Patent Publication Number: US-2022212689-A1

Title: Display Control Method and Display Control Device

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority to and the benefit of Japanese Application Patent Serial No. 2019-092485, filed May 15, 2019, the entire disclosure of which is hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a display control method and a display control device. 
     BACKGROUND 
     Conventionally, a display control device has been disclosed, which displays information to be visually recognized by a driver on a display (for example, Japanese Unexamined Patent Application Publication No. 2015-11458). Japanese Unexamined Patent Application Publication No. 2015-11458 discloses contents of displaying, on a head-up display device, a superimposed display image showing a travel route when a lane change is performed by a control system. Further, Japanese Unexamined Patent Application Publication No. 2015-11458 discloses that the progress of a lane change is indicated in the travel route shown in the superimposed display image. 
     SUMMARY 
     If complicated automatic driving such as a lane change is performed, the control performed by a control system includes a plurality of processes. Therefore, there is a requirement for the driver to be able to perceive which of the processes of the control the driver is in. According to the method disclosed in Japanese Unexamined Patent Application Publication No. 2015-11458, it is possible to perceive a change in the travelling position of a host-vehicle, but it is not possible to perceive which of the processes of the control the driver is in. 
     The present invention is made in view of the above described problems, and an object of the present invention is to provide a display control method, and a display control device in which a driver can perceive a process of the control performed by a control system. 
     In a display control method according to one aspect of the present invention, if a control system proposes a lane change to a driver of a host-vehicle, an image showing an arrow is displayed on a display, and a display method for the image showing the arrow is switched depending on a plurality of processes in the control performed by the control system. 
     According to the present invention, a driver can perceive the state of the control performed by the control system to change a lane. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram for showing a control system applied with a display control device according to the present embodiment; 
         FIG. 2  is an explanatory diagram for schematically showing a scene ahead of a driver&#39;s seat of a host-vehicle; 
         FIG. 3  is an explanatory diagram for explaining a first information image, and a second information image; 
         FIG. 4  is an explanatory diagram for showing a series of movements from a third lane to an exit path of a host-vehicle in a situation where an automatic lane change is performed along a route; 
         FIG. 5A  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change is performed along a route; 
         FIG. 5B  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change is performed along a route; 
         FIG. 5C  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change is performed along a route; 
         FIG. 5D  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change is performed along a route; 
         FIG. 5E  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change is performed along a route; 
         FIG. 5F  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change is performed along a route; 
         FIG. 5G  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change is performed along a route; 
         FIG. 5H  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change is performed along a route; 
         FIG. 5I  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change is performed along a route; 
         FIG. 6  is an explanatory diagram for showing a series of movements from a first lane to a second lane of a host-vehicle in a situation where an automatic lane change proposed by a driver is performed; 
         FIG. 7A  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change proposed by a driver is performed; 
         FIG. 7B  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change proposed by a driver is performed; 
         FIG. 7C  is an explanatory diagram for showing an example of a first information image, and a second information image displayed, if an automatic lane change proposed by a driver is performed; 
         FIG. 8A  is an explanatory diagram for showing an example of a first information image, and a second information image; and 
         FIG. 8B  is an explanatory diagram for showing an example of a first information image, and a second information image. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment of the present invention will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals, and description thereof is omitted. 
     A display control device according to the present embodiment will be described by applying the display control device to a control system (a vehicle control system). The control system controls the behavior of a host-vehicle to perform automatic driving. Automatic driving means, for example, a state in which at least one of actuators, such as a brake, an accelerator, and a steering is controlled without an operation by an occupant. Therefore, other actuators may be actuated through the operation by the occupant. The automatic driving may be a state in which any control such as acceleration/deceleration control and lateral position control is performed. Further, in the present embodiment, manual driving means, for example, a state in which the occupant operates the brake, accelerator, and steering. The host-vehicle may be capable of switching between automatic driving and manual driving. 
     An example of automatic driving is an automatic lane change. An automatic lane change means that the control system controls the behavior of the host-vehicle so that the host-vehicle changes a lane from a host-vehicle lane on which the host-vehicle travels to either one of the right and left adjacent lanes adjacent to the host-vehicle lane. 
     A configuration of the control system will be described with reference to  FIGS. 1 and 2 . The control system includes a controller  10 , a host-vehicle position estimating device  20 , a map acquisition device  21 , a surrounding information detection device  22 , a vehicle speed sensor  23 , a steering switch  24 , a touch sensor  25 , and a winker switch  26 . Further, the control system includes a steering actuator  30 , an accelerator pedal actuator  31 , and a brake actuator  32 . Still further, the control system includes a meter display  35  and a head-up display  40 . 
     In the interior of the host-vehicle applied with the control system, a steering  1  is arranged ahead of a driver, and an instrument panel  3  is arranged ahead of the steering  1 . The instrument panel  3  is provided with a meter unit  5  for displaying, to the driver, a meter of the host-vehicle. A windshield  4  is arranged ahead of the instrument panel  3 . 
     The controller  10  is a general-purpose microcomputer including a CPU (a central processing unit), a memory, and an input/output unit. The microcomputer is installed with a computer program (a display control program and a control program) for causing the microcomputer to function as a display control device, and the control system. By executing the computer program, the microcomputer functions as a plurality of information processing circuits in the control system. The present embodiment shows an example in which the software implements the plurality of information processing circuits in the control system. However, it is also possible to configure the information processing circuits by preparing dedicated hardware for performing each information process described later. Further, the plurality of information processing circuits may be constituted by individual hardware. Details of the plurality of information processing circuits of the controller  10  will be described later. 
     The host-vehicle position estimating device  20  measures position information of the host-vehicle by using a position estimation technique such as GPS (global positioning system) and odometry. The host-vehicle position estimating device  20  measures an absolute position of the host-vehicle, that is, a position of the host-vehicle relative to a predetermined reference point, a vehicle speed, an acceleration, a steering angle, and an attitude of the host-vehicle by using various types of sensors and the like. The host-vehicle position estimating device  20  includes sensor for acquiring the behavior of the host-vehicle, such as a GPS receiver, inertial navigation equipment, sensors provided to a brake pedal and an accelerator pedal, a wheel speed sensor and a yaw rate sensor, a laser radar, a camera, and the like. The host-vehicle position estimating device  20  outputs the measured position information of the host-vehicle to the controller  10 . 
     The map acquisition device  21  acquires map information showing a structure of a road on which the host-vehicle travels. The map information acquired by the map acquisition device  21  includes information on a road structure such as an absolute position on each lane, the relationship on how lanes are connected, and the relationship on relative positions, traffic rules, road signs, and the like. The map acquisition device  21  may have a map database storing the map information, or alternatively may acquire the map information from an external map data server by cloud computing. Further, the map acquisition device  21  may acquire the map information by using the vehicle-to-vehicle communication or vehicle-to-road communication. The map acquisition device  21  outputs the acquired map information to the controller  10 . 
     The surrounding information detection device  22  includes a plurality of different kinds of object detection sensors mounted on the host-vehicle. The object detection sensors are, for example, laser range finders, laser radars, millimeter wave radars, cameras or the like. The surrounding information detection device  22  detects an object around the host-vehicle by using the object detection sensors. The surrounding information detection device  22  detects moving objects including another vehicle, a motorcycle, a bicycle, and a pedestrian, and stationary objects including a parked vehicle. For example, the surrounding information detection device  22  detects the positions, attitudes (yaw angles), sizes, speeds, accelerations, jerks, decelerations, and yaw rates of the moving object and the stationary object relative to the host-vehicle. The surrounding information detection device  22  may acquire surrounding information using the vehicle-to-vehicle communication or vehicle-to-road communication. The surrounding information detection device  22  outputs the detected information to the controller  10 . 
     The vehicle speed sensor  23  detects the vehicle speed of the host-vehicle. The vehicle speed sensor  23  outputs the detected vehicle speed of the host-vehicle to the controller  10 . 
     The steering switch  24  outputs an operation signal according to an operation by a driver. The steering switch  24  is provided to the steering  1 . The steering switch  24  outputs, to the controller  10 , the operation signal according to the operation by the driver. 
     The touch sensor  25  is provided to the steering  1 , and detects that the driver&#39;s hands have touched the steering  1 . As the touch sensor  25 , a capacitance type sensor for detecting a change in the capacitance can be used. If the driver&#39;s hands touch the steering  1 , the touch sensor  25  outputs a predetermined detection signal to the controller  10 . 
     The winker switch  26  outputs an actuation signal for actuating a winker (a direction indicator)  34 , and is operated by the driver. After being operated by the driver, the winker switch  26  outputs the actuation signal of the winker  34  to the controller  10 . 
     The steering actuator  30  controls a steering angle of the steering  1 . The controller  10  controls the steering actuator  30 . 
     The accelerator pedal actuator  31  controls the stepping amount of an accelerator pedal. The controller  10  controls the accelerator pedal actuator  31 . 
     The brake actuator  32  adjusts the stepping amount of the brake pedal. The controller  10  controls the brake actuator  32 . 
     The meter display  35  is arranged to the meter unit  5 . The meter display  35  displays a predetermined image such that the driver can visually recognize the image. The driver can recognize various pieces of information from the image displayed on the meter display  35 . The meter display  35  is formed of, for example, a liquid crystal panel. The image displayed on the meter display  35  is controlled by the controller  10 . 
     The meter display  35  displays an image showing a meter of the host-vehicle. The image showing the meter includes a tachometer image  36  showing a tachometer, and a speedometer image  37  showing a speedometer. The tachometer image  36  is displayed in a left area of the entire area of the meter display  35 . The speedometer image  37  is displayed in a right area of the entire area of the meter display  35 . 
     The meter display  35  displays a second information image  38  showing information notified to the driver by the control system. The second information image  38  is displayed in a central area of the entire area of the meter display  35 . That is, the second information image  38  is displayed at a space between the tachometer image  36 , and the speedometer image  37 . 
     The tachometer and the speedometer may be formed of analog meters, and the meter display  35  may display only the second information image  38 . 
     The head-up display  40  is arranged in the instrument panel  3 . The head-up display  40  displays a predetermined image such that the driver can visually recognize the image by a remote display using a virtual image. The display light emitted from the head-up display  40  is projected on the windshield  4  through an opening (not shown) provided to the instrument panel  3 . The display light is reflected by the windshield  4  to reach the eyepoint of the driver. This causes the driver to visually recognize the virtual image at the outside of the windshield  4 . In this way, the head-up display  40  emits the image toward the windshield  4 , and displays a virtual image obtained by the emitted image, such that the virtual image is superimposed on the scene ahead of the host-vehicle. 
     The head-up display  40  displays a first information image  41  showing information notified to the driver by the control system. The driver can simultaneously visually recognize the first information image  41  displayed by the head-up display  40 , and the scene ahead of the host-vehicle viewable through the windshield  4 . 
     With reference to  FIG. 3 , the first information image  41  displayed on the head-up display  40 , and the second information image  38  displayed on the meter display  35  will be described. 
     The first information image  41  is mainly composed of a preceding vehicle icon  41   a,  a first character string  41   b,  a mode display icon  41   c,  a first lane marker icon  41   d,  and an arrow icon  41   e.    
     The preceding vehicle icon  41   a  is a figure showing a preceding vehicle traveling on the same lane as the host-vehicle. 
     The first character string  41   b  includes one or more characters such as Hiragana characters, Chinese characters, numbers and symbols, and is, for example, a sentence. Further, the first character string  41   b  may include emoji (a pictogram) that plays the same role as the character. 
     The first character string  41   b  indicates contents notified to the driver by the control system. The contents of the first character string  41   b  may be the contents of a request from the control system, for example, an operation instruction to the driver to perform an automatic lane change or the like. Further, the contents of the first character string  41   b  may be control contents of what the control system desires to perform, for example, an automatic lane change to be performed. That is, the control system uses the first character string  41   b  to notify the driver of the request from the control system, or what the control system desires to perform. The first character string  41   b  has the relationship to be the same as a part of the second character string  38   b  which will be described later. 
     The first character string  41   b  is arranged above the preceding vehicle icon  41   a.  More specifically, the first character string  41   b  is arranged at the uppermost position among positions of elements forming the first information image  41 . 
     The mode display icon  41   c  is a figure indicating whether a mode is a hands-off mode or a hands-on mode. The hands-off mode is a mode (a first mode) in which the driver can release his or her hands from the steering  1  during automatic driving. On the other hand, the hands-on mode is a mode (a second mode) in which the driver needs to slightly touch the steering  1  with his or her hands during automatic driving. The mode display icon  41   c  has two kinds of figures that are a first steering figure and a second steering figure. The first steering figure shows only the steering, and the second steering figure shows the steering and the driver&#39;s hands slightly touching the steering. The first steering figure is used if the current mode is the hands-off mode. The second steering figure is used if the current mode is the hands-on mode. The first steering figure is displayed in blue, for example, and the second steering figure is displayed in green (only a steering portion), for example. 
     The first lane marker icon  41   d  is a figure showing left and right lane markers indicating boundaries of the host-vehicle lane. The left lane marker indicated in the first lane marker icon  41   d  indicates a boundary between the host-vehicle lane, and an adjacent lane or a road shoulder adjacent to the left side of the host-vehicle lane. Similarly, the right lane marker indicated in the first lane marker icon  41   d  indicates a boundary between the host-vehicle lane, and an adjacent lane or a road shoulder adjacent to the right side of the host-vehicle lane. 
     The arrow icon  41   e  is an arrow for guiding an automatic lane change. The arrow icon  41   e  has a shape that bends in the middle from a base end side of the arrow (a lower side of the figure) to a tip side of the arrow (an upper side of the figure). Further, the arrow icon  41   e  extends from the host-vehicle lane to the adjacent lane across the first lane marker icon  41   d . That is, the arrow icon  41   e  schematically shows a state in which the host-vehicle makes a lane change by an automatic lane change, and guides an automatic lane change. 
     The first information image  41  shows a travelling state of a vehicle ahead of the host-vehicle with the preceding vehicle icon  41   a  and the first lane marker icon  41   d.  The first information image  41  is generated so as to represent the travelling state of the vehicle ahead of the host-vehicle, when the driver looks in a forward direction. 
     In the first information image  41 , the travelling state of the vehicle ahead of the host-vehicle is shown two-dimensionally. This is because the first information image  41  is displayed on the head-up display  40 . That is, by using a two-dimensional representation, the amount of information is limited, and the visibility of the first information image  41  is enhanced. 
     The first information image  41  is generated at a predetermined timing, and each time the new first information image  41  is generated, the first information image  41  displayed on the head-up display  40  is updated. 
     The first information image  41  does not need to always include all of the preceding vehicle icon  41   a,  the first character string  41   b,  the mode display icon  41   c,  the first lane marker icon  41   d,  and the arrow icon  41   e.  The first information image  41  may include some or all of the preceding vehicle icon  41   a,  the first character string  41   b,  the mode display icon  41   c,  the first lane marker icon  41   d,  and the arrow icon  41   e.    
     A real travelling state of an actually traveling host-vehicle is reflected in the travelling state of the vehicle ahead of the host-vehicle shown in the first information image  41 . Therefore, if the preceding vehicle is not present actually, the first information image  41  does not include the preceding vehicle icon  41   a.    
     The control contents of the control system are reflected in the first character string  41   b  and the arrow icon  41   e.  That is, if there is no request from the control system, the first information image  41  does not include the first character string  41   b  and the arrow icon  41   e.    
     The second information image  38  is mainly composed of a host-vehicle icon  38   a,  a second character string  38   b,  a second lane marker icon  38   c,  and a surrounding vehicle icon  38   d.    
     The host-vehicle icon  38   a  is a figure indicating the host-vehicle. 
     The second character string  38   b  includes one or more characters such as Hiragana characters, Chinese characters, numbers and symbols, and is, for example, a sentence. Further, the second character string  38   b  may include emoji (a pictogram) that plays the same role as the character. 
     Similarly to the first character string  41   b,  the second character string  38   b  indicates the contents notified to the driver by the control system. Specifically, the second character string  38   b  includes the first character string  41   b  and another character string (a third character string). The contents of the third character string are the reason why the first character string  41   b  is notified. That is, the control system uses the second character string  38   b  to notify the driver of the request from the control system, or what the control system desires to perform, and the reason thereof. The second character string  38   b  has a larger amount of information than the first character string  41   b  in that the second character string  38   b  includes the third character string, in addition to the first character string  41   b.    
     In this way, the second character string  38   b  includes the first character string  41   b.  The inclusion of the first character string  41   b  in the second character string  38   b  does not mean that the element (the first character string  41   b ) displayed on the first information image  41  is regarded as a part of the second character string  38   b.  Instead of the above, the above inclusion means that the second character string  38   b  includes a character string in which a string of characters is the same as the first character string  41   b.  However, the second character string  38   b  described above is merely an example, and may be composed of any characters without being restricted by such conditions. 
     The second character string  38   b  is positioned below the host-vehicle icon  38   a.  In other words, the second character string  38   b  is arranged at the lowermost position among positions of the elements forming the second information image  38 . 
     The second lane marker icon  38   c  is a figure indicating lane markers showing boundaries of one or more lanes in the road on which the host-vehicle travels. 
     The surrounding vehicle icon  38   d  is a figure showing a surrounding vehicle traveling around the host-vehicle. The surrounding vehicle includes the preceding vehicle, and an adjacent vehicle traveling on the adjacent lane. 
     The second information image  38  shows travelling states of the host-vehicle, and a vehicle around the host-vehicle with the host-vehicle icon  38   a,  the second lane marker icon  38   c,  and a surrounding vehicle icon  38   d.  The surroundings of the host-vehicle include each of a space in a forward direction of the host-vehicle, spaces in left and right lateral directions of the host-vehicle, and a space in a backward direction of the host-vehicle. The second information image  38  is generated so as to represent the travelling state of the vehicle around the host-vehicle, when the host-vehicle is viewed from positions above and behind the host-vehicle. It is enough if the viewpoint showing the travelling state is at least above the host-vehicle, because the purpose is to perceive the travelling state of the vehicle around the host-vehicle 
      In the second information image  38 , the travelling state of the vehicle around the host-vehicle is shown three-dimensionally. The use of the three-dimensional representation further increases the amount of information than the two-dimensional representation. Accordingly, the second information image  38  can deliver more various pieces of information to the driver than the first information image  41 . 
     The second information image  38  is generated at a predetermined timing, and each time the new second information image  38  is generated, the second information image  38  displayed on the meter display  35  is updated. 
     The second information image  38  does not need to always include all of the host-vehicle icon  38   a,  the second character string  38   b,  the second lane marker icon  38   c,  and the surrounding vehicle icon  38   d.  The second information image  38  may include a part or all of the host-vehicle icon  38   a,  the second character string  38   b,  the second lane marker icon  38   c , and the surrounding vehicle icon  38   d.    
     The real travelling state of the actually traveling host-vehicle is reflected in the travelling state of the vehicle around the host-vehicle shown by the second information image  38 . Therefore, if the surrounding vehicle is not present actually, the second information image  38  does not include the surrounding vehicle icon  38   d.  Further, the second lane marker icon  38   c  corresponds to the number of lanes in the road on which the host-vehicle actually travels. 
     The control contents of the control system are reflected in the second character string  38   b.  That is, if there is no request from the control system, the second information image  38  does not include the second character string  38   b.    
     Referring again to  FIG. 1 , the controller  10  will be described in detail. The controller  10  includes, as the plurality of information processing circuits, a route generation unit  11 , an automatic traveling processing unit  12 , a vehicle control unit  13 , an image generation unit  14 , a display control unit  15 , a speaker control unit  16 , and a winker control unit  17 . 
     The route generation unit  11  generates a route to a destination preset by the driver. The route generation unit  11  outputs the generated route to the automatic traveling processing unit  12 . The route generation unit  11  may acquire a route generated by an external device. 
     The automatic traveling processing unit  12  performs various processes necessary for performing an automatic lane change. An automatic lane change includes a state of a system proposal in which the automatic traveling processing unit  12  (the control system) makes the proposal to the driver to perform an automatic lane change, and a state of a driver proposal in which an automatic lane change is performed in response to the reception of the proposal made by the driver. 
     An automatic lane change proposed by the system occurs, if it is determined that a lane change is necessary to overtake the preceding vehicle. In addition to the above, an automatic lane change proposed by the system occurs, if it is determined that a lane change is necessary to maintain the route generated by the route generation unit  11 . On the other hand, an automatic lane change proposed by the driver occurs, if the driver operates the winker switch  26  in a direction of a lane to which the driver desires to move. 
     The automatic traveling processing unit  12  calculates a position of the host-vehicle, a position of the surrounding vehicle, a relative speed between the host-vehicle and the preceding vehicle, and the like based on pieces of information output by the host-vehicle position estimating device  20 , the map acquisition device  21 , the surrounding information detection device  22 , and the vehicle speed sensor  23 . The automatic traveling processing unit  12  performs necessary calculations based on the position of the host-vehicle, the position of the surrounding vehicle, the relative speed between the host-vehicle and the preceding vehicle, the route generated by the route generation unit  11 , and the like. The calculations made by the automatic traveling processing unit  12  also use pieces of information output by the steering switch  24 , the touch sensor  25 , and the winker switch  26 . Further, the automatic traveling processing unit  12  outputs control commands necessary for an automatic lane change, and processes associated therewith to the vehicle control unit  13 , the image generation unit  14 , the display control unit  15 , the speaker control unit  16 , and the winker control unit  17 . 
     The vehicle control unit  13  controls the steering actuator  30  and the like in response to the control command from the automatic traveling processing unit  12 . The steering actuator  30  or the like operates in accordance with the control by the vehicle control unit  13 . Accordingly, the behavior of the host-vehicle is controlled, and this enables an automatic lane change to be performed. 
     The image generation unit  14  generates the first information image  41  and the second information image  38 . The first information image  41  is generated so as to represent the travelling state of the vehicle ahead of the host-vehicle based on pieces of information output by the host-vehicle position estimating device  20 , the map acquisition device  21 , the surrounding information detection device  22 , and the vehicle speed sensor  23 . Similarly, the second information image  38  is generated so as to represent the travelling state of the vehicle around the host-vehicle based on the pieces of information output by the host-vehicle position estimating device  20 , the map acquisition device  21 , the surrounding information detection device  22 , and the vehicle speed sensor  23 . 
     In addition, the image generation unit  14  generates the first information image  41  so as to include the first character string  41   b  based on the control command from the automatic traveling processing unit  12 , that is, information to be notified to the driver. Similarly, the image generation unit  14  generates the second information image  38  so as to include the second character string  38   b  based on the control command from the automatic traveling processing unit  12 , that is, the information to be notified to the driver. 
     The display control unit  15  displays the first information image  41  generated by the image generation unit  14  on the head-up display  40 . Further, the display control unit  15  displays the second information image  38  generated by the image generation unit  14  on the meter display  35 . 
     The speaker control unit  16  controls a speaker  33  in response to the control command from the automatic traveling processing unit  12 . By being controlled by the speaker control unit  16 , the speaker  33  outputs a notification sound to the driver. 
     The winker control unit  17  controls the winker  34  in response to the control command from the automatic traveling processing unit  12 . The control of the winker  34  by the winker control unit  17  actuate either left or right winker  34 . 
     A display control device according to the present embodiment includes the image generation unit  14  and the display control unit  15  among the plurality of information processing circuits constituting the controller  10 . A display control method according to the present embodiment includes various processes performed by the image generation unit  14  and the display control unit  15 . 
     Hereinafter, with reference to  FIG. 4 , descriptions will be given for flows of an automatic lane change proposed by the system by taking an example of a situation in which the route generated by the route generation unit  11  is maintained. In order to travel toward an exit path L 4  which branches from a main road, the host-vehicle  100  performs an automatic lane change from a third lane L 3  to a second lane L 2 , then from the second lane L 2  to a first lane L 1 , and then from the first lane L 1  to the exit path L 4 . 
     In an automatic lane change, control flows of the automatic traveling processing unit  12  include the following. 
     (1) The unit proposes an automatic lane change to the driver (a timing tb 1 ).
 
(2) The unit receives the driver&#39;s consent to perform an automatic lane change (a timing tb 2 )
 
(3) Prior to the start of an automatic lane change to the second lane L 2 , the winker  34  is actuated in a direction of a lane to which the host-vehicle is to be moved (a timing tb 3 ).
 
(4) The unit completes an automatic lane change to the second lane L 2  (first automatic lane change) (a timing tb 4 ).
 
(5) Prior to the start of an automatic lane change to the first lane L 1 , the winker  34  is actuated in a direction of a lane to which the host-vehicle is to be moved (a timing tb 5 ).
 
(6) The unit completes an automatic lane change to the first lane L 1  (second automatic lane change) (a timing tb 6 ).
 
(7) The unit determines that a distance between a branch point of the exit path L 4  and the host-vehicle  100  becomes a predetermined first distance (a timing tb 7 ).
 
(8) Prior to the start of an automatic lane change to the exit path L 4 , the winker  34  is actuated in a direction of the exit path L 4  to which the host-vehicle is to be travelled (a timing tb 8 ).
 
(9) The unit determines that the host-vehicle  100  has reached the branch point (a timing tb 9 ).
 
(10) The unit completes an automatic lane change to the exit path L 4  (third automatic lane change) (a timing tb 10 ).
 
     The control performed by the automatic traveling processing unit  12  in accordance with an automatic lane change, and the processes associated therewith includes a plurality of processes as described above. The first information image  41  displayed on the head-up display  40 , and the second information image  38  displayed on the meter display  35  are changed depending on each process of the control. 
     In an automatic lane change from the third lane L 3  to the exit path L 4 , the first information image  41  and the second information image  38  are changed depending on  10  processes. 
     In a process up to the timing tb 1 , the first information image  41  and the second information image  38  are mainly composed of contents indicating the travelling state (not shown). In a process from the timing tb 1  to before the timing tb 2 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state, and contents for proposing automatic lane change to the driver ( FIG. 5A ). In an process from the timing tb 2  to before the timing tb 3 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state, and contents indicating that the driver&#39;s consent for performing an automatic lane change is received ( FIG. 5B ). In a process from the timing tb 3  to before the timing tb 4 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state, and contents indicating that an automatic lane change is being performed ( FIG. 5C ). 
     In a process from the timing tb 4  to before the timing tb 5 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state, and contents for notifying a second automatic lane change ( FIG. 5D ). In a process from the timing tb 5  to before the timing tb 6 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state, and contents indicating that an automatic lane change is being performed ( FIG. 5E ). In a process from the timing tb 6  to before the timing tb 7 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state, and contents indicating that an automatic lane change is being continuously performed ( FIG. 5F ). 
     In a process from the timing tb 7  to before the timing tb 8 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state, and contents for notifying that the host-vehicle will travel to the exit path L 4  ( FIG. 5G ). In a process from the timing tb 9  to before the timing tb 10 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state, and contents indicating that an automatic lane change is being performed ( FIG. 5H ). In a process at or after the timing tb 10 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state ( FIG. 5I ). 
     As shown in  FIGS. 5A to 51 , the first information image  41  includes a preceding vehicle icon  41   a  and a first lane marker icon  41   d,  and shows a travelling state of a vehicle ahead of the host-vehicle. The second information image  38  includes a host-vehicle icon  38   a , a second lane marker icon  38   c,  and a surrounding vehicle icon  38   d,  and shows a travelling state of a vehicle around the host-vehicle. 
     Further, the first information image  41  includes a first character string  41   b,  and the second information image  38  includes a second character string  38   b.  An example of the first character string  41   b  and the second character string  38   b  will be described below. 
     In  FIG. 5B , the first character string  41   b  is a character string “(Pictogram) Travel toward an exit”. The pictogram in the first character string  41   b  corresponds to a pictogram marked on the steering switch  24 , and has the meaning to urge the operation of the steering switch  24  (the same applies hereinafter). The character string “(Pictogram) Travel toward an exit” indicate contents for proposing an automatic lane change to the driver. 
     In  FIG. 5B , the second character string  38   b  includes character strings “There will be an exit in a forward left direction”, “Confirm the safety”, and “(Pictogram) Travel toward an exit”. The character string “(Pictogram) Travel toward an exit” indicates contents for proposing an automatic lane change to the driver. The character string “There will be an exit in a forward left direction” indicates the reason why an automatic lane change is proposed. The character string “Confirm the safety” indicates the contents for proposing the safety confirmation to the driver. As described above, the second character string  38   b  includes the first character string  41   b  (“(Pictogram) Travel toward an exit”). In other words, the first character string  41   b  is the same as a part of the second character string  38   b.    
     Further, the first information image  41  includes the arrow icon  41   e.  Flows of the change in the arrow icon  41   e  will be described below. The arrow icon  41   e  is displayed at a timing at which an automatic lane change is proposed to the driver. 
     A display scene in  FIG. 5A  corresponds to a process from a timing when the driver is proposed to perform an automatic lane change to before a timing when the driver&#39;s consent for performing an automatic lane change is received (the timing tb 1  to the timing tb 2 ). The arrow icon  41   e  blinks in white. 
     The display scene shown in  FIG. 5B  corresponds to a process from a timing when the driver&#39;s consent for performing an automatic lane change is received to before a timing when the winker  34  is actuated in a direction of a lane to which the host-vehicle is to be moved (the timings tb 2  to the timing tb 3 ). The arrow icon  41   e  is lit in white. A lit area that is lit in white is in the arrow icon  41   e  which is a figure representing an arrow, and is dynamically changed in the figure. Specifically, in the arrow icon  41   e,  the lit area that is lit in the arrow gradually increases from a base end side of the arrow (a lower side of the figure) to a tip side of the arrow (an upper side of the figure). When the lit area reaches the tip of the arrow (that is, when the entire arrow is lit), the light of the entire arrow is turned off once. Then, a series of flows from the increase in the lit area in the arrow, to the light-on of the entire arrow, and then to the light-off of the entire arrow is repeated. In  FIG. 5B , a black-filled area indicated by the arrow icon  41   e  represents the lit area that is lit in white for convenience, and alternatively, a white-filled area represents a non-lit area for convenience (the same applies to  FIGS. 5D and 5G  described later). 
     The display scene in  FIG. 5C  corresponds to a process from the actuation of the winker  34  in a direction to which an automatic lane change is performed to before the completion of a first automatic lane change (the timing tb 3  to the timing tb 4 ). The arrow icon  41   e  is made to blink in green which is the same color as the display color of the mode display icon  41   c . In  FIG. 5C , the black-filled arrow icon  41   e  represents that the icon is made to blink in green for convenience (the same applies to  FIGS. 5E, 5H, and 7B , which will be described later). 
     The display scene in  FIG. 5D  corresponds to a process from the completion of a first automatic lane change to before the actuation of the winker  34  to perform a second automatic lane change (the timing tb 4  to the timing tb 5 ). The arrow icon  41   e  is lit in white. A lit area that is lit in white is in the arrow icon  41   e  which is a figure representing an arrow, and is dynamically changed. 
     The display scene in  FIG. 5E  corresponds to a process from the actuation of the winker  34  in a direction to which a second automatic lane change is performed to before the completion of a second automatic lane change (the timing tb 5  to the timing tb 6 ). In this case, the arrow icon  41   e  is made to blink in green. 
     The individual display scenes in  FIGS. 5G and 5H  relate to the third automatic lane change, and the details thereof are the same as those of the individual display scenes in  FIGS. 5D and 5E . A display scene shown in  FIG. 5F  indicates that an automatic lane change is being continuously performed during a time from the completion of a second automatic lane change to before the start of the third automatic lane change. 
     Further, the display scene in  FIG. 5I  corresponds to the completion of the third automatic lane change, that is, the completion of all automatic lane changes. The display of the arrow icon  41   e  is ended. 
     The image generation unit  14  and the display control unit  15  generate and display the first information image  41  and the second information image  38  as described above in response to the control command from the automatic traveling processing unit  12 . At this time, the display control unit  15  displays the first information image  41  and the second information image  38  such that the first character string  41   b  and the second character string  38   b  are displayed at the same time. 
     With reference to  FIG. 6 , flows of automatic lane change proposed by the driver will be described below. After the driver operates the winker switch  26 , the host-vehicle  100  performs an automatic lane change from the first lane L 1  to the second lane L 2 . 
     In an automatic lane change, control flows of the automatic traveling processing unit  12  include the following. (1) The driver operates the winker switch  26  (a timing ta 1 ). (2) An automatic lane change to the second lane L 2  is completed (a timing ta 2 ). 
     The control performed by the automatic traveling processing unit  12  in accordance with an automatic lane change and the processes associated therewith includes a plurality of processes as described above. The first information image  41  displayed on the head-up display  40 , and the second information image  38  displayed on the meter display  35  are changed depending on each process of the control. 
     In an automatic lane change from the first lane L 1  to the second lane L 2 , the first information image  41  and the second information image  38  are changed depending on three processes. 
     In a process up to the timing ta 1 , the first information image  41  and the second information image  38  are mainly composed of contents indicating the travelling state ( FIG. 7A ). In a process from the timing ta 1  to before the timing ta 2 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state, and contents indicating that an automatic lane change is being performed ( FIG. 7B ). In a process at or after the timing ta 2 , the first information image  41  and the second information image  38  are mainly composed of the contents indicating the travelling state ( FIG. 7C ). 
     As shown in  FIGS. 7A to 7C , the first information image  41  includes the preceding vehicle icon  41   a,  and the first lane marker icon  41   d,  and shows the travelling state of the vehicle ahead of the host-vehicle. Further, the second information image  38  includes the host-vehicle icon  38   a,  the second lane marker icon  38   c,  and the surrounding vehicle icon  38   d,  and shows the travelling state of the vehicle around the host-vehicle. 
     Further, the first information image  41  includes the first character string  41   b,  and the second information image  38  includes the second character string  38   b.  An example of the first character string  41   b  and the second character string  38   b  will be described below. 
     In  FIG. 7B , the first character string  41   b  is a character string “Confirm the safety”. The character string “Confirm the safety” indicates contents for urging the driver to confirm the safety. 
     In  FIG. 7B , the second character string  38   b  includes character strings “Confirm the safety” and “(Pictogram) Make cancellation by long press”. The character string “Confirm the safety” indicates the contents for urging the driver to confirm the safety. The character string “(Pictogram) Make cancellation by long press” indicates contents for notifying the driver of how to stop an automatic lane change. In this way, the second character string  38   b  includes the first character string  41   b  (“Confirm the safety”). In other words, the first character string  41   b  is the same as a part of the second character string  38   b.    
     Further, the first information image  41  includes the arrow icon  41   e.  The arrow icon  41   e  will be described below. The arrow icon  41   e  is displayed when the driver operates the winker switch  26 . 
     The display scene in  FIG. 7B  corresponds to a process from the operation of the winker switch  26  by the driver to before the completion of an automatic lane change (the timings ta 1  to the timing ta 2 ). The arrow icon  41   e  is made to blink in green. 
     The display scene shown in  FIG. 7C  corresponds to a case where an automatic lane change is completed. The display of the arrow icon  41   e  is ended. 
     Different forms of the second information image  38  will be described below. 
     The automatic traveling processing unit  12  performs the linkage control (navigation linkage control) for causing the host-vehicle to travel by linking with a route generated by the route generation unit  11 . The automatic traveling processing unit  12  performs the above described automatic lane change in the linkage control. However, when determining a predetermined condition, for example, a traffic congestion, the automatic traveling processing unit  12  prohibits the function of an automatic lane change. 
     In a case of a time period during which an automatic lane change can be performed, the second information image  38  has a form shown in  FIG. 8A . That is, the second information image  38  includes the second lane marker icon  38   c  (a first lane image) that has the host-vehicle lane on which the host-vehicle travels, and an adjacent lane that is adjacent to the host-vehicle lane. On the other hand, in a case of a time period during which an automatic lane change may not be performed, the second information image  38  has a form shown in  FIG. 8B . That is, the second information image  38  includes the second lane marker icon  38   c  (a second lane image) that only has the host-vehicle lane on which the host-vehicle travels. 
     As described above, in the display control method according to the present embodiment, when the control system proposes an automatic lane change to the driver of the host-vehicle, an image showing an arrow for guiding an automatic lane change (the arrow icon  41   e ) is displayed on the head-up display  40 , and a display method for the arrow icon  41   e  is switched in response to the plurality of processes in the control performed by the control system. 
     The driver can perceive the state of the control performed by the control system from the change in the display method for the arrow icon  41   e.  As a result, it is possible to provide a display that is easy for the driver to understand, and a display that provides a sense of security to the driver. 
     A first process of the plurality of processes in the display control method according to the present embodiment is from a time when the control system proposes an automatic lane change to the driver, to before a time when the control system receives the driver&#39;s consent for performing an automatic lane change. In the first process, the arrow icon  41   e  is made to blink. A second process of the plurality of processes in the display control method is from the time when the control system receives the driver&#39;s consent for performing an automatic lane change to before a time when the control system actuates the winker  34  in a direction to which an automatic lane change is performed. In the second process, the arrow icon  41   e  is changed such that a lit area increases from a base end side of the arrow to a tip side of the arrow. A third process of the plurality of processes in the display control method is from the time when the control system actuates the winker  34  in the direction to which an automatic lane change is performed, to before a time when an automatic lane change by the control system is completed. In the third process, the arrow icon  41   e  is made to blink. In the display control method, the display of the arrow icon  41   e  is ended, if an automatic lane change by the control system is completed. 
     A display mode of the arrow icon  41   e  is switched at a timing of the change from the first process to the second process. This enables the driver to understand that the control system has received the driver&#39;s consent. Further, the display mode of the arrow icon  41   e  is switched at a timing of the change from the second process to the third process. This enables the driver to perceive that an automatic lane change is started, that is, the control of the behavior of the host-vehicle is started. Further, the end of the display of the arrow icon  41   e  enables the driver to perceive that an automatic lane change by the control system is completed. 
     In the first and second processes in the display control method according to the present embodiment, the arrow icon  41   e  is displayed in a first display color. In the third process, the arrow icon  41   e  is displayed in a second display color different from the first display color. 
     At a timing when the behavior control of the host-vehicle is started, the display color of the arrow icon  41   e  is switched. Accordingly, the driver can perceive in advance that the behavior control of the host-vehicle is started from the display color of the arrow icon  41   e.    
     In the present embodiment, the first display color is a white color, and the second display color is a green color. The color is set to be the same as the color of the mode display icon  41   c  in the hands-on mode. This makes it possible to notify the driver of the fact that the driver needs to slightly touch the steering  1  with his or her hands in an easy to understand way when the behavior control of the host-vehicle is started. 
     Further, in the display control method according to the present embodiment, the proposal of an automatic lane change by the control system may include the first automatic lane change, and the second automatic lane change following the first automatic lane change. In this case, a fourth process in the display control method is from a time when the first automatic lane change by the control system is completed to before a time when the control system actuates the winker  34  for a second automatic lane change. In the fourth process, the arrow icon  41   e  is changed such that the lit area increases from the base end side of the arrow to the tip side of the arrow. A fifth process in the display control method is from the time when the control system actuates the winker  34  for a second automatic lane change to before a time when a second automatic lane change by the control system is completed. In the fifth process, the arrow icon  41   e  is made to blink. 
     The driver&#39;s consent is already received prior to the first automatic lane change, and therefore, the driver&#39;s consent is not required in a second automatic lane change. This enables control specifications with less loads on the driver. By omitting a state in which the arrow icon  41   e  is made to blink in white, the driver can understand, from the display, the process of the control in which the driver&#39;s consent to perform a second automatic lane change is omitted. 
     Further, in the display control method according to the present embodiment, the arrow icon  41   e  is displayed, if the control system determines that the driver has actuated the winker  34  in order to cause the control system to start an automatic lane change. In the display control method, the arrow icon  41   e  is displayed in a blinking state during a time period from a time when the driver actuates the winker  34  to before a time when an automatic lane change by the control system is completed. 
     If an automatic lane change is performed based on the driver&#39;s intension, it is clear that the driver intends to perform an automatic lane change, and therefore, the control process is also simplified. This makes it possible to guide an automatic lane change with a simple display method. 
     Further, in the display control method according to the present embodiment, if a condition is satisfied in which an automatic lane change can be performed, the first lane image (the second lane marker icon  38   c ) is further displayed. The first lane image indicates the host-vehicle lane on which the host-vehicle travels, and the adjacent lane that is adjacent to the host-vehicle lane. Alternatively, in the display control method, if the condition is not satisfied in which an automatic lane change can be performed, the second lane image (the second lane marker icon  38   c ) indicating only the host-vehicle lane is further displayed. 
     The driver can determine whether the driver is in a situation to perform an automatic lane change from the displayed lane state. 
     The display control device according to the present embodiment includes the controller  10  that controls the head-up display  40  which can be visually recognized by the driver of the host-vehicle. If the control system proposes an automatic lane change to the driver of the host-vehicle, the controller  10  displays the arrow icon  41   e  representing the arrow for guiding an automatic lane change on the head-up display  40 , and switches the display method for the arrow icon  41   e  depending on the plurality of processes in the control performed by the control system. 
     The display control device according to the present embodiment has a technical feature corresponding to the display control method described above, and achieves the same effect as the display control method. 
     The present invention is not limited to the embodiment described above, and various modifications are possible without departing from the scope of the present invention. 
     For example, in the first image displayed on the head-up display, the vehicle icon may be a figure representing a vehicle, and is not limited to the figure representing the preceding vehicle. Further, in the second image displayed on the meter display, the vehicle icon may be a figure representing a vehicle, and is not limited to the figure representing the host-vehicle. 
     The arrow icon is displayed on the head-up display, and the control according to the present embodiment is applied to the arrow icon. However, the similar control may be performed with the meter display. Switching between the first lane image and the second lane image may be applied to the display of the head-up display. 
     REFERENCE SIGNS LIST 
       10 . Controller 
       11 . Route generation unit 
       12 . Automatic traveling processing unit 
       13 . Vehicle control unit 
       14 . Image generation unit 
       15 . Display control unit 
       16 . Speaker control unit 
       17 . Winker control unit 
       20 . Host-vehicle position estimating device 
       21 . Map acquisition device 
       22 . Surrounding information detection device 
       23 . Vehicle speed sensor 
       24 . Steering switch 
       25 . Touch sensor 
       26 . Winker switch 
       30 . Steering actuator 
       31 . Accelerator pedal actuator 
       32 . Brake actuator 
       33 . Speaker 
       34 . Winker 
       35 . Meter display 
       40 . Head-up display