Patent Publication Number: US-2004046508-A1

Title: Vehicle head lamp apparatus

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to a head lamp device used for a vehicle such as an automobile. More particularly, the present invention relates to a vehicle head lamp apparatus capable of judging an abnormality of a drive means for driving a light distribution means of the head lamp device, wherein the light distribution means changes an irradiation direction and an irradiation range of the head lamp according to a state of running of the vehicle. For example, the present invention relates to a vehicle head lamp apparatus having the Adaptive Front-lighting System which will be referred to as AFS, hereinafter.  
       [0002] As shown in the conceptional view of FIG. 1, in AFS which is proposed to enhance the safety property of driving an automobile, information expressing a state of running of an automobile CAR is detected by the sensor  1 , and the thus obtained detection output is outputted into the electronic control unit  2  which will be referred to as ECU (Electronic Control Unit, hereinafter. For example, this sensor  1  includes: a steering angle sensor  1 A for detecting a steering angle of steering wheel SW of automobile CAR; a vehicle speed sensor  1 B for detecting a vehicle speed of automobile CAR; and vehicle level sensors (Only the vehicle level sensor  1 C of the rear axle is shown in the drawing.) for detecting levels of the front and rear axles so as to detect a level of an automobile CAR. These sensors  1 A,  1 B,  1 C are connected with ECU described before. According to the output of each sensor  1 , which has been inputted into ECU  2 , the swivel lamps  3 R,  3 L, which are respectively provided in the head lamps  3  arranged at the right and the left front portion of the automobile, are controlled being deflected to the right and left, that is, the swivel lamps  3 R,  3 L are controlled being deflected to the right and left so that the light distribution characteristic can be changed. As an example of the swivel lamp  3 R,  3 L, there is provided a head lamp having a rotation drive means for rotating a reflector or a projector lamp, which is arranged in the head lamp, in the horizontal direction by a drive power source such as a drive motor. A mechanism including this rotation drive means is referred to as an actuator in this specification. When this type AFS is adopted, while an automobile is running on a curved road, it is possible to illuminate a far side of the curved road corresponding to the running speed of the automobile. Therefore, the safety property of running can be enhanced.  
       [0003] In order to realize an appropriate illumination in this AFS, it is necessary for the steering angle of steering wheel SW to properly correspond to the deflection angle of the swivel lamp  3 R,  3 L. When the steering angle of steering wheel SW does not properly correspond to the deflection angle of the swivel lamp  3 R,  3 L, the optical axis of the swivel lamp  3 R,  3 L is directed to an undesirable direction with respect to the running direction of the automobile, for example, the head lamp can not illuminate the forward portion of the road when the automobile is running straight or the automobile is running on a curved road. Alternatively, the head light is deflected onto the opposed lane side, so that an opposed automobile is dazzled by the light from the head lamp, which causes problems from the viewpoint of safety of running.  
       [0004] In order to avoid the occurrence of the above problems, in the conventional AFS, there is provided a deflection angle detector for detecting a deflection angle of the actuator of the swivel lamp. For example, a potentiometer is arranged in an output shaft of the rotation drive means for driving the swivel lamp, and a rotation angle of the output shaft is detected from the output of the potentiometer, that is, the deflection angle is detected. However, when the above potentiometer is arranged, the structure of the actuator becomes complicated and further the size of the actuator is increased, that is, provision of the above potentiometer is not preferable. In order to solve the above problems, it is considered to detect a deflection angle of the swivel lamp by detecting a rotary angle of the drive motor which is a drive source to drive the rotation drive means for driving the actuator. As the rotary angle detector used for the object, a Hall element is used which outputs the number of pulses according to the rotation of the drive motor. That is, when pulse signals emitted from the Hall element according to the rotational motion of the drive motor are counted, the deflection angle of the actuator is indirectly detected, so that AFS can be appropriately controlled.  
       [0005] In the case of AFS described above, it is possible to appropriately control AFS according to the counted values of the pulse signals sent from the Hall element. However, in the case where the drive motor of the rotation drive means or the gear mechanism develops trouble, the counted values of the pulse signals of the Hall element do not correspond to the deflection angle of the swivel lamp. Therefore, AFS can not be properly controlled. Accordingly, it is necessary to monitor the rotation drive means at all times. Examples of trouble of the rotation drive means are: the drive motor is locked and can not be rotated at all; some gears are damaged in the gear mechanism for reducing the speed and transmitting the torque of the drive motor, and it becomes impossible to obtain a normal reduction ratio by the gear mechanism; and gears meshing with each other in the gear mechanism are seized to each other, and it becomes impossible for the drive motor and the gear mechanism to be normally rotated. In either case described above, the counted values of the pulse signals of the Hall element and the deflection angle of the swivel lamp do not correspond to each other. Accordingly, it is impossible to obtain a normal AFS motion.  
       [0006] In this case, as described above, when the counted values of the pulse signals of the Hall element are monitored, it possible to judge the occurrence of an abnormality of the rotational state of the drive motor, however, the following problems may be encountered. Even when the drive motor is normally operated, if the gear mechanism develops trouble, the rotation drive means can not be properly operated, and at the same time the rotation of the drive motor is affected. Therefore, when the occurrence of an abnormality is judges according to the counted values of the pulse signals, it is impossible to judge whether the abnormality of the rotation drive means is caused by the motor or the abnormality of the rotation drive means is caused by the gear mechanism which is arranged after the drive motor. As a result, an appropriate maintenance work for recovering AFS, which has developed trouble, can not be executed, that is, AFS can not be properly controlled. In this connection, the official gazette of JP-A-64-74137 discloses the following technique. In a cornering lamp system for vehicle use, when an irradiating direction of the head lamp means exceeds the maximum angular position, electric power supply to an electric motor to drive the head lamp means is stopped under the condition that electric power supply to the inverse direction of the electric motor can be conducted, so that the occurrence of burning trouble caused by motor lock can be prevented. The official gazette of JP-A-62-244220 discloses the following technique. In a cornering lamp system, when the supply of a starting signal to a step drive type motor to control an irradiating direction of the head lamp means is stopped after a predetermined period of time has passed, trouble of burning of the motor can be prevented. However, in the former prior art, the irradiating direction is detected by a different means from the motor. Therefore, it is difficult to detect trouble in the system only by the occurrence of an abnormality of in the motor. The latter prior art is effective to previously prevent the occurrence of trouble of burning of the motor. However, it is difficult to detect the occurrence of an abnormality in the system. Accordingly, even if the above prior arts are applied to AFS, it is difficult to conduct a proper maintenance work to solve the problems caused in AFS. Therefore, even if the above prior arts are applied to AFS, it is difficult to solve the problems described before in the present application.  
       [0007] SUMMARY OF THE INVENTION  
       [0008] It is an object of the present invention to provide a vehicle head lamp apparatus in which AFS can be properly controlled when a cause of trouble in an actuator rotation drive means in AFS is properly judged.  
       [0009] The present invention provides a vehicle head lamp apparatus comprising: a light distribution control means for controlling an irradiation direction or an irradiation range of light sent from a light source; a rotation drive means having a drive motor for driving the light distribution control means; a rotation range detection means for detecting a rotation range of the drive motor; and an abnormality judgment means for judging an abnormality of the rotation drive means according to a rotation range of the drive motor detected by the rotation range detection means when the rotation drive means is driven under a predetermined condition.  
       [0010] In this case, the abnormality judgment means judges an abnormality under the predetermined condition by comparing a rotation range, which is obtained when the drive motor is rotated in one direction and then rotated in the opposite direction, with a predetermined rotation range. Alternatively, the abnormality judgment means judges an abnormality under the predetermined condition by comparing one of the rotation ranges, one range is obtained when the drive motor is rotated in one direction and the other rotation range is obtained when the drive motor is rotated in the opposite direction, with a predetermined rotation range which is previously set, and when the rotation range is larger than the predetermined rotation range which is previously set, the rotation is judged to be abnormal. It is preferable that the abnormal judgment means repeats a judgment motion when it has judged an abnormality.  
       [0011] The head lamp device of the present invention includes: a rotation range detection means for detecting a rotation range of a drive motor of a rotation drive means for driving a light distribution control means of a head lamp; and an abnormality judgment means for judging an abnormality of the rotation drive means according to a rotation range of the drive motor detected by the rotation range detection means when the rotation drive means is driven under a predetermined condition. Therefore, it is possible to judge the occurrence of an abnormality when the drive motor or the gear mechanism composing the rotation drive means develops trouble. Further, it is possible to judge a specific cause of the trouble. Therefore, in the case of an abnormality of AFS, fail-safe operation can be realized. Accordingly, an automobile can be safely driven and a proper maintenance work can be executed even when an abnormality is caused. Further, it is possible to properly control AFS.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012]FIG. 1 is a view showing a conceptional arrangement of AFS;  
     [0013]FIG. 2 is a longitudinal sectional view showing a swivel lamp;  
     [0014]FIG. 3 is an exploded perspective view showing a primary portion of the internal structure of a swivel lamp;  
     [0015]FIG. 4 is an exploded perspective view showing a portion of an actuator;  
     [0016]FIG. 5 is a plan view showing an arrangement of an actuator;  
     [0017]FIG. 6 is a longitudinal sectional view showing an actuator;  
     [0018]FIG. 7 is a partially enlarged perspective view showing a brushless motor;  
     [0019]FIG. 8 is a block diagram showing a circuit structure of AFS;  
     [0020]FIG. 9 is a circuit diagram showing a circuit structure of an actuator;  
     [0021]FIG. 10 is a flow chart for detecting an abnormality of an actuator when an ignition switch is turned on;  
     [0022]FIG. 11 is a schematic illustration showing a relation between a counted value of an up and down counter and a rotation range value; and  
     [0023]FIG. 12 is a flow chart of another embodiment for detecting an abnormality of an actuator. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0024] Next, referring to the drawings, an embodiment of the present invention will be explained below. FIG. 2 is a longitudinal sectional view showing an internal structure of the head lamp  3  composed of the swivel lamps  3 R,  3 L, the irradiating directions of which can be deflected to the right and left, in the components of AFS which are a lamp deflection angle control means of the present invention shown in FIG. 1. FIG. 3 is a partially exploded perspective view showing the primary portion. The lens  12  is attached to a front opening of the head lamp device body  11 , and the rear cover  13  is attached to a rear opening of the head lamp device body  11  so that the lighting chamber  14  is formed. In this lighting chamber  14 , there is provided a projector lamp  30 . In the projector lamp  30 , the sleeve  301 , the reflector  302 , the lens  303  and the light source  304  are integrated into one body. Since this the projector lamp  30  has been used widely, the detailed explanations are omitted here. In this embodiment, the light source  304  is composed of an electric discharge bulb. The projector lamp  30  is supported by an approximately C-shaped bracket  31 . In the periphery of the projector lamp  30  in the head lamp device body  11 , there is provided an extension so that the inside can not be exposed through the lens  12 . Further, in this embodiment, the lighting circuit  7  for lighting the electric discharge bulb  304  of the projector lamp  30  is built in the lower cover  16  attached to a bottom face opening of the head lamp device body  11 .  
     [0025] The projector lamp  30  is supported between the lower plate  312  and the upper plate  313 , which are respectively formed being bent while making a right angle with the vertical plate  311  of the bracket  31 . On the lower side of the lower plate  312 , the actuator  4  described later is fixed by the screw  314 . The rotary output shaft  448  of the actuator  4  is protruded upward through the shaft hole  315  formed on the lower plate  312 . The screw  314  is screwed to the boss  318  protruding to a lower face of the lower plate  312 . The shaft  305  provided on an upper face of the projector lamp  30  is engaged with the bearing  316  provided on the upper plate  313 . The connecting section  306  provided on a lower face of the projector lamp  30  is engaged and connected with the rotary output shaft  448  of the actuator  4 . Due to the above structure, the projector lamp  30  can be rotated to the right and left with respect to the bracket  31 . Further, the projector lamp  30  can make a rotary motion in the horizontal direction integrally with the rotary output shaft  448  driven by the actuator  4 .  
     [0026] When the bracket  31  is viewed from the front face side, the aiming nuts  321 ,  322  are respectively integrally attached to the right and the left upper portion of the bracket  31 . The leveling bearing  323  is integrally attached to the right lower portion. The aiming nuts  312 ,  322  are respectively screwed to the horizontal aiming screw  331  and the vertical aiming screw  332  which are pivotally supported by the head lamp device body  11 . The leveling bearing  323  is engaged with the leveling ball  51  of the leveling mechanism  5  supported by the head lamp device body  11 . Due to the above structure, when the horizontal aiming screw  331  is rotated, the bracket  31  can be horizontally rotated round a straight line connecting the aiming nut  322  on right with the leveling bearing  323 . When the horizontal aiming screw  331  and the vertical aiming screw  332  are simultaneously rotated, the bracket  31  can be rotated in the upward and downward direction round the leveling bearing  323 . Further, when the leveling mechanism  5  is operated, the leveling ball  51  is moved in the axial direction, and the bracket  31  can be rotated in the upward and downward direction round a straight line connecting the aiming nut  312  with the aiming nut  322 . Due to the foregoing, it becomes possible to conduct an aiming adjustment for adjusting the optical axis of the projector lamp  30  to the right and left and in the upward and downward direction. It also becomes possible to conduct an aiming adjustment for adjusting the optical axis of the projector lamp  30  in the upward and downward direction according to the leveling state when the level of an automobile is changed. In this connection, the protrusion  307  protrudes from a lower face of the reflector  302  of the projector lamp  30 . On the lower plate  312  of the bracket  31  opposing to the protrusion  307 , there are provided a pair of stoppers  317  which are arranged on the right and left. When the projector lamp  30  is rotated, the protrusion  307  collides with one of the stoppers  317 , so that the rotary range of the projector  30  can be regulated.  
     [0027]FIG. 4 is an exploded perspective view of a primary portion of the actuator  4  for swiveling the swivel lamp  3 R,  3 L, FIG. 5 is a plan view showing an assembling structure, and FIG. 6 is a longitudinal sectional view. The case  41  is composed of a lower half  41 D and an upper half  41 U which are respectively formed into a substantially pentagonal dish-shaped profile. When a plurality of protrusions  410  protruding from the circumferential face of the lower half  41 D and a plurality of engaging pieces  411  hanging downward from the circumferential face of the upper half  41 U are engaged with each other so that a case chamber can be formed inside. On both sides of the upper half  41 U and the lower half  41 D, the support pieces  412 ,  413  are respectively protruded toward both sides. These support pieces  412 ,  413  are used when the case  41  is fixed in such a manner that the screw  314  is screwed to the boss  318  of the bracket  31  as described above. The rotary output shaft  448  having a spline structure is protruded from the upper face of the case  41  and engaged with the connecting section  306  on the bottom face of the projector lamp  30 . On the back face of the case  41 , there is provided a connector  451  with which the external connector  21  (shown in FIG. 2) connected with ECU  2  is engaged.  
     [0028] On the inner bottom face of the lower half  41 D of the case  41 , there are vertically provided four hollow bosses  414 ,  415 ,  416 ,  417 . To the first hollow boss  414 , the brushless motor  42  described later, which is a drive motor, is assembled. To the second to the fourth boss  415 ,  416 ,  417 , the shafts of the gear mechanism  44  described later are inserted so that the gear mechanism  44  can be supported. Along the periphery of the inner bottom face of the lower half  41 D, there is integrally provided a step-like rib  418 . The printed board  45  is put on this step-like rib  418  while a peripheral edge portion of the printed board  45  is coming into contact with the step-like rib  418 . Therefore, the printed board  45  is set and supported inside the case  41  while the printed board  45  is being interposed between a rib, which is directed downward being provided in the upper half  41 U not shown in the drawing, and the step-like rib  418 . The first hollow boss  414  penetrates the printed board  45 , and the brushless motor  42  to be assembled is electrically connected with the printed board  45 . Various electronic parts not shown in the drawing, which compose the control circuit  43  described later, and the connector  451  are mounted on the printed board  45 .  
     [0029] As shown in FIG. 7 which is a partially cutaway perspective view, the brushless motor  42  is arranged so that the rotary shaft  423  can be pivotally supported by the thrust bearing  421  and the sleeve bearing  422  in the first hollow boss  414  of the lower half  41 D. The stator coil  424  including three pairs of coils, which are equally arranged in the circumferential direction, is fixed and supported by the first hollow boss  414 . This stator coil  424  is electrically connected with the printed board  45  so that the stator coil  424  can be supplied with electricity. In this structure, the stator coil  424  is assembled integrally with the core base  425 . By utilizing the terminal  425   a  provided on the core base  425 , the printed board  45  is electrically connected. To an upper end portion of the rotary shaft  423 , the cylindrical rotor  426  is attached in such a manner that the cylindrical rotor  426  covers the stator coil  424 . The rotor  426  is composed of a cylindrical yoke  427 , which is made of resin by means of molding, and an annular rotor magnet  428  which is attached on the inner circumferential face of the yoke  427 , wherein the S-pole and the N-pole are alternatively arranged in the circumferential direction.  
     [0030] In the brushless motor  42  composed as described above, when an alternating electric current of the phases U, V and W, the phases of which are different from each other, is supplied to the three coils of the stator coil  424 , a direction of the magnetic force generated between the stator coil  424  and the rotor magnet  428  is changed. Due to the foregoing, the rotor  426  and the rotary shaft  423  are rotated. Further, as shown in FIG. 7, on the printed board  45 , there are provided a plurality of Hall elements H 1 , H 2 , H 3  which are arranged in the circumferential direction of the rotor  426  at predetermined intervals. In this case, there are provided three Hall elements H 1 , H 2 , H 3 . When the rotor magnet  428  is rotated together with the rotor  426 , the magnetic field at each Hall element H 1 , H 2 , H 3  is changed being turned on and off. Therefore, each Hall element H 1 , H 2 , H 3  is changed, and a pulse signal corresponding to the rotation period of the rotor  426  can be outputted.  
     [0031] The first gear  441  is molded by resin integrally with the yoke  427  of the rotor  426 . This first gear  441  is composed as a portion of the gear mechanism  44 . By this first gear  441 , the rotary output shaft  448  is driven at a reduced gear ratio. In addition to the first gear  441  described above, the gear mechanism  44  includes: a second gear  443  pivotally supported by the first fixed shaft  442  supported by the second hollow boss  415 ; a third gear  445  pivotally supported by the second fixed shaft  444  supported by the third hollow boss  416 ; and a sector gear  447  formed integrally with the rotary output shaft  448  pivotally supported by the third fixed shaft  446  supported by the fourth hollow boss  417 . These gears are respectively made of resin by means of molding. As shown in FIGS. 5 and 6, the second gear  443  is composed of a second large diameter gear  443   a  and a second small diameter gear  443   b  which are integrated into one body in the axial direction. The second large diameter gear  443   a  is meshed with the first gear  441 . The third gear  445  is composed of a third large diameter gear  445   a  and a third small diameter gear  445   b  which are integrated into one body in the axial direction. The third large diameter gear  445   a  is meshed with the second small diameter gear  443   b . Further, the third small diameter gear  445   b  is meshed with the sector gear  447 . Due to the above structure, torque of the first gear  441  rotated integrally with the rotor  427  of the brushless motor  42  is transmitted to the rotary output shaft  448  via the second gear  443 , the third gear  445  and the sector gear  447  while the rotary speed is being reduced by those gears. On the inner face of the lower half  41 D on both sides of the rotary direction of the sector gear  447 , there are provided stoppers  419 , which are protruding, colliding with the end portions of the sector gear  447  concerned. The entire rotary angle range of the sector gear  447 , in other words, the entire rotary angle range of the rotary output shaft  448  can be restricted by these stoppers  419 .  
     [0032]FIG. 8 is a block circuit diagram showing an electric circuit structure of the illuminating device including ECU  2  and the actuator  4  described before. In this connection, the actuator  4  is provided in each of the right  3 R and the left swivel lamp  3 L and capable of conducting a bidirectional communication with ECU  2 . ECU  2  includes: a main CPU  201  in which a predetermined algorithm is conducted according to information sent from the sensor  1  so as to output a required control signal C 0 ; and an interface (referred to as I/F hereinafter) circuit  202  for inputting and outputting the control signal C 0  between the main CPU  201  and the actuator  4 . A signal of ON and OFF of the illumination switch S 1  provided in an automobile can be inputted into the above ECU  2 . According to ON and OFF of the illumination switch S 1 , the lighting circuit  7  for supplying electric power to the electric discharge bulb  304  of the projector lamp  30  is controlled by the control signal N, so that both the swivel lamps  3 R,  3 L can be turned on and off. ECU  2  controls the leveling control circuit  6  for controlling the leveling mechanism  5 , which is used for adjusting the optical axis of the bracket  31  to support the projector lamp  30 , in the upward and downward direction by the leveling signal DK, so that the optical axis of the projector lamp  30  can be adjusted according to a change in the level of an automobile. In this connection, of course, an electric connection of the above electric circuit with the electric power supply is turned on and off by the ignition switch S 2  which is provided so that an electric system arranged in the automobile can be turned on and off.  
     [0033] The control circuit  43  provided on the printed board  45  built in the actuator  4 , which is arranged in each of the right  3 R and the left swivel lamp  3 L of an automobile, includes: an I/F circuit  432  for inputting and outputting a signal to and from the ECU  2 ; a sub-CPU  431  for conducting a predetermined algorithm according to the signal inputted from the I/F circuit  432  and according to the pulse signal P outputted from the Hall elements H 1 , H 2  and H 3 ; and a motor drive circuit  434  for driving the brushless motor  42  which is a rotation drive means. In this case, the right and left deflection angle signals DS of the swivel lamps  3 R,  3 L, which are a portion of the control signal C 0 , are outputted from ECU  2  and inputted into the actuators  4 .  
     [0034]FIG. 9 is a schematic circuit diagram showing the motor drive circuit  434  of the control circuit  43  in the actuator  4  and also showing the brushless motor  42 . The motor drive circuit  434  includes: a switching matrix circuit  434  into which the speed control signal V, the start and stop signal S and the normal and reverse rotation signal R, which are control signals sent from the sub-CPU  431  of the control circuit  43 , are respectively inputted and further the pulse signals sent from the three Hall elements H 1 , H 2  and H 3  are inputted; and an output circuit  436  for adjusting the phases (phase U, phase V and phase W) of three phase electric power to be supplied to the three pairs of coils of the stator coil  424  of the brushless motor  42  when an output of this switching matrix circuit  435  is received. In this motor drive circuit  434 , when electric power, the phases of which are phase U, phase V and phase W, is supplied to the stator coil  424 , the magnet roller  428  is rotated, and the yoke  427  integrated with the magnet roller  428 , that is, the rotor  426  and the rotary shaft  423  are rotated. When the magnet rotor  428  is rotated, the Hall elements H 1 , H 2  and H 3  detect a change in the magnetic field and output a pulse signal P. This pulse signal P is inputted into the switching matrix circuit  435 . In the switching matrix circuit  435 , switching operation of the output circuit  436  is conducted in the time relation with the pulse signal. Due to the foregoing, the rotation of the rotor  426  is continued.  
     [0035] The switching matrix circuit  435  outputs a required control signal C 1  to the output circuit  436  according to the speed control signal V, the start and stop signal S and normal and reverse rotation signal R sent from the sub-CPU  431 . The output circuit  436  receives this control signal C 1  and adjusts the phases of the three phase electric power supplied to the stator coil  424 , so that the start, stop, rotary direction and rotary speed of the rotation of the brushless motor  42  are controlled. Into the sub-CPU  431 , a portion of the pulse signal P outputted from each of the Hall elements H 1 , H 2  and H 3  is inputted, so that a state of the rotation of the brushless motor  42  can be recognized. In this case, the up and down counter  437  is built in the sub-CPU  431 . Therefore, when the pulse signals sent from the Hall elements H 1 , H 2  and H 3  are counted, the counted values are made to correspond to the rotary position of the brushless motor  42 .  
     [0036] According to the above constitution, operation is conducted as follows. When ignition switch S 2  is turned on and illumination switch S 1  is turned, pieces of information such as a steering wheel angle of steering wheel SW, a running speed of the automobile and a level of the automobile are inputted into ECU  2  from the sensor  1  arranged in the automobile as shown in FIG. 1. According to the output of the sensor which has been inputted into ECU  2 , the main CPU  201  conducts calculation, and the right and left deflection angle signal DS of the projector lamp  30  of the swivel lamp  3 R,  3 L of the automobile is calculated and inputted into the actuator  4  of each swivel lamp  3 R,  3 L. In the actuator  4 , the sub-CPU  431  conducts calculation according to the right and left deflection angle signal DS thus inputted, and a signal corresponding to the right and left deflection angle signal DS is calculated and outputted into the motor drive circuit  434 , so that the brushless motor  42  is driven. Since the rotation of the brushless motor  42  is reduced by the gear mechanism  44  and transmitted to the rotation output shaft  448 , the projector lamp  30  connected with the rotation output shaft  448  is rotated in the horizontal direction, and the direction of the optical axis of the swivel lamp  3 R,  3 L is defected to the right and left. In this rotary motion of the projector lamp  30 , a deflection angle of the projector lamp  30  is detected by the rotary angle of the brushless motor  42 . That is, the sub-CPU  431  detects the deflection angle according to at least one of the pulse signals P (P 1 , P 2 , P 3 ) outputted from the three Hall elements H 1 , H 2 , H 3  provided in the brushless motor  42  as shown in FIG. 8. Further, the sub-CPU  431  compares the detection signal of the detected deflection angle with the right and left defection angle signal DS inputted from ECU  2  and conducts feedback control on the rotary angle of the brushless motor  42  so that both can agree with each other. In this way, the direction of the optical axis of the projector  30 , that is, the direction of the optical axis of the swivel lamp  3 R,  3 L can be highly accurately controlled so that it can be at a deflection position that is set by the right and left deflection angle signal DS.  
     [0037] Due to the deflecting motion of the projector lamp  30  described above, deflected light, which is emergent from both swivel lamps  3 R,  3 L, illuminates right and left regions that are deflected from the direction in which the automobile is going straight. Therefore, while the automobile is running, it is possible for the projector lamps  30  to illuminate not only a region located in the direction in which the automobile is going straight but also a region located in the direction in which the steering operation is conducted. Accordingly, the safety of driving can be enhanced.  
     [0038] In this AFS, when at least one of the pulse signals P of the Hall elements H 1 , H 2 , H 3  arranged corresponding to the brushless motor  42  is counted by the up and down counter  437 , the rotary angle of the brushless motor  42  can be detected, and a deflection angle of the swivel reflector  15  deflected by the actuator  4 , the drive source of which is the brushless motor  42 , is correlatively detected. However, when trouble is developed in the transmission route of rotation from the brushless motor  42  to the projector lamp  30 , the correlation between the pulse signal P and the deflection angle of the projector lamp  30  is damaged, and it becomes impossible to conduct a normal deflection control of the swivel lamp  3 R,  3 L.  
     [0039] Therefore, in the present invention, a flow of detection is conducted to detect the occurrence of trouble in the actuator in the case where the ignition switch S 2  is turned on. FIG. 10 is a flow chart to explain a flow of detection for detecting the occurrence of trouble of the actuator  4  when the ignition switch is turned on. When the ignition switch S 2  is turned on (S 101 ), initialization is executed so that the optical axis of irradiation of the swivel lamp  3 R,  31  can be directed in a predetermined direction (S 102 ). Usually, this initialization S 102  is conducted to control and rotate the brushless motor  42  so that the projector lamp  30  of the swivel lamp  3 R,  3 L can be directed in the direction in which the automobile is going straight. In this case, as a portion of this initialization, the following process is executed here. First, counted value X1 of the up and down counter  437  at the time of initialization is detected (S 103 ). Next, the sub-CPU  431  controls the brushless motor  42  by the motor drive circuit  434  so that the brushless motor  42  can be continuously driven on one direction (S 104 ). When the rotation of the brushless motor  42  is stopped in the case of rotating in one direction, that is, when the protrusion  307  of the projector lamp  30  collides with one of the stoppers  317  of the bracket  31  and deflects to the maximum angle on one side or when the sector gear  447  collides with one of the stoppers  419 , the counted value X2 is detected (S 105 ). Next, the brushless motor  42  is continuously rotated in the opposite direction (S 106 ). When the rotation of the brushless motor  42  is stopped, that is, when the protrusion  307  of the projector lamp  30  collides with the other stopper  317  and deflects to the maximum angle on the opposite side or when the sector gear  447  collides with the stopper  419  on the opposite side, the counted value X3 is detected (S 107 ). In this case, since the apparatus is designed in such a manner that a rotary range of the brush motor  42  from the start of rotation to the collision of the sector gear  447  with the stopper  419  is larger than a rotary range of the brushless motor  42  of the collision of the protrusion  307  with the stopper  317 , the counted value of the maximum angle is usually detected by the latter collision. The former rotary range regulation is prepared for the object of preventing an excessively large rotation of the projector lamp  30  in the case where the stopper function of the latter rotary range regulation is damaged.  
     [0040] With these counted values X1, X2 and X3, the following rotation range values Y1, Y2 and Y3 are calculated (S 108 ).  
     [0041] Y1=X2−X1  
     [0042] Y2=X2−X3  
     [0043] Y3=X1−X3  
     [0044] In this connection, FIG. 11 is a schematic illustration for explaining the above counted values X1, X2 and X3 and the rotary range values Y1, Y2 and Y3. In this case, the up and down counter  437  is set so that the counted value of the pulse signal is increased in the positive direction when the brushless motor  42  is rotated in one direction.  
     [0045] After that, according to the rotary range values Y1, Y2 and Y3, it is judged whether the brushless motor  42  of the actuator  4  and the gear mechanism  44  are in an abnormal state or not. In this judgment, first, it is judged whether or not Y1=0, Y2=0 and Y3=0 (S 109 ). When all these conditions are satisfied, the rotary angle of the brushless motor  42  is 0, which means that the brushless motor  42  is locked and not rotated at all. In this case, it is judged that the brushless motor  42  is out of order and in an abnormal state (S 110 ).  
     [0046] When it is judged in step S 109  that the brushless motor  42  is in a normal state, the rotary range value Y2 corresponding to all deflection angle range of the projector lamp  30  is compared with the predetermined setting rotary range value Z1, which is obtained when the pulse signals are counted when the projector lamp  30  is normally deflected at the maximum angle of the projector  30  from one side to the opposite side, and it is judged whether or not Y2 is in the predetermined error range ΔZ of the setting rotary range value Z1 (S 111 ). When Y2 is in the predetermined error range ΔZ, that is, when  
       Z 1−Δ Z≦Y 2≦ Z 1+ ΔZ,    
     [0047] it is judged that the actuator  4  is in a normal state (S 112 ).  
     [0048] On the other hand, when the rotary range value Y2 is not in the predetermined error range ΔZ of the setting rotary range value Z1 but the rotary range value Y2 is out of the range, it is judged that the gear mechanism  44  is in an abnormal state (S 13 ). In this case, when the rotary range value Y2 is larger than the error range ΔZ, that is, when  
       Y 2&gt; Z 1+Δ Z,    
     [0049] the rotary range of the brushless motor  42  is large although the projector lamp  30  has been defected in the maximum range, which means that the brushless motor  42  has excessively rotated. In this case, it is estimated that some of the gears  441 ,  443 ,  445  and  447  composing the gear mechanism  44  are damaged and running idle.  
     [0050] On the contrary, when the rotary range value Y2 is out of the predetermined error range ΔZ of the setting rotary range value Z1 and smaller than this error range ΔZ, that is, when  
       Y 2&lt; Z 1−Δ Z,    
     [0051] it is estimated that the following problems are encountered. Although the projector lamp  30  is deflected by the rotation of the brushless motor  42 , for example, some of the gears  441 ,  443 ,  445  and  447  of the gear mechanism  44  are locked being seized, so that the gear mechanism  44  can not be smoothly rotated. For the above reasons, the brushless motor  42  can not be rotated by the angle corresponding to all deflection range of the projector lamp  30 .  
     [0052] As described above, in step S 113  in which an abnormality of the gear mechanism  44  is detected, it is possible to specify a reason of the abnormality of the gear mechanism  44  by the rotary range value Y2. In this connection, in the case where it is judged in respective steps S 110  and S 113  that the brushless motor  42  or the gear mechanism  44  is in an abnormal state, in order to make confirmation, the program may return to step S 102  and the process after the process of finding the rotary range values Y1, Y2 and Y3 may be repeated by a predetermined number of times. That is, after step S 110  or S 113 , it is judged whether or not it has reached the number of retrial (S 114 ). In the case where it has not reached the number of retrial, the program returns to step S 102 . In the case where it has reached the number of retrial, the retrial is completed and the occurrence of an abnormality is decided.  
     [0053] When it is judged in step S 112  that the actuator  4  is in a normal state, a signal representing that the actuator  4  is in the normal state is sent from the sub-CPU  431  of each actuator to ECU  2 , and the main CPU  201  of ECU  2  receives the signal representing that the actuator  4  is in the normal state, and usual processing of deflection is executed (S 115 ). When it is judged to be abnormal even after the retrial has been conducted, a signal representing the occurrence of an abnormality is sent to ECU  2  from the sub-CPU  431  of each actuator  4 , and the main CPU  201  of ECU  2  receives the signal representing the occurrence of an abnormality and executes fail-safe processing (S 116 ). This fail-safe processing is conducted in such a manner that, for example, when the projector lamp  30  can be deflected, the projector lamp  30  concerned is deflected and fixed to the maximum deflection angle on the left. This direction of the left is opposite to the opposed lane in Japan where they drive on the left. Therefore, a driver driving an automobile in the opposed lane is not dazzled by the light emitted by the swivel lamps  3 R,  3 L. In this connection, in Europe and America where they drive on the right, the swivel lamps  3 R,  3 L are deflected to the maximum deflection angle to the right and then rotated to the left by a predetermined angle so that the swivel lamps  3 R,  3 L can be set at the reference positions. In the case where the projector lamp  30  can be deflected in the same way, the projector lamp  30  may be stopped at a position where it is directed in the direction in which the automobile is going straight.  
     [0054] In the case where the projector lamp  30  can not be deflected in the fail-safe processing, ECU  2  controls the lighting circuit  7  so as to turn off the supply of electric power to the swivel lamps  3 R,  3 L. Alternatively, a low intensity of electric current is made to flow in each swivel lamp  3 R,  3 L so as to emit light at a low luminance. Due to the foregoing, even when the projector lamp  30  is deflected in the direction in which a driver driving an automobile running in the opposed lane is dazzled by the headlight, it is possible to prevent the driver from being dazzled. In this connection, only the supply of electric power to a swivel lamp  3 R,  3 L, which is in an abnormal state, may be stopped, and the supply of electric power to a swivel lamp  3 R,  3 L, which is in a normal state, may be conducted in the same way as that of the normal state, and the same deflection control as that of the normal state may be conducted.  
     [0055] As described above, in the present invention, AFS can be properly controlled according to the pulse signals P sent from the Hall elements H 1 , H 2  and H 3 . Further, the occurrence of an abnormality of the brushless motor  42  or the gear mechanism  44  can be specifically judged according to the pulse signals P concerned. Therefore, in the occurrence of an abnormality of AFS, the fail-safe control can be realized and the safety of traffic can be ensured. On the other hand, it becomes possible to execute an appropriate maintenance work. Further, AFS can be properly controlled.  
     [0056] In this connection, in the present invention, when the gear mechanism  44  is damaged, it can be considered that the rotary range value Y1 in the case of rotating the brushless motor  42  in one direction exceeds the predetermined setting rotation range value Z1. Accordingly, as shown in the flow chart of FIG. 12, immediately after the counted value X2 is detected in step S105, the rotary range value Y 1  is calculated (S 201 ), and this rotary range value Y1 is compared with the setting rotary range value Z1 (S 202 ). When Y1&gt;Z1, it is immediately judged whether or not the gear mechanism  44  is in an abnormal state (S 203 ). In the same manner, from the counted value X3 obtained when the brushless motor  42  is operated in the opposite direction, the rotary range value Y2 is immediately calculated (S 204 ), and this rotary range value Y2 is compared with the setting rotary range value Z1 (S 205 ). When Y2&gt;Z1, it is immediately judged that the gear mechanism  44  is in an abnormal state (S 203 ). In this case, in the same manner as that of the embodiment described before, of course, the error ΔZ may be considered with respect to the setting rotary range value Z1. In this embodiment, one direction described before is not specified. Of course, one direction and the other direction may be reverse. When this flow is adopted, it is possible to quickly judge the occurrence of an abnormality of the gear mechanism  44 .  
     [0057] In this case, counting of the pulse signals by the up and down counter  437  of the sub-CPU  431  may be conducted on any pulse signals P 1 , P 2  and P 3  of the Hall elements H 1 , H 2  and H 3 . In the case where a period of the pulse signal sent from the Hall element is very short, counting may be conducted after the pulse signal has been divided.  
     [0058] In the above embodiment, the present invention is applied to a head lamp device in which the projector lamp composing the swivel lamp is deflected to the right and left so as to change the irradiating optical axis. However, it is possible to apply the present invention to a head lamp device in which only the reflector conducts a deflecting motion. Alternatively, it is possible to apply the present invention to a head lamp device in which the substantial irradiating range is changed by conducting a deflecting motion on the auxiliary reflector provided independently from the primary reflector.  
     [0059] As explained above, the head lamp device of the present invention includes: a rotation range detection means for detecting a rotation range of a drive motor of a rotation drive means for driving a light distribution control means for controlling a light distribution of the head lamp; and an abnormality judgment means for judging an abnormality of the rotation drive means according to a rotation range of the drive motor detected by the rotation range detection means when the rotation drive means is driven. Therefore, it is possible to judge the occurrence of an abnormality in the case where the drive motor of the rotation drive means and the gear mechanism develop trouble, and further it is possible to specifically judge a cause of the abnormality. Due to the foregoing, when AFS is in an abnormal state, it is possible to realize a fail-safe operation so that the safety of traffic can be ensured. On the other hand, it is possible to execute an appropriate maintenance work corresponding to the cause of an abnormality. Further, AFS can be properly controlled.