Patent Publication Number: US-2013249411-A1

Title: Light Emitting Module and Lighting System

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from the Japanese Patent Application No. 2012-069708, filed on Mar. 26, 2012, the entire contents of all of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a light emitting module, and a lighting system. 
     BACKGROUND 
     In recent years, as a lighting system, a lighting system which includes a power saving light emitting element such as an LED (Light Emitting Diode) is used. The lighting system includes a light emitting element which is able to obtain higher brightness, or illuminance with a smaller power consumption than, for example, an incandescent light bulb in the related art. 
     Here, there is a case in which the lighting system including a light emitting element includes a plurality of types of light emitting elements of which luminous colors are different on the same substrate. A plurality of types of light emitting elements on the same substrate is sealed with a sealing unit which is formed using resin which contains phosphor in an appropriate manner. The lighting system emits light of desired color appropriate for the use by causing the phosphor included in the sealing unit to fluorescence by light of respective luminous colors of the plurality of types of light emitting elements and mixing thereto the luminous color of the respective light emitting elements. 
     However, in the above described related art, since light emitting elements of different types as different luminous colors are used, there is a concern that mixing of luminous colors of the respective light emitting elements may become un-uniform. 
     An object of the exemplary embodiments is to provide a light emitting module and a lighting system which is able to reduce un-uniform mixing of luminous colors of respective light emitting elements of different types in consideration of the above described problems in the related art. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a vertical cross-sectional view which illustrates a lighting system on which a light emitting module according to a first embodiment is mounted. 
         FIG. 2  is a top view which illustrates the light emitting module according to the first embodiment. 
         FIG. 3  is a horizontal cross-sectional view which illustrates the lighting system on which the light emitting module according to the first embodiment is mounted. 
         FIG. 4  is a diagram which illustrates electric wiring of the light emitting module according to the first embodiment. 
         FIG. 5  is a diagram which illustrates reflections of luminous colors of respective light emitting elements in the light emitting module according to the first embodiment. 
         FIG. 6  is a top view which illustrates a light emitting module according to a second embodiment. 
         FIG. 7  is a top view which illustrates a light emitting module according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a light emitting module and a lighting system according to the embodiments will be described with reference to drawings. Constituent elements having the same functions in the embodiments are given the same reference numerals, and repeated descriptions will be omitted. In addition, the light emitting module and the lighting system which will be described in the following embodiments are merely examples, and do not limit the exemplary embodiments. In addition, embodiments below may be appropriately combined as far as they are not contradictive. 
     Light emitting modules  10   a  to  10   c  according to a first embodiment below include a first light emitting element which emits first luminous color (for example, blue LEDs  2   a  to  2   c ) when being supplied with a current, and a second light emitting element which emits second luminous color (for example, red LEDs  4   a  to  4   c ) when being supplied with a current. In addition, the light emitting modules  10   a  to  10   c  include a substrate  1  on which the first light emitting element (for example, blue LEDs  2   a  to  2   c ) and the second light emitting element (for example, red LEDs  4   a  to  4   c ) are surface mounted on the same plane. In addition, the light emitting modules  10   a  to  10   c  include a first sealing unit (for example, sealing units  3   a  to  3   c ) which seals the first light emitting element (for example, blue LEDs  2   a  to  2   c ) which is surface mounted on the substrate  1 . In addition, the light emitting modules  10   a  to  10   c  include a second sealing unit (for example, sealing units  5   a  to  5   c ) which seals the second light emitting element (for example, reds LED  4   a  to  4   c ) which is surface mounted on the substrate  1  using a sealing member having a higher refractive index than that in the first sealing unit (for example, sealing units  3   a  to  3   c ), and is arranged so as to form an interface between the first sealing unit (for example, sealing units  3   a  to  3   c ) and the second sealing unit (for example, sealing units  5   a  to  5   c ). 
     In addition, in the light emitting modules  10   a  to  10   c  according to a second embodiment below, a part of light beams of light emitted from the second light emitting element (for example, red LEDs  4   a  to  4   c ) which is reflected on an interface between the second sealing unit (for example, sealing units  5   a  to  5   c ) and gas at the upper part of the second sealing unit penetrates into the first sealing unit (for example, sealing units  3   a  to  3   c ) through the interface between the second sealing unit (for example, sealing units  5   a  to  5   c ) and the first sealing unit (for example, sealing units  3   a  to  3   c ). In addition, the light which penetrates into the first sealing unit (for example, sealing units  3   a  to  3   c ) is output to the outside from the first sealing unit (for example, sealing units  3   a  to  3   c ) along with light which is emitted from the first light emitting element (for example, blue LEDs  2   a  to  2   c ). 
     In addition, in the light emitting modules  10   a  to  10   c  according to a third embodiment below, the first light emitting element (for example, blue LEDs  2   a  to  2   c ) is arranged in a toric shape on the substrate  1 , and the second light emitting element (for example, red LEDs  4   a  to  4   c ) is arranged in the vicinity of a center of the toric shape on the substrate  1 . In addition, the first sealing unit (for example, sealing units  3   a  to  3   c ) is formed on the substrate  1  in a toric shape, and the second sealing unit (for example, sealing units  5   a  to  5   c ) is formed so as to fill the inside of the toric shape of the first sealing unit (for example, sealing units  3   a  to  3   c ). 
     In addition, in the light emitting modules  10   a  to  10   c  according to a forth embodiment below, two first light emitting element groups including the first light emitting element (for example, blue LEDs  2   a  to  2   c ), and two second light emitting element groups including the second light emitting element (for example, red LEDs  4   a  to  4   c ) are diagonally arranged at a position which is symmetric about a point with respect to a center of the substrate  1 , respectively, on the substrate  1 . 
     In addition, in the light emitting modules  10   a  to  10   c  according to a fifth embodiment below, one first light emitting element group including the first light emitting element (for example, blue LEDs  2   a  to  2   c ), and one second light emitting element group including the second light emitting element (for example, red LEDs  4   a  to  4   c ) are arranged at a position which is line symmetry with respect to a center line of the substrate  1  on the substrate  1 . 
     In addition, in the light emitting modules  10   a  to  10   c  according to a sixth embodiment below, a height (for example, H 1 ) of the first sealing unit (for example, sealing unit  3   a ) is higher than a height (for example, H 2 ) of the second sealing unit (for example, sealing units  5   a ) on a surface of the substrate  1 . 
     In addition, in the light emitting modules  10   a  to  10   c  according to a seventh embodiment below, a refractive index of a sealing member of the first sealing unit (for example, sealing units  3   a  to  3   c ), and a refractive index of a sealing member of the second sealing unit (for example, sealing units  5   a  to  5   c ) are higher than a refractive index of gas which shares interfaces with the first sealing unit (for example, sealing units  3   a  to  3   c ) and the second sealing unit (for example, sealing units  5   a  to  5   c ). 
     In addition, in the light emitting modules  10   a  to  10   c  according to a eighth embodiment below, the light emitting modules  10   a  to  10   c  further include a detection sensor which detects heat or brightness due to light emission of the first light emitting element (for example, blue LEDs  2   a  to  2   c ) and the second light emitting element (for example, red LEDs  4   a  to  4   c ) which are provided on the substrate  1 , a first control circuit which controls power which is supplied to the first light emitting element (for example, blue LEDs  2   a  to  2   c ) according to a detection result of the heat, or brightness using the detection sensor, and a second control circuit which controls power which is supplied to the second light emitting element (for example, red LEDs  4   a  to  4   c ) according to a detection result of the heat, or brightness using the detection sensor. 
     In addition, in the light emitting modules  10   a  to  10   c  according to a ninth embodiment below, the first control circuit controls a driving current, or a driving pulse which is supplied to the first light emitting element (for example, blue LEDs  2   a  to  2   c ), and the second control circuit controls a driving current, or a driving pulse which is supplied to the second light emitting element (for example, red LEDs  4   a  to  4   c ). 
     A lighting systems  100   a  to  100   c  according to a tenth embodiment below, include a light emitting module (for example, light emitting module  10   a  to  10   c ) which includes a first light emitting element which emits first luminous color (for example, blue LEDs  2   a  to  2   c ) when being supplied with a current, a second light emitting element which emits second luminous color (for example, red LEDs  4   a  to  4   c ) when being supplied with a current, a substrate on which the first light emitting element (for example, blue LEDs  2   a  to  2   c ) and the second light emitting element (for example, red LEDs  4   a  to  4   c ) are surface mounted on the same plane. In addition, the light emitting modules  10   a  to  10   c  include a first sealing unit (for example, sealing units  3   a  to  3   c ) which seals the first light emitting element (for example, blue LEDs  2   a  to  2   c ) which is surface mounted on the substrate  1 . In addition, the light emitting modules  10   a  to  10   c  include a second sealing unit (for example, sealing units  5   a  to  5   c ) which seals the second light emitting element (for example, reds LED  4   a  to  4   c ) which is surface mounted on the substrate using a sealing member having a higher refractive index than that in the first sealing unit (for example, sealing units  3   a  to  3   c ), and is arranged so as to form an interface between the first sealing unit (for example, sealing units  3   a  to  3   c ) and the second sealing unit (for example, sealing units  5   a  to  5   c ). 
     In addition, in the lighting system  100   a  to  100   c  according to an eleventh embodiment below, in the light emitting module (for example, light emitting module  10   a  to  10   c ), a part of light beams of light emitted from the second light emitting element (for example, red LEDs  4   a  to  4   c ) which is reflected on an interface between the second sealing unit (for example, sealing units  5   a  to  5   c ) and gas at the upper part of the second sealing unit penetrates into the first sealing unit (for example, sealing units  3   a  to  3   c ) through the interface between the second sealing unit (for example, sealing units  5   a  to  5   c ) and the first sealing unit (for example, sealing units  3   a  to  3   c ). In addition, the light which penetrates into the first sealing unit (for example, sealing units  3   a  to  3   c ) is output to an outside from the first sealing unit (for example, sealing units  3   a  to  3   c )along with light which is emitted from the first light emitting element (for example, blue LEDs  2   a  to  2   c ). 
     In addition, in the lighting system  100   a  to  100   c  according to a twelfth embodiment below, in the light emitting module (for example, light emitting module  10   a  to  10   c ), the first light emitting element (for example, blue LEDs  2   a  to  2   c ) is arranged in a toric shape on the substrate  1 , and the second light emitting element (for example, red LEDs  4   a  to  4   c ) is arranged in the vicinity of a center of the toric shape on the substrate  1 . In addition, the first sealing unit (for example, sealing units  3   a  to  3   c ) is formed in a toric shape so as to cover and seal the first light emitting element (for example, sealing units  3   a  to  3   c ) from above on the substrate  1 , and wherein the second sealing unit (for example, sealing units  5   a  to  5   c ) is formed so as to fill the inside of the toric shape of the first sealing unit (for example, sealing units  3   a  to  3   c ) by covering and sealing the second light emitting element (for example, red LEDs  4   a  to  4   c ) from above on the substrate  1 . 
     In addition, in the lighting system  100   a  to  100   c  according to a thirteenth embodiment below, in the light emitting module (for example, light emitting module  10   a  to  10   c ), a height (for example, H 1 ) of the first sealing unit (for example, sealing unit  3   a ) is higher than a height (for example, H 2 ) of the second sealing unit (for example, sealing units  5   a ) on a surface of the substrate  1 .In addition, a lighting system  100   a  to  100   c  according to a fourteenth embodiment below, include the light emitting module  10   a  to  10   c,  and a body  11  which is provided with the light emitting module  10   a  to  10   c.    
     In the following embodiments, the light emitting element is described as an LED (Light Emitting Diode), however, it is not limited to this, and may be another light emitting element which emits a predetermined color such as an organic EL (OLEDs (Organic Light Emitting Diodes)), and a semiconductor laser, when a current is supplied. 
     In addition, in the following embodiments, an LED is configured by a light emitting diode chip which is formed of a gallium-nitrid (GaN) based semiconductor of which luminous color is blue, or a compound-based semiconductor of four chemical materials (Al, In, Ga, P) of which luminous color is red. In addition, a part, or all of the LEDs are mounted by being arranged regularly, at regular intervals in matrix, in zigzag, in a radial pattern, or the like, and for example, using a COB (Chip On Board) technology. Alternatively, the LEDs may be configured as an SMD type (Surface Mount Device). In addition, in the following embodiments, the number of LED configures an LED group using LEDs of the same type in which a design can be changed depending on use of lighting. 
     In addition, in the following embodiments, a shape of the lighting system has a type of Krypton light bulb, however, it is not limited to this, and may be a general light bulb type, a cannonball type, or the like. 
       FIG. 1  is a vertical cross-sectional view which illustrates a lighting system on which a light emitting module according to the first embodiment is mounted. As illustrated in  FIG. 1 , a lighting system  100   a  includes a light emitting module  10   a.  In addition, the lighting system  100   a  according to the first embodiment includes a body  11 , a base member  12   a,  an eyelet unit  12   b,  a cover  13 , a control unit  14 , electric wiring  14   a,  an electrode connection unit  14   a - 1 , electric wiring  14   b,  and an electrode connection unit  14   b - 1 . 
     The light emitting module  10   a  is arranged on the top face of the body  11  in the vertical direction. The light emitting module  10   a  includes a substrate  1 . The substrate  1  is formed of ceramics with low heat conductivity, and for example, is formed of alumina. The heat conductivity of the substrate  1  is, for example, 33 [W/m·K] in an atmosphere of 300 [K]. 
     When the substrate  1  is formed of ceramics, since the substrate has a high mechanical strength, and a high accuracy of dimension, it is possible to increase yields when performing a mass production of the light emitting module  10   a,  to reduce a manufacturing cost of the light emitting module  10   a,  and to contribute to a long life of the light emitting module  10   a.  In addition, since the ceramics has high reflectivity of visible light, it is possible to improve a luminous efficiency of the LED module. 
     In addition, the substrate  1  may be formed of silicon nitride, silicon oxide, or the like, without being limited to alumina. In addition, the heat conductivity of the substrate  1  is preferably 20 to 70 [W/m·K]. When the heat conductivity of the substrate  1  is 20 to 70 [W/m·K], it is possible to suppress a manufacturing cost, reflectivity, and a heat influence between light emitting elements which are mounted on the substrate  1 . In addition, the substrate  1  which is formed using the ceramics with preferable heat conductivity is possible to suppress the heat influence between the light emitting elements which are mounted on the substrate  1 , compared to a material with high heat conductivity. For this reason, in the substrate  1  which is formed using the ceramics with preferable heat conductivity, it is possible to make a distance between the light emitting elements which are mounted on the substrate  1  short, and to realize downsizing. 
     In addition, the substrate  1  may be formed using nitride of aluminum such as aluminum nitride. In this case, the heat conductivity of the substrate  1  is, for example, smaller than 225 [W/m·K] which is the heat conductivity of aluminum of approximately 99.5 mass % in an atmosphere of 300 [K]. 
     In the light emitting module  10   a,  blue LED  2   a  is arranged on a circumference on the top face of the substrate  1  in the vertical direction. In addition, in the light emitting module  10   a,  red LED  4   a  is arranged in the vicinity of a center on the top face of the substrate  1  in the vertical direction. In the red LED  4   a,  a quantity of light emission of the light emitting element is further decreased along with a temperature rise in the light emitting element, compared to the blue LED  2   a.  That is, the heat characteristics of the red LED  4   a  deteriorate since the quantity of light emission of the light emitting element is further decreased along with the temperature rise in the light emitting element, compared to the blue LED  2   a.  According to the first embodiment, since the substrate  1  is ceramics with low heat conductivity, it is possible to prevent heat which is emitted from the blue LED  2   a  from being conducted to the red LEDs  4   a  through the substrate  1 , and to suppress deterioration in a luminous efficiency of the red LED  4   a.    
     In addition, in  FIG. 1 , the blue LED  2   a  and the red LED  4   a  are described by omitting the number thereof. That is, as a first LED group, a plurality of blue LEDs  2   a  are arranged on the circumference of the top face of the substrate  1  in the vertical direction. In addition, as a second LED group, a plurality of red LEDs  4   a  are arranged in the vicinity of the center of the top face of the substrate  1  in the vertical direction. 
     The first LED group including the plurality of blue LEDs  2   a  is covered with a sealing member  3   a  from above. The sealing member  3   a  has a cross section of approximately a semicircle shape, or a trapezoidal shape on the top face of the substrate  1  in the vertical direction, and is formed as a toric shape so as to cover the plurality of blue LEDs  2   a.  In addition, the second LED group which includes the plurality of red LEDs  4   a  is covered with a sealing member  5   a  from above together with an entire concave portion formed by the inner surface of the toric portion which is formed by the sealing member  3   a  and the substrate  1 . 
     The sealing members  3   a  and  5   a  can be formed using various resins such as epoxy resin, urea resin, and silicon resin as a member. The sealing member  5   a  may be transparent resin with high diffusibility, without including phosphor. The sealing members  3   a  and  5   a  are formed using resin of different types. In addition, a refractive index of light of the sealing member  3   a  n 1 , a refractive index of light of the sealing member  5   a  n 2 , and a refractive index of light of gas sealed in a space which is formed by the body  11  and the cover  13  n 3  have a magnitude relationship of n 3 &lt;n 1 &lt;n 2 . Hereinafter, the gas which is sealed in the space which is formed by the body  11  and the cover  13  is referred to as “sealed gas”. The sealed gas is, for example, atmosphere. 
     In addition, in the light emitting module  10   a,  an electrode  6   a - 1  which will be described later is connected to the electrode connection unit  14   a - 1 . In addition, in the light emitting module  10   a  an electrode  8   a - 1  which will be described later is connected to the electrode connection unit  14   b - 1 . 
     The body  11  is formed using metal with good heat conductivity, for example, aluminum. The body  11  forms a columnar shape of which a horizontal cross section is approximately a circle, one end thereof is attached with the cover  13 , and the other end is attached with the base member  12   a.  In addition, the body  11  is formed so that the outer peripheral surface forms an approximately conical tapered surface of which a diameter becomes sequentially small from the one end toward the other end. An appearance of the body  11  is formed in a shape which is similar to a silhouette of a neck portion in a mini krypton light bulb. In the body  11 , a plurality of radiating fins which are radially protruded from the one end toward the other end (not shown) are integrally formed in the outer peripheral surface. 
     The base member  12   a  is, for example, an E-type base of an Edison type, and includes a cylindrical shell of a copper sheet including thread, and the conductive eyelet unit  12   b  which is provided at an apex portion of the lower end of the shell through an electric insulation unit. An opening portion of the shell is fixed to an opening portion of the other end of the body  11  being electrically insulated. The shell and the eyelet unit  12   b  are connected with an input line (not shown) which is derived from a power input terminal of a circuit board (not shown) in the control unit  14 . 
     The cover  13  configures a globe, and for example, is formed in a smooth curved shape which is similar to the mini krypton light bulb including an opening portion at one end, using milky-white polycarbonate. An opening end portion of the cover  13  is fixed by being fitted into the body  11  so as to cover the light emitting surface of the light emitting module  10   a.  In this manner, the lighting system  100   a  is configured as a lamp with a base which can substitute for the mini krypton light bulb, in which a globe as the cover  13  is included at one end, the E-type base member  12   a  is provided at the other end, and the entire appearance is similar to a silhouette of the mini krypton light bulb. In addition, as a method of fixing the cover  13  to the body  11 , any of adhering, fitting, screwing, locking, and the like may be used. 
     The control unit  14  accommodates a control circuit (not shown) which controls lighting of the blue LEDs  2   a  and the red LEDs  4   a  which are mounted on the substrate  1  so as to be electrically insulated from the outside. The control unit  14  supplies a DC voltage to the blue LEDs  2   a  and the red LEDs  4   a  by converting an AC voltage to the DC voltage by a control using the control circuit. In addition, in the control unit  14 , an output terminal of the control circuit is connected with the electric wiring  14   a  for supplying power to the blue LEDs  2   a  and the red LEDs  4   a.  In addition, in the control unit  14 , an input terminal of the control circuit is connected with the second electric wiring  14   b.  The electric wiring  14   a  and the electric wiring  14   b  are covered to be insulated. 
     The electric wiring  14   a  is derived to an opening portion at the one end of the body  11  through a through hole (not shown) which is formed in the body  11 , and a guide groove (not shown). In the electric wiring  14   a,  the electrode connection unit  14   a - 1  as a tip end portion of which an insulation cover is peeled is connected to the electrode  6   a - 1  of wiring which is arranged on the substrate  1 . The electrode  6   a - 1  will be described later. 
     In addition, the electric wiring  14   b  is derived to an opening portion at the one end of the body  11  through a through hole (not shown) which is formed in the body  11 , and a guide groove (not shown). In the electric wiring  14   b,  the electrode connection unit  14   b - 1  as a tip end portion of which an insulation cover is peeled is connected to the electrode  8   a - 1  of wiring which is arranged on the substrate  1 . The electrode  8   a - 1  will be described later. 
     In this manner, the control unit  14  supplies power which is input through the shell and the eyelet unit  12   b  to the blue LEDs  2   a  and the red LEDs  4   a  through the electric wiring  14   a.  In addition, the control unit  14  collects the power which is supplied to the blue LEDs  2   a  and the red LEDs  4   a  through the electric wiring  14   b.    
       FIG. 2  is a top view which illustrates the light emitting module according to the first embodiment.  FIG. 2  is the top view of the light emitting module  10   a  which is viewed in an arrow ‘A’ direction in  FIG. 1 . As illustrated in  FIG. 2 , the first LED group including the plurality of blue LEDs  2   a  is regularly arranged in a toric shape on the circumference at the center of the approximately rectangular substrate  1 . In addition, the first LED group including the plurality of blue LEDs  2   a  is entirely covered with the sealing member  3   a  in a toric shape. In the substrate  1 , a region which is covered with the sealing member  3   a  is referred to as a first area. 
     In addition, as illustrated in  FIG. 2 , the second LED group including the plurality of red LEDs  4   a  is regularly arranged in a lattice shape in the vicinity of the center of the approximately rectangular substrate  1 . In addition, the second LED group including the plurality of red LEDs  4   a  is entirely covered with the sealing member  5   a.  In addition, the sealing member  5   a  entirely covers the inside of the above described toric portion in the first region. In the substrate  1 , a region which is covered with the sealing member  5   a  is referred to as a second region. 
     As illustrated in  FIG. 2 , a shortest distance between the blue LED  2   a  and the red LED  4   a  is set to a distance D 1  between the blue LED  2   a  and the red LED  4   a.  In addition, the distance between the blue LED  2   a  and the red LED  4   a  is not limited to the shortest distance between the blue LED  2   a  and the red LED  4   a,  and may be a distance between a center position of the first LED group and a center position of the second LED group. In the example which is illustrated in  FIG. 2 , for example, the center position of the first LED group is a circumference which passes through each center of the blue LEDs  2   a  which are arranged in the toric shape. In addition, for example, the center position of the second LED group is a center of the red LEDs  4   a  which are arranged in the lattice shape. In this case, the distance between the blue LED  2   a  and the red LED  4   a  is a distance between the center at which the red LEDs  4   a  are arranged in the lattice shape and one point on the circumference which passes through each center of the blue LEDs  2   a  which are arranged in the toric shape. 
     The light emitting module  10   a  suppresses, for example, an influence which is caused when heat emitted from the blue LEDs is received by the red LEDs, even when a plurality of types of LEDs of which the heat characteristics are greatly different are arranged in combination on the ceramics substrate  1  by being separated into regions by the type of LEDs. Accordingly, the light emitting module  10   a  easily obtains desired luminous characteristics. 
     In addition, in the light emitting module  10   a,  for example, the blue LEDs and the red LEDs are arranged by being separated into regions. For this reason, in the light emitting module  10   a,  for example, since the heat which is emitted from the blue LEDs is suppressed so as not to be conducted to the red LEDs, it is possible to improve the heat characteristic of the whole of light emitting module  10   a.    
     In addition, the number of the blue LEDs  2   a  and the red LEDs  4   a,  and positions which are illustrated in  FIG. 2  are merely examples. That is, when it is a configuration in which the red LEDs  4   a  are regularly arranged in the vicinity of the center of the substrate  1 , and the blue LEDs  2   a  are regularly arranged so as to surround the red LEDs  4   a,  it may be any methods. Alternatively, for example, when the number of red LEDs  4   a  of which the heat characteristics are inferior to that of the blue LEDs  2   a  is small, it is possible to reduce a deterioration in the entire luminous characteristic of the light emitting module  10   a  due to the deterioration in the luminous characteristics of the red LEDs  4   a  which are caused by the heat. 
       FIG. 3  is a horizontal cross-sectional view which illustrates the lighting system on which the light emitting module according to the first embodiment is mounted.  FIG. 3  is a cross-sectional view in which the light emitting module  10   a  in  FIG. 2  is taken along line B-B. In  FIG. 3 , descriptions of the cover  13 , or the lower portion of the body  11  of the lighting system  100   a  are omitted. As illustrated in  FIG. 3 , the body  11  of the lighting system  100   a  includes a concave portion  11   a  which accommodates the substrate  1  of the light emitting module  10   a,  fixing members  15   a  and  15   b  which fix the substrate  1 . In the light emitting module  10   a,  the substrate  1  is accommodated in the concave portion  11   a  of the body  11 . 
     In addition, when an edge portion of the substrate  1  is pressed toward the lower part of the concave portion  11   a  by a pressing force of the fixing members  15   a  and  15   b,  the light emitting module  10   a  is fixed to the body  11 . In this manner, the light emitting module  10   a  is attached to the lighting system  100   a.  In addition, a method of attaching the light emitting module  10   a  to the lighting system  100   a  is not limited to the method which is illustrated in  FIG. 3 , and may be any of adhering, fitting, screwing, locking, and the like. 
     As illustrated in  FIG. 3 , the distance D 1  between the blue LED  2   a  and red LED  4   a  is longer than a thickness D 2  of the substrate  1  in the vertical direction. Heat that is emitted by light emitting from the blue LEDs  2   a  and red LEDs  4   a  is easily conducted in the horizontal direction rather than the vertical direction on the substrate  1 . For this reason, for example, heat which is emitted from the blue LEDs  2   a  is conducted to the red LEDs  4   a  through the horizontal direction of the substrate  1 , and the luminance efficiency of the red LEDs  4   a  further deteriorates. However, when setting the distance D 1  between the blue LED  2   a  and red LED  4   a  to be longer than the thickness D 2  of the substrate  1  in the vertical direction, it is possible to prevent the heat which is emitted from the blue LEDs  2   a  from being conducted to the red LEDs  4   a  through the horizontal direction of the substrate  1 . Accordingly, it is possible to suppress the deterioration in the luminous efficiency of the red LEDs  4   a.    
     In addition, as illustrated in  FIG. 3 , a height H 1  of the sealing member  3   a  is higher than a height H 2  of the sealing member  5   a.  An effect thereof will be described later with reference to  FIG. 5 . In addition, the height H 1  of the sealing member  3   a  and the height H 2  of the sealing member  5   a  may be the same. 
       FIG. 4  is a diagram which illustrates electric wiring of the light emitting module according to the first embodiment. As illustrated in  FIG. 4 , the light emitting module  10   a  includes the electrode  6   a - 1  which is connected to the electrode connection unit  14   a - 1  of the lighting system  100   a,  and wiring  6   a  which is extended from the electrode  6   a - 1  on the substrate  1 . In addition, the light emitting module  10   a  includes wiring  7   a  which is connected to the wiring  6   a  in parallel through the plurality of blue LEDs  2   a  which are connected in series by a bonding wire  9   a - 1  on the substrate  1 . In addition, the light emitting module  10   a  includes wiring  8   a  which is connected to the wiring  7   a  in parallel through the plurality of red LEDs  4   a  which are connected in series by a bonding wire  9   a - 2  on the substrate  1 . The wiring  8   a  includes the electrode  8   a - 1  which is connected to the electrode connection unit  14   b - 1  of the lighting system  100   a  at a tip end which is extended. 
     In this manner, by connecting the plurality of blue LEDs  2   a  and the plurality of red LEDs  4   a  which are connected in series in parallel by the bonding wire  9   a - 1 , and the bonding wire  9   a - 2 , an amount of electric current which flows in the vicinity of each blue LED  2   a  and red LED  4   a  is suppressed, and emitting of heat is suppressed. Accordingly, deterioration in the luminous characteristic due to the heat emission is reduced in the light emitting module  10   a.  Further, for example, the number of parallel connections of the red LEDs  4   a  which are connected in series by the bonding wire  9   a - 2  is set to be larger than that which is illustrated in  FIG. 4 , and a current which flows in one red LED  4   a  is set to be smaller than a current which flows in one blue LED  2   a.  In this manner, deterioration in the entire luminous characteristic of the light emitting module  10   a  is reduced which is caused by the deterioration in the luminous characteristics of the red LEDs  4   a  due to heat. 
       FIG. 5  is a diagram which illustrates reflection of luminous color of each light emitting element in the light emitting module according to the first embodiment. As an assumption in  FIG. 5 , as described above, the refractive index of light of the sealing member  3   a  n 1 , the refractive index of light of the sealing member  5   a  n 2 , and the refractive index of light of the sealed gas which is sealed in the space formed by the body  11  and the cover  13  n 3  have a magnitude relationship of n 3 &lt;n 1 &lt;n 2 . 
     Then, as denoted by a solid arrow in  FIG. 5 , light which is emitted from the red LED  4   a  is approximately totally reflected on the interface between the sealing member  5   a  and the sealed gas, and proceeds in the direction of the sealing member  3   a  due to the above described magnitude relationship in the refractive indices. In addition, as denoted by the solid arrow in  FIG. 5 , the light which is reflected on the interface between the sealing member  5   a  and the sealed gas, and proceeds to the direction of the sealing member  3   a  refracts on the interface between the sealing member  5   a  and the sealing member  3   a,  and proceeds to the inside of the sealing member  3   a  due to the above described magnitude relationship in the refractive indices. 
     On the other hand, as is denoted by an arrow of two dotted dashed line in  FIG. 5 , light which is emitted from the blue LED  2   a  refracts on the interface between the sealing member  3   a  and the sealed gas, and proceeds to the direction of the sealed gas due to the above described magnitude relationship in the refractive indices. In addition, most of light which is emitted from the blue LED  2   a  is reflected on the interface between the sealing members  3   a  and  5   a  due to the above described magnitude relationship in the refractive indices. In addition, the height H 1  of the sealing member  3   a  is larger than the height H 2  of the sealing member  5   a.  For this reason, it is possible to set an area of the interface between the sealing member  3   a  and the sealed gas to be large, while setting an area of the interface between the sealing member  3   a  and the sealing member  5   a  to be small. 
     In this manner, as illustrated in  FIG. 5 , since most of the light which is emitted from the blue LED  2   a,  and the light which is emitted from the red LED  4   a  are output by being moderately composed in the vicinity of the interface between the sealing member  3   a  and the sealed gas, it is possible to make the light emitted be uniformed. In addition, the light emitting module  10   a  efficiently extracts the light which is emitted from the red LED  4   a,  and efficiently composed with the light which is emitted from the blue LED  2   a,  it is possible to reduce the number of red LEDs  4   a  to be mounted. Accordingly, in the light emitting module  10   a,  deterioration in the entire luminous characteristic which is caused by the deterioration in the luminous characteristic of the red LEDs  4   a  due to heat is suppressed. 
     In addition, as denoted by an arrow of a broken line in  FIG. 5 , a part of the light which is emitted from the red LED  4   a  is refracted and proceeds to the direction of the sealed gas at the upper part of the sealing member  5   a  without reflecting on the interface between the sealing member  5   a  and the sealed gas. On the other hand, as denoted by an arrow of one dotted dashed line in  FIG. 5 , a part of the light which is emitted from the blue LED  2   a  is refracted on the interface between the sealing member  3   a  and the sealed gas, and proceeds to the direction of the sealed gas at the upper part of the sealing member  5   a.  In this manner, since the height of the sealing member  3   a  is larger than the height of the sealing member  5   a,  even when a part of the light which is emitted from the red LED  4   a  is output to the upper part from the sealing member  5   a,  the light of the blue LED  2   a  which is output from the upper region on the sealing member  5   a  side in the sealing member  3   a,  and the light of the red LED  4   a  which is output from the sealing member  5   a  are further uniformly mixed. Accordingly, even when LEDs of which luminous colors are different are provided in separate regions, it is possible to further suppress an uneven color when mixing colors. 
     In the light emitting module  10   a,  it is possible to avoid absorption of light by the phosphor, and to increase luminous efficiency by sealing the second region in which an amount of light emission is small, for example, the red LEDs  4   a  are arranged, using transparent resin not including the phosphor. In addition, in the light emitting module  10   a,  when the second region in which a predetermined number of red LEDs  4   a  are arranged is sealed with the transparent resin with high diffusibility, color unevenness of the LED module is suppressed since red light is efficiently diffused. That is, in the light emitting module  10   a,  it is possible to reduce decreasing in a color rendering property, and in the luminous efficiency of light which is emitted. 
     In addition, according to the above described first embodiment, the blue LEDs  2   a  are arranged on the substrate  1  in the toric shape, and the red LEDs  4   a  are arranged in the vicinity of the center of the toric shape. However, the shape is not limited to the toric shape, and may be any shape, if it is a shape which forms a ring shape such as a rectangular shape, a diamond shape, and other than those, without being limited to the toric shape. 
     According to the first embodiment, the light emitting module  10   a  includes the first light emitting element (for example, blue LED  2   a ) which emits first luminous color when being supplied with a current. In addition, the light emitting module  10   a  includes the second light emitting element (for example, red LED  4   a ) which emits second luminous color when being supplied with a current. In addition, the light emitting module  10   a  includes the substrate  1  on which the first light emitting element (for example, blue LED  2   a ) and the second light emitting element (for example, red LED  4   a ) are surface mounted on the same plane. In addition, the light emitting module  10   a  includes the first sealing unit (sealing unit  3   a ) which seals the first light emitting element (for example, blue LED  2   a ) which is surface mounted on the substrate  1 . In addition, the light emitting module  10   a  includes the second sealing unit (sealing unit  5   a ) which seals the second light emitting element (for example, red LED  4   a ) which is surface mounted on the substrate  1 , using a sealing member of which a refractive index is higher than that in the first sealing unit (sealing unit  3   a ), and is arranged so as to form an interface between the first sealing unit and the second sealing unit. In this manner, in the light emitting module  10   a,  un-uniform mixing of luminous color from the respective different light emitting elements is suppressed. 
     In addition, in the light emitting module  10   a,  a part of light beams of light emitted from the second light emitting element (for example, red LED  4   a ) which is reflected on an interface between the second sealing unit (sealing unit  5   a ) and gas at the upper part of the second sealing unit penetrates into the first sealing unit (sealing unit  3   a ) through the interface between the second sealing unit (sealing unit  5   a ) and the first sealing unit (sealing unit  3   a ). In addition, the light which penetrates into the first sealing unit (sealing unit  3   a ) is output to the outside from the first sealing unit (sealing unit  3   a ) along with the light which is emitted from the first light emitting element (for example, blue LED  2   a ). In this manner, in the light emitting module  10   a,  it is possible to suppress the un-uniform mixing of luminous color from the respective different light emitting elements, and to efficiently extract light which is emitted from the second light emitting element (for example, red LED  4   a ). 
     In addition, in the light emitting module  10   a,  the first light emitting element (for example, blue LED  2   a ) is arranged in the toric shape on the substrate  1 , and the second light emitting element (for example, red LED  4   a ) is arranged in the vicinity of the center of the toric shape on the substrate  1 . In addition, in the light emitting module  10   a,  the first sealing unit (sealing unit  3   a ) is formed in a toric shape so as to seal the first light emitting element (for example, blue LED  2   a ) by covering thereof from above on the substrate  1 , and the second sealing unit (sealing unit  5   a ) is formed so as to fill the inside of the toric shape of the first sealing unit (sealing unit  3   a ) by covering and sealing the second light emitting element (for example, red LED  4   a ) from above on the substrate  1 . In this manner, in the light emitting module  10   a,  it is possible to further suppress the un-uniform mixing of luminous color from the respective different light emitting elements, and to efficiently extract the light which is emitted from the second light emitting element (for example, red LED  4   a ). 
     In addition, in the light emitting module  10   a,  on the surface of the substrate  1 , the height of the first sealing unit (sealing unit  3   a ) is higher than the height of the second sealing unit (sealing unit  5   a ). In this manner, in the light emitting module, it is possible to suppress the un-uniform mixing of luminous color from the respective different light emitting elements, and to efficiently extract the light which is emitted from the second light emitting element (for example, red LED  4   a ). In addition, even when a part of light beams of light emitted from the second light emitting element (for example, red LED  4   a ) is output to the upper part from the second sealing unit (sealing unit  5   a ), since the height of the first sealing unit (sealing unit  3   a ) is higher than the height of the second sealing unit (sealing unit  5   a ), the light of the first light emitting element (for example, blue LED  2   a ) which is output from the upper region on the second sealing unit (sealing unit  5   a ) side in the first sealing unit (sealing unit  3   a ), and the light of the second light emitting element (for example, red LED  4   a ) which is output from the second sealing unit (sealing unit  5   a ) are further uniformly, and easily mixed. Accordingly, even when the LEDs with different luminous colors are provided at separate regions, it is possible to further suppress the color unevenness due to the color mixing. 
     An arrangement of LEDs in a second embodiment is different from that in the first embodiment. Since the second embodiment is the same as the first embodiment in other points than that, descriptions thereof will be omitted.  FIG. 6  is a top view which illustrates a light emitting module according to the second embodiment.  FIG. 6  is a top view of a light emitting module  10   b  according to the second embodiment which is viewed in the arrow ‘A’ direction in  FIG. 1 . 
     As illustrated in  FIG. 6 , in the light emitting module  10   b,  two first LED groups including a plurality of blue LEDs  2   b  are diagonally arranged on the substrate  1 . In addition, in the light emitting module  10   b,  two second LED groups including a plurality of red LEDs  4   b  are diagonally arranged so as to be symmetric to the arrangement of the first LED group with respect to the center of the substrate  1  on the substrate  1 . 
     The light emitting module  10   b  includes an electrode  6   b - 1  which is connected to the electrode connection unit  14   a - 1  of a lighting system  100   b,  and wiring  6   b  which is extended from the electrode  6   b - 1  on the substrate  1 . In addition, the light emitting module  10   b  includes the blue LEDs  2   b  which are connected in series by a bonding wire  9   b - 1 , and wiring  8   b  which is connected to the wiring  6   b  in parallel through the red LEDs  4   b  which are connected in series by a bonding wire  9   b - 2  on the substrate  1 . The wiring  8   b  includes an electrode  8   b - 1  which is connected to the electrode connection unit  14   b - 1  of the lighting system  100   b  at a tip end which is extended. In addition, the blue LEDs  2   b  have the same heat characteristics as those in the blue LEDs  2   a  according to the first embodiment. In addition, the red LEDs  4   b  have the same heat characteristics as those in the red LEDs  4   a  according to the first embodiment. 
     As illustrated in  FIG. 6 , when the blue LEDs  2   b  and the red LEDs  4   b  are arranged on the substrate  1 , a first region which is sealed with a sealing member  3   b,  and a second region which is sealed with a sealing member  5   b  are located at a position where it is symmetrical about a point with respect to the center of the substrate  1 . Accordingly, in the light emitting module  10   b,  it is possible to easily obtain a desired luminous pattern, and brightness, or hue of light by composing light which is emitted in each of the blue LEDs  2   b  and the red LEDs  4   b  in a good balance. 
     An arrangement of LEDs in a third embodiment is different from those in the first and second embodiments. Since the third embodiment is the same as the first and second embodiments in other points than that, descriptions thereof will be omitted.  FIG. 7  is a top view which illustrates alight emitting module according to the third embodiment.  FIG. 7  is the top view of a light emitting module  10   c  according to the third embodiment which is viewed in the arrow ‘A’ direction in  FIG. 1 . 
     As illustrated in  FIG. 7 , in the light emitting module  10   c,  a first LED group including a plurality of blue LEDs  2   c  is arranged in one region of the substrate  1  which is equally divided. In addition, in the light emitting module  10   c,  a second LED group including a plurality of red LEDs  4   c  is arranged in the other region, in which the first LED group is not arranged, of the substrate  1  which is equally divided. 
     The light emitting module  10   c  includes an electrode  6   c - 1  which is connected to the electrode connection unit  14   a - 1  of a lighting system  100   c,  and wiring  6   c  which is extended from the electrode  6   c - 1  on the substrate  1 . In addition, the light emitting module  10   c  includes the plurality of blue LEDs  2   c  which are connected in series by a bonding wire  9   c - 1 , and wiring  8   c  which is connected to the wiring  6   c  in parallel through the plurality of red LEDs  4   c  which are connected in series by a bonding wire  9   c - 2  on the substrate  1 . The wiring  8   c  includes an electrode  8   c - 1  which is connected to the electrode connection unit  14   b - 1  of the lighting system  100   c  at a tip end which is extended. In addition, the blue LEDs  2   c  have the same heat characteristics as those in the blue LEDs  2   a  according to the first embodiment. In addition, the red LEDs  4   c  have the same heat characteristics as those in the red LEDs  4   a  according to the first embodiment. 
     As illustrated in  FIG. 7 , a first region which is sealed with a sealing member  3   c  by arranging the blue LEDs  2   c  and the red LEDs  4   c  on the substrate  1 , and a second region which is sealed with a sealing member  5   c  are formed by being separated. Accordingly, the control unit  14  of the lighting system  100   c  can easily perform a driving control and heat managing of the respective blue LEDs  2   c  and red LEDs  4   c.  In addition, in the light emitting module  10   c,  it is possible to control deterioration of the whole heat characteristic which is caused by deterioration of heat characteristics of the red LEDs  4   c  due to heat. 
     The lighting systems  100   a  to  100   c  which are described in the above described embodiments have one system of a control circuit which supplies power to the LEDs. However, it is not limited to this, and the lighting systems  100   a  to  100   c  may include a sensor which detects heat, or brightness of the LEDs on the substrate  1 . In addition, the lighting systems  100   a  to  100   c  may include a control circuit of two systems which individually controls a driving current, or the driving pulse width of the blue LEDs  2   a  to  2   c,  and the red LEDs  4   a  to  4   c,  respectively, according to a detection result of the sensor. In the light emitting modules  10   a  to  10   c,  since the blue LEDs  2   a  to  2   c  and the red LEDs  4   a  to  4   c  are arranged in separate regions, it is possible to control the light emission of each LED efficiently. 
     In addition, according to the above described embodiments, the blue LEDs  2   a  to  2   c  are set to the first light emitting elements, and the red LEDs  4   a  to  4   c  are set to the second light emitting elements. However, it is not limited to this, and if it is a combination of the first light emitting elements and the second light emitting elements of which the heat characteristic is inferior to that of the first light emitting elements, it may be any light emitting elements regardless of the luminous color. In addition, in the above described embodiments, the substrate  1  is formed using alumina. However, when forming the substrate  1 , aluminum, or other materials than alumina may be used without being limited to. In addition, the sealing methods of the blue LEDs  2   a  to  2   c  and the red LEDs  4   a  to  4   c  using the sealing members  3   a  to  3   c,  and the sealing members  5   a  to  5   c  are not limited to those which are described in the embodiments, and various methods may be used. 
     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.