Patent Publication Number: US-2013229796-A1

Title: Light emitting diode bar and light emitting diode module using the same

Description:
This application claims the benefit of Taiwan application Serial No. 101107237, filed Mar. 3, 2012, the subject matter of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates in general to a light bar and a module using the same, and more particularly to a light emitting diode (LED) bar and an LED bar module using the same. 
     2. Description of the Related Art 
     The light-emitting diode (LED) emits a light by converting electric energy into photo energy. The LED is mainly composed of semiconductors. Of the semiconductors, those having a larger ratio of holes carrying positive electricity are referred as P type semiconductors, and those having a larger ratio of electrons carrying negative electricity are referred as N type semiconductors. The joint connecting a P type semiconductor and an N type semiconductor forms a PN joint. When a voltage is applied to the positive polarity and negative polarity of an LED chip, the electrons and the holes will be combined and emitted in the form of a light. 
     Having the features of long lifespan, low temperature and high energy utilization rate, the LED has been widely used in the fields such as screen backlight source, desk lamp, night light, large sign board, traffic light, third brake light, mobile phone boot-up indicator, and has gradually replaced conventional light sources. 
     The LEDs can be disposed on a long shaped substrate to form a LED bar. When the LED bars are serially connected, the length of the light source can further be increased. However, the design of serial connection needs to consider structural reliability, electrical and optical performance of the product. To improve product quality, the research personnel are engaged in associated researches. 
     SUMMARY OF THE INVENTION 
     The invention is directed to a light emitting diode (LED) bar and an LED module using the same. The dark stripes of the connected LED bars are improved by rotating the LEDs at the connecting areas. 
     According to an embodiment of the present invention, a light emitting diode bar is provided. The LED bar includes a long shaped substrate, a plurality of first LEDs and a second LED. Two long parallel edges of the long shaped substrate are extended along a first direction. The long shaped substrate includes a non-connecting area and a connecting area located at an end of the long shaped substrate. The first LEDs are interlaced and disposed in the non-connecting area and between the two long sides. Each first LED has a first long axis disposed along the first direction. The second LED has a second long axis disposed in the connecting area and along a second direction. The first direction and the second direction are intersected at a predetermined angle. 
     According to another embodiment of the present invention, an LED module is provided. The LED module includes two LED bars. Each LED bar includes a long shaped substrate, a plurality of first LEDs and a second LED. Two long parallel edges of the long shaped substrate are extended along a first direction. The long shaped substrate includes a non-connecting area and a connecting area located at an end of the long shaped substrate. The first LEDs are interlaced and disposed in the non-connecting area of the long shaped substrate and between the two long sides. Each first LED has a first long axis disposed along the first direction. The second LED has a second long axis disposed in the connecting area and along a second direction. The first direction and the second direction are intersected at a predetermined angle. The predetermined angle is between 30 to 70 degrees. The distance between the second LED and the edge of the end of the long shaped substrate is substantially two times that between any two neighboring first LEDs along the first direction. The LED bar further includes a solder bump disposed in the connecting area. Two neighboring LED bars are connected by soldering the solder bumps located in the connecting areas at two neighboring ends of the two neighboring LED bars with a wire. 
     According to an alternate embodiment of the present invention, an LED module. The LED module includes two LED bars. Each LED bar includes a long shaped substrate, a plurality of first LEDs and a second LED. Two long parallel edges of the long shaped substrate are extended along a first direction. The long shaped substrate includes a non-connecting area and a connecting area located at an end of the long shaped substrate. The first LEDs are interlaced and disposed in the non-connecting area of the long shaped substrate and between the two long sides. Each first LED has a first long axis disposed along the first direction. The second LED has a second long axis disposed in the connecting area and along a second direction. The first direction and the second direction are intersected at a predetermined angle. The predetermined angle is between 30 to 70 degrees. The distance between the second LED and the edge of an end of the long shaped substrate is substantially two times that between any two neighboring first LEDs along the first direction. Each LED bar further includes a connector disposed in the connecting area. Two neighboring LED bars are connected by two connectors located at two neighboring ends of the two neighboring LED bars. 
     The above and other aspects of the invention will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment(s). The following description is made with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic diagram of an LED module of a first embodiment; and 
         FIG. 2  shows a schematic diagram of an LED module of a second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A number of embodiments are disclosed below for elaborating the invention. The dark stripes occurring to the connected LED bars are improved by rotating the LEDs at the connecting areas. The embodiments disclosed below are for exemplification purpose only, not for limiting the scope of protection of the invention. Furthermore, secondary or unimportant elements are omitted in the accompanying diagrams of the embodiments for highlighting the technical features of the invention. 
     First Embodiment 
     Referring to  FIG. 1 , a schematic diagram of an LED module  1000  of a first embodiment is shown. The LED module  1000  includes at least two LED bars  100 . A plurality of LED bars  100  can be serially connected to form a long shaped light emitter. The number of LED bars  100  connected in serial can be determined according to the needs of the products. 
     The LED bar  100  includes a long shaped substrate  130 , a plurality of first LEDs  110  and at least a second LED  120 . The long shaped substrate  130  is used for supporting various electronic elements such as a single-sided circuit board, a double-sided circuit board, a silicon substrate or an aluminum substrate. The first LED  110  and the second LED  120  are used for emitting a light and are formed by such as AlGaAs, AlGaP, AlGaInP, GaAsP, GaP, GaN, InGaN or AlGaN. If the first LED  110  and the second LED  120  are formed by different materials, then they will emit different lights. The wavelengths of the lights emitted by the first LED  110  and the second LED  120  can be the same or different. 
     The long shaped substrate  130  includes a non-connecting area A 1  and two connecting areas A 2 . In one embodiment, the long shaped substrate  130  can have only one connecting area A 2  located at an end E of the long shaped substrate  130 . The non-connecting area A 1  is located in the middle of the long shaped substrate  130  and occupies a large part of the long shaped substrate  130 . The connecting area A 2  is used for connecting two neighboring long shaped substrates  130 . 
     In the present embodiment, the LED bar  100  further includes a solder bump  140  disposed in the connecting area A 2 . Two neighboring LED bars  100  can be connected by soldering two neighboring solder bumps  140  with a wire  150 . 
     In terms of the position of the first LED  110 , two long sides L 130  of the long shaped substrate  130  are extended along a first direction C 1 . The first LEDs  110  are interlaced and disposed in the non-connecting area A 1  of the long shaped substrate  130  and between two long sides L 130 . Each first LED  110  has a first long axis L 110  disposed along the first direction C 1 . 
     In the present embodiment, the first LEDs  110  are arranged in two rows, and are interlaced between the first row and the second row to shorten the intervals between the first LEDs  110  along the first direction C 1 . 
     In terms of the position of the second LED  120 , the second LED  120  having a second long axis L 120  is disposed in the connecting area A 2  along a second direction C 2 . The first direction C 1  and the second direction C 2  are intersected at a predetermined angle θ. The second long axis L 120  of the second LED  120  is not disposed along the first direction C 1  but is inclined to the first direction C 1 , such that the second LEDs  120  of two neighboring LED bars  100  are closer to each other to avoid dark stripes occurring to two neighboring LED bars  100 . 
     When the second LED  120  is rotated, the interference between the second LED  120  and the first LED  110 , the restriction in the width W 130  of the long shaped substrate  130 , and the position of the solder bump  140  all need be taken into consideration. After several experiments, the research personnel found that when the predetermined angle θ is between 30 to 70, the above restrictions are satisfied and the dark stripes are improved. Considering the fact that the second LED  120  may have different emitting angles in different directions, the light emitted by the second LED  120  can be better used when the predetermined angle θ is equal to 30, 45, or 70 degrees. 
     As indicated in  FIG. 1 , after the second LED  120  is rotated, the distance W 120   e  between the second LED  120  and the edge of the end E of the long shaped substrate  13  is substantially two times the distance W 110  between any two neighboring first LEDs  110  along the first direction C 1 . Thus, the distance W 120  between the neighboring second LEDs  120  can be shortened to improve the phenomena of dark stripes. 
     Second Embodiment 
     Referring to  FIG. 2 , an LED module  2000  of a second embodiment is shown. The LED module  2000  of the present embodiment is different from the LED module  1000  of the first embodiment in the connection method of the neighboring LED bar  200 , and other similarities are not repeated. 
     As indicated in  FIG. 2 , the LED bar  200  further includes a connector  250  disposed in the connecting area A 2 . The connector  250  is such as a wire to wire connector, a wire to board connector, a board to board connector or a flexible printed circuit (FPC) connector. 
     Despite the LED bars  200  are connected via the connector  250 , after the second LED  120  is rotated, the distance W 120   e  between the second LED  120  and the edge of the end E of the long shaped substrate  130  is substantially two times the distance W 110  between any two neighboring first LEDs  110  along the first direction C 1 . Thus, the distance W 120  between neighboring seconds LED  120  can be shortened to improve the phenomena of dark stripes. 
     While the invention has been described by way of example and in terms of the preferred embodiment(s), it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.