Patent Publication Number: US-2015085495-A1

Title: Lamp and lighting apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a lamp using a light-emitting element such as a light-emitting diode (LED) as a light source and to a lighting apparatus including the lamp. 
     BACKGROUND ART 
     Conventionally, disc-shaped or low-profile LED lamps using LEDs as a light source have been proposed (for example, see Patent Literature (PTL) 1). Generally, such LED lamps include a disk-shaped or low-profile case which contains an LED board on which an LED is mounted, and a cover component which covers an opening of the case. Furthermore, the cover component is connected and secured to the case through an adhesive or an interfitting structure. 
     CITATION LIST 
     Patent Literature 
     PTL 1: International Publication No. WO2012/005239 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, with the above-described conventional LED lamp, there are cases where the connection between the cover component and the case breaks due to deterioration, and the like, caused by the heat when the light is on. Then, when the connection between the cover component and the case is broken, the cover component falls off. 
     Furthermore, since a reflecting component which reflects the light from the LED, and so on, are also disposed inside the case, there is the possibility that the reflecting component, and so on, may also drop together with the cover component when the cover component falls off from the case. Since, in general, such LED lamps are usually located overhead, it is very important to reduce as much as possible the possibility of such components dropping. 
     The present invention is conceived in view of the aforementioned problem and has as an object to provide a lamp and a lighting apparatus which are capable of preventing components from dropping even when the connection between the cover component and the case breaks. 
     Solution to Problem 
     In order to achieve the aforementioned object, a lamp according to an aspect of the present invention is a lamp that emits light and includes: a board on which a light-emitting element is provided; a reflecting component which is disposed on a light-emission-side of the board, and reflects light emitted from the light-emitting element; a case inside which the reflecting component is entirely or partially disposed, and which has an opening formed on the light-emission side; and a cover component which covers the opening formed in the case, wherein the reflecting component includes a case-side reflecting component connecting part for connecting with the case, and the case includes a reflecting component-side case connecting part which connects with the case-side reflecting component connecting part, the case further includes a cover-side case connecting part for connecting with the cover component, and the cover component includes a case-side cover connecting part which connects with the cover-side case connecting part, and the cover component further includes a reflecting component-side cover connecting part for connecting with the reflecting component, and the reflecting component further includes a cover-side reflecting component connecting part which connects with the reflecting component-side cover connecting part. 
     Furthermore, the case-side reflecting component connecting part and the reflecting component-side case connecting part may be shaped to be engageable with each other, the cover-side case connecting part and the case-side cover connecting part may be shaped to be engageable with each other, and the reflecting component-side cover connecting part and the cover-side reflecting component connecting part may be shaped to be engageable with each other. 
     Furthermore, the reflecting component may include a plurality of the case-side reflecting component connecting parts which are arranged equidistantly along a loop, and the case may include a plurality of the reflecting component-side case connecting parts each of which corresponds to a different one of the case-side reflecting component connecting parts, the case may include a plurality of the cover-side case connecting parts which are arranged equidistantly along a loop, and the cover component may include a plurality of the case-side cover connecting parts each of which corresponds to a different one of the cover-side case connecting parts, and the cover component may include a plurality of the reflecting component-side cover connecting parts which are arranged equidistantly along a loop, and the reflecting component may include a plurality of the cover-side reflecting component connecting parts each of which corresponds to a different one of the reflecting component-side cover connecting parts. 
     Furthermore, when seen from a center of the lamp, one or more case-side cover connecting parts including the case-side cover connecting part are arranged in a loop at positions which may be different from positions, in a loop, at which one or more reflecting component-side cover connecting parts including the reflecting component-side cover connecting part are arranged. 
     Furthermore, the cover component may further include a rotation positioning part located at both sides of the reflecting component-side cover connecting part, the rotation positioning part determining a rotation position of the cover component with respect to the reflecting component by interfitting with the cover-side reflecting component connecting part. 
     Furthermore, the cover component may further include a rotation regulating part which regulates rotation of the cover component with respect to the case, by abutting a projecting part of the case which projects towards an inside of the case. 
     Furthermore, in order to achieve the aforementioned object, a lighting apparatus according to an aspect of the present invention includes: the above-described lamp; and lighting equipment to which the lamp is attached, wherein the lighting equipment includes: a main body configured to cover the lamp; and a socket attached to the main body, for supplying power to the lamp. 
     Advantageous Effects of Invention 
     According to a lamp and a lighting apparatus according to the present invention, it is possible to prevent components from dropping even when the connection between the cover component and the case breaks. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a perspective view of an external appearance of a lamp according to Embodiment 1 of the present invention. 
         FIG. 1B  is a perspective view of an external appearance of the lamp according to Embodiment 1 of the present invention. 
         FIG. 2  is a diagram showing a configuration of the lamp according to Embodiment 1 of the present invention. 
         FIG. 3  is an exploded perspective view of the configuration of the lamp according to Embodiment 1 of the present invention. 
         FIG. 4  is a perspective view of a configuration of a case according to Embodiment 1 of the present invention. 
         FIG. 5  is a perspective view of a configuration of a reflecting mirror according to Embodiment 1 of the present invention. 
         FIG. 6  is a perspective view of a configuration of a light-transmissive cover according to Embodiment 1 of the present invention. 
         FIG. 7  is a diagram showing a positional relationship between the light-transmissive cover, and the case and reflecting mirror according to Embodiment 1 of the present invention. 
         FIG. 8  is a diagram showing a connecting state between the case and the reflecting mirror according to Embodiment 1 of the present invention. 
         FIG. 9  is a diagram showing a connecting state between the light-transmissive cover, and the case and reflecting mirror according to Embodiment 1 of the present invention. 
         FIG. 10  is a cross-sectional view of a configuration of a lighting apparatus according to Embodiment 2 of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, lamps and lighting apparatuses according to exemplary embodiments of the present invention shall be described with reference to the Drawings. It should be noted that each of subsequently-described embodiments show one specific preferred example of the present invention. The numerical values, shapes, materials, structural components, the arrangement and connection of the structural components, etc. shown in the following exemplary embodiments are mere examples, and are not intended to limit the scope of the present invention. Furthermore, among the structural components in the following exemplary embodiments, components not recited in any one of the independent claims are described as arbitrary structural components included in a more preferable form. Moreover, in the respective figures, dimensions, etc. are not precise. Furthermore, in the present application, numerical ranges defined using the word “between” include the numerical values at both end-points. 
     Embodiment 1 
     First, an outline configuration of a lamp  1  according to Embodiment 1 of the present invention shall be described. 
       FIG. 1A  and  FIG. 1B  are perspective views of the external appearance of the lamp  1  according to Embodiment 1 of the present invention. Specifically,  FIG. 1A  is a perspective view of the lamp  1  when viewed obliquely from above, and  FIG. 1B  is a perspective view of the lamp  1  when viewed obliquely from below. It should be noted that, although an opening of the lamp  1  is covered by a cover, the cover is of a transparent material and thus the inside of the lamp  1  can be seen through the cover in  FIG. 1B . 
     As shown in these figures, the lamp  1  is an LED lamp having a disk-like or low-profile overall shape. Specifically, the lamp  1  is an LED lamp having a GH76p base. More specifically, the lamp  1  has, for example, an outer diameter of between 50 and 100 mm and a height of between 30 and 50 mm, and when the lamp is a 20 W LED lamp, for example, the outer diameter is 90 mm and the height is 45 mm. 
     Furthermore, the lamp  1  includes a support  20  that is attached to lighting equipment (not illustrated), a mounting board  40  on which a light-emitting element is provided, and a case  50  that is connected to the support  20 . 
     It should be noted that, in  FIG. 1A , the lamp is illustrated in such a way that the side where light is elicited from the lamp (hereafter called light-emission-side) is the underside, and, in  FIG. 1B , the lamp is illustrated in such a way that the light-emission-side is the topside. Hereinafter, in this embodiment, up (topside) and down (underside) shall be defined with reference to the state in which an LED lamp is disposed such that the light-emission-side is the underside, as in  FIG. 1A . 
     Furthermore, five through holes  51  (through holes  51   a  to  51   e  in the figure) are formed along a circle in the top face (face on the lighting equipment-side) of the case  50 . An electrical connection pin  52  for electrically connecting with the lighting equipment is inserted in each through hole  51 . It should be noted that, although electrical connection pins  52   a  and  52   b  are inserted through the through holes  51   a  and  51   b  in the figure, electrical connection pins  52   c  to  52   e  (not illustrated) are also inserted through the through holes  51   c  to  51   e , respectively. Here, for example, the electrical connection pins  52   a  and  52   b  are power supply pins, the electrical connection pins  52   c  and  52   d  are light adjustment pins, and the electrical connection pin  52   e  is a grounding pin. It should be noted that, for example, in the case where light adjustment will not be performed, the through holes  51   c  and  51   d  are not formed and the electrical connection pins  52   c  and  52   d  are not inserted. 
     Next, the detailed configuration of the lamp  1  according to Embodiment 1 of the present invention shall be described. 
       FIG. 2  and  FIG. 3  are diagrams showing the configuration of the lamp  1  according to Embodiment 1 of the present invention. Specifically,  FIG. 2  is an outline diagram of the cross-section obtained when the lamp  1  is cut vertically, and  FIG. 3  is an exploded perspective view of the respective structural components when the lamp  1  is disassembled. Moreover,  FIG. 2  is an outline diagram for describing the positional relationship of the respective structural components, and the structure, and so on, of the connecting parts of the respective structural components are omitted in the illustration. 
     As shown in these figures, the lamp  1  includes a heat-conducting sheet  10 , the support  20 , a heat-conducting sheet  30 , the mounting board  40 , the case  50 , securing screws  60 , a circuit board  70 , a reflecting mirror  80 , and a light-transmissive cover  90 . 
     The heat-conducting sheet  10  is a heat-conductive sheet for releasing, to the lighting equipment-side, the heat from the mounting board  40  that is transmitted via the support  20 . Specifically, the heat-conducting sheet  10  is a sheet made of rubber or resin, and is, for example, a silicon sheet or an acrylic sheet. 
     The support  20  is a component that is connected to the lighting equipment. Specifically, for example, a GH76p base structure is formed in the upper part of the support  20 , and is attached and secured to the lighting equipment. Furthermore, the support  20  is a pedestal on which the mounting board  40  is attached, and is disposed on a side opposite the light-emission-side of the mounting board  40 . Furthermore, it is preferable that the support  20  be made of highly heat-conductive material such as aluminum. 
     The heat-conducting sheet  30  is a heat-conducting sheet that thermally connects the mounting board  40  and the support  20 . Specifically, the heat-conducting sheet  30  is a heat-conductive sheet that can efficiently transmit the heat from the mounting board  40  to the support  20 , and release the heat to the lighting equipment-side. It should be noted that, in the case where the mounting board  40  is a metal board, it is preferable that the heat-conducting sheet  30  be an insulating sheet that provides insulation between the mounting board  40  and the support  20 . Specifically, the heat-conducting sheet  30  is a sheet made of rubber or resin, and is, for example, a silicon sheet or an acrylic sheet. Moreover, the heat-conducting sheet  30  may be a liquid component, and so on, such as grease. 
     The mounting board  40  is a board on which a light-emitting element such as a semiconductor light-emitting element is provided. The mounting board  40  is, for example, configured to be plate-like, and has one face on which the light-emitting element is mounted, and another face that can be thermally connected to the support  20 . Furthermore, it is preferable that the mounting board  40  be made of highly heat-conductive material, and is, for example, made of an alumina substrate made of alumina. It should be noted that, aside from an alumina substrate, a ceramic substrate made of other ceramic material such as aluminum nitride, metal substrates made of aluminum, copper, or the like, or a metal-core substrate having a stacked structure of a metal plate and a resin substrate may be used for the mounting board  40 . It should be noted that the mounting board  40  is included in the “board” recited in the Claims. 
     Specifically, a light-emitting unit  41  is provided in the mounting board  40 . The light-emitting unit  41  includes plural LED chips (not illustrated) mounted on the mounting board  40 , and a sealing component (not illustrated). The LED chips are mounted on one of the faces of the mounting board  40  by die bonding, or the like. It should be noted that, for example, blue LED chips which emit blue light having a central wavelength at between 440 and 470 nm are used as the LED chips. Furthermore, the sealing component is a phosphor-containing resin made of a resin containing phosphor, for protecting the LED chips by sealing the LED chips, as well as for converting the wavelength of the light from the LED chips. As a sealing component, for example, in the case where the LED chips are blue light-emitting LEDs, a phosphor-containing resin in which yttrium, aluminum, and garnet (YAG) series yellow phosphor particles are dispersed in silicone resin can be used to obtain white light. With this, white light is emitted from the light-emitting unit  41  (sealing component) due to the yellow light obtained through the wavelength conversion by the phosphor particles and the blue light from the blue LED chips. 
     Further, the outer diameter of the light-emitting unit  41  is, for example, between 5 and 50 mm, and when the lamp  1  is a 20 W LED lamp, the outer diameter of the light-emitting unit  41  is, for example, 20 mm. 
     It should be noted that although a round light-emitting unit  41  is given as an example in this embodiment, the shape or structure of the light-emitting unit in the present invention is not limited to a round one. For example, a square-shaped light-emitting unit may be used. Furthermore, the arrangement of the LED chips is not particularly limited. For example, the LED chips may be sealed in a line, matrix, or circular form. 
     The case  50  is a low-profile, cylindrical case surrounding the light-emission-side of the lamp  1 , and has an opening formed on the light-emission side. Specifically, the upper part of the case  50  is secured to the support  20  by way of the securing screws  60 , and the light-transmissive cover  90  is attached to the bottom part of the case  50 . In addition, the heat-conducting sheet  30 , the mounting board  40 , the circuit board  70 , and the reflecting mirror  80  are disposed inside the case  50 . The case  50  is configured of a resin case made of a synthetic resin having insulation properties, such as polybutylene terephthalate (PBT). 
     Furthermore, as shown in  FIG. 1A , the case  50  includes the electrical connection pins  52  which are power receiving units that receive power for causing the LED chip mounted on the mounting board  40  to emit light. Specifically, the electrical connection pins  52  for supplying power receive alternating-current (AC) power, and the received AC power is input to the circuit board  70  via a lead wire. Detailed description of the configuration of the case  50  shall be provided later. 
     The securing screws  60  are screws for securing the case  50  to the support  20 . It should be noted the case  50  and the support  20  are not limited to being secured using screws. For example, the case  50  and the support  20  may have interfitting parts, and the case  50  may be connected to the support  20  through the interfitting of these parts. Alternatively, the case  50  may be joined to the support  20  by using an adhesive. 
     The circuit board  70  is a power source circuit board for causing the LED chip mounted on the mounting board  40  to emit light. The circuit board  70  is a disk-shaped hoard in which a circular opening is formed (i.e., donut-shaped board), and is disposed inside the case  50  and outside the reflecting mirror  80 . In addition, the circuit element (electronic component) mounted on the circuit board  70  is disposed in the space inside the case  50  and outside the reflecting mirror  80 . 
     Furthermore, since the circuit board  70  is disposed in the upper part of the inside of the case  50 , it is preferable that a circuit element in which the size of, for example, an electrolytic capacitor, choke coil, or the like, is large, be disposed on the bottom face-side of the circuit board  70 . It should be noted that although the circuit board  70  is illustrated in this embodiment in a form that is displaced inside the case  50  and outside the reflecting mirror  80 , the placement location is not particularly limited and may be arbitrarily designed. 
     Moreover, in the form in which the circuit board  70  is disposed inside the case  50  and outside the reflecting mirror  80 , it is preferable that a large-sized circuit element be disposed on the outer portion of the circuit board  70 . This is because, as shown in  FIG. 2 , when the reflecting mirror has a shape in which the radius widens towards the bottom, the space formed in the outer portion of the circuit board  70  is larger than the space formed in the inner portion of the circuit board  70 . 
     Specifically, a circuit element (electronic component), or the like, for converting the AC power received from the electrical connection pins  52  for supplying power into direct-current (DC) power is mounted on the circuit board  70 . Specifically, the input unit of the circuit board  70  and the electrical connection pins  52  for supplying power are electrically connected by a lead wire or the like, and the output unit of the circuit board  70  and the light-emitting unit of the mounting board  40  are electrically connected by a lead wire or the like. The DC power obtained from the conversion by the circuit board  70  is supplied to the light-emitting unit of the mounting board  40 , via a power supply terminal. 
     The reflecting mirror  80  is an optical component which is disposed on the light-emission-side of the mounting board  40 , and reflects light emitted from the light-emitting unit. In other words, the reflecting mirror  80  reflects, downward, the outgoing light emitted from the light-emitting unit provided in the mounting board  40 . Specifically, the reflecting mirror  80  is disposed below the mounting board  40  and inside the case  50 , and includes a truncated cylindrical part which is formed to have a radius that gradually increases towards the bottom. 
     Furthermore, the reflecting mirror  80  is made of a white synthetic resin material having insulation properties. Although it is preferable that the material of the reflecting mirror  80  be a polycarbonate, it is not limited to polycarbonate. It should be noted that, in order to improve reflectivity, the inner face of the reflecting mirror  80  may be coated with a reflective film. It should be noted that the reflecting mirror  80  is included in the “reflecting component” recited in the Claims. Furthermore, detailed description of the configuration of the reflecting mirror  80  shall be provided later. 
     The light-transmissive cover  90  is a low-profile, cylindrical component having a disk-shaped bottom, which is attached to the bottom face of the case  50  in order to protect the components disposed inside the case  50 . The light-transmissive cover  90  is secured to the bottom face of the case  50  by adhesive, rivets, screws, or the like, to cover the opening formed on the light-emission-side of the case  50 . 
     Furthermore, the light-transmissive cover  90  is made of a highly light-transmissive synthetic resin material such as polycarbonate so as to allow transmission of the outgoing light emitted from the light-emitting unit provided in the mounting board  40 . It should be noted that paint for promoting light-diffusion may be applied to the inner face of the light-transmissive cover  90 . Furthermore, phosphor may be included in the light-transmissive cover  90 . In this case, the color of the light emitted from the light-emitting unit can be converted by the light-transmissive cover  90 . It should be noted that the light-transmissive cover  90  is included in the “cover component” recited in the Claims. Furthermore, detailed description of the configuration of the light-transmissive cover  90  shall be provided later. 
     Next, details of the configuration of the case  50  shall be described. 
       FIG. 4  is a perspective view of the configuration of the case  50  according to Embodiment 1 of the present invention. Specifically, the figure is a perspective view for when the case  50  is viewed obliquely from below. 
     As shown in the figure, the case  50 , includes an annular case side face part  53 , and a disk-shaped case top face part  54  disposed above the case side face part  53  and having a circular opening formed therein. In other words, the case  50  is formed to curve inward towards the support  20 -side. 
     Furthermore, plural cover-side case connecting parts  53   a  which are arranged equidistantly along a loop (in the figure, three cover-side case connecting parts  53   a  which are arranged equidistantly along a circle) are formed in the inner face of the case side face part  53 . Here, the cover-side case connecting parts  53   a  are connecting parts for connecting with the light-transmissive cover  90 . 
     Specifically, each of the cover-side case connecting parts  53   a  has a shape which allows engagement with a corresponding one of case-side cover connecting parts  92  of the light-transmissive cover  90  to be described later. More specifically, the cover-side case connecting parts  53   a  are recessions formed in the inner face of the case side face part  53 . 
     Although three cover-side case connecting parts  53   a  are formed in this embodiment, the number of the cover-side case connecting parts  53   a  is not limited to such. It should be noted that, from the viewpoint of stably attaching the light-transmissive cover  90  to the case  50 , it is preferable that two or more of the cover-side case connecting parts  53   a  be formed, and it is more preferable that three or more of the cover-side case connecting parts  53   a  be formed. 
     In addition, a projecting part  53   b  projecting towards the inside of the case is formed in the inner face of the case side face part  53 . Here, the projecting part  53   b  is a part for regulating the rotation of the light-transmissive cover  90 . Specifically, the projecting part  53   b  is a rod-shaped projecting part which extends vertically, and, by abutting a rotation-regulating part  96  of the light-transmissive cover  90  to be described later, is capable of regulating the rotation of the light-transmissive cover  90  with respect to the case  50 . 
     Screw insertion parts  54   a  to  54   c  for the insertion of the securing screws  60  are formed in the case top face part  54 . Specifically, three securing screws  60  are respectively inserted in the screw insertion parts  54   a  to  54   c , and the case  50  and the support  20  are fastened by being screwed together. 
     Furthermore, plural mirror-side case connecting parts  55  which are arranged equidistantly along a loop (in the figure, two mirror-side case connecting parts  55  which are disposed opposite each other along a circle) are disposed inside the opening of the case top face part  54 . Here, the mirror-side case connecting parts  55  are connecting parts for connecting with the reflecting mirror  80 . 
     Specifically, the mirror-side case connecting parts  55  have a shape which allows engagement with case-side reflecting mirror connecting parts  81   a  of the reflecting mirror  80  to be described later. More specifically, each of the mirror-side case connecting parts  55  has a U-shape or a V-shape that is recessed toward the bottom. 
     In this embodiment two of the mirror-side case connecting parts  55  are provided. Here, the mirror-side case connecting parts  55  are provided as twofold drop-prevention parts for preventing the reflecting mirror  80  and the light-transmissive cover  90  from dropping in the case where the connection between the light-transmissive cover  90  and the case  50  breaks. As such, the number of connection locations for the case  50  and the reflecting mirror  80  is set lower than the number of connection points for the light-transmissive cover  90  and the case  50  and the number of connection locations for the light-transmissive cover  90  and the reflecting mirror  80 . 
     It should be noted that, although the number of the mirror-side case connecting parts  55  is not limited to two, in order to prevent the reflecting mirror  80  and the light-transmissive cover  90  from dropping in the case where the connection between the light-transmissive cover  90  and the case  50  breaks, it is preferable that two or more of the mirror-side case connecting parts  55  be provided. 
     Next, details of the configuration of the reflecting mirror  80  shall be described. 
       FIG. 5  is a perspective view of the configuration of the reflecting mirror  80  according to Embodiment 1 of the present invention. Specifically, the figure is a perspective view for when the reflecting mirror  80  is viewed obliquely from below. 
     As shown in the figure, the reflecting mirror  80  includes: a truncated cylinder-shaped reflecting mirror side face  81  which is formed with a radius that gradually increases towards the bottom; and a reflecting mirror bottom face part  82  which has a disk-like shape in which a circular opening is formed (i.e., a donut-shape) and is connected to the bottom face of the reflecting mirror side face  81 . 
     Furthermore, plural case-side mirror connecting parts  81   a  which are arranged equidistantly along a loop (in the figure, two case-side mirror connecting parts  81   a  which are disposed opposite each other along a circle) are disposed in the upper part of the reflecting mirror side face  81 . Here, the case-side mirror connecting parts  81   a  are connecting parts for connecting with the reflecting mirror  80 . 
     Specifically, the case-side mirror connecting parts  81   a  have a shape which allows engagement with the mirror-side case connecting parts  55  of the case  50 . In other words, each of the case-side mirror connecting parts  81   a  is a projecting part that projects outward from the upper part of the reflecting mirror side face  81 . 
     Although two of the case-side mirror connecting parts  81   a  are formed in this embodiment, the number of the case-side mirror connecting parts  81   a  is not limited to such. It should be noted that, like the mirror-side case connecting parts  55 , in order to prevent the reflecting mirror  80  and the light-transmissive cover  90  from dropping in the case where the connection between the light-transmissive cover  90  and the case  50  breaks, it is preferable that two or more of the case-side mirror connecting parts  81   a  be provided. 
     Furthermore, plural cover-side mirror connecting parts  82   a  and  82   b  which are arranged equidistantly along a loop (in the figure, two cover-side mirror connecting parts  82   a  and one cover-side mirror connecting part  82   b  which are arranged equidistantly along a circle) are formed on the outer periphery of the reflecting mirror bottom face part  82 . Here, the cover-side mirror connecting parts  82   a  and  82   b  are connecting parts for connecting with the light-transmissive cover  90 . 
     Specifically, the cover-side mirror connecting parts  82   a  have a shape which allows engagement with mirror-side cover connecting parts  93  of the light-transmissive cover  90  to be described later, and the cover-side mirror connecting part  82   b  has a shape which allows engagement with the mirror-side cover connecting part  95  of the light-transmissive cover  90  to be described later. Specifically, the cover-side mirror connecting parts  82   a  and  82   b  are recessions formed on the outer periphery of the reflecting mirror bottom face part  82 , and are formed so that the recession of the cover-side mirror connecting part  82   b  is wider than the recession of the cover-side mirror connecting part  82   b.    
     Although two of the cover-side mirror connecting parts  82   a  and one cover-side mirror connecting part  82   b  are formed in this embodiment, the number of the cover-side mirror connecting parts  82   a  and  82   b  is not limited to such. It should be noted that, in order to prevent the light-transmissive cover  90  from dropping in the case where the connection between the light-transmissive cover  90  and the case  50  breaks, it is preferable that two or more of the cover-side mirror connecting parts be provided, and it is more preferable that three or more of the cover-side mirror connecting parts be provided. 
     Next, details of the configuration of the light-transmissive cover  90  shall be described. 
       FIG. 6  is a perspective view of the configuration of the light-transmissive cover  90  according to Embodiment 1 of the present invention. Specifically, the figure is a perspective view for when the light-transmissive cover  90  is viewed obliquely from above. 
     Furthermore,  FIG. 7  is diagram showing the positional relationship between the light-transmissive cover  90  and the case  50  and reflecting mirror  80  according to Embodiment 1 of the present invention. Specifically, the figure is a diagram of the lamp  1  in the state in which the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  are assembled, when viewed from below. 
     As shown in these figures, the light-transmissive cover  90  includes a disc-shaped cover bottom face part  91 . In addition, case-side cover connecting parts  92 , mirror-side cover connecting parts  93 , cover side face parts  94 , and the rotation-regulating part  96  are disposed to project upward from the cover bottom face part  91 . 
     Specifically, plural case-side cover connecting parts  92  which are arranged equidistantly along a loop (in the figure, three case-side cover connecting parts  92  which are arranged equidistantly along a circle) and plural mirror-side cover connecting parts  93  which are arranged equidistantly along a loop (in the figure, three mirror-side cover connecting parts  93  which are arranged equidistantly along a circle) are provided. 
     In addition, the case-side cover connecting parts  92 , the mirror-side cover connecting parts  93 , the cover side face parts  94 , and the rotation-regulating part  96  are disposed at different positions along the same circle. In other words, they are disposed at different positions along the same circle when seen from the center of the lamp. It should be noted that all of the case-side cover connecting parts  92 , the mirror-side cover connecting parts  93 , the cover side face parts  94 , and the rotation-regulating part  96  need not be disposed along the same loop, and may be disposed along different loops. In other words, this means that they are disposed along the respective loops at different positions when seen from the center of the lamp. 
     Here, the case-side cover connecting parts  92  are connecting parts for connecting with the case  50 . Specifically, the case-side cover connecting parts  92  have a shape which allows engagement with the cover-side case connecting parts  53   a  of the case  50 . More specifically, each of the case-side cover connecting parts  92  has a shape in which the tip of the protruding part that protrudes upward from the cover bottom face part  91  projects outward. 
     Although three of the case-side cover connecting parts  92  are formed in this embodiment, the number of the case-side cover connecting parts  92  is not limited to such. It should be noted that, like the cover-side case connecting parts  53   a , from the viewpoint of stably attaching the light-transmissive cover  90  to the case  50 , it is preferable that two or more of the case-side cover connecting parts  92  be formed, and it is more preferable that three or more of the case-side cover connecting parts  92  be formed. 
     The mirror-side cover connecting parts  93  are connecting parts for connecting with the reflecting mirror  80 . Specifically, the mirror-side cover connecting parts  93  have a shape which allows engagement with cover-side mirror connecting parts  82   a  and  82   b  of the reflecting mirror  80 . More specifically, each of the mirror-side cover connecting parts  93  has a shape in which the tip of the protruding part that protrudes upward from the cover bottom face part  91  projects inward. 
     Although three of the mirror-side cover connecting parts  93  are formed in this embodiment, the number of the mirror-side cover connecting parts  93  is not limited to such. It should be noted that, like the cover-side mirror connecting parts, in order to prevent the light-transmissive cover  90  from dropping in the case where the connection between the light-transmissive cover  90  and the case  50  breaks, it is preferable that two or more of the mirror-side cover connecting parts  93  be provided, and it is more preferable that three or more of the mirror-side cover connecting parts  93  be provided. 
     Each of the cover side face parts  94  is disposed between one of the case-side cover connecting parts  92  and one of the mirror-side cover connecting parts  93 , and is a side face part of the light-transmissive cover  90  which protrudes upward from the cover bottom face part  91 . As shown in the figure, one of two rotation positioning parts  94   a  for determining the rotation position of the light-transmissive cover  90  is disposed in each of two adjacent cover side face parts  94 . The rotation positioning parts  94   a  are projecting parts which project from the corresponding cover side face parts  94  towards the inside of the light-transmissive cover  90  and are disposed at both sides of one of the mirror-side cover connecting parts  93 . 
     Specifically, the rotation positioning parts  94   a  determine the rotation position of the light-transmissive cover  90  with respect to the reflecting mirror  80 , by interfitting with the cover-side mirror connecting part  82   b  of the reflecting mirror  80 . Here, the one mirror-side cover connecting part  93  and the two rotation positioning parts  94   a  on both sides of the mirror-side cover connecting part  93  make up the mirror-side cover connecting part  95 . The mirror-side cover connecting part  95  engages with the cover-side mirror connecting part  82   b.    
     Here, rotation-regulating part  96  is a tabular part which protrudes upward from the cover bottom face  91 , for regulating the rotation of the light-transmissive cover  90 . Specifically, the rotation-regulating part  96  regulates the rotation of the light-transmissive cover  90  with respect to the case  50 , by abutting the projecting part  53   b  of the case  50 . 
     Here, as shown in  FIG. 7 , the three case-side cover connecting parts  92  and the three mirror-side cover connecting parts  93  (or two of the three mirror-side cover connecting parts  93  and the single mirror-side cover connecting part  95 ) are disposed equidistantly. In other words, the case-side cover connecting parts  92  and the mirror-side cover connecting parts  93  are disposed alternately and equidistantly so that angles R1 to R6 in the figure all have the same angles (60 degrees in the figure). 
     It should be noted that, in the forgoing description, equidistantly need not necessarily mean precisely equidistant, and is defined as a concept which includes some error. In other words, for example, an error of approximately plus or minus 10 degrees in each of the angles R1 to R6 is acceptable. 
     Next, the connecting state of the respective connecting parts of the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  shall be discussed. 
       FIG. 8  is diagram showing the connecting state between the case  50  and reflecting mirror  80  according to Embodiment 1 of the present invention. Specifically, the figure is a cross-sectional view of when the lamp  1  shown in  FIG. 7  is cut at the cross-section A-A. It should be noted that  FIG. 8  is a diagram for illustrating the connecting state between the case  50  and the reflecting mirror  80 , and omits the details of the connecting state between the case  50  and the light-transmissive cover  90 . 
     Furthermore,  FIG. 9  is diagram showing the connecting state between (i) the light-transmissive cover  90  and (ii) the case  50  and reflecting mirror  80  according to Embodiment 1 of the present invention. Specifically, the figure is a cross-sectional view of when the lamp  1  shown in  FIG. 7  is cut at the cross-section B-B. 
     First, as shown in  FIG. 9 , the light-transmissive cover  90  and the case  50  are connected through the engagement of the case-side cover connecting parts  92  and the cover-side case connecting parts  53   a . Furthermore, the light-transmissive cover  90  and the reflecting mirror  80  are connected through the engagement of the mirror-side cover connecting parts  93  and the cover-side mirror connecting parts  82   a.    
     In contrast, as shown in  FIG. 8 , the mirror-side case connecting parts  55  of the case  50  and the case-side mirror connecting parts  81   a  of the reflecting mirror  80  are disposed spaced apart, so as to engage in the case where the reflecting mirror  80  drops. In other words, the mirror-side case connecting parts  55  and the case-side mirror connecting parts  81   a  engage in the case where the connection between the light-transmissive cover  90  and the case  50  shown in  FIG. 9  breaks and the light-transmissive cover  90  drops together with the reflecting mirror  80 . 
     In this case, since the reflecting mirror  80  and the light-transmissive cover  90  are engaged as shown in  FIG. 9 , the engagement of the mirror-side case connecting parts  55  and the case-side mirror connecting parts  81   a  can prevent the dropping of not only the reflecting mirror  80  but also the light-transmissive cover  90 . 
     It should be noted that the mirror-side case connecting parts  55  and the case-side mirror connecting parts  81   a  may also be in an engaged state, that is, without being spaced apart. Furthermore, it is also acceptable that the mirror-side case connecting parts  55  and the case-side mirror connecting parts  81   a  are in an engaged state, and the case-side cover connecting parts  92  and the cover-side case connecting parts  53   a  are disposed spaced apart, or that the mirror-side cover connecting parts  93  and the cover-side mirror connecting parts  82   a  are disposed spaced apart. In any case, when the engagement between one set of the connecting parts fails, the dropping of components can be prevented since the other two sets of connecting parts become engaged. 
     As described above, according to the lamp  1  according to Embodiment 1 of the present invention, the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  are interconnected. Specifically, the lamp  1  is configured in such a way that the case-side mirror connecting parts  81   a  and the mirror-side case connecting parts  55  are connected, the cover-side case connecting parts  53   a  and the case-side cover connecting parts  92  are connected, and the mirror-side cover connecting parts  93  and the cover-side mirror connecting parts  82   a  are connected. As such, even when one connection from among the connections between the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  breaks due to deterioration caused by heat when the lamp is on, and so on, the dropping of components can be prevented. In this manner, the lamp  1  is lamp having a twofold drop-preventing function. 
     Furthermore, the lamp  1  is configured in such a way that the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  can connect with one another at the respective connection points. Specifically, the lamp  1  has a form which allows mutual engagement between: the case-side mirror connecting parts  81   a  and the mirror-side case connecting parts  55 ; the cover-side case connecting parts  53   a  and the case-side cover connecting parts  92 ; and the mirror-side cover connecting parts  93  and the cover-side mirror connecting parts  82   a . As such, in the lamp  1 , the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  can be interconnected simply, without the use of an adhesive. 
     Furthermore, the connection points of the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  of the lamp  1  are arranged equidistantly along a circle. Specifically, the lamp  1  is configured in such a way that the case-side mirror connecting parts  81   a  and the mirror-side case connecting parts  55 , the cover-side case connecting parts  53   a  and the case-side cover connecting parts  92 , and the mirror-side cover connecting parts  93  and the cover-side mirror connecting parts  82   a  are arranged equidistantly along a circle. As such, even when one connection from among the connections between the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  breaks, the dropping of components can be prevented by the other two connections which are arranged equidistantly along a circle. 
     Furthermore, the case-side cover connecting parts  92  and the mirror-side cover connecting parts  93  are arranged along their respective loops, in different positions when seen from the center of the lamp. With this, the case-side cover connecting parts  92  and the mirror-side cover connecting parts  93  can be fabricated easily during the manufacturing of the light-transmissive cover  90 . 
     Furthermore, since the light-transmissive cover  90  includes the rotation positioning parts  94   a , the rotation position of the light-transmissive cover  90  with respect to the reflecting mirror  80  can be determined easily. 
     Furthermore, since the light-transmissive cover  90  includes the rotation-regulating part  96 , the rotation position of the light-transmissive cover  90  with respect to the case  50  can be easily regulated. 
     Embodiment 2 
     Next, a lighting apparatus  100  according to Embodiment 2 of the present invention shall be described. 
       FIG. 10  is a cross-sectional view of a configuration of the lighting apparatus  100  according to Embodiment 2 of the present invention. It should be noted that the lamp  1  according to Embodiment 1 is used in the lighting apparatus according to this embodiment. Therefore, in the figure, the same reference signs are given to structural components that are the same as the structural components shown in Embodiment 1. 
     As shown in the figure, the lighting apparatus  100  is, for example, a downlight and includes lighting equipment  101 , and the lamp  1  according to Embodiment 1. The lighting equipment  101  includes: a main body which includes a reflecting plate  102  and a heat-dissipating component  104  and is configured to cover the lamp  1 ; and a socket  103  attached to the main body. 
     The reflecting plate  102  is substantially in the shape of a cup having a circular opening formed on the top face, and is configured so as to laterally surround the lamp  1 . Specifically, the reflecting plate  102  includes: as the top face, a circular flat plate part in which a circular opening is formed; and a cylinder part that is formed to have an inner diameter which gradually widens from the periphery of the flat plate part to the bottom. The cylinder part has an opening on the light-emission-side, and is configured to reflect the light from the lamp  1 . For example, the reflecting plate  102  is made of a white synthetic resin having insulation properties. It should be noted that, in order to improve reflectivity, the inner face of the reflecting plate  102  may be coated with a reflective film. Moreover, the reflecting plate  102  is not limited to a reflecting plate made of synthetic resin, and a metal reflective plate formed from a pressed metal plate may be used. 
     The socket  103  is compatible with the GH76p base, and is a disk-shaped component that supplies AC power to the lamp  1 . The socket  103  is arranged so that its upper part is inserted inside the opening formed in the flat plate part in the top face of the reflecting plate  102 . An opening part shaped to conform to the shape of the base of the support  20  is formed at the center of the socket  103 , and the top face of the lamp  1  and the bottom face of the heat-dissipating component  104  are thermally connected by installing the lamp  1  in such opening part. Furthermore, a connection hole into which an electrical connection pin  52  is inserted is formed at a position at the bottom part of the socket  103  which corresponds to the electrical connection pin  52  of the case  50 . 
     The heat-dissipating component  104  is a component which dissipates the heat transmitted from the lamp  1 . The heat-dissipating component  104  is disposed to abut the top face of the reflecting plate  102  and the top face of the socket  103 . It is preferable that the heat-dissipating component  104  be made of highly heat-conductive material such as aluminum. 
     It should be noted that the lamp  1  is installed in the socket  103  in a removable manner. 
     As described above, according to the lighting apparatus  100  according to Embodiment 2 of the present invention, the inclusion of the lamp  1  according to Embodiment 1 makes it possible to produce the same advantageous effects as in Embodiment 1. 
     Although a lamp and a lighting apparatus according to the embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments. 
     Specifically, the embodiments disclosed herein should be considered, in all points, as examples and are thus not limiting. The scope of the present invention is defined not by the foregoing description but by the Claims, and includes all modifications that have equivalent meaning to and/or are within the scope of the Claims. 
     For example, although the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  are connected by engaging with one another in the above-described embodiments, the form of connection is not limited to such engagement, and connection by interfitting is also acceptable. 
     Furthermore, although the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  are circular components in the above-described embodiments, their shape is not limited to such. For example, the case  50 , the reflecting mirror  80 , and the light-transmissive cover  90  may be components of a polygonal shape such as elliptical, quadrangular, or pentagonal. In this case, the respective connecting parts are arranged equidistantly along the elliptical or polygonal loop. 
     Furthermore, although the entirety of the reflecting mirror  80  is disposed inside the case  50 , it is also acceptable to have only part of the reflecting mirror  80  disposed inside the case  50 . Likewise, each of the heat-conducting sheet  30 , the mounting board  40 , and the circuit board  70  may be entirely or partially disposed outside the case  50 . 
     Furthermore, optical components such as a lens or reflector for focusing the light from the light-emitting unit  41 , or optical filters, and the like, for color tone-adjustment may be used in the above-described embodiments. However, such components are not essential components for the present invention. 
     Furthermore, although LEDs are used as an example of light-emitting elements in the above-described embodiments, other light-emitting elements such as semiconductor lasers or organic electro luminescence (EL) devices may also be used. 
     INDUSTRIAL APPLICABILITY 
     The lamp according to the present invention can be widely used as a lamp, or the like, that includes, for example, a GH76p base. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  Lamp 
               10  Heat-conducting sheet 
               20  Support 
               30  Heat-conducting sheet 
               40  Mounting board 
               41  Light-emitting unit 
               50  Case 
               51 ,  51   a - 51   e  Through hole 
               52 ,  52   a - 52   e  Electrical connection pin 
               53  Case side face part 
               53   a  Cover-side case connecting part 
               53   b  Projecting part 
               54  Case top face part 
               54   a - 54   c  Screw insertion part 
               55  Mirror-side case connecting part 
               60  Securing screws 
               70  Circuit board 
               80  Reflecting mirror 
               81  Reflecting mirror side face part 
               8 I a Case-side reflecting mirror connecting part 
               82  Reflecting mirror bottom face part 
               82   a ,  82   b  Cover-side reflecting mirror connecting part 
               90  Light-transmissive cover 
               91  Cover bottom face part 
               92  Case-side cover connecting part 
               93 ,  95  Mirror-side cover connecting part 
               94  Cover side face part 
               94   a  Rotation positioning part 
               96  Rotation regulating part 
               100  Lighting apparatus 
               101  Lighting equipment 
               102  Reflecting plate 
               103  Socket 
               104  Light-dissipating component