| 摘要 |
PURPOSE:To prevent a wrong map image from being shown to a user by managing the validity term of map information. CONSTITUTION:The validity term of the map information is also stored in the map data base 1. The CPU 12 of a control unit 5 inputs the position of its own vehicle detected by a GPS reception device 2 and the current time periodically, reads map information including its own vehicle position out of the map data base 1, and controls a graphic controller 10 on the basis of the map information to draw a map image including its own vehicle position on a frame memory 9 together with its own vehicle mark, and, the validity term of the map information is compared with the current time and when the validity term has expired or is in a certain period from the current time, a graphic controller 10 is controlled to draw a message 'The validity term of the data base has expired.' or 'The validity term of the map data base expires soon.' at the lower end part of the frame memory 9. The image on the frame memory 9 is displayed on a display device 4. |
