Introduced here are light sources for flash photography configured to produce high-fidelity white light that is tunable over a broader range of correlated color temperatures (CCTs) than conventional flash technologies. The light source can include multiple independently controllable color channels representing illuminants (e.g., light-emitting diodes) of different colors with varying degrees of saturation. Operating collectively, the multiple color channels can produce a high spectral quality white light corresponding to different CCTs (e.g., warm white light having a red hue, cool white light having a blue hue). Operating independently, these same color channels can be pre-flashed in a variety of prescribed sequences to probe the spectral characteristics of a scene, thereby allowing for an enhanced, spectrally matched white flash as well as collecting per-pixel reflectivity data that can be later used in during post processing of the captured image.

An airfield runway lamp controller is described herein. One airfield runway lamp controller includes a current sense transformer configured to detect a failure of a light source of an airfield runway lamp, and an alternating current (AC) switch configured to shunt the light source of the airfield runway lamp upon the current sense transformer detecting a failure of the light source.

An airfield runway lamp controller is described herein. One airfield runway lamp controller includes a current sense transformer configured to detect a failure of a light source of an airfield runway lamp, and an alternating current (AC) switch configured to shunt the light source of the airfield runway lamp upon the current sense transformer detecting a failure of the light source.

An intelligent mains power supply dimmer unit and LED lamp combination with improved power factor. The dimmer applies phase-cutting at a first angle for a first period to a mains voltage supplied to the lamp, whereafter the dimmer removes the phase-cutting. The lamp interprets the first angle as a first power level, which is then stored. The lamp retrieves the level after the first period and regulates its consumption accordingly.

A circuit for driving an LED lighting device from an AC power source includes a rectifier and one or more strings of LEDs. Each string of LEDs includes multiple LEDs. A controller produces control signals that open and close a set of switches that corresponding with the LED groups. The controller uses a current mirror with a pair of reference branches situated between a reference voltage and ground and between the switches and ground. Each reference branch has a first-in-line resistor between the reference voltage and the current mirror which primarily set the reference current through the controller by having the highest impedances, and the control signals are produced by a set of resistors on one of the branches. Each branch also has a last-in-line resistor between the current mirror and ground with the lowest impedances. The selection of the highest impedances and lowest impedances reduces sensitivity to temperature variations.

An LED tube lamp comprises a lamp tube, two end caps attached at two ends of the lamp tube respectively, a power supply disposed in one of the two end caps or separately in both of the end caps, an LED light strip disposed inside the lamp tube and a protective layer disposed on the LED light strip. The LED light strip comprises a mounting region and a connecting region. The plurality of LED light sources is mounted on the mounting region and two soldering pads are disposed on the connecting region. The mounting region and the connecting region are electrically connecting the plurality of LED light sources with the power supply. The protective layer comprises a plurality of first openings arranged on the mounting region for accommodating the LED light sources and two second openings are arranged on the connecting region for accommodating the two soldering pad.

A method for the operation of a vehicle light unit is provided. The light unit includes at least one light source module having several light sources and a control unit coupled to the light source module. The light sources each include a predetermined number of brightness levels. A predetermined number of light sources are combined by the control unit to form at least one controllable light source unit. In order to set a light distribution, the light sources that form the at least one light source unit are activated together and a brightness level of each light source of the at least one activated light source unit is set individually.

An optoelectronic circuit for receiving a variable voltage containing alternating increasing and decreasing phases. The optoelectronic circuit includes assemblies of light-emitting diodes mounted in series; a current source connected to each assembly by a switch; for each switch, a first comparison module for comparing the current passing through the switch with a current threshold; a second comparison module for comparing a voltage representing the voltage at the terminals of the current source with a voltage threshold; and a control module connected to the first and second comparison modules and designed to control the opening and closing of the switches, during each increasing phase and each decreasing phase, according to signals supplied by the first and second comparison modules.

An apparatus, method and system are disclosed for providing AC line power to lighting devices such as light emitting diodes (LEDs). A representative apparatus comprises: a plurality of LEDs coupled in series to form a plurality of segments of LEDs; first and second current regulators; a current sensor; and a controller to monitor a current level through a series LED current path, and to provide for first or second segments of LEDs to be in or out of the series LED current path at different current levels. A voltage regulator is also utilized to provide a voltage during a zero-crossing interval of the AC voltage. In a representative embodiment, first and second segments of LEDs are both in the series LED current path regulated at a lower current level compared to when only the first segment of LEDs is in the series LED current path.

A light emitting diode (LED) tube lamp configured to receive an external driving signal includes an LED module for emitting light, the LED module comprising an LED unit comprising an LED; a rectifying circuit for rectifying the external driving signal to produce a rectified signal, the rectifying circuit having a first output terminal and a second output terminal for outputting the rectified signal; a filtering circuit connected to the LED module, and configured to provide a filtered signal for the LED unit; and a protection circuit for providing protection for the LED tube lamp. The protection circuit includes a voltage divider comprising two elements connected in series between the first and second output terminals of the rectifying circuit, for producing a signal at a connection node between the two elements; and a control circuit coupled to the connection node between the two elements, for receiving, and detecting a state of, the signal at the connection node. The control circuit includes or is coupled to a switching circuit coupled to the rectifying circuit, and the switching circuit is configured to be triggered on or off by the detected state, upon the external driving signal being input to the LED tube lamp, to allow discontinuous current to flow through the LED unit.