Abstract:
A light emitting device includes a light emitting body, a base for carrying the light emitting body, an encapsulating material covering the light emitting body and a wavelength conversion material mixing with the encapsulating material. The concentration of wavelength conversion material is characterized by the fact that the concentration of the wavelength conversion material is higher at the higher space that is further from the light emitting body located at the bottom of the light emitting device. Accordingly, the reflection rate of the mixture mixed with the encapsulating material and the wavelength conversion material has gradual variation, and the total reflection on the boundary is reduced thus improves the illumination efficiency.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a structure of a light emitting device and a manufacturing method thereof. The present invention in particular relates to a light emitting device with high illumination efficiency and a manufacturing method thereof. 
         [0003]    2. Description of Related Art 
         [0004]    Lighting apparatus sometimes has problems of low illuminating efficiency due to the packaging structure of the lighting apparatus. For solving this problem, particular steps are applied in the manufacturing procedure for increasing the illuminating efficiency. 
         [0005]    Please refer to  FIG. 1 , the structure of a traditional lighting unit is shown. The structure of the traditional lighting unit has a base  102 ′, a light emitting body  106 ′, transparent encapsulating material  108 ′, fluorescence powders  110 ′ and a lens  112 ′. The fluorescence powders  110 ′ are uniformly coated on the interior surface of the lens  112 ′ by a multi-coating process. The position of the fluorescence powder  110 ′ is away from the light emitting body  106 ′ so that the light reflected back to the light emitting body  106 ′ are decreasing in order so as to avoid the loss of light. However, this manufacturing method has some disadvantages. The multi-coating process that is used for the coating of the fluorescence powders  110 ′ is a complex procedure so that the cost associated is increased. Furthermore, reflection is induced on the boundary of the encapsulating material thereby causing the lighting efficiency to be reduced. 
         [0006]    The application of the lighting unit is restricted for the reason of complex manufacturing procedure and low lighting efficiency. Therefore, in view of this, the inventor proposes the present invention to overcome the above problems based on his expert experience and deliberate research. 
       SUMMARY OF THE INVENTION 
       [0007]    The primary object of the present invention is to provide an optimized manufacturing method and the product of the optimized manufacturing method having high illumination efficiency so that the application of the light emitting device is broadened. 
         [0008]    In order to achieve the above object, the present invention provides a light emitting device. The light emitting device comprises a light emitting body; a base carrying the light emitting body; an encapsulating material covering the light emitting body; a wavelength conversion material mixing with the encapsulating material; and wherein the concentration of the wavelength conversion material within the encapsulating material is higher as the area is further from the light emitting body. Furthermore, the wavelength conversion material layer includes a plurality of first fluorescence powders. In other word, the concentration of the fluorescence powders of the wavelength conversion material layer has a variation such that the concentration of the fluorescence powders of the wavelength conversion material layer is higher as a distance between the fluorescence powders and the light emitting body is greater (i.e. within the encapsulating material area, the further the area is from the light body, the greater concentration of the fluorescence powders in that area). Furthermore, the light emitting device has a lens disposed on the light emitting body. 
         [0009]    The present invention still provides another light emitting device. The light emitting device comprises a base having at least one lead frame; a light emitting body electrically arranged on the base and connected with the lead frame; a first encapsulating material formed on the light emitting body and the lead frame, wherein the first encapsulating material having a first wavelength conversion material layer with a plurality of first fluorescence powders. A concentration of the first fluorescence powders of the first wavelength conversion material layer gradually changes. The light emitting body is assembled on the lead frame of the base. The lead frame and the light emitting body are covered by the first encapsulating material which has the fluorescence powders therein. The first encapsulating material can be cured as a first wavelength conversion material layer. The concentration of the fluorescence powders of the first wavelength conversion material layer has a variation such that the concentration of the first fluorescence powders of the first wavelength conversion material layer is higher as a distance between the first fluorescence powders and the light emitting body is greater (i.e. within the encapsulating material, the further distance is from the light emitting body, the greater concentration of the fluorescence powders in that area). Furthermore, the light emitting device has a transparent encapsulating layer and a second wavelength conversion material layer. 
         [0010]    In order to achieve the above objects, the present invention provides a manufacturing method for a light emitting device. The manufacturing method comprises the following step. Step (a) is mixing an encapsulating material and a wavelength conversion material into a mixture. Step (b) is filling the mixture into the base correspondingly to the light emitting body. Step (c) is curing the mixture, wherein a concentration of the wavelength conversion material is higher in the area of the mixture that is further away from the light emitting body. Furthermore, a step of reversing the light emitting device proceeds before step (c), thus further introduce a step of providing a fixing member, such as a lens or a molding for fixing the position the mixture correspondingly to the light emitting body before the reversing step. 
         [0011]    The feature of the present invention is that the concentration of the wavelength conversion material layer has variation. For example, the concentration of the wavelength conversion material is higher at the higher space that is further from the light emitting body located at the bottom of the light emitting device. Accordingly, the reflection rate of the mixture mixed with the encapsulating material and the wavelength conversion material has gradual variation. Therefore, the total reflection on the boundary is reduced and the illumination efficiency is improved. 
         [0012]    In order to better understand the characteristics and technical contents of the present invention, a detailed description thereof will be made with reference to accompanying drawings. However, it should be understood that the drawings and the description are illustrative only and are not used to limit the scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  shows the light emitting device according to the prior art. 
           [0014]      FIG. 2  shows the first embodiment of a light emitting device according to the present invention. 
           [0015]      FIG. 3  shows the second embodiment of a light emitting device according to the present invention. 
           [0016]      FIG. 4  shows the third embodiment of a light emitting device according to the present invention. 
           [0017]      FIG. 5  shows the fourth embodiment of a light emitting device according to the present invention. 
           [0018]      FIG. 6  shows the fifth embodiment of a light emitting device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0019]    Please refer to  FIG. 2 , the present invention discloses a light emitting device and  FIG. 2  shows the first embodiment of the light emitting device. The light emitting device includes a light emitting body  206 , a base  202 , an encapsulating material  208 , and a wavelength conversion material  210  (i.e. a plurality of fluorescence powders). The base  202  is used for carrying the light emitting body  206 , and the encapsulating material  208  covers the light emitting body  206 . Furthermore, the wavelength conversion material  210  is mixed into the encapsulating material  208 . The concentration of the wavelength conversion material  210  composed of a plurality of fluorescence powders changes according to the distance between the wavelength conversion material  210  and the light emitting body  206  thereby improving the lighting characteristics of the light emitting device. In this embodiment, when the wavelength conversion material  210  is farther away from the light emitting body  206 , the concentration of the fluorescence powders of the wavelength conversion material  210  within the encapsulating material  208  is higher. 
         [0020]    The base  202  of the light emitting device has at least one lead frame  204 , please note that there is only one lead frame  204  illustrated for the simplicity but this particular number of lead frame is not meant to be limiting. The base  202  has a receiving room therein and the light emitting body  206  is assembled on the lead frame  204  in the receiving room. A lens  212  is assembled on the base  202  correspondingly to the light emitting body  206  (i.e. correspondingly to the light emitting body here means the center of the lens  212  aligns to the center of the light emitting body  206 ) and to the encapsulating material  208  (i.e. correspondingly to the encapsulating material  208  means the shape of the lens  212  corresponds to the shape of the encapsulating material  208 ). The mixture of the encapsulating material  208  and the wavelength conversion material  210  composed of a plurality of fluorescence powders is filled into the receiving room to cover the light emitting body  206 . Moreover, the receiving room is defined as a chamber by the lens  212  and the base  202 . In this embodiment, the light emitting body  206  is, but not restricted to, an LED (light emitting diode) and the encapsulating material is a thermosetting material. The feature of the present invention is that the concentration of the fluorescence powders of the wavelength conversion material  210  has a variation depending on the position of the fluorescence powders. For example, the concentration of the fluorescence powders of the wavelength conversion material  210  is higher in the area of the encapsulating material  208  that is further away from the light emitting body  206 . As shown in  FIG. 2 , the distance H 2  is greater than the distance HI in the encapsulating material  208 , and it shows that the concentration of the wavelength conversion material  210  on H 2  is higher than that on H 1 . 
         [0021]    The manufacturing method of the light emitting device has the following steps. First, the light emitting body  206  is assembled on the lead frame  204  of the base  202 . Next, the lens  212  is assembled on the base  202  and the chamber is defined. Next step is filling a mixture of an encapsulating material  208  and a wavelength conversion material  210  into the chamber defined by the lens  212  and the base  202 . At last, the structure is reversed and then baked. When the structure is reversed, the wavelength conversion material  210  can be concentrated on the position away from the light emitting body  206 . The encapsulating material  208  is cured to a baking temperature and to a baking time period. By the above-mentioned method, the structure has the concentration variation of higher wavelength conversion material concentration along the distance that is farther away from the light emitting body  206 . 
         [0022]    In addition, further has a mixing step for mixing the encapsulating material  208  and the wavelength conversion material  210  (i.e. a plurality of fluorescence powders) before or after assembling step according to process design. 
         [0023]    The encapsulating material  208  is a thermosetting material such as glue material and the wavelength conversion material  210  can be mixed in the encapsulating material  208 . The mixture of the encapsulating material  208  and the wavelength conversion material  210  is a curable composite material. 
         [0024]    By reversing the structure of the light emitting device, the wavelength conversion material  210  composed of the fluorescence powders is concentrated on the bottom of the encapsulating material  208  (i.e. away from the light emitting body  206 ) because of the gravity. The light loss resulted from total reflection on the boundary is decreased because the reflection ratio has a gradual variation which is resulted from the higher concentration at the position farther away from the light emitting body  206 . On the other hand, the fluorescence powders of the wavelength conversion material  210  are concentrated away from the light emitting body  206  so that the lighting efficiency of the light emitting device is improved. 
         [0025]    As the aforementioned description, the structure and the manufacturing method have different types. However, the concentration of the wavelength conversion material  210  in the encapsulating material  208  is changeable and the reflection ratio has a gradual variation. 
         [0026]      FIG. 3  shows the second embodiment of the light emitting device. The light emitting device includes a light emitting body  306 , a base  302 , an encapsulating material  308 , and a wavelength conversion material  310  (i.e. a plurality of fluorescence powders). The base  302  has at least one lead frame  304  which is used for carrying the light emitting body  306 , and the wavelength conversion material  310  is mixed into the encapsulating material  308 . The mixture of the encapsulating material  308  and the wavelength conversion material  310  covers the light emitting body  306 . 
         [0027]    The manufacturing method of the second embodiment has the following steps. First, the light emitting body  306  is assembled on the lead frame  304  of the base  302 . Next step is different from the first embodiment. A molding  314  shown in  FIG. 3  is assembled on the base  302  and the chamber is defined. Next step is filling the mixture of the encapsulating material  308  and the wavelength conversion material  310  into the chamber defined by molding  314  and base  302 . At last, the structure included the molding  314  is reversed and then baked. The molding  314  is released when the encapsulating material  308  cures. As result, the wavelength conversion material  310  can be concentrated at the position away from the light emitting body  306 . By the above-mentioned method, the concentration of wavelength conversion material in close proximity to the light emitting body  306  is nearly equal to zero so that the light emitted form the light emitting body  306  can project light in higher density. 
         [0028]    The encapsulating material  308  can be formed by two kinds of encapsulating materials. The first encapsulating material is disposed in close proximity to the light emitting body  306  as a transparent encapsulating layer and the second encapsulating material is disposed away from the light emitting body  306 . In other words, the first and second encapsulating materials can be the same or different transparent glue material. 
         [0029]    In addition, the manufacturing method of the second embodiment also can be a two-step method using two kinds of the encapsulating material  308 . The second encapsulating material with the wavelength conversion material  310  composed of a plurality of fluorescence powders is filled into the molding  314  and the first encapsulating material without the wavelength conversion material  310  is filled into the receiving room of the base  302 . Next, one of the first and second encapsulating materials is cured. Then assembling the molding  314  and the base  302  and curing the other encapsulating material. Alternatively, curing the other encapsulating material and then assembling the molding  314  and the base  302  is also accepted. However, the arc surface of the molding  314  always faces downward (i.e. reversing and baking step). At last, the molding  314  is released from the base  302  when the two encapsulating materials are totally cured. 
         [0030]    Please refer to  FIG. 4 , the third embodiment of the light emitting device is shown. The light emitting device includes a light emitting body  406 , a base  402 , an encapsulating material  408 , a wavelength conversion material  410  and a lens  412 . The base  402  has at least one lead frame  404  which is used for carrying the light emitting body  406 , and the lens  412  has a concave area  4121 , i.e., a trench concave down structure. The wavelength conversion material  410  is mixed into the encapsulating material  408 . The mixture of the encapsulating material  408  and the wavelength conversion material  410  is filled into the concave area  4121  of the lens  412  or a space defined by the lens  412  with the concave area  4121  and the base  402 . The composition of the wavelength conversion material  410  is higher under the condition that the wavelength conversion material  410  are closer to the bottom of the concave area  4121  (i.e. farther away from the light emitting body  406 ). Furthermore, the wavelength conversion material  410  concentrates within the concave area  4121 . In other words, the composition of the wavelength conversion material  410  is almost zero in the area of the encapsulating material  408  except the concave area  4121  of the lens  412 . 
         [0031]    The manufacturing method of the third embodiment similar to the first embodiment has the following steps. First, the light emitting body  406  is assembled on the lead frame  404  of the base  402 . Next, the lens  412  with concave area  4121  is assembled on the base  402  and a chamber is formed by the concave area  4121  of the lens  412  and a receiving room of the base  402 . Next step is filling a mixture of an encapsulating material  408  and a wavelength conversion material  410  into the chamber defined by the lens  412  and the base  402 . At last, the structure is reversed and then baked. When the structure is reversed, the wavelength conversion material  410  can be concentrated on the concave area  4121  of the lens  412 , especially on the position away from the light emitting body  406 . The encapsulating material  408  is cured to a baking temperature and to a baking time period. 
         [0032]    The manufacturing method of the third embodiment can also be a method similar to the second embodiment using two kinds of the encapsulating material  408 . A second encapsulating material mixed with a wavelength conversion material  410  composed of a plurality of fluorescence powders is filled into the concave area  4121  of the lens  412  and the concave area  4121  is full of the mixture of the second encapsulating material and the wavelength conversion material  410 . Then, the lens  412  is reversed (i.e. the arc surface of the lens facing downward) for being baked. That is to say that the mixture filled the concave area is cured. As result, the composition of the wavelength conversion material  410  of the cured mixture is higher at the bottom of the concave area  4121  (i.e. farther away from the light emitting body  406 ). Next, the light emitting body  406  is assembled on the lead frame  404  of the base  402 . Then, an optical structure combined the lens  412  and the cured mixture within thereof is assembled with the base  402  correspondingly to the light emitting body  406 . Next, the first encapsulating material without the wavelength conversion material  410  is filled into the chamber defined by the optical structure and the base  402 . At last, curing the first encapsulating material and then the lens  412  and the base  402  can be fixed. 
         [0033]    Please refer to  FIG. 5 , which shows the fourth embodiment of the light emitting device. The light emitting device includes a light emitting body  506 , a base  502 , an encapsulating material  508 , and a wavelength conversion material  510  composed of a plurality of fluorescence powders. The base  502  has at least one lead frame  504  which is used for carrying the light emitting body  506 , and a lens  512  is assembled with the base  502  correspondingly to the top of the light emitting body  506  (i.e. lens  512  aligns so that its center corresponds to the top center of the light emitting body  506 ). The wavelength conversion material  510  is mixed into the encapsulating material  508  and the mixture is filled into the chamber defined by the lens  512  and the base  502 . The concentration of the wavelength conversion material  510  is higher in area that is further away from the light emitting body  506 . In this embodiment, the feature different from the first embodiment is that the concentration of the fluorescence powders of wavelength conversion material  510  are almost zero in the area in close proximity to the light emitting body  506 . 
         [0034]    The manufacturing method of the light emitting device has the following steps. First, the light emitting body  506  is assembled on the lead frame  504  of the base  502 . Next step is filling the encapsulating material  508  into the receiving room of the base  502 , however the receiving room is not filled full of the encapsulating material  508 . Next step is curing the encapsulating material  508 . Next, the lens  512  is assembled on the base  502  correspondingly to the light emitting body  506  (i.e. corresponds here means that the center of the lens  512  is in alignment with the center of the light emitting body  506 ). Then, mixing the encapsulating material  508  and the fluorescence powders  510 , and the mixture of the encapsulating material  508  and the fluorescence powders  510  is filled into the remaining chamber space defined by lens  512  and base  502  (i.e. there is cured encapsulating material  508  inside the chamber). At last, the structure is reversed and then baked. By the above-mentioned method, the structure achieves fluorescence powder concentration variation, wherein the structure has higher fluorescence powder concentration within the area of encapsulating material  508  that is further away from the light emitting body  506 . 
         [0035]    The encapsulating material  508  can be of two kinds. The first encapsulating material is disposed in close proximity to the light emitting body  506  and the second encapsulating material is disposed away from the light emitting body  506 . In other words, the first and second encapsulating materials can be the same or different transparent glue material. 
         [0036]    The manufacturing method of the third embodiment can be a method using two kinds of the encapsulating material  508 . First, the light emitting body  506  is assembled on the lead frame  504  of the base  502 . Next step is filling the first encapsulating material into the receiving room of the base  502 , however the receiving room is not filled full of the first encapsulating material. Next, the lens  512  is assembled on the base  502  correspondingly to the light emitting body  506  (i.e. the center of the lens is aligned to the center of the light emitting body). Then, the mixture of the second encapsulating material and the fluorescence powders  510  is filled into the remaining chamber space defined by lens  512  and base  502  (i.e. there is cured first encapsulating material inside the chamber). At last, the structure is reversed and then baked. By the above-mentioned method, the structure achieves fluorescence powder concentration variation, wherein the structure has higher fluorescence powder concentration within the area of encapsulating material  508  that is further away from the light emitting body  506 . 
         [0037]      FIG. 6  shows the fifth embodiment of the light emitting device. The light emitting device includes a light emitting body  606 , a base  602 , an encapsulating material  608 , and a plurality of fluorescence powders  610 . The base  602  has at least one lead frame  604  which is used for carrying the light emitting body  606 , and a lens  612  is assembled with the base  602  correspondingly to the light emitting body  606  (i.e. the center of the lens  612  is in alignment with the center of the light emitting body  606 ). The fluorescence powders  610  and the encapsulating material  608  are disposed in the chamber defined by the lens  612  and the base  602 . The feature differs for the fifth embodiment is that the concentration of the fluorescence powders  610  increases and then decreases along the distance between the fluorescence powders  610  and the light emitting body  606 . Furthermore, there is almost no fluorescence powder  610  in close proximity to the light emitting body  606 . Alternatively, the concentration of the fluorescence powders  610  increases and then levels off as the distance between the fluorescence powders  610  and the light emitting body  606  is increasing. 
         [0038]    The manufacturing method of the light emitting device of  FIG. 6  has the following two steps. First, the light emitting body  606  is assembled on the lead frame  604  of the base  602 , and the lens  612  is assembled on the base  602 . Then, the fluorescence powders  610  and the encapsulating material  608  are mixed as a first mixture. Next is filling the first mixture into a first chamber defined by the base  602  and a chock (the lens  612  may be as a chock) however the first chamber is smaller than the receiving room of the base  602 . Next is reversing the structure and then curing the first mixture as a first wavelength conversion material layer  6082  &amp;  6081 . In the first wavelength conversion material layer  6082  &amp;  6081 , the concentration of the fluorescence powders  610  increases as the distance to light emitting body  606  becomes greater. Next step is mixing the encapsulating material  608  and the fluorescence powders  610  as a second mixture and the concentration of the fluorescence powders  610  of the second mixture is lower than that of the first mixture. The second mixture is filled into a second chamber defined by the first wavelength conversion material layer  6082  &amp;  6081  and the lens  612 . At last, the structure is baked in order to form a second wavelength conversion material layer  6083  with a plurality of fluorescence powders  610  disposed on the first wavelength conversion material layer  6082 . By the above-mentioned method, the structure has the concentration variation of the fluorescence powders  610  and the concentration of the fluorescence powders  610  increases and then decreases as the distance is increasing from the light emitting body  606 . 
         [0039]    In addition, the second chamber also can be defined by the first wavelength conversion material layer  6082  &amp;  6081  and a molding. Then the second chamber is filled with the second mixture and then baked thereof. The molding is released when the second mixture cures. As result, the lens  612  is also formed as/with the second wavelength conversion material layer. By the above-mentioned method, the concentration of the fluorescence powders  610  decreases gradually from the interface of the first wavelength conversion material layer and the second wavelength conversion material layer  6083 . 
         [0040]    Another manufacturing method of the light emitting device of  FIG. 6  has the following three steps. First, the light emitting body  606  is assembled on the lead frame  604  of the base  602 , and the encapsulating material  608  is filled into the receiving room of the base  602  however the receiving room is not filled full of the encapsulating material  608 . Next step is curing the encapsulating material  608  to form a transparent encapsulating layer  6081 . Then, the chock (lens  612  may play as the chock) is assembled on the base  602 . Then, the fluorescence powders  610  and the encapsulating material  608  are mixed as a first mixture. Next step is filling the first mixture into the first chamber defined by the transparent encapsulating layer  6081  and the chock; and the first chamber is smaller than the receiving room of the base  602 . Next is reversing the structure and curing the first mixture as a first wavelength conversion material layer  6082  (i.e. the second step is used for forming the first wavelength conversion material layer  6082 ). In the first wavelength conversion material layer  6802 , the concentration of the fluorescence powders  610  increases as the distance between the fluorescence powders  610  and the light emitting body  606  increases. Next step is mixing the encapsulating material  608  and the fluorescence powders  610  as a second mixture and the concentration of the second mixture is smaller than that of the first mixture. The second mixture is filled into a second chamber, the residual space of receiving room of the base  602 (i.e. there are a transparent encapsulating layer  6801  and a first wavelength conversion material layer  6802  inside the room). At last, the structure is baked in order to cure the second mixture into a second wavelength conversion material layer  6083  (i.e. the third step is used for forming the second wavelength conversion material layer  6083 ). By the above-mentioned method, the structure achieves fluorescence powders concentration variation, wherein the fluorescence powders  610  and the concentration of the fluorescence powders  610  increases and then decreases as the distance between the fluorescence powders  610  and the light emitting body  606  is increasing. 
         [0041]    In addition, the lens  612  of this embodiment also can have a concave area or another structure in the previous-mentioned embodiments. 
         [0042]    Moreover, the multi-layer encapsulating structure which is formed by the first wavelength conversion material layer  6082  &amp;  6081 , and the second wavelength conversion material layer  6083  can be adopted at least two kinds of encapsulating materials. And the first wavelength conversion material layer includes a plurality of first fluorescence powders away from the light emitting body  606  and a first encapsulating material. The second wavelength conversion material layer  6083  is composed of a second encapsulating material and a plurality of second fluorescence powders disposed close to the interface of the two wavelength conversion material layer. That is to say, the first and second encapsulating materials can be the same or different transparent glue material. The concentration of the first fluorescence powders of the first wavelength conversion material layer gradually changes and the concentration of the second fluorescence powders of the second wavelength conversion material layer changes gradually. 
         [0043]    In addition, the multi-layers encapsulating structure of the light emitting device also further includes a third wavelength conversion material layer with a plurality of third fluorescence powders disposed on the second wavelength conversion material layer, wherein the concentration of the third fluorescence powders on a side of the third wavelength conversion material layer that is in close to the second wavelength conversion material layer is lower than the concentration of the third fluorescence powders on an opposite side of the third wavelength conversion material layer that is further away from the first wavelength conversion material layer. In other words, the design of the multi-layers encapsulating structure depends on optical requirement. 
         [0044]    The manufacturing method of the light emitting device of three encapsulating materials and three fluorescence powders has the following steps. First, the light emitting body  606  is assembled on the lead frame  604  of the base  602  and the lens  612  is assembled on the base  602 . Next is filling a first mixture composed of the first fluorescence powders and the first encapsulating material into a first chamber defined by the base  602  and the chock (not shown in figure); then reversing the structure and curing the first mixture to form a first wavelength conversion material layer  6082  (i.e. the first step is used for forming the first wavelength conversion material layer  6082 ). In the first wavelength conversion material layer  6082 , the concentration of the first fluorescence powders increases as the distance between the first fluorescence powders and the light emitting body  606  increases. Next step is filling a second mixture composed of the second fluorescence powders and the second encapsulating material into a space of receiving room of the base  602  and then curing the second mixture as a second wavelength conversion material layer  6083 . Wherein, the second chamber can be as a part or all the residual space of receiving room of the base  602  (i.e. there is a first fluorescence layer inside the chamber) Next step is filling a third mixture composed of the third fluorescence powders and the third encapsulating material into a space defined by the second wavelength conversion material layer  6083  and a chock/a lens/a molding. At last, reversing the following structure and then baked it. 
         [0045]    Furthermore, a transparent encapsulating material may be filled into the receiving room of the base  602  before the step of forming the first wavelength conversion material layer  6082 ; however the receiving room is not full of the transparent encapsulating material. Then, the transparent encapsulating material is cured. Therefore, the concentration of the fluorescence powders in close proximity to the light emitting body  606  is almost zero. 
         [0046]    Furthermore, in all embodiments, the light emitting device includes a first electrical terminal and a second electrical terminal and the first and the second terminals are electrically and conductively connected to the light emitting body. 
         [0047]    Although the present invention has been described with reference to the foregoing preferred embodiment, it shall be understood that the present invention is not limited to the details thereof. Various equivalent variations and modifications may occur to those skilled in this art in view of the teachings of the present invention. Thus, all such variations and equivalent modifications are also embraced within the scope of the present invention as defined in the appended claims.