DESCRIPTION

IN-VEHICLE MAP DISPLAY APPARATUS, MAP DATA STORAGE

DEVICE, AND MAP DATA STRUCTURE

TECHNICAL FIELD

The present invention generally relates to an in-vehicle map display apparatus, a map data storage device, and a map data structure.

BACKGROUND ART

Patent document 1 discloses a navigation device that includes a storage medium reproducing unit configured to select a first storage medium storing map data primarily describing a first area and secondarily describing a second area adjacent to the first area, or a second storage medium storing map data primarily describing the second area and secondarily describing the first area, and to reproduce the map data stored in the selected storage medium; a position detecting unit configured to detect a current position; a display unit; and a control circuit configured to display the reproduced map data together with the detected current position on the display unit. The control circuit of the disclosed navigation device is further configured to cause the storage medium reproducing unit to switch from the first storage medium to the second storage medium and to reproduce the map data stored in the second storage medium when the current position moves from the first area to the second area.

[Patent document 1] Japanese Patent Application Publication No. 10-213444

Meanwhile, a map, in its nature, represents

facts that basically do not vary depending on the views of respective countries. However, because of territorial disputes in the world today, positions of borders on a map sometimes cause problems. Although such problems can be solved by preparing all the map data for each country where the map data are used, this approach increases the costs and reduces the efficiency of map production.

DISCLOSURE OF THE INVENTION Embodiments of the present invention provide an in-vehicle map display apparatus, a map data storage device, and a map data structure that solve or reduce one or more problems caused by the limitations and disadvantages of the related art. An embodiment of the present invention provides an in-vehicle map display apparatus that includes a universal map data storage unit configured to store universal map data that are independent of countries; a country-specific map data storage unit configured to store country-specific map data provided for and reflecting views of the respective countries; a destination country determining unit configured to determine a destination country of a vehicle; a data obtaining unit configured to obtain the universal map data from the universal map data storage unit and to obtain the country-specific map data corresponding to the destination country determined by the destination country determining unit from the country-specific map data storage unit; and a map displaying unit configured to display a map on a display based on the universal map data and the country-specific map data obtained by the data obtaining unit.

Another embodiment of the present invention

provides an in-vehicle map display apparatus that includes a universal map data storage unit configured to store universal map data that are independent of countries; a country-specific map data storage unit configured to store country-specific map data provided for and reflecting views of the respective countries; a current country determining unit configured to determine a current country where a vehicle is running; a data obtaining unit configured to obtain the universal map data from the universal map data storage unit and to obtain the country-specific map data corresponding to the current country determined by the current country determining unit from the country-specific map data storage unit; and a map displaying unit configured to display a map on a display based on the universal map data and the country-specific map data obtained by the data obtaining unit .

Another embodiment of the present invention provides a map data storage device separately storing universal map data that are independent of countries and country-specific map data provided for and reflecting views of the respective countries.

Still another embodiment of the present invention provides a data structure of map data stored in a storage medium. The map data include universal map data that are independent of countries and country- specific map data provided for and reflecting views of the respective countries, and are configured such that the country-specific map data corresponding to any specified one of the countries are retrievable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing illustrating an exemplary

configuration of an in-vehicle map display apparatus according to an embodiment of the present invention;

FIG. 2 is a table showing an exemplary structure of map data stored in a map data source DB 40; FIG. 3 is a drawing used to describe universal map data and country-specific map data;

FIG. 4 is a flowchart showing an exemplary process of generating map data in a map DB 18 based on map data in the map data source DB 40; FIG. 5 is a table showing an exemplary structure of map data generated and stored in the map DB 18 through the process shown in FIG. 4;

FIG. 6A is a drawing illustrating an exemplary map screen displayed based on universal map data and country-specific map data of country A;

FIG. 6B is a drawing illustrating an exemplary map screen displayed based on the universal map data and country-specific map data of country B;

FIG. 7 is a flowchart showing another exemplary process of generating map data in the map DB 18;

FIG. 8 is a flowchart showing another exemplary process of generating map data in the map DB 18; FIG. 9 is a flowchart showing still another exemplary process of generating map data in the map DB 18;

FIG. 1OA is a drawing illustrating a map screen displayed when the destination country is country A and the current country is also country A; and

FIG. 1OB is a drawing illustrating a map screen displayed when the destination country is country A and the current country is country B,

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention are described below with reference to the accompanying drawings .

FIG. 1 is a drawing illustrating an exemplary configuration of an in-vehicle map display apparatus according to an embodiment of the present invention. A navigation apparatus 10 shown in FIG. 1 is an embodiment of the in-vehicle map display apparatus. The navigation apparatus 10 includes a navigation electronic control unit (ECU) 12, a display 14, a user interface 16, a map database (DB) 18, a global positioning system (GPS) receiver 30, and a map data source database (DB) 40. The navigation ECU 12 comprises a microcomputer including a CPU, a ROM, and a RAM that are connected to each other via a bus (not shown) .

Based on map data in a map DB 18 described later and positional information from the GPS receiver 30, the navigation ECU 12 performs, for example, route search, route guidance, facility search, and map rendering.

The display 14 may be implemented by a liquid crystal display and is placed in an appropriate position in a vehicle. For example, the display 14 is placed in an instrument panel. The display 14 displays a map rendered (or rasterized) based on map data in the map DB 18. The display 14 may also display an operations menu, an image taken by an in-vehicle camera, and a television picture.

The user interface 16 is an input unit such as a remote control or a touch panel on the display 14. In this embodiment, the user (such as a manufacturer, a

dealer, or an end user) uses the user interface 16 to input information (hereafter called destination country information) on a destination country to which a vehicle is to be shipped. The input destination country information is stored in a memory (preferably, a nonvolatile memory) that is accessible by the navigation ECU 12. Destination country information may be input by a manufacturer before a vehicle is shipped (or during the manufacturing process) , by a dealer before the vehicle is handed over to the end user, or by the end user after delivery. The navigation ECU 12 may be configured to output a message on the display 14 to request entry of destination country information if no destination country information is stored. Destination country information either directly or indirectly indicates a destination country. Also, destination country information may be combined with other information such as a vehicle identification number.

The map DB 18 is implemented by a writable (preferably, rewritable) non-volatile memory (or secondary storage unit) such as a hard disk drive. The map DB 18 stores map data structured as described below.

The GPS receiver 30 receives radio signals from satellites via a GPS antenna (not shown) , estimates the position of the vehicle based on the received radio signals, and sends the estimated vehicle position as vehicle position information to the navigation ECU 12. The GPS receiver 30 may use any positioning method, such as independent positioning or differential positioning (including interferometric positioning) , to estimate vehicle positions. Estimated vehicle positions may be corrected based on outputs from sensors such as a speed sensor and a gyro sensor (not shown) and/or information

received by a beacon receiver and an FM multi-receiver (not shown) . Also, estimated vehicle positions may be corrected intermittently by map-matching using map data in the map DB 18. The map data source DB 40 may be implemented by a non-rewritable memory such as a ROM. For example, the ROM of the navigation ECU 12 or a removable memory

(e.g., a secure digital (SD) card) may be used for the map data source DB 40. Also, any random-access or sequential-access memory accessible by the navigation ECU 12 via wireless or wired communication may be used for the map data source DB 40. For example, a memory (of a server) in an information center outside of the vehicle may be used for the map data source DB 40. When using a memory in an information center, the memory is preferably a rewritable memory so that the map data in the map data source DB 40 can be edited or modified under the management of an administrator.

The map data source DB 40 stores map data of multiple countries used to generate map data of the map DB 18. In other words, map data of the map DB 18 are composed of a portion of map data in the map data source DB 40. Here, for descriptive purposes, it is assumed that the map data in the map data source DB 40 include map data of adjacent countries A, B, and C.

FIG. 2 is a table showing an exemplary structure of map data stored in the map data source DB 40. As shown in FIG. 2, map data of the map data source DB 40 include route search data, route guidance data, facility search data, map rendering data, and other data. The map rendering data include a line data group, a character data group, and a symbol data group.

The line data group indicates a group of data

for rendering terrain and features such as roads and buildings by lines in two dimensions or three dimensions, and includes multiple sets of line data. Each set of line data includes a coordinate array representing positions of lines to be rendered, rendering attributes of an image to be rendered, and data attributes of the lines to be rendered. For example, the data attributes define attributes of lines such as borders.

The character data group indicates a group of data for rendering characters used to describe, for example, place names and facility names on a map, and includes multiple sets of character data. Each set of character data includes coordinates representing the position of a character string to be rendered, the character string, and rendering attributes such as the font and size of the character string.

The symbol data group indicates a group of data for rendering symbols representing, for example, facilities such as gas stations on a map, and includes multiple sets of symbol data. Each set of symbol data includes coordinates representing the position of a symbol to be rendered and a symbol ID identifying the symbol.

In this embodiment, map data stored in the map data source DB 40 include universal map data that are independent of the views of countries and (sets of) country-specific map data that reflect the views of countries. The universal map data and the country- specific map data are stored separately in the map data source DB 40. The universal map data and the country- specific map data may be stored in a hierarchical manner (e.g., the universal map data are placed in a higher layer and the country-specific map data are placed in a

lower layer) , or may be stored in separate storage areas or storage units. Each set of the country-specific map data is stored in association with the corresponding country. For example, sets of country-specific map data are stored in storage areas assigned to the respective countries such that any one of the sets of country- specific map data can be retrieved by specifying the address of the corresponding storage area.

In the example shown in FIG. 2, the map rendering data include universal map data (universal map-rendering data) and sets of country-specific map data (country-specific map-rendering data) . Hereafter, terms "universal map data" and "universal map-rendering data" may be used interchangeably, and terms "country- specific map data" and "country-specific map-rendering data" may be used interchangeably. The universal map- rendering data and the country-specific map-rendering data may have substantially the same data structure including a line data group, a character data group, and a symbol data group. In FIG. 2, the map rendering data include country-specific map-rendering data for countries A, B, and C.

The country-specific map-rendering data of each country are tailored to suit the views of the country. Assume a case as shown in FIG. 3 where countries A and B have different views regarding the border between them, and countries B and C have different views regarding the border between them. In this case, data for rendering a border A2 claimed by country A against country B are stored as the map rendering data for country A. Similarly, data for rendering borders B2 and B3 claimed by country B against countries A and C are stored as the map rendering data

for country B. In the same manner, data for rendering a border C2 claimed by country C against country B are stored as the map rendering data for country C.

Also assume a case where countries A and B use different official languages and have different views on a border area Rl. In this case, the character data describing the border area Rl and included in the map rendering data for country A may be prepared in the official language of country A. Similarly, the character data describing the border area Rl and included in the map rendering data for country B may be prepared in the official language of country B. Supposing that the names of features (such as cities, places, roads, and facilities) in the border area Rl are different in countries A and B, the corresponding map rendering data for country A are prepared with the names used in country A, and the corresponding map rendering data for country B are prepared with the names used in country B. Further, supposing that country A does not want to display some features in the border area Rl because of religious or national security reasons but country B wants to display those features, data concerning the features are excluded from the map rendering data for country A and are included in the map rendering data for country B. The above discussions may also apply to a border area R2 on which countries B and C have different views .

The map rendering data for country A may include map rendering data of the border area R2 (including the border itself) prepared for either country B or C. In this case, either the map rendering data for country B or the map rendering data for country C is selected for the border area R2, for example, based

-li¬

on the intentions of country A or relationships between country A and countries B and C. Also, the selection may be made in a manner as described below with reference to

FIG. 9. Similarly, the map rendering data for country C may include map rendering data of the border area Rl

(including the border) prepared for either country A or

B. In this case, either the map rendering data for country A or the map rendering data for country B are selected for the border area Rl, for example, based on the intentions of country C or relationships between country C and countries A and B. Also, the selection may be made in a manner as described below with reference to FIG. 9.

The universal map-rendering data (or universal map data) are independent of (the views of) countries and therefore are prepared based on facts. For example, in FIG. 3, an area A defined by segments Al and B2 is accepted by both countries A and B as the territory of country A, and therefore map data of the area A (including line data of the segment Al (or border Al) ) are prepared and stored as universal map data. The character data of the area A may be prepared in the official language of country A. Similarly, an area B defined by segments A2, Bl, and C2 is accepted by countries A, B, and C as the territory of country B, and therefore map data of the area B (including line data of the segment Bl (or border Bl) ) are prepared and stored as universal map data. The character data of the area B may be prepared in the official language of country B. Also, an area C defined by segments B3 and Cl is accepted by countries B and C as the territory of country C, and therefore map data of the area C

(including line data of the segment Cl (or border Cl) )

are prepared and stored as universal map data. The character data of the area C may be prepared in the official language of country C.

FIG. 4 is a flowchart showing an exemplary process of generating map data in the map DB 18 based on map data in the map data source DB 40. The exemplary process shown in FIG. 4 is performed by the navigation ECU 12 when requested via the user interface 16. For example, this process is requested by a manufacturer when the navigation apparatus 10 is installed in a vehicle during the manufacturing process or when the destination country is changed. Alternatively, this process may be automatically executed when destination country information is entered. In step 100 shown in FIG. 4, the navigation

ECU 12 reads destination country information from a memory.

In step 102, the navigation ECU 12 determines a destination country based on the destination country information read in step 100.

In step 104, the navigation ECU 12 retrieves universal map data from the map data source DB 40 and stores the retrieved universal map data in the map DB 18. In step 106, the navigation ECU 12 retrieves country-specific map data corresponding to the destination country determined in step 102 from the map data source DB 40 and stores the retrieved country- specific map data in the map DB 18. As a result, the universal map data and the country-specific map data for the destination country are stored in the map DB 18. The order of steps 104 and 106 may be reversed.

FIG. 5 is a table showing an exemplary structure of map data generated and stored in the map DB

18 through the process shown in FIG. 4. Here, it is assumed that the map data are for country A. As shown in FIG. 5, the map data in the map DB 18 for country A include the universal map rendering data and the country-specific map rendering data for country A that are selected from the map data in the map data source DB 40 shown in FIG. 2. Based on the map data stored in the map DB 18, the navigation ECU 12 displays a map on the display 14 and performs other functions. FIGs. 6A and 6B are schematic diagrams illustrating map screens displayed on the display 14. FIG. 6A shows an exemplary map screen displayed based on universal map data and country-specific map data of country A. FIG. 6B shows an exemplary map screen displayed based on the universal map data and country- specific map data of country B.

As shown in FIG. 6A, when the destination country is country A, the border A2 (see also FIG. 3) claimed by country A is displayed and the area Rl (see FIG. 3) is displayed according to the views of country A

(details are omitted) . Similarly, as shown in FIG. 6B, when the destination country is country B, the border B2

(see also FIG. 3) claimed by country B is displayed and the areas Rl and R2 (see FIG. 3) are displayed according to the views of country B (details are omitted) .

Thus, according to an embodiment of the present invention, map data in the map data source DB 40 comprises universal map data independent of countries and country-specific map data reflecting views of countries, and map data to be stored in the map DB 18 can be generated from the map data in the map data source DB 40 to suit the views of the corresponding country. This configuration increases the versatility of

map data in the map data source DB 40 and makes it possible to efficiently generate map data in the map DB 18 for each destination country.

FIG. 7 is a flowchart showing another exemplary process of generating map data in the map DB

18. The process shown in FIG. 7 is preferable for a case where destination country information is not available.

The process shown in FIG. 7 may be executed when requested as described above with reference to FIG. 4 or may be executed at regular intervals.

In step 200, the navigation ECU 12 obtains vehicle position information from the GPS receiver 30.

In step 202, the navigation ECU 12 determines the country where the vehicle is currently running (hereafter called the current country) based on the obtained vehicle position information.

In step 204, the navigation ECU 12 sets the current country determined in step 202 as the destination country. In step 206, the navigation ECU 12 retrieves universal map data from the map data source DB 40 and stores the retrieved universal map data in the map DB 18.

In step 208, the navigation ECU 12 retrieves country-specific map data corresponding to the destination country set in step 204 from the map data source DB 40 and stores the retrieved country-specific map data in the map DB 18. As a result, the universal map data and the country-specific map data for the destination country (or the current country) are stored in the map DB 18. The order of steps 206 and 208 may be reversed.

In step 202, the navigation ECU 12 may be configured to determine the current country based on the

current vehicle position or to determine the country where the vehicle has run most frequently based on the history of vehicle positions and use that country as the current country. The latter method makes it possible to appropriately determine the current country to be used as the destination country even when a vehicle often runs across two or more countries.

With the process shown in FIG. 7, it is possible to generate map data suitable for a current country in the map DB 18 even when destination country information is not available or is inaccurate because, for example, the destination country information is not updated after the vehicle is exported to another country as a used car. FIG. 8 is a flowchart showing another exemplary process of generating map data in the map DB 18. In the process shown in FIG. 8, map data in the map DB 18 are generated based on the current country regardless of a destination country. The process shown in FIG. 8 may be executed when requested as described above with reference to FIG. 4 or may be executed at regular intervals to reflect the change of the current country.

In step 300, the navigation ECU 12 obtains vehicle position information from the GPS receiver 30.

In step 302, the navigation ECU 12 determines the current country based on the obtained vehicle position information.

In step 304, the navigation ECU 12 retrieves universal map data from the map data source DB 40 and stores the retrieved universal map data in the map DB 18. In step 306, the navigation ECU 12 retrieves country-specific map data corresponding to the current

country determined in step 302 from the map data source DB 40 and stores the retrieved country-specific map data in the map DB 18. As a result, the universal map data and the country-specific map data for the current country are stored in the map DB 18. The order of steps 304 and 306 may be reversed.

With the process shown in FIG. 8, it is possible to generate and maintain map data suitable for the current country in the map DB 18 even if the current country changes. For example, when the current country changes from country A to country B, map data in the map DB 18 comprising the universal map data and the country- specific map data for country A are updated to include the universal map data and the country-specific map data for country B. The change of the current country from country A to country B may be determined based on either the country-specific map data for country A (i.e., the border A2 claimed by country A) or the country-specific map data for country B (i.e., the border B2 claimed by country B) .

FIG. 9 is a flowchart showing still another exemplary process of generating map data in the map DB 18.

In step 400, the navigation ECU 12 reads destination country information from a memory.

In step 401, the navigation ECU 12 determines the destination country based on the destination country information read in step 400.

In step 402, the navigation ECU 12 obtains vehicle position information from the GPS receiver 30.

In step 404, the navigation ECU 12 determines the current country based on the obtained vehicle position information.

In step 406, the navigation ECU 12 retrieves universal map data from the map data source DB 40 and stores the retrieved universal map data in the map DB 18. In step 408, the navigation ECU 12 determines whether the current country determined in step 404 matches the destination country determined in step 401. If the current country matches the destination country, the process proceeds to step 410. If the current country does not match the destination country, the process proceeds to step 412.

In step 410, the navigation ECU 12 retrieves country-specific map data corresponding to the destination country from the map data source DB 40 and stores the retrieved country-specific map data in the map DB 18. As a result, the universal map data and the country-specific map data for the destination country are stored in the map DB 18.

In step 412, the navigation ECU 12 retrieves country-specific map data corresponding to the destination country from the map data source DB 40.

In step 414, the navigation ECU 12 retrieves country-specific map data corresponding to the current country from the map data source DB 40.

In step 416, the navigation ECU 12 combines the country-specific map data for the destination country and the country-specific map data for the current country, and stores the combined data in the map

DB 18. More specifically, the navigation ECU 12 uses the country-specific map data of the destination country for a border area between the destination country and the current country and uses the country-specific map data of the current country for border areas between the current country and other countries to generate the

combined data. For example, when the destination country is country A and the current country is country B, the navigation ECU 12 stores the corresponding part of the country-specific map data of country A for the border area Rl (see FIG. 3) between countries A and B in the map DB 18, and stores the corresponding part of the country-specific map data of country B for the border area R2 (see FIG. 3) between countries B and C in the map DB 18. Thus, according to the process shown in FIG. 9, the universal map data and the combined country- specific map data are stored in the map DB 18.

FIGs. 1OA and 1OB are schematic diagrams illustrating map screens displayed based on map data generated through the process shown in FIG. 9. FIG. 1OA shows a map screen displayed when the destination country is country A and the current country is also country A (i.e., a map screen displayed based on map data generated in step 410 of FIG. 9) . FIG. 1OB shows a map screen displayed when the destination country is country A and the current country is country B (i.e., a map screen displayed based on map data generated in step 416 of FIG. 9) .

Here, it is assumed that a part of the country-specific map data of country A which part corresponds to the border area R2 between countries B and C is based on the country-specific map data of country C. Therefore, in FIG. 1OA, the border between countries B and C is displayed in a position claimed by country C. When the current country changes from country A to country B, as described in step 416 of FIG. 9, the part of the country-specific map data of country A corresponding to the border area R2 is replaced with data obtained from the country-specific map data of

country B. As a result, as shown in FIG. 1OB, the border between countries B and C is displayed in a position claimed by country B. Thus, with the process shown in

FIG. 9, it is possible to generate and maintain map data in the map DB 18 placing priority on the destination country and also taking into account the current country.

In claims of the present application, a universal map data storage unit and a country-specific storage unit may correspond to the map data source DB 40; a destination country determining unit may correspond to a function implemented by the navigation ECU 12 and exemplified in step 102 of FIG. 4, step 204 of FIG. 7, and step 401 of FIG. 9; a data obtaining unit may correspond to a function implemented by the navigation ECU 12 and exemplified in steps 104 and 106 of FIG. 4, steps 206 and 208 of FIG. 7, steps 304 and 306 of FIG. 8, and steps 406, 410, 412, 414, and 416 of FIG. 9; an input unit may correspond to the user interface 16; a current country determining unit may correspond to a function implemented by the navigation ECU 12 and exemplified in step 202 of FIG. 7, step 302 of FIG. 8, and step 404 of FIG. 9; a matching unit may correspond to a function implemented by the navigation ECU 12 and exemplified in step 408 of FIG. 9; and a map displaying unit may correspond to a function implemented by the navigation ECU 12 and exemplified in the above embodiments. Also, a function implemented by the navigation ECU 12 and exemplified in step S414 of FIG. 9 may be referred to as a second data obtaining unit. The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention.

In the above embodiments, necessary map data are retrieved from the map data source DB 40 and stored in the map DB 18, and the map data in the map DB 18 are used for processing by the navigation ECU 12. This configuration reduces the frequency of access to (or the workload of) the map data source DB 40 and eliminates the need to adapt rendering software of the navigation ECU 12 for each destination country. However, it is also possible to configure the rendering software to determine a destination country (or a current country) as described above and to select country-specific map data corresponding to the determined destination country (or the current country) when rendering a map screen. In this case, the map DB 18 may be omitted and the rendering software (or the navigation ECU 12) may be configured to directly access the map data source DB 40 when rendering a map screen. Also, a memory (main memory) such as a RAM may be used in place of the map DB 18. Destination country information may be input using a microphone and a voice recognition device that recognizes voice commands.

As described above, embodiments of the present invention provide an in-vehicle map display apparatus, a map data storage device, and a map data structure that make it possible to increase the versatility of map data and to efficiently display maps suitable for respective destination countries.

The present application claims priority from Japanese Patent Application No. 2007-123528 filed on May 8, 2007, the entire contents of which are hereby incorporated herein by reference.