Vehicle virtual image display device

Abstract

To provide a virtual image display device for a vehicle capable of recognizing a required road sign without giving attention and troublesomeness to a driver when visibility of the road sign is not good.SOLUTION: A virtual image display device for a vehicle includes: a display control unit 150 that displays an image of a sign mark 20a corresponding to road sign data in high-precision map data stored in a map database 50 on an LCD 121, and projects display light of an image of the sign mark on a windshield 10 to superimpose and display the image of the sign mark as a virtual image 20 on a foreground of the vehicle 1; a front camera 60 for photographing an actual road sign 30 in a foreground; and a determination unit 70 for determining whether or not it is necessary for a driver to recognize the road sign. The display control unit superimposes and displays the sign mark so as to correspond to a position of the road sign when recognition of the road sign photographed by the front camera is insufficient and determination by the determination unit needs recognition of the road sign.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a virtual image display device for a vehicle. [Background technology]

[0002] A sign recognition system is described in Patent Document 1. In Patent Document 1, when visibility of road signs is poor, such as at night or in rainy weather, or when visibility of road signs is good but the driver's line of sight is not directed toward the road sign, caution information regarding the road sign is displayed on a display device such as a head-up display.

[0003] Furthermore, in the vehicle display control device of Patent Document 2, an icon resembling a traffic mark is superimposed on the foreground by a head-up display based on information about the traffic mark (such as a road sign in map data) obtained from a mark determination unit. At this time, a 3D object (an image of a pseudo three-dimensional object for regulation) as a target mark is superimposed on the foreground together with the traffic mark icon in accordance with a predetermined event identified by an event identification unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-97682 [Patent Document 2] Japanese Patent Application Publication No. 2018-200626 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, when the warning information is displayed on a display device, the driver's line of sight is guided (causing eye-catching effects) to a different direction where the warning information is displayed, which may actually hinder safe driving.

[0006] Furthermore, in Patent Document 2, even on roads that the driver is familiar with, traffic signs and 3D objects are always superimposed on the road, which is annoying for the driver.Also, it is annoying for the driver to have traffic signs and 3D objects of low importance displayed each time.

[0007] In view of the above problems, the object of the present disclosure is to provide a virtual image display device for a vehicle that enables the driver to recognize necessary road signs without being conspicuous or bothersome to the driver even when the visibility of the road signs is poor. [Means for solving the problem]

[0008] In order to achieve the above object, the present disclosure employs the following technical means.

[0009] One The present disclosure provides a virtual image display device for a vehicle that includes a display control unit (150) that displays, on a display unit (121), an image of a sign mark (20a) corresponding to road sign data in high-precision map data stored in a map database (50), projects display light of the image of the sign mark onto a projection member (10) in front of a driver, and superimposes the image of the sign mark as a virtual image (20) on the foreground of a vehicle (1), a forward-facing camera (60) that captures an actual road sign (30) in the foreground; a determination unit (70) that determines whether or not a driver needs to recognize a road sign; A passenger camera (71) that captures the driver's face and Equipped with the determination unit determines that it is necessary to recognize a road sign when the driver's line of sight obtained by the passenger camera is in the direction of a road sign obtained by the front camera; When the recognition of a road sign photographed by the forward camera is insufficient and the judgment unit determines that recognition of the road sign is necessary, the display control unit superimposes a sign mark to correspond to the position of the road sign. Another aspect of the present disclosure is a virtual image display device for a vehicle that includes a display control unit (150) that displays, on a display unit (121), an image of a sign mark (20a) corresponding to road sign data in high-precision map data stored in a map database (50), projects display light of the image of the sign mark onto a projection member (10) in front of a driver, and superimposes the image of the sign mark as a virtual image (20) on a foreground of a vehicle (1), a forward-facing camera (60) that captures an actual road sign (30) in the foreground; a determination unit (70) that determines whether or not it is necessary for the driver to recognize road signs, The determination unit determines that it is necessary to recognize a predetermined road sign in consideration of its importance when there is no voice guidance from the vehicle navigation system (72), and When the recognition of a road sign photographed by the forward camera is insufficient and the judgment unit determines that recognition of the road sign is necessary, the display control unit superimposes a sign mark to correspond to the position of the road sign.

[0010] According to the present disclosure, when the recognition of a road sign photographed by the forward camera is insufficient and the determination unit determines that recognition of the road sign is necessary, a sign mark is superimposed to correspond to the position of the road sign. This makes it possible to suppress unnecessary display, and enables the driver to recognize the road sign that is necessary without being conspicuous or bothersome to the driver.

[0011] The reference numerals in parentheses for the above means indicate the corresponding relationship with the specific means described in the embodiments below. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an explanatory diagram showing the overall configuration of a head-up display device according to a first embodiment. [Figure 2] 10 is a flowchart showing control executed by a display control unit. [Figure 3] FIG. 10 is an explanatory diagram showing a case where recognition of a road sign is insufficient and the driver is looking in a direction different from the road sign. [Figure 4] FIG. 10 is an explanatory diagram showing how a sign mark is superimposed when the driver is looking in the direction of a road sign due to insufficient recognition of the road sign. [Figure 5] FIG. 10 is an explanatory diagram showing the overall configuration of a head-up display device according to a second embodiment. [Figure 6] FIG. 10 is an explanatory diagram showing the overall configuration of a head-up display device according to a third embodiment. [Figure 7] FIG. 10 is an explanatory diagram showing the overall configuration of a head-up display device according to a fourth embodiment. [Figure 8] FIG. 10 is an explanatory diagram showing the overall configuration of a head-up display device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicate descriptions may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0014] (First embodiment) A virtual image display device for a vehicle according to a first embodiment will be described with reference to Fig. 1 to Fig. 4. As shown in Fig. 1, the virtual image display device for a vehicle is a device that projects an image from a display device 120 (liquid crystal display 121) onto a windshield 10 in front of a driver (viewer) of a vehicle 1. The windshield 10 corresponds to the projection member of the present disclosure.

[0015] That is, the vehicle virtual image display device projects display light representing an image emitted from the display device 120 onto the projection position 10a on the windshield 10 of the vehicle 1. The display light is light indicated by the two-dot chain arrow from the display device 120 to the windshield 10 in FIG. 1. The vehicle virtual image display device superimposes and displays a virtual image 20 on a forward extension of the line connecting the driver and the projection position 10a, that is, on the road the vehicle 1 is traveling on (foreground), so that the driver can see it. Such a vehicle virtual image display device is called a head-up display device, and hereinafter referred to as "HUD device 100A."

[0016] In the HUD device 100A of this embodiment, the virtual image 20 is, for example, an image of a sign mark 20a (FIG. 4) indicating various road signs 30 placed on the road ahead while the vehicle is traveling. The sign mark 20a is displayed superimposed (AR display) so as to correspond to the position of the road sign 30 (FIG. 3). AR is an abbreviation for Augmented Reality. The superimposed display of the sign mark 20a will be described in detail later.

[0017] The windshield 10 is a shield on the front side of the vehicle 1, and is made of, for example, laminated glass formed from two pieces of glass with an intermediate film placed between them. When viewed from above the vehicle 1 and from the side of the vehicle 1, the windshield 10 has a curvature that makes the interior side of the vehicle 1 concave, and has the same effect as a concave mirror, allowing the displayed image to be enlarged and displayed at a greater distance.

[0018] The HUD device 100A includes a map database 50, a front camera 60, a determination unit 70, an occupant camera 71, a housing 110, a display device 120, a reflecting unit (a plane mirror 130, a concave mirror 140), a display control unit 150, and the like.

[0019] The map database 50 is a component that holds high-precision three-dimensional map data (high-accuracy map data). For example, the map database 50 used is one that is provided in a vehicle navigation system (GNSS, satellite positioning system). The high-precision three-dimensional map data includes, for example, data on road shapes, road widths, the number of lanes, destination guides, traffic lights, shoulder lines, dividing lines, stop lines, direction of travel, various road signs 30 (all of which are real features), and lane links (virtual features) that indicate lane centerlines for expressways, motorways, and general roads.

[0020] The data for various road signs 30 includes data such as the installation position on the road where the sign is installed, the height from the road surface, the type of sign, the sign design (sign mark 20a), etc. Road signs 30 include, for example, guide signs indicating place names and facilities in the driving direction, warning signs that call for caution (attention) in the driving direction, regulatory signs that regulate the traffic of the vehicle 1, directional signs that give instructions regarding driving, and auxiliary signs that provide supplementary displays.

[0021] The high-precision three-dimensional map data (data of the road signs 30) in the map database 50 is output to the display control unit 150.

[0022] The front camera 60 is installed, for example, on the front ceiling of the vehicle interior, and captures (takes) images of actual road signs 30 on the road within a predetermined distance ahead of the vehicle 1. The predetermined distance is, for example, a distance of about 30 to 50 meters ahead of the vehicle 1.

[0023] The front camera 60 may be, for example, a CCD camera, a CMOS camera, or an infrared camera. The front camera 60 outputs the acquired image data of the road sign 30 to the determination unit 70 and the display control unit 150.

[0024] The judgment unit 70 is a part that judges whether or not the driver needs to recognize the road sign 30 by using an image of the road sign 30 taken by the front camera 60 and an image of the driver's face taken by the passenger camera 71 described later (details will be described later).

[0025] The occupant camera 71 mainly acquires an image of the driver's face (an image of the face direction, eye position, pupil position, etc.) in order to grasp the driver's line of sight direction. The occupant camera 71 is, for example, a CCD camera, a CMOS camera, an infrared camera, or the like, similar to the front camera 60, and is provided on the front ceiling of the vehicle 1. The occupant camera 71 outputs data of the acquired face image of the driver to the determination unit 70.

[0026] The occupant camera 71 is not limited to a dedicated camera as described above, but may also be a camera set up for the DSM or ADAS (Advanced Driver Assistance System), if the vehicle 1 is equipped with a DSM (Driver Status Monitor, registered trademark) that detects the driver's inattentiveness or drowsiness at the wheel and provides driving assistance, or an ADAS (Advanced Driver Assistance System) that has a collision prevention function, lane departure detection function, etc.

[0027] The housing 110 is a case member that houses the display device 120, the reflecting units (the plane mirror 130, the concave mirror 140), etc., and has the shape of, for example, a rectangular parallelepiped. The determining unit 70, the display control unit 150, etc. may also be housed in the housing 110. An opening 111 is formed on the upper side (windshield 10 side) of the housing 110 so that the display light from the display device 120 can exit (pass through). A light-transmitting dustproof sheet is provided in the opening 111 to prevent dust, dirt, etc. from entering the housing 110. The housing 110 is disposed in the instrument panel of the vehicle 1. An instrument panel opening is also formed on the top surface of the instrument panel so that the display light can pass through.

[0028] The display device 120 includes a liquid crystal display 121, a backlight 122, and the like.

[0029] The liquid crystal display 121 is illuminated by light from the backlight 122 and displays a predetermined image, in this case an image (sign mark 20a) showing a road sign 30, on the display surface 121a, and is driven and controlled (image processed) by the display control unit 150. The liquid crystal display 121 is, for example, a TFT liquid crystal display using thin film transistors (TFTs). The liquid crystal display 121 corresponds to the display unit of the present disclosure.

[0030] The backlight 122 is disposed on the rear side of the liquid crystal display 121 (opposite the display surface 121a), and serves as a light source unit that emits light when energized (supplied with power) and irradiates the liquid crystal display 121 with light for displaying images. The backlight 122 uses, for example, light emitting diodes (LEDs). A plurality of light emitting diodes are provided and arranged in a grid pattern. The light emission state of the backlight 122 is controlled by the display control unit 150, and the backlight 122 irradiates light along an optical axis toward the liquid crystal display 121.

[0031] The liquid crystal display 121 emits display light representing an image by using light emitted from the backlight 122 toward the plane mirror 130 on the opposite side of the backlight 122. In this embodiment, the surface (display surface 121a) of the liquid crystal display 121 that emits the display light faces, for example, horizontally, and is disposed so that the optical axis of the display light faces in the vertical direction of the vehicle 1 (the emission direction faces upward of the vehicle 1).

[0032] The plane mirror 130 is a mirror whose reflective surface is flat, and is disposed so that the reflective surface of the plane mirror 130 faces the liquid crystal display 121 and the concave mirror 140. The plane mirror 130 reflects the display light from the liquid crystal display 121 to the concave mirror 140.

[0033] Concave mirror 140 is a mirror that magnifies the reflected image from plane mirror 130, and is arranged so that the reflective surface of concave mirror 140 faces plane mirror 130 and projection position 10a on windshield 10. Concave mirror 140 reflects the display light that is emitted from liquid crystal display 121 and reflected by plane mirror 130 through opening 111 in housing 110 to projection position 10a on windshield 10.

[0034] The concave mirror 140 is supported by a shaft and is rotatable, and the tilt direction of the concave mirror 140 shown in Fig. 1 can be adjusted by the driver or the display control unit 150. By adjusting the tilt angle of the concave mirror 140, the projection position 10a can be shifted individually for drivers of different physiques, so that the display image can be viewed at a suitable position.

[0035] The display control unit 150 controls the display related to image processing of the liquid crystal display 121 (and controls the angle of the concave mirror 140). When the recognition of the road sign 30 photographed by the forward camera 60 is insufficient and the determination unit 70 determines that the driver needs to recognize the road sign 30, the display control unit 150 superimposes and displays the sign mark 20a so as to correspond to the position of the road sign 30 (details will be described later).

[0036] The HUD device 100A is configured as described above, and the operation, functions and effects of the HUD device 100A will be described below with reference to FIGS.

[0037] When the HUD device 100A is turned on, the display control unit 150 first determines whether or not the road sign 30 can be recognized by the front camera 60 in step S100 of the flowchart shown in FIG.

[0038] For example, as shown in Fig. 3, if the road sign 30 is obscured by an obstacle such as a roadside tree, an image of the entire road sign 30 cannot be acquired. Alternatively, depending on weather conditions such as rain, snow, or fog, a clear image of the road sign 30 may not be acquired. Therefore, the display control unit 150 compares the design (image of the sign mark 20a) of the data of the road sign 30 obtained from the map database 50 with the image (design) of the road sign 30 captured by the front camera 60, and if the two do not match, determines that the recognition of the road sign 30 is insufficient (recognition is not possible).

[0039] If the display control unit 150 makes a negative determination in step S100 (recognition is not possible), the process proceeds to step S110, and if the display control unit 150 makes a positive determination (recognition is possible), the process proceeds to step S140.

[0040] In step S110, the determination unit 70 determines whether the driver needs to recognize the road sign 30, and outputs the determination result to the display control unit 150.

[0041] In this embodiment, the determination unit 70 calculates the driver's line of sight direction from the face direction, eye position, and pupil position based on the face image of the driver obtained by the passenger camera 71. The determination unit 70 then converts the coordinate position of the passenger camera 71 into the coordinate position of the front camera 60, and determines the driver's line of sight direction relative to the foreground (road sign 30).

[0042] The determination unit 70 determines that it is necessary to recognize the road sign 30 when the line of sight of the driver obtained by the occupant camera 71 is in the direction of the road sign 30 obtained by the front camera 60, as shown in Fig. 4. If the determination result from the determination unit 70 is a positive determination, the display control unit 150 proceeds to step S120, and if the determination result is a negative determination, the display control unit 150 proceeds to step S140.

[0043] In step S120, the display control unit 150 acquires the positions of the road signs 30 (positions on the road and heights from the road surface, etc.) and the types of the road signs 30 from the high-precision three-dimensional map data.

[0044] Then, in step S130, the display control unit 150 superimposes the acquired road sign 30 mark (sign mark 20a) so that it corresponds to the position of the actual road sign 30 in the foreground, as shown in FIG. 4, and ends this flow.

[0045] On the other hand, after making a positive determination in step S100 and a negative determination in step S110, the display control unit 150 does not perform the superimposed display as in step S130 (step S140) and ends this flow.

[0046] As described above, in this embodiment, when the recognition of the road sign 30 photographed by the forward camera 60 is insufficient and the determination unit 70 determines that recognition of the road sign 30 is necessary, the display control unit 150 superimposes and displays the sign mark 20a so as to correspond to the position of the road sign 30. Therefore, unnecessary display can be suppressed, and the driver can recognize the road sign 30 that is necessary for the driver without being conspicuous or bothersome to the driver.

[0047] Furthermore, when the image of the sign mark 20a does not match the image of the road sign 30 captured by the front camera 60, the display control unit 150 determines that the recognition of the road sign is insufficient, and the possibility of recognizing the road sign 30 can be clearly grasped.

[0048] Furthermore, the determination unit 70 determines that it is necessary to recognize the road sign 30 when the line of sight of the driver obtained by the passenger camera 71 is in the direction of the road sign 30 obtained by the front camera 60. This allows the driver to reliably know when it is necessary to recognize the road sign 30.

[0049] (Second embodiment) A HUD device 100B of the second embodiment is shown in Fig. 5. In the HUD device 100B of the second embodiment, in contrast to the HUD device 100A of the first embodiment, the determination unit 70 makes the determination (necessity of recognizing road signs 30) of step S110 described in Fig. 2 using driving history data (driving trajectory data) from a vehicle navigation system 72 instead of data of occupant face images from an occupant camera 71. Note that in this embodiment, image data of road signs 30 from the front camera 60 is not output to the determination unit 70.

[0050] In step S110 described in FIG. 2, the determination unit 70 determines that it is necessary to recognize the road sign 30 if the number of times the vehicle has traveled on the road in the past is a predetermined number of times or less (for example, five times or less) based on the travel history data from the vehicle navigation system 72.

[0051] As a result, if the driving history is less than the predetermined number of times, the driver will be driving on a road that is unfamiliar to the driver, and the driver can reliably grasp when it is necessary to recognize the road signs 30.

[0052] (Third embodiment) A HUD device 100C of the third embodiment is shown in Fig. 6. In the HUD device 100C of the third embodiment, in comparison with the HUD device 100A of the first embodiment, the determination unit 70 performs the determination of step S110 described in Fig. 2 (the necessity of recognizing the road sign 30) using image data of the road sign 30 captured by the front camera 60 and an operation signal from the operation device 73 of the vehicle 1.

[0053] The operating device 73 is, for example, a turn signal lever for indicating right or left turns using a turn signal, a shift lever for changing the shift position of a transmission gear, an accelerator pedal for adjusting the vehicle speed, etc.

[0054] In step S110 described in FIG. 2, when an operation signal that contradicts the road sign 30 obtained by the forward camera 60 is received from the operation device 73 of the vehicle 1 operated by the driver, the judgment unit 70 judges that it is necessary to recognize the road sign 30.

[0055] For example, even though road sign 30 indicates "No entry for vehicles," the driver may operate the turn signal lever in the prohibited direction and attempt to enter a no-entry road. Alternatively, even though road sign 30 indicates "No parking or stopping," the driver may put the shift lever into "P" or "N" in an attempt to park or stop on a no-parking road. Alternatively, even though road sign 30 indicates "Maximum speed (60)," the driver may exceed the speed limit by operating the accelerator pedal.

[0056] As a result, driving against the road signs 30 is predicted from the operation signal, so the driver can reliably know when it is necessary to recognize the road signs 30.

[0057] (Fourth embodiment) A HUD device 100D of the fourth embodiment is shown in Fig. 7. In the HUD device 100D of the fourth embodiment, in contrast to the HUD device 100A of the first embodiment, the determination unit 70 makes the determination of step S110 described in Fig. 2 (whether or not recognition of road signs 30 is necessary) using the presence or absence of voice guidance from the vehicle navigation system 72, instead of data on the facial image of the occupant captured by the occupant camera 71. Note that in this embodiment, image data of the road signs 30 captured by the front camera 60 is not output to the determination unit 70.

[0058] 2, the determination unit 70 determines that it is necessary to recognize a predetermined road sign 30 whose importance has been considered in advance when there is no voice guidance from the vehicle navigation system 72. The predetermined road signs 30 whose importance has been considered in advance are road signs 30 that, if not observed, could lead to a serious violation, and examples of such road signs include "stop sign" and "railroad crossing ahead."

[0059] The determination unit 70 determines that it is necessary to recognize the road sign 30 when there is a stop road sign 30 in the foreground but there is no voice guidance such as "Please stop" from the vehicle navigation system 72. Alternatively, the determination unit 70 determines that it is necessary to recognize the road sign 30 when there is a road sign 30 indicating a railroad crossing in the foreground but there is no voice guidance such as "There is a railroad crossing ahead" from the vehicle navigation system 72.

[0060] As a result, when there is no voice guidance for a road sign 30 that takes into account its importance, the process proceeds to step S120 and step S130, and the sign mark 20a is superimposed, allowing the driver to reliably understand when it is necessary to recognize the road sign 30.

[0061] (Fifth embodiment) A HUD device 100E of a fifth embodiment is shown in Fig. 8. In the HUD device 100E of the fifth embodiment, in comparison with the HUD device 100A of the first embodiment, the determination unit 70 determines in step S110 described in Fig. 2 that it is necessary to recognize road signs 30 in the image of the road signs 30 acquired by the forward camera 60, such as warning signs (intersection ahead, railroad crossing ahead, watch out for falling rocks, etc.) and regulatory signs (road closed, no entry, no parking, etc.).

[0062] This allows the driver to reliably understand when it is necessary to recognize a road sign 30 that is of high importance, such as a warning sign or a regulatory sign.

[0063] (Other embodiments) The disclosure in this specification and drawings, etc. is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0064] In addition, in each of the above embodiments, the windshield 10 of the vehicle 1 is used as a projection member for the display light emitted from the liquid crystal display 121 (display device 120), but this is not limited to this, and it may also be a combiner or the like that is provided exclusively for the HUD devices 100A to 100E.

[0065] Furthermore, in each of the above embodiments, the liquid crystal display 121 (TFT liquid crystal display) is used as the display device 120, but instead, other types of displays such as an organic EL display may be used.

[0066] Furthermore, in each of the above embodiments, the reflecting section includes a plane mirror 130 and a concave mirror 140. However, for example, the display light from the liquid crystal display 121 may be arranged to be directed toward the concave mirror 140, and the plane mirror 130 may be eliminated.

[0067] Furthermore, the virtual image 20 is a sign mark 20a that is superimposed on the actual road sign 30, but in addition, other vehicle information (speed, shift lever position, guide route direction, etc.) may be displayed in a fixed area within the area where the virtual image 20 is displayed. [Explanation of symbols]

[0068] 1 vehicle 10 Windshield (projection component) 20 Virtual Image 20a Sign mark 30 road signs 50 map databases 60 Front camera 70 Judgment section 71 Passenger Camera 72 Vehicle Navigation System 73 Operating device 100A~100E Head-up display device (vehicle virtual image display device) 121 LCD display (display unit) 150 Display control unit

Claims

1. A virtual image display device for a vehicle includes a display control unit (150) that displays an image of a sign mark (20 a) corresponding to road sign data in high-precision map data stored in a map database (50) on a display unit (121), projects display light of the image of the sign mark onto a projection member (10) in front of a driver, and displays the image of the sign mark as a virtual image (20) superimposed on the foreground of the vehicle (1), a forward camera (60) for photographing an actual road sign (30) in the foreground; a determination unit (70) that determines whether or not the driver needs to recognize the road sign; a passenger camera (71) for photographing the face of the driver, the determination unit determines that it is necessary to recognize the road sign when the line of sight of the driver obtained by the passenger camera is in the direction of the road sign obtained by the front camera; The display control unit is a virtual image display device for a vehicle that superimposes the sign mark to correspond to the position of the road sign when the recognition of the road sign photographed by the forward camera is insufficient and the judgment unit determines that recognition of the road sign is necessary.

2. A virtual image display device for a vehicle includes a display control unit (150) that displays an image of a sign mark (20 a) corresponding to road sign data in high-precision map data stored in a map database (50) on a display unit (121), projects display light of the image of the sign mark onto a projection member (10) in front of a driver, and displays the image of the sign mark as a virtual image (20) superimposed on the foreground of the vehicle (1), a forward camera (60) for photographing an actual road sign (30) in the foreground; a determination unit (70) that determines whether or not the driver needs to recognize the road sign, the determination unit determines that it is necessary to recognize a predetermined road sign in consideration of importance when there is no voice guidance from a vehicle navigation system (72), The display control unit is a virtual image display device for a vehicle that superimposes the sign mark to correspond to the position of the road sign when the recognition of the road sign photographed by the forward camera is insufficient and the judgment unit determines that recognition of the road sign is necessary.

3. 3. The vehicle virtual image display device according to claim 1, wherein the display control unit determines that recognition of the road sign is insufficient when the image of the sign mark does not match the image of the road sign captured by the forward camera.

Images