Patent Publication Number: US-2017356601-A1

Title: High-Output LED AC Bulb Replacement Assembly

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     None 
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     MICROFICHE APPENDIX 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention comprises an optional replacement for the halogen bulb which is commonly used in lighting instruments that are designed to light motion picture, video, and stage productions. 
     2. Description of the Related Art 
     The lighting instruments that have been in use for decades employ halogen light bulbs as their light source. The power consumption of these instruments ranges from hundreds to thousands of watts. Typically, 93% or more of this power is converted to heat, leaving 7% to be converted to light. This is the impetus for many users of these instruments to desire conversion to LEDs, which can provide eight times as much light for the same power draw. 
     Fresnel lenses have been used for centuries to project light from a point source into a spot of variable size. The size of the projected light beam can be varied by moving the light source back and forth with respect to the lens. Since halogen bulbs emit significant infrared heat energy, the Fresnel lens that is incorporated into a typical halogen instrument must be capable of withstanding extreme heat. Such lenses are typically made from thick, stepped glass. 
     These halogen bulbs typically use dual-pin, bayonet or screw bases as their interface to a socket, the socket being connected to mains power via a power cord. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention comprises a direct, plug-in replacement for the halogen bulb used in existing lighting instruments. The invention consists of an LED array, a thermal-management system, a power supply and a power connector. The invention installs in the existing socket of the Fresnel instrument through a compatible power connector. Power is fed from the AC mains through this connector to the power supply, which provides power for the LED array and, in some cases, to the thermal management system. A distinguishing feature of this invention is that it allows the light intensity emitted by the LED array to be continuously varied by means of a standard, external, phase-control AC dimmer in the same manner as the halogen bulb&#39;s intensity may be varied by the same dimmer. 
     SUMMARY OF THE VARIANTS OF THE INVENTION 
     Since there are many variations of lighting instruments which incorporate halogen or other incandescent bulbs, the present invention can take various forms in order to replace the bulb in each of these instruments. There are two primary differences that distinguish the different versions of the present invention: 
     a) the means by which the interface between the AC mains connector socket in the existing Fresnel lighting instrument and the present invention is achieved. This can be accomplished via cylindrical pins or various other mechanical/electrical interfaces;
 
b) the means by which the heat produced by the LED array is transferred to the environment. This may include natural convection only, forced air, liquid cooling, or some combination of those methods. The size, constituent parts, and configuration of the LED cooling apparatus are chosen to specifically accommodate the instrument into which the present invention is being placed.
 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Having thus described various embodiments of the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  is a perspective view of the present invention. 
         FIG. 2  is a perspective view of a convection-cooled embodiment of the present invention. 
         FIG. 3  is a perspective view of a forced-air-cooled embodiment of the present invention. 
         FIG. 4  is a perspective view of a liquid-cooled embodiment of the present invention 
         FIG. 5  is a functional block diagram of the power-supply/thermal-management module. 
     
    
    
       
     
       
         
           
               
             
               
                   
               
               
                 REFERENCE NUMERALS IN THE DRAWINGS 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 10 
                 Cooling module 
                 12 
                 LED array 
               
               
                 14 
                 Power supply 
                 16 
                 Power connector 
               
               
                 18 
                 Finned-aluminum heat sink 
                 20 
                 Pin-fin aluminum heat sink 
               
               
                 22 
                 DC cooling fan 
                 24 
                 Liquid cooling heat sink 
               
               
                 26 
                 Coolant hoses 
                 28 
                 Radiator 
               
               
                 30 
                 DC cooling fan 
                 32 
                 AC Line filter 
               
               
                 34 
                 Full-wave rectifier 
                 36 
                 Voltage buffer 
               
               
                 38 
                 Constant-current regulator 
                 40 
                 AC to DC supply 
               
               
                 42 
                 Micro-controller 
                 44 
                 +12 V DC fan 
               
               
                 46 
                 Over-temperature shut-off 
                 48 
                 Dimmable controller 
               
               
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention consists of four main sub-systems: a cooling module ( 10 ); an LED array ( 12 ); a power-supply module ( 14 ); and, a power connector ( 16 ).  FIG. 1  shows a three-dimensional, perspective view of these four subsystems connected together. 
     The LED array ( 12 ) provides all of the light that is produced by the present invention. In normal operation, the LED array ( 12 ) produces a significant amount of heat, which must be adequately removed in order to maintain a stable operating condition for the LED array. The LED array is mounted in intimate thermal contact with the cooling module. 
     The cooling module ( 10 ) removes heat from the LED array ( 12 ) and maintains the LED array at a suitable operating temperature. The cooling module may have one of several alternate embodiments.  FIG. 2  illustrates one possible embodiment of the cooling module which employs a finned, solid-aluminum heat sink ( 18 ) which is cooled by natural convection.  FIG. 3  illustrates another possible embodiment which employs a finned, solid-aluminum heat sink ( 20 ) plus a cooling fan ( 22 ) to provide forced air.  FIG. 4  illustrates another possible embodiment which employs a fluid-filled heat sink ( 24 ) connected by coolant hoses ( 26 ) to a remote radiator assembly ( 28 ) which is cooled by forced air from one or more fans ( 30 ). 
       FIG. 5  shows a functional block diagram of the power supply module ( 14 ). The power supply module ( 14 ) consists of a printed-circuit assembly and a remote temperature sensor. The power supply module converts the AC mains voltage to a current of a suitable level for driving the LED array. The power supply module incorporates a line filter ( 32 ) to reduce the level of electromagnetic interference that is fed back into the mains circuit. The line filter also includes a soft-start mechanism to suppress destructive current surges into the remainder of the power supply and control circuit. A full-wave rectifier ( 34 ) and voltage buffer ( 36 ) combine to produce a pulsating DC voltage which is fed to the constant-current regulator ( 38 ). The constant-current regulator consists of a power inductor which is switched at approximately 400 kHz by a dimmable controller ( 48 ) to apply the correct voltage and current levels to the LED array for proper operation at the chosen brightness level. A power FET and a power rectifier handle the high-current required to drive the LED array. The power FET and power rectifier, along with the LED array, are mounted directly on the cooling module. The dimmable controller ( 48 ) consists of a special-purpose integrated circuit and associated components which serve to create a drive signal for the power FET. This drive signal responds to the envelope of the AC mains input voltage, which may be controlled by an AC in-line phase-control dimmer. The present invention will work equally well with or without a dimmer. 
     Within the power supply module, an AC-to-DC power supply ( 40 ) is used to generate an appropriate DC voltage level to power the micro-controller ( 42 ). The micro-controller requires one input signal and provides two output signals. The input signal is provided by an NTC thermistor, which senses the temperature of the cooling module in the vicinity of the LED array and provides a DC-voltage level to the micro-controller. This voltage is converted to a digital value by the micro-controller&#39;s on-board analog-to-digital converter. One output signal from the micro-controller is used to control a cooling fan, if such a fan is present in the specific embodiment of the present invention. The second output signal is used to modulate or interrupt the power to the LED array in the event of an over-temperature condition. 
     Where a cooling fan is employed in the embodiment of the present invention, said fan must be capable of pulse-width-modulation speed-control. A proportional-integral-derivative (PID) algorithm is used in the micro-controller&#39;s software to maintain the temperature of the cooling module at a particular value set in the software. The cooling fan is commanded by the software to speed up or slow down, as necessary, in order to maintain the LED array temperature at the set-point value. 
     The power connector module ( 16 ) is designed to connect the power supply module ( 14 ) and the AC mains receptacle in the particular Fresnel instrument into which the present invention is to be placed. In one particular embodiment of the power connector module, the AC mains connection takes the form of a pair of cylindrical posts which insert into cylindrical AC receptacles in the Fresnel instrument. Another embodiment utilizes a single, bipolar, cylindrical connector which provides the AC connection to the Fresnel instrument. Numerous other embodiments are possible and necessary to interface to other existing Fresnel instruments. Every embodiment of the power control module is directly connected to the power supply module.