JP3464883B2 - Navigation device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device which reads out map data recorded on a recording medium and displays a map image.

[0002]

2. Description of the Related Art Generally, a vehicle navigation system detects a current position of a vehicle, reads out map data in the vicinity of the vehicle from a recording medium, and displays a map image of the area around the vehicle on a screen. Further, a vehicle position mark indicating the own vehicle position is displayed at the center of the screen, and map data in the vicinity is scrolled as the vehicle advances centering on this vehicle position mark, and map information around the own vehicle position is always visible. It is like this.

The above-mentioned recording medium stores map data in a predetermined range (for example, the entire Kanto area), from which only map data around the vehicle position is read out.
A map image created based on the read map data is displayed on the screen. As this recording medium,
Hard disks and compact disks are generally used.

[0004]

By the way, when the map data is recorded in the recording medium and the map image is displayed on the display screen by reading out the map data as described above, the recording medium is partially scratched. When such a situation occurs, a read error occurs and the map data of that portion cannot be read, so that the map image cannot be displayed on the screen.

In particular, when a hard disk device is used, the magnetic recording plate and the magnetic head in the hard disk device come into contact with each other due to vibrations and shocks while the vehicle is running, and a part of the magnetic recording plate is damaged, resulting in magnetic recording. There is a possibility that some data on the board may become unreadable. There is a method of providing a mechanism for buffering a shock or the like against a failure of the hard disk device or the like due to the shock or the like. However, this method can reduce failures to some extent, but cannot completely avoid them, and thus is not an essential solution. As another method, there is a method of recording a correction code together with the map data and performing error correction when an error occurs in the read data, but the range that can be corrected is limited,
Even this method cannot completely prevent the data from being unreadable.

The present invention was created in view of the above points, and an object thereof is to provide a navigation device capable of avoiding an unreadable state of map data.

[0007]

In order to solve the above-mentioned problems, the navigation device according to the present invention has a second map data which is compressed in addition to the first map data for performing a normal navigation operation. Is stored in the second storage means, and when the vehicle is stopped, the third map data obtained by decompressing the compressed second map data is stored in the third storage means. Therefore, in a normal navigation operation, if a read error occurs when reading the above-mentioned first map data, the map data cannot be read by using the third map data that is decompressed when the vehicle is stopped. Can be avoided, and normal navigation operation can be continued.

Particularly, when a hard disk device is used as the above-mentioned first and second storage means, the magnetic recording plate and the magnetic head come into contact with each other during reading during traveling, and a part of the magnetic recording plate is damaged. , It may not be possible to read the data, but by decompressing the second map data and creating the spare third map data while the vehicle is stopped, the map data may be damaged due to damage to the magnetic recording plate. It is possible to avoid a situation in which the data cannot be read at all.

By storing the above-mentioned first and second map data in units of map sheets, it is easy to specify reading and writing of the map data, and it is easy and convenient to manage the map data.

Further, only the map data corresponding to the map leaf around the position of the own vehicle or only the map data corresponding to the map leaf including the road which has been traveled in the past is read from the second storage means and decompressed. By doing so, the disk capacity used by the decompressed map data can be minimized.

Further, as the above-mentioned normal navigation operation, for example, there is a map image display operation, and in this operation, when a read error occurs when reading the above-mentioned first map data, it is decompressed when the vehicle is stopped. By performing the normal navigation operation using the stored third map data, when the read error occurs, the map data cannot be read, the map image creation processing cannot be performed, and the map image cannot be displayed. Inconvenience can be avoided.

Further, instead of storing the compressed data and decompressing and storing the compressed data when the vehicle is stopped, the first map data itself or a part thereof is used as the fourth map data as the fourth map data.
The fifth map data may be stored in the storage means of No. 5, and the fifth map data obtained by copying a part of the fourth map data while the vehicle is stopped may be stored in the fifth storage means. In normal navigation operation,
Even when a read error occurs when reading the above-mentioned first map data, the normal navigation operation can be continued using the fifth map data copied when the vehicle is stopped.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A navigation apparatus to which the present invention is applied stores compressed map data in a hard disk device in addition to map data to be read out in a normal navigation operation, and stores map data around a vehicle position while the vehicle is stopped. It is characterized in that the compressed map data is partially decompressed and stored in the hard disk, and if a read error occurs when reading the map data, the decompressed map data is read. In this specification, the process of reducing the amount of data in a recoverable state is referred to as “compression”, and the process of restoring (or decompressing) the compressed data to the original data is referred to as “decompression”. Shall be performed.

(1) Overall Configuration of Navigation Device FIG. 1 is a diagram showing the overall configuration of a vehicle-mounted navigation device according to an embodiment of the present invention. The navigation device shown in FIG. 1 includes a navigation controller 1 that controls the entire system, a hard disk device 2 that stores various map data necessary for map display, route search, and the like.
A remote control (remote control) unit 4 as an operation unit for the driver and passengers to input various instructions, a GPS receiver 5 and an autonomous navigation sensor 6 for detecting the vehicle position and the vehicle direction, map images, A display device 9 for displaying the guide route on top of this and an audio unit 10 for outputting a predetermined guidance voice when the route guide is performed are provided.

Here, the above-mentioned map data is in units of map leaves separated by predetermined longitude and latitude, and the map data of each map leaf is specified by designating a map leaf number and can be read out. It will be possible. In addition, the map data for each map leaf includes a drawing unit composed of various data necessary for map display, a road unit composed of data necessary for various processes such as map matching, route search, route guidance, and the like. An intersection unit consisting of detailed data is included. In addition, the above-mentioned drawing unit includes data of a background layer necessary for displaying buildings, rivers, etc., and data of a character layer necessary for displaying names of cities, towns and villages, and the like.

In the hard disk device 2, an area for storing map data in advance and an area for writing decompressed map data are secured. FIG. 2 is a diagram showing a data storage area of the hard disk device 2. In the area where map data is stored in advance, basic map data 71 in which map data corresponding to all map leaves in a predetermined range (for example, the entire Kanto area) is recorded for each map leaf, and all of the map data 71 are stored. Stored is compressed map data 72 obtained by compressing map leaves for each map leaf. Compressed map data 72
Shows the basic map data 71 compressed and stored in order to minimize the used disk capacity of the hard disk device 2.

In the area for writing the decompressed map data (decompressed map data storage area 80), the decompressed map data in which the compressed map data 72 corresponding to the map leaf around the vehicle position is decompressed is written. Here, reading and writing of data from and to the hard disk device 2 is performed under the control of the navigation controller 1. The basic map data 71 described above corresponds to the first map data, and the compressed map data 72 corresponds to the second map data.

The remote control unit 4 includes a search key for giving a route search instruction, a route guidance mode key used for setting a route guidance mode, a destination input key, left / right / up / down cursor keys, a map reduction / enlargement key, and a display screen. Various operation keys such as a setting key for confirming the item at the cursor position above are provided, and an infrared signal corresponding to the operation state of the key is transmitted to the navigation controller 1.

The GPS receiver 5 receives radio waves transmitted from a plurality of GPS satellites and performs three-dimensional positioning processing or two-dimensional positioning processing to calculate the absolute position and heading of the vehicle (the vehicle heading is the present time). Calculation based on the vehicle position in the vehicle and the vehicle position one sampling time ΔT before), and outputs them together with the positioning time. Further, the autonomous navigation sensor 6 includes an angle sensor 12 such as a vibration gyro that detects a vehicle rotation angle as a relative azimuth and a distance sensor 14 that outputs one pulse for each predetermined traveling distance. Detect position and orientation.

The display device 9 displays the map information of the surrounding area of the own vehicle together with the own vehicle position mark, the departure point mark, the destination mark, and the like on the map based on the image data output from the navigation controller 1. Display the guide route.

(2) Detailed Configuration and Operation of Navigation Controller Next, the detailed configuration of the navigation controller 1 shown in FIG. 1 will be described. The navigation controller 1 includes a map buffer 16 for displaying a predetermined map on the display device 9 based on the map data read from the hard disk device 2, a map read control unit 18, a data decompression unit 19, a map drawing unit 20, a VRAM 22, The read control unit 24, the image synthesizing unit 26, the data storage unit 30 for performing the calculation of the own vehicle position, the map matching process, the route search process, the route guidance process and displaying the result, and the vehicle position / azimuth calculation unit 32. , Map matching processing unit 3
4, route search processing unit 36, guidance route memory 38, guidance route drawing unit 42, mark image generation unit 44, intersection guidance unit 4
6, a remote controller control unit 60 for displaying various operation screens to the user and transmitting operation instructions from the remote controller unit 4 to each unit, a cursor position calculation unit 62, and an operation screen generation unit 64.

The map buffer 16 is for temporarily storing the map data read from the hard disk device 2. When the map read control unit 18 calculates the screen center position, the map read control unit 18 sends to the hard disk device 2 an instruction to read the map data in a predetermined range including the screen center position, and the map necessary for displaying the map is displayed. The data is read from the hard disk device 2 and stored in the map buffer 16. For example, the map data corresponding to the four map sheets including the screen center position are read out and stored in the map buffer 16.

The data decompression unit 19 judges whether the own vehicle is running or stopped, and if it is stopped, decompresses a part of the compressed map data 72 corresponding to the map leaves around the own vehicle and decompresses the map data. A process of writing in the storage area 80 is performed. Data decompression unit 1
Regarding the decompression operation of the compressed map data 72 in 9,
It will be described later.

The map drawing section 20 creates a map image required for display based on the drawing units included in the map data of the four map sheets stored in the map buffer 16. The created map image data is stored in the VRAM 22, and the read control unit 24 reads the map image data for one screen. The image synthesizing unit 26 performs image synthesizing by superimposing the respective image data output from the mark image generating unit 44, the intersection guidance unit 46, and the operation screen generating unit 64, which will be described later, on the read map image data. The combined image is displayed on the screen of the display device 9.

FIG. 3 is a diagram showing the relationship between the map image data stored in the VRAM 22 and the display image read by the read control unit 24. In the figure, each of the areas A to D is a map image drawn based on the drawing unit included in the map data of the four map sheets read from the map buffer 16, and the map images of these four map leaves are shown. The data is stored in the VRAM 22. Further, the area P is centered on the screen center position O and is read by the read controller 24 from the VRAM 2
2 shows the display image data read from the area 2. When the vehicle runs and the center position O of the screen corresponding to the position of the vehicle moves, the area P moves along with it and the screen is scrolled.

The data storage unit 30 sequentially stores the positioning position (vehicle position) data output from the GPS receiver 5. Further, the vehicle position / azimuth calculation unit 32 calculates an absolute own vehicle position and azimuth from the relative position and azimuth of the own vehicle output from the autonomous navigation sensor 6. The map matching processing unit 34 uses the GP stored in the data storage unit 30.
It is determined whether or not the own vehicle position by the S receiver 5 or the own vehicle position calculated by the vehicle position / azimuth calculation unit 32 exists on the road of the map data, and if it deviates from the road, it is calculated. The process of correcting the vehicle position is performed. Pattern matching and projection are known as typical methods of map matching.

When the destination input key is pressed after the cursor is moved to a specific position on the map by operating the cursor key of the remote control unit 4, the route search processing unit 36
At this time, the cursor position calculated by the cursor position calculation unit 62 is set as the destination of the route search. The set destination data is stored in the guide route memory 38.
Further, when the search key of the remote control unit 4 is pressed, the route search processing unit 36 sets the own vehicle position corrected by the map matching processing unit 34 as a departure place and stores it in the guide route memory 38. , A search is made for a travel route connecting the starting point and the destination stored in the guide route memory 38 under predetermined conditions. For example, the guide route that minimizes the cost is set under various conditions such as the shortest time, the shortest distance, and the general road priority. The Dijkstra method and the lateral search method are known as typical methods for route search. The guide route thus set by the route search processing unit 36 is stored in the guide route memory 38.

The guide route drawing unit 42 uses the guide route memory 3
V from the guidance route data stored in 8 at that time
The one included in the map area drawn in the RAM 22 is selected, and the guide route which is overlaid on the map image and thickly emphasized with a predetermined color is drawn. The mark image generation unit 44 generates a vehicle position mark or a cursor mark having a predetermined shape at the vehicle position after the map matching process.

The intersection guidance unit 46 is for guiding the intersection at which the vehicle is approaching with a display image and voice, and at the time of actual route guidance, the vehicle approaches within a predetermined distance from the intersection in front of the guidance route. At this time, the guide map of the approaching intersection (enlarged view of the intersection, destination, traveling direction arrow) is displayed on the screen of the display device 9 and the traveling direction is voiced through the audio unit 10.

The above-mentioned hard disk device 2 corresponds to the first, second, third, fourth and fifth storage means, and the data decompression section 19 corresponds to the decompression means. When focusing on the map image display operation, the map buffer 16,
Map read control unit 18, map drawing unit 20, VRAM 22,
The read control unit 24 and the like correspond to the navigation operation means. When focusing on the map matching operation, the map buffer 16, the map read control unit 18, the map matching processing unit 34, and the like correspond to the navigation operation means. When focusing on the guide route setting and the route guide operation, the map buffer 16, the map read control unit 18, the route search processing unit 36, the guide route memory 38, and the guide route drawing unit 42.
Etc. correspond to the navigation operation means.

(3) Operation of decompressing and reading data by the navigation device The entire navigation device and the navigation controller 1 have the above-mentioned configuration. Next, a detailed operation of the decompression processing of the compressed map data 72 in the data decompression unit 19 and a detailed operation when a read error occurs in reading the map data from the hard disk device 2 will be described.

The decompression process of the compressed map data 72 is performed by the hard disk drive 2 due to vibrations and shocks generated while the vehicle is running.
Since the magnetic recording plate and the magnetic head contact each other and a part of the magnetic recording plate may be damaged, this is performed while the vehicle is stopped. The decompression of the compressed map data 72 is performed on the compressed map data 72 corresponding to the basic map data 71 around the position of the vehicle that is the target of reading during normal traveling.
For example, the compressed map data 72 corresponding to eight adjacent drawing leaves centering on the drawing leaf including the vehicle position is read and decompressed.

FIG. 4 is a diagram showing the relationship between the current vehicle position and the map data of the map leaf to be decompressed. In the figure, a point P indicates the current vehicle position, and regions E to M indicate map leaves adjacent to the current vehicle position. For example, when the vehicle is stopped at the position of the point P, it corresponds to the leaves of the adjacent regions E, F, G, H, J, K, L, and M around the region I including the point P. The compressed map data 72 to be read is read out, and the decompressed map data decompressed is written in the decompressed map data storage area 80.

In FIG. 5, the decompressed map data 73 obtained by decompressing a part of the compressed map data 72 is the decompressed map data storage area 80.
It is a figure which shows the data storage state after being written in. For example, in the example shown in FIG. 4, the decompressed map data 73 corresponding to the drawing leaves of the adjacent regions E, F, G, H, J, K, L, and M around the region I including the point P is decompressed. It is written in the map data storage area 80. The decompressed map data 73 described above corresponds to the third map data.

FIG. 6 shows an operation procedure when the compressed map data is decompressed while the vehicle is stopped.
The operation procedure of is shown. The data decompression operation by the data decompression unit 19 will be described below. Normally, the data decompression unit 19 determines whether the vehicle is running or stopped (step 100). This determination is performed, for example, based on the absolute position of the vehicle for each positioning time transmitted from the GPS receiver 5, or based on the presence / absence of a pulse output from the distance sensor 14. Here, if the vehicle is traveling, the process returns to step 100, and if the vehicle is stopped,
The process moves to the next step.

Next, the data decompression unit 19 obtains information on the current vehicle position from the vehicle position on the map calculated by the map matching processing unit 34 (step 101), and obtains the current vehicle position. Then, it is determined from the contents of the decompressed map data 73 whether the compressed map data 72 needs to be newly decompressed (step 102). If not, return to step 100. For example, when the own vehicle position when the decompression process is performed last time and the current own vehicle position are included in the same map leaf,
Since the necessary decompressed map data 73 has already been stored in the decompressed map data storage area 80, the process returns to step 100. If it is necessary, the process moves to the next step.

Next, the data decompression unit 19 compresses the map data corresponding to the eight adjacent drawing leaves around the drawing leaves including the own vehicle position based on the current own vehicle position and the compressed map data 7
2 is read out (step 103), and the compressed map data read out in units of map sheets are decompressed and then written in the decompressed map data storage area 80 (step 104). Then, the process returns to step 100 and the process is repeated.

Next, a detailed operation when a read error occurs in reading the map data from the hard disk device 2 will be described. The map reading control unit 18 mainly reads the map data during normal traveling. The map read control unit 18 is usually the hard disk device 2
The map data of the four map sheets is read out from the basic map data 71 stored in and stored in the map buffer 16.

When a read error occurs in the reading of the basic map data 71, the decompressed map data 73 corresponding to the portion where the read error occurs is read from the decompressed map data storage area 80. , Are stored in the map buffer 16. This read error is caused when the magnetic recording plate of the hard disk device 2 comes into contact with the magnetic head due to vibration or shock generated while the vehicle is running, and a part of the magnetic recording plate is damaged, making it impossible to read data. Occurs when data cannot be read correctly due to the life of the magnetic recording plate.

FIG. 7 is a flow chart showing the operation procedure of reading the map data, and mainly shows the operation procedure of the map read control unit 18. The map data read operation by the map read control unit 18 will be described below. Map read control unit 18
Determines whether or not it is necessary to newly read the map data and update the contents of the map buffer 16 based on the current vehicle position and the contents of the map data of the map leaf stored in the map buffer 16. (Step 200). If it is not necessary, the process of step 200 is repeated, and if necessary, the next process is performed.

Next, the map read control unit 18 calculates the screen center position from the processing result of the pattern matching processing unit 34, and obtains the map data corresponding to the four drawing leaves including the screen center position from the basic map data 71. Read (step 20)
1). For example, in FIG. 4, it is assumed that map data of regions H, I, K, and L is stored in the map buffer 16 and the vehicle is traveling from the vehicle position P to the region F. And from the driving direction, the areas F, I,
The corresponding map data of the G and J map leaves is the basic map data 7.
It is read from 1.

Next, the map read control section 18 judges whether or not there is a read error in reading from the basic map data 71 (step 202). Whether or not this read error has occurred is stored, for example, with an error detection code together with the map data, and is determined based on this error detection code at the time of reading. If there is no read error, the map data corresponding to the four map sheets read from the basic map data 71 is stored in the map buffer 16 (step 20).
4) The process is repeated by returning to step 200.

When there is a read error, the map read control unit 18 reads the decompressed map data 73 corresponding to the map sheet in which the read error has occurred from the decompressed data storage area 80 (step 203), and the read error in step 201. The map data excluding the map data corresponding to the map leaf in which the error occurred and the map data read in step 203 are stored in the map buffer 16 (step 204), and step 200
Return to and repeat the process.

In this way, a predetermined navigation operation is performed based on the drawing unit, road unit and intersection unit contained in the map data stored in the map buffer 16. For example, the drawing unit is used by the map drawing unit 20 to create a map image required for display. The created map image data is stored in the VRAM 22, and the read control unit 24 reads the map image data for one screen. The image synthesizing unit 26 performs image synthesizing by superimposing the respective image data output from the mark image generating unit 44, the intersection guidance unit 46, and the operation screen generating unit 64 on the read map image data to synthesize the image. The displayed image is displayed on the screen of the display device 9.

Further, for example, the road unit is used in the map matching processing section 34 and the route search processing section 36 for processing such as map matching processing, route guidance setting and route guidance. The map matching processing unit 34 determines whether the own vehicle position by the GPS receiver 5 stored in the data storage unit 30 or the own vehicle position calculated by the vehicle position / azimuth calculation unit 32 exists on the road of the road unit. Is determined, and if the vehicle deviates from the road, a process of correcting the own vehicle position obtained by calculation is performed. When the search key of the remote control unit 4 is pressed, the route search processing unit 36 sets the own vehicle position corrected by the map matching processing unit 34 as the departure point and stores it in the guide route memory 38. A travel route connecting the starting point and the destination stored in the guide route memory 38 under predetermined conditions is searched.
The guide route thus set by the route search processing unit 36 is stored in the guide route memory 38.

Further, for example, the intersection unit is used in the intersection guide section 46 to provide guidance at the intersection where the vehicle is approaching with a display image and voice. At the time of actual route guidance, when the own vehicle approaches within a predetermined distance from the intersection in front of the guidance route, a guide map (enlarged intersection, destination, traveling direction arrow) of this approaching intersection is displayed on the screen of the display device 9. Along with the display, the direction of travel is announced by voice through the audio unit 10.

As described above, in the navigation device of this embodiment, the hard disk device 2 stores the compressed map data that is compressed in advance in addition to the map data that is normally read.
The map data corresponding to the map leaf around the vehicle position is decompressed from the compressed map data while the vehicle is stopped and stored in the hard disk device 2 to prevent vibrations and shocks during vehicle running. As a result, the magnetic recording plate of the hard disk device 2 comes into contact with the magnetic head, a part of the magnetic recording plate is damaged, or the map data to be normally read cannot be correctly read due to the life of the magnetic recording plate. In this case, by reading from the map data that is decompressed while the vehicle is stopped, it is possible to avoid an inoperable state of navigation operation due to the occurrence of a map data read error. Further, by reading the compressed map data and writing the decompressed map data while the vehicle with less vibration and shock is stopped, it is possible to avoid damaging the magnetic recording plate in the area where the compressed map data is stored. be able to. Further, by decompressing and storing the compressed map data by a required amount, the disk usage capacity can be minimized. Further, by reading the basic map data and the compressed map data in units of map sheets, the data can be easily managed, which is convenient.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention.

For example, in the above-described embodiment, as shown in FIG. 4, an example of decompressing the map data of the eight drawing sheets adjacent to the drawing sheet including the position of the vehicle has been shown. It is also possible to predict the traveling area from the map and decompress the map data of an appropriate number of map leaves included in this prediction range.

Further, when the guide route is set by the route search processing unit 36, the traveling route is known in advance, so that even if the map data of the appropriate number of map leaves included in the traveling route is decompressed. Good.

Also, a travel route which has been traveled in the past and has a high travel frequency is learned and recorded (for example, a memory (not shown) for travel recording is provided in the navigation controller 1 and recorded). However, it is also possible to decompress an appropriate number of map data of the drawing leaves included in the travel route.

Although the map data is compressed and decompressed in units of map sheets, it may be compressed in an appropriate data size. For example, it may be performed for each drawing unit, road unit, and intersection unit, or for each background layer and character layer.

Further, although the case where the map data is stored in the hard disk device 2 is shown as an example, a device using a storage medium other than that may be used. For example, instead of the hard disk device 2, a storage device using MO, MD (mini disk), CD, DVD or the like as a storage medium, or a semiconductor memory can be used. However, when a read-only storage medium is used, it is necessary to provide a storage device capable of writing another data for storing the decompressed map data.

In addition to the basic map data 71 that is normally read out, compressed map data 72 that has been previously compressed.
An example in which the hard disk device 2 is stored in
Without compressing, the same contents as the map data to be read normally or a part of the copy map data is stored separately and the map data corresponding to the map leaf around the own vehicle position is copied while the vehicle is stopped. By providing a data copying section (corresponding to copying means) for writing in the device 2,
When a read error occurs during the reading of the basic map data 71, it is possible to avoid the unreadable state of the map data by reading the preliminary map data copied while the vehicle is stopped. The above-mentioned copy map data corresponds to the fourth map data, and the preliminary map data corresponds to the fifth map data.
It corresponds to the map data of.

[0055]

As described above, according to the present invention, in a normal navigation operation, when a read error occurs when reading the first map data, the third navigation that is decompressed when the vehicle is stopped is performed. By using the map data, the unreadable state of the map data can be avoided, and the normal navigation operation can be continued.

In particular, when the hard disk device is used as the above-mentioned first and second storing means, a part of the magnetic recording plate may be damaged during traveling, but the second map is stopped while the vehicle is stopped. By reading the data and decompressing it to create the spare third map data, it is possible to avoid the unreadable state of the map data.

By storing the above-mentioned first and second map data in units of map sheets, it is easy and convenient to manage the map data. Also, by decompressing only the map data corresponding to the map leaves around the vehicle position, or only the map data corresponding to the map leaves that include roads that have been traveled in the past, the required disk space can be minimized. Can be Further, as the normal navigation operation described above, for example, there is a map image display operation, and it is possible to avoid the inconvenience that a read error occurs when reading the first map data and the map image cannot be displayed. .

Further, instead of storing the compressed data and decompressing and storing the compressed data when the vehicle is stopped, the first map data itself or a part thereof is used as the fourth map data as the fourth map data.
The fifth map data may be stored in the storage means of No. 5, and the fifth map data obtained by copying a part of the fourth map data while the vehicle is stopped may be stored in the fifth storage means. By using the fifth map data when a read error occurs when reading the first map data, the unreadable state of the map data can be avoided.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a vehicle-mounted navigation device of an embodiment to which the present invention is applied.

FIG. 2 is a diagram showing a data storage state of a hard disk device before storing decompressed map data.

FIG. 3 is a diagram showing a relationship between a drawing area and a display area of a VRAM.

FIG. 4 is a diagram showing a relationship between a vehicle position and map data corresponding to a map leaf to be decompressed.

FIG. 5 is a diagram showing a data storage state after storing the decompressed map data in the hard disk device.

FIG. 6 is a diagram showing an operation procedure of a data decompression operation.

FIG. 7 is a diagram showing an operation procedure of a data read operation.

[Explanation of symbols]

1 Navigation controller 2 hard disk drive 4 Remote control unit 5 GPS receiver 6 Autonomous navigation sensor 9 Display device 16 map buffer 18 Map read control unit 19 Data decompression section 34 Map Matching Processing Unit

Claims (6)

(57) [Claims] 1. A first storage means for storing first map data required for navigation operation, a second storage means for storing second map data obtained by compressing the first map data, and A third storage unit that stores third map data obtained by decompressing the second map data, a stop detection unit that determines whether the vehicle is stopped, and the stop detection unit that stops the vehicle. When it is determined to be in
And a decompression means for reading and decompressing the second map data stored in the second storage means, and storing the obtained third map data in the third storage means. When the first map data stored in the first storage means is read and a predetermined navigation operation is performed, when the first map data to be read cannot be read normally, the first map data is read instead. Navigation operation means for reading out the third map data stored in the storage means of No. 3 and performing the predetermined navigation operation. 2. The navigation device according to claim 1, wherein at least the first and second storage means are hard disk devices. 3. The first map data and the second map data according to claim 1, wherein each of the first map data and the second map data can be read in a unit of a map leaf, and the decompressing means can read the data around a vehicle position. A navigation device, wherein the second map data corresponding to a map leaf is read out from the second storage means and decompressed. 4. The first map data and the second map data according to claim 1, wherein each of the first map data and the second map data can be read in a unit of a map leaf, and the decompression means has run in the past. A navigation device, wherein the second map data corresponding to a map leaf including a certain road is read from the second storage means and decompressed. 5. The navigation operation means according to claim 1, wherein the navigation operation means reads the first map data read from the first storage means or the third map data read from the third storage means. A navigation device characterized by displaying a map image based on map data. 6. A first storage means for storing first map data required for navigation operation, a fourth storage means for storing fourth map data obtained by copying the first map data, and Fifth storage means for storing fifth map data obtained by copying the fourth map data corresponding to the vicinity of the vehicle position from the fourth storage means, and determining whether the vehicle is stopped When the vehicle stop is detected and the vehicle stop detection section determines that the vehicle is stopped.
To a copying means for said fourth storage are stored in the unit fourth reads map data copied, the resulting fifth map data stored in said fifth storage means, said first When the first map data stored in the first storage means is read and a predetermined navigation operation is performed, when the first map data to be read cannot be read normally, the first map data is read instead. 5. A navigation device, comprising: navigation operation means for reading the fifth map data stored in the storage means 5 and performing the predetermined navigation operation.