Abstract: Travel guidance devices, methods, and programs acquire map data including a road network, a position of a vehicle, and a planned travel route of the vehicle. Based on the acquired information, the devices, methods, and programs determine whether there is a planned entry branch that the vehicle is projected to enter located ahead of the vehicle. When the planned entry branch is ahead of the vehicle, the devices, methods, and programs determine whether there is a no-lane-change zone between the vehicle and the planned entry branch. When the no-lane-change zone is located between the vehicle and the planned entry branch, the devices, methods, and programs set guidance content related to a lane change of the vehicle based on a position of the no-lane-change zone. The devices, methods, and programs generate guidance using the set guidance content and communicate the generated guidance to a user of the travel guidance device.

Abstract: Travel guidance devices, methods, and programs acquire map data including a road network, a position of a vehicle, and a planned travel route of the vehicle. Based on the acquired information, the devices, methods, and programs determine whether there is a planned entry branch that the vehicle is projected to enter located ahead of the vehicle. When the planned entry branch is ahead of the vehicle, the devices, methods, and programs determine whether there is a no-lane-change zone between the vehicle and the planned entry branch. When the no-lane-change zone is located between the vehicle and the planned entry branch, the devices, methods, and programs set guidance content related to a lane change of the vehicle based on a position of the no-lane-change zone. The devices, methods, and programs generate guidance using the set guidance content and communicate the generated guidance to a user of the travel guidance device.

Abstract: A navigation apparatus and method increase the upper limit for the number of times map data may be written into a portable storage medium. A CPU reads an initial radius and an additional radius increment from a ROM and repeatedly adds the additional radius increment to the initial radius to obtain, with each addition, a new calculated radius centered on coordinates of a central geographic point of a map data extracting-region. The map data for each secondary grid unit within the map data extracting-region is sequentially read out from a CD-ROM. Then, when the map data within the incrementally enlarged map data extracting-region exceeds the maximum storage capacity of the SD memory card, the CPU deducts the last added increment of radius from the calculated radius to obtain a map region to be stored. The CPU sequentially reads out from the CD-ROM the map data for each grid unit within the map region to be stored and sequentially writes the grid units of map data into the SD memory card.

Abstract: A navigation apparatus and method increase the upper limit for the number of times map data may be written into a portable storage medium. A CPU reads an initial radius and an additional radius increment from a ROM and repeatedly adds the additional radius increment to the initial radius to obtain, with each addition, a new calculated radius centered on coordinates of a central geographic point of a map data extracting-region. The map data for each secondary grid unit within the map data extracting-region is sequentially read out from a CD-ROM. Then, when the map data within the incrementally enlarged map data extracting-region exceeds the maximum storage capacity of the SD memory card, the CPU deducts the last added increment of radius from the calculated radius to obtain a map region to be stored. The CPU sequentially reads out from the CD-ROM the map data for each grid unit within the map region to be stored and sequentially writes the grid units of map data into the SD memory card.