Road surface drawing device for vehicle and headlight for vehicle

Abstract

A road surface drawing device (1) for a vehicle displays a road surface drawing pattern (P) along a road ahead of a vehicle (100) in which said device is installed. The road surface drawing pattern (P) changes in accordance with the steering angle of the vehicle (100), the vehicle speed, and the angular velocity of the steering angle.

Description

Vehicle road surface drawing device and vehicle headlamp

[0001] The present disclosure relates to a road surface drawing device for a vehicle and a vehicle headlamp.

[0002] Patent Document 1 discloses a road surface drawing device that is mounted on a vehicle or the like and projects a road surface drawing pattern onto the road surface to indicate the traveling direction of the vehicle.

[0003] Japanese Patent Application Publication No. 2021-79835

[0004] The road surface drawing device of Patent Document 1 displays a road surface drawing pattern having a curved outer edge line that follows the driving lane. The curved outer edge line of the road surface drawing pattern is determined by the steering angle obtained from the steering device of the vehicle.

[0005] However, the curvature of the road surface is not always constant. For example, a curving road includes not only curved sections where the curvature is constant, but also transition curve sections where the curvature gradually changes. For this reason, when controlling the steering angle, the curvature of the road surface rendering pattern may shift in transition curve sections, making it impossible to display the road surface rendering pattern along the road.

[0006] An object of the present disclosure is to provide a road surface drawing device for a vehicle and a vehicle headlamp that display a road surface drawing pattern that matches the path the vehicle is traveling.

[0007] A road surface drawing device for a vehicle according to one aspect of the present disclosure is a road surface drawing device for a vehicle that displays a road surface drawing pattern along the road ahead of the vehicle on which it is installed, and the road surface drawing pattern changes depending on the steering angle of the vehicle, the vehicle speed, and the angular velocity of the steering angle.

[0008] A vehicle headlamp according to one aspect of the present disclosure includes the vehicle road surface drawing device described above, and a headlamp unit that illuminates the area ahead of the vehicle.

[0009] According to the present disclosure, it is possible to provide a road surface drawing device for a vehicle and a vehicle headlamp that display a road surface drawing pattern that matches the path the vehicle is traveling.

[0010] FIG. 1 illustrates a road surface rendering device and a road surface rendering pattern according to a first embodiment. FIG. 2 is a cross-sectional view of the road surface rendering device according to the first embodiment. FIG. 3 is a block diagram of a vehicle and a road surface rendering device according to the first embodiment. FIG. 4 illustrates a road surface rendering pattern in a transition curve section. FIG. 5 illustrates a road surface rendering pattern in a transition curve section. FIG. 6 illustrates a road surface rendering pattern in a curved section. FIG. 7 illustrates a road surface rendering pattern according to a comparative example. FIG. 8 illustrates a road surface rendering pattern according to a second embodiment in a transition curve section. FIG. 9 illustrates a road surface rendering pattern according to the second embodiment in a transition curve section. FIG. 10 illustrates a road surface rendering device according to a first modification. FIG. 11 illustrates a road surface rendering device according to a second modification.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. For the sake of convenience, descriptions of components having the same reference numerals as those already described in the description of the embodiments will be omitted. Furthermore, for the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0012] Furthermore, in the description of this embodiment, for convenience of explanation, the "up-down direction," "front-rear direction," and "left-right direction" will be referred to as appropriate. Here, the "up-down direction" is a direction that includes the "upward direction" and the "downward direction." The "front-rear direction" is a direction that includes the "forward direction" and the "rearward direction." The "left-right direction" is a direction that includes the "leftward direction" and the "rightward direction." In the drawings described below, the symbol U indicates the upward direction. The symbol D indicates the downward direction. The symbol F indicates the forward direction. The symbol B indicates the rearward direction. The symbol L indicates the leftward direction. The symbol R indicates the rightward direction.

[0013] First Embodiment A road surface drawing device 1 according to a first embodiment, which is provided on a vehicle 100, will be described with reference to Fig. 1. Fig. 1 illustrates an example of the road surface drawing device 1 and a road surface drawing pattern P according to the first embodiment.

[0014] In the example shown in FIG. 1 , the road surface drawing device 1 is housed in a headlight 60 mounted on a vehicle 100. The road surface drawing device 1 is an example of a road surface drawing device for a vehicle. The headlight 60 is an example of a vehicle headlight. The road surface drawing device 1 is configured to irradiate a road surface with light to display a road surface drawing pattern P along the road ahead of the vehicle in which it is mounted. In this embodiment, the road surface drawing pattern P is composed of two lines of a constant width that are displayed on the right front and left front of the vehicle 100. The outer edge lines L and L' of the road surface drawing pattern P are spaced apart by a distance equal to or greater than the vehicle width B1. The outer edge line L indicates the right edge of the road surface drawing pattern P displayed on the right, and the outer edge line L' indicates the left edge of the road surface drawing pattern P displayed on the left.

[0015] 2 is a cross-sectional view of the road surface drawing device 1 according to the first embodiment. The road surface drawing device 1 comprises a lamp body 2 having an opening in front of the lamp, and a translucent outer cover 3 that covers the opening of the lamp body 2. A lamp chamber 4 formed by the lamp body 2 and the outer cover 3 houses multiple light sources 5, optical members 6, and a road surface drawing control unit 7.

[0016] The light source 5 is configured by, for example, an LED (Light Emitting Diode) element or an LD (Laser Diode) element, or may be configured by a semiconductor light emitting element that emits laser light.

[0017] The light sources 5 are mounted on a substrate 50. The substrate 50 can be formed from, for example, a glass material such as silica glass, borosilicate glass, or alkali-free borosilicate glass, or a resin material such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, or cycloolefin polymer. The light sources 5 are arranged in a matrix on the substrate 50.

[0018] The optical element 6 is configured to refract the light emitted from the light source 5 and emit it toward the road surface. The optical element 6 is, for example, a plano-convex lens with a convex front surface and a flat rear surface. The optical element 6 may be formed from a light-transmitting material such as a transparent resin such as acrylic. Each light source 5 is configured so that its illuminance can be changed individually when turned on by changing the duty ratio, for example. In this example, the lighting pattern of the light sources 5 arranged in a matrix is ​​displayed on the road surface as a road surface drawing pattern.

[0019] The road surface drawing control unit 7 is configured to control the turning on and off of the light sources 5. The road surface drawing control unit 7 controls the plurality of light sources 5 so as to generate a desired image on the road surface by individually controlling the turning on and off of the plurality of light sources 5. The operation of the road surface drawing control unit 7 will be described in detail later.

[0020] Next, the road surface drawing pattern P according to the first embodiment will be described using Figures 3 to 6. Figure 3 is a block diagram of the vehicle 100 and road surface drawing device 1 according to the first embodiment. Figure 4 illustrates an example of a road surface drawing pattern P1 in a transition curve section R1. Figure 5 illustrates an example of a road surface drawing pattern P2 in a transition curve section R1. Figure 6 illustrates an example of a road surface drawing pattern P3 in a curve section R2. In the road surface drawing device 1 of this embodiment, the road surface drawing patterns P1 to P3 change depending on the steering angle, vehicle speed, and angular velocity of the steering angle of the vehicle 100.

[0021] As illustrated in Fig. 3, the vehicle 100 includes a vehicle speed sensor 11, a steering angle sensor 12, a differentiator 13, and a vehicle control unit 20. The vehicle speed sensor 11 acquires the speed of the vehicle 100 while it is traveling and transmits vehicle speed information VI including the vehicle speed to the vehicle control unit 20. The steering angle sensor 12 acquires the steering angle of the vehicle 100 while it is traveling and transmits steering angle information AI including the steering angle to the vehicle control unit 20 and the differentiator 13. The differentiator 13 time-differentiates the received steering angle information AI to calculate the angular velocity of the steering angle. The differentiator 13 transmits angular velocity information ARI including the angular velocity of the steering angle to the vehicle control unit 20.

[0022] Based on the vehicle speed information VI and the steering angle information AI, the vehicle control unit 20 calculates the radius of curvature of the course on which the vehicle 100 is traveling. Furthermore, based on the vehicle speed information VI, the steering angle information AI, and the angular velocity information ARI, the vehicle control unit 20 calculates the rate of change of the radius of curvature of the course on which the vehicle 100 is scheduled to travel.

[0023] The road surface drawing control unit 7 controls the light source 5 so that the road surface drawing patterns P1 to P3 change based on the radius of curvature of the course and the rate of change of the radius of curvature of the course calculated by the vehicle control unit 20.

[0024] As illustrated in FIGS. 4 to 6 , a road may include a transition curve section R1 and a curve section R2. The curve section R2 is a section that curves at a constant radius of curvature. The transition curve section R1 is a section that connects a straight section (not shown) with a curve section R2, or between curve sections. The transition curve section R1 is configured so that the radius of curvature gradually changes to be equal to the radius of curvature of the curve section. The transition curve section R1 is provided so that the steering angle operation by the driver does not become too abrupt. In other words, the transition curve section R1 is a section in which the radius of curvature gradually and monotonically increases or decreases.

[0025] Since the radius of curvature of the transition curve section R1 changes gradually, the vehicle 100 traveling on the transition curve section R1 travels so that the angular velocity of the steering angle is equal to or greater than a certain value. On the other hand, since the radius of curvature of the curve section R2 and the straight section does not change, the vehicle 100 traveling on the curve section R2 and the straight section travels so that the angular velocity of the steering angle is approximately zero.

[0026] The road surface drawing patterns P1 to P3 displayed from a vehicle 100 traveling on a transition curve section R1 and a curve section R2 will now be described. Note that in FIGS. 4 to 6, the radii of curvature of the outer edge line L at points p1, p2, and p3 are illustrated to explain the curvature of the road surface drawing patterns P1 to P3. Points p1, p2, and p3 are set as points on the outer edge line L on the right side as seen from the vehicle 100 in the road surface drawing patterns P1 to P3. The outer edge line L extends forward of the vehicle 100 and is an example of a curve extending forward of the vehicle 100. Point p1 is set to be closer to the vehicle 100 than points p2 and p3. Point p2 is set to be closer to the vehicle 100 than point p3.

[0027] 4, the radius of curvature of the outer edge L of the road surface pattern P1 at point p1 is r1, which is calculated based on the vehicle speed information VI and the steering angle information AI.

[0028] As illustrated in FIG. 4 , the radius of curvature of the outer edge line L of the road surface drawing pattern P1 at points p2 and p3 is set to gradually decrease as the radius of curvature of the road surface drawing pattern P1 decreases. The radius of curvature of the outer edge line L of the road surface drawing pattern P1 at point p2 is a1·r1. The radius of curvature of the outer edge line L of the road surface drawing pattern P1 at point p3 is a2·r1. Here, a1 and a2 are coefficients used to correct the radius of curvature of the road surface drawing pattern P1, which is determined by the rate of change of the radius of curvature of the road surface, calculated based on the vehicle speed information VI, steering angle information AI, and angular velocity information ARI. As illustrated in FIG. 4 , when the radius of curvature of the road surface decreases, 0<a2<a1<1 holds. Conversely, when the radius of curvature of the road surface increases, a2>a1>1 holds.

[0029] By displaying the outer edge line L in this manner, it is possible to display the outer edge line L along the road ahead of the vehicle 100 in which the device is installed.

[0030] In the example of FIG. 5, the vehicle 100 is traveling with a larger steering angle than in the example of FIG.

[0031] As shown in Fig. 5, the radius of curvature of the outer edge L of the road surface pattern P2 at point p1 is r2. The radius of curvature r2 is calculated based on the vehicle speed information VI and the steering angle information AI. In the examples of Figs. 4 and 5, r2<r1.

[0032] As illustrated in FIG. 5 , the radius of curvature of the outer edge line L of the road surface drawing pattern P1 at points p2 and p3 is set to gradually decrease as the radius of curvature of the road surface drawing pattern P1 decreases. The radius of curvature of the outer edge line L of the road surface drawing pattern P1 at point p2 is b1×r2. The radius of curvature of the outer edge line L of the road surface drawing pattern P1 at point p3 is b2×r2. Here, b1 and b2 are coefficients used to correct the radius of curvature of the road surface drawing pattern P2, which is determined by the rate of change of the radius of curvature of the road surface calculated based on the vehicle speed information VI, steering angle information AI, and angular velocity information ARI. As illustrated in FIG. 5 , when the radius of curvature of the road surface decreases, 0<b2<b1<1 holds. Conversely, when the radius of curvature of the road surface increases, b2>b1>1 holds.

[0033] If the angular velocity of the steering angle is smaller in the example shown in Fig. 5 than in the example shown in Fig. 4, the rate of decrease in the curvature of the outer edge line L in Fig. 5 will be smaller than the rate of decrease in the curvature of the outer edge line L in Fig. 4. For this reason, the road surface drawing pattern P2 is displayed so that the coefficients a1, a2, b1, and b2 satisfy a1<b1 and a2<b2.

[0034] Conversely, if the angular velocity of the steering angle is greater in the case illustrated in Fig. 5 than in the case illustrated in Fig. 4, the rate of decrease in the curvature of the outer edge line L in Fig. 5 will be greater than the rate of decrease in the curvature of the outer edge line L in Fig. 4. For this reason, the road surface drawing pattern P2 is displayed so that the coefficients a1, a2, b1, and b2 satisfy the relationships b1<a1 and b2<a2.

[0035] On the other hand, in the example of Fig. 6, the vehicle 100 is traveling with a larger steering angle than in the example of Fig. 5. However, since the vehicle 100 is traveling on the curved section R2, the angular velocity of the steering angle is approximately zero.

[0036] As shown in Figure 6, the radius of curvature of the outer edge line L of the road surface pattern P3 at points p1, p2, and p3 is r3. The radius of curvature r3 is calculated based on the vehicle speed information VI and the steering angle information AI, and does not have to be calculated based on the angular velocity information ARI. Note that r3<r2<r1.

[0037] By displaying the outer edge line L in this manner, it is possible to display the outer edge line L along the road ahead of the vehicle 100 in which the device is installed, even if the steering angle changes.

[0038] By displaying the outer edge lines extending forward of the vehicle other than the outer edge line L in the same manner, road surface drawing patterns P1 and P2 can be displayed along the road ahead of the vehicle 100 in which the vehicle is installed.

[0039] 7 illustrates a road surface drawing pattern P0 in a comparative example. In the example of Fig. 7, the vehicle 100 is traveling in the same location as in the example of Fig. 4 in the transition curve section R1.

[0040] The road surface drawing pattern P0 according to the comparative example is displayed according to only the vehicle speed and steering angle of the vehicle 100. Therefore, in the example of Figure 7, the radius of curvature of the outer edge line L at points p1, p2, and p3 is all r1.

[0041] However, because the radius of curvature of the transition curve section R1 gradually changes, the road surface drawing pattern P0 may deviate from the path that the vehicle 100 is supposed to follow. For example, the radius of curvature of the path in the example of Fig. 7 gradually decreases. However, because the road surface drawing pattern P0 does not change toward the front of the vehicle 100, the road surface drawing pattern P0 is displayed as extending outside the path that the vehicle 100 is supposed to follow.

[0042] In contrast, according to the road surface drawing device 1 of this embodiment, the road surface drawing patterns P1, P2 change in accordance with the steering angle, vehicle speed, and angular velocity of the steering angle. Therefore, even if the curvature of the road ahead of the vehicle 100 gradually changes, the road surface drawing device 1 can easily display the road surface drawing patterns P1, P2 that follow the road.

[0043] A threshold value for the angular velocity of the steering angle may be set in the road surface drawing device 1. When the angular velocity of the steering angle is equal to or greater than the threshold value, the road surface drawing control unit 7 determines that the vehicle 100 is traveling on a transition curve section R1, and controls the light source 5 to display road surface drawing patterns P1 and P2 in accordance with the steering angle, vehicle speed, and angular velocity of the steering angle. When the angular velocity of the steering angle is less than the threshold value, the road surface drawing control unit 7 determines that the vehicle 100 is traveling on a curve section R2, and controls the light source 5 to display road surface drawing pattern P3 in accordance with the steering angle and vehicle speed.

[0044] According to this road surface drawing device 1, when the angular velocity of the steering angle of the vehicle 100 is large, it is possible to display road surface drawing patterns P1, P2 that also correspond to the angular velocity of the steering angle. Therefore, even when the curvature of the vehicle's path gradually changes, the road surface drawing device 1 can easily display road surface drawing patterns P1, P2 that match the path along which the vehicle 100 is traveling.

[0045] Furthermore, when the vehicle 100 is traveling on a straight section or a curved section R2, the angular velocity of the steering angle is approximately zero. However, in reality, since the vehicle 100 travels while correcting the steering angle each time, the angular velocity of the steering angle may not be zero. In this case, if a road surface drawing pattern is formed taking the angular velocity of the steering angle into consideration, the road surface drawing pattern may be displayed with a fluctuation. In the road surface drawing device 1 of this embodiment, when the angular velocity of the steering angle is less than a threshold value, the angular velocity of the steering angle is not taken into consideration when forming the road surface drawing pattern. Therefore, even when the vehicle 100 is traveling on a straight section or a curved section R2, the display of the road surface drawing pattern P3 is less likely to fluctuate.

[0046] As illustrated in Fig. 6, when the angular velocity of the steering angle is smaller than the threshold value, the road surface drawing pattern P3 is displayed so that the radius of curvature of the outer edge line L is a constant curvature that corresponds to the vehicle speed and steering angle of the vehicle 100. On the other hand, as illustrated in Fig. 4 and Fig. 5, when the angular velocity of the steering angle is equal to or greater than the threshold value, the curvature of the outer edge line L increases or decreases as the vehicle 100 moves forward, depending on the vehicle speed, steering angle, and angular velocity of the steering angle of the vehicle 100.

[0047] This makes it easier for the outer edge lines L of the road surface drawing patterns P1 and P2 to be displayed along the path of the vehicle 100, even if the curvature of the path of the vehicle 100 gradually changes.

[0048] The road surface drawing patterns P1 to P3 display guides that serve as reference for where the vehicle 100 should pass. Specifically, the road surface drawing patterns P1 to P3 are composed of two linear patterns of a fixed width that are displayed on the right and left front of the vehicle 100, and the vehicle 100 is guided to move along the center of both patterns.

[0049] This makes it less likely for the driver to misjudge the route when the vehicle 100 is traveling around a curve, reducing the burden on the driver when operating the vehicle.

[0050] 1, the road surface pattern P has two outer edge lines L, L' spaced apart by at least the vehicle width B1, which makes it easier for the driver of the vehicle 100 to recognize in which direction the vehicle 100 should travel.

[0051] 1, the headlamp 60 includes a road surface drawing device 1 and a headlamp unit 10. The headlamp unit 10 is configured to illuminate the area ahead of the vehicle 100. With this configuration, the headlamp 60 accommodates the road surface drawing device 1 inside the headlamp 60, so that the road surface drawing device 1 can be installed in a space-saving manner.

[0052] 1, the headlamp unit 10 includes a low beam unit 70 and a high beam unit 80. The road surface drawing device 1 is located outward in the vehicle width direction from the low beam unit 70 and the high beam unit 80. The road surface drawing pattern P has two outer edge lines L, L' spaced apart by a distance equal to or greater than the vehicle width.

[0053] Such a road surface drawing device 1 is positioned outboard in the vehicle width direction relative to the low beam unit 70 and the high beam unit 80, making it easy to display a road surface drawing pattern P having a width equivalent to the vehicle width. This reduces the difference between the road surface drawing pattern P displayed on the road surface and the originally intended pattern, even when the vehicle 100 is traveling around a curve.

[0054] Second Embodiment Next, road surface drawing patterns P4 and P5 of a second embodiment for a transition curve section R1 will be described with reference to Figures 8 and 9. Figure 8 illustrates an example of a road surface drawing pattern P4 of the second embodiment for a transition curve section R1. Figure 9 illustrates an example of a road surface drawing pattern P5 of the second embodiment for a transition curve section R1.

[0055] In the transition curve section R1, the road surface drawing patterns P1 and P2 are configured so that the curvature of the outer edge line L increases or decreases toward the front of the vehicle 100. On the other hand, the road surface drawing patterns P4 and P5 of the second embodiment are configured so that the curvature of the outer edge line L is uniform even in the transition curve section R1.

[0056] When the angular velocity of the steering angle is smaller than the threshold value, that is, when the vehicle 100 is traveling on a straight section and a curved section R2, the outer edge line L has a uniform curvature depending on the vehicle speed and steering angle of the vehicle 100.

[0057] When the angular velocity of the steering angle is equal to or greater than a threshold value, that is, when the vehicle 100 is traveling on a transition curve section R1, taking into account the angular velocity of the steering angle, the outer edge line L has a uniform curvature that is different from the curvature of the outer edge line L when traveling on a straight section and a curve section R2.

[0058] 8, when the angular velocity of the steering angle is equal to or greater than a threshold, the radius of curvature of the path corresponding to the vehicle speed and steering angle is assumed to be r1. In this case, when the steering angle increases, the road surface drawing pattern P4 is displayed so that the radius of curvature of the outer edge line L becomes r4, which satisfies r4<r1.

[0059] Furthermore, as illustrated in Figure 9, even if the radius of curvature of the course according to the vehicle speed and steering angle is r2 such that r2 < r1, if the steering angle increases, the road surface drawing pattern P5 is displayed so that the radius of curvature of the outer edge line L becomes r5 such that r5 < r4 and r5 < r2.

[0060] In the road surface drawing patterns P4 and P5 of the second embodiment, when the angular velocity of the steering angle is equal to or greater than a threshold value, the curvature of the curved line L of the road surface drawing patterns P4 and P5 extending forward of the vehicle 100 differs from the curvature determined according to the vehicle speed and steering angle. This makes it easier for the outer edge line L of the road surface drawing patterns P4 and P5 to be displayed along the path of the vehicle 100.

[0061] Furthermore, whether the angular velocity of the steering angle is greater than or less than the threshold value, the curved lines that form the outer edges L of the road surface drawing patterns P4 and P5 have a uniform curvature, which makes it easy to simplify the configuration for displaying the road surface drawing patterns P4 and P5.

[0062] (Modification 1) Next, a road surface drawing device 101 according to Modification 1 will be described. Fig. 10 illustrates the road surface drawing device 101 according to Modification 1. As illustrated in Fig. 10, the road surface drawing device 101 and a headlight unit 150 are provided separately on a vehicle 200. The headlight unit 150 is configured to be able to emit low beams and high beams. The road surface drawing device 101 is positioned outward of the headlight unit 150 in the vehicle width direction.

[0063] In this way, the road surface drawing device 101 according to the first modification is positioned outside the headlamp unit 150, which is capable of emitting both low and high beams. This makes it easy to display a road surface drawing pattern having outer edge lines spaced apart by more than the vehicle width. This reduces the difference between the road surface drawing pattern P displayed on the road surface and the originally intended pattern, even when the vehicle 200 is going around a curve.

[0064] (Variation 2) Next, a road surface drawing device 201 according to Variation 2 will be described. Fig. 11 illustrates the road surface drawing device 201 according to Variation 2. As in the road surface drawing device 201 according to Variation 2, light may also be irradiated onto the area between the outer edge lines L and L' in the road surface drawing pattern P6.

[0065] The present disclosure has been described above based on the embodiments. The present embodiment is an example of the present disclosure, and is not limited to the above-described embodiment, and can be freely modified, improved, etc. as appropriate. In addition, the material, shape, dimensions, numerical values, form, number, placement location, etc. of each component in the above-described embodiment are arbitrary and not limited as long as the present disclosure can be achieved.

[0066] This application claims priority based on Japanese Patent Application No. 2023-172994 filed on October 4, 2023, and incorporates by reference all the contents of the above application.

Claims

1. A road surface drawing device for a vehicle that displays a road surface drawing pattern along the road ahead of the vehicle in which it is installed, wherein the road surface drawing pattern changes according to the steering angle, vehicle speed, and angular velocity of the steering angle of the vehicle.

2. A road surface drawing device for a vehicle as described in claim 1, wherein, when the angular velocity of the steering angle is smaller than a threshold value, the road surface drawing pattern corresponding to the vehicle speed and the steering angle of the vehicle is displayed, and when the angular velocity of the steering angle is equal to or greater than the threshold value, the road surface drawing pattern corresponding to the vehicle speed, the steering angle, and the angular velocity of the steering angle is displayed.

3. A road surface drawing device for a vehicle as described in claim 2, wherein an outer edge line of the road surface drawing pattern includes a curve extending toward the front of the vehicle, and when the angular velocity of the steering angle is smaller than the threshold value, the curvature of the curve is a constant curvature that corresponds to the vehicle speed and the steering angle of the vehicle, and when the angular velocity of the steering angle is equal to or greater than the threshold value, the curvature of the curve increases or decreases toward the front of the vehicle depending on the vehicle speed, the steering angle, and the angular velocity of the steering angle.

4. A road surface drawing device for a vehicle as described in claim 2, wherein an outer edge line of the road surface drawing pattern includes a curve extending toward the front of the vehicle, and when the angular velocity of the steering angle is smaller than the threshold value, the curve has a uniform curvature depending on the vehicle speed and the steering angle of the vehicle, and when the angular velocity of the steering angle is equal to or greater than the threshold value, the curve has a uniform curvature different from the curvature depending on the vehicle speed and the steering angle of the vehicle.

5. A road surface drawing device for a vehicle according to any one of claims 1 to 4, wherein the road surface drawing pattern displays a guide to serve as a reference for where the vehicle should pass.

6. A road surface drawing device for a vehicle according to any one of claims 1 to 5, wherein the road surface drawing pattern has two outer edge lines spaced apart by a width of the vehicle or more.

7. The road surface drawing device for a vehicle according to claim 6, which is positioned outside a headlamp unit capable of emitting low beam and high beam.

8. A vehicle headlamp comprising: a vehicle road surface drawing device according to any one of claims 1 to 7; and a headlamp unit that illuminates the area ahead of the vehicle.

9. A vehicle headlamp as claimed in claim 8, wherein the headlamp unit comprises a low beam unit and a high beam unit, the vehicle road surface drawing device is positioned outboard in the vehicle width direction relative to the low beam unit and the high beam unit, and the road surface drawing pattern has two outer edge lines spaced apart by a distance equal to or greater than the vehicle width.