Abstract:
A navigation system comprising a receiver module that receives a stream for a broadcast content and a control unit in communication with the receiver module. The control unit determines whether the stream for the broadcast content contains information that matches to a keyword from a stored list of keywords, identifies a landmark that is associated with the keyword, determines whether a position information for the landmark resides with a map area to be displayed by the navigation system according to a detected position for the navigation system, and prompts a map area display of the map area having a landmark display for the landmark that is superimposed within the map area display.

Description:
RELATED APPLICATION 
       [0001]    This application is a divisional application of U.S. application Ser. No. 11/244,076, filed on Oct. 6, 2005, which is a divisional application of U.S. application Ser. No. 10/376,590, filed on Mar. 3, 2003, and which claims priority to Japanese application JP2002-068124, filed on Mar. 13, 2002. The entire contents of these applications are incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a navigation system, or, more particularly, to a navigation system capable of presenting point information associated with data of broadcast contents and a map data display method. 
         [0004]    2. Description of the Related Art 
         [0005]    Navigation systems can detect the position of an own vehicle and the traveling speed thereof in real time by utilizing the global positioning system (GPS). A map is displayed on a display unit according to digitized map data. A current position measured by the GPS, a recommended route to a destination along which a user is guided to the destination, or the like is displayed while being superimposed on the display map. 
         [0006]    The navigation system can present marks, which represent various landmarks, such as fast-food restaurants, convenience stores, family restaurants, and event halls, while superimposing them on a map displayed on a display unit on the basis of point information (hereinafter the marks displayed on the display unit shall be called landmarks). As for the display of the landmarks, what category should be displayed or not displayed can be designated by selecting a menu item from any of hierarchically structured menus displayed on the display device. 
         [0007]    As mentioned above, landmarks can be superimposed on a map presented by a navigation system. In a conventional navigation system, landmarks existent in a portion of a map displayed on the display unit are merely displayed based on point information. 
         [0008]    Incidentally, on-vehicle equipment includes a broadcast receiver having the ability to receive programs broadcast from television or radio broadcasting stations. A commercial message (CM) is inserted between broadcast programs. Assume that a CM is broadcast while a user who may be a driver or a passenger in a compartment is watching or listening to a program presented by the broadcast receiver. 
         [0009]    For example, the CM is a CM concerning a fast-food restaurant. The user may want to stop at the fast-food restaurant. In this case, the user uses the navigation system to search the nearest fast-foot restaurant on the basis of a displayed region (current point). The user then designates the fast-food restaurant displayed as the result of the search and searches for a route to the fast-food restaurant by himself or herself. 
         [0010]    As mentioned above, when a specific landmark is designated from among displayed landmarks or a new landmark is searched, an action must be performed on the navigation system. Consequently, the navigation system must be operated. It is a nuisance to operate the navigation system for a search every time a user gets interested in a program or a CM that is broadcast from time to time. Besides, it is dangerous to operate the navigation system during driving. 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, an object of the present invention is to provide a navigation system which enables a user to visually grasp the position of a store or the like in association with the contents of a CM or a program received by a broadcast receiver. 
         [0012]    Another object of the present invention is to provide a means for adding a value to information of stores or the like registered as one of the landmarks. 
         [0013]    Through a discussion on the foregoing underlying problems, a present inventor concentrated his attention on a stream that is employed in digital television broadcast whose service will start in the near future. According to the present invention, a specific keyword contained in any of the streams representing a CM or a program triggers off the presentation of the position of a broadcast store or the like by a navigation system. 
         [0014]    In order to accomplish the above objects, one aspect of the present invention resides in a navigation system having the components described below. That is to say, the navigation system consists mainly of: a stream receiving means for receiving broadcast streams; a data decoding means for sampling a data signal from the received streams and decoding the data signal into character string information; a keyword recording means in which predetermined keywords associated with position information specified in map information data are stored; a matching means for performing matching to compare character string information with each of the keywords stored in the keyword recording means and searching a keyword consistent with a keyword contained in the character string information; a position information searching means for searching position information associated with the keyword contained in the character string information and detected to be consistent with a recorded keyword by the matching means; and a display means for displaying the detected position information while superimposing it on a display image. When it says that position information is displayed while being superimposed on a display image, this means that the position information may be not only superimposed on the display image but also allowed to flicker or colored so that it can be distinguished from the other position information. 
         [0015]    When position information associated with a keyword is contained in a portion of a map image displayed on the display means, a mark indicating the position information is displayed on the map image. 
         [0016]    The navigation system further includes a display control means for changing the scale for a portion of a map image displayed on the display means when position information associated with a keyword is not contained in the portion of the map image. 
         [0017]    In another aspect, the navigation system includes a navigation means for searching the route to the position indicated with a mark displayed on the display means or for guiding a user to the position. 
         [0018]    In the navigation system having the foregoing components, if a received stream contains a keyword, position information associated with the keyword, that is, a mark, is displayed on the display screen. A received stream is searched for a keyword in real time (stream reception). If the keyword is contained in the stream, the keyword triggers off the display of associated position information. Namely, the navigation system presents position information in association with a received stream. 
         [0019]    In still another aspect, the present invention resides in a navigation system having the components described below. That is to say, the navigation system consists mainly of: an information processing unit for sampling position information associated with contents acquired externally; and a display unit that displays the sampled position information in association with the received contents while superimposing it on a map image. A means for acquiring contents externally may be a contents receiving unit included in the navigation system. Otherwise, other equipment may receive contents, and the navigation system may receive the contents. 
         [0020]    A memory in which position information is temporarily stored may be included. When position information cannot be displayed in association with contents, the position information is stored in the memory. Position information read from the memory is superimposed on a map image displayed on the display unit. When position information is thus stored in the memory, even after contents are watched or listened to, position information can be displayed. 
         [0021]    In yet another aspect, the present invention resides in a point information display method adaptable to a navigation system. That is to say, the point information display method consists mainly of: a step of receiving broadcast contents and decoding information concerning the contents; a step of judging whether a keyword association with point information concerning a position on a map is contained in the decoded information; and a step of searching map information data for point information associated with the keyword contained in the decoded information, and displaying the point information while superimposing it on the map. 
         [0022]    In another aspect, the present invention resides in a program for controlling an information processor that displays map information and point information. That is to say, the program allows the information processor to perform: a process for receiving a broadcast radio wave, separating a predetermined signal from the other components of the radio wave, and decoding the predetermined signal; a process for searching the decoded information for character string information consistent with a keyword stored in the information processor; and a process for displaying point information according to point information and position information associated with the keyword while superimposing the point information on a map image. 
         [0023]    Other and further objects, features and advantages of the invention will appear more fully from the following description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a block diagram showing the configuration of a navigation system in accordance with an embodiment of the present invention; 
           [0025]      FIG. 2A  and  FIG. 2B  show packets employed in a digital television broadcast and transmitted during a digital television broadcast; 
           [0026]      FIG. 3  shows a table recorded in a keyword dictionary employed in the embodiment; 
           [0027]      FIG. 4A  and  FIG. 4B  show an example of a display on a display unit included in the navigation system in accordance with the embodiment; 
           [0028]      FIG. 5  is a flowchart describing a flow of processing steps according to which the navigation system of the embodiment presents a landmark in association with a CM or a program; and 
           [0029]      FIG. 6  is a flowchart describing a flow of processing steps according to which the display and non-display of a landmark is switched in association with a CM or a program. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    Referring to the appended drawings that show an embodiment of the present invention, the present invention will be described below. 
         [0031]    The number of users of digital television broadcast dependent on a satellite broadcasting service is increasing. Moreover, provision of a digital television broadcast service based on ground waves is going to start. A packet employed in a digital television broadcast and transmitted from a broadcasting station has a data field. The packet employed in digital television broadcast will be described later. According to the present embodiment, a navigation system uses information recorded in the data field to present a landmark in association with the contents of a broadcast CM or program (with a keyword contained in the CM or program as a trigger). 
         [0032]      FIG. 1  is a block diagram showing the configuration of the navigation system in accordance with the present embodiment. 
         [0033]    As illustrated, the navigation system consists mainly of: a display unit  41 , such as a liquid crystal display or any other monitor, on which a map and various kinds of information are displayed responsively to a manipulation performed on an operating unit, such as a remote controller or a control panel; a loudspeaker  42  for generating a voice or the like so as to give a guidance; a control unit  10  for controlling the whole navigation system; and a position measuring unit  20  for measuring the position of a vehicle. As mentioned above, the navigation system in accordance with the present embodiment includes a broadcast receiver unit  30  that receives a digital television signal. Hereinafter, a case where the broadcast receiver unit  30  is integrated with the navigation system will be described. As long as data can be transmitted to the control unit  10 , the navigation system and the broadcast receiver unit  30  may be independent of each other. 
         [0034]    The control unit  10  consists mainly of: a navigation block  11  having a ROM in which a program describing a control sequence for controlling the whole navigation system is stored and a CPU that performs arithmetic operations according to the program stored in the ROM; a RAM (memory)  12  serving as an internal memory for assisting in performing actions described in the program, and holding data of a map and others; a display controller  13  for controlling data to be displayed on the display unit  41 ; an audio controller  14  for controlling audio data that are generated by the loudspeaker  42  in order to give a guidance or the like; a disk drive  15  capable of reading map information from a recording disk, such as a CD-ROM or DVD-ROM, in which map information data concerning a predetermined wide area are stored; and a storage controller  16  for controlling the disk drive  15 . 
         [0035]    Moreover, the control unit  10  included in the navigation system in accordance with the present embodiment includes: a matching block  18  composed of a ROM in which a matching program that will be described later is stored and a CPU that performs arithmetic operations according to the program; and a keyword dictionary  17  in which keywords used for matching are recorded. 
         [0036]    The position measuring unit  20  includes: a GPS antenna  21  through which a signal originated from any of GPS satellites is received; a GPS position measuring block  22  that measures a position according to a signal received through the GPS antenna  21 ; a vehicle speed sensor  23  for detecting the vehicle speed of a vehicle in which the navigation system is mounted; a gyro sensor  24  for detecting a rotational displacement made by the vehicle; and a measured position correcting block  25  for correcting the result of position measurement performed by the GPS position measuring unit  22  according to a value produced by the gyro sensor  24 . In the navigation system, displaying the position of a vehicle and giving a guidance are performed based on a value provided by the measured position correcting block  25 . 
         [0037]    The navigation system in accordance with the present embodiment includes the broadcast receiver unit  30  capable of receiving a digital television signal. The broadcast receiver unit  30  includes: a digital broadcast receiver  31  for receiving a radio wave (packet) from a broadcasting station; a demultiplexer  32  for separating a video signal, an audio signal, and a data signal, which constitute a multiplexed signal, from one another and providing the separated signals; a data decoder  33  for decoding the data signal and transmitting the resultant signal to the control unit  10 ; a video decoder  34  for decoding the video signal and displaying an image on the display unit  41  according to the resultant signal; and an audio decoder  35  for decoding the audio signal and generating sounds from the loudspeaker  42  according to the resultant signal. The demultiplexer  32  separates the video signal, the audio signal, and the data signal from one another while referencing time stamps indicating time instants at which the signals are encoded. The time bases for the video signal and the audio signal, respectively, are synchronized with each other, so that output units can reproduce an image and sounds according to the video and audio signals at proper timings. The time base for the data signal accompanying the video and audio signals is also synchronized with the time bases for the video and audio signals during matching. The timing of processing data can be matched with the timing of reproducing the image and sounds. 
         [0038]      FIG. 2A  and  FIG. 2B  show packets employed in digital television broadcast and transmitted during digital television broadcast. 
         [0039]    As shown in  FIG. 2A , transport streams (TS) include a video transport stream (TS) that represents a video signal, an audio transport stream (TS) that represents an audio signal, and a data transport stream (TS) that represents a data signal. Video TSs, audio TSs, or data TSs are gathered up to produce an independent TS packet. The independent TS packets of video TSs, audio TSs, and data TSs, respectively, are multiplexed with the time bases therefor matched with one another, whereby a multiplexed TS packet composed of the video TSs, the audio TSs and the data TSs is produced. 
         [0040]    In a data TS field of the multiplexed TS packet, information concerning the contents of a video TS and an audio TS is described in the form of, for example, an ASCII character string. The data TS contains not only information of, for example, a fast-food restaurant or a convenience store but also information of a store name (or a company name or a group name), such as “OOO Burger” or “ΔΔΔ Store.” Moreover, the data TS may contain information that is displayed as a superimposed caption or a product name. From information contained in the data TS, it can be judged to what a currently broadcast CM or program is related. If the data TS contains specific character string information (keyword), the character string information may trigger off the display of a landmark in association with a CM or program. 
         [0041]      FIG. 2B  shows the structure of a multiplexed TS packet composed of independent TS packets shown in  FIG. 2A . As shown in  FIG. 2B , a plurality of video TSs constitutes an elementary stream (ES) that is a series of streams having an unrestricted length. A packed elementary stream (PES) packet header is appended to the start of the ES, whereby a PES packet is produced. Likewise, a PES packet is produced from audio TSs or data TSs. The PES packet composed of independent TSs such as video TSs, audio TSs, or data TSs is transmitted while being split into an adaptation field having a leading packet header and a payload. Thus, one TS packet is produced. A packet identifier (PID) or the like is defined in the packet header. Based on the PID, a kind of TS packet can be identified. Recorded in the adaptation field is information of program-clock-reference (PCR) that is referenced in order to match time bases with one another during decoding. Based on the PCR information, the timing of reproducing each TS packet can be controlled. A plurality of TS packets is gathered up to produce a multiplexed TS that looks like one stream having a plurality of programs incorporated therein. The thus-produced multiplexed TS is utilized for a digital television broadcast. As mentioned above, the multiplexed TSs employed in a digital television broadcast are transmitted as a multiplexed TS packet composed of video streams, audio streams, and data streams. 
         [0042]      FIG. 3  shows a table recorded in the keyword dictionary  17  included in the present embodiment. As illustrated, recorded in a keyword field in a keyword table  50  are not only a category of business but also a concrete store name. For example, “OOO Burger” and “*** Kitchen” that are names of fast-food restaurants, “Family Restaurant ♦♦♦” and “□□□&#39;S” that are names of family restaurants, and “ΔΔΔ Store” and “xxx Mart” that are names of convenience stores are recorded. 
         [0043]    According to the present invention, matching is performed in order to compare character string information, which is contained in a data TS representing a CM or program received by the digital broadcast receiver  31 , with each of the keywords recorded in the keyword table  50  contained in the keyword dictionary  17 . 
         [0044]    For example, assume that a CM concerning “OOO Burger” is broadcast. The digital broadcast receiver  31  receives the CM, and the demultiplexer  32  separates different kinds of signal components from one another so as thus to decode the received signal. A data TS (character string information) decoded by the data decoder  33  is transferred to the RAM  12  included in the control unit  10  and held in the RAM  12 . Assume that the data TS contains a character string “OOO Burger.” The matching block  18  judges whether the character string information in the data TS held in the RAM  12  contains a keyword consistent with any of the keywords recorded in the keyword table  50 . 
         [0045]    Through matching, it is judged that the data TS representing the CM contains a character string “OOO Burger” consistent with a recorded keyword. Position information and a landmark concerning “OOO Burger” are contained in map information. The navigation block  11  searches the map information for the data of the landmark (for the position information) so as to judge whether the information of “OOO Burger” is contained in a portion of the map information that can be displayed on the display unit  41 . The landmark for “OOO Burger” that can be displayed on the display unit is displayed while being superimposed on a map displayed on the display unit  41 . 
         [0046]    As mentioned above, when a keyword is specified in character string information contained in a data TS, map information is searched for a landmark associated with the keyword. The landmark is then displayed on the display unit  41 . Through matching, a keyword contained in a stream representing a CM triggers off the real-time display of a landmark associated with the contents of the CM or program. 
         [0047]    As mentioned above, the keyword table  50  that is prepared in advance is used to perform matching. Otherwise, the contents of a received data TS may be analyzed to detect a keyword. The keyword may then be added to the keyword table  50  so that the navigation system will learn the keyword. 
         [0048]      FIG. 4A  and  FIG. 4B  show an example of a display on the display unit  41  included in the navigation system of the present embodiment. 
         [0049]    As shown in  FIG. 4A , normally, a recommended route  64  from an own-vehicle position  62  to a destination  63  is displayed in a display area  61  (in which a map image is displayed) on the display unit  41  included in the navigation system. 
         [0050]    When a digital television signal specifying character string information consistent with a character string recorded in the keyword table  50  is received during driving, the foregoing matching is carried out. Thereafter, as shown in  FIG. 4B , a landmark  65   a  contained in a portion of map information that can be displayed in the display area  61  flickers. The landmark  65   a  is kept displayed until a keyword contained in character string information makes a hit next. 
         [0051]    A landmark  65   b  and a landmark  65   c  located near the own-vehicle position  62  are associated with a keyword that has made a hit. However, since the landmarks are contained in a portion of map information that falls outside the display area  61 , they are not displayed. Herein, the landmarks associated with the keyword that has made a hit and contained in the portion of the map information that falls outside the display area  61  are not displayed. Alternatively, a landmark located at a predetermined distance or less from the own-vehicle position  62  may be displayed by changing the scale for the portion of the map information that is displayed in the display area  61 . 
         [0052]    If no landmark can be displayed in association with a CM or program in the display area, nothing may be displayed. Otherwise, the display controller  13  may change the scale for the portion of the map information that is displayed in the display area  61 , so that a landmark can be displayed. 
         [0053]    The navigation block  11  selects a landmark located in the direction of advancement, in which the vehicle advances from the own-vehicle position  62 , on the basis of information acquired by the position measuring unit  20 . The position information concerning the selected nearest landmark is used to search a route. Thus, a user can be guided to the point of the nearest landmark without the necessity of changing the direction of advancement from the own-vehicle position  62 . As mentioned above, a keyword contained in character string information triggers off the display of a landmark. Moreover, a user can perform manipulations so as to change his/her destination from the initial destination  63  to the point of the landmark  65   a  and can be informed of the route to the landmark  65   a.    
         [0054]      FIG. 5  is a flowchart describing a flow of processing steps according to which the navigation system of the present embodiment presents a landmark in association with a CM or program. 
         [0055]    The digital broadcast receiver  31  included in the broadcast receiver unit  30  receives a multiplexed TS packet broadcast as a digital television signal (step  501 ). The demultiplexer  32  separates TSs, which constitute the multiplexed TS packet, from one another (step  502 ). Among the separated TSs, a data TS is decoded by the data decoder (step  503 ). The data TS is then transferred to the control unit  10 . 
         [0056]    When the control unit  10  receives the data TS, the matching block  18  performs matching (step  504 ). During the matching, it is judged whether the data TS contains a keyword that is consistent with any of the keywords recorded in the (keyword table  50  in the) keyword dictionary  17  (step  505 ). 
         [0057]    If it is judged at step  505  that the data TS does not contain the keyword, steps  501  to  505  are repeatedly performed on subsequent multiplexed TS packets. If it is judged at step  505  that the data TS contains the keyword, a portion of a map to be displayed in the display area on the display unit  41  is searched for a landmark associated with the keyword (step  506 ). It is then judged whether the landmark associated with the keyword is found (step  507 ). 
         [0058]    If it is judged at step  507  that the landmark is not found, steps  501  to  507  are repeatedly performed on subsequently received data TSs. If it is judged at step  505  that the landmark is found, the display controller  13  displays the landmark at a predetermined position while superimposing it on the map displayed on the display unit  41  (step  508 ). A landmark to be displayed in association with a CM or program may be displayed to flicker or displayed in a color different from the color in which the other landmarks are displayed. In any case, the landmark is displayed to be distinguishable from the other landmarks. 
         [0059]      FIG. 5  describes an example of displaying a landmark all the time according to a received data TS.  FIG. 6  describes a flow of processing steps for switching the display and non-display of a landmark associated with a CM or program. 
         [0060]    Steps  601  to  603  are identical to steps  501  to  503  described in  FIG. 5 . The description of the steps will therefore be omitted. 
         [0061]    When the control unit  10  receives a data TS, the data TS is stored and held in the RAM  12  (step  604 ). It is then judged whether the interlock of the display of a landmark with a digital, television broadcast is designated (step  605 ). If it is judged at step  605  that the interlock with the digital television broadcast is undesignated, steps  601  to  605  are repeatedly performed on subsequently received TS packets. Meanwhile, the received data TSs are sequentially stored in the RAM  12 . If it is judged at step  605  that the interlock with a digital television broadcast is designated, the data TS is read from the RAM  12  (step  606 ). Matching is performed on the data TS. 
         [0062]    Steps  607  to  611  succeeding the matching are identical to steps  504  to  508  described in  FIG. 5 . The description of the steps will therefore be omitted. 
         [0063]    The ability to perform matching on a data TS received by the digital broadcast receiver  31  has been described. The object of matching is not limited to the data TS broadcast as a component of a digital television signal. For example, if an audio TS can be sampled, the sampled audio TS may be compared with the keyword dictionary  17  during matching. Consequently, a landmark associated with a keyword contained in the audio TS can be displayed. 
         [0064]    As mentioned above, the navigation system of the present embodiment includes the keyword dictionary  17  in which keywords associated with landmarks are recorded and the matching block  18  that performs matching so as to compare a received data TS with keywords. Since the navigation system includes these facilities, even if a data TS transmitted from a broadcasting station does not conform to a special format, a landmark can be searched through matching. Consequently, a landmark associated with a keyword that has made a hit can be displayed. 
         [0065]    A user of the navigation system can discern information of a store or the like broadcast during a CM or program without the necessity of performing special manipulations. Moreover, a landmark presented by the navigation system is the nearest landmark located in the direction of advancement. The user is therefore encouraged to stop at the indicated point. 
         [0066]    A sponsor of a CM to be broadcast as a digital television signal does not merely broadcast the CM but appends a keyword to a data TS so that the keyword will trigger off the display of a landmark. Thus, the sponsor can appeal to users at a good timing. That is to say, when the broadcast of a CM is interlocked with the display of a landmark, the landmark presented by the navigation system has the value of an advertisement of a store or the like. 
         [0067]    Moreover, the navigation system of the present embodiment utilizes a data TS received by the digital broadcast receiver  31 . Therefore, software capable of performing matching and displaying a landmark should merely be provided. Consequently, an increase in the cost of manufacture stemming from an addition of facilities can be suppressed. 
         [0068]    Furthermore, since a landmark in map information recorded in a DVD-ROM or the like has the value of an advertisement, if advertisers who want to register their store names or the like in the keyword dictionary  17  at a charge are recruited, map information can be provided for users at a low cost. 
         [0069]    As described so far, according to the present invention, there is provided a navigation system enabling a user to visually grasp the position of a store or the like in association with the contents of a CM or program received by a broadcast receiver. 
         [0070]    Moreover, according to the present invention, information of a store or the like registered as a landmark is an added value. Consequently, the usefulness of CMs can be improved and users&#39; convenience can be ensured. 
         [0071]    The foregoing invention has been described in terms of preferred embodiments. However, those skilled in the art will recognize that many variations of such embodiments exist. Such variations are intended to be within the scope of the present invention and the appended claims.