JP3160046B2 - Travel guidance device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a travel guidance device for displaying a map of a range including its own position on a display by using a radio wave transmitted from a broadcasting station.

[0002]

2. Description of the Related Art In recent years, for example, a navigation system for a vehicle using a satellite has been developed to know the position of a vehicle. However, such a device is expensive, and as a device that can be configured at a lower cost, for example, Japanese Patent Application Laid-Open No. Sho 61-3078 discloses a device that uses a transmission radio wave from an FM radio broadcasting station. A vehicle position detection device is disclosed. In the device, when a transmission radio wave from a broadcast station is obtained exceeding a certain level, a determination result that a vehicle is present within a predetermined range centered on the broadcast station can be obtained. I have.

[0003]

However, since the apparatus described in the above publication is based only on the determination as to whether or not the radio wave received from the broadcasting station has exceeded a certain level, the broadcasting station is mainly used for broadcasting. It can only be divided into two parts: a range in which radio waves can be received at the above level and a distant range below the level. As a result, the range in which the vehicle is present is not sufficiently narrowed down. For example, when a map including the vehicle is displayed on the in-vehicle display, only a large-scale map can be displayed. Therefore, when traveling in an unfamiliar area, it is not possible to grasp the position of the vehicle in more detail, and as a result, the feeling of anxiety as to whether or not to get lost is not sufficiently resolved, and the comfort during traveling is reduced. Has not been obtained sufficiently.

[0004] The present invention has been made in view of the above-mentioned conventional problems, and has as its object to display a range in which the user is located on a display by using a radio wave transmitted from a broadcasting station. An object of the present invention is to provide a travel guidance device that can more accurately grasp a position and thereby can improve comfort during traveling.

[0005]

In order to achieve the above-mentioned object, as shown in FIG. 1, the traveling guidance apparatus according to the first aspect of the present invention comprises a plurality of broadcasting stations each having a boundary between receivable areas.
Line and the electric field strength of the broadcast waves from these stations
These boundary lines are defined as boundary lines where
Multiple areas that divide the area around the broadcasting station
Area, as well as individual broadcasts in each
The presence or absence of transmitted radio waves that can be received from the station and the level of the electric field strength
Memory for storing as a reception condition corresponding to each partitioned area
Stage (13), a receiver (10) for receiving the transmission radio wave from each broadcasting station, and whether the self-position is inside or outside the receivable area depending on whether or not the transmission radio wave is received. An inside / outside discriminating means (29) for discriminating, and the electric field strength of the received radio signal is set to the threshold level.
By comparing the bell field strength detection means for detecting in a plurality of stages (30), determination result and a plurality of the above inner and outer discriminating means (29)
Storing a field intensity detected at a stage in the storage means (13)
Has been against the receiving condition of the partitioned regions, the reception conditions that match
The divided areas corresponding to the matter and self-position specification means to identify the areas of location of the self (3 1), display control means for displaying a map including the specified area in Display Lee (1 4) and (32) Is provided.

According to a second aspect of the present invention, there is provided a travel guidance device according to the first aspect, wherein the display control is performed.
Means for detecting a change in electric field intensity detected by the electric field intensity detecting means.
It is characterized by scrolling the display screen in the direction .

According to a third aspect of the present invention, there is provided a travel guidance device according to the second aspect, wherein the display control is performed.
Means to change the display screen while driving in the same area
Scrolling and specifying the self-position
By means of being identified as being in the area
When the area is off the display screen
In this case, the scrolling is stopped in the case where the scrolling occurs.

[0008]

According to the first aspect of the present invention, whether the vehicle is located inside or outside a receivable area is determined based on whether a transmission radio wave from a broadcasting station can be received. to> et al, based on the intensity of radio waves received, own position is specified more subdivided range. By thus may identify its own position to a narrower range, the disk <br/>-play (1 4), more scale is small, therefore, we can understand the extent to which self is positioned more detail A map can be displayed. As a result, while watching the de Isupurei (14) can grasp the self-position more accurately, thereby, anxiety or not get lost on the road is reduced when traveling on the unfamiliar road,
The comfort during traveling can be improved.

According to the second aspect of the present invention, the direction in which the detected electric field intensity changes, that is, the broadcast
The screen zooms according to the approaching or distant direction.
Crawling, which changes the display screen
To follow. In this case, the screen changes continuously
Loss of self-position on display screen after change
Risk of self-positioning, and as a result
It is possible to travel while grasping the time, so when traveling
Comfort is further improved.

[0010] According to the traveling guidance device of the third aspect , the screen is scrolled while traveling in the same area.
At the same time, the self-locating means (31)
Using scroll stop control based on the determination result
To change the direction of travel in the same area.
During the line, the scroll direction and the running direction are shifted,
When traveling in the same area for a long distance,
The inconvenience that the area where you are located is off the screen
Can be eliminated.

[0011]

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIGS.

First, a reproduction process of an audio signal by the FM broadcast receiver 10 mounted on a vehicle will be described with reference to FIG. The FM broadcast wave received by the antenna 1 is amplified by the high frequency amplifier circuit 2 and then amplified by the frequency mixer 3.
Is input to The frequency mixer 3 mixes the signal with a specific frequency signal from the local oscillator 4 so that, for example, the frequency is 10.
It is converted to a 7 MHz intermediate frequency signal. Next, the intermediate frequency signal is amplified by the intermediate frequency amplifier circuit 5,
The audio signal detected by the FM multiplex detection circuit 6 or the FM detection circuit 7 and reproduced by this is output to speakers (not shown) through the de-emphasis circuits 8 and 9, respectively, so that the FM Broadcast is performed.

The above-described high-frequency amplifier circuit 2 is, as shown in more detail in FIG.
It comprises a first tuning circuit section 2b, a high-frequency amplifier circuit section 2c, and a second tuning circuit section 2d. In both tuning circuit sections 2b and 2d, for example, the tuning frequency is changed by changing the capacity of an internal variable capacitor. Will be At this time, the oscillation frequency of the local oscillator 4 is changed so as to be linked thereto. In order to perform such control when changing the tuning frequency,
As shown in FIG. 2, a tuning frequency changing unit 11 composed of a microcomputer or the like is connected to the high-frequency amplifier circuit 2 and the local oscillator 4. The tuning frequency changing unit 11 adjusts the tuning frequency in the high frequency amplifier circuit 2 to the selected broadcasting frequency in response to the user's channel selection button operation during FM radio broadcasting, and the local oscillator 4 The oscillation frequency is changed in accordance with the broadcast frequency.

Further, when a sweep signal is input to the tuning frequency changing unit 11 from a display control device 12 described later,
A sweep operation is performed to sequentially change the tuning frequency from the lower limit frequency (76 MHz) to the upper limit frequency (90 MHz) of the FM broadcast frequency band. The output from the frequency amplifying circuit 5 is sent to the display control device 12, which will be described later, as the electric field strength signal, and the oscillation frequency at the local oscillator 4 at that time is sent as the broadcast station specifying signal.

The display control device 12 is composed of, for example, a microcomputer. As shown in FIG.
A memory device 13 such as a ROM / CD-ROM and a vehicle-mounted display 14 such as a CRT are connected. The memory device 13 stores the position of the FM broadcasting station and the area surrounding the broadcasting station in accordance with the change in the electric field intensity of the broadcast radio wave. For example, FIG. 5 shows an A broadcast station, a B broadcast station located on the east side (right side in the figure) of the A broadcast station, and a C station located on the south side (lower side in the figure) between these A and B broadcast stations. FIG. 3 illustrates a divided area in an area where transmission radio waves from three broadcasting stations with a broadcasting station can be received.

In this case, for example, the electric field strength of the broadcast radio wave transmitted from the broadcast station A decreases almost monotonically as the distance increases. Thereby, for example, a high electric field intensity A _H is set between the maximum electric field intensity corresponding to the transmission output in the vicinity of the broadcast station A and the minimum electric field intensity A _L at the farthest position where the broadcast reception signal can be received. By setting two electric field intensities, ie, the electric field intensity A and the medium electric field intensity A _M , these respective intensities A _H , A _M , A
_As shown in the figure, the position where _L can receive each broadcast wave is indicated by A
It can be shown on a map by a triple circle centered on the broadcasting station.

[0017] Also, for each radio wave transmitted from the broadcast station B and C broadcasting station, in the same manner as described above, respectively, while leading to a minimum field strength B _L · C _L at the position of the farthest, high field strength B
By the setting of the _H · C _H and the medium field strength B _M · C _M, it is possible to draw a triple circle, respectively centered respectively B broadcaster · C broadcasting station on the map. Each of these triple circles is used as a section line, thereby setting each sectioned and subdivided area. Then, each of these areas and the corresponding reception conditions are stored in the memory device 13.
Is stored in

In the following description, for example, the transmission electric wave from the broadcasting station A is divided into a minimum electric field intensity A _L and a medium electric field intensity A
Subscript " ₃ " for each area that can be received with _M
For example, [A ₃ ], and a subscript “ ₂ ” is added to the area that can be received between the medium electric field intensity _AM and the high electric field intensity A _H [A ₂ ]. , High electric field strength A _H
For areas near the A broadcast station that can be received with an electric field strength exceeding, a subscript “ ₁ ” is added and described as [A ₁ ]. In addition, an area sectioned with respect to the transmission radio waves from the B and C broadcasting stations is similarly described. Further, for an area that can be received from a plurality of broadcasting stations, for example, [A ₃ * B ₂ *
As of C _1], carried out the description, which had been chosen by the "*", the zone name.

Therefore, in the figure, an area indicated by [A ₃ ] can receive radio waves from the A broadcast station between the minimum electric field intensity _AL and the medium electric field intensity _AM, and can receive radio waves from the B and C broadcast stations. This is an area where the transmitted radio wave cannot be received. The area [A ₃ ] is stored in the memory device 13 with such conditions added. Conversely, a radio wave from the broadcasting station A can be received between the medium electric field intensity _AM and the high electric field intensity _AH, and a transmission radio wave from the broadcasting station B can be received at the minimum electric field intensity _BL and the medium electric field intensity _BM . If a condition that the radio wave can be received during the period and the transmission radio wave from the C broadcast station cannot be received is given, the area satisfying this condition is indicated by the hatched area [A ₂ * B ₃ ] in the figure. Specified.

In the memory device 13, the reception radio wave conditions as described above are made to correspond to each area, and the map data and the map data for displaying each area at the center of the screen of the on-vehicle display 14 are displayed. The scale is stored.

Based on the data stored in the memory device 13 and the broadcast station specifying signal and the electric field strength signal from the receiver 10 as described above, the display control device 12
Thus, the display of the map on the vehicle-mounted display 14 is controlled, and the control procedure will be described below with reference to the control flowchart of FIG.

First, for example, when the ignition switch is set to O
In the state of N, when the control of the vehicle travel guidance device having the above configuration is started, first, the display control device 12
A sweep signal for causing the tuning frequency changing unit 11 to perform the frequency sweep operation is output (step S1). Thereby, as described above, the sweep over the FM broadcast frequency band is performed in the receiver 10. If the broadcast wave is received by the receiver 10 during this time, the broadcast station identification signal and the electric field strength signal are input to the display control device 12. Therefore, after completion of the sweeping operation, it is determined whether or not any of the broadcast radio waves has been received (step S2). If the broadcast radio wave has been received, the broadcast station identification signal, that is, the transmission frequency of the local oscillator 4 is used. , From which broadcast station the radio wave has been received. Then, the detected electric field intensity input from the receiver 10 is compared with the high electric field intensity and the medium electric field intensity set for the broadcast wave from the specified broadcast station, and the electric field intensity is determined. Is performed (step S3). When a plurality of broadcast waves are received, a broadcast station is specified and the level of the electric field strength is determined for each broadcast wave.

Next, it is determined whether or not the above result has changed from the result of the previous sweep (step S4).
If there is a change, it is determined that the vehicle has moved to a new area, and the broadcast station and the corresponding area that satisfies the high and low electric field strength results are identified (step S5).
The map centering on the relevant area is read from the CD-ROM and displayed on the in-vehicle display 14 (step S).
6).

Thereafter, the process returns to step S1. Therefore, the process from step S1 is repeated every predetermined sampling time. Step S
If no broadcast radio wave is received in step 2, it is determined that the own vehicle is located outside the area where radio waves transmitted from the broadcast station can be received, and no map is displayed on the in-vehicle display 14; In the case where there is no change from the previous time, the process returns to step S1 without changing the display screen. In the present embodiment, in step S2 in FIG. 6, the inside / outside determining means 29 for determining whether or not the vehicle itself is located within the receivable area based on the presence or absence of the transmission radio wave, In step S5, the electric field intensity detecting means 30 for detecting the electric field intensity of the received radio signal is the own vehicle position specifying means 31 as the own position specifying means for specifying the area where the vehicle is located within the receivable area. But in step S6
A display control means 32 for displaying a map including the specified area on the in-vehicle display 14 as a display.
Are respectively constituted.

An example of a screen change by the above control will be described below. For example, when traveling along the line with an arrow in FIG. 5 from the position indicated by..., The screen switching as shown in Table 1 changes the division line between the areas. It is performed every time it passes. That is, when entering a zone [A ₃ ] in which only the transmission radio waves of the broadcasting station A can be received from a position where the broadcasting radio waves from any of the broadcasting stations cannot be received, a map including the whole of the zone [A ₃ ]. Is displayed on the in-vehicle display 14. This display state is maintained while passing through the area [A ₃ ], and in the process of further reaching the position, reception from the B broadcast station becomes possible, and at the same time, the reception radio wave from the A broadcast station is received. Is detected to exceed the medium electric field strength A _M , it is determined that the vehicle has entered the area [A ₂ * B ₃ ], and at this time, the area [A ₂ * B ₃ ] It is changed to a map centered on. Thereafter, as shown in Table 1, each time a change in the receiving broadcast station and a change in the electric field strength are detected as needed, the area specified as the position of the vehicle is sequentially changed, and the newly specified area is substantially displayed on the screen. Is switched to a screen display at a reduced scale such that it is enlarged to the center of the screen and almost to the entire screen.

[0026]

[Table 1]

As described above, in the above embodiment, whether or not a transmission radio wave from a broadcasting station can be received is determined.
Furthermore, the range in which the position of the vehicle is located is specified based on the intensity of the received radio wave. Therefore, it is possible to specify the position of the own vehicle in a more subdivided range. As a result, it is possible to narrow down the position of the own vehicle to a narrower range. For this reason, the in-vehicle display 14 has a smaller scale, so that a detailed map is displayed. As a result, the driver can more accurately grasp the vehicle position while looking at the on-vehicle display (14),
As a result, even when traveling on an unfamiliar road, a feeling of anxiety as to whether or not the driver may get lost can be reduced, and comfort during traveling can be improved.

[Embodiment 2] Another embodiment of the present invention will be described below with reference to FIGS.

In this embodiment, as shown in FIG. 4, a vehicle speed signal detected by a vehicle speed sensor 21 is also input to the display control device 12, and the display control device 12 is mounted on the vehicle using the vehicle speed signal. The display screen of the display 14 is controlled, and the control procedure will be described with reference to the control flowchart of FIG.

The control in this case is to determine whether or not the number of receivable broadcast stations has changed by two or less between steps S4 and S5 in the processing from step S1 to step S6 in the above embodiment. Processing (step S11)
Is inserted. In other words, as shown in FIG. 5, which is an explanatory diagram in the above embodiment, areas [A ₃ ], [B ₃ ], [C ₃ ] in which only broadcast waves from one station can be received.
Because there is a large area difference between the area and the area where broadcast waves from multiple broadcasting stations can be received inside,
At the time of switching the screen corresponding to these areas, it is necessary to change the scale. Therefore, at this time,
Control is performed in the same manner as in the above embodiment. That is, in the above step S11, a state in which broadcasting can be newly received from one station, a state in which an increase from one station to two stations, or a state in which two stations have decreased from one station have occurred. If it is determined, as shown in FIG. 7, the corresponding area is specified as in the previous embodiment (step S5), and this area is newly displayed on the in-vehicle display 14 (step S6).

On the other hand, when it is determined in step S11 that the received broadcast station is in the state of two stations and there is no change, or that the number of stations is increased or decreased from two to three or three to two. In this case, the screen displayed at that time is a display state of a screen corresponding to an area having a small area. By scrolling this screen, it is possible to correspond to a change in the position of the own vehicle. For this purpose, first, the scroll amount and the scroll direction are set as described later (step S12), the screen is scrolled according to the settings (step S13), and the process returns to step S1.

The setting of the scroll amount and the setting of the scroll direction will be described with reference to FIG. 8. In FIG. 8, while passing through a position in the area [A ₁ * B ₃ ],
In vehicle display 14, when the map of the range indicated in the figure G ₄ is displayed, the area including the vehicle position [A
₁ * B ₂ ], when the increase of the radio wave intensity from the B broadcast station is detected, the traveling distance in the area [A ₁ * B ₃ ] is determined by the vehicle speed signal from the vehicle speed sensor 21. The skew amount is set by integrating and calculating, and multiplying the travel distance by the scale. Also, at this point, since the radio wave intensity from the B broadcast station has increased, the own vehicle is traveling in a direction approaching the B broadcast station. Therefore, as shown in Table 2, the center G _{C4 of} the screen is set to the B G The direction toward the broadcast station is set as the scroll direction. In response to such setting, as shown in FIG. 8, the previous display range G ₄ of the screen so switched to the display state in the regions shown in figure G ₅ is scrolled.

[0033]

[Table 2]

[0034] performing running in display state of the screen G ₅ which is scrolled as described above, as shown in FIG. 9, the vehicle is located, the area including the position [A ₁ * B ₂ * C _3] When entering, the scroll amount corresponding to the traveling distance in the area [A ₁ * B ₃ ] including the position is obtained, and the center G _{C5 of the} display range is set to the C broadcasting station where the electric field intensity has changed. The screen is scrolled such that the screen is moved in the direction to go. Thus, the display screen is changed to the range of the map shown in figure G _6. Hereinafter, similarly, the scroll amount according to the traveling distance in each area and the scroll direction shown in Table 2 are sequentially set in the course of traveling, and the screen is scrolled, whereby the screen is scrolled. The screen changes automatically.

As described above, in this embodiment, the display screen is made to follow a change in the position of the vehicle by scrolling the screen. In this case, since the screen changes continuously, it is easy to grasp the vehicle position before and after the change in the screen. That is, in the above-described embodiment, for example, each time a change occurs in the broadcast station that can receive the broadcast radio wave and the received electric field strength, the corresponding area is newly specified, and the control of switching to the specific screen is performed. However, discontinuous screen switching occurs before and after this switching. In this case, it becomes difficult to immediately grasp the position of the host vehicle immediately after the switching on the new screen. In particular, in an area where the number of receivable broadcast stations is large and the broadcast station and the electric field strength can be subdivided into smaller areas, the above-described discontinuous screen switching is performed. It may occur frequently during the operation, which may impair convenience.

Therefore, when traveling in an area where the number of broadcasting stations is large and thus the area is subdivided into narrower areas, as in this embodiment, scrolling in which the continuity of the screen is maintained is achieved. By changing the screen mainly based on
It is easy to grasp the position of the vehicle, thereby improving the convenience as the travel guidance device.

In this embodiment, the screen is scrolled when it is determined that the area in which the vehicle is traveling has changed. However, the direction of the change in the electric field intensity when the vehicle enters a new area is determined. It is also possible to set a scroll direction and to scroll the screen sequentially according to the traveling distance during traveling in this area. As a result, the amount of scrolling at one time can be made smaller, and the screen continuously moves in accordance with the movement of the own vehicle. Therefore, it is easier to grasp the position of the own vehicle on the screen. As a result, the feeling of anxiety as to whether or not to get lost is further eliminated, and the feeling of comfort during traveling is improved. In this case, in the same area, when scrolling the screen sequentially according to the traveling distance, it can be determined from the radio wave intensity from each broadcasting station that "the vehicle is still in the area". Regardless, if the area deviates from the screen, scrolling is stopped. That is, when the traveling direction is changed, the scroll direction and the traveling direction are shifted during traveling in the same area, and when traveling in the same area for a long distance in this state, the area where the vehicle is located is located. May be displaced from the screen. Such inconvenience can be solved by using the scroll stop control as described above.

In each of the above-described embodiments, the electric field strength centering on each broadcasting station is set to three levels of large, medium, and small, and a subdivision area that can be divided by the difference in the overlapping state of each strength is set. An example in which the center position and the like of each subdivision area are stored in the memory device in advance has been described, but, for example, the position and transmission output of the broadcast station are stored, and the broadcast station is stored in accordance with the detected electric field strength. It is also possible to calculate the distance from the vehicle and specify the area where the vehicle is located. In this case, the same calculation is performed on the received radio waves from a plurality of broadcast stations, and the overlapping of the ranges corresponding to the obtained distances enables more detailed identification of the vehicle position.

In each of the above embodiments, F
An example in which the radio receiver 10 is equipped in combination with the radio receiver 10 equipped to listen to the M radio has been described. In this case,
For example, when operating the vehicle guidance system having the above configuration while listening to the radio broadcast, the radio broadcast is interrupted for a very short time when the tuning frequency changing unit 11 performs the sweep operation over the FM broadcast frequency band. . Therefore,
In addition to a radio broadcast receiver, for a vehicle navigation device, a reception comprising a high-frequency amplifier circuit 2, a frequency mixer 3, a local oscillator 4, an intermediate frequency amplifier circuit 5, and a tuning frequency changing unit 11 in FIG. It is also possible to provide a dedicated machine. In addition, instead of the sweeping operation over the FM broadcast frequency band, a configuration in which the tuning frequency is changed in multiple stages in accordance with each transmission frequency for each receivable broadcast station, or a configuration using a television broadcast radio wave or the like is adopted. It is also possible.

[0040]

As described above, the travel guidance device according to the first aspect of the present invention provides a traffic guidance system for each of a plurality of broadcasting stations.
Boundary lines and the electric field strength of broadcast radio waves from these broadcasting stations
The boundary lines, each having a threshold level, are defined as section lines, and
Multiple districts that divide the area around the broadcasting station by inter-line
The image area is memorized, and individual
The presence or absence of transmitted radio waves that can be received from
Store the height as the reception condition corresponding to each partitioned area.
Storage means, a receiver for receiving a transmission radio wave from each broadcasting station, and an inside / outside discrimination for discriminating whether the own position is inside or outside a receivable area based on whether or not the transmission radio wave is received. means
(29) and said threshold level the electric field intensity of the radio wave signal received
And electric field intensity detecting means for detecting the electric field intensity detected in a plurality of stages by comparing the electric field intensity detected in the internal / external judging means and the electric field intensity detected in the plural stages in each partition area.
Area that matches the reception conditions
The configuration is provided with a self-position specifying means for specifying the image area as the area where the user is located, and a display control means for displaying a map including the specified area on a display.

[0041] Thus, with whether may receive radio wave transmitted from a broadcast station and further by discriminating, based on the intensity of radio waves received is identified to the extent that the self-position is more granular. This allows the display to display a map that is smaller in scale and, therefore, provides a more detailed view of the range in which you are located, resulting in reduced anxiety when traveling in an unfamiliar area, Thereby, there is an effect that comfort can be improved.

According to a second aspect of the present invention, there is provided the travel guidance device according to the first aspect, wherein the display is provided.
The control means controls the electric field strength detected by the electric field strength detecting means.
In this configuration, the display screen is scrolled in the changing direction .

Thus, the screen can be changed according to the change of the self-position.
Is changed by scrolling.
Continuity is maintained. This allows you to self
The risk of losing the position is reduced, and as a result
The it is possible to row run while constantly monitors in the screen
Thus, there is an effect that the comfort during traveling can be further improved .

Further, according to a third aspect of the present invention, there is provided the travel guidance device according to the second aspect, wherein the display is provided.
When the control means is traveling in the same area,
For scrolling the surface, and the self-position
It is determined that you are in the area by specific means
The area on the display screen
This is a configuration in which scrolling is stopped when the scrolling is performed.

As a result, while traveling in the same area,
Scroll direction and running by changing line direction
When the vehicle runs long distances in this state
, The area where you are located is off the screen
The inconvenience described above can be eliminated .

[Brief description of the drawings]

FIG. 1 is a functional block diagram of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a receiver in the vehicle travel guidance device according to one embodiment of the present invention.

FIG. 3 is a block diagram showing a detailed configuration of a high-frequency amplifier circuit in the receiver.

FIG. 4 is a control block diagram showing an overall configuration of the vehicle travel guidance device.

FIG. 5 is an explanatory diagram of a subdivision area of a region in the vehicle travel guidance device.

FIG. 6 is a control flowchart showing a control procedure performed by a display control device in the vehicle travel guidance device.

FIG. 7 is a control flowchart showing a control procedure performed by a display control device in a vehicle travel guidance device according to another embodiment of the present invention.

FIG. 8 is an explanatory diagram of scroll control of a display screen in another embodiment.

FIG. 9 is an explanatory diagram of scroll control of a display screen performed after the screen display of FIG. 8;

[Explanation of symbols]

Reference Signs List 10 receiver 13 memory device (storage means) 14 in-vehicle display (display) 21 vehicle speed sensor (traveling distance detecting means) 29 inside / outside discriminating means 30 electric field strength detecting means 31 own vehicle position specifying means (self position specifying means) 32 display control means

Continuation of the front page (56) References JP-A-4-233577 (JP, A) JP-A-64-78180 (JP, A) JP-A-63-151879 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G01C 21/00 G01S 5/02 G08G 1/0969 G09B 29/10

Claims (3)

(57) [Claims] 1. A boundary of a coverage area of each of a plurality of broadcasting stations.
Line and the electric field strength of the broadcast waves from these stations
The boundary line where the threshold level is
While storing a plurality of sub-areas that divide the side area,
Transmission power that can be received from individual broadcast stations in each partitioned area
The presence or absence of waves and the level of electric field strength correspond to each sectioned area
Storage means for storing as a reception condition, a receiver for receiving the radio wave transmitted from each broadcast station, and out of the coverage area of the self-position each broadcasting station by the presence or absence of reception of the radio wave transmitted from each broadcast station either a field strength detection means for detecting in a plurality of stages of electric field strength of the radio signal by comparing between the threshold level and the outdoors discrimination means for performing one of the discrimination is, received from a broadcast station receivable in the area at, the outdoors discrimination The result of the judgment by the means and detected in multiple stages
And the electric field intensity of each divided area stored in the storage means
Self-position specifying means for collating with a reception condition and specifying a section area corresponding to the matched reception condition as a section where the user is located; and a display control means for displaying a map including the specified section on a display. A travel guidance device comprising a step and a step . 2. The method according to claim 1, wherein said display control means includes means for detecting said electric field intensity.
Display screen in the direction of change of detected electric field strength
The traveling guidance device according to claim 1, wherein the traveling guidance device is scrolled . 3. The vehicle according to claim 1, wherein said display control means runs in the same area.
To scroll the display screen during
And the self is identified by the self-locating means.
If it is determined that the
Scroll when the area shifts from the screen of
The travel guidance device according to claim 2, wherein the vehicle stops .