Patent Publication Number: US-8981636-B2

Title: Lamp having improved insulation of the circuit unit

Description:
TECHNICAL FIELD 
     The present invention is related to lamps using light-emitting elements such as LEDs as a light source. 
     BACKGROUND ART 
     LEDs are a type of semiconductor light-emitting element. With a view to energy conservation, in recent years a lamp (hereafter, “LED lamp”) using LEDs as a light source has been proposed as a bulb-type lamp that is an alternative to an incandescent light bulb. 
     The LED lamp includes a plurality of LEDs, a mounting board, a case that is cylindrically shaped, a cover member that closes one end of the case, and a circuit unit that enables the LEDs to emit light. The LEDs are mounted on the mounting board, the mounting board is installed on a surface of the cover member, and the circuit unit is fitted inside the case (Patent Literature 1). 
     In the LED lamp disclosed in Patent Literature 1, the cover member has a function of conducting heat generated when the LEDs emit light to the case, and the case has a heat dissipation function of dissipating heat that is conducted from the cover member. Thus, the cover member and the case are formed from metal material having a high thermal conductivity, and the cover member and the case are joined in contact with each other. 
     In order to ensure that the circuit unit is in an insulated state inside the case, a resin housing that houses the circuit unit is provided inside the case. Thus, the circuit unit is isolated from the case. The resin housing consists primarily of a main part that is cylindrical and houses the circuit unit, and a cover part that closes an opening at one end of the main part. The cover part is attached to the cover member by using a screw. 
     CITATION LIST 
     Patent Literature 
     [Patent Literature 1] 
     Japanese Patent Publication No. 4612120 
     SUMMARY OF INVENTION 
     Technical Problem 
     In recent years, consideration is being given to resinification of the case in an LED lamp to achieve weight reduction. In such a case, the main part mentioned above, for ensuring insulation, is unnecessary. However, insulation is still necessary between the cover member, which is made of metal, and the circuit unit. 
     When using the cover part of the housing in the LED lamp mentioned above as insulation between the cover member and the circuit unit, the cover part and the cover member need to be fixed by a screw, and assembly is awkward. 
     The present invention aims to provide a lamp having a simple configuration that easily ensures insulation of the circuit unit. 
     Solution to Problem 
     The lamp pertaining to the present invention includes: an envelope formed by a globe and a case, a light emitting element disposed inside the envelope, and a circuit unit disposed inside the envelope and configured to light the light-emitting element, wherein the light-emitting element is attached to an extension member that extends from a mount into the globe, the mount closing an opening at one end of the case, the circuit unit being disposed inside the case, which is closed by the mount, the mount is made of an electrically conductive material, and an insulation member is disposed inside the case to insulate the circuit unit from the mount, the mount has a cylinder portion and a cover portion that closes one end of the cylinder portion, and the extension member is mounted on the cover portion of the mount, and the insulation member has a cylindrical portion that is inserted into the cylinder portion of the mount and has a protrusion portion that is formed on an outer circumference of the cylindrical portion and that protrudes toward the mount, the insulation member being attached to the mount by the protrusion portion pressing on an inner surface of the cylinder portion of the mount. 
     Advantageous Effects of Invention 
     According to the above configuration, by inserting the cylindrical portion of the insulation member, which ensures insulation of the circuit unit, into the cylinder portion of the mount, the protrusion portion of the insulation member presses the inner surface of the cylinder portion of the mount. Thus, assembly is easy since the insulation member is attached to the mount, as described above, and a simple configuration using the protrusion portion is implemented. 
     Further, the protrusion portion is a plurality of protrusion portions disposed in a circumferential direction of the cylindrical portion, each protrusion portion being elongated in a direction parallel to the central axis of the cylindrical portion. Alternatively, the protrusion portion is a plurality of protrusion portions disposed in a circumferential direction of the cylindrical portion, each protrusion portion having a bump shape. 
     Further, the insulation member has an end wall disposed at one of two ends of the cylindrical portion, and the protrusion portion is disposed closer to the other one of the two ends of the cylindrical portion than the one end at which the end wall is disposed. Furthermore, the cover portion of the mount and the end wall of the insulation member are in contact with each other, a through hole passes through the cover portion of the mount and the end wall of the insulation member, and the extension member is fixed by a screw member, which has a head portion disposed inside the cylindrical portion of the insulation member and a screw portion that passes through the through hole. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an LED lamp pertaining to an embodiment. 
         FIG. 2  is a front elevation cross-sectional view of the LED lamp. 
         FIG. 3  is an exploded perspective view of the LED lamp. 
         FIGS. 4A and 4B  illustrate the structure of an LED module,  FIG. 4A  being a plan view of the LED module, and  FIG. 4B  being a cross-sectional view of the LED module taken along the line A-A′ in  FIG. 4A . 
         FIGS. 5A and 5B  illustrate the structure of a case,  FIG. 5A  being a plan view of the case, and  FIG. 5B  being a cross-sectional view of the case taken along the line B-B′ in  FIG. 5A . 
         FIG. 6A  is a perspective view of a state in which an insulation member is attached to a mount, and  FIG. 6B  is a perspective view of the insulation member and the mount in a separated state. 
         FIG. 7A  is a plan view of a state in which the insulation member is attached to the mount, and  FIG. 7B  is a plan view of the insulation member and the mount in a separated state. 
         FIG. 8  is a cross-sectional view taken along the line C-C′ in  FIG. 7A . 
         FIGS. 9A and 9B  illustrate a state in which a circuit substrate is attached to the case,  FIG. 9A  being a plan view and  FIG. 9B  being a cross-sectional view. 
         FIGS. 10A and 10B  are illustrations for explaining a state in which a base assembly is attached to the case,  FIG. 10A  being a plan view and  FIG. 10B  being a cross-sectional view. 
         FIG. 11  is a schematic view of a lighting device pertaining to another embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     The materials and values used in the embodiment only indicate preferable examples, and the present invention is not limited in this way. Also, appropriate changes and modifications may be made without departing from the spirit and scope of the present invention. Further, a combination of the present embodiment and modifications, or a combination of modifications, may be made as long as such combination does not cause contradiction. Furthermore, the scale of the components in each drawing differs from their actual scale. 
     Embodiment 
     1. Overall Configuration 
       FIG. 1  is a perspective view of an LED lamp  1  pertaining to the present embodiment.  FIG. 2  is a front elevation cross-sectional view of the LED lamp  1 .  FIG. 3  is an exploded perspective view of the LED lamp  1 . 
     The LED lamp  1  (corresponding to the lamp pertaining to the present invention) includes an LED module  5 , a globe  7 , a case  9 , a base  11 , a mount  13 , an extension member  15 , a circuit unit  17 , and an insulation member  19 . The LED module  5  includes LEDs  3  that are a light source (refer to  FIG. 4B ). The globe  7  has the LED module  5  disposed therein. The case  9  is attached to an end portion of the globe  7  at an open side thereof. The base  11  is attached to an end of the case  9  (the lower end in  FIG. 1 ). The mount  13  closes another end of the case  9  and is made of metal. The extension member  15  is attached to the mount  13 , extends into the globe  7 , and, at the end of the extension, the LED module  5  is mounted thereon. The circuit unit  17  is housed in the case  9 , which is closed by the mount  13 . The insulation member  19  is disposed in the case  9  and ensures insulation between the mount  13  and the circuit unit  17 . 
     Note that in the present specification, a base direction is a direction along a central axis of the LED lamp downwards toward the base  11  and a globe direction is the opposite direction along the central axis of the LED lamp upwards toward the globe  7 . Also, an envelope housing the LED module  5  and the circuit unit  17  includes the globe  7  and the case  9 . 
     2. Configuration of Parts 
     (1) LED Module 
       FIGS. 4A and 4B  illustrate the structure of the LED module  5 .  FIG. 4A  is a plan view of the LED module  5 , and  FIG. 4B  is a cross-sectional view of the LED module  5  taken along the line A-A′ in  FIG. 4A . 
     As shown in  FIG. 1 ,  FIG. 2 ,  FIG. 3 , and particularly in  FIG. 4A  and  FIG. 4B , the LED module  5  includes a mounting board  21 , the LEDs  3 , and a sealant  23 . The LEDs  3  are mounted on a surface of the mounting board  21  (an upper surface, which is a side facing away from the base  11 ). The sealant  23  covers the LEDs  3 . 
     The mounting board  21  has a rectangle shape in plan view, and is formed, for example, from a light-transmissive material such as glass or alumina, in order to avoid obstructing light that is emitted backwards, in the base direction, from the LEDs  3 . 
     As shown in  FIG. 4A , the mounting board  21  has a conduction path  25 , which is composed of a connection pattern  25   a , a terminal pattern  25   b , and a terminal pattern  25   c . The connection pattern  25   a  is for connecting the LEDs  3  (in serial connection and/or parallel connection). The terminal pattern  25   b  and the terminal pattern  25   c  are for connecting a corresponding one of a lead wire  27  and a lead wire  29 , which are connected to the circuit unit  17 . Note that the conduction path  25  is also made of light-transmissive material, such as ITO, to allow transmission of light from the LEDs  3 . 
     As shown in  FIG. 3  and  FIG. 4B , the mounting board  21  has two through-holes  31  passing therethrough, formed such that one through-hole  31  passes through the terminal pattern  25   b  and the other through-hole  31  passes through the terminal pattern  25   c . The lead wire  27  passes through the one through-hole  31  and the lead wire  29  passes through the other through-hole  31 . A tip portion of the lead wire  27  and a tip portion of the lead wire  29  are adhered (connected) to the terminal pattern  25   b  and the terminal pattern  25   c , respectively, by soldering  33 . 
     The mounting board  21  has, in a center thereof in plan view, a fitting hole  35 . The fitting hole  35  fits to a fitting protrusion portion  87  of the extension member  15 . The fitting hole  35  has a polygonal shape in plan view, and specifically a rectangular shape. Note that the fitting protrusion portion  87  of the extension member  15  also has a rectangular shape, to prevent attachment of the mounting board  21  to the extension member  15  in an incorrect orientation. 
     The LEDs  3  are mounted on the mounting board  21  in the form of chips. As shown in  FIG. 4A  and  FIG. 4B , the LEDs  3  are disposed at intervals (for example, regular intervals) in two parallel rows in a longitudinal direction of the mounting board  21 . 
     The sealant  23  is primarily composed of a light-transmissive material such as silicone resin, for example. The sealant  23  has a sealant function of preventing air and water penetrating to the LEDs  3 , and a wavelength conversion function of converting the wavelength of light from the LEDs  3 . The sealant function is implemented by coating each of the rows in which the LEDs  3  are arranged. The wavelength conversion function is implemented by, for example, mixing a conversion material into the light-transmissive material that converts a certain wavelength of light, such as fluorescent particles. 
     (2) Globe 
     As shown in  FIG. 1 ,  FIG. 2  and  FIG. 3 , the globe  7  has a similar shape to a bulb of an incandescent light bulb (also called a glass bulb), and is a so-called A-type bulb. The globe  7  is made from light-transmissive material, such as glass. 
     The globe  7  includes a spherical portion  7   a  that has a hollow spherical shape and a cylindrical portion  7   b  that has a cylindrical shape. The cylindrical portion  7   b  decreases in diameter as distance from the spherical portion  7   a  increases. 
     As shown in  FIG. 2 , an opening end portion  7   c  exists at an end portion of the cylindrical portion  7   b , opposite the spherical portion  7   a . The opening end portion  7   c  is fixed to the case  9  by adhesive  37 . As shown in the enlargement in  FIG. 2 , an end edge  7   d  of the opening end portion  7   c  has a bulging spherical shape (a sphere having a diameter greater than the thickness of the remainder of the opening end portion  7   c ). The bulging spherical shape prevents the globe  7  from separating from the case  9  (separating from the adhesive  37 ), because even if adhesion is lost between the globe  7  and the adhesive  37 , the end edge  7   d  of the globe  7  is engaged with the adhesive  37 . 
     (3) Case 
     The case  9  is composed of resin material such as polybutylene terephthalate (PBT) and has a shape similar to the portion of a bulb of an incandescent light bulb that is near a base. In the present embodiment, along a central axis of the case  9 , the case  9  has a large diameter portion  9   a  in the globe direction and a small diameter portion  9   b  in the base direction. The large diameter portion  9   a  has a trumpet shape that gradually increases in diameter with distance from the small diameter portion  9   b.    
     The case  9  has a function of dissipating heat generated by the circuit unit  17 , which generates heat when the LED lamp  1  is lit, to the outside of the case  9 . As described above, the circuit unit  17  is housed inside the case  9 . Heat dissipation is performed by heat conduction and radiation from the case  9  to the outside air, and by convection of the outside air. 
     As shown in the enlargement in  FIG. 2 , an opening at one end of the case  9  is closed by the insertion of the mount  13  into an end portion of the large diameter portion  9   a . Also, the opening end portion  7   c  of the globe  7  is inserted into a gap between an outer circumferential surface of the mount  13  and an inner circumferential surface of the large diameter portion  9   a  of the case  9 . In such a state, the case  9 , the globe  7 , and the mount  13  are fixed by the adhesive  37 . 
       FIGS. 5A and 5B  illustrate the structure of the case  9 .  FIG. 5A  is a plan view of the case  9 , and  FIG. 5B  is a cross-sectional view of the case  9  taken along the line B-B′ in  FIG. 5A . 
     As shown in  FIG. 3  and  FIGS. 5A and 5B , disposed inside the large diameter portion  9   a  is a reinforcement unit  41 , a fixing unit  43 , a support unit  45 , a support unit  46 , and a rotation restriction unit  47 . The reinforcement unit  41  reinforces the large diameter portion  9   a . The fixing unit  43  fixes the insulation member  19  that is attached to the mount  13 . The support unit  45  and the support unit  46  support the circuit unit  17 . The rotation restriction unit  47  restricts rotation of the mount  13 . 
     As shown in  FIG. 3 , the reinforcement unit  41  has an arc portion  41   a , and a connection portion  41   b . The arc portion  41   a  has an arc shape that follows a circumferential wall of the large diameter portion  9   a  (which has a cylindrical shape). The arc portion  41   a  is elongated in a direction that is parallel to the central axis of the large diameter portion  9   a . The connection portion  41   b  connects each end of the arc portion  41   a  in a circumferential direction thereof to the large diameter portion  9   a . Due to the reinforcement by the reinforcement unit  41 , the thickness of the circumferential wall of the large diameter portion  9   a  is reduced and the weight of the case  9  is reduced. Note that the arc portion  41   a , in plan view ( FIG. 5A ), has a shape of an interrupted circle centered on a central axis of the large diameter portion  9   a.    
     As shown in  FIG. 5A , the reinforcement unit  41  is provided in a plurality, in the present embodiment four reinforcement units  41 , at regular intervals in a circumferential direction of case  9 . Four intervals exist between the four reinforcements units  41  in the circumferential direction of the case  9 , and by passing through two of the four intervals, the lead wires  27  and  29  connect to the circuit unit  17  and the LED module  5 . 
     The fixing unit  43  has a support portion  43   a  and a locking portion  43   b . The support portion  43   a  supports the insulation member  19  from the base direction. The locking portion  43   b  locks the insulation member  19  into position from the globe direction (refer to  FIG. 10B ). 
     The support portion  43   a  protrudes in the globe direction (upwards) from a substantially central position of an upper surface of the arc portion  41   a  in the circumferential direction of the case  9 . Note that it suffices that the support portion  43   a  supports the insulation member  19  from the base direction, and therefore the support portion  43   a  need not be a protrusion. 
     The fixing unit  43  is provided in a plurality, in the present embodiment four fixing units  43 , at regular intervals in a circumferential direction of the case  9 . In plan view, each of the locking portions  43   b  is positioned between two of the reinforcement units  41  that are adjacent in the circumferential direction of the case  9 . Note that the present invention is not limited to four of the locking portions  43   b  being provided, and two or more of the locking portions  43   b  are sufficient to fix the insulation member  19  into position. 
     As shown in  FIG. 5B , each of the support unit  45  and the support unit  46  is a ridge portion protruding from an inner surface of a different one of the arc portions  41   a  toward the central axis of the large diameter portion  9   a , and is elongated toward the small diameter portion  9   b . In the present embodiment three support units  45  and one support unit  46  are provided, for a total of four ridge portions being provided. 
     Each of the support unit  45  is composed of a fitting portion  45   a  and a support portion  45   b . An upper end of the fitting portion  45   a  extends to an upper end of the reinforcement unit  41  (the arc portion  41   a ) and fits into a corresponding one of a cutaway portion  91   a , a cutaway portion  91   b , and a cutaway portion  91   c  that are formed on a circuit substrate  91  of the circuit unit  17 . The support portion  45   b  is positioned closer to the central axis of the case  9  than the fitting portion  45   a  and supports the circuit substrate  91  from the base direction. Thus, the support units  45  support the circuit substrate  91  and restrict rotation of the circuit substrate  91  inside the case  9 . 
     The upper end of the support portion  45   b  is positioned closer to the base  11  than the upper end of the fitting portion  45   a , such that a portion of the upper end of each of the support units  45  that is closer to the center of the case  9  is lower than the other portion of the upper end of each of the support units  45 , which is farther from the center of the case  9 . Thus the supports units  45  each have a stepped shape. 
     The support unit  46  is composed of a support portion  46   a  that supports the circuit substrate  91  from the base direction. An upper end position of the support portion  46   a  is the same as the upper end position of the support portion  45   b  of the support unit  45 . Thus, the circuit substrate  91  is supported orthogonally to the central axis of the case  9 , by the support portions  45   b  of the support unit  45  and the support portion  46   a  of the support unit  46 . 
     The rotation restriction unit  47  is formed as a ridge protruding from an area of the inner surface of the large diameter portion  9   a  where the mount  13  is to be attached, toward the central axis of the large diameter portion  9   a . Further, the rotation restriction unit  47  is elongated along the central axis of the case  9 , in the base direction. Furthermore, the rotation restriction unit  47  fits into a restriction groove  13   f  of a flange portion  13   c  of the mount  13 . Thus, the rotation restriction unit  47  restricts the mount  13  from rotating inside the case  9 . 
     The small diameter portion  9   b  has a joining unit that joins to the base  11 . Specifically, an outer circumferential surface of the small diameter portion  9   b  has a male thread  49  that mates with a thread of the base  11 , which is an Edison-type base. 
     As shown in  FIG. 3  and  FIG. 5B , part of the outer circumferential surface of the small diameter portion  9   b  has a fixing groove  51  and a cutaway portion  53 . The fixing groove  51  is for fixing a lead wire  67  that connects the base  11  and the circuit unit  17 . The cutaway portion  53  is at a lower end of the small diameter portion  9   b , is connected to the fixing groove  51 , determines the position of the lead wire  67 , and fixes the lead wire  67  into position. The fixing groove  51  is elongated in a direction parallel to the central axis of the case  9 . 
     (4) Base 
     The base  11  is for receiving power from a socket of a lighting apparatus when the LED lamp  1  is attached to the lighting apparatus and lit. 
     The base  11  is not specifically limited to any type of base, but an Edison-type base is used in the present embodiment, as shown in  FIGS. 1-3 . As shown in  FIG. 2 , the base  11  is composed of a shell portion  61  and an eyelet portion  65 . The shell portion  61  has a cylindrical shape and a circumferential wall that is threaded. The eyelet portion  65  is attached to the shell portion  61 , and insulation material  63  is between the eyelet portion  65  and the shell portion  61 . 
     The lead wire  67  is connected to the shell portion  61  by being bent back toward the outer circumferential surface of the case  9  at the cutaway portion  53  at the lower end of the small diameter portion  9   b , by being covered by the shell portion  61  while being inserted into the fixing groove  51  of the case  9 . Further, a lead wire  69  is connected to the eyelet portion  65  by soldering. Thus, the base  11  is connected to the circuit unit  17 . 
     (5) Mount 
     The mount  13  closes an opening at an upper end of the case  9  and has the extension member  15  attached thereto. The mount  13  is formed from metal material (for example, aluminium material) for easy conduction of heat generated by the LED module  5  upon light emission, to the globe  7 , the case  9 , etc. 
       FIG. 6A  is a perspective view of a state in which the insulation member  19  is attached to the mount  13 , and  FIG. 6B  is a perspective view of the insulation member  19  and the mount  13  in a separated state.  FIG. 7A  is a plan view of the state in which the insulation member  19  is attached to the mount  13 , and  FIG. 7B  is a plan view of the insulation member  19  and the mount  13  in the separated state.  FIG. 8  is a cross-sectional view taken along the line C-C′ in  FIG. 7A . 
     As shown in the upper portion of  FIG. 6B , the mount  13  has a cylinder portion  13   a , a cover portion  13   b , and the flange portion  13   c . The cover portion  13   b  closes an opening at an upper end of the cylinder portion  13   a  in a central axis direction of the cylinder portion  13   a . The flange portion  13   c  protrudes from a lower end of the cylinder portion  13   a  in a central axis direction, outward in a radial direction from the central axis of the cylinder portion  13   a . A central area of an upper surface of the cover portion  13   b  is an attachment area  71  for attaching the extension member  15 . 
     As shown in  FIG. 3  and the upper portion of  FIG. 6B , the flange portion  13   c  is provided in a plurality (for example, four flange portions  13   c ) at regular intervals in a circumferential direction of the cylinder portion  13   a . Further, as shown in  FIG. 8 , at portions of the lower end of the cylinder portion  13   a  without the flange portion  13   c  (indicated as  13   d  in  FIG. 6B ), step portions  13   e  that are indented toward the central axis of the mount  13  are formed. 
     As shown in the enlargement in  FIG. 2 , the adhesive  37  wraps around the step portion  13   e  of the mount  13 . Thus, the provision of the step portions  13   e  prevents the adhesive  37  from separating from the case  9  and the mount  13  even if the adhesive  37  between the case  9  and the mount  13  loses adhesion thereto, since the portion of the adhesive  37  around the step portions  13   e  is engaged with the step portions  13   e . Note that step portions may instead be formed on the case  9  for the adhesive  37  to wrap around. 
     One of the four flange portions  13   c  has formed therein the restriction groove  13   f , which is elongated parallel to the central axis of the mount  13 . When the mount  13  is attached to the case  9 , the restriction groove  13   f  fits onto the rotation restriction unit  47 . 
     The attachment area  71  has a fitting unit that fits with the extension member  15  (refer to  FIG. 3 ). As shown in the upper portion of  FIG. 6B , the fitting unit is formed by a fitting protrusion portion  73  that protrudes upwards, for fitting to a fitting groove  81  at a lower end portion of the extension member  15 . Two through-holes  75  and a through-hole  77  are formed in the fitting protrusion portion  73 , penetrating the fitting protrusion portion  73  in the direction of thickness of the cover portion  13   b . The two through-holes  75  are for the lead wires  27  and  29 , which connect the circuit unit  17  and the LED module  5 . The through-hole  77  is for a screw  121  that is for fixing the extension member  15 . 
     The through-hole  77  is positioned along the central axis of the mount  13  (in plan view, the center of the cover portion  13   b ). As shown in the upper portion of  FIG. 7B , the through-holes  75  are positioned on an imaginary straight line D that passes through the through-hole  77 . In plan view, the imaginary straight line D passes through a substantially central point between opposing pairs of the flange portion  13   c  in the circumferential direction of the mount  13 . 
     (6) Extension Member 
     As shown in  FIG. 3 , the extension member  15  has an overall shape of a rod and is formed from metal material, which has high thermal conductivity. The extension member  15  is composed of a base attachment portion  15   a  that is attached to the mount  13 , a module attachment portion  15   b  to which the LED module  5  is attached, and a connection portion  15   c  that connects the base attachment portion  15   a  and the module attachment portion  15   b.    
     The base attachment portion  15   a  has a circular truncated cone shape that tapers off toward the connection portion  15   c . The base attachment portion  15   a  has a fitting groove  81  that is rectangular in plan view and is for fitting to the fitting protrusion portion  73  of the attachment area  71  of the mount  13 . In addition, as shown in  FIG. 2 , the base attachment portion  15   a  has two through-holes  83  for the lead wires  27  and  29 , and a screw-hole  85  for fixing the mount  13  into position. The two through-holes  83  are aligned with the two through-holes  75  of the mount  13  and the screw-hole  85  is aligned with the through-hole  77  of the mount  13 . 
     As shown in  FIG. 3 , the module attachment portion  15   b  has a shape similar to an inversion of the shape of the base attachment portion  15   a . The module attachment portion  15   b  has a modified circular truncated cone shape that lacks portions of the circular truncated cone shape that would protrude beyond the rectangular shape of the LED module  5  in plan view. As shown in  FIG. 2 , the fitting protrusion portion  87  is formed at a central position of an upper end surface of the module attachment portion  15   b , and is for fitting to the fitting hole  35  that is formed in the mounting board  21  of the LED module  5 . 
     (7) Circuit Unit 
     The circuit unit  17  receives power via the base  11 , converts the power to LED applicable power, and supplies the converted power to the LED module  5  (the LEDs  3 ). As shown in  FIG. 3 , the circuit unit  17  is composed of the circuit substrate  91  and electrical components  93 ,  95 , and  97  that are mounted on the circuit substrate  91 . 
     In plan view, the circuit substrate  91  has a shape similar to a circular shape, and has the cutaway portion  91   a  and the cutaway portion  91   b  that correspond to protruding portions of the inner circumference of the large diameter portion  9   a  of the case  9  (specifically, an upper portion of the fitting portion  45   a ). Thus, the circuit substrate  91  is restricted from rotating inside the case  9 . Two cutaway portions  91   d  are formed on a circumferential rim of the circuit substrate  91 , opposite each other across the center of the circuit substrate  91 . The two cutaway portions  91   d  are for the lead wires  27  and  29 , which connect the circuit unit  17  and the LED module  5 . When the LED lamp  1  is in an assembled state, the two cutaway portions  91   d  are positioned, in plan view, along the imaginary straight line D and an imaginary straight line E, which are shown in  FIG. 7B . 
     The electrical components of the circuit unit  17  include a rectification circuit that rectifies commercial power (AC) received via the base  11 , a smoothing circuit that smoothes rectified DC power, a step-down circuit that steps-down a smoothed voltage to a predetermined voltage, etc. 
     Here, the rectifying circuit includes a diode bridge  93 , the smoothing circuit includes a capacitor  95 , and the step-down circuit includes a transistor  97 , a capacitor  99 , a switching element, etc. 
     Note that, of the electrical components, the diode bridge  93 , for example, is attached to a main surface of the circuit substrate  91  on side that is closer to the globe  7  than an opposite side of the circuit substrate  91  that is closer to the base  11 . Also, the circuit substrate  91  is between the support unit  45  and the insulation member  19 , inside the case  9  in such a way that there is a slight possibility of the circuit substrate  91  moving up and down. 
     (8) Insulation Member 
     As shown in  FIG. 3 ,  FIG. 6A ,  FIG. 6B ,  FIG. 7A ,  FIG. 7B , and  FIG. 8 , the insulation member  19  has a bottomed cylindrical shape, is formed from a resin material, and is inserted into and fixed to the inside of the cylinder portion  13   a  of the mount  13 . The insulation member  19  has a bottomed cylinder portion  19   a  and a flange portion  19   b . The bottomed cylinder portion  19   a  has a cylindrical portion that is a circumferential wall of the insulation member  19  and an end wall at one end of the cylindrical portion. The flange portion  19   b  projects outward in a radial direction from the other end of the cylindrical portion of the bottomed cylinder portion  19   a . As shown in the lower portion of  FIG. 7B , a plurality of protrusion portions  101  (here, four protrusion portions  101 ) are formed at regular intervals in a circumferential direction on an outer circumferential surface of the bottomed cylinder portion  19   a . The protrusion portions  101  are for fixing the insulation member  19  to the mount  13 . 
     A pair of a protrusion  103   a  and a protrusion  103   b  are formed on the flange portion  19   b , protruding upward into an area between pieces of the flange portion  13   c  that are adjacent in the circumferential direction of the cylinder portion  13   a  (an area  13   d  where the flange portion  13   c  is not present). Four pairs of the protrusion  103   a  and the protrusion  103   b  are formed. Each pair corresponds to one of the four areas where the flange portion  13   c  of the mount  13  is not present. Thus, the pairs of the protrusion  103   a  and the protrusion  103   b  are usable as a guide for aligning the insulation member  19  and the mount  13  when attaching the insulation member  19  to the mount  13 , and restrict rotation of the insulation member  19  relative to the mount  13  when the insulation member  19  is attached to the mount  13 . 
     As shown in  FIG. 3 ,  FIG. 6A , and  FIG. 6B , a surface of the end wall of the bottomed cylinder portion  19   a  that faces the globe direction is flat. As shown in FIG.  8 , a thick portion  104  protrudes in the base direction from a central area of a surface of the end wall of the bottomed cylinder portion  19   a  that faces the base direction. Two through-holes  105  are provided that penetrate the thick portion  104 , for the lead wires  27  and  29  that connect the circuit unit  17  and the LED module  5 . A through-hole  107  is provided that penetrates the thick portion  104 , for the screw  121  that is for fixing the extension member  15  into position. 
     As shown in the bottom portion of  FIG. 7B , the through-hole  107  is positioned along a central axis of the insulation member  19  (in plan view, at the center of the end wall), and the two through-holes  105  are positioned on the imaginary straight line E that passes across the through-hole  107 . In plan view, the imaginary straight line E is coincident with the imaginary straight line D. Note that the through-holes  105  are wider than the through-holes  75  of the mount  13 , in order that the lead wires  27  and  29  pass through the two through-holes  105  easily. 
     As shown in  FIG. 8 , in a substantially central area of the thick portion  104 , a concave portion  104   a  is formed for fitting a head portion  121   a  of the screw  121  that connects the mount  13 , the insulation member  19 , and the extension member  15 . 
     Convex protrusion portions  19   c  protrude downward from a lower surface of the flange portion  19   b , and are formed in two locations opposing each other. The convex protrusion portion  19   c  is for restricting upward movement of the circuit substrate  91  of the circuit unit  17 . Note that the convex protrusion portion  19   c  and the circuit substrate  91  of the circuit unit  17  are in contact, and therefore a gap exists between the circuit substrate  91  and the insulation member  19  corresponding to a protrusion amount of the convex protrusion portion  19   c . The lead wires  27  and  29  pass through the gap, and therefore disconnection of the lead wires  27  and  29  is prevented. 
     3. Assembly 
     The following is an explanation of assembly of the LED lamp  1 , and particularly of how the parts join together. Note that in the following, only the joining of representative parts is explained, and the explanation may not coincide with the actual order of assembly of the LED lamp  1 . 
     (1) Module and Extension Member 
     Joining of the LED module  5  and the extension member  15  is performed by (i) fitting the fitting hole  35  that is formed in the mounting board  21  of the LED module  5  to the fitting protrusion portion  87  that is formed at the upper end surface of the module attachment portion  15   b  of the extension member  15 , (ii) inserting the lead wire  27  through one of the through-holes  31  and inserting the lead wire  29  through the other one of the through-holes  31 , and (iii) fixing the upper ends of the lead wires  27  and  29  to the mounting board  21  by the soldering  33 . 
     Here, since the fitting hole  35  and the fitting protrusion portion  87  each have a polygonal shape in plan view, rotation of the LED module  5  relative to the extension member  15  is restricted. Also, the center of the mounting board  21  is fixed in position by the fitting protrusion portion  87 , and both end portions of the mounting board  21  in a longitudinal direction of the mounting board  21  are fixed in position by the lead wires  27  and  29 . Thus, the LED module  5  is supported by the extension member  15 , etc., in a stable state. 
     Note that, for increasing the coherence (contact) or reducing imperfections in the contact area between the mounting board  21  and the module attachment portion  15   b , the mounting board  21  and the module attachment portion  15   b  may be, for example, fixed by an adhesive having a high thermal conductivity. Note that by increasing coherence between the mounting board  21  and the module attachment portion  15   b , the amount of heat conducted from the LED module  5  to the extension member  15  is increased. 
     (2) Insulation Member and Mount 
     The insulation member  19  is attached to the mount  13  by inserting the bottomed cylinder portion  19   a  inside the cylinder portion  13   a  of the mount  13 . The protrusion portions  101 , which come in contact with an inner surface of the cylinder portion  13   a , are formed on an outer circumferential surface of the bottomed cylinder portion  19   a  of the insulation member  19 . Thus, the insulation member  19  is press-fitted to the mount  13 . 
     Since the mount  13  is formed from metal material and the insulation member  19  is formed from resin material, it suffices to adjust the protrusion amount of the protrusion portions  101  to ensure that the protrusion portions  101  contact with the mount  13 . 
     In other words, if the protrusion amount of the protrusion portion  101  is slightly larger than the gap between the inner circumferential surface of the cylinder portion  13   a  of the mount  13  and the outer circumferential surface of the bottomed cylinder portion  19   a  of the insulation member  19 , compression of the protrusion portion  101  due to press-fitting reduces incidences of separation of the insulation member  19  from the mount  13 . 
     On the other hand, if the protrusion amount of the protrusion portion  101  is considerably larger than the gap between the inner circumferential surface of the cylinder portion  13   a  of the mount  13  and the outer circumferential surface of the bottomed cylinder portion  19   a  of the insulation member  19 , depression (deformation) of the cylindrical portion (circumferential wall) of the bottomed cylinder portion  19   a  in the vicinity of the protrusion portions  101  due to press-fitting reduces incidences of separation of the insulation member  19  from the mount  13 . 
     As such, it suffices that the variation in the protrusion amount of the protrusion portions  101  is adjusted such that contact with the mount  13  is ensured at the lower limit of the protrusion amount of the protrusion portions  101 . Thus, the protrusion portions  101 , the insulation member  19 , and the mount  13  do not require high manufacturing precision, and the insulation member  19  can easily be attached to the mount  13 . In addition, easy separation of the insulation member  19  from the mount  13  is prevented. 
     Note that the mount  13  having the insulation member  19  attached thereto is called a base assembly. 
     (3) Extension Member and Base Assembly 
     The extension member  15  and the base assembly are joined (connected) by the screw  121   
     First, the fitting groove  81  on a lower surface of the base attachment portion  15   a  of the extension member  15  and the fitting protrusion portion  73  are fitted together to form a fitted state. In the fitted state, the through-hole  77  of the mount  13  and the screw-hole  85  of the extension member  15  are aligned, and the screw  121  is screwed into the screw-hole  85  of the extension member  15  from the insulation member  19  side of the base assembly via the through-hole  107  and the through-hole  77 . In this way, assembly of the extension member  15  and the base assembly is completed. 
     Note that, in plan view, the fitting groove  81  of the extension member  15  and the fitting protrusion portion  73  of the mount  13  have a shape that is not a circular shape, centered on the axis of the screw  121 . Here, the fitting groove  81  and the fitting protrusion portion  73  have matching elliptical shapes that are elongated in a direction parallel to a line through the axis of the screw  121 . Thus, even when the screw  121  is screwed into the screw-hole  85  of the extension member  15 , rotation of the extension member  15  relative to the base assembly is prevented. 
     Note that here, the screw  121  is made of metal. In order to ensure insulation between the screw  121  and the circuit substrate  91 , after the screw  121  is screwed in and fixed inside the concave portion  104   a  of the thick portion  104  of the insulation member  19 , the inside of concave portion  104   a  is filled up with a silicon resin  123 , covering the screw  121  (refer to  FIG. 2 ). The silicon resin  123  is insulative. Note that the silicon resin  123  also has a function of preventing loosening of the screw  121  and preventing separation of the screw  121  from the screwed-in position. 
     (4) Case and Circuit Unit 
     The circumferential rim of the circuit substrate  91  of the circuit unit  17  does not have a perfectly circular shape, and the circuit substrate  91  has the cutaway portions  91   a ,  91   b , and  91   c . The cutaway portions  91   a ,  91   b , and  91   c  correspond to the upper portions of the three fitting portions  45   a  in the inner circumferential surface of the case  9 . The cutaway portions  91   a ,  91   b  and  91   c  are each aligned to the corresponding one of the three fitting portions  45   a  and the circuit substrate  91  is inserted into the case  9  such that the capacitor  99  faces in the base direction. 
       FIGS. 9A and 9B  illustrate a state in which the circuit substrate  91  is inserted into the case  9 .  FIG. 9A  is a plan view and  FIG. 9B  is a cross-sectional view. 
     In plan view, the fitting portion  45   a  protrudes toward the center of the case  9 . Thus, as shown in  FIG. 9A , when the three fitting portions  45   a  are fitted to the cutaway portions  91   a ,  91   b , and  91   c , respectively, the circuit substrate  91  does not rotate relative to the case  9 . 
     As shown in  FIG. 9A , the circumferential rim of the circuit substrate  91  that is not cutaway portions, etc. is in contact with or near to the arc portion  41   a  of the reinforcement unit  41 . Thus, the circuit unit  17  does not move in a direction orthogonal to the central axis of the case  9 . 
     Also, a portion of the support unit  45  relatively close to the center of the case  9  is stepped down in the base direction. As shown in  FIG. 9B , the support portion  45   b , which is stepped down, and the support unit  46  support a rear surface of the circuit substrate  91  (the rear surface facing the base direction). 
     Note that, as shown in  FIG. 9A , a gap exists between the cutaway portions  91   d  of the circuit substrate  91  and the locking portions  43   b  of the case  9 . The lead wire  27  passes through one of the gaps and the lead wire  29  passes through the other one of the gaps. 
     (5) Case and Base Assembly 
       FIGS. 10A and 10B  are illustrations for explaining a state in which the base assembly is attached to the case  9 .  FIG. 10A  is a plan view and  FIG. 10B  is a cross-sectional view. 
     Note that in  FIG. 10B , in order to show the joining of the flange portion  19   b  and the fixing unit  43  of the case  9 , a cross-section of the flange portion  19   b  is shown as the cross-section of the insulation member  19 . 
     First, the locking portions  43   b  of the fixing units  43  of the case  9  and one pair of the protrusions  103   a  and the protrusions  103   b  are aligned, and a lower surface of the flange portion  19   b  is placed on an upper surface of the locking portions  43   b  (a “placed state”). The aligning is performed such that the restriction groove  13   f  of the base assembly (the mount  13 ) and the rotation restriction unit  47  fit together. By performing the alignment, each of the locking portions  43   b  exists between a different one of the pairs of the protrusions  103   a  and the protrusions  103   b.    
     Then, while in the placed state, the base assembly is pushed towards the small diameter in the base direction. As shown in  FIG. 10B , as the locking portions  43   b  approach the small diameter portion  9   b , the locking portions  43   b  protrude farther toward the center of the case  9 , such that an upper surface of each of the locking portions  43   b  forms a slope. Therefore, by pushing the base assembly, the flange portion  19   b  of the base assembly passes by the locking portions  43   b . Thus, as shown in  FIG. 10B , a lower surface of the locking portions  43   b  comes in contact with an upper surface of the flange portion  19   b  of the insulation member  19 , and movement of the base assembly in the globe direction is prevented. 
     On the other hand, as shown in  FIG. 10B , after the base assembly passes by the locking portion  43   b , a lower surface of the flange portion  19   b  of the insulation member  19  comes in contact with the support portions  43   a  of the case  9  to be supported from the base direction. Thus, the base assembly is attached to the case  9 . Since each of the locking portions  43   b  is positioned between one of each of the pairs of the protrusions  103   a  and the protrusions  103   b , rotation of the base assembly inside the case  9  is prevented. 
     Note that as shown in  FIG. 10B , the circuit substrate  91  of the circuit unit  17  is positioned between the joining portion  45   a  of the case  9  and the insulation member  19  such that, although some up and down movement is possible, the circuit substrate  91  is contained inside the case  9 . 
     4. Example of Implementation 
     The following is an explanation of an example of an implementation pertaining to the embodiment. 
     The LED lamp  1  is a replacement for a 20 W type incandescent light bulb, power input to the LED module  5  is 3.5 W, and when the power input is 3.5 W, a total luminous flux of the LED lamp  1  is 210 lm. 
     The LEDs  3  emit blue light. As the conversion material, fluorescent particles that convert blue light to yellow light are used. Thus, mixing of the blue light emitted by the LEDs  3  and yellow light from wavelength conversion by the fluorescent particles results in white light being emitted from the LED module  5  (the LED lamp  1 ). 
     In this example 24 LEDs  3  are disposed in two lines along a longitudinal direction of the mounting board  21 , each line including  12  of the LEDs  3  disposed at regular intervals of 1.25 mm. The  12  LEDs  3  in each of the lines are electrically connected in series, and the two lines of the LEDs  3  are electrically connected in parallel. 
     The mounting board  21  has a shape of a rectangle having short sides (L 1  in  FIG. 4A ) that are 6 mm long, and long sides (L 2  in  FIG. 4A ) that are 25 mm long. The thickness of the mounting board  21  is 1 mm. Light-transmissive alumina is used as the material of the mounting board  21 . Note that the volume of the mounting board is 150 mm 3 . 
     The mount  13  has an outer diameter (the outer diameter of the cylinder portion  13   a ) of 30 mm and a height of 8 mm. The thickness of the cylinder portion  13   a  is 1.95 mm and the thickness of the cover portion  13   b  is 2.2 mm. Note that an amount of protrusion of the flange portion  13   c  from the outer circumference of the cylinder portion  13   a  is 1.65 mm and the height of the flange portion  13   c  is 2.0 mm. 
     The total length of the extension member  15  (the distance between an upper surface and a lower surface of the extension member  15 , excluding the fitting protrusion portion  87  and the fitting groove  81 ) is 27 mm and the outer diameter of the connection portion  15   c  is 5 mm. The outer diameter of the lower end of the base attachment portion  15   a  is 10 mm. In plan view the module attachment portion  15   b  has a shape obtained by cutting away two portions from of a circle of diameter 8 mm. The two portions are defined by a pair of lines parallel to an imaginary line through the center of the circle and 3 mm distant from the imaginary line. The fitting protrusion portion  87  has a rectangular shape having a length (a measurement in the longitudinal direction of the LED module  5 ) of 1.9 mm and a width of 0.9 mm. Note that the protrusion amount of the fitting protrusion portion  87  from the module attachment portion  15   b  is 1 mm. Also note that the protrusion amount of the protrusion portion  101  of the insulation member  19  is 0.3 mm and a length of the protrusion portion  101  is 2 mm. 
     A contact area between the LED module  5  and the extension member  15  is 46.53 mm 2 , and a contact area between the mount  13  and the extension member  15  (including the contact area between the fitting protrusion portion  73  and the fitting groove  81 ) is 81.43 mm 2 . 
     5. Light Distribution Characteristics 
     In the LED lamp  1  pertaining to the embodiment, the LED module  5  is disposed at a position inside the globe  7  corresponding to the position (for example, in substantially the same position) of a light source of an incandescent light bulb (the filament). Thus, even if the LED lamp  1  is attached to a lighting apparatus that has a reflector for a conventional incandescent light bulb, the LED module  5  would be positioned at a focal point of the reflector. Therefore, light distribution characteristics similar to the light distribution characteristics of the conventional incandescent light bulb can be obtained. 
     Also, since the mounting board  21  in the LED module  5  is light-transmissive, light emitted backwards in the base direction from the LEDs  3  is transmitted through the mounting board  21  and emitted from the globe  7  to the outside of the LED lamp  1 . 
     Further, since the extension member  15  that supports the LED module  5  has a long, thin, rod shape, obstruction of light emitted backward from the LEDs  3  is decreased. 
     6. Heat Dissipation Paths 
     The LED lamp  1  pertaining to the embodiment dissipates heat that is generated upon light emission by multiple paths. In the present embodiment, heat that is generated when emitting light includes heat generated by the LEDs  3  and heat generated by the circuit unit  17 . 
     (1) Heat Generated by LEDs 
     (a) The heat generated by the LEDs  3  is conducted through the mounting board  21  of the LED module  5 , the extension member  15 , and then the mount  13 . Heat conducted to the mount  13  is conducted to the globe  7  and the case  9 . A portion of the heat conducted to the globe  7  and the case  9  is dissipated by the effects of heat transfer, convection, and radiation. Also, a portion of the heat conducted to the case  9  is conducted from the base  11  to a socket on a lighting apparatus side.
 
(b) In the LED lamp  1 , the globe  7  has a size and shape similar to a glass bulb of an incandescent light bulb. Therefore, the envelope volume of the globe  7  is large, and a large amount of heat is radiated from the globe  7 . Thus, a large amount of heat generated by the LEDs  3  is, via the extension member  15  and the mount  13 , dissipated from the globe  7 .
 
(2) Heat Generated by Circuit Unit
 
     Heat generated by the circuit unit  17  is conducted to the case  9  by heat transfer, convection, and radiation. A portion of heat conducted to the case  9  is dissipated from the case  9  by the effects of heat transfer, convection, and radiation, and the remaining heat is conducted to the socket on the lighting apparatus side. 
     (3) Thermal Load to Circuit Unit 
     In the LED lamp  1 , the globe  7  has a size and shape similar to a glass bulb of an incandescent light bulb, and the LED module  5  is provided in a substantially central position inside the globe  7 . 
     Thus, (a) the distance between the LED module  5  and the circuit unit  17  is increased, reducing the thermal load received by the circuit unit  17  from the LEDs  3 , and (b) the distance between the LED module  5  and the case  9  is increased, reducing the amount of heat accumulated in the case  9  due to heat received from the LEDs  3 . Thus, the size of the case  9  can be reduced. On the other hand, the globe  7  (the envelope volume of the globe  7 ) can be increased in size, increasing the amount of heat dissipated from the globe  7 . 
     7. Protrusion Portion for Fixing Insulation Member 
     (1) Number of Pieces 
     In the embodiment, the four protrusion portions  101  are formed at regular intervals in the circumferential direction of the bottomed cylinder portion  19   a . However, it suffices that only one protrusion portion  101  be formed if attention is paid only to preventing the insulation member  19  falling apart from the mount  13 . If only one protrusion portion  101  is formed, there is a possibility of axial misalignment between the insulation member  19  and the axis of the mount  13 , but this can be adjusted for by forming larger through-holes for the lead wires  27  and  29 , and the screw  121 . 
     (2) Positions 
     (2-1) Positions in Plan View 
     In the embodiment, the protrusion portions  101  are formed at 90 degree intervals in a circumferential direction of the bottomed cylinder portion  19   a . However, for the same reason explained under the above heading “(1) Number of Pieces”, the positions of the protrusion portions  101  in plan view is not specifically limited in this way. Nevertheless, in order to restrict axial misalignment between the insulation member  19  and the mount  13 , positioning at least three protrusion portions  101  at regular intervals in plan view is desirable. 
     (2-2) Position in Side View 
     In the embodiment, the protrusion portions  101  are formed closer to an opening of the bottomed cylinder portion  19   a  than to the end wall thereof. This is because, when inserting the insulation member  19  into the mount  13 , if the protrusion portions  101  were formed near the end wall, deformation by the protrusion portion  101  of the portion of the bottomed cylinder portion  19   a  near the end wall would be difficult, and therefore insertion of the insulation member  19  into the mount  13  would be difficult. 
     However, if the protrusion portions  101  are such that the protrusion amount of the protrusion portions  101  gradually increases with increasing distance from the end wall, the protrusion portion  101  may be positioned near the end wall, or may be elongated from the end wall to the opening of the bottomed cylinder portion  19   a.    
     (3) Shape of Protrusion Portion 
     (3-1) Overall Shape 
     In the embodiment, the protrusion portions  101  are formed having a ridge shape and are elongated parallel to the central axis of the bottomed cylinder portion  19   a  of the insulation member  19 . However, the protrusion portions  101  may each have a bump shape (a dot shape). Also, each of the protrusion portions  101  in the embodiment has a ridge shape that has a constant protrusion amount and width. However, each of the protrusion portions  101  may have a ridge shape that has a variable protrusion amount and width. Specifically, each of the protrusion portions  101  may have a shape such that the protrusion amount and width of each of the protrusion portions  101  gradually increases with increasing distance from the end wall. 
     Also, each of the protrusion portions  101  may have an arc shape following the outer circumferential surface of the bottomed cylinder portion  19   a  in plan view. In such a case, each of the protrusion portions  101  may have an inclined surface, and increase in arc as the position of the arc shape approaches the opening of the bottomed cylinder portion  19   a.    
     (3-2) Cross-Sectional Shape 
     In the embodiment, a cross-section of each of the protrusion portions  101  before attachment of the insulation member  19  to the mount  13  (the cross-section being taken along a plane orthogonal to the central axis of the insulation member  19 , viewed in a direction of extension of the central axis of the insulation member  19 ) is a triangle shape that tapers off as each of the protrusion portions  101  approaches the mount  13  from the insulation member  19 . However, the shape of each of the protrusion portions  101  in cross-section may be other shapes. Examples of shapes that taper off, other than triangle shapes, include semicircle shapes, semi-elliptical shapes, trapezoid shapes, and polygonal shapes. Examples of shapes that do not taper off include square shapes and rectangular shapes. 
     &lt;Modifications&gt; 
     An explanation is given above based on an embodiment of the present invention, but the present invention is not limited to the above embodiment. For example, the following modifications are possible. 
     1. Mount and Extension Member 
     In the above embodiment, the extension member and the mount are separate members and are joined by the screw, but, for example, the extension member and the mount may be integrated into a single body. Die casting or machining may be used to form the single body. 
     In the above embodiment, the extension member has a rod shape, but the extension member may have any shape or structure that positions the LEDs (the LED module) inside the globe. 
     For example, the extension member may have a cone shape or a polygonal pyramid shape, and further, may have a shape that becomes narrower through a series of steps as an upper part of the extension member is approached. Furthermore, the extension members may be provided in a plurality. For example, two rod-shaped extension members may be used to support both end portions of the mounting board of the LED module in the longitudinal direction of the mounting board (the end portions corresponding to the short sides of the mounting board), or four rod-shaped extension members may be used to support four corners of the rectangular mounting board. 
     In the above embodiment, a transverse cross-section of the cylinder portion of the mount has a circular shape, but as long as the extension member attaches to the cylinder portion and the cylinder portion closes one open end of the case, other shapes are possible. Examples of other shapes of the transverse cross-section include elliptical shapes or polygonal shapes. 
     2. Insulation Member 
     In the above embodiment, the insulation member has a bottomed cylindrical shape, but as long as the insulation member has a cylindrical portion that can be inserted into the inside of the cylinder portion of the mount, the insulation member may have other overall shapes. For example, the insulation member may have other overall shapes, such as a shape including a flat portion having a flat shape and a cylinder portion protruding from a central area of the flat shape. 
     Also, in the above embodiment, the insulation member has a bottomed cylindrical shape having the end wall as the bottom, but in a case where insulation is ensured between the cover portion of the mount and the circuit unit, the end wall is not required. 
     In the above embodiment, the insulation member has a bottomed cylindrical shape, and the end wall is in contact with the cover portion of the mount. Thus, accuracy when positioning the insulation member with respect to the mount is increased. On the other hand, to make conduction of heat from the mount to the insulation member more difficult, it suffices that faces of the end wall and the cover portion are not in surface contact with each other. Note that by providing an upper surface of the end wall with a bump portion contacting the cover portion of the mount, heat conduction to the insulation member from the mount is suppressed, while maintaining accuracy when positioning the insulation member with respect to the mount. 
     3. LED module 
     (1) LED 
     In the above embodiment, LED elements are used as the light source of the lamp. However, for example, surface-mount type or shell-type LEDs may be used, such that each LED element is resin sealed and the LED module is composed of the mounting board and the LEDs. 
     In the above embodiment, an example is given in which the LEDs emit blue light and the fluorescent particles convert blue light to yellow light, but other combinations are possible. As one example of a different combination, the LEDs may emit ultra-violet light and three types of fluorescent particle may be used to enable the lamp to emit white light: a particle that converts ultra-violet light to red light, a particle that converts ultra-violet light to blue light, and a particle that converts ultra-violet light to green light. 
     Further, the lamp may be configured to emit white light by using three types of LED elements: a first type emitting red light, a second type emitting green light, and a third type emitting blue light, and by mixing the three colors emitted by the three types of LED elements. Note that the color of light emitted from the LED module is of course not limited to white, and according to the purpose of the lamp, a variety of LEDs (including LED elements and surface-mounted LEDs) and fluorescent particles may be used. 
     (2) Mounting Board 
     In the above embodiment, an explanation is given of an example in which the mounting board has a rectangular shape in plan view. However, the shape of the mounting board in plan view is not specifically limited in this way. For example, in plan view the mounting board may have a circular shape, an elliptical shape, a polygonal shape, etc. 
     Also, in the above embodiment, an explanation is given of an example mounting board which is a board having a small thickness (an area of a side surface is smaller than an area of an upper surface). However, for example, the mounting board may be a board having a large thickness or a block shape. 
     Note that regardless of the shape, thickness, and form of the mounting board, the mounting board in the present specification indicates a mount on which the LEDs (including LED elements and surface-mounted LEDs) are mounted, and that has a pattern that is electrically connected to the LEDs. Accordingly, the mounting board may have the block shape mentioned above, or may be the mounting board and the extension member pertaining to the embodiment configured as a single body. 
     In the above embodiment, the mounting board is formed from light-transmissive material, but in a case where emitting light backward, in the base direction, is not required the mounting board may be formed from material other than light-transmissive material. 
     (3) Attachment position 
     The LED module in the above embodiment has a mounting board formed from a light-transmissive material in order to irradiate light backward, in the base direction, but light may be irradiated backward, in the base direction, by other methods. 
     As another method, the mounting board may be formed from material that is not light-transmissive material, and the LEDs may be mounted on both main surfaces of the mounting board. As yet another method, the mounting board may be formed from material that is not light-transmissive material, the mounting board may have a spherical shape, a cube shape, etc. (for example, the mounting board may include six insulated boards joined in three-dimensions to form a cube shape), and the LEDs (including shell-type LEDs and surface-mounted LEDs) may be mounted on a surface of the mounting board. 
     (4) Light-Emitting Elements 
     In the above embodiment and modifications, LEDs are used as the light-emitting elements, but light-emitting elements other than LEDs may be used. As other light-emitting elements, for example, EL light-emitting elements (including organic and inorganic) or LD, etc., may be used, or a combination of such light-emitting elements, including LEDs, may be used. 
     4. Globe 
     (1) Form 
     In the above embodiment, an A-type globe or R-type globe is used, but other types, such as B-type globes or G-type globes may be used, or globe shapes completely different from the bulb shapes of incandescent light bulbs and light-bulb shaped fluorescent lamps may be used. 
     Also, in the above embodiment, the globe is formed as a single body, but, for example, the globe may be a plurality of pieces that are produced separately and assembled as one globe. In such a case, every piece does not have to be made from the same material, and, for example, the globe may be a combination of pieces composed of resin and pieces composed of glass. Note that the use of a globe assembled from a plurality of pieces allows the use of an LED module that is larger than the opening at the lower end of the globe. 
     The globe may be light-transmissive such that the interior of the globe is visible, or may be semitransparent such that the interior of the globe is not visible. A semitransparent globe, for example, may be implemented by applying a diffusion layer having a primary component such as calcium carbonate, silica, white pigment, etc., to an inner surface of the globe, and applying a treatment for roughening an inner surface of the globe (for example, a blast treatment). 
     (2) Size 
     In the above embodiment, an explanation is not specifically given of a ratio of a length of the globe to a total length of the lamp. Here, a globe ratio means a total length of the globe relative to the total length of the lamp. The total length of the globe is a length of the central axis of a portion of the globe that is exposed to outside air. 
     The globe ratio is preferably equal to or greater than 0.54. If the globe ratio is less than 0.54, a surface area of the portion of the globe that is exposed to outside air is small, and a sufficient heat dissipation characteristic of the globe cannot be obtained. Also, if the globe size is decreased, the distance between the LED module and the circuit unit is decreased, and when the lamp is lit, heat received by the circuit unit from the LED module is increased, affecting the circuit unit. 
     (3) Material 
     In the above embodiment, a glass material is used as the material of the globe, but other light-transmissive materials, for example a resin material, may be used. 
     5. Case 
     In the above embodiment, the envelope that includes the globe and the case has a shape similar to an incandescent light bulb, but the envelope may have other shapes. Also, in the above embodiment explanation was not specifically given regarding an outer surface of the case, but, for example, in order to increase an envelope volume of the case, heat dissipation grooves and heat dissipation fins may be provided on the outer surface of the case. 
     6. Envelope 
     In the above embodiment, a particular treatment is not applied to the outer circumferential surface of the envelope that includes the globe and the case. However, coating material having a desired function may be applied to all or part of the outer circumferential surface of the envelope. Examples of such functions include a shatter prevention function, an ultraviolet light shielding function, an anti-fogging function, etc. 
     A shatter prevention function prevents scattering of fragments of the envelope if the envelope is damaged for any reason. As the coating material, for example, urethane resin and silicone resin, etc., may be used. Note that the coating material having a shatter prevention function may be applied to the globe only (a part of the envelope). 
     An ultraviolet light shielding function prevents exposure of the envelope to ultraviolet light, and thus prevents changes in color and reduction in strength of the envelope. As the coating material having the ultraviolet light shielding function, for example, polyolefin-type resin, etc., may be used. 
     An anti-fogging function prevents fogging of primarily the globe (a part of the envelope) when the lamp is used in a high humidity ambient atmosphere. As the coating material having the anti-fogging function, for example, acrylic resin, etc., may be used. 
     7. Base 
     In the above embodiment, an Edison-type base is used, but other types of bases, for example pin-type bases (specifically, G-type bases such as GY and GX) may be used. 
     Also, in the above embodiment, the base is attached to the case by a female thread of the shell portion of the base being screwed into the male thread of the case, but the base may be attached to the case by another method. As another method, attaching by adhesive, attaching by caulking, attaching by pressure, etc., or attaching by a combination of two or more of the above methods is possible. 
     8. LED position 
     In the present embodiment, the position of the LEDs inside the globe corresponds to the position of a filament of an incandescent light bulb. Specifically, the globe has a shape similar to an incandescent light bulb (A-type), and has a spherical portion and a cylindrical portion. Further, the LEDs (the LED module) are, if the globe shape corresponds to an A-type incandescent light bulb, arranged in a central position of the spherical portion. 
     The position described above is a position relative to the globe and is the central position of the spherical portion. However, from the base, the distance from an end tip of the base (an end tip of the eyelet portion) to the position of the LEDs is substantially the same as the distance from an end tip of a base of an incandescent light bulb to a filament of the incandescent light bulb. 
     However, the structure of the present invention is not limited to a globe that has an A-type shape as described above. For example, the globe may have a cylindrical shape that is closed at an end portion opposite the base. In such a case, the LEDs may be positioned at a focal point of a reflector of a lighting apparatus to which the lamp is attached, or a light-emission center of a lamp that the lamp is replacing (for example, a krypton bulb, a fluorescent bulb-type lamp, etc.). 
     9. Lighting Device 
     In the above embodiment and elsewhere, explanation is primarily given of the LED lamp, but the following is an explanation of a lighting device that uses the LED lamp. In other words, the present lighting device includes at least one of the varieties of the lamp described above and a lighting apparatus that attaches and lights up the lamp. 
     In the LED lamp explained under the heading Background Art (hereafter, “conventional LED lamp”), the case is used as a heat dissipation part, and therefore the case is large. In such a case, the LEDs are farther from the base than a filament is from a base in an incandescent light bulb. In other words, the position of the LEDs in the conventional LED lamp seen as a whole (distance from the base) is different from the position of the filament in an incandescent lamp seen as a whole (distance from the base). 
     When the conventional LED lamp is used with a reflector that is included in a lighting apparatus that an incandescent light bulb was attached to, for example when using the conventional LED lamp as a downlight, problems occur such as an annular shadow on a surface irradiated by the conventional LED lamp. In other words, due to differences in light source position between the conventional LED lamp and a conventional incandescent light bulb, problems occur with light distribution characteristics, etc. 
       FIG. 11  is a schematic view of a lighting device  201  pertaining to another embodiment. 
     The lighting device  201  is used, for example, while attached to a ceiling  202 . 
     As shown in  FIG. 11 , the lighting device  201  includes the LED lamp  1  and a lighting apparatus  203  to which the LED lamp  1  is attached. The lighting apparatus  203  lights up and turns off the LED lamp  1 . 
     The lighting apparatus  203  includes, for example, an equipment main body  205  that is attached to the ceiling  202  and a cover  207  that is attached to the equipment main body  205  and covers the LED lamp  1 . The cover  207  in the present example is an open-type cover that has a reflection film  211  on an inner surface thereof. The reflection film  211  reflects light emitted from the LED lamp  1  in a predetermined direction (downward, in the present example). 
     The equipment main body  205  includes a socket  209  to which the base  11  of the LED lamp  1  is attached (screwed into). Electricity is supplied to the LED lamp  1  via the socket  209 . 
     In the present example, since the position of the LEDs  3  (the LED module  5 ) of the LED lamp  1 , which is attached to the lighting apparatus  203 , is similar to the position of a filament of an incandescent light bulb, a light-emission center of the LED lamp  1  is positioned similarly to a light-emission center of the incandescent light bulb. 
     Thus, even when the LED lamp  1  is attached to the lighting apparatus  203 , to which the incandescent light bulb was attached, since the position of the light-emission center of the LED lamp  1  and the incandescent light bulb is similar, problems such as an annular shadow on a surface irradiated by the LED lamp  1  are less likely to occur. 
     Note that the above-described lighting apparatus is one example, and the lighting apparatus  203  may, for instance, not have the cover  207 , which is an open type, and instead have a closed type cover. The lighting apparatus  203  may also orientate the LED lamp  1  sideways (an orientation where the central axis of the lamp is horizontal), or obliquely (an orientation where the central axis of the lamp is oblique, relative to the central axis of the lighting apparatus), and light up the LED lamp  1 . 
     Also, the lighting device in the present example includes the lighting apparatus  203  that is a direct attachment type that, in a state of contact with a ceiling or wall, is attached to the ceiling or the wall. However, the lighting apparatus  203  may be an embedded type that, in a state of being embedded in a ceiling or wall, is attached to the ceiling or the wall, or the lighting apparatus  203  may be a suspended type that is suspended from a ceiling by an electric cable of the lighting apparatus  203 . 
     Furthermore, in the present example, the lighting apparatus lights up one LED lamp (the LED lamp  1 ) that is attached thereto, but the lighting apparatus may light up a plurality, for example three, LED lamps attached thereto. 
     INDUSTRIAL APPLICABILITY 
     The present invention provides an LED lamp that has a simple structure and that is easy to assemble. 
     REFERENCE SIGNS LIST 
     
         
           1  LED lamp 
           3  LEDs 
           5  LED module 
           7  globe 
           9  case 
           11  base 
           13  mount 
           13   a  cylinder portion 
           13   b  cover portion 
           15  extension member 
           17  circuit unit 
           19  insulation member 
           19   a  bottomed cylinder portion 
           19   b  flange portion 
           101  protrusion portion