Navigation system with capability of instructing running direction

Claim 1

A navigation system for displaying, on a display screen, road map information and a running trace of a car superimposed thereon comprising: display means including a cathode ray tube for displaying road map information and information regarding the car running trace; at least one bearing sensor means for detecting the running direction of the car; running distance detector means for detecting the running distance of the car; and control means, connected to receive output signals from said bearing sensor means and said running distance detector means, for computing a current position of the car, for controlling car running information. such as the road map information, a running trace and a running bearing corresponding to the current position of the car, and for displaying the car running information on said cathode ray tube, said control means including: (a) external storage means for storing the road map information and the car running information; (b) a central control unit for controlling said external storage means, said computation of the current position of the car and said display of the road map information; and (c) means for instructing the driver as to the desired running direction; and wherein: said central control unit comprises means for setting specified areas centered on respective crossings of roads on said road map information stored in said external storage means, means for calculating a running position of the car in accordance with the output signals of said bearing sensor means and said running distance detector means, means for detecting the arrival of the car at an entrance of the specified area by comparing the calculated value of the running position with data indicating the boundary of the specified area, means for determining the angular difference between the current running direction of the car and a destination bearing at the entrance of the specified area in accordance with the output signal of said bearing sensor means at said entrance and information of the destination bearing stored in said external storage means, and means for controlling said running direction instructing means to indicate to the driver the desired running direction at a crossing in accordance with said determined angular difference.