Control device of vehicle lamp

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, an auto-leveling control is known that automatically adjusts the optical axis position of a vehicle headlamp according to the inclination angle in the pitch direction of the vehicle to change the irradiation direction. In general, in the auto-leveling control, a vehicle height sensor is used as a vehicle inclination detection device, and the optical axis position of the headlamp is adjusted based on the pitch angle of the vehicle detected by the vehicle height sensor. In contrast, Patent Document 1 discloses a configuration using a gravity sensor as the inclination detection device. Patent Document 2 discloses a configuration using a three-dimensional gyro sensor that detects the inclination angle relative to a horizontal plane as the inclination detection device. Patent Document 3 discloses a configuration using an inclinometer that detects the inclination angle of the vehicle relative to the gravity direction as the inclination detection device. Patent Document 4 discloses a configuration using an acceleration sensor that detects gravitational acceleration as the inclination detection device.

[0003] When 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] JP 2000-085459 A [Patent Document 2] JP 2004-314856 A [Patent Document 3] JP 2001-341578 A [Patent Document 4] JP 2009-126268 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the auto-leveling control using an acceleration sensor, the inclination angle detected by the acceleration sensor is the inclination angle of the vehicle relative to the horizontal plane, including the inclination angle of the road surface relative to the horizontal plane and the inclination angle of the vehicle relative to the road surface. On the other hand, the inclination angle of the vehicle required for the auto-leveling control is the inclination angle of the vehicle relative to the road surface. Therefore, in the auto-leveling control using an acceleration sensor, it is necessary to extract information about the inclination angle of the vehicle relative to the road surface from the inclination angle of the vehicle relative to the horizontal plane obtained by the acceleration sensor. In response to this, the present inventors have come up with a new method for extracting information about the inclination angle of the vehicle relative to the road surface from the inclination angle of the vehicle relative to the horizontal plane obtained from the detection value of the acceleration sensor.

[0006] The present invention has been 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 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 being characterized in comprising: a receiving unit for receiving acceleration detected by an acceleration sensor from which acceleration in the vehicle longitudinal direction and in the vehicle vertical direction can be derived; a control unit for generating a control signal that instructs adjustment of the beam axis of the vehicle lamp based on a change in the ratio between the amount of change in acceleration in the vehicle longitudinal direction and the amount of change in acceleration in the vehicle vertical direction during at least one of acceleration and deceleration of the vehicle; and a transmitting unit for transmitting the control signal to a beam axis adjustment unit of the vehicle lamp.

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

[0009] In the above aspect, the control unit may plot the detection values ​​of the acceleration sensor over time at least when the vehicle is accelerating and / or decelerating on a coordinate system in which the acceleration in the vehicle's fore-and-aft direction is set as the first axis and the acceleration in the vehicle's up-and-down direction is set as the second axis, and may take the slope of a line or vector obtained from at least two points as a ratio.

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

[0011] Furthermore, in the above aspect, when the inclination angle of the vehicle with respect to the horizontal plane is referred to as 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 traveling, avoids generating a control signal or generates a control signal instructing to maintain the optical axis position, 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 optical axis position 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 it is possible to reduce the decrease in 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 a correction value smaller than the predetermined threshold.

[0013] In the above embodiment, the control unit may obtain the inclination angle of the vehicle with respect to the road surface from the ratio at least one of the acceleration and deceleration of the vehicle on the horizontal plane 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 embodiment, 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 in which the reference value of the road surface angle θr is rewritten when the total angle θ changes while the vehicle is traveling, and the reference value of the vehicle attitude angle θv is rewritten when the total angle θ changes while the vehicle is stopped.

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

[0015] Another aspect of the present invention is a vehicle lighting system comprising a vehicle lighting device capable of adjusting a light axis, an acceleration sensor, and a control unit for controlling the vehicle lighting device, wherein the control unit receives acceleration detected by the acceleration sensor from which acceleration in the vehicle fore-aft direction and in the vehicle up-down direction can be derived, and adjusts the light axis of the vehicle lighting device based on a change in the ratio between the amount of change in acceleration in the vehicle fore-aft direction and the amount of change in acceleration in the vehicle up-down 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, the method being for adjusting the optical axis of the vehicle lamp using an acceleration sensor, 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 fore-and-aft direction of the vehicle and the amount of change in acceleration in the up-and-down 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 detection value of the acceleration sensor in auto-leveling control of a vehicle lamp using an acceleration sensor. Effect of the Invention

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

[0019] [Figure 1] 1 is a schematic vertical sectional view illustrating an internal structure of a vehicle lighting system according to a first embodiment. [Diagram 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. [Diagram 3] 3(A) and 3(B) are schematic diagrams for explaining the relationship between the direction of the vehicle motion acceleration vector and the vehicle attitude angle. [Figure 4] 4 is a graph showing the relationship between the acceleration in the vehicle longitudinal direction and the acceleration in the vehicle vertical direction. [Diagram 5] 4 is a flowchart of auto-leveling control of the vehicle lighting system according to the first embodiment. [Figure 6] FIG. 11 is a schematic diagram for explaining auto-leveling control of a vehicle lighting system according to a third embodiment. [Figure 7]11 is a flowchart of auto-leveling control of a vehicle lighting system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, the embodiments are illustrative rather than limiting 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 having a symmetrical structure, so the structure of the right headlamp unit 210R will be described below, and the description of the left headlamp unit will be omitted as appropriate. When describing each member of the left headlamp unit, for convenience of explanation, the same reference numerals as the corresponding members of the headlamp unit 210R will be used for each member.

[0022] The headlamp unit 210R has a lamp body 212 with an opening on the vehicle front side, and a light-transmitting 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 light-transmitting cover 214 form a lamp chamber 216. The lamp chamber 216 houses a lamp unit 10 (vehicle lamp) that irradiates light forward of the vehicle.

[0023] A lamp bracket 218 having a pivot mechanism 218a which is the center of the vertical and horizontal swing of the lamp unit 10 is formed in a part of the lamp unit 10. The lamp bracket 218 is screwed 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 in the lamp chamber 216 determined by the adjustment state of the aiming adjustment screw 220, and can change its posture to a forward or backward tilt posture, etc., with the pivot mechanism 218a as the center based on that position. In addition, a rotation shaft 222a of a swivel actuator 222 for forming a curved road variable light distribution headlamp that illuminates the traveling direction when driving on a curved road, etc. is fixed to the underside of the lamp unit 10. 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 composed of, for example, a motor that expands and contracts a rod 226a in the directions of the arrows M and N. When the rod 226a expands in the direction of the arrow M, the lamp unit 10 swings around the pivot mechanism 218a so as to assume a rearward tilting position. Conversely, when the rod 226a contracts in the direction of the arrow N, the lamp unit 10 swings 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 performed to orient the pitch angle of the optical axis O, that is, the vertical angle of the optical axis O, upward. When the lamp unit 10 assumes a forward tilting position, a leveling adjustment can be performed to orient the pitch angle of the optical axis O downward.

[0025] An illumination control unit 228 (control unit, control device) that controls the turning on and 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, and the like. The illumination control unit 228R may be provided outside the headlamp unit 210R.

[0026] The lamp unit 10 may include an aiming adjustment mechanism. For example, an aiming pivot mechanism (not shown) that serves as a swing center during aiming adjustment is disposed at a connection portion between the rod 226a of the leveling actuator 226 and the unit bracket 224. The above-mentioned aiming adjustment screws 220 are disposed at intervals in the vehicle width direction on the lamp bracket 218. 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, and the optical axis O can be adjusted up, down, left, and right. This aiming adjustment is performed, for example, when the vehicle is shipped, when a vehicle inspection is performed, or when the headlamp unit 210R is replaced. The headlamp unit 210R is adjusted to a position determined by design, and the formation control of the light distribution pattern and the adjustment control of the optical axis position are performed based on this position.

[0027] The lamp unit 10 includes a shade mechanism 18 including a rotating shade 12, a bulb 14 as a light source, a lamp housing 17 supporting a reflector 16 on an inner wall, and a projection lens 20. For the bulb 14, for example, an incandescent bulb, a halogen lamp, a discharge bulb, an LED, or the like can be used. In this embodiment, an example in which the bulb 14 is a halogen lamp is shown. The reflector 16 reflects the light emitted from the bulb 14. Then, a part of the light from the bulb 14 and the light reflected by the reflector 16 are guided to the projection lens 20 via the rotating shade 12. The rotating shade 12 is a cylindrical member that can rotate around a rotating shaft 12a, and includes a cutout part cut out in the axial direction and a plurality of shade plates (not shown). Either the cutout part 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 the 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 front-rear 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 aspheric lens having a convex front surface and a flat rear surface, and projects a 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 may be a reflective lighting unit not having the projection lens 20.

[0029] 2 is a functional block diagram for explaining 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 explained and the explanation of the headlamp unit 210L side will be omitted.

[0030] The irradiation 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 irradiation control unit 228R controls the power supply circuit 230 based on information obtained from the vehicle control unit 302 mounted on the vehicle 300, and executes lighting control of the bulb 14. The irradiation control unit 228R also controls the variable shade control unit 232, the swivel control unit 234, and the 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 information and information stored in the memory 228R4 as necessary. Then, the control signals are transmitted by the transmitting unit 228R3 to the power supply circuit 230 of the lamp unit 10, the variable shade control unit 232, the swivel control unit 234, the leveling control unit 236, and the like. 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 rotating shaft 12a of the rotating shade 12 to move a desired shade plate or cutout portion onto the optical axis O. The swivel control unit 234 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 and right direction). For example, when turning such as traveling on a curved road or turning right or left, the optical axis O of the lighting unit 10 is oriented in the direction of travel from now on. The leveling control unit 236 controls the leveling actuator 226 to adjust the optical axis O of the lighting unit 10 in the vehicle up and down direction (pitch angle direction). For example, the attitude of the lighting unit 10 is adjusted according to the forward or backward tilt of the vehicle attitude when the load amount increases or decreases or the number of passengers increases or decreases, and the reach distance of the forward illumination light is adjusted to an optimal distance. 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 irradiation control units 228L, 228R control the motor 238 via the variable shade control unit 232 in response to the operation of the light switch 304 to determine the light distribution pattern formed by the lamp unit 10. 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 formation control of the light distribution pattern is executed when the automatic formation control of the light distribution pattern is instructed by the light switch 304, for example.

[0033] In order to detect objects such as a preceding vehicle or an oncoming vehicle, a camera 306 such as a stereo camera is connected to the vehicle control unit 302. 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 result is provided to the vehicle control unit 302. The vehicle control unit 302 can also obtain 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 allows the illumination control units 228L, 228R to select a light distribution pattern to be formed in accordance with the running state and attitude of the vehicle 300, and to change the direction of the optical axis O.

[0034] Next, the auto-leveling control by the vehicle lighting system 200 having the above-mentioned 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 described later does not change, and Figure 3(B) shows a state in which the vehicle attitude angle θv changes. In addition, in Figures 3(A) and 3(B), the motion acceleration vector α and the resultant acceleration vector β generated when the vehicle 300 moves forward are indicated by solid arrows, and the motion acceleration vector α and the resultant acceleration vector β generated 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 there is luggage in the luggage compartment at the rear of the vehicle or passengers in the rear seats, the vehicle posture is tilted backward, and when the luggage is removed or the passengers in the rear seats get off, the vehicle posture is tilted forward from the backward posture. The illumination direction of the lamp unit 10 also changes up and down in response to the posture state of the vehicle 300, and the forward illumination distance becomes longer or shorter. 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 according to the vehicle posture. In this way, by implementing auto-leveling control that performs leveling adjustment 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 if the vehicle posture changes according to 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 each other. The acceleration sensor 316 is attached to the vehicle 300 so that the X-axis of the sensor is along the front-rear axis of the vehicle 300, the Y-axis of the sensor is along the left-right axis of the vehicle 300, and the Z-axis of the sensor is along the up-down axis of the vehicle 300. The acceleration sensor 316 detects the inclination of the vehicle 300 with respect to the 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 (total angle) of the vehicle with respect to the horizontal plane, including a road surface angle θr that is the inclination angle (first angle) of the road surface with respect to the horizontal plane, and a vehicle attitude angle θv that is the inclination angle (second angle) of the vehicle with respect to the road surface. In addition, the acceleration sensor 316 detects a resultant acceleration vector β, which is a resultant of the gravitational acceleration vector G and the motion acceleration vector α generated by the movement of the vehicle 300, when the vehicle 300 is traveling, and outputs the numerical values ​​of each axis 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 angles in the up-down direction of the X-axis, in other words, angles in the pitch direction of the vehicle 300. In the following description, the component of the acceleration sensor 316 in the Y-axis direction, that is, the angle in the roll direction of the vehicle 300, is not considered. The acceleration sensor 316 may be attached to the vehicle 300 in any orientation. In this case, the numerical values ​​of each component of the X-axis, Y-axis, and Z-axis output from the acceleration sensor 316 are converted into components of the front-rear axis, left-right axis, and up-down axis of the vehicle by the illumination control unit 228R.

[0037] The auto-leveling control is intended to absorb the change in the forward illumination distance of the vehicle lamp accompanying the change in the inclination angle in the pitch direction of the vehicle, and to maintain the forward reach distance of the illumination light at an optimum level. Therefore, the vehicle inclination angle required for the auto-leveling control is the vehicle attitude angle θv. That is, it is desired to control the light axis position of the lamp unit 10 to be adjusted when the vehicle attitude angle θv changes, and to maintain the light 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, the vehicle 300 moves parallel to the road surface. Therefore, the motion acceleration vector α is a vector parallel to the road surface regardless of the vehicle attitude angle θv. Also, as shown in FIG. 3A, when the vehicle attitude angle θv of the vehicle 300 is 0°, the X-axis of the acceleration sensor 316 (or the front-rear axis of the vehicle 300) is theoretically parallel to the road surface, so the motion acceleration vector α is a vector parallel to the X-axis of the acceleration sensor 316. Therefore, when the magnitude of the motion acceleration vector α changes due to the acceleration or deceleration of the vehicle, the trajectory of the tip of the resultant acceleration vector β detected by the acceleration sensor 316 is a straight line parallel to the X-axis. On the other hand, as shown in FIG. 3B, when the vehicle attitude angle θv is not 0°, the X-axis of the acceleration sensor 316 deviates obliquely from the road surface, so the motion acceleration vector α is a vector extending obliquely to the X-axis of the acceleration sensor 316. Therefore, when the magnitude of the motion acceleration vector α changes due to acceleration or deceleration of the vehicle, the trajectory of the tip of the resultant acceleration vector β becomes 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 between the amount of change in acceleration in the vehicle longitudinal direction and the amount of change in acceleration in the vehicle vertical direction during at least one of acceleration and deceleration of the vehicle 300. For example, the illumination control unit 228R plots the detection value 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) as shown in FIG. 4. At point t A1 ~t An is the time from t1 to t n is the detection value of the acceleration sensor 316 at point t B1 ~t Bn is the time from t1 to t nThe acceleration sensor 316 detects the acceleration at the point t. Then, the slope of a 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 a line or vector obtained from the plotted points t A1 ~t An ,t B1 ~t Bn Linear approximations A and B are found using the least squares method or the like, and the slopes of the linear approximations A and B are calculated as a ratio.

[0040] When the vehicle attitude angle θv is 0°, a linear approximation equation A parallel to the x-axis is obtained from the detection value of the acceleration sensor 316. That is, the inclination of the linear approximation equation A is 0. On the other hand, when the vehicle attitude angle θv is not 0°, a linear approximation equation B having a inclination according to the vehicle attitude angle θv is obtained from the detection value of the acceleration sensor 316. Therefore, by measuring the change in the ratio of the amount of time change in the acceleration in the vehicle longitudinal direction and the vehicle vertical direction during acceleration and deceleration of the vehicle 300, the change in the vehicle attitude angle θv can be known from the detection value of the acceleration sensor 316 as information on the vehicle attitude angle θv. Then, by using the obtained change information of the vehicle attitude angle θv, more accurate auto-leveling control can be realized.

[0041] The vehicle lighting system 200 according to the present embodiment executes the following auto-leveling control using information on 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 and set as a reference state, for example, at a vehicle manufacturer's manufacturing plant or a dealer's maintenance plant. In the reference state, the vehicle 300 is set as a state in which one person is seated in the driver's seat or an empty vehicle state. Then, an initialization signal is transmitted to the illumination control unit 228R by operating a switch of an initialization processing device at the plant or by communication of a CAN (Controller Area Network) system that connects 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 the receiving unit 228R1 and sent to the control unit 228R2. When the control unit 228R2 receives the initialization signal, the control unit 228R2 performs an initial aiming adjustment using the output value of the acceleration sensor 316 received by the receiving unit 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] During vehicle travel, the vehicle attitude angle θv rarely changes due to an increase or decrease in the load or number of passengers, so the change in the total angle θ during travel can be estimated as the change in the road surface angle θr. Therefore, when the total angle θ changes during vehicle travel, the control unit 228R2 avoids generating a control signal instructing adjustment of the optical axis. The control unit 228R2 may generate a control signal instructing maintenance of the optical axis position in response to a change in the total angle θ during vehicle travel, and transmit the control signal from the transmission unit 228R3 to the leveling control unit 236. The fact that the vehicle 300 is traveling can be determined, for example, by the vehicle speed obtained from the vehicle speed sensor 312. The aforementioned "vehicle travel" refers to, for example, the period from when the detection value of the vehicle speed sensor 312 exceeds 0 to when the detection value of the vehicle speed sensor 312 becomes 0. This "vehicle travel" can be appropriately set based on experiments and simulations by a designer.

[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 stops. Then, this road surface angle θr is recorded in the memory 228R4 as a new reference value of the road surface angle θr. The "when the vehicle stops" is, for example, when the detection value of the acceleration sensor 316 becomes stable after the detection value of the vehicle speed sensor 312 becomes 0. The reason why the detection value of the acceleration sensor 316 becomes stable is because it takes some time for the vehicle attitude to become stable after the vehicle 300 stops, and it is difficult to detect an accurate total angle θ when the vehicle attitude is not stable. This "when it becomes stable" may be when the change amount per unit time of the detection value of the acceleration sensor 316 becomes equal to or less than a predetermined amount, or may be when a predetermined time has passed since the detection value of the vehicle speed sensor 312 became 0. The "when the vehicle stops", "predetermined amount", and "predetermined time" can be appropriately set by a designer based on experiments and simulations.

[0044] On the other hand, while the vehicle is stopped, the vehicle 300 rarely moves and the road surface angle θr changes, so the change in the total angle θ while the vehicle is stopped can be estimated as the 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 for instructing the adjustment of the optical axis 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 a predetermined timing 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, the control unit 228R2 generates a control signal based on the newly obtained vehicle attitude angle θv when the difference between the calculated vehicle attitude angle θv and the reference value of the vehicle attitude angle θv held in the memory 228R4 is equal to or greater than a predetermined amount. 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, and optical axis adjustment is performed 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 appropriately set by a designer based on experiments and simulations.

[0046] The control unit 228R2 records the output value of the acceleration sensor 316 during at least one of the acceleration and deceleration of the vehicle, for example, for a predetermined time when the vehicle starts or stops. The control unit 228R2 plots the recorded output value on a coordinate system with the acceleration in the vehicle vertical direction as the first axis and the acceleration in the vehicle vertical direction as the second axis, and calculates a linear approximation equation continuously or at predetermined time intervals using the least squares method. Then, the control unit 228R2 generates a control signal that instructs the adjustment of the optical axis of the lighting unit 10 based on a change in the slope of the obtained linear approximation equation, thereby correcting the optical axis position. In addition, the control unit 228R2 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 when a change in the slope of the linear approximation equation is detected, executes a correction process based on the change in the slope.

[0047] Also, for example, it is assumed that the vehicle attitude angle θv held in the memory 228R4 is p°, and the integrated value of the change in the slope of the linear approximation equation from the first calculation is q°. Alternatively, it is assumed that the change amount of the vehicle attitude angle θv during the previous vehicle stop, that is, the difference between the vehicle attitude angle θv held when the vehicle stopped and the vehicle attitude angle θv held when the vehicle started, is p°, and the difference in the 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. Also, the control unit 228R2 corrects the reference value of the vehicle attitude angle θv held in the memory 228R4 by (pq)°. This makes it possible to avoid a decrease in the accuracy of the auto-leveling control caused by the accumulation of detection errors of the acceleration sensor 316 due to the repeated rewriting of the reference values ​​of the road surface angle θr and the vehicle attitude angle θv as described above. Alternatively, it is possible to reduce the decrease in accuracy of the auto-leveling control.

[0048] Alternatively, the method of correcting the reference values ​​of the optical axis position and the vehicle attitude angle θv may be as follows. That is, if disturbances such as the inclination of the vehicle attitude caused by the acceleration / deceleration of the vehicle 300 or the inclination of the vehicle attitude caused by the turning of the vehicle 300 cannot be excluded, the amount of change in the inclination of the linear approximation equation may be significantly different from the amount of 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 change in the inclination of the linear approximation equation, the angle will deviate from the actual vehicle attitude angle θv. In addition, since the inclination of the linear approximation equation has changed, it is highly likely that the actual vehicle attitude angle θv deviates from the held reference value, so that even if the optical axis adjustment is performed using the held reference value, it may not be possible to perform auto-leveling control with high accuracy. Therefore, when a change in the ratio or the inclination of the linear approximation equation is detected, the control unit 228R2 performs correction control of the optical axis position based on the change in the inclination by correcting the optical axis position so that the optical axis position approaches the horizontal direction or the initial position and the reference value of the vehicle attitude angle θv approaches 0°. As a result, even if 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, a fail-safe function can be realized that ensures visibility for the driver by bringing the optical axis position closer to the horizontal or initial position.

[0049] In addition, the control unit 228R2 may record the calculated vehicle attitude angle θv in the memory 228R4 as a new reference value when the difference between the calculated vehicle attitude angle θv and the reference value of the vehicle attitude angle θv held 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 in the memory 228R4 as a new reference value when the difference between the calculated road surface angle θr and the reference value of the road surface angle θr recorded in the memory 228R4 is equal to or greater than a predetermined amount. This makes it possible to avoid the reference value of the road surface angle θr or the vehicle attitude angle θv being frequently rewritten. In addition, the control unit 228R2 may 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 makes it possible to reduce the control burden of 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 one start to one stop of the vehicle 300, and calculate a linear approximation equation when the vehicle stops, etc., to perform the above-mentioned correction process.

[0051] FIG. 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 displayed by a combination of S (initial letter of Step) meaning a step and a number. In addition, in the process displayed by the combination of S and a number, if some judgment process is performed and the judgment result is positive, Y (initial letter of Yes) is added and displayed as (Y of S101), for example, and conversely, if the judgment result is negative, N (initial letter of No) is added and displayed as (N of S101), for example. This flow is repeatedly executed at a predetermined timing by the illumination control unit 228R (control unit 228R2) when the ignition is turned on in a state in which the execution instruction of the auto-leveling control mode is given 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, the presence or absence of depression of the accelerator pedal or the brake pedal (both not shown), etc. 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 linear approximation equation calculated previously (S103). Then, the control unit 228R2 determines whether a change in the slope of the linear approximation equation has been detected (S104). When a change in the slope of the linear approximation equation is detected (Y in S104), the control unit 228R2 generates a control signal to instruct the optical axis adjustment to correct the optical axis position and correct the reference value of the vehicle attitude angle θv (S105). After that, even if the total angle θ detected by the acceleration sensor 316 changes, the control unit 228R2 does not generate a control signal to instruct the optical axis adjustment, avoids the optical axis adjustment (S106), and ends this routine. In addition, when the vehicle is not accelerating or decelerating (N in S102) and when a change in the slope of the linear approximation equation is not detected (N in S104), the control unit 228R2 also avoids the 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 subtracts the reference value of the vehicle attitude angle θv from the current total angle θ to calculate the road surface angle θr (S108), and records the calculated road surface angle θr as a new reference value in the memory 228R4 (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), this means that the vehicle is stopped, so 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 obtain the calculated vehicle attitude angle θv or the road surface angle θr and adjust the optical axis O.

[0056] In addition, while the vehicle is traveling, it can be estimated that the time during which the vehicle 300 maintains a constant speed is generally short, and 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 the present embodiment receives accelerations detected by the acceleration sensor 316 from which accelerations in the vehicle longitudinal direction and 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 amount of time change in the acceleration in the vehicle longitudinal direction and the amount of 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 the present 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 amount of time change in the acceleration in the vehicle longitudinal direction and the amount of 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, according to the vehicle lighting system 200 according to the present embodiment, a new technique for extracting information about the vehicle attitude angle θv from the total angle θ detected by the acceleration sensor 316 can be provided.

[0058] In addition, 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 when the total angle θ changes while the vehicle is traveling, and rewrites the reference value of the road surface angle θr that is held, and derives the vehicle attitude angle θv from the changed total angle θ and the reference value of the road surface angle θr when the total angle θ changes while the vehicle is stopped, and rewrites the reference value of the vehicle attitude angle θv that is held. Then, the vehicle lighting system 200 corrects the optical axis position of the lighting unit 10 by using the information about the vehicle attitude angle θv extracted by the above-mentioned method when the vehicle 300 accelerates or decelerates. Therefore, the auto-leveling control using the acceleration sensor can be performed with higher accuracy.

[0059] (Embodiment 2) The vehicle lighting system 200 according to the second embodiment derives a vehicle attitude angle θv from the ratio between the amount of change in acceleration in the vehicle longitudinal direction over time and the amount of change in acceleration in the vehicle vertical direction over time, and adjusts the optical axis using the obtained vehicle attitude angle θv. Hereinafter, this embodiment will be described. Note that the main configuration of the vehicle lighting system 200 is the same as that of the first embodiment, so the same reference numerals are used for the same configuration as that of the first embodiment, and the description and illustration thereof will be omitted as appropriate.

[0060] The vehicle lighting system 200 according to this embodiment executes 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 set to a reference state in which the vehicle 300 runs on a horizontal plane, for example, at a vehicle manufacturer's manufacturing plant or a dealer's maintenance plant, and the vehicle 300 is accelerated or decelerated in that 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 time change in acceleration in the vehicle's longitudinal direction and the amount of time change in acceleration in the vehicle's vertical direction during at least one of the 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 used, the control unit 228R2 calculates the ratio between the amount of change in acceleration in the vehicle longitudinal direction and the amount of change in acceleration in the vehicle vertical direction at the current vehicle, at least one of when the vehicle 300 is accelerating and decelerating. Then, the control unit 228R2 obtains the vehicle attitude angle θv from the ratio of the current vehicle and a reference value of the ratio recorded in advance by the initialization process, and performs the 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, obtains a reference straight-line approximation equation from the plotted points, and calculates the slope of the reference straight-line approximation equation as a reference value of the ratio. Also, in the actual usage conditions 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 to obtain a straight-line approximation equation, and calculates the slope of the straight-line approximation equation as a ratio. Here, the angle (θ in FIG. 4) between the reference straight-line approximation equation and the straight-line approximation equation calculated under the actual usage conditions is calculated as the slope of the straight-line approximation equation. 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 expressions or the ratio 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 in which the reference value of the road surface angle θr is rewritten when the total angle θ changes while the vehicle is traveling, and the reference value of the vehicle attitude angle θv is rewritten when the total angle θ changes while the vehicle is stopped, there is a possibility that an adjustment error will increase due to repeated rewriting of the reference value, but in the case of the auto-leveling control of this embodiment, the optical axis position can be adjusted without incurring such an increase in the adjustment error.

[0064] (Embodiment 3) The vehicle lighting system 200 according to the third embodiment calculates a linear approximation equation using a pair of sensor output values, one for when the vehicle accelerates and the other for when the vehicle decelerates. Hereinafter, this embodiment will be described. Note that the main configuration of the vehicle lighting system 200 is the same as that of the first embodiment, so the same reference numerals are used for the same configuration as that of the first embodiment, and the description and illustration thereof will be omitted as appropriate.

[0065] FIG. 6 is a schematic diagram for explaining 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(+) that are predetermined for the acceleration of the vehicle 300, and a first deceleration range P1(-) and a second deceleration range P2(-) that are predetermined for the deceleration (negative acceleration) of the vehicle 300, as information on the acceleration range of the plot used in the calculation of the linear approximation formula (hereinafter, this information will be appropriately referred to as plot range information). This plot range information is configured as a set of a range on the acceleration side and a range on the deceleration side. In this embodiment, the plot range information is configured as two sets, a set of the first acceleration range P1(+) and the first deceleration range P1(-) and a set 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 vehicle longitudinal component obtained from the detection value of the acceleration sensor 316. The plot range information is recorded in, for example, the memory 228R4.

[0066] For example, 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(-) during the period from when the vehicle 300 starts to when it stops, the control unit 228R2 records the detection value of the acceleration sensor 316. Then, the control unit 228R2 calculates a linear approximation equation by plotting the recorded detection value on a coordinate system in which the acceleration in the vehicle vertical direction is the first axis and the acceleration in the vehicle vertical direction is 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, the control unit 228R2 executes a correction process for the optical axis O and the reference value of the vehicle attitude angle θv based on the change in the gradient of the obtained linear approximation equation at any timing during the vehicle travel. 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 gradient of the linear approximation equation (the ratio of the amount of change in acceleration in the vehicle longitudinal direction and the vehicle vertical direction over time). For example, the control unit 228R2 calculates an integrated value of the change in gradient of the linear approximation equation from the initial calculation to derive the vehicle attitude angle θv, and obtains 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, the control unit 228R2, similar to the second embodiment, obtains the vehicle attitude angle θv from the slope between a 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, when 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. In addition, the control unit 228R2 generates a control signal for adjusting the optical axis position by the correction value θc, thereby correcting the optical axis position. The control unit 228R2 may execute the above-mentioned correction process immediately after the vehicle 300 stops, etc.

[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 the error caused by, for example, the main error factor that has the smallest generated error value. An example of such an error factor is the variation in vehicle attitude under the same load condition, that is, the variation in suspension displacement.

[0070] Moreover, 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 if the detection accuracy of the error component Δθe is low. For example, the resolution of angle detection using the change in the slope of the linear approximation equation is 0.04°, 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 appropriately set based on experiments and simulations by the designer.

[0071] As described above, the plot range information is configured as a set of an acceleration side range and a deceleration side range. In this way, by combining the acceleration side range and the deceleration side range, 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 cancelled out, so that the linear approximation formula can be calculated with higher accuracy. In addition, the first acceleration range P1(+) and the first deceleration range P1(-) are set to have the same range of magnitude (absolute value) of acceleration and deceleration, respectively, for example. 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 cancelled out more effectively, so that the linear approximation formula can 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. The second acceleration range P2(+) and the second deceleration range P2(-) are set to be a predetermined range of rapid acceleration / deceleration, in which the acceleration / deceleration is greater than that of 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 approximation equations 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 gradient of each linear approximation equation. In this case, the weighting of 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 gradient of the linear approximation equations calculated independently. Furthermore, when plots 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(-) are aligned within a specified time period, a linear approximation equation may be calculated using these plots, and when plots for all sets are not aligned within the specified time period, a linear approximation equation may be calculated using the plots for the set of plots that are aligned at that time period.

[0074] The plot range information may be composed of only one of 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(-). For example, the set of the first acceleration range P1(+) and the first deceleration range P1(-) set in the range of gradual acceleration / deceleration is more likely to include the detection value of the acceleration sensor 316 during vehicle travel than the set of the second acceleration range P2(+) and the second deceleration range P2(-) set in the range of rapid acceleration / deceleration, so that the number of correction processes can be increased. The number of sets 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 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 be more effectively cancelled out, allowing the linear approximation equation to be calculated with greater accuracy. The range widths of the acceleration range and the deceleration range, the magnitudes of the acceleration / deceleration, etc. can be appropriately set 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 in a state in which an instruction to execute the auto-leveling control mode is 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 complete (S202). If the plots are not complete (N in S202), the control unit 228R2 avoids the optical axis adjustment (S203) and ends this routine. If the plots are complete (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). After that, the control unit 228R2 avoids optical axis adjustment for the 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 (210), 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 the 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 equation 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, an error component of a vehicle attitude change caused by acceleration and an error component of a vehicle attitude change caused by deceleration can be cancelled out, so that a linear approximation equation having a slope closer to the vehicle attitude angle θv can be calculated.

[0081] Furthermore, the control unit 228R2 executes the correction process at the time when the 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 performed while the vehicle is stopped after the correction process, the vehicle 300 may 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 lighting unit 10 whose optical axis is adjustable, an acceleration sensor 316, and illumination controllers 228L and 228R for controlling the lighting unit 10, and the illumination controllers 228L and 228R execute the above-mentioned auto-leveling control.

[0083] Another aspect of the present invention is the illumination control units 228L and 228R as a control device. The illumination control units 228L and 228R include a receiving unit 228L1 and 228R1 for receiving acceleration in the vehicle longitudinal direction and the vehicle vertical direction from the acceleration sensor 316, a control unit 228L2 and 228R2 for executing the above-mentioned auto-leveling control, and a transmitting unit 228L3 and 228R3 for transmitting a control signal generated by the control unit 228L2 and 228R2 to the leveling control unit 236. The illumination control unit 228 in the vehicle lighting system 200 corresponds to a control unit in a broad sense, and the control units 228L2 and 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 the 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-mentioned embodiments, and it is possible to combine the embodiments, or to add various modifications such as design changes based on the knowledge of a person skilled in the art, and such combined or modified embodiments are also included in the scope of the present invention. New embodiments resulting from combinations of the above-mentioned embodiments with each other, or combinations of the above-mentioned embodiments with the following modifications, have the same effects as the combined embodiments and modifications.

[0086] In each of the above-mentioned embodiments, the illumination control unit 228 may control the leveling actuator 226 as the optical axis adjustment unit without the intervention of 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 instructing the optical axis adjustment in each of the above-mentioned 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, the correction process may be performed using a predetermined threshold value θth and a correction value θc. [Explanation of symbols]

[0088] 10 lighting unit, 200 vehicle lighting system, 228, 228L, 228R irradiation 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. outputting a control signal for changing the illumination direction of the vehicle lamp in the vertical direction of the vehicle when a ratio between an amount of change in acceleration in the longitudinal direction of the vehicle and an amount of change in acceleration in the vertical direction of the vehicle detected by the acceleration sensor while the vehicle is traveling changes; A control device for vehicle lighting.

2. Holds information about vehicle attitude angles; When a ratio between an amount of change in acceleration in a vehicle's forward / rearward direction and an amount of change in acceleration in a vehicle's up / down direction detected by an acceleration sensor while the vehicle is traveling changes, the stored information changes before and after the change in the ratio. A control device for vehicle lighting.

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

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

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