Patent ID: 8036820

Claim:
A vehicle-mounted device that acquires traffic information for a vehicle, comprising: a traffic-information acquisition unit configured to automatically acquire traffic information from a first source of traffic information, said first source configured to provide traffic information via wireless communication; and a controller configured to: responsive to a request from a driver to set a destination for the vehicle, control the traffic-information acquisition unit to acquire traffic information from an external second source of traffic information, the second source having at least certain traffic information not available from the first source and configured to provide traffic information to the traffic-information acquisition unit; calculate a route to the destination using the traffic information from the first source and the second source; during guidance along the route, control the traffic-information acquisition unit to acquire current traffic information from the second source only if a value of at least one of a change between a current traffic condition along the route and a previous traffic condition along the route or between a previous traveling condition of the vehicle and a current traveling condition of the vehicle is larger than a predetermined threshold, the previous traffic condition based on previously-provided traffic information; and recalculate the route to the destination using at least one of the current traffic information, the current traveling condition of the vehicle or the current traffic condition along the route if the traffic-information acquisition unit acquires the current traffic information.