JP2006184093A - Navigation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a navigation device dispensing with a frequent change of a channel, when a program of the same broadcasting station or a broadcasting station in the same group as a broadcasting station under listening at present is listened to continuously even after movement from its broadcasting area. <P>SOLUTION: Each electric field strength 41, 42 on a recommended route of a broadcasting electric wave from each transmitting station is calculated from the distance to the transmitting station in the broadcasting station. Each electric field strength 41, 42 of the broadcasting electric wave from each transmitting station is compared each other, and thereby spots 35-39 where the strength relation between the electric field strength 41 of the broadcasting electric wave from one transmitting station and the electric field strength 42 of the broadcasting electric wave from the other transmitting station is changed are calculated. Then, a channel from which the program is listened to is switched from a channel of the broadcasting electric wave having the electric field strength 41 to a channel of the broadcasting electric wave having the electric field strength 42, at the spot 39 where the relation is changed finally. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a navigation device having a function of receiving terrestrial broadcasting.

By using television broadcast station channel information stored in the storage device of the navigation system, it is possible to automatically switch to the channel of the same broadcast station or affiliated broadcast station, so that the program can be watched continuously. There has been known a television receiver for a mobile body that enables this (Patent Document 1).
Japanese Patent Laid-Open No. 7-284030

  In the mobile television receiver of the invention of Patent Document 1, when receiving radio waves of a broadcasting station in an area where a plurality of frequencies of the same broadcasting station exist, the radio wave having a stronger frequency is received. For this reason, depending on the path | route which drive | works the area where two or more frequencies of the same broadcasting station exist, the received frequency may switch many times. When such switching of the frequency to be received frequently occurs, there is a problem that this switching becomes annoying and annoying for the viewer.

(1) The invention of claim 1 is a navigation device having a function of receiving and outputting broadcasts, and includes route search means for searching for a recommended route from the departure point to the destination, and a broadcasting station of a set channel. Broadcast output means for receiving and outputting the broadcast, a first electric field strength of the broadcast radio wave of the first broadcast station in the first broadcast area, and a second broadcast area adjacent to the first broadcast area. Electric field intensity detecting means for detecting the second electric field intensity of the broadcast radio waves of the two broadcasting stations, and when the detected first electric field intensity and the second electric field intensity satisfy a predetermined condition, the first broadcast Channel switching means for switching the channel from the first broadcasting station in the area to the second broadcasting station in the second broadcasting area, and on the recommended route, from the second broadcasting station in the second broadcasting area to the first broadcasting station. Channel to the first broadcasting station in the broadcasting area Channel switching determination means for determining whether or not there is a case of switching between the first and second field strengths, even if the detected first field strength and second field strength satisfy a predetermined condition. If the channel switching determining means determines that there is a case where the channel is switched from the second broadcasting station in the second broadcasting area to the first broadcasting station in the first broadcasting area first on the recommended route, The channel is not switched from the first broadcasting station in the second broadcasting area to the second broadcasting station in the second broadcasting area.
(2) The invention of claim 2 is a navigation device having a function of receiving and outputting broadcasts, and includes route search means for searching for a recommended route from the departure point to the destination, and a broadcast station of the set channel. Broadcast output means for receiving and outputting the broadcast, a first electric field strength of the broadcast radio wave of the first broadcast station in the first broadcast area, and a second broadcast area adjacent to the first broadcast area. Electric field intensity detecting means for detecting the second electric field intensity of the broadcast radio waves of the two broadcasting stations, and when the detected first electric field intensity and the second electric field intensity satisfy a predetermined condition, the first broadcast Channel switching means for switching the channel from the first broadcasting station in the area to the second broadcasting station in the second broadcasting area, and the number of broadcast radio waves of the first broadcasting station in the first broadcasting area on the recommended route 3 field strength and the second broadcast area second An electric field intensity calculating means for calculating the fourth electric field intensity of the broadcast radio wave of the broadcasting station is further provided, and the channel switching means satisfies the predetermined condition between the detected first electric field intensity and the second electric field intensity. Even in this case, based on the third electric field strength and the fourth electric field strength obtained by the calculation, the second broadcasting station in the second broadcasting area is ahead of the first broadcasting area on the recommended route. When it is determined that there is a case where the channel is switched to the first broadcasting station, the channel is not switched from the first broadcasting station in the first broadcasting area to the second broadcasting station in the second broadcasting area. To do.
(3) The invention according to claim 3 is the navigation device according to claim 2, wherein the channel of the first broadcasting station in the first broadcasting area is switched to the channel of the second broadcasting station in the second broadcasting area. In addition, when the first electric field strength of the broadcast radio wave of the first broadcasting station in the first broadcasting area detected by the electric field strength detecting means becomes equal to or lower than a predetermined value, the first electric field strength calculated by the electric field strength calculating means is calculated. The arrival time calculating means for calculating the arrival time to the point where the third electric field strength of the broadcast radio wave of the first broadcasting station in the broadcast area is equal to or higher than a predetermined value, and the arrival time calculated by the arrival time calculating means are notified. And arrival time notification means.
(4) The invention of claim 4 is a navigation device having a function of receiving and outputting broadcasts, and includes route search means for searching for a recommended route from the departure place to the destination, and a broadcast station of the set channel. Broadcast output means for receiving and outputting the broadcast, a first electric field strength of the broadcast radio wave of the first broadcast station in the first broadcast area, and a second broadcast area adjacent to the first broadcast area. Electric field strength detection for detecting the second electric field strength of the broadcast radio wave of the second broadcasting station and the third electric field strength of the broadcast radio wave of the third broadcast station in the third broadcast area adjacent to the second broadcast area Means and a channel from the first broadcast station in the first broadcast area to the second broadcast station in the second broadcast area when the detected first and second electric field strengths satisfy a predetermined condition. On the recommended route. Electric field strength calculating means for calculating the fourth electric field strength of the broadcast radio wave of the second broadcasting station in the second broadcasting area by calculation, and the channel switching means includes the detected first electric field strength and the second electric field strength Even when the electric field strength satisfies the predetermined condition, if the fourth electric field strength obtained by calculation does not satisfy the condition, the first broadcasting station in the first broadcasting area is changed to the second broadcasting area. The channel is switched from the first broadcasting station in the first broadcasting area to the third broadcasting station in the third broadcasting area without switching the channel to the second broadcasting station.
(5) The invention of claim 5 is an electric field intensity detecting means for detecting the electric field intensity of the broadcast radio wave of the broadcast station in the broadcast area, and a broadcast station in the broadcast area where the electric field intensity of the broadcast radio wave is strong among the plurality of broadcast areas. And a channel switching means for switching channels, wherein the broadcasting station channels switched by the channel switching means are continuously transmitted multiple times between the broadcasting stations of the same two broadcasting areas. When switching, the number of times of switching is reduced.
(6) The invention according to claim 6 is the navigation device according to claim 5, wherein the number of times of switching is reduced to one.

  According to the present invention, since the channel to be received is switched based on the electric field strength on the recommended path of each channel calculated in advance, frequent channel switching is performed when trying to watch a program of the same broadcasting station or the same series of broadcasting stations. Does not occur.

  A configuration of a navigation apparatus according to an embodiment of the present invention is shown in FIG. The navigation device 1 in FIG. 1 can receive and display a terrestrial digital broadcast in addition to a normal navigation function such as a map display. The navigation device 1 includes a control circuit 11, a ROM 12, a RAM 13, a current location detection device 14, an image memory 15, a display monitor 16, a speaker 17, an input device 18, a terrestrial digital broadcast receiving unit 19, and a disk drive 110. The disc drive 110 is loaded with a DVD-ROM 111 on which map data is recorded. The map data includes broadcast area information, map display data, route search data, and the like. The map display data has map data of a plurality of scales from a wide area to details, and the scale of the display map can be changed according to the passenger's request.

  The broadcast area information is transmitted from the broadcast area information indicating the area where the broadcast wave from the transmitting station transmitting the broadcast wave of the digital terrestrial broadcasting reaches, the receiving channel of the broadcast wave, the position of the transmitting station, and the transmitting station. Information on the output of broadcast radio waves, information on affiliated stations of broadcast stations, and the like are included. Here, terrestrial digital broadcasting refers to broadcasting in which the contents of broadcasting are digitized and broadcast on terrestrial waves. Terrestrial digital broadcasting includes terrestrial digital television broadcasting and terrestrial digital audio broadcasting.

  The control circuit 11 includes a microprocessor and its peripheral circuits, and performs various controls by executing a control program stored in the ROM 12 using the RAM 13 as a work area. When the control circuit 11 performs a predetermined route search process based on the map data stored in the DVD-ROM 111, the processing result is displayed on the display monitor 16 as a recommended route.

  The current position detection device 14 is a device that detects the current position of the vehicle. For example, a vibration gyro 14a that detects the traveling direction of the vehicle, a vehicle speed sensor 14b that detects the vehicle speed, and a GPS signal from a GPS (Global Positioning System) satellite. It consists of a GPS sensor 14c and the like. The navigation device 1 determines a map display range, a route search start point, and the like based on the current location of the vehicle detected by the current location detection device 14, and displays the current location on the map.

  The image memory 15 stores image data to be displayed on the display monitor 16. The image data includes road map drawing data and various graphic data, which are appropriately generated based on map data stored in the DVD-ROM 111 read by the disk drive 110. The navigation device 1 can perform map display and the like by using the image data generated in this way.

  The display monitor 16 provides various information such as a road map in the vicinity of the vehicle position to the passenger of the navigation device 1 as a screen display based on various information such as map data. Further, the display monitor 16 outputs video information of terrestrial digital broadcast received by the terrestrial digital broadcast receiver 19. The speaker 17 provides a passenger with various information such as a map near the vehicle position based on various information such as map data. The speaker 17 outputs the terrestrial digital broadcast audio information received by the terrestrial digital broadcast receiver 19.

  The input device 18 has an input switch for a passenger to set a destination of the vehicle, and this is realized by an operation panel, a remote controller, or the like. The occupant selects the destination by setting the destination by operating the input device 18 in accordance with the instruction on the display screen of the display monitor 16 or the instruction of the voice from the speaker 17. In addition, a broadcast station received by the terrestrial digital broadcast receiver 19 can be selected by the input device 18.

  When the destination is set by the occupant, the navigation apparatus 1 performs a route calculation from the current location detected by the current location detection means 14 to the destination based on a predetermined algorithm. The route thus obtained (hereinafter referred to as a recommended route) is displayed on the screen separately from other roads by changing the display form, for example, the display color. Thus, the passenger can recognize the recommended route on the map on the screen. In addition, the navigation device 1 instructs the occupant to travel in the direction of travel using a screen, voice, or the like so that the vehicle can travel according to the recommended route.

  The terrestrial digital broadcast receiver 19 receives the terrestrial digital broadcast and outputs the content of the received broadcast to the display monitor 16 and the speaker 18. The disk drive 110 reads map data for displaying a map on the display monitor 16 from the loaded DVD-ROM 111. The map data may be read from a recording medium other than the DVD-ROM, such as a CD-ROM or a hard disk.

  Next, the terrestrial digital broadcast receiver 19 will be described with reference to FIG. The terrestrial digital broadcast receiving unit 19 includes antennas 21 and 22, tuners 23 and 24, demodulation units 25 and 26, tuner control circuit 27, decoding unit 28, decoding unit RAM 29, NTSC (National Television System Committee) encoding unit 210, audio signal A DA conversion unit 211, a reception unit control circuit 212, a reception unit ROM 213, and a communication unit 214 are included. Here, the part of the broken line 215 is called the front end part 215 and the part of the broken line 216 is called the back end part 216.

  The antennas 21 and 22 have a function of receiving terrestrial digital broadcasting. The tuners 23 and 24 have a function of setting broadcast channels received by the antennas 21 and 22, a function of detecting electric field strength of signals received by the antennas 21 and 22, and a function of converting analog signals into digital signals. . The demodulation units 25 and 26 have a function of digitally demodulating the signals converted into digital signals by the tuners 23 and 24.

  The tuner control circuit 27 has a function of controlling the channels set by the tuners 23 and 24, a function of synthesizing signals from the two tuners 23 and 24, and outputting them to the decoding unit 28, and one of the tuners 23 and 24. It has a function of outputting only signals to the decoding unit 28. The tuner control circuit 27 switches the channel set to the tuner from one channel to another channel. Further, by combining the signals from the two tuners 23 and 24 and outputting them to the decoding unit 28, the shape of the rectangular wave of the digital signal output to the decoding unit 28 is improved.

  The decoding unit 28 has a function of compressing / decompressing and extracting a digital video signal and a digital audio signal which are MPEG-compressed included in the terrestrial digital wave signal. The decoding unit RAM 29 has a function as a work area for the compression / decompression processing in the decoding unit 28. The NTSC encoding unit 210 has a function of converting the digital video signal extracted by the decoding unit 28 into an NTSC analog output video signal and outputting it to the monitor 16. The audio signal DA conversion circuit 211 has a function of converting the digital audio signal extracted by the decoding unit 28 into an analog audio signal and outputting the analog audio signal to the speaker 17. As for video output, NTSC is taken as an example, but RGB (DVI (Digital Video Interface)) used in PAL ((Phase Alternation by Line System), PC (Personal Computer), etc. High Definition (Multimedia Interface) may be used.

  The reception unit control circuit 212 has a function of controlling operations of the tuner control circuit 27 and the decoding unit 28. Under the control of the receiving unit control circuit 212, the channel of one of the tuners 23 and 24 set by the tuner control circuit 27 is scanned to detect a receivable channel. The function communication unit 214 has a function of inputting an output from the control circuit 11 and outputting the output to the reception unit control circuit 212.

  Next, the contents of the channel switching process in the navigation device 1 according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 3 is a diagram for explaining how the vehicle moves between broadcast areas. The host vehicle 31 moves from the broadcast area 33 to the broadcast area 34 through the recommended route 32. In the broadcast area 33, it is assumed that the program of the broadcast station A is broadcast on, for example, three channels. Then, it is assumed that the host vehicle 31 is currently viewing this program. The channel of the currently viewed program is hereinafter referred to as the currently viewed channel. In the broadcast area 34, which is the next destination, the program of the broadcast station B, which is the same broadcast station as the broadcast station A that is broadcasting the program currently being viewed, or the broadcast station of the affiliated station, is broadcast on, for example, seven channels. It is assumed that In order to continue viewing the program broadcasted by the broadcast station A, the passenger of the host vehicle 31 views the program of the broadcast station B in the broadcast area 34 that is the next destination. The channel that is viewed in the next destination broadcast area is hereinafter referred to as a switching target channel.

  The points 35 to 39 on the recommended route 32 are points where the electric field strength of the broadcast radio wave of the broadcasting station A is the same as the electric field strength of the broadcast radio wave of the broadcasting station B, that is, when the point passes the point, 3 shows the point where the electric field strength of channel 3 is stronger or weaker than the electric field strength of channel 7 which is the electric field strength of the broadcast radio wave of broadcasting station B. That is, the right side of the line connecting the points 35, 36, 37, 38, and 39 has a strong 3-channel electric field strength, and the left-hand side has a strong 7-channel electric field strength. A point 310 on the recommended route 32 is a position temporarily deviating from the broadcast area 33 on the recommended route, and a point 311 is a position returning to the broadcast area 33 again.

  In the conventional mobile television receiver, the channel for viewing the program is simply switched according to the electric field strength of the channel. Therefore, at point 35, the channel for viewing the program is switched from 3 channels to 7 channels, and at point 36, Switch from channel 7 to channel 3. At point 37, switch again from channel 3 to channel 7. At point 38, switch again from channel 7 to channel 3. And at point 39, channel 3 to channel 7. Switch to. In this way, at the point 39, until the channel is switched from the 3rd channel to the 7th channel, the channel is switched between the channel currently being viewed and the channel to be switched many times. It feels very annoying and annoying for viewers of the program.

  On the other hand, in the invention of the first embodiment of the present invention, at the points 36 to 38 on the recommended route 32, the channel is not switched, and the channel for viewing the program for the first time by the point 39 is changed from 3 channels to 7 channels. That is, the channel is switched from the broadcasting station A to the broadcasting station B. At points 310 and 311 on the recommended route 32, the viewing of the program is interrupted halfway, but since the channel for viewing the program is switched only at point 39, the viewer does not feel uncomfortable or irritating.

  Next, referring to FIG. 4, the electric field strength on the recommended path 32 of the broadcast radio wave of the broadcast station A, that is, the electric field strength on the recommended path 32 of the broadcast radio wave of the channel currently being viewed, and the recommended broadcast radio wave of the broadcast station B The electric field intensity on the path 32, that is, the electric field intensity on the recommended path 32 of the broadcast radio wave of the channel to be switched will be described. The electric field strength curve 41 is the electric field strength on the recommended channel 32 of the three channels that are the currently viewing channel on which the program of the broadcasting station A currently being viewed is broadcast. The electric field strength curve 42 is a channel to be switched on which the program of the broadcast station B that is the same broadcast station as the broadcast station A that is broadcasting the program currently being viewed or the affiliated station is broadcast. The electric field strength of 7 channels.

  Points 36 to 39 in FIG. 4 are points where the electric field strength of the channel currently being viewed on the recommended path 32 in FIG. 3 and the electric field strength of the channel to be switched are the same value, that is, when the point passes the point, This is a point where the electric field strength becomes stronger or weaker than the electric field strength of the channel to be switched. Further, a point 310 in FIG. 4 is a position temporarily deviating from the broadcast area 33 on the recommended route 32 in FIG. 3, that is, a point at which viewing of the program of the currently viewed channel becomes impossible, and a point 311 The position where the program returns to the broadcast area 33 again, that is, the point at which the program on the currently viewed channel can be viewed again. The required limit value described in FIG. 4 refers to the minimum electric field strength of broadcast radio waves that can be viewed by the terrestrial digital broadcast receiver 19. For example, 60 dBμV / m.

  Of points where the field intensity of the currently viewed channel and the field intensity of the switching target channel are the same as points 36 to 38, when the recommended path 32 is advanced, the field intensity of the currently viewing channel and the switching target channel again. In the following, a field strength change point is referred to as a field strength change point. Also, as indicated by point 39, the field strength of the currently viewed channel is switched again from the point where the field strength of the currently viewed channel and the field strength of the switching target channel have the same value even if the recommended path 32 is advanced. Hereinafter, a channel switching point that does not have the same value as the electric field strength of the target channel is referred to as a channel switching point. In addition, the point where the electric field strength of the broadcast radio wave of the currently viewed program before the channel switching point becomes smaller than the required limit value and the program cannot be viewed is hereinafter referred to as a viewing interruption start point. In addition, the point at which viewing is enabled again is referred to as a viewing interruption end point.

  The electric field strength on the recommended route of the broadcast radio wave from the transmitting station in each broadcasting area is calculated from the position of the transmitting station of digital terrestrial broadcasting and the output value of the transmitting station stored in the DVD-ROM 111 without directly measuring. be able to. Calculation of the electric field strength on the recommended path will be described with reference to FIG.

  A symbol 51 in FIG. 5A indicates a transmitting station in the broadcasting area of digital terrestrial broadcasting, and a circle 52 indicates a point away from the transmitting station 51 by a distance r. The relationship between the point 52 away from the transmitting station 51 by the distance r and the electric field strength at that point is inversely proportional to the square of the distance as shown in FIG. Therefore, if the output value of the broadcast radio wave at the transmitting station 51 is known, the electric field strength at a point r away from the transmitting station 51 can be calculated.

  As described above, the electric field strength on the recommended route can be calculated from the position of each point on the recommended route and the distance from the transmitting station at that position. Then, by calculating and comparing the electric field strength of the broadcast radio wave from the transmitting station in each broadcast area, the recommended route becomes the field strength change point on the recommended route, the channel switching point, the viewing suspension start point, and the viewing suspension end point. You can see if it exists above. And when it exists, the position of the electric field strength change point, the channel switching point, the viewing interruption start point, and the viewing interruption end point on the recommended route is known.

  For example, as a result of calculating the electric field strength on the recommended route, if the electric field strength of the channel currently being viewed and the electric field strength of the channel to be switched become the same value, proceeding further on the recommended route will result in again the electric field strength of the channel currently being viewed. If the field strength of the channel to be switched has the same value, that point becomes the field strength change point, and if it does not become the same value, that point becomes the channel switching point. In addition, when the recommended route is followed, the point where the electric field strength of the currently viewed channel is below the required limit value is the starting point of the viewing interruption. Is the end point of viewing interruption.

  Next, the operation of the channel switching process of the control circuit 11 of the navigation device according to the first embodiment of the present invention will be described using the flowcharts of FIGS. 6 to 8 are executed by a program that starts when a destination is input. In the start state, the terrestrial digital broadcast is received by the antenna 21 and the terrestrial digital broadcast program is viewed by the tuner 23.

  In step S601, the recommended route 32 from the departure point to the destination is searched. In step S602, information on a channel for continuing to watch a program of the same or the same broadcast station as the broadcast area through which the recommended route 32 passes is acquired from the broadcast area information stored in the DVD-ROM 111. In step S603, the program of the same or the same series of broadcast stations is calculated from the position of the transmission station in the broadcast area of the same or the same series of broadcast stations in each broadcast area and the output value of the broadcast radio wave transmitted from the transmission station. The electric field strength on the recommended path 32 of the broadcast radio wave of the broadcast station in each broadcast area that is received in order to continue watching is calculated.

  In step S604, it is determined whether or not the electric field intensity change points 36 to 38 exist on the recommended path 32. If a positive determination is made in step S604, the process proceeds to step S605. If a negative determination is made in step S604, the process proceeds to step S801 in FIG. In step S605, the passenger is notified that channel switching frequently occurs. In step S605, the occupant is allowed to select either the “frequent switching prevention mode” for preventing frequent channel switching or the “field strength switching mode” for switching the channel depending on the strength of the electric field strength. If the occupant selects the “frequent switching prevention mode”, the process proceeds to step S701 in FIG. When the occupant selects the “field strength switching mode”, the process proceeds to step S801 in FIG.

  In step S701 of FIG. 7, the broadcast interruption start point 310, the broadcast interruption end point 311 and the channel switching are calculated from the result of the electric field strength on the recommended path 32 of the broadcast radio wave of the broadcast station in each broadcast area calculated in step S603 of FIG. The position of the point 39 on the recommended route is calculated. In step S <b> 702, the current location detection device 14 detects information on the current location of the host vehicle 31. In step S703, it is determined whether the next destination is the viewing interruption start point 310 or the channel switching point 39. If the next destination is the viewing interruption start point 310, the process proceeds to step S704. If the next destination is the channel switching point 39, the process proceeds to step S705.

  In step S704, the tuner 23 of the terrestrial digital broadcast receiving unit 19 of the navigation device 1 detects the electric field strength of the currently viewed channel. In step S706, it is determined whether the electric field strength of the currently viewed channel is equal to or less than a required limit value. If step S706 is positive, the process proceeds to step S707. If step S706 is negative, the process returns to step S704. In step S707, the current location information is detected by the current location detection device 14. In step S708, the distance from the current location on the recommended route 32 to the viewing interruption end point 311 is calculated, and the required time to the viewing interruption end point 311 is calculated by dividing the distance by the vehicle speed detected by the vehicle speed sensor 14b. . In step S709, the speaker 17 announces that the viewing of the program is temporarily suspended, and the required time until the viewing suspension end point 311 is output from the display monitor 16 or the speaker 17. Then, the passenger of the own vehicle 31 is notified of the fact that the program is interrupted and the time until viewing of the interrupted program can be resumed.

  In step S710, output of the terrestrial digital broadcast program to the display monitor 16 and the speaker 17 is stopped, and viewing of the terrestrial digital broadcast program is interrupted. In step S711, it is determined whether the electric field strength is greater than or equal to a required limit value. If step S711 is positive, the process proceeds to step S712. If step S711 is negative, the process returns to step S709. In step S712, output of the terrestrial digital broadcast program to the display monitor 16 and the speaker 17 is resumed, and viewing of the terrestrial digital broadcast program is started. In step S713, the current location device 14 detects current location information. In step S714, it is determined whether there is a viewing interruption start point 310 or a channel switching point 39 at the next destination. If step S714 is positive, the process proceeds to step S703. If step S714 is negative, the channel switching process is terminated.

  In step S <b> 705, the current location information is detected by the current location detection device 14. In step S715, it is determined whether or not the host vehicle 31 has reached a predetermined range from the channel switching point 39. If a positive determination is made in step S715, the process proceeds to step S716. If a negative determination is made in step S715, the process returns to step S705. In step S716, the electric field strength of the channel currently being viewed and the channel to be switched is detected. The electric field strength of the channel currently being viewed is detected by the tuner 23 of the terrestrial digital broadcast receiver 19. Further, the electric field strength of the channel to be switched is detected by the tuner 24 of the terrestrial digital broadcast receiver 19.

  In step S717, the electric field strength of the channel currently being viewed is compared with the electric field strength of the channel to be switched, and it is determined whether the electric field strength of the channel to be switched is stronger. If the channel to be switched is stronger than the electric field strength of the channel currently being viewed, that is, if the determination in step S717 is affirmative, the process proceeds to step S718. If step S717 is negative, the process returns to step S716. In step S718, the channel received by the tuner 23 is switched from the currently viewed channel to the switching target channel, and the program of the switching target channel is viewed.

  In step S <b> 801 of FIG. 8, the current location information is detected by the current location detection device 14. In step S802, the electric field strength of the channel currently being viewed and the channel to be switched is detected. The electric field strength of the currently viewed channel is detected by the tuner 23 of the terrestrial digital broadcast receiver 19. The electric field strength of the channel to be switched is detected by the tuner 24 of the terrestrial digital broadcast receiver 19.

  In step S803, the electric field strength of the currently viewed channel is compared with the electric field strength of the switching target channel to determine whether the electric field strength of the switching target channel is higher. If the channel to be switched is stronger than the electric field strength of the channel currently being viewed, that is, if the determination in step S803 is affirmative, the process proceeds to step S804. If step S803 is negative, the process returns to step S802. In step S804, the channel received by the tuner 23 is switched from the currently viewed channel to the switching target channel, and the program of the switching target channel is viewed. In step S805, it is determined whether there is a next channel to be switched. If there is a next channel to be switched, a negative determination is made in step S805, and the process proceeds to step S801. If there is no channel to be switched, an affirmative determination is made in step S805, and the channel switching process ends.

The navigation device according to the first embodiment of the present invention has the following operational effects.
(1) After the electric field strength of the channel currently being viewed and the electric field strength of the channel to be switched become the same value, the electric field strength of the channel currently being viewed and the electric field strength of the channel to be switched become the same value again. Until the point at which it becomes impossible to switch, the channel to be viewed does not switch between the channel currently being viewed and the channel to be switched. For this reason, even if the channel is switched to a broadcasting station in a broadcasting area where the electric field strength of the broadcasting radio wave is strong, even if the channel is continuously switched several times between the broadcasting stations in the same two broadcasting areas, In the embodiment of the invention, the number of times of switching can be reduced. For this reason, it is possible to reduce frequent channel switching which is unpleasant to the viewer and unpleasant.
(2) After the electric field strength of the channel currently being viewed and the electric field strength of the channel to be switched become the same value, the electric field strength of the channel currently being viewed and the electric field strength of the channel to be switched become the same value again. Until the point at which it becomes impossible to switch, the channel to be viewed does not switch between the channel currently being viewed and the channel to be switched. For this reason, even if the channel is switched to a broadcasting station in a broadcasting area where the electric field strength of the broadcasting radio wave is strong, even if the channel is continuously switched several times between the broadcasting stations in the same two broadcasting areas, In the embodiment of the invention, the number of times of switching can be reduced to one. For this reason, frequent channel switching that is unsightly to the viewer and harsh is not caused.
(3) Even when the currently viewed program is interrupted, the time until the program can be resumed is displayed, so that the viewer is not frustrated.

  Next, the contents of the channel switching process in the navigation device 1 according to the second embodiment of the present invention will be described with reference to FIG.

  FIG. 9 is a diagram for explaining how the host vehicle moves in a plurality of broadcast areas. The own vehicle 91 starts from the point A, passes through the recommended route 92, moves from the broadcast area 93 to the destination B through the broadcast area 94, the broadcast area 95, the broadcast area 96, and the broadcast area 97. In the broadcast area 93, it is assumed that the program of the broadcasting station A currently being viewed on the host vehicle 91 is broadcast on, for example, three channels. The channel currently being viewed in this way is hereinafter referred to as the currently viewing channel. In the broadcast areas 95 and 97, it is assumed that the program of the broadcast station A is broadcast on three channels.

  In the broadcast areas 94 and 96, the program of the broadcast station B, which is the same broadcast station as the broadcast station A that is broadcasting the program currently being viewed, or a broadcast station of the affiliated station, is broadcast on, for example, seven channels. It shall be. Therefore, on the recommended route 93, when the program of the same broadcast station as the broadcast station A that is broadcasting the currently viewed program or the broadcast station of the affiliated station is continuously viewed, the channel is changed from 3 channels in some places. Switch to channel 7. In this way, the 7 channels that are the channels that are switched from the currently viewed 3 channels in some places are hereinafter referred to as temporary switching target channels.

  Points 910 to 914 on the recommended path 92 are points where the electric field intensity of the 3 channel broadcast radio wave and the electric field intensity of the 7 channel broadcast radio wave have the same value, that is, the electric field intensity of the 3 channel after passing through that point is 7 channels. The point where the electric field strength is stronger or weaker is shown. Accordingly, when the channel for viewing the program is switched according to the electric field strength of the channel, the channel for viewing the program is switched from the 3 channel to the 7 channel when the own vehicle 91 arrives at the position of the point 910, and at the position of the point 912. The channel for viewing the program is switched from 7 to 3 channels. At point 913, the channel for viewing the program is switched from channel 3 to channel 7 again, and the channel for viewing the program is switched from channel 7 to channel 3 at point 914.

  A point 915 on the recommended route 92 is a position deviating from the broadcast area 93, and a point 916 is a position entering the broadcast area 95. A point 917 on the recommended route 92 is a position deviating from the broadcast area 95, and a point 918 is a point entering the broadcast area 97. Therefore, if the program of 3 channels is continuously viewed, the viewing of the program is interrupted at the point 915, the viewing of the program is resumed at the point 916, and the viewing of the program is interrupted again at the point 917. Program viewing is resumed at the point 918.

  By the way, when the currently viewed channel is temporarily switched to the temporarily switching target channel, there is an advantage of switching to the temporarily switching target channel if the displayed screen or sound is clear. However, if the screen or sound when switching to the temporarily switched channel is poor, the viewer will be disturbed and irritated.

  Therefore, in the second embodiment of the present invention, when the image quality and sound quality of the program of the temporarily switching target channel are poor, the channel to be viewed is not switched to the temporarily switching target channel, but is continuously viewed on the currently viewing channel. I have to. Whether the image quality or sound quality of the program of the temporarily switching target channel is poor is determined by whether or not the electric field strength of the temporarily switching target channel is equal to or higher than a predetermined value.

  The electric field strength of each channel on the recommended path 92 is calculated based on the output value of the transmitting station and the distance from the transmitting station in each broadcasting area, as in the first embodiment of the present invention. FIG. 10 shows the electric field strength on the recommended route 93 calculated by the distance from the transmitting station. The electric field strength curve 101 is a curve indicating the electric field strength of the three channels transmitted from the transmitting station in the broadcast area 93, that is, the electric field strength of the broadcast radio wave of the broadcasting station in the broadcasting area 93, and the electric field strength curve 102 is transmitted in the broadcasting area 94. 7 is a curve showing the electric field strength of the seven channels transmitted from the station, that is, the electric field strength of the broadcast radio wave of the broadcast station in the broadcast area 94. The electric field strength curve 103 is a curve indicating the electric field strength of the three channels transmitted from the transmitting station in the broadcast area 95, that is, the electric field strength of the broadcast radio wave of the broadcasting station in the broadcast area 95, and the electric field strength curve 104 is the broadcast area 96. 3 is a curve showing the electric field intensity of the three channels transmitted from the transmitting station, that is, the broadcast radio waves of the broadcast station in the broadcast area 96. An electric field strength curve 105 is a curve showing the electric field strength of the three channels transmitted from the transmitting station in the broadcast area 97, that is, the electric field strength of the broadcast radio wave of the broadcasting station in the broadcast area 97.

  In addition, the horizontal axis representing the recommended route in FIG. 10 is given the same numerals at positions corresponding to the points 910 to 918 in FIG. 9. The required limit value is the lower limit value of the electric field strength of the broadcast radio wave that can be viewed by the terrestrial digital broadcast receiver 19 as in the description of the first embodiment.

  In the second embodiment of the present invention, when the maximum values of the electric field curve 102 and the electric field curve 104 are not so different from the required limit value, for example, within two times the required limit value, 7 channels for viewing the program are set. Even if the channel is switched, only the broadcast with poor image and sound is received, so the channel for viewing the program is not switched to 7 channels. Then, the channel for viewing the program is not switched from the departure point A to the destination B, but is maintained at three channels. If the channel for viewing the program remains three channels, the program cannot be viewed between the point 915 and the point 916 and between the point 917 and the point 918. In this case, as in the case of the first embodiment, the time until the program can be resumed is notified to the passenger of the host vehicle, and the program is interrupted.

  Next, the operation of the channel switching process of the control circuit 11 in the navigation device 1 according to the second embodiment of the present invention will be described with reference to the flowcharts of FIGS. 11 and 12 is executed by a program that starts when a destination is input. In the start state, the terrestrial digital broadcast is received by the antenna 21 and the terrestrial digital broadcast program is viewed by the tuner 23. The same process steps as those in the flowcharts of FIGS. 6 to 8 in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In step S1140 of FIG. 11, when the channel is switched based on the electric field strength of the received broadcast radio wave from the electric field strength on the recommended path 93 calculated in step S603, the currently viewed channel is changed to the temporarily switched channel. Judge whether to switch. If step S1104 is positively determined, the process proceeds to step S1201 in FIG. If a negative determination is made in step S1204, the channel switching process ends.

  In step S1201 of FIG. 12, the maximum value of the electric field strength of the channel to be temporarily switched is determined to be a predetermined value from the result of the electric field strength on the recommended path 92 of the broadcast radio wave from the transmitting station calculated in step S603 of FIG. It is determined whether this is the case. If it is equal to or greater than the predetermined value, the process proceeds to step S801 in FIG. Then, the channel for viewing the program is switched by comparing the electric field strength of the channel currently being viewed with the electric field strength of the channel to be temporarily switched. At this time, “switching target channel” is read as “switching target channel or temporary switching target channel” in the flowchart of FIG. If a negative determination is made in step S1201, the process proceeds to step S702. In step S1203, it is determined whether the next destination is the viewing interruption start point 915, 917. If step S1203 is positive, the process proceeds to step S704. If step S1203 is negative, the process ends.

The navigation device according to the second embodiment of the present invention described above has the following operational effects.
(1) When the electric field strength of the temporarily switching target channel is weak, the channel switching to the temporarily switching target channel does not occur, so that the viewer is not disturbed and the annoying channel switching does not occur.

  In the second embodiment described above, the channels for viewing programs in the broadcast areas 93, 95, and 97 are the same for all three channels, but are not limited to the same channel. Moreover, although all the broadcasting areas 94 and 96 have 7 channels, they are not limited to the same channel.

  In the second embodiment described above, when the maximum value of the 7-channel electric field strength is less than or equal to the predetermined value, only 3 channels are received, and when the 3-channel program cannot be viewed, the viewing is only interrupted. Further, a route that minimizes the viewing interruption time during which the program of 3 channels cannot be viewed may be searched, and the recommended route may be changed to a route that minimizes the viewing interruption time. For example, the recommended route may be changed from the recommended route 92 to the route 98 in FIG. By changing the recommended route in this way, the time during which the program cannot be viewed is shortened, and the viewer's irritation caused by the interruption of the program can be alleviated.

  In the above embodiment, the electric field strength on the recommended route of the broadcast radio wave of the broadcast station in each broadcast area is calculated by the distance from the transmitting station in the broadcast station. The intensity may be calculated. Further, the electric field strength on the recommended route may be calculated from the electric field strength map that is obtained by measuring the distribution of the electric field strength from the transmitting station in advance and displaying it on the map.

  In each of the embodiments described above, an example is described in which the navigation device reads broadcast area information from a storage medium such as a DVD-ROM and the control circuit 11 calculates the electric field strength of the broadcast radio wave on the recommended route of the broadcast station. However, the present invention is not limited to this content. For example, the present invention can also be applied to a communication navigation apparatus that downloads the field intensity of broadcast radio waves on a recommended route of a broadcast station from an information distribution center using wireless communication using a mobile phone or the like. In this case, calculation of the electric field strength of the broadcast radio wave on the recommended route of the broadcasting station as described above is performed in the information distribution center, and the result is output from the information distribution center and distributed to the navigation device. Good. That is, the information distribution center is configured by a device that calculates the electric field strength on the recommended route and a device that outputs the electric field strength on the recommended route to the outside.

  In the above embodiment, the terrestrial digital broadcasting is applied. However, the terrestrial broadcasting is not limited to the terrestrial digital broadcasting. For example, the present invention may be applied to analog television broadcasting or analog radio broadcasting.

The correspondence between the elements of the claims and the embodiments will be described.
The route search means of the present invention corresponds to the control circuit 11, and the broadcast output means corresponds to the display monitor 16 and the speaker 17. The electric field strength detection means corresponds to the tuner 23 and the tuner 24, and the channel switching means corresponds to the tuner control circuit 27. Channel switching determination means and electric field strength calculation means correspond to the control circuit 11. The arrival time calculation means corresponds to the control circuit 11, and the arrival time notification means corresponds to the display monitor 16 and the speaker 17. In addition, the above description is an example to the last, and when interpreting invention, it is not limited to the correspondence of the component of said embodiment and the component of this invention at all.

It is a block diagram which shows the structure of the navigation apparatus in embodiment of this invention. It is a block diagram which shows the structure of a terrestrial digital broadcast receiver. It is a figure explaining the movement between the broadcast areas of the own vehicle in the 1st Embodiment of this invention. It is a figure for demonstrating the electric field strength on the recommendation path | route of the broadcast electromagnetic wave from the transmitting station in the 1st Embodiment of this invention. It is a figure which shows the relationship between the distance from the transmitting station in a broadcasting station, and the electric field strength of the broadcast radio wave from the transmitting station in the distance. It is a flowchart for demonstrating the channel switching process in the 1st Embodiment of this invention. It is a flowchart for demonstrating the channel switching process in the 1st Embodiment of this invention. It is a flowchart for demonstrating the channel switching process in the 1st Embodiment of this invention. It is a figure explaining the movement between the broadcast areas of the own vehicle in the 2nd Embodiment of this invention. It is a figure for demonstrating the electric field strength on the recommendation path | route of the broadcast electromagnetic wave from the transmitting station in the 2nd Embodiment of this invention. It is a flowchart for demonstrating the channel switching process in the 1st Embodiment of this invention. It is a flowchart for demonstrating the channel switching process in the 1st Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Navigation apparatus 11 Control circuit 14 Present location detection apparatus 16 Display monitor 17 Speaker 18 Input apparatus 19 Digital terrestrial broadcast receiving part 23, 24 Tuner 27 Tuner control circuit 31, 91 Own vehicle 32, 92 Recommended route 33, 34, 93-97 Broadcast Area 51 transmitting station

Claims (6)

A navigation device having a function of receiving and outputting a broadcast,
A route search means for searching for a recommended route from the starting point to the destination,
Broadcast output means for receiving and outputting the broadcast of the broadcasting station of the set channel;
The first electric field strength of the broadcast radio wave of the first broadcast station in the first broadcast area and the second electric field of the broadcast radio wave of the second broadcast station in the second broadcast area adjacent to the first broadcast area. Electric field strength detection means for detecting the strength;
When the detected first electric field strength and second electric field strength satisfy a predetermined condition, a channel is transmitted from the first broadcasting station in the first broadcasting area to the second broadcasting station in the second broadcasting area. Channel switching means for switching between,
Channel switching determination means for determining whether or not there is a case where a channel is switched from the second broadcasting station in the second broadcasting area to the first broadcasting station in the first broadcasting area on the recommended route. In addition,
Even when the detected first electric field strength and second electric field strength satisfy the predetermined condition, the channel switching means is arranged so that the channel switching judgment means is located on the recommended path ahead of the first electric field strength. When it is determined that there is a case where the channel is switched from the second broadcasting station in the second broadcasting area to the first broadcasting station in the first broadcasting area, the first broadcasting station in the first broadcasting area A navigation device, wherein a channel is not switched to a second broadcasting station in a second broadcasting area. A navigation device having a function of receiving and outputting a broadcast,
A route search means for searching for a recommended route from the starting point to the destination,
Broadcast output means for receiving and outputting the broadcast of the broadcasting station of the set channel;
The first electric field strength of the broadcast radio wave of the first broadcast station in the first broadcast area and the second electric field of the broadcast radio wave of the second broadcast station in the second broadcast area adjacent to the first broadcast area. Electric field strength detection means for detecting the strength;
When the detected first electric field strength and second electric field strength satisfy a predetermined condition, a channel is transmitted from the first broadcasting station in the first broadcasting area to the second broadcasting station in the second broadcasting area. Channel switching means for switching between,
A third electric field strength of the broadcast radio wave of the first broadcast station in the first broadcast area on the recommended route, and a fourth electric field strength of the broadcast radio wave of the second broadcast station in the second broadcast area; Further comprising electric field strength calculating means for calculating
The channel switching means is configured such that, even when the detected first electric field strength and second electric field strength satisfy the predetermined condition, the third electric field strength obtained by the calculation and the fourth electric field strength are calculated. When it is determined that there is a case where the channel is switched from the second broadcasting station in the second broadcasting area to the first broadcasting station in the first broadcasting area on the recommended route based on the electric field strength. Does not switch the channel from the first broadcast station in the first broadcast area to the second broadcast station in the second broadcast area. The navigation device according to claim 2, wherein
Before switching from the channel of the first broadcasting station in the first broadcasting area to the channel of the second broadcasting station in the second broadcasting area, the first broadcasting area detected by the electric field strength detecting means When the first electric field strength of the broadcast radio wave of the first broadcast station is equal to or less than a predetermined value, the third of the broadcast radio waves of the first broadcast station in the first broadcast area calculated by the electric field strength calculating means. An arrival time calculating means for calculating an arrival time to a point where the electric field intensity of
An arrival time notifying unit for notifying the arrival time calculated by the arrival time calculating unit. A navigation device having a function of receiving and outputting a broadcast,
A route search means for searching for a recommended route from the starting point to the destination,
Broadcast output means for receiving and outputting the broadcast of the broadcasting station of the set channel;
The first electric field strength of the broadcast radio wave of the first broadcast station in the first broadcast area and the second electric field of the broadcast radio wave of the second broadcast station in the second broadcast area adjacent to the first broadcast area. Electric field strength detecting means for detecting the strength and the third electric field strength of the broadcast radio wave of the third broadcast station in the third broadcast area adjacent to the second broadcast area;
When the detected first electric field strength and second electric field strength satisfy a predetermined condition, from the first broadcasting station in the first broadcasting area to the second broadcasting station in the second broadcasting area. Channel switching means for switching channels,
Electric field strength calculating means for calculating by calculation the fourth electric field strength of the broadcast radio wave of the second broadcasting station of the second broadcasting area on the recommended route;
The channel switching means has a fourth electric field strength obtained by the calculation satisfying a predetermined condition even when the detected first electric field strength and second electric field strength satisfy the predetermined condition. If not, the channel is not switched from the first broadcast station in the first broadcast area to the second broadcast station in the second broadcast area, and from the first broadcast station in the first broadcast area to the second broadcast station. A navigation apparatus characterized by switching a channel to a third broadcasting station in three broadcasting areas. Electric field strength detecting means for detecting the electric field strength of the broadcast radio wave of the broadcasting station in the broadcasting area;
In a navigation device comprising channel switching means for switching channels to a broadcast station in a broadcast area where the electric field strength of the broadcast radio wave is strong among a plurality of broadcast areas,
When the channel of the broadcasting station in the broadcasting area switched by the channel switching means switches continuously a plurality of times between the broadcasting station channels of the same two broadcasting areas, the number of switching is reduced. A navigation device. In the navigation apparatus according to claim 5,
A navigation device characterized in that the number of times of switching is reduced to one.

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