Abstract:
In one aspect, there is a lithium battery powered LED light. The light includes a lithium battery power source, a switch, and a Gallium Nitride Light Emitting Diode (LED) selectively electrically connected to the lithium battery by the switch. The light also includes a heat sink thermally coupled to the LED and a voltage converter and current regulator circuit having a circuit contact electrically connected to the switch. The LED and the lithium battery are constructed and arranged to provide a predetermined voltage and current to the LED when connected to the lithium battery. The light also includes a housing within which the lithium battery, the switch, the LED, the heat sink and the voltage converter and current regulator circuit are located.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     For background, reference is made to the following U.S. Pat. Nos.  4 , 577 , 263 ;  4 , 656 , 565 ;  4 , 658 , 336 ;  4 , 819 , 141 ;  4 , 851 , 974 ;  4 , 899 , 265 ;  4 , 942 , 505 ;  4 , 963 , 798 ;  5 , 003 , 440 ;  5 , 442 , 528 ;  5 , 642 , 932 ;  5 , 865 , 524 ;  6 , 046 , 572 ;  6 , 019 , 482 ;  6 , 168 , 288 ;  6 , 222 , 138 ; 
     
    
     SUMMARY OF THE INVENTION  
       [0002]     In one aspect, there is a lithium battery powered LED light. The light includes a lithium battery power source, a switch, and a Gallium Nitride Light Emitting Diode (LED) selectively electrically connected to the lithium battery by the switch. The light also includes a heat sink thermally coupled to the LED and a voltage converter and current regulator circuit having a circuit contact electrically connected to the switch. The LED and the lithium battery are constructed and arranged to provide a predetermined voltage and current to the LED when connected to the lithium battery. The light also includes a housing within which the lithium battery, the switch, the LED, the heat sink and the voltage converter and current regulator circuit are located.  
         [0003]     In other examples, the light can include one or more of the following features. The housing includes a metal body that includes the heat sink. The housing includes a metal body having threaded parts that include the switch, which is closed when the threaded parts of the housing are screwed together in a first direction, thereby urging the lithium battery against the circuit contact, causing activation of the voltage converter and current regulator circuit and causing the LED to emit light. The light can include a compressed rubber ring configured to urge the battery away from the circuit contact and deactivate the voltage converter and current regulator circuit when the threaded parts of the housing are turned in a second direction opposed to the first direction. The threaded parts include outside-diameter threads and inside-diameter threads that are moveably coupled to each other. The lithium battery and the Gallium Nitride LED are constructed and arranged to have a shelf life of at least 10 years.  
         [0004]     In other examples, the light includes a collimator optically coupled to the LED. The collimator includes an optical-grade-acrylic-plastic. The collimator is constructed and arranged to produce a substantially 10-degree light beam when the LED is on. The collimator is integrally coupled to the housing, thereby acting as a protective lens at a front end of the light to protect the LED and electronic components included within the housing. The LED is constructed and arranged to emit light waves at a frequency that is seen by the human eye as blue/green or teal in color. The LED has a brightness such that the LED can be seen from a distance of over 1 mile. The voltage converter and current regulator circuit is constructed and arranged to provide at least 85% power efficiency.  
         [0005]     In other examples, the LED is permanently mounted on a metal circuit board holder that includes a thermally conductive path thermally coupled to the LED and a metal body of the housing. The metal circuit board holder includes a first passage. The light includes a one-sided circuit board that includes a second passage aligned with the first passage. The light also includes a connecting wire passing through the first and second passages, where the connecting wire is electrically connected to the circuit board and to a contact for the lithium battery. The light also includes a cavity defined by the housing within which portions of the connecting wire are stored. The housing includes a polished metal in the form of a column. The housing does not include any switches or buttons external to the housing. The LED is electrically connected to an electronic circuit board that includes the voltage converter and current regulator circuit. The electronic circuit board is a one-sided circuit board and the lithium battery is located on a side of the circuit board opposite of where the LED is located. The circuit board includes a passage that is constructed and arranged to allow a wire connected to the LED to pass through the passage in the circuit board to a connection that is in contact with the battery.  
         [0006]     In other examples, the voltage converter and current regulator circuit is constructed and arranged to provide a minimum of 2.7 volts to the Gallium Nitride LED. The Gallium Nitride LED is a 1-watt LED and the Lithium battery is a 3-volt lithium battery. The voltage converter and current regulator circuit is constructed and arranged to power the 1-watt Gallium Nitride LED using the 3-volt lithium battery. The voltage converter and current regulator circuit is constructed and arranged to allow the 3-volt lithium battery to provide at least six hours of continual light from the 1-watt LED. The voltage converter and current regulator circuit includes an inductor electrically connected to the switch and a Schottky type diode including an anode side and a cathode side, were the anode side electrically connected to the inductor. The circuit also includes a current sensing resistor electrically connected to the LED, an output capacitor electrically connected to the cathode side of the Schottky type diode, and a switching transistor electrically connected to the anode side of the Schottky type diode. The circuit also includes a voltage converter and current regulator controller IC that includes a voltage sense port electrically connected to the inductor, a current sensing port electrically connected to the current sensing resistor, and a transistor driving port electrically connected to the switching transistor.  
         [0007]     Numerous other features, objects and advantages of the invention will become apparent from the following detailed description when read in connection with the accompanying drawing in which: 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0008]      FIGS. 1A and 1B  are outline drawings of a side view and a front view of a battery-powered LED light according to the invention;  
         [0009]      FIG. 2  is a cross sectional view of the light of  FIGS. 1A and 1B ;  
         [0010]      FIG. 3  is an assembly drawing of a portion of the light of  FIGS. 1A and 1B ; and  
         [0011]      FIG. 4  is a circuit diagram of an exemplary circuit used in the portable battery-powered light according to the invention. 
     
    
     DETAILED DESCRIPTION  
       [0012]      FIGS. 1A and 1B  illustrate a portable battery-powered LED light  10  according to the invention.  FIG. 1A  illustrates a side view of the light  10 . The housing of light  10  includes a first portion  15  and a second portion  20 . As described in more detail below, a user rotates one of the portions (e.g.,  15  or  20 ) while holding the other stationary to turn light  10  on and off.  FIG. 1B  illustrates a front view of light  10 . The front view shows a lens  25  within the second portion  20  of the housing.  
         [0013]     In one embodiment, the appearance of light  10  is that of a simple, polished metal column with no outside switches or buttons. All that is seen is the outside surface of a body of first portion  15  that abuts the outside surface of a cylindrical head of second portion  20 . The bottom end body (e.g., at first portion  15 ) is flat and the top end (e.g., at second portion  20 ) has a round opening with the collimator/lens  25  recessed away from the face. This elegant appearance advantageously enables light  10  to be unobtrusive and ornaments a supporting office desk or piece of furniture while readily accessible for use.  
         [0014]      FIG. 2  shows a cross sectional view of light  10 . The illustrated example includes a metal barrel at portion  15  having an elongated, hollow, tubular body closed at one end ready to accept and hold a single lithium battery  30 . Part of the outside diameter of the barrel of portion  15  is threaded.  
         [0015]     The cylindrical shaped lithium battery  30  is inserted in the barrel  15  and used as the power source that powers light  10 . A metal electrical contact  35  is staked into a nonconductive cover  40  that is pressed into and encloses one end of a metal circuit board holder  45 . The nonconductive cover  40  has a counter-bore, which is used to capture a donut shaped rubber gasket  50  that acts as a spring to force the battery  30  away from the metal electrical contact  35  to break the electrical circuit and extinguish light  10 .  
         [0016]     A wire  55  is soldered to the metal electrical contact  35  at the inside of non-conductive cover  40 . The wire  55  runs through a hole in the circuit board holder  45  and connects to the circuit board  60 . LED  65  is soldered on the circuit side of the circuit board  60  and oriented to allow the beam to shine away from circuit board  60  and through collimator  25  that also acts as lens cover that protects LED  65  and circuit board  60 . The tapered outside diameter of collimator  25  provides a surface that allows a threaded ring  75  to hold collimator  25  in place inside the cylindrical head  20 . The threaded internal diameter holds collimator  25  in place and seals the face against the shoulder. Plastic collimator  25  also acts as a protector for LED  65  and electronic components against the outside environment.  
         [0017]     In operation, the tubular metal body that forms the first portion  10  not only acts as the storage area for a 3-volt lithium battery  30 , but also is part of the electrical and thermal circuit. The negative-end  80  of battery  30  is grounded against the closed end of the tubular metal body of first portion  15 , which completes the circuit when the positive contact of battery  30  is forced against circuit board contact  35 .  
         [0018]     Longitudinal pressure is applied, in the direction of arrow  85 , to the battery  30  as the body of first portion  15  is screwed in a clockwise motion into the cylindrical head of second portion  20 , moving the positive contact of battery  30  against the metal contact  35  that is staked into a nonconductive cover  40 . Current is conducted through contact  35  along an insulated wire  55  and through a hole in the circuit board  60 , at which point the wire  55  is soldered to circuit board  60 .  
         [0019]     Power is transmitted and controlled by the electrical circuit and electronic components soldered to the circuit board  60 . LED  65  is soldered to circuit board  60 , which, in conjunction with circuit board holder  45 , acts as a heat sink and conducts heat into the metal body (e.g., portions  15  and  20 ) of light  10 . This heat sink combination advantageously maintains LED  65  and extends the life of battery  30 .  
         [0020]     Light transmitted from LED  65  is guided and focused into, for example, a 10-degree beam, by an optical collimator  25 . In one example, optical collimator  25  is located within 0.005 inches from the face of LED  65 . Threaded ring  75  maintains this spacing by pressing against the tapered sides of collimator  25 , forcing it against the inside face of the cylindrical head of second portion  20 .  
         [0021]     The battery power connection is broken and the light is turned off when the body of first portion  15  is unscrewed in a counter clockwise direction and resilient rubber gasket  50  forces battery  30  away from metal electrical contact  35 .  
         [0022]     The thread connecting the barrel of portion  15  and the cylindrical head of portion  20  operate together as the on/off switch. This reliable mechanism contributes to the long life cycle of light  10  in conjunction with the long shelf life of lithium battery  30 , typically at least 10 years, and an almost limitless life of an Indium Gallium Nitride (InGaN) LED.  
         [0023]      FIG. 3  is an assembly drawing that shows structure for connecting lithium battery  30  on one side of circuit board  60  to LED  65  on the other side of the board  60 . Circuit board  60  on which the LED  65  is mounted has a contact point to which wire  55  is soldered. Wire  55  is then passed through a hole  90  in circuit board  60 , and a hole  95  in circuit board holder  45  and then into a cavity counter-bored into circuit board holder  45 . The free end of this wire  55  is then soldered to the electrical contact  35  that has been staked into and held by a nonconductive cover  40 . All soldering and inspection is easily accomplished in full view of the technician before cover  40  is turned over and pressed into circuit board holder  45 . Cover  40  is then pressed into circuit board holder  45 , allowing wire  55  to coil inside where wire  55  remains protected.  
         [0024]      FIG. 4  illustrates an exemplary circuit  100  for light  10 . This circuit advantageously provides steady LED current and thus steady light output, regardless of the battery voltage, until the battery is nearly exhausted. Circuit  100  includes a voltage converter and current regulator circuit. To implement the voltage converter and current regulator circuit, circuit  100  includes battery  30  (typically a single 3-Volt lithium cell), an on/off Switch  105 , a voltage converter/current regulation controller integrated circuit (IC)  110 , an inductor  115 , a diode  120 , with an anode side (A) and a cathode side (K), a switching transistor  125 , an output capacitor  130 , a current sensing resistor  135 , and LED  65 , with an anode side (A) and a cathode side (K).  
         [0025]     In operation, the user closes switch  105  (e.g., by rotating portion  15  and/or portion  20 ), causing the battery voltage to be impressed upon inductor  115  and IC  110 . IC  110 , sensing that there is no voltage present at its current sense input port  140  causes its transistor drive output port  145  to go low (near 0 Volts), turning on transistor  125  for a minimum pre-set period of time, initiating a “soft start,” which minimizes an abrupt inrush of battery current. During this on time, all of the battery&#39;s voltage appears across inductor  115 , and the resulting energy (proportional to the battery voltage and the transistor&#39;s on time) is stored as a magnetic flux in the core of inductor  115 . At the end of the preset transistor on time, IC  110  turns transistor  125  off, and the magnetic flux collapses, inducing current in the inductor windings, causing a higher voltage than the battery voltage to appear at the anode side (A) of diode  120  (i.e., the inductor&#39;s resulting voltage is added to that of battery  30 ). This voltage can typically be greater than twice the battery voltage. For an increase in output voltage, there is a resulting increase in the current provided by the battery  30 . The efficiency of conversion is the quotient of: (output voltage X output current) divided by (battery voltage X battery current). Diode  120  only allows current to flow in one direction towards LED  65 , and the higher voltage from inductor  115 , minus the small inherent voltage loss across diode  120  is impressed upon the anode side (A) of LED  65 . This voltage causes a current to flow through LED  65  and current sense resistor  135 , and thence back through battery  30 . Since the same current flows through LED  65  and current sense resistor  135 , the resultant voltage across resistor  135  is directly proportional to the current through LED  65 , providing a means for IC  110  to monitor LED current. Capacitor  130  stores energy as it is released from inductor  115 , and releases the energy to LED  65  when inductor  115  is not providing it, supplying an almost constant amount of energy to LED  65  when transistor  125  switches on and off as the process continues.  
         [0026]     This process repeats with the transistor on time being gradually increased until the voltage at the IC sense input port  140  is indicative of the desired LED current. An increasing transistor on time causes more energy to be stored and subsequently released by inductor  115 , thus increasing the current flowing through LED  65 . This transistor on time is constantly adjusted by IC  110 , keeping the LED current and thus the LED brightness constant regardless of the battery voltage, as long as the battery&#39;s voltage is within the limits of the circuit design.  
         [0027]     Since current regulator IC  110  switches transistor  125  at a rate of approximately 1 Megahertz, inductor  115  and capacitor  130  can be physically small. A power field-effect transistor is advantageous for transistor  125  because of its extremely low drive current requirements, low voltage drop losses, and fast switching speeds. Diode  120  can be a Schottky type, which exhibits low voltage drop losses and fast recovery time. At these frequencies, it is advantageous to use a circuit board layout that includes short and relatively heavy copper traces. Circuit  100  provides small size and efficient operation from a low voltage battery, typically in the order of 75% to 90% power efficiency over the life of the battery.  
         [0028]     Circuit  100  fits on the small circuit board  60  shown in  FIG. 2 . Controlling the threshold voltage regulates the LED driver current to typically cause furnishing approximately 85% of the maximum optical intensity of the LED.  
         [0029]     Using the techniques described above can provide many advantages. One advantage is long shelf life. Another advantage is furnishing a high level light for a relatively extended period. Another advantage is visibly indicating battery deterioration over a relatively long period before exhaustion. Another advantage is furnishing a light stream visible over an extended distance. Another advantage is furnishing light for night vision in smoky conditions. Another advantage is diffusing heat. Another advantage is relatively easy storage readily available to the user for easy access. Another advantage is relatively small size that produces an abundance of light. Another advantage is an efficient electronic circuit to drive the light emitting diode (LED) to control the current load regulating the voltage applied to the LED. Another advantage is an efficiently collimated light beam. Another advantage is a reliable switch for selectively energizing the LED. Another advantage is using a single 1-watt LED to produce a high level of light. Another advantage is using a small, commercially available battery for powering the LED. An advantageous feature is a convenient structure for moving power from the battery side of a single-sided circuit board to the other side where the LED is located.  
         [0030]     It is evident that those skilled in the art may now make numerous modifications of and departures from the specific apparatus and techniques disclosed herein. Consequently, the invention is to be construed as embracing each and every novel feature and novel combination of features present in or possessed by the apparatus and techniques herein disclosed and limited only by the spirit and scope of the appended claims.