JP4266175B2 - Vehicle lighting device - Google Patents

Description

  The present invention relates to an illumination device for a vehicle that includes an additional lighting lamp that supplementarily illuminates the front of the vehicle when a vehicle such as an automobile travels on a curved road.

In order to improve the driving safety of the car, in addition to the main lamp that illuminates the vehicle's headlight as the headlight of the car, an additional lighting lamp is arranged as a secondary lamp that illuminates the front or side of the car. AFS (Adaptive Front-lighting System) is a system that expands the lighting range to the side of the car by turning on the additional lighting lamp when the car runs on a curved road. Proposed. According to this AFS, on / off of the additional lighting lamp is controlled based on the steering angle when the vehicle travels on a curved road, and the additional lighting lamp is turned on when the vehicle is in a predetermined curved road state. The illuminance in the traveling direction of the automobile can be increased, and the traveling safety can be increased. As such an illuminating device, there are technologies described in Patent Document 1 and Patent Document 2.
JP 2001-213227 A JP 2003-170777 A

  In such an illuminating device having an additional lighting lamp, in order to increase the effectiveness of the illumination by the additional lighting lamp, the lighting / extinction of the additional lighting lamp is controlled based on the steering angle and the vehicle speed of the vehicle. It has been broken. For example, in Patent Document 1, dimming control is performed in which the light amount (luminance) of the additional lighting lamp is gradually changed according to the rudder angle, and thereby the driver by suddenly turning on / off the additional lighting lamp. It prevents the feeling of discomfort and the fear of pedestrians. Further, in Patent Document 2, the dimming control of the additional lighting lamp is performed according to the steering angle, and the lighting / extinguishing timing of the additional lighting lamp is controlled according to the vehicle speed of the vehicle. While ensuring the brightness, it prevents the driver from feeling uncomfortable.

The technique of Patent Document 1 and 2 are both are common in that they perform a dimming control of the additional lighting lamp in response to the steering angle, yet for the steering angle is increased when the light control Along with this, control is performed to increase the luminous intensity of the additional lighting lamp. This is considered to be a case where the vehicle travels on a curved road with a small radius of curvature, that is, a so-called sharp curve when the vehicle travels with a large steering angle. Based on the high need for lighting. For this reason, depending on the driving situation, there may be a situation where the brightness of the illumination by the additional lighting lamp does not match the actual situation, which promotes a sense of incongruity for the driver or creates an unfavorable situation in terms of safe driving. Sometimes it ends up. For example, when the additional lighting lamp is turned on when the vehicle is traveling on a curved road at a so-called medium speed of about 30 km / h, the side lighting of the vehicle by the additional lighting lamp is too bright and the driver's The line of sight is attracted to the side of the automobile, and the line of sight deviates from the traveling direction. In particular, this is likely to occur when the illumination light of the additional lighting lamp is reflected by a guardrail on the road, or when the illumination light is reflected by a snow wall existing on the road shoulder.

  In order to alleviate the problems caused by lighting such an additional lighting lamp, in Patent Document 1, the dimming characteristics of the additional lighting lamp are set in advance as a plurality of different dimming modes, and the driver manually The dimming mode selection switch is operated by or the dimming mode is automatically selected depending on the brightness of the driving environment. In Patent Document 2, as described above, the steering angle at which lighting of the additional lighting lamp is started is controlled in accordance with the vehicle speed.

  However, in the technique of Patent Document 1, since it is necessary to operate the dimming mode changeover switch based on the driver's judgment, the driver is required to perform an extra operation. This is not preferable for safe driving. In addition, although the dimming mode is switched automatically, the dimming mode is selected only based on the surrounding brightness. This makes it difficult to solve the above-mentioned problems. On the other hand, in the technique of Patent Document 2, when the additional lighting lamp is lit, it is always lit with the same brightness. Therefore, once the additional lighting lamp is lit, the above-described problem can be solved. Almost impossible.

  An object of the present invention is to enable a safe driving by preventing such a problem that the driver's line of sight is attracted to the side when the additional lighting lamp is turned on or a pedestrian is feared. An illumination device for a vehicle is provided.

A first aspect of the present invention includes an additional lighting lamp that supplementarily illuminates the front or side of the vehicle, and a control unit that controls lighting / extinguishing of the additional lighting lamp following the steering angle of the vehicle. In the vehicle lighting device, the control means turns on the additional lighting lamp when the steering angle becomes equal to or greater than the predetermined steering angle, and changes the luminous intensity when the steering angle changes, and changes the luminous intensity. The dimming rate (the change rate of the luminous intensity with respect to the change in the steering angle) is controlled to change according to the traveling state of the vehicle. For example, the dimming rate is controlled to decrease as the vehicle speed increases.

According to a second aspect of the present invention, there is provided an additional lighting lamp that illuminates the front or side of the vehicle in an auxiliary manner, and a control unit that controls lighting / extinction of the additional lighting lamp following the steering angle of the vehicle. In the vehicular lighting device, the control means turns on the additional lighting lamp when the steering angle is equal to or greater than the predetermined steering angle, and changes the luminous intensity when the steering angle changes, and this luminous intensity It is characterized in that the maximum luminous intensity that can be changed is controlled to change according to the traveling state of the vehicle. For example, the maximum luminous intensity is controlled to increase as the vehicle speed increases.

According to the present invention, when the additional lighting lamp is turned on according to the traveling state of the vehicle, in particular, the vehicle speed, the dimming rate when changing the light intensity at the time of lighting along with the change of the steering angle is decreased as the speed is increased. By controlling so that the maximum luminous intensity of the additional lighting lamp increases as the vehicle speed increases, the driver changes the luminous intensity when lighting with changes in the steering angle. Driving without any extra operation, and without turning off the driver's line of sight from the driving direction by turning on the additional lighting lamp, and on the other hand, driving without fear of pedestrians can be realized, and safe driving Can be secured.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a schematic diagram of an automobile provided with an additional lighting lamp. A left headlight LL is arranged on the left of the front part of the car CAR, and a right headlamp LR is arranged on the right. These headlamps LL and LR are main lamps 1L and 1R that illuminate the straight direction of the car, respectively. And additional lighting lamps 2L and 2R as auxiliary lamps for illuminating the left front and right front of the vehicle, respectively. As shown in FIG. 2A, the left and right headlamps LL, LR have the optical axes of the main lamps 1L, 1R directed in the straight direction of the car CAR, and these main lamps 1L , 1R illuminates a required range in front of the car CAR in a straight line direction. In addition, as shown in FIG. 2B, the additional lighting lamp 2L of the left headlamp LL is lit with its optical axis inclined to the left by a required angle with respect to the straight traveling direction of the automobile. Sometimes, in addition to the illumination in the straight direction by the main lamps 1L and 1R, the area closer to the left is illuminated. On the contrary, as shown in FIG. 2 (c), the additional lighting lamp 2R of the right headlamp LR has its optical axis tilted to the right by a required angle with respect to the straight traveling direction of the automobile. In this case, in addition to the illumination in the straight direction by the main lamps 1L and 1R, the area near the right side is illuminated.

  FIG. 1B is a block diagram of an electrical system of the headlamps LL and LR, and the left and right headlamps LL and LR are configured to be controlled by a control circuit 3. The control circuit 3 includes a steering angle sensor 4 for detecting the steering angle of the automobile operated by the steering wheel SW of the automobile CAR, a vehicle speed sensor 5 for detecting the vehicle speed of the automobile CAR, and a car navigator. In the case of an automobile, the car navigators 6 are connected to each other. The detected steering angle signal of the automobile is input to the control circuit 3 from the steering angle sensor 4, and the detected vehicle speed signal of the automobile is input to the control circuit 3 from the vehicle speed sensor 5. The car navigator 6 inputs a driving condition signal indicating the condition of the road on which the car CAR is driven to the control circuit 3.

  According to such an illumination device including the headlamps LL and LR, the main lamps 1L and 1R are turned on by turning on a lighting switch (not shown) when the automobile CAR is running. When the car CAR enters a curved road and is steered by the steering wheel SW, a steering angle signal from the steering angle sensor 4 is input to the control circuit 3, and the control circuit 3 detects the left and right fronts based on the steering angle signal. Of the headlamps LL and LR, the additional lighting lamp 2L or 2R of the headlamp on the steering direction side is turned on. Thus, as shown in FIG. 2 (a), the light distribution by the main lamps 1L and 1R and the light distribution by the additional lighting lamps 2L or 2R illuminate the straight traveling direction and the steering direction of the vehicle, and the driver can turn It becomes easy to confirm the destination of the road.

  FIG. 3A is a diagram showing the dimming rate when the additional lighting lamps 2L and 2R are turned on during steering in the first embodiment. The horizontal axis is the vehicle speed, and the vertical axis is the dimming rate. Here, the dimming rate indicates a ratio of increasing the luminous intensity of the additional lighting lamp with respect to the steering angle, that is, (increased luminous intensity) / (increased steering angle). Further, as shown in FIG. 3, the dimming rate is set to be large on the low speed side and small on the high speed side, and the dimming rate continuously changes with respect to the vehicle speed. . The left and right additional lighting lamps 2L and 2R have the same dimming rate characteristics, and FIG. 3 shows only one of the left and right.

  FIGS. 4 (a) to 4 (c) show steering characteristics at 15 km / h, 30 km / h, and 60 km / h, respectively, as representatives of the low speed, medium speed, and high speed of the automobile in the dimming rate characteristics shown in FIG. 3 (a). The luminous intensity characteristic of the additional lighting lamp with respect to the corner is shown. In each figure of FIG. 4, the horizontal axis indicates the steering angle, the vertical axis OFF indicates that the additional lighting lamp is turned off, and ON indicates that the lamp is lit at the maximum luminous intensity. The inclination of these characteristics is shown in FIG. The light control rate is a). As shown in FIGS. 4A and 4B, when the steering wheel SW is steered and the steering angle becomes equal to or greater than a preset lighting reference rudder angle θ2, the additional lighting lamp starts to light and gradually increases its luminous intensity. The light is adjusted so that the maximum luminous intensity of the additional lighting lamp is obtained. The light control rate is large at the low speed (15 km / h) in FIG. 4A, is smaller at the medium speed (30 km / h) in FIG. 4B, and is high at 60 km / h in FIG. 4C. In h), it is further reduced.

  In addition, when the additional lighting lamp is turned off, the dimming rate is changed according to the difference in the vehicle speed. Here, as can be seen from FIGS. 4 (a) to 4 (c), each vehicle speed is turned on. The light is turned off at almost the same dimming rate. In this case, the turn-off reference rudder angle θ1 for starting to turn off the additional turn-on lamp is set to a steering angle smaller than the turn-on reference rudder angle θ2. This is set to prevent so-called lighting hunting, in which the additional lighting lamp frequently repeats lighting and extinguishing in a driving situation where the steering angle is slightly changed.

  FIG. 5 is a flowchart for explaining dimming control of the headlamp performed based on the diagram of FIG. First, when the lighting switch of the automobile is turned on (S101), the main lamps 1L and 1R of the left and right headlamps LL and LR are lit, and the vehicle travels straight in the light distribution characteristic shown in FIG. Is illuminated (S102). When the vehicle enters a curved road and steering is performed by the steering wheel SW, the control circuit 3 recognizes the steering angle from the steering angle signal from the steering angle sensor 4 (S103). The steering direction is determined based on the recognized steering angle (S104). If the steering direction is the right direction, the process proceeds to the right headlamp process flow S200. If the steering direction is the left direction, the process proceeds to the left headlamp process flow S300. Further, when the steering direction is the straight traveling direction, the headlamp processing flow according to the present invention is not executed.

  In the right headlamp processing flow S200, the control circuit 3 detects the vehicle speed based on the vehicle speed signal from the vehicle speed sensor 5 (S201). When the vehicle speed is detected, a dimming rate corresponding to the vehicle speed is set based on the characteristics shown in FIG. 3A (S202). Then, the recognized steering angle is compared with the lighting reference rudder angle θ2 (S203), and the lighting of the additional lighting lamp 2R for the right headlamp LR is started when the steering angle is equal to or larger than the lighting reference rudder angle θ2. As the steering angle further increases, the current supplied to the additional lighting lamp 2R is increased, and the luminous intensity is gradually increased based on the set dimming rate (S204). This increase in light intensity is finally adjusted until the maximum light intensity is reached. Thereby, the illumination of the light distribution characteristic shown in FIG.2 (c) is performed, and the illumination of the diagonally forward right is performed in addition to the straight direction of a motor vehicle.

  On the other hand, after the additional lighting lamp 2R is turned on, a change in the steering angle is determined (S205), and when the steering angle is reduced by directing the steering direction, the control circuit 3 turns off the reference steering angle. Comparison with θ1 is performed (S206). When the steering angle becomes smaller than the turn-off reference rudder angle θ1, the control circuit 3 starts to reduce the current supplied to the additional lighting lamp 2R based on the characteristic at the set dimming rate, and gradually increases the luminous intensity. The light is adjusted until it is finally turned off (S207). Thereby, the illumination is only performed by the main lamps 1L and 1R, and the light distribution characteristics shown in FIG. 2A are restored. Note that the left headlight processing flow S300 is the same as the right headlight processing flow S200, and a description thereof will be omitted.

  As described above, since the luminous intensity of the additional lighting lamp is increased in a short time with a large dimming rate at a low speed, the maximum luminous intensity is reached when the steering angle is slightly increased. At low speeds, the driving situation is such as turning at a sharp curve or intersection with a small radius of curvature. In such a case, it is preferable to promptly illuminate the destination of the vehicle in terms of safe driving. On the other hand, when you finish the turn, you can quickly eliminate the dazzling situation of pedestrians by quickly reducing the luminous intensity of the additional lighting lamps that are already illuminating the direction deviating from the running direction. At the same time, it eliminates the uncomfortable feeling that the driver's line of sight is attracted to the side. In addition, in the case of low speed, even if the additional lighting lamp is suddenly turned on, there is little possibility of causing a pedestrian to feel a fear.

  The brightness of the additional lighting lamp is increased at medium speeds with a smaller dimming rate than at low speeds. It is a driving situation where the radius of curvature is a curve of a general road with a larger radius of curvature than at low speeds at medium speed, but there is less need to turn on the additional lighting lamp when the steering angle is small, and it is added when the steering angle is large The need to turn on the lighting fixture is somewhat greater. Therefore, the luminous intensity is slowly increased when the additional lighting lamp is turned on compared to the low speed, and the luminous intensity is slowly reduced when the additional lamp is turned off. Therefore, even if the pedestrian is nearby, the pedestrian will not be afraid, and at the same time, the driver will feel uncomfortable and the driver's line of sight will not be attracted to the side. In terms of surface.

  The light intensity of the additional lighting lamp is gradually increased at a high speed with a smaller dimming rate than at the medium speed. At high speeds, it is a driving situation where the radius of curvature is a curve such as an expressway with a larger radius of curvature than at medium speed, but when the steering angle is small, there is almost no need to turn on the additional lighting lamp, and the steering angle is There are few driving situations that become larger than a certain amount except for special driving conditions such as hairpin curves. Therefore, the luminous intensity is increased more slowly when the additional lighting lamp is turned on than when it is in the middle speed, and the luminous intensity is reduced more slowly when it is turned off. Here, there are very few cases where a pedestrian is in the vicinity, which is preferable in terms of safe driving by exclusively eliminating a sense of incongruity in the driver and suppressing the driver's line of sight from being attracted to the side.

  As described above, in the first embodiment, since the dimming rate is automatically controlled in accordance with the vehicle speed, there is no operation burden on the driver during driving. In addition, by controlling the change of the light control rate, the driver does not feel uncomfortable as described above, and the problem of safe driving due to the fact that the line of sight is attracted to the side does not occur. On the other hand, there is no fear of pedestrians.

  In the first embodiment, an example in which the change in the dimming rate is continuously changed corresponding to the change in the vehicle speed is shown. In the second embodiment, the vehicle speed is divided into regions such as a low speed, a medium speed, and a high speed. The characteristics correspond to the category. For example, as shown in FIG. 3B, when the vehicle speed is 15 km / h or less, the vehicle speed is classified as high speed when the vehicle speed exceeds 15 and 40 km / h or less and the vehicle speed exceeds 40 km / h. Each dimming rate is set to a different specific value. As a result, the characteristic is based on a high dimming rate as shown in FIG. 4 (a) at low speed, the characteristic based on the intermediate dimming rate shown in FIG. 4 (b) at medium speed, and the characteristic shown in FIG. 4 (c) at high speed. The characteristic is based on the low dimming rate shown in FIG.

  The dimming operation in the second embodiment is basically the same as the flow in FIG. 5, but in the second embodiment, in the right headlamp processing flow S200 shown in FIG. 5, as shown in FIG. Then, after step S201 in which the vehicle speed is detected, a determination step S211 for dividing the vehicle speed is performed, and the dimming rate selected in advance in each of the determined vehicle speed divisions is dimmed at a low dimming rate / large and medium speed. The one corresponding to the dimming rate / small is selected at high / medium / high speed (S212, S213, S214). Thereafter, the steering angle is compared with the lighting reference steering angle in the same manner as shown in FIG. 5 (S203). The same applies to the left headlamp processing flow S300. In the second embodiment, the dimming rate can be selected and set from a plurality of predetermined values, so that the processing in the control circuit 3 can be simplified.

  In Examples 1 and 2, the example in which the dimming rate at each speed is a characteristic having a predetermined slope is shown, but in Example 3, the dimming rate is changed and controlled stepwise as shown in FIG. . Further, in this case, the number of steps of the light control rate, the amount of increase in luminous intensity, and the like may be varied depending on the vehicle speed. In FIG. 7 (a), it is set to light up in two steps from the lighting reference rudder angle, to light up in three steps at medium speed, and to light up with increasing light intensity in four steps at high speed. Further, even when the light is turned off, the light is turned off in two steps from the turn-off reference steering angle, and the light is turned off while reducing the light intensity by three steps at medium speed and four steps at high speed. In the third embodiment, a plurality of predetermined luminous intensity can be selected and set with respect to the steering angle, so that the control in the control circuit 3 can be simplified.

  In the first to third embodiments, since the light intensity is gradually increased when the additional lighting lamp is turned on, the additional lighting lamp in the steering direction is gradually brightened from the viewpoint of other vehicles and pedestrians. Therefore, it is possible to determine in which direction the vehicle travels, and it is also possible to exert a function as a direction indicator lamp.

  FIG. 8 is a diagram for explaining dimming control for turning on / off the additional lighting lamps 2L, 2R accompanying steering in the fourth embodiment. Here, when the steering wheel SW is steered and the steering angle exceeds a preset lighting reference steering angle θ, lighting of the additional lighting lamp is started, and dimming is performed while gradually increasing the luminous intensity. It is the same as Examples 1-3. However, in the fourth embodiment, change control is performed at the same dimming rate regardless of the difference in vehicle speed, while the maximum luminous intensity of the additional lighting lamps 2L and 2R is changed in accordance with the vehicle speed. That is, the maximum luminous intensity is increased at high speeds, and the maximum luminous intensity is decreased at low speeds. Further, here, the maximum luminous intensity continuously changes following the change in the vehicle speed.

  As shown in FIG. 9, the right headlamp processing flow S200 in the fourth embodiment has dimming characteristics selected in each of the low speed, medium speed, and high speed sections after step S201 in which the vehicle speed is detected. Although the same, the maximum brightness is different from the maximum brightness / low at low speed, the maximum brightness / medium at medium speed, and the maximum brightness / high at high speed (S215, S216, S217). The same applies to the left headlamp processing flow S300.

  In the case of the fourth embodiment, the additional lighting lamps 2L and 2R are controlled to be turned on / off in accordance with the steering angle at both low speeds and high speeds, and in particular, control is performed to gradually increase the luminous intensity at the time of lighting. This is similar to the first to third embodiments in that it eliminates the driver's discomfort and is effective for safe driving, but in addition to this, the luminous intensity of the additional lighting lamp at high speed traveling on a general road or highway Can be used to illuminate the direction of travel when driving at high speeds, while reducing the intensity of the additional lighting lamps at low speeds when traveling at intersections in urban areas, etc. It is possible to secure lighting on a curved road at a medium speed when traveling on an urban road and reduce fear of a pedestrian. This makes it possible to further increase the safe driving of the automobile.

  FIG. 10 is a diagram for explaining dimming control for turning on / off the additional lighting lamps 2L, 2R accompanying steering in the fifth embodiment. In the fourth embodiment, the dimming rate when the additional lighting lamp is turned on is fixed to a predetermined value regardless of the difference in speed, but in the fifth embodiment, as in the first to third embodiments, depending on the vehicle speed. Thus, the dimming rate is made different and the maximum luminous intensity is made different according to the vehicle speed as in the fourth embodiment. Since the left and right headlamp processing flow in the fifth embodiment is a combination of the processing in the second and fourth embodiments, illustration and detailed description thereof are omitted here.

  In the case of the fifth embodiment, when the luminous intensity of the additional lighting lamp is increased, the dimming rate at the low speed is larger than that at the high speed, and the same effects as in the first to third embodiments can be obtained. Since the maximum luminous intensity is lower than that at high speed, it is possible to obtain the same effect as in the fourth embodiment.

  Although Embodiments 1 to 5 have been described above, the lighting / extinguishing control of the additional lighting lamp according to the present invention is to change and control the dimming rate and the maximum luminous intensity depending on the traveling state when the automobile travels. In Examples 1-5, the vehicle speed of the automobile is used as this traveling situation. However, in the automobile in which the navigator 6 is arranged as shown in FIG. 1, the traveling road information obtained from the navigator 6 is used as the traveling situation. On / off control may be performed based on the above.

  Here, when the additional lighting lamp according to the present invention is configured with a light bulb, as described above, the current supplied to the light bulb, the voltage, or the like is changed to change and control the dimming rate or the maximum luminous intensity. The lighting lamp may be composed of LEDs (light emitting diodes). In this case, in addition to controlling the LED drive current, dimming can be performed by changing the number of LEDs that make up the additional lighting lamp. The rate and the maximum luminous intensity may be controlled to change. Moreover, since the LED has a longer life compared to the light bulb, this is also advantageous in this respect.

  Further, in the above-described embodiment, an example is shown in which one additional lighting lamp is provided for each of the left and right headlamps. However, a plurality of additional lighting lamps having different optical axis directions are arranged in order. In this case, when turning on / off each additional lighting lamp, the dimming rate and maximum light intensity are controlled to change according to the vehicle speed. May be.

It is the schematic of the motor vehicle which applied the illuminating device of this invention, and the block circuit diagram of an electric system. It is a light distribution characteristic view of a car provided with an additional lighting lamp. FIG. 6 is a diagram showing the characteristics of the light control rate in Example 1. FIG. 3 is a diagram showing lighting / extinguishing characteristics in Example 1. FIG. 6 is a flowchart for explaining a turn-on / off control operation according to the first embodiment. FIG. 10 is a flowchart for explaining a lighting / extinguishing control operation according to the second embodiment. FIG. 6 is a diagram showing lighting / extinguishing characteristics of Example 3. FIG. 10 is a diagram showing lighting / extinguishing characteristics of Example 4. FIG. 10 is a flowchart for explaining a turn-on / off control operation of the fourth embodiment. FIG. 10 is a diagram showing lighting / extinguishing characteristics of Example 5.

Explanation of symbols

CAR SW SW Steering wheel LL Left headlight LR Right headlight 1L, 1R Main lamp 2L, 2R Additional lighting lamp 3 Control circuit 4 Steering angle sensor 5 Vehicle speed sensor 6 Navigator θ1 Turn-off reference steering angle θ2 Lighting reference steering angle

Claims (4)

In a vehicle lighting device comprising: an additional lighting lamp that illuminates the front or side of the vehicle in an auxiliary manner; and a control unit that controls lighting / extinguishing of the additional lighting lamp following a steering angle of the vehicle, The control means turns on the additional lighting lamp when the steering angle becomes equal to or greater than a predetermined steering angle, changes the luminous intensity at the time of lighting with the change of the steering angle, and adjusts the light when changing the luminous intensity. A vehicular lighting device, wherein the rate (the rate of change in luminous intensity with respect to a change in steering angle) is controlled to change in accordance with a running state of the vehicle.   The lighting device for a vehicle according to claim 1, wherein the dimming rate is reduced as the vehicle speed increases. In a vehicle lighting device comprising: an additional lighting lamp that illuminates the front or side of the vehicle in an auxiliary manner; and a control unit that controls lighting / extinguishing of the additional lighting lamp following a steering angle of the vehicle, The control means turns on the additional lighting lamp when the steering angle becomes equal to or greater than a predetermined steering angle, and changes the luminous intensity at the time of lighting with the change of the steering angle and can change the luminous intensity. A vehicular lighting device, wherein the maximum luminous intensity is controlled to change in accordance with a traveling state of the vehicle.   4. The vehicular lighting device according to claim 3, wherein the maximum luminous intensity is increased as the vehicle speed increases.

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