Abstract:
In a side surface light emitting type light emitting device mounted on the surface of a wiring board, the light emitting device comprises: a base body part having a reflecting case and a terminal holding part formed integrally with the reflecting case in the rear part of the reflecting case; and lead members inserted into the base body part, having a pair of connecting parts including base parts of the connecting parts drawn out from the lower surface of the base body part and bent along the lower surface and side bending parts provided in the base parts of the connecting parts and bent along the side surfaces of the terminal holding part and connected to a pattern of the wiring board; and is characterized in that the base parts of the connecting parts are provided with protruding parts protruding toward the center of the lower surface of the terminal holding part and cut-out parts are provided for accommodating the protruding parts in the lower surface of the terminal holding part.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a side surface light emitting type light emitting device mounted on the surface of a wiring board. 
     2. Description of the Related Art 
     An example of the light emitting device of the above-described type is disclosed in Patent Document 1. In this light emitting device, lead members are drawn out from both side parts of a reflecting case having a front part opened and a planar bottom part, and a terminal holding part is integrally provided in the rear part of the reflecting case. The parts of the lead members that are drawn out from the reflecting case are bent along the side surfaces of the terminal holding part from the side parts of the reflecting case, and further bent along the lower surface of the terminal holding part and ends thereof are accommodated in cut out parts as connecting parts. 
     On the other hand, Patent Document 2 discloses a side surface light emitting type light emitting device in which lead members are drawn out from the lower surface of a reflecting case of the light emitting device and bent along the lower surface of a terminal holding part. Further, Patent Document 3 discloses a structure that lead members drawn out from the lower part of a light reflecting case of a light emitting device and bent along the lower surface of a terminal holding part are further bent along the side surfaces of the terminal holding part.
     Patent Document 1: JP-A-2006-253551   Patent Document 2: Japanese Design Registration No. 1171708   Patent Document 3: Japanese Design Registration No. 1288058   

     It has been required for a recent light emitting device to have a high output. Therefore, the light emitting device is liable to mount a high output LED chip thereon. The high output LED chip generates a great heat. When the temperature of the LED chip itself becomes high, the output of the LED chip is undesirably low. Thus, heat needs to be effectively radiated from the LED chip. Since a side surface light emitting type light emitting device is used as a light source of a display of a portable telephone, the side surface light emitting type light emitting device needs to be compact. Accordingly, a heat radiating member such as a heat sink is not used to transmit the heat to a wiring board through a lead member on which the LED chip is mounted and radiate the heat. In the light emitting device disclosed in the Patent Document 1, the lead members are drawn out from both the side parts of the reflecting case. However, since the side surface light emitting type light emitting device is long in a transverse direction, a heat radiating path is long so that a heat radiating effect is low. On the other hand, in the light emitting devices disclosed in the Patent Documents 2 and 3, since the lead members are drawn out from the lower surface of the reflecting case, a heat radiating path is short. However, since a drawn out part of the lead member is compact depending on the miniaturization of the light emitting device, a contact area of the lead members and the wiring board is relatively reduced. Thus, an adequate heat radiating effect cannot be obtained. 
     SUMMARY OF THE INVENTION 
     Thus, it is an object of the present invention to provide a structure compact and high in its heat radiating effect in a side surface light emitting type light emitting device. 
     The present invention is devised to achieve the above-described object and the structure thereof is defined as described below. 
     In a side surface light emitting type light emitting device mounted on the surface of a wiring board, the light emitting device comprises: a base body part having a reflecting case and a terminal holding part formed integrally with the reflecting case in the rear part of the reflecting case; and lead members inserted into the base body part, having a pair of connecting parts including base parts of the connecting parts drawn out from the lower surface of the base body part and bent along the lower surface and side bending parts provided in the base parts of the connecting parts and bent along the side surfaces of the terminal holding part and connected to a pattern of the wiring board; and is characterized in that the base parts of the connecting parts are provided with protruding parts protruding toward the center of the lower surface of the terminal holding part and cut-out parts are provided for accommodating the protruding parts in the lower surface of the terminal holding part. 
     In the light emitting device constructed as described above, the lead members are provided with the protruding parts protruding toward the center of the lower surface of the terminal holding part. Since the protruding parts are formed integrally with the lead members, the protruding parts are allowed to come into contact with the wiring board to improve a heat radiating effect. That is, the protruding parts play the role of heat radiating plates. Since the protruding parts are accommodated in the cut out parts in the lower surface of the terminal holding part and do not protrude to an external part, the device can be made to be compact. Further, an external force is prevented from being excessively exerted on the lead members to reduce the bending or breakage of the lead members. Further, since the protruding parts form a part of the connecting parts for connecting the lead members to the wiring board, the connecting area of the connecting parts of the lead members and the wiring board is increased. Thus, even when a position on which the light emitting device is mounted is slightly shifted, it is permissible. Accordingly, the light emitting device is easily mounted. As a result, workability in attaching is improved and a yield is improved. 
     According to a second aspect of the present invention, the present invention is defined as described below. That is, in the light emitting device according to the first aspect, the lower surfaces of the base parts of the connecting parts and the lower surfaces of the protruding parts are flush with the lower surface of the reflecting case. 
     According to the invention of the second aspect defined as described above, the connecting parts do not protrude from the lower part of the device. Thus, a light emitting area of the light emitting device is ensured and the thickness of the entire part of the device can be reduced at the same time. 
     According to a third aspect of the present invention, the present invention is defined as described below. That is, in the light emitting device according to the first or second aspect, the protruding parts are provided in the ends of the base parts of the connecting parts. 
     According to the invention of the third aspect defined as described above, the protruding parts are provided at positions sufficiently separated from the bending parts (namely, bottom parts drawn out from the reflecting case) of the base parts of the connecting parts. 
     Since the side surface light emitting type light emitting device is frequently exclusively used for a light source for lighting a portable telephone, an entire size is regulated. As a result, the base body part ordinarily formed with a resin is apt to be made of a thin member. When a force required for bending the base part of the connecting part drawn out in such a base body part is increased, there is a fear that an excessive force is exerted on the base body part to deteriorate a mechanical strength. Thus, when the protruding part is provided at a position sufficiently separated from the bending part of the base part of the connecting part, since the width of the bending part is not enlarged due to the protruding part, the force required for bending the base part of the connecting part is not increased. Thus, the mechanical strength of the base body part is prevented from being deteriorated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a light emitting device of an embodiment of the present invention.  FIG. 1(A)  is perspective view showing a light emitting device  1  from a front surface.  FIG. 1(B)  is a perspective view showing the light emitting device from a bottom surface. 
         FIG. 2  is a hexahedral view.  FIG. 2(A)  is a plan view.  FIG. 2(B)  is a left side view.  FIG. 2(C)  is a front view.  FIG. 2(D)  is a right side view.  FIG. 2(E)  is a bottom view.  FIG. 2(F)  is a rear view. 
         FIG. 3  is a sectional view taken along a line I-I in  FIG. 2(C) . 
         FIG. 4  is a sectional view taken along a line II-II in  FIG. 2(C) . 
         FIG. 5  is a sectional view taken along a line III-III in  FIG. 2(C) . 
         FIG. 6  is a diagram showing a production process of the light emitting device of the embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, an embodiment of the present invention will be described below by referring to an illustrated example. 
       FIG. 1(A)  is perspective view showing a light emitting device  1  of the embodiment from a front surface.  FIG. 1(B)  is a perspective view showing the light emitting device from a bottom surface.  FIG. 2  is a hexahedral view.  FIG. 2(A)  is a plan view.  FIG. 2(B)  is a left side view.  FIG. 2(C)  is a front view.  FIG. 2(D)  is a right side view.  FIG. 2(E)  is a bottom view  FIG. 2(F)  is a rear view.  FIG. 3  is a sectional view taken along a line I-I in  FIG. 2(C) .  FIG. 4  is a sectional view taken along a line II-II in  FIG. 2(C) .  FIG. 5  is a sectional view taken along a line III-III in  FIG. 2(C) . 
     As shown in  FIG. 1(B) , the light emitting device  1  of the embodiment includes a base body part  10 , a first lead member  3  and a second lead member  4 . 
     The base body part  10  includes a reflecting case  11  and a terminal holding part  20 . As shown in  FIG. 3 , the reflecting case  11  has a transversely long cup shape and an inner peripheral surface of a recessed part  13  serves as a reflecting surface. The recessed part  13  is filled with a silicone resin type sealing member to form a sealing part  70 . 
     The inner peripheral surface of the recessed part  13  includes a side wall part  151  and a bottom part  153 . In the bottom part  153 , insert parts  31  and  41  of the lead members  3  and  4  are exposed. A material with which the reflecting case  11  is formed is a resin material. The insert parts  31  and  41  are coated with the resin material to increase a contact area of the resin to resin to the sealing member made of the silicone resin so that an adhesion by the sealing member can be improved. Here, the contact area of the resin to resin is the contact area between the resin of the reflecting case and the (silicone) resin of the sealing member. Further, the inner peripheral surface of the recessed part  13  can be coated with a white paint. 
     As shown in  FIG. 2(E) , the terminal holding part  20  is formed integrally with the reflecting case  11  in the rear part of the reflecting case  11  and entirely solid. In the side surfaces of the terminal holding part  20 , two cut out parts  23  and  24  are formed. In the lower surface (a bottom surface side) of the terminal holding part  20 , cut out parts  25  and  26  are formed that are directed toward a central part from both the side parts of the terminal holding part  20 . 
     The first lead member  3  includes the insert part  31  and a connecting part  30 . As shown in  FIG. 3 , the insert part  31  has a length of about ¾ as long as the length of the base body part  10  in the transverse direction of the base body part  10 . In the insert part  31 , an LED chip  60  is mounted on a part located at a substantially central part of the reflecting case  11  by a well-known method. In the first lead member  3 , a part drawn outside from the base body part  10  is the connecting part  30 . As shown in  FIG. 2(E) , the connecting part  30  includes a base part  32  of a connecting part, a side surface bending part  33  provided at an end of the base part  32  of the connecting part and a protruding part  34 . Under a state before the side surface bending part  33  and the protruding part  34  are bent, the side surface bending part  33  and the protruding part  34  are formed in a linear shape. That is, the connecting part  30  has a T shape. Initially, the base part  32  of the connecting part is bent to a lower side (a rear surface side) along the lower surface of the terminal holding part  20  and the protruding part  34  at the end of the connecting part  30  is accommodated in the cut out part  25  of the terminal holding part  20 . Then, the side surface bending part  33  is bent along the side surface of the terminal holding part  20  and accommodated in the first cut out part  23 . When the light emitting device  1  is observed from an upper surface, as shown in  FIG. 2(A) , an upper end part of the side surface bending part  33  is located at a side part of the terminal holding part  20 . When the light emitting device  1  is observed from a front surface, as shown in  FIG. 2(C) , the side surface bending part  33  slightly protrudes outside along a right side surface of the reflecting case  11 . When the light emitting device  1  is observed from a right side surface side, as shown in  FIG. 2(D) , the side surface bending part  33  is exposed in the right side surface of the light emitting device  1 . In  FIG. 2(D) , the height of the side surface bending part  33  is a little higher than ½ as high as the height (thickness) of the light emitting device  1 . When the light emitting device  1  is observed from a rear surface side, as shown in  FIG. 2(F) , the connecting part  30  has an L shape and forms a part of an outer edge of the light emitting device  1 . On the other hand, the protruding part  34  protrudes toward a central side of a lower surface of the terminal holding part  20  as shown in  FIG. 2(E) . 
     The second lead member  4  includes the insert part  41  and a connecting part  40 . As shown in  FIG. 3 , the insert part  41  has a length of about ¼ as long as the length of the base body part  10  in the transverse direction of the base body part  10 . In the second lead member  4 , a part drawn outside from the base body part  10  is the connecting part  40 . As shown in  FIG. 2(E) , the connecting part  40  includes, similarly to the connecting part  30  of the first lead member  3 , a base part  42  of a connecting part, a side surface bending part  43  provided at an end of the base part  42  of the connecting part and a protruding part  44 . Initially, the base part  42  of the connecting part is bent to a lower side (a rear surface side) along the lower surface of the terminal holding part  20  and the protruding part  44  is accommodated in the cut out part  26  of the terminal holding part  20 . Then, the side surface bending part  43  is bent along the side surface of the terminal holding part  20  and accommodated in the second cut out part  24 . When the light emitting device  1  is observed from an upper surface, as shown in  FIG. 2(A) , an upper end part of the side surface bending part  43  is located at a side part of the terminal holding part  20 . When the light emitting device  1  is observed from a front surface, as shown in  FIG. 2(C) , the side surface bending part  43  slightly protrudes outside along a left side surface of the reflecting case  11 . When the light emitting device  1  is observed from a left surface side, as shown in  FIG. 2(B) , the side surface bending part  43  is exposed in the left side surface of the light emitting device  1 . In  FIG. 2(B) , the height of the side surface bending part  43  is a little higher than ½ as high as the height (thickness) of the light emitting device  1  like the side surface bending part  33 . When the light emitting device  1  is observed from a rear surface side, as shown in  FIG. 2(F) , the connecting part  40  has an L shape and forms a part of an outer edge of the light emitting device  1 . On the other hand, the protruding part  44  protrudes toward a central side of a lower surface of the terminal holding part  20  as shown in  FIG. 2(E) . 
     In the above-description, the base body part  10  may be formed by using a resin material such as nylon or an inorganic material such as ceramics. The base body part  10  may be formed with a white material and a material itself may have a reflection performance. 
     As the lead members  3  and  4 , a copper plate or Al may be used. In this embodiment, to obtain a good reflection by the lead members  3  and  4 , a surface is plated with Ag. 
     As the LED chip  60 , a semiconductor light emitting element of a nitride compound of a III group that emits the light of short wavelength is employed. A suitable phosphor is combined with the LED chip  60  to obtain a white light emission. In this embodiment, as the LED chip, a blue color light emitting diode and a phosphor that absorbs a blue color light and emits a yellow light are selected. The color of the emitted light of the LED chip can be arbitrarily selected. Further, a plurality of LED chips can be mounted on the lead member. 
     The light emitting device  1  of the embodiment is produced as described below. 
     The copper plate is pressed and stamped to obtain the lead members  3  and  4  under a state that the connecting parts  30  and  40  are expanded. Then, the lead members  3  and  4  are inserted to the base body part  10  to injection mold the base body part  1 . Then, the LED chip  60  is mounted on the first lead member  3  to bond wires  63  and  64 . The LED chip  60  and the wires  63  and  64  are sealed by a light transmitting silicone resin from the viewpoint of durability. The phosphors may be dispersed in the silicone resin. After that, the copper plate is cut and divided to obtain a state shown in  FIG. 6 . 
     As shown in  FIG. 6 , in the first lead member  3 , a drawn out part  130  is drawn out downward in the lower surface of the base body part  10  in the right side of a sheet surface. The drawn out part  130  has a T shape and includes a base part  132  of a drawn out part and ends  133  and  134 . Initially, the base part  132  of the drawn out part is bent along the lower surface of the terminal holding part  20  to have the base part  32  of the connecting part. At the same time, the end  134  is accommodated in the cut out part  25  directed toward the central part of the lower surface of the terminal holding part  20  to have the protruding part  34 . Here, the depth of the cut out part  25  is slightly larger than the thickness of the protruding part  34 . The lower surface of the protruding part  34  is flush with the lower surface of the reflecting case  11  as shown in  FIG. 2(C) . Then, the end  133  is bent along the side surface of the terminal holding part  20  to have the side bending part  33 . The side bending part  33  is exposed on the right side surface of the light emitting device  1  as shown in  FIG. 2(D) . In the second lead member  4 , a T shaped drawn out part  140  including a base part  142  of a drawn out part and ends  143  and  144  is drawn out similarly to the first lead member  3  and sequentially bent to form the base part  42  of the connecting part, the side bending part  43  and the protruding part  44 . The side bending part  43  is exposed in the left side surface of the light emitting device  1  as shown in  FIG. 2(B) . Further, the lower surface of the protruding part  44  is flush with the lower surface of the reflecting case  11  like the protruding part  34  (see  FIG. 2(C) ). 
     In the emitting device  1  produced in such a way, under a state that the emitting device  1  is mounted on the wiring board (not shown in the drawing), since the protruding parts  34  and  44  come into contact with the wiring board, a heat radiating effect is increased. That is, the protruding parts  34  and  44  function as heat radiating plates. Since the protruding parts  34  and  44  are accommodated in the cut out parts  25  and  26  in the lower surface of the terminal holding part  20  and do not protrude outside, the protruding parts  34  and  44  contribute to the miniaturization of the light emitting device  1 . Further, an external force is prevented from being excessively exerted on the lead members  3  and  4  to reduce the bending or breakage of the lead members  3  and  4 . Further, since the protruding parts  34  and  44  form a part of the connecting parts  30  and  40 , the protruding parts  34  and  44  are provided to increase the connecting area of the connecting parts  30  and  40  of the lead members and the wiring board. Thus, a tolerance in shift of a mounting position of the light emitting device  1  is increased. Accordingly, the light emitting device  1  is easily mounted. As a result, workability in attaching is improved and a yield is improved. 
     As shown in  FIG. 2  (C), the lower surfaces of the bases  32  and  42  of the connecting parts and the lower surfaces of the protruding parts  34  and  44  are flush with the lower surface of the reflecting case  11 . Thus, since the connecting parts  30  and  40  do not protrude from the lower part of the light emitting device  1 , a light emitting area (an opening area of the recessed part  13 ) of the light emitting device  1  is adequately ensured and the thickness of the entire part of the device can be reduced at the same time. 
     Since the protruding parts  34  and  44  are provided in the ends of the base parts  32  and  42  of the connecting parts, the protruding parts  34  and  44  are provided at positions sufficiently separated from the bending parts (namely, the bottom parts drawn out from the reflecting case  11 ) of the base parts  32  and  42  of the connecting parts. Since the width of the bending parts is not enlarged due to the protruding parts  34  and  44 , the force required for bending the base parts  32  and  42  of the connecting parts is not increased. Thus, the mechanical strength of the base body part  10  is prevented from being deteriorated. 
     As shown in  FIG. 6 , under a state before the lead members  3  and  4  are bent, the drawn parts  130  and  140  are T-shaped and the end  133  ( 143 ) and the end  134  ( 144 ) are formed in a linear shape. Thus, a stability is increased when the end  133  ( 143 ) is bent to form the side bending part  33  or  43  and the side bending parts  44  and  43  can be highly accurately formed. 
     The present invention is not limited to the above-described embodiment of the invention and the explanation of the embodiment. Various modified embodiments may be included in the present invention within a range that can be easily thought by a person with ordinary skill in the art without departing the description of claims.