Abstract:
A headlamp system providing both visible and IR illumination, provided in the same housing and using the same wiring harness as a headlamp system currently in use by the US Military, but instead of utilizing incandescent bulb technology as does the headlamp system currently in use, the headlamp system provided herewith utilizes HID lighting for visible light illumination, LEDs for blackout driving and marker lights, and an array of IR LEDs for IR illumination.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Reference is made to and priority claimed from U.S. provisional application Ser. No. 61/023,622, filed on Feb. 13, 2008. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention pertains to the field of illumination and more particularly to headlamps for vehicles and especially for military vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    The MMPV (Medium Mine Protected Vehicle), as well as other military vehicles, currently use a headlamp system specified in MIL-DTL-14465E (12 Aug. 1998), attached hereto, called a vehicular composite light assembly, shown in  FIG. 1 , including a first incandescent bulb lamp  16  providing a high beam and a low beam, and a second incandescent bulb lamp  17  also providing a high beam and a low beam, but covered by a filter so as to pass only infrared light. An operator switches from visible to infrared illumination, and thus engages one or the other of the bulbs, and then selects high beam or low beam, as needed. The headlamp system can be provided as a quick detachable or as a bolt-down model. (MIL-DTL-14465E indicates it is a specification for tracked vehicles, but the specification is also for headlamp systems used in non-tracked vehicles also.) 
         [0004]    For each headlamp system (the right or left) according to the prior art, MIL-DTL-14465E calls for sealed-beam lamps conforming to MS18003-411, two-filament type, for high and low-beam operation, a clear lens per drawing 7962266, a filter lens for passing substantially only infrared illumination, conforming to 7962265, thus providing the first incandescent bulb lamp  16  and the second incandescent bulb lamp  17 . The prior art headlamp system also includes an incandescent blackout marker light  15  serving as a “position marker” emitting white light through two Y-shaped openings in an otherwise opaque filter lens, and an incandescent blackout driving light  14 , per an applicable drawing or military standard, covered by a hood  14   a  to conceal the light from over-flying aircraft. MIL-DTL-14465E also prescribes that electrical cable shall conform to MIL-C-13486 (stranded tinned copper conductor, rubber insulating core, inner glass braid, black neoprene jacket). 
         [0005]    Incandescent bulbs are inefficient, and the illumination provided by such bulbs, in the visible and also in the infrared, is significantly less than what can be provided by more recently developed lighting technology. High intensity discharge (HID) and light emitting diode (LED) technology provide greater luminosity while consuming less power than standard incandescent lamps. 
         [0006]    An HID lamp consumes less power than an incandescent lamp and has a luminous intensity even greater than a halogen lamp, approximately 200,000 cd (candela). HID lamps work by producing an electric arc through a gas, and in the case of automotive applications, typically xenon gas. The color temperature of an HID light is in the range of 5000 K, similar to daylight. The average lifespan of an HID bulb is 2000 hours, roughly 5 times longer than a standard incandescent lamp. 
         [0007]    Incandescent bulbs are inefficient infrared (IR) light sources because the illumination provided by such bulbs is significantly less than what can be provided by light-emitting diode (LED) technology. One problem with LED sources, however, is that excessive heat generated by the LED chip inside the light housing must be effectively dissipated to avoid damaging the headlight components. 
         [0008]    It would be advantageous to have a headlamp system using more recent lighting technology, but that is fully interchangeable with the existing headlamp, using the same wiring harness, control signals, and housing as the existing headlamp. 
       SUMMARY 
       [0009]    The invention provides a headlamp system that meets the requirements of MIL-DTL-14465E except that in place of the sealed-beam lamps and the clear lens and filter lens therefor, two high intensity discharge (HID) lights are included, one for high beam and one for low beam, and an infrared illuminator is included using an array of infrared (IR) light emitting diodes (LEDs) having a spectrum centered at either 880 nm or 940 nm, depending on the application. IR LEDs are used as a light source for the blackout driving and marker lights. The headlamp system provided by the invention uses the same housing as the headlamp system of MIL-DTL-14465E, and also the same electrical cables, so that both the mechanical and electrical interfaces are the same as for the current headlamp system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The above and other objects, features and advantages of the invention will become apparent from a consideration of the subsequent detailed description presented in connection with accompanying drawings, in which: 
           [0011]      FIG. 1  is a perspective view of a headlamp system according to the prior art. 
           [0012]      FIG. 2  is a front view of a headlamp system according to the invention. 
           [0013]      FIG. 3  is a perspective view of a headlamp system according to the invention. 
           [0014]      FIG. 4  is a perspective view of an opened headlamp system according to the invention, showing a main printed circuit board and a metal plate positioned over two ballasts. 
           [0015]      FIG. 5  is a perspective drawing of an opened headlamp system according to the invention, showing ballasts for the HID lights included in the headlamp system. 
           [0016]      FIG. 6  is a front view of the IR illuminator with the cover off, showing the LED arrangement. 
           [0017]      FIG. 7  is a front view of the IR illuminator cover. 
           [0018]      FIG. 8  is a front view of another embodiment of the IR illuminator with the cover off, showing an LED arrangement and optional Fresnel lenses. 
           [0019]      FIG. 9  is a wiring schematic for a headlamp system according to the invention. 
       
    
    
     DRAWINGS LIST OF REFERENCE NUMERALS 
       [0020]    The following is a list of reference labels used in the drawings to label components of different embodiments of the invention, and the names of the indicated components.
     11  prior art headlamp     12  headlamp according to the invention     12   a  back component of the headlamp housing     12   b  front component of the headlamp housing     12   c  cut out area of interior back component of the headlamp housing     12   d  supports for ballasts and printed circuit board (part of back component of the headlamp housing)     14  blackout driving light     14   a  blackout driving light hood     15  blackout marker light     16  incandescent bulb lamp     17  IR pass filtered incandescent bulb lamp     18   a  low beam HID light     18   b  high beam HID light     18   c  main printed circuit board     18   d  ballast     18   e  ballast     18   f  metal plate with holes for wiring     19  IR illuminator     19   a  low beam IR LED-lens unit     19   b  high beam IR LED-lens unit     19   c  cover     19   e  IR illuminator housing     19   f  Fresnel lens     19   g  IR LED (with integrated lens)     20  base     61  control panel     62  power supply   
 
       DETAILED DESCRIPTION 
       [0048]    Referring now to  FIGS. 1-9 , the invention provides a headlamp system  12  that is interchangeable with the (composite) headlamp system  11  of the prior art. The headlamp system  12  comprises a housing front component  12   b  covering and affixed to a back component  12   a,  the front component  12   b  having two slots, a first slot into which a low beam HID light  18   a  is inserted, and a second slot into which a high beam HID light  18   b  is inserted. An LED blackout driving light  14  is centered above the low and high beam HID lights  18   a    18   b  and located just below a hood  14   a.    
         [0049]    The HID lights  18   a    18   b  differ principally in the reflector lens component. The high beam HID light has a reflector component that provides a more collimated beam. In an advantageous embodiment, the HID lights used in the headlamp system  12  have an average luminescence of 200,000 cd (candela), and a color temperature of 5000 K (similar to daylight). 
         [0050]    Ballasts  18   d    18   e  are affixed to the interior of the housing back component  12   a  at a plurality of supports  12   d,  and fit into a cut out or recessed area  12   c  carved out of the interior of the metal housing component  12   a,  allowing the ballasts  18   d    18   e  to fit further back into the housing. A metal plate  18   f,  typically made of aluminum, is affixed over the ballasts  18   d    18   e  and attached to the back housing component at the plurality of supports  12   d.  The plate  18   f  has two holes to accommodate electrical wiring from the HID lights  18   a    18   b.  A main printed circuit board  18   c  is affixed to the center of the plate  18   f  and mechanically supports and electrically connects the lighting components  14   15   18   a    18   b    18   d    18   e    19   a    19   b    19   g  to electrical contacts within a base  20 . The back component  12   a  includes a centralized hole located beneath the ballasts and the main printed circuit board through which all wiring for the lighting components exit the housing and enter the base  20 . The base  20  contains electrical contacts as well as a nut, serving as both a physical connector to connect the headlamp system  12  to a vehicle, as well as an electrical connector, electrically connecting the headlamp&#39;s lighting components to a vehicle&#39;s control panel  61  and a power supply  62 . 
         [0051]    Located below the HID lights  18   a    18   b  in the housing front component  12   b  is an IR illuminator  19 . Referring more specifically to  FIG. 8 , the illuminator comprises a housing  19   e,  for holding an array of IR LEDs  19   g  on a printed circuit board (not shown), and in an embodiment shown more particularly in  FIG. 8 , includes six IR LEDs  19   g  in a first row and seven IR LEDs  19   g  in a second row. The type of IR LED suitable for use in this embodiment has an integrated lens. In such an embodiment, for low beam operation only the IR LEDs  19   g  in the first row are turned on, but for high beam operation all of the IR LEDs are turned on. The array of IR LEDs is covered by a cover  19   c  made of plastic or glass that may or may not filter out visible light. The cover may or may not include a Fresnel lens  19   f  at locations corresponding to those of the IR LEDs  19   g  used only for high (IR) beam operation. 
         [0052]    In other embodiments, such as the embodiment shown in  FIG. 6 , a combined IR LED-lens unit may be used. The type of IR LED suitable for use in this embodiment lacks an integrated lens, and a separate lens is added to each IR LED to create a combined IR LED-lens unit. Four low beam IR LED-lens units  19   a  are located on one side of the printed circuit board, in this embodiment, shown on the right side of the headlamp. Each low beam unit  19   a  features a dispersion lens for low beam operation. Four high beam IR LED-lens units  19   b  are located on the opposite side of the printed circuit board, in this embodiment, shown on the left side of the headlamp. Each high beam unit  19   b  features a spot lens. High beam operation is achieved by simultaneously turning on all the units  19   a    19   b.  The housing  19   e  is typically made from aluminum, to facilitate conducting LED-generated heat away from those LED units  19   a    19   b,  to the headlamp housing  12   a    12   b.    
         [0053]    The IR LEDs  19   a    19   b    19   g  may have a spectrum substantially centered about one or another wavelength in the infrared. In a typical embodiment, the center wavelength is 880 nm, but higher wavelengths are also used, including 940 nm. The higher wavelength may have the disadvantage of producing less IR illumination per Watt of power consumed, but typically produces no visible light whatsoever, whereas IR LEDs at 880 nm may produce some (reddish) light at the far end of the visible spectrum. In case of using IR LEDs at 940 nm, a headlamp system according to the invention may use an array of more LEDs, even up to three times the number of LEDs shown in  FIG. 8 , and the LEDs may be provided in an array other than one consisting of two rows. For example, an octagonal array may be used. In embodiments using combined LED-lens units, as that illustrated in  FIG. 6 , the units are arranged so that all the high beam IR LED-lens units are located on one side, and all the low beam IR LED-lens units are located on the other side. 
         [0054]    Below the IR illuminator  19  is an LED blackout marker light  15 . 
         [0055]    The headlamp system  12  of the invention has the same form and fit, mounting location, and hardware as the prior art headlamp system  11 , uses the prior art vehicle wiring harness, and is installable by field service technicians in place of the prior art headlamp system. The headlamp system  12  uses the vehicle&#39;s existing switch configuration and wiring harness, illustrated schematically as including the control panel  61  for switching on and off power from the typically 24 v power supply  62 , to different ones of the IR and visible illuminators, and also to the blackout marker light  15  and the blackout driving light  14 . 
         [0056]    IR LEDs suitable for use in the embodiment of the invention shown in  FIG. 8  feature an integrated lens, such as the 880 nm peak IR LED with part number OD-50L from Opto-Diode of Newberry Park, Calif., and the 940 nm peak IR LED with part number OD-50L-940 also from Opto-Diode. IR LEDs suitable for use in the embodiment of the invention shown in  FIG. 6  lack an integrated lens, such as the 940 nm peak IR LED with part number SFH4231 from OSRAM of Munich, Germany. Spot and dispersion lenses suitable for use in the embodiment of the invention shown in  FIG. 6  are available from Ledil OY of Salo, Finland, the spot lens using part number OSS-RS, and the dispersion lens using part number OSS-O. 
         [0057]    The HID lights used in headlamp system according to the invention are a 35 watt Xenon System available from Ibis Tek, LLC of Butler, Pa., the high beam HID light using part number 9-00002213, and the low beam HID light using part number 9-00002214. Ballasts  18   d    18   e  for these lights are also available from Ibis Tek, LLC using part number HID 24 v 9-00002216. 
         [0058]    It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention, and the appended claims are intended to cover such modifications and arrangements.