Abstract:
A method for detecting errors in driving device of head light of vehicles utilizes a microprocessor control unit of a main circuit to detect the position of the driving shaft by checking the change of magnetic field or resistance of the driving member and the change of magnetic field or resistance is compared with a pre-set value to decide the position of the driving shaft. The motor is then commanded to drive the driving shaft to the pre-set position. The method detects the position of the head light before the drivers drive the vehicles on the road and if the head light is not in a desired position, the user can adjust the head light position to prevent potential risk on the road.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a method for driving the driving device of head light of vehicles, especially for a method for detecting errors and correcting the positions of the head light to pre-set positions.  
       BACKGROUND OF THE INVENTION  
       [0002]     One of the latest safety devices for vehicles is the Adaptive Front-lighting System (AFS) which allows the head light turns according to needs and the system includes a driving device to turn the head light. A latest driving device known to applicant includes step motor and a sensor connected to the output shaft of the motor, wherein the sensor detects the angle that the output shaft rotates and generates a reference voltage which is compared with a pre-set voltage so as to decide the position of the head light. A control unit is then activate the step motor to rotate the output shaft of the step motor to move the head light to pre-set position. Although errors from the parts or the environment have been considered by the known device, the range of the pre-set voltage does not include method for detecting errors. Therefore, the drivers cannot correct the movement of the head light when errors that are not considered by the device happen. In other words, if the driving device of the head light cannot work functionally and the driving device cannot correct the errors, the drivers take risks to drive.  
         [0003]     The present invention intends to provide a method for driving the driving device of the head light and the method provides a detection function to detect errors of the movement of the head light.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention relates to a method for detecting errors in driving device of head light of vehicles, and the method includes the following steps:  
         [0005]     step  1 : activating driving device of head light and a main circuit beginning to operate;  
         [0006]     step  2 : initializing a microprocessor control unit of the main circuit and zeroing the counting condition, the microprocessor control unit detecting parts in the main circuit and making judgement of error;  
         [0007]     step  3 : judging whether position of driving shaft is detected, if the position of the driving shaft is not detected, a motor being activated to rotate the driving shaft and the counting condition being added by one and stored as record, judging whether the number of the counting condition is over three, if the number of the counting condition is less than three, repeat step  3 , if the number is over three, an error judgement is made and the main circuit is stopped;  
         [0008]     step  4 : the microprocessor control unit obtaining pre-set position and recording the position, the microprocessor control unit obtaining current position of the driving shaft, the pre-set position and the current position being compared, if the result of comparison is different, the motor driving the driving shaft to the pre-set position;  
         [0009]     step  5 : judging whether the driving shaft is returned to the pre-set position, if the driving shaft is not returned to the pre-set position, the counting condition is added by one and stored as record, judging whether the number of the counting condition is over pre-set times, if the number of the counting condition is less than the pre-set times, repeat steps  3  to  5 , if the number is over the pre-set times, an error judgement is made and the main circuit is stopped;  
         [0010]     step  6 : judging whether the revolution of the motor is in a range of restriction, if the revolution of the motor exceeds the range of restriction, the counting condition is added by one and stored as record, judging whether the number of counting condition is over five, if the number is less than five, repeat steps  2  to  5 , if the number is over the pre-set times, an error judgement is made and the main circuit is stopped, and step  7 : when completing steps  1  to  6 , a driving module of the driving device is set and the driving device is ready to active, the driving device is ready to accept commands from the microprocessor control unit, the main circuit is stopped.  
         [0011]     The primary object of the present invention is to provide a method to detect the current position of the head light and the method is able to judge the status of the head light during driving.  
         [0012]     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  shows a perspective view of the driving device of head light of the present invention;  
         [0014]      FIG. 2  is an exploded view of the driving device of head light of the present invention;  
         [0015]      FIG. 3  is a plane view to show that the reduction gear set is engaged with a rack on the driving member;  
         [0016]      FIG. 4  is an exploded view of another embodiment of the driving device of head light of the present invention;  
         [0017]      FIG. 5  shows a flow chart of the main circuit of the present invention;  
         [0018]      FIG. 6  shows a first method for detecting the current position of the head light;  
         [0019]      FIG. 7  shows a second method for detecting the current position of the head light;  
         [0020]      FIG. 8  shows a third method for detecting the current position of the head light;  
         [0021]      FIG. 9  shows the flow chart to illustrate that the driving shaft is moved back to original position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]     Referring to FIGS.  1  to  3 , the driving device for head light of the present invention comprises a box  1 , a motor  2 , a reduction device  3 , a driving member  4 , a circuit board  5  and a driving shaft  6 . The box  1  includes a base  11  and a top board  12 , wherein the base  11  has a first hole  111  through which the output shaft  21  of the motor  2  extends and a second hole  112  through which the driving shaft  6  extends. The reduction device  3 , the driving member  4  and the circuit board  5  are received between the top board  12  and the base  11 .  
         [0023]     The output shaft  21  has a gear  22  which is engaged with one of the gears of the reduction device  3  and the motor  2  is connected to an underside of the base  11 . Therefore, when the output shaft  21  rotates, the reduction device  3  is activated.  
         [0024]     The driving member  4  has a fan-shaped rack  41  which is engaged with the reduction device  3  so that the driving member  4  is driven by the reduction device  3  when the motor  2  is activated. A magnet with N pole and S pole is received in one end of the driving member  4  and faces the circuit board  5 . The other end of the driving member  4  is connected with the extension  61  of the driving shaft  6 . The circuit board  5  has a microprocessor control unit (MCU) and a detection circuit composed of a sensor which is located corresponding to the magnet  42  so that when the driving member  4  rotates, the sensor  51  senses the change of magnetic field and generates a reference number which is sent to the MCU.  
         [0025]     When in assembling, the extension  61  of the driving shaft  6  extends through the second hole  112  and is connected to the second end of the driving member  4 . The reduction device  3  is then installed in the base  11  and engaged with the gear  22  on the output shaft  21  of the motor  2  and the rack  41  of the driving member  4 . The circuit board  5  is installed to the bas  11  and the top board  12  is then mounted to the base  11 .  
         [0026]     The driving shaft  6  is connected to the head light (not shown) and when the driving member  4  rotates, the sensor of the detection circuit senses the change of magnetic field due to the movement of the magnet  42  in the driving member  4 . The change generates a reference number and sent to the MCU to judge the current position of the driving shaft  6 . The current position is compared with a pre-set position, if the two positions are different, the motor  2  drives the reduction device  3  to rotate the driving shaft  6  to the pre-set position.  
         [0027]      FIG. 4  shows another embodiment of the driving device, wherein the driving member  7  has a fan-shaped rack  71  which is engaged with the reduction device  3 . A hole  72  is defined in an end of the driving member  7  and faces the circuit board  5 . The other end of the driving member  7  is connected to the driving shaft  6 . The circuit board  5  has a detection circuit composed of a variable resistance  8  which is engaged with the hole  72  of the driving member  7 .  
         [0028]     When the driving member  7  rotates an angle, the variable resistance changes its resistance value so as to generate a voltage value by which the current position of the driving shaft  6  is detected. The current position is compared with a pre-set position, if the two positions are different, the motor  2  drives the reduction device  3  to rotate the driving shaft  6  to the pre-set position.  
         [0029]     As shown in  FIG. 5 , which discloses the flow chart of the main circuit of the circuit board  5  and includes the following steps.  
         [0030]     step  10  shows that after the driving device of head light is activated, the main circuit begins to operate. The step  11  shows that the microprocessor control unit of the main circuit is initialized and the counting condition is zeroed. The microprocessor control unit also detects parts in the main circuit and making judgement of error.  
         [0031]     Step  12  judges the current position of the driving shaft  6 , if the current position of the driving shaft  6  cannot be detected, step  18  is activated to activate the motor  2  and the counting condition is added by one and stored as record. In the step  18 , judging whether the number of the counting condition is over three which is pre-set, if the number of the counting condition is less than three, the step  12  is repeated, if the number is over three, an error judgement as disclosed in step  21  is made and process step  17  to stop the main circuit. If the current position is detected, then the step  13  is processed.  
         [0032]     During the step  13 , the microprocessor control unit obtains the pre-set position and records the position. The pre-set position and the current position obtained in step  12  are compared with each other, if the result of comparison is different, the motor  2  drives the driving shaft  6  to the pre-set position. If the two positions are the same, then the step  14  is processed.  
         [0033]     Step  14  is to judge whether the driving shaft  6  is returned to the pre-set position, if the driving shaft  6  is not returned to the pre-set position, the counting condition is added by one and stored as record as disclosed in step  20 . Step  18  is activated to judge whether the number of the counting condition is over pre-set times which is three, if the number of the counting condition is less than the pre-set times, repeat steps  12  to  14 . If the number is over the pre-set times and the driving shaft  6  is not returned to its pre-set position, an error judgement is made as disclosed in step  21  and the main circuit is stopped as disclosed in step  17 . On the contrary, if the driving shaft  16  is returned to its pre-set position by the judgement in step  14 , then step  15  is processed.  
         [0034]     Step  15  is to judge whether the number of the revolution, the operation time or the electric current passing through of the motor is in a range of restriction. If the factor that mentioned above of the motor exceeds the range of restriction, the counting condition is added by one and stored as record as disclosed in step  20 . The step  18  judges whether the number of counting condition is over three, if the number is less than three, then repeat steps  12  to  15 , if the number is over three, an error judgement is made by step  21  and the step  17  cuts off the main circuit. On the contrary, if the step  15  judges that the number of the counting condition is not exceeded, the process step  16 .  
         [0035]     When processing the step  16 , the driving module of the driving device is set and the driving device is ready to active. The driving device is ready to accept commands from the microprocessor control unit and the step  17  cuts off the main circuit.  
         [0036]     As shown in  FIG. 6 , there are three ways to detect the current position of the driving shaft  6 , the first way is to use the detection circuit composed of the sensor  51  on the circuit board  5  as shown in  FIG. 2  to detect the current position of the driving shaft  6 .  
         [0037]     When processing the step  12  to obtain the current position of the driving shaft  6 , the step  121  is processed in the same to zero the counting condition and the step  1211  is also processed.  
         [0038]     In step  1211 , the sensor  51  detects a change of magnetic field of a magnet  42  in a driving member  4  so as to obtain a conference number which is sent to the MCU and transferred into a position reference number. After the step  1211  is completed, the step  1212  is processed wherein the transferred position reference number is compared with pre-set position reference number to judge if a result of the comparison exceeds a pre-set range of the position reference number. If the result of comparison is within the range of the pre-set position reference number, the current position of the driving shaft  6  is obtained by the step  1213  and the step  1214  eliminates the processes for obtaining the current position and the main circuit process in step  13  as shown in  FIG. 5  starts. On the contrary, if the result of comparison is not located within the range of the pre-set position reference number, an error judgement is made by the step  1215  and the step  1214  eliminates the processes for obtaining the current position and the main circuit process in step  19  as shown in  FIG. 5  starts.  
         [0039]     As shown in  FIG. 7 , the second way for obtaining the current position of the driving shaft  6  uses a detection circuit composed of a sensor  51  of the circuit board  5  as shown in  FIG. 2  and a quadrature A/B circuit. The quadrature circuit generates a pulse “A” and a pulse “B” with a phase angle difference, if the pulse “A” leads a phase angle 90 degrees from the pulse “B”, the a first pre-set process is processed. If the pulse “B” leads a phase angle 90 degrees from the pulse “A”, a second pre-set process is processed.  
         [0040]     When processing the step  12  to obtain the current position of the driving shaft  6 , the step  122  is processed in the same to zero the counting condition and the step  1221  is also processed.  
         [0041]     The step  1221  judges whether the driving shaft  6  is returned to its pre-set position which is the original position, if the driving shaft  6  did not returned to the pre-set position in the record of the MCU, step  1223  is activated to activate the motor  2  to drive the driving shaft  6  back to its original position. This is recorded in the MCU and step  1222  begins to process. On the contrary, if the driving shaft  6  has been returned to the original position, then the step  1222  is processed.  
         [0042]     In the step  1222 , the angular movement of the magnet  42  results in a change of magnetic field and the change generates a reference number which is sent to the quadrature circuit to generate the pulses “A” and “B” with a phase difference. The signal is sent to the MCU which transfers the signal into position reference number and the position reference number is recorded.  
         [0043]     When the step  1222  is completed, the step  1224  is activated and the transferred position reference number is compared with pre-set position reference number to judge if a result of the comparison exceeds a pre-set range of the position reference number. The range is composed of different position references numbers collected by the angular movements of the magnet  42 . Each angular movement generates a change of magnetic field which is transferred to the MCU and transferred to different positioning reference numbers. If the result of comparison is within the range of the pre-set position reference number, the current position of the driving shaft is obtained by the step  1226 . The step  1227  eliminates the processes for obtaining the current position and the main circuit process in step  13  as shown in  FIG. 5  starts. On the contrary, if the result of comparison is not located within the range of the pre-set position reference number, an error judgement is made by the step  1225  for the obtaining current position of the driving shaft. The step  1227  eliminates the processes for obtaining the current position and the main circuit process in step  19  as shown in  FIG. 5  starts.  
         [0044]     As shown in  FIG. 8 , the third way to obtain the current position of the driving shaft  6  uses a detection circuit composed of a variable resistance  8  on the circuit board  5  as shown in  FIG. 4  to detect the current position of the driving shaft  6 .  
         [0045]     When processing the step  12  to obtain the current position of the driving shaft  6 , the step  123  is processed in the same to zero the counting condition and the step  1231  is also processed.  
         [0046]     When processing the step  1231 , the MCU obtains the reference voltage which comes from the change of the resistance of the variable resistance  8  when the driving member  7  rotates.  
         [0047]     After the reference voltage is obtained in step  1231 , step  1232  is processed and the reference voltage is compared with pre-set voltage to judge if a result. of the comparison exceeds a pre-set range of the voltage, if the result of comparison is within the range of the pre-set voltage, the current position of the driving shaft  6  is obtained, and the step  1235  eliminates the process for obtaining the current position and the main circuit process as disclosed in step  13  as shown in  FIG. 5  begins. If the result of comparison is not located within the range of the pre-set voltage, an error judgement is made for the current position of the driving shaft  6  by step  1234  and the step  1235  eliminates the process for obtaining the current position and the main circuit process as disclosed in step  13  as shown in  FIG. 5  begins.  
         [0048]     The method for returning the driving shaft  6  back to its pre-set position in step  13  as disclosed in  FIG. 5  is described hereinafter.  
         [0049]     As shown in  FIG. 9 , after the main circuit process obtains the current position of the driving shaft  6  in step  12 , the step  130  is activated to activate the motor  2  to drive the driving shaft  6  back to its pre-set position.  
         [0050]     Then the step  131  begins to obtain a pre-set position from the MCU and records the pre-set position, the counting condition is zeroed.  
         [0051]     Then the step  132  records the current position of the driving shaft  6  and the current position can be obtained by the methods mentioned above.  
         [0052]     Then the step  133 , the current position and the pre-set position are compared, if the two positions are not the same, the motor  2  is activated one more action or the motor reduces one action. In other words, the motor  2  rotates an angle clockwise or counter clockwise to drive the driving shaft  6 .  
         [0053]     Then the step  134 , the MCU records the operation time of the motor  2 .  
         [0054]     Then the step  135  compares the operation time of the motor  2  recorded in step  134  and the pre-set period of time of the operation of the motor  2 , if the actual operation time is longer than the pre-set period of time of the motor  2 , the step  138  judges that the motor  2  operates too long and the step  139  stops the operation of the motor  2 . The main circuit process in step  14  as shown in  FIG. 5  starts. On the contrary, if the actual operation time is shorter than the pre-set period of time of the motor  2 , the step  136  judges that the driving shaft  6  is in its pre-set position. If the driving shaft  6  has not yet arrived its pre-set position, then steps  132  to  136  are repeated to drive the motor  2 . If the driving shaft  6  has arrived its pre-set position, then step  137  judges that the action is completed and the step  139  stops the motor  2  and the main circuit process in step  14  as shown in  FIG. 5  starts.  
         [0055]     The present invention provides thee ways to detect the current position of the driving shaft so that the users have different options to detect the driving shaft. After the driving device is activated, the users know that the status of the driving device, if an error is detected, the users can correct it before driving on the roads.  
         [0056]     While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.