Superposed image display device

Abstract

To provide a superposed image display device characterized in that a guide object enables guiding of explicitly showing a leaving direction at a guide branch point and it is prevented that visibility around the guide branch point is degraded by the guide object.SOLUTION: A travel scheduled route of a vehicle is acquired, and branch point information on a guide branch point existing ahead in an advancing direction of the vehicle along the travel scheduled route is acquired. Based on the travel scheduled route and branch point information, a leaving direction of the vehicle at the guide branch point is identified. A guide object for guiding the leaving direction of the vehicle at the guide branch point is displayed at a position where the guide object is superposed on the guide branch point and its periphery and made visible. The guide object is displayed by making a range of superposition larger in a section, where a distance from the guide branch point is larger than a predetermined distance, than in a section where the distance falls below the predetermined distance.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a superimposed image display device that performs driving support for a vehicle. [Background technology]

[0002] Conventionally, various means have been used as information providing means for providing various information for vehicle driving support such as route guidance and warning of obstacles to vehicle occupants. For example, the information is displayed on a liquid crystal display installed in the vehicle, or sound is output from a speaker. In recent years, one such information providing means is a device that provides information by displaying an image superimposed on the surrounding environment (landscape, real scene) of the occupant. For example, a head-up display, a windshield display, or a method of displaying an image superimposed on a captured image of the vehicle surroundings displayed on a liquid crystal display corresponds to the information providing means.

[0003] As a technique for providing guidance to a guidance branch point by displaying an image superimposed on the surrounding environment, for example, JP 2022-77198 A proposes a technique for displaying an arrow indicating the exit direction of the vehicle at the guidance branch point by superimposing the arrow on the guidance branch point. Furthermore, it is also disclosed that the arrow is displayed in a floating state above the road surface, rather than displaying the image of the arrow on the road surface so that the occupant can more easily grasp the exit direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-77198 A (paragraph 0057) Summary of the Invention [Problem to be solved by the invention]

[0005] Here, when an arrow image is superimposed on the guidance branch point as in Patent Document 1, the displayed arrow image may hide the scenery of the guidance branch point, making it difficult to see. In particular, when the arrow image is displayed floating above the road surface, it becomes easier to grasp the exit direction, but the area hidden by the arrow image increases. Things that passengers can see around the guidance branch point include, for example, structures that serve as landmarks for the guidance branch point, and pedestrians and bicycles located around the guidance branch point, and it is problematic if the visibility of these is hindered. In particular, pedestrians and bicycles are objects that vehicles must pay attention to when passing through a guidance branch point, and it is necessary to avoid making them difficult to see.

[0006] The present invention has been made to solve the above-mentioned problems in the conventional art, and aims to provide an overlay image display device that enables guidance that clearly indicates the exit direction of a guidance junction using a guidance object, while preventing the guidance object from reducing visibility around the guidance junction. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the superimposed image display device of the present invention is an overlay image display device that allows a guide object that provides information to a vehicle occupant in a vehicle to be visually superimposed on the scenery around the vehicle, and has a planned driving route acquisition means for acquiring a planned driving route for the vehicle, a branch point information acquisition means for acquiring branch point information relating to a guidance branch point located ahead in the vehicle's direction of travel along the planned driving route, and an object display means for displaying the guide object for guiding the vehicle's exit direction at the guidance branch point at a position where it can be visually seen superimposed on the guidance branch point and its surroundings, and the object display means displays the guide object by expanding the superimposition range in sections at a predetermined distance or more from the guidance branch point rather than sections less than a predetermined distance from the guidance branch point. It should be noted that the "scenery" includes not only the scenery actually viewed from the vehicle (actual scenery), but also an image of the scenery captured, an image of the scenery reproduced, and the like. Effect of the Invention

[0008] According to the superimposed image display device of the present invention having the above-mentioned configuration, it is possible to provide guidance that clearly indicates the exit direction of the guidance junction by using a guidance object that is superimposed on the scenery around the vehicle, while it is also possible to prevent a decrease in visibility around the guidance junction due to the guidance object by restricting the range over which the guidance object is superimposed in sections less than a specified distance from the guidance junction. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a superimposed image display device according to an embodiment of the present invention. [Diagram 2] 1 is a diagram showing an example of a landscape viewed by a vehicle occupant and a virtual image superimposed on the landscape. [Diagram 3] 1 is a block diagram showing a navigation device according to an embodiment of the present invention; [Figure 4] FIG. 11 is a diagram showing an example of branch point data. [Diagram 5] 5 is a flowchart of a driving support processing program according to the present embodiment. [Figure 6] FIG. 13 is a diagram illustrating a method for calculating an exit angle. [Figure 7] 1A and 1B are diagrams showing examples of guide objects visually recognized by vehicle occupants; [Figure 8] 13A and 13B are diagrams illustrating an area in which the overlapping range of the guide object is expanded. [Figure 9] 13A and 13B are diagrams illustrating the extent to which the overlapping range of a guide object is expanded with respect to an exit angle. [Figure 10] 13 is a diagram showing the relationship between an exit angle, a distance from a guidance branch point, and an overlapping range of a guidance object. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a detailed description will be given of an embodiment of a superimposed image display device 1 according to the present invention with reference to the drawings. First, a schematic configuration of the superimposed image display device 1 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic configuration diagram of the superimposed image display device 1 according to this embodiment.

[0011] 1, the superimposed image display device 1 basically includes a navigation device 3 mounted on a vehicle 2, and a front display 4 also mounted on the vehicle 2 and connected to the navigation device 3. The front display 4 functions as a head-up display together with a windshield 5 of the vehicle 2 as described below, and serves as an information providing means for providing various information to an occupant 6 of the vehicle 2.

[0012] Here, the navigation device 3 has functions of searching for a recommended route to the destination, displaying a map image of the area around the current position of the vehicle 2 based on map data acquired from a server or stored in memory, and providing driving guidance along a set guide route together with the front display 4. Note that the navigation device 3 does not need to have all of the above functions, and the present invention can be constituted as long as it has at least the function of providing driving guidance along a guide route. Note that the structure of the navigation device 3 will be described in detail later.

[0013] Meanwhile, the front display 4 is a liquid crystal display that is installed inside the dashboard 7 of the vehicle 2 and has a function of displaying images on an image display surface provided on the front. For example, a CCFL (cold cathode fluorescent lamp) or a white LED is used as a backlight. Note that, as the front display 4, in addition to a liquid crystal display, an organic EL display or a combination of a liquid crystal projector and a screen may also be used.

[0014] The front display 4 functions as a head-up display together with the windshield 5 of the vehicle 2, and is configured to reflect the image output from the front display 4 onto the windshield 5 in front of the driver's seat so that it can be viewed by an occupant 6 of the vehicle 2.

[0015] In this embodiment, images displayed on the front display 4 and visually recognized by the occupant 6 of the vehicle 2 include information about the vehicle 2 and various information used to support the driving of the occupant 6. For example, there are warnings for objects to be warned to the occupant 6 (other vehicles, pedestrians, guide signs), a guide route set by the navigation device 3 and guide information based on the guide route (arrows indicating the right and left turn directions, etc.), warnings to be displayed on the road surface (collision warning, speed limit, etc.), lane markings on which the vehicle is traveling, current vehicle speed, shift position, remaining energy, advertisement images, facility information, map images, traffic information, news, weather forecasts, time, the screen of a connected smartphone, television programs, etc. In addition, in the embodiment described below, information for providing guidance at a guidance branch point located ahead in the traveling direction of the vehicle is displayed as a guidance object on the front display 4. More specifically, it is a line segment superimposed on the road surface connecting the entrance road to the exit road of the guidance branch point.

[0016] In addition, when the occupant 6 views the image displayed on the front display 4 reflected by the windshield 5, the image displayed on the front display 4 at a distant position beyond the windshield 5 is viewed by the occupant 6 as a virtual image 10, not at the position of the windshield 5. In addition, the virtual image 10 is displayed superimposed on the surrounding environment (landscape, real scene) in front of the vehicle, and can be displayed superimposed on any object (road surface, intersection, building, object to be warned, etc.) located in front of the vehicle.

[0017] For example, FIG. 2 shows an example of a case where a virtual image 10 is displayed superimposed on the surrounding environment (scenery, real scene) in front of the vehicle. As shown in FIG. 2, an image 9 of a line segment superimposed on a road surface connecting, for example, an entrance road to an exit road at a guidance branch point is displayed on the front display 4. As a result, the image 9 of the line segment displayed on the front display 4 is reflected on the windshield 5 and viewed by the vehicle occupant 6, and the virtual image 10 of the image 9 of the line segment superimposed on the scene through the windshield 5 is viewed. However, the virtual image 10 cannot be superimposed anywhere on the scene through the windshield 5, and the range in which the virtual image 10 can be superimposed and viewed by the vehicle occupant 6 is limited. Specifically, the range is determined by the size of the display screen of the front display 4 and the installation position with respect to the dashboard 7.

[0018] On the other hand, the position in the depth direction where the virtual image 10 is generated, more specifically, the distance L from the occupant 6 to the virtual image 10 (hereinafter referred to as the imaging distance), is determined by the position of the front display 4. For example, the imaging distance L is determined by the distance (optical path length) along the optical path from the position where the image is displayed on the front display 4 to the windshield 5. For example, the optical path length is set so that the imaging distance L is 1.5 m.

[0019] In addition, in this embodiment, the front display 4 installed inside the dashboard 7 is used as a means for displaying an image to be superimposed on the scenery around the vehicle, but other means may be used. For example, a head-up display (HUD) device may be provided as an in-vehicle device, or the windshield 5 may be a transparent liquid crystal display and an image may be displayed directly on the windshield 5. Furthermore, it is also possible to display the scenery around the vehicle captured by a front camera 11 (described later) on a liquid crystal display inside the vehicle, and to display an image to be superimposed on the displayed scenery on the same liquid crystal display. In this case, too, the image displayed on the liquid crystal display becomes an image to be superimposed on the scenery around the vehicle, similar to the HUD.

[0020] A front camera 11 is installed above the front bumper of the vehicle or on the back side of the rearview mirror. The front camera 11 is an imaging device having a camera using a solid-state imaging element such as a CCD, and is installed with its optical axis direction facing forward in the traveling direction of the vehicle. Then, image processing is performed on the image captured by the front camera 11, and the situation of the front environment (i.e., the environment on which the virtual image 10 is superimposed) visually recognized by the occupant 6 through the windshield is detected. Note that a sensor such as a millimeter wave radar may be used instead of the front camera 11.

[0021] An in-vehicle camera 12 is installed on the top surface of the vehicle's instrument panel. The in-vehicle camera 12 is an imaging device having a camera using a solid-state imaging element such as a CCD, and is installed with its optical axis direction facing the driver's seat. A range in the vehicle where the face of an occupant is generally expected to be located is set as a detection range (imaging range of the in-vehicle camera 12), and an image of the face of the occupant 6 sitting in the driver's seat is captured. Then, image processing is performed on the captured image captured by the in-vehicle camera 12, thereby detecting the eye position (starting point of gaze) and gaze direction of the occupant 6.

[0022] Next, a schematic configuration of the navigation device 3 constituting the above-mentioned superimposed image display device 1 will be described with reference to Fig. 3. Fig. 3 is a block diagram showing the navigation device 3 according to this embodiment.

[0023] 3, the navigation device 3 according to this embodiment includes a current position detection unit 13 for detecting the current position of the vehicle 2 on which the navigation device 3 is mounted, a data recording unit 14 for recording various data, a navigation ECU 15 for performing various calculation processes based on input information, an operation unit 16 for receiving operations from a user, a liquid crystal display 17 for displaying a map of the area around the vehicle and facility information on facilities to the user, a speaker 18 for outputting voice guidance on route guidance, a DVD drive 19 for reading a DVD as a storage medium, and a communication module 20 for communicating with an information center such as a probe center or a VICS (registered trademark: Vehicle Information and Communication System) center. The navigation device 3 is also connected to the front display 4, the front camera 11, the in-vehicle camera 12, and the like via an in-vehicle network such as a CAN.

[0024] Each of the components of the navigation device 3 will be described below in order. The current position detection unit 13 is composed of a GPS 21, a vehicle speed sensor 22, a steering sensor 23, a gyro sensor 24, etc., and is capable of detecting the current vehicle position, direction, vehicle running speed, current time, etc. Here, the vehicle speed sensor 22 in particular is a sensor for detecting the travel distance and vehicle speed of the vehicle, and generates pulses in response to the rotation of the drive wheels of the vehicle and outputs the pulse signal to the navigation ECU 15. The navigation ECU 15 then calculates the rotation speed and travel distance of the drive wheels by counting the generated pulses. Note that the navigation device 3 does not need to be equipped with all of the above four types of sensors, and the navigation device 3 may be configured to be equipped with only one or more types of sensors among these.

[0025] The data recording unit 14 also includes a hard disk (not shown) as an external storage device and recording medium, and a recording head (not shown) which is a driver for reading out the map information DB 31 and predetermined programs recorded on the hard disk and writing predetermined data to the hard disk. The data recording unit 14 may have a flash memory, a memory card, or an optical disk such as a CD or a DVD instead of the hard disk. The map information DB 31 may also be stored in an external server and the navigation device 3 may acquire it through communication.

[0026] Here, the map information DB 31 is a storage means that stores, for example, link data 32 relating to roads (links), node data 33 relating to node points, branch point data 34 relating to branch points, point data relating to points such as facilities, map display data for displaying a map, search data for searching for routes, search data for searching for points, etc.

[0027] The link data 32 includes, for each link constituting the road network, data representing the width, gradient, cant, bank, road surface condition, and shape complement point data for identifying the link shape between nodes (for example, the shape of the curve in the case of a curved road), the number of lanes on the road, the traffic division in the direction of travel for each lane, the presence or absence of an oncoming lane (whether it is a two-way traffic section or not), the presence or absence of a central divider, points where the road width narrows, and railroad crossings; for corners, data representing the radius of curvature, intersections, T-junctions, corner entrances and exits, etc.; for road attributes, data representing downhill roads, uphill roads, etc.; and for road types, data representing expressways and general roads (national highways, prefectural roads, narrow streets, etc.).

[0028] The node data 33 also includes data regarding the coordinates (positions) of actual road branching points (including intersections, T-junctions, etc.) and node points set at predetermined distances on each road depending on the radius of curvature, etc., node attributes indicating whether the node corresponds to an intersection, etc., a connecting link number list which is a list of link numbers of links connecting to the node, an adjacent node number list which is a list of node numbers of nodes adjacent to the node via links, and the height (altitude) of each node point, etc.

[0029] In addition, the branch point data 34 stores the intersection name of the branch point, corresponding node information that identifies the node that forms the branch point, connecting link information that identifies the link connected to the branch point, the direction name corresponding to the link connected to the branch point, information that identifies the shape of the branch point, etc.

[0030] Moreover, the information for specifying the shape of the branch point included in the branch point data 34 includes, in addition to the number of roads connected to the intersection, information for specifying the direction in which each road is connected to the intersection (connection direction). For example, for a five-way branch point where five roads 51 to 55 are connected as shown in Fig. 4, the angle θ1 of road 51, the angle θ2 of road 52, the angle θ3 of road 53, the angle θ4 of road 54, and the angle θ5 of road 55 are stored with one direction (for example, the north direction) as the reference. However, instead of the information for specifying the above angles, the information for specifying the road connection direction may be, for example, the coordinates of nodes P1 to P5 located at the end points of roads 51 to 55 (the road connection direction can be specified by comparing with the coordinates of the branch point).

[0031] On the other hand, the navigation ECU (electronic control unit) 15 is an electronic control unit that controls the entire navigation device 3, and includes a CPU 41 as an arithmetic device and a control device, a RAM 42 that is used as a working memory when the CPU 41 performs various arithmetic processing and stores route data when a route is searched, a ROM 43 that stores a driving support processing program (FIG. 5) described later as well as a control program, and a flash memory 44 that stores a program read from the ROM 43. The navigation ECU 15 has various means as processing algorithms. For example, a planned driving route acquisition means acquires a planned driving route of the vehicle. A branch point information acquisition means acquires branch point information on a guidance branch point located ahead of the vehicle in the traveling direction along the planned driving route. An object display means displays a guidance object for guiding the vehicle in the exit direction at the guidance branch point at a position where the guidance object is superimposed on the guidance branch point and its periphery so as to be visually recognized.

[0032] The operation unit 16 is operated when inputting a departure point as a travel start point and a destination point as a travel end point, and has a plurality of operation switches (not shown) such as various keys and buttons. The navigation ECU 15 performs control to execute various corresponding operations based on switch signals output by pressing each switch. The operation unit 16 may have a touch panel provided on the front surface of the liquid crystal display 17. It may also have a microphone and a voice recognition device.

[0033] The liquid crystal display 17 also displays map images including roads, traffic information, operation guidance, operation menus, key guidance, guided route from the departure point to the destination, guidance information along the guided route, news, weather forecasts, time, e-mail, television programs, etc. In this embodiment, the front display 4 is provided as information display means, and therefore the liquid crystal display 17 may be omitted if the map images and the like are displayed on the front display 4.

[0034] The speaker 18 also outputs voice guidance for guiding the vehicle along a guide route based on instructions from the navigation ECU 15, and traffic information guidance.

[0035] The DVD drive 19 is a drive capable of reading data recorded on a recording medium such as a DVD or a CD. Based on the read data, music and video are played, and the map information DB 31 is updated. Instead of the DVD drive 19, a card slot for reading and writing data into a memory card may be provided.

[0036] The communication module 20 is a communication device for receiving traffic information consisting of various information such as congestion information, regulation information, and traffic accident information transmitted from a traffic information center, such as a VICS center or a probe center, and is, for example, a mobile phone or a DCM.

[0037] Next, a driving support processing program executed by the navigation ECU 15 in the navigation device 3 having the above configuration will be described with reference to Fig. 4. Fig. 5 is a flowchart of the driving support processing program according to this embodiment. Here, the driving support processing program is executed after the ACC power supply (accessory power supply) of the vehicle is turned on, and is a program that assists driving of the vehicle by allowing the image displayed on the front display 4 to be visually recognized by superimposing it on the scenery (actual scene) around the vehicle. The program shown in the flowchart in Fig. 5 below is stored in the RAM 42 or ROM 43 provided in the navigation device 3, and is executed by the CPU 41.

[0038] In the following description, an example of providing vehicle driving guidance along a guidance route set by the navigation device 3 as vehicle driving support using a guidance object will be described. The guidance object to be displayed is guidance information for providing guidance at a guidance branch point ahead in the traveling direction of the vehicle, and in particular, a process in which a line segment indicating the exit direction of the guidance branch point is displayed as a guidance object will be described as an example. However, the superimposed image display device 1 can also provide guidance and information other than the above-mentioned driving support using a guidance object. The guidance object to be displayed can also be information other than the above-mentioned line segment. For example, it is possible to display, as a guidance object, a warning for an object to be warned to the occupant (another vehicle, a pedestrian, a guide sign), a warning to be displayed on the road surface (beware of rear-end collisions, speed limits, etc.), an arrow indicating the exit direction of the next guidance branch point, a current vehicle speed, a gear shift position, remaining energy, an advertisement image, facility information, a guide sign, a map image, traffic information, news, a weather forecast, time, a screen of a connected smartphone, and the like.

[0039] First, in the driving support processing program, in step (hereinafter abbreviated as S) 1, the CPU 41 specifies the current position of the vehicle based on the detection result of the current position detection unit 13 and map information. When specifying the current position of the vehicle, a map matching process is also performed to match the current position of the vehicle with the map information. After that, the guidance route set in the navigation device 3 is read out, and the distance from the specified current position of the vehicle to the next guidance branch point along the guidance route is calculated. Note that the guidance branch point is a branch point (intersection) that is a target for guidance such as right or left turn instructions when the navigation device 3 provides driving guidance according to the guidance route set in the navigation device 3. Note that a branch point (difficult intersection) that does not require right or left turns but has a special shape also corresponds to the guidance branch point.

[0040] Next, in S2, the CPU 41 judges whether the distance to the next guidance branch point calculated in S1 is less than a predetermined guidance start distance. The guidance start distance is determined according to the road type of the road on which the vehicle is traveling, for example, 500 m for expressways and 100 m for general roads, which is shorter than expressways. However, the guidance start distance may be a variable value rather than a fixed value. For example, it may be set according to the traveling speed of the vehicle.

[0041] If it is determined that the distance to the next guidance branch point calculated in S1 is less than the guidance start distance (S2: YES), the process proceeds to S3. On the other hand, if it is determined that the distance to the next guidance branch point calculated in S1 is not less than the guidance start distance (S2: NO), the process returns to S1.

[0042] In S3, the CPU 41 specifies an entrance road for the vehicle to enter the guidance branch point determined to be within the guidance start distance and an exit road for the vehicle to exit the guidance branch point. Specifically, the CPU 41 can specify a link corresponding to the entrance road and a link corresponding to the exit road from the guidance route and branch point data 34 set in the navigation device 3.

[0043] Next, in S4, the CPU 41 acquires an exit direction for the vehicle to exit from the guidance branch point that is determined to be within the guidance start distance. Basically, the travel direction of the exit road (specifically, the link corresponding to the exit road) acquired in S3 is the exit direction. The travel direction of each link connected to the branch point is stored in the map information as the branch point data 34 (FIG. 4).

[0044] Next, in S5, the CPU 41 acquires the current traveling direction of the vehicle based on the detection result of the current position detection unit 13.

[0045] Thereafter, in S6, the CPU 41 calculates an angle θ (hereinafter referred to as an exit angle) between the current traveling direction of the vehicle acquired in S5 and the exit direction of the vehicle at the guidance branch point acquired in S4. Here, the process from S5 onwards is repeatedly executed until the vehicle passes the guidance branch point. Therefore, the exit angle θ calculated in S6 changes as the traveling direction of the vehicle changes. For example, in the example shown in FIG. 6, the exit angle θ is about 90 degrees before the vehicle 60 enters the guidance branch point 61. On the other hand, when the vehicle 60 enters the guidance branch point 61 and starts turning, the exit angle θ gradually decreases from 90 degrees, and finally the traveling direction α of the vehicle 60 coincides with the exit direction β, so that the exit angle θ becomes 0 degrees.

[0046] Next, in S7, the CPU 41 sets an area for widening the range in which the guidance object is superimposed. Here, in this embodiment, the guidance object 65 (more precisely, a virtual image of the guidance object) displayed on the front display 4 and visually recognized by the occupant is a line segment superimposed on the road surface connecting the entrance road 67 of the guidance branch point 66 to the exit road 68 as shown in FIG. 7. Also, the thickness of the line segment (width in the road width direction) corresponds to the vehicle width. As a result, as shown in FIG. 7, the guidance object 65 superimposed on the road surface of the entrance road 67 before entering the guidance branch point 66 is sufficiently thick and easy for the occupant to visually recognize, but the guidance object 65 superimposed on the road surface of the exit road 68 of the guidance branch point 66 has a problem that the road surface of the exit road 68 (visible to the occupant) becomes narrow, so that the guidance object 65 superimposed thereon is also thin, making it difficult for the occupant to understand the exit road 68 (i.e., the exit direction of the guidance branch point). In particular, when the exit angle θ is 90 degrees or more, it becomes difficult to know the exit direction. For example, assuming that the line segment thickness of the guide object 65 is 1.5 m, when the guide object superimposed on the exit road 68 with an exit angle of 90 degrees is visually recognized 100 m before the guidance branch point, the thickness of the guide object 65 is 0.17 mm. Similarly, it becomes 0.68 mm from 50 m before, and 2.72 mm from 25 m before. Therefore, in this embodiment, as shown in FIG. 7, the guide object 65 superimposed on the exit road 68 is displayed with the superimposed range expanded upward with respect to the road surface.

[0047] However, if the range of overlapping of the guide object 65 is widened, while the exit direction becomes easier to grasp, the range hidden by the guide object 65 also increases. For example, the objects that the passenger can see around the guidance branch point include structures that serve as landmarks for the guidance branch point, and pedestrians and bicycles located around the guidance branch point, and it is problematic that the visibility of these objects is hindered. In particular, pedestrians and bicycles are objects that the vehicle must pay attention to when passing through the guidance branch point, and it is necessary to avoid making them difficult to see. Therefore, in this embodiment, the range of overlapping of the guide object 65 is widened only to a section that is away from the guidance branch point (more specifically, the branch point center, the node corresponding to the branch point) by a predetermined distance L or more. In S7, the CPU 41 sets this predetermined distance L.

[0048] Here, it is desirable to set the predetermined distance L based on the shape of the guidance branch point. Basically, the larger the branch point (the more intersecting lanes), the larger the predetermined distance L is set to. For example, the predetermined distance L is set to a large value for a branch point where main roads intersect. Also, as shown in FIG. 8, if there is a crosswalk 69 near the guidance branch point, it is desirable to set the predetermined distance L to the distance from the guidance branch point 66 (more specifically, the center of the branch point, the node corresponding to the branch point) to the crosswalk 69 (or a distance greater than that). Here, the "distance to the crosswalk 69" is the distance from the guidance branch point 66 to the furthest position of the crosswalk 69 (the edge on the opposite side from the guidance branch point).

[0049] As a result, the crosswalk 69 is excluded from the section in which the overlapping range of the guide object 65 is expanded, so that it is possible to prevent the crosswalk 69 from being difficult to see due to the guide object 65. In addition, since the overlapping range of the guide object 65 is expanded on the exit road 68, the predetermined distance L is basically set based only on the crosswalk on the exit road 68, but the predetermined distance L may be set based on a crosswalk other than the exit road. In addition, if there is an area other than the crosswalk where, for example, a pedestrian or a bicycle may pass, the predetermined distance L may be the distance from the guidance branch point 66 (more specifically, the branch point center, the node corresponding to the branch point) to the area (or a distance greater than that). On the other hand, for example, in a guidance branch point where a pedestrian or a bicycle is not basically present, such as a branch point with a pedestrian bridge or a branch point on a highway, the predetermined distance L may be set to 0 (i.e., the overlapping range of the guide object 65 is expanded on the entire exit road).

[0050] Next, in S8, the CPU 41 sets how much to widen the range in which the guide object overlaps in the section set in S7. In this embodiment, as shown in FIG. 7, the overlapping range is widened upward from the road surface, so the extent to which the overlapping extends upward from the road surface is set. Here, in this embodiment, the closer the exit angle θ calculated in S6 is to a right angle (90 degrees), the thinner the line segment of the guide object overlapping the road surface of the exit road appears to the passenger, so the overlapping range is set to be wider. However, the upper limit is set when the exit angle θ is 90 degrees, and when the exit angle θ is 90 degrees or more (90 to 180 degrees), the upper limit value may be set.

[0051] As a result, as shown in FIG. 9, when comparing the case where the exit angle θ is 45 degrees with the case where the exit angle θ is 90 degrees, the guide object 65 is superimposed higher above the road surface when the exit angle is 90 degrees.

[0052] The range of overlapping of the guide object can be set by a combination of the exit angle θ and the distance from the guidance branch point (more specifically, the center of the branch point, or the node corresponding to the branch point). For example, as shown in FIG. 10, when the exit angle θ is between 0 and 90 degrees, the range of overlapping of the guide object is made larger as the exit angle θ approaches 90 degrees. On the other hand, when the exit angle θ is 90 degrees or more, it is set to a fixed value. Also, the range of overlapping of the guide object is made larger as the distance from the guidance branch point increases. However, if the range of overlapping of the guide object is made too large, the visibility of the guidance branch point decreases, so the upper limit is set to 400 mm. The overlapping range [mm] shown in FIG. 10 is not the distance on the screen but the distance within the scenery to be overlapped.

[0053] Also, the exit angle θ may be corrected in the positive direction when there is an upward gradient in the direction in which the vehicle is exiting, and in the negative direction when there is a downward gradient. This is because the road width of the exit road appears wider when there is an upward gradient, and narrower when there is a downward gradient. It is also possible to set the range in which the guide object overlaps according to the current vehicle speed. For example, the faster the vehicle speed, the larger the range in which the guide object overlaps.

[0054] After that, in S9, the CPU 41 determines the position (range) in which the guide object is to be displayed on the front display 4. Specifically, in S9, the following process is performed.

[0055] First, the CPU 41 detects the eye positions of the vehicle occupants based on the captured image captured by the in-vehicle camera 12. Next, the position of the windshield 5 onto which the image is to be projected by the front display 4 is obtained. The eye positions of the vehicle occupants and the position of the windshield 5 are specified by three-dimensional position coordinates. Next, the CPU 41 obtains the position of the guidance object to be displayed on the front display 4 to be superimposed on the scenery. Basically, the position of the guidance object to be superimposed is the guidance branch point and its surroundings as described above, specifically, on the road surface connecting the entrance road of the guidance branch point to the exit road. However, for a section that is a predetermined distance L or more from the guidance branch point of the exit road (more specifically, the branch point center, the node corresponding to the branch point), the guidance object is also superimposed in the range above the road surface set in S8. Next, the CPU 41 determines a projection range of the guidance object on the windshield 5 based on the identified eye positions of the vehicle occupants, the position of the windshield 5, and the position where the guidance object is to be superimposed. Furthermore, the CPU 41 also determines a display range of the guidance object on the front display 4 from the determined projection range. Note that the shape of the guidance object to be displayed on the front display 4 can be specified, for example, by arranging the guidance object in a three-dimensional space that reproduces the periphery of the vehicle, and calculating the shape when viewed from a position corresponding to the current position of the vehicle in the three-dimensional space.

[0056] Next, in S10, the CPU 41 transmits a control signal to the front display 4, and displays an image of the guide object in the display range determined in S9 on the front display 4. As a result, it becomes possible for the vehicle occupants to visually recognize the guide object (more precisely, a virtual image of the guide object) superimposed on the scenery.

[0057] Specifically, the virtual image of the guide object 65 visually recognized by the passenger in S9 is a line segment superimposed on the road surface from the entrance road 67 of the guidance branch point 66 to the exit road 68 in the scenery as shown in FIG. 9. The thickness (length in the road width direction) of the line segment of the guide object 65 corresponds to the vehicle width of the vehicle. However, for a section that is a predetermined distance L or more from the guidance branch point of the exit road (more specifically, the branch point center, the node corresponding to the branch point), the guide object 65 is also superimposed in a range above the road surface set in S8. In other words, the superimposed range is expanded in a section that is a predetermined distance or more from the guidance branch point 66 compared to a section that is less than the predetermined distance L from the guidance branch point 66. As a result, a sufficient thickness can be secured for the guide object 65 superimposed on the exit road 68, and a virtual image of the guide object 65 that clearly indicates the exit direction of the guidance branch point 66 is displayed. On the other hand, since the superimposed range is not expanded for a section that is less than the predetermined distance L from the guidance branch point 66, the visibility of the guidance branch point 66 can also be secured.

[0058] Thereafter, in S11, the CPU 41 specifies the current position of the vehicle based on the detection result of the current position detection unit 13, and determines whether or not the vehicle has passed a guidance branch point.

[0059] If it is determined that the vehicle has not passed the guidance branch point (S11: NO), the process returns to S5 and the guidance object continues to be displayed. On the other hand, if it is determined that the vehicle has passed the guidance branch point (S11: YES), the driving support processing program is terminated. In this case, a control signal is sent to the front display 4, and the guidance object displayed on the front display 4 is hidden. Note that the front display 4 may be configured not to display anything until the next guidance branch point is within the guidance start distance, or a line segment or a straight arrow suggesting to proceed along the road during that time may be displayed, or other information such as the vehicle speed and a map image of the surrounding area may be displayed.

[0060] As described in detail above, according to the superimposed image display device 1 and the computer program executed by the superimposed image display device 1 of this embodiment, a planned driving route for the vehicle is obtained (S1), branch point information regarding a guidance branch point located ahead in the vehicle's direction of travel along the planned driving route is obtained (S3, S4), and a guidance object for guiding the vehicle's exit direction at the guidance branch point is displayed in a position where it can be seen by superimposing it on the guidance branch point and its surroundings (S10). At the same time, the guidance object is displayed with a wider superimposed range in sections that are a predetermined distance or more from the guidance branch point than in sections that are less than the predetermined distance from the guidance branch point (S7, S8, S10). Therefore, while the guidance object superimposed on the scenery around the vehicle makes it possible to provide guidance that clearly shows the exit direction from the guidance branch point, it is also possible to prevent a reduction in visibility around the guidance branch point due to the guidance object by restricting the superimposed range of the guidance object in sections that are less than the predetermined distance from the guidance branch point. In addition, based on the planned driving route and the branch point information, an entry road through which the vehicle will enter the guidance branch point and an exit road through which the vehicle will exit the guidance branch point are identified (S3), and the guidance objects are superimposed on the road surface connecting the entry road to the exit road, and the range of the superimposition on the road surface is expanded upwardly for sections that are a predetermined distance or more from the guidance branch point, thereby displaying the guidance objects (S7, S8, S10). Therefore, the guidance objects superimposed on the road surface of the guidance branch point provide intuitive and easy-to-understand guidance as to which direction to enter and which direction to exit the guidance branch point from, while by expanding the range of the guidance object superimposed upwardly for sections that are a predetermined distance or more from the guidance branch point, the guidance objects can be clearly seen even if the road surface visible to the occupants, i.e., the guidance object superimposed on the road surface, becomes thinner. In addition, the vehicle's direction of travel is obtained (S5), and the exit direction in which the vehicle will exit from the guidance branch point is identified based on the planned route and branch point information (S4). The angle between the direction of travel and the exit direction is obtained (S6). In sections that are a specified distance or more from the guidance branch point, the closer the angle between the direction of travel and the exit direction is to a right angle, the wider the superimposed range of the guidance object is displayed (S7, S8, S10). This makes it possible to clearly view the guidance object, especially even when the road surface of the exit road that is visible to the occupants, i.e., the guidance object superimposed on the road surface of the exit road, is thin. Furthermore, if there is a crosswalk near the guidance branch point, the specified distance is set to the distance from the guidance branch point to the crosswalk or a distance greater than that (S7). Therefore, the crosswalk is excluded from the section in which the range in which the guidance object overlaps is expanded, and it is possible to prevent pedestrians and bicycles crossing the crosswalk from being difficult to see due to the guidance object.

[0061] Incidentally, the present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications are possible without departing from the spirit and scope of the present invention. For example, in this embodiment, a head-up display system is used as a means for displaying an image to be superimposed on the scenery around the vehicle, but the windshield 5 may be a transparent liquid crystal display and an image may be displayed directly on the windshield 5. Furthermore, it is also possible to display the scenery around the vehicle captured by a front camera 11 (described later) on a liquid crystal display inside the vehicle, and to display an image to be superimposed on the displayed scenery on the same liquid crystal display. In this case, too, the image displayed on the liquid crystal display is an image to be superimposed on the scenery around the vehicle, similar to the HUD.

[0062] In addition, in this embodiment, the front display 4 is configured to generate a virtual image in front of the windshield 5 of the vehicle 2, but the virtual image may be generated in front of a window other than the windshield 5. Furthermore, the target onto which the image is reflected by the front display 4 may not be the windshield 5 itself, but a visor (combiner) installed around the windshield 5.

[0063] In addition, in this embodiment, a line segment superimposed on the road surface connecting the entrance road and the exit road is used as the guidance object that provides guidance to the guidance branch point, but a guidance object other than the above line segment (for example, an arrow-shaped guidance object) may also be used as long as the guidance object can suggest the exit direction from the guidance branch point.

[0064] In addition, in this embodiment, when the overlapping range of the guide object is expanded, the overlapping range is expanded upward with respect to the road surface. However, the overlapping range may be expanded parallel to the road surface.

[0065] In this embodiment, the navigation ECU 15 of the navigation device 3 executes the driving support processing program (FIG. 5), but the executing entity can be changed as appropriate. For example, the control unit of the front display 4, the vehicle control ECU, or other in-vehicle device may execute the program. [Explanation of symbols]

[0066] 1...superimposed image display device, 2...vehicle, 3...navigation device, 4...front display, 5...windshield, 6...occupant, 15...navigation ECU, 41...CPU, 42...RAM, 43...ROM, 65...guidance object, 66...guidance branch point, 67...entrance road, 68...exit road

Claims

1. 1. A superimposed image display device for displaying information to a vehicle occupant in a vehicle by superimposing a guide object on a landscape around the vehicle, the superimposed image display device comprising: A planned driving route acquisition means for acquiring a planned driving route of a vehicle; A branch point information acquisition means for acquiring branch point information regarding a guidance branch point located ahead in a traveling direction of the vehicle along the planned travel route; and an object display means for displaying the guidance object for guiding the vehicle in the exit direction at the guidance branch point at a position where the guidance object can be visually recognized by being superimposed on the guidance branch point and its periphery, The object display means is a superimposed image display device in which the guide object is displayed in a wider range of superimposition in a section that is a predetermined distance or more from the guidance branch point than in a section that is less than the predetermined distance.

2. a road specifying means for specifying an entrance road for a vehicle to enter the guidance branch point and an exit road for a vehicle to exit the guidance branch point based on the planned travel route and the branch point information, 2. The superimposed image display device according to claim 1, wherein the object display means superimposes the guide object on a road surface connecting the entrance road to the exit road, and displays the guide object by expanding the range of superimposition above the road surface in a section that is a predetermined distance or more from the guidance branch point.

3. A traveling direction acquisition means for acquiring a traveling direction of a vehicle; an exit direction specifying means for specifying an exit direction in which a vehicle exits from the guidance branch point based on the planned travel route and the branch point information; An angle acquisition means for acquiring an angle between the travel direction and the exit direction, 2. The superimposed image display device according to claim 1, wherein the object display means displays the guide object by expanding the superimposed range as the angle between the travel direction and the exit direction approaches a right angle in a section that is a predetermined distance or more from the guidance branch point.

4. 4. The superimposed image display device according to claim 1, wherein, when a pedestrian crossing is present near the guidance branch point, the predetermined distance is a distance from the guidance branch point to the pedestrian crossing or a distance greater than the distance.

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