Patent Publication Number: US-7897983-B2

Title: Light emitting diode assembly and light emitting diode display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is divisional application of application Ser. No. 12/017,310, filed on Jan. 21, 2008, now U.S. Pat. No. 7,728,337, entitled “LIGHT EMITTING DIODE ASSEMBLY AND LIGHT EMITTING DIODE DISPLAY DEVICE”, assigned to the same assignee, disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to light emitting diode assemblies and light emitting diode display devices. 
     2. Discussion of Related Art 
     Light emitting diode (LED) assemblies having various sizes and display effects have been developed and are available in the market. Depending on the complexity of the required illumination pattern, most LED display devices include a number of LED assemblies arranged in an array and selectively switchable on/off to generate such an illumination pattern. 
     Referring to  FIG. 10 , a typical LED display device is provided. The LED display device includes a number of lead-frame LED assemblies  91 , a positioning member  92 , and a printed circuit board  93 . In  FIG. 10 , only one LED assembly  91  is shown for the purpose of illustration. The LED assemblies  91  each have a positive electrode  911  and a negative electrode  912 . The positioning member  92  defines a number of positioning holes  920  penetrating therethrough. The LED assemblies  91  each is installed in a corresponding positioning hole  920  and the positive electrode  911  and the negative electrode  912  are soldered on and penetrate through the printed circuit board  93 . 
     In assembly of the LED display device, because each of the LED assemblies  91  is a unidirectional conduction device, the positive and the negative electrodes  911 ,  912  of each of the LED assemblies  91  are necessary to be distinguished beforehand, then the LED assemblies  91  are correctly electrically connected with the printed circuit board  93 . However, distinguishing between the positive and the negative electrodes  911 ,  912  is time consuming. 
     Therefore, what is needed is a LED assembly, and a LED display device with a simplified and effective assembling process. 
     SUMMARY 
     A preferred embodiment provides a light emitting diode (LED) assembly. The LED assembly includes a cover, a substrate, a LED unit, a first electrode terminal, and a second electrode terminal. The substrate includes a first surface and a second surface on an opposite side of the substrate to the first surface. The substrate and the cover cooperatively define a cavity. The LED unit is received in the cavity. The first electrode terminal and the second electrode terminal extend from the second surface of the substrate. The first electrode terminal is electrically connected to one of a positive lead and a negative lead of the light emitting diode unit. The second electrode terminal is electrically connected to the other of the positive lead and the negative lead thereof. The second electrode terminal includes a first electrode portion and a second electrode portion symmetrically arranged at opposite sides of the first electrode terminal. The first electrode portion and the second electrode portion are at least partially symmetrical with respect to the first electrode terminal. 
     Another preferred embodiment provides a LED display device. The LED display device includes a plurality of LED assemblies as described above, a positioning member, and a circuit board. The positioning member is fixed on the circuit board and the positioning member defines a plurality of positioning holes configured for receiving the LED assemblies. The circuit board includes a plurality of electrode pad units each comprising a first electrode pad and a second electrode pad electrically connected with the respective first electrode terminal and the second electrode terminal. 
     Detailed features of the present LED assembly and LED display device will become more apparent from the following detailed description and claims, and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present LED assembly and LED display device can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present LED assembly and LED display device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, wherein: 
         FIG. 1  is a schematic, front view of a LED assembly, according to a first exemplary embodiment; 
         FIG. 2  is a bottom view of the LED assembly shown in  FIG. 1 ; 
         FIG. 3  is a schematic, isometric view of a LED display device, according to an exemplary embodiment, employing the LED assembly as shown in  FIG. 1 ; 
         FIG. 4  is a schematic, front view of a LED assembly, according to a second exemplary embodiment; 
         FIG. 5  is a schematic, front view of a LED assembly with an alternative configuration of magnetic members, according to the second exemplary embodiment; 
         FIG. 6  is a schematic, bottom view of a LED assembly, according to a third exemplary embodiment; 
         FIG. 7  is a schematic, bottom view of a LED assembly, according to a fourth exemplary embodiment; 
         FIG. 8  is a schematic, bottom view of a LED assembly, according to a fifth exemplary embodiment; 
         FIG. 9  is a schematic, bottom view of a LED assembly, according to a sixth exemplary embodiment; 
         FIG. 10  is a schematic, isometric view of a conventional LED display device employing a number of LED assemblies. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings to describe the preferred embodiments of the light emitting diode (LED) assembly and the LED display device, in detail. 
     Referring now particularly to  FIGS. 1 and 2 , a LED assembly  20 , according to a first exemplary embodiment, is provided. The LED assembly  20  includes a cover  21 , a substrate  22 , a LED unit  23 , a first electrode terminal  24  and a second electrode terminal  25 . 
     The cover  21  is suitably made of light transmissive materials such as plastic, resin and glass. 
     The substrate  22  is a glass fiber board, a flexible printed circuit board or a ceramic board. The substrate  22  includes a first surface  220  and a second surface  222  on an opposite side of the substrate  22  to the first surface  220 . The first surface  220  and the cover  21  cooperatively define a cavity  210 . 
     The LED unit  23  may be a LED lamp such as a surface mount device LED lamp, a chip on board LED lamp, and a lead frame LED lamp. In the illustrated embodiment, the LED unit  23  is a lead frame LED lamp received in the cavity  210 . The LED unit  23  includes an encapsulation body  230 , a first lead  232  and a second lead  234 . Alternatively, the LED unit  23  also may be a LED chip electrically connected with the first electrode terminal  24  and the second electrode terminal  25  by wire bonding. 
     Referring to  FIG. 2 , the first electrode terminal  24  and the second electrode terminal  25  extend from the second surface  222  of the substrate  22 . The first electrode terminal  24  is electrically connected to one of a positive lead and a negative lead of the LED unit  23 , and the second electrode terminal  25  is electrically connected to the other of the positive lead and the negative lead thereof. The second electrode terminal  25  includes a first electrode portion  250  and a second electrode portion  252  arranged at both sides of the first electrode terminal  24 . The first electrode portion  250  and the second electrode portion  252  have an identical bar-shape. The first electrode portion  250  and the second electrode portion  252  are suitably symmetrical with respect to the first electrode terminal  24 . 
     Referring to  FIG. 3 , a LED display device  30  employing a number of LED assemblies  20  is provided. It is noted that only one LED assembly  20  is shown for the purpose for illustration. The LED display device  30  further includes a positioning member  31  and a circuit board  32 . 
     The positioning member  31  defines a number of positioning holes  310  arranged in an array and the positioning holes  310  are configured (i.e., structured and arranged) for receiving the LED assembly  20 . The positioning member  31  is fixed on the circuit board  32 . The positioning member  31  is made from a material selected from a group consisting of plastics and alloys. 
     The circuit board  32  includes a plurality of electrode pad units that each comprise a first electrode pad  320  and a second electrode pad  322 . The first electrode pad  320  and the second electrode pad  322  are electrically connected to an interior circuitry of the circuit board  32 . The first electrode pads  320  and the second electrode pads  322  are respectively electrically connected to a corresponding one of the first electrode terminal  24  and the second electrode terminal  25 . As such, when the LED assembly  22  is received in the positioning hole  310 , the circuit board  32  supplies electrical power to the first and second electrode terminals  24 ,  25  by the first and second electrode pads  320  and  322 . 
     Because the first electrode portion  250  and the second electrode portion  252  of the second electrode terminal  25  are symmetrical with respect to the first electrode terminal  24 , even when the LED assembly  20  is rotated round OO′ by 180 degrees and assembled into the through hole  310 , the first and second electrode terminals  24  and  25  can still draw power normally from the first and second electrode pads  320  and  322  with proper polarity. 
     Referring to  FIG. 4 , a LED assembly  40 , according to a second exemplary embodiment, is provided. The configuration of the LED assembly  40  is generally similar to the above-mentioned LED assembly  20 . However, the LED assembly  40  further includes magnetic members  46  arranged on the first surface  420  of the substrate  42  and received in the cavity  410 . The magnetic members  46  are made of a material selected from a group consisting of iron, aluminum-nickel-cobalt (Al—Ni—Co), neodymium-iron-boron (Nd—Fe—B) and samarium-cobalt (Sm—Co). When the LED assembly  40  is employed in the LED display device  30 , the first electrode pads  320  and the second electrode pads  322  of the LED display device  30  can be magnetic electrodes. When the LED assembly  40  is assembled into the positioning hole  310  of the positioning member  31 , the LED assembly  40  would be fixed in the positioning hole  310  by a magnetic force between the magnetic members  46  and the first and second electrode pads  320  and  322 , thus making assembly of the LED display device  30  simple and convenient. 
     Referring to  FIG. 5 , alternatively, the magnetic members  46  also can be disposed on the second surface  422  of the substrate  42  and at the outside of the cavity  410 . At least one of the first electrode terminal  44  and the second electrode terminal  45  is electrically insulated from the magnetic members  46 . 
     It is noted that, the first electrode portion  250  and the second electrode portion  252  of the second electrode terminal  25  is not limited to being bar-shaped. The first electrode portion  250  and the second electrode portion  252  of the second electrode terminal  25  also may have other shapes, as long as the polarity of the LED assembly is still correct after being rotated round its central axis (shown as OO′ in  FIG. 3 ) by a certain angle and assembled into the positioning hole  310 . 
     Referring to  FIG. 6 , a LED assembly  50  according to a third exemplary embodiment of the present invention is provided. The configuration of the LED assembly  50  is generally similar to the above-mentioned LED assembly  10 . However, the first electrode portion  550  and the second electrode portion  552  of the second electrode terminal each have a semi-circular ring shape held in contact with each other. 
     Referring to  FIG. 7 , a LED assembly  60  according to a fourth exemplary embodiment of the present invention is provided. The configuration of the LED assembly  60  is generally similar to the above-mentioned LED assembly  10 . However, the first electrode portion  650  and the second electrode portion  652  of the second electrode terminal each has a broken semi-circular ring shape which does not contact the other. 
     Referring to  FIG. 8 , a LED assembly  70  according to a fifth exemplary embodiment of the present invention is provided. The configuration of the LED assembly  70  is generally similar to the above-mentioned LED  10 . However, the first electrode portion  750  and the second electrode portion  752  of the second electrode terminal each have semi-elliptical ring shapes, and contact with each other. 
     When the first electrode portion and the second electrode portion of the second electrode terminal have bar, semi-circular ring, broken semi-circular ring or semi-elliptic ring shape, the second power supply electrode  322  of the light emitting diode display device  30  suitably has a shape matching with the first electrode portion and the second electrode portion of the second electrode terminal. The first electrode terminal may be round, ellipsoid, rectangular, triangular etc. Accordingly, the first power supply electrode  320  has a shape matching with the first electrode terminal. 
     Referring to  FIG. 9 , a LED assembly  80  according to a sixth exemplary embodiment of the present invention is provided. The difference between the LED assembly  80  and the above-mentioned LED assembly  10  is that, the first electrode portion  850  of the second electrode terminal  85  is bar-shaped, and the first electrode portion  850  includes two parts  850   a  and  850   b . The second electrode portion  852  has identical size and shape to the part  850   b . The second electrode portion  852  and the part  850   b  are symmetrical with respect to the first electrode terminal  84 . When employed in the light emitting diode display device  30 , even the light emitting diode assembly  80  is rotated round its central axis by a certain angle and assembled into the through hole  310 , the first and second electrode terminals  84  and  85  can also normally draw power from the first and second electrode pads  320  and  322  with proper polarity. 
     The above-mentioned LED assemblies  20 ,  40 ,  50 ,  60 ,  70 ,  80  each includes a first electrode terminal and a second electrode terminal. The second electrode terminal includes a first electrode portion and a second electrode portion. The first electrode portion and the second electrode portion are at least partially symmetrical with respect to the first electrode terminal. When being assembled in to the light emitting diode display device, the light emitting diode assembly always receives satisfactory polarity power without requiring identification. 
     Finally, it is to be understood that the above-described embodiments are intended to illustrate rather than limit the invention. Variations may be made to the embodiments without departing from the spirit of the invention as claimed. The above-described embodiments illustrate the scope of the invention but do not restrict the scope of the invention.