Vehicle headlight system

Abstract

The present invention further reduces the influence of a light curtain in front of a reference position of a vehicle.　This vehicle headlight system includes: a headlight installed in a vehicle and configured to be capable of emitting at least a high beam toward an area in front of the vehicle; a controller connected to the headlight; and a weather condition detection sensor installed in the vehicle and connected to the controller. On the basis of an output of the weather condition detection sensor, the controller controls the headlight so that the high beam is emitted in a first mode when it is not estimated that the weather is bad, and controls the headlight so that the high beam is emitted in a second mode when it is estimated that the weather is bad, the second mode being a mode in which an illumination amount of light to a first range, which is a relatively upper part in an illumination range of the high beam in the first mode, is relatively reduced compared with a second range, which is a part other than the first range.

Description

Vehicle headlight system

[0001] The present disclosure relates to a vehicle headlight system.

[0002] Japanese Patent No. 7236453 (Patent Document 1) describes a vehicle lamp that controls a variable light distribution lamp so as to reduce or zero the irradiation amount of a beam to a range where no irradiation target exists in a predetermined area ahead of the vehicle during snowfall or rainfall.

[0003] Japanese Patent No. 7236453

[0004] One of the objects of a specific embodiment according to the present disclosure is to provide a technology that can further reduce the influence of a light curtain ahead of a reference position of a vehicle.

[0005] A vehicle headlight system according to one aspect of the present disclosure includes: a headlight installed on a vehicle and configured to be capable of emitting at least a high beam to the front of the vehicle; a controller connected to the headlight; and a weather condition detection sensor installed on the vehicle and connected to the controller, wherein the controller controls the headlight such that the high beam is emitted in a first mode when bad weather is not estimated based on an output of the weather condition detection sensor, and when bad weather is estimated, the controller controls the headlight such that the high beam is emitted in a second mode in which an irradiation amount of light to a first range that is a relatively upper part of the irradiation range of the high beam in the first mode is relatively lower than that to a second range that is a part other than the first range. It is a vehicle headlight system.

[0006] According to the above configuration, in bad weather such as rainfall, it is possible to further reduce the influence of the light curtain ahead of the reference position of the vehicle.

[0007] Figure 1A is a block diagram showing the configuration of a vehicle headlight system according to the first embodiment. Figure 1B is a block diagram showing an example of the controller configuration. Figure 2A is a schematic plan view showing an example of the headlight configuration. Figure 2B is a diagram showing an example of the configuration of an ADB unit capable of emitting high beams and selective high beams. Figure 3A is a diagram illustrating the illumination ranges of high beams and low beams. Figure 3B is a diagram illustrating the dimming range provided for high beams in bad weather. Figure 4 is a diagram illustrating the principle of preventing the generation of a light curtain in bad weather. Figure 5 is a diagram illustrating the definitions of each parameter used to explain the principle of preventing the generation of a light curtain in more detail. Figure 6 is a flowchart showing the operation procedure of the vehicle headlight system according to the first embodiment. Figure 7 is a diagram showing an example of multiple sets of data that are set according to the vehicle type and stored in memory. Figure 8 is a flowchart showing the operation procedure of the vehicle headlight system according to the second embodiment. Figure 9 is a flowchart showing the operation procedure of the vehicle headlight system according to the third embodiment. Figure 10 is a graph showing the braking distance D with respect to vehicle speed V.

[0008] (First Embodiment) Figure 1A is a block diagram showing the configuration of a vehicle headlight system according to the first embodiment. The illustrated vehicle headlight system comprises a controller 1, a memory 2, a pair of headlights 3L and 3R, a headlight switch 4, a weather condition detection sensor 5, a vehicle speed sensor 6, a driver monitoring system (DMS) 7, and a road surface condition detection sensor 8. This vehicle headlight system illuminates the area in front of the vehicle with headlights 3L and 3R in response to operation of the headlight switch 4 installed on the vehicle. The controller 1, headlight switch 4, weather condition detection sensor 5, vehicle speed sensor 6, driver monitoring system 7, and road surface condition detection sensor 8 are connected directly or indirectly via other devices.

[0009] The controller 1 controls the illumination pattern of the headlights 3L and 3R based on at least one of the following: the operation status of the headlight switch 4, the rainfall conditions detected by the weather condition detection sensor 5, the vehicle speed detected by the vehicle speed sensor 6, the driver's status detected by the driver monitoring system 7, and the road surface conditions detected by the road surface condition detection sensor 8.

[0010] The controller 1 can be configured using a computer system that includes, for example, a processor 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, a storage device 204, an input / output unit (IF) 205, etc., as shown in Figure 1B. The program 206 stored in the storage device 204 is read and executed by the processor 201, thereby realizing the various functions of the controller 1 described later.

[0011] Memory 2 is connected to controller 1 and stores data necessary for arithmetic processing in controller 1. Memory 2 uses non-volatile memory, which retains stored data even after the power is turned off. Details of the data stored in memory 2 will be described later.

[0012] The headlights 3L and 3R are mounted at predetermined positions on the left and right sides of the front of the vehicle and operate in response to control signals provided by the controller 1 to project light in a desired pattern toward the front of the vehicle. Each headlight 3L and 3R is equipped with an ADB unit 31 and a low beam unit 32, respectively.

[0013] The ADB unit 31 is configured to emit a normal high beam within the illumination range of the high beam (driving light), and also to emit light using a light distribution pattern in which the light illumination range and dimming range can be freely set. In other words, the ADB unit 31 is configured to emit a variable light distribution beam. The low beam unit 32 is configured to emit a low beam (passing light).

[0014] The headlight switch 4 is located in the driver's seat of the vehicle, close to the steering wheel, and is operated by the driver to activate the headlights.

[0015] The weather condition detection sensor 5 is a sensor for detecting weather conditions such as the presence or absence of raindrops around the vehicle, the diameter of raindrops (size of raindrops), and the amount of rainfall, and is installed at an appropriate location on the vehicle. For example, a raindrop sensor can be used as the weather condition detection sensor 5. Alternatively, an optical sensor such as LiDAR (Light Detection And Ranging) may be used as the weather condition detection sensor 5 to detect the size and spread of raindrops (dissipation coefficient and backscattering coefficient) and the number of raindrops. Furthermore, a camera that images the area around the vehicle and performs image processing may be used to detect weather conditions (e.g., sunny, cloudy, rainy, snowy, foggy, number of raindrops, etc.). The weather condition detection sensor 5 may be configured to include two or more of these raindrop sensors, optical sensors, and cameras. Note that the weather condition detection sensor 5 may also be a sensor for detecting the number of raindrops. The number of raindrops may be detected by laser light, as in a distrometer, or by detecting it from camera images, etc. For example, the number of raindrops can be estimated by applying a template matching method to an image obtained by photographing raindrops attached to the vehicle's windshield with a camera. Such technology is described, for example, in the academic paper "Situational Rainfall Recognition Using In-Vehicle Camera Images for Driving Assistance" by Hiroyuki Kurihata et al. (IEICE). The paper is available at the following link: https: / / www.cs.is.i.nagoya-u.ac.jp / users / ide / res / paper / J05-kenkyukai-hkuri-1.pdf

[0016] The vehicle speed sensor 6 is a sensor for detecting the vehicle's speed and is set at an appropriate position on the vehicle.

[0017] The Driver Monitoring System (DMS) 7 detects the driver's condition by performing image processing based on images obtained by capturing the driver's face. The driver's condition can be detected as follows: for example, the direction of the face (e.g., whether or not the driver is distracted), whether or not the eyes are open or closed (e.g., whether or not the driver is drowsy), the direction of the gaze, and the position of the eyes.

[0018] The road surface condition detection sensor 8 is a sensor for detecting the road surface condition of the road on which the vehicle is traveling. The road surface condition can be detected, for example, whether it is dry or wet.

[0019] To make the functions of controller 1 easier to understand, let's explain them using functional blocks. Controller 1 includes an irradiation state setting unit (irradiation state setting function) 11, a weather state determination unit (weather state determination function) 12, a braking stop distance calculation unit (braking stop distance calculation function) 13, and a control signal generation unit (control signal generation function) 14.

[0020] The illumination state setting unit 11 sets the high beam light distribution pattern (illumination state) for each ADB unit 31 of each headlight 3L and 3R based on at least one of the following: the operation state of the headlight switch 4, the determination result by the weather condition determination unit 12, the vehicle speed output by the vehicle speed sensor 6, the driver status output by the driver monitoring system 7, and the road surface condition output by the road surface condition detection sensor 8. The illumination state setting unit 11 also sets the low beam illumination state for each low beam unit 32 of each headlight 3L and 3R.

[0021] The weather condition determination unit 12 determines the weather condition based on the detection results output by the weather condition detection sensor 5. In this embodiment, the weather condition determined by the weather condition determination unit 12 is either a state estimated to be "bad weather" or a state estimated to be "good weather". In this embodiment, "bad weather" is a state in which the formation of a light curtain is expected.

[0022] For example, the presence of raindrops can be used to determine "bad weather." Similarly, the number of raindrops in a given space can exceed a certain value. Rainfall can also exceed a certain value to determine "bad weather." Furthermore, the dissipation coefficient or backscattering coefficient can exceed a certain value to determine "bad weather." Finally, if the weather condition is rain, snow, or fog, it can be determined to be "bad weather." By using one or more of these methods, the weather condition can be determined.

[0023] The braking distance calculation unit 13 calculates the braking distance based on the vehicle speed detected by the vehicle speed sensor 6 and the coefficient of friction estimated from the road surface condition detected by the road surface condition detection sensor 8. The coefficient of friction may be estimated based on the weather condition detected by the weather condition detection sensor 5, or it may be estimated based on the detection results of both the weather condition detection sensor 5 and the road surface condition detection sensor 8.

[0024] The control signal generation unit 14 generates control signals to realize the light distribution pattern set by the irradiation state setting unit 11 and outputs them to each ADB unit 31. The control signal generation unit 14 also outputs control signals to each low beam unit 32 to irradiate with a low beam.

[0025] Figure 2A is a schematic plan view showing an example of a headlight configuration. Here, the headlights 3L and 3R are schematically shown as viewed from the front of the vehicle. In the illustrated example of headlights 3L and 3R, each ADB unit 31 is positioned relatively inward in the left-right direction of the vehicle, and each low beam unit 32 is positioned relatively outward in the left-right direction of the vehicle.

[0026] Each ADB unit 31 is capable of emitting a high beam, and is also capable of emitting a high beam (selective high beam) with a light distribution pattern that reduces (or does not emit) any range within the irradiable range of the high beam.

[0027] Each low-beam unit 32 is capable of emitting a low beam. In this embodiment, a high beam (selective high beam) HB is formed by the combined light of the light emitted by each ADB unit 31, and a low beam LB is formed by the combined light of the light emitted by each low-beam unit 32 (see Figure 3A, described later).

[0028] Figure 2B shows an example configuration of an ADB unit capable of emitting a high beam and a selective high beam. The illustrated ADB unit 31 includes a light source 60 equipped with a plurality of light-emitting elements (e.g., LEDs: Light Emitting Diodes) and a lens 61 that projects the light emitted from the light source 60. The light source 60 includes, for example, a plurality (hundreds as an example) of semiconductor light-emitting elements (LEDs, laser diodes, etc.) arranged in a matrix along two orthogonal directions.

[0029] Each light-emitting element is configured to allow individual control of its on / off state and luminous intensity (brightness). By individually controlling the on / off state and luminous intensity of each semiconductor light-emitting element in such a light source 60, a selective high beam with a light distribution pattern that includes a dimming range 63 at any position within the high beam irradiation range 62 can be generated. In this specification, "dimming" is a concept that includes not only relatively reducing the brightness but also reducing the brightness to zero (i.e., no illumination).

[0030] The configuration of the ADB unit 31 is not limited to the above configuration, as long as it can generate a selective high beam. The ADB unit 31 can also be configured using, for example, a light source capable of emitting laser light and an optical deflector such as a MEMS mirror that scans the laser light. Alternatively, the ADB unit 31 can be configured using a light source (LED, laser, etc.) and a liquid crystal element capable of partially controlling the transmittance of the light emitted from the light source. Furthermore, the ADB unit 31 can also be configured using a light source and a movable shutter configured to partially block the light emitted from the light source. In addition, in this embodiment, as will be described in detail later, it is sufficient to dim at least a portion of the range relatively above the irradiable range of the high beam, so the ADB unit 31 may be configured to include a leveling mechanism that can change the optical axis direction of the high beam vertically. The ADB unit 31 may also be configured integrally with the low beam unit 32.

[0031] Figure 3A is a diagram illustrating the illumination ranges of high beams and low beams. Here, the illumination ranges of high beams and low beams are schematically shown on a virtual screen assumed to be in the vertical direction at a predetermined position in front of the vehicle (for example, 25 m in front of the vehicle). In the figure, the horizontal line H is a line indicating the horizontal direction based on the positions of each headlight 3L and 3R, and the vertical line V is a line indicating the vertical direction based on the positions of each headlight 3L and 3R.

[0032] In the diagram, the low beam LB, shown as a dotted line, has an illumination range that extends slightly above the horizontal line H to the left of the vertical line V, and slightly below the horizontal line to the right of the vertical line V. It has a diagonal cutoff line near the vertical line V and mainly has a wide illumination range below the horizontal line H. The low beam LB has a relatively wider illumination range than the high beam HB in the left-right direction. This low beam LB mainly illuminates the road surface in a range relatively close to the vehicle (for example, about 40m in front of the vehicle).

[0033] In the diagram, the high beam HB, exemplified by the solid line, has an illumination range that is approximately symmetrical left and right across the vertical line V, and an illumination range that is approximately symmetrical up and down across the horizontal line H. The high beam HB has a relatively narrower illumination range in the left and right direction than the low beam LB. This high beam HB mainly illuminates the road surface and the space above the road surface in a range relatively far from the vehicle (for example, about 100m in front of the vehicle).

[0034] Figure 3B illustrates the dimming range provided for the high beams during adverse weather conditions. When, for example, rainfall is detected around the vehicle, the ADB unit 31 is controlled to form a dimming range HB1, which is a portion of the high beam HB illumination range above the horizontal line H, as shown in the figure. This prevents a decrease in the driver's forward visibility caused by the reflection of the high beams by raindrops, which creates a light screen in front of the vehicle. The same applies to adverse weather conditions for other reasons.

[0035] The dimming range HB1 is achieved by controlling the light intensity of some of the light-emitting elements of the light source 60 to be reduced, as described above. The same applies when using other types of ADB units 31, and the dimming range HB1 is achieved according to the principle of each type. When using an ADB unit 31 configured to have a leveling mechanism, the irradiation range of the entire high beam HB is lowered vertically by controlling the optical axis direction of the high beam HB downwards, and as a result the dimming range HB1 can be obtained.

[0036] Figure 4 is a diagram illustrating the principle of preventing the formation of a light curtain in adverse weather conditions. Figure 4 schematically shows a vehicle 100 viewed from the side. As shown in the figure, high beams HB are projected forward from each of the vehicle's headlights 3L and 3R. When a normal high beam HB is projected without forming a dimming range HB1, a range S is created where the driver's line of sight e and the high beam HB overlap. In this range S, for example, during rainfall, a light curtain is formed when a portion of the high beam HB is projected onto raindrops in the air and reflected. This reduces the driver's forward visibility.

[0037] In contrast, by forming a dimming range HB1 relatively upward within the illumination range of the high beam HB, the range S in which the driver's line of sight direction e and the high beam HB overlap can be eliminated, or the range S can be moved relatively farther away from the vehicle 100. Therefore, it becomes possible to suppress the reduction in visibility caused by the light curtain in the driver's line of sight direction e.

[0038] Furthermore, the high beam HB when the dimming range HB1 is not formed (not during bad weather) corresponds to the high beam irradiated in the "first mode," and the high beam HB when the dimming range HB1 is formed during bad weather corresponds to the high beam irradiated in the "second mode." In addition, the dimming range HB1 within the irradiation range of the high beam HB corresponds to the "first range," and the other range corresponds to the "second range."

[0039] Figure 5 is a diagram illustrating the definitions of each parameter used to explain in more detail the principle of preventing light curtain generation. Similar to Figure 4, a schematic view of the vehicle 100 from the side is shown. Let A be the height of the driver's eye position relative to the road surface (hereinafter referred to as "driver's eye height"), let B be the height of the mounting position of the ADB unit 31 relative to the road surface (hereinafter referred to as "unit height"), let C be the distance between the driver's eye position and the position of the ADB unit 31 (distance in the vehicle's longitudinal direction), and let X be the difference between the driver's eye height A and the unit height B. Also, let Y2 be the distance between the position of the eye and the point where the driver's line of sight direction e intersects with the upper end of the high beam HB (lower end of the dimming range HB1). As an example, let the driver's line of sight direction e be approximately parallel to the road surface. Y is the difference between distance Y2 and distance C. Let θ1 be the angle indicating the position of the upper end of the irradiation range of a normal high beam HB, and let θ2 be the angle indicating the position of the upper end of the irradiation range of the high beam HB (lower end of the dimming range HB1) when a dimming range HB1 is formed to suppress the formation of a light curtain due to rainfall, etc.

[0040] As an example, a preferred numerical example of the above-mentioned angle θ2 will be described assuming the size of a general SUV-type vehicle and assuming a male of average physique as a driver. For example, assume that the driver's eye height A is 1.42 m, the unit height B is 0.89 m, the distance C is 2.26 m, and the angle θ1 is 6.4°. At this time, X (= A - B) is 0.53 m, so Y is as follows. Note that the value of the "driver's eye position" referred to herein is an estimated value corresponding to a position estimated based on the assumed physique and vehicle type.

[0041] Y = X / tanθ1 = 0.53 / tan(6.4°) = 4.51 m

[0042] Accordingly, Y2 (= Y + C) is 6.78 m. That is, assuming a normal high beam HB in which the dimming range HB1 is not formed, a light curtain can occur from a position 6.78 m forward of the vehicle based on the driver's eye position (see range S).

[0043] In contrast, if, for example, the target value (target distance) of the distance Y2 to the position where the line-of-sight direction e intersects the upper end of the high beam HB is set to 40 m, Y (= Y2 - C) becomes 37.74 m, and X (= A - B) becomes 0.53 m. At this time, the angle θ2 is obtained as follows. θ2 = arctan(X / Y) = arctan(0.53 / 37.74) = 0.8°

[0044] In other words, when it rains, if the dimming range HB1 is formed such that the angle θ2 indicating the upper end of the high beam HB (the lower end of the dimming range HB1) is 0.8°, the occurrence of light curtains can be suppressed in a range from the driver's eye position to at least 40 m forward of the vehicle, and the driver's forward visibility can be improved. In other words, the dimming range HB1 is set such that at a position separated from the driver's eye position toward the front of the vehicle by the target value of the distance Y2, the vertical height A of the driver's eye position substantially matches the vertical height of the upper end of the high beam HB (or the lower end of the dimming range HB1).

[0045] It should be noted that although an SUV-type vehicle is taken as an example in the above description, by designing the controller 1 with respective parameters assumed in accordance with the vehicle type (e.g., sedan, one-box vehicle, etc.), the angle θ2 suitable for the vehicle type of each vehicle can be set.

[0046] FIG. 6 is a flowchart showing an operation procedure of the vehicular headlamp system according to the first embodiment. Regarding the respective processes shown here, the order thereof may be changed as long as no contradiction or inconsistency arises in the information processing results, and other processes not explicitly described herein may also be added.

[0047] When the headlamp switch 4 is on (step S11; YES), the irradiation state setting unit 11 of the controller 1 instructs the control signal generating unit 14 to turn on the low-beam units 32 of the respective headlamps 3L and 3R (step S12). A control signal is transmitted from the control signal generating unit 14 that has received the instruction to each low-beam unit 32, whereby a low beam is emitted from each low-beam unit 32.

[0048] On the other hand, when the headlamp switch 4 is off (step S11; NO), the irradiation state setting unit 11 controls the control signal generating unit 14 to turn off the respective headlamps 3L and 3R. In a case where the vehicle is configured such that the headlamps are automatically turned on in accordance with the illuminance of the surrounding environment or the like, the irradiation state setting unit 11 performs the control of step S12 triggered by the fact that the respective headlamps 3L and 3R have automatically shifted to a lighting state.

[0049] Based on the detection result of the weather condition detection sensor 5, when the weather in the vicinity of the vehicle is "bad weather" (step S13; YES), the irradiation state setting unit 11 sets the high-beam light distribution pattern to "upper dimming mode", which is a mode in which a dimming range is formed above the high beam (step S14). The high beam in this upper dimming mode corresponds to the high beam irradiated in the second aspect.

[0050] On the other hand, based on the detection result of the weather condition detection sensor 5, the illumination state setting unit 11 sets the high beam light distribution pattern to a "normal mode" in which no dimming range is formed above the high beam (step S14) if the weather around the vehicle is not "bad weather" (i.e., "good weather") (step S13; NO). The high beam in this normal mode corresponds to the high beam illuminated in the first embodiment.

[0051] If the headlight switch 4 is in a state that instructs the operation of the high beam (step S16; YES), the illumination state setting unit 11 instructs the control signal generation unit 14 to light up the ADB units 31 of each headlight 3L, 3R according to the light distribution pattern set in step S13 or S14 (step S17). The control signal generation unit 14 sends a control signal to each ADB unit 31, causing the high beam to be emitted from each ADB unit 31. On the other hand, if the operation of the high beam is not instructed (step S16; NO), the process returns to step S11.

[0052] Furthermore, if the vehicle is configured to automatically switch the high beams on and off depending on the vehicle in front, the illumination state setting unit 11 performs the control in step S17 when each headlight 3L, 3R switches to the state of emitting high beams.

[0053] If the high beams are turned off by operating the headlight switch 4 or by the automatic switching function (step S18; YES), the illumination state setting unit 11 controls the control signal generation unit 14 to turn off each ADB unit 31 (step S19). The control signal generation unit 14 receives the instruction and sends a control signal to each ADB unit 31, causing each ADB unit 31 to turn off. Then, the process returns to step S11. Also, if the high beams are not turned off (step S18; NO), the process returns to step S11.

[0054] According to the first embodiment described above, it is possible to eliminate or move the light screen that may appear in the driver's line of sight during bad weather such as rain, or to move it further away from the vehicle. As a result, the effect of the light screen can be reduced and the forward visibility perceived by the driver can be improved.

[0055] (Second Embodiment) In the first embodiment described above, the values ​​of each parameter, such as the driver's eye height (estimated height) A and the unit height B, were set in advance according to the vehicle type. However, the parameters set according to the vehicle type may be stored in memory 2 as multiple sets of data, and one set of data corresponding to the vehicle type on which the vehicle headlight system is installed may be read and used during control. The embodiment in this case will be described below. Note that the configuration of the vehicle headlight system is the same as in the first embodiment described above, so the explanation will be omitted here.

[0056] Figure 7 shows an example of multiple sets of data that are set according to the vehicle type and stored in memory 2. For each vehicle type, data is prepared for the following parameter values: the driver's eye height (estimated height) A, the unit height B, and the distance C between the driver's eye position and the position of the ADB unit 31. A target value Y2, the distance to the point where the driver's line of sight e intersects with the upper edge of the high beam HB, is also prepared. For example, for vehicle type 1, which is a sedan, the corresponding data set is set as A = 1.11m, B = 0.65m, C = 2.34m, and Y2 = 40m, and is stored in memory 2. Similarly, data sets are set for other vehicle types 2, 3, ... and stored in memory 2. In addition, data indicating which vehicle type the vehicle equipped with the vehicle headlight system is is also stored in memory 2 beforehand.

[0057] Under the conditions of vehicle type 1, the light curtain may be generated from 6.44 m in front of the driver's eye position. For example, vehicle type 2 is an SUV type vehicle as exemplified in the first embodiment described above, and as described above, the light curtain may be generated from 6.78 m in front of the driver's eye position. In other words, the position and range of light curtain generation may differ depending on the vehicle type.

[0058] Figure 8 is a flowchart showing the operation procedure of the vehicle headlight system according to the second embodiment. Note that the order of the processes shown here can be changed as long as it does not result in inconsistencies or contradictions in the information processing results, and other processes not explicitly shown here can also be added.

[0059] When the vehicle starts, such as when the ignition switch or start switch is turned on, the illumination state setting unit 11 of the controller 1 reads a set of data from the memory 2 corresponding to the vehicle model on which the vehicle headlight system is installed (step S21). For example, if the vehicle model on which the vehicle headlight system is installed is model 1, the set of data corresponding to model 1 is read.

[0060] The illumination state setting unit 11 calculates the difference X between the driver's eye height A, which is identified based on the set of data read out, and the unit height B (step S22). In the case of vehicle type 1, X = 0.46 m.

[0061] The illumination state setting unit 11 calculates the angle θ2 that indicates the upper end of the high beam HB (lower end of the dimming range) based on the read-out target value of distance Y2 (step S23). For example, in vehicle model 1, the target value of distance Y2 is set to 40m, so Y (= Y2 - C) is 37.66m. Since X (= A - B) is 0.46m, the angle θ2 is obtained as follows.

[0062] θ2=atan(X / Y) =atan(0.46 / 37.66) =0.7°

[0063] After the angle θ2 is obtained, the process from step S11 onwards in the first embodiment described above is executed (see Figure 6). As a result, the high beam is illuminated in either upward dimming mode or normal mode depending on whether or not it is raining. Further details are omitted.

[0064] According to the second embodiment described above, in addition to the same effects as the first embodiment, by configuring the system to use sets of data for each vehicle model that are stored in memory 2 in advance, it becomes unnecessary to design the controller 1 individually for each vehicle model.

[0065] (Third Embodiment) In the first and second embodiments described above, control was performed using sets of data prepared for each vehicle type. However, it is also preferable to use a value for the driver's eye height A that is actually detected from the driver while they are in the vehicle. The embodiment in this case will be described below. Note that the configuration of the vehicle headlight system is the same as in the first embodiment described above, so the explanation will be omitted. In addition, the sets of data that are pre-stored in memory 2 are basically the same as in the second embodiment, but the driver's eye height (estimated height) A may be omitted.

[0066] Figure 9 is a flowchart showing the operation procedure of the vehicle headlight system according to the third embodiment. Note that the order of the processes shown here can be changed as long as it does not result in inconsistencies or contradictions in the information processing results, and other processes not explicitly shown here can also be added.

[0067] When the vehicle starts, such as when the ignition switch or start switch is turned on, the driver monitoring system (DMS) 7 is activated (step S31), and the eye height A of the driver who is actually in the vehicle is detected (step S32). For example, the eye height A is detected to be 1.35m (for example, if the driver is female).

[0068] The illumination state setting unit 11 of the controller 1 reads a set of data from the memory 2 corresponding to the vehicle model on which the vehicle headlight system is installed (step S33). For example, if the vehicle on which the vehicle headlight system is installed is vehicle model 2, the set of data corresponding to vehicle model 2 is read.

[0069] The illumination state setting unit 11 calculates the difference X between the driver's eye height A detected by the driver monitoring system 7 and the unit height B included in the data set read from the memory 2 (step S34). For example, in the case of vehicle type 2, X = 1.35 - 0.89 = 0.46 m.

[0070] The illumination state setting unit 11 calculates the angle θ2 that indicates the upper end of the high beam HB (lower end of the dimming range) based on the target value of the read-out distance Y2 (step S35). For example, in vehicle model 2, the target value of distance Y2 is set to 40m, so Y (= Y2 - C) is 37.74m. Since X (= A - B) is 0.46m, the angle θ2 is obtained as follows.

[0071] θ2=atan(X / Y) =atan(0.46 / 37.66) =0.7°

[0072] After the angle θ2 is obtained, the process from step S11 onwards in the first embodiment described above is executed (see Figure 6). Depending on the weather conditions, the high beam is illuminated in either upward dimming mode or normal mode. A detailed explanation is omitted.

[0073] According to the third embodiment described above, in addition to the same effects as the first and second embodiments, the ability to detect the actual eye height of the driver according to each driver's sitting height and posture allows for more accurate results in eliminating or moving the light curtain to a distant location. In the third embodiment, the driver monitoring system 7 may detect the eye height A in accordance with changes in the driver's posture and update the value of the angle θ2. Similarly, the driver monitoring system 7 may detect changes in the driver's gaze direction e in accordance with changes in the driver's gaze direction e and update the value of the angle θ2.

[0074] (Modified Embodiments) This disclosure is not limited to the contents of the embodiments described above, and can be modified and implemented in various ways within the scope of the gist of this disclosure. For example, although not explicitly explained in the embodiments described above, in parallel with the control that sets a dimming range for the high beams in bad weather, control may also be performed to set a dimming range within the illumination range of the high beams according to the position of the preceding vehicle or oncoming vehicle. In this case, for example, the position of the preceding vehicle can be detected using an object sensor such as LiDAR or a camera, and the illumination state setting unit 11 can set the dimming range according to that position.

[0075] In the embodiments described above, it was assumed that the dimming range would be formed by dimming the ADB units 31 of each headlight 3L and 3R to the same degree of dimming. However, the degree of dimming of each ADB unit 31 may be different. For example, if the driver's seat is located relatively to the right within the vehicle, the ADB unit 31 of the right headlight 3R, which is on the driver's seat side, can be set to not emit light into the dimming range (off or nearly off), while the ADB unit 31 of the left headlight 3L, which is opposite the driver's seat side, can be set to either dim light or not dim light into the dimming range. As a result, the dimming range for the high beam, which is composed of the combined light emitted by each ADB unit 31, can be set in the same way as in the embodiments described above. Furthermore, in this control embodiment, the amount of light emitted forward from the driver's seat side (illuminance or luminous intensity) is reduced, so the light curtain perceived by the driver can be further reduced. Therefore, the driver's forward visibility can be further improved.

[0076] In the embodiments described above, the illumination amount of the high beam was not changed regardless of whether there was a dimming range or not. However, when a dimming range is set, it is also preferable to increase the illumination amount in the illumination range other than the dimming range of the high beam. This makes it possible to further improve forward visibility while suppressing the effect of the light curtain. In this case, it is more preferable that the brightening of the high beam's illumination range is achieved by the ADB unit 31 on the opposite side of the driver's seat. For example, if the driver's seat is located on the right side, it is preferable not to brighten the illumination range of the ADB unit 31 of the right headlight 3R, which is on the driver's seat side, but to brighten the illumination range of the left headlight 3L, which is on the opposite side of the driver's seat. This is preferable because the amount of illumination from the driver's seat forward is reduced, so the light curtain perceived by the driver can be further reduced. Therefore, the driver's forward visibility can be further improved.

[0077] In the embodiments described above, the illumination amount in the area of ​​the high beam's illumination range other than the dimmed area (non-dimmed area) was not changed, but the illumination amount in the non-dimmed area may be increased. This makes it possible to further improve visibility in the area close to the vehicle while suppressing the effect of the light curtain. In this case, the ADB unit 31 of each headlight 3L and 3R may be brightened, or only the ADB unit 31 on the opposite side of the driver's seat may be brightened. Furthermore, when brightening, the non-dimmed area may be brightened with power equivalent to the power consumption reduced by providing a dimmed area. This makes it possible to keep the power consumption constant before and after providing a dimmed area.

[0078] In the embodiments described above, the dimming range was set in the event of bad weather, but the width (size) of the dimming range may be increased or decreased depending on the degree of bad weather. For example, rainfall may be used as an example of an indicator of the degree of bad weather, and the dimming range may be set so that the lower end of the dimming range (the upper end of the high beam) is lowered vertically as the amount of rainfall increases. In this case, it is preferable not to increase or decrease the width of the dimming range in accordance with the amount of rainfall when the amount of rainfall is below a certain value (for example, 5 mm per hour), and to control the lower end of the dimming range to be lowered further when the amount of rainfall exceeds a certain value, that is, to set the angle θ2 to a smaller value. Note that snowfall may be used instead of rainfall as an example of an indicator of the degree of bad weather.

[0079] Furthermore, as an example of an indicator of the degree of bad weather, the size and spread of raindrops (such as the dissipation coefficient and backscattering coefficient) that can be detected by a weather condition detection sensor 5 configured to include sensors such as LiDAR may be used, and the lower end of the light-reducing range may be adjusted up or down according to these indicators. For example, when the occurrence of fog is expected, the effect of the light curtain is greater, so it is preferable to lower the lower end of the light-reducing range even more (i.e., make the angle θ2 a smaller value) than when the occurrence of fog is not expected.

[0080] By considering the degree of adverse weather conditions in this way, it becomes possible to mitigate the effects of the reflective screen in situations where the reduction in forward visibility due to the screen is more pronounced, such as during heavy rainfall or snowfall, or when fog occurs.

[0081] In the embodiments described above, the irradiation dose within the dimming range was uniform in the vertical direction. However, the dimming rate may be set so that the irradiation dose is lower towards the top of the vertical direction and higher towards the bottom of the vertical direction. For example, the dimming range may be divided into several sections from the bottom to the top, and the dimming rate may be set to gradually increase from the section closest to the bottom. As an example, it may be divided into three sections, and the dimming rate can be set in stages, starting from the section closest to the bottom of the dimming range, at 80%, 10%, and 0% (off), based on the irradiation dose without dimming.

[0082] In the embodiments described above, a portion of the upper part of the high beam illumination range was set as the dimming range, but dimming ranges may also be provided on both the left and right sides of the high beam illumination range.

[0083] In the embodiments described above, vehicle speed was not specifically considered when setting the dimming range, but it is preferable to lower the lower end of the dimming range vertically as the vehicle speed increases. Generally, forward visibility tends to decrease as the vehicle speed increases, so by lowering the lower end of the dimming range (i.e., making the angle θ2 smaller) as the vehicle speed increases, the effect of the light curtain can be suppressed and forward visibility can be further improved. This will be explained in more detail below.

[0084] According to the publicly available document "A Policy on Geometric Design of Highways and Streets 2018, 7th Edition," the braking distance D of a vehicle can be calculated using the following formula.

[0085] Here, V is the vehicle speed (km / h), t is the reaction time (sec), and g is the acceleration due to gravity (9.8 m / s²). 2 ), f is the coefficient of friction. The value gf, obtained by multiplying g and f, is the deceleration (m / s). 2 ) For example, if the driver's reaction time t is 1.64 sec and the deceleration gf is 3.4 m / s 2 With this definition, the braking distance D for a given vehicle speed V can be calculated as shown in the graph in Figure 10.

[0086] Therefore, by using the vehicle speed V detected by the vehicle speed sensor 6 and the friction coefficient f estimated from the road surface condition detected by the road surface condition detection sensor 8, the braking distance D can be calculated based on the above calculation formula. This calculation can be performed by the braking distance calculation unit 13. As the vehicle speed increases, the braking distance D increases, so it becomes necessary to see further away from the vehicle. In order to ensure visibility at a distance, it is necessary to reduce the effect of the light curtain. Therefore, by setting the illumination state in the illumination state setting unit 11 to lower the lower end of the dimming range vertically according to the braking distance D calculated by the braking distance calculation unit 13, forward visibility over long distances can be improved.

[0087] As for specific control methods, for example, if the calculated braking distance D is smaller than the target value of the distance Y2 (for example, 40 m) to the point where the driver's line of sight e intersects with the upper end of the high beam HB, the dimming range can be set using the target value of distance Y2, regardless of the vehicle speed, in the same manner as in each of the embodiments described above. If the braking distance D exceeds the target value, the dimming range can be set using the braking distance D calculated according to the vehicle speed as a new target value.

[0088] Another control method involves setting the dimming range by using the braking distance D calculated according to the vehicle speed as a new target value for any vehicle speed.

[0089] Furthermore, in any of the control embodiments described above, it is also preferable to set the dimming range according to the braking distance D when the vehicle speed exceeds a first reference value (e.g., 30 km / h). Furthermore, in any of the control embodiments described above, it is also preferable to increase the illumination range (non-dimming range) of the high beam when the vehicle speed exceeds a second reference value greater than the first reference value (e.g., 60 km / h).

[0090] Furthermore, in the embodiments described above, the high beam dimming range was set using the driver's eye position (estimated or actual position) as the reference position, but the reference position is not limited to this. For example, the mounting position of a camera installed to capture images of the area in front of the vehicle may be used as the reference position. Similarly, the mounting position of a sensor installed to detect objects in front of the vehicle may be used as the reference position. This reduces the influence of the light curtain on the shooting range in front of the vehicle from the mounting position of the camera, etc. Therefore, if a camera is used, clearer images can be captured, and if a sensor is used, detection accuracy can be improved.

[0091] This disclosure has the following features: (Note 1) A headlight system for a vehicle comprising: a headlight installed on a vehicle and configured to illuminate at least a high beam in front of the vehicle; a controller connected to the headlight; and a weather condition detection sensor installed on the vehicle and connected to the controller, wherein the controller controls the headlight so that the high beam is illuminated in a first mode when it is not estimated to be bad weather, and controls the headlight so that the high beam is illuminated in a second mode when it is estimated to be bad weather, in which the amount of light irradiated to a first range, which is a relatively upper part of the illumination range of the high beam in the first mode, is relatively lower than that of a second range, which is the part other than the first range. (Note 2) The vehicle headlight system according to Note 1, wherein when the controller controls the headlight in the second embodiment, the controller sets the first range at a position separated by a target distance in front of the vehicle from a reference position set in relation to the vehicle, such that the vertical height of the reference position and the vertical height of the lower end of the first range substantially coincide. (Note 3) The vehicle headlight system according to Note 1, wherein when the controller controls the headlight in the second embodiment, the controller sets the first range at a position separated by a target distance in front of the vehicle from a reference position set in relation to the vehicle, such that the vertical height of the reference position and the vertical height of the upper end of the second range substantially coincide. (Note 4) The vehicle headlight system according to Note 2 or 3, wherein the vertical height of the reference position is determined at a position separated by a target distance from the reference position in front of the vehicle, substantially parallel to the road surface. (Note 5) The reference position is the position of the driver's eyes of the vehicle, as described in any of Notes 2 to 4 for the vehicle headlight system. (Note 6) The reference position is the position of a camera installed on the vehicle or the position of a sensor attached to the vehicle, as described in any of Notes 2 to 4 for the vehicle headlight system.(Note 7) A headlight system for a vehicle according to Note 5, further comprising a memory connected to the controller, wherein the memory stores data of multiple estimated eye positions set according to each of a plurality of vehicle types in the vehicle, and the controller uses the estimated eye position corresponding to the vehicle type in question as the reference position. (Note 8) A headlight system for a vehicle according to any one of Notes 1 to 7, wherein the controller sets the first range such that the height of the lower end of the first range decreases as the vehicle speed increases. (Note 9) A headlight system for a vehicle according to Note 2 or 3, wherein the controller calculates the braking distance of the vehicle using the vehicle speed and sets the first range using the braking distance as the target distance. (Note 10) The vehicle headlight system according to Note 2 or 3, wherein the controller calculates the braking distance of the vehicle using the vehicle speed, and if the braking distance exceeds the target distance, sets the first range using the braking distance as a new target distance. (Note 11) The vehicle headlight system according to Note 9 or 10, wherein the controller sets the first range using the braking distance when the vehicle speed exceeds a first reference value. (Note 12) The vehicle headlight system according to Note 11, wherein the controller controls the headlights to relatively increase the amount of light irradiated into the second range when the vehicle speed exceeds a second reference value which is greater than the first reference value, compared to when the vehicle speed is less than or equal to the second reference value.

[0092] 1: Controller, 2: Memory, 3L, 3R: Headlights, 4: Headlight switch, 5: Weather condition detection sensor, 6: Vehicle speed sensor, 7: Driver monitoring system (DMS), 8: Road surface condition detection sensor, 11: Illumination state setting unit, 12: Weather condition determination unit, 13: Braking distance calculation unit, 14: Control signal generation unit, 31: ADB unit, 32: Low beam unit

Claims

1. A vehicle headlight system comprising: a headlight installed on a vehicle and configured to illuminate at least a high beam in front of the vehicle; a controller connected to the headlight; and a weather condition detection sensor installed on the vehicle and connected to the controller, wherein the controller controls the headlight to illuminate the high beam in a first mode based on the output of the weather condition detection sensor when it is not estimated to be bad weather, and controls the headlight to illuminate the high beam in a second mode when it is estimated to be bad weather, wherein the amount of light irradiated to a first range, which is a relatively upper part of the illumination range of the high beam in the first mode, is relatively lower than that to a second range, which is the part other than the first range.

2. The vehicle headlight system according to claim 1, wherein the controller, when controlling the headlight in the second embodiment, sets the first range at a position separated by a target distance in front of the vehicle from a reference position set in relation to the vehicle, such that the vertical height of the reference position and the vertical height of the lower end of the first range substantially coincide.

3. The vehicle headlight system according to claim 1, wherein the controller, when controlling the headlight in the second embodiment, sets the first range at a position separated by a target distance in front of the vehicle from a reference position set in relation to the vehicle, such that the vertical height of the reference position and the vertical height of the upper end of the second range substantially coincide.

4. The vehicle headlight system according to claim 2, wherein the vertical height of the reference position is determined at a position located approximately parallel to the road surface and separated by the target distance from the reference position toward the front of the vehicle.

5. The vehicle headlight system according to claim 2, wherein the reference position is the position of the driver's eyes of the vehicle.

6. The vehicle headlight system according to claim 2, wherein the reference position is the position of a camera installed on the vehicle or the position of a sensor attached to the vehicle.

7. A headlight system for a vehicle according to claim 5, further comprising: a memory connected to the controller, the memory storing data of a plurality of estimated eye positions set according to each of a plurality of vehicle types in the vehicle, and the controller using the estimated eye position corresponding to the vehicle type in question as the reference position.

8. The vehicle headlight system according to claim 1, wherein the controller sets the first range such that the vertical height of the lower end of the first range decreases as the vehicle speed increases.

9. The vehicle headlight system according to claim 2, wherein the controller calculates the braking distance of the vehicle using the vehicle speed and sets the first range using the braking distance as the target distance.

10. The vehicle headlight system according to claim 2, wherein the controller calculates the braking distance of the vehicle using the vehicle speed, and if the braking distance exceeds the target distance, sets the first range using the braking distance as a new target distance.

11. The vehicle headlight system according to claim 9 or 10, wherein the controller sets the first range using the braking distance when the vehicle speed exceeds a first reference value.

12. The headlight system for a vehicle according to claim 11, wherein the controller controls the headlight to relatively increase the amount of light irradiated into the second range compared to when the vehicle speed is less than or equal to the second reference value, when the vehicle speed exceeds a second reference value which is greater than the first reference value.

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