JPH05204304A - Map display device for vehicle - Google Patents

Abstract

PURPOSE:To automatically set the scale of a map corresponding to the level of reception from a broadcasting station. CONSTITUTION:A receiving means 1 receives a sent signal from a broadcasting key station. The broadcasting key station is discriminated from the frequency of the signal. A detecting means 3 detects the reception level (electric field intensity). A display means 5 varies the scale of the map to be displayed by a scale varying means 4 according to the electric field intensity. The map of the periphery of the broadcasting key station is displayed on the map scale corresponding to the electric field intensity together with traffic information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a map display device for a vehicle which does not have a vehicle position detecting means such as GPS.

[0002]

2. Description of the Related Art A vehicle having no vehicle position detecting means is provided with a broadcast frequency detecting section, a storage section, and an area discriminating section, as described in, for example, Japanese Patent Laid-Open No. 61-3078. A vehicle presence area detection device that knows the area where a vehicle is present with a simple configuration using broadcast radio waves is known.

Therefore, it is conceivable to apply such a vehicle presence area detection device to a vehicle navigation device to display a map of the vicinity of the own vehicle on the display screen of the display means.

[0004]

However, even if the map can be automatically displayed in this way, the scale of the map displayed by the display means must be adjusted by the occupant according to the position of the own vehicle. No, it was troublesome.

It is an object of the present invention to provide a vehicle map display device capable of automatically setting the scale of a map displayed on the display means without complicating the structure. .

[0006]

According to the present invention, a receiving means for receiving a transmission signal from a broadcasting base station, a displaying means for displaying a map, and a displaying means for receiving a transmitting signal from the broadcasting base station are provided. A display control means for displaying a map near the broadcasting base station, a detecting means for detecting a reception level of a transmission signal from the broadcasting base station, and a transmission signal from the broadcasting base station for receiving the output of the detecting means. And a scale changing unit for changing the scale of the map displayed on the display unit according to the reception level.

[0007]

When the receiving means receives the transmission signal from the broadcast base station, the display control means causes the display means to display the map around the broadcast base station. Then, the detection unit detects the reception level of the transmission signal from the broadcast base station, and the scale changing unit changes the scale of the map displayed on the display unit according to the detected reception level.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In FIG. 1 showing a map display device for a vehicle,
Reference numeral 1 is an FM broadcast receiving means for receiving a transmission signal from the broadcast base station P (see FIG. 2) via the receiving antenna 2.
Reference numeral 3 is a detection means for receiving the signal from the reception means 1 and detecting the reception level (electric field strength) of the transmission signal from the broadcast base station P. Reference numeral 4 denotes a scale changing unit that receives the output of the detecting unit 3 and changes the scale of the map displayed on the display unit 5 according to the reception level of the transmission signal from the broadcast base station P.

When the receiving means 1 receives the transmission signal from the broadcast base station, the display means 5 is adapted to display the map around the broadcast base station P by the display control means 6. Further, the map displayed by the display means 5 is centered on each broadcasting base station, and for each broadcasting base station, a plurality of types having different map scales are created according to the electric field strength. Storage means 7 (CD-RO
M, IC card, etc.). still,
The display control means 6 determines which broadcast base station the transmission signal is from.

Specifically, the map stored in the map storage means 7 is centered around the broadcast base station P, and its surrounding area (reception area) is, for example, as shown in FIG. It is divided into four areas Z1, Z2, Z3 and Z4, and the closer the vehicle position is to the broadcasting base station P,
Reception level (electric field strength) of the transmission signal from the broadcast base station P
Is detected by the detecting means 3, the scale changing means 4 receiving it is displayed by the display means 5,
The map scale centering on the broadcast base station O is changed so that the map scale is gradually reduced. That is, the map scale is the largest when the own vehicle position is in the area Z1, and when moving to the areas Z2 and Z3, the map is sequentially changed to the map having the next largest map scale, and the map scale is the smallest in the area Z1. It will be changed to a map.

The FM broadcast receiving means 1 has a receiving antenna 2 as is well known, as shown in FIG.
RF amplifier 11 (RF AMP) that receives the received signal from
Frequency mixer 12 (MIXEX), local oscillator 13, intermediate frequency amplifier 14 (IF AMP), FM multiple detector 15, FM
It has a detector 16 and de-emphasis 17 and 18.
Then, the frequency of the received signal, that is, the frequency of the signal transmitted by the broadcast base station, based on the signal from the frequency mixer 12,
The electric field strength is detected by the S-meter signal output from the intermediate frequency amplifier 11.

Next, the control flow of the above apparatus will be specifically described with reference to FIG.

When the start is performed by the ignition on, audio on, etc., first, in step S1, a signal for traffic information (for example, traffic jam information, accident information, parking information, etc.) from the broadcasting base station P is sent. It is determined whether there is any reception. If it is received, it is determined in step S2 whether or not the data is updated, while if it is not received, it is returned. At this time, it is possible to determine which broadcast base station the broadcast base station is based on the frequency of the signal regarding the traffic information from the broadcast base station P, and the map can be selected accordingly.

If the data is updated (including the initial case), it is determined in step S3 whether or not the data is displayed on the display screen (CRT). If it is not the data updated, the return is made. To do. If it is displayed, it is determined in step S4 whether or not there is a change in the electric field strength (reception level) in order to estimate the change in the position of the vehicle. On the other hand, if it is not displayed, it is returned.

If there is a change in the electric field strength, it is further calculated in step S5 which area Z1 to Z4 the own vehicle is in. Then, in step S6, if it is within the information providing area, that is, in the areas Z1 to Z4 where maps of different scales are prepared, the traffic information is displayed on the display screen together with the map of a predetermined scale corresponding to the areas Z1 to Z4. To do. Therefore, not only the vehicle position information but also the traffic information can be obtained.

Thereafter, it is judged whether or not the ignition is OFF. If it is not OFF, the process returns to step S1 to repeat this control, while if it is OFF, the process ends.

Although not described in the above flow chart, the information providing area (areas Z1 to Z4)
), The vehicle may enter the information provision area again immediately, so even if the vehicle goes out of the information provision area, the traffic information received last in the information provision area is the RAM for traffic information memory. And so on. Further, it is possible to control the enlargement / reduction of the map scale by the driver's operation in each of the areas Z1 to Z4.

[0019]

As described above, according to the present invention, the scale of the displayed map is automatically changed according to the reception level of the transmission signal from the broadcasting base station, so that the position of the own vehicle can be detected. In a vehicle having no means, the scale of the map can be changed without complicating the configuration and without requiring the occupant to perform a complicated operation, and an appropriate map scale can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a vehicle map display device.

FIG. 2 is an explanatory diagram of division of a reception area.

FIG. 3 is a block diagram of receiving means.

FIG. 4 is a flowchart showing the flow of control.

[Explanation of symbols]

 P Broadcast base station 1 Receiving means 3 Detecting means 4 Scale changing means 5 Displaying means 6 Display controlling means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yutaka Tagawa 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Motor Corporation

Claims (1)

[Claims] 1. A receiving means for receiving a transmission signal from a broadcasting base station, a displaying means for displaying a map, and a receiving means for receiving a transmitting signal from the broadcasting base station. Display control means for displaying a map, detection means for detecting the reception level of the transmission signal from the broadcasting base station, and display according to the reception level of the transmission signal from the broadcasting base station upon receiving the output of the detection means. A map display device for a vehicle, comprising: a scale changing means for changing a scale of a map displayed by the means.