Inter-vehicle distance detecting device

An inter-vehicle distance detecting device wherein top and bottom image signals focused on top and bottom image sensors substantially by a pair of top and bottom optical systems, are compared and distances from a driving vehicle to preceding vehicles are measured by detecting deviation between the top and bottom images under a principle of trigonometry comprising:

• a display means for displaying the images of the preceding vehicles taken by either one of the top and bottom image sensors;
• an image-tracking means for setting a tracking window surrounding one of the images of the preceding vehicles and image-tracking said one of the images of the preceding vehicles by the tracking window;
• a first distance detecting means for calculating the distance from the driving vehicle to the one of the preceding vehicles by detecting the deviation between the corresponding top and bottom images wherein an image signal of the one of the preceding vehicles is a reference signal;
• a shadow window setting means for setting a plurality of shadow windows which are not displayed on a display image plane and which are totally different from the tracking window, at predetermined positions in the image taken by one of the top and bottom image sensors;
• a second distance detecting means for detecting distances from the driving vehicle to objects caught by the respective shadow windows by detecting the deviation between top and bottom corresponding image signals wherein image signals in the shadow windows are reference signals;
• a symmetry determining means for reading image signals in an arbitrary domain in the shadow windows and surroundings thereof and determining horizontal symmetry in the arbitrary domain;
• a detecting means for detecting a cut-in vehicle or lane change of the one of the preceding vehicles which is image-tracked by predicting movements of the preceding vehicles in front of the driving vehicle based on a distance information on the distances from the driving vehicle to the objects in the shadow windows caught by the second distance detecting means, an output of the symmetry determining means and an information provided by a calculation result of the image-tracking means on the one of the preceding vehicles which is image-tracked by the tracking window.