WO2015008465A1

WO2015008465A1 - Navigation device

Info

Publication number: WO2015008465A1
Application number: PCT/JP2014/003679
Authority: WO
Inventors: 鈴木　孝光
Original assignee: 株式会社デンソー
Priority date: 2013-07-15
Filing date: 2014-07-10
Publication date: 2015-01-22
Also published as: JP2015017958A

Abstract

In the present invention, initial map data is saved to a non-rewritable first storage medium (171), and map difference data is saved to a rewritable second storage medium (181). The rewritable second storage medium may be provided with a capacity for storing map difference data having a relatively small data size. The first storage medium, which saves the initial map data that forms the majority of the combined total map data of the initial map data and the map difference data, is realized through a non-rewritable storage medium that is cheaper than the rewritable second storage medium.

Description

Navigation device

Cross-reference of related applications

This disclosure is based on Japanese Patent Application No. 2013-147167 filed on July 15, 2013, the contents of which are incorporated herein.

The present disclosure relates to a storage medium that stores map data in a navigation device.

Conventionally, navigation devices are provided with a storage medium for storing map data. As a storage medium for storing the map data, as disclosed in Patent Document 1, a hard disk, a compact disk, or the like is used.

Since this map data includes road data, background data, and voice data for voice guidance, the data size of the map data is enormous. Therefore, the storage medium needs to have a sufficient storage capacity for storing this large-capacity map data.

In addition, it is preferable that the map data provided in the navigation device is updated as needed with changes in the map such as road connections. However, if the entire map data stored in the storage medium is updated to new map data, communication costs and processing time are relatively increased. Therefore, in recent years, navigation devices that acquire a portion of the map data that has changed as map difference data from the outside have been sold. In this navigation device, the acquired difference data and the original map data (this is used as initial map data) are stored in a storage medium, and the map is integrated to reflect the map update when the map data is used. May generate data.

Therefore, a storage medium for storing map data is required to be able to add map difference data (that is, rewriteability) in addition to large capacity.

JP 2003-035543 A

However, a storage medium that is generally large-capacity and rewritable is more expensive than a storage medium that is not rewritable. In addition, since the storage medium mounted on the vehicle is subject to vibrations and shocks when the vehicle is running, the data stored in the rewritable storage medium is more damaged than the data stored in the non-rewritable storage medium. Cheap. For this reason, a rewritable storage medium used in a vehicle is more expensive than a rewritable storage medium that is supposed to be used in a stationary state in order to improve vibration resistance.

The present disclosure has been made based on this situation, and an object of the present disclosure is a navigation device that can further reduce the cost required for a storage medium in a navigation device that uses both initial map data and map difference data. Is to provide.

In order to achieve the object, the navigation device of one example of the present disclosure is configured as follows. A first storage medium in which initial map data is stored in advance, a non-rewritable first storage medium, a first data access device that reads out the initial map data stored in the first storage medium, and a change with respect to the initial map data Is a storage medium that stores map difference data that describes and includes a rewritable second storage medium, and a second data access device that reads the map difference data stored in the second storage medium .

In such a configuration, initial map data having a relatively large data size is stored in a non-rewritable first storage medium, and map differential data having a relatively small data size is stored in a rewritable second storage medium. The

According to the above configuration, the rewritable second storage medium only needs to have a capacity for storing map difference data having a relatively small data size. Further, the first storage medium that stores the initial map data that occupies most of the entire map data including the initial map data and the map difference data is realized by a non-rewritable storage medium that is cheaper than a rewritable storage medium. The Therefore, the cost required for the storage medium can be further reduced than when the entire map data is stored in a rewritable storage medium. In addition, since map difference data is stored in a rewritable storage medium, addition and rewriting of map difference data accompanying update of map data can be handled. Furthermore, since the initial map data is stored in a non-rewritable storage medium, the data can be made less likely to be damaged than when stored in a rewritable storage medium.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings.
It is a block diagram showing an example of a schematic configuration of a navigation system according to the present embodiment, It is a block diagram showing the storage location of map difference data and initial map data, It is a figure showing an example of the configuration of the initial map data, It is a conceptual diagram for explaining the hierarchical structure of partition data, It is a figure which shows an example of a structure of division data, It is a figure for explaining the relation of a link, a segment, and a route, It is a figure which shows an example of a structure of difference data, It is a flowchart showing a flow of map difference data acquisition processing, It is a flowchart showing the flow of map providing processing, FIG. 10 is a block diagram illustrating an example of a schematic configuration of a navigation device according to Modification 1.

Hereinafter, an embodiment of the present disclosure will be described with reference to FIGS. FIG. 1 is a diagram illustrating an example of a schematic configuration of a navigation system 100 including a navigation device 1 according to the present disclosure and an external server 2. The navigation device 1 in this embodiment is mounted on a vehicle, and the vehicle on which the navigation device 1 is mounted is called a main vehicle or a host vehicle. The navigation device 1 and the external server 2 are configured to perform wireless communication with each other and transmit and receive data. In the present embodiment, the navigation device 1 is mounted on a vehicle, but may be a portable navigation device that can be brought into the vehicle.

(Configuration of the navigation device 1)
As shown in FIG. 1, the navigation device 1 includes a control circuit 10, a communication device 11, an external input interface (hereinafter simply referred to as I / F) 12, an input device 13, a position detector 14, a display device 15, a voice output device 16, A first data access device 17 and a second data access device 18 are provided. The control circuit 10, the communication device 11, the external input I / F 12, the input device 13, the position detector 14, the display device 15, the audio output device 16, the first data access device 17, and the second data access device 18 are: Each is connected so that it can communicate with each other.

The communication device 11 includes a transmission / reception antenna and communicates with the external server 2 via a communication network. As the communication device 11, for example, various devices such as an in-vehicle communication module such as DCM (Data Communication Module) used for telematics communication can be adopted.

The external input I / F 12 is an interface for the control circuit 10 to acquire vehicle state information from ECUs and sensors mounted on the main vehicle. For example, it is assumed that vehicle state information is input to the external input I / F 12 from an ECU or a sensor mounted on the main vehicle via an in-vehicle LAN or the like that complies with a communication protocol such as CAN. Examples of vehicle status information include shift position sensor signals, parking brake switch on / off signals, door courtesy switch on / off signals, ignition power on / off signals, passenger seat and rear seat sensor signals, etc. .

For example, a touch switch or a mechanical switch integrated with the display device 15 is used as the input device 13, and the user instructs the control circuit 10 to execute various functions by operating these switches.

The position detector 14 is a well-known geomagnetic sensor, gyroscope, vehicle speed (distance) sensor, and GNSS receiver for a GNSS (Global Navigation Satellite System) that detects the position of its own device based on radio waves from a satellite (sometimes Are also not shown). The position detector 14 sequentially detects the current position of the main vehicle (hereinafter referred to as vehicle position) based on the outputs of these sensors. The vehicle position is, for example, coordinates represented by latitude and longitude. Since these have errors of different properties, they are configured to be used while being complemented by a plurality of sensors. Depending on the accuracy of each sensor, the position detector 14 may be constituted by a part of the sensors described above.

The display device 15 displays text and images based on the input from the control circuit 10 and notifies the user of various information. The display device is arranged, for example, in the center of the instrument panel or in a combination meter provided in front of the driver's seat. The display device 15 is capable of full color display, for example, and can be configured using a liquid crystal display, an organic EL display, a plasma display, or the like. The voice output device 16 includes a speaker or the like, and outputs a guidance voice or the like based on an instruction from the control circuit 10.

The first storage medium 171 stores initial map data 3 installed at the beginning of shipment of the navigation device 1 as map data, as shown in FIG. The initial map data 3 represents a road network in a map recording area (for example, all over Japan) at the time of shipment. Since the initial map data 3 includes all road data and background data in the map recording area, and further voice data for voice guidance, the data size is enormous. Therefore, the first storage medium 171 having a storage capacity necessary for storing the initial map data 3 is selected. In the present embodiment, the first storage medium 171 may be a read-only storage medium. In the present embodiment, a DVD (so-called DVD-ROM) is used. Of course, the first storage medium 171 may be another read-only optical storage medium such as a CD, or a mask ROM.

The first data access device 17 is also referred to as the first storage device 17 or the read / write device 17, and includes the first storage medium 171 described above, and stores data stored in the first storage medium 171 based on instructions from the control circuit 10. The read data is output to the control circuit 10. In the present embodiment, since the first storage medium 171 is a DVD (so-called DVD-ROM), the first data access device 17 is a DVD driver for vehicles. The first data access device 17 may be a reading device according to the standard of the storage medium used as the first storage medium 171.

The second storage medium 181 stores the map difference data 4. The map difference data 4 is map data representing a new road network based on a difference from the road network based on the road network indicated by the initial map data 3. The map difference data 4 is composed of a group of difference data for each version. Versions are newer in time from the first version in numerical order, with increasing numerical values. For example, the difference data of the first version indicates the difference from the initial map data 3. In the difference data of the nth version other than the first version (n is an integer of 2 or more), the difference data of the current version (nth) is the difference from the difference data of the previous version (n-1). Show. A new road network is configured by integrating the initial map data and all versions up to the present version. In other words, for example, by integrating the first version difference data and the initial map data 3, the latest new road network at the time of creating the first version difference data is represented. The difference data of the second version indicates the difference after the first version, and is the latest at the time of creating the difference data of the second version by integrating the initial map data 3, the difference data of the first version, and the difference data of the second version. Represents the new road network. The second storage medium 181 is a map composed of a group of difference data from the first version to the latest version by storing the difference data up to the latest version included in the signal received from the external server 2 by the communication device 11. Difference data 4 (also referred to as a map difference data group) is stored.

Here, whereas the initial map data 3 includes all the data in the map recording area, the map difference data 4 stored in the second storage medium 181 describes the change from the initial map data 3. Therefore, the data size can be kept relatively small.

In the present embodiment, since the difference data of each version describes a difference from the previous version, the second storage medium 181 may store a plurality of difference data of different versions. . However, even when the map difference data 4 including all the plurality of difference data of different versions is stored, it is expected that the data size is sufficiently smaller than that of the initial map data 3. In addition, the data structure and update method of the map difference data 4 should just be designed suitably. An example of the configuration of the map difference data will be described later in detail.

In the present embodiment, the second storage medium 181 is realized by an SD card, but may be another flash memory. Further, it may be a storage medium other than the flash memory, which can electrically read the reference destination data. Further, it may be a storage medium such as a HDD (Hard Disk Drive) that reads data at a reference destination with a mechanical movement of a head.

The second data access device 18 is also referred to as a second storage device 18 or a read / write device 18, and has an insertion slot for inserting a standard SD card used as the second storage medium 181. 2 An SD card as the storage medium 181 is inserted and integrated. The second data access device 18 reads data stored in the second storage medium 181 based on an instruction from the control circuit 10 and outputs the read data to the control circuit 10. When a new version of difference data is acquired from the external server 2, the difference data is written to the second storage medium 181 based on an instruction from the control circuit 10.

In this embodiment, since the SD card is used as the second storage medium 181, the second data access device 18 is also a device that reads the SD card. However, according to the standard of the storage medium used as the second storage medium 181. Any reading device may be used. For example, when a USB memory is used as the second storage medium 181, a configuration including a USB insertion slot may be used. It is assumed that the insertion slot of the second storage medium 181 is provided at a position where the second storage medium 181 can be easily attached and detached by the user, for example, at a corner of the instrument panel.

The control circuit 10 is also referred to as a control device 10 and is configured as a normal computer. The control circuit 10 is configured as a normal computer 10A, a nonvolatile memory (not shown) such as a ROM or EEPROM, a volatile memory 10B such as a RAM, an I / O 10C, And a bus line (not shown) for connecting these components. The nonvolatile memory stores a program for executing various processes. The control circuit 10 performs various processes based on various information input from the communication device 11, the external input interface I / F 12, the input device 13, and the position detector 14 and a program stored in the memory. Examples of processing executed by the control circuit 10 include map display processing, facility search processing, route calculation processing, route guidance processing, and the like.

More specifically, in the map display process, a road map around the current position detected by the position detector 14 or around the area specified by the user through the input device 13 is displayed on the display device 15 at a scale specified by the user. Display on the screen. Further, in the facility search process, a word input by the user via the input device 13 is used as a search word, and the search word is matched from the facilities included in the initial map data 3 and the map difference data 4 (complete match). Acquire facilities that include not only partial matching but also partial matching. As another form of the facility search process, a specified point is narrowed down by selecting a genre of the facility, and a process that acquires facilities belonging to the genre selected by the user is also performed.

In the route calculation process, for example, a recommended route satisfying preset conditions such as distance priority and time priority from the departure point to the destination such as the current vehicle position is calculated using a known search method such as the Dijkstra method. .

In the route guidance process, the travel of the guidance route is guided. The guide route is a recommended route calculated by route calculation processing, and is a route determined by the user's route determination operation. For example, in the route guidance process, an electronic map showing the guidance route and the vehicle position of the main vehicle is sequentially displayed on the display device 15, and guidance voices to the destination are sequentially output from the voice output device 16, thereby Guide the run.

In addition, the control circuit 10 executes map difference data acquisition processing for downloading the difference data from the external server 2 and updating the map difference data 4. Further, the control circuit 10 generates map data of the section designated by the read request from the initial map data 3 and the map difference data 4 in response to the read request from the map display process, the route guidance process, etc. The map providing process to be provided is executed. These map difference data acquisition processing and map provision processing will be described in detail later using flowcharts.

(Configuration of external server 2)
The external server 2 includes a server side communication unit 21 and a server side storage unit 22 as shown in FIG. The server side communication unit 21 communicates with the navigation device 1 by a known wireless communication technique. The server-side storage unit 22 stores map difference data including difference data of all versions up to the latest version. When the external server 2 receives a signal for requesting an unacquired version of difference data from the navigation device 1, the navigation server 1 obtains the difference data not acquired by the navigation device 1 among the difference data stored in the server-side storage unit 22. Delivered to the device 1.

(Structure of initial map data 3)
Here, an example of the configuration of the initial map data 3 stored in the first storage medium 171 will be described. As shown in FIG. 3, the initial map data 3 includes map data for each section obtained by dividing the map recording area into a plurality of sections. Below, the data for every division with which initial map data 3 is provided are called main division data. A group of these main section data is configured as a data group in which corresponding main section data is arranged in an order according to the geographical arrangement of the sections. In FIG. 3, the K-th main section data in the arrangement order is expressed as K-th main section data.

Each of the main section data is configured as map data obtained by hierarchically expressing the road network in the corresponding main section by road case. As an example, when the road case is defined in three levels, upper, middle, and lower, the main division data is the third-tier data representing the road network with the highest road case in the corresponding division, and the road case is medium. The second layer data representing the higher-order road network, and the first layer data representing the road network with a lower road rating.

(About road case)
Here, the relationship between the above-mentioned road case and road type will be described. The types of roads include highways, national roads, prefectural roads, ordinary roads, and narrow streets. The road type is classified into those for long distance movement, medium distance movement, and short distance movement. It can be classified into any of the three levels. For example, highways and national roads can be defined as high-order roads, prefectural roads as medium-level roads, general roads and narrow streets as low-grade roads. According to such classification, the main division data represents the road network of the expressway and the national road in the division by the third layer data, and the road network of the prefectural road in the division by the second layer data. . Further, the first layer data is configured as data expressing the road network of the general road and the narrow street in the section.

(About the second layer data)
Next, the second layer data constituting the main partition data will be described. The second layer data is managed in units of sections (hereinafter referred to as “medium sections”) obtained by dividing the corresponding main section into a plurality of parts. Each of the 2nd layer data divided | segmented by the unit of medium division (this is set as medium division data) is comprised as map data showing the road network of the middle road rank in the corresponding middle division. More specifically, in this embodiment, the middle section data is divided into 16 parts by dividing the area corresponding to the main section into four parts in the vertical and horizontal directions as shown in FIG. The main section data corresponds to the section surrounded by a thick line in FIG. 4, and one middle section data corresponds to one square of the second layer data in FIG. A group of these middle section data (that is, second layer data) is configured as a data group in which corresponding middle section data is arranged in an order according to the geographical arrangement of the middle section. In FIG. 3, the K-th middle section data in the arrangement order is expressed as the Kth middle section data.

(About the first layer data)
The first layer data is managed in units of sections (hereinafter referred to as “small sections”) obtained by further dividing the corresponding middle section into a plurality of parts. Each of the 1st layer data divided | segmented by the subcompartment unit (this is made into subcompartment data) is comprised as map data showing the road network of the low-order road case in a corresponding subcompartment. In this embodiment, each of the small sections is divided into 16 parts by dividing the corresponding middle section into four equal parts. One small section data corresponds to each cell in the first layer in FIG. For this reason, the first layer data of one main section has a configuration including 256 pieces of small section data. A group of these subsection data (that is, first layer data) is configured as a data group in which corresponding subsection data is arranged in an order according to the geographical arrangement of the subsections. In FIG. 3, the K-th subcompartment data in the arrangement order is expressed as K-th subcompartment data. Hereinafter, each of the main partition data, the medium partition data, and the small partition data is also simply expressed as “partition data”.
(Detailed description of parcel data)
Next, the detailed configuration of the partition data will be described with reference to FIGS. However, since the configuration of the section data adopted here is the same as that described in the prior application (Japanese Patent Application No. 2011-026064) of the same applicant, the configuration will be briefly described here.

Each block data represents the connection relation of each road that constitutes the road network of the corresponding road class (for example, the middle-ranked road in the case of medium block data) existing in the corresponding block by link connection. As shown in FIG. 5, a link record for each link is provided. The link record includes link detailed information indicating a link length, a connection relationship with another link, and the like, and reference information to the coordinate record. A group of coordinate records represents the coordinates of a node (a connection point with another link) or a point in the link for each link indicated by the group of link records. That is, each of the coordinate records is configured as a record representing the coordinates of one of these points and the type of the point (node or coordinate holding point). The reference information to the coordinate record included in the link record is configured as information for referring to a coordinate record group representing the coordinates of the link and the end point corresponding to the link record.

(About segment records)
In addition, each section data is at the intersection with links other than lower ranks for links other than lower ranks (which are not relative to lower ranks here, refer to lower ranks in a three-stage road case). A segment record is provided for each segment having at least a linked link string as a unit. Therefore, the segment record is provided for the main division data and the middle division data, and is not provided for the small division data constituting the first layer data having the lowest road case. This segment record includes reference information to the link record corresponding to each link constituting the corresponding segment. This segment is defined so as not to straddle from one route defined in the route record to another route.

The segment (see FIG. 6) replaces the link of the main road expressed in a layer higher than the lowest layer in the conventional map data. Conventional map data can be handled efficiently in response to changes in the scale of the map to be displayed, such as layer data representing a detailed road network and layer data representing a main road network with a road case thinned out. It was configured with map data. On the other hand, in this embodiment, layer data for each road case is provided without adopting a conventional map data configuration in which main road information is duplicated in a plurality of layers. For this reason, the concept of segment is used to express the link of the upper-level main roads in the conventional map data in a format that refers to the link record.
(About route records)
Further, the partition data has a route record (see FIG. 5) for each link row belonging to the same route. The “route” referred to here is a concept larger than the segment, and is defined by, for example, a link string of the same road name and the same road number connected to one line in the corresponding section. Each route record includes route attribute information including information indicating whether the corresponding route is a toll road or a non-toll road, reference information to a segment record or link record, and reference information to a coordinate record. Reference information to the segment record or link record included in the route record refers to the segment record corresponding to each segment constituting this route when the link sequence constituting the corresponding route has the concept of segment. It is configured as information for In addition, when the link row constituting this route does not have the concept of segment, it is configured as information for referring to the link record corresponding to each link constituting this route. The reference information to the coordinate record included in the route record is configured as information for referring to a coordinate record group representing the coordinates of the inside of the route and the end point corresponding to the route record.

In this embodiment, by adopting such a data structure, it is possible to reduce the scale, etc., without adopting a map data structure in which main road information overlaps in multiple layers as in conventional map data. Accordingly, the link (segment) connection relationship can be acquired.

(Structure of map difference data 4)
The map difference data 4 is map data representing a new road network based on a difference from the road network based on the road network indicated by the initial map data 3. As shown in FIG. 7, the map difference data 4 is composed of a group of difference data for each version. More specifically, the difference data of the first version (difference data (Ver1 in the figure)) represents the new road network by the difference from the initial map data 3, and the difference data of each version other than the first version is The new road network is represented by the difference from the previous version.

In the map difference data 4, the difference data for each version has a data structure similar to that of the initial map data 3. That is, each difference data is composed of a data group for each section. Below, the data for every division with which difference data are provided are expressed as division difference data.

As shown in FIG. 7, the section difference data includes third layer difference data, second layer difference data, and first layer difference data. The third layer difference data has a road case in the corresponding section. The upper new road network is represented by the difference from the previous version. In addition, the second layer difference data represents a new road network with a middle road grade in the corresponding section by a difference from the previous version, and the first layer difference data has a lower road case in the corresponding section. The new road network is represented by differences from the previous version.

The definition of road case and section in the difference data is the same as the initial map data 3. For example, the 3/2/1 layer difference data constituting the difference data of the first version represents a new road network with a road case of upper / middle / lower in the corresponding section by the difference from the initial map data 3 .

That is, the map difference data 4 of the present embodiment has difference data for each version, each difference data has section difference data for each section, and each section difference data is classified according to a road case. The configuration includes layer difference data, second layer difference data, and first layer difference data. However, the difference data of each layer is different from the layer data constituting the initial map data 3, and the map obtained by combining the change of road (road difference) with the layer difference data up to the previous version and the initial map data 3. The configuration is represented by a command group that represents a correction location and correction content for the data. In particular, each layer difference data constituting the first version of the difference data has a configuration in which the amount of change in the road from the initial map data 3 is represented by a command group indicating a correction location and correction contents for the initial map data 3. Furthermore, in the difference data of each version, the section difference data of the section having no correction portion is configured as empty data.

地図 According to such a map data structure, as described above, unlike the conventional map data structure, it is possible to suppress the redundant description of the road network among a plurality of layers. Then, for each road case (layer), new road map data (updated map data) is generated at high speed by combining the section data constituting the initial map data 3 and the section difference data constituting the map difference data 4. can do.

(Map difference data acquisition process)
Here, the details of the process of acquiring the map difference data 4 performed by the control circuit 10 (hereinafter referred to as the map difference data acquisition process) will be described with reference to the flowchart shown in FIG. The flowchart shown in FIG. 8 is assumed to start when the external server 2 is connected via a wireless communication network. In addition, when downloading of unacquired difference data is charged, the configuration is started when an operation by the user to purchase the difference data is received.

Here, the flowchart or the process of the flowchart described in this application is configured by a plurality of sections (or referred to as steps), and each section is expressed as S100, for example. Further, each section can be divided into a plurality of subsections, while a plurality of sections can be combined into one section. Further, each section configured in this manner can be referred to as a device, module, or means. In addition, each of the above sections or a combination thereof includes not only (i) a section of software combined with a hardware unit (eg, a computer), but also (ii) hardware (eg, an integrated circuit, As a section of (wiring logic circuit), it can be realized with or without the function of related devices. Furthermore, the hardware section can be configured inside the microcomputer.

In S101, the control circuit 10 transmits to the external server 2 a transmission signal including the version of the difference data provided by itself. When the external server 2 receives the transmission signal transmitted by the control circuit 10, the external server 2 determines whether or not the map difference data 4 included in the transmission source navigation device 1 includes the latest version of the difference data. When the map difference data 4 included in the navigation device 1 includes the latest version of difference data, a signal indicating that there is no new difference data is returned to the navigation device 1. On the other hand, if the map difference data 4 does not include the latest version of difference data, a signal indicating that there is unacquired difference data is returned. An example of the case where there is unacquired difference data is a case where the user has purchased the difference data up to the old version but has not purchased the latest version of the difference data.

In S103, the control circuit 10 determines whether there is unacquired difference data based on the content of the signal returned from the external server 2. If there is unacquired difference data, S103 is YES and the process proceeds to S105. When there is no unacquired difference data, S103 is NO and the map difference data acquisition process is terminated.

In S105, the control circuit 10 transmits a request signal for requesting the external server 2 to distribute an unacquired version of differential data. In this embodiment, the difference data indicates a difference from the previous version of the difference data. Therefore, if there are a plurality of unacquired versions, the map may not be matched if only the latest version is acquired. There is. Therefore, when there are a plurality of unacquired difference data, it is requested to distribute all the unacquired versions. In response to a request signal from the control circuit 10, the external server 2 transmits a version of difference data that has not been acquired by the control circuit 10.

When receiving the difference data transmitted from the external server 2, the control circuit 10 stores the difference data in the second storage medium 181 and ends the map difference data acquisition process. In addition, when new difference data is added to the map difference data 4 by executing this map difference data acquisition process, the version number of the added difference data is notified to another application. .

(Map provision processing)
Here, the details of the map providing process performed by the control circuit 10 will be described with reference to the flowchart shown in FIG. The flowchart shown in FIG. 9 is started when there is a read request from another process (such as a map display process, a route search process, and a route guidance process). Hereinafter, an application that has made a read request is set as a read request source.

First, in S201, an initial map data reading process is performed, and the process proceeds to S203. In the initial map data reading process of S201, the section data of each section to be read designated by the read request (hereinafter referred to as designated section) is read from the initial map data 3. However, depending on the read request, the main section, the middle section, the small section, and a combination of these data are designated as the reading target. Here, the designated section data is read by referring to the layer data corresponding to the section to be read. That is, in S201, when main partition data is specified from the read request source, the specified main partition data (third layer data) is read from the first storage medium 171. Further, when the medium partition is designated from the read request source, the designated medium partition data is read from the first storage medium 171 with reference to the second layer data. When the sub-partition data is designated from the read request source, the designated sub-partition data is read from the first storage medium 171 with reference to the first layer data. These designated sections are also referred to as map areas.

In S203, it is determined whether or not the map difference data 4 corresponding to the designated section needs to be read based on the type of the read request. Here, for example, when the read request requests use of the map difference data 4, it is determined that the map difference data 4 needs to be read, and the read request does not request use of the map difference data 4 If it is, it is determined that reading of the map difference data 4 is unnecessary. The type of read request that needs to read the map difference data 4 may be stored in advance in a memory provided in the control circuit 10. Of course, as another aspect, the read request signal includes data indicating that the map difference data 4 needs to be used, and the functional block that performs the map providing process refers to the read request signal to map difference It may be determined whether the data 4 needs to be used.

If it is necessary to read the map difference data 4 corresponding to the designated section, S205 becomes YES and the process moves to S207. If it is not necessary to read out the map difference data 4 corresponding to the designated section, S205 is NO and the process proceeds to S220.

In S207, for each version of difference data provided in the second storage medium 181, a group of partition difference data of the partition corresponding to the specified partition is read out from the group of partition difference data constituting the difference data.

In S209, merge processing is executed and the process proceeds to S211. In the merge processing in S209, for each piece of section data read from the initial map data 3 in S201, the section data and the section difference data corresponding to the section data read out in S207 are combined, and a new one is added to each section. The correct partition data. Hereinafter, the section data obtained by the merge process is expressed as integrated section data.

More specifically, the integrated block data refers to the block difference data of each version in order, and the corresponding block data in the initial map data 3 is determined according to the command group indicating the correction location and the correction content indicated by the block difference data. It can be generated by modifying it.

For example, the main section data of the section included in the designated section is corrected according to the command group indicating the correction location and the correction content indicated by the difference data (third layer difference data) of the same main section read in S207. As a result, the main section data is combined with the above-mentioned section difference data of each version, and the road case indicated by the main section data is added to the upper road network, and the new road network indicated by the section difference data is higher. The integrated partition data reflecting the information is generated.

The section data of the medium section and the small section included in the specified section is also corrected according to the correction point and the command group indicating the correction contents indicated by the difference data of the same section read in S207. Through the above processing, map data (integrated map data) composed of integrated block data reflecting the information of the road network of all roads is generated. The integrated map data is stored in the volatile memory 10B.

In S211, the integrated map data composed of the integrated block data generated in the previous S209 is provided to the read request source, and the map providing process is terminated. Further, in S220, the map data composed of the section data corresponding to the designated section read from the initial map data 3 (this is referred to as unupdated map data in order to distinguish from the above-described integrated map data) is provided to the read request source. And this map provision process is complete | finished.

The application that is the read request source performs various processes using the map data (integrated map data and unupdated map data) provided in this way. For example, when the map display process is a read request source, the map data provided by the map providing process is used to display the area specified by the user and the road map around the current location at the scale specified by the user. It is displayed on the screen of the display device 15. When the route search process or the route guidance process is the read request source, the route to the destination designated by the user is searched and displayed, or the image is displayed through the display device 15 or the voice output device 16. And route guidance to the destination according to the current position by voice output. In these read request source applications, when the use of the integrated map data ends, the integrated map data stored in the volatile memory 10B is deleted.

(Summary of this embodiment)
In the above configuration, the initial map data 3 is stored in the non-rewritable first storage medium 171, and the map difference data 4 is stored in the rewritable second storage medium 181. If updated map data is requested (S205 YES), the initial map data 3 stored in the first storage medium 171 and the map difference data 4 stored in the second storage medium 181 , Merged to generate updated map data and provide it to the requester.

According to the configuration of the present embodiment, the capacity for storing the initial map data 3 having a relatively large data size is realized not by a rewritable storage medium but by a cheaper non-rewritable storage medium. The rewritable second storage medium 181 only needs to have a capacity for storing the map difference data 4 having a relatively small data size.

Accordingly, the cost can be reduced by the difference between the cost required for the rewritable storage medium having the storage capacity for storing the initial map data 3 and the cost required for the non-rewritable storage medium having the same storage capacity. . That is, the cost required for the storage medium can be further reduced than when the entire map data is stored in a rewritable storage medium.

At this time, since the data size of the initial map data 3 can be grasped in advance, the first storage medium 171 for storing the initial map data 3 can be designed to have a necessary and sufficient capacity to accommodate the initial map data 3. Further, since the map difference data 4 is stored in a rewritable storage medium, it is possible to cope with addition and rewriting of the map difference data 4 accompanying the update of the map data. Furthermore, since the contents of the initial map data 3 and the map difference data 4 are not rewritten, this embodiment can be used even in a country where editing map data without permission is prohibited.

(Effects on reading speed)
Incidentally, the map data is used for various applications provided in the navigation device 1 such as a map display process, a route search process, and a route guidance process. For this reason, it is preferable to store the map data in a storage medium with a high reading speed. In particular, in the present embodiment, since the integrated map data is generated every time a read request arrives, it is expected that data access to the second storage medium 181 is also frequently performed.

However, the data necessary to generate the data to be provided to the read request source may be distributed in various versions of difference data or may be a plurality of partition data stored in separate storage areas. It is done. In that case, the second data access device 18 must sequentially access the discontinuous reference destinations and read the data.

In general, since the HDD reads the data by mechanically moving the magnetic head, it is good at reading data stored continuously, but is not suitable for reading discontinuous data. Note that data is preferably stored continuously not only on the HDD but also on an optical disk such as a DVD or a CD. On the other hand, a flash memory such as an SD card can be read (or read / written and accessed) by electrically specifying a data reference destination (so-called address) without performing a mechanical head movement or the like. Therefore, the reading speed for discontinuous data is higher than that of the HDD.

In view of the above circumstances, in the present embodiment, an SD card, which is one of flash memories, is used as the second storage medium 181. Thereby, in the second storage medium 181 where discontinuous data reading is expected to be frequently performed, the reading speed can be increased as compared with the case where the HDD is used.

Further, since the initial map data 3 is written in the first storage medium 171 at the factory, the arrangement of data in the storage medium can be designed. Therefore, if the initial map data 3 is stored in the first storage medium 171 with an arrangement of data that is optimal for reading, the reading speed of the initial map data 3 can be compared with the reading speed of the map data in the conventional navigation device 1. Can be maintained or improved.

(Vibration resistance)
In addition, since the navigation device 1 used in a vehicle is subject to vibrations and shocks when the vehicle is running, the storage medium used in the vehicle has a requirement for data retention performance (this is assumed to be vibration resistance) against these vibrations. It is necessary to select in consideration. More specifically, if a scratch or the like is caused on the storage medium due to the vibration during traveling of the vehicle, a read error occurs and it becomes impossible to read the map data at that portion. As an example, in a conventional navigation device that stores the initial map data 3 and the map difference data 4 in a single storage medium (this is a comparative configuration), for example, a case where an HDD is used as the storage medium is assumed. I will explain.

In the HDD, a magnetic head moves on a magnetically coated magnetic recording plate, and data is read / written or accessed. When this magnetic head comes into contact with the magnetic recording plate in the hard disk drive due to vibration or impact while the vehicle is running, a part of the magnetic recording plate is damaged, and some map data on the magnetic recording plate cannot be read. It becomes possible.

Of course, if the map data is damaged, it becomes impossible to read the map data, which impairs user convenience. In particular, when the initial map data 3 which is a product at the time of shipment from the factory is easily damaged, that is, when the vibration resistance of the storage medium storing the map data is relatively low, the merchantability as a navigation device is impaired. It will be.

Therefore, a navigation device provided with a mechanism for improving the vibration resistance of a storage medium as in Patent Document 1 has been proposed. However, when such a mechanism for improving the vibration resistance is provided, the navigation device 1 is It becomes expensive.

On the other hand, in this embodiment, the initial map data 3 is stored on a read-only DVD. Thereby, it is possible to provide a navigation device 1 that is less expensive and less likely to damage the initial map data 3. Note that the storage medium mounted on the vehicle has various electronic devices and harnesses that connect them to the vehicle. Because it is mounted, it is exposed to electrical noise and magnetic noise. Therefore, a storage medium mounted on a vehicle must have resistance to electrical noise and magnetic noise in addition to vibration resistance. Furthermore, it is necessary to take measures against the possibility that the power supply that supplies power to the storage device suddenly drops due to the influence of vibration, electrical noise, magnetic noise, or the like. However, a semiconductor memory or magnetic memory that satisfies these requirements is more expensive than a normal semiconductor memory or magnetic memory. For this reason as well, the initial map data 3 occupying most of the data size of the map data is stored on an optical disk such as a DVD that is not easily affected by electrical noise or magnetic noise. Can be further reduced.

Further, since the first storage medium 171 and the second storage medium 181 are different storage media, even if the second storage medium 181 fails due to vibration or the like, only the second storage medium 181 needs to be replaced. Thereby, workability at the time of failure can be improved. Moreover, the workability at the time of a failure can be further improved by providing the second data access device 18 with a structure that allows the user to easily remove the second data access device 18 from the second data access device 18 because of the exchangeability at the time of the failure. For example, an insertion slot of an SD card as the second storage medium 181 may be provided at the corner of the instrument panel and the like, and the SD card insertion slot may be removed by pushing it lightly in the inserted state. In the case where a storage medium having high vibration resistance is used as the first storage medium 171, it is expected that the replacement frequency is low because it is relatively difficult to break. Therefore, the first data access device 17 may be arranged at a position where it is difficult for the user to remove.

Note that, by configuring the second storage medium 181 to be removable from the second data access device 18, the map difference data 4 provided in the second storage medium can be updated outside the vehicle. For example, the second storage medium 181 is removed from the navigation device 1 and connected to a computer provided outside the vehicle that can access the Internet, and the map difference data 4 included in the second storage medium is obtained by operating this computer. It may be updated. When the map difference data 4 can be updated by such a procedure, the navigation device 1 does not necessarily require the communication device 11 and can simplify the configuration of the navigation device 1.

(Modification 1)
The second storage medium 181 may be a storage medium included in the mobile terminal 1B such as a mobile phone brought into the vehicle. FIG. 10 is a block diagram showing an example of the configuration of the navigation device 1 in the first modification.

As shown in FIG. 10, the navigation apparatus 1 includes an on-vehicle device 1A and a mobile terminal 1B. The on-vehicle device 1A includes the same components 10 to 17 (not shown in FIG. 10) as the navigation device 1 in the above-described embodiment except for the second data access device 18 and the second storage medium 181. The second data access device 18 and the second storage medium 181 are provided in the mobile terminal 1B.

Further, the vehicle-mounted device 1A and the mobile terminal 1B each include a vehicle-mounted device-side communication unit 19A and a mobile terminal-side communication unit 19B, and are configured to be able to communicate with each other. For example, the vehicle-mounted device side communication unit 19A and the mobile terminal side communication unit 19B exchange map difference data by performing communication (hereinafter referred to as BT communication) in accordance with the Bluetooth (registered trademark) standard. Of course, the configuration is not limited to BT communication, and may be configured to be performed by wireless communication in accordance with a short-range wireless communication standard such as ZigBee (registered trademark) or a wireless LAN standard such as IEEE 802.11. Furthermore, it is good also as a structure performed by wired communication, such as USB communication.

Usually, the portable terminal 1B brought into the vehicle is often stored in a user's bag or a pocket of clothes or placed in a console box of the vehicle. In this case, the portable terminal 1B is fixed to the vehicle. It has not been. That is, since the second storage medium 181 is not fixed to the vehicle, the second storage medium 181 is less susceptible to vibrations and shocks when the vehicle is traveling than when mounted on a vehicle fixed to the vehicle.

Therefore, when the storage medium included in the mobile terminal 1B has vibration resistance equivalent to that of a storage medium that is assumed to be fixed to the vehicle, the storage medium included in the mobile terminal 1B is used as the second storage medium. By adopting the configuration to be used, it is possible to make the map difference data less likely to be damaged. Alternatively, the requirement for vibration resistance can be relaxed by using the storage medium included in the portable terminal 1B as the second storage medium. Further, with such a configuration, a mobile phone that is already widely used can be used as the second storage medium.

Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims

A first non-rewritable storage medium (171) in which initial map data (3) is stored in advance;
A first data access device (17) for reading the initial map data stored in the first storage medium;
A second storage medium (181) that is a storage medium for storing map difference data (4) describing a change with respect to the initial map data and is rewritable;
A navigation device (1) comprising: a second data access device (18) for reading the map difference data stored in the second storage medium.
In claim 1,
The navigation device further includes a volatile memory (10B),
The map difference data includes a plurality of versions of difference data in numerical order from the first version, the first version difference data describes a change from the initial map data, and the current version difference data other than the first version Describes the change from the previous version,
When generating the target map data reflecting the change in the target map area of the initial map data, the initial map data corresponding to the target map area and the map difference data corresponding to the target map area The target map difference data is read out, and the target map data of the target map area reflecting the change from the initial map data is generated by integrating the read out target initial map data and the target map difference data. A navigation device that stores the generated target map data in the volatile memory and erases the target map data stored in the volatile memory after the process of using the generated target map data is completed.
In claim 2,
In the second storage medium, the navigation device is accessed by electrically specifying a data reference destination.
In claim 3,
The navigation device, wherein the second storage medium is a flash memory.
In any one of Claims 1-4,
A portable terminal (1B) comprising the second storage medium and the second data access device;
An on-vehicle device (1A) including the first storage medium and the first data access device;
The mobile terminal and the vehicle-mounted device each include a communication unit (19A, 19B) that communicates with each other.
In any one of Claim 1 to 5,
The second storage medium includes a storage capacity smaller than the data size of the initial map data.
In any one of Claim 1 to 6,
The second storage medium can be removed from the second data access device by a user.
In any one of Claims 1-7,
The first storage medium is a non-rewritable optical storage medium.