Abstract:
An LED device in which LED groups are located on a pixel board has calibration data for each LED stored both electrically and mechanically close to the actual LED. Preferably, each LED group has a number of LEDs of different colors on the pixel board, being electrically connected to a color controller. The color controller is connected to a power supply, and the pixel board has a memory circuit having the LED calibration data related to the LEDs stored therein. The color controller controls LEDs for generating light based on the LED calibration data stored in the memory circuit on said pixel board. Preferably, at least one of the LEDs is formed on a chip that contains the memory circuit for storing the calibration data.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a division of commonly owned, co-pending U.S. patent application Ser. No. 12/676,667, and filed Jul. 8, 2010. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to LED bar modules comprising a number of LED groups, which LED groups comprise a number of LEDs, which LEDs have different colours, which LEDs are electrically connected to a colour controller for generating light of changing colour, which colour controller is connected to a power supply, which is formed as a main printed circuit ( 8 ), where the LED groups are placed at a pixel board, which pixel board conducts heat from the LEDs. 
     2. Description of Related Art 
     The present invention further concerns a method for calibration of LEDs, where the LEDs are connected to control means, which control means control at least one electric parameter used in relation to the operation of the LEDs, where each LED is connected to its own control circuit. 
     US 2006/0002110 disclose a linear LED housing comprising a top part attached to a bottom part by fasteners. The power and data are fed through the interior of the lighting unit and the top of the housing includes a slot into which light sources are disposed. The housing can be fit with a lens for protecting the light sources or shaping light coming from the light sources. In embodiments the housing may house drive circuitry for a high-voltage and lines for power and data run through the housing. A metal plate conducting heat away from the drive circuit board and the light sources are provided transversal inside the housing. The housing comprises cooling fins on the outside of the housing for additional cooling for the housing. The circuit for high voltage power lines runs through the interior of the housing and there is thus a great risk that current might jump from the high voltage and power lines to the housing causing dangerous ground faults. This risk is increased when the LED housing is used in moist and humid environments (e.g. on a cruse ship where the LED housing might get in contact with saltwater), as moist might enter the housing, as it is difficult to seal the upper and bottom part of the housing, causing corrosion to appear at the electrical circuits and thus increasing the risk of current jumps and ground faults. Further the disclosed housing is very complicated to manufacture, as the outer part comprises of an upper part and bottom part which are fasten together by screws. 
     It is the object of the invention to achieve a highly efficient LED bar for generating a bar of light. A further object is to form modules of a LED bar which are easy to connect and which by connection automatically connect both power and data. A third object of the invention is to achieve efficient cooling of the LEDs. Yet another object is to achieve an efficient electrical isolation between electronic printed circuits and the bar housing. A further object of the invention is to store calibration data for each LED both electrically and mechanically close to the actual LED. And yet, another object of the invention is to achieve wide orientation scope of LED bar. Another further object is to form modules of LED which is easy to change the diffuser which can fulfil different beam angle out. 
     SUMMARY OF THE INVENTION 
     The object of the invention can be fulfilled with a LED bar module having a number of LED groups, each LED group comprising a number of LEDs on a pixel board, the LEDs having different colors and being electrically connected to a color controller, if the main printed circuit is placed inside a heat conductive tube, where the pixel board is placed outside the heat conductive tube in a longitudinal recess, where a connector is electrically connecting the pixel board to the main printed circuit, where the main printed circuit is placed inside an isolation cover, which isolation cover is placed between the main printed circuit and the heat conductive tube, which isolation cover has a longitudinal opening for achieving heat conduction between the main printed circuit and a central part of the upper wall of the heat conductive tube. 
     Hereby, it is achieved that the LEDs are placed on the outside of the tube in a way where heat generated from the LEDs is conducted downwards to the tube. Inside the tube, the rest of the power electronics and also the light controlling electronics are placed. Placing e.g. switch mode, supply circuits and also control circuits inside a tube gives a highly efficient electromagnetic shield for shielding against electromagnetic radiation to the outside. Placing the electronic printed circuits inside an isolation cover reduces the risk of electrical short cut towards the tube. In all situations where printed circuit boards are to be placed inside a metallic tube, the same problem of how to achieve a highly efficient isolation of the printed circuit board occurs. Problems also occur because the physical size of components can change during production life of a product so components which are bigger in production are replacing the components designed during the developing process of the product. Placing the printed circuit boards inside the isolation cover solves all these problems in a highly efficient way. 
     The colour controller can be placed on a daughter printed circuit, which daughter printed circuit can be electrically and mechanically connected to the main printed circuit by connectors. Placing the colour controller on a daughter printed circuit can lead to the result that this colour controller could be a module which is used in a number of different products using exactly the same circuit. Placing the colour controller on the daughter printed circuit also leads to a situation where all the intelligence in the light controller can easily be exchanged. In this way, the rest of the printed circuit board can be manufactured as a highly efficient switch mode power supply with sufficient room for a high current connection between at least some of the components. 
     The pixel board can comprise a memory circuit, in which memory circuit LED calibration data for the LEDs at the board is stored. It is well-known when using LEDs for generating different colours that these LEDs need to be calibrated. The best result is achieved if an intelligent circuit is used where, at first, factory data for the LEDs are known and calibration data are calculated in relation to the number of hours the LED has been in operation. By using these data, it is possible to make an intelligent calibration which is sufficient for the LED for at least a period of operation. Placing these calibration data close to the LEDs assures that the correct data is in place for the right LED during operation. This is especially important with the knowledge that two LEDs do probably not have the same colour result for the same supply current. Therefore, it is necessary to calibrate each individual LED. Recalibration might be performed after a period of operation. 
     Instead the LEDs can be formed at a chip, which chip further comprises a memory circuit for storing calibration data for the actual LED. As an alternative, the calibration data can be stored in a memory chip which could be formed directly at the LED chip. In this way, the calibration data are stored as close as possible to the actual LED. 
     A number of LED modules can be connected in order to form a longitudinal LED bar, where each LED bar module comprises female connectors at the first end and male connectors at the second end, which connectors comprise a first group of power connectors and a second group of data connectors. For forming a long LED bar, it is necessary to connect a number of LED modules. This is efficiently achieved by placing male and female connectors in each end of each module. Forming both power bus connections and data bus connections in both ends of a module, it is possible to connect both data and power each time a new module is added to the existing module. By using an intelligent light controller, the controller can exchange data and in this way automatically be programmed to operate in conjunction with the neighbours. By performing a light show where the LED modules react correctly on execution of a programme. 
     Preferably, two independent data buses are connected between the modules. By using two different data buses, it is possible to let the modules communicate with the DMX protocol and at the same time exchange data over another and more modern communication protocol. 
     The LED groups can be placed beneath lenses for deflecting generated light in a mainly perpendicular and longitudinal direction of the bar. By using specially designed lenses nearly no light leaves the lenses in a sideward direction in relation to the bar. In the direction perpendicular to the bar, nearly all the light will be radiated in this direction by these lenses. In this way, a bar placed e.g. next to a stage will appear relatively small. 
     The lenses can be placed in relation to reflectors, which reflectors deflect the light in a mainly perpendicular and longitudinal direction in relation to the bar. If reflectors are used, the light transmitted from lenses in the longitudinal directions of the bar can be deflected by reflectors in a direction perpendicular to the longitudinal axis of the bar. Using the reflectors, fewer LED groups are probably necessary for forming a perfect lighting bar. 
     Hereby, it can be achieved that the actual calibration data is stored in relation to the actual colour group. The calibration data is stored at the same pixel board as the colour group. In this way, the calibration data follows the colour group in both initial tests, during normal use and during repair. Hereby, pixel boards are replaceable without performing any start-up calibration. 
     The calibration data for each colour group can comprise at least storage of operational time in relation to the actual colour group power level. Hereby, the wear-out of each colour group can be calculated, and the electric supply parameters for each LED can be adjusted in relation to the wear-out.
     The operational time in relation to the actual power level can be stored in a two-dimensional historic file in the calibration data storage. Hereby, only a small number of data needs to be stored in the calibration memory.   

     The rotation of LED bar can be fulfilled manually through an integrated pivot which is placed at both ends of LED bar modules. When the anticipated angle is reached, rotate the knob which is on the bottom of bracket to secure the position. The angle of the LED bar is capable of being rotated from 0° to 360° freely. 
     By adding the different diffuser film in front of Lens will change beam spread angle. A diffuser film with a certain angle can be hold by a pair of chimps which is located inside the front cover and it is easily removable for alternative. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a LED bar module 
         FIG. 2  shows a sectional view of a LED bar 
         FIG. 3  shows a LED bar  2  seen from a first end 
         FIG. 4  shows the opposite end of a LED module 
         FIG. 5  shows a longitudinal sectional view of a LED bar 
         FIG. 6  shows an isolating cover 
         FIG. 7  shows an exploded view of the LED bar 
         FIG. 8  shows a pixel board 
         FIG. 9  shows a LED bar  2  seen partly opened in one end 
         FIG. 10  shows an exploded perspective view of another embodiment of LED bar module. 
         FIG. 11  shows a cross section view of another embodiment of LED bar module with chimbs. 
         FIG. 12  shows a plurality of another embodiment LED bar modules combined together. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a LED bar module  2  comprising a tube  4  in which tube  4  lighting means in form of LEDs are placed together with control electronics for controlling the light emission of the LEDs. Furthermore,  FIG. 1  shows a first end plate  20  and a second end plate  22 . A fixture  24  is connected to framing means  26 . A printed circuit connector  30  and two bus connectors  32  and  34  are also shown. Furthermore, in this figure, a valve  36  is shown which valve comprises a diaphragm which diaphragm only allows humidity to pass in the direction inside out from the LED module  2 . 
     In operation, power will be connected to the LED module  2  by the connector  30  and data will be connected to connectors  34  or  36 . Thus, the LED module will receive sufficient power and information to start performing a light show where colour change is only one of several possibilities. 
       FIG. 2  shows a sectional view of a LED bar  2 . In a cavity  14 , the housing  4  forms a seat for the pixel board  6  which is heat conductively connected to the tube  4 . Inside the tube  4  in the cavity, a main printed board  8  and a daughter printed board  10  are shown. Both printed boards  8  and  10  are placed inside an isolation cover  12  which isolation cover  12  has an opening  60  ( FIG. 6 ) in which a protrusion  16  of the tube  4  is heat conductively connected to the main printed circuit board  8 . The daughter circuit board  10  is connected to the main printed circuit board  8  by a connector  18 . Outside the tube  4 , first and second end covers  20  and  22  are indicated. Over the pixel board  6 , reflectors  58  are seen which reflectors  58  are placed beneath a cover  64 , and a second cover  66 , which is formed of clear plastic such as poly carbonate. The second cover  66 , seals the tube  4 . At the outside, the tube  4  is connected to a frame  26  which is further connected to holding means  24 . 
     In operation, the heat generated at the pixel board  6  will be conducted into the tube  4 . Further heat produced at the main printed circuit board  8  will also be conducted into the tube  4 . The tube  4  as such is heat conductively connected to the frame  26  from where the heat is radiated or converted outside to the surroundings. 
       FIG. 3  shows a LED bar  2  seen from a first end.  FIG. 3  shows the tube  4  connected to the first end cover  20 . The tube  4  is connected to a frame  26  which is further connected to a holder  24 . A printed circuit board connector  30  is seen and above the PCB connector  30 , two data bus connectors  32  and  34  are seen. Furthermore, a valve  36  is seen comprising a diaphragm which only allows humidity to pass from the inside to the outside of the tube. 
     In operation, the valve  36  allows air to pass from inside out which takes place each time the LED module is connected to power and starts to operate. The module heats up, and air flows out of the operators. After shutting down, the LED module will start cooling down, and air from the outside will be sucked into the cavity. As the air subsequently passes through the diaphragm in the valve  36 , humidity is left outside and in this way the internal volume will be kept dry. 
       FIG. 4  shows the opposite end of a LED module  2 , and this time the second end cover  22  is indicated. Again the tube  4  is mechanically connected to framing means  26  which are connected to a holder  24 . The end cover shows a female printed circuit board connector  40  and female data bus connectors  42  and  44 . 
     Combining  FIG. 4  and  FIG. 3 , it is clear that two or more LED modules can be coupled serial to form a relatively long tube. 
       FIG. 5  shows a longitudinal sectional view of a LED bar  2  which bar is formed of a tube  4 . Inside the tube, a pixel board  6  and a main printed circuit board  8  are indicated. Furthermore, a daughter printed circuit board  10  is seen. At a first end, an end cover  20  is seen and at the opposite end, an end cover  22  is seen. Beneath the tube  4 , a frame  26  and a holder  24  are seen. At the first end, a printed circuit board connector  30  and valve  36  are indicated. At the other end, the female connector  40  is seen. Inside the tube, connectors  50  and  52  are seen which are electrically interconnecting the main board  8  and the pixel board  6 . Furthermore, at the pixel board, LEDs  54  are seen which are placed beneath lenses  56  which lenses  56  are cooperating with reflectors  58 . 
     Light generated from LEDs  54  is at first deflected by lenses  56  in a direction which is longitudinal in relation to the bar. The light which leaves the lenses  56  is then reflected upwards by reflectors  58  with the result that the light leaving the bar is mainly transmitted perpendicular to the bar. By forming the reflectors  58  as a long section with steps between forming reflecting surfaces at the steps, it is possible to let a single group of LEDs light up a relatively long distance of the module. In this way, this module only indicates three groups of LEDs. But seen from the outside, the LED will light up the whole bar. 
       FIG. 6  shows an isolating cover  12  which isolating cover has a longitudinal opening  60 . Furthermore, the isolation cover  12  has a recess  62  at both sides which cooperates with the inner contour of the tube  4  seen in  FIG. 2 . 
       FIG. 7  shows an exploded view of the LED bar  2  which comprises a tube  4  where a pixel board  6  is placed in a recess in the tube  4 . Inside the tube  4  in a cavity, a main printed circuit board  8  is placed inside an isolation cover  12 . The tube  4  is connected to a first end cover  20  and a second end cover  22 . Furthermore, the tube  4  is connected to a frame  26  which frame is further connected to a holder  24 . At the end of the printed main circuit board  8 , female connectors  40  for power and further female data connectors  42  and  44  are seen. Over the pixel board  6 , lenses  56  and reflectors  58  are seen. Above the reflectors  58 , a first cover  64  and a second plastic cover  66  are indicated. The isolation cover  12  comprises an opening  60  and the recess  62 . Furthermore, an end cover  69  is indicated which is cooperating with the end cover  22 . 
       FIG. 8  shows a pixel board  6  on which pixel board a connector  50  is indicated. Furthermore, at the pixel board, LEDs  54  are seen which are placed in groups where each group comprises four LEDs. In addition, memory components  53  and  55  for storing LED calibration data at the board are shown. 
       FIG. 9  shows a LED bar  2  which is partly opened in one end. The tube  4  is seen and inside the tube  4 , the isolation cover  12  is indicated which comprises the main printed circuit board. Also, the frame  26  is seen outside the tube  4 . The end cover  20  covers the first end of the tube and the second end cover is supposed to cover the other end when the tube is correctly assembled. The top cover which is made of a clear plastic  66  is seen and below that cover, the cover  64  is also indicated. 
       FIGS. 10 ,  11  and  12  show another embodiment of the invention. From  FIG. 10  and  FIG. 12 , it is seen that LED bar modules  102  comprising a heat conductive tube  104 , in which tube  104  and lighting means in form of LEDs are placed together. Power supply  108  and colour controller  110  for controlling the light emission of the LEDs are placed outside of the LED bar modules  102 . Furthermore,  FIG. 10  shows a first end plate  120  and a second end plate  122 . A first pivot  184  and a second pivot  186  connect the LED bar modules to rail  124  through the first bracket  180  and the second bracket  182 . Two knobs  181  and  183  are on the seat of the bracket  180  and  182 . LED bar modules  102  is capable of being rotated manually around the dual pivot  184  and  186 . After the anticipated position is reached, to move the knob  181  and  183  toward the tube  104  to fasten or away the tube  104  to loosen can secure the orientation.
     In operation, power and data will be connected to the LED module  102  by the cable  118 . Thus, the LED module will receive sufficient power and information to start performing a light show where colour change is only one of several possibilities.   

       FIG. 11  shows a cross-section view of a LED bar  2 . In a recess  114 , the tube  4  forms a seat for the pixel board  106  which is heat conductively connected to the tube  106 . Over the pixel board  106 , a LEDs  154  can be placed beneath lenses  156  for deflecting generated light, diffuser  185  is seen which is placed beneath a cover  166  which is formed of transparent or translucent plastic such as poly carbonate. 
     In operation, the heat generated at the pixel board  106  will be conducted into the tube  104 . The tube  104  as such is heat conductively connected to the bracket of integrated pivot and further connected to a rail  124  from where the heat is radiated or converted outside to the surroundings. 
     A pair of chimbs  187  and  188  is placed inside of the cover  166  to hold the diffuser  185 . A diffuser film  185  with a certain light angle can be hold by the chimbs. By adding the different diffuser film in front of Lens will change beam spread angle from 20° to 40°, 60° and 120° or any other. When moving away the first end plate  120  and the second plate  122 , it is easily removable for changing different diffuser films, thus alternative. 
       FIG. 12  shows a plurality of LED bar modules  102  are combined together to form a long strip light. The LED bar modules  102  can be aligned through a clamp  190 . The cable  118  integrated power and data is extended from the inside of the tube  104  to the power supply  108  and colour controller  110  which are placed outside of the tube  104 . Preferably, the cable  118  is a CAT5e network cable. Sometimes the colour controller  110  can be a common controller for an array of LED bar modules.