| 摘要 |
PROBLEM TO BE SOLVED: To reduce computation load on a navigation system and acquire and display maps and guidance route information from an external device at an appropriate timing according to a vehicle speed. SOLUTION: The navigation system NAV previously acquires both the next map information requisition time and an identifier of map information from a server SEV, and transmits the map identifier and the location of one's own vehicle to the server when present time reaches the map information requisition time. The server downloads map information of the map identifier to the navigation system, computes a travel speed on the basis of the location of one's own vehicle, determines the next map information requisition time on the basis of the travel speed, and transmits the map information requisition time and an identifier of the next map information to the navigation system. The navigation system displays maps on a display screen on the basis of the map information acquired from the server, acquires the map information requisition time and the identifier of the next map information, and repeats the above-mentioned operations. COPYRIGHT: (C)2005,JPO&NCIPI |
