Abstract:
Disclosed is a navigation device capable of guiding HOV lanes more intelligibly. The device comprises a storage unit that stores installation information relating to traffic lanes that become passable when predetermined conditions are satisfied (hereinafter referred to as “conditional traffic lanes”) and a guiding unit that guides entrances to the conditional traffic lanes. The guiding unit displays entrance guide images for guiding the car in which the device is installed to the entrances to the conditional traffic lanes instead of images that have been displayed until then when the position of the car approaches the entrances to the conditional traffic lanes.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a navigation device and a guiding method employed in the navigation device. The present invention claims priority from Japanese Patent Application No. 2009-298079 filed on Dec. 28, 2009 and Japanese Patent Application No. 2009-298080 filed on Dec. 28, 2009, the contents of which are incorporated by reference herein in those designated states that allow incorporation by reference of literature. 
       BACKGROUND ART 
       [0002]    Conventionally, in a navigation device, there has been used a technology of searching for routes corresponding to traffic lanes in which only vehicles satisfying specific conditions are qualified for traveling, such as high-occupancy vehicles (HOV) lanes. Patent Literature 1 describes a technology for such navigation device. Note that, the HOV lanes are also called “car pool lanes”. 
       CITATION LIST 
     Patent Literature 
       [0003]    [PTL 1] JP 2000-131085 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    However, in the conventional navigation device, guidance as to the HOV lanes is not necessarily provided at a satisfactory level. 
         [0005]    In view of the above, the present invention has an object of providing guidance as to HOV lanes more intelligibly in a navigation device. 
       Solution To Problem 
       [0006]    In order to solve the above-mentioned problem, according to an aspect of the present invention (hereinafter, referred to as “first aspect of the present invention”), there is provided a navigation device which aims at providing guidance as to an HOV lane by visually displaying the HOV lane in a visually apparent manner, comprising: storage unit adapted to store lane assignment information of a traffic lane (hereinafter, referred to as “conditional lane”) that is available for passage of vehicles when a predetermined condition is satisfied; and guiding unit adapted to provide guidance as to an entrance of the conditional lane. When an own vehicle position is appeared to come closer to the entrance of the conditional lane, the guiding unit displays an entrance guidance image for guiding the vehicle to the entrance of the conditional lane instead of a previously displayed image. Further, according to another aspect of the present invention (hereinafter, referred to as “second aspect of the present invention”) there is provided a navigation device which determines at higher accuracy whether or not a certain lane is an HOV lane, comprising: storage unit adapted to store lane information containing a lane assignment time period of a traffic lane (hereinafter, referred to as “conditional lane”) that is available for passage of vehicles when a predetermined condition is satisfied; and guiding unit adapted to provide guidance as to an entrance of the conditional lane. The guiding unit uses the lane information to identify a road which is designated as the conditional lane at a predetermined time, and provides the guidance as to the entrance of the identified road designated as the conditional lane. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]    [ FIG. 1 ] A schematic configuration diagram of a navigation device according to a first aspect of the present invention. 
           [0008]    [ FIG. 2 ] A diagram illustrating a configuration of a link table according to the first aspect of the present invention. 
           [0009]    [ FIG. 3 ] A diagram illustrating a configuration of a guide target link table according to the first aspect of the present invention. 
           [0010]    [ FIG. 4 ] A view illustrating a mounting position of a camera according to the first aspect of the present invention. 
           [0011]    [ FIG. 5 ] A diagram illustrating how a picked-up image is projected on a ground surface according to the first aspect of the present invention. 
           [0012]    [ FIG. 6 ] A functional block diagram of a processing unit according to a first embodiment of the first aspect of the present invention. 
           [0013]    [ FIG. 7 ] A flow chart of target link extraction processing according to the first aspect of the present invention. 
           [0014]    [ FIG. 8 ] A flow chart of HOV entrance guiding processing according to the first aspect of the present invention. 
           [0015]    [ FIG. 9 ] Example screens showing HOV lane entrance guidance views according to the first aspect of the present invention. 
           [0016]    [ FIG. 10 ] A flow chart of target link extraction processing according to a second embodiment of the first aspect of the present invention. 
           [0017]    [ FIG. 11 ] A diagram illustrating links connected along the road to a link on which an own vehicle is located according to the first aspect of the present invention. 
           [0018]    [ FIG. 12 ] A schematic configuration diagram of a navigation device according to a second aspect of the present invention. 
           [0019]    [ FIG. 13 ] A diagram illustrating a configuration of a link table according to the second aspect of the present invention. 
           [0020]    [ FIG. 14 ] A diagram illustrating a configuration of a guide target link table according to the second aspect of the present invention. 
           [0021]    [ FIG. 15 ] A view illustrating a mounting position of a camera according to the second aspect of the present invention. 
           [0022]    [ FIG. 16 ] A diagram illustrating how a picked-up image is projected on a ground surface according to the second aspect of the present invention. 
           [0023]    [ FIG. 17 ] A functional block diagram of a processing unit according to a first embodiment of the second aspect of the present invention. 
           [0024]    [ FIG. 18 ] A flow chart of target link extraction processing according to the second aspect of the present invention. 
           [0025]    [ FIG. 19 ] A flow chart of HOV entrance guiding processing according to the second aspect of the present invention. 
           [0026]    [ FIG. 20 ] A flow chart of target link extraction processing according to a second embodiment of the second aspect of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0027]    Hereinafter, embodiments of a first aspect and a second aspect of the present invention are described. Now, a navigation device to which a first embodiment of the first aspect of the present invention is applied is described with reference to the drawings. 
         [0028]      FIG. 1  is an overall configuration diagram of a navigation device  100 . The navigation device  100  is a so-called navigation device capable of displaying map information, and of showing a point indicating a present location of the navigation device  100  and information for guiding a route to a set destination. 
         [0029]    The navigation device  100  includes a processing unit  1 , a display  2 , a storage unit  3 , a voice input/output unit  4  (including a microphone  41  as a voice input unit and a speaker  42  as a voice output unit), an input unit  5 , a ROM device  6 , a vehicle speed sensor  7 , a gyro sensor  8 , a global positioning system (GPS) receiver  9 , an FM multiplex broadcasting receiver  10 , a beacon receiver  11 , a camera  12 , and an in-vehicle network communication unit  13 . 
         [0030]    The processing unit  1  is a central unit which performs various kinds of processing. For example, the processing unit  1  calculates the present location based on information output by, for example, the various sensors  7  and  8 , the GPS receiver  9 , the FM multiplex broadcasting receiver  10 , and the like. Further, based on the obtained information on the present location, the processing unit  1  reads out map data necessary to be displayed, from the storage unit  3  or the ROM device  6 . 
         [0031]    Still further, the processing unit  1  graphically develops the map data thus read out, and displays the map data thus developed with a mark indicating the present location superimposed thereon, on the display  2 . The processing unit  1  also makes a search for an optimal route (recommended route) which connects a departure place (present location) and a destination (or via point or stop-off point), which are designated by the user, by using the map data or the like stored in the storage unit  3  or the ROM device  6 . In addition, the processing unit  1  provides the user with guidance by using the speaker  42  and the display  2 . 
         [0032]    Further, the processing unit  1  may give priority to a route for using HOV lanes in the route search as described below. Note that, an HOV lane is a traffic lane prescribed that only vehicles with a predetermined number of passengers (for example, two persons including the driver) or more, or vehicles satisfying predetermined criteria (low fuel consumption or low emission) are qualified for traveling. 
         [0033]    The processing unit  1  of the navigation device  100  has a configuration in which devices are connected to one another by a bus  25 . The processing unit  1  includes a central processing unit (CPU)  21  which executes various kinds of processing such as performing mathematical operations and control on each of the devices, a random access memory (RAM)  22  which stores the map data and operation data read out from the storage unit  3 , a read only memory (ROM)  23  which stores programs and data, and an interface (I/F)  24  which connects various kinds of hardware to the processing unit  1 . 
         [0034]    The display  2  is a unit which displays graphic information created in the processing unit  1  or the like. The display  2  includes, for example, a liquid crystal display or an organic electroluminescence (EL) display. 
         [0035]    The storage unit  3  includes a storage medium such as a hard disk drive (HDD) or a nonvolatile memory card, which is capable of at least reading and writing. 
         [0036]    The storage medium stores a link table  200 , which is the map data (including link data on links constituting roads on the map) necessary for a general route search device, and a guide target link table  250  in which links identified as HOV lanes are registered. 
         [0037]      FIG. 2  is a diagram illustrating a configuration of the link table  200 . The link table  200  contains, for each identification code (mesh ID)  201  for a mesh which is a partitioned area on the map, link data  202  on each of the links constituting roads included in the mesh area. 
         [0038]    The link data  202  contains, for each link ID  211  which is an identifier of the link, coordinate information  222  on two nodes (initiating node and terminating node) which form the link, a road type  223  indicating a type of the road which includes the link (ordinary road, toll road, national highway, local street, or the like), a link length  224  indicating a length of the link, link travel time  225  which is stored in advance, an initiating connection link and terminating connection link  226  which identifies an initiating connection link, which is a link connected to the initiating node of the link, and a terminating connection link, which is a link connected to the terminating node of the link, a speed limit  227  indicating a speed limit of the road including the link, HOV lane information  228  for identifying an attribute regarding a status on whether or not an HOV lane is assigned for each link, and the like. 
         [0039]    The HOV attribute  228  includes “exclusive”, “shared-solid line”, “shared-broken line”, and “none”. The HOV attribute  228  has a “exclusive” attribute  229  when the link is a road constituted only of HOV lanes, and a “none” attribute  232  when the link is a road that does not include an HOV lane. Alternatively, the HOV attribute  228  has a “shared-solid line” attribute  230  when the link is a road which includes both an HOV lane and a normal lane and in which a lane change between the HOV lane and the normal lane is not allowed, and a “shared-broken line” attribute  231  when the link is a road which includes both an HOV lane and a normal lane and in which a lane change between the HOV lane and the normal lane is allowed. 
         [0040]      FIG. 3  is a diagram illustrating a configuration of the guide target link table  250 . The guide target link table  250  is a table in which links extracted in HOV target link extraction processing, which is to be described later, are registered. Registered in the guide target link table  250  are a link ID  251  of the extracted link, an “initiating node and terminating node”  252  of the link, a road type  253 , and an “initiating connection link and terminating connection link”  254 . Note that, for the link ID  251 , the “initiating node and terminating node”  252 , the road type  253 , and the “initiating connection link and terminating connection link”  254 , the same ID number and coordinate information as those registered in the link table  200  are used. 
         [0041]    Note that, in this example, the two nodes constituting the link are designated separately as the initiating node and the terminating node, and hence the upbound direction and the downbound direction of the same road are separately managed as different links. 
         [0042]    Returning again to  FIG. 1 , further explanation is given. The voice input/output unit  4  includes the microphone  41  as a voice input unit and the speaker  42  as a voice output unit. The microphone  41  picks up a sound produced outside the navigation device  100 , such as a voice uttered by the user or another passenger. 
         [0043]    The speaker  42  outputs a message to the user, which is created in the processing unit  1 , as a voice. The microphone  41  and the speaker  42  are separately disposed at predetermined positions in a vehicle, or may be integrally accommodated in a casing. The navigation device  100  may include a plurality of the microphones  41  and a plurality of the speakers  42 . 
         [0044]    The input unit  5  is a unit which receives an instruction from the user, through operations performed by the user. The input unit  5  includes a touch panel  51 , a dial switch  52 , and a scroll key, a zoom key, and the like as other hard switches (not shown). The input unit  5  also includes a remote controller capable of remotely issuing an operational instruction to the navigation device  100 . The remote controller includes a dial switch, a scroll key, a zoom key, and the like. The remote controller delivers information obtained by operations of the keys and the switches to the navigation device  100 . 
         [0045]    The touch panel  51  is mounted on the display surface side of the display  2 , allowing a display screen to be seen therethrough. The touch panel  51  identifies a touch position associated with the X and Y coordinates of an image displayed on the display  2 , and outputs the touch position converted into a form of the coordinates. The touch panel  51  includes a pressure-sensitive or capacitive input detecting element or the like. 
         [0046]    The dial switch  52  is configured to be rotatable in a clockwise direction or in a counter-clockwise direction, generates a pulse signal for each predetermined angle of rotation, and outputs the pulse signal to the processing unit  1 . The processing unit  1  obtains the rotation angle based on the number of the pulse signals. 
         [0047]    The ROM device  6  includes a storage medium such as a read only memory (ROM) including CD-ROM and DVD-ROM, or an integrated circuit (IC) card, which is at least readable. The storage medium stores, for example, moving image data and voice data. 
         [0048]    The vehicle speed sensor  7 , the gyro sensor  8 , and the GPS receiver  9  are used for calculating a present location (own vehicle position) in the navigation device  100 . The vehicle speed sensor  7  is a sensor which outputs a value to be used for calculating a vehicle speed. The gyro sensor  8  includes an optical-fiber gyroscope or a vibrating gyroscope, and detects an angular speed in accordance with the rotation of a moving object. The GPS receiver  9  receives a signal from a GPS satellite and measures, with respect to three or more satellites, a distance between a moving object and each of the GPS satellites and a rate of change in the distance, to thereby measure a present location, a traveling speed, and a traveling orientation of the moving object. 
         [0049]    The FM multiplex broadcasting receiver  10  receives an FM multiplex broadcasting signal transmitted from an FM broadcasting station. The FM multiplex broadcasting includes general current traffic information, regulation information, service area/parking area (SA/PA) information, parking information, weather information, and the like, which are provided as Vehicle Information Communication System (VICS: registered trademark) information, and text information provided as FM multiplex general information by a radio station. 
         [0050]    The beacon receiver  11  receives the general current traffic information, the regulation information, service area/parking area (SA/PA) information, the parking information, the weather information, which are provided as the VICS information, an emergency alert, and the like. The beacon receiver  11  is a receiver which receives, for example, an optical beacon communicated via light, a radio wave beacon communicated via radio waves, or the like. 
         [0051]      FIG. 4  illustrates the camera  12  mounted on the back of a vehicle  300 . The camera  12  faces slightly downward, and picks up an image of a ground surface at the rear of the vehicle by using an image pickup device such as a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) image sensor. Note that, the position at which the camera  12  is mounted is not particularly limited, and for example, the camera  12  may be mounted at the front of the vehicle  300  and pick up an image of a ground surface in front of the vehicle. 
         [0052]      FIG. 5  is a diagram illustrating a method of creating a ground projected image by using the image picked up by the camera  12  of  FIG. 4 . A camera control unit  104 , which is to be described later, obtains a position of a point of view P of the camera  12  (coordinate position in a three-dimensional space with its origin at a predetermined position in the vehicle) and an image pickup direction (line-of-sight direction) K. Then, the camera control unit  104  projects a picked-up image  510  on a ground surface  520  from the position of the point of view P of the camera  12  toward the image pickup direction K, to thereby create a ground projected image  530 . Note that, the image pickup direction K perpendicularly intersects the center of the picked-up image  510 . Further, the distance from the point of view P of the camera  12  to the picked-up image  510  is determined in advance. The ground projected image  530  thus created is a bird&#39; s eye view of the vehicle and its surroundings from above the vehicle. 
         [0053]    The in-vehicle network communication unit  13  is a device which connects the navigation device  100  to a network (not shown) compliant to a control network specification of the vehicle, such as Controller Area Network (CAN), and performs communication by exchanging CAN messages to and from an electronic control unit (ECU), which is a control device of another vehicle connected to the network. 
         [0054]      FIG. 6  is a functional block diagram of the processing unit  1 . As illustrated in  FIG. 6 , the processing unit  1  includes a main control unit  101 , an input reception unit  102 , an output processing unit  103 , the camera control unit  104 , a lane recognition unit  105 , a qualification for traveling HOV determination unit  106 , a route search unit  107 , a branch guiding unit  108 , and an HOV entrance guiding unit  109 . 
         [0055]    The main control unit  101  is a central functional unit which performs various kinds of processing, and controls other processing units depending on the type of the processing. The main control unit  101  also acquires information on the various sensors, the GPS receiver  9 , and the like, and performs map matching processing or the like to identify the present location. Further, the main control unit  101  outputs the current time in response to a request from the processing units. The main control unit  101  also manages various kinds of setting information contained in the navigation device  100 . For example, the main control unit  101  receives the various kinds of setting information from the user through the functional units, and stores the various kinds of setting information in the storage unit  3 . Note that, examples of the various kinds of setting information include information on the use of HOV lanes (for example, information on whether or not active use of HOV lanes is approved). When a request to acquire the various kinds of setting information is received from another functional unit, the main control unit  101  passes the information to the functional unit which has made the request. 
         [0056]    The input reception unit  102  receives an instruction input by the user through the input unit  5  or the microphone  41 , and controls each of the units of the processing unit  1  to execute processing corresponding to the request. For example, when the user makes a request to search a recommended route, the input reception unit  102  requests the output processing unit  103  to execute processing of displaying a map on the display  2  so that the destination may be set. 
         [0057]    The output processing unit  103  receives, for example, screen information to display information, such as polygon information, converts the screen information to a signal to be rendered on the display  2 , and instructs the display  2  to render the signal. 
         [0058]    The camera control unit  104  controls operation of the camera  12 . For example, the camera control unit  104  sets timings to start and end an image pick-up by the camera  12 . The camera control unit  104  also controls transmission of the picked-up image to the lane recognition unit  105 . 
         [0059]    The lane recognition unit  105  acquires the image picked up by the camera  12  as image data. Then, the lane recognition unit  105  converts the acquired image to an image for display (ground projected image). The lane recognition unit  105  also recognizes signs and the like provided or colored on the surface of the road from the acquired image, and identifies a type of a traffic lane in which the own vehicle is traveling. For example, as described below, the lane recognition unit  105  recognizes the presence of a sign (painted rhomboid) or the like indicating an HOV lane, and when the sign is present around the horizontal center in the image, determines that the vehicle  300  is traveling an HOV lane. In a case where the sign is recognized not at around the horizontal center in the image, but at a position shifted to the left or the right from the around horizontal center, and is recognized on the side nearer the edge with respect to a sign of a traffic lane when viewed from around the horizontal center, the lane recognition unit  105  determines that the vehicle  300  is traveling a lane which is not an HOV lane and is adjacent to an HOV lane. 
         [0060]    The qualification for traveling HOV determination unit  106  determines whether or not the own vehicle  300  is qualified for traveling HOV lanes. In determining the qualification, the qualification for traveling HOV determination unit  106  determines the type and the like of the own vehicle  300  based on the communication information flowing in an in-vehicle network of the own vehicle  300  through the in-vehicle network communication unit  13 , and determines whether or not the own vehicle  300  is of a type qualified for traveling HOV lanes. It should be understood, however, that the processing of determining qualification for traveling HOV lanes is not limited thereto, and the qualification for traveling HOV determination unit  106  may determine the occupancy from load sensors (not shown) installed in seats of the vehicle or through seat belt buckle sensors, and determine whether or not the occupancy has reached an occupancy to qualify for traveling HOV lanes. 
         [0061]    The route search unit  107  searches for an optimal route (recommended route) which connects the user specified departure place or the present location to the user specified destination. In the route search, the route search unit  107  searches for a route by using a route search logic such as the Dijkstra method, based on a link cost set in advance to a predetermined section (link) of the road. Note that, in the processing, the route search unit  107  requests the above-mentioned qualification for traveling HOV determination unit  106  to determine whether or not the own vehicle has a status to satisfy the qualification for traveling HOV lanes, and when a result of the determination is that the own vehicle has the status to satisfy the qualification for traveling, searches for a recommended route by giving priority to a route for using HOV lanes. 
         [0062]    When the own vehicle does not have the status to satisfy the qualification for traveling, the route search unit  107  searches for a route having the minimum link cost without considering HOV lanes. Note that, in the processing, even in a case where it is determined that the own vehicle does not have the status satisfy the qualification for using HOV lanes, when the own vehicle is already traveling an HOV lane, the route search unit  107  searches for a recommended route by giving priority to a route for using HOV lanes. In determining whether or not the own vehicle is already traveling an HOV lane, the route search unit  107  refers to the HOV attribute  228  of the link to which the present location belongs, and determines that the own vehicle is traveling an HOV lane when the HOV attribute  228  is “exclusive” and that the own vehicle is not traveling an HOV lane when the HOV attribute  228  is “none”. Alternatively, when the HOV attribute  228  is “shared”, the route search unit  107  makes the determination by requesting the lane recognition unit  105  to determine whether or not the traffic lane being traveled by the own vehicle is an HOV lane. 
         [0063]    The branch guiding unit  108  provides guidance to the driver as to the presence and position of a junction with another road, a branch to another road, and the like, by using a video or a voice. For example, the branch guiding unit  108  causes, through the output processing unit  103 , the display  2  to output a display notifying of an approaching junction and an approximate distance to the junction, before a position where a feeder road and a main road of an expressway or the like meet. Alternatively, the branch guiding unit  108  notifies, at a point where a ramp road branches from a main road of an expressway, the driver of a correct traffic lane to take, with a voice through the speaker  42 . 
         [0064]    The HOV entrance guiding unit  109  is a functional unit which extracts link information on a link corresponding to an HOV lane and registers the link information in the guide target link table  250 . Specifically, the HOV entrance guiding unit  109  refers to the HOV attributes  228  of links which are connected to the link on which the own vehicle is located and are within a predetermined range (for example, within 5 km), and identifies a link corresponding to an HOV lane. Then, the HOV entrance guiding unit  109  extracts information on the identified link and registers the extracted information in the guide target link table  250 . The HOV entrance guiding unit  109  is also a functional unit which provides guidance as to an entrance of the HOV lane. Specifically, when the own vehicle approaches a link registered in the guide target link table  250  enough to be within a predetermined distance range (for example, 500 m to 600 m), the HOV entrance guiding unit  109  displays a guidance image for guiding the own vehicle to the HOV lane and starts guidance as to the entrance of the HOV lane. 
         [0065]    The above-mentioned functional units of the processing unit  1  including the main control unit  101 , the input reception unit  102 , the output processing unit  103 , the camera control unit  104 , the lane recognition unit  105 , the qualification for traveling HOV determination unit  106 , the route search unit  107 , the branch guiding unit  108 , and the HOV entrance guiding unit  109  are implemented as the CPU  21  reads and executes predetermined programs. Therefore, the RAM  22  stores the programs for realizing the processing of the functional units. 
         [0066]    Note that, the above-mentioned components represent the configuration of the navigation device  100  classified by the type of the processing mainly performed by the components for ease of understanding. Therefore, the invention of the subject application is not limited by how the components are classified or the names of the components. The configuration of the navigation device  100  may be classified into a larger number of components based on the type of processing performed by the components. Alternatively, the configuration may be classified so that one component executes a larger number of processing. 
         [0067]    Alternatively, the functional units may be implemented by hardware (such as ASIC or GPU). Still alternatively, the processing of each of the functional units may be executed by one piece of hardware or a plurality of pieces of hardware. 
         [0068]    Next, operation of the target link extraction processing performed by the navigation device  100  is described.  FIG. 7  is a flow chart illustrating the target link extraction processing performed by the navigation device  100 . This flow starts when the navigation device  100  is activated. 
         [0069]    First, the HOV entrance guiding unit  109  determines whether or not HOV lanes can be used (Step S 001 ). In other words, the HOV entrance guiding unit  109  determines whether or not the navigation device  100  is set to use HOV lanes (Step S 001 ). Specifically, the HOV entrance guiding unit  109  acquires, from among the various kinds of setting information contained in the navigation device  100 , information on the use of HOV lanes (for example, information on whether or not the use of HOV lanes is approved is set or not) from the main control unit  101 . Then, the HOV entrance guiding unit  109  refers to the information to determine whether or not the setting is made to use HOV lanes. 
         [0070]    When the setting is made to use HOV lanes (Yes in Step S 001 ), the HOV entrance guiding unit  109  determines whether or not the own vehicle is qualified for traveling HOV lanes (Step S 002 ). Specifically, the HOV entrance guiding unit  109  requests the qualification for traveling HOV determination unit  106  to determine whether or not the own vehicle is qualified for traveling HOV lanes. On the other hand, when the setting is not made to use HOV lanes (No in Step S 001 ), the HOV entrance guiding unit  109  ends the target link extraction processing. 
         [0071]    In Step S 002 , the qualification for traveling HOV determination unit  106  determines whether or not the own vehicle is qualified for traveling HOV lanes. Specifically, the qualification for traveling HOV determination unit  106  identifies the type or occupancy based on the type of the own vehicle or information obtained from the load sensors or the seat belt buckle sensors. Then, the qualification for traveling HOV determination unit  106  determines whether or not the identified type or occupancy satisfies predetermined conditions for using HOV lanes, and outputs a result of the determination to the HOV entrance guiding unit  109 . 
         [0072]    When the own vehicle is qualified for traveling HOV lanes (Yes in Step S 002 ), the HOV entrance guiding unit  109  refers to the HOV attributes  228  of links which are connected to the link on which the own vehicle is located and are within the predetermined range (Step S 003 ). Specifically, the HOV entrance guiding unit  109  identifies the link on which the own vehicle is located based on the information registered in the link table  200 . Then, the HOV entrance guiding unit  109  refers to the HOV attributes  228  of links which are connected to the link on which the own vehicle is located and are within a range of 5 km or less from the own vehicle position, for example. On the other hand, when the own vehicle is not qualified for traveling HOV lanes (No in Step S 002 ), the HOV entrance guiding unit  109  ends the target link extraction processing. 
         [0073]    Note that, when the own vehicle is traveling a toll road, the HOV entrance guiding unit  109  refers to the HOV attributes  228  of links which are on the toll road and are within a predetermined range (for example, within 30 km) from the own vehicle position. 
         [0074]    The HOV entrance guiding unit  109  refers to the attributes  228  of the links (Step S 003 ), extracts a link for which “exclusive” or “shared-broken line” is registered in the HOV attribute  228 , and stores the extracted link in the guide target link table  250  (Step S 004 ). 
         [0075]    After executing Step S 004 , the HOV entrance guiding unit  109  shifts the processing to Step S 001  (R 001 ). In this way, the HOV entrance guiding unit  109  repeatedly executes the processing of Steps S 001  to S 004 . 
         [0076]    Note that, after executing Step S 004 , the HOV entrance guiding unit  109  may shift the processing to Step S 003  (R 002 ). In this case, for example, after executing the processing of Steps S 001  and S 002 , the HOV entrance guiding unit  109  may repeatedly execute the processing of Steps S 003  and S 004  (R 002 ) and shift the processing to Step S 001  at a predetermined timing (R 001 ). Specifically, the HOV entrance guiding unit  109  may repeatedly execute the processing of Steps S 003  and S 004  and shift the processing to Step S 001  at timings of every 10 minutes, for example (R 001 ). 
         [0077]    Next, referring to  FIG. 8 , HOV entrance guiding processing is described.  FIG. 8  is a flow chart illustrating the HOV entrance guiding processing. 
         [0078]    The HOV entrance guiding unit  109  determines whether or not there is a link which is stored in the guide target link table  250  by the target link extraction processing and which is within the predetermined range from the own vehicle position (Step S 011 ). Specifically, the HOV entrance guiding unit  109  examines presence or absence of a link which is stored in the guide target link table  250  and which is at a distance within a range of 500 m to 600 m from the own vehicle position, for example. When there is such link (Yes in Step S 011 ), the HOV entrance guiding unit  109  shifts the processing to Step S 012 . On the other hand, when there is no link within the predetermined range from the own vehicle position (No in Step S 011 ), the HOV entrance guiding unit  109  shifts the processing to Step S 013 . 
         [0079]    In Step S 011 , when there is a link within the predetermined range from the own vehicle position (Yes in Step S 011 ), the HOV entrance guiding unit  109  starts guidance as to the entrance of the HOV lane (Step S 012 ), and shifts the processing to Step S 023 . Specifically, the HOV entrance guiding unit  109  displays an image for guiding the own vehicle to the HOV lane on the display  2 . 
         [0080]    Note that, as the entrance guidance image for guiding the own vehicle to the HOV lane, an image that is enlarged compared to a normal guidance image of a branch (right turn or left turn) is displayed. Specifically, compared to the normal branch guidance, the road is displayed in a manner that the width thereof is appeared wider, and an arrow for encouraging a lane change is displayed in a manner that the size thereof is appeared larger. Displaying such enlarged image provides an advantage that the guidance as to the entrance of the HOV lane is more easily seen by a fellow passenger even with a small display  2 . The conditions required for traveling HOV lanes include, for example, that two or more passengers must be in the vehicle. Therefore, it is assumed that the vehicle using HOV lanes often carries a fellow passenger other than a driver. Therefore, when the guidance as to the entrance of the HOV lane is displayed as an enlarged view that is more easily seen by the fellow passenger, the fellow passenger may provide the guidance as to the entrance of the HOV lane more easily. On the other hand, when too large a guidance image is displayed in the normal branch guidance, the guidance image becomes rather difficult to see. Therefore, such display of the enlarged guidance image of the HOV lane provides an advantage specific to the guidance as to the entrance of the HOV lane. 
         [0081]    Note that, configuration of such HOV entrance guidance image is described later. Further, the HOV entrance guiding unit  109  executes voice guidance through the speaker  42  along with the display of the entrance guidance image. 
         [0082]    In Step S 013 , after the own vehicle has moved to the HOV lane, or after a predetermined period of time has elapsed since the own vehicle passed through the HOV lane entrance, the HOV entrance guiding unit  109  switches the entrance guidance image that is being displayed back to the map image or the like that was displayed before the entrance guidance image. Specifically, the HOV entrance guiding unit  109  requests the lane recognition unit  105  to determine whether or not the own vehicle is traveling an HOV lane. When the own vehicle is traveling an HOV lane, or when the predetermined period of time has elapsed since the own vehicle passed through the HOV lane entrance, the HOV entrance guiding unit  109  displays again the map image or the like that was displayed before the entrance guidance image of the HOV lane that is being displayed on the display  2 . Then, the HOV entrance guiding unit  109  shifts the processing to Step S 104 . 
         [0083]    In Step S 014 , the HOV entrance guiding unit  109  deletes a link that has been stored in the guide target link table  250  for a predetermined period of time from when the link is stored. Specifically, the HOV entrance guiding unit  109  deletes, of the links stored in the guide target link table  250 , information on a link that has been stored for one hour or more from when the link is stored. Note that, such period of time for which a link is stored may be set as appropriate. Alternatively, instead of setting the predetermined period of time for which a link is stored as a requirement for deleting the link, the HOV entrance guiding unit  109  may delete a registered link when the own vehicle position moves away from the registered link by a predetermined distance or more, for example. The predetermined distance may also be set as appropriate. Note that, in the HOV entrance guiding processing illustrated in  FIG. 8 , the processing of Steps S 011  to S 014  is repeatedly executed while the target link extraction processing is executed. 
         [0084]    Hereinabove, the flows of the target link extraction processing and the HOV entrance guiding processing have been described. 
         [0085]    Next, an example screen of the navigation device  100  after execution of the target link extraction processing and the HOV entrance guiding processing is described.  FIG. 9A  is an example screen in which the guidance as to the entrance of the HOV lane is displayed while the vehicle is traveling an ordinary road.  FIG. 9B  is an example screen in which the guidance as to the entrance of the HOV lane is displayed while the vehicle is traveling a toll road. Note that, the same reference symbols are used for the same parts, and description thereof is omitted. 
         [0086]    An example screen  301  of  FIG. 9A  is a map image indicating a position  302  of the own vehicle that is traveling an ordinary road. When a link stored in the guide target link table  250  is located within a range of 500 m to 600 m from the own vehicle position, the HOV entrance guiding unit  109  displays an entrance guidance view  303  of an HOV lane on the display  2  (Steps S 011  to S 014 ). As illustrated in  FIG. 9A , the entrance guidance view  303  is displayed as an image obtained by enlarging a portion from the own vehicle position to the entrance of the HOV lane. 
         [0087]    Shown in the entrance guidance view  303  are a front road graphic  304  showing a front road, a travel lane indication graphic  305  indicating a travel lane, an HOV lane graphic  306  indicating that there is an HOV lane ahead, a distance indication graphic  307  for graphically indicating a distance to a point of entry to the HOV lane, a distance meter  308  displayed to be superimposed on the distance indication graphic, and a distance indication  309  for numerically indicating the distance to the point of entry to the HOV lane. 
         [0088]    As shown in the example screen  303 , the distance meter  308  and the distance indication  309  indicate the distance to the point of entry to the HOV lane so that the driver can easily understand the timing to steer a vehicle into a direction of the HOV lane entrance. Further, at a position ahead of the travel lane indication graphic  305 , the HOV lane graphic  306  is displayed so that the driver can easily be aware that the vehicle is about to be entered the HOV lane and the correct travel lane leads to the HOV lane. Further, the entrance guidance image of the HOV lane is displayed as an image that is enlarged compared to the normal branch guidance. As a result, the entrance guidance image is displayed in a manner that is easy to see not only for the driver but also for a fellow passenger. 
         [0089]    An example screen  401  of  FIG. 9B  displays an image showing the own vehicle position on a toll road. Note that, when the own vehicle is traveling a toll road, the HOV entrance guiding unit  109  extracts a target link as to which the entrance guidance is to be provided, from links on the toll road on which the own vehicle is located, and stores the target link in the guide target link table  250  (Steps S 001  to S 004 ). 
         [0090]    Displayed on the example screen  401  are check point graphics  402  indicating check points such as an interchange or a service area, an own vehicle position graphic  403 , graphics  404  indicating entrance/exit information on an HOV lane, and a scroll operation graphic  405  for receiving an instruction to scroll the screen. 
         [0091]    The HOV entrance guiding unit  109  repeatedly executes the processing of Steps S 001  to S 004  to store links which are on the toll road and which have the HOV attributes  228  of “shared-broken line” in the guide target link table  250 . 
         [0092]    Further, based on position information on the link stored in the guide target link table  250 , the HOV entrance guiding unit  109  identifies a link that is closest to the own vehicle position. Then, the HOV entrance guiding unit  109  regards such link as an entrance to an HOV lane, and displays the graphic  404  indicating the entrance/exit information on the HOV lane to be superimposed on the check point graphic  402  or between check points. 
         [0093]    Further, based on the position information on the link stored in the guide target link table  250 , the HOV entrance guiding unit  109  identifies a link which is the closest to the own vehicle position, other than the link that is regarded as the entrance to the HOV lane, and which has the HOV attribute  228  of “shared-broken line”. Then, the HOV entrance guiding unit  109  regards such link as an exit of the HOV lane, and displays the graphic  404  indicating the entrance/exit information on the HOV lane to be superimposed on the check point graphic  402  or between check points. 
         [0094]    Next, when there is a link, among the links registered in the guide target link table  250 , that is within a predetermined range from the own vehicle position, the HOV entrance guiding unit  109  displays the entrance guidance view  303  of the HOV lane on the display  2 . Specifically, when there is a link that is an entrance to an HOV lane within a range of, for example, 1 km to 1.2 km from the own vehicle position, the HOV entrance guiding unit  109  displays the entrance guidance view  303  of the HOV lane on the display  2  (Steps S 011  to S 014 ). At this time, the entrance guidance image of the HOV lane is displayed as an enlarged image compared to the normal branch guidance. As a result, the entrance guidance image is displayed in a manner that is easy to see not only for the driver but also for a fellow passenger. 
         [0095]    As described above, the navigation device according to the first embodiment of the first aspect of the present invention executes guidance as to the entrance of the HOV lane that is within the predetermined range from the own vehicle with the enlarged view. Therefore, according to the present invention, the guidance can be provided by visually displaying the HOV lane in a manner that is easier to see. 
         [0096]    Note that, the navigation device  100  according to the first embodiment described above extracts link information on the link having the HOV attribute  228  of “exclusive” or “shared-broken line”, but the present invention is not limited thereto. According to the navigation device  100  of a second embodiment of the first aspect of the present invention, link information on a link connected along the road to the link on which the own vehicle is located is further displayed. Referring to  FIG. 10 , operation of the navigation device  100  according to the second embodiment of the first aspect of the present invention is described. 
         [0097]      FIG. 10  is a flow chart illustrating target link extraction processing performed by the navigation device  100  according to the second embodiment. In the second embodiment, all the processing other than Step s 024  show the same processing executed in the first embodiment. Therefore, the description of the types of processing similar to those of the first embodiment is omitted. Further, the flow illustrated in  FIG. 10  starts when the navigation device  100  is activated. 
         [0098]    In Step S 024  of  FIG. 10 , the HOV entrance guiding unit  109  extracts link information on a link connected along the road to the link on which the own vehicle is located, the link having the HOV attribute  228  of “exclusive” or “shared-broken line”. Specifically, when a plurality of links are not connected to the terminating node of the link on which the own vehicle is located, the HOV entrance guiding unit  109  identifies a link connected to the link on which the own vehicle is located as a link along the road. 
         [0099]    On the other hand, when a plurality of links are connected to the terminating node of the link on which the own vehicle is located, the HOV entrance guiding unit  109  identifies, of the plurality of links, a link having the smallest difference from a link orientation of the link on which the own vehicle is located as the link along the road. For example, as illustrated in  FIG. 11 , only one link is connected to a terminating node of a link  602  on which an own vehicle position  601  is located. In this case, the HOV entrance guiding unit  109  identifies a link  603  connected to the terminating node of the link  602  as the link along the road. 
         [0100]    Further, only one link  604  is connected to a terminating node of the link  603 , and hence the HOV entrance guiding unit  109  identifies the link  604  as the link connected along the road to the link  603 . 
         [0101]    In this example, two links, that is, a link  606  and a link  607  are connected to a terminating node of a link  605 . In this case, the HOV entrance guiding unit  109  identifies the link  606 , which is a link having the smallest difference from a link orientation  608  of the link  605  as the link along the road. 
         [0102]    Further, the HOV entrance guiding unit  109  tracks links which are connected to the link on which the own vehicle is located and are within a predetermined range (for example, within 5 km), to identify the links along the road. 
         [0103]    Then, the HOV entrance guiding unit  109  extracts a link which is identified as the link along the road and has the HOV attribute  228  of “exclusive” or “shared-broken line”, and stores the extracted link in the guide target link table  250 . 
         [0104]    Note that, in identifying the link along the road, the road type of the link table may be referred to, for example. That is, when a plurality of links are connected to a terminating node of a certain link, a link having the same road type as the road type (for example, national highway) of the certain link may be identified as a link connected along the road to the link. 
         [0105]    Note that, also in the second embodiment of the first aspect of the present invention as described above, the HOV entrance guiding processing is executed as in the first embodiment. 
         [0106]    As described above, according to the second embodiment of the first aspect of the present invention, entrance guidance can be provided only for the HOV lane on the link along the road. In other words, guidance as to an HOV lane that appears after turning right or left from the link on which the own vehicle is located can be restricted. As a result, the number of times of entrance guidance as to the HOV lane can be suppressed, and the guidance as to the HOV lane can be provided by visually displaying the HOV lane in a manner that is easier to see. 
         [0107]    Next, a navigation device to which a first embodiment of the second aspect of the present invention is applied is described with reference to the drawings. 
         [0108]      FIG. 12  is an overall configuration diagram of a navigation device  1000 . The navigation device  1000  is a so-called navigation device capable of displaying map information, and of showing a point indicating a present location of the navigation device  1000  and information for guiding a route to a set destination. 
         [0109]    The navigation device  1000  includes a processing unit  1001 , a display  1002 , a storage unit  1003 , a voice input/output unit  1004  (including a microphone  1041  as a voice input unit and a speaker  1042  as a voice output unit), an input unit  1005 , a ROM device  1006 , a vehicle speed sensor  1007 , a gyro sensor  1008 , a global positioning system (GPS) receiver  1009 , an FM multiplex broadcasting receiver  1010 , a beacon receiver  1011 , a camera  1012 , and an in-vehicle network communication unit  1013 . 
         [0110]    The processing unit  1001  is a central unit which performs various kinds of processing. For example, the processing unit  1001  calculates the present location based on information output by, for example, the various sensors  1007  and  1008 , the GPS receiver  1009 , the FM multiplex broadcasting receiver  1010 , and the like. Further, based on the obtained information on the present location, the processing unit  1001  reads out map data necessary for display, from the storage unit  1003  or the ROM device  1006 . 
         [0111]    Still further, the processing unit  1001  graphically develops the map data thus read out, and displays the map data thus developed with a mark indicating the present location superimposed thereon, on the display  1002 . The processing unit  1001  also makes a search for an optimal route (recommended route) which connects a departure place (present location) and a destination (or via point or stop-off point), which are designated by the user, by using the map data or the like stored in the storage unit  1003  or the ROM device  1006 . In addition, the processing unit  1001  provides the user with guidance by using the speaker  1042  and the display  1002 . 
         [0112]    Further, the processing unit  1001  may give priority to a route for traveling HOV lanes in the route search as described below. Note that, an HOV lane is a traffic lane prescribed that only vehicles with a predetermined number of passengers (for example, two persons including the driver) or more, or vehicles satisfying predetermined criteria (low fuel consumption or low emission) are qualified for traveling. 
         [0113]    The processing unit  1001  of the navigation device  1000  has a configuration in which devices are connected to one another by a bus  1025 . The processing unit  1001  includes a central processing unit (CPU)  1021  which executes various kinds of processing such as performing mathematical operations and control on each of the devices, a random access memory (RAM)  1022  which stores the map data and operation data read out from the storage unit  1003 , a read only memory (ROM)  1023  which stores programs and data, and an interface (I/F)  1024  which connects various kinds of hardware to the processing unit  1001 . 
         [0114]    The display  1002  is a unit which displays graphic information created in the processing unit  1001  or the like. The display  1002  includes, for example, a liquid crystal display or an organic electroluminescence (EL) display. 
         [0115]    The storage unit  1003  includes a storage medium such as a hard disk drive (HDD) or a nonvolatile memory card, which is capable of at least reading and writing. 
         [0116]    The storage medium stores a link table  1200 , which is the map data (including link data on links constituting roads on the map) necessary for a general route search device, and a guide target link table  1250  in which links identified as HOV lanes are registered. 
         [0117]      FIG. 13  is a diagram illustrating a configuration of the link table  1200 . The link table  1200  contains, for each identification code (mesh ID)  1201  for a mesh which is a partitioned area on the map, link data  1202  on each of the links constituting roads included in the mesh area. 
         [0118]    The link data  1202  contains, for each link ID  1211  which is an identifier of the link, coordinate information  1222  on two nodes (initiating node and terminating node) which form the link, a road type  1223  indicating a type of the road which includes the link, a link length  1224  indicating a length of the link, link travel time  1225  which is stored in advance, an initiating connection link and terminating connection link  1226  which identifies an initiating connection link, which is a link connected to the initiating node of the link, and a terminating connection link, which is a link connected to the terminating node of the link, a speed limit  1227  indicating a speed limit of the road including the link, HOV lane information  1228  for identifying an attribute regarding a status on whether or not an HOV lane is provided for each link, and the like. 
         [0119]    The HOV lane information  1228  contains HOV attribute details data  1230  indicating whether or not the link can be an HOV lane. In the HOV attribute details data  1230 , an attribute  1231  indicating whether or not an HOV lane is provided to the link, and when an HOV lane is provided, a time of day  1232  when the HOV lane is provided are registered in association with each other. Specifically, when an HOV lane is provided to the link, “YES” is registered in the attribute  1231 . Also, times of day (for example, 6:00 to 10:00, 15:00 to 17:00, and the like) when the link is an HOV lane are registered in association with the attributes  1231  indicating “YES”. 
         [0120]      FIG. 14  is a diagram illustrating a configuration of the guide target link table  1250 . The guide target link table  1250  is a table in which links extracted in HOV target link extraction processing, which is to be described later, are registered. Registered in the guide target link table  1250  are a link ID  1251  of the extracted link, an “initiating node and terminating node”  252  of the link, and an “initiating connection link and terminating connection link”  1253 . Note that, for the link ID  1251 , the “initiating node and terminating node”  1252 , and the “initiating connection link and terminating connection link”  1253 , the same ID number and coordinate information as those registered in the link table  1200  are used. 
         [0121]    Note that, in this example, the two nodes constituting the link are differentiated from each other as the initiating node and the terminating node, and hence the upbound direction and the downbound direction of the same road are separately managed as different links. 
         [0122]    Returning again to  FIG. 12 , further description is given. The voice input/output unit  4  includes the microphone  1041  as a voice input unit and the speaker  1042  as a voice output unit. The microphone  1041  picks up a sound produced outside the navigation device  1000 , such as a voice uttered by the user or another passenger. 
         [0123]    The speaker  1042  outputs a message to the user, which is created in the processing unit  1000 , as a voice. The microphone  1041  and the speaker  1042  are separately disposed at predetermined positions in a vehicle, or may be integrally accommodated in a casing. The navigation device  1000  may include a plurality of the microphones  1041  and a plurality of the speakers  1042 . 
         [0124]    The input unit  1005  is a unit which receives an instruction from the user, through operations performed by the user. The input unit  1005  includes a touch panel  1051 , a dial switch  1052 , and a scroll key, a zoom key, and the like as other hard switches (not shown). The input unit  1005  also includes a remote controller capable of remotely issuing an operational instruction to the navigation device  1000 . The remote controller includes a dial switch, a scroll key, a zoom key, and the like. The remote controller delivers information corresponding to operations on the keys and the switches to the navigation device  1000 . 
         [0125]    The touch panel  1051  is mounted on the display surface side of the display  1002 , allowing a display screen to be seen therethrough. The touch panel  1051  identifies a touch position which is associated with the X and Y coordinates of an image displayed on the display  1002 , and outputs the touch position converted into a form of the coordinates. The touch panel  1051  includes a pressure-sensitive or capacitive input detecting element or the like. 
         [0126]    The dial switch  1052  is configured to be rotatable in a clockwise direction or in a counter-clockwise direction, generates a pulse signal for each predetermined angle of rotation, and outputs the pulse signal to the processing unit  1001 . The processing unit  1001  obtains the rotation angle based on the number of the pulse signals. 
         [0127]    The ROM device  1006  includes a storage medium such as a read only memory (ROM) including CD-ROM and DVD-ROM, or an integrated circuit (IC) card, which is at least readable. The storage medium stores, for example, moving image data and voice data. 
         [0128]    The vehicle speed sensor  1007 , the gyro sensor  1008 , and the GPS receiver  1009  are used for calculating a present location (own vehicle position) in the navigation device  1000 . The vehicle speed sensor  1007  is a sensor which outputs a value to be used for calculating a vehicle speed. The gyro sensor  1008  includes an optical-fiber gyroscope or a vibrating gyroscope, and detects an angular speed in accordance with the rotation of a moving object. The GPS receiver  1009  receives a signal from a GPS satellite and measures, with respect to three or more satellites, a distance between a moving object and each of the GPS satellites and a rate of change in the distance, to thereby measure a present location, a traveling speed, and a traveling orientation of the moving object. 
         [0129]    The FM multiplex broadcasting receiver  1010  receives an FM multiplex broadcasting signal transmitted from an FM broadcasting station. The FM multiplex broadcasting includes general current traffic information, regulation information, service area/parking area (SA/PA) information, parking information, weather information, and the like, which are provided as Vehicle Information Communication System (VICS: registered trademark) information, and text information provided as FM multiplex general information by a radio station. 
         [0130]    The beacon receiver  1011  receives the general current traffic information, the regulation information, service area/parking area (SA/PA) information, the parking information, the weather information, which are provided as the VICS information, an emergency alert, and the like. The beacon receiver  1011  is a receiver which receives, for example, an optical beacon communicated via light, a radio wave beacon communicated via radio waves, or the like. 
         [0131]      FIG. 15  illustrates the camera  1012  mounted on the back of a vehicle  1300 . The camera  1012  faces slightly downward, and picks up an image of a ground surface at the rear of the vehicle by using an image pickup device such as a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) image sensor. Note that, the position at which the camera  1012  is mounted is not particularly limited, and for example, the camera  1012  may be mounted at the front of the vehicle  1300  and pick up an image of a ground surface in front of the vehicle. 
         [0132]      FIG. 16  is a diagram illustrating a method of creating a ground projected image by using the image picked up by the camera  1012  of  FIG. 15 . A camera control unit  1104 , which is to be described later, obtains a position of a point of view P of the camera  1012  (coordinate position in a three-dimensional space with its origin at a predetermined position in the vehicle) and an image pickup direction (line-of-sight direction) K. Then, the camera control unit  1104  projects a picked-up image  1510  on a ground surface  1520  from the position of the point of view P of the camera  1012  toward the image pickup direction K, to thereby create a ground projected image  1530 . Note that, the image pickup direction K perpendicularly intersects the center of the picked-up image  1510 . Further, the distance from the point of view P of the camera  1012  to the picked-up image  1510  is determined in advance. The ground projected image  1530  thus created is a bird&#39; s eye view of the vehicle and its surroundings from above the vehicle. 
         [0133]    The in-vehicle network communication unit  1013  is a device which connects the navigation device  1000  to a network (not shown) compliant to a control network specification of the vehicle, such as Controller Area Network (CAN), and performs communication by exchanging CAN messages to and from an electronic control unit (ECU), which is another vehicle control device connected to the network. 
         [0134]      FIG. 17  is a functional block diagram of the processing unit  1001 . As illustrated in  FIG. 17 , the processing unit  1001  includes a main control unit  1101 , an input reception unit  1102 , an output processing unit  1103 , the camera control unit  1104 , a lane recognition unit  1105 , a qualification for traveling HOV determination unit  1106 , a route search unit  1107 , a branch guiding unit  1108 , and an HOV entrance guiding unit  1109 . 
         [0135]    The main control unit  1101  is a central functional unit which performs various kinds of processing, and controls other processing units depending on the type of the processing. The main control unit  1101  also acquires information on the various sensors, the GPS receiver  1009 , and the like, and performs map matching processing or the like to identify the present location. Further, the main control unit  1101  outputs the current time in response to a request from the processing units. The main control unit  1101  also manages various kinds of setting information contained in the navigation device  1000 . For example, the main control unit  1101  receives the various kinds of setting information from the user through the functional units, and stores the various kinds of setting information in the storage unit  1003 . Note that, examples of the various kinds of setting information include information on the use of HOV lanes (for example, information on whether or not active use of HOV lanes is approved). When a request to provide the various kinds of setting information is received from another functional unit, the main control unit  1101  passes the information to the functional unit which has made the request. 
         [0136]    The input reception unit  1102  receives an instruction input by the user through the input unit  1005  or the microphone  1041 , and controls each of the units of the processing unit  1001  to execute processing corresponding to the request. For example, when the user makes a request to search a recommended route, the input reception unit  1102  requests the output processing unit  1103  to execute processing of displaying a map on the display  1002  so that the destination may be set. 
         [0137]    The output processing unit  1103  receives, for example, screen information to display, such as polygon information, converts the screen information to a signal to be rendered on the display  1002 , and instructs the display  1002  to render the signal. 
         [0138]    The camera control unit  1104  controls operation of the camera  1012 . For example, the camera control unit  1104  sets timings to start and end picking up an image by the camera  1012 . The camera control unit  1104  also controls transmission of the picked-up image to the lane recognition unit  1105 . 
         [0139]    The lane recognition unit  1105  acquires the image picked up by the camera  1012  as image data. Then, the lane recognition unit  1105  converts the acquired image to an image for display (ground projected image). The lane recognition unit  1105  also recognizes signs and the like provided or colored on the surface of the road from the acquired image, and identifies a type of a traffic lane in which the own vehicle is traveling. For example, as described below, the lane recognition unit  1105  recognizes the presence of a sign (painted rhomboid) or the like indicating an HOV lane, and when the sign is present around the horizontal center in the image, determines that the vehicle  1300  is traveling an HOV lane. In a case where the sign is recognized not at around the horizontal center in the image, but at a position shifted to the left or the right from the around horizontal center, and is recognized on the side nearer the edge with respect to a sign of a traffic lane when viewed from around the horizontal center, the lane recognition unit  1105  determines that the vehicle  1300  is traveling a lane which is not an HOV lane and is adjacent to an HOV lane. 
         [0140]    The qualification for traveling HOV determination unit  1106  determines whether or not the own vehicle  1300  is qualified for traveling HOV lanes. In determining the qualification, the qualification for traveling HOV determination unit  1106  determines the type and the like of the own vehicle  1300  based on the communication information flowing in an in-vehicle network of the own vehicle  1300  through the in-vehicle network communication unit  1013 , and determines whether or not the own vehicle  1300  is of a type qualified for traveling HOV lanes. It should be understood, however, that the processing of determining qualification for traveling HOV lanes is not limited thereto, and the qualification for traveling HOV determination unit  1106  may determine the occupancy from load sensors (not shown) installed in seats of the vehicle or through seat belt buckle sensors, and determine whether or not the occupancy has reached an occupancy to qualify for traveling HOV lanes. 
         [0141]    The route search unit  1107  searches for an optimal route (recommended route) which connects the user specified departure place (current position) to the user specified destination. In the route search, the route search unit  1107  searches for a route by using a route search logic such as the Dijkstra method, based on a link cost set in advance to a predetermined section (link) of the road. Note that, in the processing, the route search unit  1107  requests the above-mentioned qualification for traveling HOV determination unit  1106  to determine whether or not the own vehicle has a status to satisfy the qualification for traveling HOV lanes, and when a result of the determination is that the own vehicle has the status to satisfy the qualification for traveling, searches for a recommended route by giving priority to a route for using HOV lanes. 
         [0142]    When the own vehicle does not have the status to satisfy the qualification for traveling, the route search unit  1107  searches for a route having the minimum link cost without considering HOV lanes. Note that, in the processing, even in a case where it is determined that the own vehicle does not have the status to satisfy the qualification for using HOV lanes, when the own vehicle is already traveling an HOV lane, the route search unit  1107  searches for a recommended route by giving priority to a route for using HOV lanes. In determining whether or not the own vehicle is already traveling an HOV lane, the route search unit  1107  refers to the HOV lane information  1228  on the link to which the present position belongs. When “YES” is registered in the attribute  1231  and the current time is included in the time of day associated with the attribute  1231  of “YES”, the route search unit  1107  determines that the own vehicle is traveling an HOV lane. On the other hand, in other cases (a case where the HOV lane information  1228  on the link to which the present position belongs does not have the attribute  1231  to which “YES” is registered, or in a case where the current time is not included in the time of day  1232  associated with the attribute  1231  to which “YES” is registered), the route search unit  1107  determines that the own vehicle is not traveling an HOV lane. 
         [0143]    The branch guiding unit  1108  provides guidance to the driver as to the presence and position of a junction with another road, a branch to another road, and the like, by using a video or a voice. For example, the branch guiding unit  1108  causes, through the output processing unit  1103 , the display  1002  to output a display notifying of an approaching junction and an approximate distance to the junction, before a position where a feeder road and a main road of an expressway or the like meet. Alternatively, the branch guiding unit  1108  notifies, at a point where a ramp road branches from a main road of an expressway, the driver of a correct traffic lane to take, with a voice through the speaker  1042 . 
         [0144]    The HOV entrance guiding unit  1109  is a functional unit which extracts link information on a link corresponding to an HOV lane and registers the link information in the guide target link table  1250 . Specifically, the HOV entrance guiding unit  1109  refers to the HOV lane information  1228  of links which are within a predetermined range (for example, within 5 km) from the own vehicle position at the current time, and identifies a link corresponding to an HOV lane. Then, the HOV entrance guiding unit  1109  extracts information on the identified link and registers the extracted information in the guide target link table  1250 . The HOV entrance guiding unit  1109  is also a functional unit which provides guidance as to an entrance of the HOV lane. Specifically, when the own vehicle approaches a link registered in the guide target link table  1250  enough to be within a predetermined distance (for example, 500 m), the HOV entrance guiding unit  1109  starts guidance as to the entrance of the HOV lane. 
         [0145]    The above-mentioned functional units of the processing unit  1001  including the main control unit  1101 , the input reception unit  1102 , the output processing unit  1103 , the camera control unit  1104 , the lane recognition unit  1105 , the qualification for traveling HOV determination unit  1106 , the route search unit  1107 , the branch guiding unit  1108 , and the HOV entrance guiding unit  1109  are implemented as the CPU  1021  reads and executes predetermined programs. Therefore, the RAM  1022  stores the programs for realizing the processing of the functional units. 
         [0146]    Note that, the above-mentioned components represent the configuration of the navigation device  1000  classified by the type of the processing mainly performed by the components for ease of understanding. Therefore, the invention of the subject application is not limited by how the components are classified or the names of the components. The configuration of the navigation device  1000  may be classified into a larger number of components based on the type of processing performed by the components. Alternatively, the configuration may be classified so that one component executes a larger number of processing. 
         [0147]    Alternatively, the functional units may be implemented by hardware (such as ASIC or GPU). Still alternatively, the processing of each of the functional units may be executed by one piece of hardware or a plurality of pieces of hardware. 
         [0148]    Next, operation of the target link extraction processing performed by the navigation device  1000  is described.  FIG. 18  is a flow chart illustrating the target link extraction processing performed by the navigation device  1000 . This flow starts when the navigation device  1000  is activated. 
         [0149]    First, the HOV entrance guiding unit  1109  determines whether or not HOV lanes can be used (Step S 1001 ). In other words, the HOV entrance guiding unit  1109  determines whether or not the navigation device  1000  is set to use HOV lanes (Step S 1001 ). Specifically, the HOV entrance guiding unit  1109  acquires, from among the various kinds of setting information contained in the navigation device  1000 , information on the use of HOV lanes (for example, information on whether or not the use of HOV lanes is approved is set or not) from the main control unit  1101 . Then, the HOV entrance guiding unit  1109  refers to the information to determine whether or not the setting is made to use HOV lanes. 
         [0150]    When the setting is made to use HOV lanes (Yes in Step S 1001 ), the HOV entrance guiding unit  1109  determines whether or not the own vehicle is qualified for traveling HOV lanes (Step S 1002 ). Specifically, the HOV entrance guiding unit  1109  requests the qualification for traveling HOV determination unit  1106  to determine whether or not the own vehicle is qualified for traveling HOV lanes. On the other hand, when the setting is not made to use HOV lanes (No in Step S 1001 ), the HOV entrance guiding unit  1109  ends the target link extraction processing. 
         [0151]    In Step S 1002 , the qualification for traveling HOV determination unit  1106  determines whether or not the own vehicle is qualified for traveling HOV lanes. Specifically, the qualification for traveling HOV determination unit  1106  identifies the type or occupancy based on the type of the own vehicle or information obtained from the load sensors or the seat belt buckle sensors. Then, the qualification for traveling HOV determination unit  1106  determines whether or not the identified type or occupancy satisfies predetermined conditions for using HOV lanes, and outputs a result of the determination to the HOV entrance guiding unit  1109 . 
         [0152]    When the own vehicle is qualified for traveling HOV lanes (Yes in Step S 1002 ), the HOV entrance guiding unit  1109  examines, for links which are connected to the link on which the own vehicle is located and are within the predetermined range, the HOV attributes corresponding to the current time (Step S 1003 ). Specifically, the HOV entrance guiding unit  109  identifies the link on which the own vehicle is located based on the information registered in the link table  1200 . Then, the HOV entrance guiding unit  1109  examines the HOV attributes of links which are connected to the link on which the own vehicle is located and are within a range of 5 km or less from the own vehicle position, for example. At this time, the HOV entrance guiding unit  1109  examines the attributes  1231  corresponding to the current time for each of the links. On the other hand, when the own vehicle is not qualified for traveling HOV lanes (No in Step S 1002 ), the HOV entrance guiding unit  1109  ends the target link extraction processing. 
         [0153]    The HOV entrance guiding unit  1109  examines the attributes  1231  of the links (Step S 1003 ), extracts a link for which “YES” is registered in the attribute  1231  corresponding to the time of day  1232  including the current time, and stores the extracted link in the the guide target link table  1250  (Step S 1004 ). 
         [0154]    After executing Step S 1004 , the HOV entrance guiding unit  1109  shifts the processing to Step S 1001  (R 1001 ). In this way, the HOV entrance guiding unit  1109  repeatedly executes the processing of Steps S 1001  to S 1004 . 
         [0155]    Note that, after executing Step S 1004 , the HOV entrance guiding unit  1109  may shift the processing to Step S 1003  (R 1002 ). In this case, for example, after executing the processing of Steps S 1001  and S 1002 , the HOV entrance guiding unit  1109  may repeatedly execute the processing of Steps S 1003  and S 1004  (R 1002 ) and shift the processing to Step S 1001  at a predetermined timing (R 1001 ). Specifically, the HOV entrance guiding unit  1109  may repeatedly execute the processing of Steps S 1003  and S 1004  and shift the processing to Step S 1001  at timings of every 10 minutes, for example (R 1001 ). 
         [0156]    Next, referring to  FIG. 19 , HOV entrance guiding processing is described.  FIG. 19  is a flow chart illustrating the HOV entrance guiding processing. 
         [0157]    The HOV entrance guiding unit  1109  determines whether or not there is a link which is stored in the guide target link table  1250  by the target link extraction processing and which is within the predetermined range from the own vehicle position (Step S 1021 ). Specifically, the HOV entrance guiding unit  1109  examines presence or absence of a link which is stored in the guide target link table  1250  and which is at a distance within a range of 500 m from the own vehicle position, for example. When there is such link (Yes in Step S 1021 ), the HOV entrance guiding unit  1109  starts guidance as to an entrance of an HOV lane (S 1022 ). Specifically, the HOV entrance guiding unit  1109  displays the required time and the distance to the HOV lane, the lane position of the HOV lane, and the like on the display  1002 , and provides voice guidance through the speaker  1042 . 
         [0158]    On the other hand, when there is no link within the predetermined range from the own vehicle position (No in Step S 1021 ), the HOV entrance guiding unit  1109  shifts the processing to Step S 1033 . 
         [0159]    In Step S 1023 , the HOV entrance guiding unit  1109  deletes a link that has been stored in the guide target link table  1250  for a predetermined period of time from when the link is stored. Specifically, the HOV entrance guiding unit  1109  deletes, of the links stored in the guide target link table  1250 , information on a link that has been stored for one hour or more from when the link is stored. Note that, such period of time for which a link is stored may be set as appropriate. Alternatively, instead of setting the predetermined period of time for which a link is stored as a requirement for deleting the link, the HOV entrance guiding unit  109  may delete a registered link when the own vehicle position moves away from the link by a predetermined distance or more, for example. The predetermined distance may also be set as appropriate. Note that, in the HOV entrance guiding processing illustrated in  FIG. 19 , the processing of Steps S 1021  to S 1023  is repeatedly executed while the target link extraction processing is executed. 
         [0160]    Hereinabove, the flows of the target link extraction processing and the HOV entrance guiding processing have been described. 
         [0161]    According to the navigation device of the first embodiment of the second aspect of the present invention as described above, in determining whether or not the link is an HOV lane, the HOV attribute that changes depending on the time of day is taken into consideration. As a result, according to the navigation device of the first embodiment of the second aspect of the present invention, the determination on whether or not the link is an HOV lane can be performed at higher accuracy to provide guidance as to the HOV lane. 
         [0162]    Note that, the navigation device  1000  according to the first embodiment of the second aspect of the present invention described above identifies the HOV attributes  1231  of adjacent links corresponding to the current time, but the present invention is not limited thereto. According to a navigation device  1000  of a second embodiment of the second aspect of the present invention, the attributes  1231  of HOV lanes are identified based on expected arrival times to adjacent links. Referring to  FIG. 20 , operation of the navigation device  1000  according to the second embodiment of the second aspect of the present invention is described. 
         [0163]      FIG. 20  is a flow chart illustrating target link extraction processing performed by the navigation device  1000  according to the second embodiment. In the second embodiment, processing different to that of the first embodiment is executed only in Steps S 1033  and S 1034 . Therefore, the description of the types of processing similar to those of the first embodiment is omitted. Further, the flow illustrated in  FIG. 20  starts when the navigation device  1000  is activated. 
         [0164]    In Step S 1033  of  FIG. 20 , when the own vehicle is qualified for traveling HOV lanes (Yes in Step S 1032 ), the HOV entrance guiding unit  1109  examines, for links which are connected to the link on which the own vehicle is located and are within a predetermined range, the HOV attributes  1231  corresponding to the expected arrival times (Step S 1033 ). Specifically, the HOV entrance guiding unit  1109  refers to link travel time  1225  of the link table  1200 , and calculates expected arrival times to links which are connected to the link on which the own vehicle is located and are within 5 km from the own vehicle position, for example. Then, the HOV entrance guiding unit  1109  examines the attributes  1231  of the links at the calculated expected arrival times to the links. On the other hand, when the own vehicle is not qualified for traveling HOV lanes (No in Step S 1002 ), the HOV entrance guiding unit  1109  ends the target link extraction processing. 
         [0165]    The HOV entrance guiding unit  1109  examines the attributes  1231  of the links (Step S 1033 ), extracts a link for which “YES” is registered in the attribute  1231  corresponding to the time of day  1232  including the expected arrival time, and stores the extracted link in the guide target link table  1250  (Step S 1034 ). 
         [0166]    Note that, also in the second embodiment of the second aspect of the present invention as described above, the HOV entrance guiding processing is executed as in the first embodiment of the second aspect of the present invention. 
         [0167]    As described above, according to the second embodiment of the second aspect of the present invention, in determining whether or not the link is a target HOV lane, the expected arrival times to the links are used. The navigation device determines whether or not each link is an HOV lane based on the HOV attributes of the links identified as described above. Therefore, according to the second embodiment of the present invention, whether or not the link is an HOV lane can determined at higher accuracy to provide guidance as to the HOV lane. 
         [0168]    Alternatively, in a modified example of the present invention, in the first embodiment or the second embodiment of the second aspect of the present invention described above, the attribute  1231  of the link may be determined again with respect to the time immediately before the guidance as to an HOV lane is provided. Specifically, when the own vehicle reaches at a point which is 1 km before the link identified as an HOV lane, the navigation device  1000  refers again to the time of day  1232  contained in the attribute  1231  of the link. Then, at the time point when the own vehicle is at 1 km before the link, the navigation device  1000  determines whether or not the attribute  1231  of the link is an HOV lane. In a case where the result of the determination is that the link is not an HOV lane, the navigation device  1000  cancels the guidance as to the entrance of the HOV. On the other hand, in a case where the link is an HOV lane, when the own vehicle position reaches at a point which is 500 m before the link, the navigation device  1000  starts the guidance as to the entrance of the HOV. Note that, in a case where a link for which the attribute  1231  is determined again is found that the link is not an HOV lane any more, the link may be deleted from the guide target link table  1250 . 
         [0169]    According to the modified example described above, for a link that is once identified as the HOV lane, it is determined again whether or not the link is a target HOV lane immediately before the link, and hence the determination can be performed at higher accuracy to provide guidance as to the entrance of the HOV lane. For example, there may be a case where the attribute of the link changes before the own vehicle reaches the link originally identified as a target HOV lane due to a traffic jam or the like. However, according to the modified example of the second aspect of the present invention, it may be reexamined whether or not the link is an HOV lane immediately before the link, and hence guidance as to the entrance of the HOV lane can be performed at higher accuracy. 
       REFERENCE SIGNS LIST 
       [0170]      100 ,  1000  . . . navigation device;  1 ,  1001  . . . processing unit;  2 ,  1002  . . . display;  3 ,  1003  . . . storage unit;  4 ,  1004  . . . voice input/output unit;  5 ,  1005  . . . input unit;  6 ,  1006  . . . ROM device;  7 ,  1007  . . . vehicle speed sensor;  8 ,  1008  . . . gyro sensor;  9 ,  1009  . . . GPS receiver;  10 ,  1010  . . . FM multiplex broadcasting receiver;  11 ,  1011  . . . beacon receiver;  12 ,  1012  . . . camera;  13 ,  1013  . . . in-vehicle network communication unit