Map acquisition system, map acquisition unit, and navigation apparatus equipped with a map acquisition unit

Claim 2

A map acquisition system including, connected via a communication medium, a center unit and a map acquisition unit in a vehicle for obtaining from the center unit map data covering areas to a travel destination, the system comprising: center-side map storage means installed in the center unit and storing map data with different scales; present-position detecting means for detecting the present position of the vehicle; destination setting means for setting the travel destination of the vehicle; and deciding means for deciding, based on a detected present position, whether the vehicle has reached a map acquisition point individually set for said map data of each scale, wherein a map acquisition point where larger scale map data is obtained is set nearer to the destination so that the scale of map data obtained at a map acquisition point balances with the distance between this point and the destination, and the center unit sends, based on a decision of said deciding means, the map acquisition unit map data with a scale corresponding to a map acquisition point where the vehicle has reached, wherein said present-position detecting means is included in the map acquisition unit and said deciding means is included in the center unit and decides, based on present position data sent from the map acquisition unit, whether a vehicle has reached the map acquisition point.

Claim 3

A navigation apparatus for providing route guidance using map data covering areas to a destination, comprising: a present-position detecting section for detecting a present position; a map acquisition process section for obtaining map data from an outside source via a communication medium; and a guidance process section for providing route guidance using map data obtained by the map acquisition process section, wherein as the present position nears the destination, the scale of map data obtained by the map acquisition process section becomes larger, the guidance process section changes map data for route guidance to the larger scale map data which the map acquisition process section has obtained and provides route guidance using a tentative destination in the rough vicinity of said destination, said tentative destination being a predetermined typical point on a currently used route guidance map, and the map acquisition process section decides, based on the distance between the present position and said tentative destination, whether a vehicle has reached a point where larger scale map data than the map data then being used for route guidance should be obtained.

Claim 4

A navigation apparatus for providing route guidance using map data covering areas to a destination, comprising: a present-position detecting section for detecting a present position; a map acquisition process section for obtaining map data from an outside source via a communication medium; and a guidance process section for providing route guidance using map data obtained by the map acquisition process section, wherein as the present position nears the destination, the scale of map data obtained by the map acquisition process section becomes larger, the guidance process section changes map data for route guidance to the larger scale map data which the map acquisition process section has obtained and provides route guidance using a tentative destination in the rough vicinity of said destination, said tentative destination being a predetermined typical point on a currently used route guidance map, and the map acquisition process section decides, based on the distance between the present position and said tentative destination, whether a vehicle has reached a point where larger scale map data than the map data then being used for route guidance should be obtained.

Claim 5

A navigation apparatus for providing route guidance using map data covering areas to a destination, comprising: a present-position detecting section for detecting a present position; a map acquisition process section for obtaining map data from an outside source via a communication medium; and a guidance process section for providing route guidance using map data obtained by the map acquisition process section; address separating means for separating a destination address with hierarchical structure into address elements belonging to individual hierarchies, wherein, as the present position nears the destination, the scale of map data obtained by the map acquisition process section becomes larger, and the map acquisition process section obtains in turn a map corresponding to an address element belonging to a lower hierarchy, and wherein a map scale is set for each hierarchy of address elements so that a lower address element corresponds to a larger scale, wherein the guidance process section changes map data for route guidance to the larger scale map data which the map acquisition section has obtained and provides route guidance using a tentative destination in the rough vicinity of said destination, said tentative destination being a predetermined typical point on a currently used route guidance map, and when the present position nears the current tentative destination, the map acquisition process section obtains a map corresponding to an address element of the next lower hierarchy and usable for guidance to a tentative destination for said address element of the next lower hierarchy.

Claim 6

A navigation apparatus for providing route guidance using map data covering areas to a destination, comprising: a present-position detecting section for detecting a present position; a map acquisition process section for obtaining map data from an outside source via a communication medium; and a guidance process section for providing route guidance using map data obtained by the map acquisition process section; address separating means for separating a destination address with hierarchical structure into address elements belonging to individual hierarchies, wherein, as the present position nears the destination, the scale of map data obtained by the map acquisition process section becomes larger, and the map acquisition process section obtains in turn a map corresponding to an address element belonging to a lower hierarchy, and wherein a map scale is set for each hierarchy of address elements so that a lower address element corresponds to a larger scale, wherein the guidance process section changes map data for route guidance to the larger scale map data which the map acquisition section has obtained and provides route guidance using a tentative destination in the rough vicinity of said destination, said tentative destination being a predetermined typical point on a currently used route guidance map, and when the present position nears the current tentative destination, the map acquisition process section obtains a map corresponding to an address element of the next lower hierarchy and usable for guidance to a tentative destination for said address element of the next lower hierarchy.

Claim 7

A navigation apparatus according to claim 3, wherein, after a map corresponding to an address element of the lowest possible hierarchy is obtained, said guidance process section uses the map to provide route guidance to the actual destination.