Abstract:
A lamp light source comprises: a light-emitting unit having a plurality of semiconductor light-emitting elements arranged as a ring on a front face of a mount so as to principally emit light in a frontal direction; and a circuit unit converting externally-supplied electrical power to cause the semiconductor light-emitting elements to emit the light, wherein a through-hole passes vertically through the light-emitting unit at a point inside the ring of semiconductor light-emitting elements, the circuit unit is at least partly arranged within the through-hole, and a space is provided between the circuit unit and the light-emitting unit.

Description:
TECHNICAL FIELD 
     The present invention relates to a lamp light source using a semiconductor light-emitting element, and particularly relates to miniaturization of a case containing a circuit unit in such a lamp light source. 
     BACKGROUND ART 
     In recent years, light bulb-type lamp light sources using a semiconductor light-emitting element such as an LED (Light Emitting Diode) have become a widespread replacement for incandescent light bulbs. 
     Such lamp light sources typically feature a number of LEDs mounted on a single mounting substrate while a circuit unit for lighting the LEDs is held in the internal space of a case between the back of the mounting substrate and a base. The light produced by the LEDs radiates outward through a globe (see Patent Literature 1). 
     Also, the case is formed of a metal having thermoconductive properties and thus transmits heat produced by the LEDs to the base. The case is typically made so as not to accumulate heat (see page 12 of Non-Patent Literature 1) 
     CITATION LIST 
     Patent Literature 
     [Patent Literature 1] 
     
         
         
           
             Japanese Patent Application Publication 2006-313717
 
[Non-Patent Literature]
 
[Non-Patent Literature 1]
 
           
         
       
    
     “2010 Lamp Catalogue”, Publisher: Panasonic Corporation Lighting Company et al. 
     SUMMARY OF INVENTION 
     Technical Problem 
     Conventionally, a lamp light source using a semiconductor light-emitting element requires the case to be large enough to accommodate a circuit unit therein. 
     The size and dimensions of the lamp thus differ from those of an incandescent light bulb, and as such, the lamp is not always appropriate for mounting in a conventional light fixture intended for an incandescent bulb. 
     Therefore, demand is growing for a semiconductor light-emitting element-using lamp light source that more closely approximates the size and dimensions of a conventional incandescent bulb be developed by making the case smaller. 
     However, miniaturizing the case implies a decrease in distance between the semiconductor light-emitting module, i.e., the heat source, and the circuit unit. As a result, the circuit unit is easily affected by the heat from the semiconductor light-emitting module, and the heat produced by the circuit unit itself is not easily dissipated. This leads to a problem in that the heat load imposed on the circuit unit is increased. The electronic components making up the circuit unit include components having a useable life that is dramatically influenced by heat. Therefore, there is a need to constrain increases to the heat load imposed on the circuit unit in order to guarantee a long useable life therefor. 
     Therefore, the present invention aims to provide a lamp light source configured such that the circuit unit and the semiconductor light-emitting module are in proximity but the heat transmitted to the circuit unit from the semiconductor light-emitting module is constrained. 
     Solution to Problem 
     In order to achieve the above-stated aim, one aspect of the present invention provides a lamp light source, comprising: a light-emitting unit having a plurality of semiconductor light-emitting elements arranged as a ring on a front face of a mount so as to principally emit light in a frontal direction; a circuit unit converting externally-supplied electrical power to cause the semiconductor light-emitting elements to emit the light; a globe that is diffusive and transmittant, disposed so as to cover a front side of the light-emitting unit; an envelope that includes a base receiving the externally-supplied electrical power for causing the semiconductor light-emitting elements to emit the light; and a support member arranged at a distance from the light-emitting unit and supporting the circuit unit in relation to the envelope, wherein a through-hole passes vertically through the light-emitting unit at a point inside the ring of semiconductor light-emitting elements, the circuit unit is at least partly arranged within the through-hole, a space is provided between the circuit unit and the light-emitting unit, and the support member forms at least part of a heat transmission pathway from the circuit unit to the base, the support member thermally connecting the circuit unit and the base. 
     Advantageous Effects of Invention 
     The lamp light source pertaining to one aspect of the present invention has the circuit unit disposed at least partly in the through-hole within the light-emitting unit. This enables miniaturization of the case and, through the accompanying provision of a space between the light-emitting unit and the circuit unit, constrains heat transmission from the light-emitting unit to the circuit holder while constraining increases to the heat load imposed on the circuit unit in order to guarantee a long useable life therefor. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to Embodiment 1. 
         FIG. 2  is a partial-cutaway perspective view diagram illustrating the overall configuration of the lamp light source pertaining to Embodiment 1. 
         FIG. 3  is a magnified view of portion A in  FIG. 1 . 
         FIG. 4  is a plane-view diagram of a semiconductor light-emitting module pertaining to Embodiment 1. 
         FIG. 5  is a cross-sectional diagram of a beam splitter pertaining to Embodiment 1. 
         FIG. 6  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to Embodiment 2. 
         FIG. 7  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a first variation. 
         FIG. 8  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a second variation. 
         FIG. 9  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a third variation. 
         FIG. 10  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a fourth variation. 
         FIG. 11  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a fifth variation. 
         FIG. 12  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a sixth variation. 
         FIG. 13  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a seventh variation. 
         FIG. 14  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to an eighth variation. 
         FIG. 15  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a ninth variation. 
         FIG. 16  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a tenth variation. 
         FIG. 17  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to an eleventh variation. 
         FIG. 18A  is a plane view of a semiconductor light-emitting module pertaining to a twelfth variation,  FIG. 18B  is a plane view of a semiconductor light-emitting module pertaining to a thirteenth variation,  FIG. 18C  is a plane view of a semiconductor light-emitting module pertaining to a fourteenth variation, and  FIG. 18D  is a plane view of a semiconductor light-emitting module pertaining to a fifteenth variation. 
         FIG. 19  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a sixteenth variation. 
         FIG. 20  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a seventeenth variation. 
         FIG. 21  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to an eighteenth variation. 
         FIG. 22  is a magnified view of portion B in  FIG. 21 . 
         FIG. 23  is a magnified view of portion C in  FIG. 21 . 
         FIG. 24  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a twenty-second variation. 
         FIG. 25  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to a twenty-third variation. 
         FIG. 26A  is a magnified view corresponding to portion D in  FIG. 3 , pertaining to a twenty-fourth variation of the lamp light source from  FIG. 3 , and  FIG. 26B  is a magnified view corresponding to portion D in  FIG. 3  pertaining to a twenty-fifth variation of the lamp light source from  FIG. 3 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A light source for a lamp pertaining to the present invention is described below, with reference to the accompanying drawings. 
     The scale-sized components in the drawings do not conform to reality. In the Embodiments described below, the materials, values, and so on are described by means of examples, and no limitations are intended thereby. Further, appropriate modifications may be made to the present invention provided that these do not deviate from the technical concept of the present invention Further still, combination with elements of other Embodiments is possible, provided that no contradictions arise. 
     (Embodiment 1) 
     Overall Configuration 
       FIG. 1  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to Embodiment 1.  FIG. 2  is a partial-cutaway perspective view diagram illustrating the lamp light source pertaining to Embodiment 1.  FIG. 3  is a cross-sectional diagram showing a magnified view of section A, encircled by the double-dashed line in  FIG. 1 . In the drawings, the single-dashed line drawn along the vertical axis of the page represents lamp axis J within the lamp light source. The top of the page corresponds to the front of the lamp light source, while the bottom of the page corresponds to the back of the lamp light source. 
     As shown in  FIGS. 1 through 3 , the lamp light source  1  pertaining to Embodiment  1  is an LED lamp intended as a replacement for an incandescent bulb. The lamp light source  1  includes a semiconductor light-emitting module  10  serving as the light source, a mount  20  on which the semiconductor light-emitting module  10  is mounted, a globe  30  covering the semiconductor light-emitting module  10 , a circuit unit  40  for lighting the semiconductor light-emitting module  10 , a circuit holder  50  holding the circuit unit  40 , a case  60  covering the circuit holder  50 , a base  70  electrically connected to the circuit unit  40 , and a beam splitter  80  diffusing light emitted from the semiconductor light-emitting module  10 . The semiconductor light-emitting module  10  and the mount  20  form a light-emitting unit  90 . The globe  30 , the case  60 , and the base  70  form an envelope. 
     (Component Configuration) 
     (1) Semiconductor Light-Emitting Module 
       FIG. 4  is a plane-view diagram of the semiconductor light-emitting module pertaining to Embodiment 1. As shown, the semiconductor light-emitting module includes a mounting substrate  11 , semiconductor light-emitting elements  12  serving as the light source and mounted on the mounting substrate  11 , and sealers  13  provided on the mounting substrate  11  so as to encapsulate the semiconductor light-emitting elements  12 . In the present Embodiment, the semiconductor light-emitting elements  12  are LEDs, as the semiconductor light-emitting module  10  is an LED module. However, the semiconductor light-emitting elements  12  may alternatively be LD (laser diodes) or EL elements (electroluminescent elements). 
     The mounting substrate  11  is made up of an element mounting portion  15 , which is annular and has a substantially circular hole  14  in the middle, and a tongue portion  16 , which extends from one part of the inner edge of the element mounting portion  15  toward the middle of the hole  14 . A connector  17  is provided on the top face of the tongue portion  16 , and is connected to a wire  41  of the circuit unit  40 . The semiconductor light-emitting module  10  and the circuit unit  40  are electrically connected through the connection of the wire  41  to the connector  17 . While  FIG. 4  indicates that the connector  17  is provided on the top face of the tongue portion  16 , no limitation is intended. When the mounting substrate  11  is made of a non-conducting material, such as ceramic, the connector  17  may be provided on the back face of the tongue portion  16 . 
     The element mounting portion  15  has, for example,  32  semiconductor light-emitting elements  12  mounted thereon, arranged as a ring on the surface. Specifically, the semiconductor light-emitting elements  12  are combined into pairs, each pair being aligned radially with respect to the element mounting portion  15 , and the  16  pairs being arranged along the circumferential direction of the element mounting portion  15  at equal intervals so as to form a ring. The aforementioned ring is not necessarily limited to a circular ring, but is also intended to include other polygons, such as triangular, rectangular, or pentagonal shapes. Accordingly, the semiconductor light-emitting elements  12  may be mounted in a ring that is an oval or polygonal loop. 
     Each pair of the semiconductor light-emitting elements  12  is sealed by one of the sealers  13 , each of which is substantially rectangular. Accordingly, there are  16  sealers  13  in total. The longitudinal direction of each sealer  13  coincides with a radial direction of the element mounting portion  15 . When viewed from the front and aligned with the lamp axis J, the sealers appear to be radiating out from lamp axis J. 
     The sealers  13  are primarily made of a translucent material. However, when the wavelength of the light emitted by the semiconductor light-emitting element  12  is to be converted to a predetermined wavelength, the translucent material may be made to include wavelength converting material performing such a conversion. Silicone resin or the like may be used as the translucent material, while fluorescent particles or the like may be used as the wavelength converting material. 
     In the present Embodiment, semiconductor light-emitting elements  12  emitting blue light are used in combination with sealers  13  made of a translucent material having fluorescent particles mixed therein that convert blue light into yellow light. Thus, the blue light emitted by the semiconductor light-emitting elements  12  is partly converted into yellow light by the sealers  13 , such that the semiconductor light-emitting module  10  emits white light generated by the combination of unconverted blue light with converted yellow light. 
     Furthermore, the semiconductor light-emitting module  10  may, for example, use semiconductor light-emitting elements producing ultraviolet light in combination with fluorescent particles converting the light produced thereby into three colours (e.g., red, green, and blue). Further still, the wavelength converting material may be any material, such as a semiconductor, a metal compound, an organic dye, or a pigment, capable of absorbing light of a particular wavelength and emitting light of a different wavelength. 
     The semiconductor light-emitting elements  12  are arranged such that the principal direction of light emission is forward, i.e., along the lamp axis J. 
     (2) Mount 
     Again, as shown in  FIG. 1 , the mount  20  is, for example, substantially tubular and has a substantially cylindrical through-hole  21 . The tubular axis is oriented so as to match the lamp axis J. Accordingly, as shown in  FIG. 3 , the through-hole  21  passes through the mount  20 , from a front face  22  to a back face  23  thereof, each face being substantially annular in the plane. The semiconductor light-emitting module  10  is mounted on the front face  22  of the mount  20 , and is disposed flatly such that the principal direction of light emission of each semiconductor light-emitting element  12  is oriented forward. The mounting of the semiconductor light-emitting module  10  on the mount  20  may be achieved by various means, such as through the use of screws, adhesive, or engagement. 
     The front face  22  is not limited to being substantially annular, but may have any shape. Similarly, the front face  22  need not necessarily be completely flat, provided that the semiconductor light-emitting elements can be arranged flatly thereon. The same applies to the back face  23 . 
     The mount  20  is, for example, made of a metallic material. The metal in question may be Al, Ag, Au, Ni, Rh, Pd, an alloy combining two or more of these metals, or an alloy of Cu and Ag. Such a metallic material has advantageous thermal conductivity, and is thus able to effectively conduct the heat produced by the semiconductor light-emitting module  10  to the case  60 . 
     The through-hole  21  enables miniaturization, which is achieved by arranging part of the circuit unit  40  in the through-hole  21  and in the globe  30 , passing through the through-hole  21 . In addition, the through-hole  21  provided in the mount  20  serves to reduce the weight of the lamp light source  1 . 
     (3) Globe 
     Again, as shown in  FIG. 1 , in the present Embodiment, the globe  30  is shaped so as to resemble the bulb of a ball-shaped Japanese type G light bulb. An open edge  31  of the globe  30  is fixed to the mount  20  and to the case  60 . The envelope of the lamp light source  1  is formed by the globe  30 , the case  60 , and the base  70 . The shape of the globe  30  is not limited to resembling the aforementioned G-type bulb, but may have any desired shape. Furthermore, the lamp light source need not have a globe at all. 
     The globe  30  has an inner face  32  that diffuses the light emitted by the semiconductor light-emitting module  10 . For example, the inner face  32  may be treated with silica or with a white pigment so as to achieve light diffusion. Light incident on the inner face  32  of the globe  30  passes through the globe  30  and reaches the outside atmosphere. 
     (4) Circuit Unit 
     The circuit unit  40  lights the semiconductor light-emitting element  12 , and includes a circuit substrate  42  having electronic components  43 ,  44 , and  47  mounted thereon. The drawings show only a subset of electronic components with reference signs. The circuit unit  40  is held in the circuit holder  50  and affixed thereto by, for example, the use of screws, adhesive, engagement, and so on. 
     The circuit substrate  42  is oriented such that a principal surface thereof is substantially perpendicular to lamp axis J and affixed to an inner bottom surface of a lid  58  of the later-described circuit holder  50  by adhesive or similar. Accordingly, the circuit unit  40  is compactly held in the circuit holder  50 . Also, the circuit unit  40  is arranged such that heat-sensitive electronic components  43  is positioned far from the semiconductor light-emitting module  10  while heat-resistive electronic component  44  is positioned close to the semiconductor light-emitting module  10 . Accordingly, heat-sensitive electronic component  43  is less susceptible to heat damage from the heat produced by the semiconductor light-emitting module  10 . 
     The circuit unit  40  and the base  70  are electrically connected through electric wires  45  and  46 . Electric wire  45  passes a through-hole  51  provided in the circuit holder  50  and is connected to a shell portion  71  of the base  70 . Similarly, the electric wire  46  passes through a rear opening  54  of the circuit holder  50  and is connected to an eyelet portion  73  of the base  70 . 
     The circuit unit  40  is partly arranged in the through-hole  21  of the mount  20  and in the globe  30 . Accordingly, less space is required to accommodate the circuit unit  40 , which is farther back than the mount  20 . Thus, the distance between the mount  20  and the base  70  is decreased, enabling a reduction in the diameter of the case  60 , which is advantageous for miniaturizing the lamp light source  1 . The portion of the circuit unit  40  may be held only in the through-hole  21  without reaching the interior of the globe  30 . In such circumstances, the space for accommodating the circuit unit  40  behind the mount  20  may be correspondingly reduced. 
     (5) Circuit Holder 
     The circuit holder  50  is made up of a large-diameter portion  52 , a small-diameter portion  53 , and the lid  58 . The large-diameter portion  52  and the small-diameter portion  53  are, for example, substantially cylindrical with an opening at each end, connected and oriented so as to have a common axis that coincides with the lamp axis J to form a single unit. The large-diameter portion  52  is positioned toward the front and contains a large part of the circuit unit  40 . In contrast, the small-diameter portion  53  is positioned toward the back and has the base  70  fit thereon, thus closing the rear opening  54  of the circuit holder  50 . 
     The lid  58  is, for example, shaped as a bottomed cylinder or as a cap, is held by the large-diameter portion  52 , via the beam splitter  80 , such that a bottom of the lid is oriented toward the front of the large-diameter portion  52 , and thereby closes the openings of the large-diameter portion  52  and of the beam splitter  80 . 
     The circuit holder  50  has a through-hole  56  provided at a position corresponding to that of the tongue portion  16  of the semiconductor light-emitting module  10 . The front edge of the tongue portion  16  is inserted into the circuit holder  50  through the through-hole  56 , such that the connector  17  provided on the tongue portion  16  comes to be positioned in the circuit holder  50 . 
     The circuit holder  50  may be formed of resin or of a similar insulating material. Also, the lid  58  is not limited to being shaped as a bottomed cylinder or cap. The lid  58  may, for example, be a cone, polygonal prism or pyramid, or any desired shape provided that the light from the semiconductor light-emitting module  10  is not obstructed thereby upon passing through the beam splitter  80 . 
     (6) Case 
     The case  60  is, for example, shaped as a round tube open at both ends, having a diameter that decreases toward the back, or is shaped as a bowl with an opening at the bottom thereof. As shown in  FIG. 3 , the mount  20  and the open edge  31  of the globe  30  are accommodated in a forward edge portion  62  of the case  60 . The case  60 , the mount  20 , and the globe  30  are fixed as a single unit by, for example, using an adhesive introduced in space  63  (an installation groove) surrounded by the aforementioned components. 
     The outer circumferential surface of a rear edge portion of the mount  20  is tapered to match the inner circumferential of the case  60 . Thus, a tapered face  25  is in surface contact with an inner face  64  of the case  60  and transmits heat from the semiconductor light-emitting module  10  to the mount  20 . This also causes heat to be more easily transmitted to the case  60 . The heat produced by the semiconductor light-emitting elements  12  is mainly transmitted through the mount  20  and the case  60  to the small-diameter portion  53  of the circuit holder  50  to reach the base  70 , before being dissipated by the base  70  to a non-diagrammed light fixture. 
     The tapered face  25  completely matches the inner face  64  of the case  60 . As such, the tapered face  25  and the inner face  64  of the case  60  are combined in cohesive, gapless contact. Accordingly, the light from the semiconductor light-emitting module  10  does not escape into a gap  61 . Alternatively, the tapered face  25  and the inner face  64  of the case  60  may be joined by a non-transparent adhesive or the like, so as to secure the cohesiveness between the two components. 
     The case  60  is, for example, made of a metallic material. The metal in question may be Al, Ag, Au, Ni, Rh, Pd, an alloy combining two or more of these metals, or an alloy of Cu and Ag. Given that such a metallic material is suited to thermal conduction, the heat transmitted by the case  60  is effectively transmitted toward the base  70 . 
     (7) Base 
     When the lamp light source  1  is affixed to a light fixture and lit, the base  70  serves to receive electric power from a socket of the light fixture. In the present Embodiment, an E26 Edison screw base is used. However, no limitation is intended regarding the type of base  70  employed. The base  70  is substantially cylindrical and includes a shell portion  71  formed as a male screw along the outer circumferential surface of the base  70  as well as an eyelet portion  73  mounted to the shell portion  71  through an insulating member  72 . An insulating member  74  is introduced between the shell portion  71  and the case  60 . 
     (8) Beam Splitter 
       FIG. 5  is a cross-sectional diagram of a beam splitter pertaining to Embodiment 1. As shown, the beam splitter  80  is, for example, a bottomed cylinder that includes a main body  81 , which is substantially tubular and open at both ends, and an attaching portion  82 , which is substantially annular and closes a rear opening of the main body  81 . The beam splitter  80  is attached to the forward edge portion  57  of the circuit holder  50 . For example, in  FIG. 3 , the boundary between the main body  81  and the attaching portion  82  is marked by a double-chained line. 
     A back face  83  of the attaching portion  82  has a recess  84  that is substantially cylindrical and engages with a forward edge portion  57  of the large-diameter portion  52 . Fitting the forward edge portion  57  into the recess  84  positions the beam splitter  80  with respect to the large-diameter portion  52 . The beam splitter  80  is fixed to the large-diameter portion  52  in this position, through the use of an adhesive or similar. Shaping the forward edge portion  57  of the large-diameter portion  52  to match the recess  84  enables the beam splitter  80  to be appropriately positioned with respect to the semiconductor light-emitting elements  12  through the simple action of fitting the forward edge portion  57  in the recess  84 . 
     Similarly, the front face  85  of the attaching portion  82  is provided with a recess  86  that is substantially cylindrical and engages with a rear edge portion  59  of the lid  58  of the circuit holder  50 . The cap-shaped lid  58  is attached to the beam splitter  80  by fitting and fixing the rear edge portion  59  in the recess  86 . 
     The attaching portion  82  has a substantially round hole  87  provided at the approximate centre thereof. The gap in the circuit holder  50  and the gap in the lid  58  are in communication through the hole  87 . Accordingly, the part of the circuit unit  40  accommodated within the large-diameter portion  52  and the small-diameter portion  53  of the circuit holder  50  is also accommodated within the hole  87  and the lid  58 . Also, providing the hole  87  prevents the beam splitter  80  from interfering with the accommodation of the circuit unit  40 . 
     The beam splitter  80  is made of a translucent material. The translucent material is, for example, a polycarbonate or similar resin, glass, or ceramic. In addition, reflective processing is applied to an outer circumferential surface  88  of the main body  81 . The reflective processing may applied to the outer circumferential surface  88  using, for example, a reflective membrane such as a metallic thin-film or dielectric multilayer shaped using thermal evaporative deposition, electron beam evaporation deposition, sputtering, plating, or similar methods. 
     As shown in  FIG. 1 , the main body  81  is substantially tubular, having a diameter that is smallest at the back and gradually increases toward the front. When the front is viewed from the back along lamp axis J, the outer circumferential surface  88  of the main body  81  appears annular. When the main body  81  is oriented such that a tubular axis thereof is perpendicular to the front face  22  of the mount  20 , the main body  81  is separated from the semiconductor light-emitting module  10  and arranged in front of the semiconductor light-emitting elements  12 . The front of the semiconductor light-emitting elements  12 , which are arranged as a ring, is thus covered by the annular outer circumferential surface  88 . As such, the semiconductor light-emitting elements  12  and the outer circumferential surface  88  are arranged opposite each other. That is, the principal direction of light emission for the semiconductor light-emitting elements  12  is toward the outer circumferential surface  88 , and the outer circumferential surface  88  serves as a light-receiving surface for the beam splitter  80 . 
     The light emitted from the semiconductor light-emitting module  10  and incident on the outer circumferential surface  88  of the main body  81  is partly reflected obliquely backward by the outer circumferential surface  88  so as to avoid the front face  22  of the mount  20 . The direction is indicated by optical path L 1  in  FIG. 3 . Also, another part of the light passes through the main body  81  and on toward the front, as indicated by optical path L 2  in  FIG. 3 . That is, the function of the beam splitter  80  is mainly utilized by the main body  81 . 
     The main body  81  is provided so as to reflect a part of the light emitted by the semiconductor light-emitting element  12  obliquely backward, avoiding the front face  22  of the mount  20 . Thus, the lamp light source  1  exhibits advantageous light distribution characteristics despite the narrow lighting angle of individual semiconductor light-emitting elements  12 . Further, given that the semiconductor light-emitting elements  12  are arranged in a ring and that the outer circumferential surface  88  is correspondingly annular, the light reflected obliquely backward and avoiding the front face  22  of the mount  20  spreads over the entire exterior of the mount  20 . Accordingly, the light distribution characteristics are advantageous across the entire circumference centered on lamp axis J. 
     Further still, the main body  81  not only reflects a part of the light but also allows another part of the light to pass. The beam splitter  80  is thus highly unlikely to produce a shadow, which leads to an advantage in terms of design when the lit lamp light source  1  is viewed head-on. 
     As such, the provision of the beam splitter  80  allows the outgoing light from the semiconductor light-emitting module  10  to be diffused and, given that the light is unlikely to be obstructed by the lid  58 , allows the circuit unit  40  to be arranged farther ahead than the semiconductor light-emitting module  10 . This enables miniaturization of the case  60 , which accommodates these components. 
     In the present Embodiment, a reflective processing is applied to the outer circumferential surface  88  such that the beam splitter  80  has reflectivity on the order of 50% (for the outer circumferential surface  88 ), and transmittance on the order of 50% (for the outer circumferential surface  88 ). The reflectivity is desirably 50% or higher in order to maintain advantageous light distribution for the lamp light source  1 . Similarly, the transmittance is desirably 40% or higher in order to maintain an advantageous design for the lamp light source  1 . In brief, assuming 0% absorptance, the main body  81  desirably exhibits reflectivity ranging from 50% to 60% inclusive, and transmittance ranging from 40% to 50% inclusive. 
     The reflectivity and transmittance need not be uniform across the entirety of the outer circumferential surface  88 , but may be made to vary in different regions. For example, when less light is to be reflected toward the back and more light is to be reflected toward the sides, the reflectivity of the outer circumferential surface  88  may be increased at the back and decreased at the front. Conversely, when more light is to be reflected toward the back and less light is to be reflected toward the sides, the reflectivity of the outer circumferential surface  88  may be decreased at the back and increased at the front. 
     As shown in  FIG. 3 , the sealers  13  of the semiconductor light-emitting module  10  are directly under the main body  81  when viewed from the front along lamp axis J. The sealers  13  are entirely covered by the beam splitter  80 . A rear edge  89  (i.e., the edge nearest lamp axis J) of the outer circumferential surface  88  is arranged at the limit of the illuminatingle angle θ of the semiconductor light-emitting element  12  nearest lamp axis J, or closer to lamp axis J than the limit. According to this structure, emitted light is unlikely to enter the gap between the back face  83  of the beam splitter  80  and the semiconductor light-emitting module  10 , thereby preventing light loss. 
     The outer circumferential surface  88  of the main body  81  is shaped as a concave plane, having an inward concavity facing the tubular axis of the main body  81 . Specifically, as shown in  FIG. 1 , the outer circumferential surface  88  is substantially arc shaped, curving toward lamp axis J when seen in cross-section (i.e., a vertical cross-section) of the main body  81  taken along a virtual plane that includes lamp axis J (i.e., coincides with the tubular axis of the main body  81 ). In other words, the arc shape curves more toward the lamp axis J than toward a straight line in the vertical cross-section joining the rear edge  89  of the outer circumferential surface  88  to a front edge thereof 
     (Circuit Unit Heat Load Suppression) 
     As shown in  FIG. 1 , the large-diameter portion  52  of the circuit holder  50  passes through the through-hole  21  of the mount  20 , being disposed therein such that a part of the circuit unit  40  is accommodated within the circuit holder  50 . As shown in  FIG. 3 , the large-diameter portion  52  of the circuit holder  50  is not in contact with the mount  20 , resulting in gap (space)  27   a  therebetween. In other words, gap  27   a  is provided between the exterior  55  (outer circumferential surface) of the large-diameter portion  52  of the circuit holder  50  and the inner face  24  (inner face of the mount  20 ) of the through-hole  21  of the mount  20 . Width W 1  of gap  27   a , is given as measured perpendicularly with respect to lamp axis J, and is substantially uniform along the entirety of the circuit holder  50 . Providing gap  27   a  between the circuit holder  50  and the mount  20  in this way makes heat less likely to be transmitted from the mount  20  to the circuit holder  50 . Accordingly, the circuit holder  50  is less likely to reach high temperatures, and the circuit unit  40  is less likely to suffer heat damage. In order to suppress the transmission of heat from the mount  20  to the circuit holder  50 , W 1  should desirably be from 0.3 mm to 1 mm, inclusive. 
     The semiconductor light-emitting module  10  is not in contact with the large-diameter portion  52  of the circuit holder  50 . Gap (space)  27   b  is provided between the mounting substrate  11  of the semiconductor light-emitting module  10  and the large-diameter portion  52  of the circuit holder  50 . In other words, gap  27   b  is provided between the exterior  55  of the large-diameter portion  52  of the circuit holder  50  and the inner face  18  of the mounting substrate  11 . Width W 2  of gap  27   b  is given as measured perpendicularly with respect to lamp axis J, and is substantially uniform along the entirety of the large-diameter portion  52  of the circuit holder  50 , with the exception of the tongue portion  16 . Accordingly, the semiconductor light-emitting module  10  is less likely to transmit heat to the circuit holder  50 , the circuit holder  50  is less likely to reach high temperatures, and the circuit unit  40  is less likely to suffer heat damage. In order to suppress the transmission of heat from the semiconductor light-emitting module  10  to the circuit holder  50 , W 2  should desirably be from 0.3 mm to 1 mm, inclusive. 
     In the present Embodiment, the front face  22  of the mount  20  and the back face of the element mounting portion  15  have substantially identical shapes. Also, the semiconductor light-emitting module  10  is positioned such that the front face  22  of the mount  20  and the back face of the element mounting portion  15  fit. As such, W 1  and W 2  are substantially equal. The gaps  27   a  and  27   b  form a single, undivided gap (space)  27 . Given that the front face  22  of the mount  20  and the back face of the element mounting portion  15  have substantially identical shapes, the semiconductor light-emitting module  10  is easy to position with respect to the mount  20 , and W 2  can be made uniform along the entire circumference of the circuit holder  50 . 
     As described above, gap  27   a  is provided between the circuit holder  50  and the mount  20  while gap  27   b  is provided between the circuit holder  50  and the semiconductor light-emitting module  10 . That is, gap  27  is provided between the circuit holder  50  and the light-emitting unit  90 . As such, transmission of heat produced in the semiconductor light-emitting module  10  to the circuit holder  50  is suppressed, and the heat load on the circuit unit  40  is prevented from increasing. 
     Also, the heat produced by the electronic components making up the circuit unit  40 , i.e., the heat produced by the circuit unit  40  itself, is transmitted from the circuit substrate  42  to the lid  58  and the beam splitter  80 , then further transmitted to the large-diameter portion  52 , the small-diameter portion  53 , and the base  70 , to be ultimately dissipated by the base  70  to the lighting fixture in which the lamp light source  1  is installed, and to the wall, pillar, or other structure carrying the fixture. 
     Furthermore, as described above, gap  27  is provided between the circuit holder  50  and the light-emitting unit  90 . Thus, air easily circulates within the envelope formed by the globe  30 , the case  60 , and the base  70 . That is, space  33  in the globe  30  and space  61  behind the mount  20  in the case  60  allow air to circulate therethrough, thus making high local temperatures less likely to arise within the envelope. 
     Furthermore, given that the circuit unit  40  and the semiconductor light-emitting module  10  are arranged close together, the length of the wire  41  used to supply electric power from the circuit unit  40  to the semiconductor light-emitting module  10  can be reduced, thus effectuating reductions in material consumption and in production costs. 
     (Embodiment 2) 
     Embodiment 1 describes gap  27 , provided between the light-emitting unit  90  and the circuit holder  50  to suppress the transmission of heat produced in the semiconductor light-emitting module  10  to the circuit holder  50  and reduce the heat load on the circuit unit  40 . 
     However, the heat load imposed on the circuit unit  40  involves not only heat from the semiconductor light-emitting module  10  but also heat produced by the circuit unit  40  itself. In Embodiment 1, the heat produced by the circuit unit  40  is transmitted from the circuit substrate  42  to the lid  58 , the beam splitter  80 , the large-diameter portion  52 , the small-diameter portion  53 , and the base  70 , to be ultimately dissipated by the base  70  to the light fixture in which the lamp light source  1  is installed and to the wall, pillar, or similar supporting the fixture. Given that the circuit holder  50  forms part of the heat transmission pathway, the temperature of the circuit holder  50  may rise, in turn causing the air in the circuit holder  50  to rise in temperature and potentially causing an increase in the heat load imposed on the circuit unit  40 . Additionally, although the through-hole  56  enables the air inside and outside the circuit holder  50  to remain in communication, the through-hole  56  is only as large as needed for the tongue portion  16  to be inserted. Thus, the inside of the circuit holder  50  is almost hermetic and little air circulates between the inside and outside thereof. Therefore, air tends to stagnate within the circuit holder  50 . As a result, high local temperatures arise and may lead to an increased heat load being imposed on the circuit unit  40 . 
     The present Embodiment describes a configuration in which such high local temperatures within the circuit holder  50  are suppressed, thus constraining the heat load imposed on the circuit unit  40 . 
     In order to avoid redundant explanation, portions identical to Embodiment 1 are omitted or abbreviated below. Also, identical components use the same reference signs. 
       FIG. 6  is a cross-sectional diagram illustrating the overall configuration of a lamp light source pertaining to Embodiment 2. 
     A support base  76  formed of insulating resin material or the like is provided in the recess formed by the insulating member  72  and the eyelet portion  73  of the base  70  and fixed therein. The support base  76  supports two columnar support members  91 , which extend substantially parallel to lamp axis J. The circuit substrate  42  of the circuit unit  40  is fixed to the end of the support members  91  opposite the end supported by the support base  76  by means of an adhesive made of insulating material, such as resin. 
     The support members  91  are, for example, made of a metallic material. The metal in question may be Al, Ag, Au, Ni, Rh, Pd, an alloy combining two or more of these metals, or an alloy of Cu and Ag. The heat transmission characteristics of such metals enable the heat generated by the circuit unit  40  to be more efficiently transmitted to the base  70 . 
     Although the present Embodiment describes two support members  91 , no limitation is intended. A single support member may also be used, as may three or more support members. 
     In Embodiment 1, the large-diameter portion  52  and the small-diameter portion  53  of the circuit holder  50  (see  FIG. 1 ) form a single whole. However, as shown in  FIG. 6 , in Embodiment 2 a large-diameter portion  502  (corresponding to the large-diameter portion  52  of Embodiment 1) of a circuit holder  501  is separated from a tubular portion  503  (corresponding to the small-diameter portion  53  of Embodiment 1), and a gap  65   a  is provided between the two components. The lid  58  and the large-diameter portion  502  form a circuit holder main body. In the present Embodiment, the circuit holder  501  may be formed of resin or of a similar insulating material. 
     Also, when, for example, the lid  58  is not included, the circuit holder main body may be formed from the large-diameter portion  502  alone. 
     Furthermore, gap  65   b  is provided between the large-diameter portion  502  and the case  60 . Gap  65  is formed by the communicating gaps  65   a  and  65   b . Accordingly, the circuit holder main body (i.e., the large-diameter portion  502  and the lid  58 ) and the circuit unit  40  are supported by the support members  91  as a single whole, and are not connected to any components other than the wire  41  and the connector  17 . Therefore, not only is the direct transmission of heat from the semiconductor light-emitting module  10  to the circuit holder main body constrained, but so is the transmission of heat from the semiconductor light-emitting module  10  to the case  60  and the base  70  and on to the circuit holder main body. 
     The heat produced by the circuit unit  40  is then transmitted from the circuit substrate  42  through the support members  91  and the support base  76  to the base  70 , to be dissipated by the base  70  to a light fixture in which the lamp light source  100  is installed, and to the wall, pillar, or other structure carrying the fixture. 
     Also, the space in the circuit holder main body and the space in the tubular portion  503  are in communication with space  61  through gap  65  (see  FIG. 3 ). Space  61  is in communication with space  33  in the globe  30  through gap  27 . Accordingly, the spaces in the circuit holder main body and the tubular portion  503  are in communication with space  33  through gap  65 , space  61 , and gap  27 . As a result, air circulates through the gaps. 
     As described above, in the present Embodiment, gap  27  is provided between the light-emitting unit  90  and the circuit holder main body to suppress transmission of heat produced by the semiconductor light-emitting module  10  to the circuit holder main body, and the transmission of heat produced by the circuit unit  40  through the support members  91  to the base  70  is enabled. Also, the space in the circuit holder main body and the tubular portion  503  and space  33  in the globe  30  are in communication via gap  65 , space  61 , and gap  27 , thus encouraging air circulation. Thus, high local temperatures are prevented from arising in the space within the circuit holder main body and the tubular portion  503 , and an effective constraint is placed on the heat load imposed on the circuit unit  40 . 
     (Variations) 
     The following variations are also possible. In order to avoid redundant explanation, portions identical to Embodiments 1 and 2 are omitted or abbreviated below. Also, identical components use the same reference signs.
     (1) Embodiment 1 describes circuit substrate  42  as being fixed to the lid  58 . However, no limitation is intended. As shown in  FIG. 7 , the circuit substrate  42  may instead be fixed to the bottom face of the large-diameter portion  52  and to the front end of the small-diameter portion  53 . In such circumstances, gap  27  is still provided between the circuit holder  50  and the light-emitting unit  90 . Thus, the transmission of heat from the light-emitting unit  90  to the circuit holder  50  is suppressed and the heat load on the circuit unit  40  is prevented from increasing.   

     Further, heat-sensitive electronic components  43  may be arranged on the back face of the circuit substrate  42 , i.e., on the principal surface thereof farther from the semiconductor light-emitting module  10 . This constrains the effect of the heat produced by the semiconductor light-emitting module  10  on the electronic components  43 .
     (2) When, for example, in the first variation described above, the base  70  has a small diameter and the small-diameter portion  53  is not easily able to accommodate the electronic components  43 , then as shown in  FIG. 8 , the electronic components  43  may be arranged on the front face of the circuit substrate  42  along with other electronic components, i.e., arranged on the side closer to the semiconductor light-emitting module  10 . In such circumstances, gap  27  is still provided between the circuit holder  50  and the light-emitting unit  90 . Thus, the transmission of heat from the light-emitting unit  90  to the circuit holder  50  is suppressed and the heat load on the circuit unit  40  is prevented from increasing.   

     Also, the electronic components  43  may be arranged so as to be accommodated within the lid  58 . As such, the electronic components  43  are arranged as far away as possible from the semiconductor light-emitting module  10 , suppressing the effect of heat produced by the semiconductor light-emitting module  10  on the electronic components  43 .
     (3) In the Embodiments and variations described above, the circuit substrate  42  is oriented such that the principal surface thereof is substantially orthogonal to lamp axis J. However, no limitation is intended. For example, as shown in  FIG. 9 , the circuit substrate  42  may be oriented such that the principal surface thereof is oriented substantially parallel to lamp axis J. Accordingly, a small-diameter lamp light source  400  can nevertheless be made to compactly accommodate the circuit unit  40  in the circuit holder  50 . In such circumstances, the gap  27  is still provided between the circuit holder  50  and the light-emitting unit  90 . Thus, the transmission of heat from the light-emitting unit  90  to the circuit holder  50  is suppressed and the heat load on the circuit unit  40  is prevented from increasing. This variation is ideally applicable to a lamp light source shaped so as to resemble a typical Japanese type A light bulb, for example.   (4) In Embodiment 1 as described above, the heat produced by the circuit unit  40  is transmitted from the circuit substrate  42  through the circuit holder  50  and the beam splitter  80  to the base  70 . As such, the temperature of the circuit holder  50  and the space within increases, potentially leading to an increase in the heat load imposed on the circuit unit  40  contained in the circuit holder  50 . However, as shown in  FIG. 10 , the configuration of Embodiment 1 may be supplemented by providing support members  91 . These allow the heat produced by the circuit unit  40  to be transferred to the base  70 .   

     According to this variation, the heat produced by the circuit unit  40  is transferred in part as described in Embodiment 1, i.e., through the circuit holder  50  and the beam splitter  80  to the base  70 , while another part of the heat is instead transferred through the highly thermoconductive support members  91  to the base  70 . Therefore, temperature increases in the circuit holder  50  and in the space within are suppressed. This effectively prevents the heat load imposed on the circuit unit  40  from increasing. 
     In such circumstances, the gap  27  is still provided between the circuit holder  50  and the light-emitting unit  90 . Thus, the transmission of heat from the light-emitting unit  90  to the circuit holder  50  is suppressed and the heat load on the circuit unit  40  is prevented from increasing.
     (5) A further heat transmission pathway may be provided between the base  70  and electronic component  47 , which is the electronic component producing the most heat among those making up the circuit unit  40 , so as to transmit the heat produced by electronic component  47  directly to the base  70 . The electronic component  47  producing the most heat is, for example, a switching element or a transistor.   

     For example, as shown in in  FIG. 11 , a rope-like heat conducting member  92  may be fixed to the electronic component  47  at one end, while the other end thereof is fixed to the insulating member  72  of the base  70  using resin or a similar adhesive  77 . Accordingly, most of the large amount of heat produced by electronic component  47  is transmitted through the heat conducting member  92  to the base  70 . This enables suppression of heat transmission from electronic component  47  to the circuit substrate  42  and, as described in the fourth variation above, temperature increases in the circuit holder  50  and in the space within are suppressed. This effectively prevents the heat load imposed on the circuit unit  40  from increasing. 
     In such circumstances, gap  27  is still provided between the circuit holder  50  and the light-emitting unit  90 . Thus, the transmission of heat from the light-emitting unit  90  to the circuit holder  50  is suppressed and the heat load on the circuit unit  40  is prevented from increasing.
     (6) As shown in  FIG. 12 , the support members  91  of the fourth variation and the heat conducting member  92  of the fifth variation may be replaced by an insulating thermoconductive filling member  78 , which is made of resin or the like, solidly fills the space between the circuit unit  40  and the base  70 , and is thermally conductive.   

     In such circumstances, in order to prevent damage to the electronic components of the circuit unit  40  during the filling and hardening of the insulating thermoconductive filling member  78 , the insulating thermoconductive filling member  78  solidly fills a space defined by the back face of the circuit substrate  42 , the inner face of the small-diameter portion  53 , the inner face of the insulating member  72 , and the eyelet portion  73 , formed when, as shown, the circuit substrate  42  is fixed to the bottom face of the large-diameter portion  52  and to the front end of the small-diameter portion  53  and the electronic components are arranged on the front face of the circuit substrate  42 . 
     In this variation, gap  27  is still provided between the circuit holder  50  and the light-emitting unit  90 . Thus, the transmission of heat from the light-emitting unit  90  to the circuit holder  50  is suppressed, heat produced by the circuit unit  40  is transmitted through the insulating thermoconductive filling member  78  to the base  70 , and the heat load on the circuit unit  40  is prevented from increasing.
     (7) Embodiment 2 describes circuit substrate  42  as fixed to the lid  58 . However, as shown in  FIG. 13 , the circuit substrate  42  may also be fixed to the bottom face of the large-diameter portion  502 .   

     In such circumstances, gap  27  is still provided between the circuit holder  50  and the light-emitting unit  90 . Thus, the transmission of heat from the light-emitting unit  90  to the circuit holder  50  is suppressed, and the heat produced by the circuit unit  40  is transmitted through the support members  91  to the base  70 . Also, the space in the circuit holder main body and the tubular portion  503  and space  33  in the globe  30  are in communication via gap  65 , space  61 , and gap  27 , thus encouraging air circulation. Thus, high local temperatures are prevented from arising in the space within the circuit holder main body and the tubular portion  503 , and an effective constraint is placed on the heat load imposed on the circuit unit  40 . 
     Furthermore, heat-sensitive electronic component  43  may be arranged on the back face of the circuit substrate  42 , i.e., on the principal surface thereof farther from the semiconductor light-emitting module  10 . This constrains the effect of the heat produced by the semiconductor light-emitting module  10  on electronic component  43 .
     (8) When, for example, in the seventh variation described above, the base  70  has a small diameter and the small-diameter portion  53  is not easily able to accommodate electronic component  43 , then as shown in  FIG. 14 , electronic component  43  may be arranged on the front face of the circuit substrate  42  along with the other electronic components, i.e., arranged on the side closer to the semiconductor light-emitting module  70 .   

     In such circumstances, gap  27  is still provided between the circuit holder  50  and the light-emitting unit  90 . Thus, the transmission of heat from the light-emitting unit  90  to the circuit holder  50  is suppressed, and the heat produced by the circuit unit  40  is transmitted through the support members  91  to the base  70 . Also, the space in the circuit holder main body and the tubular portion  503  and space  33  in the globe  30  are in communication via gap  65 , space  61 , and gap  27 , thus encouraging air circulation. Thus, high local temperatures are prevented from arising in the space within the circuit holder main body and the tubular portion  503 , and an effective constraint is placed on the heat load imposed on the circuit unit  40 . 
     Also, electronic component  43  may be arranged so as to be contained within the lid  58 . As such, electronic component  43  is arranged as far away as possible from the semiconductor light-emitting module  10 , suppressing the effect of heat produced by the semiconductor light-emitting module  10  thereon.
     (9) In Embodiment 2, the circuit unit  40  is supported in relation to the base  70  by support members  91 , which form a heat transmission pathway from the circuit unit  40  to the base  70  and transmit the heat produced by the circuit unit  40  to the base  70  to be dissipated. However, as shown in  FIG. 15  and as described in the fifth variation, a further heat transmission pathway may be provided between the base  70  and electronic component  47 , which is the electronic component producing the most heat among those making up the circuit unit  40 , so as to transmit the heat produced by electronic component  47  directly to the base  70 .   

     In such circumstances, gap  27  is still provided between the circuit holder  50  and the light-emitting unit  90 . Thus, the transmission of heat from the light-emitting unit  90  to the circuit holder  50  is suppressed, and the heat produced by the circuit unit  40  is transmitted through the support members  91  to the base  70 . Also, the space in the circuit holder main body and the tubular portion  503  and space  33  in the globe  30  are in communication via gap  65 , space  61 , and gap  27 , thus encouraging air circulation. Thus, high local temperatures are prevented from arising in the space within the circuit holder main body and the tubular portion  503 , and an effective constraint is placed on the heat load imposed on the circuit unit  40 . 
     Accordingly, by providing the heat conducting member  92 , most of the large amount of heat produced by electronic component  47  is transmitted through the heat conducting member  92  to the base  70 . This enables suppression of heat transmission from electronic component  47  to the circuit substrate  42  and, as described in the eighth variation above, temperature increases in the circuit holder  50  and in the space within are suppressed. This effectively prevents the heat load imposed on the circuit unit  40  from increasing.
     (10) In the Embodiments and variations described above, the beam splitter  80  is sandwiched between the large-diameter portion  52  ( 502 ) of the circuit holder  50  ( 501 ) and the lid  58 . However, no limitation is intended. For example, as shown in  FIG. 16 , a beam splitter  180  may be fixed by an adhesive not to a circuit holder  150  but rather to a mounting substrate  111  of a semiconductor light-emitting module  110 .   

     Accordingly, the heat received by a light-receiving surface (outer circumferential surface)  188  of the beam splitter  180  from the semiconductor light-emitting module  110  is not transmitted to the circuit holder  150 . Thus, the heat load imposed on the circuit unit  40  is suppressed. 
     Also,  FIG. 16  illustrates a variation in which the configuration of the beam splitter  180  is applied to the third variation as illustrated by  FIG. 9 , when appropriate.
     (11) Further still, as shown in  FIG. 17 , a beam splitter  280  may be fixed to a globe  230  rather than to the mounting substrate  111 .   

     Also,  FIG. 17  illustrates a variation in which the configuration of the beam splitter  280  is applied to the third variation as illustrated by  FIG. 9 , when appropriate. 
     The globe  230  is made up of a front member  231  and a rear member  232 , divided along a virtual plane that is orthogonal to lamp axis J and divides the globe  230 . The front member  231  and the rear member  232  are combined to form a lamp light source shaped so as to resemble a typical Japanese type A light bulb. A rear edge portion  233  of the rear member  232  is accommodated in the forward edge portion  62  of the case  60 . The case  60 , the mount  20 , and the rear member  232  are fixed so as to form a single whole by introducing adhesive or similar. The front end of the rear member  232  is attached to the front member  231 . 
     The beam splitter  280  is, for example, shaped like the beam splitter  80  pertaining to Embodiment 1 but modified so as to be substantially tubular, with the forward edge portion of the main body  81  extending away from lamp axis J, and as described in Embodiment 2, is not fixed to the mounting substrate  111  but rather has a forward edge portion  289  fixed to the rear member  232  of the globe  230 . Specifically, an engagement groove  235  is provided in the forward edge portion  234  of the rear member  232  for engaging with the forward edge portion  289  of the main body  281 . The engagement groove engages with the forward edge portion  289  to achieve fixing. When the forward edge portion  289  is engaged with the engagement groove  235 , adhesive or similar may be used to form an adhesive bond between a forward edge portion  234  and another forward edge portion  289 . The globe  230  also has an inner face that diffuses the light emitted by the semiconductor light-emitting module  10 . For example, the inner face may be treated with silica or with a white pigment so as to achieve light diffusion. 
     According to this variation as described above, the beam splitter  280  is not in contact with the semiconductor light-emitting module  110  or with the circuit holder  150 . Accordingly, the heat produced by the semiconductor light-emitting module  110  is unlikely to be transmitted to the beam splitter  280  and even less likely to be transmitted through the beam splitter  280  to the circuit holder  150 . Thus, the heat load imposed on the circuit unit  40  is effectively suppressed.
     (12) In the above-described Embodiments and variations, the semiconductor light-emitting elements  12  are arranged in pairs, each sealed by a substantially rectangular sealer  13 , the longitudinal direction of each sealer  13  coincides with a radial direction of the element mounting portion  15 , and the sealers appear to be radiating from the central lamp axis J when viewed from the front along lamp axis J. However, no limitation is intended.   

     For example, as indicated by a semiconductor light-emitting module  510  shown in  FIG. 18A , sealers  513  may also be oriented on an element mounting portion  515  of a mounting substrate  511  such that the longitudinal direction of the sealers  513  is aligned with the circumferential direction of the element mounting portion  515 . A plurality of semiconductor light-emitting elements  512  are arranged on the element mounting portion  515  of the mounting substrate  511  and aligned the circumferential direction of the element mounting portion  515 , the sealers  513  each seal one pair of the semiconductor light-emitting elements  512 , and the longitudinal direction of the sealers  513  is aligned with the circumferential direction of the element mounting portion  515 . Accordingly, the light-emitting portion is made nearly continuous along the circumferential direction of the element mounting portion  515 , thus making illumination intensity in the circumferential direction irregularities unlikely.
     (13) Also, as indicated by semiconductor light-emitting module  610  shown in  FIG. 18B , a plurality of semiconductor light-emitting elements  612  may be arranged in a staggered pattern along the circumferential direction of an element mounting portion  615  of a mounting substrate  611 . The semiconductor light-emitting elements  612  are, for example, individually sealed by sealers  613 . Accordingly, a more even light-emitting portion can be realized over the element mounting portion, thus improving the light distribution characteristics.   (14) Further, as indicated by semiconductor light-emitting module  710  shown in  FIG. 18C , a plurality of semiconductor light-emitting elements  712  may be aligned along the circumferential direction of an element mounting portion  715  of a mounting substrate  711 , and all of the semiconductor light-emitting elements  712  may be sealed by a single substantially annular sealer  713 . Accordingly, the light-emitting portion can be made continuous with the element mounting portion  715 , thus making illumination intensity irregularities in the circumferential direction unlikely.   (15) Also, as indicated by semiconductor light-emitting module  810  shown in  FIG. 18D , a plurality of pieces may be mounted in combination on the mount  20 . For example, a mounting substrate  811  may be made of a substantially semicircular element mounting portion  815  and a tongue portion  816  extending from one part of the element mounting portion  815 . A plurality of semiconductor light-emitting elements  812  may be mounted in an arc pattern on the element mounting portion  815  and sealed by a single substantially semicircular sealer  813 . A connector  817  is provided on the tongue portion  816 . Assembly is not complexified, provided that each module is arranged so that the front face  22  of the mount  20  is mountable on the semiconductor light-emitting modules  810 , i.e., so to be planar.   (16) Alternatively, the circuit holder may be omitted in whole or in part from the configuration, provided that sufficient space is provided between the circuit unit  40  and the light-emitting unit  90 , the case  60 , and so on, and that insulation is maintained for the circuit unit  40 . For example, as indicated by lamp light source  1300  shown in  FIG. 19 , the circuit holder main body is not required. As shown, the circuit unit  40  is indirectly supported in relation to the base  70  through the support member  91  and via the support base  76 . Also, a beam splitter  1380  is fixed to the lid  58  by adhesive or similar.   (17) In addition, as illustrated by lamp light source  1400  shown in  FIG. 20 , the circuit unit  40  may also be configured so as to be supported by a beam splitter  1480  in relation to a globe  1430 . As shown, the circuit substrate  42  of the circuit unit  40  is fixed to the lid  58  by adhesive or similar, and the lid  58  is likewise fixed to the beam splitter  1480 . Then, the beam splitter  1480  is fixed to the globe  1430 , and the circuit unit  40  is thus supported in relation to the globe  1430 . In such circumstances, the lid  58  and the beam splitter  1480  serve the role of support members that support the circuit unit in relation to the envelope (made up of the globe  1430 , the case  60 , and the base  70 ).   (18) Further, as indicated by lamp light source  1500  shown in  FIG. 21 , the circuit substrate  42  is fixed to the tubular portion  503 , and thus supported in relation to the base  70 . In such circumstances, as shown, the lid may be omitted. Also, the tubular portion  503  may be considered a portion of the base  70 , and the circuit holder may be completely absent.   (19) Although the above Embodiments and variations (those shown in  FIGS. 16 and 21  excepted) describe the beam splitter as being separate from the light-emitting unit, no limitation is intended. As indicated by lamp light source  1500  shown in  FIG. 21 , a space may be provided between the beam splitter  1580  and the circuit unit  40  such that the two components are separated. Thus, there is no risk of transmitting the heat produced by the light-emitting unit  1590  through the beam splitter  1580  to the circuit unit  40 . Like the lamp light source  1100  of the tenth variation illustrated in  FIG. 16 , the beam splitter  1580  is fixed directly to the top face of the mounting substrate  1511  of the semiconductor light-emitting module  1510 .   

     The beam splitter  1580  may be fixed to the top face of the mounting substrate  1511  the using an adhesive or the like, or the beam splitter  1580  and the mounting substrate  1511  may be fixed by screws  93  to form a single whole with the mount  1520 . 
       FIG. 22  is a magnified view of the portion of  FIG. 21  surrounded by double-chained line circle B, showing the above-described beam splitter  1580  and the mounting substrate  1511  fixed to the mount  1520  by the screws  93 . As shown, screw hole  928  is provided in the mount  1520 , screw hole  919 , which is a through-hole, is provided in the mounting substrate  1511 , and screw hole  1582   d , which is also a through-hole, is provided in the beam splitter  1580 . The screws  93  are screwed into these screw holes through a washer  94 . Accordingly, the mounting substrate  1511  and the beam splitter  1580  are fixed to the mount  1520 . The front face of the portion of the beam splitter  1580  where the screws  93  are screwed is formed as a recess  1582   a , simplifying the introduction of the screws  93 . A hole  1587 , which is a through-hole, is provided at the centre of the beam splitter  1580 . The portion between the inner face of the hole  1514  and screw hole  1582   d  is formed so as to protrude along the inner face toward the back face, forming a positioning portion  1582   b . The external diameter of the positioning portion  1582   b  matches the internal diameter of through-hole  1521  in the mount  1520  and hole  1514  in the mounting substrate  1511 . The positioning portion  1582   b  is fit into through-hole  1521  in the mount  1520  and hole  1514  in the mounting substrate  1511  such that the positions of the screw holes  928 ,  919 , and  1582   d  coincide when viewed head-on (i.e., in a direction parallel to lamp axis J). Thus, the screws  93  are screwable, simplifying the assembly. 
     In addition, a piece of the positioning portion  1582   b  is cut away to allow the tongue portion  916  to fit in this cutaway potion. 
     Although  FIG. 21  illustrates the beam splitter  1580  and the mounting substrate  1511  as being fixed to the mount  1520  by screws at three positions, no limitation is intended. Two screw positions may be used, as may four or more screw positions.
     (20) In the above-described Embodiments and variations, the inner face of the globe is treated so as to diffuse the light emitted by the semiconductor light-emitting module. For example, the inner face may be treated with silica or with a white pigment so as to achieve light diffusion. However, the inner face of the globe in the vicinity of the opening thereof may also be provided with a treated portion (light-diffusing portion)  1534  in a region illuminated by the portion of light emitted from the semiconductor light-emitting module and reflected by the beam splitter so as to further enhance the diffusing effect.   

     As shown in  FIG. 21 , the region of the inner face of the globe  1530  illuminated by the portion of light emitted from the semiconductor light-emitting module  1510  and reflected by the outer circumferential surface  1588  of the beam splitter  1580  is in near correspondence with a region between virtual plane P 1 , which is orthogonal to lamp axis J and passes through the forward edge portion of the beam splitter  1580 , and virtual plane P 2 , which corresponds to the front face of the mounting substrate  1511 . In the figure, the virtual planes P 1  and P 2  are cross-sections of planes passing through lamp axis J, represented by dashed lines. 
       FIG. 23  is a cross-sectional diagram showing a magnified view of section C, encircled by the chained line in  FIG. 21 .  FIG. 23  does not illustrate the entirety of the section encompassed by the oval section C. Only a small sub-section is illustrated. The treated portion  1534  of the inner face  1532  of the globe  1530  is formed as a uniform series of primary dimples  1535 , each being a semisphere of radius R (where R=40 μm, for example). A uniform series of secondary dimples  1536  are formed on the inner face of each primary dimple  1535 , each secondary dimple  1536  being a semisphere of radius r (where r=5 μm, for example). 
     Accordingly, each tiny dimple so formed has a uniform series of yet smaller simples formed therein. This doubly-dimpled structure provides the treated portion  1534  with improved light dispersion characteristics in comparison to similar but singly-dimpled structures. 
     The treated portion  1534  is formed in a region of the globe  1530  that is exposed from the case  60 , a region where the light reflected by the outer circumferential surface  1588  of the beam splitter  1580  arrives being beneficial. This results in the light reflected backward by the outer circumferential surface  1588  being diffused by the (treated portion  1534  of the) globe  1530 , expanding the light dispersion range backward, and improving the contrast provided by the globe  1530  when the lamp light source  1500  is lit. 
     The radius of each primary dimple  1535  is desirably such that R=20 μm to 40 μm, inclusive, and the radius of each secondary dimple  1536  is desirably such that r=2 μm to 9 μm, inclusive. 
     Also, the semiconductor light-emitting elements  12  need not necessarily be arranged so as to emit light forward, i.e., along lamp axis J. The semiconductor light-emitting elements  12  may be, in whole or in part, arranged so as to be slanted with respect to lamp axis J. Accordingly, control of the light distribution is improved and desired light distribution is achievable.
     (21) The support members  91  used in  FIG. 14  may be replaced by an insulating thermoconductive filling member  78 , which is made of resin or the like, solidly fills the space between the large-diameter portion  502  and the base  70 , and is thermally conductive. Such a member is shown in  FIG. 12  and described in the sixth variation.   

     In such circumstances, gap  65   a  between the large-diameter portion  502  and the tubular portion  503  is filled by the insulating thermoconductive filling member  78  and eliminated thereby. Gap  65   b  between the large-diameter portion  502  and the case  60  is likewise partly filled by the insulating thermoconductive filling member  78  and thereby eliminated. However, the space within the tubular portion  503  is also filled by the insulating thermoconductive filling member  78 . Thus, the heat produced by the circuit unit  40  is transmitted through the insulating thermoconductive filling member  78  to the base  70  to be dissipated thereby, thus constraining heat accumulation in the space.
     (22) Also,  FIG. 24  illustrates the configuration of a lamp light source  1600 , which is a variation where the insulating thermoconductive filling member  78 , made of thermally conductive resin or the like, solidly fills the space between the circuit substrate  42  and the base  70 , applied to the eighteenth variation shown in  FIG. 21 , when appropriate. In such circumstances, the heat produced by the circuit unit  40  is transmitted through the insulating thermoconductive filling member  78  to the base and dissipated, thus constraining heat accumulation in the space.   (23) The configuration shown in  FIG. 21  involves the circuit substrate  42  being fixed to and supported by the tubular portion  503 . However, as indicated by lamp light source  1700  shown in  FIG. 25 , when a gap is provided between the circuit substrate  42  and the tubular portion  503  (i.e., when the two components are separated), the circuit substrate  42  may be supported by the support members  91 . Accordingly, the heat produced by the circuit unit  40  is transmitted through the support members  91  to the base  70  and dissipated. Additionally, the space between the circuit substrate  42  and the base  70  is in communication with the gap between the circuit substrate  42  and the tubular portion  503  and with the space within the globe  1530  through the through-hole  1521 . Therefore, air is able to circulate through these spaces, thus constraining temperature increases caused to heat accumulation in the space between the circuit substrate  42  and the base  70 .   (24) In the above-described Embodiments and variations, the mount  20  is accommodated within the forward edge portion  62  of the case  60  and the globe  30  is installed by inserting the open edge  31  of the globe  30  in space  63  (i.e., the installation groove), which is a gap between the mount  20  and the case  60 . Here, for example, an adhesive or similar may be applied to space  63  before the open edge  31  is inserted. The adhesive thus serves to fix the open edge  31  after insertion and fix the mount  20 , the globe  30 , and the case  60  as a single whole.   

     As shown in  FIG. 26A , through-hole  34  may be formed so as to pass through the thickness direction of the open edge  31 .  FIG. 26A  is a magnified-view cross-sectional diagram of a lamp light source pertaining to the present variation corresponding to portion D encircled by the double-chained line in  FIG. 3 . 
     As shown, when the open edge  31  is inserted into space  63 , some of the adhesive applied to space  63  is displaced by the open edge  31  and infiltrates through-hole  34  through a minute gap formed between the outer circumferential surface of the open edge  31  and the inner face  64  of the case  60  and through another minute gap formed between the inner face of the open edge  31  and the outer circumferential surface of the mount  20 . Some of the adhesive further infiltrates through-hole  34  beyond the minute gaps. After solidifying, the adhesive is subdividable into adhesive  95  located behind the open edge  31  in space  63 , adhesive  96  located within through-hole  34 , adhesive  98  forming a thin film in the minute gap between the outer circumferential surface of the open edge  31  and the inner face  64  of the case  60 , and adhesive  99  forming a thin film in the minute gap between the inner face of the open edge  31  and the outer circumferential surface of the mount  20 . These form a stretch of adhesive working as a whole to keep the mount  20 , the case  60 , and the open edge  31  of the globe  30  fixed to one another. 
     The diameter of the through-hole  34  may be, for example, 0.5 mm to 2.5 mm, inclusive. However, no limitation is intended. 
     Given that adhesive  98  and adhesive  99  are thin films, these portions are represented by thick lines in the drawings for ease of comprehension. The thickness of the lines is not intended to suggest a particular thickness for adhesive  98  and adhesive  99 . The same applies to the twenty-fifth variation described below. 
     Accordingly, the surface contact area between the open edge  31  and the adhesive is increased. This makes the adhesive less likely to easily peel away from the surface of the open edge  31 , and in the unlikely case that adhesive  98  and adhesive  99  do peel away, the open edge  31  is prevented from separating from space  63  (i.e., the installation groove) by the anchoring effect of adhesive  96 , which is connected to adhesive  95  through adhesive  98  and adhesive  99 . 
     The above-described through-hole  34  is beneficial when provided in at least two locations. Here, through-holes  34  are ideally provided at substantially equal intervals along the circumferential direction of the open edge  31 . Accordingly, the load on adhesive  26  is spread out, the risk of breakage is decreased at the junction between adhesive  96  and adhesive  98  or adhesive  99 , and the open edge  31  is prevented from separating from space  63  (the installation groove), despite the adhesive peeling away from the open edge  31 . 
     The adhesive applied inside space  63  before the open edge  31  is inserted therein should be provided in a quantity that does not cause the adhesive pressed out by the open edge  31  to surpass either the leading edge of the forward edge portion  62  of the case  60  or the front face  22  of the mount  20 . This is beneficial for cost reduction as well as aesthetics. The adhesive may also be applied so as to not surpass the front face of the mounting substrate  11 , rather than the front face  22  of the mount  20 . The same applies to the twenty-fifth variation, described below.
     (25) The configuration described above in the twenty-fourth variation may replace the through-holes in the thickness direction with a dimpled recess in the same direction.   

       FIG. 26B  is a magnified-view cross-sectional diagram of a lamp light source pertaining to the present variation corresponding to portion D encircled by the double-chained line in  FIG. 3 . 
     As shown, the outer circumferential surface of the open edge  31  has a dimpled recess  35  formed therein in the thickness direction. As described in the twenty-fourth Embodiment, when the open edge  31  is inserted into space  63 , some of the adhesive applied to space  63  is displaced by the open edge  31  and infiltrates the recess  35  through a minute gap formed between the outer circumferential surface of the open edge  31  and the inner face  64  of the case  60 . The adhesive then spreads through the minute gap formed between the outer circumferential surface of the open edge  31  and the inner face  64  of the case  60  and through another minute gap formed between the inner face of the open edge  31  and the outer circumferential surface of the mount  20 . After solidifying, the adhesive is subdividable into adhesive  95 , adhesive  97 , adhesive  98 , and adhesive  99 . 
     Accordingly, the surface contact area between the open edge  31  and the adhesive is increased. This makes the adhesive less likely to easily peel away from the surface of the open edge  31 , and in the unlikely case that adhesive  98  and adhesive  99  do peel away, the open edge  31  is prevented from separating from space  63  (i.e., the installation groove) by the anchoring effect of adhesive  97 , which is connected to adhesive  95  through adhesive  98 . 
     The diameter of the dimpled recess  35  may be, for example, 0.5 mm to 2.5 mm inclusive. However, no limitation is intended. The depth of the dimpled recess  35  is dependent on the thickness of the open edge  31 . When the open edge  31  is 1 mm thick, then the recess  35  is, for example, 0.8 mm. However, no limitation is intended. 
     Like the through-holes  34  described in the twenty-fourth variation, the above-described dimpled recess  35  is beneficial when provided in at least two locations. Here, the dimpled recesses  35  are ideally provided at substantially equal intervals along the circumferential direction of the open edge  31 . Accordingly, the load on adhesive  97  is spread out, the risk of breakage is decreased at the junction between adhesive  97  and adhesive  98 , and the open edge  31  is prevented from separating from space  63  (i.e., the installation groove), despite the adhesive peeling away from the open edge  31 .
     (26) In the Embodiments and variations described above, groove-like space  63  in which the open edge  31  is inserted is formed by the inner face  64  of the case  60  and the outer circumferential surface of the mount  20 . However, no limitation is intended. For example, the exterior of the mount  20  may be provided with an annular member having a groove-like space serving as the installation groove, and the case  60  may be installed in this member. In such circumstances, the mount  20  may be pressed into the annular member or fixed thereto by adhesive or similar. Conversely, the annular member may be press into the case  60 , or fixed thereto by adhesive or similar.   

     Furthermore, given a thin-walled case with a correspondingly thin forward edge portion, mechanical properties such as strength and rigidity can be provided through reinforcing members on the forward edge of the case. For instance, this may take the form of a reinforcing ring pressed into the case, such that the installation groove is formed between the reinforcing ring and the outer circumferential surface of the mount  20 . 
     Furthermore, the installation groove may be formed in the mount  20 , or provided on the case  60 . For example, an installation groove provided on the case  60  may be realized by folding over an edge of the case  60 , which is made of a metallic material.
     (27) In the above-described Embodiments and variations, the open edge  31  is described as being continuous along the circumferential direction, and space  63  (i.e., the installation groove) for inserting the open edge  31  is correspondingly described as being a continuous groove in the circumferential direction. However, no limitation is intended. For example, a plurality of protruding open edges  31  may be formed and a groove of sufficient depth to accommodate the protrusions may be formed at a corresponding position in the circumferential direction. In such circumstances, the protruding open edges  31  are desirably substantially equidistant with respect to the circumferential direction. Accordingly, the force applied by the globe  30  on the case  60  is distributed equally with respect to the circumferential direction, and the globe  30  is more reliably secured.   

     Also, when the installation groove is formed using a separate member, grooves may be provided at positions corresponding to the protruding open edges  31 . Further, rather than using a set of annular members, the plurality of members providing the installation groove may be arranged at positions corresponding to the protruding open edge  31 .
     (28) In the above-described Embodiments and variations, space is provided throughout the entire area between the circuit unit (or the circuit holder) and the light-emitting unit. However, no limitation is intended. For example, the area between the circuit unit (or the circuit holder) and the light-emitting unit may be filled in whole or in part by adiabatic material formed from an insulating member. In such circumstances, the propagation of heat from the light-emitting unit to the circuit unit is suppressed, in turn suppressing temperature increases in the circuit unit.   (29) Further, the space between the circuit unit (or the circuit holder) and the light-emitting unit may be partially filled by an insulating member. In such circumstances, the insulating member need not be adiabatic, as an adiabatic effect is provided by the air in the space between the circuit unit (or the circuit holder) and the light-emitting unit that is not filled by the insulating member. Thus, the propagation of heat from the light-emitting unit to the circuit unit is suppressed to a certain degree.   

     The individual components of the lamp light sources pertaining to Embodiments 1 and 2, as well as the configurations described in the variations, may be freely combined as appropriate into a given lamp light source. In addition, the materials and dimensions described in the above Embodiments and variations are given as examples, and no limitation is intended thereby. Further, the dimensions and ratios of components indicated by the drawings are intended only as examples. No limitations is intended regarding the dimensions of an actual lamp light source. Further still, appropriate modifications may be made to the lamp light source provided that these do not deviate from the technical concept of the present invention. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure is applicable to miniaturizing an LED lamp while preserving the useable life of the circuit unit. 
     REFERENCE SIGNS LIST 
     
         
           1 ,  100  Lamp light source 
           12 ,  512 ,  612 ,  712 ,  812  Semiconductor light-emitting element 
           20  Mount 
           21  Through-hole 
           27  Gap 
           30  Globe 
           40  Circuit unit 
           42  Circuit substrate 
           50 ,  501  Circuit holder 
           58  Lid 
           60  Case 
           65  Gap 
           70  Base 
           80 ,  180 ,  280 ,  380  Beam splitter 
           90  Light-emitting unit 
           91  Support member