Abstract:
A safety light for a vehicle is provided. The safety light includes a housing defining a retaining space. The housing is mountable to the vehicle proximate the rear end thereof. The safety light further includes a light source supported within the retaining space of the housing such that the light source projects a visual line of reference from the housing and onto a roadway on which the vehicle is traveling substantially coextensive to the rear end of the vehicle and perpendicular to the direction of travel of the vehicle so that the driver of the vehicle is able to determine the position of an adjacent obstacle relative to the rear end of the vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Serial No. 60/143,966, filed Jul. 15, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to lights, and more particularly, but not by way of limitation, to a safety light for projecting a light beam onto the roadway adjacent to a vehicle to provide a visual line of reference. 
     2. Brief Description of the Related Art 
     Devices which aid a driver in viewing regions surrounding a car or truck are well known in the art. More specifically, automobile manufacturers equip vehicles with features such as side and rear view mirrors to allow drivers to view other vehicles which are located beside or behind their vehicle. While side view and rear view mirrors are helpful for viewing nearby vehicles, it is nevertheless difficult for drivers to judge the distance of their vehicles from another vehicle by only looking into the mirror. As such, drivers are often unsure whether it is safe to change lanes. This problem is increased several fold when the vehicle being driven is a truck having a long tractor trailer attached thereto. This depth perception problem is further compounded at night. Therefore, a need exists for a device for projecting a light beam onto the roadway adjacent to a vehicle to provide a visual line of reference. It is to such a device that the present invention is directed. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an apparatus for attaching to the rear of a trailer or long vehicle for projecting a visual line of reference onto the surface of the road at the rear end of a vehicle. Broadly, the apparatus includes a housing, at least one light source, and a light source mount assembly. 
     The housing is provided with a top end, a bottom end, a first side, and a second side defining a retaining space. The light source is mounted in the retaining space of the protective housing by the light source mount assembly such that the light source projects a visual line of reference from the housing and onto the surface of the road substantially coextensive to the rear end of the vehicle and perpendicular to the direction of travel of the vehicle so that the driver of the vehicle is able to determine the position of an adjacent obstacle relative to the rear end of the vehicle. 
     This line of reference should be beneficial in reducing accidents caused by lane changes. Other features and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a perspective view of an apparatus constructed in accordance with the present invention. 
     FIG. 2 is a diagram of an electronic circuit of the apparatus. 
     FIG. 3 is a side elevational view of a light source mount assembly of the apparatus attached to a set of five light sources. 
     FIG. 4 is a side elevational view of a light source mounting bracket. 
     FIG. 5 is a rear view of a trailer diagrammatically illustrating the apparatus of the present invention attached to the rear end of a trailer and projecting a visual line of reference onto a portion of the roadway on which the trailer is traveling. 
     FIG. 6 is a top, diagrammatic view a trailer and an automobile illustrating the apparatus of the present invention attached to the rear end of a trailer and projecting a visual line of reference onto a portion of the roadway on which the trailer is traveling. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and more particularly to FIG. 1, shown therein is an apparatus  10  constructed in accordance with the present invention. The apparatus  10  is attachable to the rear end of a trailer or vehicle for projecting a beam of light onto a roadway on which the vehicle is traveling substantially coextensive to the rear end of the trailer or vehicle substantially perpendicular to the direction of travel of the vehicle to provide a visual line of reference. The apparatus  10  includes a housing  12 , at least one light source  14 , and a light source mount assembly  16 . 
     The housing  12  has a top end  20 , a bottom end  22 , a first side  24 , and a second side  26  defining a retaining space  28 . The retaining space  28  extends through the housing  12  from an open front side  30  to an open back side  32 . The light sources  14  are mounted in the retaining space  28  of the housing  12  by the light source mount assembly  16 . As shown in FIG. 1, five light sources  14  are mounted in the retaining space  28  of the housing  12 . A suitable light source is a laser pointer, which produces a focused beam of light rather than a diffusing beam of light. The use of the light sources  14  will form a line of spots or a dotted line of reference  34  (FIG. 5) across the roadway. 
     A beam of light  36  (shown in FIGS. 5 and 6) is emitted from each of the light sources  14  (FIG.  1 ). Each beam of light  36  must be bright enough for the driver to see the line of reference  34  clearly in the rear or side view mirror. In addition, the beams of light  36  must be of such intensity that if inadvertently shined directly into another driver&#39;s eyes at a short distance, the beams of light  36  will not cause any temporary blindness or affect visual acuity. The beams of light  36  may be clear or colored; the color of the beams of light  36  will affect the brightness of the line of reference  34  and thus the visibility of the line of reference  34 . Desirably, a wavelength of 635 nm will be emitted from the light sources  14 . 
     Each light source  14  desirably has an output power of 3.5 mW, runs on a 12 volt battery and needs 50 to 120 mA of current. In addition, each light source  14  is desirably operational at temperatures ranging from −18 to 104 degrees F, while able to be safely stored at a range of −72 to 185 degrees F. 
     While the apparatus  10  has been specifically described above as including a plurality of light sources, it should be understood that the use of a single light source which produces a single beam of light is contemplated by the present invention. For example, the light source can be a single bulb which produces a single diffusing beam of light. A lens or a shade with a vertically oriented slot can be used to focus the beam of light onto the roadway so as to project a visual line of reference which extends substantially coextensive from the rear end of the vehicle and substantially perpendicular to the direction of travel of the vehicle. 
     Referring now to FIG. 2, an example of a suitable electronic circuit  38  for operating the apparatus  10  is shown. The electronic circuit  38  is connected to a trailer&#39;s turning signal light circuit  40 . The trailer&#39;s turning signal light circuit  40  is used by the apparatus  10  as a control, while a tail light circuit (not shown) acts as the power supply. A switch  42  in the electronic circuit  38  senses a trailer&#39;s turning signal and connects or disconnects the power to the apparatus  10  depending on whether the trailer&#39;s turning signal is on or off. Therefore, the light sources  14  of the apparatus  10  are only turned on when the trailer&#39;s taillights are on. This type of electronic circuit  38  provides voltage protection to the apparatus  10 . 
     It will be understood that in other embodiments contemplated by this invention, the design of the electronic circuit as well as its components may be changed. 
     Referring now to FIGS. 1,  3  and  4 , the light source mounting assembly  16  includes a light source mounting bracket  44 , a back cover plate  46 , and a mounting clamp  48 . The light source mounting bracket  44  is a substantially U-shaped plate member having a plurality of openings  50 ,  52 ,  54 ,  56  and  58  formed through one side thereof. The openings  50 ,  52 ,  54 ,  56  and  58  are sized to receive a corresponding one of the light sources  14 . As illustrated in FIG. 4, the openings  50 ,  52 ,  54 ,  56  and  58  are formed through the light source mounting bracket  44  at different angles. More specifically, the preferred light source angles in reference to a top  60  of the mounting bracket  44  are 0° for the light source mounted in opening  50  while the opening  52 - 58  are formed through the light source mounting bracket  44  at angles  59   a - 59   d , respectively. The angle  59   a  is approximately 2.5°, the angle  59   b  is approximately 6.2°, the angle  59   c  is approximately 11.9°, and the angle  59   d  is approximately 21.8°. 
     Ends  62  and  64  of the light source mounting bracket  44  are secured to one side  66  of the back cover plate  46  in a suitable manner, such as by welding. The back cover plate  46  is adapted to be secured to the back side  32  of the housing  12  so that the back cover plate  46  extends over the retaining space  28  of the housing  12  with the light source mounting bracket  44  disposed within the retaining space  28 . The back cover plate  46  further includes a mounting flange  68  having a pair of holes  70 ,  72 . The mounting flange  68  is adapted to be adjustably connected to the mounting clamp  48 . 
     As shown in FIG. 1, the mounting clamp  48  includes a mounting plate  74 , which is attachable to a flat surface on the rear of a trailer or other vehicle, and a pair of parallel, spaced apart plates  76 ,  78 . Each of the plates  76  and  78  includes a hole  80  and  82 , respectively, which is alignable with the hole  70  of the mounting flange  68  and an elongated slot  84  and  86 , respectively, which is alignable with the hole  72  of the mounting flange  68 . The mounting flange  68  is securable to the mounting clamp  48  by inserting a suitable fastening member, such as a pin  87 , through the holes  80  and  82  of the mounting clamp  48  and the hole  70  of the mounting flange  68 . The mounting flange  68  is further secured to the mounting clamp  48  upon adjusting the angle of the mounting flange  68  relative to the mounting clamp  48  by inserting a suitable fastening member, such as a clamp  89 , through the slots  84  and  86  of the mounting clamp  48  and the hole  72  of the mounting flange  68 . 
     Referring again to FIGS. 5 and 6, in use, the apparatus  10  should be mounted on the vehicle in such a location so that the dotted line of reference  34  is substantially coextensive relative to the rear end of the vehicle. Desirably, installation of the apparatus  10  will require only a few screws or bolts, and the apparatus  10  can be mounted on several different types of trailers. Placement of the apparatus  10  should be as low as possible to prevent the vision of another driver being impaired by the beams of light  36 . Desirably, the apparatus  10  is mounted to a trailer  88  at a flat surface on a bottom side  90  at the rear end of the trailer  88 , which is typically from about 39 to about 43 inches above the ground. The apparatus  10  is designed to work best at this height, which provides an optimum mounting height so that the dotted line of reference  34  is approximately eight feet long beginning 3.75 feet from the edge of the trailer  88 . Since an interstate lane is 12 feet wide and the maximum legal width of a non-wide-load trailer is 8.5 feet, the dotted line of reference  34  should appear centered in the adjacent lane. 
     To produce the desired dotted line of reference  34  evenly spaced over the eight foot distance, the angles of the light sources  14  should be held constant, as any adjustment in angle will slightly distort the spacing of the laser dots on the roadway. However, adjustment of the angles should not be enough to reduce visibility of the dotted line of reference  34 . By way of example, at the optimum mounting height, the housing  12  may be mounted at an initial angle, θ 0 =15.2, and the angles of the light sources  14  will be adjusted by adding θ 0  to the preferred light source angles in reference to the top  60  of the mounting bracket  44 , as shown in FIG.  4 . Therefore, the light source angles will be, from top to bottom: θ 1 =15.2, θ 2 =17.7, θ 3 =21.4, θ 4 =27.1, θ 5 =38.0. 
     It will be appreciated that the placement of the apparatus on the trailer  88 , as well as the laser angles may be changed. Further, the apparatus  10  of the present invention can be used on both the passenger&#39;s side of the vehicle, as well as the driver&#39;s side of the vehicle. Finally, the apparatus  10  of the present invention can also be employed with passenger cars, vans, recreational vehicles, boats or any vehicle where a visual line of reference can be beneficial in safely operating the vehicle. 
     As shown in FIG. 6, once the dotted line of reference  34  is visible on the roadway in front of an obstacle, such as a passenger car  92  being passed, the driver of the trailer  88  will know that his vehicle has cleared the obstacle and can proceed to change lanes. This line of reference should be beneficial in reducing accidents resulting from lane changes. 
     From the above description, it is clear that the present invention is well adapted to carry out the objects and to attain the advantages mentioned herein as well as those inherent in the invention. While a presently preferred embodiments of the invention have been-described for purposes of this disclosure, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the spirit of the invention disclosed and claimed.