Patent Publication Number: US-8113681-B2

Title: Blood tracking system

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 11/929,526, filed Oct. 30, 2007, which is a continuation of application Ser. No. 11/195,371, filed Aug. 2, 2005, which claims the benefit of Provisional Application No. 60/598,289, filed Aug. 3, 2004, all of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     The present invention relates generally to the field of blood tracking. In particular, the present invention relates to a portable lighting unit configured to track blood using a light emitting diode (LED) illumination system. 
     There are occasions in which it is useful to be able to easily identify small amounts of blood in a particular environment. For example, a hunter may wound an animal, such as a deer, that runs some distance away from the hunter after being wounded. In such a case, the hunter would like to follow the blood trail in order to find the animal. Small drops of blood can be difficult to see on the ground and on foliage, especially in low light conditions. To aid the hunter, blood tracking systems have been devised that help differentiate the red color of the blood from the rest of the environment. Such systems include the utilization of special filters placed on flashlights and/or special goggles or glasses that highlight the blood. 
     It would be advantageous to provide a portable lighting device that gives the user true blood tracking capability in low-level lighting conditions by using the optical principle of color enhancement. In particular, it would be advantageous to provide a lighting device that gives a distinct visual appearance to blood without requiring special filters on a light source or requiring the user to wear special glasses or goggles. 
     SUMMARY 
     One embodiment of the invention relates to a blood tracking light having a blue LED, a red LED, and a cyan LED. The blue LED, the red LED, and the cyan LED combine to create a light beam that highlights blood. 
     Another embodiment of the invention relates to a blood tracking light having a first light source emitting blue light, a second light source emitting red light, and a third light source emitting cyan light. The first light source, the second light source, and the third light source combine to create a light beam that provides a distinct visual appearance to blood. 
     Yet another embodiment of the invention relates to a flashlight. The flashlight includes a first light source emitting light of a first color at a first intensity, a second light source emitting light of a second color at a second intensity, and a third light source emitting light of a third color at a third intensity. The first intensity is greater than either the second intensity or the third intensity. The second intensity and third intensity are approximately the same. 
    
    
     
       BRIEF DESCRIPTION 
         FIG. 1  is a front elevation view of a tracking device. 
         FIG. 2  is a side elevation view of a tracking device. 
         FIG. 3  is a perspective view of a tracking device. 
         FIG. 4  is an elevation view of a LED array. 
         FIG. 5  is an elevation view of a LED array. 
         FIG. 6  is an elevation view of a LED array. 
         FIG. 7  is an elevation view of a LED array. 
         FIG. 8  is an elevation view of a LED array. 
         FIG. 9  is an elevation view of a LED array. 
         FIG. 10  is an elevation view of a LED array. 
         FIG. 11  is an elevation view of a LED array. 
     
    
    
     DETAILED DESCRIPTION 
     Color perception cannot be attributed directly and solely to wavelengths of light. The eye focuses slightly differently on long wavelengths (reds) than on short wavelengths (blues). According to an exemplary embodiment of the present invention, a tracking device may include a multiple color light source having a red LED light beam and a blue LED light beam that create an illusion causing the eye to see red objects in low level lighting conditions as blaze orange. Simultaneously illuminating a red blood spot with the red LED beam and the blue LED beam of the system creates the desired highlighted orange blood effect. The highlighted blood appears orange and the surrounding background green or brown flora appears blue/purple under the multi color LED beam even when the flora is wet. 
     In an exemplary embodiment, the blood tracking system is incorporated into a portable light source, such as a headlamp flashlight. The headlamp may have a removable, adjustable headband. The headlamp may utilize a single AAA battery to provide power to the LEDs. Alternatively, multiple batteries may be used and the batteries may be of various sizes and types. The blood tracking system may be utilized in other portable light sources such as handheld flashlights and lanterns. 
     In some embodiments, two distinct colors may be utilized. In an exemplary embodiment, one or more blue LEDs (i.e. LEDs having a peak wavelength centered in the range of about 410 nm to about 500 nm) may be used with one or more red LEDs (i.e. LEDs having a peak wavelength in the range of about 600 nm to about 740 nm) to produce a spot that appears to be magenta to a user. In some embodiments, a LED having an output centered at about 425 nm may be used with an a LED having an output centered at about 625 nm. In another exemplary embodiment, a red LED having a wavelength centered around 628 nm and a blue LED having a wavelength centered around 470 nm may be used. 
     In some embodiments, the blood tracking system may include two LEDs (a red LED and a blue LED) that are simultaneously activated to provide the desired blood tracking effect. In other embodiments, additional LEDs are used to increase the brightness of the light source, such as two red LEDs and two blue LEDs, or even more LEDs, such as 3-6 red LEDs and 3-6 blue LEDs. The number of red LEDs may be greater or less than the number of blue LEDs. Also, the intensity of the red LEDs may be greater of less than that of the blue LEDs. 
     In another embodiment, the red LED may be pulsed at a particular frequency, which, when combined with the steady output of the blue LED, can enhance the visual signature of the blood or other red material being tracked. 
     In some embodiments, the LEDs may be used individually, to provide either red output or blue output separately. In other embodiments, other LEDs may be added to the system, including other LEDs having different colors or wavelengths, such as infrared wavelengths. Circuitry may be utilized to provide different lighting options of the various LEDs and combinations of LEDs. 
     The tracking device has several potential uses in addition to use in the hunting context described above. For example, the system may have several potential military uses, such as by medics to determine the source of blood on a body that is covered by dirt, mud, or other material obscuring the wound providing the source of blood. Further, special forces personnel may utilize the invention to track enemy combatants that may have been wounded and are providing a blood trail. Also, the tracking device may be used by forensic analysts to find blood. 
     Referring to  FIGS. 1-3 , according to an exemplary embodiment, tracking device  10  includes a housing with a handle  12 , and a head  14 . Handle  12  includes a grip portion  16 , first power switch  18 , a power supply  20 , and a second power switch  22 . Head  14  and handle  12  are shown coupled to each other at an angle of about 90° and may be formed as a single unitary body. Alternatively, head  14  and handle  12  may be coupled at other angles or in-line such that the head and handle extend along either the same longitudinal axis, or along longitudinal axes that are substantially parallel. In yet another embodiment, head  14  may be rotatably coupled to handle  12  to allow a user to adjust the angle formed by head  14  and handle  12 . 
     Handle  12  may include a grip portion  16  that includes grooves  24  for the fingers of a user to contact while using tracking device  10 . Handle  12  is shown as being generally straight along a longitudinal axis. Alternatively, other ergonomic configurations including a curved handle may be used. Power supply  20  or handle  12  may include a removable cover  26  which may cover a battery compartment. According to some embodiments, tracking device  10  may be adaptable to be used with alternating or direct current from an external power source. 
     Head  14  may include a primary light source  30  and a secondary light source  32 . Primary light source  30  may include a lamp  34 , a reflector  36 , cap  38 , and lens  40 . Lamp  34  may be a xenon bulb. Alternatively, lamp  34  may be another type of incandescent bulb, or one or more white LEDs. Reflector  36  may be generally parabolic in shape to direct light emitted from lamp  34  into a beam. Reflector  36  may be faceted or smooth. Primary light source  30  may include a cap  38  for securing the primary light source  30  to head  14 . Cap  38  may be threadably or otherwise coupled to head  14 . Lens  40  may be disposed within cap  38  to provide a water resistant seal for primary light source  30 . According to some embodiments, reflector  36  may be coupled to cap  38  such that rotation of cap  38  moves reflector  36  relative to lamp  34  whereby the width of the light beam produced by primary light source  30  may be adjusted by rotating cap  38 . Second power switch  22  may be used to turn primary light source  30  on and off. 
     Secondary light source  32  may include a LED array  42 , shown as eight LEDs of similar size in  FIG. 1 . A greater or lesser number of LEDs in other configurations may also be used. LED array  42  may be controlled by first power switch  18 . In some embodiments, first power switch  18  may simultaneously deactivate primary light source  30  and activate LED array  42 . 
     In some embodiments, tracking device  10  may optionally include a power indicator  44 , shown as three LEDs, that may be used to indicate the strength of batteries used to power tracking device  10 . Alternatively, a greater or lesser number of LEDs in other configurations may also be used to indicate battery strength. Also, power indicator  44  may be placed in a variety of positions on tracking device  10 . Secondary light source  32  may be covered by lens  46  to protect LED array  42  and power indicator  44 . 
     According to some embodiments, removable cover  26  may include an optional coupling point  28  which may be used to attach a lanyard to tracking device  10 . Alternatively, a coupling point for a lanyard may be provided elsewhere on tracking device  10 . 
     Referring to  FIG. 4 , LED array  42  may include a total of eight LEDs  48  and  50 . According to some embodiments, LEDs  48  may be blue while LEDs  50  are red. Alternatively, LEDs  48  may be red while LEDs  50  are blue. 
     Referring to  FIG. 5 , a LED array for use in a tracking device may include a total of six LEDs. According to some embodiments, LEDs  52  may be blue while LEDs  54  are red. Alternatively, LEDs  52  may be red while LEDs  54  are blue. 
     Referring to  FIG. 6 , a LED array for use in a tracking device may include LED dies (i.e. components made of a semiconductor material used to generate light in a LED). According to some embodiments one or more red LED dies  56  may be used with one or more blue LED dies  58 . The LED dies may be focused and tuned to produce a homogenous magenta spot. 
     Referring to  FIG. 7 , a LED array for use in a tracking device may alternatively include one or more red LED dies  60  may be used with one or more blue LED dies  62  and one or more green LED dies  64  where the green output is kept to a low level relative to the red and blue outputs to avoid diminishing the highlighting effect of the tracking device. 
     Referring to  FIG. 8 , a LED array for use in a tracking device may include a bicolor LED  66 . According to some embodiments one or more red emitter outputs  68  may be used with one or more blue emitter outputs  70 . The LED emitter outputs may be focused and tuned to produce a homogenous magenta spot. 
     Referring to  FIG. 9 , a LED array for use in a tracking device may include a tricolor LED  72 . According to some embodiments, the tricolor LED  72  may include one or more red emitter outputs  74 , one or more blue emitter outputs  76 , and one or more green emitter outputs  78 . The LED emitter outputs may be focused and tuned to produce a homogenous magenta spot. 
     Referring to  FIG. 10 , a LED array for use in a tracking device may include a magenta LED  80 . The magenta LED  80  may include an emitter  82  designed to emit a magenta output (i.e. a combination of blue and red wavelengths). 
     Referring to  FIG. 11 , a white LED  84  may be used with a filter  86 . Filter  86  may absorb green light while transmitting and balancing blue and red light to create a magenta beam. Alternatively, a plurality of filters may be used create a magenta beam. In some embodiments, a plurality of light sources, such as white LEDs may be used with filters to create a magenta beam. For example, one light source including one or more white LEDs and a blue filter may be used with a second light source including one or more white LEDs and a red filter. 
     According to another exemplary embodiment, the tracking device  10  utilizes three colors to provide the distinct visual appearance to blood. In particular, the tracking device  10  may utilize one or more blue LEDs with one or more red LEDs and one or more cyan LEDs. In a preferred embodiment, the tracking device  10  includes one blue LED, one red LED, and one cyan LED, the combination of the LEDs capable of providing illumination sufficient for blood tracking purposes. According to another embodiment, a single LED array is created with a blue LED die, a red LED die, and a cyan LED die. The use of the blue LED die, the red LED die, and the cyan LED die in a single LED array is advantageous because the light beams from the three LED dies are easier to mix and focus into one beam. In the embodiment using three discrete LEDs, the blue, red, and cyan LEDs may be focused and tuned to produce a homogenous spot using a lens that functions as a color mixer and focusing optic. 
     Referring back to  FIGS. 4 and 5 , the LEDs  48 ,  50  in  FIG. 4  and the LEDs  52 ,  54  in  FIG. 5  may be blue LEDs, red LEDs, and cyan LEDs as desired to provide the three color embodiment. Alternatively, referring to  FIG. 7 , the LED dies  60 ,  62 , and  64  may be blue, red, and cyan to create the LED array. As a further alternative, variable color LEDs (e.g., RGB LEDs) may be utilized along with a controller (e.g. a pulse width modulation controller) configured to control the emitted colors or intensities of the variable color LEDs to provide the blue, red, and cyan light sources that are combined to highlight blood. 
     According to a preferred embodiment, the cyan LED has a peak wavelength of about 505 nm. The red and blue LEDs may have peak wavelengths in the ranges discussed above, but in a preferred embodiment the blue LED has a peak wavelength of about 470 nm and the red LED has a peak wavelength of about 630 nm. 
     The addition of the cyan LED is intended to aid in differentiating dried blood from yellow and brown materials that reflect red light to the same extent as dried blood. For example, green leaves tend to absorb nearly all incident red light while fresh blood tends to reflect red light, causing the fresh blood to be highlighted relative to the green leaves. However, as leaves die and turn yellow, brown, and shades of red, they begin reflecting red light to a much greater extent than green leaves. While fresh blood still reflects red light to a much greater extent than the dead leaves, dried blood exhibits much less reflectivity of red light and can be difficult to distinguish from dead leaves (and other non-green forest materials having red tones) when only red and blue light sources are utilized in combination. Adding a cyan light source provides additional highlighting of blood, in particular, dried blood, relative to dead leaves and other non-green forest materials. 
     The intensity of the individual light sources in the tracking device  10  may be varied to improve the highlighting of blood. In the three color embodiments discussed above, when the tracking device  10  is activated, the luminous intensity (candelas) of the blue and cyan light sources may be greater than the intensity of the red light source. In one embodiment, the number of blue and cyan LEDs is greater than the number of red LEDs to provide the greater intensity of the blue and cyan light sources. In another embodiment, more current is provided to the blue and cyan LEDs to increase their intensity relative to the red LED. In a preferred embodiment, the intensity of the blue and cyan light sources is approximately the same and both have an intensity much greater than that of the red light source. For example, the ratio of the intensity of either the blue LED or the cyan LED to the intensity of the red LED may be ten to one in one embodiment. The increased intensity of the blue LED and the cyan LED relative to the red LED may be accomplished via the selection of appropriate LED sizes or providing the necessary forward current to the LEDs to accomplish the intensity differential. 
     While the detailed drawings and specific examples given describe various exemplary embodiments of the blood tracking system, they serve the purpose of illustration only. It is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the preceding description or illustrated in the drawings. For example, other arrangements of LEDs may be used to create the desired blood tracking effect, or the flashlight may be one of a variety of configurations known in the art. Furthermore, other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangements of the exemplary embodiments without departing from the scope of the invention as expressed in the appended claims.