Vehicle lighting device control device

Abstract

To provide a novel technique for extracting information on an inclination angle of a vehicle with respect to a road surface on the basis of a value detected by an acceleration sensor in auto-leveling control of a vehicle lamp using the acceleration sensor.SOLUTION: A control device of a vehicle lamp includes: a receiving unit for receiving acceleration which is detected by an acceleration sensor and from which vehicle longitudinal direction acceleration and vehicle vertical direction acceleration can be derived; a control unit for generating a control signal for indicating optical axis adjustment of the vehicle lamp, on the basis of variation in ratio between an amount of temporal change of the vehicle longitudinal direction acceleration and an amount of temporal change of the vehicle vertical direction acceleration during at least one of acceleration and deceleration of a vehicle; and a transmitting unit for transmitting the control signal to an optical axis adjusting unit of the vehicle lamp.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a vehicle lighting control device, a vehicle lighting system, and a vehicle lighting control method, and more particularly to a vehicle lighting control device, a vehicle lighting system, and a vehicle lighting control method used in automobiles and the like. [Background technology]

[0002] Conventionally, auto-leveling control is known that automatically adjusts the optical axis position of vehicle headlights to change the illumination direction in accordance with the tilt angle of the vehicle in the pitch direction. Generally, auto-leveling control uses a vehicle height sensor as a vehicle tilt detection device, and adjusts the optical axis position of the headlights based on the vehicle pitch angle detected by the vehicle height sensor. In contrast, Patent Document 1 discloses a configuration using a gravity sensor as the tilt detection device. Patent Document 2 discloses a configuration using a three-dimensional gyro sensor that detects the tilt angle relative to a horizontal plane as the tilt detection device. Patent Document 3 discloses a configuration using an inclinometer that detects the tilt angle of the vehicle relative to the direction of gravity as the tilt detection device. Patent Document 4 discloses a configuration using an acceleration sensor that detects gravitational acceleration as the tilt detection device.

[0003] If an acceleration sensor including a gravity sensor or a three-dimensional gyro sensor is used as a vehicle inclination detection device, the auto-leveling system can be made cheaper and lighter than when a vehicle height sensor is used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-085459 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-314856 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-341578 [Patent Document 4] Japanese Patent Application Laid-Open No. 2009-126268 Summary of the Invention [Problem to be solved by the invention]

[0005] In auto-leveling control using an acceleration sensor, the inclination angle detected by the acceleration sensor is the vehicle's inclination angle with respect to the horizontal plane, which includes the inclination angle of the road surface with respect to the horizontal plane and the inclination angle of the vehicle with respect to the road surface. Meanwhile, the vehicle's inclination angle required for auto-leveling control is the vehicle's inclination angle with respect to the road surface. Therefore, in auto-leveling control using an acceleration sensor, it is necessary to extract information about the vehicle's inclination angle with respect to the road surface from the vehicle's inclination angle with respect to the horizontal plane obtained by the acceleration sensor. In response to this, the present inventors have devised a new method for extracting information about the vehicle's inclination angle with respect to the road surface from the vehicle's inclination angle with respect to the horizontal plane obtained from the detection value of the acceleration sensor.

[0006] The present invention was made based on this recognition by the inventors, and its purpose is to provide a new technology for extracting information about the vehicle's inclination angle relative to the road surface from the detection value of an acceleration sensor in auto-leveling control of vehicle lighting fixtures using an acceleration sensor. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the present invention is a control device for a vehicle lamp, the control device comprising: a receiving unit for receiving acceleration detected by an acceleration sensor from which acceleration in the longitudinal direction of the vehicle and acceleration in the vertical direction of the vehicle can be derived; a control unit for generating a control signal that instructs adjustment of the optical axis of the vehicle lamp based on a change in the ratio between the amount of change in acceleration over time in the longitudinal direction of the vehicle and the amount of change in acceleration over time in the vertical direction of the vehicle during at least one of acceleration and deceleration of the vehicle; and a transmitting unit for transmitting the control signal to a optical axis adjustment unit of the vehicle lamp.

[0008] According to this aspect, in the auto-leveling control of a vehicle lamp using an acceleration sensor, a new technique can be provided for extracting information about the inclination angle of the vehicle relative to the road surface from the detected value of the acceleration sensor.

[0009] In the above aspect, the control unit may plot the detection values ​​of the acceleration sensor over time during at least one of vehicle acceleration and deceleration on a coordinate system in which the acceleration in the vehicle's longitudinal direction is set as the first axis and the acceleration in the vehicle's vertical direction is set as the second axis, and may use the slope of the line or vector obtained from at least two points as a ratio.

[0010] In the above aspect, the control unit may use the slope of a line or vector obtained from the detection value of the acceleration sensor when the vehicle acceleration is within a predetermined range and the detection value of the acceleration sensor when the vehicle deceleration is within a predetermined range as the ratio.

[0011] Furthermore, in the above aspect, when the inclination angle of the vehicle with respect to the horizontal plane is called the total angle, this total angle includes a first angle which is the inclination angle of the road surface with respect to the horizontal plane and a second angle which is the inclination angle of the vehicle with respect to the road surface, the total angle can be obtained from the detection value of the acceleration sensor, the control unit holds a reference value of the first angle and a reference value of the second angle, and if the total angle changes while the vehicle is stopped, generates a control signal using the second angle obtained from the detection value of the acceleration sensor and the reference value of the first angle and holds the obtained second angle as a new reference value, if the total angle changes while the vehicle is moving, avoids generating a control signal or generates a control signal instructing to maintain the position of the optical axis, and holds the first angle obtained from the detection value of the acceleration sensor and the reference value of the second angle when the vehicle is stopped as a new reference value, and if the ratio changes, corrects the position of the optical axis of the vehicle lamp based on the change in the ratio. According to this aspect, it is possible to avoid a decrease in the accuracy of the auto-leveling control due to the accumulation of detection errors of the acceleration sensor, etc., caused by repeatedly rewriting the reference values ​​of the first angle and the second angle, or to reduce the decrease in the accuracy of the auto-leveling control.

[0012] In the above aspect, the control unit may derive a difference between a reference value of the second angle and the second angle derived from the ratio, and correct the reference value of the second angle so that the difference becomes smaller. Furthermore, when the difference exceeds a predetermined threshold, the control unit may correct the reference value of the second angle by an amount smaller than the predetermined threshold.

[0013] In the above aspect, the control unit may obtain the inclination angle of the vehicle with respect to the road surface from the ratio during at least one of acceleration and deceleration of the vehicle on a horizontal plane that has been recorded in advance and the ratio of the current vehicle, and generate a control signal using the obtained inclination angle of the vehicle with respect to the road surface. According to this aspect, the optical axis adjustment can be performed without increasing the adjustment error due to repeated rewriting of the reference value, which may occur in the case of auto-leveling control that rewrites the reference value of the road surface angle θr when the total angle θ changes while the vehicle is traveling, and rewrites the reference value of the vehicle attitude angle θv when the total angle θ changes while the vehicle is stopped.

[0014] In the above aspect, the control unit may obtain a linear approximation for the plotted points, and may use the slope of the linear approximation as the ratio.

[0015] Another aspect of the present invention is a vehicle lighting system comprising a vehicle lighting fixture capable of adjusting its light axis, an acceleration sensor, and a control unit for controlling the vehicle lighting fixture, wherein the control unit receives acceleration detected by the acceleration sensor from which acceleration in the vehicle's longitudinal direction and vehicle's vertical direction can be derived, and adjusts the light axis of the vehicle lighting fixture based on a change in the ratio between the amount of change in acceleration in the vehicle's longitudinal direction and the amount of change in acceleration in the vehicle's vertical direction during at least one of acceleration and deceleration of the vehicle.

[0016] Yet another aspect of the present invention is a method for controlling a vehicle lamp, which is a method for controlling a vehicle lamp for adjusting the optical axis of the vehicle lamp using an acceleration sensor, and is characterized in that the optical axis of the vehicle lamp is adjusted based on a change in the ratio between the amount of change in acceleration in the longitudinal direction of the vehicle and the amount of change in acceleration in the vertical direction of the vehicle during at least one of acceleration and deceleration of the vehicle.

[0017] These aspects also provide a new technique for extracting information about the inclination angle of the vehicle relative to the road surface from the detected value of the acceleration sensor in auto-leveling control of a vehicle lamp using an acceleration sensor. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a new technique for extracting information about the inclination angle of the vehicle relative to the road surface from the detected value of the acceleration sensor in auto-leveling control of a vehicle lamp using an acceleration sensor. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic vertical cross-sectional view illustrating the internal structure of a vehicle lighting system according to a first embodiment. [Figure 2] 4 is a functional block diagram illustrating the operational cooperation between an illumination control unit of the headlamp unit and a vehicle control unit on the vehicle side. FIG. [Figure 3] 3(A) and 3(B) are schematic diagrams for explaining the relationship between the direction of the vehicle's motion acceleration vector and the vehicle attitude angle. [Figure 4] 1 is a graph showing the relationship between acceleration in the vehicle longitudinal direction and acceleration in the vehicle vertical direction. [Figure 5] 4 is a flowchart of auto-leveling control of the vehicle lighting system according to the first embodiment. [Figure 6] FIG. 10 is a schematic diagram for explaining auto-leveling control of a vehicle lighting system according to a third embodiment. [Figure 7]10 is a flowchart of auto-leveling control of a vehicle lighting system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and redundant explanations will be omitted where appropriate. Furthermore, the embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0021] (Embodiment 1) FIG. 1 is a schematic vertical cross-sectional view illustrating the internal structure of a vehicle lighting system according to a first embodiment. The vehicle lighting system 200 of this embodiment is a variable light distribution headlamp system in which a pair of symmetrically formed headlamp units are arranged on the left and right sides of the vehicle in the vehicle width direction. The left and right headlamp units have substantially the same configuration except for their symmetrical structure. Therefore, the following describes the structure of the right headlamp unit 210R, and the description of the left headlamp unit will be omitted as appropriate. Note that when describing the components of the left headlamp unit, the same reference numerals as the corresponding components of headlamp unit 210R will be used for ease of explanation.

[0022] The headlamp unit 210R has a lamp body 212 with an opening on the vehicle front side, and a translucent cover 214 that covers this opening. The lamp body 212 has a removable cover 212a on the vehicle rear side that can be removed when replacing the bulb 14, etc. The lamp body 212 and the translucent cover 214 form a lamp chamber 216. The lamp chamber 216 houses a lamp unit 10 (vehicle lamp) that irradiates light in front of the vehicle.

[0023] A lamp bracket 218 having a pivot mechanism 218a serving as the center of vertical and horizontal swing of the lamp unit 10 is formed on a part of the lamp unit 10. The lamp bracket 218 is threadedly engaged with an aiming adjustment screw 220, which is rotatably supported on the wall surface of the lamp body 212. Therefore, the lamp unit 10 is fixed at a predetermined position within the lamp chamber 216 determined by the adjustment state of the aiming adjustment screw 220, and can change its posture, such as leaning forward or backward, around the pivot mechanism 218a based on that position. In addition, a rotation shaft 222a of a swivel actuator 222 is fixed to the underside of the lamp unit 10. The swivel actuator 222 is used to configure a curved road variable light distribution headlamp that illuminates the traveling direction when driving on a curved road, for example. The swivel actuator 222 is fixed to a unit bracket 224.

[0024] A leveling actuator 226 disposed outside the lamp body 212 is connected to the unit bracket 224. The leveling actuator 226 is configured, for example, with a motor that extends and retracts a rod 226a in the directions of arrows M and N. When the rod 226a extends in the direction of arrow M, the lamp unit 10 pivots around the pivot mechanism 218a so as to assume a rearward tilting position. Conversely, when the rod 226a contracts in the direction of arrow N, the lamp unit 10 pivots around the pivot mechanism 218a so as to assume a forward tilting position. When the lamp unit 10 assumes a rearward tilting position, a leveling adjustment can be made to adjust the pitch angle of the optical axis O, i.e., the vertical angle of the optical axis O, upward. When the lamp unit 10 assumes a forward tilting position, a leveling adjustment can be made to adjust the pitch angle of the optical axis O downward.

[0025] An illumination control unit 228 (control unit, control device) that controls the on / off of the lamp unit 10, the formation of a light distribution pattern, and the adjustment of the optical axis of the lamp unit 10 is disposed on the inner wall surface of the lamp chamber 216 below the lamp unit 10. In the case of FIG. 1, an illumination control unit 228R for controlling the headlamp unit 210R is disposed. This illumination control unit 228R also controls the swivel actuator 222, the leveling actuator 226, etc. The illumination control unit 228R may be provided outside the headlamp unit 210R.

[0026] The lamp unit 10 can be equipped with an aiming adjustment mechanism. For example, an aiming pivot mechanism (not shown), which serves as the center of swing during aiming adjustment, is disposed at the connection between the rod 226a of the leveling actuator 226 and the unit bracket 224. Furthermore, the aforementioned aiming adjustment screws 220 are disposed on the lamp bracket 218 at intervals in the vehicle width direction. By rotating the two aiming adjustment screws 220, the lamp unit 10 can be rotated up, down, left, and right around the aiming pivot mechanism, thereby adjusting the optical axis O up, down, left, and right. This aiming adjustment is performed, for example, when the vehicle is shipped, during vehicle inspection, or when the headlamp unit 210R is replaced. The headlamp unit 210R is adjusted to a position determined by design, and the formation of the light distribution pattern and the adjustment of the optical axis position are controlled based on this position.

[0027] The lamp unit 10 includes a shade mechanism 18 including a rotating shade 12, a lamp housing 17 supporting a bulb 14 as a light source and a reflector 16 on its inner wall, and a projection lens 20. The bulb 14 may be, for example, an incandescent bulb, a halogen lamp, a discharge bulb, or an LED. In this embodiment, the bulb 14 is a halogen lamp. The reflector 16 reflects light emitted from the bulb 14. A portion of the light from the bulb 14 and the light reflected by the reflector 16 is guided to the projection lens 20 via the rotating shade 12. The rotating shade 12 is a cylindrical member that can rotate around a rotation axis 12a and includes a notch cut out in the axial direction and multiple shade plates (not shown). Either the notch or the shade plate is moved along the optical axis O to form a predetermined light distribution pattern. At least a portion of the reflector 16 is ellipsoidal, and this ellipsoidal surface is set so that the cross section including the optical axis O of the lamp unit 10 is at least a part of an ellipse. The ellipsoidal portion of the reflector 16 has a first focal point approximately at the center of the bulb 14 and a second focal point on the rear focal plane of the projection lens 20.

[0028] The projection lens 20 is disposed on an optical axis O extending in the longitudinal direction of the vehicle. The bulb 14 is disposed rearward of a rear focal plane, which is a focal plane including the rear focal point of the projection lens 20. The projection lens 20 is made of a plano-convex aspherical lens with a convex front surface and a flat rear surface, and projects the light source image formed on the rear focal plane as an inverted image onto a virtual vertical screen in front of the vehicle lighting system 200. Note that the configuration of the lighting unit 10 is not particularly limited to this, and it may be a reflective lighting unit that does not have the projection lens 20.

[0029] 2 is a functional block diagram illustrating the operational cooperation between the illumination control unit of the headlamp unit configured as described above and the vehicle control unit on the vehicle side. As described above, the right headlamp unit 210R and the left headlamp unit 210L are basically configured the same, so only the headlamp unit 210R side will be described and the description of the headlamp unit 210L side will be omitted.

[0030] The illumination control unit 228R of the headlamp unit 210R has a receiving unit 228R1, a control unit 228R2, a transmitting unit 228R3, and a memory 228R4. The illumination control unit 228R controls the power supply circuit 230 based on information obtained from a vehicle control unit 302 installed in the vehicle 300, and executes lighting control of the bulb 14. The illumination control unit 228R also controls the variable shade control unit 232, swivel control unit 234, and leveling control unit 236 (optical axis adjustment unit) based on information obtained from the vehicle control unit 302. Various information transmitted from the vehicle control unit 302 is received by the receiving unit 228R1, and various control signals are generated by the control unit 228R2 from the received information and, as necessary, information stored in the memory 228R4. The transmitting unit 228R3 then transmits the control signals to the power supply circuit 230, variable shade control unit 232, swivel control unit 234, leveling control unit 236, etc. of the lamp unit 10. The memory 228R4 is, for example, a non-volatile memory.

[0031] The variable shade control unit 232 controls the rotation of a motor 238 connected to the rotary shaft 12a of the rotating shade 12 to move the desired shade plate or cutout onto the optical axis O. The swivel control unit 234 also controls the swivel actuator 222 to adjust the angle of the optical axis O of the lighting unit 10 in the vehicle width direction (left-right direction). For example, when turning, such as around a curve or making a right or left turn, the optical axis O of the lighting unit 10 is oriented in the direction of travel. The leveling control unit 236 controls the leveling actuator 226 to adjust the optical axis O of the lighting unit 10 in the vertical direction of the vehicle (pitch angle direction). For example, the position of the lighting unit 10 is adjusted in response to the forward or backward tilt of the vehicle posture when the load amount or the number of passengers increases or decreases, thereby optimizing the reach of the forward-illuminated light. The vehicle control unit 302 also provides similar information to the headlamp unit 210L, and an illumination control unit 228L (control unit, control device) provided in the headlamp unit 210L executes the same control as the illumination control unit 228R.

[0032] The light distribution pattern formed by the headlamp units 210L, 210R can be switched depending on the operation of the light switch 304 by the driver. In this case, the illumination control units 228L, 228R control the motor 238 via the variable shade control unit 232 in accordance with the operation of the light switch 304 to determine the light distribution pattern to be formed by the lamp unit 10. Furthermore, the headlamp units 210L, 210R may be automatically controlled to form an optimal light distribution pattern by detecting the state of the vehicle 300 and the circumstances around the vehicle using various sensors, regardless of the operation of the light switch 304. This automatic control of forming a light distribution pattern is executed, for example, when an instruction to automatically form a light distribution pattern is issued by the light switch 304.

[0033] A camera 306 such as a stereo camera is connected to the vehicle control unit 302 in order to detect objects such as preceding vehicles and oncoming vehicles. Image frame data captured by the camera 306 is subjected to predetermined image processing such as object recognition processing in an image processing unit 308, and the recognition results are provided to the vehicle control unit 302. The vehicle control unit 302 can also acquire information from a steering sensor 310, a vehicle speed sensor 312, a navigation system 314, an acceleration sensor 316, and the like mounted on the vehicle 300. This enables the illumination control units 228L, 228R to select a light distribution pattern to be formed and change the direction of the optical axis O in accordance with the traveling state and attitude of the vehicle 300.

[0034] Next, the auto-leveling control by the vehicle lighting system 200 having the above-described configuration will be described in detail. Figures 3(A) and 3(B) are schematic diagrams for explaining the relationship between the direction of the vehicle's motion acceleration vector and the vehicle attitude angle. Figure 3(A) shows a state in which the vehicle attitude angle θv, which will be described later, remains unchanged, and Figure 3(B) shows a state in which the vehicle attitude angle θv has changed. In addition, in Figures 3(A) and 3(B), the motion acceleration vector α and resultant acceleration vector β that occur when the vehicle 300 moves forward are indicated by solid arrows, and the motion acceleration vector α and resultant acceleration vector β that occur when the vehicle 300 decelerates or moves backward are indicated by dashed arrows. Figure 4 is a graph showing the relationship between the acceleration in the vehicle's longitudinal direction and the acceleration in the vehicle's vertical direction.

[0035] For example, when luggage is loaded in the luggage compartment at the rear of the vehicle or when passengers are in the rear seats, the vehicle posture tilts backward. When the luggage is removed or the passengers in the rear seats get off, the vehicle posture tilts forward from the backward posture. The illumination direction of the lamp unit 10 also fluctuates up and down depending on the posture of the vehicle 300, lengthening or shortening the forward illumination distance. Therefore, the illumination control units 228L and 228R receive the detection value of the acceleration sensor 316 via the vehicle control unit 302 and control the leveling actuator 226 via the leveling control unit 236 to set the pitch angle of the optical axis O to an angle corresponding to the vehicle posture. By implementing auto-leveling control that adjusts the leveling of the lamp unit 10 in real time based on the vehicle posture, the reach distance of the forward illumination can be optimally adjusted even when the vehicle posture changes depending on the usage situation of the vehicle 300.

[0036] The acceleration sensor 316 is, for example, a three-axis acceleration sensor having an X-axis, a Y-axis, and a Z-axis that are orthogonal to one another. The acceleration sensor 316 is attached to the vehicle 300 so that the X-axis of the sensor is aligned with the longitudinal axis of the vehicle 300, the Y-axis of the sensor is aligned with the lateral axis of the vehicle 300, and the Z-axis of the sensor is aligned with the vertical axis of the vehicle 300. The acceleration sensor 316 detects the inclination of the vehicle 300 with respect to a gravitational acceleration vector G, and outputs the numerical values ​​of each axial component of the gravitational acceleration vector G in the three axial directions. That is, the acceleration sensor 316 can detect, as a vector, a total angle θ that is the inclination angle of the vehicle with respect to a horizontal plane (total angle) including a road surface angle θr that is the inclination angle of the road surface with respect to a horizontal plane (first angle) and a vehicle attitude angle θv that is the inclination angle of the vehicle with respect to the road surface (second angle). Furthermore, while the vehicle 300 is traveling, the acceleration sensor 316 detects a resultant acceleration vector β, which is a combination of the gravity acceleration vector G and the motion acceleration vector α resulting from the movement of the vehicle 300, and outputs the numerical values ​​of each axial component of the resultant acceleration vector β in the three-axis direction. The road surface angle θr, the vehicle attitude angle θv, and the total angle θ are each angles in the up-down direction of the X-axis, in other words, the angle in the pitch direction of the vehicle 300. In the following description, the Y-axis component of the acceleration sensor 316, i.e., the angle in the roll direction of the vehicle 300, is not taken into consideration. The acceleration sensor 316 may be attached to the vehicle 300 in any orientation. In this case, the numerical values ​​of the X-axis, Y-axis, and Z-axis components output from the acceleration sensor 316 are converted by the illumination control unit 228R into components of the vehicle's longitudinal axis, lateral axis, and up-down axis.

[0037] The purpose of auto-leveling control is to absorb changes in the forward illumination distance of a vehicle lamp that accompany changes in the vehicle's pitch tilt angle, thereby maintaining an optimal forward reach of the illuminated light. Therefore, the vehicle tilt angle required for auto-leveling control is the vehicle attitude angle θv. In other words, it is desirable to adjust the optical axis position of the lamp unit 10 when the vehicle attitude angle θv changes, and to maintain the optical axis position of the lamp unit 10 when the road surface angle θr changes. To achieve this, it is necessary to extract information about the vehicle attitude angle θv from the total angle θ obtained from the acceleration sensor 316.

[0038] Here, vehicle 300 moves parallel to the road surface. Therefore, motion acceleration vector α is a vector parallel to the road surface regardless of vehicle attitude angle θv. Furthermore, as shown in FIG. 3(A), when vehicle attitude angle θv of vehicle 300 is 0°, theoretically, the X-axis of acceleration sensor 316 (or the front-rear axis of vehicle 300) is parallel to the road surface, and therefore motion acceleration vector α is a vector parallel to the X-axis of acceleration sensor 316. Therefore, when the magnitude of motion acceleration vector α changes due to acceleration or deceleration of the vehicle, the trajectory of the tip of resultant acceleration vector β detected by acceleration sensor 316 is a straight line parallel to the X-axis. On the other hand, as shown in FIG. 3(B), when vehicle attitude angle θv is not 0°, the X-axis of acceleration sensor 316 deviates obliquely from the road surface, and therefore motion acceleration vector α is a vector extending obliquely with respect to the X-axis of acceleration sensor 316. Therefore, when the magnitude of the motion acceleration vector α changes due to acceleration or deceleration of the vehicle, the locus of the tip of the resultant acceleration vector β is a straight line inclined with respect to the X-axis.

[0039] Therefore, the illumination control unit 228R receives the acceleration in the vehicle longitudinal direction and the vehicle vertical direction from the acceleration sensor 316 by the receiving unit 228R1. Then, the control unit 228R2 calculates the ratio of the amount of change in acceleration in the vehicle longitudinal direction to the amount of change in acceleration in the vehicle vertical direction over time during at least one of acceleration and deceleration of the vehicle 300. For example, as shown in FIG. 4, the illumination control unit 228R plots the detected values ​​of the acceleration sensor 316 over time during at least one of acceleration and deceleration of the vehicle on a coordinate system in which the acceleration in the vehicle longitudinal direction is set as the first axis (x-axis) and the acceleration in the vehicle vertical direction is set as the second axis (z-axis). A1 ~t An is the time t1 to t in the state shown in FIG. n is the detected value of the acceleration sensor 316 at point t B1 ~t Bn is the time t1 to t in the state shown in FIG. nThe acceleration sensor 316 detects the value at the point t. Then, the slope of the line or vector obtained from at least two points is calculated as the ratio. In this embodiment, the irradiation control unit 228R calculates the slope of the line or vector obtained from the plotted points t A1 ~t An ,t B1 ~t Bn Linear approximation formulas A and B are found using the least squares method or the like, and the slopes of the linear approximation formulas A and B are calculated as a ratio.

[0040] When the vehicle attitude angle θv is 0°, the detection values ​​of the acceleration sensor 316 provide a linear approximation equation A that is parallel to the x-axis. That is, the slope of the linear approximation equation A is 0. In contrast, when the vehicle attitude angle θv is not 0°, the detection values ​​of the acceleration sensor 316 provide a linear approximation equation B that has a slope that corresponds to the vehicle attitude angle θv. Therefore, by measuring the change in the ratio of the amount of change in acceleration with time in the vehicle longitudinal direction and the vehicle vertical direction when the vehicle 300 accelerates or decelerates, it is possible to know the change in the vehicle attitude angle θv from the detection values ​​of the acceleration sensor 316 as information about the vehicle attitude angle θv. Then, by using the obtained change information about the vehicle attitude angle θv, it is possible to achieve more accurate auto-leveling control.

[0041] The vehicular lighting system 200 according to this embodiment performs the following auto-leveling control using information about the vehicle attitude angle θv obtained by detecting the change in the ratio. That is, first, the vehicle 300 is placed on a horizontal plane at, for example, a vehicle manufacturer's manufacturing plant or a dealer's maintenance plant, to establish a reference state. In the reference state, the vehicle 300 has one occupant in the driver's seat or is empty. Then, an initialization signal is transmitted to the illumination control unit 228R by operating a switch on an initialization processing device at the plant or by communication through a Controller Area Network (CAN) system connecting the illumination control unit 228R and the acceleration sensor 316 via the vehicle control unit 302. The initialization signal transmitted to the illumination control unit 228R is received by a receiver 228R1 and sent to a control unit 228R2. Upon receiving the initialization signal, the control unit 228R2 performs initial aiming adjustment using the output value of the acceleration sensor 316 received by the receiver 228R1 as a reference tilt angle. In addition, the control unit 228R2 stores the output value of the acceleration sensor 316 at this time in the memory 228R4 as the reference value of the road surface angle θr (θr=0°) and the reference value of the vehicle attitude angle θv (θv=0°), thereby retaining these reference values.

[0042] While the vehicle is traveling, the vehicle attitude angle θv rarely changes due to an increase or decrease in the load or number of passengers. Therefore, a change in the total angle θ during traveling can be estimated as a change in the road surface angle θr. Therefore, the control unit 228R2 avoids generating a control signal instructing adjustment of the light axis when the total angle θ changes while the vehicle is traveling. The control unit 228R2 may generate a control signal instructing maintenance of the light axis position in response to a change in the total angle θ while the vehicle is traveling, and transmit the control signal from the transmission unit 228R3 to the leveling control unit 236. Whether the vehicle 300 is traveling can be determined, for example, by the vehicle speed obtained from the vehicle speed sensor 312. The "vehicle traveling" may refer to, for example, the period from when the detection value of the vehicle speed sensor 312 exceeds 0 until the detection value of the vehicle speed sensor 312 returns to 0. This "vehicle traveling" may be appropriately set by a designer based on experiments or simulations.

[0043] When the vehicle stops, the control unit 228R2 subtracts the reference value of the vehicle attitude angle θv read from the memory 228R4 from the current total angle θ detected by the acceleration sensor 316 to calculate the road surface angle θr when the vehicle is stopped. The road surface angle θr is then stored in the memory 228R4 as a new reference value for the road surface angle θr. The "vehicle stopped" refers to, for example, when the detection value of the acceleration sensor 316 stabilizes after the detection value of the vehicle speed sensor 312 becomes zero. The reason for determining the "time when the detection value of the acceleration sensor 316 stabilizes" is that it takes some time for the vehicle attitude to stabilize after the vehicle 300 stops, making it difficult to accurately detect the total angle θ when the vehicle attitude is not stable. This "time when the acceleration sensor 316 stabilizes" may refer to when the change in the detection value of the acceleration sensor 316 per unit time becomes equal to or less than a predetermined amount, or may refer to when a predetermined time has elapsed since the detection value of the vehicle speed sensor 312 became zero. The "vehicle stopped," "predetermined amount," and "predetermined time" may be appropriately set by a designer based on experiments or simulations.

[0044] On the other hand, while the vehicle 300 is stopped, the road surface angle θr rarely changes due to movement of the vehicle 300. Therefore, a change in the total angle θ while the vehicle is stopped can be estimated as a change in the vehicle attitude angle θv. Therefore, when the total angle θ changes while the vehicle is stopped, the control unit 228R2 generates a control signal instructing optical axis adjustment using the vehicle attitude angle θv obtained from the detection value of the acceleration sensor 316 and the reference value of the road surface angle θr read from the memory 228R4. Specifically, the control unit 228R2 repeatedly calculates the vehicle attitude angle θv at predetermined timings while the vehicle is stopped. The vehicle attitude angle θv is obtained by subtracting the reference value of the road surface angle θr recorded in the memory 228R4 from the current total angle θ received from the acceleration sensor 316. Then, when the difference between the calculated vehicle attitude angle θv and the reference value of the vehicle attitude angle θv stored in the memory 228R4 is equal to or greater than a predetermined amount, the control unit 228R2 generates a control signal based on the newly obtained vehicle attitude angle θv. This makes it possible to avoid frequent optical axis adjustment, thereby reducing the control burden on the control unit 228R2 and extending the life of the leveling actuator 226. The generated control signal is transmitted by the transmission unit 228R3 to the leveling control unit 236, which then performs optical axis adjustment based on the control signal. The calculated vehicle attitude angle θv is recorded in the memory 228R4 as a new reference value.

[0045] The "vehicle is stopped" is, for example, from when the detection value of the acceleration sensor 316 becomes stable until the vehicle starts moving, and this "vehicle starts moving" is, for example, when the detection value of the vehicle speed sensor 312 exceeds 0. The "vehicle is stopped" can be set appropriately by the designer based on experiments and simulations.

[0046] The control unit 228R2 records the output values ​​of the acceleration sensor 316 for a predetermined period of time during at least one of vehicle acceleration and deceleration, for example, when the vehicle starts or stops. The control unit 228R2 plots the recorded output values ​​on a coordinate system with the vehicle's vertical acceleration as the first axis and the vehicle's vertical acceleration as the second axis, and calculates a linear approximation equation continuously or at predetermined intervals using the least squares method. The control unit 228R2 then generates a control signal to instruct the lamp unit 10 to adjust the optical axis based on changes in the slope of the obtained linear approximation equation, thereby correcting the optical axis position. The control unit 228R2 also corrects the reference value of the vehicle attitude angle θv stored in the memory 228R4. For example, the control unit 228R2 compares the slope of the obtained linear approximation equation with the slope of the linear approximation equation obtained in the previous calculation, and if a change in the slope of the linear approximation equation is detected, performs correction processing based on the change in slope.

[0047] Also, for example, suppose the vehicle attitude angle θv stored in the memory 228R4 is p°, and the integrated value of the change in the slope of the linear approximation equation since the initial calculation is q°. Alternatively, suppose the change in the vehicle attitude angle θv during the previous vehicle stop, i.e., the difference between the vehicle attitude angle θv stored when the vehicle was stopped and the vehicle attitude angle θv stored when the vehicle started, is p°, and the difference in slope between the linear approximation equation calculated at the previous start and the linear approximation equation calculated at the current start is q°. In this case, the control unit 228R2 generates a control signal for adjusting the optical axis position by the error (pq)° of the vehicle attitude angle θv, and the transmission unit 228R3 transmits the control signal. The control unit 228R2 also corrects the reference value of the vehicle attitude angle θv stored in the memory 228R4 by (pq)°. This makes it possible to avoid a decrease in the accuracy of the auto-leveling control due to the accumulation of detection errors of the acceleration sensor 316 caused by repeatedly rewriting the reference values ​​of the road surface angle θr and the vehicle attitude angle θv as described above, or to reduce the decrease in accuracy of the auto-leveling control.

[0048] Alternatively, the reference values ​​of the optical axis position and the vehicle attitude angle θv may be corrected as follows. Specifically, if disturbances such as the tilt of the vehicle attitude due to acceleration / deceleration of the vehicle 300 or the tilt of the vehicle attitude due to cornering of the vehicle 300 cannot be eliminated, the change in the slope of the linear approximation equation may significantly deviate from the change in the vehicle attitude angle θv. In this case, even if the reference values ​​of the optical axis position and the vehicle attitude angle θv are corrected by the amount of the change in the slope of the linear approximation equation, they will still deviate from the actual vehicle attitude angle θv. Furthermore, since the slope of the linear approximation equation has changed, it is highly likely that the actual vehicle attitude angle θv deviates from the stored reference value. Therefore, even if the stored reference value is used to perform optical axis adjustment, it may not be possible to perform auto-leveling control with high accuracy. Therefore, when a change in the ratio or the slope of the linear approximation equation is detected, the control unit 228R2 corrects the optical axis position based on the change in slope by moving the optical axis position closer to the horizontal direction or the initial position and correcting the reference value of the vehicle attitude angle θv closer to 0°. This makes it possible to realize a fail-safe function that ensures visibility for the driver by bringing the optical axis position close to horizontal or the initial position even when it becomes impossible to accurately follow the optical axis position of the lighting unit 10 in response to changes in the vehicle attitude angle θv.

[0049] The control unit 228R2 may record the calculated vehicle attitude angle θv as a new reference value in the memory 228R4 when the difference between the calculated vehicle attitude angle θv and the reference value of the vehicle attitude angle θv stored in the memory 228R4 is equal to or greater than a predetermined amount. Similarly, the control unit 228R2 may record the calculated road surface angle θr as a new reference value in the memory 228R4 when the difference between the calculated road surface angle θr and the reference value of the road surface angle θr stored in the memory 228R4 is equal to or greater than a predetermined amount. This prevents the reference value of the road surface angle θr or the vehicle attitude angle θv from being frequently rewritten. The control unit 228R2 may also calculate the road surface angle θr when the total angle θ at the start of the vehicle 300 and the total angle θ at the stop are different. This reduces the control burden on the control unit 228R2.

[0050] In addition, the control unit 228R2 may record the detection values ​​of the acceleration sensor 316 during acceleration and deceleration from the start to the stop of the vehicle 300, calculate a linear approximation equation when the vehicle stops, etc., and perform the above-mentioned correction process.

[0051] 5 is a flowchart of the auto-leveling control of the vehicle lighting system according to the first embodiment. In the flowchart of FIG. 5, the processing procedure of each unit is indicated by a combination of S (the initial letter of Step), which means a step, and a number. Furthermore, if a determination process is performed in the process indicated by the combination of S and a number, and the determination result is affirmative, Y (the initial letter of Yes) is added, for example, to indicate (Y of S101). Conversely, if the determination result is negative, N (the initial letter of No) is added, for example, to indicate (N of S101). This flow is repeatedly executed at a predetermined timing by the illumination control unit 228R (control unit 228R2) when the ignition is turned on while an instruction to execute the auto-leveling control mode is issued by the light switch 304, and ends when the ignition is turned off.

[0052] First, the control unit 228R2 determines whether the vehicle is traveling (S101). If the vehicle is traveling (Y in S101), the control unit 228R2 determines whether the vehicle is accelerating or decelerating (S102). The acceleration or deceleration of the vehicle can be detected from the detection value of the acceleration sensor 316, whether the accelerator pedal or the brake pedal (neither of which is shown) is depressed, or the like. If the vehicle is accelerating or decelerating (Y in S102), the control unit 228R2 calculates a linear approximation equation from multiple output values ​​of the acceleration sensor 316, and compares the slope of the obtained linear approximation equation with the slope of the previously calculated linear approximation equation (S103). Then, the control unit 228R2 determines whether a change in the slope of the linear approximation equation has been detected (S104). If a change in the slope of the linear approximation equation is detected (Y in S104), the control unit 228R2 generates a control signal instructing optical axis adjustment to correct the optical axis position and correct the reference value of the vehicle attitude angle θv (S105). Thereafter, even if the total angle θ detected by the acceleration sensor 316 changes, the control unit 228R2 does not generate a control signal instructing optical axis adjustment, avoids optical axis adjustment (S106), and ends this routine. In addition, if the vehicle is not accelerating or decelerating (N in S102) or if a change in the slope of the linear approximation equation is not detected (N in S104), the control unit 228R2 also avoids optical axis adjustment (S106) and ends this routine.

[0053] If the vehicle is not moving (N in S101), the control unit 228R2 determines whether the vehicle is stopped (S107). If the vehicle is stopped (Y in S107), the control unit 228R2 calculates the road surface angle θr by subtracting the reference value of the vehicle attitude angle θv from the current total angle θ (S108), and records the calculated road surface angle θr in the memory 228R4 as a new reference value (S109). Then, the illumination control unit 228R avoids adjusting the optical axis (S106) and ends this routine.

[0054] If the vehicle is not stopped (N in S107), which means that the vehicle is stopped, the control unit 228R2 calculates the vehicle attitude angle θv by subtracting the reference value of the road surface angle θr from the current total angle θ (S110). Next, the control unit 228R2 determines whether the difference between the calculated vehicle attitude angle θv and the reference value of the vehicle attitude angle θv is equal to or greater than a predetermined amount (S111). If the difference is less than the predetermined amount (N in S111), the control unit 228R2 avoids adjusting the optical axis (S106) and ends this routine. If the difference is equal to or greater than the predetermined amount (Y in S111), the control unit 228R2 adjusts the optical axis position based on the calculated vehicle attitude angle θv (S112). Then, the control unit 228R2 records the calculated vehicle attitude angle θv as a reference value in the memory 228R4 (S113) and ends this routine.

[0055] For the left headlamp unit 210L, the illumination control unit 228L (control unit 228L2) executes similar control. Alternatively, one of the illumination control units 228L, 228R may calculate the vehicle attitude angle θv or the road surface angle θr, and the other may acquire the calculated vehicle attitude angle θv or the road surface angle θr and adjust the optical axis O.

[0056] Furthermore, while the vehicle is traveling, it can be assumed that the time during which the vehicle 300 maintains a constant speed is generally short, and that most of the time the vehicle is accelerating or decelerating. Therefore, step 102 of determining whether the vehicle 300 is accelerating or decelerating may be omitted.

[0057] As described above, the vehicle lighting system 200 according to this embodiment receives accelerations detected by the acceleration sensor 316 from which accelerations in the vehicle longitudinal direction and the vehicle vertical direction can be derived, and adjusts the optical axis of the lamp unit 10 based on the change in the ratio between the time change in the acceleration in the vehicle longitudinal direction and the time change in the acceleration in the vehicle vertical direction during at least one of acceleration and deceleration of the vehicle 300. In this way, the vehicle lighting system 200 according to this embodiment acquires information about the vehicle attitude angle θv using a new extraction method that acquires the change in the vehicle attitude angle θv from the change in the ratio between the time change in the acceleration in the vehicle longitudinal direction and the time change in the acceleration in the vehicle vertical direction during vehicle acceleration and deceleration. That is, the vehicle lighting system 200 acquires information about the vehicle attitude angle θv from the plot characteristics of the acceleration sensor 316. Therefore, the vehicle lighting system 200 according to this embodiment can provide a new technique for extracting information about the vehicle attitude angle θv from the total angle θ detected by the acceleration sensor 316.

[0058] Furthermore, when the total angle θ changes while the vehicle is traveling, the vehicle lighting system 200 according to this embodiment derives the road surface angle θr from the changed total angle θ and the reference value of the vehicle attitude angle θv, and rewrites the reference value of the road surface angle θr. When the total angle θ changes while the vehicle is stopped, the vehicle attitude angle θv is derived from the changed total angle θ and the reference value of the road surface angle θr, and rewrites the reference value of the vehicle attitude angle θv. When the vehicle 300 accelerates or decelerates, the vehicle lighting system 200 corrects the optical axis position of the lighting unit 10 using information about the vehicle attitude angle θv extracted by the above-described method. This allows for more accurate auto-leveling control using an acceleration sensor.

[0059] (Embodiment 2) A vehicle lighting system 200 according to the second embodiment derives a vehicle attitude angle θv from the ratio of the amount of change in acceleration in the vehicle's longitudinal direction over time to the amount of change in acceleration in the vehicle's vertical direction over time, and performs optical axis adjustment using the obtained vehicle attitude angle θv. This embodiment will be described below. Note that the main configuration of the vehicle lighting system 200 is the same as that of the first embodiment, and therefore the same components as those of the first embodiment are denoted by the same reference numerals, and their description and illustration will be omitted as appropriate.

[0060] The vehicular lighting system 200 according to this embodiment performs the following auto-leveling control using information about the vehicle attitude angle θv obtained by detecting the change in the ratio. That is, first, the vehicle 300 is placed in a reference state in which it is traveling on a horizontal plane, for example, at a vehicle manufacturer's manufacturing plant or a dealer's maintenance facility, and the vehicle 300 is accelerated or decelerated in this state. Then, as an initialization process, the control unit 228R2 receives acceleration from the acceleration sensor 316 and calculates the ratio between the amount of change in acceleration in the vehicle's longitudinal direction over time and the amount of change in acceleration in the vehicle's vertical direction over time during at least one of acceleration and deceleration of the vehicle 300. The control unit 228R2 records the obtained ratio in the memory 228R4 as a reference value.

[0061] In a situation where the vehicle 300 is actually being used, the control unit 228R2 calculates the ratio between the amount of change in acceleration in the vehicle's longitudinal direction over time and the amount of change in acceleration in the vehicle's vertical direction over time for the current vehicle, at least during acceleration and deceleration of the vehicle 300. Then, the control unit 228R2 obtains the vehicle attitude angle θv from the ratio for the current vehicle and a reference value of the ratio recorded in advance by the initialization process, and performs optical axis adjustment using the obtained vehicle attitude angle θv.

[0062] For example, in the initialization process, the control unit 228R2 plots the detection values ​​of the acceleration sensor 316 on a coordinate system with the acceleration in the vehicle's vertical direction as the first axis and the acceleration in the vehicle's vertical direction as the second axis, determines a reference linear approximation formula from the plotted points, and calculates the slope of the reference linear approximation formula as a reference value for the ratio. Also, in the actual usage situation of the vehicle, the control unit 228R2 records the output values ​​of the acceleration sensor 316 for a predetermined time, for example, when the vehicle starts or stops, plots the recorded output values ​​on the coordinate system, determines a linear approximation formula, and calculates the slope of the linear approximation formula as a ratio. Here, the angle (θ in FIG. 4) formed between the reference linear approximation formula and the linear approximation formula calculated under the actual usage situation is AB ) corresponds to the vehicle attitude angle θv. Therefore, the vehicle attitude angle θv can be obtained by comparing the slopes of the two linear approximation equations or the ratios described above.

[0063] As described above, in the vehicle lighting system 200 according to this embodiment, the vehicle attitude angle θv is obtained from the ratio when the vehicle 300 is on a horizontal plane and the ratio of the current vehicle, and the optical axis adjustment is performed. Therefore, in the case of auto-leveling control that rewrites the reference value of the road surface angle θr when the total angle θ changes while the vehicle is traveling, and rewrites the reference value of the vehicle attitude angle θv when the total angle θ changes while the vehicle is stopped, repeated rewriting of the reference value may increase adjustment errors, but in the case of the auto-leveling control of this embodiment, it is possible to adjust the optical axis position without increasing such adjustment errors.

[0064] (Embodiment 3) A vehicle lighting system 200 according to a third embodiment calculates a linear approximation equation using a pair of sensor output values, one during vehicle acceleration and the other during vehicle deceleration. This embodiment will be described below. Note that the main configuration of the vehicle lighting system 200 is the same as that of the first embodiment, and therefore the same components as those of the first embodiment are denoted by the same reference numerals, and their description and illustration will be omitted as appropriate.

[0065] 6 is a schematic diagram illustrating the auto-leveling control of the vehicle lighting system according to the third embodiment. As shown in FIG. 6, in the vehicle lighting system 200 according to this embodiment, the control unit 228R2 holds a first acceleration range P1(+) and a second acceleration range P2(+) predetermined for the acceleration of the vehicle 300, and a first deceleration range P1(-) and a second deceleration range P2(-) predetermined for the deceleration (negative acceleration) of the vehicle 300, as information about the acceleration range of the plot used to calculate the linear approximation equation (hereinafter, this information will be referred to as plot range information, as appropriate). The plot range information is configured with a pair of a range on the acceleration side and a range on the deceleration side. In this embodiment, the plot range information is configured with two pairs: a pair of the first acceleration range P1(+) and the first deceleration range P1(-), and a pair of the second acceleration range P2(+) and the second deceleration range P2(-). These acceleration ranges and deceleration ranges can be set based on the amount of change over time in the vehicle speed detected by the vehicle speed sensor 312, or the magnitude of the longitudinal component of the vehicle obtained from the detection value of the acceleration sensor 316. The plot range information is recorded in, for example, memory 228R4.

[0066] For example, from when the vehicle 300 starts to when it stops, the control unit 228R2 records the detection values ​​of the acceleration sensor 316 when the acceleration of the vehicle 300 is within the first acceleration range P1(+) or the second acceleration range P2(+) or when the deceleration is within the first deceleration range P1(-) or the second deceleration range P2(-). The control unit 228R2 then calculates a linear approximation equation by plotting the recorded detection values ​​on a coordinate system with the acceleration in the vehicle's vertical direction as the first axis and the acceleration in the vehicle's vertical direction as the second axis. For example, while the vehicle 300 is traveling, the control unit 228R2 calculates the linear approximation equation when the detection values ​​or plots of the acceleration sensor 316 in the first acceleration range P1(+), the first deceleration range P1(-), the second acceleration range P2(+), and the second deceleration range P2(-) are aligned.

[0067] Then, at any timing while the vehicle is traveling, the control unit 228R2 executes a process for correcting the optical axis O and the reference value of the vehicle attitude angle θv based on a change in the slope of the obtained linear approximation equation. Specifically, the control unit 228R2 derives an error component Δθe, which is the difference between the reference value of the vehicle attitude angle θv and the vehicle attitude angle θv derived from the slope of the linear approximation equation (the ratio of the amount of change over time in the vehicle's longitudinal direction and vertical direction). For example, the control unit 228R2 derives the vehicle attitude angle θv by calculating an integrated value of the change in the slope of the linear approximation equation from the initial calculation, and then calculates the error component Δθe from this vehicle attitude angle θv and the reference value of the vehicle attitude angle θv stored in the memory 228R4. Alternatively, similar to the second embodiment, the control unit 228R2 obtains the vehicle attitude angle θv from the slope between the pre-recorded reference straight-line approximation equation and the calculated straight-line approximation equation, and calculates the error component Δθe from this vehicle attitude angle θv and the reference value of the vehicle attitude angle θv stored in the memory 228R4.

[0068] Then, the control unit 228R2 corrects the reference value of the vehicle attitude angle θv so that the error component Δθe becomes smaller. At this time, if the absolute value of the obtained error component Δθe exceeds a predetermined threshold value θth (|Δθe|>θth), the control unit 228R2 corrects the reference value of the vehicle attitude angle θv by the correction value θc. Furthermore, the control unit 228R2 generates a control signal that adjusts the optical axis position by the correction value θc, thereby correcting the optical axis position. Note that the control unit 228R2 may perform the above-described correction process immediately after the vehicle 300 has stopped, for example.

[0069] The "predetermined threshold value θth" and the "correction value θc" are set according to the resolution of the optical axis control, the detection accuracy of the error component Δθe, or the detection resolution of the vehicle attitude angle θv using the change in the slope of the linear approximation equation. The predetermined threshold value θth is set within an error range that does not interfere with the optical axis control. The correction value θc is set according to, for example, an error caused by the smallest of the main error factors. Such an error factor may be, for example, a variation in vehicle attitude under the same load condition, i.e., a variation in suspension displacement.

[0070] Furthermore, the correction value θc is set to a value smaller than the predetermined threshold value θth. This allows the reference value of the vehicle attitude angle θv to gradually approach a more likely value even when the detection accuracy of the error component Δθe is low. For example, the resolution of angle detection using changes in the slope of the linear approximation equation is 0.04°, and the threshold value θth is set to 0.1° and the correction value θc is set to 0.03°. The "predetermined threshold value θth" and the "correction value θc" can be set appropriately based on experiments and simulations by a designer.

[0071] As described above, the plot range information is configured as a set of an acceleration side range and a deceleration side range. By combining the acceleration side range and the deceleration side range in this way, the error components of the vehicle attitude change caused by acceleration and the error components of the vehicle attitude change caused by deceleration can be canceled out, thereby enabling the linear approximation formula to be calculated with higher accuracy. Furthermore, the first acceleration range P1(+) and the first deceleration range P1(-) are set, for example, so that the ranges of the magnitude (absolute value) of the acceleration and deceleration are equal. This allows the error components of the vehicle attitude change caused by acceleration and the error components of the vehicle attitude change caused by deceleration to be canceled out more effectively, enabling the linear approximation formula to be calculated with higher accuracy.

[0072] In this embodiment, the first acceleration range P1(+) and the first deceleration range P1(-) are set to be a predetermined range of gradual acceleration / deceleration. In addition, the second acceleration range P2(+) and the second deceleration range P2(-) are set to be a predetermined range of rapid acceleration / deceleration that is greater in acceleration / deceleration than the first acceleration range P1(+) and the first deceleration range P1(-). In this embodiment, the plot range information is set to the range of gradual acceleration / deceleration and the range of rapid acceleration / deceleration, so that the linear approximation formula can be calculated with higher accuracy than when only one of the sets is used.

[0073] Alternatively, linear approximations may be calculated independently for the first acceleration range P1(+) and the first deceleration range P1(-) and the second acceleration range P2(+) and the second deceleration range P2(-), and correction processing may be performed based on the slope of each linear approximation. In this case, the weighting of the correction may be different for each set, such as by changing the magnitude of the correction value θc, depending on the frequency and accuracy of calculation for the set of the first acceleration range P1(+) and the first deceleration range P1(-) and the set of the second acceleration range P2(+) and the second deceleration range P2(-). Alternatively, correction processing may be performed based on the average slope of the linear approximations calculated independently. Furthermore, if plots are complete for the set of the first acceleration range P1(+) and the first deceleration range P1(-) and the set of the second acceleration range P2(+) and the second deceleration range P2(-) within a predetermined time, a linear approximation formula may be calculated using these plots, and if plots are not complete for all sets within the predetermined time, a linear approximation formula may be calculated using the plots of the set of plots that are complete at that time.

[0074] Furthermore, the plot range information may be composed of only one of the pair of the first acceleration range P1(+) and the first deceleration range P1(-) and the pair of the second acceleration range P2(+) and the second deceleration range P2(-). For example, the pair of the first acceleration range P1(+) and the first deceleration range P1(-), which is set as a range of gradual acceleration / deceleration, is more likely to include the detected values ​​of the acceleration sensor 316 during vehicle travel than the pair of the second acceleration range P2(+) and the second deceleration range P2(-), which is set as a range of rapid acceleration / deceleration. Therefore, the number of correction processes can be increased. The number of pairs of acceleration ranges and deceleration ranges included in the plot range information may be three or more.

[0075] Furthermore, the first acceleration range P1(+) and the first deceleration range P1(-) may be set to have the same range of acceleration / deceleration magnitudes, and the second acceleration range P2(+) and the second deceleration range P2(-) may also be set to have the same range of vehicle speeds. This allows the error components caused by acceleration and the error components caused by deceleration to cancel each other out more effectively, allowing for more accurate calculation of the linear approximation equation. The range widths of the acceleration range and the deceleration range, the magnitudes of the acceleration / deceleration, etc. can be set appropriately by the designer based on experiments and simulations.

[0076] 7 is a flowchart of the auto-leveling control of the vehicle lighting system according to embodiment 3. This flow is repeatedly executed at a predetermined timing by the illumination control unit 228R (control unit 228R2) when the ignition is turned on while an instruction to execute the auto-leveling control mode is being given by the light switch 304, for example, and ends when the ignition is turned off.

[0077] The control unit 228R2 determines whether the vehicle is traveling (S201). If the vehicle is traveling (Y in S201), the control unit 228R2 determines whether the detection value plots of the acceleration sensor 316 in the first acceleration range P1(+), the first deceleration range P1(-), the second acceleration range P2(+), and the second deceleration range P2(-) are aligned (S202). If the plots are not aligned (N in S202), the control unit 228R2 avoids optical axis adjustment (S203) and ends this routine. If the plots are aligned (Y in S202), the control unit 228R2 calculates a linear approximation equation (S204) and calculates an error component Δθe, which is the difference between the vehicle attitude angle θv derived from the slope of the linear approximation equation and the reference value of the vehicle attitude angle θv recorded in the memory 228R4 (S205).

[0078] The control unit 228R2 determines whether the absolute value of the error component Δθe exceeds the threshold value θth (S206). If the absolute value of the error component Δθe exceeds the threshold value θth (Y in S206), the control unit 228R2 corrects the reference value of the vehicle attitude angle θv and the optical axis position by the correction value θc (S207). Thereafter, the control unit 228R2 avoids optical axis adjustment with respect to a change in the total angle θ obtained from the detection value of the acceleration sensor 316 (S203) and ends this routine. If the absolute value of the error component Δθe is equal to or less than the threshold value θth (N in S206), the control unit 228R2 avoids optical axis adjustment without performing correction processing (S203) and ends this routine.

[0079] If the vehicle is not moving (N in S201), the control unit 228R2 determines whether the vehicle is stopped (S208). If the vehicle is stopped (Y in S208), the control unit 228R2 calculates the road surface angle θr (S209), records the calculated road surface angle θr as a new reference value (S210), avoids optical axis adjustment (S203), and ends this routine. If the vehicle is not stopped (N in S208), the control unit 228R2 calculates the vehicle attitude angle θv (S211), and determines whether the difference between the calculated vehicle attitude angle θv and the reference value of the vehicle attitude angle θv is equal to or greater than a predetermined amount (S212). If the difference is less than the predetermined amount (N in S212), the control unit 228R2 avoids optical axis adjustment (S203) and ends this routine. If the difference is equal to or greater than a predetermined amount (Y in S212), the control unit 228R2 adjusts the optical axis position based on the calculated vehicle attitude angle θv (S213), records the calculated vehicle attitude angle θv as a reference value (S214), and ends this routine.

[0080] As described above, in the vehicle lighting system 200 according to this embodiment, the control unit 228R2 calculates a linear approximation formula from a plot of the detection values ​​of the acceleration sensor 316 when the acceleration of the vehicle 300 is within a predetermined range and a plot of the detection values ​​of the acceleration sensor 316 when the deceleration of the vehicle 300 is within a predetermined range. Therefore, the error components of the vehicle attitude change caused by acceleration and the error components of the vehicle attitude change caused by deceleration can cancel each other out, so that it is possible to calculate a linear approximation formula with a slope closer to the vehicle attitude angle θv.

[0081] Furthermore, the control unit 228R2 executes the correction process when plots are obtained for the predetermined acceleration range and deceleration range. Therefore, for example, in a control that executes the correction process by calculating a linear approximation formula from the detection values ​​of the acceleration sensor 316 recorded from the start to the stop of the vehicle 300 immediately after the vehicle stops, if an error occurs in the calculation of the vehicle attitude angle θv and in the optical axis adjustment that are performed while the vehicle is stopped after the correction process, the vehicle 300 may continue to run with the error included, but this embodiment can avoid such a situation.

[0082] The vehicle lighting system 200 according to each embodiment is one aspect of the present invention. The vehicle lighting system 200 includes a lamp unit 10 with an adjustable optical axis, an acceleration sensor 316, and illumination control units 228L and 228R for controlling the lamp unit 10, and the illumination control units 228L and 228R perform the auto-leveling control described above.

[0083] Another aspect of the present invention is illumination control units 228L, 228R serving as control devices. The illumination control units 228L, 228R include receiving units 228L1, 228R1 for receiving acceleration in the longitudinal direction of the vehicle and the vertical direction of the vehicle from the acceleration sensor 316, control units 228L2, 228R2 for executing the above-mentioned auto-leveling control, and transmitting units 228L3, 228R3 for transmitting control signals generated by the control units 228L2, 228R2 to the leveling control unit 236. The illumination control unit 228 in the vehicular lighting system 200 corresponds to a control unit in a broad sense, and the control units 228L2, 228R2 in the illumination control unit 228 correspond to a control unit in a narrow sense.

[0084] Yet another aspect of the present invention is a method for controlling a vehicle lamp, which adjusts the optical axis of a lamp unit 10 based on a change in the ratio between the amount of change in acceleration in the vehicle's longitudinal direction and the amount of change in acceleration in the vehicle's vertical direction during at least one of acceleration and deceleration of the vehicle 300.

[0085] The present invention is not limited to the above-described embodiments, but rather may be combined with other embodiments or modified, such as by various design changes, based on the knowledge of a person skilled in the art. Such combined or modified embodiments are also included within the scope of the present invention. New embodiments resulting from the combination of the above-described embodiments with each other, or the combination of the above-described embodiments with the following modifications, combine the effects of the combined embodiments and modifications.

[0086] In each of the above-described embodiments, the illumination control unit 228 may control the leveling actuator 226 as an optical axis adjustment unit without using the leveling control unit 236. That is, the illumination control unit 228 may function as the leveling control unit 236. Furthermore, the generation of a control signal that instructs optical axis adjustment in each of the above-described embodiments may be performed by the vehicle control unit 302. That is, the vehicle control unit 302 may constitute a control device that executes auto-leveling control. In this case, the illumination control unit 228 controls the driving of the leveling actuator 226 based on an instruction from the vehicle control unit 302.

[0087] In the first embodiment, similarly to the third embodiment, a correction process using a predetermined threshold value θth and a correction value θc may be executed. [Explanation of symbols]

[0088] 10 Lighting unit, 200 Vehicle lighting system, 228, 228L, 228R Illumination control unit, 228L1, 228R1 Receiving unit, 228L2, 228R2 Control unit, 228L3, 228R3 Transmitting unit, 300 Vehicle, 316 Acceleration sensor, O Optical axis, θ Total angle, θr Road surface angle, θv Vehicle attitude angle, α Motion acceleration vector, β Resultant acceleration vector.

Claims

1. When a ratio between a change in acceleration in the longitudinal direction of the vehicle and a change in acceleration in the vertical direction of the vehicle detected by one acceleration sensor while the vehicle is traveling changes, a control signal is output to change the illumination direction of the vehicle lamp in the vertical direction of the vehicle. A control device for vehicle lighting fixtures.

2. Holds information about vehicle attitude angles, When a ratio between the amount of change in acceleration in the vehicle's longitudinal direction and the amount of change in acceleration in the vehicle's vertical direction detected by one acceleration sensor while the vehicle is traveling changes, the information stored therein changes before and after the change in the ratio. A control device for vehicle lighting fixtures.

3. Holds information about vehicle attitude angles, updating the information held when a ratio between the amount of change in acceleration in the vehicle's longitudinal direction and the amount of change in acceleration in the vehicle's vertical direction detected by one acceleration sensor while the vehicle is traveling changes; A control device for vehicle lighting fixtures.

4. When a ratio between the amount of change in acceleration in the vehicle's longitudinal direction and the amount of change in acceleration in the vehicle's vertical direction detected by one acceleration sensor changes while the vehicle is traveling, information on the vehicle attitude angle corresponding to the ratio after the change is stored. A control device for vehicle lighting fixtures.

Images