Abstract:
Provided is a light-emitting device that aims not to affect a service life and characteristics of light emission by releasing heat from a substrate on that a plurality of LED elements mounted, and the LED elements generate the heat. 
     A light-emitting device includes: a first electrode and a second electrode formed on the upper surface of a substrate with a gap between the first electrode and the second electrode, the gap being provided at a central portion of the upper surface of the substrate; at least one first light-emitting diode element mounted on the first electrode; and at least one second light-emitting diode element mounted on the second electrode. The first light-emitting diode element includes a pair of element electrodes on an upper surface of the first light-emitting diode element and the second light-emitting diode element includes a pair of element electrodes on an upper surface of the second light-emitting diode element. The first light-emitting diode element is connected by a wire to the first electrode and/or the second electrode. The second light-emitting diode element is connected by a wire to the first electrode and/or the second electrode.

Description:
FIELD  
       [0001]    The present invention relates to a light-emitting device, and more specifically, to a light-emitting device configured such that a plurality of light-emitting diode elements is used as light sources for various illumination purposes. 
       BACKGROUND 
       [0002]    As a result of the advent of a long-life blue light-emitting diode with low power consumption in recent years, a light-emitting diode (LED) element has been mounted widely not only on various illumination devices but also on many electronic devices typified by mobile phones and various control devices. If used as a light source of such illumination devices, key illumination of electronic devices, and backlight, for example, a single LED element cannot provide a sufficient amount of light. Accordingly, a plurality of LED elements is arranged in a light-emitting device being employed. 
         [0003]    Japanese Patent Application Laid-Open No. 2009-283653 discloses a light-emitting device known as an example of the aforementioned conventional device. As shown in  FIG. 12 , this light-emitting device includes a substrate  1  composed of a metal plate divided into a first portion  2  and a second portion  3  with a gap  8  provided therebetween, a plurality of LED elements  5  mounted on the second portion  3  of the substrate  1  and electrically connected to the first portion  2  through wires  4 , a reflecting frame  6  surrounding the LED elements  5 , and a light-transmitting member  7  sealing the LED elements  5 . 
         [0004]    The conventional light-emitting device with this structure allows heat generated due to the light emission of the LED elements  5  to be dissipated from the substrate  1  composed of the metal plate or the reflecting frame  6 . 
       CITATION LIST 
     Patent Literature 
       [0005]    Patent Literature 1: Japanese Patent Application Laid-Open No. 2009-283653 
       SUMMARY 
     Technical Problem 
       [0006]    In the conventional light-emitting device described in Japanese Patent Application Laid-Open No. 2009-283653, however, the LED elements  5  are mounted only on the second portion  3  of the substrate  1 . Accordingly, heat generated due to the light emission of the LED elements  5  concentrates at the second portion  3 , leading to the fear that the heat will not be dissipated from the substrate  1  effectively. In particular, if more LED elements  5  are mounted on the second portion  3 , a great amount of heat is generated in the second portion  2 . This may adversely affect the service life of the light-emitting device. Additionally, if more LED elements  5  are mounted on the second portion  3 , a distance between adjacent LED elements  5  is shortened. In this case, light rays emitted from the LED elements  5  interfere with each other, so that light emission characteristics may be affected adversely. 
         [0007]    There is an object of the invention to provide a light-emitting device that aims not to affect a service life and characteristics of light emission by releasing heat from a substrate on that a plurality of LED elements mounted, and the LED elements generate the heat. 
       Solution to Problem 
       [0008]    In order to solve the aforementioned problem, alight-emitting device of the invention includes: a substrate; a first electrode and a second electrode formed on the entire upper surface of the substrate with a gap between the first electrode and the second electrode, the gap being provided at a central portion of the upper surface of the substrate; at least one first light-emitting diode element mounted on the first electrode; and at least one second light-emitting diode element mounted on the second electrode. The first light-emitting diode element includes a pair of element electrodes as a first element electrode and a second element electrode on an upper surface of the first light-emitting diode element and the second light-emitting diode element includes a pair of element electrodes as a first element electrode and a second element electrode on an upper surface of the second light-emitting diode element. The first light-emitting diode element is connected by a wire to at least one of the first electrode and the second electrode, and the second light-emitting diode element is connected by a wire to at least one of the first electrode and the second electrode. 
         [0009]    According to one embodiment of the present invention, the first element electrode of the pair of element electrodes of the first light-emitting diode element is connected by a wire to the second electrode, and the second element electrode of the pair of element electrodes of the first light-emitting diode element is connected by a wire to the first electrode. The first element electrode of the pair of element electrodes of the second light-emitting diode element is connected by a wire to the first electrode, and the second element electrode of the pair of element electrodes of the second light-emitting diode is connected by a wire to the second electrode. According to such a connection mentioned above, the first and second light-emitting diode elements are electrically connected in parallel to each other. 
         [0010]    According to another embodiment of the invention, a first element electrode of the pair of element electrodes of the first light-emitting diode element is connected to a second element electrode of the second light-emitting diode element, and the second element electrode of the pair of element electrodes of the first light-emitting diode element is connected by a wire to the first electrode. 
         [0011]    The second element electrode of the pair of element electrodes of the second light-emitting diode element is connected to the first element electrode of the first light-emitting diode element, and first element electrode of the pair of element electrodes the second light-emitting diode element is connected by a wire to the second electrode. According to such a connection, the first light-emitting diode element and the second light-emitting diode element are electrically connected in series. 
         [0012]    According to still another embodiment, the substrate includes an elongated shape, the first electrode includes an elongated shape extending along the elongated shape of the substrate and the second electrode includes an elongated shape extending along the elongated shape of the substrate, an elongated gap in the form of a slit is provided between the first electrode and the second electrode, a plurality of the first light-emitting diode elements are mounted on the first electrode and a plurality of the second light-emitting diode elements are mounted on the second electrode, the first light-emitting diode elements and the second light-emitting diode elements are disposed to be a plurality of pairs each with one first light-emitting diode element and one second light-emitting diode element; and in each pair of the plurality of pairs, the first light-emitting diode element is electrically connected by a wire, and the second light-emitting diode element is electrically connected to at least one of the first electrode and the second electrode by a wire. 
         [0013]    According to still another embodiment, the first includes a first inner portion adjacent to the gap and the second electrode includes a second inner portion adjacent to the gap, and a first outer portion positioned outside of the first inner portion, a second outer portion positioned outside of the second inner portion. The first inner portion of first electrode includes a first inner edge defining one side of the gap between the first electrode and the second electrode, the second inner portion of second electrode includes a second inner edge defining another side of the gap between the first electrode and the second electrode. The first outer portion of the first electrode includes a first outer edge at an opposite side of the first inner edge of the first inner portion, and is an area positioned outside of a center line between the first inner edge and the first outer edge, the second outer portion of the second electrodes includes a second outer edge at an opposite side of the second inner edge. The first light-emitting diode element is mounted on the first outer portion of the first electrode, and is connected by a wire to at least one of the first inner portion of the first electrode and the second inner portion of the second electrode. The second light-emitting diode element is mounted on the second outer portion of the second electrode, and is connected by a wire to at least one of the first inner portion of the first electrode and the second inner portion of the second electrode. 
       Advantageous Effects of Invention 
       [0014]    According to the present invention, the first electrode and the second electrode are arranged with a gap between the first electrode and the second electrode, the gap being provided at a central portion of the substrate, and the first LED element is disposed on the first electrode and the second LED element is disposed on the second electrode. Thus, heat generated from the LED elements that emit light is allowed to be dissipated from the substrate through the first electrode on that the first LED elements are mounted and through the second electrode on that the second LED element is mounted. This enhances the effective dissipation of heat, and it is possible to avoid an influence caused by heat generated by the first and second LED elements. 
         [0015]    Further, if the first LED element in a pair is arranged on the first outer portion of the first electrode and the second LED element in the pair is arranged on the second outer portion of the second electrode, a distance from the first LED element to the gap is increased and a distance from the second LED element to the gap is increased. Accordingly, the amount of light emission from the first LED element and the second LED element affecting an upper surface of the substrate appearing in the gap can be reduced, and thus, it is possible to avoid a deterioration of substrate caused by light exposure effectively. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0016]      FIG. 1  is a plan view showing a light-emitting device according to a first embodiment of the present invention. 
           [0017]      FIG. 2  is a side view of the light-emitting device illustrated in  FIG. 1 . 
           [0018]      FIG. 3  is a plan view showing a light-emitting device according to a second embodiment of the present invention. 
           [0019]      FIG. 4  is a plan view showing a light-emitting device according to a third embodiment of the present invention. 
           [0020]      FIG. 5  is a plan view showing a light-emitting device according to a fourth embodiment of the present invention. 
           [0021]      FIG. 6  is a plan view showing a light-emitting device according to a fifth embodiment of the present invention. 
           [0022]      FIG. 7  is a side view of the light-emitting device illustrated in  FIG. 6 . 
           [0023]      FIG. 8  is a plan view showing a light-emitting device according to a sixth embodiment of the present invention. 
           [0024]      FIG. 9  is a plan view showing a light-emitting device according to a seventh embodiment of the present invention. 
           [0025]      FIG. 10  is a plan view showing a light-emitting device according to an eighth embodiment of the present invention, in a state where a large number of LED element pairs are arranged. 
           [0026]      FIG. 11  is a plan view showing a light-emitting device according to a ninth embodiment of the present invention, in a state where a large number of LED element pairs are arranged. 
           [0027]      FIG. 12  is a plan view showing an example of a conventional light-emitting device. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0028]      FIGS. 1 and 2  show a light-emitting device  10  according to a first embodiment of the present invention. The light-emitting device  10  according to the present embodiment shows a structure where at least two LED elements are connected in parallel with each other and configured to be one pair of LED elements, as an embodiment. 
         [0029]    As shown in  FIGS. 1 and 2 , the light-emitting device  10  of the present embodiment includes a substrate  11 , a first electrode  12  and a second electrode  13  that are adjacently arranged on the upper surface of the substrate  11  with a gap  11   a  between the first electrode  12  and the second electrode  13 , and a first LED element  14  is mounted on the first electrode  12  and a second LED element  15  is mounted on the second electrode  13 . The first electrode  12  includes a first upper surface electrode  12   a  and a first lower surface electrode  12   c  electrically connected to the first upper surface electrode  12   a  via a first through-hole  12   b,  and the second electrode  13  includes a second upper surface electrode  13   a  and a second lower surface electrode  13   c  electrically connected to the second upper surface electrode  13   a  via a second through-hole  13   b . The first lower surface electrode  12   c  and the second lower surface electrode  13   c  are configured to be power supply terminals. 
         [0030]    The first LED element  14  is arranged on the first electrode  12  at a slightly inward from a substantially central area of the first electrode  12  above the first through hole  12   b,  and the second LED element  15  is arranged on the second electrode  13  at a slightly inward from a substantially central area of the second electrode  13  above the second through-hole  13 . In other words, the first LED element  14  is arranged on and adhered through an adhesive such as a heat-conductive adhesive to the first electrode with the first LED element  14  insulated from the first electrode, and the second LED element  15  is arranged on and adhered through an adhesive such as a heat-conductive adhesive to the second electrode with the second LED element  15  insulated from the second electrode. 
         [0031]    The first LED element  14  includes a pair of element electrodes on an upper surface of the first LED element  14 , the second LED element  15  includes a pair of element electrodes on an upper surface of the second LED element  15 . More specifically, the first LED element  14  includes a p-element electrode as a first element electrode  14   a  and an n-element electrode as a second element electrode  14   b  on the upper surface of the first LED element  14 . The second LED element  15  includes a p-element electrode as a first element electrode  15   a  and an n-element electrode as a second element electrode  15   b  on the upper surface of the second LED element  15 . 
         [0032]    In the first LED element  14 , the first element electrode  14   a  that is the p-element electrode is electrically connected by a wire  16   a  to an inner portion of the second electrode  13 , and the second element electrode  14   b  that is the n-element electrode  14   b  is electrically connected by a wire  16   b  to an outer portion of the first electrode  12 . In the second LED element  15 , the second element electrode  15   b  that is the n-element electrode  15   b  is electrically connected by a wire  17   b  to an inner portion of the first electrode  12 , and the first element electrode that is the p-element electrode  15   a  is electrically connected by a wire  17   a  to an outer portion of the second electrode  13 . In this way, the first LED element  14  and the second LED element  15  are electrically connected in parallel 
         [0033]    The substrate  11  is a glass epoxy resin substrate, for example. As described above, the first through-hole  12   b  electrically connecting the first upper surface electrode  12   a  and a first lower surface electrode  12   c  of the first electrode  12  is provided in the substrate  11 , and the second through-hole  13   b  electrically connecting the first upper surface electrode  13   a  and a second lower surface electrode  13   c  of the second electrode  13  is provided in the substrate  11 . 
         [0034]    A sealing resin  19  covering the first LED element  14  and the second LED element  15 , the first electrode  12  and the second electrode  13 , and the wires  16   a,    16   b,    17   a  and  17   b  is disposed on the upper surface of the substrate  11 . A transparent silicone resin or a light-transmitting silicone resin may be used as the sealing resin  19 . 
         [0035]    As described above, in the light-emitting device  10  of the present embodiment, the first electrode  12  and the second electrode  13  are arranged on the upper surface of the substrate  11  with the gap  11   a  between the first electrode  12  and the second electrode  13  provided at the central portion of the upper surface of the substrate  11 , and the first LED element  14  is disposed on the first electrode  12  and the second LED element  15  is disposed on the second electrode  13 , respectively. Thus, heat generated from the first LED element  14  is allowed to be effectively dissipated through the first electrode  12  on that the first LED element  14  is mounted, and heat generated from the second LED electrode  13  is allowed to be effectively dissipated through the second electrode  13  on that the second LED element  15  is mounted. Further, if the first LED element  14  is mounted on the first upper surface electrode of the first electrode  12  to cover from above the first through-hole  12   b  that is filled with a heat conductor  18  such as a solder and the second LED element  15  is mounted on the second upper surface electrode of the second electrode  13  to cover from above the second through-hole  13   b  that is filled with the heat conductor  18  such as a solder, heat generated from the first LED element and the second LED element can be released the heat conductor  18 . Accordingly, it is possible to enhance the heat releasing efficiency. 
       Second Embodiment 
       [0036]      FIG. 3  shows a light-emitting device  20  according to a second embodiment of the present invention. The light-emitting device  20  of the present embodiment includes a substantially same structure as that of the first embodiment, except the wire connection in that the wire  16   b  connects the n-element electrode  14   b  of the first LED element  14  to the first electrode  12 , and the wire  17   a  connects the p-element electrode  15   a  of the second LED element  15  to the second electrode  13 , are the wires  16   b  and  17   a  are bonded to positions on the first electrode and the second electrode, the positions here being different from the corresponding bonding positions of the first embodiment. Accordingly, here are the same constituent elements denoted by the same reference numerals, and will not be described in detail. 
         [0037]    As shown in  FIG. 3 , in the light-emitting device  20  according to the present embodiment, the wire  16   b  connecting the n-element electrode  14   b  of the first LED element  14  and the first electrode  12  is bonded to a first inner portion of the first electrode  12 , more specifically, bonded to a position adjacent to a position where the wire  17   b  electrically connecting the n-element electrode  15   b  of the second LED element  15  is bonded to the first electrode  12 . Meanwhile, the wire  17   a  connecting the p-element electrode  15   a  of the second LED element  15  and the second electrode  13  is bonded to a second inner portion of the second electrode  13 , more specifically, bonded to a position adjacent to a position where the wire  16   a  electrically connecting the p-element electrode  14   a  of the first LED element  14  is bonded to the second electrode  13 . In this way, the first LED element  14  and the second LED element  15  are electrically connected in parallel. 
         [0038]    In the present embodiment, the position of the first LED element  14  mounted on the first electrode  12  and the position of the second LED element  15  mounted on the second electrode  13  are the same as the those corresponding positions of the first LED element and the second LED element in the first embodiment. Accordingly, as shown in  FIG. 3 , the size of the substrate  11  can be reduced from the size of the substrate the first embodiment, and thus, the size of the light-emitting device  20  can be reduced. 
       Third Embodiment 
       [0039]      FIG. 4  shows a light-emitting device  30  according to a third embodiment of the present invention. The light-emitting device  30  of the present embodiment includes a substantially same structure as that of the second embodiment, except the wire connection in that the p-element electrode  14   a  of the first LED element  14  and the n-element electrode  15   b  of the second LED element  15  are directly connected by a single wire  31 . Accordingly, the same constituent elements are denoted by the same reference numerals, and will not be described in detail. In the present embodiment, the first LED elements  14  and the second LED element  15  is connected electrically in series. 
       Fourth Embodiment 
       [0040]      FIG. 5  shows a light-emitting device  40  according to a fourth embodiment of the present invention. The light-emitting device  40  of the present embodiment includes a substantially same structure as that of the third embodiment, except that a third electrode  41  is provided in the gap  11   a  between the first electrode  12  and the second electrode  13 , for example in a central area of the gap  11   a  as shown in the drawing, and that the p-element electrode  14   a  of the first LED element  14  and the n-element electrode  15   b  of the second LED element  15  are connected through the third electrode  41 . Accordingly, the same constituent elements are denoted by the same reference numbers, and will not be described in detail. 
         [0041]    The third electrode  41  is electrically isolated from the first electrode  12  and the second electrode  13 . The third electrode  41  is connected to the p-element electrode  14   a  of the first LED element  14  by the wire  16   a,  and is connected to the n-element electrode  15   b  of the second LED element  15  by the wire  17   b.  As a result, the p-element electrode  14   a  of the first LED element  14  is electrically connected to the n-element electrode  15   b  of the second LED element  15  through the third electrode  41 . Accordingly, similar to the third embodiment, the first LED element  14  and the second LED element  15  are electrically connected in series in the present embodiment. 
         [0042]    In the light-emitting device of the present embodiment, the the third electrode is used as an intermediary that allows reduction of a length of a wire, compared to the case where the first element electrode  14   a  of the first LED element  14  and the second element electrode  15   b  of the second LED element  15  are directly connected by a single wire. Accordingly, it is possible to prevent a wire from being broken and thus, a reliability of the light-emitting device can be increased. 
       Fifth Embodiment 
       [0043]      FIGS. 6 and 7  show a light-emitting device according to a fifth embodiment of the present invention. The light-emitting device  50  of the present embodiment includes a substantially same structure as that of the second embodiment, except that the first LED element  14  is mounted on the first electrode  12  at a position different from the corresponding position disclosed in the second embodiment and the second LED element  15  is mounted on the second electrode  13  at a position different from the corresponding position disclosed in the second embodiment. Accordingly, the same constituent elements are denoted by the same reference numbers, and will not be described in detail. 
         [0044]    As shown in  FIG. 6 , in the light-emitting device  50  of the present embodiment, the first electrode  12  includes a first inner portion  12   d  adjacent to the gap  11   a  and a first outer portion  12   e  positioned on an outside of the inner portion  12   d,  and the second electrode  13  includes a second inner portion  13   d  adjacent to the gap  11   a  and a second outer portion  13   e  positioned on the outside of the second inner portion  13   d.  The first inner portion  12   d  of the first electrode  12  includes a first inner edge  12   f  that defines a first side of the gap  11   a  between the first electrode  12  and the second electrode  13 , the second inner portion  13   d  of the second electrode  13  includes as a second inner edge  13   f  that defines a second side of the gap  11   a  between the first electrode  12  and the second electrode  13 . Further, the first outer portion  12   e  of the first electrode  12  includes a first outer edge  12   g  at an opposite side of the first inner edge  12   f  of the first inner portion  12   d  and is an area positioned outside of a center line  51  between the first inner edge  12   f  and the first outer edge  12   g,  and the second outer portion  13   e  of the second electrode  13  includes a second outer edge  13   g  at an opposite side of the second inner edge  13   f  of the second inner portion  13   d,  and is an area positioned outside of a center line  51  between the second inner edge  13   f  and the second outer edge  13   f.    
         [0045]    Further, in the present embodiment, the first through-hole  12   b  for electrical connection between the first upper surface electrode  12   a  and the first lower surface electrode  12   c  of the first electrode  12  is provided at the first outer portion  12   e  of the first electrode  12 , and the second through-hole  13   b  for electrical connection between the second upper surface electrode  13   a  and the second lower surface electrode  13   c  of the second electrode  13  is provided in the second outer portion  13   e  of the second electrode  13 . 
         [0046]    The first LED element  14  is mounted on the first upper surface electrode  12   a  to cover the first through-hole  12   b  at the first outer portion  12   e,  and the second LED element is mounted on the second upper surface electrode  13   a  to cover the second through-hole  13   b  at the second outer portion  13   e  of the second electrode  13 . Regarding the pair of element electrodes provided on the upper surface of the first LED element  14 , the first element electrode  14   a  as the p-element electrode is electrically connected by the wire  16   a  to the second inner portion  13   d  of the second electrode  13 , and the second element electrode as the n-element electrode  14   b  is electrically connected by the wire  16   b  to the first inner portion  12   d  of the first electrode  12 . Also, regarding the pair of element electrodes provided on the upper surface of the second LED element  15 , the second element electrode as the n-element electrode  15   b  is electrically connected by the wire  17   b  to the first inner portion  12   d  of the first electrode  12 , and the first element electrode as the p-element electrode  15   a  is electrically connected by the wire  17   a  to the second inner portion  13   d  of the second electrode  13 . In the present embodiment, the first LED element  14  and the second LED element  15  are electrically connected to each other in parallel. 
         [0047]    Similar to the second embodiment, in the light-emitting device  50  according to the present embodiment, heat generated from the first LED element  14  is allowed to be effectively dissipated through the first electrode  12  and the first through-hole  12   b  on that the first LED element  14  is mounted, and heat generated from the second LED element  15  is allowed to be effectively dissipated through the second electrode  13  and the second through-hole  13   b  on that the second LED element  15  is mounted. Further, the first LED element  14  is mounted on the first outer portion  12   e  of the first electrode  12 , and the second LED element  15  is mounted on the second outer portion  13   e  of the second electrode  13 . Accordingly, as a distance from the first LED element  14  to the gap  11   a  is increased and a distance from the second LED element  15  to the gap  11   a  is increased, the amount of light emission from the first LED element  14  and the second LED element  15  affecting an upper surface of the substrate appearing in the gap  11   a  can be reduced, and thus, it is possible to avoid a deterioration of substrate caused by light exposure. 
       Sixth Embodiment 
       [0048]      FIG. 8  shows a light-emitting device according to a sixth embodiment of the present invention. The light-emitting device  60  of the present embodiment includes a substantially same structure as that of the fifth embodiment, except that the p-element electrode  14   a  of the first LED element  14  and the n-element electrode  15   b  of the second LED element  15  are directly connected by the single wire  31 . Accordingly, the same constituent elements are denoted by the same reference numbers, and will not be described in detail. In the present embodiment, the first LED element  14  and the second LED element  15  are electrically connected in series. 
         [0049]    Similar to the fifth embodiment described previously, the light-emitting device  60  according to the present embodiment achieves a good effect of heat release and effectively suppresses a deterioration of the substrate  11 . 
       Seventh Embodiment 
       [0050]      FIG. 9  shows a light-emitting device  70  according to a seventh embodiment of the present invention. The light-emitting device  70  of the present embodiment includes a similar structure as that of the sixth embodiment, except that a fourth electrode  71  is provided in the gap  11   a  between the first electrode  12  and the second electrode  13 , and that the p-element electrode  14   a  of the first LED element  14  and the n-element electrode  15   b  of the second LED element  15  are connected through the fourth electrode  71 . Accordingly, the same constituent elements are denoted by the same reference numbers, and will not be described in detail. 
         [0051]    Like the third electrode  41  of  FIG. 5  described in the fourth embodiment, the fourth electrode  71  is electrically isolated from the first electrode  12  and the second electrode  13 . The fourth electrode  71  is connected to the p-element electrode  14   a  of the first LED element  14  by the wire  16   a,  and the fourth electrode  71  is connected to the n-element electrode  15   b  of the second LED element  15  by the wire  17   b.  As a result, the first element electrode  14   a  of the first LED element  14  and the second element electrode  15   b  of the second LED element  15  are electrically connected through the fourth electrode  71 . Accordingly, in the present embodiment, the first LED element  14  and the second LED element  15  are electrically connected in series. 
         [0052]    Similar to the fourth embodiment, in the light-emitting device  70  of the present embodiment, the fourth electrode  71  that exists as an intermediary allows reduction of the a length of a wire, compared to the case where where the first element electrode  14   a  of the first LED element  14  and the second element electrode  15   b  of the second LED element  15  are directly connected by a single wire. Accordingly, it is possible to prevent a wire from being broken and thus, reliability of the light-emitting device can be increased. 
       Eighth Embodiment 
       [0053]      FIG. 10  shows a light-emitting device  80  according to an eighth embodiment of the present invention. In the light-emitting device  80  of the present embodiment, the first LED element  14  and the second LED element  15  described in the fifth embodiment form one pair, and a plurality of such pairs are arranged on an elongated substrate  81 . More specifically, as shown in  FIG. 10 , an elongated first electrode  82  and an elongated second electrode  83  that includes a substantially same shape as the first electrode  82  are formed on the upper surface of the elongated substrate  81 , and a gap  81   a  in the form of a slit extending in a shape of a straight line is provided between the first electrode  82  and the second electrode  83 . Similar to the fifth embodiment, the first electrode  82  includes a first inner portion  82   d  adjacent to the gap  81   a  and a first outer portion  82   e  positioned on the outside of the first inner portion  82   d  at both sides of the center line  84  and the second electrode  83  includes a second inner portion  83   d  adjacent to the gap  81   a  and the second outer portion  83   e  positioned on the outside of the second inner portion  83   d  at both sides of the center line. Similar to the fifth embodiment, the first through-hole and the second through-hole (not shown in the drawing) filled with a heat conductor  18  such as solder, and the first through-hole is provided at a position of the first outer portion  82   e  on that the first LED element is arranged and the second through-hole is provided at a position of the second outer portion  83   e  on that the second LED element is arranged. 
         [0054]    The first LED element  14  and the second LED element  15  form one pair, and a plurality of such pairs is arranged on the first outer portion  82   e  of the first electrode  82  in a longitudinal direction of a first electrode  82  and the second outer portion  83   e  of the second electrode  83  in a longitudinal direction of the second electrode. Similar to the fifth embodiment, regarding all of the arranged first LED elements  14 , the p-element electrode  14   a  of the first LED elements are electrically connected by the wires  16   a  to the second inner portion  83   d  of the second electrode  83 , and the n-element electrodes  14   b  of the first LED elements are electrically connected by the wires  16   b  to the first inner portion  82   d  of the first electrode  82 . Similar to the fifth embodiment, regarding all of the arranged second LED elements  15 , the n-element electrodes  15   b  of the second electrode  15  are electrically connected by the wires  17   b  to the first inner portion  82   d  of the first electrode  82 , and the p-element electrodes  15   a  of the second electrode  15  are electrically connected by the wires  17   a  to the second inner portion  83   d  of the second electrode  83 . The structure is substantially same in other respects as that of the fifth embodiment described on the basis of  FIGS. 6 and 7 , and accordingly, it will not be described in detail. 
         [0055]    As described above, in the light-emitting device  80  according to the present embodiment, the first LED element  14  and the second LED element  15  form one pair, and in each of a plurality of such pairs, the first LED element  14  and the second LED element  15  are electrically connected in parallel. As a result, light can appear to be uniform from the entire light-emitting device  80 . Further, a great amount of heat generated from a plurality of the first LED elements and the second LED elements is allowed to be efficiently dissipated through corresponding electrodes. 
       Ninth Embodiment 
       [0056]      FIG. 11  shows a light-emitting device  90  according to a ninth embodiment of the present invention. The light-emitting device  90  of the present embodiment has a structure composed of a combination of the light-emitting device of the fifth embodiment shown in  FIG. 6  and the light-emitting device of the seventh embodiment shown in  FIG. 9 . More specifically, as shown in  FIG. 11 , an elongated first electrode  82  and an elongated second electrode  83  that includes a substantially same shape as the elongated first electrode  82  are provided on the upper surface of an elongated substrate  81 . Further, a pair  91  of the first LED element and the second LED element connected electrically in series and a pair  92  of the first LED element and the second LED element electrically connected in parallel are alternately arranged in the elongated direction of the first electrode  82  and the second electrode  83 . Electrical connections between the first LED element  14  and the second LED element  15  in each of pairs through wires are the same as those described in the fifth and seventh embodiments, and thereforem a detail description is omitted. 
         [0057]    In the present embodiment, the pairs  91  of series-connected the first LED element and the second LED element and the pairs  92  of parallel-connected the first LED element and the second LED element are alternately arranged one pair by one pair. However, the present invention is not limited to this. By way of example, two pairs  91  of series-connected the first LED element and the second LED element and two pairs  92  of parallel-connected the first LED element and the second LED element may be alternately arranged in turn. Further, pairs of series-connected the first LED element and the second LED element and pairs of parallel-connected the first LED element and the second LED element to be arranged alternately are not always required to be the same in number. Additionally, the pair  91  of the first LED element and the second LED element forming the pair  91  may not be always connected in series by the connection structure shown in the seventh embodiment, but they may be connected in series by the connection structure the sixth embodiment shown in  FIG. 8 , for example. 
         [0058]    In the light-emitting device  90  of the present embodiment, series connection and parallel connection can be combined freely, where appropriate, for connection of the first LED elements and the second LED elements in pairs to be mounted on the single substrate  81 . Further, if the first LED element and the second LED element arranged in a plurality of pairs are mounted on the single substrate  81 , great amount of heat is generated from the first LED elements and the second LED elements. In this case, the heat is allowed to be efficiently dissipated. 
         [0059]    Although not specifically described above, the the first LED element and the second LED element of each embodiment can be selected appropriately from a red LED element, a green LED element, a blue LED element, and the like. Additionally, the sealing resin may also be a phosphor containing resin. The resin may be made of a silicone resin that can contain various fluorescent substances, for example. 
         [0060]    It is to be understood that the present invention is not limited to the embodiments described above, but various modifications and changes can be made to the embodiments. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           10 ,  20 ,  30 ,  40 ,  50 ,  60 ,  70 ,  80 ,  90  light-emitting device 
           11 ,  81  substrate 
           11   a,    81   a  gap 
           12 ,  82  first electrode 
           12   a,    13   a  first upper surface electrode, second upper surface electrode 
           12   b,    13   b  first through-hole, second through-hole 
           12   c,    13   c  first lower surface electrode, second lower surface electrode 
           12   d,    13   d  first inner portion, second inner portion 
           12   e,    13   e  first outer portion, second outer portion 
           12   f,    13   f  first inner edge, second inner edge 
           12   g,    13   g  first outer edge, second outer edge 
           13 ,  83  second electrode 
           14  first LED element 
           15  second LED element 
           14   a,    15   a  p-element electrode (first element electrode) 
           14   b,    15   b  n-element electrode (second element electrode) 
           16   a,    16   b  wire 
           17   a,    17   b  wire 
           18  heat conductor 
           19  sealing resin 
           31  wire 
           41  third electrode 
           51 ,  52 ,  84 ,  85  center line 
           71  fourth electrode 
           91  pairs of series-connected LED elements 
           91  pairs of parallel-connected LED elements