Lighting circuit and vehicular lighting device

A vehicular lighting device, comprising:

• a semiconductor light source;
• a reflector structured to reflect emitted light of the semiconductor light source;
• a motor mounted with the reflector and that rotates so as to scan the front of a vehicle with reflected light of the reflector;
• a motor drive circuit structured to drive the motor;
• and
• a lighting circuit structured to drive the semiconductor light source,
• wherein the lighting circuit turns on the semiconductor light source after the motor starts driving and after a rotation frequency of the motor reaches a predetermined minimum rotation frequency.

A lighting circuit used for a vehicular lighting device,

• the vehicular lighting device comprising:
• a semiconductor light source;
• and
• a reflector structured to reflect emitted light of the semiconductor light source and to repeat a predetermined periodic motion so as to scan the front of a vehicle with reflected light of the emitted light, and
• the lighting circuit comprising:
• a light intensity calculator structured to receives light-distribution-pattern information indicating a target light distribution pattern to be formed in front of the vehicle and to calculate light intensity to be generated by the semiconductor light source at each time;
• and
• a driver structured to light the semiconductor light source so as to obtain the light intensity calculated by the light intensity calculator at each time,
• wherein when the target light distribution pattern is varied, the light intensity calculator calculates light intensity at each time so as to gradually vary a light distribution pattern with time toward the target light distribution pattern after variation.