JP2013200133A - Navigation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a navigation device capable of providing route guidance that is easy to follow even in places where various types of ambient noise make it difficult for users to comprehend voice guidance generated from the navigation device.SOLUTION: A navigation device includes: display means 140; a speaker 170; a microphone 160; current location detection means 120; route guidance means 112 which allows a route guidance message, showing how to proceed from a current location on the basis of route information and current location information, to be displayed on the display means 140 as an image or to be generated as a voice message by the speaker 170; and voice guidance assessment means 113 which assesses whether to generate a route guidance message from the speaker 170 at a current location or not. The voice guidance assessment means 113 determines not to generate a route guidance message from the speaker 170 when magnitude of an audio signal input from the microphone 160 exceeds a predetermined threshold value, in which case the route guidance means switches the destination of the route guidance message from the speaker 170 to the display means 140.

Description

  The present invention relates to a navigation device that guides a user along a route from a current position to a destination.

  In recent years, navigation devices for pedestrians have been developed for the purpose of guiding a pedestrian from a departure point to a destination. When a user sets a destination, these navigation devices search for a route from the current position to the destination, perform display guidance or voice guidance along the route, and guide the user to the destination. it can.

  In such a navigation device, it is important for the user to provide easy-to-understand guidance so as not to make a mistake in the route, and various navigation devices have been developed to achieve the purpose.

  For example, in the following Patent Document 1 (Japanese Patent Laid-Open No. 7-146152), voice data reproduced after voice guidance itself or address information for storing reproduced voice data is saved in a buffer, and the user operates an input operation unit. Discloses a navigation device that reproduces voice guidance based on buffer data. According to this navigation device, even if the user has missed the voice guidance once reproduced, it can be reheard as necessary.

  Patent Document 2 below (Japanese Patent Laid-Open No. 2004-85963) inputs from a common microphone without adding a microphone or an amplifier in order to solve the problem that voice guidance is difficult to hear due to various noises. In-vehicle electronics that extracts audio voice / running noise, calculates the optimum gain to be added to the voice guidance in the gain control unit, and improves the clarity of the navigation voice by performing the optimum gain correction on the navigation voice in the equalizer Devices and programs are disclosed. According to this in-vehicle electronic device, it is possible to provide voice guidance that is easy for the user to hear when the surrounding noise is large.

JP 7-146152 A JP 2004-85963 A

  In the devices disclosed in Patent Documents 1 and 2 above, it is possible to rehearse the voice guidance as described above, or to improve the clarity and make it easier to hear. In such a navigation device, the size of the built-in speaker is limited because it is necessary to carry the navigation device. Therefore, even if the sound guidance output from the speaker is improved or increased when there are loud sounds such as car driving sound, railway driving sound, advertising sound, and hustle noise in the surroundings, There is a limit, and there is a problem that the user cannot hear voice guidance and cannot receive proper route guidance.

  Accordingly, an object of the present invention is to provide a navigation device capable of providing easy-to-understand route guidance to the user even in a place where voice guidance output from the device is difficult to hear due to various noises in the surroundings. That is.

  In order to achieve the above object, a navigation device according to the present invention includes a display means, a speaker, a microphone that collects ambient sounds and inputs them as audio signals, a current position detection means that detects a current position, Route search means for searching for a route from the current position detected by the current position detection means to a set destination, information on the route searched for by the route search means, and the current specified by the current position detection means Generating a route guidance message indicating how to proceed from the current position to the destination based on the position information and displaying the generated route guidance message as an image on the display means, or the speaker. Route guidance means for outputting as voice, and the route guidance when the magnitude of the voice signal input from the microphone exceeds a predetermined threshold Voice guidance availability determination means for determining that a message is not output from the speaker, wherein the route guidance means has a voice signal input from the microphone that exceeds a predetermined threshold. If it is determined that the generated route guidance message is output as voice information from the speaker, the voice guidance availability determination means determines that the magnitude of the voice signal input from the microphone exceeds a predetermined threshold. When the determination is made, the generated route guidance message is not output from the speaker but is displayed only on the display means.

  Thus, according to the present invention, it is possible to determine a place where the surrounding noise is large, and to output the route guidance message to the display means without outputting the route guidance message using the speaker. Therefore, when the ambient noise is low, route guidance can be performed by voice from the speaker, and when the ambient noise is high, a route guidance message can be output to the display means. The route is appropriately determined according to the current position and the surrounding noise conditions. It is possible to switch the guidance method.

  Further, according to the navigation device of the present invention, the predetermined threshold value is changed based on a set value of a volume of a route guidance message output from the speaker.

  Thereby, for example, when the volume of the route guidance message is set to be low, the route guidance message is reproduced with a small sound, and therefore the route guidance message cannot be heard due to relatively small noise. However, since the threshold value is also set low according to the set volume of the route guidance message, the route guidance message is output only to the display means due to relatively small noise, and the user can receive route guidance appropriately. become able to. On the other hand, when the volume of the route guidance message is set to be high, the route guidance message is reproduced with a loud sound, so that the route guidance message can be heard even with relatively loud noise. In this case, since the threshold value is also set high according to the set sound volume of the route guidance message, the route guidance message can be output by voice until the noise becomes considerably high.

  Further, according to the navigation apparatus of the present invention, the voice guidance availability determination unit does not output the route guidance message from the speaker when the angle of the display unit with respect to the direction of gravity is in a predetermined range. , It is determined to display only on the display means.

  Thus, according to the present invention, the angle at which the user is looking at the display means is determined, and when it is estimated that the user is looking at the display means, the route guidance message is not output from the speaker, only the display means. A route guidance message can be output. Accordingly, for example, when the user is not looking at the display unit of the navigation device even when the surrounding noise is large, it is possible to prevent the route guidance message from being output to the display unit.

  Further, according to the navigation device of the present invention, the voice guidance availability determination unit does not output the route guidance message from the speaker when the own device is set to a mute mode in which voice is not output from the speaker. , It is determined to display only on the display means.

  Thereby, when the navigation apparatus is set to the mute mode, the route guidance message can be prevented from being output from the speaker.

  As is clear from the above description, the navigation device of the present invention provides easy-to-understand route guidance to the user even in places where the voice guidance output from the device is difficult to hear due to various noises in the surroundings. It becomes possible.

It is an internal block diagram of the navigation apparatus of this embodiment. It is the figure which showed the relationship between the audio guidance volume of a speaker, and a threshold value in the navigation apparatus of this embodiment. It is a flowchart which shows the operation | movement of the route guidance in the place where voice guidance is hard to hear in the navigation apparatus of this embodiment. FIG. 4 is an explanatory diagram (FIG. 4B) when a route guidance message is output from a speaker in the navigation device of the present embodiment (FIG. 4A) and when it is output on a display screen.

  A navigation device 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is an internal block diagram of the navigation device 100 of this embodiment. FIG. 2 is a diagram showing the relationship between the voice guidance volume of the speaker and the threshold value in the navigation device of this embodiment.

  A navigation device 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is an internal block diagram of the navigation device 100 of this embodiment. The navigation device 100 includes a control unit 110, a current position detection unit 120, a map database 130, a display unit 140, an operation unit 150, a microphone 160, a speaker 170, and a storage unit 180.

  The control unit 110 includes a CPU, a ROM, and a RAM (not shown), and the CPU executes a control program stored in the ROM and the RAM, so that the navigation device 100 as a whole and each of the following means are configured. Control and control the operation. That is, the control unit 110 includes a route search unit 111, a route guide unit 112, a voice guidance availability determination unit 113, and a display control unit 114.

  The route search means 111 performs a route search from the current position to the destination designated by the user. Specifically, when the user operates the operation unit 150 to set a destination and make a route search request, the route search means 111 refers to road network data stored in the map database 130, and the Dijkstra method or the like. The route from the departure point to the destination is searched by the method of above, and the link length (link cost) and required time of the links that make up the route data are accumulated, and the total link length (travel distance) and total required time are minimized. The optimum route is stored as route data in the storage unit 180 described later.

  In addition, the route search unit 111 sets guidance points when storing the searched route data in the storage unit 180. This guide point is, for example, an intersection that makes a right or left turn on the route, a point before that predetermined distance, a starting point or an end point of a pedestrian crossing, a point before those predetermined distances, or a boarding place when using public transportation such as a railway. This is a point where a left or right turn is made in or around a station or an exit station, a stairs used, a starting point or an ending point of an escalator, a point before that predetermined distance, or the like.

  Based on the route data stored in the storage unit 180 and the information on the current position specified by the current position detection unit 120, the route guidance unit 112 tells the user how to proceed from the current position. I will guide you. More specifically, the route guidance unit 112 compares the current position with route data, and how the user should proceed from the guidance point when the current position reaches the guidance point on the route. A route guidance message including instructions such as turning left and right and straight ahead is output as voice guidance from a speaker 170 described later, or a route guidance message is displayed in a form such as a balloon on a map image around the current position displayed on the display unit 140. For example, a display instruction is output to the display control unit 114 to be described later.

  The voice guidance availability determination unit 113 determines whether or not the current position specified by the current position detection unit 120 is an appropriate place for voice guidance. Specifically, the voice guidance availability determination unit 113 determines that voice guidance is not performed when the magnitude of the voice signal input from the microphone 160 exceeds a predetermined threshold, for example, 70 dB (decibel). That is, even if a route guidance message is output from the speaker 170, it is determined that the location is not audible even if voice guidance is output because it is hardly audible due to a large noise around. The threshold value can be set in advance in the storage unit 180 by the user, and a desired value can be set. Alternatively, this threshold is set to a high value when the voice guidance volume output value output from the speaker 170 is set high, and when the voice guidance volume setting value is set low. The threshold value may also be lowered.

  For example, a voice guidance volume / threshold value correspondence table as shown in FIG. 2 is stored in the storage unit 180. In FIG. 2, the threshold is set to 65 dB when the voice guidance volume is “low”, the threshold is set to 70 dB when the voice guidance volume is “medium”, and the threshold is set to 75 dB when the voice guidance volume is “high”. As a result, the threshold value changes in accordance with the set sound volume of the route guidance message, so that route guidance can be appropriately received even when the volume is set low.

  Further, the voice guidance availability determination unit 113 determines that voice guidance is not performed when the navigation device 100 is set to the mute mode by the user.

  The voice guidance availability determination means 113 outputs to the route guidance means 112 which guidance to output a route guidance message by voice using the speaker 170 or guidance by screen display using the display unit 140, The route guidance unit 112 changes the output destination of the route guidance based on an instruction from the voice guidance availability determination unit 113.

  The display control means 114 is an area including the current position from road network data, POI (Point of Interest) data, and background data stored in a map database 130, which will be described later, based on an instruction from the route guidance means 112. Are converted into map image data of a predetermined display mode and output to a video memory (not shown) of the display unit 140. Thereby, a map of the area including the current position is displayed on the display unit 140. Further, the display control unit generates a display image indicating the current position and an image indicating the route on the map image displayed on the display unit 140 so that the display unit 140 can display the display image. Further, the display control unit 114 generates a route guidance message such as a left or right turn at a guidance point as an image such as a balloon or a pop-up when the route guidance unit 112 instructs to display a route guidance message, and displays it on a map. Let

  The current position detection unit 120 identifies the current position of the navigation device 100 at predetermined time intervals. The current position detection unit 120 includes GPS signal receiving means and autonomous navigation means (each not shown). The GPS signal receiving means receives radio waves (satellite signals) including time information from a plurality of GPS satellites orbiting over the earth, and calculates position information (GPS positioning positions) at predetermined time intervals based on the radio waves (satellite signals). The autonomous navigation means complements the current position detected by the GPS signal receiving means based on the acceleration and angular velocity output values from the acceleration sensor and angular velocity sensor built in the navigation device 100. The angular velocity sensor of the autonomous navigation means is used not only to detect the position when using the vehicle, but also to detect the “held in hand” state (paragraph [0052]) described later. Further, an electronic compass or the like is mounted on the current position detection unit 120 as a means for complementing a moving direction that becomes unstable during low-speed movement.

  The map database 130 stores and stores road network data, background data, and text data.

The road network data is composed of node data in which roads are nodes such as inflection points and branch points, and link data in which routes connecting the respective nodes are links. The node data includes a node number, node position coordinates (latitude / longitude), intersection information and intersection name, the number of connection links, connection link number data, and the presence / absence of a pedestrian crossing.

  Further, the background data is configured to include position coordinates (latitude / longitude) composed of at least three points serving as background image data such as a coastline, a lake, a river shape, and a forest, and display color data.

  The text data includes characters (names) such as place names and river names, and data of their coordinates (latitude / longitude).

  In this embodiment, the display unit 140 is a liquid crystal panel, and displays a map image and a route guidance image generated by the display control unit 114. The display unit 140 and an operation unit 150 described later constitute a touch panel or a touch screen.

  The operation unit 150 is an input device configured by a touch pad or the like, and is formed on the surface of the display unit 140. The operation unit 150 is used to make a destination input setting when the user makes a route search request.

  The microphone 160 converts the sound around the navigation device 100 into an electrical signal and outputs it to the voice guidance availability determination unit 113.

  The speaker 170 outputs a voice guidance message instructed to be output from the route guidance means as a voice. Note that the volume level for outputting the voice guidance message can be set by the user, and the setting value is stored in the storage unit 180.

  The storage unit 180 stores the conditions when route search conditions such as a departure place and a destination are set by the user. In addition, the storage unit 180 stores current position information specified by the current position detection unit 120.

  Further, the storage unit 180 stores route data from the current position searched by the route search means 111 to the destination. This route data includes the data of the links that make up the route, the total time required, the information of the nodes that should turn left and right, the information of the nodes that cross the pedestrian crossing, the information of the nodes that get on and off the transportation, the route Information on guide points set above is included.

  Further, the storage unit 180 stores preset threshold value data serving as a criterion for determining whether to perform voice guidance or display guidance. Furthermore, the user can select in advance where voice guidance should not be performed, such as in a hospital, a station, or a store, and the POI attribute set as a place where voice guidance is not performed is stored. For example, POI attributes such as a hospital building or a station of a predetermined size or larger are set. These POIs are places where it is necessary to refrain from outputting voices, and places where large noises such as the premises of large stations and roads with heavy traffic cannot be heard even if voices are output.

  Furthermore, in the storage unit 180, voice guidance message data reproduced at the guidance point of the route, for example, voice guidance data such as “Please turn right at XX m ahead, XX intersection”, and a balloon on the display unit 140 In addition, display text of route guidance messages and image data displayed in a pop-up format are stored.

  The storage unit 180 also has setting values for whether route guidance is performed in the normal mode in which sound is output using the speaker 170 in the navigation device 100 or in the mute mode in which sound output from the speaker 170 is not performed. Remembered. This set value is set by the user operating the operation unit 150.

  Next, with reference to FIG. 3 and FIG. 4, the operation of route guidance when voice guidance is inappropriate in the navigation device 100 of the present embodiment will be described. FIG. 3 is a flowchart showing the route guidance operation in a place where voice guidance is inappropriate in the navigation device 100 of the present embodiment. FIG. 4A is an explanatory diagram when a route guidance message is output from a speaker in the navigation device of the present embodiment. FIG. 4B is an explanatory diagram when a route guidance message is output on the display screen in the navigation device of the present embodiment.

  In step S301 of FIG. 3, when a user sets search conditions such as a departure point and a destination by operating the operation unit 150 and makes a route search request, these search conditions are temporarily stored in the storage unit 180. . Next, the route search unit 111 searches for a route from the departure point to the destination based on the search condition stored in the storage unit 180 with reference to the road network and the traffic network of the map database 130, and the shortest The storage unit 180 stores data of nodes and links constituting a route that is a distance and a route that requires a minimum time.

  In addition, the route search unit 111 sets guidance points on the route and stores them in the storage unit 180 when storing the route data in the storage unit 180. Guide points are, for example, intersections that should turn left and right on the route, points before a predetermined distance, starting and ending points of pedestrian crossings, points before those predetermined distances, public transportation such as railways, etc. It is set at a point where the vehicle makes a right or left turn in or around the boarding station or the getting-off station, a point before the predetermined distance, a starting point or an end point of the stairs or escalator to be used, or a point before the predetermined distance.

  In step S302, the route guidance unit 112 starts route guidance. The route guidance unit 112 acquires map data around the current position specified by the current position detection unit 120 from the map database 130, and displays an image indicating the current position and an image indicating the route on the display unit 140 in a superimposed manner. The display control unit 114 is instructed to do so. Based on this instruction, the display control means 114 acquires map data of a predetermined area including the current position from the map database 130, that is, road data, background data, text data, and the like, and shows an image and a route indicating the current position. The images are superimposed and displayed on the display unit 140.

  In step S <b> 303, the route guidance unit 112 determines whether or not the current position specified by the current position detection unit 120 is a guidance point set for the route stored in the storage unit 180. If it is determined that the current position is not a guidance point, the process returns to step S302, and the route guidance process by the route guidance unit 112 is continued. If it is determined that the current position is a guidance point, the process proceeds to step S304.

  In step S304, the voice guidance availability determination unit 113 refers to the storage unit 180 to determine whether or not the navigation device 100 is currently set in the mute mode. If it is determined that the navigation device 100 is set to the mute mode, the process proceeds to step S308. If it is determined that the navigation mode 100 is set to the normal mode, the process proceeds to step S305.

  In step S <b> 305, the voice guidance availability determination unit 113 determines whether noise around the navigation device 100 is high. Specifically, the determination is made based on whether or not the value of the audio signal input from the microphone 160 exceeds a threshold stored in the storage unit 180, for example, 70 dB. If the value of the voice signal exceeds the threshold, the voice guidance availability determination unit 113 determines that the surrounding noise is high and proceeds to the process of step S306. If the value of the voice signal is equal to or less than the threshold, Is determined to be a place where the surrounding noise is low, and the process proceeds to step S307.

  Note that the threshold value may be changed according to the set volume of the speaker 170 as shown in FIG. That is, if the set volume of the storage unit 170 is set to a small value, the route guidance by voice cannot be heard even with relatively small noise, so the threshold value is also set to a small value. On the other hand, when the set volume is set to a large value, even a relatively loud noise can be heard, so that the threshold value is also set to a large value. By doing so, it becomes possible to change the threshold value of the route guidance method according to the volume set by the user, and the route guidance by display is made only when the route guidance by voice is not really heard. .

  In step S306, based on output values of various sensors such as an acceleration sensor of the current position detection unit 120, it is determined whether or not the display unit 140 of the navigation device 100 is within a predetermined angle range with respect to the direction of gravity. Accordingly, it can be estimated whether or not the user is viewing the display unit 140 with the navigation device 100 in hand. When it is determined that the navigation device 100 is in the direction within the predetermined range, that is, when it is estimated that the user is holding the navigation device 100 in his / her hand and looking at the display unit 140, the process proceeds to step S308. When it is determined that the navigation device 100 is not in a predetermined range, that is, when it is estimated that the user does not look at the operation unit 140 with the navigation device 100 in hand, the process proceeds to step S307. .

  In step S <b> 307, the voice guidance availability determination unit 113 outputs an instruction to output a route guidance message by voice at the current position to the route guidance unit 112. Based on this instruction, the route guidance unit 112 extracts an appropriate voice route guidance message from the storage unit 180 and outputs it to the speaker 170 to perform voice guidance. The state at this time is shown in FIG. 4A, and a route guidance message is output by voice from the speaker 170 of the navigation device 100. Thereafter, the process proceeds to step S309. In addition, although the case where a map image is displayed on the display unit 140 has been described in the above description and FIG. 4A, the present embodiment is not limited to this, and when outputting a route guidance message by voice, You may make it not display a map image etc. on the display part 140. FIG.

  In step S308, the voice guidance availability determination unit 113 outputs an instruction to display a route guidance message on the display unit 140 to the route guidance unit 112 without performing voice guidance at the current position. Based on this instruction, the route guidance unit 112 extracts from the appropriate route guidance message storage unit 180 and outputs it to the display control unit 114. The display control unit 114 outputs a route guidance message such as a right / left turn instruction or the like by a balloon or a pop-up. And is displayed on the display unit 140 while being superimposed on the map image. The state of the display screen of the display unit 140 at this time is shown in FIG. On the display screen, an image showing the current position on the map image, a route, and a route guidance message displayed in the form of a balloon are superimposed and displayed. Thereafter, the process proceeds to step S309.

  In step S309, the route guidance unit 112 determines whether the route guidance has ended. This is performed by the route guidance unit 112 determining whether or not the current position acquired by the current position detection unit 120 has reached the destination. If the current position has reached the destination, the route guidance means 112 outputs the fact that the destination has been reached to the display unit 140 or the speaker 170, and the processing of this embodiment is terminated. If the current position has not reached the destination, the process returns to step S302 to continue route guidance.

  As described above, in the above-described embodiment, it is determined that voice guidance is not performed in a place where the noise is large enough to exceed the threshold value, and the route guidance that displays the route guidance message on the display unit 140 is switched. Therefore, the route guidance can be appropriately provided to the user in a place where the voice guidance is difficult to hear.

  In the above-described embodiment, a case has been described in which when the magnitude of the audio signal input from the microphone 160 exceeds a predetermined threshold, the route guidance is switched to only the display guidance. However, if the voice signal input from the microphone 160 once exceeds a predetermined threshold, route guidance based only on display guidance is performed for a predetermined time regardless of whether the voice signal input thereafter falls below the threshold. It may be continued.

  Furthermore, if the voice signal input from the microphone 160 once exceeds a predetermined threshold, the voice guidance is not performed and the route guidance only by the display guidance is continued until the second threshold lower than the threshold is exceeded. It may be. By doing so, it is possible to prevent frequent switching of the guidance method, and it is possible to avoid a situation in which the user is confused without knowing which method is used for route guidance.

  In the above embodiment, when the surrounding noise of the navigation device 100 is so great that the voice route guidance message cannot be heard, the output of the route guidance message to the speaker 170 is stopped and the route guidance message is blown to the display unit 140. Explained how to display in a pop-up format. However, the present invention is not limited to the above. For example, the voice guidance availability determination unit 113 may determine whether the current position specified by the current position detector 120 is inappropriate for voice guidance such as in a hospital. It is also possible to determine that voice guidance is not performed when the surrounding noise is high, such as in a station.

  In this case, POI data such as stations, bus stops, airports, commercial buildings, hospitals, and private houses are stored in the map database 130, and the types of places where the user does not provide voice guidance are set in the storage unit 180 in advance. To. Then, whether the voice guidance availability determination unit 113 refers to the map database 130 and the POI attribute information corresponding to the current position in the map database 130 applies to the type of POI stored in the storage unit 180 that does not perform voice guidance. Judge whether or not. For example, if the user has set in the storage unit 180 that “station” and “hospital” in the POI are locations where voice guidance is not performed, and the current position is a station or a hospital, the voice guidance availability determination is performed. The means 113 determines not to perform voice guidance at the current position. In this way, it is possible to switch from guidance by voice to guidance by outputting a route guidance message on the display screen at a place where it is inappropriate to output voice around or a place preset by the user.

DESCRIPTION OF SYMBOLS 100 Navigation apparatus 110 Control part 111 Route search means 112 Route guidance means 113 Voice guidance availability determination means 114 Display control means 120 Current position detection part 130 Map database 140 Display part 150 Operation part 160 Microphone 170 Speaker 180 Storage part

Claims (4)

Display means;
Speakers,
A microphone that picks up surrounding audio and inputs it as an audio signal;
Current position detecting means for detecting the current position;
Route search means for searching for a route from the current position detected by the current position detection means to a set destination;
Generates a route guidance message indicating how to proceed from the current position to the destination based on the information on the route searched by the route search means and the information on the current position specified by the current position detection means A route guidance unit that displays the generated route guidance message as an image on the display unit, or causes the speaker to output the voice as a voice;
Voice guidance availability determination means for determining that the route guidance message is not output from the speaker when the magnitude of the voice signal input from the microphone exceeds a predetermined threshold;
The route guidance means, when the voice guidance availability judgment means judges that the magnitude of the voice signal input from the microphone does not exceed a predetermined threshold, the generated route guidance message is voiced from the speaker. When the voice guidance availability determination means determines that the magnitude of the voice signal input from the microphone exceeds a predetermined threshold, the generated route guidance message is not output from the speaker. A navigation device for displaying only on the display means.   The navigation device according to claim 1, wherein the predetermined threshold changes based on a set value of a volume of a route guidance message output from the speaker.   The voice guidance availability determination unit determines that the route guidance message is not output from the speaker and is displayed only on the display unit when the angle of the display unit with respect to the direction of gravity is in a predetermined range. The navigation device according to claim 1 or 2.   The voice guidance availability determination unit determines that the route guidance message is not output from the speaker and is displayed only on the display unit when the apparatus is set in a mute mode in which the voice is not output from the speaker. The navigation device according to any one of claims 1 to 3.

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