Abstract:
Method for navigating a vehicle in a road system is provided, in which method data is read from a data-storage medium and automatically transferred to a memory of a navigation device after the data medium is inserted into a data-media drive associated with the navigation device. The transferred data remains available for vehicle navigation even after the data medium is removed from the data-media drive.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to a method for navigating a vehicle in a road system. 
     BACKGROUND INFORMATION 
     Navigation devices that require a data medium, e.g., a compact disc or a DVD (digital versatile disc), in order to perform navigation are already known. A digital map containing a road system is placed on the data medium, the navigation device regularly accessing the data medium to calculate the trip route and to output driving instructions. The expensive data-media drive is thus available in the vehicle only for the navigation device, or the drive cannot be used for other data media while vehicle navigation is being carried out. Navigation methods in which a navigation device in the vehicle accesses an external database without requiring a data medium in the vehicle are also known. However, additional costs are thereby incurred for data transfer. 
     SUMMARY 
     The method according to the present invention for navigating a vehicle in a road system has the advantage over the related art in that navigation data is automatically transferred to a memory of the navigation device immediately after the data medium is inserted into a data media drive. The transferred data is then available to the navigation device for vehicle navigation purposes, i.e., in particular for calculating the trip route and outputting driving instructions as well as for outputting additional information, without having to access the data medium again. As a result, the data-media drive may also be used for other purposes, e.g., for playing music or video data. In addition, navigation is possible within a limited area even without inserting a data medium, if permitted by the storage capacity of the navigation device memory. The direct access to the memory assigned to the navigation device also shortens the navigation-data access time. 
     It is advantageous that the inserted data medium may be removed after the navigation data has been transferred and another data medium may be inserted without having to interrupt the navigation function. This makes it possible, in particular, to link the data of different data media in the navigation device, e.g., the data media of different manufacturers or data media having different content. One example of this is linking a first data medium containing map data with a second data medium containing tourist information that may then be evaluated together by the navigation device. 
     A further advantage of the present invention is that a first map area is stored on a first data medium and a second map area on a second data medium, so that the trip route may be planned from the first map area to the second map area. For example, if a trip is to cross the border from Germany to France, the Germany CD may be inserted first and its relevant data transferred to the memory. A CD containing French map data is then inserted, the route also being planned through France. It is no longer necessary to subsequently change data media, since the relevant navigation data has been automatically transferred to the memory of the navigation device without prompting the user. The stored data may also be combined from multiple data sources, e.g., a travel guide for a mixed tour compiled from different travel guide data media, or navigation data combined from data media for multiple areas. 
     A further advantage of the present invention is that audio and/or video data may be stored on a second data medium, so that, for example, navigation does not have to be interrupted to play music, nor does an additional drive need to be installed in the vehicle, for example for a music compact disc. 
     It is further advantageous to store the data transferred from the data medium through non-volatile means in the navigation device so that the data remains available for further vehicle navigation even after turning off the vehicle or after a power failure. 
     It is further advantageous to store the data dependent on a selected function, the planned route or the present vehicle position. For example, the data that is especially likely to be accessed is transferred from the data medium to the navigation device. 
     In this regard, it is particularly advantageous to store data for the area surrounding a trip route so that it is not necessary to access the data medium again when traveling along the trip route within a corridor of a preselected width. 
     It is further advantageous to convert the navigation data to a different data format during the transfer. In particular, if the data is stored on the data medium in coded form, this makes it possible to store uncoded data directly in the memory assigned to the navigation device. This also makes it possible to convert data media of different manufacturers directly to a data format that is compatible with the navigation device when transferring data to the navigation device memory, so that the conversion of the data format does not take up any extra time when accessing the corresponding data. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a block diagram of a navigation device according to the present invention for carrying out the method according to the present invention. 
         FIG. 2  shows a flowchart of a portion of an exemplary embodiment of the method according to the present invention. 
         FIG. 3  shows a flowchart of another portion of the exemplary embodiment of the method according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a navigation device  1  that is connected to a display unit  2 . Navigation device  1  has an arithmetic unit  3 , a main memory  4 , a memory  5  for navigation data and a playback device  6  for audio and/or video data. In addition, a loudspeaker  7  is connected to navigation device  1 , the loudspeaker of the car radio. Display unit  2  has a display area  8 , which may be designed as a liquid crystal display. A map representation  9  having a road representation is displayed in display area  8 . In addition, a control menu  10  that is operated by controls  11  next to display area  8 , and which is used to control navigation device  1 , is displayed in display area  8 . A positioning device  12 , which may be a GPS (Global Positioning System) satellite positioning device, may be used to determine a position of the vehicle in which navigation device  1  is located, via contact with a satellite  13 . Additional data is retrievable from a mobile communications network  16  via a radio interface  14 . In particular, a connection to the Internet is possible. A data media drive  15  into which a data medium  20  is insertable is also connected to navigation device  1 . Data medium  20  may be ejected at the user&#39;s request and replaced by a second data medium  21 . In a further exemplary embodiment, the data media drive may also be integrated into navigation device  1 , or a data medium, e.g., a memory card, may instead be connected directly to navigation device  1  via a suitable interface. 
     Data media  20 ,  21  may be magnetic and/or optical data media, e.g., in the form of a compact disc, a magneto-optical disc or a DVD (digital versatile disc). Playback device  6  is used, in particular, as an audio or video tuner, a video signal being output via display unit  2  and an audio signal being output via loudspeaker  7 . Main memory  4  is designed as a volatile memory and assigned to arithmetic unit  3 . Memory  5  is used to record the navigation data transferred from data medium  20  to navigation device  1 . In an exemplary embodiment, memory  5  is designed as a non-volatile memory, e.g., as a battery-backed volatile memory such as a RAM (random-access memory), a hard disk, a memory card or a rewritable magnetic and/or optical data medium. When data medium  20  is inserted into data media drive  15 , arithmetic unit  3  initiates an automatic transfer of navigation data to memory  5 . The navigation data is, for example, data of a digital road map. Further navigation data includes, for example, additional information such as information on road traffic, hotels and restaurants, tourist sights or gas stations as well as rest areas. Up-to-date traffic information is also retrievable via air interface  14  and taken into account for vehicle navigation. After the user makes an entry via controls  11 , navigation device  1  calculates a trip route from the vehicle position determined via positioning device  12  to a destination entered via controls  11  on the basis of the navigation data transferred to memory  5 . Arithmetic unit  3  uses this information to determine driving instructions, which are output to the driver via the loudspeaker and/or display unit  2 . 
     In an exemplary embodiment of the method according to the present invention, data is input from different navigation data media and taken into account for vehicle navigation. If a user would like to drive, for example, from a city in Germany to a French city, and if the road map information is only located on two different data media, the user is first prompted to insert the first data medium containing the German map data. A portion of the map data is transferred to memory  5 , depending on the present vehicle position. The user is then prompted to insert the second data medium containing the French map data. The optimum trip route is determined on the basis of the transferred map data. If the user removes the data medium from data media drive  15  too early, a warning thereof is output via the loudspeaker and/or display  2 . 
       FIG. 2  shows a flowchart of a portion of an exemplary embodiment of a method according to the present invention. Based on a prompt step  30 , a user is prompted to insert a navigation data medium into data media drive  15 . In a determination step  31 , the data transferred to memory  5  of navigation device  1  is then determined, for example, as a function of the trip route or the destination entered via controls  11 . In a subsequent transfer step  32 , this data is read from data medium  20  immediately, if possible, after data medium  20  is inserted, transferred to navigation device  1  and stored in memory  5 . There, the data is available for processing by arithmetic unit  3 . It is not necessary to prompt the user to transfer the data, since the data transfer is started automatically by navigation device  1 . A further transfer desired by the user may also be requested, for example, via control panel  11 . If necessary, the data is decoded by arithmetic unit  3  during the transfer. In a subsequent notification step  33 , a message to the user is output stating that the necessary data transfer has been completed and the data medium is no longer needed for the time being. If the user would like to play music or a video, he may insert another data medium  21  into data media drive  15  and start playing music  34 . In a subsequent checking step  35 , a check is carried out at regular, preselected intervals to ascertain whether the data medium is needed again. While traveling the previously calculated route, this will not be the case, since all relevant data is stored in memory  5  and thus available to arithmetic unit  3 . If data medium  20  is not needed, music playback  34  continues. If, however, it is determined that the previous data medium is required again, or that another data medium must be inserted, the method branches back to prompt step  30 . 
       FIG. 3  shows another portion of the exemplary embodiment of a method according to the present invention. Based on a route calculation step  40 , a trip route is calculated from a starting point to a destination, if necessary, including necessary driving instructions. In a subsequent determination step  41 , the navigation data transferred from data medium  20  to memory  5  is determined. In particular, a corridor surrounding the trip route is determined. This corridor may be determined, for example narrowly in the vicinity of the starting point and destination, then broadened as needed in the direction of the middle of the route. If necessary, it is also possible to make an assignment to geographic sectors that are limited, for example, by specifying limits in a coordinate system, e.g., the degrees of longitude and latitude. If necessary, driver preferences that may be stored in, or are preselectable by, navigation device  1  may be taken into account. For example, only side streets, or only the data of highways, may be transferred. This transfer then takes place in subsequent transfer step  42 . In a subsequent output step  43 , the individual driving instructions and any necessary additional tourist information are optically and/or acoustically output to the user via display unit  2  and/or loudspeaker  7 . In a subsequent position checking step  44 , the present vehicle position is checked. If it is determined that the destination has been reached, the vehicle navigation ends in a termination step  45 . If it is determined that the vehicle is still located in the predefined corridor, the method branches back to output step  43  for outputting the next set of driving instructions. If it is determined in position checking step  44  that the vehicle has left the corridor, for example due to a traffic holdup, either at the user&#39;s request or due to a necessary route change as a result of a traffic holdup transmitted via air interface  14 , the method branches back to route calculation step  40 , and the trip route is modified. Although the data medium is no longer needed following transfer step  42 , it must nevertheless be inserted again for route calculation step  40 . 
     It is also possible to display, in display area  8 , the time remaining until the data has been fully transferred to memory  5 . In particular, the prompt to insert the data medium may also be output acoustically via loudspeaker  7 . Likewise, a warning is output if the data has not yet been fully transferred to memory  5 .