Abstract:
A dock light warning system includes an exterior unit adapted to be mounted adjacent a loading dock door. The exterior unit is provided with a red light assembly for providing a narrow beam of red light focused on a driver&#39;s side exterior rearview mirror when the loading dock door is in the open position to warn a driver against moving the truck. A corresponding interior unit is provided with a red light assembly and a green light assembly to indicate the condition of the red light assembly and the green light assembly of the exterior unit. A photocell assembly is provided for sensing the position of the overhead door to control the switching of the red light assembly to the green light assembly and vice versa.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to a dock light warning system and more specifically to a red light/green light system mounted in a common housing mounted on the outer surface of the dock structure adjacent a dock door to advise a truck driver when it is safe to back up to a dock or depart from a dock. 
     Many systems have been utilized over the years to prevent the unauthorized movement of a truck toward and away from a loading dock to prevent injury to employees involved in the loading and unloading of the truck. Many of these systems have relied upon complicated, physical restraint structures which actually grip a portion of the truck or block the wheels of a truck to prevent the truck from unauthorized movement away from the loading dock. Such systems are extremely complicated and expensive to build and install and frequently can cause expensive damage to a truck. 
     Applicant&#39;s U.S. patent (U.S. Pat. No. 5,964,059) is directed to an extendible and retractable safety pole which is located in front of a truck when it is backed up to the loading dock. Thus, the truck driver will have a highly visible pole blocking his removal of the truck from the loading dock when it is in the extended position. When the loading or unloading operation of the truck is completed and the dock door is closed, the pole will automatically retract, thereby allowing the truck driver to leave. Although this system is simpler than the mechanical restraint systems, it is still somewhat expensive to install and maintain. 
     SUMMARY OF THE INVENTION 
     The present invention provides a warning system to truck drivers which is less complicated and less expensive than the prior art systems which still provides a very distinctive warning to a truck driver against moving his truck. 
     The present invention provides a dock light warning system wherein a red light and a green light are mounted in a common housing adjacent the door of the loading dock. When the door is closed, the green light will be on which provides a bright but diffuse green light which clearly indicates to a driver that it is safe to approach or depart from the loading dock. Once the truck is in position adjacent the loading dock in front of the door, the door of the loading dock may be opened. The opening of the door automatically changes the light from green to red. The red light is located at a height approximately equal to the average height of an outside rearview mirror on a truck adjacent the driver&#39;s side thereof. The red light emanates from the housing and provides a narrow, 5° beam spread, thereby concentrating the light directly onto the outside rearview mirror on the driver&#39;s side so as to reflect the bright red light into the face of the driver, thereby clearly warning the driver that the truck should not be moved. 
     The above and other objects, features and advantages of the present invention will be more apparent and more readily appreciated from the following detailed description of preferred exemplary embodiment of the present invention, taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a loading dock with the loading door open showing the location of the exterior unit of the red light/green light warning system according to the present invention. 
     FIG. 2 is an inside view of the loading door in the raised position showing the location of the interior unit of the warning system. 
     FIG. 3 is an exploded view of the exterior unit of the warning light system. 
     FIG. 4 is a top plan view of the exterior unit with the outer cover removed. 
     FIG. 5 is a front elevational view of the exterior unit with the front cover removed. 
     FIG. 6 is a vertical, sectional view of the exterior unit. 
     FIG. 7 is an exploded view of the interior unit of the dock light warning system. 
     FIG. 8 is a perspective view from the bottom front of the cover for the interior unit. 
     FIG. 9 is a circuit diagram for the dock light warning system. 
     FIG. 10 is a schematic view showing the red light beam in relation to the rearview mirrors of different size trucks. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The red light/green light warning unit  10  is shown in FIG. 1 as being mounted on the right hand side of a dock door opening  12  as viewed from the outside. A warning legend printed in reverse for readability in a rearview truck mirror is mounted above the warning unit  10  and reads “MOVE ON GREEN ONLY”. The loading dock is provided with conventional bumpers  16  and a conventional dock leveling platform  18 . The dock door  20  is usually an overhead type door which is shown in the open position in FIG.  1 . FIG. 2 is an interior view of the dock door opening with the interior unit  22  of the dock light warning system mounted to the left hand side of the door opening  12  at a location approximately opposite the exterior unit  10 . The overhead door  20 , which is only partially illustrated in FIG. 2, is guided for movement in tracks  24  and  26 , located at opposite sides of the door opening. A flexible dock light unit  28  may be mounted adjacent the interior unit  22 . The dock light is provided with a flexible neck  30  which enables the ideal positioning of the light  32  for illuminating the interior of a truck backed up to the dock door opening  12 . The operation of the lighting unit  28  is electrically controlled in coordination with the dock light warning system. An electric eye  34  is mounted beneath the interior unit  22  on a bracket  36  secured to the wall. The electric eye is aligned with an aperture  38  in the overhead door track  24  so as to detect when the door  20  is in the raised position and the lowered position. 
     The exterior unit  10  of the dock light warning system is shown in an exploded view in FIG.  3 . The exterior unit  10  is comprised of a support plate  40  adapted to be secured to the building wall and a light supporting plate  42  comprised of a substantially S-shaped metal plate secured at the top to the support plate  40  and at the bottom to a horizontal support plate  44  secured to and extending outwardly at right angles to the support plate  40 . The light support plate  42  is provided with two circular apertures  46  and  48  with a light baffle  50  protruding outwardly therefrom at right angles between the two apertures  46  and  48 . An L-shaped bracket  52  is adapted to be secured to the inner face of the light support plate  42  and a plurality of electrical control units  54  are adapted to be secured thereto. 
     A pair of lamp support brackets  56  and  58  are formed as thin boxes connected together by a pair of straps  60 . Each strap is provided with a hole for the reception of screws  62 , which extend therethrough into engagement with aligned holes  64  in the support plate  42 . The upper edge of the box  56  is provided with a pair of upstanding tabs  66  which are adapted to extend through corresponding slots  68  in the support plate  42 . A similar pair of tabs (not shown) protrude downwardly from the lower edge of the box  58  and are adapted to extend through the slots in the support plate  42 . Once the tabs are inserted through the corresponding slots, they may be bent upwardly or downwardly into engagement with the inner surface of the support plate  42  to secure the boxes  56  and  58  to the support plate  42  along with the screws  62 . A pair of thin profile halogen lamps are provided and are adapted to be disposed within the boxes  56  and  58 . The diameter of the halogen lamps is such that the outer circumferential edges of the lamps are secured between the boxes  56  and  58  and the outer surface of the support plate  42  surrounding the apertures  46  and  48 . The upper lamp  72  is a narrow, 5° beam spread 50 watt halogen lamp while the lower lamp  74  is a wide beam 50 watt halogen lamp. 
     A custom colored acrylic lens  80  is adapted to be secured to the outer surface of the box  56  by any suitable means over the circular opening  76 . The lens  80  is a custom acrylic lens having a reddish orange color, preferably ACRILEX 2128 red. The lens  80  does not diffuse light coming from the lamp  72  and the beam of the lamp  72  retains its 5° spread. A standard green lens  82  is adapted to be secured to the box  58  over the circular opening  78 . The lens  82  is used to diffuse the light from the wide beam lamp  74 . 
     Finally, a cover  84  is provided for the entire unit in the form of a rectilinear box having a pair of circular openings  86  and  88  in the front surface thereof in alignment with the circular apertures  76  and  78  in the boxes  56  and  58  and the circular apertures  46  and  48  in the support plate  42 . The cover  84  may be secured to the main support plate  40  by any suitable means such as screws or the like which allow for detachability. Thus the exterior unit  10  will have the red light disposed over the green light and the unit  10  is mounted on the building structure at a height approximately the average height of an exterior rearview mirror of a truck from the ground. 
     In order to focus the narrow 5° beam of red light on the driver&#39;s side exterior rearview mirror, the support plate  42  is disposed at a 2° angle relative to the main support plate  40  as best seen in FIG.  4 . This is necessary in view of the fact that the exterior unit  10  is mounted to one side of the door and accordingly, will be located to one side of a truck backed up to the dock. FIG. 10 is a schematic view of a 30 foot truck  90  and a 63 foot truck  92  showing their relationship relative to the exterior unit  10  of the warning light system. The 5° light beam  94  is angled by 2 degrees due to the 2 degree angle of the support plate  42  relative to the main support plate  40  so that an outer edge of the beam  94  will be disposed substantially parallel to the side of either size truck. Thus, the center of the beam will be in substantial alignment with the outside rearview mirror  96  of the 30 foot truck  90  as well as the outside mirror  98  of the longer 63 foot truck  92 . Thus, the high intensity red light beam will be focused on the driver&#39;s side outside rearview mirrors and will not provide any high intensity light on the outside passengers&#39; side mirrors of the truck at the next loading dock position. The diffuse green beam of light, which indicates that it is safe to back up to or leave the loading dock, will not interfere with the driver&#39;s rear vision. On the other hand, the high intensity red beam of light will be reflected off the outside driver&#39;s rearview mirror into the face of the driver so that he can not possibly ignore the warning that he should not move the truck under any circumstance. 
     FIG. 7 is an exploded view of the interior unit  22  of the dock light warning system. A main support bracket  100  is comprised of a substantially U-shaped sheet metal member having flanges  102  with apertures  104  for receiving mounting screws to secure the bracket  100  to the interior wall of the building structure. A tab  106  extends inwardly from the upper edge of the bracket  100  and is provided with a screw hole  108  for reception of the screw  110  which would extend through a corresponding aperture  11  in the cover  112  to secure the cover to the support bracket  100 . A bottom flange  114  is integral with and extends outwardly from the bracket  100  and is provided with apertures  118  to provide for wiring access. 
     A lamp support plate  116  is adapted to be secured to the bracket  100  in spaced parallel relation thereto by means of screws (not shown) extending through apertures  118  in the plate  116  and the bracket  100 . The screws will also extend through spacers  120 , which are located between the plate  116  of the bracket  100 . Four 120 volt lamps  122  are mounted on the plate  116  along with a 12 volt transformer for the lights in the external unit. The cover  112  is provided with a semi-cylindrical profile having two windows  124  and  126  extending from one side thereof, parallel to each other. The window  124  is provided with a red lens  125  and the window  126  is provided with a green lens  127 . Each of the lenses provides a 180° view so that the status of the warning system can readily be determined from many different locations within the building. As best seen in FIG. 8, a semi-circular divider plate  128  is provided between the openings  124  and  126  to provide a light baffle between the two upper lamps and the two lower lamps. When the upper lamps  122  are illuminated, a red light will emanate through the lens  125  which indicates that the red lamp of the outside unit is illuminated and the overhead door is in the open position. Likewise, when the two lower lamps  122  are illuminated, the lens  127  will provide a green light, indicating that the green light of the exterior unit is illuminated and the overhead door is closed. 
     A control circuit for the warning system is shown in FIG. 9. 120 volts is supplied from a source TB-1 to a 12 volt transformer T 1  through a switch SW 1  and a fuse F 1 . 120 vac is supplied to the lamps LP 1  and LP 2 , which correspond with upper lamps  122  and the lamps LP 3  and LP 4 , which correspond to the lower lamps  122  under the control of a relay D 3 . 
     The optional light may be connected to the lamps of the interior unit  22  such that the light unit  128  for lighting the interior of a truck will be energized when the overhead door  20  is in the open position. 12 vac is supplied to the outside lamps LP 5  and LP 6  which correspond to the lamp  72  and the lamp  74 , respectively. These lamps are under the control of the relay D 4 . The photocell assembly  34  controls the relays D 3  and D 4  through the transistors Q 1  and Q 2 , respectively. The photocell  34  is provided with 12 vdc through the rectifier D 2  and the regulator. The truck light warning system described above is substantially automatic inasmuch as the system will switch from the green light to the red light in both the interior and exterior units upon opening of the overhead dock door. The dock door would only be opened when a truck is backed up to the door with the brakes set and the engine shut off. The red warning light would be highly visible to the driver, which would clearly indicate to him that the truck should not be moved while the red light is illuminated. Thus, the dock light warning system according to the present invention provides a high degree of safety to dock workers who are in the process of loading or unloading a truck. 
     While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.