Patent Publication Number: US-6707393-B1

Title: Traffic signal light of enhanced visibility

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to traffic signal lights of the type generally positioned at road intersections, and more particularly concerns traffic signal lights which sequentially display green, amber and red lights. 
     2. Description of the Prior Art 
     Traffic signal lights are generally comprised of an enclosure that houses green, amber and red lights. The switching mechanism for controlling the activation of the lights may be located within the enclosure or at a remote site. In communities having considerable business, industrial or other commercial activity closely adjacent streets having substantial vehicular activity there is generally a significant amount of artifical light sources, particularly in the form of advertising signage. The advertising signs often employ red-colored neon illumination because the red color is most visibly distinctive. However, the red color of neon lights can often confuse a driver who is looking at the traffic signal light, especially under nighttime conditions. 
     The use of flashing lights to attract greater visual perception is commonplace. However, if the flashing principle were to be employed for enhancing the visual perception of traffic lights, there would still be confusion with extraneous lights employed for roadside advertising, and with warning lights such as those employed on brake lights, turn signal indicators and police and emergency vehicles. 
     It is accordingly an object of the present invention to provide a traffic signal light having improved visual recognizability. 
     It is another object of this invention to provide a traffic signal light as in the foregoing object having improved discernability with respect to competing light sources. 
     It is a further object of the present invention to provide an improved traffic signal light of the aforesaid nature which can be retrofitted into existing traffic light enclosures. 
     It is yet another object of this invention to provide a traffic signal light of the aforesaid nature which is of simple, durable construction and amenable to low cost manufacture. 
     These objects and other objects and advantages of the invention will be apparent from the following description. 
     SUMMARY OF THE INVENTION 
     The above and other beneficial objects and advantages are accomplished in accordance with the present invention by a traffic signal light comprised of green, amber and red primary lights disposed in a linear array within a protective enclosure, associated timing means for the sequential activation of said lights, and a source of electrical current for said activation, said traffic signal light further including: 
     a. a light of blue color adapted to interact with said primary red and green lights when said primary lights are activated, and 
     b. flasher means for causing said blue light to have a rapidly cycling intensity, whereby 
     c. the illumination added to said red light by said blue light causes said red light to have a visually perceived modified hue of rapidly varying intensity, and 
     d. the illumination added to said green light by said blue light causes said green light to have a visually perceived modified hue of rapidly varying intensity. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing forming a part of this specification and in which similar numerals of reference indicate corresponding parts in all the figures of the drawing: 
     FIG. 1 is a sectional side view of an embodiment of the traffic signal light of the present invention. 
     FIG. 2 is a front view thereof. 
     FIG. 3 is a schematic view of the control and activation system for the traffic light of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1-3, an embodiment of the traffic light signal  10  of the present invention is shown comprised of primary red, amber and green light assemblies  11 ,  12  and  13  respectively disposed in a linear array within protective enclosure  14 . Each light assembly is comprised of a colored filter  16  which is a weatherproof window of said enclosure, and associated incandescent light bulbs  17 ,  18  and  19  for said red, amber and green light assemblies, respectively. 
     Said array may be vertical or horizontal. The amber light is positioned between said red and green lights. When the array is oriented in a vertical position, the top light is red, middle light amber and lowermost light green. When the array is horizontally oriented, the left light is red, middle light amber, and right light green. The enclosure is conspicuously mounted adjacent a road intersection at an elevated location such as suspended from an overhead support, or mounted atop a vertical post. 
     Red light assembly  11  is comprised of a red colored filter  16 , and a light bulb  17  capable of producing light of a blue color. 
     Said blue color may be produced either by way of a colored glass which forms said bulb, or by way of a blue coating deposited upon the exterior glass portion of said bulb. Amber light assembly  12  is comprised of an amber colored filter  16 , and a light bulb  18  which emits white light. Green light assembly  13  is comprised of a green colored filter  16 , and a light bulb  19  which produces light of a blue color. Said colored filters may be Fresnel lenses which produce a directed beam of light. 
     Light bulbs  17 ,  18  and  19  are separately associated with electrical conductor wires  21 ,  22  and  23 , respectively, which extend away from enclosure  14  to engagement with on/off timer control box  25 . Flasher control boxes  26  are interposed within the conductive paths of wires  21  and  23  between enclosure  14  and timer control box  25 , and are adapted to produce rapid cycling of electrical power at a frequency between 3 and 12 cycles per second. Such frequency produces an attention-attracting flicker effect. In one manner of operation, the flasher may operate as an on-off switch. In an alternative manner of operation, the flasher may vary the strength of the electrical current passed on to the respective blue bulb between high and low values. In such latter manner of operation, preferably achieved by way of voltage variations, not only does the intensity of the emitted light vary, but the hue of the light also varies between a true red or green at the lower intensity levels to blue-red and blue-green at the higher intensity levels. This feature augments the attention-attracting effect and the distinctiveness of the traffic signal. A power source  27  supplies operating electrical current to timer control box  25 , said current then being routed through said conductor wires for the activation of said light bulbs. Power attenuating means in the form of transformers  30  may be associated with said conductor wires in order to modify the intensity of light emergent from each light assembly. In a preferred embodiment, the intensity of light emergent from said light assemblies is lower than the usual intensity of traffic signal lights. 
     The aforesaid components and their interaction enable commonplace traffic control signals to be retrofitted with blue light bulbs and associated flasher devices to facilitate operation by the usual timer control box. The retrofitted traffic control signal will produce a flashing red light having a very distinctive blue hue, and a flashing green light having a very distinctive blue hue. Such characteristics of the red and green lights cause the traffic signal light to have greater visibility and to be more distinguishable over extraneous interfering light sources. 
     While particular examples of the present invention have been shown and described, it is apparent that changes and modifications may be made therein without departing from the invention in its broadest aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention.