Information display method, device, and program for vehicle

Abstract

This information display device for a vehicle acquires the coordinates of an intersection at which a left or right turn is to be made according to route guidance to a destination, and displays an arrow-shaped guidance virtual image (24) at the coordinate position of the intersection so that the guidance virtual image (24) is superimposed, via an AR-HUD (1), on a forward scene viewed through a windshield (2). The display device determines whether the intersection is of a simple shape or a complicated shape according to a predetermined criterion, and, if the intersection is of a complicated shape, displays an intersection layout image (41, 42, 43) as a bird's-eye view in which the intersection is viewed from a second viewpoint (15A) higher than the viewpoint (15) of the driver before displaying the guidance virtual image (24).

Description

Vehicle information display method, device, and program

[0001] The present invention relates to a vehicle information display that uses an AR-HUD (Augmented Reality Head-Up Display) to display a virtual image superimposed on a real scene.

[0002] In recent years, HUDs (head-up displays), which project and display various information necessary while driving a vehicle onto the windshield in front of the driver's seat, have become increasingly popular. Furthermore, AR-HUDs (augmented reality head-up displays) are known as a more advanced version of HUD technology. AR-HUDs can superimpose virtual information (also called virtual objects or virtual images) made up of virtual images onto the real information visible through the windshield, reducing the need for the driver to move their viewpoint or focus as much as conventional HUDs, which display information on the glass surface of the windshield.

[0003] Virtual information can include a variety of things, one of which is route guidance display for turning right or left at an intersection, as described in Patent Document 1. For example, based on route guidance from a car navigation system, a virtual image such as an arrow indicating the direction of the road to turn right or left and proceed is displayed by the AR-HUD at a position that overlaps with the intersection in the real scene.

[0004] Here, most of the intersections for which route guidance is provided have simple shapes such as crossroads. However, occasionally, intersections with complex shapes exist. For example, there are five-way intersections where no straight roads exist, circular intersections known as roundabouts, and winding intersections where you must turn right and left in a crank-like pattern at short intervals. A roundabout is an intersection without traffic lights, where vehicles travel in one direction (clockwise in Japan) around a circular ring road, with multiple roads that serve as entrances and exits connected radially.

[0005] At such intersections with complex shapes, even if virtual images such as arrows for route guidance are displayed when a vehicle actually approaches the intersection, it is difficult for the driver to understand the layout of the intersection through which they will proceed, which can easily make the driver feel uneasy.

[0006] JP 2015-166230 A

[0007] This invention is an information display method for a vehicle, which displays a virtual image for vehicle route guidance on the coordinates of an intersection via the vehicle's AR-HUD, superimposed on the view ahead seen through the windshield. The method determines whether the next intersection at which the vehicle should change course is a simple intersection or a complex intersection according to predetermined criteria, and if it is a complex intersection, displays an intersection layout image representing the intersection layout on the road surface in front of the vehicle as a bird's-eye view seen from a second viewpoint position higher than the driver's viewpoint, before the vehicle approaches the intersection and the virtual image for route guidance is displayed on the intersection coordinates.

[0008] The intersection layout image is displayed only when the next intersection at which the driver should change lanes is a complex intersection. This intersection layout image allows the driver to grasp the overall layout of the intersection before the virtual image of the route guidance is displayed on the intersection's coordinates, making it easier to drive according to the route guidance. Furthermore, because the intersection layout is displayed as a bird's-eye view by the AR-HUD, it does not give the driver any sense of incongruity when superimposed on the road surface visible through the windshield, and also makes the intersection layout easier to understand.

[0009] 1. An explanatory diagram of the configuration of an information display device according to an embodiment. An explanatory diagram showing the relationship between the distance to an object and the look-down angle. An explanatory diagram showing an example of a virtual image for route guidance seen through the windshield. An explanatory diagram of a bird's-eye view. A plan view schematically showing a real five-way intersection. An explanatory diagram showing an example display of an intersection layout image of a five-way intersection seen through the windshield. An explanatory diagram showing an enlarged view of the display area of ​​FIG. 6. A plan view schematically showing a real roundabout. An explanatory diagram showing an example display of an intersection layout image of a roundabout seen through the windshield. An explanatory diagram showing an enlarged view of the display area of ​​FIG. 9. A plan view schematically showing a real double intersection where successive right and left turns are required. An explanatory diagram showing an example display of an intersection layout image of a double intersection seen through the windshield. An explanatory diagram showing an enlarged view of the display area of ​​FIG. 12. A flowchart showing the processing flow for displaying an intersection layout image and a virtual image for route guidance.

[0010] An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0011] FIG. 1 is an explanatory diagram showing the configuration of an information display device for a vehicle according to one embodiment. The vehicle according to this embodiment is a typical automobile equipped with an AR-HUD (Augmented Reality Head-Up Display) 1 in front of the driver's seat. The AR-HUD 1 displays virtual objects, i.e., virtual information, superimposed on real information visible through a windshield 2. In the present invention, any format may be used; for example, a projector may be provided below the windshield 2, and light reflected by the surface of the windshield 2 and reaching the driver's eyes generates a virtual image of the virtual information on a virtual focal plane located an appropriate distance (e.g., several meters) in front of the driver. The virtual information may include a virtual image indicating a right or left turn for route guidance to be displayed superimposed on an intersection, as described below, information from an advanced driver assistance system (ADAS), or appropriate information such as actual vehicle speed.

[0012] The AR-HUD 1 is controlled by a controller 3. That is, the controller 3 generates a virtual image and controls its display position. A car navigation system 4 using a GPS, which provides vehicle route guidance, is connected to the controller 3. The car navigation system 4 includes map information, which includes intersection information such as coordinate data of intersection nodes, the number of links connected to the nodes, and the direction of each link. If the intersection is a roundabout, the map information also includes information about the roundabout (e.g., the size of the circular road, the number and direction of radially connected roads, etc.). The car navigation system 4 also identifies the vehicle's position. The illustrated system further includes information acquisition devices such as a radar 5 and a camera 6 for detecting the positions of preceding vehicles, pedestrians, etc. Note that nodes are components that, together with links, constitute a road network on a digitized road map, and represent points such as intersections and other nodal points on a road network representation. A road network is formed by connecting nodes with links.

[0013] An information display device using the AR-HUD 1 according to one embodiment includes a viewpoint detection camera 7 that detects the driver's viewpoint position in order to optimize the position of the virtual image of the AR-HUD 1. The viewpoint detection camera 7 constitutes, for example, part of a driver monitoring system (DMS) that monitors the driver's condition. The viewpoint detection camera 7 is disposed, for example, near the upper edge of the windshield, facing the driver's head. The controller 3 processes images acquired by the viewpoint detection camera 7 to detect the driver's viewpoint position (i.e., the position of the driver's eyes). Note that the driver's viewpoint position may be detected without using a camera, and may be detected indirectly, for example, from the driver's seating position, driver height, or the like. The controller 3 corrects the position at which the virtual image, i.e., the object, is generated by the AR-HUD 1 according to the viewpoint position thus detected, so that the actual scene seen by the driver through the windshield 2 and the object of the AR-HUD 1 are properly superimposed.

[0014] The controller 3 is configured as a part of the functions of an in-vehicle computer system that performs various controls, and in a mode in which route guidance is provided by the car navigation system 4, it displays, via the AR-HUD 1, virtual images indicating right and left turns required for route guidance, virtual images indicating the destination, and the like. Furthermore, as will be described later, if the intersection is an intersection with a complex shape, an intersection layout image is displayed prior to displaying the virtual image for route guidance. The controller 3 performs operations such as obtaining the coordinates of the intersection via the car navigation system 4, obtaining information regarding the intersection layout, creating display data for the virtual image, calculating the distance between the vehicle and the intersection, and changing the display mode of the virtual image according to the distance between intersections.

[0015] Next, basic virtual information display by the AR-HUD 1 will be described using Figures 2 and 3. Figure 3 is a simplified explanatory diagram showing the view seen through the windshield 2 when the vehicle approaches a node, i.e., an intersection, where a left turn is to be made. A rectangular display area 21 of the AR-HUD 1 is present in a portion of the view through the windshield 2. The display area 21 is basically positioned directly in front of the driver. Note that the frame around the periphery of the display area 21 is not actually displayed, but is shown in the figure for illustrative purposes. Various virtual information required while driving is displayed in this display area 21 via the AR-HUD 1.

[0016] The display area 21 in the illustrated example is divided into an upper area 21A and a lower area 21B by a boundary line 22 defined by regulations. Note that the boundary line 22 is shown for illustrative purposes only and is not actually displayed. A virtual image 24 for route guidance is displayed in the upper area 21A as so-called specific information permitted by regulations. The display position and display form of the virtual image 24 displayed in the upper area 21A can change depending on the distance to the intersection, changes in the direction of travel within the intersection, etc. An intersection layout image, which will be described later, is also displayed in the upper area 21A.

[0017] In the lower region 21B below the boundary line 22, virtual images 23 (for convenience, referred to as fixed virtual images 23) of information other than the specific information, such as information related to ADAS such as hands-off driving and information related to speed limits, are displayed. For example, multiple fixed virtual images 23 are displayed in a horizontal row in the lower region 21B. The display positions of these fixed virtual images 23 within the lower region 21B are fixedly determined. Since these fixed virtual images 23 are not a main part of the present invention, their description will be omitted. Furthermore, the display examples of the speed limits and the like in the fixed virtual images 23 are not necessarily accurate.

[0018] When approaching an intersection where a right or left turn is required for route guidance, a virtual image 24 indicating the right or left turn is displayed in the upper area 21A as one piece of specific information. This image is superimposed on the real scene so as to appear at the intersection point (node) indicated by coordinates. The illustrated virtual image 24 is an example of a left turn, and has a form in which three arrowhead-shaped segments are arranged at intervals. For example, the central segment corresponds to the position of the intersection node. Therefore, the road in real space located to the left of this arrow-shaped virtual image 24 is the road onto which the left turn should be taken.

[0019] In the present invention, the virtual image indicating a right or left turn for route guidance is not limited to the form shown in the illustration, and may be in any form, such as a simple arrow.

[0020] In the AR-HUD 1, when a virtual object, i.e., a virtual image, is displayed by the AR-HUD 1, the driver perceives the distance to the object based on a look-down angle, which is a downward angle relative to a horizontal plane. FIG. 2 is an explanatory diagram of this look-down angle. The driver looks down on a real object (e.g., an intersection) 20 from a viewpoint 15, and the look-down angle α at this time is geometrically determined by the height H of the viewpoint 15 from the road surface and the distance x from the vehicle to the object 20. The plane labeled 16 in the figure indicates a virtual focal plane on which a virtual image is generated by the AR-HUD 1. This focal plane 16 is located outside the windshield 2, i.e., in front of the vehicle. A virtual object (e.g., the arrow-shaped virtual image 24 described above) is displayed on this focal plane 16 at a position that corresponds to the look-down angle α of the real object, allowing the driver to perceive the virtual object as being located on the coordinates of the real object.

[0021] Next, an intersection layout image display for a complex-shaped intersection, which is an object of the present invention, will be described. FIG. 5 is an explanatory diagram showing a plan view of a five-way intersection as an example of a complex-shaped intersection. The illustrated intersection has five roads, R1, R2, R3, R4, and R5, connected to a central intersection P1. The vehicle 31 is traveling on road R5, and based on the vehicle's straight-ahead direction, there are two roads R1 and R2 in the left-turn direction and two roads R3 and R4 in the right-turn direction. In one example, the road to be traveled according to route guidance provided by the car navigation system 4 is road R1, which is a left turn. When the vehicle approaches an appropriate distance from the intersection, the AR-HUD 1 displays a three-segment arrow-shaped virtual image 24 (for convenience, referred to as the guidance virtual image 24) indicating the route direction, as described in FIG. 3 . At the illustrated five-way intersection, adjacent to road R1, which is the road to be turned left, there is road R2, which also extends in the left-turn direction. Therefore, even if the arrow-shaped virtual guide image 24 is displayed at the intersection P1, it is difficult for the driver to distinguish whether the road R1 or the road R2 is the correct route, and misidentification of the route is likely to occur. In particular, misidentification is likely to occur when the driver approaches the intersection P1 without knowing that it is a five-way intersection.

[0022] Therefore, in one embodiment, if the intersection is a multi-junction with five or more roads and the angle θ between the correct road R1 to be traveled and the adjacent incorrect road R2 in the same direction is equal to or less than a threshold θT, a bird's-eye view intersection layout image is displayed before the display of the virtual guide image 24 is started (i.e., when the vehicle is relatively far from the intersection). Since misidentification is generally unlikely to occur if the directions of the two roads differ by 90° or more, the threshold θT is set to an appropriate value less than 90°. For example, the threshold θT can be set to 60°, 45°, 30°, etc.

[0023] FIG. 6 is an explanatory diagram showing an example of a display of a five-way intersection layout image 41 seen through the windshield 2, and FIG. 7 is an enlarged view of the display area 21 of the AR-HUD 1 in FIG. 6. The intersection layout image 41 mimics the layout of a real intersection, and the angles between adjacent roads (e.g., roads R1 and R2) are enlarged and highlighted to enable distinction between them. The intersection layout image 41 is displayed by the AR-HUD 1 as a bird's-eye view seen from a second viewpoint position higher than the driver's viewpoint 15 (see FIG. 2), superimposed on the road surface ahead of the vehicle. In one embodiment, the intersection layout image 41 is generated as a two-dimensional intersection layout image so as to appear as a bird's-eye view along a predetermined downward angle, and the two-dimensional intersection layout image is displayed as a virtual image on the virtual focal plane 16 (see FIG. 2) by the AR-HUD 1.

[0024] In one embodiment, the intersection layout image 41 is displayed on a virtual line that passes through the center of the vehicle and extends in the longitudinal direction. In another example, the intersection layout image 41 is displayed on a virtual line that passes through the driver's viewpoint 15 and extends in the longitudinal direction. Alternatively, the intersection layout image 41 is displayed on the center line of the horizontal angle of view of the display area 21. In other words, the intersection layout image 41 is displayed in a position that is easy for the driver to see, and is not necessarily displayed in the same direction as the actual intersection.

[0025] 7, in a preferred embodiment, the intersection layout image 41 includes a display of the road to be traveled (route display 41a). That is, in the intersection layout image 41, the area from the currently traveled road R5 to road R1 is displayed in different colors and brightness as the route display 41a. The black display in the figure is added merely for illustrative purposes. For example, the entire intersection layout image 41 is gray, and the route display 41a is a relatively bright blue.

[0026] FIG. 4 is an explanatory diagram of a bird's-eye view. It shows the driver's viewpoint 15 when the vehicle approaches a real intersection P within a certain distance (e.g., the distance at which the display of the virtual guide image 24 begins), a second viewpoint 15A that serves as the basis for the bird's-eye view, and a third viewpoint 15B that provides a planar view of the intersection P from directly above. The downward angle from the driver's viewpoint 15 when viewing the intersection layout on the road surface is relatively small. As a result, for example, a five-way intersection as shown in FIG. 5 appears flat. Therefore, even if the five-way intersection viewed from viewpoint 15 is graphically displayed, the layout of the five roads at the five-way intersection cannot be accurately understood. On the other hand, if the intersection layout viewed from the third viewpoint 15B directly above is graphically displayed, the shape of the five-way intersection itself can be understood, but it is not possible to immediately understand from which direction the vehicle 31 is approaching the graphically displayed five-way intersection.

[0027] In contrast to these, the intersection layout image 41 is displayed as a bird's-eye view seen from a second viewpoint 15A that is higher than the driver's viewpoint 15. Therefore, the display is seen from a larger angle of view than the angle of view seen from the driver's viewpoint 15, allowing the viewer to correctly understand the layout of the five-way intersection with five roads, and also to intuitively understand from which direction the vehicle 31 is approaching the five-way intersection.

[0028] The angle of view of the bird's-eye view is set within the range of, for example, 10° to 80°, preferably 20° to 70°, and more preferably 30° to 60°.

[0029] Next, an example of a roundabout as a complex intersection will be described with reference to FIGS. 8 to 10 . FIG. 8 is an explanatory diagram showing a plan view of an example roundabout. The illustrated roundabout is composed of a circular ring road RC surrounding a central island IL and four roads R11, R12, R13, and R14 radially connected to the ring road RC as entrances and exits to the ring road RC. In Japan, where people drive on the left side of the road, the ring road RC is a one-way road running clockwise (counterclockwise in countries where people drive on the right side of the road). In FIG. 8 , a vehicle 31 is traveling on road R11 and turns left from road R11 to enter the ring road RC. After traveling an appropriate angle on the ring road RC, the vehicle exits the ring road RC by turning left onto one of the target roads R12, R13, or R14. There is no need to stop temporarily when entering or exiting the ring road RC. The roundabout does not have traffic lights. The roads R11, R12, R13, and R14 connected to the ring road RC are, for example, two-lane roads with one lane on each side. They may also have multiple lanes on each side.

[0030] In such a roundabout, for example, even though the wide-area map shows the driver heading in the right direction, the driver is guided to make two left turns, one to enter the circular road RC and one to exit the circular road RC, which can be confusing for the driver. Therefore, as in the example of the five-way intersection, a bird's-eye view intersection layout image is displayed before the display of the virtual guide image 24 begins (i.e., before the driver actually approaches the roundabout).

[0031] FIG. 9 is an explanatory diagram showing an example of a display of an intersection layout image 42 of a roundabout as seen through the windshield 2, and FIG. 10 is an enlarged view of the display area 21 of the AR-HUD 1 in FIG. 9. The intersection layout image 42 mimics the layout of an actual roundabout and is appropriately designed (i.e., highlighted) to clearly show the multiple roads R11 to R14 extending radially. The intersection layout image 42 is displayed by the AR-HUD 1 as a bird's-eye view seen from a second viewpoint 15A (see FIG. 4 ) higher than the driver's viewpoint 15, as described above, superimposed on the road surface ahead of the vehicle. In one embodiment, the intersection layout image 42 is generated as a two-dimensional intersection layout image so as to appear as a bird's-eye view from a predetermined downward angle, and the two-dimensional intersection layout image is displayed as a virtual image on the virtual focal plane 16 (see FIG. 2 ) by the AR-HUD 1.

[0032] 7, in a preferred embodiment, the intersection layout image 42 includes an indication of the road to be traveled (route indication 42a). That is, in the intersection layout image 42, the area from the currently traveled road R11 to road R13 via the ring road RC is shown in different colors and brightness as the route indication 42a.

[0033] Next, with reference to Figures 11 to 13, an example of a complex-shaped intersection will be described, which is an intersection where two consecutive right and left turns are required at two points within a predetermined distance (hereinafter, for convenience, this will be referred to as a double intersection). Figure 11 is an explanatory diagram showing an example of a double intersection in plan view. The double intersection in the illustrated example has two roads R21 and R22 running along the direction of travel, and two intersections P1 and P2 formed by a road R23 that intersects these roads at right angles. The vehicle 31 is traveling on road R21, and according to route guidance, after making a right turn at intersection P1, it must immediately make a left turn at intersection P2.

[0034] At such double intersections, if the distance between the two intersections P1 and P2 is short, drivers are likely to be confused. Therefore, as in the case of five-way intersections and roundabouts, a bird's-eye view intersection layout image is displayed before the display of the virtual guide image 24 begins on the intersection P1.

[0035] FIG. 12 is an explanatory diagram showing an example of a display of an intersection layout image 43 of a double intersection as seen through the windshield 2, and FIG. 13 is an enlarged view of the display area 21 of the AR-HUD 1 in FIG. 12. The intersection layout image 43 mimics the layout of a real double intersection and is appropriately designed (i.e., highlighted) to clearly identify the roads R21, R22, and R23. The intersection layout image 43 is displayed by the AR-HUD 1 as a bird's-eye view seen from a second viewpoint 15A (see FIG. 4 ) higher than the driver's viewpoint 15, as described above, superimposed on the road surface ahead of the vehicle. In one embodiment, the intersection layout image 43 is generated as a two-dimensional intersection layout image so that it appears as a bird's-eye view from a predetermined downward angle, and the two-dimensional intersection layout image is displayed as a virtual image on the virtual focal plane 16 (see FIG. 2 ) by the AR-HUD 1.

[0036] 7, in a preferred embodiment, the intersection layout image 43 includes an indication of the road to be traveled (route indication 43a). That is, in the intersection layout image 43, the route that advances in a crank shape from the road R21 on which the vehicle is currently traveling is indicated in a different color or brightness as the route indication 43a.

[0037] 14 is a flowchart showing the process flow for displaying an intersection layout image in one embodiment. The process shown in this flowchart is repeatedly executed while route guidance is being provided by the car navigation system 4. In the first step 1, it is determined whether the distance L from the vehicle 31 to the next intersection (the intersection where a lane change is required) is equal to or less than a predetermined distance LB at which display of the intersection layout image should begin. If the result is NO, that is, if the distance is greater than the predetermined distance LB, the determination in step 1 is repeated until the predetermined distance LB is reached.

[0038] If it is determined in step 1 that the distance L is equal to or less than the predetermined distance LB, then in steps 2, 4, and 6, the next intersection is determined to be a simple intersection or a complex intersection according to predetermined criteria. First, in step 2, it is determined whether the next intersection is a complex intersection, such as a five-way or six-way intersection, where the angle θ between the road to be traveled and the adjacent road is equal to or less than the predetermined threshold θT, as described above. That is, whether the intersection is a complex intersection is determined based on the number of roads branching off from the intersection and the angle between the roads. If it is determined in step 2 that the next intersection is a predetermined multi-way intersection, for example, a five-way intersection, then the process proceeds to step 3, where an intersection layout image 41 simulating a real five-way intersection is generated as a bird's-eye view with a predetermined overhead angle. In a preferred embodiment, the intersection layout image 41 of the entire five-way intersection is generated by appropriately combining multiple images of road elements corresponding to individual roads (images of road elements in bird's-eye views).

[0039] If the determination in step 2 is NO, then in step 4 it is determined whether the next intersection is a roundabout. If it is determined to be a roundabout, the process proceeds to step 5, where an intersection layout image 42 that imitates an actual roundabout is generated as a bird's-eye view from a predetermined looking-down angle. In the case of a roundabout, an intersection layout image 42 of the entire roundabout is also generated by combining images of multiple road elements, including an image of an oval road element that corresponds to the circular road RC.

[0040] If the determination in step 4 is NO, then in step 6, it is determined whether the next intersection is a predetermined double intersection. Here, as shown in FIG. 11 , if intersections P1 and P2 where a right or left turn should be made are consecutive and the distance between the two intersections P1 and P2 is smaller than a predetermined threshold, the intersection is determined to be a double intersection. The threshold for the distance between the two intersections P1 and P2 is appropriately set in advance, such as 5 m, 10 m, or 20 m. The distance threshold may also be variably set depending on certain conditions, such as the vehicle speed when approaching the first intersection P1. If it is determined to be a double intersection in step 6, the process proceeds to step 7, where an intersection layout image 43 simulating a real double intersection is generated as a bird's-eye view at a predetermined angle. In the case of a double intersection, the intersection layout image 43 is generated by combining images of multiple road elements, as in the case of a five-way intersection or the like.

[0041] If the determination in step 6 is NO, it is assumed that the next intersection where the lane is to be changed is a simple shape intersection, and the process proceeds to step 11, which will be described later, without generating an intersection layout image.

[0042] After generating an intersection layout image corresponding to the complex-shaped intersection in steps 3, 5, and 7, the process proceeds to step 8, where it is determined whether the driver's driving load is currently low. If the driving load is low, the process proceeds to step 9, where the corresponding intersection layout images 41, 42, and 43 are displayed, as shown in Figures 6, 9, and 12.

[0043] If the determination in step 8 is NO, that is, if the driving load is high, the process proceeds to step 10 without displaying the intersection layout images 41, 42, 43 in order to prevent the driver's attention from being distracted.

[0044] Several conditions are set in advance for determining the driving load. For example, a small curvature of the road on which the vehicle is traveling can be one of the conditions for a low driving load. A long distance to the next intersection can be one of the conditions for a low driving load. Alternatively, a long predicted time to the next intersection can be one of the conditions for a low driving load. A lack of operation of the vehicle's turn signal can be one of the conditions for a low driving load. A lack of steering operation of the vehicle can be one of the conditions for a low driving load. A lack of a preceding vehicle, pedestrian, or obstacle ahead of the host vehicle 31 can be one of the conditions for a low driving load. The determination in step 8 may be based on any one of these conditions, or may be based on whether multiple conditions (e.g., all conditions) are met simultaneously.

[0045] In step 10 following step 9, it is determined whether the distance L from the vehicle 31 to the intersection is equal to or less than a predetermined distance LE at which the display of the intersection layout image should be terminated. The processing of steps 8 and 9 is repeated until the predetermined distance LE is reached, and the intersection layout images 41, 42, and 43 are displayed under the condition that the driving load is low. When the predetermined distance LE is reached, the display of the intersection layout images 41, 42, and 43 is terminated.

[0046] In the next step 11, it is determined whether the distance L from the vehicle 31 to the intersection is equal to or less than a predetermined distance LA. If the distance L is equal to or less than the predetermined distance LA, the display of the arrow-shaped virtual guide image 24 (see FIG. 3) for route guidance begins.

[0047] In this way, in the above embodiment, when the intersection where a lane change is to be made is a complex-shaped intersection, the intersection layout images 41, 42, 43 representing the intersection layout are displayed as bird's-eye views before the route guidance virtual image 24 is displayed on the intersection coordinates. Therefore, the driver can know in advance that the next intersection where a lane change is to be made is a complex-shaped intersection and what the intersection layout is like, and can respond without confusion when the route guidance virtual image 24 is displayed.

[0048] Furthermore, the intersection layout image is displayed only when the intersection is a complex-shaped intersection that meets predetermined criteria, and is not displayed for other simple-shaped intersections. Therefore, the driver's attention is not unnecessarily distracted. Moreover, by not displaying the image when the driver's driving load is high, the driver's attention is prevented from being distracted.

[0049] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, a multi-junction, a roundabout, and a double intersection are given as examples of complex-shaped intersections, but other intersections with layouts that make it difficult to determine the route may also be included as complex-shaped intersections. For example, intersections such as three-way intersections and irregular crossroads where the angle between the road that is the original route and the adjacent road is less than a threshold may also be included.

[0050] Furthermore, in the above embodiment, a two-dimensional intersection layout image is generated as a bird's-eye view along a predetermined downward angle, and this intersection layout image is displayed in a planar manner by the AR-HUD 1. However, it is also possible to generate an intersection layout image as a virtual object that shows the intersection in a planar view, and display this intersection layout image in 3D as a bird's-eye view.

Claims

1. A vehicle information display method that displays a virtual image for vehicle route guidance on the intersection coordinates via the vehicle's AR-HUD, superimposed on the view ahead seen through the windshield; the method determines whether the next intersection at which the vehicle should change course is a simple intersection or a complex intersection according to predetermined criteria; and if it is a complex intersection, displays an intersection layout image representing the intersection layout on the road surface in front of the vehicle as a bird's-eye view seen from a second viewpoint higher than the driver's viewpoint, before the virtual image for route guidance is displayed on the intersection coordinates as the vehicle approaches the intersection.

2. The vehicle information display method according to claim 1, wherein the intersection layout image is a two-dimensional intersection layout image that is viewed as a bird's-eye view from a predetermined angle above the intersection, and the two-dimensional intersection layout image is displayed via an AR-HUD.

3. The vehicle information display method according to claim 1, wherein the intersection layout image is generated as a virtual object showing the intersection in a plan view, and the intersection layout image is displayed in 3D as a bird's-eye view.

4. The vehicle information display method according to claim 1, wherein the display of the intersection layout image is terminated before the vehicle approaches the intersection and a virtual image for route guidance is displayed on the intersection coordinates.

5. The vehicle information display method according to claim 1, wherein the complex intersection is an intersection in which there is a road adjacent to the road to be traveled that forms an angle with the road to be traveled that is less than a threshold value and less than 90 degrees.

6. The vehicle information display method according to claim 1, wherein the complex intersection is a multi-junction with five or more roads.

7. The vehicle information display method according to claim 1, wherein the complex intersection is a roundabout.

8. The vehicle information display method according to claim 1, wherein the complex intersection is an intersection where two consecutive right and left turns are required at two points within a predetermined distance.

9. The vehicle information display method according to claim 1, wherein the bird's-eye view display of the intersection layout image is performed under the condition that the driver's current driving load is low.

10. The vehicle information display method according to claim 9, wherein one of the conditions for a low driving load is that the curvature of the road on which the vehicle is traveling is small.

11. The vehicle information display method according to claim 9, wherein a long distance to the intersection is one of the conditions for a low driving load situation.

12. The vehicle information display method according to claim 9, wherein a long predicted travel time to the intersection is one of the conditions for a low driving load.

13. The information display method for a vehicle according to claim 9, wherein one of the conditions for a low driving load is that the direction indicator of the vehicle is not operating.

14. The vehicle information display method according to claim 9, wherein one of the conditions for a low driving load is that the vehicle is not being steered.

15. The vehicle information display method according to claim 9, wherein one of the conditions for a low driving load is the absence of a preceding vehicle, pedestrian, or obstacle ahead.

16. The vehicle information display method according to claim 1, wherein the intersection layout image is displayed on a virtual line that passes through the center of the vehicle and extends in the longitudinal direction.

17. The vehicle information display method according to claim 1, wherein the intersection layout image is displayed on a virtual line extending in the forward and backward directions through the driver's viewpoint.

18. The vehicle information display method according to claim 1, wherein the intersection layout image is displayed on the center line of the left and right angle of view of the display area.

19. The vehicle information display method according to claim 1, wherein the intersection layout image includes an indication of the road to be traveled.

20. The vehicle information display method according to claim 1, wherein the intersection layout image is an imitation of an actual intersection layout, and the angles or spacing between roads or the widths of the roads are highlighted so that individual roads can be distinguished.

21. A vehicle information display program that causes an on-board computer to execute the vehicle information display method according to claim 1.

22. An information display device for a vehicle comprising: an AR-HUD that displays a virtual object superimposed on the view ahead seen through the windshield; and a control unit that controls the AR-HUD to display a virtual image for route guidance for the vehicle on intersection coordinates as the object, wherein the control unit determines whether the intersection at which the vehicle should next change course is a simple intersection or a complex intersection according to predetermined criteria; and if the intersection is a complex intersection, displays an intersection layout image representing the intersection layout on the road surface in front of the vehicle as a bird's-eye view seen from a second viewpoint position higher than the driver's viewpoint, before the virtual image for route guidance is displayed on the intersection coordinates as the vehicle approaches the intersection.

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