FIG. 11  is a schematic partial cross-sectional view of the luminaire according to an eighth embodiment. 
     A luminaire  8  according to the eighth embodiment is a luminaire having a bulb shape. 
     The luminaire  8  includes the light-emitting portion  20 , the thermal radiator  15  configured to radiate heat generated by the light-emitting portion  20  to the outside, and the circuit board  30 . The material of the thermal radiator  15  is, for example, aluminum (Al). The thermal radiator  15  also functions as an outer frame member of the luminaire. The circuit board  30  includes the notch  31  or the through hole  32 . The circuit board  30  is provided above the thermal radiator  15  at a predetermined distance from the thermal radiator  15  and the light-emitting portion  20 , that is, on the side of the light-emitting of the light-emitting portion  20 . 
     The luminaire  8  also includes the electronic components  40 . The electronic components  40  is mounted on the side of the second main surface  30   b  of the circuit board  30  opposite to the first main surface  30   a  of the circuit board  30 . The luminaire  8  further includes the thermally-conductive medium  50 . The thermally-conductive medium  50  is provided on the side of the first main surface  30   a  of the circuit board  30 , and is in contact with the electronic component  40  via the notch  31  or the through hole  32 . In addition, the luminaire includes a translucent shielding member  81  having a spherical shape and a cap  16 . 
     In the luminaire  8 , the heat generated by the electronic components  40  is transferred from the side of the second main surface  30   b  to the side of the first main surface  30   a  of the circuit board  30  via the thermally-conductive medium  50  in contact with the electronic components  40  via the interior of the notch  31  or the interior of the through hole  32 . Subsequently, the heat is radiated to the thermal radiator  15  or the cap  16  via the thermally-conductive medium  50 . Therefore, in the luminaire  8  as well, the thermal radiating effect of the electronic components  40  is enhanced. 
     Also, the luminaire  8  does not require covering of the entire surfaces of the electronic components  40  on the side of the second main surface  30   b  of the circuit board  30  with the thermally-conductive medium  50 , or embedding the electronic components  40  into the thermally-conductive medium  50 . Therefore, the amount of usage of the thermally-conductive medium  50  is significantly reduced, so that the cost reduction of the luminaire is achieved. 
     The embodiments are described with reference to detailed examples thus far. However, the embodiments are not limited to the detailed examples shown above. In other words, configurations modified in design as needed by those skilled in the art are also included within the scope of the embodiments as long as characteristics of the embodiments are included. The respective elements provided in respective detailed examples, the arrangements, the materials, the conditions, the shapes and the sizes thereof are not limited to the examples given above, and modifications may be made as needed. 
     The respective elements provided in the above-described embodiments may be combined as long as technically possible, and such combined configurations are also included in the scope of the embodiments as long as the characteristics of the embodiments are included. Various modifications or corrections may be imagined by those skilled in the art within the range of the consciousness of the embodiments, and those modifications and corrections are also understood to be included in the scope of the embodiments. 
     Although the several exemplary embodiments are described thus far, these embodiments are illustrative only, and are not intended to limit the scope of the invention. The novel embodiments as described above may be implemented in various modes, and omissions, replacements, and modifications may be made without departing the scope of the exemplary embodiments. These embodiments and the modifications are included in the scope and the gist of the exemplary embodiments, and are included in claims and equivalent ranges.