Abstract:
A lighting device includes a housing, multiple light emitting diodes (LEDS), and multiple magnifier lenses. The multiple LEDS and the multiple magnifier lenses are located in the housing. Each of the magnifier lenses corresponds to a different one of the LEDS, and there are less magnifier lenses than LEDS. Each LED that has a corresponding magnifier lens is arranged with respect to its magnifier lens so that substantially all of the light emitted by the LED only traverses its corresponding magnifier lens. At least one of the LEDS emits light that does not traverse any of the multiple magnifier lenses.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This is a continuation of U.S. application Ser. No. 12/166,420, filed Jul. 2, 2008,which was a continuation of U.S. application Ser. No. 10/518,219, filed Dec. 16, 2004,now U.S. Pat. No. 7,461,944, which was the National Stage Entry of International Application No. PCT/US03/19385, filed Jun. 20, 2003 which claimed the benefit of US Provisional Application No. 60/390,245, filed Jun. 20, 2002, the entire disclosures of which are hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention generally relates to portable lighting devices (e.g., flashlights) and, more particularly, to a lighting device using multiple light emitting diodes (LEDs) as the light source. 
         [0003]    Many light illuminating devices, such as flashlights, typically employ an incandescent lamp as the light source. Light emitting diodes (LEDs) offer many advantages over conventional incandescent lamps. LEDs are durable, have a lamp life of about 8,000 hours; and because they operate at low current drains, the useful life of energy storage batteries powering LEDs is extended. Despite these advantages, there are certain aspects of LEDs which limit their usefulness in certain applications, such as in portable lighting devices. The best standard 5 mm white LEDs currently available on the market are typically rated at about 3.6 volts, 30 milliamps (mA), and produce less than four (4) lumens of light. In comparison, an incandescent lamp used in conventional lighting devices with a similar voltage rating will typically produce light output that can range from less than ten (10) lumens to greater than forty (40) lumens or anywhere in between. 
         [0004]    A solution to overcome the limitation of the LED currently being investigated is to use multiple LEDs as the light source in the lighting device. Some portable lighting devices currently use up to ten (10), or even more, LEDs as the light source, which increases the cost of the lighting device. Additionally, the light rays emitted by each LED are dispersed (e.g., forty degrees), and simply using multiple LEDs as the light source does not cure this problem. 
         [0005]    One further approach to the solution is disclosed in U.S. Pat. No. 5,174,649 which employs one or more LEDs that illuminate portions of a single refractive lens element having hyperboloidal surfaces which translate the LEDs emitted rays into substantially parallel beams within the single refractive lens element. Another approach employing multiple LEDs in a flashlight is disclosed in U.S. Pat. No. 6,485,160 which employs multiple reflector wells, each housing an LED and a lens. While such approaches provide some directivity and concentration of light rays emitted from multiple LEDs, drawbacks still exist. For example, the formation of a complex refractive lens element and the requirement of the multiple reflector wells add to the cost and complexity of the lighting device. 
         [0006]    In view of these disadvantages, it would be desirable to have an LED-based lighting system for a portable lighting device, which emitted light in a directed and concentrated manner. 
       SUMMARY OF THE INVENTION 
       [0007]    In one aspect, a lighting device includes a housing, multiple light emitting diodes (LEDS), and multiple magnifier lenses. The multiple LEDS and the multiple magnifier lenses are located in the housing. Each of the magnifier lenses corresponds to a different one of the LEDS, and there are less magnifier lenses than LEDS. Each LED that has a corresponding magnifier lens is arranged with respect to its magnifier lens so that substantially all of the light emitted by the LED only traverses its corresponding magnifier lens. At least one of the LEDS emits light that does not traverse any of the multiple magnifier lenses. 
         [0008]    In another aspect, a lighting device includes a housing, first and second light emitting diodes located in the housing, a first magnifier lens arranged in a light path of the first light emitting diode that focuses a first light beam of the first light emitting diode onto a target area, wherein substantially all of the first light beam traverses the first magnifier lens, a second magnifier lens arranged in a light path of the second light emitting diode that focuses a second light beam of the second light emitting diode onto the target area, wherein substantially all of the second light beam traverses the second magnifier lens, wherein substantially all of the first and second light beams only illuminate the target area, a third light emitting diode located in the housing, wherein the third light emitting diode generates a third light beam that does not traverse the first and second magnifier lenses, a support member that respectively supports the first and second magnifier lenses relative to the first and second light emitting diodes, and a rear housing coupled to a back side of the housing, the rear housing having a battery compartment. 
         [0009]    In another aspect, a method includes focusing a first light beam generated by a first light emitting diode with a first lens at a target region, focusing a second light beam generated by a second light emitting diode with a second lens at the target region, wherein substantially all of the first and second light beams illuminate only the area within the target region, and emitting a third light beam that does not traverse the first and second lenses. 
         [0010]    In accordance with the teachings of the present invention, a lighting device is provided which uses multiple LEDs to illuminate a target area. The lighting device includes a housing and first and second light emitting diodes located on the housing and spaced from each other. The lighting device also includes a first magnifier lens arranged in a light path of the first light emitting diode for focusing a first light beam onto a target area, and a second magnifier lens arranged in a light path of the second light emitting diode for focusing a second light beam onto the target area. The lighting device further has a support member for supporting the first and second magnifier lenses relative to the first and second light emitting diodes, respectively. 
         [0011]    In another aspect of the present invention, the support member is a cover extending over the front of the housing, and the cover has a non-reflective inner wall. In a further aspect of the present invention, the lighting device comprises first and second convex magnifier lenses. The axes of the first and second LEDs are parallel to each other, and each magnifier lens is positioned orthogonal to the axis of the first and second LEDs, respectively. 
         [0012]    The lighting device of this invention takes advantage of the positive attributes of LEDs, while minimizing costs. The lighting device is designed to produce a spotlight beam from each individual LED and magnifier lens combination which overlaps with the spotlight beam produced by each adjacent LED and magnifier lens combination. The target area is illuminated with a substantially single spotlight beam which shows excellent symmetry and high, uniform intensity. 
         [0013]    These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0015]      FIG. 1  is a perspective view of a headlamp lighting device utilizing the multiple LED lighting system of the present invention; 
           [0016]      FIG. 2  is an exploded view of the lighting device of  FIG. 1 ; 
           [0017]      FIG. 3  is a cross-sectional view of the front portion of the lighting device; 
           [0018]      FIG. 4  is a top view layout of the multiple LEDs and magnifier lenses in the lighting device of the present invention; and 
           [0019]      FIG. 5  is a reduced top view layout of the multiple LEDs and magnifier lenses, further illustrating the resultant spotlight beam coverage. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    Referring to  FIG. 1 , a lighting device  10  is shown employing multiple light emitting diodes (LEDs) and multiple magnifier lenses according to one embodiment of the present invention. The lighting device  10  is shown as a headlamp flashlight (e.g., spotlight) having an adjustable strap  16  adaptive to be worn on the head of a user. While the lighting device  10  is shown and described herein as a headlamp flashlight, it should be appreciated that the lighting device  10  may be employed in any of a number of lighting systems to provide light illumination to a target area. 
         [0021]    As shown in  FIGS. 1-3 , the lighting device  10  generally includes a rear housing  14  connected to an adjustable strap (headband)  16 . The rear housing  14  provides a compartment for housing a plurality of energy storage batteries  52  (e.g., AA-type alkaline batteries) which serve as the electrical power source. The lighting device  10  further includes a front housing assembly  12  containing the light source and light focusing components of the lighting device  10 . The front housing assembly  12  has a molded housing  18  forming the rear and side walls. Located within the housing  18  is a printed circuit board  20  having a light control switch  22  and other electrical circuitry (not shown) for controlling energization of the lighting device  10  by controlling the application of electrical current from the power source to the light source. According to one embodiment, the control switch  22  is a manually-actuated, three-position switch having a first position in which all the LEDs are turned off, a second position to turn on two LEDs, and a third position to turn on a third LED. 
         [0022]    The lighting device  10  includes, as the light source, a plurality of light emitting diodes (LEDs) that are shown connected to the printed circuit board  20  which, in turn, is connected to housing  18 . The LEDs include a first LED  24  spaced from a second LED  26  for generating first and second light beams, respectively. Also shown disposed between first and second LEDs  24  and  26  is a third LED  28  for emitting a third light beam. The LEDs  24 ,  26 , and  28  used as the light source in the lighting device  10  of the present invention are commercially available from a variety of sources. One example of a commercially available white LED is Model No. NSPW500BS available from Nichia Corporation. It should be appreciated that various kinds of LEDs are readily available from several commercial suppliers. The LEDs  24 ,  26 , and  28  can be of any color, depending upon the choice of the users. According to one embodiment, the first and second LEDs.  24  and  26  are white LEDs made by Nichia Corporation, and the third LED  28  is a red-colored LED. 
         [0023]    The lighting device  10  also includes an inner cover  30  fastened to front housing  18  to provide a covering over the printed circuit board  20 . Inner cover  30  has openings for allowing the first, second, and third LEDs  24 - 28  to extend therethrough forward of the inner cover  30 . Assembled to the front of inner cover  30  is an outer cover and support member  32  that covers the front face of cover  30  forward of LEDs  24 ,  26 , and  28 . Outer cover and support member  32  supports the first and second magnifier lenses  34  and  36  and forms a cover on front housing  18 . The inner wall of outer cover and support member  32  is non-reflective, and thus does not reflect any substantial light rays. The first and second magnifier lenses  34  and  36  may be integrally formed within the outer cover and support member  32  or may otherwise be attached to outer cover and support member  32 . According to one embodiment, the outer cover and support member  32  is made of a polymeric material (e.g., plastic) and the magnifier lenses  34  and  36  are integrally formed within the polymeric material. In a further embodiment, cover member  32  is made of a substantially transparent material that allows light rays to pass through. 
         [0024]    The magnifier lenses  34  and  36  are light transparent optics magnifiers that magnify light transmitted through the lens and direct the magnified light in a light beam. The magnifier lenses  34  and  36  may each be configured as a double convex magnifier lens as shown, according to one embodiment. According to another embodiment, the magnifier lenses  34  and  36  may each include a plano convex magnifier lens. The magnifier lenses  34  and  36  each have at least one convex surface to provide magnification to focus the light beam. The magnifier lenses  34  and  36  can be made of any transparent material, such as glass or polymer (e.g., polycarbonate). The dimensions of the magnifier lenses  34  and  36  can vary depending upon the spotlight diameter desired by the user. The magnifier lenses  34  and  36  used in the present invention are commercially available from a variety of sources and may each include a polycarbonate double convex magnifier lens having Model No. NT32-018, commercially available from Edmund Industrial Optics, having a diameter of nine millimeters (9 mm) and a focal length of nine millimeters (9 mm). 
         [0025]    Electrical power lines  54  and  56  extend between the printed circuit board  20  within the front housing  18  and the energy storage batteries  52  located in rear housing  14 . The electrical power lines  54  and  56  supply electrical current (e.g., direct current) from the batteries  52  to the LEDs  24 - 28  to power the LEDs  24 ,  26 , and  28  which generate the corresponding light beams. According to one embodiment, the third LED  28  may be illuminated separate from LEDs  24  and  26  to provide a light beam of a different color as compared to LEDs  24  and  26 . According to one embodiment, LEDs  24  and  26  provide a white light beam, while LED  28  provides a red colored light beam. 
         [0026]    Formed at the bottom of front housing assembly  12 , along the bottom edge of support member  32 , is a hinge assembly  58  that is connected to the rear housing  14 . Hinge assembly  58  is rotatable about a horizontal axis to allow the front housing assembly  12  and corresponding LED  24 - 28  and magnifier lenses  34  and  36  to rotate relative to the rear housing  14 . This enables a user to rotate front housing assembly  12  to adjust the height positioning of the illuminating light beams. 
         [0027]    The lighting systems arrangement of the LEDs  24 - 28  and magnifier lenses  34  and  36  is best illustrated in  FIGS. 3 through 5 . First and second LEDs  24  and  26  are arranged relative to magnifier lenses  34  and  36  to produce first and second light beams  44  and  46 , respectively. The first LED  24  illuminates the first magnifier lens  34  to generate a first light beam generally within a defined full angle field of view of about forty degrees(40°). Substantially all of the light generated by the first LED  24  is illuminated onto the first magnifier lens  34  which magnifies and redirects the first light beam in a path shown in  FIGS. 4 and 5  by dashed lines  44 . The second LED  26  likewise illuminates the second magnifier lens  36  to generate a second light beam within a defined full angle field of view of about forty degrees(40°). The light beam generated by the second LED  26  is illuminated onto the second magnifier lens  36  which refocuses and directs the light beam in a second path shown by dashed lines  46 . 
         [0028]    Light beams  44  and  46  are shown substantially overlapping and substantially cover a common target area  50  to form a single spotlight having excellent symmetry and uniform intensity. By employing the arrangement of the first and second LEDs  24  and  26  and magnifier lenses  34  and  36 , respectively, focused onto a single target area  50 , increased brightness illumination is achieved in target area  50 . 
         [0029]    The third LED  28  is shown generating a light beam in a path shown by phantom lines  48  that extends substantially between an opening between magnifier lenses  34  and  36 . The light beam  48  generated by LED  28  is emitted within a full angle wide field of view of about forty degrees(40°). Accordingly, a substantial portion of the light beam  48  generated by a third LED  28  is not directed through a magnifier lens and, hence, is not magnified and focused onto the focal target area  50 . Instead, the third LED  28  illuminates a wider angle of coverage and, thus, operates more as a floodlight. 
         [0030]    Each of the three LEDs  24 - 28  includes an electrically powered diode shown as diodes  24 A,  26 A, and  28 A, respectively. The diodes  24 A,  26 A, and  28 A generate light rays in response to the application of electrical current. Each of the diodes  24 A,  26 A, and  28 A are shown enclosed within a transparent housing  24 B,  26 B, and  28 B, respectively. While lamp-type LEDs are shown and described herein, it should be appreciated that other LEDs may be employed in the lighting device  10 . 
         [0031]    The first and second LEDs  24  and  26  are spaced apart from each other by distance D which is measured from the center of the LEDs. In one embodiment, distance D is about 18.2 mm. The magnifier lenses  34  and  36  can be glass (SF5) double convex magnifier lenses which, in one embodiment, are 9 mm in diameter with a 9 mm effective focal length. Magnifier lens  34  is positioned orthogonal to first LED  24 , while magnifier lens  36  is positioned orthogonal to second LED  26 . The central focal axes of first and second LEDs  24  and  26  are parallel to each other. The surface of the magnifier lenses  34  and  36  can be placed from the tip of their respective LEDs at a distance L A  and L B  to allow for a back focal length of 7.9 mm, according to one embodiment. This is the distance L A  and L B  between the focal point within the first and second LEDs  24  and  26  and the surface of the corresponding lenses  34  and  36 , respectively. 
         [0032]    The spotlight beam produced from the first LED  24  and magnifier lens  34  combination substantially overlaps with the spotlight beam produced from the second LED  26  and magnifier  36  combination. The overlap may be less than a complete overlap of light beams  44  and  46  due to the offset arrangement of the perpendicular LED  24  and  26  and magnifier lenses  34  and  36  combinations. However, the combination of LEDs  24  and  26  and magnifier lenses  34  and  36  can result up to a two hundred percent (200%) increase in beam intensity, as compared to a single LED alone. 
         [0033]    Accordingly, the lighting device  10  of the present invention advantageously produces an enhanced intensity and uniform spot beam focused onto a target area  50  by employing multiple LEDs at a minimal cost. While light beams  44  and  46  do not completely overlap when offset magnifier lenses  34  and  36  are arranged orthogonal to LEDs  24  and  26 , the resultant light beams  44  and  46  do substantially overlap in target area  50 . The overlapping target area  50  could further be refined by tilting magnifier lenses  34  and  36  towards a common target area so as to focus beans  44  and  46  onto an overlapping target area. However, the tilting of magnifier lenses  34  and  36  may change the shape of the resultant light beams  44  anal  46 . 
         [0034]    The power source used in the light system of the present invention can be any conventional power source. AC and DC current can be used. Conventional dry cell batteries, for example, zinc/MnO 2 , carbon/zinc, nickel metal hydride, or lithium-based electrochemical cells can all be used. 
         [0035]    It will be understood by those who practice the invention and those skilled in the art, that various modifications and improvements may be made to the invention without departing from the spirit of the disclosed concept. The scope of protection afforded is to be determined by the claims and by the breadth of interpretation allowed by law.