JPH01143915A - On-vehicle navigation device - Google Patents

Abstract

PURPOSE:To transfer data required to display the estimated current position of a vehicle at all times by writing the necessary data in a buffer memory by using an area opposite to and distant from a nondeficient part when the necessary data is deficient. CONSTITUTION:An image memory 23 is stored with map data of one screen required for a display on a display device 8. Then a buffer memory 22 is stored with nine map blocks which are arrayed in three rows and three columns, i.e. one block of one picture required for the display on a wide-area map consisting of the device 8 and its adjacent map blocks. Here, a central processing unit 24 transfers the necessary map data from the memory 22 to the memory 23. Further, if the very data to be transferred to the memory 23 at the time of vehicle movement has a deficient part as compared with the data in the memory 22, the data is stored in the memory 22 by using the area opposite to and distant film the nondeficient part and also the transfer to the memory 23 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an on-vehicle navigation device that can efficiently update a map as the vehicle moves.

[Prior Art] In-vehicle navigation devices display the vehicle's current location along with a road map on a display device inside the vehicle to help guide the vehicle to its destination. It can be included in a navigation system in a broad sense that estimates the current location of a moving object.

The conventional in-vehicle navigation device l shown in FIG.
The current location is basically estimated by a central processing unit 4 connected to a mileage sensor 3 and the like. CD-ROM through a reading device 5 called a media controller.
The road map read from the road map information recording medium 6 is first stored in the buffer memory 7, then transferred to the image memory 10, and displayed on the screen of the display device 8 together with the estimated current location. The display device 8 controlled by the display control device 9 can store an image memory 10, and through key operations on a keyboard device 11 connected to the central processing device 4, a line connecting the departure point and the destination in the shortest distance can be displayed. The route closest to can also be displayed. Therefore, the driver can select a route to the destination while comparing the shortest route to the destination displayed on the screen of the display device 8 with the estimated current location.

In the case of this example, the road map recorded on the road map information recording medium 6 is divided into a plurality of map blocks for the entire country of Japan using the display frame of the display device 8 as a unit, and a block number is assigned to each map block. be.

Therefore, the calling of a map block is carried out with the block number, and the map block once called into the buffer memory 7 is updated at the moment when the vehicle crosses the boundary of the map block.

[Problems to be Solved by the Invention] The conventional in-vehicle navigation device 1 described above is configured to update the map block displayed on the display device 8 immediately before the vehicle moves to an adjacent map block. If surrounding maps are read in advance as the estimated current location moves, map data within the same block is often forced to be distributed and stored in the buffer memory 7, which has a limited storage capacity. Yes, if you do,
Not only will the continuity of the map be destroyed, but when picking up and transferring distributed map data, it will take time to transfer, especially when moving to multiple adjacent map blocks. In such a case, it may be necessary to update the next adjacent map block before the first read adjacent map block has been updated, and in such a case, the reading of the adjacent map block may be delayed. There have been problems in that a portion of the road map is not displayed on the screen of the display device, resulting in a blank area sometimes occurring.

Means for Solving Problem U] This invention solves the above problems, and includes a display device that displays the estimated current location of a vehicle, and a display device that stores map data of map blocks displayed on the display device. An image memory, a buffer memory capable of storing a wide area map block consisting of one map block and its adjacent map blocks, and map data required by the image memory are stored in the wide area map data stored in the buffer memory. If even a part is missing, this missing part is written in a buffer memory using an area spaced apart from the non-missing part, and data transfer control means for transferring divided blocks of map data required by the image memory from this buffer memory. The present invention is characterized in that it is configured by providing the following.

[Operation] This invention stores map data of a map block displayed on a display device that displays the estimated current location of a vehicle from a buffer memory that can store a wide area map block consisting of one map block and its adjacent map blocks. If the map data transferred to the image memory and required by the image memory is missing even in part from the wide area map data stored in the notation buffer memory, the missing part is separated from the non-missing part using an area. The map data necessary for displaying the estimated current location of the vehicle is accurately and quickly transferred to the image memory by writing it into the buffer memory and transferring the map data required by the image memory from the buffer memory in divided blocks.

[Embodiments] Examples of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a circuit configuration diagram showing an embodiment of the in-vehicle navigation system of the present invention, and FIGS. 2 and 3 are for explaining the division determination operation of map data by the central processing unit shown in FIG. 1, respectively. The flowchart and diagram for explaining the map data division case, Figure 3.4, are as follows:
2 is a flowchart for explaining the transfer operation of map data by the central processing unit shown in FIG. 1, and a flowchart showing details of the transfer operation for each division case, respectively.

In FIG. 1, the in-vehicle navigation device 2I displays map data stored in a buffer memory 22 capable of storing nine map blocks arranged squarely in three rows and three columns on a display device 8. The central processing unit 24 is provided with a map data transfer control function for transferring the map data to the image memory 23 which can store one screen worth of map data required for the image processing.

The display device 8 shown in the embodiment has a horizontal RX (=6
It has a display area (square ABDC) consisting of 40 dots) and vertical RY (=200 dots) pixels, and the area of this 640 x 200 dot display frame is used as a unit to display multiple road maps of Japan. It is divided into blocks. Therefore, eight map blocks are adjacent to each other around one map block, and map data necessary for display is stored in the image memory 23 from the wide area map data for nine map blocks stored in the buffer memory 22. It is necessary to transfer efficiently.

However, the problem with data transfer from the buffer memory 22 to the image memory 23 is that as the vehicle moves, the map data that should be transferred to the image memory 23 is the wide area map data stored in the buffer memory 22. In this case, the image memory 23
While the map data to be transferred is stored in opposing areas in the buffer memory 22, appropriate block transfers to the image memory 23 must be performed so that it can be stored as continuous map data.

The division determination of map data by the central processing unit 24 and the block transfer at the time of division will be described below.

First, map data division determination is performed, as shown in FIG. Steps to defeat flags and crossing flags (
101).

The presence or absence of a vertical section is determined by the fact that the X coordinate Xa of the point A indicating the apex of the display frame of the display device 8 is the length RX(-) of the display frame in the X-axis direction.
640 dots)). Then, as a result of the determination in step (102), as shown in FIG. 104), the divided 2
-Point A.

The coordinate margins XL and XR to the boundary line of B are XL=3RX-
Determine according to Xa XR=RX-XL. In addition, if the division is not made, in step (105), the coordinate margins XL, X
Let R be XL-RX XR=0.

In addition, the presence or absence of a cross section shown in Figure 3 (B) is determined by following the same procedure as the vertical cross section, and the Y coordinate Ya of point A indicating the apex of the display frame is determined by the length of the display frame in the Y axis direction. It is judged whether or not it exceeds twice RY (-200 dots). however,
YU and YD represent the respective coordinate margins of the two divided points A and C, respectively.

In this way, the states of the vertical flag and the cross flag are determined up to step (108), but both the vertical flag and the cross flag are set for the four-division state shown in FIG. 3(C).

When the division judgment of the map data is completed, the central processing unit 24
transfers data from the buffer memory 22 to the image memory 23 by performing four steps depending on the state of division.

First, if the map data stored in the image memory 23 is neither vertical nor cross-sectional, the flag is inverted as shown in step (111), and the top of the display frame is determined as shown in step (112). A block of map data stored in the buffer memory 22 is transferred to the image memory 23 starting from the coordinates of A. In this case, the image memory 23
The map data to be block transferred to the display device 8
It is sufficient to perform this for 200 lines in the vertical direction of the display frame. First, in step (+21) shown in FIG.
The transfer destination address is set to 0, and the number of lines to be transferred is set to RY in the line counter. Then, one time n(
- 2 bytes) at a time, the step (
+22), the number of transfers CX (=RX/2) required to transfer data for line RX (-80 bytes) is
). Next, in step (123), map data for one line is transferred by performing block transfer for the number of CX times, and then, in step (124), 1 is subtracted from the count value set in the line counter. .

Next, step (12
5), 2R is added to the address Sl used last for reading.
Add X and use this as the next read start address.

Then, data transfer is repeated sequentially for adjacent lines, and finally, when the count value of the line counter reaches 0,
Upon receiving the affirmative determination in step (126), the transfer of all 200 lines is completed.

On the other hand, if the map data stored in the image memory 23 is divided into two parts vertically, the flag is inverted in step (113) shown in FIG. Of the map data divided and stored in the memory 22, data corresponding to the left half of the map and data corresponding to the right half of the map are sequentially read out while repeating line scanning and transferred in blocks to the image memory 23 in byte units. That is, as shown below in step (13, 1) of FIG. 5(B), first, the vertex A of the display frame is
After setting the X coordinate Xa of
(=XL/2) is calculated. Next, block transfer is performed Cx times, and 1912 minutes of the left half of the map data is transferred to the image memory 23. Therefore, in order to transfer 1942 minutes of the right half of the map data, in step (134), set the reading start address Sl to O, calculate the number of transfers CX (=XR/2) from the coordinate margin XR, and Perform block transfer. When the transfer of 1 line of map data divided into 2 is completed, next, 1 is subtracted from the count value of the line counter, and the address corresponding to 2RX is added to the readout start address of the next line. Specify. And finally step (1
The same steps are repeated until it is determined that data transfer for all 200 lines is completed in step 37).

In addition, in such a case of vertical division into two parts, if the left half and right half of the map data stored in the image memory 23 are read out using consecutive addresses for every l line, the left and right data will be separated at the transfer destination. This creates a level difference of 1 line, which causes a fault in the display on the display device 8. To avoid this problem, the step (
134) has an important meaning.

Next, when the map data stored in the image memory 23 is divided into two by crossing, the steps (1) shown in FIG.
In response to the determination result in step 15), in the following step (116), data corresponding to the lower half of the map and data corresponding to the upper half of the map are sequentially transferred in blocks. In this case, as shown in FIG. 5(C) in detail, the transfer of the lower half of the map data is completed up to step (146), and the transfer of the upper half of the map data is completed up to step (152). . For this reason, steps (+41) and (147)
Although there is a slight difference in the set count value of the line counter in , it is basically the same as repeating the steps in the case of no division twice.

Finally, if the map data stored in the image memory 23 is divided into four sections by cross section and longitudinal section, step (
In response to the negative result of the determination in step 11'5), as shown in the subsequent step (+17), the map data divided into four parts is individually transferred in blocks. Specifically, as shown in steps (161) to 174) in FIG. 5(D), data transfer is performed in which the two divisions by the traverse and longitudinal sections are combined. That is, after the right and left halves of the lower half of the map data are transferred, the right and left halves of the upper half of the map data are transferred.

In this way, the in-vehicle navigation device 21 stores the map data of the map blocks displayed on the display device 8 that displays the estimated current location of the vehicle as a wide-area map block consisting of one map block and its adjacent map blocks. If the map data required by the image memory 23 is missing even in part from the wide area map data stored in the buffer memory 22, the missing part is transferred to the image memory 23 from the buffer memory 22, which can be transferred to the image memory 23. While writing to the buffer memory 22 using an area spaced apart from each other,
Since the map data required by the image memory 23 is transferred in divided blocks from this buffer memory 22,
The map data required for display on the display device 8 can be written into the buffer memory 22 as the vehicle progresses, and the map data is transferred from the buffer memory 22 to the image memory 23 by divided block transfer. Even if the map data stored in the image memory 23 is divided within the buffer memory 22, the transfer will not be delayed due to the division, and therefore the map data necessary for displaying the estimated current location of the vehicle can be sent to the image memory 23. , can always be transferred accurately and quickly.

[Effects of the Invention] As explained above, the present invention converts map data of a map block displayed on a display device that displays the estimated current location of a vehicle into a wide area map block consisting of one map block and its adjacent map blocks. The map data required by the image memory is transferred from the buffer memory where it can be stored to the image memory, and if even part of the map data required by the image memory is missing from the wide-area map data stored in the buffer memory, this missing part is compared to the non-missing part. The configuration uses separate areas to write to the buffer memory, and transfers the map data required by the image memory from this buffer memory in divided blocks, so the map data required for display on the display device can be transferred in accordance with the progress of the vehicle. The map data can be written to the buffer memory using the map data, and map data is transferred from the buffer memory to the image memory using divided block transfer. Therefore, there is no delay in the transfer due to the fact that the map data is transferred to the image memory, and map data necessary for displaying the estimated current location of the vehicle can always be accurately and quickly transferred.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the in-vehicle navigation system of the present invention, and FIGS. 2 and 3 are diagrams each illustrating the division determination operation of map data by the central processing unit shown in FIG. 1. FIG. 6 is a circuit configuration diagram showing an example of a conventional vehicle-mounted navigation device. 818. Display device, 21. , Vehicle navigation device, 22. ,,buffer memory,23. ．． . Image memory, 24. ,,central processing unit.

Claims (1)

[Claims] A display device that displays the estimated current location of the vehicle, an image memory that stores map data of map blocks displayed on the display device, and a wide area map block that is capable of storing one map block and its adjacent map blocks. If the map data required by the buffer memory and the image memory is missing even in part from the wide-area map data stored in the buffer memory, the buffer memory uses an area that separates the missing part from the non-missing part. A vehicle-mounted navigation device comprising: a data transfer control means for writing map data into the image memory and transferring divided blocks of map data required by the image memory from the buffer memory.