A noise reduction circuit for a matrix LED driver includes a pseudo random number generator, an up counter, a clock module, and a plurality of matrix switch controllers. The matrix switch controllers and the up counter randomly change a power-on sequence applied across matrix switches in the matrix LED driver according to working random numbers generated by the pseudo random number generator. The circuit prevents jitter-induced noise from periodically reoccurring at the power source of the matrix LED driver, thereby reducing noise energy.

A variable light distribution light source includes an array-type light-emitting device. The array-type light-emitting device includes a power supply terminal and multiple pixel circuits electrically coupled and spatially arranged in a matrix. A power supply circuit includes a power supply unit that supplies electric power to the array-type light-emitting device. An output of a DC/DC converter is coupled to the power supply terminal VDD of the array-type light-emitting device via an output terminal. A voltage setting circuit generates a controllable correction voltage. A feedback circuit generates a feedback voltage based on the correction voltage and the control target voltage that corresponds to the output voltage of the DC/DC converter, and supplies the feedback voltage to a feedback pin of a converter controller.

A method is provided for storing light distributions of a matrix headlight system. The method includes loading, from a memory, first control data for lighting means of a first matrix light module for generating a first light distribution; feeding the first control data to a comparison module; loading, from the memory, second control data for the lighting means of the first matrix light module or for lighting means of a second matrix light module for generating a second light distribution and feeding the second control data to a comparison module. The method compares the first and second control data; stores the first control data for the first light distribution if there is a similarity or equality between the first and second control data; and linking the second control data for the second light distribution by means of a link to the control data for the first light distribution.

A vehicle headlamp system includes a vehicle supported power and control system including a data bus. A sensor module can be connected to the data bus to provide information related to environmental conditions or information relating to presence and position of other vehicles and pedestrians. A separate headlamp controller can be connected to the vehicle supported power and control system and the sensor module through the bus. The headlamp controller can include an image frame buffer that can refresh held images at greater than 30 Hz speed. An active LED pixel array can be connected to the headlamp controller to project light according to a pattern and intensity defined by the image held in the image frame buffer and a standby image buffer can be connected to the image frame buffer to hold a default image.

A method for driving LEDs involves arranging the LEDs in a matrix. The LEDs are designed as RGB LEDs and are driven by means of a duty cycle control protocol.

A lighting circuit turns on multiple semiconductor light sources. Multiple current sources are each coupled in series with a corresponding one from among the semiconductor light sources. A switching converter supplies a driving voltage V.sub.OUT across each of multiple series connection circuits formed of the multiple semiconductor light sources and the multiple current sources. A converter controller controls a switching transistor of the switching converter based on a relation between a voltage across one from among the multiple current sources and a reference voltage having a positive correlation with the temperature T.sub.j.

A lighting circuit turns on multiple semiconductor light sources. Multiple current sources are each coupled in series with a corresponding one from among the semiconductor light sources. A switching converter supplies a driving voltage V.sub.OUT across each of multiple series connection circuits formed of the multiple semiconductor light sources and the multiple current sources. A converter controller controls a switching transistor of the switching converter based on a relation between a voltage across one from among the multiple current sources and a reference voltage having a positive correlation with the temperature T.sub.j.

An embodiment relates to a technique for driving an LED display. In a method of controlling grayscale of pixels dividedly by N subframes (N is a natural number of 2 or greater), a pulse width modulation (PWM) control value of each subframe may be calculated by a precalculator disposed at a front end of latches, thereby simplifying a circuit.

A lighting apparatus includes a rectifier, a loading module, a constant current switch module and a current supplemental module. The rectifier is connected to an output of the AC power for receiving an AC signal to convert the AC signal to a positive wave signal. The loading module includes multiple loading units. The loading module is disposed on the output of the rectifier. The constant current switch module is connected to output of each loading unit and to control the working cycle of each loading unit so as to ensure a total passing current of the loading module is opposite in phase to the positive wave signal to keep output power constant. The current supplemental module supplies output current to the loading module when the positive wave signal is in sufficient to drive the loading module.

A lighting apparatus includes a rectifier, a loading module, a constant current switch module and a current supplemental module. The rectifier is connected to an output of the AC power for receiving an AC signal to convert the AC signal to a positive wave signal. The loading module includes multiple loading units. The loading module is disposed on the output of the rectifier. The constant current switch module is connected to output of each loading unit and to control the working cycle of each loading unit so as to ensure a total passing current of the loading module is opposite in phase to the positive wave signal to keep output power constant. The current supplemental module supplies output current to the loading module when the positive wave signal is in sufficient to drive the loading module.