Vehicle headlamp apparatus

• US 20040090788A1
• Filed: 10/31/2003
• Published: 05/13/2004
• Est. Priority Date: 11/05/2002
• Status: Active Grant

• Current Assignee: Koito Manufacturing Company Limited
• Original Assignee: Koito Manufacturing Company Limited
• Inventors: Ishida, Tetsuya
• Granted Patent: US 6,918,688 B2
• Time in Patent Office: Days
• US Class Current: 362/467
• CPC Class Codes: B60Q 1/076 by electrical means including means to transmit the movements, e.g. shafts or joints
• CPC Class Codes: B60Q 1/10 due to vehicle inclination, e.g. due to load distribution
• CPC Class Codes: B60Q 1/12 due to steering position
• CPC Class Codes: B60Q 2200/38 Automatic calibration of motor-driven means for adjusting headlamps, i.e. when switching on the headlamps, not during mounting at factories
• CPC Class Codes: H02P 6/182 using back-emf in windings

Abstract

A vehicle headlamp device contains a rotation-state recognizing circuit operating such that when any of Hall elements used for controlling a rotational position of a drive motor for deflecting the optical axes in a headlamp device is abnormal, a rotation-state recognizing circuit recognizes a rotational position of the drive motor based on the output signals of the remaining Hall elements and a predetermined angle prediction time computed using a rotational period of the drive motor. With provision of the rotation-state recognizing circuit, even when any of the Hall elements becomes defective, the rotation of the drive motor is normally controlled to thereby secure a proper optical-axis deflection control in the headlamp device.

Claims

1. A vehicle headlamp device comprising:

optical-axis deflecting means for deflecting illumination optical axes of headlamps of a vehicle,

said optical-axis deflecting means comprising;

a drive motor as a rotation drive source;

a plurality of detecting elements for detecting a rotational position of said drive motor; and

motor drive means for controlling a rotation of said drive motor based on a rotational position of said drive motor detected by said detecting elements,

wherein said motor drive means includes a rotation-state recognizing means operating such that when any of said plurality of detecting elements is abnormal, said rotation-state recognizing means recognizes a rotational position of said drive motor based on the output signals of the remaining detecting elements and a predetermined angle prediction time computed using a rotational period of said drive motor.

2. A vehicle headlamp device according to claim 1, wherein said rotation-state recognizing means includes means for encoding the output signals of said plurality of detecting elements, means for detecting a change of each said code value encoded, means for measuring a time duration where each said code value changes to thereby set a predetermined angle prediction time, means for recognizing a rotational position of said drive motor from said code values, and means for recognizing a time point when said predetermined angle prediction time has elapsed from a time point that said code value changes, as a rotational position of said drive motor.

3. A vehicle headlamp device according to claim 1, wherein said drive motor is a brushless motor including a stator coil, and a rotor formed with an annular magnet rotating about said stator coil, and each said detecting element is a Hall element which varies an output signal thereof in response to a magnetic field change caused by rotation of said rotor.

4. A vehicle headlamp device according to claim 2, wherein said drive motor is a brushless motor including a stator coil, and a rotor formed with an annular magnet rotating about said stator coil, and each said detecting element is a Hall element which varies an output signal thereof in response to a magnetic field change caused by rotation of said rotor.

5. A vehicle headlamp device according to claim 3, wherein the annular magnet having two magnetic poles arrayed at 180°

of the center angle, and three Hall elements are arrayed at an angular interval of 120°

.

6. A vehicle headlamp device according to claim 4, wherein the annular magnet having two magnetic poles arrayed at 180°

of the center angle, and three Hall elements are arrayed at an angular interval of 120°

.

7. A vehicle headlamp apparatus according to claim 1, wherein the illumination optical axes of the headlamp is changed horizontally according to the steering angle of the steering wheel of the vehicle.

8. A vehicle headlamp apparatus according to claim 1, wherein the drive motor and the motor drive means are integrally accommodated as a single unit.