Patent Publication Number: US-2011073883-A1

Title: Led lamp

Description:
TECHNICAL FIELD 
     The present invention relates to an LED lamp. 
     BACKGROUND ART 
       FIG. 20  is a sectional view showing an example of conventional LED lamp (see Patent Document 1). The LED lamp X is used as a substitute for a fluorescent lamp to be mounted to fluorescent lighting fixtures for general purpose lighting. The LED lamp X includes a cylindrical light-transmitting cover  93 , a substrate  91 , LED modules  92  and a terminal  94 . The substrate  91  and the LED modules  92  are housed in the light-transmitting cover  93 . The substrate  91  comprises a rectangular flat plate extending in the axial direction x of the LED modules  92 . The plurality of LED modules  92  are mounted on the substrate  91 . The terminal  94  is configured to be fitted into an inlet of a socket of a fluorescent lighting fixture. Electric power is supplied from the outside of the LED lamp X to the LED modules  92  via the terminal  94 . Herein, the fluorescent lighting fixtures for general purpose lighting refer to lighting fixtures which are widely used for general indoor lighting, which utilize e.g. the commercial power supply of 100V or 200V in Japan, and to which straight-tube fluorescent lamps in accordance with JIS C7617 or circular fluorescent lamps in accordance with JIS C7618 are mounted. 
     However, in the conventional LED lamp X, the LED modules  92  are oriented in the same direction when viewed in the axial direction x, causing the light to be emitted in only one direction. Thus, the use of the LED lamp X involves a problem that light emission in a certain direction is insufficient and some areas cannot be illuminated brightly. 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     The present invention has been conceived under the circumstances described above. It is therefore an object of the present invention to provide an LED lamp which is capable of providing a wider light irradiation range as viewed in the axial direction. 
     Means for Solving the Problems 
     To solve the above-described problem, the present invention takes the following technical measures. 
     An LED lamp according to a first aspect of the present invention is elongated in an axial direction and includes a plurality of LED chips. Each of the LED chips is arranged to emit light having a main light irradiation direction directed outwards of a radial direction perpendicular to the axial direction, where the main light irradiation directions of the LED chips are different from each other as viewed in the axial direction. 
     In a preferred embodiment of the present invention, the LED lamp a further includes a metal support member supporting the LED chips and arranged inwards of the radial directions with respect to the LED chips. 
     In a preferred embodiment of the present invention, the LED lamp includes a reflective surface, where the radial directions include a first direction passing through one of the LED chips, and the reflective surface is configured to, as receding in the first direction, become farther away from the relevant LED chip in a second direction perpendicular to the first direction. 
     In a preferred embodiment of the present invention, the LED lamp includes a reflective member made of a metal and provided with the reflective surface, where the reflective member and the metal support member are connected to each other. 
     In a preferred embodiment of the present invention, the LED lamp includes at least one multiple light source in which at least two LED chips having different main light irradiation directions, among the plurality of the LED chips, are arranged at the same position in the axial direction. 
     In a preferred embodiment of the present invention, a plurality of the multiple light sources are provided and spaced apart from each other in the axial direction. 
     Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a principal portion of an LED lamp according to a first embodiment of the present invention; 
         FIG. 2  is a sectional view taken along lines II-II in  FIG. 1 ; 
         FIG. 3  is a side view of a principal portion of an LED lamp according to a second embodiment of the present invention; 
         FIG. 4  is a partially cut away plan view of an LED lamp according to a third embodiment of the present invention; 
         FIG. 5  is a partially cross-sectional perspective view of part of the LED lamp shown in  FIG. 4 ; 
         FIG. 6  is a plan view of a principal portion of the LED lamp shown in  FIG. 4 ; 
         FIG. 7  is a perspective view showing a material board used for a manufacturing process of the LED lamp shown in  FIG. 4 ; 
         FIG. 8  is a perspective view showing the step of mounting LED modules on the material board in the manufacturing process of the LED lamp shown in  FIG. 4 ; 
         FIG. 9  is a perspective view showing the step of cutting the material board in the manufacturing process of the LED lamp shown in  FIG. 4 ; 
         FIG. 10  is a perspective view showing the step of bending the cut material board in the manufacturing process of the LED lamp shown in  FIG. 4 ; 
         FIG. 11  is a front view of an LED lamp according a fourth embodiment of the present invention; 
         FIG. 12  is a sectional view taken along lines XII-XII in  FIG. 11 ; 
         FIG. 13  is a side view of the LED lamp shown in  FIG. 11 , as viewed in the axial direction; 
         FIG. 14  is a plan view showing the step of punching holes in a metal plate; 
         FIG. 15  is a perspective view showing the step of forming a support member; 
         FIG. 16  is a plan view showing the step of forming cylindrical portion at an end of the support member; 
         FIG. 17  is a plan view of the support member after a cylindrical portion is formed at each end thereof; 
         FIG. 18  is a front view showing the step of mounting Peltier devices; 
         FIG. 19  is a sectional view showing the step of attaching a substrate on a side plate portion; and 
         FIG. 20  is a sectional view of a principal portion of a conventional LED lamp. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Preferred embodiments of the present invention are described below with reference to accompanying drawings. 
       FIGS. 1 and 2  show an LED lamp according to a first embodiment of the present invention.  FIG. 1  is a perspective view of a principal portion of an LED lamp A 1  according to this embodiment.  FIG. 2  is a sectional view taken along lines II-II in  FIG. 1 . 
     The LED lamp A 1  is used as a substitute for a fluorescent lamp, for example. The LED lamp A 1  includes a cylindrical light-transmitting cover  3 , a metal support member  20 , substrates  10 A,  10 B,  10 C, LED modules  30  and reflective members  40 . The metal support member  20 , the substrates  10 A,  10 B,  10 C and the LED modules  30  are housed in the cylindrical light-transmitting cover  3 . 
     The metal support member  2  shown in  FIGS. 1 and 2  is made of A 1 , for example, and has an elongated shape. The metal support member  20  may be annular. The metal support member  20  includes a columnar portion  21 , leg portions  22 A,  22 B,  22 C and plate portions  23 A,  23 B,  23 C. The columnar portion  21  extends in a predetermined direction. In this embodiment, the direction which extends through the center of the columnar portion  21  and in which the columnar portion  21  extends is the axial direction according to the present invention. 
     The leg portions  22 A,  22 B and  22 C have a flat plate-like shape elongated in the axial direction x. When viewed in the axial direction x, the leg portions  22 A,  22 B and  22 C extend radially from the center of the columnar portion  21  in radial directions perpendicular to the axial direction x. Each of the leg portions  22 A,  22 B and  22 C is arranged to form an angle of 120 degrees with the adjacent one of the leg portions. The plate portions  23 A,  23 B and  23 C are positioned on the outer side of the leg portions  22 A,  22 B and  22 C in the radial directions, respectively. The plate portions  23 A,  23 B and  23 C are connected at right angles to the leg portions  22 A,  22 B and  22 C, respectively. 
     The substrates  10 A,  10 B and  10 C are fixed to the outer side of the plate portions  23 A,  23 B and  23 C in the radial directions, respectively. Each of the substrates  10 A,  10 B and  10 C comprises a flat plate of an elongated rectangular shape made of e.g. glass-fiber-reinforced epoxy resin. Each of these substrates is provided with metal wiring layers (now shown) formed on the obverse surface (the upper side in the figures for the substrate  10 A) and the reverse surface (the lower side in the figures for the substrate  10 A) to be spaced apart from each other, through-holes and so on. The substrates  10 A,  10 B and  10 C may be made by using aluminum covered with an insulating film. 
     As shown in  FIG. 1 , the LED modules  30  are arranged on each of the substrates  10 A,  10 B and  10 C at predetermined intervals in the axial direction x. As shown in  FIG. 2 , the LED modules  30  are mounted on the outer surfaces of the substrates  10 A,  10 B and  10 C in the radial directions. Each of the LED modules  30  includes an LED chip (light emitting diode), leads spaced apart from each other, a wire and a resin package. 
     The LED chip has a lamination structure made up of an n-type semiconductor layer, a p-type semiconductor layer and an active layer sandwiched between these layers. The LED chip can emit blue light when made of a GaN-based semiconductor. The resin package contains a fluorescent substance mixed therein. Depending on the kinds of the fluorescent substance, LED modules can emit light of different color temperatures. 
     In order for the LED module  30  to emit white light, a yellow-light emitting substance, that emits yellow light when excited by blue light, is employed as the fluorescent substance. The LED module  30  can emit white light because of the blue light from the LED chip and the yellow light from the yellow fluorescent substance. 
     The fluorescent substance may not be a yellow fluorescent substance but may be a mixture of fluorescent substances. The mixture consists of a red fluorescent substance that emits red light when excited by blue light, and a green fluorescent substance that emits green light when excited by blue light. The LED module  30  can emit white light because of the blue light from the LED chip and red light and green light from the mixture of the fluorescent substances. With this arrangement, the LED module  30  can emit white light with a higher color rendering index than when the resin package contains a yellow fluorescent substance. 
     By appropriately adjusting the mixing ratio of the fluorescent substance in the resin package, the LED module  30  can emit white light with a color temperature of 3000K (incandescent color) or white light with a color temperature of 670K (daylight color), for example. 
     In this embodiment, the LED modules  30  are so arranged as to emit light outwards in the radial directions with respect to the center of the columnar portion  21 . Specifically, for example, the LED modules  30  mounted on the substrate  10 A are arranged to emit light upward in  FIG. 2 . The LED modules  30  mounted on the substrate  10 B and the LED modules mounted on the substrate  10 C are arranged to emit light diagonally to the lower right and to the lower left in  FIG. 2 , respectively. These light irradiation directions of the LED modules  30  are indicated by arrows in the figure. These directions are the main light irradiation directions of the LED chips, defined in the present invention. As viewed in the axial direction x, the main light irradiation directions of the LED chips defined in the present invention refer to a direction extending through the center of the range irradiated with the light from the LED modules  30 . 
     The reflective member  40  is connected to each end of the plate portion  23 A,  23 B,  23 C. An angle of about 150 degrees is defined between each of the reflective members  40  and the relevant plate portion  23 A,  23 B,  23 C. The reflective member  40  is made of e.g. A 1 . The reflective member  40  has a reflective surface  41 . The reflective surface  41  causes the light emitted from the LED modules  30  to travel in the radial direction. As shown in the sectional view of  FIG. 2 , the reflective surface  41  is configured in a manner such that as proceeding away from the columnar portion  21  in the radial direction extending through the relevant LED module  30 , the reflective surface  41  becomes gradually farther away from the LED modules  30  in the direction which is perpendicular to the radial direction. Although the reflective surface  41  in this embodiment is a flat surface, it may be a curved surface, for example. 
     The light-transmitting cover  3  is made of a transparent material. Thus, the light-transmitting cover  3  allows light from the LED modules  30  to pass therethrough. 
     The advantages of the LED lamp A 1  are described below. 
     The LED lamp A 1  according to the present embodiment provides a wider light irradiation range, as viewed in the axial direction x. Heat generated at the LED chips is dissipated to the outside of the LED lamp A 1  from the metal support member  20 , whereby heat dissipation of the LED lamp A 1  is promoted. Part of the light emitted from the LED modules  30  is reflected by the reflective surfaces  40  to travel outwards in the radial directions. This enhances the luminance of the light emitted from the LED lamp A 1 . Heat generated at the LED chips is dissipated to the outside of the LED lamp A 1  also from the reflective members  40 . This further promotes the heat dissipation of the LED lamp A 1 . 
       FIGS. 3-19  illustrate other embodiments of the LED lamp according to the present invention. In these figures, the elements which are identical or similar to those of the foregoing embodiment are designated by the same reference signs as those used for the foregoing embodiment. 
       FIG. 3  shows an LED lamp according to a second embodiment of the present invention. The LED lamp A 2  of this embodiment comprises a cylindrical bar  50  around which a tape light  60  carrying LED modules  30  is wound. The LED lamp A 2  having this structure can emit light from the entirety of the circumference, as viewed in the axial direction x. 
     The LED lamp according to the present invention is not limited to the foregoing embodiments. The specific structure of each part of the LED lamp according to the present invention can be varied in design in various ways. For instance, a plurality of LED modules may be provided on each of the two faces of a single substrate. In this case, it is not necessary to prepare a plurality of substrates to make a single LED lamp, which allows reducing the manufacturing cost of the LED lamp. 
       FIGS. 4-6  illustrate an LED lamp according to a third embodiment of the present invention. The LED lamp A 3  of this embodiment includes a plurality of light emitting modules  1 , a metal support member  20 , a light-transmitting cover  3 , a bracket  4  and a base  5 . The LED lamp A 3  is mounted to a non-illustrated lighting fixture adapted to circular fluorescent lamps. 
     Each of the light emitting modules  1  is a tubular member comprising a plurality of substrates  10  connected to each other at the longitudinal edges. Each of the substrates  10  is made of a glass-fiber-reinforced epoxy resin, for example, and has an elongated rectangular shape. Adjacent ones of the substrates  10  are connected to each other at their longitudinal edges via a thin-walled portion. On each of the substrates  10 , a plurality of LED modules  30  are mounted, as oriented outwards, at equal intervals in the longitudinal direction of the substrate. Each of the LED modules  30  includes an LED chip (not shown) connected to a lead made of a metal (not shown) and sealed with a light-transmitting resin (not shown). These LED modules  30  are connected to a wiring pattern (not shown) formed on the substrate  10 . The light emitting modules  1  are attached to the metal support member  20 . 
     In this embodiment, as an example, the light emitting modules  1  each comprising five substrates  10  are attached to the metal support member  20 . The metal support member  20  and the bracket  4  are formed with wiring patterns (now shown) electrically connected to the substrates  10 . With this arrangement, electric power from a power supply is supplied from the base  5  to the LED modules  30  via the bracket  4 , the metal support member  20  and the substrates  10 . The light emitting modules  1  are housed in the light-transmitting cover  3 . Each light emitting module  1  exhibits a substantially hexagonal cross section when viewed as an integral part with the metal support member  20 . Thus, with the plurality of light emitting modules  1 , light from the LED chips (not shown) incorporated in the LED modules  30  is directed in various directions in which the substrates  10  are oriented. 
     The metal support member  20  is made of e.g. A 1  and bonded to the substrates  10  that form two ends of each light emitting module  1 . The metal support member  20  is formed with a plurality of projections  24 . The projections  24  are exposed from the light-transmitting cover  3  and the bracket  4  toward the center. With this metal support member  20 , heat generated from the LED modules  30  is efficiently transmitted to the metal support member  2  via the substrates  10 . Since the projections  24  exposed to the outside increases the contact area of the metal support member  20  with air, heat is dissipated quickly. The main body and projections of the heat dissipation member may be made of different metals, and a Peltier device may be provided at the portion where these are bonded together to enhance the heat dissipation effect. 
     The light-transmitting cover  3  is made of e.g. glass or a polycarbonate resin and allows the light emitted from the light emitting modules  1  to pass therethrough to the outside while protecting the light emitting modules  1  housed therein. The light-transmitting cover  3  is formed with an opening on the inner circumferential side. The base  5  is attached to a portion of the light-transmitting cover  3 . A power supply connector of a non-illustrated lighting fixture is connected to the base  5 . 
     The bracket  4  is annular and attached to the opening on the inner circumferential side of the light-transmitting cover  3 . The metal support member  20  is bonded to the bracket  4 . With the support by the bracket  4 , the light emitting modules  1  are arranged within the light-transmitting cover  3  annularly at predetermined intervals. The bracket  4  is electrically connected to the base  5 , thereby also serving as a path to supply electric power to the light emitting modules  1 . 
       FIGS. 7-10  show an embodiment of a method for manufacturing the LED lamp  3 . 
     First, as shown in  FIG. 7 , a rectangular material board  100  which can provide a plurality of substrates  10  is prepared. Then, a plurality of continuous rectangle regions Cr, each consisting of a plurality of portions to become substrates  10  connected together at the longitudinal edges thereof, are defined in the material board  100 . In the figure, the boundaries between the rectangular portions Sr, which correspond to the substrates  10 , are indicated by single-dashed lines, whereas the outer edges of the continuous rectangle regions Cr are indicated by broken lines. 
     Then, as shown in  FIG. 8 , a plurality of LED modules  30  are mounted on the material board  100  in each of the rectangular portions Sr at equal intervals in the longitudinal direction of the rectangular portion. 
     Then, as shown in  FIG. 9 , by using e.g. a dicing saw or laser, grooves are formed in the material board  100  along the boundary lines L 1  between the rectangular portions Sr indicated by the single-dashed lines. As for the continuous rectangle regions Cr overall, the material board  100  is cut along the cutting lines L 2  corresponding to the outer edges of these regions indicated by the broken lines. As a result, the continuous rectangle regions Cr are cut out of the material board  100 . In this state, each of the continuous rectangle regions Cr includes a plurality of rectangular portions Sr connected to each other via thin-walled portions where the grooves are formed along the boundary lines L 1 . 
     Then, as shown in  FIG. 10 , each of the continuous rectangle regions Cr cut out of the material board  100  is formed into a tubular shape by bending along the grooves, which serve as the boundaries between the substrates (rectangular portions Sr). In this way, a light emitting module  1  is obtained in which the LED modules  30  on each of the substrates  10  are oriented to the outside. 
     In the LED lamp A 3  according to this embodiment, a tubular light emitting module  1  is obtained by bending the continuous rectangle region Cr at the boundaries between the rectangular portions Sr. Since the plurality of light emitting modules  1  are arranged annularly, light is emitted uniformly in various directions in which the substrates  10  are oriented even when each of the LED modules  30  has high directivity. 
     As for the manufacture of the LED module  1 , the tubular light emitting module  1  can be completed just by cutting a continuous rectangle region Cr out of a rectangular material board  100  and bending the continuous rectangle region Cr along grooves. This allows reducing the remnants of the material board as small as possible as compared with cutting a curved substrate out of a rectangular material board, for example. Thus, the productivity and yield are easily enhanced. 
     The present invention is not limited to the foregoing embodiment. The specific structure of each part of the LED lamp according to the present invention can be varied in design in various ways. 
     For instance, one or a plurality of light emitting modules  1  according to the foregoing embodiment may be housed in a light-transmitting cover of a straight-tube shape and mounted to a non-illustrated lighting fixture adapted to straight-tube fluorescent lamps. 
     The elongated rectangle regions may be defined in the material board such that no space is left between the adjacent elongated rectangle regions and the cutting lines lie on the boundary between the rectangle regions. This arrangement allows a larger number of substrates connected to each other at the longitudinal edges to be cut out of a single material board. 
     The LED chips may be mounted directly on the substrate. 
       FIGS. 11-13  show an LED lamp according to a fourth embodiment of the present invention. The LED lamp A 4  shown in  FIGS. 11-13  includes a metal support member  20 , substrates  10 A,  10 B,  10 C, a plurality of LED modules  30 , a plurality of screws  70 , a plurality of nuts  71  and a plurality of Peltier devices  80 . The LED lamp A 4  may be housed in a light-transmitting cover (not shown) of a straight-tube shape and mounted to a fluorescent lighting fixture for general purpose lighting for use as a substitute for a straight-tube fluorescent lamp. This LED lamp has an elongated shape extending in the axial direction x overall. As shown in  FIG. 12 , the LED lamp  4  has a 120-degree rotational symmetry with respect to a non-illustrated axis extending in the axial direction x. For convenience of explanation, the height direction z of the substrate  10 A is indicated in  FIG. 11  in addition to the axial direction x, whereas the width direction y and the height direction z of the substrate  10 A are indicated in  FIGS. 12 and 13 . 
     The metal support member  20  is made of e.g. A 1 , includes side plate portions  25 A,  25 B,  25 C, a bonding portion  28  and cylindrical portions  29 , and has a tubular shape elongated in the axial direction x. 
     The side plate portion  25 A has a constant width in the width direction y and a constant thickness of about 1 to 2 mm in the height direction z, and is elongated in the axial direction x. An edge of the side plate portion  25 A in the width direction y is connected to the side plate portion  25 B via a bent portion  26   a . The side plate portion  25 A and the side plate portion  25 B form an angle of 60° at the bent portion  26   a . The other edge of the side plate portion  25 A in the width direction y is connected to the side plate portion  25 C via a bent portion  26   b . The side plate portion  25 A and the side plate portion  25 C form an angle of 60° at the bent portion  26   b . As shown in  FIG. 12 , the side plate portions  25 B and  25 C each have a configuration obtained by turning the side plate portion  25 A through 120° in different directions. An edge of the side plate portion  25 B and an edge of the side plate portion  25 C are welded together at the bonding portion  28 . Peltier devices  80  are attached to the inner surfaces of the side plate portions  25 A,  25 B, and  25 C at positions close to the ends spaced in the axial direction x. Each of the side plate portions  25 A,  25 B and  25 C is formed with a plurality of punched holes  27 . 
     The punched holes  27  are formed to penetrate the side plate portions  25 A,  25 B and  25 C in the thickness direction. For instance, the punched holes  27  are so formed that five punched holes are aligned in each row extending in the width direction of the side plate portions  25 A,  25 B and  25 C. 
     As shown in  FIG. 13 , the cylindrical portions  29  are annular as viewed in the axial direction x and provided at each end of the metal support member  20  in the axial direction x. A cylindrical base (not shown), for example, is attached to the cylindrical portions  29 . 
     The substrates  10 A,  10 B and  10 C are made of e.g. glass-fiber-reinforced epoxy resin and have a rectangular shape having a constant width and elongated in the axial direction x. The substrate  10 A is fixed to the outer surface of the side plate portion  25 A with three screws  70  and three nuts  71 . The substrate  10 B is fixed to the outer surface of the side plate portion  25 B with three screws  70  and three nuts  71 . The substrate  10 C is fixed to the outer surface of the side plate portion  25 C with three screws  70  and three nuts  71 . As illustrated in  FIG. 11 , of the three screws  70  that fix the substrate  10 C, two screws fix each end of the substrate  10 C in the axial direction x, whereas one screw fixes a central portion of the substrate  10 C in the axial direction x. The two screws  70  fixing each end and the screw  70  fixing the central portion are spaced apart from each other in the width direction of the substrate  10 C, which is favorable for the reliable fixing of the substrate  10 C to the side plate portion  25 C. The substrates  10 A and  10 B are also reliably fixed to the side plate portions  25 A and  25 B in the similar manner. As illustrated in  FIG. 12 , each of the screws  70  penetrates the punched hole  27 . 
     Each of the LED modules  30  includes an LED device  31 , metal leads  32  and  33  spaced apart from each other, a wire  34  and a resin package  35 . The LED modules  30  are mounted on each of the substrates  10 A,  10 B and  10 C to be aligned in the axial direction x. The LED modules  30  mounted on the substrate  10 A are exemplarily described below. 
     The LED device  31  may have a lamination structure made up of an n-type semiconductor layer, a p-type semiconductor layer and an active layer sandwiched between these layers. The LED device  31  can emit blue light when made of an AlGaInP-based semiconductor. The LED device  31  is mounted on the lead  32  arranged on one side of the substrate  10 A in the width direction y. The upper surface of the LED device  31  is connected, via the wire  34 , to the lead  33  arranged on the other side of the substrate  10 A in the width direction. 
     The resin package  35  protects the LED device  31  and the wire  34 . The resin package  35  is made of e.g. an epoxy resin that allows light emitted from the LED device  31  to pass therethrough. Mixing in the resin package  35  a fluorescent substance that emits yellow light when excited by blue light enables the LED module  30  to emit white light. 
     A method for manufacturing the LED lamp A 4  is described below with reference to  FIGS. 14-19 . 
     First, as shown in  FIG. 14 , a metal plate  10  is prepared which has a thickness of 1 to 2 mm and a constant width in the width direction y, and is elongated in the axial direction x. For instance, the metal plate  10  is made of A 1 . Then, a plurality of punched holes  27  are formed in the metal plate  10  to be uniformly distributed. In this embodiment for example, 15 punched holes are aligned in the width direction y. Punched holes  27  are not formed in the regions adjacent to each end of the metal plate  10  in the axial direction x. The punched holes  27  can be easily formed by using e.g. a punch press machine. 
     Then, a metal support member  20  is made from the metal plate  10 . Specifically, in this process, the metal plate  10  is first bent 60° along two imaginary lines extending in the axial direction x and indicated in  FIG. 14 , whereby side plate portions  25 A,  25 B and  25 C are formed. Then, the respective edges of the side plate portions  25 B and  25 C, which correspond to the two ends of the original metal plate  10  in the width direction y, are bonded together. Thus, a metal support member  20  shaped like a triangular tube as shown in  FIG. 15  is obtained. The above-described bonding of the edges of the side plate portions  25 B and  25 C is performed by welding, for example. Then, as shown in  FIG. 16 , a cylindrical portion  29 , which is annular as viewed in the axial direction x, is formed at an end of the metal support member  20 . The cylindrical portion  29  is formed by pushing a rod, which is circular as viewed in the axial direction x, into an end of the metal support member  20  in the axial direction x. As shown in  FIG. 17 , a cylindrical portion  29  is formed also at the other end of the metal support member  20 . The metal support member  20  of the LED lamp A 4  is completed by the above-described process. 
     Then, Peltier devices  80  are mounted as shown in  FIG. 18 . Specifically in this process, six Peltier devices  80  are put into the metal support member  20  from the cylindrical portions  29 , and two Peltier devices, for example, are bonded to each of the side plate portions  25 A,  25 B and  25 C at appropriate portions of the inner surface. The Peltier devices  80  may be mounted before the metal plate  10  is bent. 
     Then, as shown in  FIG. 19 , a substrate  10 A is attached to the side plate portion  25 A. It is to be noted that the substrate  10 A has a plurality of LED modules  30  mounted thereon in advance. Specifically in this process, three screws  70  are inserted into the substrate  10 A, and the screws  70  are then inserted through the punched holes  27 . Thereafter, a nut  71  is attached to the end of each screw  70 , whereby the substrate  10 A is fixed to the side plate portion  25 A. In the above-described process, one of the screws  70  is inserted into the substrate  10 A at a central position in the axial direction x and close to an end in the width direction y, whereas the other two screws  70  are inserted in the substrate  10 A at positions close to the two ends in the axial direction x and close to the other end in the width direction y. 
     Similarly to the attaching process of the substrate  10 A, the substrate  10 B and the substrate  10 C are attached to the side plate portion  25 B and the side plate portion  25   c , respectively, whereby the LED lamp A 4  shown in  FIGS. 11-13  is completed. 
     The advantages of the LED lamp A 4  are described below. 
     In the LED lamp A 4 , the LED modules  30  mounted respectively on the substrates  10 A,  10 B and  10 C emit light in different directions. Thus, the LED lamp A 4  can emit light similar to that of a fluorescent lamp and is hence suitable for use as a substitute for a tubular fluorescent lamp. 
     Since the substrates  10 A,  10 B and  10 C are directly attached to the metal support member  20  made of a relatively thin single metal plate  10 , the weight of the lamp is relatively small. The provision of the punched holes  27  in the side plate portions  25 A,  25 B and  25 C also contributes to the reduction in weight of the LED lamp A 4 . 
     Since the metal support member  20  of this embodiment is formed with a plurality of punched holes  27  and hollow, the metal support member also functions effectively as a heat dissipation member for cooling the heat generated from the LED modules  30 . The provision of the Peltier devices  80  on the inner surfaces of the side plate portions  25 A,  25 B and  25 C further cools the substrates  10 A,  10 B and  10 C effectively. Thus, the temperature of the substrates  10 A,  10 B,  10 C and the LED modules  30  does not rise excessively, so that the LED lamp A 4  is unlikely to break down and provides stable illumination. 
     Moreover, in this embodiment, since each end of the metal support member  20  in the axial direction x is provided with the cylindrical portion  29 , a cylindrical base used for fluorescent lighting fixtures for general purpose lighting can be easily attached. Thus, the LED lamp A 9  is suitable for use as a substitute for a straight-tube fluorescent lamp. 
     In this embodiment, the metal support member  20  is easily formed by bending a metal plate  10  and welding the two edges together. Thus, the manufacturing process is simple, and the manufacturing cost can be reduced. 
     In this embodiment, in fixing the substrates  10 A,  10 B and  10 C to the side plate portions  25 A,  25 B and  25 C with screws  70 , the punched holes  27  formed in advance are utilized. Thus, the attaching work is facilitated. 
     The LED lamp according to the present invention is not limited to the foregoing embodiment. The specific structure of each part of the LED lamp according to the present invention can be varied in design in various ways. For instance, although the metal support member  20  in the foregoing embodiment is substantially shaped like a triangular tube, the metal support member may have a tubular shape having other polygonal cross sections such as a rectangular cross section. 
     Although the LED lamp A 4  of the foregoing embodiment is structured as a substitute for a straight-tube fluorescent lamp, an LED lamp usable as a substitute for a circular fluorescent lamp can also be provided according to the present invention. This can be achieved by disposing a plurality of LED lamps each having a relatively short metal support member  20  in an annular arrangement.