Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
1998-08-06
2001-08-28
Nguyen, Tan (Department: 3664)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S023000, C701S200000, C340S990000, C340S995190, C342S176000, C342S178000, C345S440000, C345S519000
Reexamination Certificate
active
06282490
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to a map display device which transforms the coordinates of map data, and displays a map by using the transformed coordinates.
2. Description of Related Art
There are various types of vehicle navigation systems providing a driver with guidance information along a vehicle travel route, such as a navigation system that searches for a route to a destination and provides audio/visual guidance of characteristic information on the map regarding the route to the destination, and a navigation system that displays a map centering the present position and provides information about the vicinity of the present position, etc. For example, regarding a vehicle navigation system having functions, such as route search and route guidance, there are proposed systems, for displaying a travel image on a 3-D screen in order for the driver to comprehend information on the travel direction at a glance, and for displaying a road map from a bird's-eye view method, which magnifies a road map of the vicinity of the present position of a vehicle. (e.g. Japanese Patent Publication No. 160853/96, No. 166249/96 and No. 127861/97).
Some of the previously proposed systems display a wide-area map by setting a window display area on part of the bird's-eye view and designating the displayed area by a frame in order to improve the defects of the bird's-eye view this makes it difficult for the driver to sense distances and the dimensions of the road map area. Some other systems display a plane map or a bird's-eye view close to a plane map at the top of the displayed area within the predetermined area in order for the driver to receive accurate road distance information.
The above mentioned bird's-eye view displays a wider area than a plane map does, however, this applies to only one direction (Y direction) which is in the forward direction of the present position. Furthermore, as only the vertical direction of the screen is compressed, the sense of distance is different between vertical direction and horizontal direction. The distortion produced in the vicinity of the present position causes the driver to lose the sense of distance during the movement of the vehicle because the ratio between the actual travel distance and the distance shown by the movement of the present position mark on the screen differs according to the direction.
SUMMARY OF THE INVENTION
An aspect of the invention is to provide the sense of distance unaffected by the direction using a present position and a display wide area map in the forward direction.
In order to attain the aspect as described above there is provided a map display device, comprising an information memory device for storing map data, a display device for displaying a map based on map data stored in the information memory device, and a display control device which has a coordinate transformation device for transforming the coordinates on a curved plane into the coordinates on a projected plane for controlling the readout of map data from the information memory device and the map display on the display device. In addition, the display control device relates the coordinates on the map to coordinates on the curved plane with respect to a coordinate transformation reference point, transforms the coordinates on the curved plane into coordinates on the projected plane using the coordinate transformation device, and displays a map on the display device by using the coordinates transformed on the projected plane.
Further, the display control device regards a curved plane as a spherical plane, an oval spherical plane, or a partial circular cone plane. Map coordinates in the area within the predetermined radius around a coordinate transformation reference point are regarded as coordinates on the plane. Map coordinates in the area outside the predetermined radius are regarded as coordinates on the curved plane. The map coordinates on the curved plane which curvature is gradually reduced at every fixed radius around a coordinate transformation reference point, or only the X-coordinates of the coordinates on the map below the coordinate transformation reference point are regarded as a center point coordinates on the curved plane. The various coordinates are transferred into the respective coordinates on the projected plane by the coordinate transformation device.
REFERENCES:
patent: 5161886 (1992-11-01), De Jong et al.
patent: 5913918 (1999-06-01), Nakano et al.
patent: 8-160853 (1996-06-01), None
patent: 8-166249 (1996-06-01), None
patent: 9-127861 (1997-05-01), None
Masuda Hiroyoshi
Morimoto Hirofumi
Nimura Mitsuhiro
Aisin Aw Co. Ltd.
Beaulieu Yonel
Nguyen Tan
Oliff & Berridge PLC.
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