JP2002323324A - Navigation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To previously receive a wide-range map for displaying a map usable for a long time even in the outside the range wherein receiption of the map is impossible in a navigation device carrying no storage medium such as a DVD with a large map storage capacity and traveling while receiving the map. SOLUTION: This navigation device is provided with a communication circuit 8 receiving map information from a station distributing several pieces of map information different in area range by radio waves and a control circuit 1 selecting the area range of the map information to be received according to receiption intensity of the communication circuit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device for receiving map information.

[0002]

2. Description of the Related Art In order to reduce the size and weight, a disk drive such as a CD-ROM or a DVD-ROM is not mounted.
A navigation device equipped with a small storage medium such as a smart media, a compact flash (registered trademark), a memory stick, and an SD card has been considered.

[0003] Such a small navigation device cannot store many maps because the storage capacity of the storage medium is small. Then, in order to supplement the small storage capacity, it has been considered to receive insufficient maps and peripheral information using wireless communication such as a mobile phone (Japanese Patent No. 2910).
No. 544).

[0004]

However, when the mobile terminal moves out of the area where reception is not possible, the radio wave intensity gradually weakens, and eventually a problem arises in that it becomes impossible to receive maps and peripheral information.

[0005]

SUMMARY OF THE INVENTION In view of the foregoing, a navigation device according to the present invention has a communication circuit for receiving map information from a station that wirelessly distributes map information having different areas, and the communication circuit. Control means for selecting the area size of the map information to be received based on the reception strength of the circuit.

[0006] This makes it possible to display a map that can be used for a long time when it is out of the service area and the map cannot be received.

[0007] Also, a communication circuit for receiving map information from a station that wirelessly distributes map information of a plurality of scales, and control means for selecting a scale of the received map information based on the reception strength of the communication circuit. .

[0008] This makes it possible to display a wide-range map when it is out of the service area and the map cannot be received.

A communication circuit for receiving map information from a station that wirelessly distributes the map information divided into a plurality of sections;
Control means for determining the number of map information segments to be received based on the reception strength of the communication circuit.

[0010] This makes it possible to display a wide-range map when it is out of the service area and the map cannot be received.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. The navigation device according to the present embodiment is a device that reads map information and peripheral information from a storage medium having a small storage capacity.

FIG. 1 is a block diagram showing a configuration of a main part of the first embodiment. (1) is a control circuit, a ROM
Each part is controlled based on the program written in (2). (3) is a RAM for storing information necessary for the operation of the control circuit (1). (4) is GPS (Global)
Positioning System (Positioning System) is a positioning means that receives a radio wave from a GPS satellite, measures the current position, and outputs measurement data to the control circuit (1). (5) is a compact flash comprising a non-volatile memory having a storage capacity of 32 MB, on which map information is written. Since the compact flash (5) has a smaller storage capacity than a CD or DVD, it stores a nationwide map with a small scale. A local map having a large current position scale is received by communication and stored in the RAM (3). (6) a liquid crystal display unit for displaying map information and the current position based on the control of the control circuit (1). (7) is an input unit operated by a user.

Next, the operation of the first embodiment will be described. FIG. 2 is a flowchart showing the operation of the control circuit (1) of the navigation device, and FIG. 3 is a table showing the operation of the control circuit (1).

Here, as shown in FIG. 3, the control circuit (1)
Indicates the strength of the reception strength received by the communication circuit (8),
dB or more as “strong”, −85 dB or more and less than −50 dB as “medium”, −100 dB or more and less than −85 dB as “weak”,
If it is less than -100 dB, it is determined as "weak". Then, the base station transmits a plurality of maps divided by sections each having a size of one screen of the display unit of the navigation device on four scales. Each map information includes latitude / longitude information and scale information of an area, and the navigation device can selectively receive a map of a desired scale including the current position. As shown in FIGS. 4 to 7, the four scales are 1/2500 and 1/10 in descending order.
000, 1/50000, 1/200000, and the larger the scale, the more detailed the map information.

In FIG. 2, each time the control circuit (1) travels a predetermined distance (S1, S2), the communication circuit (8) receives a map including the current position (S3 to S13). As shown in FIG. 2 and FIG. 3, when the reception intensity is “strong” or “medium” (Y in S3), the control circuit (1)
If less than m, receive a map of scale 1/2500 and RAM
Stored in (3) (Y in S4, S5), if the speed is 70 km / h or more, receive a map of scale 1 / 10,000 and RAM
It is stored in (3) (N in S4, S6). If the reception intensity is "weak" (Y in S7), if the speed is less than 70 km / h, a map with a scale of 1 / 10,000 is received and stored in the RAM (3) (Y in S9, S9). Ba scale
The map of 1/50000 is received and stored in the RAM (3) (N in S9, S10). When the reception strength is “weak” (S
7N), if the speed is less than 70 km / h, a map with a scale of 1 / 50,000 is received and stored in the RAM (3) (Y of S11,
S12) If the speed is 70 km / h or more, a map having a scale of 1/200000 is received and stored in the RAM (3) (N in S11, S13).

As described above, when the scale of the map to be received can be selected, the navigation apparatus of the present invention selects and receives a map with a small scale when the reception intensity becomes weak, and stores a wide range of maps. As a result, when it is out of the service area and a map cannot be formed, a wide-range map can be displayed. At this time, when the moving speed is high, by receiving a map with a smaller scale, a map that can be used for a long time can be displayed by giving priority to a wider range than the degree of detail.

In the first embodiment, a map with a small scale is received when the moving speed is high. However, a map with a small scale may be received on an expressway or a toll road. This is a second embodiment, and the operation is shown in the table of FIG.

Next, a third embodiment will be described. As shown in FIG. 10, the size of the unit section in the third embodiment is obtained by dividing the display section of the navigation device into three parts vertically and three parts horizontally, so that nine sections have a size of one screen. The base station transmits the map divided by this section on one type of scale. The map information of each section includes the latitude and longitude information of the area, and the navigation device can selectively receive a plurality of maps of the desired section.

FIG. 9 is a flowchart showing the operation of the control circuit (1) of the navigation device according to the third embodiment.
The control circuit (1) determines when the current position section becomes a section at the end of the map stored in the RAM (3) (S2).
1) The map of the insufficient section is received by the communication circuit (8) so that the plan of the current position becomes the central section, and the RAM is used.
It is stored in (3) (S22 to S24). The receiving area differs depending on the electric field strength.
If it is less than dB, 9 map areas (see FIG. 10) are received (Y in S22, S23), and if it is 100 dB or more, 49 map areas (see FIG. 11) are received (S22).
22 N, S24).

For example, in the case of FIG. 10 having nine sections, when the current position moves from L1 in the center section to L2 in the upper right end section, RA among the nine sections centering on the section in which L2 is located.
Five sections (hatched lines in FIG. 10) not stored in M (3) are received. In this case, the minimum reception required for screen display is always performed, and the communication cost and storage capacity are reduced. In the case of FIG. 11 of the 49 sections, when the current position moves from L1 of the center section to L2 of the upper right end section, among the 49 sections with the section where L2 is located at the center, not stored in the RAM (3) 4
The 0 section (the oblique line in FIG. 10) is received. When a map of 49 sections is stored, it is not necessary to receive a new map until the current position becomes the area of the 24 sections at the end. in this case,
It is possible to receive a map of an area larger than the screen display and prepare for a case where the map cannot be received.

[0021]

As described above, according to the present invention, when a map is received while the vehicle is traveling, the map is received over a wide area when the reception intensity is weakened. Accordingly, when the map is out of the service area and cannot be received, a wide-range map can be received in advance so that a map that can be used for a long time can be displayed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the first embodiment.

FIG. 3 is a table showing an operation of the first embodiment.

FIG. 4 is a diagram showing a map on a scale of 1/2500.

FIG. 5 is a diagram showing a map on a scale of 1/10000.

FIG. 6 is a diagram showing a map on a scale of 1/50000.

FIG. 7 is a diagram showing a map on a scale of 1/200000.

FIG. 8 is a table showing the operation of the second embodiment.

FIG. 9 is a flowchart showing the operation of the third embodiment.

FIG. 10 is a diagram showing a narrow map area received in the third embodiment.

FIG. 11 is a diagram showing a wide map area received in the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control circuit 3 RAM 4 GPS positioning means 5 Compact flash 6 Display means 8 Communication circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C032 HB22 HB25 HC08 HC24 HD03 2F029 AA02 AB07 AC02 AC09 AC16 AC20 AD07 5H180 AA01 BB04 CC12 FF05 FF13 FF22 FF27 FF33 FF35

Claims (3)

[Claims] 1. A communication circuit for receiving map information from a station that wirelessly distributes map information having different area sizes, and selecting an area size of the received map information based on a reception strength of the communication circuit. A navigation device comprising control means. 2. A communication circuit for receiving map information from a station that wirelessly distributes map information of a plurality of scales, and control means for selecting a scale of the map information to be received based on the reception strength of the communication circuit. A navigation device characterized by the following. 3. A communication circuit for receiving map information from a station that wirelessly distributes map information divided into a plurality of sections, and the number of map information sections to be received is determined based on the reception strength of the communication circuit. A navigation device comprising control means.