Patent Publication Number: US-2015060900-A1

Title: Light Emitting Module and Lighting Device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priorities from Japanese Patent Application No. 2013-178631 filed on Aug. 29, 2013; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate to a light emitting module and a lighting device. 
     BACKGROUND 
     In recent years, a lighting device including an LED (Light Emitting Diode) as a light source is spreading. As such a lighting device, there is known a lighting device mounted with a plurality of kinds of LEDs having different light emission colors. In the lighting device, light having a color obtained by mixing the light emission colors of the LEDs is irradiated. 
     In the lighting device mounted with the plurality of kinds of LEDs having the different light emission colors, in some case, lights having different colors are not mixed and color unevenness occurs on an irradiated surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an example of the configuration of a lighting device mounted with a light emitting module according to an embodiment; 
         FIG. 2  is a diagram showing an example of the configuration of the light emitting module; 
         FIG. 3  is a diagram showing an example of electric wiring of the light emitting module; 
         FIG. 4  is a conceptual diagram for explaining an array of blue LEDs and red LEDs according to the embodiment; 
         FIG. 5  is a conceptual diagram for explaining emitting directions of lights emitted by the light emitting module; and 
         FIG. 6  is a conceptual diagram for explaining emitting directions of lights emitted by the light emitting module. 
     
    
    
     DETAILED DESCRIPTION 
     It is an object of the present invention to provide a light emitting module and a lighting device that can reduce color unevenness of light that occurs from an irradiated surface. 
     According to one embodiment, there is provided a light emitting module including: a plurality of blue LEDs, which are an example of a plurality of first light emitting elements; and a plurality of red LEDs, which are an example of a plurality of second light emitting elements configured to emit lights in a color different from a color of lights emitted by the blue LEDs. The plurality of blue LEDs and the plurality of red LEDs are arranged side by side on a board in a plurality of rows set in advance. Each of the plurality of blue LEDs is arranged such that, in each of the plurality of rows, the number of the blue LEDs arranged adjacent to one another is equal to or smaller than the number set in advance. Among the plurality of rows, there is a row in which the number of the blue LEDs arranged adjacent to one another is different from the number in the other rows. By irregularly arranging the blue LEDs and the red LEDs in this way, it is possible to reduce color unevenness of light emitted by the light emitting module. 
     In the light emitting module according to the embodiment, the plurality of blue LEDs and the plurality of red LEDs may be arranged in each of a plurality of regions on the board, and the numbers of the arranged blue LEDs and red LEDs may be the same among the regions. The plurality of blue LEDs and the plurality of red LEDs may be arranged in the same arrangement among the regions. Since the plurality of blue LEDs and the plurality of red LEDs are arrayed the same in each of the regions, it is easy to manufacture the light emitting module and it is possible to reduce manufacturing costs. 
     In the light emitting module according to the embodiment, the plurality of blue LEDs and the plurality of red LEDs in each of the regions may be electrically connected in series. 
     In the light emitting module according to the embodiment, in each of the regions, there may be a plurality of light emitting element groups including the plurality of blue LEDs continuously connected in series, and, among the plurality of light emitting element groups, there may be a light emitting element group including the different number of the continuously-connected plurality of blue LEDs. Consequently, by arranging, in each of the regions, the plurality of blue LEDs and the plurality of red LEDs connected in series, it is possible to easily create a light emitting module in which the plurality of blue LEDs and the plurality of red LEDs are irregularly arranged as a whole. 
     The light emitting module according to the embodiment may further include: a wiring pattern provided on the board and configured to supply electric power to each of the plurality of blue LEDs and the plurality of red LEDs; resin, which is a sealing body formed to cover the plurality of blue LEDs and the plurality of red LEDs; and a blocking member configured to surround the resin. At least a part of the blocking member may be disposed on the wiring pattern. Consequently, even when the red LED is arranged at an end of the light emitting module, light emitted by the red LED is reflected on the inner wall of the blocking member and emitted to the outside. Therefore, the light emitting module can efficiently emit the light of the red LED to the outside. 
     According to another embodiment, there is provided a lighting device including: the light emitting module; and a control section, which is a power-supply control section configured to control a power supply for the light emitting module. 
     A light emitting module and a lighting device according to an embodiment are explained below with reference to the drawings. In the embodiment, components having the same functions are denoted by the same reference numerals and signs and redundant explanation of the components is omitted. The light emitting module and the lighting device explained in the embodiment are only an example and do not limit the present invention. The embodiments may be combined as appropriate to the extent that the embodiments do not contradict each other. 
     Configuration of a Lighting Device 
       FIG. 1  is a diagram showing an example of the configuration of a lighting device mounted with a light emitting module according to an embodiment. As shown in  FIG. 1 , a lighting device  1  according to this embodiment includes a light emitting module  10 , a main body  11 , a cap member  12 , an eyelet section  13 , a cover  14 , a control section  15 , an electric wire  16   a,  and an electric wire  16   b.  The light emitting module  10  includes a board  110 . The board  110  is formed of ceramics having low heat conductivity, for example, alumina, silicon nitride, silicon oxide, or aluminum and arranged on an upper surface  11   a  of the main body  11 . 
     The main body  11  is formed of metal having high heat conductivity, for example, aluminum in a columnar shape substantially circular in a cross section. The cap member  12  is attached to one end of the main body  11 . The cover  14  is attached to the other end of the main body  11 . The main body  11  is formed such that the outer circumferential surface of the main body  11  forms a taper surface having a substantially conical shape, the diameter of which sequentially increases in a direction from one end toward the other end. 
     The main body  11  is formed in an external shape approximate to a silhouette of a neck section in a conventional mini-krypton bulb. On the outer circumferential surface of the main body  11 , a not-shown large number of thermal radiation fins radially projecting from one end toward the other end are integrally formed. 
     The cap member  12  is, for example, an E-type cap of an Edison type. The cap member  12  includes a cylindrical shell made of a cooper plate including a thread ridge. The cap member  12  includes a conductive eyelet section  13  provided at an apex at the lower end of the shell via an electrically insulated section. An opening section of the shell is electrically insulated from and fixed to an opening section at one end of the main body  11 . 
     An input line led out from a power input terminal of a not-shown circuit board in the control section  15  is connected to the shell and the eyelet section  13 . The cap member  12  is inserted into a socket provided in, for example, the ceiling to supply electric power, which is supplied from the commercial power supply, to the control section  15 . 
     The cover  14  is formed of, for example, milky-white polycarbonate. The cover  14  is formed in a smooth curved surface shape approximated to a silhouette of a mini-krypton bulb having an opening at one end. An opening end portion of the cover  14  is fit in and fixed to the main body  11  to cover a light emitting surface of the light emitting module  10 . A method of fixing the cover  14  to the main body  11  may be any of boning, fitting, screwing, and locking. 
     The control section  15  supplies electric power to the light emitting module  10  provided on the board  110  and controls lighting and extinction of the light emitting module  10 . The control section  15  includes a control circuit housed to be electrically insulated from the outside. The control section  15  converts an alternating-current voltage into a direct-current voltage according to the control by the control circuit and applies the converted direct-current voltage to the light emitting module  10  on the board  110 . The electric wires  16   a  and  16   b  for supplying electric power to the light emitting module  10  on the board  110  are connected to an output terminal of the control circuit of the control section  15 . 
     The electric wires  16   a  and  16   b  are led out to an opening section at the other end of the main body  11  via a not-shown through-hole and a not-shown guide groove formed in the main body  11 . Insulation coating is peeled from distal end portions of the electric wires  16   a  and  16   b.  The distal end portions are connected to a below-mentioned connector  160  arranged on the board  110 . 
     In this way, the control section  15  supplies electric power, which is input via the shell and the eyelet section  13 , to the light emitting module  10  on the board  110  via the electric wires  16   a  and  16   b.  The control section  15  collects the electric power, which is supplied to the light emitting module  10 , via the electric wires  16   a  and  16   b.    
     Configuration of the Light Emitting Module 
       FIG. 2  is a diagram showing an example of the configuration of the light emitting module according to this embodiment.  FIG. 2  is a top view showing an example of the configuration of the light emitting module  10  viewed from an arrow A direction in  FIG. 1 . As shown in  FIG. 2 , a plurality of blue LEDs  121  and a plurality of red LEDs  122  are arranged on an arrangement surface  110   a  of the board  110 . 
     Each of the blue LEDs  121  is a light emitting element configured to emit blue-based light having a peak wavelength within a range of, for example, 445 to 465 nm. Each of the red LEDs  122  is a light emitting element configured to emit red-based light having a peak wavelength within a range of, for example, 590 to 640 nm. 
     In  FIG. 2 , one blue LED among the plurality of blue LEDs  121  is denoted by reference numeral “ 121 ”. However, members indicated by the same white square shape are equivalent to the blue LEDs  121 . In  FIG. 2 , one red LED among the plurality of red LEDs  122  is denoted by reference numeral “ 122 ”. However, members indicated by the same black square shape are equivalent to the red LED  122 . 
     An annular blocking member  130  is arranged on the arrangement surface  110   a  of the board  110  to surround the blue LEDs  121  and the red LEDs  122 . At least the inner wall of the annular blocking member  130  is formed of a member having a color with high reflectance (e.g., a white color). Alternatively, paint having a color with high reflectance is applied to the inner wall. In a recess formed by the inner wall of the blocking member  130  and the arrangement surface  110   a  of the board  110 , resin including a phosphor is filled. 
     As the resin, resin obtained by adding a phosphor to transparent resin having high diffusibility such as epoxy resin, urea resin, or silicone resin is used. Each of the blue LEDs  121  and the red LEDs  122  is entirely covered with the resin including such a phosphor from above. 
     The phosphor added to the resin is excited by the blue-based light emitted by the blue LED  121  and emits light having a color different from a color of the light emitted by the blue LED  121 . In this embodiment, a yellow phosphor excited by the blue-based light emitted by the blue LED  121  to emit yellow-based light (a peak wavelength is, for example, 540 to 570 nm), which is in a complementary color relation with the blue-based light, is added to the resin. 
     Consequently, the light emitting module  10  can emit white light as a whole using the blue-based light emitted by the blue LED  121  and the yellow-based light emitted by the yellow phosphor. Besides the yellow phosphor, a green phosphor excited by the light emitted by the blue LED  121  to emit green-based light may be added to the resin. 
     Wiring patterns  151  and  152  are formed on the arrangement surface  110   a  of the board  110 . The wiring patterns  151  and  152  are electric conductors printed on the board  110 . One end of the wiring pattern  151  and one end of the wiring pattern  152  are connected to the connector  160  provided on the board  110 . 
     As shown in  FIG. 2 , the other end of the wiring pattern  151  and the other end of the wiring pattern  152  are formed in substantially parallel linear shapes on the arrangement surface  110   a  of the board  110 . At least a part of the other end of the wiring pattern  151  and at least a part of the other end of the wiring pattern  152  are arranged between the arrangement surface  110   a  of the board  110  and the blocking member  130 . 
     Wiring in the Light Emitting Module 
       FIG. 3  is a diagram showing an example of electric wiring of the light emitting module according to this embodiment. As shown in  FIG. 3 , the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged in each of a plurality of regions  18   a  to  18   c  (in the example shown in  FIG. 3 , three regions) on the board  110 . In each of the regions  18   c  to  18   c,  the plurality of blue LEDs  121  and the plurality of red LEDs  122  are connected in series by a bonding wire  172 . 
     In each of the regions  18   a  to  18   c,  one end of the plurality of blue LEDs  121  and the plurality of red LEDs  122  connected in series is connected to the other end of the wiring pattern  151 , which is formed in a linear shape, by a bonding wire  171 . The other end of the plurality of blue LEDs  121  and the plurality of red LEDs  122  connected in series is connected to the other end of the wiring pattern  152 , which is formed in a linear shape, by the boding wire  171 . 
     In each of the regions  18   a  to  18   c,  the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged side by side in a predetermined array on the arrangement surface  110   a  of the board  110 . In the example shown in  FIG. 3 , the blue LEDs  121  and the red LEDs  122  are arranged side by side in an array of a lattice shape on the arrangement surface  110   a  of the board  110 . 
     In a state in which the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged side by side on the arrangement surface  110   a  of the board  110 , the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged such that the number of continuously-arranged LEDs of the same type among the blue LEDs  121  and the red LEDs  122  is within a predetermined number (in the example, shown in  FIG. 3 , nine) in each of rows of the LEDs. 
     In each of the rows, the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged such that the number of continuously-arranged LEDs of the same type among the blue LEDs  121  and the red LEDs  122  is irregular within the predetermined number. Therefore, among a plurality of rows of the LEDs, there is a row in which the number of the blue LEDs  121  arranged adjacent to one another is different from the number in the other rows. 
     Among the plurality of regions  18  on the arrangement surface  110   a  of the board  110 , the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged such that the number of continuously-arranged LEDs of the same type among the blue LEDs  121  and the red LEDs  122  is irregular within the predetermined number. 
     In each of the regions  18   a  to  18   c,  as shown in  FIG. 3 , the plurality of blue LEDs  121  and the plurality of red LEDs  122  connected in series are arranged to meander from the wiring pattern  151  to the wiring pattern  152  while being folded back at every predetermined number (in the example shown in  FIG. 3 , at every three LEDs) along a linear portion of the wiring pattern  151 . 
     In the plurality of blue LEDs  121  and the plurality of red LEDs  122  connected in series in each of the regions  18   a  to  18   c,  there is a plurality of light emitting element groups  173  including the plurality of blue LEDs  121  continuously connected in series. Among the plurality of light emitting element groups  173 , there is the light emitting element group  173  in which the number of the continuously-connected plurality of blue LEDs  121  is different. 
     For example, in the example shown in  FIG. 3 , there are, for example, a light emitting element group  173   a  and a light emitting element group  173   b  including the plurality of blue LEDs  121  continuously connected in series in the region  18   c.  The number of the blue LEDs  121  continuously connected in series in the light emitting element group  173   a  is four. The number of the blue LEDs  121  continuously connected in series in the light emitting element group  173   b  is three. In the light emitting element group  173   a  and the light emitting element group  173   b,  the numbers of the blue LEDs  121  continuously connected in series are different. 
     Among the regions  18   a  to  18   c,  the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged the same. Therefore, the light emitting module  10  can be created by arranging the arrangement in one region  18  to other region  18 . Consequently, it is possible to reduce manufacturing costs for the light emitting module  10 . 
     In each of the regions  18   a  to  18   c  and among the regions  18   a  to  18   c,  the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged such that the number of continuously-arranged LEDs of the same type is irregular within a range of the predetermined number. Therefore, in the entire light emitting module  10 , the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged irregularly. Consequently, the light emitting module  10  can reduce color unevenness due to lights having different colors emitted by the plurality of blue LEDs  121  and the plurality of red LEDs  122 . 
     In each of the regions  18   a  to  18   c,  there is a portion where the number of the blue LEDs  121  continuously connected in series is different. Consequently, it is possible to easily realize irregular arrangement by arranging the plurality of blue LEDs  121  and the plurality of red LEDs  122  connected in series to meander. 
     Arrangement of the Blue LEDs and the Red LEDs 
       FIG. 4  is a conceptual diagram for explaining the array of the blue LEDs and the red LEDs according to this embodiment. For example, as shown in  FIG. 4 , the blue LEDs  121  and the red LEDs  122  in this embodiment are arranged side by side in an array of a lattice shape on the arrangement surface  110   a  of the board  110 . Besides the lattice shape, the arrangement of the blue LEDs  121  and the red LEDs  122  may be an array of a radial shape, a concentric shape, or a combination of these shapes. 
     For example, in a row  192  in which the blue LEDs  121  and the red LEDs  122  are arranged side by side in the left right direction in  FIG. 4 , the number of continuously-arranged blue LEDs  121  is nine. On the other hand, in a row  193  in which the blue LEDs  121  and the red LEDs  122  are also arranged side by side in the left right direction of  FIG. 4 , the number of the continuously-arranged blue LEDs  121  is two. 
     For example, in a row  190  in which the blue LEDs  121  and the red LEDs  122  are arranged side by side in the up down direction of  FIG. 4 , the number of the continuously-arranged blue LEDs  121  is one, two, or three. On the other hand, in a row  191  in which the blue LEDs  121  and the red LEDs  122  are also arranged side by side in the up down direction of  FIG. 4 , the number of the continuously-arranged blue LEDs  121  is two or three. Further, in the row  190  and the row  191 , places where the same numbers of the blue LEDs  121  are continuously arranged are different. 
     As explained above, the plurality of blue LEDs  121  and the plurality of red LEDs  122  are irregularly arranged on the arrangement surface  110   a  of the board  110 . Therefore, in the entire light emitting module  10 , it is possible to reduce color unevenness due to lights having different colors emitted by the plurality of blue LEDs  121  and the plurality of red LEDs  122 . 
     Positional Relation Between the Red LED and the Blocking Member 
       FIG. 5  is a conceptual diagram for explaining emitting directions of lights emitted by the light emitting module according to this embodiment.  FIG. 5  is an enlarged view of a part of a B-B section of  FIG. 2 . Resin  140  includes a yellow phosphor  141 . The blue LED  121  emits blue-based light. The yellow phosphor  141  is excited by the light of the blue LED  121  to emit yellow-based light. The light emitting module  10  emits white light as a whole using the blue-based light emitted by the blue LED  121  and the yellow-based light emitted by the yellow phosphor  141 . 
     The red LED  122  emits red-based light. The light emitting module  10  can improve color rendering properties of the white light using the red-based light emitted by the red LED  122 . 
     The blue LED  121  and the red LED  122  emit lights having strong directivity. However, a part of the light emitted by the blue LED  121  is diffused by the yellow phosphor  141 . Therefore, when the light is emitted to the outside of the light emitting module  10 , the directivity decreases. 
     On the other hand, the light emitted by the red LED  122  is hardly diffused by the yellow phosphor  141 . Therefore, the light is emitted to the outside of the light emitting module  10  while keeping the strong directivity. Therefore, depending on a viewing angle, the light emitted by the red LED  122  weakens and a portion of the light emitting module  10  where the red LED  122  is arranged looks dark. In particular, when the red LED  122  is arranged at an end of a region on the board  110  where the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged, the light emitted from the blue LED  121  decreases around the region. Therefore, depending on a viewing angle, the portion looks dark. 
     Therefore, in the light emitting module  10  in this embodiment, the blocking member  130  is arranged near the region on the board  110  where the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged. Consequently, even when the red LED  122  is arranged at the end of the region on the board  110  where the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged, a part of the light emitted by the red LED  122  is reflected on the inner wall of the blocking member  130  and emitted to the outside. Therefore, the periphery of the red LED  122  can look brighter. 
       FIG. 6  is a conceptual diagram for explaining emitting directions of lights emitted by the light emitting module according to this embodiment.  FIG. 6  is an enlarged view of a part of a C-C section of  FIG. 2 . For example, as shown in  FIG. 6 , in the light emitting module  10  in this embodiment, the blocking member  130  is arranged near the region on the board  110  where the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged. As a result, at least a part of the blocking member  130  is arranged on the wiring pattern  152 . Although not shown in  FIG. 6 , on the wiring pattern  151  side, similarly, at least a part of the blocking member  130  is arranged on the wiring pattern  151 . 
     In this embodiment, the plurality of blue LEDs  121  and the plurality of red LEDs  122  are irregularly arranged. Therefore, the red LED  122  is sometimes arranged at the end of the region on the board  110  where the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged. However, even in such a case, since the blocking member  130  is arranged near the region on the board  110  where the plurality of blue LEDs  121  and the plurality of red LEDs  122  are arranged, it is possible to prevent the portion of the light emitting module  10  where the red LED  122  is arranged from looking dark. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.