JPH081641B2 - How to access map data of dual-purpose machine - Google Patents

Description

The present invention relates to a map data access method for a dual-purpose machine, and more particularly to a map data access method for a dual-purpose machine that uses a CD-ROM player for both navigation and audio.

<Prior Art> There is an automobile navigation system using a CD-ROM as a storage means for storing map data. Such an automobile navigation system stores a large amount of map data on a CD-ROM, and is provided with a display device and a position measuring device for measuring the current position of the vehicle, and the like.
The mark indicating the current position of the vehicle is fixedly displayed at a fixed position on the display screen, the map data corresponding to the vehicle position is read from the CD-ROM, the map is drawn on the display screen, and the map is displayed according to the movement of the vehicle. Scroll display.

The map stored in the CD-ROM has a hierarchical structure of a plurality of stages having different scales, for example, a hierarchical structure having different scales from level 9 to level 0. The level 0 map has view sets A, B, C having different display areas, and the level 0 map data is used for normal navigation. At level 0, view set A corresponds to the scale of level 0, view set B has more detailed map data than view set A, and view set C has more detailed map data than view set B. Have

To scroll the map, m × n (for example, 3 ×
3) The adjacent map images are developed in the video RAM (VRAM), and the range (window) for reading the map data from the VRAM is moved according to the movement of the vehicle to scroll the map on the display screen. Then, when the vehicle enters the adjacent area, new 3x3 adjacent map data is read from the CD-ROM so that the entered area is at the center, and these map data are used to generate a map image for 9 screens. After that, the map image is scroll-displayed on the CRT.

CD-ROM player for such navigation (CD-ROM
The drive) can also be used as an audio CD player. For this reason, conventionally, a changeover switch is provided in order to use the CD-ROM for both navigation and audio, and one of the navigation and audio is selected by the switch to serve as a CD-ROM player.

<Problems to be Solved by the Invention> However, such a conventional dual-purpose device has a problem that navigation cannot be performed when the CD-ROM player is used for audio.

In view of the above, an object of the present invention is to provide a map data access method for a dual-purpose machine capable of navigation even when the CD-ROM player is used for audio.

<Means for Solving the Problems> In the present invention, the above-mentioned problems are storage means (RAM) for storing map data read from a CD-ROM, and map data around the current vehicle position when there is no map access request. To read data from the CD-ROM and store it in RAM.
When using the M player for audio, when there is a map access request from the navigation host side, it is achieved by means of searching for the corresponding map data from the map data pre-read in RAM and outputting it to the host side. To be done.

<Operation> When the CD-ROM player is used for navigation and a map request is made from the navigation host side, the corresponding map data is retrieved from the CD-ROM and output to the host side. However, if there is no map request, the map data of a considerable range around the current vehicle position is read from the CD-ROM and stored in RAM. And when using the CD-ROM player for audio, if there is a map access request from the navigation host side, RAM
The corresponding map data is retrieved from the map data read in and output to the host side.

<Embodiment> FIG. 1 is a block diagram of an apparatus for realizing the method of the present invention. 1 is a navigation host, 2 is an audio circuit including an amplifier, 3a is a CD-ROM, 3b is an audio CD, and 4 is an audio CD.
Is a CD-ROM player (CD-ROM drive), which has a first unit 4a, a second unit 4b, and a map storage RAM 4c.

The first unit 4a has almost the same structure as that of the audio CD player, moves the pickup to a designated position, reads digital data from the CD-ROM 3a or CD3b, and performs error detection / correction processing on the read data. And output to the navigation side or the audio side.

The second unit 4b includes (1) a data input / output interface processing between the first unit, a data input section for performing synchronization detection, descrambling, etc. (2) A CD for the map data read from the CD-ROM 3a
-ECC data block that performs digital signal processing (various types of decoding, error processing, etc.) dedicated to ROM, (3) Host interface that holds commands from the navigation host 1 and sends map data to the host side (4) It has a processor 41 for controlling each of these parts.

The RAM 4c for map storage is controlled by the processor 41 to the CD-R.
Map data around the current vehicle position read from OM3a is stored. The storage capacity required for one map data is 16
Since it is K bytes, if it is assumed that 400 pieces of map data are stored, a capacity of about 6.4 M bytes is required.

5 is various keys for audio and navigation,
It is an operation panel provided with switches and the like, and is provided with a switch 5a for selecting whether to use the CD-ROM player 4 for navigation or for audio.
Reference numeral 6 is a DA converter that DA-converts audio digital data, and reference numeral 7 is a low-pass filter.

FIG. 2 is an explanatory diagram of map management data stored in the CD-ROM 3a. On the disc label LB of the CD-ROM 3a, a pointer P1 indicating the location where the leaf management information MCI is stored is recorded. The map leaf management information MCI is a pointer P21, P22, P23, ...
.. are arranged for the number of map sheets, and are arranged in descending order of map leaf level (scale level).

The map leaf record MRD pointed by the pointer Pij is
(1) scale level, (2) map leaf number, (3) child map leaf number and child map leaf number, (4) adjacent map leaf number, (5) view set management information VSA address (pointer P3), (6)
It includes longitudes at the left and right ends of the map leaf, and latitude data at the upper and lower ends.

The view set management information VSA has a pointer Pu to an upper layer view set, a pointer Pd to a lower layer view set, pointers Pn1 to Pn8 to adjacent view sets, unit data (map data) UND, and the like. Therefore, view set A,
In the relationship between B and C, as shown in FIG. 3, view set A
The pointer Pd of the view set B indicates the start address of the view set B, the pointer Pd of the view set B indicates the start address of the view set C, the pointer Pu of the view set C indicates the start address of the view set B, View set A by pointer Pu of B
Is specified. When the lower layer view set does not exist, the pointer Pd has a specific value (for example, all 1).

FIG. 4 is a flow chart of processing of the processor 41 which executes the map search output processing of the present invention. The overall operation of FIG. 1 will be described below with reference to this flowchart.

The processor 41 checks whether the navigation mode is selected by the switch 5a or the audio mode is selected (step 101), and if the navigation mode is selected, checks whether there is a map access request from the navigation host 1 (step 10).
2).

If there is a map access request from the navigation host 1 that knows the data indicating the current position (latitude and longitude) of the car, the map is the level currently displayed on the CRT,
The map data including the current vehicle position is retrieved from the CD-ROM 3 and sent to the navigation host 1 (step 103).

Then, it is checked whether or not the conditions for buffering the map data around the current vehicle position in the RAM4c are satisfied (step 104). If not satisfied, step 1
The processing from 01 is repeated. It is assumed that the map data around the current vehicle position is read from the CD-ROM 3a and stored in the RAM 4c or the contents thereof are updated every time the vehicle travels in the longitude direction or the latitude direction for a predetermined distance or more.

On the other hand, if the map data buffering condition is satisfied, the flag F for instructing the start of the map data buffering process is set to "0", and the processes from step 101 are repeated (step 105).

And when in navigation mode,
If there is no map request, the result in step 102 is "NO", so the processor 41 checks whether the flag F indicating whether or not map buffering should be performed next is "0" (step 10).
6).

If the flag is "0", the processor 41 CD-draws the leaf management information, the view set management information, and the map data for each level in a predetermined area (N area) adjacent to the area to which the current vehicle position belongs. It is read from ROM3 and stored in RAM4c (map buffering, step 107).

When the map buffering process is performed for a predetermined time T and all the map data within a predetermined range is stored in the RAM 4c, the flag F is set to "1" to complete the buffering process (step 108). After that, the processing from step 101 onward is repeated. If the storage of all the map data is not completed within the time T, the flag F remains "0" and the process returns to step 101 to repeat the subsequent processing. Then, while there is no map access request, the above process is repeated to store all the map data within the predetermined range in the RAM 4c, and the flag F becomes "1" in step 108.

If F = “1”, the buffering of the map data is not performed until the buffering condition is satisfied by moving a predetermined distance in a predetermined direction thereafter.

When the audio mode is selected by the switch 5a in the state where the map data is stored in the RAM 4c by the above processing, the CD-ROM player 4 becomes an audio device after that, and the audio data read from the CD is transferred to the DA converter 6 and the low-pass filter. It is input to the audio circuit 2 via the filter 7 and output from the speaker.

In the audio mode, the processor 41 checks whether or not there is a map access request from the navigation host 1 (step 110), and if not, repeats the processing from step 101 onward.

Now, also in the audio mode, the navigation host 1 performs the navigation process to scroll the map as the automobile moves. Then, when entering the adjacent area, the map access request is sent to the CD-ROM player 4
Send to.

As a result, since "YES" is obtained in step 110, the processor 41 searches for desired map data using the map data stored in the RAM 4a and outputs it to the navigation host 1 (step 111) and thereafter step 101 and thereafter. The process of is repeated.

In the above description, the RAM for storing the map is provided in the CD-ROM player, but it may be provided outside. FIG. 5 is a block diagram of an embodiment provided outside, 11 is a map buffer processing unit, a processor 11a, a map data storage RAM 11b
have. In FIG. 5, the same parts as those in FIG. 1 are designated by the same reference numerals. The processor 11a executes the map data buffering process of FIG. 4 and also performs a data relay process between the navigation host 1 and the CD-ROM 4, and stores the map data in the RAM 11b in the buffering process. According to the configuration of FIG. 5, since the map buffer processing unit is provided outside the CD-ROM player,
There is an advantage that the storage capacity can be easily expanded.

<Advantages of the Invention> According to the present invention as described above, when the CD-ROM player is used for navigation, the map data of a considerable range around the current vehicle position is displayed on the CD-RO in the state where there is no map request.
When the CD-ROM player is used for audio and the map access request is issued from the navigation host side, the corresponding map data is read from the RAM and searched for the corresponding map data. Since it is configured to output to the host side, navigation is possible even when the CD-ROM player is used for audio.

[Brief description of drawings]

FIG. 1 is a block diagram of a system for implementing the present invention, FIGS. 2 and 3 are map management data explanatory diagrams, FIG. 4 is a flow chart of map access processing of the present invention, and FIG. FIG. 6 is another block diagram of the system. 1 ... Navigation host 2 ... Audio circuit 3a ... CD-ROM 4 ... CD-ROM player 4c ... Map storage RAM 41 ... Processor

Claims (1)

[Claims] 1. A map data access method for a dual-purpose machine that uses a CD-ROM player for both navigation and audio. When the CD-ROM player is used for navigation, there is a map request from the navigation host side. In this case, the corresponding map data is retrieved from the CD-ROM and output to the host side.If there is no map request, the map data around the current vehicle position is read from the CD-ROM and stored in RAM. When the player is used for audio, when there is a map access request from the navigation host side, the map data pre-read in the RAM is searched for the corresponding map data and output to the host side. Access method for map data of dual-purpose machine.