Display system

Abstract

A display system with excellent information transmission capability is provided. A display system of the present embodiment comprises a first display device that displays an image in a first display area such that it is visually recognized at a position of a first display distance from the gaze of a driver of a self-propelled vehicle, a second display device that displays an image in a second display area that differs from the first display area such that it is visually recognized at a second display distance that is greater from the driver's gaze than the first display distance, and a display control unit that performs a recognition level enhancement treatment in which, if a first condition is met, a warning image is displayed in the second display area, and, if after the first condition is met, a second condition is met that indicates a situation with a higher warning level than the first condition,the warning image is moved to the first display area and displayed, or a detection level reduction treatment is performed in which, if the second condition is met, the warning image is displayed in the first display area, and, if the first condition is met after the second condition has been met, the warning image is moved to the second display area and displayed.

Description

Display System

[0001] The present disclosure relates to a display system for a vehicle or the like having multiple displays.

[0002] BACKGROUND ART Conventionally, a plurality of display devices are arranged at a plurality of locations within a vehicle, and information is displayed by linking the plurality of display devices.

[0003] JP 2017-071398 A

[0004] Today, vehicles are increasingly being equipped with head-up displays capable of displaying information in a variety of display formats and large display panels capable of displaying a large amount of information. Accordingly, the amount and variety of information that can be conveyed to the driver is increasing. Accordingly, display devices are increasingly being required to convey necessary information to the driver at the necessary time with good visibility.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to provide a display system with excellent information transmission capabilities.

[0006] In order to solve the above-mentioned problems, the display system of the present disclosure comprises a first display device that displays an image in a first display area so that it can be viewed at a first display distance relative to the line of sight of the driver of the vehicle; a second display device that displays an image in a second display area different from the first display area so that it can be viewed at a second display distance that is greater than the first display distance relative to the line of sight of the driver; and a display control unit that performs a recognition-increasing process that displays a warning image in the second display area if a first condition is met, and moves and displays the warning image in the first display area if a second condition is met after the first condition is met, which is a situation with a higher level of warning than the first condition, or a recognition-decreasing process that displays the warning image in the first display area if a second condition is met, and moves and displays the warning image in the second display area if the first condition is met after the second condition is met.

[0007] The display system of the present disclosure has excellent information transmission properties.

[0008] 1 is a diagram showing an example of the system configuration of a display system according to an embodiment; FIG. 2 is a diagram showing an example of display by two displays; FIG. 3 is a flowchart illustrating a recognition level increasing process executed by a main control unit; FIG. 4 is a flowchart illustrating a recognition level decreasing process executed by a main control unit; FIG. 5 is an explanatory diagram showing an example of a display before execution of a recognition level decreasing process as a first specific example; FIG. 6 is an explanatory diagram showing an example of a display of a warning image in step S12 of a recognition level decreasing process as a first specific example; FIG. 7 is an explanatory diagram showing another example of a display of a warning image in step S12 of a recognition level decreasing process as a first specific example; FIG. 8 is an explanatory diagram showing an example of a display of a warning image in step S14 of a recognition level decreasing process as a first specific example; FIG. 9 is an explanatory diagram showing an example of a display of a warning image in step S4 of a recognition level increasing process as a first specific example; FIG. 10 is an explanatory diagram showing an example of a display of a warning image in step S2 of a recognition level increasing process as a second specific example; FIG. 11 is an explanatory diagram showing another example of a display of a warning image in step S2 of a recognition level increasing process as a second specific example; FIG. 12 is an explanatory diagram showing an example of a display of a warning image in step S4 of a recognition level increasing process as a second specific example; An explanatory diagram showing an example of the display of a warning image in step S4 of the recognition level increase processing as a fourth specific example. An explanatory diagram showing an example of the display of a warning image in step S2 of the recognition level increase processing as a fifth specific example. An explanatory diagram showing an example of the display of a warning image in step S2 of the recognition level increase processing as a fifth specific example. An explanatory diagram showing an example of the display of a warning image in step S4 of the recognition level increase processing as a fifth specific example.

[0009] An embodiment of a display system according to the present disclosure will be described with reference to the accompanying drawings. The display system according to the present disclosure can be applied to, for example, a display system mounted on a vehicle such as an automobile or a motorcycle, or a ship, agricultural machinery, or construction machinery. In this embodiment, the display system according to the present disclosure will be described using an example in which the display system according to the present disclosure is mounted on a vehicle and has two head-up displays (HUDs) that display required information based on various information acquired from the vehicle.

[0010] Fig. 1 is a diagram showing an example of the system configuration of a display system 10 according to this embodiment. Fig. 2 is a diagram showing an example of display using two displays.

[0011] In the following description, "front," "rear," "upper," "lower," "right," and "left" follow the definitions of "Fr.", "Re.", "To.", "Bo.", "R," and "L" in Figures 1 and 2.

[0012] The display system 10 is mounted in an instrument panel 2 of a vehicle 1 (host vehicle). The display system 10 includes an upper HUD 20, a lower HUD 30, and a main control unit 40.

[0013] The upper HUD 20 (first display) is disposed forward of the steering wheel 5 and irradiates display light L1 onto the windshield 3. The reflected display light L1 is reflected by the windshield 3 toward the driver 4, thereby allowing the driver 4 to view an image in the form of a virtual image V1 in front of the vehicle 1. The image displayed by the upper HUD 20 is displayed, for example, in a virtual upper HUD display area 8 (first display area) in Fig. 2 and is viewed superimposed on the view ahead, such as the road surface.

[0014] The lower HUD 30 (second display) is disposed further forward (away from the driver 4) than the upper HUD 20 and irradiates display light L2 onto a light-shielding portion 3a formed around the windshield 3. The light-shielding portion 3a is a portion made of a light-shielding color such as black, made of black ceramics or the like. The light-shielding portion 3a is formed for the purposes of preventing deterioration of the adhesive that secures the windshield 3 to the vehicle 1 due to sunlight, concealing the adhesive, and improving the design. The reflected display light L2 is reflected by the light-shielding portion 3a toward the driver 4, thereby allowing the driver 4 to view an image formed by a virtual image V2 in front of the vehicle 1. The image displayed by the lower HUD 30 is displayed, for example, in a virtual lower HUD display area 9 (second display area) different from the upper HUD display area 8 in FIG. 2 and is viewed forward of the light-shielding portion 3a.

[0015] The upper HUD 20 displays an image such that the image formed by the virtual image V1 is viewed at a distance d1 (first display distance) in the vertical direction from the line of sight 4a of the driver 4, which is assumed to be in a normal state (during driving). The lower HUD 30 displays an image such that the image formed by the virtual image V2 is viewed at a distance d2 (second display distance) from the line of sight 4a of the driver 4, which is greater than the distance d1. That is, the distance the driver 4 moves to shift the line of sight 4a to the image formed by the display light L2 is greater than the distance the driver moves to shift the line of sight 4a to the image formed by the display light L1. In other words, the angle θ2 formed between the direction of the line of sight 4a and the line of sight for viewing the image formed by the virtual image V2 is greater than the angle θ1 formed between the direction of the line of sight 4a and the line of sight for viewing the image formed by the virtual image V1. Therefore, the driver 4 views the image displayed by the lower HUD 30 at a position farther from the line of sight 4 a than the image displayed by the upper HUD 20 , below the image displayed by the upper HUD 20 .

[0016] In this embodiment, the upper HUD 20 forms the virtual image V1 in front of the virtual image V2 formed by the lower HUD 30. That is, the image formed by the virtual image V1 is viewed from a position farther from the driver 4 in the front-to-rear direction, and the image formed by the virtual image V2 is viewed from a position closer to the driver 4 in the front-to-rear direction.

[0017] The display surfaces of the upper HUD display area 8 and the lower HUD display area 9 are surfaces having four sides: top, bottom, left, and right. For example, the bottom sides 8a, 9a and the top sides 8b, 9b are sides that are approximately parallel to the left-right direction. The left sides 8c, 9c and the right sides 8d, 9d are surfaces that are set at any angle relative to the up-down direction. For example, the display surfaces are formed so that the left sides 8c, 9c and the right sides 8d, 9d are surfaces that are aligned along the up-down direction (surfaces perpendicular to the road surface), inclined at a predetermined angle relative to the up-down direction (surfaces inclined relative to the road surface), or surfaces that are aligned along the front-to-rear direction (surfaces that are superimposed (approximately parallel) to the road surface). Alternatively, the display surfaces may be surfaces that are formed so that the left sides 8c, 9c and the right sides 8d, 9d are curved so that the side closer to the viewer is aligned along the up-down direction and curves along the front-to-rear direction as the distance increases. A display surface formed on a surface other than perpendicular to the road surface may display an image with a sense of depth, with the display distance between the driver 4 and the virtual image varying depending on the display position on the display surface. For example, if the display surface is a surface inclined such that the left sides 8c, 9c and right sides 8d, 9d are inclined so that the upper sides 8b, 9b are positioned forward relative to the lower sides 8a, 9a, the driver 4 can perceive depth on the display surface.

[0018] Furthermore, information regarding the line of sight 4a (viewpoint) of the driver 4 for calculating the display distance of the image, etc. may be set in advance and stored in the main control unit 40, etc., or if the vehicle 1 or the display system 10 has a sensor that detects the viewpoint of the driver 4, it may be detected by this sensor.

[0019] The upper HUD 20 includes a display 21 , a concave mirror 22 , a housing 24 , and an upper HUD display control unit 25 .

[0020] The display 21 emits display light L1 toward the concave mirror 22. The display 21 is, for example, a TFT (Thin Film Transistor) type liquid crystal display or an organic EL (Electroluminescence) display. The display 21 may also include a projector and a screen that forms a display surface.

[0021] The concave mirror 22 reflects the display light L1 emitted by the display 21 toward the windshield 3. The concave mirror 22 functions as a magnifying mirror, and enlarges the image displayed on the display 21 and reflects it toward the windshield 3. In other words, the driver 4 sees an enlarged version of the image displayed on the display 21.

[0022] The housing 24 supports the concave mirror 22, the display 21, and a control board on which the upper HUD display control unit 25 is mounted inside the housing 24.

[0023] The upper HUD display control unit 25 has a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and executes predetermined arithmetic processing in accordance with a program written in the ROM. Specifically, the upper HUD display control unit 25 controls the display 21 to display a required image based on instructions from the main control unit 40.

[0024] The lower HUD 30 includes a display 31 , a housing 34 , and a lower HUD display control unit 35 .

[0025] The display 31 emits display light L2 directly to the light-shielding portion 3 a outside the housing 34. The display 31 has a configuration similar to that of, for example, the upper HUD 20. This allows the driver 4 to view an image displayed on the display 31 and reflected by the light-shielding portion 3 a.

[0026] The housing 34 supports a control board on which the display 31 and the lower HUD display control unit 35 are mounted inside the housing 34 .

[0027] The lower HUD display control unit 35 has a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and executes predetermined arithmetic processing in accordance with a program written in the ROM. Specifically, the lower HUD display control unit 35 controls the display 31 to display a required image based on instructions from the main control unit 40.

[0028] The main control unit 40 controls the upper HUD 20 and the lower HUD 30, particularly based on information acquired from each part of the vehicle 1, which will be described later. The main control unit 40 has a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and executes predetermined arithmetic processing and display control processing, which will be described later, in accordance with a program written in the ROM.

[0029] In addition to the display system 10, the vehicle 1 also includes a surrounding information acquisition unit 51, an outside-vehicle information acquisition unit 52, a car navigation system 53, and a vehicle ECU (Electronic Control Unit) 54. Each unit and the main control unit 40 are connected via a CAN (Controller Area Network) bus 50, for example.

[0030] The surrounding information acquisition unit 51 acquires information about the surroundings (external) of the vehicle 1. The surrounding information acquisition unit 51 performs communication between the vehicle 1 and a wireless network, between the vehicle 1 and other vehicles, between the vehicle 1 and pedestrians, and between the vehicle 1 and roadside infrastructure. For example, the surrounding information acquisition unit 51 includes a communication module capable of directly accessing a wide area network (WAN), a communication module for communicating with an external device (such as a mobile router) that can access the WAN, or an access point of a public wireless local area network (LAN), and performs Internet communication. The surrounding information acquisition unit 51 also includes a wireless communication module that complies with a predetermined wireless communication standard. Furthermore, the surrounding information acquisition unit 51 has a communication device that wirelessly communicates with roadside infrastructure, and acquires object information and traffic information from, for example, a base station of a driving safety support system (DSSS) via a roadside wireless device installed as infrastructure.

[0031] The outside-vehicle information acquisition unit 52 detects the contents and positions of objects such as people, structures, other vehicles 1, and the like that exist in the external environment around the vehicle 1 on all sides above, below, before, after, and to the left and right of the vehicle 1. The outside-vehicle information acquisition unit 52 is, for example, a stereo camera that captures images of the scenery around the vehicle 1, a distance measurement sensor such as LIDAR (Laser Imaging Detection And Ranging) that measures the distance from the vehicle 1 to an object, a sonar, an ultrasonic sensor, a millimeter-wave radar, or the like that detects objects located around the vehicle 1.

[0032] The car navigation system 53 has a GPS controller that calculates the position of the vehicle 1 based on GPS (Global Positioning System) signals received from artificial satellites, etc. The car navigation system 53 has a memory unit that stores map data, and based on the position information from the GPS controller, reads map data for the area around the current position from the memory unit and determines a guide route to a destination set by the user. The car navigation system 53 outputs information about the current position of the vehicle 1 and the determined guide route to the main control unit 40.

[0033] Furthermore, the car navigation system 53 references map data to output to the main control unit 40 information indicating the names and types of facilities ahead of the vehicle 1, the distance between the facilities and the vehicle 1, etc. The map data associates various information with position data, such as road shape information (lanes, road width, number of lanes, intersections, curves, branching roads, etc.), traffic information regarding road signs such as speed limits, traffic regulations such as road closures, alternating one-way traffic, and speed restrictions, and information about each lane if there are multiple lanes. The car navigation system 53 outputs this information to the main control unit 40. Note that the car navigation system 53 is not limited to being mounted on the vehicle 1, but may be realized by a mobile terminal (e.g., a smartphone or a tablet PC (Personal Computer)) with a car navigation function that communicates with the main control unit 40 via wired or wireless communication.

[0034] The vehicle ECU 54 acquires vehicle information necessary for the running of the vehicle 1, such as vehicle speed and engine rotation speed, from various sensors provided in the vehicle 1, and controls the operation of the vehicle 1. The vehicle ECU 54 outputs required vehicle information, such as vehicle speed and warning information about the vehicle 1 itself (e.g., low fuel, abnormal engine oil pressure), to the main control unit 40.

[0035] Next, a detailed description will be given of image display control by the display system 10. When a predetermined condition is satisfied, the display system 10 executes a recognition level increasing process or a recognition level decreasing process.

[0036] FIG. 3 is a flowchart illustrating a recognition level increasing process executed by the main control unit 40. FIG. 4 is a flowchart illustrating a recognition level decreasing process executed by the main control unit 40. The recognition level increasing process is a process in which, if a first condition is met (YES in step S1), a warning image is displayed in the lower HUD display area 9 (step S2), and, if a second condition, which is a situation with a higher level of warning than the first condition, is met after the first condition is met (YES in step S3), the warning image is moved to the upper HUD display area 8 and displayed therein (step S4). The recognition level decreasing process is a process in which, if the second condition is met (YES in step S11), a warning image is displayed in the upper HUD display area 8 (step S12), and, if the first condition is met after the second condition is met (YES in step S13), the warning image is moved to the lower HUD display area 9 and displayed therein (step S14).

[0037] That is, the display system 10 in this embodiment has an upper HUD 20 that displays an image at a position (close position) requiring a small amount of line-of-sight movement from the line of sight 4a of the driver 4, making it easy for the driver 4 to recognize, and a lower HUD 30 that displays an image at a position (far position) requiring a larger amount of line-of-sight movement from the line of sight 4a than the upper HUD 20, making it relatively difficult for the driver 4 to recognize. The display system 10 links the upper HUD 20 and lower HUD 30, and in situations where the level of warning is high, displays an image on the upper HUD 20, which is easy to recognize, thereby enabling appropriate information to be conveyed to the driver 4. The recognition level increasing process or the recognition level decreasing process in FIGS. 3 and 4 will be described below using first to fourth specific examples.

[0038] [First Specific Example] A first specific example is a recognition reduction process that is executed when the upper HUD 20 and the lower HUD 30 display warning images (sign images 87 and 97 in FIGS. 5 to 9 ) indicating traffic information ahead. Hereinafter, an example will be described in which the traffic information is a road sign indicating a speed limit.

[0039] FIG. 5 is an explanatory diagram showing a display example before execution of the recognition level reduction process as a first specific example.

[0040] The lower HUD display area 9 displays a host vehicle image 91 showing the vehicle 1, a vehicle speed image 92 related to vehicle speed information acquired from the vehicle ECU 54, an image related to information related to vehicles surrounding the vehicle 1 acquired from the outside information acquisition unit 52, etc., and a lane marking image 94 showing information related to lane markings of the driving lane in which the vehicle 1 is traveling. The image related to information related to the surrounding vehicles includes, for example, a rear vehicle image 95 related to information related to a rear vehicle traveling behind the vehicle 1 and a front vehicle image 96 related to information related to a front vehicle traveling in front, and shows the relative positional relationship with the host vehicle image 91. The rear vehicle image 95 and the front vehicle image 96 are displayed when there are a rear vehicle and a front vehicle.

[0041] Additionally, the lower HUD display area 9 displays, at required timing, sign images 97 related to information about road signs currently applied to the traveling vehicle 1. The content of the road signs may be regulatory signs indicating prohibitions such as no overtaking, or information about other road signs. The lower HUD display area 9 may display multiple sign images 97. In this case, it is preferable that sign images 97 related to speed limits of high importance are displayed in the center of the lower HUD display area 9, in an area that is easily recognized by the driver 4. At this time, no image is displayed in the upper HUD display area 8 because there is no information to prompt recognition.

[0042] The main control unit 40 determines whether a second condition is satisfied, that is, whether the surrounding information acquisition unit 51 or the outside-vehicle information acquisition unit 52 detects traffic information related to road signs and traffic regulation information located ahead of the vehicle 1, or whether the car navigation system 53 acquires traffic information related to road signs and traffic regulation information located ahead of the vehicle 1 (step S11 in FIG. 4 ). If the main control unit 40 determines that the second condition is not satisfied (NO in step S11), it waits until the second condition is satisfied. If the main control unit 40 determines that the second condition is satisfied (YES in step S11), it controls the upper HUD display control unit 25 to display a sign image 87 as a warning image in the upper HUD display area 8 (step S12). FIG. 6 is an explanatory diagram showing an example of the display of a warning image in step S12 of the recognition reduction process as a first specific example.

[0043] The upper HUD display control unit 25 starts displaying the sign image 87 near the upper edge 8b of the upper HUD display area 8. The upper HUD display control unit 25 preferably displays the sign image 87 in a color and shape that resembles a regulatory sign related to a speed limit. As the vehicle 1 approaches a road sign as the vehicle 1 travels, the upper HUD display control unit 25 moves the sign image 87 within the upper HUD display area 8 so that the sign image 87 approaches the lower HUD display area 9. In this way, the upper HUD display control unit 25 makes the driver 4 aware that a road sign that will soon be applied is approaching the vehicle 1. Specifically, the upper HUD display control unit 25 makes the driver 4 aware that the speed limit (100 km / h) associated with the sign image 97 displayed in the lower HUD display area 9 will be changed to the speed limit (80 km / h) associated with the sign image 87. The upper HUD display control unit 25 moves the sign image 97 to the vicinity of the lower side 8a of the upper HUD display area 8 at the timing when the speed limit is applied, that is, before the vehicle 1 passes the road sign.

[0044] The upper HUD display control unit 25 moves the sign image 97 in a vertically linear manner directly above (aligning the horizontal position of) the position where the sign image 97 is displayed in the lower HUD display area 9. FIG. 7 is an explanatory diagram showing another display example of the warning image in step S12 of the recognition reduction processing as a first specific example. As shown in FIG. 7 , the upper HUD display control unit 25 may move the sign image 97 in a vertically linear manner diagonally downward from the horizontal center toward the position where the sign image 97 is displayed in the lower HUD display area 9. By moving the sign image 87 toward the sign image 97 in the lower HUD display area 9 in this manner, the upper HUD display control unit 25 can improve the sense of linkage between the displays of the upper HUD 20 and the lower HUD 30 when moving the sign image 87 from the upper HUD display area 8 to the lower HUD display area 9.

[0045] At this time, the upper HUD display control unit 25 preferably moves the sign image 87 from the upper side 8b to the lower side 8a while increasing the visibility of the sign image 87, in order to further enhance awareness that a road sign is approaching. For example, the upper HUD display control unit 25 preferably increases the visibility by changing various elements of the sign image 87, such as chromaticity, saturation, brightness, luminance, transparency, and size, to increase the visibility and make the driver aware that a road sign is approaching. The upper HUD display control unit 25 may also make the driver aware that a road sign is approaching by flashing the sign image 87 and moving it at an increasing flashing rate, or by gradually increasing the speed of its movement from the upper side 8b to the lower side 8a.

[0046] The main control unit 40 determines whether the first condition, that is, the distance between the road sign and the vehicle 1 is equal to or less than a predetermined distance, is satisfied (step S13 in FIG. 4 ). The predetermined distance is a distance shorter than the distance between the road sign and the vehicle 1 when the road sign is detected. That is, the main control unit 40 determines whether the sign image 87 displayed in the upper HUD display area 8 is sufficiently recognized by the driver 4, resulting in a lower level of warning than when the second condition is satisfied, and whether the time has come (or is approaching) for the speed limit indicated by the road sign to be applied. If the main control unit 40 determines that the first condition is not satisfied (NO in step S13), the main control unit 40 maintains the display of the sign image 87 in the upper HUD display area 8.

[0047] On the other hand, if the main control unit 40 determines that the first condition is met (YES in step S13), it controls the upper HUD display control unit 25 to turn off the display of the sign image 87 that has moved to the vicinity of the bottom edge 8a of the upper HUD display area 8. At the same time, it controls the lower HUD display control unit 35 to display the sign image 97 in the lower HUD display area 9. Here, Figure 8 is an explanatory diagram showing an example of the display of a warning image in step S14 of the recognition reduction processing as a first specific example.

[0048] The lower HUD display control unit 35 replaces the currently displayed sign image 97 with an image similar to the sign image 87 displayed in the upper HUD display area 8. At this time, the lower HUD display control unit 35 may, for example, perform an effect that makes it appear as if the sign image 87 is falling downward from the upper HUD display area 8. The lower HUD display control unit 35 may also replace the old and new sign images 97 in a linked manner, such as by rotating and replacing the already displayed sign image 97. Furthermore, the lower HUD display control unit 35 may perform an effect such as flashing the sign image 97 at the time of replacement, to notify the driver 4 that the sign image 97 has been replaced.

[0049] As a result, the main control unit 40 can make the sign image 87 displayed in the upper HUD display area 8 appear as if it has moved to the lower HUD display area 9. That is, the main control unit 40 displays the sign image 87 in the upper HUD display area 8 to warn the driver 4 in order to increase the recognizability of the road sign that will be applied in the future. Furthermore, after the road sign is made recognizable to the driver 4 and is actually applied, the main control unit 40 displays the sign image 97 in the lower HUD display area 9 to reduce the recognizability. That is, the main control unit 40 notifies the driver 4 in the lower HUD display area 9 without reducing forward visibility. As a result, the display system 10 can effectively utilize the upper HUD 20 and the lower HUD 30 to appropriately convey necessary information to the driver 4.

[0050] Although the above description uses road signs related to speed limits as examples of the sign images 87 and 97, multiple types of road signs may be displayed as the sign images 87 and 97 in the upper HUD display area 8 and the lower HUD display area 9. For example, if the lower HUD display area 9 displays a speed limit sign image 97 and a no-overtaking sign image, and there is a speed limit sign for changing the current speed limit and a road sign of the same type as the no-overtaking sign image (e.g., a no-parking sign) ahead, the upper HUD display control unit 25 may display multiple sign images located ahead in the upper HUD display area 8 (step S12). When moving each sign image, the upper HUD display control unit 25 moves it diagonally downward toward the corresponding sign image of the same type in the lower HUD display area 9, thereby creating a sense of depth and improving the visual effect.

[0051] As another example, when a sign image 87 is displayed in the upper HUD display area 8, if the vehicle 1 follows the content of the sign image 87, the main control unit 40 may determine that the driver 4 has recognized the sign image 87 and turn off the sign image 87 in the upper HUD display area 8. Specifically, when a sign image 87 related to an 80 km / h speed limit is displayed in the upper HUD display area 8, if the vehicle speed drops below 80 km / h, the upper HUD display control unit 25 turns off the sign image 87.

[0052] When turning off the sign image 87, the upper HUD display control unit 25 may display the current vehicle speed together with the sign image 87 to notify the driver that the vehicle speed is within the speed limit associated with the sign image 87. Additionally or alternatively, when turning off the sign image 87, the upper HUD display control unit 25 may perform a visual effect such as making the sign image 87 glow, bold, flash, rotate, or bounce, thereby further notifying the driver that the speed is within the speed limit. The turned-off sign image 87 is then displayed as a sign image 97 in the lower HUD display area 9.

[0053] Furthermore, when the main control unit 40 detects that the vehicle speed does not conform to the sign image 97 displayed in the lower HUD display area 9, the main control unit 40 may execute a recognition level increasing process.

[0054] The main control unit 40 displays the sign image 97 currently applied to the vehicle 1 in the lower HUD display area 9 (YES in step S1, step S2 in FIG. 3). The main control unit 40 determines whether a second condition, that is, the vehicle 1 deviates from the current speed limit displayed by the sign image 97, is satisfied (step S3 in FIG. 3). For example, the main control unit 40 determines whether the speed limit is exceeded or the set speed of the adaptive cruise control exceeds the speed limit.

[0055] If the main control unit 40 determines that the second condition is satisfied (YES in step S3), it controls the upper HUD display control unit 25 to move the sign image 97 displayed in the lower HUD display area 9 to the upper HUD display area 8 and display it as the sign image 87 (step S4). FIG. 9 is an explanatory diagram showing a first example of a warning image display in step S4 of the recognition enhancement process. At this time, the lower HUD display control unit 35 maintains the display of the sign image 97 displayed in the lower HUD display area 9. By displaying the sign image 97 in the upper HUD display area 8 as the sign image 87, the display system 10 can improve the recognition of the warning and appropriately communicate it to the driver 4.

[0056] [Second Specific Example] The second specific example is a recognition enhancement process that is executed when the upper HUD 20 and the lower HUD 30 display warning images (rear approaching vehicle images 88, 98 in Figures 10 to 12) that show information about vehicles traveling around the vehicle 1 (host vehicle) and rearward vehicles (other vehicles) traveling on the left and right sides of the vehicle 1.

[0057] The main control unit 40 determines whether a first condition, that is, that the surrounding information acquisition unit 51 or the outside-of-vehicle information acquisition unit 52 has detected an approaching rear vehicle, is satisfied (step S1 in FIG. 3 ). The main control unit 40 may determine that the first condition is satisfied, for example, when the distance (inter-vehicle distance) between the vehicle 1 and the rear vehicle is equal to or less than a first distance, or when the approaching speed of the rear vehicle is greater than a predetermined value. The first distance is, for example, a distance at which it is determined that a rear vehicle is approaching and is about to pass the vehicle 1, and that a warning to that effect should be given to the driver 4, and is determined to be an arbitrarily determined distance. If the main control unit 40 determines that the first condition is not satisfied (NO in step S1), it waits until the first condition is satisfied.

[0058] When the main control unit 40 determines that the first condition is satisfied (YES in step S1), it controls the lower HUD display control unit 35 to display an image showing information about the approaching rear vehicle (warning image, hereinafter referred to as "rear approaching vehicle image 98") in the lower HUD display area 9 (step S2). Here, Fig. 10 is an explanatory diagram showing an example of the display of the warning image in step S2 of the recognition level increasing process as a second specific example. In the second specific example, an example will be described in which a rear vehicle is traveling to the left rear.

[0059] The lower HUD display control unit 35 displays the rear approaching vehicle image 98 in a left area of ​​the lower HUD display area 9. The lower HUD display control unit 35 displays the rear approaching vehicle image 98 so that the positional relationship between the rear vehicle and the vehicle 1 can be easily recognized by aligning the top, bottom, left, and right sides of the lower HUD display area 9 with the front, back, left, and right sides of the vehicle 1. In other words, the lower HUD display control unit 35 starts displaying the rear approaching vehicle image 98 from the lower left of the lower HUD display area 9.

[0060] The lower HUD display control unit 35 displays the rear approaching vehicle image 98, for example, as an image using a gradation that has a reference point at the center of the image and becomes lighter the farther away from the reference point. Preferably, the lower HUD display control unit 35 displays the rear approaching vehicle image 98 in front of layers such as the vehicle speed image 92 that are always displayed in the lower HUD display area 9, thereby making it easier for the driver 4 to recognize the rear approaching vehicle image 98.

[0061] The main control unit 40 determines whether the following conditions are met: the distance between the vehicle 1 and the vehicle behind is equal to or shorter than the second distance, the vehicle behind is closer than under the first condition, and the level of warning is high. The second distance is shorter than the first distance used to determine whether the first condition is met. If the main control unit 40 determines that the above conditions are not met, it maintains the display of the image 98 of the vehicle approaching from behind in the lower HUD display area 9.

[0062] On the other hand, if the main control unit 40 determines that the above condition is satisfied, it controls the lower HUD display control unit 35 to move and display the rear approaching vehicle image 98 in the lower HUD display area 9 within the lower HUD display area 9 so that the image approaches the upper HUD display area 8. Here, Figure 11 is an explanatory diagram showing another display example of the warning image in step S2 of the recognition level increasing process as a second specific example.

[0063] The lower HUD display control unit 35 moves the rear approaching vehicle image 98 in accordance with the direction of the relative speed of the rear vehicle. Specifically, the lower HUD display control unit 35 gradually moves the rear approaching vehicle image 98 upward and to the right, thereby making the driver perceive that the rear approaching vehicle is traveling from behind to ahead toward the vehicle 1. Furthermore, the lower HUD display control unit 35 moves the rear approaching vehicle image 98 toward the lower left edge of the upper HUD display area 8, thereby improving the sense of linkage between the displays of the upper HUD 20 and the lower HUD 30 when the rear approaching vehicle image 98 is later moved from the lower HUD display area 9 to the upper HUD display area 8. Furthermore, from the standpoint of visibility, the lower HUD display control unit 35 switches the rear approaching vehicle image 98, which has been displayed in front of layers such as the vehicle speed image 92, to being displayed behind the layers.

[0064] When the rear approaching vehicle image 98 moves, the lower HUD display control unit 35 preferably changes the representation of the rear approaching vehicle image 98 as appropriate to convey the status of the rear approaching vehicle. For example, the lower HUD display control unit 35 may break the isotropy of the rear approaching vehicle image 98 and display it as if it is extending in the direction of movement to create the illusion that the rear approaching vehicle is moving. Furthermore, the lower HUD display control unit 35 may vary the area of ​​the rear approaching vehicle image 98 or the movement speed of the rear approaching vehicle image 98 in accordance with the relative speed and distance to the rear approaching vehicle. Furthermore, to improve the visibility of the rear approaching vehicle image 98, the lower HUD display control unit 35 may reduce or move the vehicle speed image 92, which is always displayed, to the right to create space for displaying the rear approaching vehicle image 98. Furthermore, as shown in FIG. 11 , the upper HUD display control unit 25 may display the rear approaching vehicle image 88 in the upper HUD display area 8 as a notice of the warning image to be displayed under the second condition, along with text, sound, or the like.

[0065] The main control unit 40 determines whether a second condition is satisfied, for example, that the inter-vehicle distance is equal to or less than a third distance, or that the vehicle approaching from behind is approaching further than when the rear approaching vehicle image 98 started to move and is in a situation where the level of warning is high enough to assume that the vehicle will soon overtake the vehicle 1 (step S3). The third distance is a distance smaller than the first distance and the second distance used to determine the first condition. If the main control unit 40 determines that the second condition is not satisfied (NO in step S3), the main control unit 40 maintains the display of the rear approaching vehicle image 98 in the lower HUD display area 9.

[0066] On the other hand, if the main control unit 40 determines that the second condition is satisfied (YES in step S3), it controls the lower HUD display control unit 35 to move the rear approaching vehicle image 98 displayed in the lower HUD display area 9 to the vicinity of the upper edge 9b and then turn it off. The main control unit 40 also controls the upper HUD display control unit 25 to move the rear approaching vehicle image 98 displayed in the lower HUD display area 9 toward the upper HUD display area 8 and display it (step S4). The timing of turning off the rear approaching vehicle image 98 by the lower HUD display control unit 35 and the timing of displaying the rear approaching vehicle image 88 by the upper HUD display control unit 25 may be simultaneous, may overlap, or may be slightly spaced apart. Furthermore, it is preferable that the main control unit 40 calculates the relative speed from the distance to the rear vehicle, and that the rear approaching vehicle image 98 reach the vicinity of the upper edge 9b of the lower HUD display area 9 when the second condition is satisfied.

[0067] FIG. 12 is an explanatory diagram showing a display example of a warning image in step S4 of the recognition level increasing process as a second specific example.

[0068] The upper HUD display control unit 25 displays the rear approaching vehicle image 88 on an extension of the movement direction of the rear approaching vehicle image 98 in the lower HUD display area 9, just as the rear approaching vehicle image 98 displayed in the lower HUD display area 9 has moved to the upper HUD display area 8. In other words, the upper HUD display control unit 25 displays the rear approaching vehicle image 88 as a warning image near the lower left edge of the upper HUD display area 8.

[0069] The upper HUD display control unit 25 can indicate the speed direction of the rear vehicle relative to the vehicle 1 by using an image that can indicate an arrow-shaped direction, as shown in FIG. 12 . The upper HUD display control unit 25 can intuitively convey the degree of approach to the driver 4 by changing the color of the rear approaching vehicle image 88 depending on the distance to the rear vehicle. For example, when the rear vehicle is closest to the vehicle 1, the upper HUD display control unit 25 can notify the driver 4 that the rear vehicle is closest by displaying the rear approaching vehicle image 88 in a warning color such as red. The upper HUD display control unit 25 can also convey the relative speed and inter-vehicle distance to the rear vehicle to the driver 4 by using the length of the rear approaching vehicle image 88 (length of the arrow), etc. For example, the upper HUD display control unit 25 can increase the length of the arrow when the rear vehicle is approaching at high speed.

[0070] At this time, the lower HUD display control unit 35 may indicate the presence of a rear vehicle by displaying a rear vehicle image 95 in the lower HUD display area 9. Furthermore, when the main control unit 40 detects that the driver 4 has operated the turn signal in the direction in which the rear vehicle is traveling while the rear approaching vehicle image 88 is displayed in the upper HUD display area 8, the main control unit 40 may, for example, in addition to or instead of the rear approaching vehicle image 88, notify the upper HUD display area 8 that a lane change is not permitted.

[0071] When a rear vehicle has overtaken vehicle 1 and is deemed to be within the field of view of driver 4, the main control unit 40 determines that it is not necessary for driver 4 to be aware of this and turns off the display of the rear approaching vehicle image 88 in the upper HUD display area 8. Furthermore, when the rear vehicle has changed lanes into the driving lane of vehicle 1 and is traveling ahead of vehicle 1, the main control unit 40 may indicate this using the rear approaching vehicle image 88 in the upper HUD display area 8. For example, the upper HUD display control unit 25 indicates that the current position of the rear approaching vehicle is ahead of vehicle 1 by bending and extending the tip of the rear approaching vehicle image 88 toward the center in the left-right direction of the upper HUD display area 8.

[0072] As a result, the main control unit 40 can make it appear as if the rear approaching vehicle image 98 displayed in the lower HUD display area 9 has moved to the upper HUD display area 8. That is, the main control unit 40 displays the rear approaching vehicle image 98 in the lower HUD display area 9 to give the driver 4 a warning. In addition, in order to further increase the awareness of a rear vehicle that is predicted to overtake the vehicle 1, the rear approaching vehicle image 88 is displayed in the upper HUD display area 8 at the stage when the vehicle is actually about to overtake, thereby increasing the awareness. As a result, the display system 10 can effectively utilize the upper HUD 20 and the lower HUD 30 to appropriately convey necessary information to the driver 4.

[0073] If there are multiple vehicles behind, the main control unit 40 may continue to display the rear approaching vehicle images 98, 88 displayed in the lower HUD display area 9 and the upper HUD display area 8 in the same display mode until the last of the multiple rear vehicles overtakes the vehicle 1. As a result, the main control unit 40 continues to display the rear approaching vehicle image 88 in the upper HUD display area 8, and turns off the rear approaching vehicle image 88 in the upper HUD display area 8 when all rear vehicles have disappeared, thereby alerting the driver 4 to the presence of vehicles behind during this time.

[0074] Furthermore, if the first and second conditions are no longer satisfied, for example, if the rearward approaching vehicle decelerates or changes lanes into the vehicle 1's driving lane, the main control unit 40 may turn off the display of the rearward approaching vehicle images 88, 98 at that time, or may notify the driver 4 of this by changing the display mode of the rearward approaching vehicle images 88, 98. For example, the main control unit 40 may invert the arrow-shaped rearward approaching vehicle image 88 in the upper HUD display area 8 in the opposite direction (downward) to indicate the relative speed of the rearward approaching vehicle, thereby expressing the vehicle heading toward the vehicle 1. In this case, the upper HUD display area 8 may not simply switch the rearward approaching vehicle image 88, but may also switch the displayed rearward approaching vehicle image 88 by rotating it around a vertical or horizontal axis. Furthermore, it is preferable that the upper HUD display area 8 display the rearward approaching vehicle image 88 with reduced visibility compared to before switching, for example by reducing the brightness of the rearward approaching vehicle image 88. As a result, the direction of the arrow points to the lower HUD display area 9, and the main control unit 40 can prompt the driver 4 to view the lower HUD display area 9 instead of the upper HUD display area 8 from now on.

[0075] [Third Specific Example] The third specific example is a recognition enhancement process that is executed when the upper HUD 20 and the lower HUD 30 are a vehicle 1 traveling around the vehicle 1 (host vehicle) and display a warning image (forward vehicle images 86, 96 in Figure 13) that shows information about a forward vehicle (other vehicle) traveling in front of the vehicle 1.

[0076] The main control unit 40 determines whether a first condition, that is, that the surrounding information acquisition unit 51 or the vehicle exterior information acquisition unit 52 has detected a vehicle ahead, is satisfied (step S1 in FIG. 3). The first condition is, for example, a situation in which the distance between the vehicle 1 and the vehicle ahead is appropriate, but the driver 4 should be made aware of the presence of the vehicle ahead and a warning should be issued. If the main control unit 40 determines that the first condition is not satisfied (NO in step S1), it waits until the first condition is satisfied.

[0077] When the main control unit 40 determines that the first condition is satisfied (YES in step S1), it controls the lower HUD display control unit 35 to display an image showing information about a forward vehicle (a warning image, hereinafter referred to as a "forward vehicle image 96") in the lower HUD display area 9 (step S2). The main control unit 40 displays the forward vehicle image 96 in the same manner as in the lower HUD display area 9 shown in Fig. 5. The forward vehicle image 96 is shown as if the vehicle is traveling ahead of the host vehicle image 91.

[0078] The main control unit 40 determines whether a second condition is met, for example, that the inter-vehicle distance is equal to or less than a second distance, and the vehicle is closer to the vehicle ahead than the vehicle ahead under the first condition (step S3). The second distance is shorter than the distance at the time of determining the first condition, and the second condition is a situation requiring a higher level of warning than the first condition. If the main control unit 40 determines that the second condition is not met (NO in step S3), the main control unit 40 maintains the display of the forward vehicle image 96 in the lower HUD display area 9.

[0079] On the other hand, if the main control unit 40 determines that the second condition is satisfied (YES in step S3), it controls the lower HUD display control unit 35 to move the forward vehicle image 96 displayed in the lower HUD display area 9 toward the upper HUD display area 8 (step S4). At this time, the lower HUD display control unit 35 may increase the visibility of the forward vehicle image 96 displayed in the lower HUD display area 9 and then move the forward vehicle image 96 toward the upper HUD display area 8. The lower HUD display control unit 35 increases the visibility, for example, by displaying the forward vehicle image 96 in a warning color such as red. Furthermore, after moving the forward vehicle image 96, the lower HUD display control unit 35 may maintain or decrease the increased visibility. If the lower HUD display control unit 35 has decreased the visibility, it is preferable that the lower HUD display control unit 35 restores the visibility again after the forward vehicle image 96 is displayed in the upper HUD display area 8.

[0080] Thereafter, or simultaneously therewith, the main control unit 40 controls the upper HUD display control unit 25 to display a forward vehicle image 86 as a warning image in the upper HUD display area 8, thereby moving and displaying the forward vehicle image 96 from the lower HUD display area 9 (step S4). Here, Fig. 13 is an explanatory diagram showing an example of display of a warning image in step S4 of the recognition level increasing process as a third specific example.

[0081] The upper HUD display control unit 25 displays the forward vehicle image 86 above the display position in the left-right direction of the forward vehicle image 96 in the lower HUD display area 9, so that the forward vehicle image 96 displayed in the lower HUD display area 9 has moved to the upper HUD display area 8.

[0082] When displaying the forward vehicle image 86, the upper HUD display control unit 25 may move the forward vehicle image 86 from the lower side 8a toward the upper side 8b of the upper HUD display area 8, thereby creating the illusion of the vehicle moving from the lower HUD display area 9. Furthermore, if the up-down direction of the upper HUD display area 8 can express a sense of depth corresponding to the depth and front of the foreground, the upper HUD display control unit 25 can intuitively convey the inter-vehicle distance to the driver 4 by displaying the forward vehicle image 86 so that it fades in at a position corresponding to the actual inter-vehicle distance. Furthermore, the upper HUD display control unit 25 can intuitively convey information about the vehicle 1 to the driver 4 by varying the movement speed when displaying the forward vehicle image 86 in the upper HUD display area 8 and the visibility during fading in depending on the relative speed between the vehicle and the forward vehicle. The upper HUD display control unit 25 may display an image with reduced visibility, such as a blurred image of the forward vehicle image 86, while the forward vehicle image 86 is moving, so long as the driver 4 is able to recognize that the forward vehicle image 86 is moving from the lower HUD display area 9.

[0083] While the second condition is satisfied, the upper HUD display control unit 25 displays the forward vehicle image 86 with increased visibility as the inter-vehicle distance decreases or the approaching speed increases. For example, as shown in FIG. 13 , the upper HUD display control unit 25 changes the display position and the movement speed of the forward vehicle image 86 in accordance with the inter-vehicle distance or the relative speed. When the inter-vehicle distance decreases, the upper HUD display control unit 25 moves the image downward (toward the driver's side) as in a forward vehicle image 86a. When the inter-vehicle distance increases, the upper HUD display control unit 25 moves the image upward (toward the driver's side) as in a forward vehicle image 86b.

[0084] At this time, when the approaching speed between the vehicle 1 and the vehicle ahead is high, the upper HUD display control unit 25 increases the moving speed of the vehicle ahead image 86 more than usual. Furthermore, when the degree of warning to the driver 4 further increases, for example, when the inter-vehicle distance becomes smaller than a predetermined distance, the upper HUD display control unit 25 may increase the visibility of the vehicle ahead image 86 by changing the color of the vehicle ahead image 86 to a warning color or by enlarging the size of the image. Furthermore, when the degree of warning to the driver 4 decreases, the upper HUD display control unit 25 may decrease the visibility by returning the color or size of the vehicle ahead image 86 to its original state.

[0085] When the second condition is no longer satisfied, i.e., when the inter-vehicle distance from the forward vehicle becomes greater than the second distance, the main control unit 40 turns off the display of the forward vehicle image 86 in the upper HUD display area 8. The upper HUD display control unit 25 may turn off the displayed forward vehicle image 86 immediately or may turn it off by fading it out. Note that even if the inter-vehicle distance becomes greater than the second distance, the main control unit 40 may maintain the display of the forward vehicle image 86 in the upper HUD display area 8, as the second condition is satisfied, if, for example, the closing speed is still greater than a predetermined value.

[0086] Thereafter, the main control unit 40 controls the lower HUD display control unit 35 to return to a display mode in which the forward vehicle image 96 is displayed in the same manner as in the lower HUD display area 9 shown in FIG.

[0087] As a result, the main control unit 40 can make it appear as if the forward vehicle image 96 displayed in the lower HUD display area 9 has moved to the upper HUD display area 8. That is, the main control unit 40 first displays the forward vehicle image 96 in the lower HUD display area 9 to warn the driver 4 of the presence of a forward vehicle. Furthermore, after the driver 4 has been made aware of the presence of the forward vehicle, if the degree of warning increases, for example, because the inter-vehicle distance is short or the approaching speed is high, the main control unit 40 displays the forward vehicle image 86 in the upper HUD display area 8 to increase the degree of awareness. As a result, the display system 10 can effectively utilize the upper HUD 20 and the lower HUD 30 in cooperation with each other to appropriately convey necessary information to the driver 4.

[0088] In order to improve the visibility of the forward vehicle image 96, the lower HUD display control unit 35 may hide or reduce the visibility of the vehicle speed image 92, which is always displayed, while the forward vehicle image 86 is displayed in the upper HUD display area 8. Furthermore, when the forward vehicle image 96 is moved from the lower HUD display area 9 to the upper HUD display area 8 and display of the forward vehicle image 86 in the upper HUD display area 8 is started, if another image that will be superimposed on the display of the forward vehicle image 86 is displayed in the upper HUD display area 8, it is preferable that the upper HUD display area 8 displays the forward vehicle image 86 so that it moves behind the layer of the other image. Alternatively, the upper HUD display control unit 25 may temporarily move the other image to a position that is not on the movement path of the forward vehicle image 86 to create space for the forward vehicle image 86, thereby displaying the other image so that they do not overlap. This allows the display linkage between the lower HUD display area 9 and the upper HUD display area 8 to be maintained without reducing the visibility of the other image already displayed.

[0089] [Fourth Specific Example] The fourth specific example is a recognition enhancement process that is executed when the upper HUD 20 and the lower HUD 30 display warning images (the lane marking images 84 and 94 and the warning image 89 in FIG. 14 ) that show information regarding the relationship between the vehicle 1 (host vehicle) and the driving lane in which the vehicle 1 is traveling.

[0090] When the outside-vehicle information acquisition unit 52 detects a lane marking, the main control unit 40 controls the lower HUD display control unit 35 to display a lane marking image 94 in the lower HUD display area 9 as shown in the lower HUD display area 9 in Figure 5. In Figure 5, the lower HUD display control unit 35 displays two lane marking images 94 located on the left and right sides of the vehicle 1, but it may display either one of the lane marking images 94. When the vehicle 1 moves left or right and approaches a lane marking, the main control unit 40 moves the host vehicle image 91 toward the approaching lane marking image 94 in conjunction with the movement of the vehicle 1.

[0091] The main control unit 40 determines whether a first condition, that is, the distance between the vehicle 1 and the lane marking is equal to or less than a first distance, is satisfied (step S1 in FIG. 3). The first condition is, for example, a situation in which there is a high possibility that the vehicle 1 will deviate from the lane marking. If the main control unit 40 determines that the first condition is not satisfied (NO in step S1), the main control unit 40 maintains the display in the lower HUD display area 9.

[0092] On the other hand, if the main control unit 40 determines that the first condition is satisfied (YES in step S1), it controls the lower HUD display control unit 35 to increase the visibility of the lane marking image 94 in the lower HUD display area 9 and notify the driver that there is a high possibility that the vehicle 1 will deviate from the lane marking (step S2). The lower HUD display control unit 35 increases the visibility by highlighting the lane marking image 94 in a warning color such as red or by flashing it.

[0093] The main control unit 40 determines whether a second condition, that is, the distance between the vehicle 1 and the lane marking is equal to or less than a second distance that is smaller than the first distance, is satisfied (step S3). The second condition is a situation in which the degree of warning is higher than under the first condition and the possibility of the vehicle 1 deviating from the lane marking is further increased. The second condition also includes a situation in which part or all of the vehicle 1 is traveling deviating from the lane marking.

[0094] If the main control unit 40 determines that the second condition is not satisfied (NO in step S3), it maintains the display of the lane marking image 94 in the lower HUD display area 9. If the first condition is no longer satisfied, for example, if the distance between the vehicle 1 and the lane marking becomes greater than the first distance, the lower HUD display control unit 35 may return the lane marking image 94 to the display mode before the first condition was satisfied.

[0095] On the other hand, if the main control unit 40 determines that the second condition is satisfied (YES in step S3), it controls the upper HUD display control unit 25 to move the lane marking image 94 displayed in the lower HUD display area 9 to the upper HUD display area 8 and display it therein (step S4). Here, Figure 14 is an explanatory diagram showing an example of the display of a warning image in step S4 of the recognition level increasing process as a fourth specific example.

[0096] The upper HUD display control unit 25 displays the demarcation line image 84 above the left-right display position of the demarcation line image 94 in the lower HUD display area 9, so that the demarcation line image 94 displayed in the lower HUD display area 9 has moved to the upper HUD display area 8.

[0097] For example, the lower HUD display control unit 35 reduces the visibility of the lane line image 94 that was displayed with increased visibility in the lower HUD display area 9 under the second condition, returning it to the lane line image 94 that was displayed under the first condition. The upper HUD display control unit 25 also starts displaying the lane line image 84 in the same display manner as the lane line image 94 that was displayed with increased visibility in the lower HUD display area 9 under the second condition. The upper HUD display control unit 25 starts displaying the lane line image 84 by, for example, moving it a predetermined amount from the bottom edge 8a to the top edge 8b of the upper HUD display area 8. As a result, the lane line image 84 is displayed as if the lane line image 94, which had increased visibility in the lower HUD display area 9, had faded out of the lower HUD display area 9 and faded in (moved) to the upper HUD display area 8.

[0098] In addition, when the upper HUD display control unit 25 starts displaying the dividing line image 84, if there is a high need for a warning, it can increase the degree of warning to the driver 4 by increasing the movement speed within the upper HUD display area 8.

[0099] The upper HUD display control unit 25 also displays a warning image 89 after displaying the lane marking image 84 superimposed on the lane marking image 84, or simultaneously with the lane marking image 84. As shown in FIG. 14 , the warning image is an image that further enhances the visibility of the lane marking image 84 corresponding to a lane marking from which the vehicle 1 may depart or a lane marking from which the vehicle 1 has actually departed. The upper HUD display control unit 25 displays the warning image 89 (pop-up) so that it rises from the lower edge 8 a to the upper edge 8 b of the upper HUD display area 8, or, if the upper HUD display area 8 can express a sense of depth, displays the warning image 89 so that it rises from below to above in the vertical direction of the actual scene. The upper HUD display control unit 25 may link the visibility of the warning image 89 to the degree of warning obtained from, for example, the amount of deviation from the lane marking.

[0100] When the vehicle 1 is not deviating from the lane markings, the upper HUD display control unit 25 displays the lane marking image 84 in approximately the center in the left-right direction of the upper HUD display area 8, thereby superimposing the lane marking image 84 on the lane markings in the actual view. However, when the vehicle 1 is deviating from the lane markings, the upper HUD display control unit 25 needs to display the lane marking image 84 and the warning image 89 (hereinafter sometimes referred to as "lane marking image 84, etc.") shifted from the center in the left-right direction by the amount of deviation in order to superimpose them on the position of the lane markings in the actual view.

[0101] When the upper HUD display control unit 25 displays the lane line image 84, etc., shifted from the center in the left-right direction, if the position of the vehicle 1 changes with respect to the lane line due to steering after displaying the lane line image 84, etc., for example, if the vehicle transitions to driving at an appropriate position within the lane line, the upper HUD display control unit 25 may move the display position of the lane line image 84, etc., which is shifted from the center in the left-right direction in the upper HUD display area 8, in accordance with the steering amount of the vehicle 1. For example, if the vehicle 1 deviates from the lane line on the left, the upper HUD display control unit 25 displays the lane line image 84, etc., shifted to the right from the center in the left-right direction in the upper HUD display area 8. If the vehicle 1 is steered to the right, the upper HUD display control unit 25 may move the lane line image 84, etc., to the left to superimpose it on the lane line in the actual view.

[0102] Furthermore, the upper HUD display control unit 25 may display the lane marking image 84, etc. fixed at approximately the center in the left-right direction without shifting it from the center in the left-right direction of the upper HUD display area 8, and may not move the display position of the lane marking image 84, etc. even if steering is performed after the display of the lane marking image 84, etc. begins.

[0103] After displaying the lane marking image 84, etc. in the upper HUD display area 8, if the main control unit 40 determines that the vehicle 1's deviation from the lane markings, etc. has been resolved and the second condition is no longer satisfied, the main control unit 40 turns off the display of the lane marking image 84, etc. in the upper HUD display area 8 and displays the lane marking image 94 in the lower HUD display area 9 in the display mode used when the first condition is satisfied. At this time, the upper HUD display control unit 25 may turn off the display of the lane marking image 84, etc., in a manner opposite to the manner used when the display of the lane marking image 84, etc. was initiated (e.g., movement from the lower edge 8a to the upper edge 8b). Furthermore, the lower HUD display control unit 35 may perform an effect in which the lane marking image 84, which was displayed as if it had moved to the upper HUD display area 8 when the second condition was satisfied, returns to the lower HUD display area 9, while increasing the visibility of the lane marking image 94.

[0104] As a result, the main control unit 40 can make it appear as if the lane marking image 94 displayed in the lower HUD display area 9 has moved to the upper HUD display area 8. That is, when the vehicle deviates from the lane marking, the main control unit 40 highlights the lane marking image 94 and displays it in the lower HUD display area 9 to warn the driver 4. Furthermore, when the possibility of deviation increases, in order to further increase awareness, the main control unit 40 displays the lane marking image 84, etc. in the upper HUD display area 8 to raise awareness and issue a warning. As a result, the display system 10 can effectively utilize the upper HUD 20 and the lower HUD 30 in cooperation with each other to appropriately convey necessary information to the driver 4.

[0105] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0106] [Fifth Specific Example] The fifth specific example is a recognition enhancement process that is executed when the upper HUD 20 and the lower HUD 30 display warning images (rear approaching vehicle images 182, 192 in Figures 15 to 17) that show information about rear vehicles (other vehicles) traveling behind the vehicle 1 (host vehicle) on the left and right sides.

[0107] The main control unit 40 determines whether a first condition, that is, that the surrounding information acquisition unit 51 or the outside-of-vehicle information acquisition unit 52 has detected an approaching rear vehicle, is satisfied (step S1 in FIG. 3 ). The main control unit 40 may determine that the first condition is satisfied, for example, when the distance (inter-vehicle distance) between the vehicle 1 and the rear vehicle is equal to or less than a first distance, or when the approaching speed of the rear vehicle is greater than a predetermined value. The first distance is the same as in the second specific example. When the main control unit 40 determines that the first condition is not satisfied (NO in step S1), it waits until the first condition is satisfied.

[0108] When the main control unit 40 determines that the first condition is satisfied (YES in step S1), it controls the lower HUD display control unit 35 to display an image showing information about an approaching rear vehicle (warning image, hereinafter referred to as "rear approaching vehicle image (warning image) 192") in the lower HUD display area 9 (step S2). Here, Fig. 15 is an explanatory diagram showing an example of the display of the warning image in step S2 of the recognition level increasing process as a fifth specific example. In the fifth specific example, an example will be described in which a rear vehicle is traveling to the left rear.

[0109] The lower HUD display control unit 35 displays the rear approaching vehicle image 192 in a left area of ​​the lower HUD display area 9. The lower HUD display control unit 35 displays the rear approaching vehicle image 192 by matching the top, bottom, left, and right sides in the lower HUD display area 9 with the front, back, left, and right sides of the vehicle 1 so that the positional relationship between the rear vehicle and the vehicle 1 can be easily recognized. In other words, the lower HUD display control unit 35 starts displaying the rear approaching vehicle image 192 from the lower left of the lower HUD display area 9.

[0110] 15 , for example, the lower HUD display control unit 35 can indicate the speed direction of the rear approaching vehicle relative to the vehicle 1 by using an image that can indicate an arrow-shaped direction as the rear approaching vehicle image 192. The lower HUD display control unit 35 can intuitively convey the degree of approach to the driver 4 by changing the color of the rear approaching vehicle image 192 depending on the distance to the rear vehicle. For example, when the rear vehicle is closest, the lower HUD display control unit 35 can notify the driver 4 that the rear approaching vehicle is closest by displaying the rear approaching vehicle image 192 in a warning color such as red.

[0111] The lower HUD display control unit 35 displays a vehicle speed image 191 having an indicator image 193 formed in a line near the upper side 9 b of the lower HUD display area 9 toward the upper HUD display area 8. The indicator image 193 is formed to coincide with an extension of a lane marking line image 183, which will be described later. The lower HUD display control unit 35 displays a rear approaching vehicle image 192 along the indicator image 193 near the upper side 9 b.

[0112] Furthermore, when increasing the number of rear approaching vehicle images 192, the lower HUD display control unit 35 displays an emphasis warning image 194 that overlaps the leading rear approaching vehicle image 192. The lower HUD display control unit 35 displays the emphasis warning image 194, for example, as an image using a gradation that has a reference point at the center of the image and becomes lighter the farther away from the reference point. It is preferable that the lower HUD display control unit 35 displays the emphasis warning image 194 in front of layers such as the rear approaching vehicle image 192 displayed in the lower HUD display area 9, thereby making it easier for the driver 4 to recognize the emphasis warning image 194.

[0113] The main control unit 40 determines whether the following conditions are met: the distance between the vehicle 1 and the vehicle behind is equal to or less than a second distance, the vehicle behind is closer than under the first condition, and the level of warning is high. The second distance is the same as in the second specific example. If the main control unit 40 determines that the above conditions are not met, the main control unit 40 maintains the display of the rear approaching vehicle image 192 and the highlighted warning image 194 in the lower HUD display area 9.

[0114] On the other hand, if the main control unit 40 determines that the above condition is satisfied, it controls the lower HUD display control unit 35 to sequentially increase the number of images displayed in the lower HUD display area 9 so that the rear approaching vehicle image 192 in the lower HUD display area 9 approaches the upper HUD display area 8. Here, Figure 16 is an explanatory diagram showing another example of the display of a warning image in step S2 of the recognition level increasing process as a second specific example.

[0115] The lower HUD display control unit 35 sequentially increases the rear approaching vehicle image 192 in accordance with the direction of the relative speed of the rear vehicle. Specifically, the lower HUD display control unit 35 gradually increases the rear approaching vehicle image 192 toward the upper right, thereby making the driver perceive that the rear approaching vehicle is traveling from rear to front toward the vehicle 1. Furthermore, the lower HUD display control unit 35 increases the rear approaching vehicle image 192 toward the lower left edge of the upper HUD display area 8, thereby improving the sense of linkage between the displays of the upper HUD 20 and the lower HUD 30 when the rear approaching vehicle image 192 is later increased from the lower HUD display area 9 to the upper HUD display area 8.

[0116] After the rear approaching vehicle images 192 increase, the lower HUD display control unit 35 moves the emphasis warning image 194 in the order of increase of the rear approaching vehicle images 192. Specifically, the lower HUD display control unit 35 gradually moves the emphasis warning image 194 upward and to the right, thereby making the driver more aware that a vehicle approaching from behind is traveling forward toward the vehicle 1.

[0117] After the rear approaching vehicle image 192 increases, the lower HUD display control unit 35 moves only the highlighted warning image 194 toward the upper HUD display area 8 and erases it while cutting it off from the upper side 9 b of the lower HUD display area 9. The lower HUD display control unit 35 erases the rear approaching vehicle image 192 at the same time as the highlighted warning image 194 is erased.

[0118] The lower HUD display control unit 35 repeatedly displays the rear approaching vehicle image 192 and the highlighted warning image 194 .

[0119] When moving the emphasized warning image 194, the lower HUD display control unit 35 preferably changes the representation of the emphasized warning image 194 as appropriate to communicate the status of the rear vehicle. For example, the lower HUD display control unit 35 may break the isotropy of the emphasized warning image 194 and display it as extending in an increasing direction to create the impression that the rear vehicle is moving. Furthermore, the lower HUD display control unit 35 may vary the area of ​​the emphasized warning image 194 or the rate at which the emphasized warning image 194 increases, depending on the relative speed and distance to the rear vehicle. Furthermore, as shown in FIG. 16 , the upper HUD display control unit 25 may display a rear approaching vehicle image (warning image) 182 in the upper HUD display area 8 together with text, sound, or the like as a notice of the warning image to be displayed under the second condition.

[0120] The main control unit 40 determines whether a second condition is satisfied (step S3), for example, that the inter-vehicle distance is equal to or less than a third distance, or that the vehicle approaching from behind is approaching further than when the rear approaching vehicle image 192 started to move and is in a situation where the level of warning is high enough to assume that the vehicle will soon overtake the vehicle 1. The third distance is the same as in the second specific example. If the main control unit 40 determines that the second condition is not satisfied (NO in step S3), the main control unit 40 maintains the display of the rear approaching vehicle image 192 in the lower HUD display area 9.

[0121] On the other hand, if the main control unit 40 determines that the second condition is met (YES in step S3), it controls the lower HUD display control unit 35 to maintain the display of the rear approaching vehicle image 192 displayed in the lower HUD display area 9. At this time, the highlighted warning image 194 is not displayed. The main control unit 40 also controls the upper HUD display control unit 25 to increase the rear approaching vehicle image 192 displayed in the lower HUD display area 9 toward the upper HUD display area 8 (step S4). Furthermore, it is preferable that the main control unit 40 calculates the relative speed from the distance to the rear vehicle, and causes the rear approaching vehicle image 192 to reach the vicinity of the upper edge 9b of the lower HUD display area 9 when the second condition is met.

[0122] FIG. 17 is an explanatory diagram showing a display example of a warning image in step S4 of the recognition level increasing process as a second specific example.

[0123] The upper HUD display control unit 25 displays the rear approaching vehicle image 182 on an extension of the movement direction of the rear approaching vehicle image 192 in the lower HUD display area 9, so that the rear approaching vehicle image 192 that was displayed in the lower HUD display area 9 has been expanded to the upper HUD display area 8. In other words, the upper HUD display control unit 25 displays the rear approaching vehicle image 182 as a warning image near the lower left edge of the upper HUD display area 8.

[0124] 17 , for example, the upper HUD display control unit 25 can indicate the speed direction of the rear approaching vehicle relative to the vehicle 1 by using an image 182 of the rear approaching vehicle that can indicate an arrow-like direction in the same manner as the rear approaching vehicle image 192 (with substantially the same design and color). The upper HUD display control unit 25 sequentially increases the number of rear approaching vehicle images 182 in accordance with the direction of the relative speed of the rear vehicle.

[0125] The upper HUD display control unit 25 displays a lane marking image 183 that imitates a lane line and is superimposed on the lane line on the road surface ahead of the vehicle 1 in the upper HUD display area 8. The upper HUD display control unit 25 displays the rear approaching vehicle image 182 along with the indicator image 193.

[0126] Furthermore, when the upper HUD display control unit 25 increases the number of rear-approaching vehicle images 182, it displays an emphasis warning image 184 that overlaps the leading rear-approaching vehicle image 182. The upper HUD display control unit 25 displays the emphasis warning image 184 in the same manner as the emphasis warning image 194 (with substantially the same design and color), for example, as an image using a gradation that has a reference point at the center of the image and becomes lighter the farther away from the reference point. After the number of rear-approaching vehicle images 182 has increased, the upper HUD display control unit 25 moves the emphasis warning image 184 in the order in which the rear-approaching vehicle images 182 increase.

[0127] After the rear approaching vehicle image 182 increases, the upper HUD display control unit 25 moves only the highlighted warning image 184 toward the upper edge 8b of the upper HUD display area 8 and erases it while cutting it off from the upper edge 8b. The upper HUD display control unit 25 erases the rear approaching vehicle image 182 at the same time as the highlighted warning image 184 is erased. In addition, the lower HUD display control unit 35 erases the rear approaching vehicle image 192 at the same time as the highlighted warning image 184 is erased.

[0128] The main control unit 40 controls the lower HUD display control unit 35 and the upper HUD display control unit 25 to repeatedly display the rear approaching vehicle image 192 and the highlighted warning image 194, and the rear approaching vehicle image 192 and the highlighted warning image 194.

[0129] At this time, the lower HUD display control unit 35 may indicate the presence of a rear vehicle by displaying a rear vehicle image 95 in the lower HUD display area 9. Furthermore, when the main control unit 40 detects that the driver 4 has operated the turn signal in the direction in which the rear vehicle is traveling while the rear approaching vehicle image 182 is displayed in the upper HUD display area 8, the main control unit 40 may, for example, in addition to or instead of the rear approaching vehicle image 182, notify the upper HUD display area 8 that a lane change is not permitted.

[0130] When a rear vehicle has overtaken vehicle 1 and is deemed to be within the field of view of driver 4, the main control unit 40 determines that it is not necessary for driver 4 to be aware of this and turns off the display of rear approaching vehicle images 182, 192 in the upper HUD display area 8. Furthermore, when a rear vehicle has changed lanes into vehicle 1's driving lane and is traveling ahead of vehicle 1, the main control unit 40 may indicate this with the rear approaching vehicle image 182 in the upper HUD display area 8. For example, the upper HUD display control unit 25 indicates that the current position of the rear approaching vehicle is ahead of vehicle 1 by bending and extending the tip of the rear approaching vehicle image 182 toward the center of the upper HUD display area 8 in the left-right direction.

[0131] As a result, the main control unit 40 can make the rear approaching vehicle image 192 displayed in the lower HUD display area 9 appear to be moving into the upper HUD display area 8 and approaching the vehicle 1. That is, the main control unit 40 displays the rear approaching vehicle image 192 in the lower HUD display area 9 to give the driver 4 a warning. In addition, in order to further increase the awareness of the rear approaching vehicle that is predicted to overtake the vehicle 1, the rear approaching vehicle image 182 is displayed in the upper HUD display area 8 at the stage when the vehicle is actually about to overtake, thereby increasing the awareness. As a result, the display system 10 can effectively utilize the upper HUD 20 and the lower HUD 30 to appropriately convey necessary information to the driver 4.

[0132] For example, although an example has been described in which the first display and the second display are both HUDs, one or both of them may be devices that allow the user to view a real image displayed on a display panel such as a TFT (Thin Film Transistor) type liquid crystal display or an organic EL (Electroluminescence) display.

[0133] Furthermore, although the example in which the projection member of the upper HUD 20 and the lower HUD 30 is the windshield 3 has been described, the projection member may instead be a combiner, or may be combined with the windshield 3 .

[0134] The first condition, the second condition, and the warning image used in the first to fifth specific examples are merely examples, and the content of the conditions and the warning image may be set as appropriate. When information (image) displayed in the lower HUD display area 9 (second display area) is moved to the upper HUD display area 8 (first display area) and displayed there, or when information displayed in the upper HUD display area 8 (first display area) is moved to the lower HUD display area 9 (second display area) and displayed there, it is not necessary for the information to move within the upper HUD display area 8 or the lower HUD display area 9; the information may be turned off in place without moving and then reappear in the lower HUD display area 9 or the upper HUD display area 8. In this case, the turning off and reappearance of the information may or may not be performed with a fade-out or fade-in effect, for example.

[0135] REFERENCE SIGNS LIST 1 vehicle 2 instrument panel 3 windshield 3a shading portion 4 driver 4a line of sight 5 steering wheel 8 upper HUD display area 9 lower HUD display area 8a, 9a lower side 8b, 9b upper side 8c, 9c left side 8d, 9d right side 10 display system 20 upper HUD 21, 31 display 22 concave mirror 24, 34 housing 25 upper HUD display control unit 30 lower HUD 35 lower HUD display control unit 40 main control unit 50 CAN bus 51 surrounding information acquisition unit 52 outside vehicle information acquisition unit 53 car navigation system 54 vehicle ECU 84, 94 lane marking image 86, 86a, 86b, 96 forward vehicle image 87, 97 sign image 88, 98 Image of vehicle approaching from behind 89 Warning image 91 Image of own vehicle 92 Vehicle speed image 95 Image of vehicle approaching from behind 182 Image of vehicle approaching from behind (warning image) 183 Image of lane markings 184 Highlighted warning image 191 Vehicle speed image 192 Image of vehicle approaching from behind (warning image) 193 Index image 194 Highlighted warning image L1, L2 Display light V1, V2 Virtual image d1, d2 Distance θ1, θ2 Angle

Claims

1. A display system comprising: a first display device that displays an image in a first display area so that it can be seen at a first display distance relative to the line of sight of a driver of a vehicle; a second display device that displays an image in a second display area different from the first display area so that it can be seen at a second display distance that is greater than the first display distance relative to the line of sight of the driver; and a display control unit that executes a recognition increasing process that displays a warning image in the second display area if a first condition is met, and moves and displays the warning image in the first display area if a second condition is met after the first condition is met, which is a situation with a higher level of warning than the first condition, or a recognition decreasing process that displays the warning image in the first display area if the second condition is met, and moves and displays the warning image in the second display area if the first condition is met after the second condition is met.

2. The display system of claim 1, wherein the warning image is an image showing information regarding traffic information located in front of the vehicle, the second condition is when the display control unit detects the traffic information that should be notified to the driver, the first condition is when the distance between the traffic information and the vehicle is equal to or less than a predetermined distance that is smaller than the distance between the traffic information and the vehicle when the traffic information is detected, and the display control unit executes the visibility reduction processing when the first condition is met after the second condition is met.

3. A display system as described in claim 2, wherein the display control unit, when the second condition is satisfied, moves the warning image within the first display area so as to approach the second display area as the distance between the traffic information and the vehicle decreases.

4. The display system of claim 1, wherein the warning image is an image showing information about other vehicles traveling around the vehicle, the first condition is when the other vehicle is detected, the second condition is that the distance between the other vehicle and the vehicle is equal to or less than a predetermined distance that is smaller than the distance between the other vehicle and the vehicle when the other vehicle is detected, and the display control unit executes the awareness increase processing when the second condition is met after the first condition is met.

5. The display system of claim 4, wherein the other vehicle is a vehicle traveling to the left or right and rear of the host vehicle, and the display control unit, when the first condition is satisfied, moves the warning image within the second display area so as to approach the first display area as the distance between the other vehicle and the host vehicle decreases.

6. The display system of claim 4, wherein the other vehicle is a vehicle traveling ahead of the host vehicle, and the display control unit, when the second condition is satisfied, displays the warning image with increased visibility the shorter the distance between the other vehicle and the host vehicle or the greater the approaching speed.

7. The display system of claim 1, wherein the warning image is an image showing a dividing line of the lane in which the vehicle is traveling and information about the vehicle traveling in the lane, the first condition is that the distance between the vehicle and the dividing line is equal to or less than a first distance, the second condition is that the distance between the vehicle and the dividing line is equal to or less than a second distance that is smaller than the first distance, and the display control unit executes the awareness increase process if the second condition is met after the first condition is met.

8. The other vehicle is a vehicle traveling to the left and right and rear of the host vehicle, and the display control unit, when the first condition is met, sequentially increases the number of warning images in the second display area so that they move closer to the first display area as the distance between the other vehicle and the host vehicle decreases, and when the second condition is met, while keeping the warning image in the second display area displayed, sequentially increases the number of warning images in the first display area so that they move farther away from the second display area as the distance between the other vehicle and the host vehicle decreases, and the warning image in the first display area is an image of approximately the same design as the warning image in the second display area. A display system as described in claim 4.

9. The display system according to claim 8, wherein the display control unit moves an emphasized warning image that overlaps the leading warning image along the warning images when the number of warning images increases.

Images