Vehicle headlamp apparatus

In a headlamp apparatus comprising a sub-CPU integrally provided on a headlamp for controlling an optical axis direction changing operation and a main CPU for sending out to the sub-control circuit a control signal for changing the direction of the optical axis, the sub-CPU comprises a power-on resetting circuit of a simple configuration comprising a capacitor and a resistor. When the main CPU detects an abnormality in the sub-CPU, a power supply is temporarily cut off by a power supply control means, and the sub-CPU is reset by a power-on resetting circuit. An abnormality triggered by a runaway of the sub-CPU can be resolved so that the sub-CPU can be restored to a normal condition as quickly as possible.

BACKGROUND OF THE INVENTION

The present invention relates to a headlamp apparatus for vehicles such as automobiles for changing the direction of the light-emitting optical axis of a headlamp by making use of a motor as a drive source, and more particularly to a vehicle headlamp apparatus preferred for use for a headlamp apparatus comprising a light distribution control means, such as the Adaptive Front-lighting System (hereinafter, referred to as AFS), for changing the illuminating direction and range of the headlamp to follow the diving direction of a vehicle.

As an AFS that has been proposed to enhance the driving safety of automobiles, U.S. Published Patent Application 2002-0064051 A1 (published on May 30, 2002) describes a technology proposed by the inventor of this invention. As the concept of the technology is briefly shown inFIG. 1, in this AFS, information indicating the driving conditions of an automobile CAR is detected by a sensor1, and what has been detected is outputted to an electronic control unit (hereinafter, referred to as ECU). As the sensor1, there are provided, for example, a steering angle sensor1A for detecting an angle through which a steering wheel SW of the automobile CAR is steered, a vehicle speed sensor1B for detecting the vehicle speed of the automobile CAR and vehicle height sensors1C for detecting the respective heights of front and rear axles to detect the horizontality (level) of the automobile CAR (only a sensor for a rear axle is shown inFIG. 1), these sensors1A,1B and1C being connected to the ECU. The ECU2controls swivel lamps3R,3L or headlamps3equipped at the front of the automobile on the right- and left-hand sides thereof, respectively, which are adapted for changing their light distributions by controlling the side-to-side change of the illuminating direction of light based on outputs from the respective sensors1. As the swivel lamps3R,3L, there is provided, for example, a headlamp in which a reflector and a projector lamp that are provided in the headlamp are constructed so as to rotate or swivel in horizontal directions and which comprises a rotationally driving means for rotationally driving the reflector and the projector lamp by means of a drive source such as a driving motor. The mechanism including the rotationally driving means is referred to as an actuator herein. According to the AFS of this type, when the automobile is driven on a curved road, the road surface ahead of a curve on the curved road can be illuminated according to the driving speed of the automobile, and thus, the AFS is effective when attempting to enhance the driving safety of the automobile.

When there occurs in this AFS a defect that the direction of the optical axis of the headlamp cannot be changed properly, that is, when there occurs a defect that the illuminating direction of the headlamp cannot be controlled with the illuminating direction of the headlamp being kept shifted either leftward or rightward relative to the straight-ahead running direction of the automobile, the foreground of the automobile cannot be illuminated when the automobile drives straight ahead or takes a turn at an opposite bend to the direction in which the reflector and the projector lamp are kept shifted, whereby the driving safety is deteriorated. Alternatively, when there occurs a defect that the illuminating direction continues to change side to side, there may be caused a risk that drivers of oncoming vehicles and/or vehicles in the vicinity of the subject vehicle are dazzled and are then put to dangerous conditions. While the following cases are considered as reasons for triggering the defects: there occurs a certain defect in the sensors1, and no outputs from the sensors1cannot be inputted into the ECU2; there occurs a certain defect in the ECU2; and there occurs a certain defect in the actuators of the respective swivel lamps3R,3L, most of the defects are triggered when a main control circuit such as a microcomputer incorporated in the ECU2or sub-control circuits integrally provided on the actuators of the respective swivel lamps3R,3L runs away.

When the AFS fails due to the runaway of the main control circuit or the sub-control circuits, since the normal condition can be restored from the failing condition immediately the control circuits are reset, it is considered that a reset circuit is provided on the main control circuit and/or the sub-control circuits. In particular, in case an automatic reset circuit is provided for automatically implementing an automatic reset operation based on a signal which has detected a defect, the control circuit can be reset immediately the defect occurs so as to be recovered from the problematic condition. Since the main control circuit having the ECU2can be placed at an appropriate position on the vehicle, as shown inFIG. 1, and there is little limitation imposed on the external size and capacity of the ECU2, it is relatively easy to incorporate the automatic reset circuit in the main control circuit. However, since the actuator having the sub-control circuit needs to be incorporated in the swivel lamp3R,3L, the external configuration and capacity of the actuator are subjected to a certain restriction, and therefore, it is difficult to provide the automatic reset circuit that is provided on the main control circuit on the sub-control circuit. Due to this, once a defect occurs, it becomes difficult to get recovered from a problematic condition quickly by automatically resetting the sub-control circuit.

SUMMARY OF THE INVENTION

An object of the invention is to provide a vehicle headlamp apparatus which enables an automatic reset of the sub-control circuit only by providing a simple power-on resetting circuit on the sub-control circuit so that the AFS can get recovered from a problematic condition as quickly as possible.

According to an aspect of the invention, there is proposed a vehicle headlamp apparatus having an optical axis direction changing means for changing the direction of a light-emitting optical axis of a headlamp of a vehicle, the vehicle headlamp apparatus comprising a sub-control circuit provided integrally on the headlamp for controlling the optical axis direction changing means and a main control circuit for sending out to the sub-control circuit a control signal for changing the direction of the optical axis of the headlamp, wherein the sub-control circuit comprises, in turn, a power-on resetting circuit for implementing a reset by switching on and off a power supply, and wherein the main control circuit comprises, in turn, a power supply control means for temporarily cutting off the supply of power to the sub-control circuit when the main control circuit detects an abnormality of the sub-control circuit. In addition, the main control circuit makes the power supply control means to continue to maintain the power supply cut off state when the main control circuit detects an abnormality in the sub-control circuit again after the power supply control means has been activated.

In the invention, the main control circuit sends out a request-a-reply signal to the sub-control circuit and activates the power supply control means when no appropriate reply signal to the request-a-reply signal is sent back from the sub-control circuit. Alternatively, the main control circuit activates the power supply control means when a reply signal is sent thereto from the sub-control circuit to which no request-a-reply signal has been sent out therefrom.

According to the invention, with the power-on resetting circuit of a simple construction comprising a capacitor and a resistor being provided on the sub-control circuit, when the main control circuit detects an abnormality in the sub-control circuit, in the event that the supply of power to the sub-control circuit is cut off once by the power supply control means, the sub-control circuit can be reset by the power-on resetting circuit, so that the abnormality triggered due to the runaway of the sub-control circuit can be resolved, and the AFS is allowed to get recovered as quickly as possible from a problematic condition triggered by the abnormality of the sub-control circuit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, an embodiment of the invention will be described by reference to the accompanying drawings.FIG. 2is a vertical view of an internal construction of a headlamp comprising, among the constituent elements of the AFS shown as a lamp angle change control means inFIG. 1, the swivel lamp which can change the illuminating direction thereof side to side, andFIG. 3is a partially exploded perspective view of a main part of the swivel lamp. A lens12is mounted in a front opening and a rear cover13is mounted in a rear opening in a lamp body11, respectively, whereby a lamp chamber14is formed, and a projector lamp30is disposed in the lamp chamber14. The projector lamp30includes a sleeve301, a reflector302, a lens303and a light source304which are integrated into a single unit, and since the project lamp so constructed has already been in wide use, a detailed description thereof will be omitted here only with a single remark that a light source employing a discharge bulb is used for the light source304. The projector lamp30is supported on a substantially U-shaped bracket31. In addition, an extension15is disposed around the periphery of the projector lamp30in the lamp body11so that the interior of the lamp body11is not exposed to the outside through the lens12. Furthermore, in this embodiment, a bottom cover mounted in a bottom opening in the lamp body11is utilized in installing therein an illuminating circuit7for illuminating the discharge bulb of the projector lamp30.

The projector lamp30is supported in a state in which the projector lamp30is held between a lower plate312and an upper plate313which are both formed by being bent substantially at right angles from a vertical plate311of the bracket31. An actuator4, which will be described later on, is fixed to a lower side of the lower plate312with screws, and a rotational output shaft448of the actuator4protrudes upwardly through a shaft hole315opened in the lower plate312. The screws314are fixedly screwed into bosses318provided on the lower side of the lower plate312in such a manner as to protrude therefrom. Then, a shaft portion305provided on an upper surface of the projector lamp30is fitted in a bearing portion316provided on the upper plate313, and a connecting portion306provided on a lower surface of the projector lamp30is fitted on the rotational output shaft448of the actuator4for connection, whereby the projector lamp30is allowed to rotate in leftward and rightward directions relative to the bracket31, and, as will be described later on, is designed to be operated to rotate in horizontal directions together with the rotational output shaft448as the actuator4operates.

Here, as viewed from the front, aiming nuts321,322are integrally mounted on the bracket31at top left- and right-hand side corner portions thereof, and a leveling bearing portion323is integrally mounted on a bottom right-hand side corner portion, so that a horizontal aiming screw331and a vertical aiming screw332which are rotatably supported on the lamp body11are screwed into the aiming nuts321,322, respectively, and a leveling pole51of a living mechanism5is fitted in the leveling bearing portion323. Then, by operating the horizontal aiming screw331and the vertical aiming screw332to rotate, the bracket31is allowed to rotate horizontally and vertically. In addition, by moving the leveling pole51axially back and forth by the leveling mechanism5, the bracket31is allowed to rotate vertically. Thus, an aiming adjustment and a leveling adjustment are enabled through these operations, the aiming adjustment being intended to adjust the optical axis of the projector lamp30horizontally and vertically and a leveling adjustment to adjust the, optical axis of the projector lamp30vertically according to the leveling conditions of a vehicle which change in association with a change in vehicle height. In addition, a projection307is provided on a lower side of the reflector302of the projector lamp30in such a manner as to protrude therefrom, and a pair of stoppers are cut and erected from the lower plate312of the bracket31at left- and right-hand side positions thereon which correspond to the projection so provided, so that the rotational range of the projector lamp30is restricted when the projection307is brought into collision contact with either of the stoppers317as the projector lamp30rotates.

FIG. 4is an exploded perspective view of a main part of the actuator4for swiveling the swivel lamp3R,3L,FIG. 5is a plan view showing the construction of the actuator assembled together, andFIG. 6is a longitudinal sectional view of the assembled actuator. A case41is made up of an upper half41U and a lower half41D which are each formed into a substantially pentagonal disc-like shape, and when a plurality of projections410provided on a circumferential surface of the lower half41D in such a manner as to protrude therefrom and a plurality of fitting pieces411provided on a circumferential surface of the upper half41U in such a manner as to suspend downwardly therefrom are brought into fit engagement with each other, a case chamber is formed inside the upper half41U and the lower half41D so fitted together. In addition, supporting pieces412,413are formed on sides of the upper half41U and the lower half41D in such a manner as to protrude horizontally outwardly therefrom for use in fixing the case41to the bracket31by screwing the screws314into the bosses318on the bracket31through the supporting pieces412,413as has been described before. In addition, the splined rotational shaft448is caused to protrude from an upper surface of the case41for connection to the connecting portion306formed on the bottom surface of the projector lamp30. Additionally, a connector451is disposed on a back of the case41so that an external connector21(refer toFIG. 2) which is connected to the ECU2is designed to be connected thereto.

Four hollow bosses414,415,416,417are provided on an inner bottom surface of the case41at predetermined positions in such a manner as to erect therefrom, and a brushless motor42, which will be described later on, is assembled onto the first hollow boss414as a drive motor. In addition, as will be described later on, respective shafts of a gear mechanism44are inserted into the second to fourth hollow bosses415,516,417to be supported therein. Additionally, a printed circuit board45is placed on a staged rib418formed along a circumferential edge of the inner bottom surface of the lower half41D and is installed to be supported within the case41while being held between the upper half41U and the lower half41D. The brushless motor42is electrically connected to this printed circuit board45, and various types of electronic components, not shown, which function as part of a control circuit43, which will be described later on, and the connector451are installed on the printed circuit board45.

As shown inFIG. 6, the brushless motor42is constructed such that a stator coil424including three pairs of coils which are disposed at regular intervals in a circumferential direction is fixedly supported on the first hollow boss414on the lower half41D and is then electrically connected to the printed circuit board45so as to be fed. In addition, a cylindrical container-like rotor426is fixedly mounted on an upper end portion of a rotational shaft423which is rotatably supported on the first hollow boss414by a thrust bearing421and a sleeve bearing422in such a manner as to cover the stator coil424. This rotor426includes a cylindrical container-like yoke427formed from a resin and an annular rotor magnet428which is fixedly mounted on an inner circumferential surface of the yoke427and which is magnetized in such a manner that S and N poles alternate in a circumferential.

The brushless motor42constructed as has been described above is designed to change the direction of a magnetic force between the stator coil424and the rotor magnet428by supplying alternating currents having U, V and W phases which are different from one another to thereby drive to rotate the rotor426and the rotational shaft423. Furthermore, as shown inFIG. 7, three Hall elements H1, H2, H3are arranged and supported on the printed circuit board45at predetermined angular intervals in a circumferential direction of the rotor426, and when the rotor magnet428is rotated together with the rotor426, magnetic fields in the respective Hall elements H1, H2, H3are changed, and on and off conditions of the respective Hall elements H1, H2, H3are then changed, whereby a pulse signal is designed to be outputted in which an H level and an L level are changed periodically in response to the rotational cycle of the rotor426.

A first gear wheel441is integrally formed on the yoke427of the rotor426from a resin, and this first gear wheel441constitutes part of the gear mechanism44. The gear mechanism44transmits the rotational force of the first gear wheel441, while sequentially decelerating it, to a second large-diameter gear wheel443aand a second small-diameter gear wheel443bof a second gear wheel443rotatably supported on a first stationary shaft442, a third large-diameter gear wheel445aand a small-diameter gear wheel445bof a third gear wheel445rotatably supported on a stationary shaft444and a sector gear wheel447integrally formed on the rotational output shaft448and which is rotatably supported on a third stationary shaft446. In addition, stoppers419are formed on the inner bottom surface of the lower half41D at positions thereon corresponding to both ends of rotational directions of the sector gear wheel447in such a manner as to protrude therefrom for collision contact with respective end portions of the sector gear wheel447so as to restrict the total rotational angle range of the sector gear wheel447or the rotational output shaft448. Note that the total rotational angle range of the sector gear wheel447is set to become slightly larger than the total rotational angle range of the projector lamp30that is restricted by the projection307and the stoppers317.

FIG. 7is a block diagram showing an electric circuit configuration of an illumination system including the ECU2and the actuator4. Note that the actuator4is installed in each of the left and right swivel lamps3R,3L of the automobile and is allowed to communicate with the ECU2bilaterally. The ECU2includes a main CPU201as a main control circuit for implementing a process with a predetermined algorithm based on information from the sensors1so as to output a required control signal C0and an interface (hereinafter, referred to as I/F) circuit202for inputting and outputting the control signal C0between the main CPU201and the actuator4. As will be described later on, here, the control signal C0has a left and right direction change angle signal DS indicating optical axes direction change angles of the swivel lamps3R,3L which is sent to the actuators4and a request-a-replay signal RS for detecting a defect. The main CPU201has there in an abnormality detecting unit203for detecting a defect using a programmed software and, as will be described later on, detects a defect according to a reply condition from a sub-CPU431. In addition, an automatic reset circuit204is additionally provided in the main CPU201so that the main CPU201can automatically be reset. Furthermore, a power supply control circuit205is provided in the ECU2, so that power supplied to the actuator4can be cut off temporarily or continuously through the control by the main CPU201. In addition, on and off signals from a lighting switch S1provided on the automobile can be inputted into the ECU2, so that the swivel lamp3R,3L can be switched between on and off by controlling based on the on and off of the lighting switch S1the illuminating circuit7for supplying power to the discharge bulb304of the projector lamp30when connected to an on-board power supply, not shown, by a control signal N. Additionally, the main CPU201controls by a leveling signal DK a leveling control circuit6for controlling the leveling mechanism5for vertically adjusting the optical axis of the bracket31which supports the projector lamp30, so that the optical axis of the projector lamp30can be adjusted as the height of the automobile changes. Note that it goes without saying that connections of these electric circuits to the power supply are switched on and off by an ignition switch S2for switching on and off electric systems provided on the automobile.

The sub-control circuit43configured on the printed circuit board45installed within the actuator4provided in each of the swivel lamps3R,3L includes an I/F circuit432for inputting and outputting signals from and to the ECU2, a sub-CPU431for implementing a process with a predetermined algorithm based on a signal inputted from the I/F circuit432and pulse signals P outputted from the Hall elements H1, H2, H3and a motor drive circuit434for rotationally driving the brushless motor42which functions as a rotationally driving means. A power-on resetting circuit437to which an onboard power supply is supplied via the power supply control circuit205of the ECU2is additionally provided in the sub-CPU431, so that the sub-CPU431is reset when the power supply to the power-on resetting circuit437is cut off. Although not shown, since it can be made up of a capacitor and a resistor, the power-on resetting circuit is, in reality, integrally assembled onto the printed circuit board45which configures the sub-control circuit43. In addition, the sub-CPU431is configured so as to send out to the ECU2an operating condition signal JS which indicates the operating condition of the sub-CPU431.

FIG. 8is a circuit diagram typically showing the motor drive circuit434of the control circuit43and the brushless motor42in the actuator4. The motor drive circuit434includes a switching matrix circuit435to which a speed control signal V, start/stop signal S, forward rotation/backward rotation signal Rare inputted from the sub-CPU431of the control circuit43as control signals and pulse signals are inputted from the three Hall elements H1, H2, H3, and an output circuit436for adjusting phases of powers in three phases (U phase, V phase, W phase) supplied to the three pairs of coils of the stator coil424of the brushless motor42when receiving an output from the switching matrix circuit435. In this motor drive circuit435, by supplying powers in U phase, V phase and W phase to the stator coil424, the magnet rotor428rotates, and then, the yoke427which is made integral with the magnet rotor428, that is, the rotor426and the rotational shaft423rotate. When the magnet rotor428rotates, the Hall elements H1, H2, H3detect changes in magnetic field and output pulse signals P, which are then inputted into the switching matrix circuit435, where a switching operation at the output circuit436is implemented to the timings of the pulse signals, whereby the rotor426is allowed to continue rotating.

According to the configuration as has been described heretofore, with the ignition switch S2on and also the lighting switch S1on, as shown inFIG. 1, when information on an angle through which the steering wheel SW of the automobile is steered, the speed of the automobile and the height of the automobile is inputted into the ECU2from the sensors1, the ECU2implements an operation at the main CPU201based on the sensor outputs which have been inputted into the ECU2, calculates a left and right direction change angle signal DS of the projector lamp30in each of the swivel lamps3R,3L of the automobile and outputs the left and right direction change angle signal DS so calculated to the actuator4in each of the respective swivel lamps3R,3L. In the actuator4, the sub-CPU431implements an operation by the left and right direction change angle signal DS so inputted into the actuator4to calculate a signal corresponding to the left and right direction change angle signal DS and then outputs the signal so calculated to the motor drive circuit434to thereby rotationally drive the brushless motor42. Since the rotational driving force of the brushless motor42is decelerated by the gear mechanism44for transmission to the rotational output shaft448, the projector lamp30connected to the rotational output shaft448rotates horizontally, and the direction of the optical axis of the swivel lamp3R,3L is changed horizontally. When the projector lamp30rotates, the direction change angle of the projector lamp30is detected from the rotation angle of the brushless motor42. Then, the sub-CPU431compares the direction change angle detection signal so detected with the left and right direction change angle signal DS inputted from the ECU2and feedback controls the rotation angle of the brushless motor2in such a manner that the two signals coincide with each other, so that the direction of the optical axis of the projector lamp30, that is, the direction of the optical axis of the swivel lamp3R,3L can be controlled with high accuracy to be situated at a direction change position which is set by the left and right direction change angle signal DS.

Thus, through the direction changing operation on the projector lamps30, the directions of the axes of beams of light emitted from the both swivel lamps3R,3L are changed and the beams of light whose directions are so changed illuminate areas which are horizontally out of the straight-ahead running direction of the automobile, whereby not only the foreground straight-ahead of the moving automobile but also the foreground in a direction in which the automobile is steered can be illuminated, thereby making it possible to enhance the driving safety of the automobile.

Next, operations of the vehicle headlamp apparatus when a defect occurs in the ECU2and the actuator4will be described below. As to the ECU2, the main CPU201monitors its own operating conditions at all times, and when the ECU2detects an abnormality therein, the ECU2resets itself by the automatic reset circuit204, whereby, for example, in the event that an abnormal signal is inputted from the sensors1and the actuator4to make the main CPU201run away, a reset is applied immediately and the ECU2can be restored to its normal condition.

On the other hand, a case where an abnormality occurs in the actuator4will be described below.FIG. 9Ais a timing chart when signals are sent and received at the normal time. In addition,FIG. 10is a flowchart illustrating a flow of detecting an abnormality, as well as a flow of operations taken to deal with the abnormality so detected. In these diagrams, the main CPU201sends out the left and right direction change angle signal DS to the sub-CPU431in each actuator4in each swivel lamp3R,3L on a predetermined cycle and sends out a request-a-replay signal RS to one and the other actuator alternately. For example, in the same figure, firstly, a reply requesting signal RS is sent to the right swivel lamp3R in time series (S101). Then, keep queuing for a predetermined length of time and wait until an operating condition signal JS is received from the actuator4(S102). When an operating condition signal JS indicating the operating condition of the actuator4is sent back from the sub-CPU431while queuing, the main CPU201receives this operating condition signal JS (S103). The abnormality detecting unit203within the main CPU201determines that the operating condition of the actuator4is normal from the fact that the operating condition signal JS has been received properly (S105), and thereafter, realizes a proper and normal optical axis direction changing operation (S106). Similarly, next, a reply requesting signal RS is sent to the sub-CPU431in the left swivel lamp3L and realizes a proper optical axis direction changing operation when receiving a return of an operating condition signal JS.

Incidentally, in the event that there occurs a defect in the actuator4, whereby the sub-CPU431is brought to a runaway state, as has been described previously, the proper control of the AFS becomes impossible. In this case, the runaway of the sub-CPU431is stopped in the following manner.FIG. 9Bis a timing chart of sending and receiving signals when a first abnormality occurs. Referring to the flowchart shown inFIG. 10again, similarly to when it is normal, the main CPU201sends out the left and right direction change angle signal DS to the sub-CPUs431of the actuators4in the left and right swivel lamps3R,3L on the predetermined cycle and also sends out a request-a-reply signal RS to one and the other actuator alternately (S101). In the same figure, the request-a-reply signal RS is first sent to the right swivel lamp3R in time series. Then, the main CPU201queues a predetermined length of time (S102), and if no operating condition signal JS indicating the condition of the actuator4is sent back from the sub-CPU431while the main CPU201is queuing and hence the main CPU201can receive no operating condition signal JS (S103), the main CPU201then detects that the sub-CPU431is running away and hence that the actuator4is abnormal (S107). Then, when detecting the abnormality, the main CPU201controls the power supply control means205to cut off the power supply supplied to the actuator4temporarily (S108), whereby the power-on resetting circuit437is activated in the actuator4in question so as to reset the sub-CPU431(S109). The runaway of the sub-CPU431is stopped by this reset. The same operation is carried out to the left swivel lamp3L. Thus, the actuator4is brought back to the normal operation by resetting the sub-CPU431in that manner, and thereafter, the actuator4realizes a proper optical axis direction changing operation by signals DS, RS from the main CPU201.

In addition, despite the fact that the sub-CPU431has been reset by carrying out the runaway stopping operation as has just been described, if the abnormality of the actuator4continues to be detected by the abnormality detecting unit203of the main CPU201(S110), the main CPU201determines that the abnormality is not being caused by the runaway of the sub-CPU431, in which case the power supply control circuit205is made to continue cutting off the power supply to the power-on resetting circuit437(S111), whereby the sub-CPU431is activated in no case, and the optical axis direction changing operation by the actuator4is stopped. As this occurs, a fail safe is executed in the actuator4in which the optical axis is reset to the initial position (S112), whereby the continuation of the abnormal condition of the AFS can be prevented.

FIG. 9Cis a timing chart of sending and receiving signals when a second abnormality occurs. Here, referring to a flowchart shown inFIG. 11, there is described, for example, a case where only a left and right direction change angle signal DS is sent out and no request-a-reply signal RS is sent out. Thus, despite the fact that no request-a-reply signal RS is sent out (S101), in case an operating condition signal JS indicating the condition of the actuator4is sent back from the sub-CPU431within the predetermined cycle time and the main CPU201receives the operating condition signal JS (S102, S104), the main CPU201detects that the relevant sub-CPU431is running away and hence that the actuator4is abnormal (S107). In contrast, if no operating condition signal JS is received, then, the main CPU201determines that the actuator4is normal, whereby a normal optical axis direction changing operation is carried out (S106). Then, when the main CPU201detects an abnormality in the actuator4, as with the case of the first abnormality, the main CPU201controls the power supply control means205to cut off the power supply being supplied to the actuator4temporarily (s108), whereby the power-on resetting circuit437is activated in the actuator4in question to thereby reset the sub-CPU431(S109). The sub-CPU431is prevented from running away by this reset. By resetting the sub-CPU431like this, the actuator4is brought back to the normal operation, and thereafter, the actuator4realizes a normal optical axis direction changing operation by signals DS, RS sent from the main CPU201.

Note that also in the case of the second abnormality, if the main CPU201continues to detect the abnormality of the actuator4despite of the fact that the sub-CPU431has been reset (S110), as with the case of the first abnormality, the power supply control circuit205is caused to continue cutting off the power supply to the power-on resetting circuit437(S111) so that the sub-CPU431is not activated, and a fail safe is then executed (S112).

In addition, although not shown, in the case of the second abnormality, for example, if no operating condition signal JS is sent back from the actuator4of the right swivel lamp3R in question but from the actuator4of the left swivel lamp3L despite the fact that the main CPU201sends out a request-a-reply signal RS to the actuator4of the right swivel lamp3R, a similar determination is made. That is, in this case, since both the left and right actuators4can be determined to be running away, the main CPU201may only have to temporarily cut off the power supply to both the left and right actuators431to thereby execute power-on resetting operations.

Thus, in the sub-CPU431provided in the actuator4, the sub-control circuit43may only have to be configured by installing the power-on resetting circuit437of a simple configuration comprising a capacitor and a resistor on the printed circuit board45, whereby even in the limited space within the actuator4, an environment can be arranged in which the sub-CPU431can be reset. Then, the runaway of the sub-CPU431in the actuator4is detected by the CPU201of the ECU2, and based on this detection, the power supply to the actuator4is temporarily cut off by the power supply control circuit205provided in the ECU2, whereby the runaway of the sub-CPU431can be stopped by resetting the sub-CPU431in a similar manner to a reset by an automatic resetting circuit. Consequently, a defect in the AFS can be removed as quickly as possible so as to restore the normal condition therein, whereby a safe optical axis direction changing control can be ensured.

Note that while the example has been described in the embodiment in which the invention is applied to the headlamp in which the direction of the projector lamp constituting the swivel lamp is horizontally changed to thereby change the light-emitting optical axis thereof, the invention may be applied to a headlamp configuration in which only a reflector is operated so as to change the direction thereof or a headlamp configuration in which an auxiliary reflector provided independently from a main reflector is operated so as to change the direction thereof to thereby change the substantial illuminating range of the headlamp.

As has been described heretofore, according to the invention, with the power-on resetting circuit of a simple configuration comprising a capacitor and a resistor being provided in the sub-control circuit provided in the actuator, when the main control circuit detects an abnormality in the sub-control circuit, in the event that the power supply to the sub-control circuit is temporarily cut off by the power supply control means, the sub-control circuit can be reset by the power-on resetting circuit, whereby the abnormality triggered by the runaway of the sub-control circuit can be resolved so that the sub-control circuit can be restored to the normal condition. From this configuration, even in the event that there is not too sufficient a space for the actuator, the sub-control circuit can be restored to the normal condition from the abnormal condition by resetting it, thereby making it possible to allow the AFS to get recovered from the defect condition as quickly as possible.