Control device for vehicle lamp, vehicle lamp, and method of controlling vehicle lamp

There is provided a control device for controlling a vehicle lamp provided in a vehicle. The device includes: a receiver configured to receive an inclination angle of the vehicle with respect to a horizontal plane from an inclination detector; a controller configured to: i) generate a first control signal instructing the vehicle lamp to adjust an optical axis of the vehicle lamp in response to a change of the inclination angle, when the vehicle has already stopped; and ii) generate a second control signal instructing the vehicle lamp to maintain the optical axis of the vehicle lamp, when the vehicle is traveling on a road surface; and a transmitter configured to transmit the first control signal or the second control signal to an optical axis adjuster provided in the vehicle lamp.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2010-151180, filed on Jul. 1, 2010, the entire contents of which are hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a control device for a vehicle lamp, the vehicle lamp, and a method of controlling the vehicle lamp.

2. Related Art

An automatic leveling control, which changes an irradiation direction by automatically adjusting the position of an optical axis of a vehicle headlight according to an inclination angle of a vehicle, has been known in the past. In automatic leveling control, a vehicle height sensor is used as an inclination detector of a vehicle and the position of an optical axis of a headlight is adjusted based on a pitch angle of a vehicle that is detected by the vehicle height sensor. Meanwhile, a structure, which performs automatic leveling control using a gravity sensor as an inclination detector, is disclosed in JP-A-2000-085459. Further, a structure, which performs automatic leveling control using a three-dimensional gyro-sensor as an inclination detector, is disclosed in JP-A-2004-314856.

If an acceleration sensor, such as a gravity sensor or a three-dimensional gyro-sensor, is used as an inclination detector of a vehicle, it may be possible to reduce the manufacturing cost and weight of an automatic leveling system as compared to a case where a vehicle height sensor is used. Meanwhile, the inventors have recognized that there is the following problem in the automatic leveling control using the acceleration sensor in the related art.

That is, an inclination angle detected by the acceleration sensor is an inclination angle of a vehicle with respect to a horizontal plane that includes an inclination angle of a road surface with respect to the horizontal plane and an inclination angle of a vehicle with respect to the road surface. Meanwhile, an inclination angle of a vehicle required for the automatic leveling control is an inclination angle of a vehicle with respect to the road surface. Meanwhile, when a detected value of the acceleration sensor is changed in the automatic leveling control in the related art, the position of an optical axis has been adjusted without determining whether the change of the detected value of the acceleration sensor is the change of the inclination angle of a road surface with respect to a horizontal plane or the change of the inclination angle of a vehicle with respect to the road surface. For this reason, it has been desired to accurately adjust the position of an optical axis in the automatic leveling control using the acceleration sensor in the related art.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention may address the above disadvantages and other disadvantages not described above. However, the present invention is not required to overcome the disadvantages described above, and thus, an exemplary embodiment of the present invention may not overcome any disadvantages.

Exemplary embodiments provide a technique performing automatic leveling control, which acquires an inclination angle of a vehicle with respect to a horizontal plane from an inclination detector and adjusts the position of an optical axis of a vehicle lamp, with higher accuracy.

According to one or more illustrative aspecsts of the present invention, there is provided a control device for controlling a vehicle lamp provided in a vehicle. The device includes: a receiver configured to receive an inclination angle of the vehicle with respect to a horizontal plane from an inclination detector; a controller configured to: i) generate a first control signal instructing the vehicle lamp to adjust an optical axis of the vehicle lamp in response to a change of the inclination angle, when the vehicle has already stopped; and ii) generate a second control signal instructing the vehicle lamp to maintain the optical axis of the vehicle lamp, when the vehicle is traveling on a road surface; and a transmitter configured to transmit the first control signal or the second control signal to an optical axis adjuster provided in the vehicle lamp.

According to one or more illustrative aspects of the present invention, there is provided a vehicle lamp provided in a vehicle. In the vehicle lamp, an optical axis of the vehicle lamp is adjested in response to a change of an inclination angle of the vehicle with respect to a horizontal plane, when the vehicle has already stopped, and the optical axis is maintained even if the inclination angle is changed, when the vehicle is tranvelling on a road surface.

According to one or more illustrative aspects of the present invention, there is provided a method of controlling a vehicle lamp provided in a vehicle. The method includes: detecting an inclination angle of the vehicle with respect to a horizontal plane; adjusting an optical axis of the vehicle lamp in response to a change of the inclination angle, when the vehicle has already stopped; and maintaining the optical axis of the vehicle lamp, when the vehicle is traveling on a road surface.

According to one or more illustrative aspects of the present invention, there is provided a vehicle lamp system. The vehicle lamp system includes: a vehicle lamp mounted in a vehicle so as to irradiate an area in front of the vehicle with light; an inclination detector that detects an inclination angle of the vehicle with respect to a horizontal plane; an optical axis adjuster that adjusts an optical axis of the vehicle lamp; and a control device for controlling the vehicle lamp. The control device includes: a receiver configured to receive the inclination angle from the inclination detector; a controller configured to: i) generate a first control signal instructing the vehicle lamp to adjust the optical axis of the vehicle lamp in response to a change of the inclination angle, when the vehicle has already stopped; and ii) generate a second control signal instructing the vehicle lamp to maintain the optical axis of the vehicle lamp, when the vehicle is traveling on a road surface; and a transmitter configured to transmit the first control signal or the second control signal to the optical axis adjuster. The optical axis adjuster adjusts the optical axis of the vehicle lamp based on the first control signal or the second control signal.

Other aspects and advantages of the present invention will be apparent from the following description, the drawings and the claims.

DETAILED DESCRIPTION

Preferred embodiments of the invention will be described below with reference to the drawings. The same or equivalent elements, members, and processes, which are shown in the respective drawings, are denoted by the same reference numerals, and repeated description thereof will be appropriately omitted. Further, the embodiments are illustrative and do not limit the invention. The characteristics or combinations described in the embodiments are not necessarily essential in the invention.

FIG. 1is a schematic vertical cross-sectional view illustrating the internal structure of a vehicle lamp system according to a first embodiment. A vehicle lamp system200according to this embodiment is an adaptive front-lighting system where a pair of headlight units symmetrical to each other is disposed at the left and right portions of a vehicle in a vehicle width direction, respectively. The headlight units, which are disposed at the right and left portions of the vehicle, have substantially the same structure except for the symmetrical structure. Accordingly, the structure of a right headlight unit210R will be described below, and the description of a left headlight unit will be appropriately omitted. Meanwhile, when being described, the respective members of the left headlight unit are denoted by the same reference numerals as those of the members of the headlight unit210R that correspond to the members of the left headlight unit.

The headlight unit210R includes a lamp body212and a translucent cover214. The lamp body212includes an opening that is formed on the front side of a vehicle. The translucent cover214covers the opening. The lamp body212includes a detachable cover212athat is provided on the rear side thereof in the longitudinal direction of a vehicle and can be detached when a bulb14is replaced. A lamp chamber216is formed by the lamp body212and the translucent cover214. A lamp unit10(vehicle lamp), which irradiates the area in front of the vehicle with light, is received in the lamp chamber216.

A lamp bracket218, which includes a pivot mechanism218aserving as a swiveling center of the lamp unit10in vertical and horizontal directions, is formed at a part of the lamp unit10. The lamp bracket218is threadably engaged with aiming adjustment screws220that are rotatably supported by the wall surface of the lamp body212. Accordingly, the lamp unit10is fixed at a predetermined position in the lamp chamber216that is set according to the adjustment states of the aiming adjustment screws220, and can swivel about the pivot mechanism218aat that position so that the posture of the lamp unit is changed to a forward inclined posture or a backward inclined posture.

Further, a rotating shaft222aof a swivel actuator222of an adaptive front-lighting system (AFS) for a curved road, which irradiates the area in front in a traveling direction along which the subject vehicle is traveling while a vehicle is traveling on a curved road, is fixed to the lower surface of the lamp unit10. The swivel actuator222makes the lamp unit10swivel about the pivot mechanism218ain the traveling direction based on the steering angle data provided from the vehicle, the shape data of a traveling road provided from a navigation system, a relative positional relationship between a subject vehicle and a front vehicle including an oncoming vehicle and a preceding vehicle, and the like. As a result, the irradiation area of the lamp unit10faces not the area in front of the vehicle but the area in front on the curved road, so that the driver's forward field of view is improved. The swivel actuator222may be formed of, for example, a stepping motor. Meanwhile, if a swivel angle has a fixed value, a solenoid or the like may also be used as the swivel actuator. The swivel actuator222is fixed to a unit bracket224.

A leveling actuator226, which is disposed outside the lamp body212, is connected to the unit bracket224. The leveling actuator226is formed of, for example, a motor or the like that pushes and pulls a rod226ain directions of arrows M and N. When the rod226ais pushed in the direction of the arrow M, the lamp unit10swivels about the pivot mechanism218aso as to be inclined backward. On the contrary, when the rod226ais pulled in the direction of the arrow N, the lamp unit10swivels about the pivot mechanism218aso as to be inclined forward. When the lamp unit10is inclined backward, it may be possible to perform leveling adjustment that makes a pitch angle of an optical axis O, that is, an angle of the optical axis O in a vertical direction be directed to the upper side. When the lamp unit10is inclined forward, it may be possible to perform leveling adjustment that makes the pitch angle of the optical axis O be directed to the lower side. It may be possible to adjust the optical axis according to the posture of the vehicle by performing the above-mentioned leveling adjustment. As a result, it may be possible to adjust the range of light, which is emitted forward from the vehicle lamp system200, to an optimum distance.

An irradiation controller228(control device), which controls the turning-on/off of the lamp unit10or controls the formation of a light distribution pattern, and adjusts the optical axis of the lamp unit10, is disposed on the inner wall surface of the lamp chamber216below the lamp unit10. An irradiation controller228R, which controls the headlight unit210R, is disposed inFIG. 1. The irradiation controller228R also controls the swivel actuator222, the leveling actuator226, and the like. Meanwhile, the irradiation controller228R may be provided outside the headlight unit210R.

The lamp unit10may include an aiming adjustment mechanism. For example, an aiming pivot mechanism (not shown), which functions as a swiveling center during aiming adjustment, is disposed at a connection portion between the unit bracket224and the rod226aof the leveling actuator226. Furthermore, the above-mentioned aiming adjustment screws220are disposed at the lamp bracket218with a gap therebetween in the vehicle width direction. For example, when the two aiming adjustment screws220are rotated in a counterclockwise direction, the lamp unit10swivels about the aiming pivot mechanism so as to be inclined forward. Accordingly, the optical axis O is adjusted so as to be directed to the lower side. Likewise, when the two aiming adjustment screws220are rotated in a clockwise direction, the lamp unit10swivels about the aiming pivot mechanism so as to be inclined backward. Accordingly, the optical axis O is adjusted so as to be directed to the upper side. Furthermore, when the aiming adjustment screw220, which is disposed on the left side in the vehicle width direction, is rotated in the counterclockwise direction, the lamp unit10swivels about the aiming pivot mechanism so as to be in a right swivel posture. Accordingly, the optical axis O is adjusted so as to be directed to the right side. Moreover, when the aiming adjustment screw220, which is disposed on the right side in the vehicle width direction, is rotated in the counterclockwise direction, the lamp unit10swivels about the aiming pivot mechanism so as to be in a left swivel posture. Accordingly, the optical axis O is adjusted so as to be directed to the left side. This aiming adjustment is performed at the time of the shipment of vehicles, the inspection of vehicles, or the replacement of the headlight unit210R. Further, the headlight unit210R is adjusted to a designed posture, and the formation of a light distribution pattern or the adjustment of the position of the optical axis is controlled based on this posture.

The lamp unit10includes a shade mechanism18including a rotary shade12, a bulb14as a light source, a lamp housing17that supports a reflector16on the inner wall thereof, and a projection lens20. For example, an incandescent bulb, a halogen lamp, a discharge bulb, an LED, or the like may be used as the bulb14. An example where the bulb14is formed of a halogen lamp is described in this embodiment. The reflector16reflects light that is emitted from the bulb14. Further, a part of the light emitted from the bulb14and the light reflected by the reflector16are guided to the projection lens20through the rotary shade12.

The rotary shade12is a cylindrical member that is rotatable about a rotating shaft12a. Moreover, the rotary shade12includes a cutout portion that is formed by cutting out a part of the rotary shade in an axial direction, and a plurality of shade plates (not shown). Any one of the cutout portion and the shade plates is moved onto the optical axis O, so that a predetermined light distribution pattern is formed. At least a part of the reflector16is formed in an ellipsoidal shape, and the ellipsoidal surface of the reflector is set so that the shape of the cross-section of the ellipsoidal surface, which includes the optical axis O of the lamp unit10, becomes at least a part of an elliptical shape. The ellipsoidal portion of the reflector16has a first focus substantially at the center of the bulb14, and has a second focus on the rear focal plane of the projection lens20.

The projection lens20is disposed on the optical axis O extending in the longitudinal direction of a vehicle. The bulb14is disposed on the rear side of a rear focal plane that is a focal plane including the rear focus of the projection lens20. The projection lens20is formed of a plano-convex aspheric lens of which the front surface is a convex surface and the rear surface is a flat surface. The projection lens projects a light source image, which is formed on the rear focal plane, onto a virtual vertical screen, which is formed in front of the vehicle lamp system200, as an inverted image. Meanwhile, the structure of the lamp unit10is not particularly limited thereto, and the lamp unit may be a reflective lamp unit or the like that does not include the projection lens20.

FIG. 2is a functional block diagram illustrating an operational interaction between the irradiation controller of the above headlight unit and a vehicle controller provided in a vehicle. Meanwhile, since the structure of the right headlight unit210R is basically the same as that of the left headlight unit210L as described above, only the right headlight unit210R will be described and the description of the left headlight unit210L will be omitted.

The irradiation controller228R of the headlight unit210R includes a receiver228R1, a controller228R2, a transmitter228R3, and a memory228R4. The irradiation controller228R controls a power circuit230based on the information obtained from a vehicle controller302mounted on a vehicle300, and controls the turning-on of the bulb14. Further, the irradiation controller228R controls a variable shade controller232, a swivel controller234, and a leveling controller236(optical axis adjuster) based on the information obtained from the vehicle controller302. Various kinds of information, which are transmitted from the vehicle controller302, are received by the receiver228R1, and various control signals are generated from the information, which is stored in the memory228R4, according to the information and need by the controller228R2. Further, the control signals are transmitted to the leveling controller236, the swivel controller234, the variable shade controller232, or the power circuit230of the lamp unit10by the transmitter228R3. The memory228R4is, for example, a nonvolatile memory.

The variable shade controller232controls the driving of a motor238, which is connected to the rotating shaft12aof the rotary shade12through a gear mechanism, and moves a desired shade plate or the cutout portion onto the optical axis O. Meanwhile, rotation information, which represents the rotational state of the rotary shade12and is provided from a detection sensor such as an encoder provided on the motor238or the rotary shade12, is provided to the variable shade controller232. Accordingly, accurate rotation control is realized by feedback control. Further, the swivel controller234adjusts the angle of the optical axis O of the lamp unit10in the vehicle width direction (horizontal direction) by controlling the swivel actuator222. For example, when a vehicle travels on a curved road or turns right or left, the optical axis O of the lamp unit10is directed to the traveling direction where the vehicle is to travel.

The leveling controller236adjusts the optical axis O of the lamp unit10in the vertical direction of the vehicle (the direction of the pitch angle) by controlling the leveling actuator226. For example, the leveling controller adjusts the range of light, which is emitted toward the front side, to an optimum distance by adjusting the posture of the lamp unit10according to whether the posture of a vehicle is inclined forward or backward at the time of increase/decrease of the amount of load or the number of persons on the vehicle. The vehicle controller302also provides the same information as the information, which is provided to the headlight unit210R, to the headlight unit210L, and an irradiation controller228L (control device) of the headlight unit210L performs the same control as the control that is performed by the irradiation controller228R.

In the case of this embodiment, the light distribution patterns formed by the headlight units210L and210R may be switched according to the operation of a light switch304that is performed by a driver. In this case, each of the irradiation controllers228L and228R determines a light distribution pattern, which is to be formed by the lamp unit10, by controlling the motor238through the variable shade controller232according to the operation of the light switch304.

The headlight units210L and210R of this embodiment detect the circumstances around the vehicle by various sensors and may be automatically controlled regardless of the operation of the light switch304so as to form light distribution patterns optimal for the state of the vehicle300or the circumstances around the vehicle. For example, when it may be possible to detect that preceding vehicles, oncoming vehicles, pedestrians, or the like are present in front of a subject vehicle, the irradiation controllers228L and228R determine that glare should be prevented based on the information obtained from the vehicle controller302. Then, the irradiation controllers form low beam light distribution patterns by the lamp units10. Further, when it may be possible to detect that preceding vehicles, oncoming vehicles, pedestrians, or the like are not present in front of a subject vehicle, the irradiation controllers228L and228R determine that the driver's visibility should be improved. Then, the irradiation controllers form high beam light distribution patterns where light is not blocked by the rotary shades12. Furthermore, when a so-called left or right-side high light distribution pattern, a special high beam light distribution pattern well known in the related art such as a V-beam light distribution pattern, or a special low beam light distribution pattern can be formed in addition to the low beam light distribution patterns and the high beam light distribution patterns, a light distribution pattern optimal for a front vehicle may be formed according to the presence/non-presence of a front vehicle. This control mode may be referred to as an ADB (Adaptive Driving Beam) mode.

A camera306, such as a stereo camera, for recognizing an object is connected to the vehicle controller302in order to detect objects, such as preceding vehicles or oncoming vehicles as described above. Frame data of images taken by the camera306are subjected to predetermined image processing such as object recognition processing in an image processor308, and the results of recognition are provided to the vehicle controller302. For example, if data including feature points, which represent a vehicle and are previously stored in the vehicle controller302, are present in the recognition result data provided from the image processor308, the vehicle controller302recognizes the presence of the vehicle and provides information about the vehicle to the irradiation controllers228L and228R. The irradiation controllers228L and228R receive the information about the vehicle from the vehicle controller302, determine light distribution patterns optimal for the vehicle, and form the light distribution patterns. Here, the “feature points representing a vehicle” mean, for example, light spots that have luminance equal to or higher than a predetermined luminance and appear in an estimated area where the headlights, sign lamps such as tail lamps, and the like of a front vehicle are present. Further, for example, if data including feature points, which represent a pedestrian and are previously stored, are present in the recognition result data provided from the image processor308, the vehicle controller302provides information about the pedestrian to the irradiation controllers228L and228R. Then, the irradiation controllers228L and228R form light distribution patterns optimal for the pedestrian.

Furthermore, the vehicle controller302may also acquire information from a steering sensor310, a vehicle speed sensor312, a navigation system314, an acceleration sensor316(inclination detector) that are mounted on the vehicle300. Accordingly, the irradiation controllers228L and228R may select a light distribution pattern that is formed according to the traveling state or traveling posture of the vehicle300, or easily change the light distribution pattern by changing the direction of the optical axis O. For example, when luggage is loaded in a luggage compartment formed at the rear portion of the vehicle or occupants are seated in the rear seats, the posture of the vehicle becomes a backward inclined posture. When luggage is unloaded or occupants get out of the rear seats, the vehicle is inclined forward from the backward inclined posture. The irradiation direction of the lamp unit10is also changed in a vertical direction according to the posture of the vehicle300, so that the range of light emitted forward increases or decreases. Further, the irradiation controllers228L and228R receive the inclination angle of the vehicle300from the acceleration sensor316through the vehicle controller302, and set the pitch angle of the optical axis O to an angle according to the posture of the vehicle by controlling the leveling actuator226through the leveling controller236. Since the leveling adjustment of the lamp unit10is performed in real time based on the posture of the vehicle as described above, it may be possible to adjust the range of light, which is emitted forward, to an optimum distance even though the posture of the vehicle is changed according to the state of use of the vehicle300. This control mode may be referred to as an automatic leveling control mode. For example, when the automatic formation control for automatically forming light distribution patterns is instructed by the light switch304, the automatic formation control for automatically forming light distribution patterns, which includes the above-mentioned various control modes, is performed.

Subsequently, the automatic leveling control of the vehicle lamp system200having the above-mentioned structure will be described in detail.

The acceleration sensor316of the vehicle lamp system200is, for example, a three-axis acceleration sensor that has an X axis, a Y axis, and a Z axis perpendicular to one another. The acceleration sensor316is mounted on the vehicle300so that the X axis of the sensor is parallel to the longitudinal axis of the vehicle300, the Y axis of the sensor is parallel to the horizontal axis of the vehicle300, and the Z axis of the sensor is parallel to the vertical axis of the vehicle300. The acceleration sensor316can detect a resultant acceleration vector of a gravity acceleration vector and a motion acceleration vector that is generated due to the movement of the vehicle300, and outputs numerical values of the respective components of the resultant acceleration vector in three axis directions. When the vehicle300has already stopped, the acceleration sensor316outputs numerical values of the respective components of the gravity acceleration vector in three axis directions. That is, the acceleration sensor316can detect the inclination angle (total angle) of the vehicle with respect to the horizontal plane, which includes the inclination angle (first angle) of a road surface with respect to the horizontal plane and the inclination angle (second angle) of the vehicle with respect to the road surface, as a vector. Hereinafter, the inclination angle of a road surface with respect to the horizontal plane is appropriately referred to as a “road surface angle” and is denoted by reference character θr; the inclination angle of a vehicle with respect to the road surface is appropriately referred to as a “vehicle posture angle” and is denoted by reference character θv; and the inclination angle of the vehicle with respect to the horizontal plane is appropriately referred to as a “total angle” and is denoted by reference character θ. Meanwhile, each of the road surface angle θr, the vehicle posture angle θv, and the total angle θ is an angle of the X axis in the vertical direction, that is, an angle of a pitch direction of the vehicle300.

Here, an object of the automatic leveling control is to keep the range of light, which is emitted toward the front side, to an optimum distance by absorbing the change of the range of light, which is emitted forward from the vehicle lamp, caused by the change of the inclination angle of the vehicle. Accordingly, the inclination angle of the vehicle, which is required for the automatic leveling control, is a vehicle posture angle θv. Meanwhile, the vehicle lamp system200according to this embodiment performs control so as to adjust the position of the optical axis of the lamp unit10if the vehicle posture angle θv is changed and so as to keep the position of the optical axis of the lamp unit10if the road surface angle θr is changed.

Further, in this embodiment, the change of the total angle θ during the stop of the vehicle is estimated as the change of the vehicle posture angle θv and the change of the total angle θ during the traveling of the vehicle is estimated as the change of the road surface angle θr. That is, since the vehicle posture angle θv is rarely changed during the traveling of the vehicle by the increase or decrease of the amount of load or the number of persons on the vehicle, the change of the total angle θ during the traveling of the vehicle may be estimated as the change of the road surface angle θr. Meanwhile, since the road surface angle θr is rarely changed during the stop of the vehicle by the movement of the vehicle300, the change of the total angle θ during the stop of the vehicle may be estimated as the change of the vehicle posture angle θv. The irradiation controller228R receives the total angle θ from the acceleration sensor316, generates a control signal that instructs the lamp unit to adjust the position of the optical axis with respect to the change of the total angle θ during the stop of the vehicle, and avoids generating the control signal with respect to the change of the total angle θ during the traveling of the vehicle. Further, the irradiation controller transmits the control signal to the leveling controller236. Meanwhile, the irradiation controller228R may generate a control signal that instructs the lamp unit to keep the position of the optical axis with respect to the change of the total angle θ during the traveling of the vehicle, and may transmit the control signal to the leveling controller236.

Specifically, firstly, the vehicle300is placed on the horizontal plane, for example, at a vehicle maker's manufacturing plant, a dealer's maintenance shop, or the like, and this state is referred to as a reference state. The reference state is a state where one person gets in the driver's seat of the vehicle300, or an empty state where there is no person in the vehicle. Further, an initialization signal is transmitted to the irradiation controller228R by the operation of a switch of an initialization processor in the plant, the communication of a CAN (Controller Area Network) system that connects the irradiation controller228R to the acceleration sensor316through the vehicle controller302. The initialization signal, which is transmitted to the irradiation controller228R, is received by the receiver228R1and is sent to the controller228R2. When receiving the initialization signal, the controller228R2performs initial aiming adjustment while using an output value of the acceleration sensor316, which is received by the receiver228R1, as a reference inclination angle. Moreover, the controller228R2records the information about the fact that the reference value of the road surface angle θr is 0° and the reference value of the vehicle posture angle θv is 0° in the memory228R4. Accordingly, the controller228R2keeps these reference values.

During the traveling of the vehicle, the controller228R2(irradiation controller228R) avoids generating a control signal that instructs the lamp unit to adjust the position of the optical axis. It may be possible to determine the fact that the vehicle300is traveling, by vehicle speed obtained from, for example, the vehicle speed sensor312. “During the traveling of the vehicle” means a period, for example, between when the detected value of the vehicle speed sensor312exceeds 0 and when the detected value of the vehicle speed sensor312becomes 0. “During the traveling of the vehicle” may be appropriately set based on the experiments or simulations of a designer.

Further, when the vehicle is stopping, the controller228R2calculates the road surface angle θr during the stop of the vehicle by subtracting the reference value of the vehicle posture angle θv, which is read out from the memory228R4, from the current inclination angle of the vehicle300that is detected by the acceleration sensor316, that is, the total angle θ. Furthermore, this road surface angle θr is recorded in the memory228R4as a new reference value of a road surface angle θr. “During the stop of the vehicle” means a period, for example, when the detected value of the acceleration sensor316is stable after the detected value of the vehicle speed sensor312becomes 0. The reason why “During the stop of the vehicle” means a period until the detected value of the acceleration sensor316is stable is that some time is required until the posture of the vehicle becomes stable after the stop of the vehicle300and it is difficult to detect an accurate total angle θ when the posture of the vehicle is not stable. This “period until the detected value of the acceleration sensor316is stable” may be a period until the variation of the detected value of the acceleration sensor316per unit time becomes equal to or smaller than a predetermined value and may be a period until a predetermined time has passed after the detected value of the vehicle speed sensor312becomes 0. “During the stop of the vehicle”, the “predetermined value”, and the “predetermined time” may be appropriately set based on the experiments or simulations of a designer.

Meanwhile, when a difference between the reference value of the road surface angle θr recorded in the memory228R4and the road surface angle θr during the stop of the vehicle calculated by subtracting the reference value of the vehicle posture angle θv from the total angle θ during the stop of the vehicle is equal to or larger than a predetermined value, the controller228R2may record the calculated road surface angle Or in the memory228R4as a new reference value. Further, the controller228R2may calculate a road surface angle θr when the total angle θ at the time of the start of the vehicle300is different from the total angle θ during the stop of the vehicle. In this case, it may be possible to avoid frequently rewriting the reference value of the road surface angle θr and to reduce the control load of the controller228R2.

During the stop of the vehicle, the controller228R2repeatedly calculates the vehicle posture angle θv at a predetermined timing. The vehicle posture angle θv is calculated by subtracting the reference value of the road surface angle θr, which is recorded in the memory228R4, from the current total angle θ. When a difference between the calculated vehicle posture angle θv and the reference value of the vehicle posture angle θv is equal to or larger than a predetermined value, the controller228R2generates a control signal, which is used for the adjustment of the optical axis, based on the newly obtained vehicle posture angle θv. Further, the optical axis is adjusted based on this control signal. Further, the calculated vehicle posture angle θv is recorded in the memory228R4as a new reference value. Since the optical axis is adjusted when a difference between the calculated vehicle posture angle θv and the reference value is equal to or larger than a predetermined value as described above, it may be possible to avoid frequently adjusting the optical axis. As a result, it may be possible to reduce the control load of the controller228R2and to lengthen the life of the leveling actuator226. “During the stop of the vehicle” means a period, for example, until the start of the vehicle after the detected value of the acceleration sensor316is stable. “The time of the start of the vehicle” means, for example, the time when the detected value of the vehicle speed sensor312exceeds 0. Meanwhile, the calculation of the vehicle posture angle θv may not be repeated at a predetermined timing and may be performed at the time of the start of the vehicle. “During the stop of the vehicle” may be appropriately set based on the experiments or simulations of a designer.

Moreover, for example, power is not supplied to the irradiation controller228R during the turning-off of the ignition (IG). The controller228R2receives an IG-OFF signal generated from the vehicle controller302during the turning-off of the ignition when the memory228R4is not a nonvolatile memory, or the reference value of the road surface angle θr is recorded in a nonvolatile memory (not shown) when a power supply voltage supplied to the irradiation controller228R is equal to or smaller than a predetermined voltage. Accordingly, since it may be possible to keep the reference value of the road surface angle θr even though the ignition is turned off, it may be possible to perform automatic leveling control with high accuracy even after the ignition is turned on.

Further, when the ignition is turned on, that is, when the irradiation controller228R is started, the controller228R2calculates the vehicle posture angle θv from the detected value of the acceleration sensor316and the reference value of the road surface angle θr. Furthermore, the controller228R2determines the position of the optical axis using the calculated vehicle posture angle θv, and records and keeps the calculated vehicle posture angle θv in the memory228R4as a new reference value. Accordingly, even though the vehicle posture angle θv is changed while the ignition is turned off, the optical axis O is adjusted to an appropriate position during the turning-off of the ignition. Therefore, it may be possible to improve the accuracy of the automatic leveling control.

FIG. 3is a flowchart of automatic leveling control of the vehicle lamp system according to the first embodiment. In the flowchart ofFIG. 3, each process is denoted by the combination of a number and the letter S (the initial letter of step) meaning a step. Further, a certain determination is performed by a process that is denoted by the combination of a number and the letter S. If the result of the determination is positive, Y (the initial letter of Yes) is added, for example, this is represented as Y in S101. If the result of the determination is negative, N (the initial letter of No) is added, for example, this is represented as N in S101. For example, when the automatic leveling control mode is instructed by the light switch304, this flow is repeated at a predetermined timing during the turning-on of the ignition by the irradiation controller228R (controller228R2) and is ended at the time of the turning-off of the ignition.

Firstly, the controller228R2determines whether a vehicle is traveling on a road surface (S101). If the vehicle is traveling (Y in S101), the controller228R2avoids adjusting the optical axis (S102) without generating a control signal that instructs the lamp unit to adjust the position of the optical axis and ends this routine. If the vehicle is not traveling (N in S101), the controller228R2determines whether the vehicle is about to stop (S103). If the vehicle is about to stop (Y in S103), the controller228R2calculates the road surface angle θr by subtracting the reference value of the vehicle posture angle θv from the current total angle θ (S104) and records the calculated road surface angle θr in the memory228R4as a new reference value. Further, the irradiation controller228R avoids adjusting the optical axis (S102), and ends this routine.

If the vehicle is not about to stop (N in S103), this case means that the vehicle has already stopped. Accordingly, the controller228R2calculates the vehicle posture angle θv by subtracting the reference value of the road surface angle θr from the current total angle θ (S106). Subsequently, the controller228R2determines whether a difference between the calculated vehicle posture angle θv and the reference value of the vehicle posture angle θv is equal to or larger than a predetermined value (S107). If the difference between the calculated vehicle posture angle θv and the reference value of the vehicle posture angle θv is smaller than the predetermined value (N in S107), the controller228R2avoids adjusting the optical axis (S102) and ends this routine. If the difference between the calculated vehicle posture angle θv and the reference value of the vehicle posture angle θv is equal to or larger than the predetermined value (Y in S107), the controller228R2adjusts the position of the optical axis based on the calculated vehicle posture angle θv (S108). Further, the controller228R2records the calculated vehicle posture angle θv in the memory228R4as a reference value (S109), and ends this routine.

Meanwhile, the left headlight unit210L performs the same control as the control of the irradiation controller228L (controller228L2). Alternatively, one of the irradiation controllers228L and228R may calculate the vehicle posture angle θv or the road surface angle θr, and the other thereof may acquire the calculated vehicle posture angle θv or the calculated road surface angle θr and adjust the optical axis O.

When performing automatic leveling control based on the total angle θ detected by the acceleration sensor316in the vehicle lamp system200, the irradiation controllers228L and228R adjust the position of the optical axis of the lamp unit if the vehicle posture angle θv is changed and maintains the position of the optical axis of the lamp unit10if the road surface angle θr is changed. Further, in this embodiment, the change of the total angle θ during the stop of the vehicle is estimated as the change of the vehicle posture angle θv and the change of the total angle θ during the traveling of the vehicle is estimated as the change of the road surface angle θr. Furthermore, each of the irradiation controllers228L and228R generates a control signal that instructs the lamp unit to adjust the position of the optical axis with respect to the change of the total angle θ during the stop of the vehicle, and avoids generating the control signal with respect to the change of the total angle θ during the traveling of the vehicle or generates a control signal that instructs the lamp unit to maintain the position of the optical axis. Accordingly, it may be possible to perform the automatic leveling control, which uses the acceleration sensor316as an inclination detector, with higher accuracy. Further, since the inclination angle of the vehicle300is detected using the acceleration sensor316in this embodiment, a vehicle height sensor does not need to be used. For this reason, as compared to a case where a vehicle height sensor is used, this embodiment is advantageous in terms of reduction in cost and has a high degree of freedom in the design of a vehicle body.

A vehicle lamp system200according to a second embodiment performs automatic leveling control in consideration of the change of the vehicle posture angle θv that may occur during the traveling of a vehicle. This embodiment will be described below. Meanwhile, the main structure of the vehicle lamp system200, the main flow of automatic leveling control, and the shape of light distribution patterns that can be formed are the same as those of the first embodiment. Accordingly, the same elements as the elements of the first embodiment are denoted by the same reference numerals, and appropriately will not be described and shown.FIG. 4is a view illustrating automatic leveling control of the vehicle lamp system according to the second embodiment.

In the first embodiment, the change of a vehicle inclination angle (total angle θ) during the traveling of the vehicle is estimated as the change of the road surface angle θr. Accordingly, it may be possible to perform automatic leveling control with high accuracy by a simple control structure. However, although it is rare, the vehicle posture angle θv may be changed during the traveling of the vehicle. For example, if the vehicle300is a large vehicle such as a bus, there is a possibility that an occupant moves in the vehicle during the traveling of the vehicle. This may cause the change of the vehicle posture angle θv. For this reason, if the change of the total angle θ during the traveling of the vehicle is estimated as the change of the road surface angle θr, there is a possibility that an error occurs between an actual road surface angle θr and the estimated road surface angle θr.

Further, in this embodiment, whether a road surface is horizontal is determined at least at one timing of the time of the start of the vehicle and the time of the stop of the vehicle. Furthermore, the reference value of the road surface angle θr is corrected according to the result of the determination of whether a road surface is horizontal.

The determination of whether a road surface is horizontal at the time of the start of the vehicle and the correction of the reference value according to the result thereof will be performed as follows. Firstly, the controller228R2determines whether the vehicle300starts. If the variation of vehicle speed per unit time (the motion acceleration of the vehicle300), which is obtained from the detected value of the vehicle speed sensor312, is equal to or larger than a predetermined value, the controller228R2may determine that the vehicle300starts. It may be possible to appropriately set the predetermined value of the motion acceleration where it is determined that the vehicle300starts. Further, the controller228R2determines whether the vehicle300goes straight. The controller228R2can determine whether the vehicle goes straight, from the detected value of the steering sensor310or the numerical value of the Y-axis component of the acceleration sensor316. For example, when a steering angle is about 0°, the controller228R2determines that the vehicle300goes straight, from the detected value of the steering sensor310. It may be possible to appropriately set the range of the steering angle where it is determined that the vehicle300goes straight.

If the vehicle300goes straight, the controller228R2calculates the square of the magnitude of the detected value vector of the acceleration sensor316and the square of the magnitude of the motion acceleration vector of the vehicle300obtained from the vehicle speed sensor312after a predetermined time from the start of the vehicle. Moreover, if a difference between the square of the magnitude of the detected value vector of the acceleration sensor316and the square of the magnitude of the motion acceleration vector of the vehicle300is equal to the square of the magnitude of a gravity acceleration vector, the controller228R2corrects the kept reference value of the road surface angle θr so that the kept reference value of the road surface angle θr is close to 0°.

Further, the determination of whether a road surface is horizontal at the time of the stop of the vehicle and the correction of the reference value according to the result thereof will be performed as follows. Firstly, the controller228R2determines whether the stop of the vehicle300is predicted. If the variation of vehicle speed per unit time (the motion deceleration of the vehicle300, that is, negative motion acceleration), which is obtained from the detected value of the vehicle speed sensor312, is equal to or larger than a predetermined value, the controller228R2may predict that the vehicle300will stop. It may be possible to appropriately set the predetermined value of the motion deceleration where the stop of the vehicle300is predicted. Furthermore, the controller228R2determines whether the vehicle300goes straight.

If the vehicle speed becomes 0 and the vehicle300stops when the vehicle300goes straight, the controller228R2calculates the square of the magnitude of the detected value vector of the acceleration sensor316and the square of the magnitude of the motion acceleration vector of the vehicle300obtained from the vehicle speed sensor312before a predetermined time from the stop of the vehicle. Moreover, if a difference between the square of the magnitude of the detected value vector of the acceleration sensor316and the square of the magnitude of the motion acceleration vector of the vehicle300is equal to the square of the magnitude of a gravity acceleration vector, the controller228R2corrects the reference value of the road surface angle θr obtained at the time of the stop of the vehicle so that the reference value of the road surface angle θr is close to 0°.

As shown inFIG. 4, for example, if a vehicle300of which the pitch angle is inclined by the vehicle posture angle θv stops on a road having a road surface angle θr, gravity acceleration having a magnitude G is applied to the vehicle300and motion acceleration (motion deceleration) having a magnitude α is applied to the vehicle300in a direction where the vehicle300decelerates. This motion acceleration is a vector parallel to the road surface. Accordingly, an X-axis component, a Y-axis component, and a Z-axis component of the detected value vector (V=(x,y,z)) of the acceleration sensor316in this state can be represented by the following Formulas (1) to (3).
x=α·cos θv+G·sin(θv+θr)  (1)
y=0  (2)
z=−α·sin θv+G·cos(θv+θr)  (3)

Further, the square of the magnitude of the detected value vector V of the acceleration sensor316is represented by the following Formula (4).

The following Formula (5) is obtained from the modification of Formula (4).
|{right arrow over (V)}|2=α2=G2+2αG·sin θr(5)

If the vehicle300stops on a horizontal road, that is, if the road surface angle θr is 0°, it is understood from Formula (5) that a difference between the square of the magnitude of the detected value vector V of the acceleration sensor316and the square of the magnitude α of the motion acceleration vector is equal to the square of the magnitude G of a gravity acceleration vector. Accordingly, it may be possible to determine whether the vehicle300is placed on a horizontal plane, by calculating the square of the magnitude α of the motion acceleration vector of the vehicle300obtained from the vehicle speed sensor312and the square of the magnitude of the detected value vector V of the acceleration sensor316and determining whether a difference between the square of the magnitude α of the motion acceleration vector and the square of the magnitude of the detected value vector V is equal to the square of the magnitude G of the gravity acceleration vector. Moreover, if a difference between the square of the magnitude of the detected value vector and the square of the magnitude of the motion acceleration vector before a predetermined time from the stop of the vehicle is equal to the square of the magnitude of the gravity acceleration vector, the controller228R2corrects the reference value of the road surface angle θr obtained at the time of the stop of the vehicle so that the reference value of the road surface angle θr is close to 0°. The amount of correction may be in the range of, for example, 0.01 to 0.1°.

Further, even when the vehicle starts, the detected value vector of the acceleration sensor316, the motion acceleration vector, and the gravity acceleration vector satisfy the same relationship as the relationship at the time of the stop of the vehicle. Accordingly, if a difference between the square of the magnitude of the detected value vector and the square of the magnitude of the motion acceleration vector after a predetermined time from the start of the vehicle is equal to the square of the magnitude of the gravity acceleration vector, the controller228R2corrects the kept reference value of the road surface angle θr so that the kept reference value of the road surface angle θr is close to 0°. It may be possible to improve the accuracy of the automatic leveling control while suppressing the increase of the control load of the controller228R2, by performing the above-mentioned correction at any one of the time of the start of the vehicle and the time of the stop of the vehicle. Furthermore, if the correction is performed at both the time of the start of the vehicle and the time of the stop of the vehicle, it may be possible to further improve the accuracy of the automatic leveling control.

“After a predetermined time from the start of the vehicle” and “before a predetermined time from the stop of the vehicle” mean time where the above-mentioned determination of whether a road surface is horizontal can be performed on a road surface of which the road surface angle θr is substantially the same as the road surface angle of the road surface of a place where the reference value of the road surface angle Or (which is an object to be corrected) is calculated. That is, when the vehicle starts, it may be possible to substantially determine whether the road surface of which the reference value of the road surface angle θr (which is an object to be corrected) is calculated is horizontal, by performing the determination of whether the road surface immediately after the start of the vehicle is horizontal. Further, when the vehicle stops, it may be possible to substantially determine whether the road surface of which the reference value of the road surface angle θr (which is an object to be corrected) is calculated is horizontal, by performing the determination of whether the road surface immediately before the stop of the vehicle is horizontal. Furthermore, as the result of the determination, if the reference value of the road surface angle θr is not 0° in spite of a horizontal road surface, it means that an error occurs between an actual road surface angle θr and the recorded reference value of the road surface angle θr. Accordingly, the reference value of the road surface angle θr is corrected so as to be close to 0°.

Accordingly, even though the vehicle posture angle θv is changed during the traveling of the vehicle, it may be possible to obtain the reference value of the road surface angle θr considering the change of the vehicle posture angle. Further, since the vehicle posture angle θv is calculated using the corrected reference value of the road surface angle θr, it may be possible to more accurately calculate the vehicle posture angle θv. “After a predetermined time from the start of the vehicle” and “before a predetermined time from the stop of the vehicle” may be appropriately set based on the experiments or simulations of a designer. Furthermore, the determination of whether a road surface is horizontal may be performed so that it is determined that a road surface is horizontal when a state where a difference between the square of the magnitude of the detected value vector and the square of the magnitude of the motion acceleration vector is equal to the square of the magnitude of the gravity acceleration vector continues for a predetermined time, for example, 3 seconds or more.

FIG. 5is a control flowchart of the determination of whether a road surface is horizontal and the correction of a road surface angle at the time of the start of a vehicle in the vehicle lamp system according to the second embodiment. For example, when an automatic leveling control mode is instructed by the light switch304, this flow is repeated at a predetermined timing during the turning-on of the ignition by the controller228R2(irradiation controller228R) and is ended at the time of the turning-off of the ignition. Further, this flow is appropriately combined with the control flow of the first embodiment.

First, the controller228R2determines whether a vehicle has already stopped (S201). If the vehicle has stopped yet (N in S201), the controller228R2ends this routine. If the vehicle has already stopped (Y in S201), the controller228R2determines whether the motion acceleration of the vehicle300is equal to or larger than a predetermined value (S202). If the motion acceleration is smaller than the predetermined value (N in S202), the controller228R2ends this routine. If the motion acceleration is equal to or larger than the predetermined value (Y in S202), the controller228R2determines whether a steering angle is close to 0° (S203).

If a steering angle is not close to 0° (N in S203), the controller228R2ends this routine. If a steering angle is close to 0° (Y in S203), the controller228R2determines whether a road surface is horizontal (S204). Further, the controller228R2determines whether a road surface is horizontal (S205). If the road surface is not horizontal (N in S205), the controller228R2ends this routine. If the road surface is horizontal (Y in S205), the controller228R2corrects the reference value of the road surface angle θr so that the reference value of the road surface angle θr is close to 0° (S206) and ends this routine.

FIG. 6is a control flowchart of the determination of whether a road surface is horizontal and the correction of a road surface angle at the time of the stop of a vehicle in the vehicle lamp system according to the second embodiment. For example, when an automatic leveling control mode is instructed by the light switch304, this flow is repeatedly performed at a predetermined timing during the turning-on of the ignition by the controller228R2(irradiation controller228R) and is ended at the time of the turning-off of the ignition. Further, this flow is appropriately combined with the control flow of the first embodiment.

First, the controller228R2determines whether a vehicle is traveling (S301). If the vehicle is not traveling (N in S301), the controller228R2ends this routine. If the vehicle is traveling (Y in S301), the controller228R2determines whether the motion deceleration of the vehicle300is equal to or larger than a predetermined value (S302). If the motion deceleration is smaller than the predetermined value (N in S302), the controller228R2ends this routine. If the motion deceleration is equal to or larger than the predetermined value (Y in S302), the controller228R2determines whether a steering angle is close to 0° (S303).

If a steering angle is not close to 0° (N in S303), the controller228R2ends this routine. If a steering angle is close to 0° (Y in S303), the controller228R2determines whether vehicle speed is 0 from the detected value of the vehicle speed sensor312(S304). If vehicle speed is not 0 (N in S304), the controller228R2ends this routine. If vehicle speed is 0 (Y in S304), the controller228R2determines whether a road surface is horizontal (S305) and determines whether a road surface is horizontal (S306). If the road surface is not horizontal (N in S306), the controller228R2ends this routine. If the road surface is horizontal (Y in S306), the controller228R2corrects the reference value of the road surface angle θr so that the reference value of the road surface angle θr is close to 0° (S307) and ends this routine.

In the vehicle lamp system200according as described above, the irradiation controllers228L and228R determine whether a road surface is horizontal at least at one timing of the time of the start of the vehicle and the time of the stop of the vehicle and correct the reference value of the road surface angle θr according to the result thereof. For this reason, even though the vehicle posture angle θv is changed during the traveling of the vehicle, it may be possible to obtain the reference value of the road surface angle θr considering the change of the vehicle posture angle. Accordingly, it may be possible to further improve the accuracy of the automatic leveling control.

A vehicle lamp system200according to a third embodiment considers the change of the road surface angle θr that is obtained during the stop of a vehicle in automatic leveling control. This embodiment will be described below. Meanwhile, the main structure of the vehicle lamp system200, the main flow of automatic leveling control, and the shape of light distribution patterns that can be formed are the same as those of the first embodiment. Accordingly, the same elements as the elements of the first embodiment are denoted by the same reference numerals, and appropriately will not be described.

In the first embodiment, the change of a vehicle inclination angle (total angle θ) during the stop of the vehicle is estimated as the change of the vehicle posture angle θv. Accordingly, it may be possible to perform automatic leveling control with high accuracy by a simple control structure. However, although it is rare, the road surface angle θr may be changed during the stop of the vehicle. For example, if a vehicle300is transported or towed by a ship, a carrier, or the like, the road surface angle θr may be changed during the stop of the vehicle. For this reason, if the change of the total angle θ during the traveling of the vehicle is estimated as the change of the vehicle posture angle θv, there is a possibility that an error occurs between an actual vehicle posture angle θv and the estimated vehicle posture angle θv.

Further, in this embodiment, it is determined whether the vehicle posture angle θv obtained from the reference value of the road surface angle θr and the total angle θ is included in a predetermined range, and automatic leveling control is performed or is stopped according to the result of the determination.

If the vehicle posture angle θv calculated from the reference value of the road surface angle θr and the total angle θ detected by the acceleration sensor316exceeds a predetermined range, the controller228R2determines the position of the optical axis of the lamp unit10by the kept reference value of the vehicle posture angle θv. If the calculated vehicle posture angle θv is included in the predetermined range, the controller228R2determines the position of the optical axis by the calculated vehicle posture angle θv. Accordingly, it may be possible to improve the visibility of a driver of a subject vehicle while suppressing a concern that glare is directed at drivers of other vehicles. The “predetermined range” is a range obtained by adding a margin of 0.1° to the range of, for example, a vehicle posture angle θv when a vehicle is empty to a vehicle posture angle θv when the maximum load is applied to a luggage compartment, that is, the range of a vehicle posture angle θv that can be substantially taken by a vehicle300. If the calculated vehicle posture angle θv exceeds this range, it may be possible to estimate that the calculated vehicle posture angle θv is different from an actual vehicle posture angle θv.

Meanwhile, if the calculated vehicle posture angle θv exceeds the predetermined range, the controller228R2may forbid generation of a control signal, which instructs the lamp unit to adjust the position of the optical axis. Specifically, if the calculated vehicle posture angle θv exceeds the predetermined range, the controller228R2stops the generation of a control signal (stops automatic leveling control). Further, the controller228R2notifies a user of the abnormality of automatic leveling control by turning on an indicator (not shown) through the vehicle controller302. Furthermore, the controller228R2generates automatic leveling control-stop-information and records the automatic leveling control-stop-information in the memory228R4. After that, if the automatic leveling control-stop-information is read out from the memory228R4even though automatic leveling control is instructed by the operation of the light switch304or the like, the controller228R2avoids performing automatic leveling control and turns on the indicator. When receiving a reset signal transmitted to the irradiation controller228R through the operation of a switch, the communication of a CAN system at a dealer's maintenance shop, the controller228R2resets the reference value of the vehicle posture angle θv and the reference value of the road surface angle θr to 0°. Further, the controller228R2restores the automatic leveling control to an executable state by erasing or invalidating the automatic leveling control-stop-information. Accordingly, it may be possible to more reliably prevent glare from being directed at drivers of other vehicles.

Moreover, for example, power is not supplied to the irradiation controller228R during the turning-off of the ignition. The controller228R2receives an IG-OFF signal generated from the vehicle controller302during the turning-off of the ignition when the memory228R4is not a nonvolatile memory, or not only the reference value of the road surface angle θr but also the reference value of the vehicle posture angle θv is recorded in a nonvolatile memory (not shown) when a power supply voltage supplied to the irradiation controller228R is equal to or smaller than a predetermined voltage. Accordingly, even though the ignition is turned off, it may be possible to keep the reference value of the vehicle posture angle θv.

While the ignition is turned off, the vehicle300is often transported or towed by a ship, a carrier, or the like. Further, the controller228R2determines whether the calculated vehicle posture angle θv is included in a predetermined range during the turning-on of the ignition, and may perform the above-mentioned control based on the result of the determination.

FIG. 7is a control flowchart of determination of a vehicle posture angle θv in a vehicle lamp system according to a third embodiment. For example, when the automatic leveling control mode is instructed by the light switch304, this flow is repeatedly performed at a predetermined timing during the turning-on of the ignition by the controller228R2(irradiation controller228R) and is ended at the time of the turning-off of the ignition. Further, this flow is appropriately combined with the control flow of the first embodiment.

First, the controller228R2calculates a vehicle posture angle θv from the reference value of the road surface angle θr and the total angle θ (S401), and determines whether the calculated vehicle posture angle θv is out of a predetermined range (S402). If the calculated vehicle posture angle θv is out of the predetermined range (Y in S402), the controller228R2adjusts the optical axis using the recorded reference value of the vehicle posture angle θv (S403) and ends this routine. If the calculated vehicle posture angle θv is in the predetermined range (N in S402), the controller228R2adjusts the optical axis using the calculated vehicle posture angle θv (S404) and ends this routine.

FIG. 8is another control flowchart of determination of a vehicle posture angle θv in the vehicle lamp system according to the third embodiment. For example, when the automatic leveling control mode is instructed by the light switch304, this flow is repeatedly performed at a predetermined timing during the turning-on of the ignition by the controller228R2(irradiation controller228R) and is ended at the time of the turning-off of the ignition. Further, this flow is appropriately combined with the control flow of the first embodiment.

First, the controller228R2determines whether automatic leveling control-stop-information is recorded in the memory228R4(S501). If the automatic leveling control-stop-information is recorded (Y in S501), the controller228R2stops the automatic leveling control and turns on the indicator (S502). Subsequently, the controller228R2determines whether a reset signal is detected (S503). If a reset signal is detected (Y in S503), the controller228R2resets the reference value of the vehicle posture angle θv and the reference value of the road surface angle θr to 0°, erases the automatic leveling control-stop-information, turns off the indicator (S504), and ends this routine. If a reset signal is not detected (N in S503), the controller228R2ends this routine.

If the automatic leveling control-stop-information is not recorded (N in S501), the controller228R2calculates a vehicle posture angle θv from the reference value of the road surface angle θr and the total angle θ (S505) and determines whether the calculated vehicle posture angle θv is out of a predetermined range (S506). If the calculated vehicle posture angle θv is out of the predetermined range (Y in S506), the controller228R2generates automatic leveling control-stop-information and records the automatic leveling control-stop-information in the memory228R4(S507). Further, the controller228R2stops automatic leveling control and turns on the indicator (S502). Subsequently, the controller228R2determines whether a reset signal is detected (S503), resets the reference value of the vehicle posture angle θv and the reference value of the road surface angle θr, erases the automatic leveling control-stop-information, turns off the indicator (S504), and ends this routine.

If the calculated vehicle posture angle θv is in the predetermined range (N in S506), the controller228R2adjusts the optical axis using the calculated vehicle posture angle θv (S508) and ends this routine.

In the vehicle lamp system200according to this embodiment as described above, the irradiation controllers228L and228R determines whether the calculated vehicle posture angle θv is included in the predetermined range. Further, if the calculated vehicle posture angle θv is out of the predetermined range, the irradiation controllers228L and228R performs automatic leveling control using the kept reference value of the vehicle posture angle θv. For this reason, even though the road surface angle θr is changed during the stop of the vehicle, it may be possible to perform the automatic leveling control considering the change of the road surface angle. Accordingly, it may be possible to improve the visibility of a driver of a subject vehicle while suppressing glare directed at drivers of other vehicles. Alternatively, if the calculated vehicle posture angle θv is out of the predetermined range, the irradiation controllers228L and228R stop automatic leveling control. Accordingly, it may be possible to reliably prevent glare from being directed at drivers of other vehicles.

Meanwhile, the vehicle lamp system200according to each embodiment is an aspect of the invention. The vehicle lamp system200includes the lamp units10that can adjust the optical axes O, the acceleration sensor316(inclination detector) that can detect the inclination angle of the vehicle300with respect to the horizontal plane, and the irradiation controllers228L and228R that control the lamp units10. The vehicle lamp system200performs the above-mentioned automatic leveling control by the irradiation controllers228L and228R.

Another aspect of the invention may be the irradiation controllers228L and228R as control devices. The irradiation controllers228L and228R include the receivers228L1and228R1, the controllers228L2and228R2, and the transmitters228L3and228R3, respectively. The receivers228L1and228R1receive the inclination angle of the vehicle300with respect to the horizontal plane from the acceleration sensor316. The controllers228L2and228R2perform the above-mentioned automatic leveling control. The transmitters228L3and228R3transmit the control signals, which are generated by the controllers228L2and228R2, to the leveling controllers236. The irradiation controllers228of the vehicle lamp system200correspond to controllers in a broad sense, and the controllers228L2and228R2of the irradiation controllers228correspond to controllers in a narrow sense.

Further, another aspect of the invention may be the lamp unit10as a vehicle lamp. When the inclination angle of the vehicle300with respect to the horizontal plane is changed during the stop of the vehicle, the position of the optical axis of the lamp unit10is adjusted. When the inclination angle of the vehicle300with respect to the horizontal plane is changed during the traveling of the vehicle, the position of the optical axis of the lamp unit10is maintained.

Furthermore, another aspect of the invention may be a method of controlling the vehicle lamp. When adjusting the optical axis O of the lamp unit10based on the inclination angle, which is detected by the acceleration sensor316, of the vehicle300with respect to the horizontal plane, this method adjusts the position of the optical axis when the inclination angle of the vehicle300with respect to the road surface is changed and maintains the position of the optical axis when the inclination angle of the road surface with respect to the horizontal plane is changed.

The determination of the traveling state of the subject vehicle in each of the above-mentioned embodiments (which includes the determination of whether a vehicle goes straight or the calculation of the motion acceleration of the vehicle300), the determination of the position of the optical axis, and the determination of a light distribution pattern may be performed by any one of the vehicle controller302and the irradiation controllers228. When the irradiation controllers228perform these kinds of determination, information output from various sensors or a navigation system is transmitted to the irradiation controllers228through the vehicle controller302. Further, when the irradiation controllers228perform these kinds of determination, any one or both of the irradiation controllers228L and228R may perform these kinds of determination. Further, the irradiation controllers228may control the leveling actuators226as optical axis adjusters through the leveling controllers236. That is, the irradiation controllers228may function as the leveling controllers236. When the vehicle controller302perform these kinds of determination, the irradiation controllers228control the turning-on/off of the bulbs14, the drive and the like of the swivel actuators222, the leveling actuators226, and the motors238based on the instructions from the vehicle controller302. In this case, the vehicle controller302forms a control device that performs automatic leveling control.

While aspects of embodiments of the present invention have been shown and described above, other implementations are within the scope of the claims. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.