Patent Document

BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a light-emitting diode (LED) light assembly. More particularly, the present invention relates to a readily positionable LED light assembly that is adapted to provide a substantially clean and uniform beam of light.  
         [0003]     2. Description of the Prior Art  
         [0004]     Portable lighting devices of the type frequently known as shop, work, utility or task lights, and other portable lighting devices have limitations in that they often fail to provide a clean light beam. Often, the emitted light has bright or shady spots. These obstructions to the light beam may be caused by the interference of a filament with the emitted light beam. A clean and uniform beam of light is necessary to provide a bright beam over a distance.  
         [0005]     Work lights also require a clean and bright beam of light. One of the essential requirements for work in a close or confined work space is adequate lighting. Non-limiting examples of a confined work space include the engine compartment, the space below the dashboard, or the chassis of an automobile.  
         [0006]     General lighting such as fluorescent overhead lighting typically available in a workspace, such as in a garage, is insufficient for close work. The shadows cast by the many components of an object of work make working without directed illumination nearly impossible.  
         [0007]     A typical lighting solution has been the conventional shop light which includes an incandescent or fluorescent light bulb surrounded on one side by a protective cage and on the other side by a reflective plate. A hook is usually provided for hanging the light from an overhead support. The hook is either a fixed device or a swivel device attached to the reflective plate or the protective cage. The shop light hangs by the hook and is oriented by a worker to direct the light as needed. One limitation of the shop light is finding a suitable location for hanging. Also, when suspended by a swivel hook, the light frequently rotates or moves. The light output direction shifts, thereby reducing its usefulness.  
         [0008]     Shop lights are adequate for general work, but do not provide adequate light for working in close or confined work areas. Moreover, these types of lights are usually too large and cumbersome to fit into constricted workspaces. As a result, light cannot be directed into the desired locations due either to obstructions or the physical size of the components. Also, many of the existing work or utility lights reach uncomfortably high temperatures over an extended use period and these can become hazardous to the user when used in a close work space.  
         [0009]     Additionally, shop lights emit diluted or less intense light in a broad area, rather than concentrating light on a particular desired location. The further a light is positioned away from the work space, the more diluted the light intensity. Thus, shop lights often emit an “overspray” of light. This “overspray” is very distracting and can cause eye irritation. The eye irritation can also lead to time consuming and dangerous working conditions.  
         [0010]     Light-emitting diodes (LEDs) are a commonly used light source in applications including lighting, signaling, signage, and displays. LEDs have several advantages over incandescent and fluorescent lamps, including high reliability, long lifetime, and high efficiency.  
         [0011]     U.S. Pat. No. 6,231,207 to Kennedy et al. discloses a light emitting diode flashlight lamp. This reference discloses the use of an LED as a direct source of light for a flashlight assembly. As shown, the LED is contained in an end cap housing that is threaded onto an end of a translucent cylinder. In this manner, the end cap, and corresponding LED can be positioned to shine light away from the cylindrical tube (i.e., in flashlight mode) or can be positioned to shine light into the cylindrical tube (i.e., in lamp mode). Even with the bright white light LEDs currently available, the LED light source fails to provide a light source having optic tolerances that provide a sufficiently clean, broad and intense light.  
         [0012]     A need therefore exists for a readily positionable compact LED light assembly that is adapted to provide a clean, broad and uniform light whether over a distance or in a confined workplace.  
       SUMMARY OF THE INVENTION  
       [0013]     It an object of the present invention to provide a portable light that is free of filament shading or bright spots.  
         [0014]     It is another object of the present invention to provide a light that utilizes one or more LEDs as the light source.  
         [0015]     It is also an object of the present invention to provide a light having LED optics spatially arranged such that the light tolerances provide a clean and bright light.  
         [0016]     It is another object of the present invention to provide an LED work or utility light that provides a substantially uniform and bright light over distances encountered by workers, such as automobile mechanics, under typical working conditions.  
         [0017]     It is a further object of the present invention to provide an LED utility or work light that provides a substantially clean, uniform and bright light in a confined workspace.  
         [0018]     It is yet another object of the present invention to provide an LED utility light having an optical means that is positioned on a flexible neck.  
         [0019]     It is still another object of the present invention to provide an LED utility light that provides a lighted area approximately twenty inches in diameter at a distance of approximately 24 to 32 inches.  
         [0020]     It is still a further object of the present invention to provide an LED utility light wherein the angle of dispersion of the LED light beam is approximately between 35 degrees and 45 degrees.  
         [0021]     It is a yet further object of the present invention to provide an LED utility light having means for securing the utility light housing to a surface within a work space.  
         [0022]     These and other objects and advantages of the present invention are achieved by an LED work or utility light comprising a lamp head, which houses an array of LED elements, and an optical means, as well as a housing and a power source, that generates the output of the LED elements and produces a substantially clean and uniform beam of light over a range extended from the lamp head to a distance of at least 24 to 32 inches.  
         [0023]     The objects and advantages of the present invention are also achieved by an LED utility light comprising a lamp head, which houses an array of LED elements, a housing, a power source, a flexible neck that is connected at a first end to said housing and at a second end to said lamp head, and an optical means that takes the output of the LED elements and produces a substantially clean and uniform beam of light over a range extended from said lamp head to a distance of at least five feet. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     The foregoing and still other objects and advantages of the present invention will be more apparent from the following detailed explanation of the preferred embodiments of the invention in connection with the accompanying drawings.  
         [0025]      FIG. 1  is a block diagram of the LED light of the present invention;  
         [0026]      FIG. 2  is an exploded perspective view of the lamp head of the LED light of the present invention;  
         [0027]      FIG. 3  is a cross-sectional view of the lamp head of the LED light of the present invention;  
         [0028]      FIG. 4  is a perspective view of an LED utility light according to one embodiment of the present invention, illustrating the lamp head and flexible neck or stalk in a storage position;  
         [0029]      FIG. 5  is a perspective view of the LED utility light of the present invention, illustrating the lamp head and flexible stalk in an extended position;  
         [0030]      FIG. 6  is an environmental view illustrating the LED utility light of the present invention being employed within an automobile engine compartment to illuminate an automobile engine; and  
         [0031]      FIG. 7  is an exploded side perspective view of the LED utility light of the present invention, illustrating the magnetic means for attachment to a ferromagnetic surface within a workspace. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]     Referring to the drawings and, in particular,  FIG. 1  there is illustrated an LED light according to the present invention generally represented by reference numeral  10 . LED light  10  preferably has a lamp head  20  and a housing  25 . Housing  25  contains a power routing element  115 , a rechargeable battery  35 , recharge circuitry  40 , and LED (light emitting diode) driver circuitry  50 .  
         [0033]     As shown in  FIGS. 2 and 3 , lamp head  20  houses an LED module  50 , an optic assembly  55  comprising a lens  60  and a reflector  65 , a power lead  70 , and a heat sink  75 . LED module  50  is preferably a packaged array of a multiplicity of individual LED semiconductor chips disposed on a substrate. The substrate is preferably engineered for optimizing thermal performance and heat transfer, such as substrates supplied by Lamina Ceramics of Westampton, N.J. LED module  50  preferably incorporates means for electrostatic discharge protection.  
         [0034]     LED light  10  employs an LED optical system of the type disclosed in U.S. Published Application Number 2004/0264004 A1 to Jacobson et al., incorporated herein by reference. The &#39;004 Publication is directed to a non-imaging optical system for processing first and second light distributions. The non-imaging optical system includes at least two refractive surfaces, at least one reflective surface nearer to the first light distribution along at least one ray path than the nearer of the two refracting surfaces and the reflective surface. The refractive surfaces cooperate to redirect light edge rays of the first light distribution into the neighborhood of the edge of the second light distribution with a single reflection from the reflecting surface.  
         [0035]     More specifically, the disclosed optical system uses an aspheric dielectric lens with two refraction surfaces at the large aperture of a hollow, funnel-shaped reflector. The back surface of the dielectric (the surface facing the reflector) has a higher curvature than the front surface, making the structure more compact. This approach achieves performance comparable to a non-truncated CPC, with much better compactness. Aspect ratios range from 0.4 to 0.7. Moreover, the dielectric lens has acceptably low thickness for cost-effective molding. Unlike the earlier designs, the small aperture of the funnel is advantageously positioned behind the optic, so that a source or detector can be supported by a much larger circuit board or heat sink without shadowing.  
         [0036]     LED emitted light provides a collimated beam having a wide angle of dispersion. LED module  50  and optic assembly  55  provide a substantially uniform beam of light having little diffusion. In a preferred embodiment, LED module  50  and optic assembly  55  provide an illuminated area approximately 18 to 20 inches. Actual prototypes and production components have measured about 19 inches in diameter when the LED light  10  is at a distance of two feet from an object to be illuminated. Preferably, the angle of dispersion of the light beam of LED light  10  is between about 35 to about 45 degrees. The LED light beam provides a uniform and bright light at these angles, thereby enabling illumination within a confined work space.  FIG. 6  illustrates illumination of an automobile engine work space W by LED light  10 .  
         [0037]     Optic assembly  55 , comprising lens  60  and reflector  65 , is dedicated to LED module  50 . The spatial relationship between lens  60  and reflector  65  provides the tolerances necessary to providing a clean beam of light. Optic assembly  55  gathers the uncontrolled light emitted from LED module  50  and directs such light into an output pattern with a relatively constant intensity. Optic assembly  55  produces a substantially uniform beam of light from the output of LED module  50  over a range extended from lamp head  20  to a distance of at least 24 to 32 inches, although the optic assembly  55  produces a substantially uniform beam of light. This uniformity extends to distances of 40 to 50 feet and sometimes more. However, the brightness of an illuminated area will clearly also be a function of the distance from the optic assembly and a function of ambient light conditions.  
         [0038]     The output pattern is preferably cone-shaped and provides relatively constant intensity across a plane normal to the axis of the cone. LED module  50  preferably also has at least one heat sink  75  for dispersing the heat generated by LED module  50 . Heat sink  75  is preferably a machined unit.  
         [0039]     To obtain a clean or uniform beam of light, the optic assembly  55  should be held dimensionally in the correct position relative to LED array  50 . In the disclosed design, the position of LED array  50 , and the position of optic assembly  55 , are controlled by the heat sink, which is a machined unit having reasonably good tolerances. Required tolerances are no tighter than those produced routinely and typically by computer-numerically-controlled machining equipment.  
         [0040]     Heat sink  75  is preferably a conical structure and functions to draw heat away from the LED module and transfer it to the ambient air. Heat sink  75  preferably has a series of corrugated protrusions or ribs  107  as shown. Ribs  107  optimize surface area for dissipation of heat. Heat sink  75  is engineered from a suitable electrically and thermally conductive material. A non-limiting example of a thermally conductive material is aluminum. Heat sink  75  also serves to conduct electrical power to LED module  50 . Structurally, heat sink  75  further provides the required precise dimensional location of LED module  50  and reflector  65  and support for LED module  50 .  
         [0041]     Lamp head  20  may optionally have a cage  85 , a retaining ring  90 , a connecting means  95  for mechanical and electrical connection of the heat sink to LED module  50 . Cage  85  protects heat sink  75  from casual contact with heat sensitive materials, such as human skin. Cage  85  also functions to support bushing  100  and to provide an engageable connection with retaining ring  90 . Cage  85  is formed of an electrically insulating material such as plastic.  
         [0042]     Retaining ring  90  functions to retain the lamp head  20  while providing uniform pressure on optic assembly  55 , thus holding reflector  65  and lens  60  in precise coaxial alignment relative to one another. Retaining ring  90  additionally provides protection from mechanical shock and impact as well as a measure of moisture resistance. Retaining ring  90  further provides a simple, tool-free means for field disassembly, enabling replacement of a compromised lens. Retaining ring  90  is preferably formed of an elastic material.  
         [0043]     The bushing  100  is formed of an electrically conductive material such as brass. Bushing  100  is installed in cage  85 , serving as both a mechanical mounting means as well as an electrical conductor of a polarity opposite to that of the heat sink  75 . The bushing  100  may be press fit, threaded or connected by any other known means.  
         [0044]     Connecting means  95  may be any means known in the art for providing mechanical and electrical connection. Connecting means  95  is preferably a screw and washer assembly.  
         [0045]     As illustrated in  FIGS. 4 and 5 , lamp head  20  is coupled to housing  25  by a flexible stalk or neck  105 . Flexible stalk  105  is preferably flexible along its entire length and is preferably permanently attached to housing  25 . It should be noted that flexible stalk  105  may be flexible in one or a plurality of locations along its length. The lamp head  20  is pivotally mounted to flexible stalk  105  such that the lamp head  20  is positionable along at least two axes.  
         [0046]      FIG. 4  illustrates lamp head  20  and flexible stalk  105  in a closed or storage position. When lamp head  20  is in the storage position it may be secured to housing  25  by a hook means  110 . Hook means  110  may be any fastening means known in the art. While the hook  110  secures the lamp head  20  in one position (as shown in  FIG. 4 ), it is preferably movable and positionable such that it may support the housing  25  in a plurality of positions. Thus, with hook  110  deployed as shown in  FIG. 5 , by virtue of a detented ball-and-socket joint  111 , the housing  25  can be hung from a support in a plurality of positions or orientations.  
         [0047]     Hook means  110  is preferably coupled to housing  25  by a ball and socket-type mechanism. Hook means  110  also functions to provide a means by which to hang LED light  10  from a support.  FIG. 5  illustrates lamp head  20  and flexible stalk  105  in at least a partially extended position.  
         [0048]     Housing  25  preferably has an external power port (not shown). External or input power may be directed to recharge rechargeable battery  35  via the external power port. External power may alternately be directed to drive LED driver circuitry  45  when rechargeable battery  35  is depleted.  
         [0049]     Referring again to  FIG. 1 , input power may be supplied to recharge circuitry  40  by an automobile battery  16  or a plug-in transformer module commonly known as wall wart or power adapter  17 . Input voltage is preferably about 11.5 to about 18 VDC. It should be noted that input power supplied by wall wart  17  may have some ripple effect. Accordingly, recharge circuitry  40  is preferably designed to be immune from such effect. A “smart charger” may be used, which is capable of detecting the state of the battery, and it is self-regulating to optimize recharge. A smart charger provides the most appropriate voltage and current characteristic to a selected battery type, such as a NiMH battery pack, of recharge circuitry  40 , and additionally prevents overcharging.  
         [0050]     The external power port is adapted to accept 12 VDC from an automotive battery via a cigarette lighter outlet or directly from the battery via “alligator”-type clips. A partially depleted automobile battery has a terminal voltage of approximately 11.5 VDC. A normally running automobile has a system voltage of approximately 14.5 VDC. However, it should be noted that transients common to the automotive electrical system, which boost system voltage to approximately 18 VDC may exist.  
         [0051]     The external power port may also be adapted to accept 12 VDC from wall wart  17 . The North American standard for input voltage is 120 VAC 60 Hz. Nominal output voltage will be 12 VDC at rated current.  
         [0052]     Input power to LED driver circuitry  45  is approximately 8.4 VDC to 18 VDC. Input power will contain some ripple if the power source is a wall wart. Accordingly, LED driver circuitry  45  is preferably designed to be immune to such ripple.  
         [0053]     Power routing element  115  enables a user to switch between several modes of operation. A first mode draws internal power from rechargeable battery  35  for normal LED operation. A second mode draws external power to LED module  50  if lighting is desired. A third mode draws external power to the battery recharge circuit, if LED module  50  is not operational. Power routing element  115  may be any mechanical means for switching known in the art such as switch contacts. Power routing element  115  may be solid-state means or any combination of mechanical and solid-state means.  
         [0054]     In a preferred embodiment, LED light  10  further has a charge status indicator (not shown). The charge status indicator may be any indicator known in the art such as a small lamp, an audio device or any other signaling means.  
         [0055]     Other embodiments are possible that use primary cells (replaceable, non-rechargeable batteries). In these embodiments, the energy source is exclusively the primary cells; there is no external port nor is there any need for power-routing  115  nor for recharge unit  40 .  
         [0056]     The lamp head  20  is interchangeable between a white light mode and any other commercially available LED color. Non-limited examples include ultra-violet, violet, blue, green, amber, and red. Since there is no such thing as a white LED die, a close approximation of white is commercially obtained by coating blue LED die with various phosphors.  
         [0057]     Various lighting applications may benefit from illumination via a colored light other than white. One example includes detection of ultraviolet dyes employed in leak detection and security; another includes red light, which is sometimes employed in low-light conditions to preserve night vision.  
         [0058]     The LED module  50  preferably consists of a cell array populated with a prescribed number of LED die. In a preferred embodiment, LED module  50  consists of a Lamina 7-cell array populated with  42  LED die. In a more preferred embodiment, the LED die are wired in a configuration having three in a series and fourteen sets in parallel. Nominal forward voltage of a single die is approximately 3.5 VDC. Accordingly, three LED die in a series provide approximately 10.5 VDC. Nominal forward current is 30 mA per series of die. Accordingly, fourteen sets in parallel provide a forward current of 420 mA.  
         [0059]     To provide the brightest light for illumination, however any color LED die may be employed. In an alternate embodiment, LED module  50  has blue ultraviolet LED die. Blue ultraviolet LED may be useful for automotive leak detection as well as for non-automotive uses such as security, adhesive curing, detecting Freon leaks in refrigeration systems and any other known use. In this embodiment, LED module  50  preferably has a Lamina 7-cell array populated with fourteen blue die in the range of 470 nm. In a more preferred embodiment, fourteen blue die are wired in parallel and run at approximately 420 mA at approximately 3.5 VDC. LED module  50  may alternately have twenty-eight blue die in the range of 470 nm. In this embodiment, twenty-eight die are wired in two parallel lines, fourteen in a series, and run at 420 mA at approximately 7 VDC.  
         [0060]     Flexible stalk  105  preferably has a quick-release means incorporated therein for allowing rapid removal of the lamp head  20  and changeover from a white lamp head to a UV or any other LED lamp head. The quick-release means preferably has a mechanical mounting system and a set of electrical contacts.  
         [0061]     As shown in  FIG. 5 , housing  25  preferably has a series of attaching means  120  disposed along at least one outer surface of housing  25 . Attaching means  120  may be magnets, Velcro, clamp or other suitable attachment means. Attaching means  120  enable housing  25  to be attached to any suitable working surface such as an automobile engine. Alternately, LED light  10  may have clamp or other suitable means for fastening housing  25  to a work space.  
         [0062]     The present invention has been described with particular reference to the preferred embodiments. It should be understood that the foregoing descriptions and examples are only illustrative of the present invention. Various alternatives and modifications thereof can be devised by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the appended claims.

Technology Category: 2