Abstract:
The present invention is a system of emergency vehicle lighting that uses a low profile hood/trunk mounted LED plate unit and a door mounted LED strip unit. It is designed for both stand alone operation or for integration into an emergency vehicle&#39;s electronic alarm notification sequencing unit. The hood/trunk LED plate unit has a thin, enhanced geometrical configuration and an LED lens design that allows the light emitted from the superbright LEDs to be seen to a much higher degree to vehicles approaching from direction normal to the longitudinal centerline of the emergency vehicle. Mounting of the LED plate unit and LED strip unit can be permanent or temporary and because of the light weight, numerous chemical, magnetic and mechanical methods of affixation may be utilized.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a lighting system that can be removably affixed to an emergency vehicle to enhance the visibility of the emergency vehicle from all angles and from a distance that allows ample time for corrective action on the part of approaching drivers. More particularly, to a inexpensive exterior lighting system that can be easily integrated into the vehicle&#39;s electrical system or electronic alert sequencing unit and attached to exterior locations about the emergency vehicle such as the door or hood. 
   Most conventional emergency vehicles today have a variable audible alert, sequenced flashing head/tail/side light assemblies and a roof mounted light bar containing at least one light source designed to disburse light in 360 degrees. These lights may be solid, stroboscopic, revolving, flashing, modulated, pulsing, oscillating, alternating or any combination thereof. While in most situations any of the aforementioned devices will adequately alert a passerby of the presence of the emergency vehicle, there are crucial situations in which this is not the case. Specifically, when an emergency vehicle must enter into an intersection at the junction of more than one road, problems arise. 
   When exigent circumstances exist, the emergency vehicle often has to traverse the intersection against the prevailing traffic light. While those vehicles approaching approximately head on with the emergency vehicle receive the benefit of all of the emergency vehicle&#39;s alert devices, objects such as trees, bushes, other vehicles, or knolls often obstruct the view that vehicles approaching at acute angles have. Additionally, vehicles approaching the emergency vehicle at right angles (broadside) are already disadvantaged because they do not have the benefit of a visual line of sight with the emergency vehicle&#39;s front flashing lights as well as much of the roof mounted light bar alerts. Protocol is for the emergency vehicle to slowly creep into the intersection with the alert devices enabled. Herein lies the problem. The conventional system is not visible to the driver approaching at right angles until the center of the emergency vehicle is out into the middle of the intersection. At this time if the approaching vehicle is moving too fast to stop the emergency vehicle gets struck broadside and at the approximate center of the vehicle. 
   A similar problem arises when the emergency vehicle must be left unattended in an intersection, as is often the case at intersection accidents or where access to a road must be physically blocked from use by the emergency vehicle. Vehicles approaching the emergency vehicle at right angles are at the greatest danger of colliding with the emergency vehicle. 
   The present invention is a system of emergency vehicle lighting that uses a hood/trunk mounted LED assembly and a door mounted LED strip. The hood/trunk LED assembly has an enhanced three dimensional geometrical configuration that allows the light emitted from the LEDs to be seen from an approximate 135 degree horizontal viewing angle from either side of the longitudinal centerline of the emergency vehicle (270 degree total field of horizontal view) and a vertical field of view that encompasses all possible situations. 
   Henceforth, an emergency vehicle lighting device and system would fulfill a long felt need in the emergency vehicle industry. This new invention utilizes and combines known and new technologies in a unique and novel configuration to overcome the aforementioned problems and accomplish this. 
   SUMMARY OF THE INVENTION 
   The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a lighting system for an emergency vehicle that is able to enhance the visibility of the emergency vehicle especially to those people in vehicles approaching the emergency vehicle at right angles. 
   It has many of the advantages mentioned heretofore and many novel features that result in a new configuration of a vehicular lighting system which is not anticipated, rendered obvious, suggested, or even implied by any of the prior art, either alone or in any combination thereof. 
   In accordance with the invention, an object of the present invention is to provide an improved vehicular external lighting system capable of operating with a low current draw and able to be simply integrated into an existing vehicle&#39;s electrical system or electronic alarm sequencer system. 
   It is another object of this invention to provide an improved emergency vehicle external lighting system capable of providing enhanced visual notification to drivers of vehicles approaching the emergency vehicle normally with respect to either side of the longitudinal centerline of the emergency vehicle. 
   It is a further object of this invention to provide a low cost, light weight, vehicular external lighting system that can be temporarily or permanently mounted on a vehicle and is not subject to mechanical failure that will affect the multi directional visibility. 
   It is still a further object of this invention to provide for a low profile, high visibility light emitting visual notification system that when not in use has a barely perceptible configuration as affixed to a vehicle. 
   It is yet a further object of this invention to provide an enhanced vehicular alert lighting system that has a three dimensional geometrical configuration that allows the light emitted to be seen from an approximate 135 degree horizontal viewing angle from either side of the longitudinal centerline of the emergency vehicle, and to be seen in vertical field of view that encompasses all possible situations. 
   The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements. Other objects, features and aspects of the present invention are discussed in greater detail below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is perspective view of an emergency vehicle with a hood mounted LED assembly; 
       FIG. 2  is a front side view of the door mounted LED strip; 
       FIG. 3  is a longitudinal cross sectional view of the door mounted LED strip showing the general arrangement of all components; 
       FIG. 4  is a longitudinal cross sectional view of the door mounted LED strip with internal microprocessor showing the general arrangement of all components; 
       FIG. 5  is a top view of the hood mounted LED assembly illustrating the directions of illumination, 
       FIG. 6  is a front view of the hood mounted LED assembly; 
       FIG. 7  is a side view of the hood mounted LED assembly; 
       FIG. 8  is a vertical cross section view of the hood mounted LED assembly; 
       FIG. 9  is a vertical cross section view of the alternate embodiment hood mounted LED assembly; 
       FIG. 10  is a partial cutaway of a vertical cross section view of the hood mounted LED assembly showing the microprocessor and current limiting resistor; 
       FIG. 11  is a bottom view of the hood mounted LED assembly; 
       FIG. 12A  illustrates the electrical circuit logic when the hood mounted LED assembly is used in conjunction with the vehicles existing sequencing unit; and 
       FIG. 12B  illustrates the electrical circuit logic when the hood mounted LED assembly with microprocessor is used as a stand alone unit; 
   

   DETAILED DESCRIPTION 
   There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. 
   In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting. 
   The following system for emergency vehicle lighting entails the simultaneous use of at least one of each of the hood mounted light emitting diode (LED) assemblies and the door mounted LED strips although use of either of these alone could be sufficient to accomplish the task of enhancing the visibility of the emergency vehicle to approaching vehicles. 
   Light emitting diodes were chosen because their light output can be varied, they have a long life cycle and low power draw, they are inexpensive and diminutive in size so that a plethora of diodes may be used in a small space enabling multiple redundancy, they are lightweight and most importantly they have a low RF electromagnetic emission thereby minimizing radio distortion. This lack of radio distortion is a critical requirement of police and emergency vehicles. Further, LEDS are available in various colors with intensities that can be varied. This allows the use of clear lenses rather than colored lenses on the devices. Thus in the event of a shattered lens the specific alert color will not be lost. (I.E. This depends upon the type of emergency vehicle i.e. red for police, yellow, amber for road crews etc.) 
     FIG. 1  illustrates a police vehicle  30  with a LED strip  2  mounted on the vehicle&#39;s door  32  and a LED assembly  50  mounted on the vehicle&#39;s hood  34 . 
     FIG. 2  illustrates a front view of the LED strip  2  showing two linear arrays of light emitting diodes (LEDS)  4  mounted directly onto LED strip circuit board  6  which is mechanically affixed directly above a linear base  8 . The lens top cover cannot be seen from this view. 
   Looking at  FIG. 3 , a longitudinal cross sectional view of the door mounted LED strip showing the general arrangement of all components, it can be seen that circuit board  6  has an array of LEDS  4  mounted on it&#39;s top surface  9  and in electrical connection with electrical connector  10  which is affixed on the bottom surface  11  of circuit board  6 . The circuit board  6  has standoff spacers  16  between it&#39;s bottom surface  11  and base  8  so as to maintain their generally parallel spacial relationship and provide an adequate spacing between circuit board  6  and base  8  for electrical component clearance and heat dissipation. Diffusing lens top cover  18  mechanically attaches to linear base  8  so as to encapsulate the circuit board  6 . There are small concave formations  20  on the inner surface of the lens top cover  18 . These formations  20  act in the reverse of a culminator and serve to diffuse and refract the emitted light out into a wide array of directions thereby enhancing the viewing angle of the LED strip  2 . There are orifices  23  formed through the base  8  through which electrical wires and mechanical fasteners  26  pass to facilitate mounting of the LED strip to the vehicle&#39;s door, quarter panels or pillars. 
   Looking at  FIG. 4 , a longitudinal cross sectional view of an alternate embodiment of the door mounted LED strip, it can be seen that circuit board  6  has a first microprocessor  12  and first current limiting resistor  14  which also is affixed on the bottom surface of circuit board  6  and in electrical connection with the power connector  10  and LEDS  4 . This alternate embodiment differs principally by the elimination of the first microprocessor  12  and by the location of the limiting resistor at a place other than on the circuit board  6 . The first microprocessor  12  is required only to give non-static visual effects to the LEDS  4  such as pulsing, sequenced stroboscopic movement, etc. Such would be the simplest case where the LEDS  4  were only turned on or off. Also, the top cover lens  18  is not smooth and has concave formations on it&#39;s inside surface. In the preferred embodiment mounting devices  24  project from the bottom side of base  8  these may be magnetic or adhesive strips, or resilient reinforcement strips with orifices there through to accommodate mechanical fasteners. In the alternate embodiment, direct mechanical attachment is via screw fasteners  26  that pass through screw orifices  23 . As is well known in the field, any combination of lens type, mounting methods and electric configuration may be used to form other alternate embodiments as would be required to meet the specific situation. The approximate dimensions of the LED strip  2  for use on a conventional  4  door police sedan is 2 inches wide, 12 inches long and ½ to 3 inches deep. The nominal depth is approximately 1 inch but varies depending upon the location of the limiting resistor  14  and microprocessor  12  as well as the lens cover  18  configuration and electrical connector  10  used. 
     FIGS. 5 ,  6 ,  7  and  8  showing a top, front, side and side cross sectional view of a hood mounted LED assembly  50 , when viewed together illustrate that LED assembly  50  is formed from the connection of five LED encrusted circuit boards angled at approximately 40 degrees (+/−20 degrees) with respect to the horizontal plane and secured into an eight sided, irregular, octahedron, three dimensional, geometrical configuration by top plate  52 , bottom plate  66  and rear plate  64 . It is to be noted that top plate  52  and bottom plate  66  have a two dimensional planar configuration as irregular, nonequilateral, nonequiangular, convex hexagons. The top plate  52  and bottom plate  66  have congruent corresponding contained angles but not congruent corresponding side lengths. The bottom plate  66  is simply a larger version of the top plate  52  wherein all interior angles and ratio of side lengths remain identical with those of the top plate. However the side lengths in the bottom plate  66  are larger than those of the top plate  52 . It is this difference that allows the angled placement of the LED circuit boards. This angled design of the circuit boards increases the vertical visibility of the assembly. 
   It is to be noted that because most car hoods are not truly flat, bottom plate  66  has a slight concavity in both two dimensional planar directions, front to back and side to side. This enables a more aesthetic appearance when installed. Lens cover  70  serves to diffuse the emitted light and seal the assembly from the elements and moisture. It may be clear or colored. 
   Front circuit board  54  is attached at proximate end  53  to right short circuit board  56  and at distal end  55  to left front circuit board  58 . Right long circuit board  60  is joined to right short circuit board  56 . Left long circuit board  62  is joined to left short circuit board  58 . Rear plate  64  is connected to right long circuit board  60  and left long circuit board  62 . Second mounting strips  68  are affixed to bottom plate  66 . Similar to LED strip  2  these strips  68  be magnetic or adhesive strips, or resilient reinforcement strips with orifices there through to accommodate mechanical fasteners. 
   Looking at  FIGS. 6 and 7  the angled disposition of the circuit boards with respect to the top plate  52  and bottom plate  66  can best be seen. Experimentation has shown that for the optimal vertical visibility, the contained angle between the bottom plate  66  and all circuit boards should be approximately 40 degrees (+/−20 degrees). 
   Although in the preferred embodiment right long circuit board  60  and left long circuit board  62  have a quadrilateral planar geometry, in an alternate embodiment as shown in  FIG. 9 , the geometry of these two circuit boards is triangular, thereby eliminating the need for rear plate  64 . In this alternate configuration top plate  52  would be joined along it&#39;s rear side to bottom plate  66  and the three dimensional geometric shape formed by the connection of by top plate  52 , bottom plate  66  and the circuit boards would be a seven sided, irregular heptahedron. This forms a sleek, wedge like configuration. The approximate dimensions of the LED assembly  50  for use on a conventional four door police sedan is 12 inches wide, 12 inches long and a depth that may vary from 1/16 inches up to 3 inches deep. 
     FIG. 10 , a partial cutaway of a cross sectional side view illustrates a second current limiting resistor  76  and a second microprocessor  78  on the front circuit board  54 . 
     FIG. 11  shows the location of typical mounting orifices  74  drilled through bottom plate  66  and Second mounting strips  68  so as to allow for the passing of mechanical fasteners and electrical wires. 
   It is to be noted that current limiting resistors must be used with LEDS so as to allow the LEDS to be powered with a current not to exceed a specific limit. These limiting resistors may incorporated onto the circuit board in some embodiments or into a remote location such as the vehicle&#39;s electrical alarm sequencing unit. These resistors may even be incorporated into the connector wires. The current and voltage in an LED are not linearly related and a change in voltage will not produce a proportional change in current. LEDs are semiconductors, or specifically, diodes wherein the current flowing in the LED is an exponential function of voltage across the LED. Because of this, a small change in voltage can produce a huge change in current and can damage the LED. A typical LED rating is 3.3V@20 mA and most LEDs reach peak brightness at a drive current of 20 mA. Powering a LED at a higher current will not produce substantial additional light but rather will cause the junction to dissipate the excess power as heat. Heating the junction will decrease the LED&#39;s useful life, and can reduce the output of the LED substantially. Heating it enough will cause catastrophic failure (producing a dark emitting diode). There are two rows of LED lights used on all or part of each of the five circuit boards, as experimentation has shown that this can produce the level of visual display required with a minimal current draw on the vehicle&#39;s electrical system. Depending upon the level of visual intensity desired more or less lights could be used as is well known in the art. 
   Although not necessary for operation, the microprocessor accomplishes selective illumination of individual or multiple LEDs to provide a plethora of visual effects. The processor may also adjust the power to the LED so as to change the LED&#39;s intensity for glowing effects. Without the use of a microprocessor the LEDS would be controlled to be on or off. Similar to the limiting resistors, the microprocessor may be remotely located, typically incorporated into the vehicle&#39;s electric alarm sequencer unit, although it would be the norm to have the microprocessor installed directly onto one of the circuit boards. 
     FIGS. 12  A and  12 B illustrate different methods of electrical operation of the hood mounted LED assembly and the strip LED. Basically, a manually operated logic module (which in a base unit could be as simple as an on/off switch) sends a signal to the microprocessor which switches on, switches off, or adjusts the electrical power to the LED strip or LED assembly individual LEDS in conjunction with the limiting resistor to accomplish the desired intensity and duration of illumination to achieve the desired visual effect. The logic module wiring may or may not also transmit the system power to the LED assembly and the strip LED. System power may be transmitted to the LED assembly and the strip LED by a separate electrical wire/s. 
     FIG. 12  A shows how the system components typically would integrate with an existing sequencer unit of an emergency vehicle. Here, all vehicle alerts such as siren  80 , vehicle lights  82  and auxiliary lights  84  are controlled by one master sequencer  86  located centrally within the vehicle. This sequencer  86  may incorporate a general timing module  88  that operates the integrated individual logic modules  90  for each alert either individually or in unison with another logic module to obtain a unique vehicle alert effect. The power distribution module  92  transmits power to the alerts and may or may not incorporate the current limiting resistance necessary for LED operation. 
     FIG. 12B  shows a typical stand alone operation of the system components in the absence of a vehicle sequencer unit. Power is supplied to both the LED strip  2  (and the LED assembly  50 ) and the associated logic module  90 . The logic module  90  for the LED strip  2  is manipulated by the vehicle operator to send a selected signal to the LED strip&#39;s microprocessor  12  (or the LED assembly&#39;s microprocessor  76 ). In this example the microprocessor  12  and current limiting resistors  14  are mounted directly on the circuit boards of the LED strip  2  or LED assembly  50 . Power is also provided to the LED strip through the electrical connector  10 . The microprocessor manipulates and delivers this power to the LEDS according to it&#39;s preprogrammed instructions according to the logic provided by the logic module  90 . This graves the desired visual effect to the LED unit  2 . As can be seen a microprocessor is not necessary for all alerts. 
   In usage, the emergency vehicle operator pilots the vehicle to its desired location and switches on the LED strip  2  or LED assembly  50  to obtain the desired visual indication through the individual logic module  90  for the LED strip  2  or LED assembly  50 , or through the vehicle&#39;s existing sequencer unit  86  into which the logic module  90  for the LED strip  2  or LED assembly  50  has been integrated. 
   As can be seen there are several interchangeable methods of mounting or lens configurations between the embodiments. The number of linear arrays may vary, limited mainly by the power capacity of the vehicle, however, testing has shown that two linear arrays provide an adequate visual alert. Although not illustrated, culminator cups or reflective plates may be placed about the LED arrays to project their emitted light in a more forwardly direction. Additional elements or configurations of existing elements used to enhance the emitted light or increase the strength of the units are well known in the art. Such elements include but are not restricted to parabolic reflectors, silicate glass lens covers, inverted parabolic lens covers, and rubber seals. Similarly, there are different electrical configurations that can be utilized dependent upon whether the operational logic and electrical resistance is provided from an external sequencer or by circuit board mounted elements. While the preferable method of mounting is via mechanical fasteners through orifices in the base, adhesive strips, glue, magnets, suction cups and panel clips may be substituted. 
   The above description will enable any person skilled in the art to make and use this invention. It also sets forth the best modes for carrying out this invention. There are numerous variations and modifications thereof that will also remain readily apparent to others skilled in the art, now that the general principles of the present invention have been disclosed. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.