Abstract:
A signaling apparatus including a substantially transparent panel, a light emitting element attached to a surface of the transparent panel, substantially transparent means for delivering power to the light emitting elements, and means for selectively controlling energization of the light emitting elements. The signaling apparatus being substantially transparent when the light emitting elements are not in an energized state. The light emitting elements might be LEDS, organic LEDS (OLEDs), electroluminescent displays, LCDs, or incandescent bulbs. The signaling apparatus is adapted to be mounted on a vehicle window for providing selectable patterns, variable rate flashing, changeable colors, textual or graphic messages, strobe lights, and other types of displays. Cooling channels or a cooling plenum may be provided to allow higher power (e.g., high intensity) operation.

Description:
FIELD OF THE INVENTION 
   The invention pertains to emergency warning lights and, more particularly, to a system of transparent warning lights and/or a signaling or communicating device suitable for mounting in a window of an emergency vehicle without significantly occluding the otherwise transparent apparatus. 
   BACKGROUND OF THE INVENTION 
   Emergency vehicles such as police cars, fire response vehicles, ambulances, and the like require highly visible warning lights and signals to alert motorists of their presence. Warning lights visible to motorists from a reasonable distance allow drivers to safely make way for an overtaking emergency vehicle. Many emergency vehicles have large glass windshields and/or rear windows. These surfaces offer ideal locations for emergency signals. Unfortunately, these advantageous surfaces have heretofore not been unutilized for such purposes because any warning signal device placed therein has significantly limited visibility of the driver of the emergency vehicle. It would be advantageous, therefore, to have an emergency signaling system which could take advantage of highly visible placement positions such as a rear window or windshield of an emergency vehicle without significantly affecting the vehicle driver&#39;s visibility. 
   DISCUSSION OF THE RELATED ART 
   U.S. Pat. No. 4,574,269 for VEHICLE COMMUNICATOR, issued Mar. 4, 1986 to Gregory R. Miller, discloses a semi-transparent unit for selectively displaying a message adapted for mounting in the rear window of a vehicle. Mounting is by a frame adjustable to conform to the periphery of the vehicle&#39;s window to which the MILLER apparatus is attached. Ancillary brake and/or turn signals are optionally included on the rear window mounted apparatus. A remote programmer is used to select from among a plurality of predetermined messages. 
   U.S. Pat. No. 5,764,141 for MOTOR VEHICLE WARNING SIGNAL LIGHT ASSEMBLY, issued Jun. 9, 1998 to Jih-Cheng Chan, teaches an auxiliary stop light, emergency signal, and optional turn signal indicators for use in the rear window of a motor vehicle. 
   U.S. Pat. No. 6,270,236 for LED LIGHTING UNIT WITH TRANSPARENT CARRIER PANEL, issued Aug. 7, 2001 to Ingo Brussog, teaches a transparent carrier panel upon which are mounted surface mount LEDs electrically connected via indium-tin oxide (ITO) interconnections. 
   United States Pregrant Publication 2003/00165343 for STOP LAMP FOR VEHICLES, published upon application of Kiyohiro Akiyama teaches an LED array on a transparent substrate designed for direct mounting on the rear window of a vehicle using double back tape. 
   In contradistinction, the signaling apparatus of the present invention utilizes a readily removable, substantially transparent, universal signal and message display system primarily for use in rear windows or on windshields of emergency vehicles. Multiple color indicators, varying patterns and flash rates are provided. In addition, the normally transparent substrate supporting the light-emitting elements may selectively be made opaque to provide a contrasting background to the display as well as privacy as desired. 
   In addition, one embodiment of the invention utilizes a second substrate parallel to the first, thereby forming a plenum for circulating cooling air to allow high-powered (e.g., high intensity) operation of the signaling apparatus as is suitable for use in emergency vehicles. In still other embodiments of the invention, the display may be hinged so as to fold away from a window when not in use. This movement may be either manually or automatically performed. 
   None of these patents, either individually or in combination, is seen to teach or suggest the novel features of the emergency vehicle signaling apparatus of the present invention. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention there is provided a signaling apparatus adapted for mounting on a transparent substrate in or on a windshield, rear window, or other window of an emergency vehicle. The signaling apparatus uses an array of light-generating elements such as LEDs, organic LEDs (OLEDs), electroluminescent displays, LCD displays, or incandescent bulbs to create displays having selectable patterns, variable rate flashing, changeable colors, textual or graphic messages, strobe lights, and virtually any other imaginable type of display. The signaling apparatus may be permanently affixed to the window or, alternatively, may be removably attached. In still other embodiments, the signaling apparatus may be hinged and either manually or automatically moved into place for use. Cooling channels or a cooling plenum may be provided to allow high power (e.g., high intensity) operation. Optionally, the signaling apparatus may selectively be made opaque using existing electrochromic processes to provide a contrasting background to the display as well as privacy within the vehicle, at least through the window upon which the signaling apparatus is mounted. 
   It is therefore an object of the invention to provide a versatile signaling apparatus for use in emergency vehicles. 
   It is another object of the invention to provide a signaling apparatus selectively providing a wide range of warning lights, symbol, or textual message display. 
   It is a further object of the invention to provide a signaling apparatus which is substantially transparent at least when inactive, thereby allowing unobstructed vision through the apparatus. 
   It is a still further object of the invention to provide a signaling apparatus capable of displaying multiple colors. 
   It is yet another object of the invention to provide a signaling apparatus which may be permanently installed, removably installed, or hingedly installed in an emergency vehicle&#39;s window. 
   It is an additional object of the invention to provide a signaling apparatus through which cooling air may be circulated to allow high power operation of the signaling apparatus. 
   It is a further object of the invention to provide a signaling apparatus that may selectively be made opaque upon application of a suitable electrical signal. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when considered in conjunction with the subsequent detailed description, in which: 
       FIG. 1  is a schematic plan view of an embodiment of the signaling apparatus of the invention; 
       FIG. 2   a  is a schematic, cross-sectional view of a portion of the signaling apparatus of  FIG. 1 ; 
       FIG. 2   b  is a schematic, cross-sectional view of a portion of an alternate embodiment of a signaling apparatus of the invention; 
       FIG. 2   c  is a schematic, cross-sectional view of the signaling apparatus of  FIG. 2   a  having an added electrochromic layer; 
       FIG. 2   d  is a schematic, cross-sectional view of the alternate embodiment of a signaling apparatus of  FIG. 2   b  with an added electrochromic layer; 
       FIG. 3  is a diagrammatic, schematic view of a cooling system suitable for use with the signaling apparatus of  FIGS. 2   b  and  2   d;    
       FIG. 4   a  is a side, elevational view showing a first embodiment of a mounting arrangement of the signaling apparatus of  FIG. 1 ; 
       FIG. 4   b  is a side, elevational showing a second embodiment of a mounting arrangement of the signaling apparatus of  FIG. 1 ; 
       FIG. 4   c  is a side, elevational showing a third embodiment of a mounting arrangement of the signaling apparatus of  FIG. 1 ; and 
       FIG. 5  is a schematic block diagram of a controller suitable for use with the signaling apparatus of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present invention provides a substantially transparent emergency vehicle signaling apparatus (EVSA) for use in an emergency vehicle such as a police car, ambulance, fire truck, rescue vehicle, or the like. When not in use (i.e., not turned on), the EVSA allows unobstructed vision through the unit and may, therefore, be permanently affixed in or to a windshield or rear window of a vehicle without creating a safety hazard. 
   Referring first to  FIG. 1 , there is shown a schematic plan view of an EVSA  102  in accordance with the invention, shown mounted in a vehicle window  104 . A plurality of light-emitting elements  106 , shown schematically as circles, are disposed in a central region of EVSA  102 . It will be recognized that, depending upon the usage of EVSA  102 , the pattern of light-emitting elements  106  may vary. In some applications, light-emitting elements  106  may be disposed substantially in peripheral regions of EVSA  102 . In other applications, the EVSA  102  may be capable of multi-line, full text messages, a fairly dense, uniform array of light-emitting elements  106  will be required. For applications wherein EVSA  102  will be required to display only a limited number of predetermined symbols, the array of light-emitting elements  106  may be smaller, sparse or both smaller and sparse. Consequently, the EVSA  102  of the present invention is not considered limited to any particular arrangement of light-emitting elements  106  upon its face, but rather is seen to encompass all possible arrangements of light-emitting elements  106 . 
   It will also be recognized that a wide variety of different known devices may be used to implement light-emitting elements  106 . These include, but are not limited to LEDs, organic LEDs (OLEDs), electroluminescent devices, and incandescent lamps, either directly disposed on the surface of EVSA  102  or located remotely therefrom and connected to the surface by optical fibers or the like. It will be recognized that multiple types of light-emitting elements may be used to provide a wider range of display possibilities. Multi-color LEDs, for example, may be used as light-emitting elements  106  so that, by proper application of voltage, or through other control means, EVSA  102  may selectively display different colors. Alternatively, light-emitting elements  106  may be formed from groups of LEDs or other light-emitting devices each having different primary colors, analogous to sub-pixels in LED-based flat-panel displays. Using such a technique, EVSA  102  could be made to display full color images in a manner similar to a multi-color scoreboard. 
   EVSA  102 , as depicted in  FIG. 1 , has a border between the edges thereof and a frame region  110  of window  104 . While EVSA  102  may be sized and positioned as shown, more likely EVSA  102  will extend substantially completely to the edge (i.e., to a point adjacent the frame region  110 ) of window  104 . For permanent attachment, a double back tape, not shown, or similar adhesive system may be used to secure EVSA  102  to window  104 . Other fastening methods, not shown, such as brackets mounting the EVSA  102  to a rear deck of a vehicle, bracket mounting EVSA  102  to the ceiling of a vehicle, etc., none of which are shown, may also be used and will be described in more detail hereinbelow. 
   Electrical connections  108  connect either individual ones or groups of light-emitting elements  106  to external circuitry, not shown, from one or more edges of EVSA  102 . Electrical connection  108  may be implemented using fine, discrete wires, not shown, or by using conductive lines, not shown, formed from a conductive, transparent material such as indium-tin oxide (ITO) as is well known to designers of flat panel displays and other similar devices. The ITO conductor approach is preferable because the conductors may be screen printed or otherwise disposed on the substrate, not shown, of EVSA  102 . Fine wires would require much more sophisticated assembly techniques and, depending upon the required current, may be so large in diameter as to significantly reduce the overall transparency of EVSA  102 . 
   As described in detail hereinbelow, electrical connections  108  may be made to either individual ones or groups of light-emitting elements  106  as is required for a specific implementation of EVSA  102 . Matrix addressing techniques, wherein individual rows and columns of light-emitting elements are commonly connected to row and column driver lines, may be used. When such matrix addressing techniques are used, a particular light-emitting element  106  is energized by applying a voltage or other signal to both the associated row and associated column driver line for that particular light-emitting element. Such a row and column drive technique is commonly used to address individual pixels and sub-pixels in flat-panel displays. 
   Referring now to  FIG. 2   a , there is shown a schematic, edge, cross-sectional view of a portion of the EVSA  102  of  FIG. 1 , generally at reference number  120 . As may be seen, EVSA  102  comprises a single, substantially transparent substrate  122  upon which are disposed light-emitting elements  106  and electrical connections  108 . Vehicle window  104  is shown in phantom to indicate the relationship of EVSA  102  thereto. Mounting devices  124  are shown disposed between a front surface of EVSA  102  and vehicle window  104 . Mounting devices  124  may be a double back adhesive device well known to those of skill in the art. 
   Referring now also to  FIG. 2   b , there is shown a schematic, edge, cross-sectional view of an alternate embodiment of the EVSA  102  of  FIG. 1 , generally at reference number  140 . In addition to substrate  122 , a second, substantially transparent substrate  142  is disposed in a spaced-apart relationship to first substrate  122 . Spacers  146  are used to maintain a predetermined spaced apart relationship, and/or secure substrates  122 ,  142  to one another. The space  144  between substrates  122 ,  142  forms a plenum through which cooling air, not shown, may be circulated. By applying cooling air directly to light-emitting elements  106 , the light-emitting elements  106  may be operated reliably at a higher intensity than were they not cooled. Air may be supplied by a fan or blower  160  ( FIG. 3 ) at ambient temperature. For more extreme operation (i.e., higher intensity), chilled air may also be supplied. Either compressor-based, traditional refrigeration, or electrical cooling using Peltier devices, not shown, or the like may be used. 
   Referring now also to  FIGS. 2   c  and  2   d , there are shown schematic, cross-sectional diagrams of the embodiments of EVSA  102  of  FIGS. 2   a  and  2   b , respectively, but an eletrochromic layer  148  has been added. Electrochromic layer  148  is disposed behind light-emitting elements  106  in the embodiment of  FIG. 2   c . In an alternate arrangement, not shown, electrochromic film  148  may be disposed on a rear surface of substrate  122  and light-emitting elements  106  may penetrate elctrochromic film  148 . Electrochromic layer  148  is disposed on substrate  142  in the embodiment of  FIG. 2   d . Electrochromic devices such as optically switchable glass (i.e., “smart” windows) are well known and will not be described further hereinbelow. Application of a voltage or other signal to an electrochromic layer  148  causes that layer  148  to change from a transparent state to an opaque state. Some electrochromic devices may be controlled to provide a substantially continuous range of light blocking between transparent and opaque. 
   Referring now to  FIG. 3 , there is shown a diagrammatic representation of one method for accomplishing cooling of EVSA  102 . In the embodiments of  FIGS. 2   b  and  2   d , space or plenum  144  allows cooling air to contact light-emitting elements  106 . Cooling air may be supplied to a bottom edge of EVSA  102  by a plenum  150  attached thereto. Assuming that the vertical edges of EVSA  102  are sealed with a panel  152 , air forced into plenum  150  from supply duct  158  flows across the light-emitting elements  106  and exits the top of EVSA  102  through a grill  154  in the direction indicated by arrows  156 . In alternate embodiments, air may be supplied to one edge of EVSA  102  and exit through an opposite edge. It will be recognized by those skilled in the art that many other implementations may be provided to cool light-emitting elements  106 . The invention in not considered limited to the embodiment chosen for purposes of disclosure. 
   A supply duct  158  may be connected to a fan or blower  160  which is, in turn, supplied air by intake  162 . Fan or blower  160  may be controlled by a temperature sensor  164  located on or in EVSA  102 . Either an on/off control or a continuous control of air flow may be provided by temperature sensor  164  in cooperation with appropriate control circuitry, not shown, operatively connected to fan or blower  160  and temperature sensor  164 . 
   In alternate embodiments, cooled air may be supplied to supply duct  158  from the vehicle&#39;s cooling and ventilating system by means of a suitable adapter. In yet other embodiments, air intake  162  may be located outside the vehicle. In still other embodiments, air discharged from grill  154  may be conveyed outside the vehicle by another plenum, not shown, and suitable ducts. 
   Referring now to  FIGS. 4   a ,  4   b , and  4   c , there are shown schematic representations of the embodiments for mounting EVSA  102  to a vehicle. In  FIG. 4   a , one or more fixed brackets  402 , rigidly secures to EVSA  102 , are used to secure EVSA  102  to the vehicle using fasteners, not shown. 
   In  FIG. 4   b , top bracket  402  is replaced by a hinge  404 . The use of hinge  404  allows EVSA  102  to be manually moved along a path defined by arrow  406  for storage when not in use. It will be recognized that, alternatively, hinge  404  could be placed on a lower edge of EVSA  102  thus allowing EVSA  102  to fold downwardly as well as upwardly. 
   In  FIG. 4   c , hinge  404  ( FIG. 4   b ) is replaced by an electro-mechanical actuator  408  which, in response to a signal, not shown, automatically folds EVSA  102  upwardly. Electro-mechanical actuator  408  is shown schematically. It will be recognized that a wide variety of electrical, pneumatic, or hydraulic devices may be used to accomplish the intended function of electro-mechanical actuator  408 . Consequently, the invention in not considered limited to any particular electro-mechanical actuator but is seen to encompass any mechanism capable of moving EVSA  102 . 
   Referring now to  FIG. 5 , there is shown a controller  500  which controls all aspects of the display provided on EVSA  102 . A light-emitting device controller  502  is connected to EVSA  102  by a cable  504 . Connectors, not shown, may be provided at controller  500  and/or EVSA  102 . A keyboard  508  for providing textual input is connected to light-emitting device controller  502 . A selector panel  506  is likewise connected to light-emitting device controller  502 . In addition, a radio receiver  510  is connected to light-emitting device controller  502 . Receiver  510  is adapted to optionally receive control input from two possible sources. First, a local remote control  514  designed for short range communication with controller  500  is provided. Alternatively, control may be provided from a remote location  516 , such control being broadcast from transmission tower  518 , for example. 
   Light-emitting device controller  502 , upon input from keyboard  508 , selector panel  506 , or remotely generated input from receiver  510 , translates input commands into actuation signals for the plurality of light-emitting devices  106  ( FIG. 1 ). Text, symbols (either stationary or animated), flashing lights, changing colors, strobe, scrolling speed, flash rate and/or duration are a few of the parameters of EVSA  102  that are controlled by controller  500 . Control of electrochromic device  148  ( FIGS. 2   c ,  2   d ) may also be exercised by controller  500 . It will be recognized that controller  500  is disclosed as a generic device and is enabled to provide any and all control necessary to control the display from EVSA  102 . Exact circuitry for implementing any of the possible features is well known to those skilled in the art and is not described further herein. 
   Since other modifications are changes varied to fit particular operating conditions and environments or designs will be apparent to those skilled in the art, the invention is not considered limited to the examples chosen for purposes of disclosure, and covers changes and modifications which do not constitute departures from the true scope of this invention. 
   Having thus described the invention, what is desired to be protected by letters patents is presented in the subsequently appended claims.