Abstract:
An LED lamp has: an LED with a pair of terminals; a holder to which the LED is attached, the holder being of insulating material; and a radiation unit that has two metallic radiation plates that are attached to the holder while surrounding the holder and being insulated from each other. Each of the radiation plates has a contact portion that contacts the pair of terminals of the LED being attached to the holder and a power receiving terminals for power supplied to the LED.

Description:
[0001]    The present application is based on Japanese patent application No. 2002-349285, the entire contents of which are incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to an LED lamp that needs a means for radiating heat to be generated in operation.  
           [0004]    2. Description of the Related Art  
           [0005]    For example, automobiles are equipped with various lamps such as head lamp, tail lamp, winker lamp and stop lamp. These lamps use a lamp of several watts to tens of watts according to use, and an electric light bulb (hereinafter referred to as bulb) is conventionally used for them. The conventional various lamps are attached in a socket to facilitate the attaching and releasing, and its light section where the lamp is attached has a reflector to converge light in a desired direction.  
           [0006]    Since automobile bulbs are change parts, they have a structure to be fitted to a socket. Further, in order to shorten the time required in attaching step of manufacturing, they are not screw type but insert type. For example, bulb base section has a convex insert portion to the socket and two electrodes are disposed along both sides of insert portion. The socket attached to the reflector is provided with built-in contact electrodes to contact the electrodes and bulb support opening to which the insert portion is fitted. Thus, the attaching or releasing of bulb can be performed simply by inserting or pulling (for example, Japanese patent application laid-open No. 2001-110210, pages 2-3 and FIG. 2).  
           [0007]    Some vehicles use an LED stop lamp that has a plurality of red LED lamps with high output, instead of light bulb. The LED lamp has small and lightweight light emitting elements and therefore the socket is unnecessary and the front panel of transparent red is further unnecessary. Thus, the entire lamp can be minimized and simplified in structure. Also, it has long lifetime Accordingly, it is an optimum lamp for automobiles.  
           [0008]    In recent years, a blue LED with high output is developed other than conventional red LED. Also, a white LED is developed based on the blue LED and some applications thereof begin instead of the conventional bulb. The white LED has a lower power consumption and longer lifetime than bulb. If the price lowers in the future, the white LED will be rapidly popularized.  
           [0009]    Commercially available lighting apparatuses (flashlight, key holder etc.) using LED are generally structured such that LED leads are directly soldered to pattern or terminal of printed circuit board and therefore its LED lamp cannot be changed. Furthermore, the soldering is difficult to incorporate in the manufacturing line of automobile lamp and the manufacturing process is complicated thereby. So, it is desired that the LED lamp has such a structure that can be inserted to socket without soldering, like bulb. If so, the LED lamp can be handled as change parts, like bulb.  
           [0010]    However, the conventional LED lamp of high output type (high brightness type) with consumption power of several watts to ten or more watts generates substantial amount of heat due to increased current. Especially in tail lamp and winker lamp of automobile, the LED, socket and its peripherals may be overheated because such a lamp is subject to radiation of external light and is frequently placed in a space with bad ventilation and, as a result, heat cannot be sufficiently radiated. Therefore, the temperature of light emitting element will rise and the brightness will lower.  
         SUMMARY OF THE INVENTION  
         [0011]    It is an object of the invention to provide an LED lamp that can offer a high radiation property even when using a high output light emitting element.  
           [0012]    It is another object of the invention to provide an LED lamp that can be easily assembled.  
           [0013]    According to the invention, an LED lamp comprises;  
           [0014]    an LED with a pair of terminals;  
           [0015]    a holder to which the LED is attached, the holder being of insulating material; and  
           [0016]    a radiation unit that comprises two metallic radiation plates that are attached to the holder while surrounding the holder and being insulated from each other, each of the radiation plates including a contact portion that contacts the pair of terminals of the LED being attached to the holder and a power receiving terminals for power supplied to the LED.  
           [0017]    In the above structure, where the radiation unit is composed of two radiation plates attached on both sides of the holder, the contact portion contacts the terminal of LED attached to the holder and heat generated from LED in operation is conducted to each radiation plate, thereby the radiation is performed. Thus, the overheating of LED can be prevented. Furthermore, the manufacturing process can be simplified because the LED lamp of the invention has such a structure that can facilitate the assembling.  
           [0018]    It is preferable that each of the radiation plates is formed approximately C-shaped and has a fitted portion on its one end and the contact portion on its other end, and the holder has a pair of grooves on its both sides, one of the pair of grooves receiving the fitted portion and the other receiving the contact portion. Thereby, the radiation plate can be easily fixed to the holder.  
           [0019]    It is preferable that the contact portion is processed to have a springy force. Thereby, the electrical connection with the pair of terminals of LED can be secured and therefore the loose connection due to disturbance such as vibration or thermal expansion can be prevented.  
           [0020]    It is preferable that each of the radiation plates has an aperture in the side surface, and the holder has a protrusion to be engaged to the aperture in attaching the radiation plate to the holder. Thereby, the fixation of radiation plates to the holder can be secured.  
           [0021]    It is preferable that the holder has an attachment section for attaching the holder to other member on its one end at which the LED is attached. Thereby, the positioning and attaching to the other member can be conducted simultaneously. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    The preferred embodiments according to the invention will be explained below referring to the drawings, wherein:  
         [0023]    [0023]FIG. 1 is a perspective view showing a broken LED lamp in a first preferred embodiment according to the invention;  
         [0024]    [0024]FIG. 2 is a perspective view showing an assembled LED in FIG.1;  
         [0025]    [0025]FIG. 3 is a cross sectional view cut along the line C-C in FIG. 2;  
         [0026]    [0026]FIG. 4 is a perspective view showing a reflector  50  to which an LED lamp  1  of the first embodiment is attached;  
         [0027]    [0027]FIG. 5 is a perspective view showing a schematic composition of vehicle combination lamp in a second preferred embodiment according to the invention;  
         [0028]    [0028]FIG. 6 is a vertical sectional view cut along the line D-D in FIG. 5; and  
         [0029]    [0029]FIG. 7 is a vertical sectional view showing a lateral emission type LED in a third preferred embodiment according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]    [0030]FIG. 1 is a perspective view showing a broken LED lamp in the first preferred embodiment according to the invention. FIG. 2 is a perspective view showing the assembled LED in FIG. 1  
         [0031]    LED lamp  1  is composed of LED  10  including a light emitting element (not shown), a holder  20  of insulating resin in which the LED  10  is housed, and a radiation unit  30  that is attached on both sides of the holder  20 . The radiation unit  30  is composed of a pair of radiation plates  31   a ,  31   b  that are, as shown in FIG. 2, attached on the right and left sides of the holder  20 .  
         [0032]    LED  10  is composed of a tubular main body  11  and terminals  12   a,    12   b  extending behind the main body  11 . The main body  11  has a transparent front face from which light is emitted when supplying power between the terminals  12   a,    12   b.  The terminals  12   a,    12   b  of LED  10  are inserted to the holder  20 , as shown by arrow  8  in FIG. 1.  
         [0033]    The holder  20  is made by molding the insulating resin, and it is desirable that the insulating resin has heat resistance. The holder  20  is composed of: terminal holes  21  into which the terminals  12   a,    12   b  are inserted in the direction of arrow A in FIG. 1; a cylindrical attachment section  22  that is fitted and engaged to the center of a reflector  50  described later; engaging portions  23   a,    23   b  that are disposed opposite to each other on the attachment section  22  and engaged to the reflector  50  to fix the holder  20 ; upper and lower grooves  24  that are formed on both sides of the holder  20  to receive the radiation plates  31   a ,  31   b;  and protrusions  25  that prevent the disengaging of radiation plates  31   a ,  31   b.    
         [0034]    The radiation plates  31   a ,  31   b  of radiation unit  30  are inserted to the holder  20  in the direction of arrow A in FIG. 1. The radiation plates  31   a ,  31   b  each are shaped such that its upper and lower portions are folded to offer an around C-shaped section in the front portion to middle portion and a plate-shaped section in the back portion. The radiation plates  31   a ,  31   b  are preferably of metal with good radiation and conductivity properties such as copper and copper alloy, and it is desirable that they have Au or Ag plating on the surface to avoid corrosion. The radiation plates  31   a ,  31   b  have apertures  32   a ,  32   b,  to which the protrusions  25  of holder  20  are engaged, on its both sides in th middle portion. Furthermore, the radiation plates  31   a ,  31   b  have contact portions  33   a ,  33   b,  which are formed parallel to the side and contact the terminals  12   a ,  12   b  being inserted to the holder  20 , on one end in the middle portion.  
         [0035]    The contact portions  33   a ,  33   b  are slightly bent upward and downward, respectively, such that they bring a certain springy force to the terminals  12   a ,  12   b  to secure the contact with the terminals  12   a ,  12   b  The contact portions  33   a ,  33   b  have a length about equal to the terminals  12   a,    12   b  such that a sufficient contact area can be obtained. The radiation plates  31   a ,  31   b  have a pair of fitted portions  34 ,  35 , which slide while being fitted in the grooves  24 , on the other end in the middle portion. The radiation plates  31   a ,  31   b  has terminals  36   a ,  36   b  in the back portion.  
         [0036]    With the above structure, the radiation plates  31   a ,  31   b  can be easily attached to the holder  20 . Moreover, it is not necessary to fix the radiation plates  31   a ,  31   b  with screws since they do not disengage from the holder  20  when the protrusions  25  are engaged to the apertures  32   a ,  32   b.  Thus, the assembling becomes easy and the productivity can be thereby improved.  
         [0037]    [0037]FIG. 3 is a cross sectional view cut along the line C-C in FIG. 2.  
         [0038]    When the radiation unit  30  is attached to the holder  20  and LED  10  is inserted thereto, the terminal  12   a  of LED  10  contact the contact portion  33   a  of radiation plate  31   a  while having a springy force and the terminal  12   b  of LED  10  contact the contact portion  33   b  of radiation plate  31   b  while having a springy force. Then, when a predetermined DC voltage is applied between the terminals  36   a  and  36   b,  the voltage is applied through the terminals  36   a ,  36   b  and the contact portions  33   a ,  33   b  to the terminals  12   a ,  12   b.  Thereby, LED  10  emits light,  
         [0039]    When the LED  10  radiates heat during the operation, heat is conducted to the terminals  12   a ,  12   b.  Then, heat is conducted to the contact portions  33   a ,  33   b  being contacted with the terminals  12   a ,  12   b,  then conducted the other portion of radiation plates  31   a ,  31   b.  At that time, the entire radiation plates  31   a ,  31   b  serve as a radiation member to radiate heat. Since the radiation plates  31   a ,  31   b  are provided on the outer surface of holder  20 . the radiation can be performed efficiently.  
         [0040]    [0040]FIG. 4 is a perspective view showing the reflector  50  to which the LED lamp  1  of the first embodiment is attached. The reflector  50  is composed of an attachment hole  51  that is located at the center of light reflection surface  50 A, and cutting regions  52   a ,  52   b  that are engaged with the engaging portions  23   a ,  23   b  of LSD lamp  1 . The light reflection surface  50 A is formed concave while having a plurality of reflection regions in order to converge light emitted from LED  10  to lamp the forward.  
         [0041]    In assembling the LED lamp  1 , at first, the radiation plates  31   a ,  31   b  are inserted, in the direction of arrow A in FIG. 1, from the back end of the holder  20  to the grooves  24  on both sides of the holder  20 . When they are pushed until the protrusion  25  is engaged to the apertures  32   a ,  32   b,  the radiation plates  31   a ,  31   b  are fixed to the holder  20 . Then, the terminals  12   a ,  12   b  are inserted to the terminal holes  21  in the direction of arrow B in FIG. 1 while matching the polarity of the terminals  12   a ,  12   b  to that of terminal holes  21  of holder  20  until the back face of LED  10  abut on the inner face of attachment section  22 . Thus, the LED lamp  1  shown in FIG. 2 is assembled.  
         [0042]    Then, to the terminals  36   a ,  36   b  of the assembled LED lamp  1  in FIG. 2, P type crimping terminals  41   a ,  41   b  are inserted in the direction of arrow D in FIG. 4. Thereby, the terminals  36   a ,  36   b  are connected with the F type crimping terminals  41   a ,  41   b , respectively. The F type crimping terminals  41   a ,  41   b  have wires  42   a ,  42   b  which are connected with a wire harness (not shown) and ends of which are crimped. Then, from the back of reflector  50 , the top of LED  10  is inserted to the attachment hole  51  in the direction of arrow B while matching the engaging portions  23   a ,  23   b  of holder  20  to the cutting regions  52   a ,  52   b  of reflector  50 . After inserting the attachment section  32  of holder  20  to the attachment hole  51 , the holder  20  is rotated in a predetermined direction and, thereby, the engaging portions  23   a ,  23   b  are engaged to the reflector  50 . Thus, the disengaging of LED lamp  1  can be prevented.  
         [0043]    In the first embodiment described above, with the radiation unit  30  attached on the holder  20  to hold LED  10 , heat generated during the operation of LED  10  can be radiated such that the LED lamp  1  operates stably without reducing the emission efficiency of LED due to such heating. The radiation plates  31   a ,  31   b  are integrally attached to the holder  20  while also serving as the electrical connection portions to the F type crimping terminals  41   a ,  41   b.  Therefore, the LED lamp  1  can offer a sufficient radiation area without increasing the size of holder  20 .  
         [0044]    Furthermore, the LED lamp  1  is fixed to the reflector  50  by means of the engagement between the engaging portions  23   a ,  23   b  of holder  20  and the cutting regions  52   a ,  52   b  of reflector  50 . Thus, the LSD lamp  1  can be easily and securely fixed thereto simply by inserting the LED lamp  1  to the attachment hole  51  and then rotating it. Simultaneously, the LED  10  can be accurately positioned to the light reflection surface  50 A.  
         [0045]    Although in the first embodiment the terminals  12   a ,  12   b  are disposed to contact the contact portions  33   a ,  33   b  orthogonally to each other as shown in FIGS. 1 and 3, the contact portions  33   a ,  33   b  may be bent 90 degrees such that the terminals  12   a ,  12   b  contact the contact portions  33   a ,  33   b  while being stacked in parallel. In this case, since the contact area further increases the radiation property can be enhanced.  
         [0046]    Alternatively, the other radiation member may be additionally attached to or laid in contact with the radiation plates  31   a ,  31   b.  Also in this case, since the contact area further increases, the radiation property can be enhanced.  
         [0047]    Further, in FIGS.  1  to  4 , the fitted portions  34 ,  35  and the contact portions  33   a ,  33   b  may be disposed reversely. Also, though the radiation plates  31   a ,  31   b  are attached to the right and left sides of holder  20 , they may be attached to the top and bottom sides of holder  20 .  
         [0048]    [0048]FIG. 5 is a perspective view showing the schematic composition of vehicle combination lamp in the second preferred embodiment according to the invention.  
         [0049]    The combination lamp  60  has an opening that extends from the front face in the direction of arrow Z to the side face in the direction of arrow X. In cover  61  with an inside space, two divider plates  62  to horizontally divide the space into three stages with equal intervals are disposed. On each stage, three seats  63  are arranged laterally. Each seat  63  has LED lamp  1  attached on the front face. Aluminum deposition is made to ceiling face  61   a , bottom face  61   ba  and side wall  61   c  inside the cover  61 , to top face  62   a  and bottom face  62   b  of the divider plate  62 , and to top  63   a  and side  63   b  of the seat  63 . In other words, aluminum deposition is made to entire interior of cover  61 .  
         [0050]    [0050]FIG. 6 is a vertical sectional view cut along the line D-D in FIG. 5. As shown in FIG. 6, the combination lamp  60  is structured combining the LED lamps  1  and reflectors  50 . The LED lamp  1  is attached to the reflector  50  by engaging the engaging portions  23   a ,  23   b  of holder  20  to the cutting regions  52   a ,  52   b.    
         [0051]    In the second embodiment, as earlier described in the first embodiment, the LED lamp  1  is attached to the reflector  50  by engaging the engaging portions  23   a ,  23   b  of holder  20  to the cutting regions  52   a ,  52   b.  Therefore, in assembling, the LED lamp  1  can be easily and accurately positioned to the reflector  50 . In the combination lamp  60  with a plurality of LED lamps  1  thus attached, each LED lamp  1  can be easily changed when it does not turn on normally Thus, the entire combination lamp  60  is not needed to be wastefully changed in such a case.  
         [0052]    [0052]FIG. 7 is a vertical sectional view showing a lateral emission type LED in the third preferred embodiment according to the invention.  
         [0053]    LED  10 A is composed of: a pair of lead frames  12   a ,  12   b  that are disposed via a space for insulation on the X-Y plane; a light emitting element  13  that is mounted at X-Y coordinate origin on the lead frame  12   a  which is formed L-shaped by bending a metal strip plate; a bonding wire  14  to electrically connect the upper electrode of light emitting element  13  with the end of lead frame  12   a;  and transparent epoxy resin  15 , which has flat and cylindrical form, to seal the lead frames  12   a ,  12   b , light emitting element  13  and bonding wire  14 .  
         [0054]    The transparent epoxy resin  15  has flat portion  15 A located just over the light emitting element  13 , reflection surface  15 B formed in arc shape connecting with the flat portion  15 A, and side reflection surface  15 C.  
         [0055]    The reflection surface  15 B is in the form of umbrella by rotating part of a parabola, which has a focal point corresponding to the center of emission surface of the light emitting element  13  and a symmetrical axis in the X-axis direction, around Z-axis in the range of more than 60 degrees from the coordinate origin to the Z-axis.  
         [0056]    With LED  10 A thus structured, emission light can be efficiently taken out in the direction of perpendicular to the center axis of light emitting element. Thereby, when LED  10 A attached to the holder  20  is fixed to the reflector  50 , light emitted to the side direction can be reflected on the reflector  50 , then radiated uniformly in a wide range. As a result, the visibility of LED lamp  1  can be enhanced.  
         [0057]    Although, in the above explanation, the led lamp of the invention is applied to vehicle lamp, it is not limited to that use and can be applied to all led lamps that may generate some heat.  
         [0058]    Although the invention has been described with respect to the specific embodiments for complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.