Automotive lamp
AssigneeKoito Manufacturing Co., Ltd.
InventorsKentarou MURAKAMI, Atsushi UESUGI, Toshiyuki TSUCHIYA
Life of this patent
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Abstract
A scanning light source includes a semiconductor light source and a motor, and scans output light of the semiconductor light source in front of a lamp according to the movement of the motor. A constant current driver supplies a driving current ILED to the semiconductor light source according to a light source control signal. A light source control signal generator generates the light source control signal so as to obtain a light distribution pattern that corresponds to light distribution instruction data. A delay time measurement device measures the delay time required for the transition of the on/off states of the semiconductor light source from the change of the light source control signal.
Claims18
A lighting circuit structured to control a scanning light source that comprises a semiconductor light source and a motor, and that is structured to scan output light of the semiconductor light source in front of a lamp according to a movement of the motor, the lighting circuit comprising:
- a constant current driver structured to supply a driving current that corresponds to a light source control signal to the semiconductor light source;
- a light source control signal generator structured to generate the light source control signal so as to obtain a light distribution pattern that corresponds to light distribution instruction data;
- and
- a delay time measurement device structured to measure a delay time required for a transition of lighting-on and lighting-off states of the semiconductor light source from a change of the light source control signal,
- wherein the lighting circuit is adaptive to cancel variation and fluctuation of the delay time.
An automotive lamp comprising:
- a scanning light source comprising a semiconductor light source and a motor, and structured to scan output light of the semiconductor light source in front of the lamp according to a movement of the motor;
- and
- a lighting circuit structured to measure a period of a pulse signal that is synchronized with the movement of the motor, to calculate a parameter based on a measurement value of the period and light distribution instruction data, to generate a dimming signal for indicating a time waveform of a light amount to be output from the semiconductor light source using the parameter, and to turn on the semiconductor light source according to the dimming signal,
- wherein, in the lighting circuit, a judgement condition is defined with respect to a current value that is the measurement value of the period in a current cycle and a reference value that is a period that was used to calculate the parameter in an immediately previous cycle,
- wherein, when pass judgement has been made for the judgment condition, the current value is used to calculate the parameter,
- and wherein, when fail judgement has been made for the judgment condition, instead of the current value, the reference value is used to calculate the parameter.
An automotive lamp comprising:
- a scanning light source comprising a motor and a motor driver structured to rotate the motor in an enable state, and to stop a rotation of the motor in a disable state;
- and
- a lighting circuit structured to supply an enable signal for indicating an enable state and a disable state to the motor driver, and to turn on the semiconductor light source in synchronization with a pulse-shaped position detection signal that is synchronized with the rotation of the motor so as to obtain a desired light distribution pattern,
- wherein, when an event which is a trigger for starting the rotation of the motor occurs, the lighting circuit asserts the enable signal,
- wherein, after the assertion of the enable signal, when the lighting circuit detects that a state in which a period of the position detection signal is longer than a predetermined threshold value continues for a predetermined first time, the lighting circuit repeats a retry operation in which the enable signal is negated, following which, after a predetermined second time elapses, the enable signal is asserted again,
- and wherein, when the period of the position detection signal does not become shorter than the threshold value even after the retry operation is executed a plurality of times, the lighting circuit makes an abnormal stop in a state in which the enable signal is negated.
Dependencies are inferred from the claim text.