Abstract:
A multifunction lighthead for mounting to a vehicle includes several groups of LEDs arranged to provide distinct light emission patterns. Each group of LEDs and associated optics are selected and positioned to produce light emission patterns needed to meet lighting standards applicable to the vehicle. Such standards may require wide angle light emission, which is enhanced by supporting groups of LEDs that project away from the vehicle body, enhancing visibility of the lighthead from directions close to a plane defined by the body panel. The projecting support for the LEDs and optics for a wide angle light emission pattern may be employed to support LEDs arranged for ground illumination. Other groups of LEDs in the same lighthead may be arranged with optics to provide area illumination in support of arrest, search, triage or other emergency functions.

Description:
BACKGROUND OF THE DISCLOSURE 
       [0001]    The present disclosure relates to lightheads, and more particularly, to LED lightheads for mounting to vehicles. 
         [0002]    Lightheads for mounting to a motor vehicle may be mounted in any one of a multitude of positions and orientations to provide specific lighting functions. Some examples of lighting functions include fog lighting, warning lighting, spot lighting, takedown lighting, ground lighting, and alley lighting, each having directional, intensity, color and emission pattern requirements. Emergency vehicles often utilize lightheads to give visual indications of their presence during emergencies. Different types of emergency vehicles must meet distinct requirements for emergency warning lights, frequently requiring many distinct warning light modules to be mounted to body panels. Mounting each distinct warning light may require one or more holes in the body panel and running electrical power to the location of each warning light. The multiplicity of warning lights can complicate the manufacture of emergency vehicles. Warning light modules may also be referred to as lightheads. Relevant standards include California Title 13, NFPA standards for firefighting equipment and the Federal KKK standard for ambulances. These standards may include ground lighting and scene lighting requirements in addition to standards for warning light signals intended to alert motorists and individuals at any position around the vehicle. 
         [0003]    The mounting location for a lighthead may relate to the specific lighting function that the lighthead serves. Lightheads are commonly mounted to any of a number of surfaces on a motor vehicle. Surfaces to which the lightheads are mounted may include the front grille, side panels, front bumper, rear bumper, brush guard, push bumper, roof, roof rack, and/or side-view mirrors. 
         [0004]    Traditional lightheads may provide limited functionality in each individual unit. Most lightheads are designed for a specific function, and have the ability to produce a specific light emission pattern. In order to provide light emission for different functions and required standards, a vehicle must traditionally utilize multiple lightheads, each lighthead configured for the desired function and pattern of illumination. 
         [0005]    Accordingly, there is a need in the market for a compact, multifunction LED lighthead. 
       SUMMARY 
       [0006]    According to aspects of the disclosure, a compact multifunction LED lighthead comprises a thermally conductive base parallel with a vertically oriented plane, first and second PC boards, a support, at least first and second pluralities of LEDs, and a light-transmissive lens attachable to the base. 
         [0007]    The first PC board is mounted in thermally conductive relationship to the base. The support has first and second surfaces which are oriented transverse to one another in a generally v-shaped configuration. The support is connected in thermally conductive relationship to the base and extends away from the vertical plane defined by the base. A first plurality of LEDs are mounted in groups to the first and second support surfaces and configured to emit a first distinct light emission pattern in a generally horizontal direction. 
         [0008]    In one embodiment, an optic covers each group of the first plurality of LEDs. The optic is a wide-angle collimator having swept ends which creates a wider angle light emission pattern than is possible with LEDs alone. 
         [0009]    A second PC board extends perpendicularly away from the first PC board and is adjacent to the bottom edges of the first and second surfaces of the support and secured beneath the support. A second plurality of LEDs are mounted to the second PC board and configured to emit a second distinct light emission pattern in a generally vertical direction. The first and second groups of LEDs may be arranged on PC boards connected by wires, or constructed with flexible connectors manufactured with the PC boards. 
         [0010]    The configuration of the support and the position of the second PC board play important roles in generating the first and second specific patterns of light. Extending the support away from the base allows light emitted by the first plurality of LEDs to be seen at any point between vantage points close to the vertical plane, representing a side panel of an emergency vehicle. Additionally, arranging LEDs on the second PC board allows the second plurality of LEDs to emit light in a direction perpendicular to said first plurality of LEDs that is not blocked by a lip created by a recessed portion of the base, lens, and bezel in which the electronic components are secured. 
         [0011]    In one embodiment a third plurality of LEDs are mounted to the first PC board and configured to emit a third light emission pattern in a generally horizontal direction. 
         [0012]    A lighthead according to aspects of the current disclosure emits multiple distinct patterns of light in a single compact package, eliminating the need for multiple individual light heads. In addition to reducing clutter on the surface of an emergency vehicle, a lighthead of the current disclosure is relatively inconspicuous. Since the function of three lightheads can be served by a single lighthead mount, a lighthead of the current disclosure may be utilized for unmarked law enforcement vehicles without drawing attention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0013]    Aspects of the preferred embodiment will be described in reference to the drawings, where like numerals reflect like elements: 
           [0014]      FIG. 1  is a perspective view of a fully assembled embodiment of a compact multi-function lighthead of the current disclosure, planes P 1  and P 2  are included for illustrative purposes; 
           [0015]      FIG. 2  is a frontal view of the lighthead of  FIG. 1 , the lens and bezel are omitted for clarity; 
           [0016]      FIG. 3  is a top-plan view of the support, all other components of the lighthead are omitted for clarity; 
           [0017]      FIG. 4  is a cross-sectional view of the lighthead taken along line  4 - 4  of  FIG. 1 , 
           [0018]      FIG. 5  shows a bottom perspective view, of the lighthead of  FIG. 1 , the lens and the bezel are omitted for clarity; 
           [0019]      FIG. 6  is a cross-sectional view of the lighthead taken along line  6 - 6  of  FIG. 1 ; 
           [0020]      FIG. 7  shows the rearward-facing side of the lens, all other components of the lighthead are omitted for clarity; 
           [0021]      FIG. 8  is a frontal view of the base, all other components are omitted for clarity; and 
           [0022]      FIG. 9  shows a sectional view of the optics as seen along a vertical line passing through one die of the first plurality of LEDs. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    Embodiments of a compact multi-function lighthead will now be described with reference to the Figures, wherein like numerals represent like parts throughout the  FIGS. 1-8 . 
         [0024]      FIGS. 1 and 2  depict a lighthead  100  for attachment to a vehicle (not shown). The lighthead  100  generally comprises a thermally conductive base  102 , a thermally conductive support  104 , a light transmissive lens  106  attachable to said base  102 , and first and second PC boards  108  and  110 , respectively. A vertically oriented plane P 1  is parallel with the base  102 , while a horizontally oriented plane P 2  intersects the lighthead  100  along a length denoted by line  4 - 4 . P 1  and P 2  perpendicularly intersect along line  4 - 4 . 
         [0025]    Referring to  FIGS. 2 and 8 , the thermally conductive base  102  has a central recessed portion  114  which is sized to receive a PC board  108 . The base  102  may be constructed from die cast aluminum, or any other cost-effective material which effectively dissipates heat generated by the lighthead&#39;s electronic components. The base  102  defines a channel  116  adjacent the periphery  118  of the lighthead  100 . PC board  108  is mounted in thermally conductive relationship to the base  102  using any manner known in the art to provide strong retentive forces without impeding heat transfer between PC board  108  and the base  102 . In the disclosed embodiment, PC board  108  is generally coplanar with P 1 . 
         [0026]    Referring to  FIG. 3 , the support  104  is a unitary piece of sheet metal cut and bent to provide LED support surfaces  122 ,  124 . A structural cross-piece  128  extends between and connects first and second surfaces  122  and  124 , respectively. End tabs  130  extend from surfaces  122 ,  124  and provide a thermally conductive path away from LEDs  126 . In the disclosed embodiment, the first and second surfaces  122  and  124  are oriented substantially transverse to one another, and extend away from the plane P 1 . Other angular relationships between surfaces  122 ,  124  are compatible with the disclosed lightheads. The position and orientation of the surfaces  122 ,  124  and the associated LEDs  126 , is designed to produce a warning light signal meeting the requirements for a 180° warning light and enhance visibility of the lighthead to individuals positioned close to a plane represented by the vehicle body panel upon which the lighthead is mounted. Conventional panel mounted warning lights meeting this standard typically lack visibility from such vantage points. The cross-piece  128  reinforces the first and second surfaces  122  and  124 , and provides a secure attachment point for the second PC board  110  (described in further detail below). 
         [0027]    The support  104  is mounted in thermally conductive relationship to the base  102 . As shown in  FIGS. 4 and 5 , the support  104  is secured at the end tabs  130  via fasteners  134  to a pair of platforms  132  (see also  FIG. 8 ) raised from the recessed portion  114  of the base  102 . The platforms  132  extend the connection point between the support  104  and the base  102  away from the vertically oriented plane P 1 . 
         [0028]    A first plurality of LEDs  126  are mounted to PC boards  127  secured in thermally conductive relationship to the first and second surfaces  122  and  124  and provide a first distinct light emission pattern. Power is delivered to PC boards  127  through flexible connectors fabricated as part of PC boards  110  and  127 , though other electrical connections between PC boards are known and compatible with the disclosed embodiment. The first plurality of LEDs  126  are arranged to emit light in a generally horizontal wide angle beam. In one embodiment, the first plurality of LEDs  126  and the support  104  are configured to provide high visibility over 180° centered on a line vertically bisecting the lighthead  100 . The first plurality of LEDs  126  and optics  136  are configured to generate a light emission pattern meeting the photometric intensity and spread requirements of the Society of Automotive Engineers (SAE) Standard J 845 class 1. 
         [0029]    As shown in  FIGS. 2, 4, and 5 , optics  136  cover each group of the first plurality of LEDs  126  and cooperate with the first plurality of LEDs  126  to provide the first distinct light emission pattern. The optics  136  collimate the light emitted from the LEDs  126  into a generally horizontal direction, and spread the light emitted in a wider and more consistent pattern within the horizontal plane than is possible with the LEDs alone. Optics  136  are constructed of surfaces designed to cooperate to produce the desired vertically collimated, wide-angle beam according to well-understood optical principles. As best seen in  FIG. 9 , the optic  136  has top, bottom and intermediate emission surfaces  138 ,  140 , and  142 , respectively. Refracting surfaces  137  cooperate with internal reflecting surfaces  139 ,  141  to re-direct light emitted from LEDs  126  into directions generally parallel with plane P 2 . Light redirected by surfaces  137 ,  139  and  141  meets emission surfaces  138 ,  140  at a right angle and passes through emission surfaces  138 ,  140  with little further change in direction relative to plane P 2 . Refracting surface  143  cooperates with curved emission surface  142  to vertically collimate light emitted from LEDs  126 . Emission surface  142  also refracts light passing through it, with the shape of surfaces  142  and  143  selected to result in the desired, vertically collimated wide angle emission pattern. The internal reflecting surfaces  139  and  141  may be aspheric, as shown in the disclosed embodiment, although other known surface shapes are compatible with the disclosed multifunction lighthead  100 . 
         [0030]    Optic  136  is constructed from the sectional shape shown in  FIG. 9  projected along line  4 - 4  and swept about an axis of revolution A R  ( FIGS. 2 and 4 ) at lateral ends of the optic  136 . A R  is centered on the area of light emission of the end LED  126  in each group. The lateral ends are swept in a ninety (90) degree arc about the axis of revolution A R  to form curved refracting surfaces  137 ,  143  and curved emission surfaces  138 ,  140 , and  142 . The swept configuration of the lateral optic ends maximizes the angle of light emission in the horizontal plane P 2  such that light emitted by LEDs mounted to the first surface  122  overlaps with light emitted by LEDs mounted to the second surface  124  providing a continuous horizontal pattern of light emission. Optic  136  is designed to re-direct light emitted from LEDs  126  on trajectories divergent from plane P 2  into trajectories substantially parallel with plane P 2 . Some vertical spread to the light emission pattern from LEDs  126  is permissible and may be necessary to meet the relevant light emission standard. Generally speaking the vertical spread of the desired wide angle horizontal beam is less than 20° up or down relative to plane P 2  and desirably less than 10° up or down relative to plane P 2 . 
         [0031]    The support  104  provides clearance away from a mounting surface of a vehicle (not shown), extending LEDs  126  and optic  136  beyond a bezel  150  (see  FIG. 4 ) which would otherwise impede visibility of the light signal from directions close to plane P 1  Accordingly, the optics  136 , V-shaped design of the support  104 , and raised platforms  132  improve visibility from vantage points close to P 1 . As one example, these vantage points correspond to that of pedestrians or motorists in front and behind a vehicle and close to the vehicle&#39;s path of travel when the subject multifunction lightheads  100  are mounted to the side body panels of the vehicle. The enhanced visibility of the subject lightheads is intended to supplement light signals generated by warning lights mounted to the front and rear of the vehicle. 
         [0032]    In the embodiment where the first plurality of LEDs  126  comply with SAE standards J845 class 1, the first plurality of LEDs  126  emit a high intensity vertically collimated wide-angle beam of light which may be seen at any point between vantage points coplanar with P 1 . Consequently, when the lighthead is mounted on the side panels of an emergency vehicle, pedestrians and motorists positioned directly behind or directly in front of the emergency vehicle can see light emitted by the first plurality of LEDs  126 . 
         [0033]    Referring to  FIGS. 4, 5 and 6  PC board  110  projects perpendicularly from the first PC board  108 . The second PC board  110  may be soldered to the first PC board and a fastener  144  or other means may secure the second PC board  110  to the cross-piece  128  of the support  104 . Alternatively, plug type connectors may be used to form electrical connections between the first and second PC boards  108 ,  110 . The second PC  110  board projects as far from plane P 1  as the support  104 . 
         [0034]    As best seen in  FIGS. 5 and 6 , a second plurality of LEDs  146  are mounted to the second PC board  110 . The second plurality of LEDs  146  is arranged on the second PC board  110  to provide a second distinct light emission pattern. As shown in  FIGS. 5 and 6 , the second plurality of LEDs are oriented to emit light in a direction transverse to plane P 2 . The second plurality of LEDs  146  may function as ground lights, and are mounted at a position on the second PC board  110  so that the light the second plurality of LEDs  146  emits is not blocked by the lip created by the central recessed portion  114  and the peripheral base channel  116  or bezel  150 . Altering the dimensions of the lighthead  100  so that a greater surface area projects beyond the lip and bezel provides more surface area to which the second plurality of LEDs  146  may be attached, and increases the potential for a greater degree of illumination from the second plurality of LEDs  146 . 
         [0035]    A third plurality of LEDs  112  is mounted to the first PC board  108 . The third plurality of LEDs  112  is oriented to emit beams of light in a generally horizontal direction. The type of LED utilized in the third plurality of LEDs  112  is selected to provide a specific third distinct light emission pattern e.g. illumination in support of search, traffic stop, rescue, and arrest activities. 
         [0036]    In one embodiment, the third plurality of LEDs  112  are high intensity white LEDs. High intensity white LEDs can provide a takedown light emission pattern of the type utilized by law enforcement officials when conducting a traffic stop to illuminate the cabin of the vehicle being stopped. Alternatively, high intensity white LEDs can provide an alley light emission pattern to spotlight areas to either side of the vehicle. The focused beam of light necessary to produce the takedown/alley light emission pattern is provided by an optic  120 . In the embodiment shown in  FIGS. 6 and 7 , the optic  120  is a total internal reflection (TIR) optic molded into the lens  106 . Alternatively, optic  120  or lens  106  may include features to re-direct light from LEDs  112  into a downward direction relative to plane P 2  to provide supplemental area illumination adjacent the body panel to which the lighthead  100  is mounted. 
         [0037]    The location on the vehicle where the lighthead  100  is mounted determines whether the first plurality of LEDs provide a takedown or an alley lighting effect. The takedown lighting effect is provided by mounting and orienting the lighthead  100  to emit a high intensity beam of light in a direction aligned with the vehicle&#39;s direction of travel. For example, this function can be accomplished using a pedestal mount (not shown) connected to the push bumper or front bumper of the vehicle. The takedown light emission pattern may alternately be provided by mounting the lighthead to the front grille of the vehicle. 
         [0038]    The alley light emission pattern is provided by mounting and orienting the lighthead  100  to emit a high intensity beam of light in a direction generally transverse to the vehicle&#39;s direction of travel. For example, the alley light emission pattern may be provided by mounting the lighthead  100  to the front quarter panel, door panel, or side view mirror of the vehicle. 
         [0039]    In the embodiment shown in  FIGS. 4, 6 and 7 , the lens  106  is secured to the base  102  in weather-tight relationship. A seal  148  projects from the interior-facing side of the lens  106  along a periphery of the lens  152  in a configuration complementary to the peripheral channel  116 . In the disclosed embodiment a bezel  150  secures the lens  106  in weather tight communication against the base  102 , though the bezel may not be required. 
         [0040]    As seen in  FIGS. 4 and 6 , a gasket  154  projects from the perimeter of the base  118  in a direction opposite the lens  106 . In embodiments where the lighthead  100  is mounted directly to the surface of a vehicle, the gasket ensures a weather tight seal against the vehicle, preventing salt and moisture from penetrating behind the lighthead  100 . 
         [0041]    While a preferred embodiment has been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit of the invention and scope of the claimed coverage.