A position display instrument for light spot display on a map of the position of vehicles, in particular aircraft or helicopters. The instrument comprises a flat map holder for accommodating and holding map sheets in an exact position, a light transmitter located below the map holder for producing a light spot on the map sheet and movable in two coordinates by positioning means, a microcomputer to which the grid coordinates of the vehicle position are applied from a navigational computer and by which the positioning means are controlled, a memory for storing map data, said memory cooperating with the microcomputer, and display means which is connected to the microcomputer and by which the map sheet or map field required for the respective grid coordinates is displayed.

The present invention relates to a method and apparatus for enabling a traveler to determine the correct route from his present location to a desired destination in a city. To this end, the traveler enters information identifying his desired destination into an information station located at his present location. The information station compares the entered information with information identifying all the streets in the city and dividing the city into adjacent zones. As a result of the comparison, the information station determines the zone in which the desired destination is located. A map corresponding to the identified zone is then provided to the traveler. The map contains both the map of the streets in that zone and information on how to reach the zone from the present location. The traveler then proceeds to the desired destination, using boards arranged at street intersections. The boards contain information identifying each street corner and information concerning surrounding corners and may also include other data such as advertising.

A drive guide system for guiding a motor vehicle from a start point to a destination point by displaying a travel locus of the motor vehicle on a map is disclosed. A drive route map from the start point to the destination point is divided into a plurality of sections and they are stored in a memory. When a position of the motor vehicle reaches or approaches an outline of the map section displayed on a display screen, the drive route map section on the display screen is switched to the one corresponding to the direction of travel to be followed by the motor vehicle in accordance with a current azimuth of travel of the motor vehicle.

To eliminate the harmful influence of drift when integrating a sensor signal, the sensor signal is integrated from a time point a first predetermined time period before the sensor signal level becomes higher than the perdetermined signal level to a time point a second predetermined time period after the sensor signal level becomes lower than the predetermined signal level.

A navigator for use aboard a vehicle includes means for detecting the running distance of the vehicle, means for detecting the angle of the advancing direction of the vehicle with reference to terrestrial magnetism, arithmetic operational means for calculating the coordinates of the position of the vehicle in response to the detected running distance and angle of direction, a memory for storing data regarding the coordinates of the points of correction set at intersections of roads on a map corresponding to an area in which the vehicle is traveling, the distances between the points of correction, and the angles of roads branching from the points of correction with reference to terrestrial magnetism, a locating means for judging whether the vehicle is within a predetermined distance from a point of correction by comparing the coordinates of the present position of the vehicle with the coordinates of the points of correction stored in the memory, a means for judging whether the vehicle has made a turn, and a second arithmetic operational means for calculating the ratio of a reference distance between first and second reference points of correction to the measured distance between the first and second reference points of correction from the means for detecting the running distance, to obtain a compensation coefficient in determining the actual distance traveled by the vehicle.