Abstract:
A heads up display arrangement for a motor vehicle includes a wheel sensor sensing a speed of rotation of a wheel. A distance-sensing device senses a distance between the motor vehicle and an other vehicle that is in front of the motor vehicle relative to a direction of travel of the motor vehicle. A processor receives the sensed speed of rotation of the wheel and calculates dependent thereon a stopping distance of the motor vehicle. A heads up display presents an image indicative of both the calculated stopping distance of the motor vehicle and the sensed distance between the motor vehicle and the other vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/132,422 filed on Mar. 12, 2015, which the disclosure of which is hereby incorporated by reference in its entirety for all purposes. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The disclosure relates to a heads up display for a motor vehicle. 
       BACKGROUND OF THE INVENTION 
       [0003]    A heads up display in a motor vehicle typically displays only the vehicle speed. Thus, a heads up display is underutilized in terms of the information it may provide to a driver. 
       SUMMARY 
       [0004]    Disclosed herein is a heads up display (HUD) that provides a graphical and/or spatial indication of how much distance a first vehicle needs in order to come to a stop at its current speed relative to the distance to a second vehicle that the first vehicle is following. For example, the HUD may display a horizontal line indicating how much distance the first vehicle needs to stop during hard braking based on the first vehicle&#39;s current speed. Also displayed may be an indication of the position of the closest other vehicle (second vehicle) in front of the first vehicle relative to the first vehicle&#39;s required stopping distance. That is, the HUD may indicate whether the first vehicle has enough distance to stop and avoid hitting the second vehicle in front of the first vehicle in the event that the second vehicle in front comes to an immediate stop, as may be the result of an accident involving the second vehicle. The HUD may indicate how much more stopping distance is needed to avoid hitting the second vehicle in a hard braking scenario, or how much extra stopping distance is available to avoid hitting the second vehicle in a hard braking scenario. 
         [0005]    In one embodiment, the invention comprises a heads up display arrangement for a motor vehicle including a wheel sensor sensing a speed of rotation of a wheel. A distance-sensing device senses a distance between the motor vehicle and an other vehicle that is in front of the motor vehicle relative to a direction of travel of the motor vehicle. A processor receives the sensed speed of rotation of the wheel and calculates dependent thereon a stopping distance of the motor vehicle. A heads up display presents an image indicative of both the calculated stopping distance of the motor vehicle and the sensed distance between the motor vehicle and the other vehicle. 
         [0006]    In another embodiment, the invention comprises a method of operating a heads up display in a motor vehicle, including detecting a speed of rotation of a wheel of the motor vehicle. A distance between the motor vehicle and an other vehicle that is in front of the motor vehicle relative to a direction of travel of the motor vehicle is sensed. A stopping distance of the motor vehicle is calculated dependent upon the detected speed of rotation of the wheel. An image indicative of both the calculated stopping distance of the motor vehicle and the sensed distance between the motor vehicle and the other vehicle is presented on the heads up display. 
         [0007]    In yet another embodiment, the invention comprises a heads up display arrangement for a motor vehicle including means for sensing a speed of the motor vehicle. A distance-sensing device senses a distance between the motor vehicle and an other vehicle that is in front of the motor vehicle relative to a direction of travel of the motor vehicle. A processor receives the sensed speed of the motor vehicle and calculates dependent thereon a stopping distance of the motor vehicle. A display device presents an image indicative of both the calculated stopping distance of the motor vehicle and the sensed distance between the motor vehicle and the other vehicle. 
         [0008]    An advantage of the invention is that it may prevent a driver from getting too close to the car in front of him, and may thereby provide enough space for the driver&#39;s vehicle to come to a complete stop before hitting the car in front of the driver&#39;s vehicle. 
         [0009]    Although a forward looking radar could tell the driver the distance to the car in front of him and if he is too close to that car, the forward looking radar alone does not display the information to the driver and does not relate the distance to the car in front of him to the stopping distance required for his vehicle based on the vehicle&#39;s current speed. 
         [0010]    Another advantage of the invention is that it provides easily perceived graphical and/or spatial information that enables the driver to judge for himself whether he is allowing enough stopping distance between him and the car in front of him. 
         [0011]    Yet another advantage is that the weight of the vehicle may be taken into account in calculating the stopping distance. For example, the manufactured weight of the vehicle, which may be known when the inventive system is installed and initialized, may be entered into the inventive system and taken into account in calculating the stopping distance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A better understanding of the present invention will be had upon reference to the following description in conjunction with the accompanying drawings. 
           [0013]      FIG. 1  is a block diagram of one example embodiment of a heads up display system of the present invention. 
           [0014]      FIG. 2  is a schematic view of an example embodiment of a heads up display of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]      FIG. 1  illustrates one embodiment of a heads up display arrangement  10  of the present invention including a vehicle  11  having a body side  12 , a heads up display (HUD) module  14  having a processor  15 , a windshield  16 , a wheel  18 , a wheel sensor  20 , a radar device  22 , a central processor  40 , a global positioning system  42 , a brake sensor  44 , an ambient outside temperature sensor  46 , a moisture sensor  48 , a traction sensor  50 , and an ambient light sensor  52 . The vehicle  11  generally travels in a forward direction  24 . 
         [0016]    During use, as the vehicle  11  travels in direction  24 , radar device  22  determines a distance  26  between the vehicle  11  and a second vehicle  28  that vehicle  11  is following. Radar device  22  may communicate the calculated distance  26  to HUD module  14 . Simultaneously with the operation of radar device  22 , wheel sensor  20  may sense the speed of rotation of wheel  18  and may calculate therefrom a stopping distance in which vehicle  11  would come to a stop in the event that the driver of vehicle  11  applies the brakes of vehicle  11  as hard as possible. Wheel sensor  20  may include a processor  21  to perform such calculations. The driver may apply the brakes as hard as possible, for example, in response to seeing second vehicle  28  de-accelerate quickly, come to a stop, and/or be involved in a collision. Wheel sensor  20  may communicate this calculated stopping distance to HUD module  14 . Alternatively, wheel sensor  20  may communicate only the sensed speed of rotation of wheel  18  to HUD  14 , and processor  15  of HUD  14  may calculate the stopping distance. The stopping distance may be calculated dependent upon the weight of vehicle  11  as manufactured and/or upon signals from ambient outside temperature sensor  46 , moisture sensor  48 , traction sensor  50 , and/or ambient light sensor  52 . 
         [0017]    In response to receiving distance  26  from radar device  22  and the stopping distance from wheel sensor  20 , HUD module  14  may project a display onto windshield  16 , an example of which is depicted in  FIG. 2 . The display may include a horizontal line  30  the length of which is proportional to the calculated stopping distance. An indication  32  of the position of vehicle  11  at the beginning of the path that vehicle  11  travels while braking may also be provided. Near the opposite end of the path, the display may also include an indication  34  of the present position of the vehicle  28  that vehicle  11  is behind or following. Accordingly, the combination of the horizontal line  30  and the indication  34  of the position of vehicle  28  may inform the driver of vehicle  11  whether he would have enough space to come to a stop and avoid hitting vehicle  28  in the event that vehicle  28  came to an immediate stop. For example, a space  36  between horizontal line  30  and indication  34  of the position of vehicle  28  may indicate the extra distance that would be between vehicle  11  and vehicle  28  if the driver of vehicle  11  were to hit the brakes as hard as possible and come to a stop. Conversely, if there is overlap (e.g., at least partial alignment in vertical directions  38  of the display) between horizontal line  30  and indication  34  of the position of vehicle  28 , it may indicate the additional stopping distance that would be required in order to avoid vehicle  11  colliding with vehicle  28  in the event that the driver of vehicle  11  hits the brakes as hard as possible to thereby attempt to come to a stop before colliding with vehicle  28 . 
         [0018]    In some embodiments, wheel sensor  20  and/or HUD  14  may take into account current weather conditions and/or the driver&#39;s reaction time when calculating the length of line  30  that should be presented on the display projected onto windshield  16 . For example, vehicle  11  may include a temperature sensor and moisture sensor in order to determine whether it is currently raining or snowing, and perhaps to determine the intensity with which the rain or snow is coming down. Wheel sensor  20  and/or HUD  14  may take into account whether it is raining or snowing, and possibly the intensity of such precipitation, when calculating the length of line  30 . As another example, vehicle  11  may include a traction sensor to determine how slick the roadway is on which vehicle  11  is traveling. Wheel sensor  20  and/or HUD  14  may take into account the traction on the roadway when calculating the length of line  30 . As yet another example, wheel sensor  20  and/or HUD  14  may take into account a typical driver&#39;s reaction brake time (i.e., the time between the event that the driver sees and the time at which the driver applies the brakes), which may be approximately between 1.5 and 2.3 seconds. In one embodiment, HUD  14  tests and stores each individual driver&#39;s reaction brake time, and uses this tested and stored driver reaction brake time when calculating the length of line  30 . Another system within the vehicle may inform HUD  14  of which individual is currently driving vehicle, and such driver identification systems are known in the art. For example, the test of an individual driver&#39;s reaction brake time may include HUD  14  displaying a prompt on windshield  16  for the driver to apply the brakes, and measuring the elapsed time before the driver actually applies the brakes. As a further example, wheel sensor  20  and/or HUD  14  may take into account the level of ambient light or daylight outside the vehicle, as determined by a vehicle light sensor (e.g., similar to a sensor used to automatically turn on vehicle headlights) when estimating the driver&#39;s reaction brake time. For example, it may be assumed that the darker it is outside, the more difficult it may be for the driver to see an event calling for his braking, and thus increasing darkness may be assumed to increase the driver&#39;s reaction brake time, and thus increase the calculated length of line  30 . 
         [0019]    In another embodiment, the speed of the vehicle is determined by central processor  40  based on global position data received from GPS  42 . Central processor  40  also calculates the vehicle stopping distance based on the speed of the vehicle. HUD  14  presents the vehicle stopping distance as calculated by central processor  40 . 
         [0020]    In another embodiment, the vehicle stopping distance is calculated based, at least in part, on empirical data collected on the current trip. The stopping distance may be dependent upon the weight of the passengers and truck contents, both of which may vary from trip to trip, so more accurate stopping distances may be obtained by considering the empirical data. Brake sensor  44  may detect the timing and magnitude of instances of braking, and the resulting decrease in speed of vehicle  11  may be determined based on data from GPS  42 . 
         [0021]    The invention has been described herein as presenting the image on a head up display. However, it is within the scope of the invention to present the image on any in-vehicle display, such as a display on a dashboard of the vehicle. 
         [0022]    The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom for modifications can be made by those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention.