A load control device for controlling the intensity of a lighting load, such as a light-emitting diode (LED) light source, may include a power converter circuit operable to receive a rectified AC voltage and to generate a DC bus voltage, a load regulation circuit operable to receive the bus voltage and to control the magnitude of a load current conducted through the lighting load, and a control circuit operatively coupled to the load regulation circuit for pulse width modulating or pulse frequency modulating the load current to control the intensity of the lighting load to a target intensity. The control circuit may control the intensity of the lighting load by pulse width modulating the load current when the target intensity is above a predetermined threshold and control the intensity of the lighting load by pulse frequency modulating the load current when the target intensity is below the predetermined threshold.

A load control device for controlling the intensity of a lighting load, such as a light-emitting diode (LED) light source, may include a power converter circuit operable to receive a rectified AC voltage and to generate a DC bus voltage, a load regulation circuit operable to receive the bus voltage and to control the magnitude of a load current conducted through the lighting load, and a control circuit operatively coupled to the load regulation circuit for pulse width modulating or pulse frequency modulating the load current to control the intensity of the lighting load to a target intensity. The control circuit may control the intensity of the lighting load by pulse width modulating the load current when the target intensity is above a predetermined threshold and control the intensity of the lighting load by pulse frequency modulating the load current when the target intensity is below the predetermined threshold.

A load control device for controlling the intensity of a lighting load, such as a light-emitting diode (LED) light source, may include a power converter circuit operable to receive a rectified AC voltage and to generate a DC bus voltage, a load regulation circuit operable to receive the bus voltage and to control the magnitude of a load current conducted through the lighting load, and a control circuit operatively coupled to the load regulation circuit for pulse width modulating or pulse frequency modulating the load current to control the intensity of the lighting load to a target intensity. The control circuit may control the intensity of the lighting load by pulse width modulating the load current when the target intensity is above a predetermined threshold and control the intensity of the lighting load by pulse frequency modulating the load current when the target intensity is below the predetermined threshold.

Disclosed herein are systems and methods for powering light sources to reduce optical and/or electrical interference between the light sources and optical components in the same environment. The light sources may be powered using power modulation signals, whose frequency may be varied across modulation periods. Optionally, the frequency may be varied randomly or pseudo randomly. The systems and methods may additionally or alternatively introduce phase modulation into the control signals for driving channels of light sources. A phase difference in the control signals to at least two channels can reduce or avoid simultaneous or synchronous driving of the channels. The systems and methods described herein can vary one or more properties (e.g., frequency, phase shift, delay, duty cycle, power, etc.) of the power modulation signals.

A method for driving one or more electrically powered light sources, such as LED modules, may include applying a pulse-width-modulated signal thereto having a pulse-repetition frequency and a duty-cycle, the duty-cycle being selectively variable in order to vary the intensity of light emitted by the light source or light sources. To counter the occurrence of temporal light artefacts, or TLAs, the method may include frequency modulating the pulse-width-modulated signal (V.sub.PWM) by varying the pulse-repetition frequency thereof around a certain value between a lower frequency value and a higher frequency value, thus giving rise to a signal with combined FM/PWM modulation.

A method for driving one or more electrically powered light sources, such as LED modules, may include applying a pulse-width-modulated signal thereto having a pulse-repetition frequency and a duty-cycle, the duty-cycle being selectively variable in order to vary the intensity of light emitted by the light source or light sources. To counter the occurrence of temporal light artefacts, or TLAs, the method may include frequency modulating the pulse-width-modulated signal (V.sub.PWM) by varying the pulse-repetition frequency thereof around a certain value between a lower frequency value and a higher frequency value, thus giving rise to a signal with combined FM/PWM modulation.

A system includes an isolated converter having a power transformer with a primary winding, a secondary winding, and an auxiliary winding. The system also includes: 1) a first switch coupled to the primary winding; 2) a switch controller coupled to the first switch; and 3) a bias power regulator circuit coupled to the auxiliary winding and the switch controller. The bias power regulator circuit includes a second switch. The bias power regulator circuit is configured to provide a bias supply output voltage to the switch controller based on a first set of modes that modulate a switching frequency of the second switch and based on a second mode in which the second switch stays off.

A power adjusting circuit, an LED power supply and an LED luminaire. The power adjusting circuit includes: a zero-crossing detecting unit, adapted to generate a zero-crossing detection signal according to an high-frequency signal, wherein the zero-crossing detection signal is a pulse wave or a square wave, and the high-frequency signal is a sine wave or an AC wave; a signal processing unit, adapted to determine a second number of pulses or square waves of the zero-crossing detection signal corresponding to an adjustment signal that is input externally, according to a first number of pulses or square waves of the zero-crossing detection signal corresponding to a full-load operation of a functional device; a counting unit, adapted to generate a switch control signal according to the first number and the second number; and a switch unit, adapted to control an output of the high-frequency signal according to the switch control signal.

A power adjusting circuit, an LED power supply and an LED luminaire. The power adjusting circuit includes: a zero-crossing detecting unit, adapted to generate a zero-crossing detection signal according to an high-frequency signal, wherein the zero-crossing detection signal is a pulse wave or a square wave, and the high-frequency signal is a sine wave or an AC wave; a signal processing unit, adapted to determine a second number of pulses or square waves of the zero-crossing detection signal corresponding to an adjustment signal that is input externally, according to a first number of pulses or square waves of the zero-crossing detection signal corresponding to a full-load operation of a functional device; a counting unit, adapted to generate a switch control signal according to the first number and the second number; and a switch unit, adapted to control an output of the high-frequency signal according to the switch control signal.

A system for obtaining a multispectral image of a scene includes a first light source, a second light source, at least one imaging sensor, and a controller. The first light source emits light in a first wavelength range. The second light source emits light in a second wavelength range. The at least one imaging sensor senses light in the first wavelength range reflected off of the scene during a first illumination sensing period and senses light in the second wavelength range reflected off of the scene during a second illumination sensing period. The controller is electrically coupled to the at least one imaging sensor. The controller interprets signals received from the at least one imaging sensor as imaging data, stores the imaging data, and analyzes the imaging data with regard to multiple dimensions. The first illumination sensing period and the second illumination sensing period are discrete time periods.