JPH07175409A - Display method of map for navigation device - Google Patents

Abstract

PURPOSE:To provide a display method of maps for a navigation device which makes characters and symbols easily visible by preventing the sizes of the characters and symbols from changing when a map is displayed in enlargement/ reduction. CONSTITUTION:Road map information indicating the roads appearing on the map and character and symbol information indicating the characters and symbols are previously stored in memory places different from each other of a memory means 4. The road map information and character and symbol information which are included in a region to be displayed are respectively read out of the corresponding memory place of a memory means 4. The road map information is subjected to enlargement or reduction processing independently from the character and symbol information when the information are displayed on a display screen 5 and an instruction to the enlargement or reduction as to the display of the map is made from outside. Such road map information is then displayed together with the character and symbol information included in the region on the display screen 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a map display method in a vehicle-mounted navigation device for displaying a vehicle position, a road map, information necessary for traveling, and the like.

[0002]

2. Description of the Related Art A vehicle traveling guide device for detecting the current position of a vehicle, displaying it on a road map, and displaying information necessary for traveling is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-169785. An "induction device" is known. This displays a mark indicating the position and the traveling direction of the vehicle in a predetermined direction on the display screen with a certain direction, and is displayed on the display screen as the vehicle travels. Then, in this, an apparatus adapted to move a map pattern is disclosed. In this device, in order to easily identify the current position of the vehicle on the map, the display map can be enlarged and reduced at a plurality of predetermined magnifications.

[0003]

By the way, in such an apparatus, when a display map is enlarged / reduced, when characters / symbols are displayed in the map, their sizes are also enlarged / reduced, which makes it difficult to see. There's a problem. In particular,
When the screen is displayed in a reduced size, there is a problem that it becomes difficult to read characters and symbols.

The known example also has the following problems. That is, in the device disclosed in this known example, the display map is represented as a set of dots (dots) on the screen, and when enlarging the display map, the corresponding M rows N from the display screen data are displayed. Take out the display point of the column,
The display map is enlarged by distributing the display points on the display screen. At this time, when the map is enlarged and displayed due to the dispersion of the display points, there is a drawback that the displayed map is difficult to visually recognize. Therefore, even if the display points are dispersed, the magnification of enlargement can be suppressed to such an extent that it can be visually recognized as a map display with the naked eye.

In the above-mentioned publicly known example, for example, the number of display points required to display a map at a scale of 1 / 250,000 is M rows N.
It is assumed that the row (M × N) is sufficient. Next, when this 1 / 250,000 scale map is displayed at a 1 / 50,000 scale (magnification of 5 times), the dispersion of the display points becomes large (that is, the area of the display points becomes 5 × 5 = 25 times). , The display map has poor visibility.

Therefore, in order to enable enlarged display at a scale of 1 / 50,000 (magnification of 5 times), the number of display points is reduced to 1 / 250,000.
The display map with good visibility cannot be obtained unless it is stored with the accuracy of 5 times as many as the map of 5 in 5M rows and 5N examples (5M × 5N pieces). That is, in order to display a map at a magnification of 5 times and a scale of 1 / 50,000, a storage capacity that is 25 times the storage capacity necessary to store the original map (scale of 1 / 50,000) is required. If the magnification of the enlarged map is 10 times, the storage capacity of 100 times that of the original map is required.

As described above, the conventional technique has a drawback that the storage capacity of map data becomes enormous when an enlarged view is required. If the amount of magnetic tape that stores map data increases, the read time for reading one map data will increase, and the amount of data handled as a vehicle travel guidance device will increase. However, a large-capacity storage unit is required for the entire device, and there is a problem in cost.

A first object of the present invention is to provide a map display method in a navigation device in which the size of characters / symbols is not changed when the map is enlarged / reduced so that the characters / symbols can be easily seen. To provide.

A second object of the present invention is to provide a large amount of map information including an enlarged view with a relatively small storage capacity without excessively increasing the storage capacity of the storage medium and the storage device in the navigation device. It is to provide a display method of a map that can be stored.

[0010]

In order to achieve the above first object, according to a first aspect of the present invention, a map of a map in a navigation device for displaying a map and a position of a vehicle on a display screen of a display device. In the display method, the road map information indicating the road appearing on the map and the character / symbol information indicating the characters / symbols appearing on the map are separately generated and displayed on the display screen. When an instruction to enlarge or reduce is given from, about the road map information,
A method for displaying a map in a navigation device is provided, which is characterized by performing enlargement or reduction processing independently of character / symbol information and displaying the same on a display screen together with the character / symbol information included in the area.

Further, according to the second aspect of the present invention, in the map display method in the navigation device for displaying the map and the position of the vehicle on the display screen of the display device, the road map showing the road that appears on the map. The information and the character / symbol information indicating the character / symbol are stored in advance in different storage locations of the storage means, and the road map information and the character / symbol information included in the area to be displayed are stored in the storage means. When the map display is read from the relevant memory location and displayed on the display screen, and the map display is instructed to be enlarged or reduced externally, the road map information is enlarged or reduced independently of the character / symbol information. A method for displaying a map in a navigation device is provided, which is characterized in that the map is displayed on a display screen together with the character / symbol information included in the area.

According to a third aspect for achieving the above second object, in addition to the above second aspect,
As the road map information, for each road appearing on the map, position coordinate information of division points obtained by dividing each road within a range in which each road can be linearly interpolated is stored in the storage means for each road.
It is sequentially stored along each road from one end to the other end, and when the map of the target section is displayed, the position coordinate information included in the map to be displayed is stored in order of storage for each road. According to the method, a map display method in a navigation device is characterized in that a road map is generated by linearly interpolating adjacent coordinates of the read position coordinate information to form a line connecting the division points in order. Provided.

[0013]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of a navigation device to which the map display method of the present invention is applied.

In the figure, the traveling distance detector 1 generates a pulse signal according to the vehicle speed, for example. The traveling direction detector 2 is a detector for detecting the traveling direction of the vehicle, and is, for example, a magnetic sensor that detects the traveling direction by utilizing the geomagnetism. The signals detected by the traveling distance detector 1 and the traveling direction detector 2 are read by the signal arithmetic processing unit 3.

The signal arithmetic processing unit 3 arithmetically processes these two signals to calculate the current traveling position of the vehicle. Further, the signal processing unit 3 calculates the current traveling position and inputs the map data corresponding to the current traveling position from the information storage device 4. A cassette tape recorder is used as the information storage device 4, but RA
Storage means such as M and a magnetic disk are also conceivable. And
This signal arithmetic processing device 3 compares the current traveling position with the information in the information storage device 4, and displays the map data and the accurate current traveling on the map data on the screen of the display device 5 composed of a cathode ray tube (CRT). Display position and at the same time.

The input device 6 is an input device for controlling the operation of the signal arithmetic processing device 3.

Next, the configuration of the signal arithmetic processing unit 3 will be described in detail with reference to FIG.

The signal arithmetic processing unit 3 inputs signals from the traveling distance detector 1, the traveling direction detector 2 and the input unit 6, respectively, and calculates the current position of the vehicle. Then, the map data corresponding to the current position is read from the information storage device 4 and displayed on the display device 2. In FIG. 2, a television antenna 7 is provided so that the display device 5 can be used as a television.

Next, the configuration of the signal processing unit 3 will be described.

The signal processing unit 3 is controlled by two microprocessors 31 and 32. The microprocessor 31 performs arithmetic processing of the current position and control of the entire system, and the microprocessor 32 performs map data processing and map display.

The input / output circuit 311 reads a signal from the input device 6 such as a keyboard. Processor 312
Performs waveform shaping processing so that the signals from the traveling distance detector 1 and the traveling direction detector 2 can be easily processed by the microprocessor 31. The interface 313 is a circuit for controlling the microprocessor 32 by the microprocessor 31.

The microprocessor 32 operates according to a program stored in a read only memory (ROM) 321. A read / write memory (RAM 322 is for temporarily storing stack memory data, map data, etc. of the microprocessor 32. Input / output circuit 3
Reference numeral 23 is a map data search for reproducing, fast-forwarding, and rewinding operations of the information storage device (cassette / deck in this embodiment) 4, and converts serial map data from the cassette deck 4 into parallel data. , Reproduce and edit map data such as temporarily storing it.

The video RAM 324 is a read / write memory that stores display data for one display map. Video R
The display data written in the AM 324 is displayed on the display device 5 by the video display generator (VDG) 325.

In this embodiment, the television antenna 7, the television tuner 33, and the demodulation circuit 331 are provided, and television reception can be performed by switching the switching circuit 314 to the television receiving side by the microprocessor 31. The display device 5 includes a deflection circuit 501, a video amplification circuit 502, and a CRT.
503.

In the navigation device having such a structure,
When a map as shown in FIG. 3 is displayed on the display device 5, the map data such as characters and symbols shown in FIG. 3 and the map data for the road map are recorded on a recording medium such as the magnetic tape 11 shown in FIG. Then, like the map number recording unit 111, the character / symbol information recording unit 112, and the road map information recording unit 113, the area is divided and recorded according to the stored contents.

First, the character / symbol information recording section 112 will be described. The data format of the character / symbol information recording unit 112 is, as shown in FIG. 5, for one character, that character is a main scale map (map data that is always displayed. In this embodiment, it is shown in FIG. Which position on the map (scale of 1 / 250,000 shown) corresponds to the main scale position information section 112A of the X and Y coordinates of the main scale map of FIG. 8 is recorded at the beginning of the stored character. Then, after the main scale position information section 112A, character / dot position information such as characters / symbols is recorded in the character information recording section 112B, similarly to the output of the character generator. Memory information such as characters and symbols is called font information.

Therefore, the cassette deck 5 searches for a predetermined map number, and the read data such as characters and symbols corresponds to the video RAM 32 corresponding to the position information of the data.
4 is written in place. This way,
The size of characters does not change as the display image is enlarged or reduced. If the same number of characters are always displayed on the enlarged and reduced display screens, the reduced scale display screen becomes very difficult to see, so the main scale position information section 11
In 2A, discrimination information of whether each character / symbol information is displayed in an enlarged view or a reduced view is recorded.

Next, the road map recording unit 113 will be described.

FIG. 6 is an explanatory diagram of linear interpolation,
The figure is a recording state diagram of the position coordinate information of each point O, P, Q, and R in FIG. First, the cassette deck 4 is searched for the map number N, and then the position coordinate information on the road map is read. That is, the position coordinate information O (x ₁ , y ₁ ) is read, and then the position coordinate information P (x ₂ , y ₂ ) and Q (x ₃ ,
y ₃ ), R (x ₄ , y ₄ ), ... In this order, the respective position coordinates on the road map are read in sequence. Then, by performing linear interpolation in the order of the read position coordinate information, the sixth
The O / P / Q / R road map as shown in the figure is drawn.

By doing this, the road map O / P / Q /
The number of pieces of position information required to draw R is four in FIG. By using such a linear interpolation method,
The number of data required to display roads on the map can be greatly reduced.

A method of determining the division points divided in the range where the above linear interpolation can be performed will be described with reference to FIG.

The arc ACB in FIG. 10 is a road map. The point A on this road map is set as a reference point, and the point B is slid along the road map. At this time, a string AB (straight line L) formed between points A and B and a parallel line L1 having a distance D
Suppose Then, as the point B slides, the parallel line L1 and the road map (arc ACB) may cross each other. The point C at this intersection is defined as a division point divided within a range in which linear interpolation can be performed. Then, the reference point A and the division point C are connected. This straight line (broken line) AC is a road map formed by linear interpolation. Next, by using the point C as a reference point and repeating the same operation as described above, the division points divided within the range where linear interpolation can be performed are determined.

The accuracy of the map created by the above method is determined by the distance D between the parallel line L1 and the chord AB (straight line L). In addition to the above method, for example, there is a determination method based on the radius of curvature of the road. The above will be described in more detail with reference to FIG.

FIG. 9 shows the road map of FIG. 3 by the above-mentioned linear interpolation. First, cassette deck 5
The position coordinates a1 to a13 are sequentially read in and linear interpolation is performed between two points of these position coordinates. Next, the position coordinates b1 to b11 are read, finally the position coordinates E1 to E5 are read, and linear interpolation of these position coordinates is performed, whereby a road map as shown in FIG. 9 is completed.

When the road map of FIG. 3 is recorded as a set of display points as in the prior art, about 350 pieces of position coordinate information must be recorded as the number of display points required for display. However, when it is stored as the position coordinates of the division points in the range where linear interpolation can be performed as in the present invention, as is clear from FIG. 9, the number of position coordinate points is sufficient, and in addition, as shown in FIG. There is no problem in the visibility of the map information when comparing FIG.

According to this embodiment, the storage capacity for one road map can be greatly reduced, and the time required to read the map data can be shortened.

In the above description, the characters / symbols, etc. are used as font information, and the position coordinates of the dividing points in the range where linear interpolation is possible on the road map are used. May be recorded.

Next, as described above, the navigation device according to the present invention enlarges / reduces the map by using the recorded map data. Therefore, this operation will be described below.

First, in FIG. 2, the map data recorded as described above is read by the cassette deck 4. At this time, the road map information is read after the character / symbol information and written in the read / write memory 322. The position coordinate information of the road map information written in the read / write memory 322 is linearly interpolated by the microprocessor 32 and written in a predetermined place in the video RAM 324 as a set of straight lines.

The map data written in the video RAM 324 as described above is controlled by the video display generator 325 and displayed on the display device 5 as a road map as shown in FIG. 8 (characters and symbols are omitted). To be done.

Therefore, when enlarging a part of the road map shown in FIG. 8, the area to be enlarged on the display screen (area Z in FIG. 8) and the magnification (10 times) are designated by the input device 6. As a method of designating this area, the cursor is fixed to one point on the display screen, and the map is enlarged centering on that one point. Then, map data within the range of this designated area is selected from the magnetic tape 11 and read.

The position coordinates of the read map data are magnified by the designated magnification, and the character / symbol information is written in the video RAM 324 and displayed by the video display generator 325 by the same operation as described above. Here, if the original road information, that is, the map with the largest scale (Fig. 9) is recorded with sufficient accuracy for linear interpolation, a map with a smaller scale than this stored information is displayed with high accuracy. It's easy to do.

In the above, when displaying an enlarged view,
The map data of the portion to be enlarged is read again from the magnetic tape 11. Therefore, as another method of enlarging and displaying the map, if the original road information is recorded in the read / write memory 322 with an accuracy capable of enlarging and displaying, it is not necessary to search the magnetic tape again. In this case, it is possible to select a portion to be enlarged and displayed from the original map information recorded in the read / write memory 322 and display it as it is. As an effect of such an embodiment, it is possible to instantly enlarge any place and eliminate the delay time required for displaying the enlarged view, that is, the time for re-reading.

In the above-described embodiment, the microprocessor 32 is provided with the function of linear interpolation, but a device for performing linear interpolation may be provided separately from the microprocessor 32, and the video display generator 325 may be provided with such a device. You may add a function.

[0046]

As described above, according to the present invention, when a map is enlarged / reduced, the size of the character / symbol is not changed, and the character / symbol can be easily seen.

When the road is divided and stored at the coordinates of the division points and displayed, the division points are linearly interpolated to generate the shape of the road, thereby reducing the storage capacity required to store the map data. The size of the map can be reduced, and thus the enlarged map can be displayed without increasing the storage capacity, and the usability and usefulness as the navigator device can be further improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an outline of a navigation device to which a map display method of the present invention is applied.

FIG. 2 is a block diagram showing a basic configuration of a navigation device.

FIG. 3 is a diagram showing an example of a map displayed on a display device.

FIG. 4 is a diagram showing an example of a map data format recorded on a magnetic tape.

FIG. 5 is a diagram showing an example of a data format of characters, symbols, etc. recorded on a magnetic tape.

FIG. 6 is an explanatory diagram of linear interpolation.

FIG. 7 is a diagram showing an example of a data format of a road map recorded on a magnetic tape.

FIG. 8 is a diagram showing an example of a normally displayed map at a scale of 1 / 250,000.

9 is a diagram showing an example of a map in which a part of the map of FIG. 8 is enlarged and displayed by linear interpolation.

FIG. 10 is a diagram illustrating a linear interpolation method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Odometer, 2 ... Travel direction detector, 3 ... Signal processing unit, 4 ... Cassette deck, 5 ... Display unit, 6
… Input device, 11… Magnetic tape

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takanori Shibata 2520 Takaba, Katsuta City, Ibaraki Prefecture Inside the Sawa Plant, Hitachi, Ltd.

Claims (9)

[Claims] 1. A method of displaying a map in a navigation device for displaying a map and the position of a vehicle on a display screen of a display device. Road map information indicating a road appearing on the map and characters indicating characters / symbols appearing on the map.・ The symbol information and the symbol information are generated separately and displayed on the display screen. When the map display is instructed to be enlarged or reduced from the outside, the road map information is enlarged independently of the character / symbol information. Alternatively, a method of displaying a map in a navigation device is characterized by performing a reduction process and displaying the same on a display screen together with character / symbol information contained in the area. 2. The road map information and the character / symbol information displayed on the display screen according to claim 1, are stored in advance in different storage locations of the storage means, and are stored respectively when displayed on the display screen. A method for displaying a map in a navigation device, characterized in that the map is read out from the corresponding memory location of the means and displayed. 3. The display screen according to claim 2, wherein the number of characters and symbols in the same area on the map is displayed differently depending on whether the map is enlarged or reduced. A method for displaying a map in a navigation device, characterized by: 4. The display according to claim 2, wherein when the map is displayed on the display screen, the size of characters and symbols is displayed the same regardless of whether the map is enlarged or reduced. The number of characters / symbols in the same area on the map is reduced and displayed when the map is displayed in a reduced size as compared with the case where the map is displayed in an enlarged manner. Display method. 5. The character / symbol information according to claim 4,
A method of displaying a map in a navigation device, wherein discrimination information for discriminating whether to display the character or symbol in an enlarged view or a reduced view is added in advance. 6. The map according to claim 2, 3, 4 or 5, wherein a map to be displayed is preliminarily divided and stored, and each divided map shows road map information indicating a road and characters / symbols. A method for displaying a map in a navigation device, which stores character / symbol information. 7. The road map information according to claim 6,
For each road represented on the map, position coordinate information of division points obtained by dividing each road within a range in which each road can be linearly interpolated is sequentially stored in the storage means along each road from one end to the other end. When displaying the map of the target section, the position coordinate information included in the map to be displayed is read for each road in the order stored and the adjacent coordinate of the read position coordinate information is read. Characteristic of linearly interpolating each other to form a line connecting the division points in order to generate a road map,
A method of displaying a map on a navigation device. 8. When the map enlargement display instruction is received, the position coordinate information in a range that can be enlarged and displayed is read out, and the position coordinate information is converted into enlarged position coordinate information. Then, a method for displaying a map in a navigation device is characterized in that the linear interpolation is performed on the expanded position coordinate information. 9. The storage means according to claim 8, wherein, as the character / symbol information, position coordinate information indicating a display position on the map where each character / symbol is to be displayed and font information indicating their shape are stored in the storage means. When storing and displaying the map of the target section, read out the position coordinate information and font information included in the map to be displayed, and correspond to the position coordinate information of the generated road map on the display screen. A method for displaying a map in a navigation device, characterized in that characters / symbols are displayed at the positions indicated by the font information.