Light distribution control device and light distribution control method

Abstract

A light distribution control device (10) is provided with a vibration state determination unit (11) and a light distribution control unit (12). The vibration state determination unit (11) determines whether or not the vibration state of an own vehicle satisfies a predetermined condition. When the above condition is satisfied during the execution of forward irradiation by a low beam of the own vehicle, the light distribution control unit (12) controls a lighting device (30) of the own vehicle to execute a cutoff line reduction irradiation for irradiating the upper side of a cutoff line of the low beam with reduced light darker than the low beam.

Description

Light distribution control device and light distribution control method

[0001] The present disclosure relates to a technology for controlling light distribution of vehicle headlights.

[0002] Generally, when passing an oncoming vehicle, drivers switch from high beams to low beams. Low beams are also called "passing headlights" or "passing lights." Low beams cut off the light that shines upward to protect the driver of the oncoming vehicle from being dazzled, and the boundary where this light is cut off is called the "cut-off line" (hereinafter sometimes abbreviated as "CL").

[0003] For example, if the road surface is uneven, the cutoff line vibrates up and down as the vehicle vibrates, causing dazzle to drivers of oncoming vehicles. Furthermore, the low beam range vibrates from the driver's perspective, causing discomfort to the driver.

[0004] The following Patent Document 1 discloses a technology that prevents the occurrence of the above-mentioned problem by providing a reflector in the headlight that provides illumination above the cutoff line and reducing the difference in brightness above and below the cutoff line.

[0005] Japanese Patent Application Laid-Open No. 2003-288805

[0006] In the technology of Patent Document 1, the reflector always illuminates above the cutoff line, which may cause dazzle to drivers of oncoming vehicles regardless of the state of vibration of the vehicle.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a light distribution control device that can reduce the difference in brightness above and below the cutoff line depending on the vibration state of the vehicle.

[0008] The light distribution control device according to the present disclosure includes a vibration state determination unit that determines whether the vibration state of the vehicle satisfies a predetermined condition, and a light distribution control unit that, when the condition is satisfied while the vehicle is performing forward illumination with its low beam, controls the vehicle's lighting device to perform cutoff line mitigation illumination, irradiating mitigation light that is darker than the low beam above the low beam cutoff line.

[0009] According to the light distribution control device of the present disclosure, it is possible to reduce the difference in brightness above and below the cutoff line depending on the vibration state of the vehicle.

[0010] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0011] 1 is a diagram showing a typical setting example of a low beam cutoff line. FIG. 1 is a diagram showing an example of a low beam illuminance distribution 10 m ahead of a vehicle. FIG. 2 is a diagram showing an example of a low beam illuminance distribution 10 m ahead of a vehicle. FIG. 3 is a diagram showing definitions of the X, Y, and Z directions. FIG. 4 is a diagram showing an example of a low beam irradiation pattern on a wall surface 10 m ahead of a vehicle. FIG. 5 is a diagram showing an example of a low beam irradiation pattern on a wall surface 10 m ahead of a vehicle. FIG. 6 is a diagram showing fluctuations in the low beam illuminance distribution 10 m ahead of a vehicle when the vehicle vibrates. FIG. 7 is a diagram showing fluctuations in the low beam illuminance distribution on a wall surface 10 m ahead of a vehicle when the vehicle vibrates. FIG. 8 is a diagram showing fluctuations in the low beam irradiation range on a road surface when the vehicle vibrates. FIG. 9 is a diagram showing time-series changes in the low beam illuminance at headlight height when the vehicle vibrates. FIG. 10 is a diagram showing a configuration of a light control system according to a first embodiment. FIG. 11 is a diagram showing an example of the illuminance distribution of low beam and CL mitigation light 10 m ahead of a vehicle performing CL mitigation illumination. FIG. 12 is a diagram showing an example of an irradiation pattern of low beam and CL mitigation light on a wall surface 10 m ahead of a vehicle performing CL mitigation illumination. 1 is a diagram showing an example of an irradiation pattern of low beams and CL mitigating light on a wall surface 10 m ahead of a vehicle performing CL mitigation illumination. 2 is a diagram showing an example of an irradiation pattern of low beams and CL mitigating light on a wall surface 10 m ahead of a vehicle performing CL mitigation illumination. 3 is a diagram showing a variation in the illuminance distribution of low beams and CL mitigating light 10 m ahead of a vehicle when a vehicle performing CL mitigation illumination vibrates. 4 is a diagram showing a variation in the illuminance distribution of low beams and CL mitigating light on a wall surface 10 m ahead of a vehicle when a vehicle performing CL mitigation illumination vibrates. 5 is a diagram showing a variation in the irradiation range of low beams on a road surface when a vehicle performing CL mitigation illumination vibrates. 6 is a diagram showing a time-series change in the illuminance of low beams and CL mitigating light at headlight height when a vehicle performing CL mitigation illumination vibrates. 7 is a flowchart showing the operation of a light distribution control device according to a first embodiment. 8 is a diagram showing an example of an irradiation pattern of low beams and CL mitigating light when the amplitude of vibration of the host vehicle is small. 9 is a diagram showing an example of an irradiation pattern of low beams and CL mitigating light when the amplitude of vibration of the host vehicle is large. 10 is a diagram showing an example of the relationship between the amplitude of vibration of the host vehicle and the set CL mitigation illumination width.FIG. 1 is a diagram for explaining a preferred size of a CL relaxation irradiation width. FIG. 2 is a diagram for explaining a modified example 2 of embodiment 1. FIG. 3 is a diagram for explaining a modified example 2 of embodiment 1. FIG. 4 is a diagram for explaining a modified example 2 of embodiment 1. FIG. 5 is a diagram for explaining a modified example 3 of embodiment 1. FIG. 6 is a diagram for explaining a configuration of a light control system according to embodiment 2. FIG. 7 is a diagram for explaining a modified example 1 of embodiment 2. FIG. 8 is a diagram for explaining a configuration of a light control system according to embodiment 3. FIG. 9 is a flowchart showing the operation of a light distribution control device according to embodiment 3. FIG. 10 is a diagram for explaining a configuration of a light control system according to modified example 2 of embodiment 3. FIG. 11 is a flowchart showing the operation of a light distribution control device according to modified example 2 of embodiment 3. FIG. 12 is a diagram for explaining a configuration of a light control system according to modified example 3 of embodiment 3. FIG. 13 is a diagram for explaining a hardware configuration example of a light distribution control device.

[0012] <Base Technology> First, the base technology of the present disclosure will be described.

[0013] FIG. 1 is a diagram showing a typical setting example of the low beam cutoff line. In this setting example, the height L0 of the low beam cutoff line 10 meters ahead of the vehicle is set to be lower by Ldif than the headlight height L1. Here, the headlight height L1 is 100 cm, and Ldif is 10 cm. In other words, the cutoff line height L0 10 meters ahead of the vehicle is adjusted to 90 cm. When Ldif is set to 10 cm, the angle θunder at which the upper end of the low beam points downward is adjusted to approximately 0.6 degrees.

[0014] Figure 2 shows an example of the illumination distribution of low beams 10 m ahead of the vehicle. Illuminance is set to zero at positions higher than the cutoff line height L0 (90 cm). Figure 3 shows a diagram in which the vertical axis of Figure 2 is changed to "downward angle." Illuminance is set to zero in areas where the downward angle is smaller than the angle θunder (approximately 0.6 degrees) at which the upper end of the low beam points downward.

[0015] As shown in FIG. 4, the forward direction of the vehicle is defined as the X direction, the lateral direction of the vehicle as the Y direction, and the height direction as the Z direction.

[0016] Figure 5 shows the low beam illumination pattern on a wall 10 m ahead of the vehicle. As shown in Figure 6, the cut-off line may be designed so that the low beam illumination on the lane of oncoming vehicles is directed downward.

[0017] In this underlying technology, when a vehicle emitting low beams vibrates, the illuminance distribution of the low beams 10 m ahead of the vehicle fluctuates as shown in Figure 7, and the illuminance distribution of the low beams on a wall 10 m ahead of the vehicle fluctuates as shown in Figure 8. When viewed from above, the range of low beam illumination on the road surface fluctuates as shown in Figure 9.

[0018] For example, if the height of a vehicle's headlights is 1 m and the wheelbase, which is the distance between the front and rear wheels of the vehicle, is 2.5 m, if the front wheels of the vehicle are 5 cm higher than the rear wheels, the vehicle will be angled upward by approximately 1.1 degrees, and the cutoff line will be 20 cm higher 10 m ahead. When the cutoff line is angled upward, the cutoff line height Lup will be 110 cm, causing dazzle to drivers of oncoming vehicles. Conversely, if the front wheels are 5 cm lower than the rear wheels, the vehicle will be angled downward by approximately 1.1 degrees, and the cutoff line will be 20 cm lower 10 m ahead. When the cutoff line is angled downward, the cutoff line height Ldown will be 70 cm.

[0019] Figure 10 shows the time series change in low beam illuminance at headlight height L1 (100 cm) when a vehicle illuminating low beams vibrates. While actual vehicle vibrations exhibit complex patterns, the low beam illuminance waveform shown in Figure 10 was calculated by assuming the vehicle vibration waveform to be a sine wave. When a vehicle illuminating low beams vibrates, the low beam illuminance at headlight height L1 changes discontinuously, as shown in Figure 10, creating a situation similar to headlights flashing rapidly. This can cause discomfort to the driver of the vehicle and drivers of oncoming vehicles.

[0020] 11 is a diagram showing the configuration of a light control system 1 according to embodiment 1. In this embodiment, it is assumed that the light control system 1 is mounted on a vehicle, and the vehicle on which the light control system 1 is mounted is referred to as the "host vehicle."

[0021] As shown in FIG. 11 , the light control system 1 includes a light distribution control device 10 , a vibration sensor 21 , and a light device 30 .

[0022] The vibration sensor 21 is a detector that detects vibrations of the body of the host vehicle. The vibration sensor 21 can be configured with, for example, a vehicle height sensor, an acceleration sensor, a rate sensor, a spirit level, an on-board camera, etc. The vibration sensor 21 may also detect the pitch angle, yaw angle, and roll angle of the host vehicle and detect the vibration of the host vehicle from fluctuations in these angles. The vibration sensor 21 provides the light distribution control device 10 with vibration information that indicates the state of vibration of the host vehicle (for example, vibration amplitude, frequency, etc.).

[0023] The lighting device 30 is a lamp that illuminates the area ahead of the vehicle and includes a headlight 31 and a sublight 32. The headlight 31 is the main lamp that illuminates the area ahead of the vehicle and is switchable between high beam and low beam (passing light). The headlight 31 has a light distribution that is set so as not to illuminate anything above the cut-off line when illuminating the area ahead with low beam.

[0024] When the headlights 31 perform forward illumination with low beams, the sublights 32 perform cutoff line mitigation illumination (CL mitigation illumination) by irradiating the upper side of the cutoff line with light darker than the low beams to mitigate the difference in brightness above and below the cutoff line. Hereinafter, the light irradiated by the headlights 31 for CL mitigation illumination will be referred to as "CL mitigation light."

[0025] 11 shows the sub-light 32 as a separate device from the headlight 31, the headlight 31 and the sub-light 32 may be an integrated device. In other words, the headlight 31 may have the function of the sub-light 32.

[0026] The light distribution control device 10 performs CL mitigation illumination by controlling the sublights 32. The light distribution control device 10 includes a vibration state determination unit 11 and a light distribution control unit 12.

[0027] The vibration state determination unit 11 acquires vibration information of the vehicle from the vibration sensor 21, and determines whether the vibration state of the vehicle satisfies a predetermined condition based on the vibration information. This condition is a condition for determining whether to perform CL mitigation illumination, and hereinafter, this condition is referred to as a "CL mitigation illumination implementation condition."

[0028] When the CL mitigation illumination implementation conditions are met while the vehicle is illuminating the front with low beams, the light distribution control unit 12 controls the lighting device 30 to implement CL mitigation illumination, which irradiates CL mitigation light that is darker than the low beams above the low beam cutoff line.

[0029] Here, a specific example of CL mitigation illumination will be described. Fig. 12 shows an example of the illumination distribution of low beam and CL mitigation light 10 m ahead of a vehicle implementing CL mitigation illumination. CL mitigation illumination creates an area with illuminance lower than the illuminance of low beam (LL) at a position higher than the cutoff line height L0 (90 cm). In this embodiment, the CL mitigation light has a luminous intensity distribution in which the luminous intensity (corresponding to the illuminance in Fig. 12) decreases with increasing distance from the cutoff line.

[0030] It is preferable that the illuminance distribution of CL mitigation irradiation has lower illuminance at positions farther from the cutoff line than at positions closer to the cutoff line, as in the example of Figure 12. The illuminance distribution of CL mitigation irradiation shown in Figure 12 has a linear dimming characteristic with respect to height, but any characteristic may be used, such as a curved dimming characteristic or a stepwise dimming characteristic. Furthermore, the low beam irradiation range and the CL mitigation irradiation range may overlap, or there may be a slight gap between them.

[0031] Fig. 13 shows the illumination patterns of low beams and CL mitigation light on a wall 10 m ahead of a vehicle using CL mitigation illumination. The cutoff line may be designed so that the low beam illumination toward the oncoming vehicle lane is directed downward, as shown in Fig. 14. In this case, the illumination pattern of CL mitigation illumination may correspond to the shape of the cutoff line, as shown in Fig. 15.

[0032] When a vehicle using CL mitigation illumination vibrates, the illuminance distribution of the low beam and CL mitigation light 10 m ahead of the vehicle fluctuates as shown in Fig. 16, and the illuminance distribution of the low beam and CL mitigation light on a wall surface 10 m ahead of the vehicle fluctuates as shown in Fig. 17. When viewed from above, the illumination range of the low beam and CL mitigation light on the road surface fluctuates as shown in Fig. 18.

[0033] Figure 19 shows the time-series changes in the illuminance of low beam and CL mitigation light at headlight height L1 (100 cm) when a vehicle using CL mitigation illumination vibrates. When a vehicle using CL mitigation illumination vibrates, the illuminance of low beam and CL mitigation light at headlight height L1 changes continuously, and the change in illuminance is more gradual than in the case of the prerequisite technology, i.e., low beam only (Figure 10). This reduces discomfort to the driver of the vehicle and drivers of oncoming vehicles. The waveforms of the time-series changes in the illuminance of low beam and CL mitigation light shown in Figure 19 are merely examples, and this waveform depends on the luminous intensity distribution of CL mitigation illumination.

[0034] Various conditions for implementing CL mitigation illumination may be considered. For example, the condition for implementing CL mitigation illumination may be that the amplitude of vibration of the host vehicle is equal to or greater than a predetermined threshold. As described above, if the wheelbase of a vehicle is 2.5 m, when the difference in height between the front and rear wheels of the vehicle is 5 cm, the cutoff line 10 m ahead will be shifted by 20 cm. Therefore, if the threshold is 5 cm, CL mitigation illumination is implemented when the cutoff line 10 m ahead fluctuates by an amplitude of 20 cm or more. If the threshold is 2.5 cm, CL mitigation illumination is implemented when the cutoff line 10 m ahead fluctuates by an amplitude of 10 cm or more. The amplitude of vibration of the host vehicle may be defined as the maximum value, average value, median value, etc. of the amplitude during which the host vehicle travels a certain distance (e.g., 20 m) or a certain time period (e.g., 5 seconds).

[0035] For example, the CL mitigation illumination implementation condition may be that the pitch angle of the host vehicle is equal to or greater than a predetermined threshold value. As described above, if the vehicle wheelbase is 2.5 m, when the difference in height between the front and rear wheels of the vehicle is 5 cm, the vehicle pitch angle is 1.1 degrees. Therefore, if the threshold is set to 1.1 degrees, CL mitigation illumination is implemented when the cutoff line 10 m ahead fluctuates with an amplitude of 20 cm or more. If the threshold is set to 0.6 degrees, CL mitigation illumination is implemented when the cutoff line 10 m ahead fluctuates with an amplitude of 10 cm or more.

[0036] Furthermore, for example, the CL mitigation irradiation implementation condition may be that the amplitude of the vibration of the vehicle is equal to or greater than a predetermined threshold (e.g., 1 cm) and the frequency of the vibration is equal to or greater than a predetermined threshold (e.g., 1 Hz). Even if the amplitude of the vibration of the vehicle is small, if the vehicle vibrates actively, it can cause discomfort to the driver of the vehicle and the driver of an oncoming vehicle, so it is effective to consider both the amplitude and frequency of the vibration.

[0037] In this way, according to the light distribution control device 10 according to the first embodiment, even if the low beams vibrate due to vibration of the vehicle, CL mitigation illumination can be implemented to reduce dazzle and discomfort felt by the driver of the vehicle and the driver of an oncoming vehicle. Furthermore, because CL mitigation illumination is implemented only when the vibration state of the vehicle satisfies predetermined CL mitigation illumination implementation conditions, unnecessary implementation of CL mitigation illumination is prevented, which contributes to energy conservation.

[0038] 20 is a flowchart showing the operation of the light distribution control device 10 according to embodiment 1. The operation of the light distribution control device 10 according to embodiment 1 will be described below with reference to the flowchart in FIG.

[0039] 20 starts when the headlights 31 of the vehicle perform forward illumination with low beams. When forward illumination with low beams is started, the vibration state determination unit 11 acquires vibration information of the vehicle from the vibration sensor 21 (step S101). Based on the acquired vibration information, the vibration state determination unit 11 determines whether the vibration state of the vehicle satisfies the CL mitigation illumination execution condition (step S102).

[0040] If the vibration state of the host vehicle satisfies the CL mitigation illumination implementation condition (YES in step S102), the light distribution control unit 12 determines the mode of CL mitigation illumination (step S103) and controls the lighting device 30 to implement CL mitigation illumination (step S104). Examples of the mode of CL mitigation illumination include the altitude distribution of CL mitigation illumination and its vertical width (width Lexp shown in FIGS. 12 and 13). The mode of CL mitigation illumination may be fixed, or, as will be described later, the mode of CL mitigation illumination may change depending on the vibration state of the host vehicle.

[0041] If the vibration state of the host vehicle does not satisfy the CL mitigation irradiation execution condition (NO in step S102), steps S103 and S104 are skipped.

[0042] Thereafter, the light distribution control unit 12 checks whether forward illumination with low beam has ended (step S105). For example, forward illumination with low beam ends when the driver of the vehicle turns off the headlights 31, when the operation of the headlights 31 is switched from low beam to high beam, or when the ignition of the vehicle is turned off. If forward illumination with low beam has ended (YES in step S105), the flow in Fig. 20 ends. If forward illumination with low beam continues (NO in step S105), the process returns to step S101, and the above operations are repeatedly executed.

[0043] [Variation 1] The light distribution control unit 12 may change the mode of CL mitigation illumination depending on the state of vibration of the host vehicle. For example, the vibration state determination unit 11 may analyze the amplitude of the vibration of the host vehicle, and the light distribution control unit 12 may expand the range of CL mitigation illumination upward when the amplitude of the vibration is large compared to when the amplitude is small. Here, as an index of the upward width of CL mitigation illumination, the distance from the height L0 of the cutoff line 10 m ahead of the host vehicle to the upper end of the CL mitigation illumination range (width Lexp shown in FIGS. 12 and 13 ) is defined as the "CL mitigation illumination width."

[0044] For example, when the amplitude of vibration of the host vehicle is small, the CL mitigation illumination width Lexp can be reduced as shown in Fig. 21, and when the amplitude of vibration of the host vehicle is large, the CL mitigation illumination width Lexp can be increased as shown in Fig. 22. When the amplitude of vibration is large, increasing the CL mitigation illumination width can enhance the effect of suppressing dazzle and discomfort felt by the driver of the host vehicle and the driver of an oncoming vehicle, and when the amplitude of vibration is small, decreasing the CL mitigation illumination width can suppress unnecessary CL mitigation illumination.

[0045] Fig. 23 is a diagram showing an example of the relationship between the amplitude of vibration of the vehicle and the set CL mitigation illumination width. In Fig. 23, CL mitigation illumination is performed when the vibration amplitude is 2.5 cm or more, and the CL mitigation illumination width is set to match the amplitude of the cutoff line. That is, when the vibration amplitude is 2.5 cm, the CL mitigation illumination width is set to 10 cm, and when the vibration amplitude is 5 cm, the CL mitigation illumination width is set to 20 cm. In addition, an upper limit is set for the CL mitigation illumination width.

[0046] The CL mitigation illumination width is preferably equal to twice the amplitude of the cutoff line (i.e., the difference between the height of the cutoff line when the vehicle is vibrating upward and the height of the cutoff line when the vehicle is vibrating downward). In this case, as shown in FIG. 24 , the height of the cutoff line when the vehicle is vibrating upward and the height of the upper end of the CL mitigation illumination range when the vehicle is vibrating downward are the same. The area higher than the height of the cutoff line when the vehicle is vibrating upward is a range where low beam illumination is essentially unnecessary, so unnecessary CL mitigation illumination is suppressed. Conversely, the area lower than the height of the cutoff line when the vehicle is vibrating upward is a range where low beam illumination is essentially necessary, so by performing CL mitigation illumination over the entire area, the effect of suppressing dazzle and discomfort to the driver of the vehicle and the driver of an oncoming vehicle can be enhanced. However, if the amplitude of the vehicle's vibration itself fluctuates, it is preferable to set the CL mitigation illumination width to a larger value in anticipation of the amount of fluctuation.

[0047] [Variation 2] The light distribution control unit 12 may change the mode of CL mitigation illumination in accordance with the frequency of vibration of the vehicle. Note that the frequency of vibration may be defined in any way, such as the frequency having the maximum power in the analysis results obtained by FFT (Fast Fourier Transform) or the reciprocal of the interval between waveforms having a certain amplitude or more within a certain time period.

[0048] The light distribution control unit 12 may make the gradient of the luminous intensity distribution of the CL mitigating light near the cutoff line gentler as the frequency of the vibration of the vehicle increases. That is, when the frequency of the vibration is high, the gradient of the luminous intensity distribution of the CL mitigating light near the cutoff line may be made gentler, as shown in Fig. 25 , and when the frequency of the vibration is high, the gradient of the luminous intensity distribution of the CL mitigating light near the cutoff line may be made steeper, as shown in Fig. 26 . Fig. 27 is a diagram showing an example of the relationship between the frequency of the vibration and the half-width of the luminous intensity of the CL mitigating radiation (Lhalf shown in Figs. 25 and 26 ).

[0049] By making the gradient of the luminous intensity distribution of the CL mitigating light near the cutoff line gentle when the vibration frequency is high, it is possible to enhance the effect of suppressing the dazzle and discomfort felt by the driver of the vehicle and the driver of an oncoming vehicle.When the vibration frequency is low, it is considered that the dazzle and discomfort felt by the vibration of the cutoff line to the driver of the vehicle and the driver of an oncoming vehicle is small, so by making the gradient of the luminous intensity distribution of the CL mitigating light near the cutoff line steep, it is possible to reduce the CL mitigating irradiation light and achieve an energy-saving effect.

[0050] [Modification 3] The above-described modification 1 and modification 2 may be combined. That is, the light distribution control unit 12 may control both the CL mitigation irradiation width (Eexp) and the half-value width (Lhalf) of the luminous intensity of the CL mitigation irradiation in accordance with the amplitude and frequency of the vibration of the host vehicle.

[0051] [Variation 4] In the first embodiment, the width of the CL mitigation illumination range is adjusted to match the width of the low beam. That is, in the first embodiment, the CL mitigation illumination range is limited to the area above the cutoff line, but as shown in Fig. 28, the CL mitigation illumination may also be applied to the lateral outside of the low beam illumination range. This makes it possible to reduce the dazzle and discomfort felt by the driver of the vehicle and the driver of an oncoming vehicle even when the vehicle vibrates in the rolling or yawing direction.

[0052] [Modification 5] The light distribution control unit 12 may change the mode of CL mitigation illumination depending on the traveling speed of the vehicle. Information on the traveling speed of the vehicle can be obtained from, for example, an in-vehicle LAN.

[0053] For example, the light distribution control unit 12 may widen the CL mitigation illumination width in the horizontal direction as the vehicle's traveling speed decreases. When the vehicle's traveling speed is low, the driver's field of vision is wide, so by widening the CL mitigation illumination range in the horizontal direction, the lighting conditions in the driver's field of vision can be made closer to those in daytime, thereby reducing the discomfort felt by the driver.

[0054] [Variation 6] The light distribution control unit 12 may change the mode of CL mitigation illumination depending on whether or not there is an oncoming vehicle. The presence or absence of an oncoming vehicle can be detected using a surrounding detection device (e.g., a camera or image processing device) of the vehicle.

[0055] When an oncoming vehicle is detected ahead of the host vehicle, the light distribution control unit 12 may reduce the luminance of the CL mitigation light. Reducing the luminance of the CL mitigation light includes setting the luminance of the CL mitigation light to zero, i.e., stopping CL mitigation illumination. This enhances the anti-glare effect for the driver of the oncoming vehicle. The luminance of the CL mitigation illumination in the area on the oncoming vehicle's lane may also be reduced partially.

[0056] Furthermore, the same effect can be obtained by the light distribution control unit 12 reducing the CL mitigation illumination width to shorten the reach distance of the CL mitigation light when an oncoming vehicle is detected ahead of the host vehicle.

[0057] <Embodiment 2> Figure 29 is a diagram showing the configuration of a light control system 1 according to embodiment 2. The configuration of light control system 1 in Figure 29 is the same as the configuration of embodiment 1 (Figure 11) except that a road surface condition detection device 22 connected to light distribution control device 10 and a color tone adjustment unit 13 provided within light distribution control device 10 are added. Also, in embodiment 2, sub-light 32 of lighting device 30 has a function of changing the color tone of the light it emits. Note that "color tone" is a concept that includes color elements such as "hue," "lightness," and "saturation."

[0058] The road surface condition detection device 22 detects the condition of the road surface by analyzing an image of the road surface ahead of the vehicle taken by a camera or the like mounted on the vehicle. In this embodiment, the road surface condition detection device 22 detects at least the color tone of the road surface ahead of the vehicle.

[0059] In response to a request from the light distribution control unit 12, the color tone adjustment unit 13 adjusts the color tone of the light for CL mitigation illumination (CL mitigation light) performed by the light distribution control unit 12 based on the color tone of the road surface ahead of the vehicle detected by the road surface condition detection device 22. For example, the color tone adjustment unit 13 sets the color tone of the CL mitigation light to an intermediate color between the color tone of the road surface ahead of the vehicle and the color tone of the light from the headlights 31.

[0060] The operation of the light distribution control device 10 according to the second embodiment is basically the same as that of the first embodiment (flow in FIG. 20 ). However, step S103 in the flow in FIG. 20 includes adjustment of the color tone of the CL mitigating light by the color tone adjustment unit 13. In addition, in step S104, the light distribution control unit 12 sets the color tone of the CL mitigating light emitted by the sublight 32 to the color tone determined by the color tone adjustment unit 13 in step S103, and then performs CL mitigating illumination.

[0061] According to the light distribution control device 10 of embodiment 2, the color tone of the CL mitigation light is adjusted according to the color tone of the road surface, thereby preventing the driver of the vehicle from feeling uncomfortable due to the CL mitigation light and preventing the driver from feeling uncomfortable due to the CL mitigation illumination.

[0062] [Variation 1] The color tone adjustment unit 13 may change the color tone of the CL mitigating light within the CL mitigating illumination range. For example, as shown in Fig. 30 , the color tone adjustment unit 13 may set the color tone of the CL mitigating light so that its conspicuousness (degree of attracting the driver's attention) decreases upward from the cutoff line side. In other words, the color tone adjustment unit 13 may adjust the distribution of the color tone of the CL mitigating light so that the CL mitigating light becomes less noticeable as it moves away from the cutoff line.

[0063] It is also known that blue light is more visible against a white background, so for example, when the vehicle is traveling on a snowy road, the color tone of the CL mitigation light may be changed in the following order from the cut-off line side: white (the color of the light from the headlights 31), blue, dark blue, and even darker blue.

[0064] It is also known that yellow light is more visible when the background is brown, so for example, when the vehicle is traveling on an unpaved road or a brick road, the color tone of the CL mitigation light may be changed in the following order from the cut-off line side: white (the color of the light from the headlights 31), yellow, dark yellow, and further dark yellow.

[0065] [Variation 2] The color tone adjustment unit 13 may add a pattern to the CL mitigating illumination by changing the color tone of a portion of the CL mitigating light. For example, the color tone adjustment unit 13 may change the roughness of the pattern of the CL mitigating illumination depending on the road surface condition detected by the light distribution control unit 12. For example, by representing the unevenness or damage of the road surface by the roughness of the pattern of the CL mitigating illumination, the driver can easily recognize the road surface condition.

[0066] <Embodiment 3> Fig. 31 is a diagram showing the configuration of a light control system 1 according to embodiment 3. The configuration of the light control system 1 in Fig. 31 is obtained by adding an operating device 24 connected to the light distribution control device 10 and a learning unit 14 provided within the light distribution control device 10 to the configuration of embodiment 1 (Fig. 11).

[0067] The operation device 24 is a switch that allows the driver to input an operation indicating his or her intention to the light distribution control device 10. The operation device 24 may be any device that allows the driver to input his or her intention, and may be, for example, a touch panel, a voice recognition device, a gesture recognition device, or the like.

[0068] The learning unit 14 learns the relationship between the vibration state of the vehicle and the necessity of CL mitigation illumination based on the vibration state of the vehicle determined by the vibration state determination unit 11 and the operation (driver's intention) input to the operation device 24. Furthermore, the learning unit 14 updates the CL mitigation illumination implementation conditions based on the learning results.

[0069] Furthermore, in this embodiment, regardless of whether the CL mitigation illumination implementation condition is satisfied, the light distribution control unit 12 can start or end CL mitigation illumination in response to the driver's operation of the operation device 24. The learning unit 14 learns the relationship between the vibration state of the host vehicle and the necessity of cutoff line mitigation illumination, based on the vibration state of the host vehicle when the driver performs the operation to start or end CL mitigation illumination.

[0070] Fig. 32 is a flowchart showing the operation of light distribution control device 10 according to embodiment 3. The operation of light distribution control device 10 according to embodiment 3 will be described below with reference to the flowchart in Fig. 32. Note that steps S101 to S105 in Fig. 32 are basically the same as steps S101 to S105 in Fig. 20.

[0071] The flow of Fig. 32 starts when the headlights 31 of the vehicle start illuminating the road ahead with low beams. When low beam illumination starts, the vibration state determination unit 11 acquires vibration information about the vehicle from the vibration sensor 21 (step S101). Based on the acquired vibration information, the vibration state determination unit 11 determines whether the vibration state of the vehicle satisfies the CL mitigation illumination implementation condition (step S102). Here, the CL mitigation illumination implementation condition is set to be a vibration amplitude of d(0) or more, where d(0) = 5 cm.

[0072] If the vibration state of the vehicle satisfies the CL mitigation illumination implementation conditions (YES in step S102), the light distribution control unit 12 determines the mode of CL mitigation illumination (step S103) and controls the lighting device 30 to implement CL mitigation illumination (step S104).

[0073] The learning unit 14 then checks whether the driver has input a request to terminate CL mitigation illumination via the operating device 24 (step S201). If a request to terminate CL mitigation illumination has been received (YES in step S201), the learning unit 14 records the vibration amplitude d(n) at the time of the nth driver request as training information indicating a condition under which CL mitigation illumination is not required (step S202). The learning unit 14 then provisionally sets the vibration amplitude being equal to or greater than d(n) as a CL mitigation illumination implementation condition in the vibration state determination unit 11 (step S203), and instructs the light distribution control unit 12 to terminate CL mitigation illumination (step S204). Note that if a request to terminate CL mitigation illumination has not been received (NO in step S201), steps S202 to S204 are not executed.

[0074] On the other hand, if the vibration state of the vehicle does not satisfy the CL mitigation illumination implementation condition (NO in step S102), the learning unit 14 checks whether the driver has input a request to implement CL mitigation illumination to the operation device 24 (step S205). If a request to implement CL mitigation illumination has been received (YES in step S205), the learning unit 14 records the vibration amplitude d(m) at the time of the mth request from the driver as training information indicating the condition for CL mitigation illumination (step S206). Then, the learning unit 14 provisionally sets the vibration amplitude being equal to or greater than d(m) as the CL mitigation illumination implementation condition in the vibration state determination unit 11 (step S207) and causes the light distribution control unit 12 to implement CL mitigation illumination (step S208). Note that if a request to implement CL mitigation illumination has not been received (NO in step S205), steps S206 to S209 are not executed.

[0075] Thereafter, the light distribution control unit 12 checks whether the low beam forward illumination has ended (step S105). If the low beam forward illumination is continuing (NO in step S105), the process returns to step S101, and the above operations are repeated.

[0076] When low-beam forward illumination is terminated (YES in step S105), the learning unit 14 learns the relationship between the vibration state of the vehicle and the necessity of CL mitigation illumination according to a predetermined learning rule based on d(n) and d(m) recorded as the teacher information (step S210). The learning unit 14 then calculates new CL mitigation illumination implementation conditions based on the learning results and sets the new CL mitigation illumination implementation conditions in the vibration state determination unit 11 (step S211). Thereafter, the flow in FIG. 32 ends.

[0077] The learning process and the calculation process of the new CL relaxation irradiation implementation condition may be performed using any logic. For example, the new CL relaxation irradiation implementation condition may be calculated using a statistical method for past multiple d(m)s and multiple d(n). For example, the average value of multiple d(m)s and multiple d(n)s may be set as the new d(0). Furthermore, a weighted average of multiple d(m)s and multiple d(n)s, in which more recent values ​​are weighted, may be set as the new d(0).

[0078] The discomfort experienced by a driver due to fluctuations in the low-beam cutoff line varies depending on the vibration state of the vehicle and also varies from person to person. In this embodiment, the learning unit 14 learns the relationship between the vibration state of the vehicle and the necessity of CL mitigation illumination based on the vibration state of the vehicle and requests from the driver to implement and terminate CL mitigation illumination, and updates the CL mitigation illumination implementation conditions based on the learning results. As a result, CL mitigation illumination is implemented at a timing that suits the driver's preference, thereby reducing the driver's discomfort.

[0079] [Variant 1] The learning unit 14 learns the vibration conditions when a request to implement or terminate CL mitigation irradiation is input by the driver, but the vibration conditions learned by the learning unit 14 are not limited to conditions related to the amplitude of vibration, and may also include, for example, the frequency of vibration, vibration conditions in the rolling direction, and vibration conditions in the yawing direction.

[0080] [Modification 2] The learning unit 14 may learn the relationship between the vibration state of the vehicle and the necessity of cutoff line mitigating illumination from the state of the driver while low beam forward illumination is being performed.

[0081] Fig. 34 is a diagram showing the configuration of a light control system 1 according to Variation 2 of Embodiment 3. The configuration of the light control system 1 in Fig. 34 is similar to the configuration in Fig. 31 , except that the operating device 24 is replaced with a driver monitoring system (DMS) 23.

[0082] The DMS 23 detects the driver's state. In this modification, the DMS 23 detects a specific state related to the driver's discomfort using a non-invasive physiological or psychological measurement means and provides the detection result to the learning unit 14. A method for detecting a specific state related to the driver's discomfort includes, for example, detecting the driver's line of sight, facial expression, gestures, heart rate, etc. from an image of the driver to detect the specific state related to discomfort. For example, the driver's frowning expression, squinting, or covering their eyes with their hands may be recognized as facial expressions and gestures indicating discomfort. Another method for detecting discomfort is to detect an increase in the driver's heart rate or pulse rate using a millimeter-wave laser or a blood flow sensor installed on the steering wheel.

[0083] The learning unit 14 learns the relationship between the vibration state of the vehicle and the need for CL mitigation illumination based on the vibration state of the vehicle when the DMS 23 detects a specific state of discomfort of the driver during forward illumination with low beam.

[0084] Fig. 34 is a flowchart showing the operation of the light distribution control device 10 according to this modification. The operation of the light distribution control device 10 according to this modification will be described below with reference to the flowchart in Fig. 34. Note that steps S101 to S105 in Fig. 32 are basically the same as steps S101 to S105 in Fig. 20.

[0085] The flow of Fig. 32 starts when the headlights 31 of the vehicle start illuminating the road ahead with low beams. When low beam illumination starts, the vibration state determination unit 11 acquires vibration information about the vehicle from the vibration sensor 21 (step S101). Based on the acquired vibration information, the vibration state determination unit 11 determines whether the vibration state of the vehicle satisfies the CL mitigation illumination implementation condition (step S102). Here, the CL mitigation illumination implementation condition is set to be a vibration amplitude of d(0) or more, where d(0) = 5 cm.

[0086] If the vibration state of the vehicle satisfies the CL mitigation illumination implementation conditions (YES in step S102), the light distribution control unit 12 determines the mode of CL mitigation illumination (step S103) and controls the lighting device 30 to implement CL mitigation illumination (step S104).

[0087] The learning unit 14 then acquires information about the driver's condition from the DMS 23 (step S301) and checks whether a state indicating driver discomfort has been detected (step S302). If a state indicating driver discomfort has been detected (YES in step S302), the learning unit 14 records the vibration amplitude d(n) at the time when the state indicating driver discomfort was detected for the nth time in step S302 as training information indicating a condition under which CL relaxation irradiation is not required (step S303). If a state indicating driver discomfort has not been detected (NO in step S302), step S303 is not executed.

[0088] On the other hand, if the vibration state of the vehicle does not satisfy the CL mitigation illumination implementation condition (NO in step S102), the learning unit 14 acquires information about the driver's state from the DMS 23 (step S304) and checks whether a state indicating driver discomfort has been detected (step S305). If a state indicating driver discomfort has been detected (YES in step S305), the learning unit 14 records the vibration amplitude d(m) at the time when the state indicating driver discomfort was detected for the mth time in step S305 as training information indicating the condition requiring CL mitigation illumination (step S306). If a state indicating driver discomfort has not been detected (NO in step S305), step S306 is not executed.

[0089] Thereafter, the light distribution control unit 12 checks whether the low beam forward illumination has ended (step S105). If the low beam forward illumination is continuing (NO in step S105), the process returns to step S101, and the above operations are repeated.

[0090] When low-beam forward illumination is terminated (YES in step S105), the learning unit 14 learns the relationship between the vibration state of the vehicle and the necessity of CL mitigation illumination according to a predetermined learning rule based on d(n) and d(m) recorded as the teacher information (step S307). The learning unit 14 then calculates new CL mitigation illumination implementation conditions based on the learning results and sets the new CL mitigation illumination implementation conditions in the vibration state determination unit 11 (step S308). Then, the flow in FIG. 34 ends.

[0091] The learning process and the calculation process of the new CL relaxation irradiation implementation condition may be performed using any logic. For example, the new CL relaxation irradiation implementation condition may be calculated using a statistical method for past multiple d(m)s and multiple d(n). For example, the average value of multiple d(m)s and multiple d(n)s may be set as the new d(0). Furthermore, a weighted average of multiple d(m)s and multiple d(n)s, in which more recent values ​​are weighted, may be set as the new d(0).

[0092] In this modification, the CL mitigation illumination is also performed at a timing that suits the driver's preference, thereby reducing discomfort to the driver. Furthermore, since no operation by the driver is required, the present modification is highly convenient.

[0093] When a state indicating discomfort to the driver is detected (when a determination of YES is made in step S302 or step S305), CL mitigation illumination may be switched on and off, similarly to the flow of FIG.

[0094] This modification may be combined with embodiment 3. That is, the learning unit 14 may learn the relationship between the vibration state of the vehicle and the necessity of CL mitigation illumination from both the operation (driver's intention) input to the operating device 24 and the driver's state detected by the DMS 23, and may then activate CL mitigation illumination.

[0095] [Variation 3] Figure 35 is a diagram showing the configuration of a light control system according to Variation 3 of Embodiment 3. The configuration of the light control system 1 in Figure 35 is obtained by connecting an image processing sensor 25 to the light distribution control device 10 in addition to the configuration in Figure 31. The image processing sensor 25 analyzes images taken of the surroundings of the host vehicle and calculates the brightness ahead of the host vehicle.

[0096] Whether the driver finds the fluctuation of the low beam cut-off line uncomfortable or not depends on the lighting conditions in the surroundings. Therefore, in this modification, the vibration state determination unit 11 acquires information on the brightness around the vehicle from the image processing sensor 25, and learns the relationship between the brightness and vibration state ahead of the vehicle and the necessity of CL mitigation illumination based on the brightness ahead of the vehicle and the vibration state of the vehicle at the time when the driver requests the implementation or termination of CL mitigation illumination.

[0097] It is possible to implement CL mitigation illumination that takes into account not only the vibration state but also the brightness ahead of the vehicle.

[0098] In the third embodiment, an example was shown in which the light distribution control device 10 mounted on each vehicle learned the relationship between the vibration state of the vehicle and the necessity of CL mitigation illumination. However, for example, a server may collect information on multiple vehicles and learn the relationship between the vibration state of the multiple vehicles and the necessity of CL mitigation illumination. This makes it possible to determine CL mitigation illumination implementation conditions suitable for many users.

[0099] <Hardware Configuration Example> Figures 36 and 37 are diagrams showing examples of the hardware configuration of the light distribution control device 10. The functions of the components of the light distribution control device 10 shown in Figure 11 and the like are realized, for example, by a processing circuit 50 shown in Figure 36. That is, the light distribution control device 10 includes a processing circuit 50 that determines whether the vibration state of the host vehicle satisfies a predetermined condition, and, when the condition is satisfied while the host vehicle is performing forward illumination with low beams, controls the lighting devices of the host vehicle to perform cut-off line mitigation illumination, which irradiates an area above the low beam cut-off line with mitigating light that is darker than the low beam. The processing circuit 50 may be dedicated hardware, or may be configured using a processor (also called a central processing unit (CPU), processing device, arithmetic device, microprocessor, microcomputer, or DSP (Digital Signal Processor)) that executes a program stored in a memory.

[0100] When the processing circuitry 50 is dedicated hardware, the processing circuitry 50 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination of these. The functions of the components of the light distribution control device 10 may be realized by individual processing circuits, or these functions may be realized together by a single processing circuit.

[0101] FIG. 37 shows an example of the hardware configuration of the light distribution control device 10 when the processing circuit 50 is configured using a processor 51 that executes a program. In this case, the functions of the components of the light distribution control device 10 are realized by software, etc. (software, firmware, or a combination of software and firmware). The software, etc. is written as a program and stored in memory 52. ​​The processor 51 realizes the functions of each part by reading and executing the program stored in memory 52. ​​That is, the light distribution control device 10 includes memory 52 for storing a program that, when executed by the processor 51, results in the execution of a process for determining whether the vibration state of the host vehicle satisfies a predetermined condition, and a process for controlling the host vehicle's lighting devices to perform cutoff line mitigation illumination, which irradiates a mitigation light that is darker than the low beam above the low beam cutoff line of the host vehicle when the condition is satisfied during forward illumination with the low beam of the host vehicle. In other words, this program can be said to cause a computer to execute the procedures and methods of operation of the components of the light distribution control device 10.

[0102] Here, the memory 52 may be, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically Erasable Programmable Read Only Memory), a HDD (Hard Disk Drive), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD (Digital Versatile Disc), and a drive device for such a disk, or any other storage medium that will be used in the future.

[0103] The above describes a configuration in which the functions of the components of the light distribution control device 10 are realized either by hardware or software, etc. However, the present invention is not limited to this, and the light distribution control device 10 may be configured such that some of the components are realized by dedicated hardware and other components are realized by software, etc. For example, it is possible to realize the functions of some of the components by a processing circuit 50 as dedicated hardware, and to realize the functions of other components by having the processing circuit 50 as a processor 51 read and execute a program stored in memory 52.

[0104] As described above, the light distribution control device 10 can realize the above-described functions by hardware, software, or a combination of these.

[0105] It is possible to freely combine the embodiments, and to modify or omit the embodiments as appropriate.

[0106] The above description is illustrative in all respects, and it is understood that countless variations not illustrated can be envisioned.

[0107] REFERENCE SIGNS LIST 1 Light control system, 10 Light distribution control device, 11 Vibration state determination unit, 12 Light distribution control unit, 13 Color tone adjustment unit, 14 Learning unit, 21 Vibration sensor, 22 Road surface state detection device, 23 DMS, 24 Operation device, 25 Image processing sensor, 30 Lighting device, 31 Headlight, 32 Sublight.

Claims

1. A light distribution control device comprising: a vibration state determination unit that determines whether or not the vibration state of a vehicle satisfies a predetermined condition; and a light distribution control unit that, when the condition is satisfied while the vehicle is performing forward illumination with its low beam, controls the lighting device of the vehicle to perform cut-off line mitigation illumination by irradiating an area above the cut-off line of the low beam with mitigation light that is darker than the low beam.

2. The light distribution control device according to claim 1, wherein the reduced light has a luminous intensity distribution in which the luminous intensity decreases with increasing distance from the cutoff line.

3. The light distribution control device according to claim 1, wherein the light distribution control unit expands the irradiation range of the mitigating light in an upward direction as the amplitude of the vibration of the host vehicle increases.

4. The light distribution control device according to claim 2, wherein the light distribution control unit makes the gradient of the luminous intensity distribution of the mitigating light in the vicinity of the cut-off line gentler as the frequency of vibration of the vehicle increases.

5. The light distribution control device according to claim 1, further comprising a color tone adjustment unit that adjusts the color tone of the mitigating light based on the color tone of the road surface ahead of the vehicle.

6. The light distribution control device according to claim 5, wherein the color tone adjustment unit adjusts a distribution of color tones of the reduced light so that the reduced light becomes less noticeable as it moves away from the cutoff line.

7. The light distribution control device according to claim 1, further comprising a learning unit that learns the relationship between the vibration state of the vehicle and the necessity for irradiation to reduce the cutoff line, and updates the conditions based on the learning results.

8. The light distribution control device of claim 7, wherein the light distribution control unit is capable of starting or ending the cutoff line mitigating irradiation in response to an operation by the driver of the vehicle regardless of whether the condition is satisfied or not, and the learning unit learns the relationship between the vibration state of the vehicle and the necessity for the cutoff line mitigating irradiation based on the vibration state of the vehicle when the driver performs an operation to start or end the cutoff line mitigating irradiation.

9. The light distribution control device as described in claim 7, wherein the learning unit learns the relationship between the vibration state of the vehicle and the necessity for the cutoff line mitigating illumination based on the vibration state of the vehicle when a specific state of the driver related to discomfort is detected by a driver monitoring system of the vehicle while the forward illumination is being performed by the low beam.

10. The light distribution control device according to claim 1, wherein the light distribution control unit is configured to expand the irradiation range of the mitigating light in the lateral direction as the traveling speed of the host vehicle decreases.

11. The light distribution control device according to claim 1, wherein the light distribution control unit reduces a luminance of the mitigating light when an oncoming vehicle is detected ahead of the host vehicle.

12. A light distribution control method, in which a vibration state determination unit of a light distribution control device determines whether or not the vibration state of the vehicle satisfies a predetermined condition, and a light distribution control unit of the light distribution control device controls the lighting device of the vehicle when the condition is satisfied while the vehicle is performing forward illumination with a low beam to perform cut-off line mitigating illumination, which irradiates mitigating light that is darker than the low beam above the cut-off line of the low beam.

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