Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
1999-05-20
2001-04-24
Blum, Theodore M. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
C701S208000, C340S995190, C342S419000
Reexamination Certificate
active
06222485
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
In general, this invention relates to automotive navigational mapping equipment and, more specifically, to a map display which utilizes a locking desired heading to control the orientation of an electronic map.
2. Description of the Related Art
Automotive navigational equipment utilizing map displays are common in the field of electronic navigation equipment. In general, these devices display a map of a desired area for a driver to reference while driving or planning a route. All such systems must implement some criteria for determining the orientation of the displayed map.
Some prior art systems always display the map heading north at the top of the electronic map display. These prior art systems may be useful in displaying an absolute direction of travel, but can become difficult to interpret while a vehicle is in motion. In such a situation, the user has to first locate the position of the vehicle on the map, determine the current direction the vehicle is traveling, and then reference the direction relative to the map display.
Some other types of navigational systems utilize positioning sensors, such as Global Positioning Systems (GPS antenna/receivers), to constantly calculate a vehicle's direction and use this calculated direction as the top of the display. Because some GPS systems become inaccurate at low speeds, the inaccuracies can cause the map display to shift erratically, confusing and annoying the driver attempting to read the map directions. In addition, since most turns from one road onto another occur at low velocity, the shifting of the map can become extremely disorienting to the driver at a time when it is most needed.
Some known prior art systems have attempted to remedy these problems by incorporating a desired heading, or desired track, to fix the orientation of the map display. This desired track method locates the general directional heading of the entire route and fixes that direction as top of the display for the entire trip. However, this method can become difficult to use, especially when there are multiple heading changes along a route. For example, in planning a route, the general direction of the entire route may be east. According to the prior art desired track method, the map display would be orientated so that east would always be at the top of the display. If the route being taken is generally straight east, the desired heading method generally serves its purpose. The desired track becomes disorientating, however, if the route changes direction either as multiple thoroughfares are traversed or just change in thoroughfare direction. In this scenario, east might be displayed as top while the vehicle may be traveling a different direction, thereby eliminating the usefulness of a desired track heading.
There exists a need for a map heading display which determines a map orientation that is useful in accommodating the relative current direction of a vehicle without being inaccurate and unsteady at low speeds and which is able to account for variations in the direction of travel along a desired route.
SUMMARY OF THE INVENTION
Based on the above mentioned deficiencies in the related art, it is an object of the present invention to provide a map heading display that can display a vehicle's current relative direction as the top of a map display.
It is a further object of the present invention to provide a map heading display which is accurate and steady at low speed.
Finally, it is an object of the present invention to provide a map heading display that can account for directional change along a route.
These and other objects of the present invention are achieved by a map display which utilizes a locking desired heading to fix a map orientation. In this system, the map display device includes a processor, a memory containing cartographic data encompassing a desired route and an input device capable of determining a vehicle's current location. Based on the cartographic data in memory, the processor graphically represents this data as a map on the display. In deciding which orientation the displayed map should have, the processor first calculates the vehicle's current location by sampling global positioning system data through an antenna/receiver. Using the vehicle's calculated two dimensional coordinates, the processor scans the cartographic data in memory to determine whether a preestablished thoroughfare corresponds to the vehicle's coordinates. If so, the processor uses the adjacent points within that thoroughfare to calculate the thoroughfare's direction. The processor sets the calculated thoroughfare direction as the desired heading orientation and adapts the display so as to make the desired heading the top of the heading.
If there is no corresponding thoroughfare for the vehicle's calculated position, the processor scans the cartographic data in memory to determine a thoroughfare most adjacent to the vehicle's current location. The processor uses the nearby points of the adjacent thoroughfare to calculate the thoroughfare's direction. The processor sets the calculated thoroughfare direction as the desired heading orientation and adjusts the display so as to make the desired heading the top of the display. The processor continues to monitor the vehicle's position and will update the map display as the thoroughfare changes direction.
REFERENCES:
patent: 4982332 (1991-01-01), Saito et al.
patent: 5161886 (1992-11-01), De Jong et al.
patent: 5204817 (1993-04-01), Yoshida
patent: 5774826 (1998-06-01), McBride
patent: 5938720 (1999-08-01), Tamai
Beesley Darin J.
Robinson Stephen C.
Walters Thomas H.
Blum Theodore M.
Garmin Corporation
Shook Hardy & Bacon LLP
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