Abstract: A method includes activating a transistor providing current to a load via an inductor based on values stored at a first timer and at a second timer. The second timer is enabled based a value of a current conducted at the inductor and based on a value of a reference current. The transistor is deactivated in response to determining that a measurement of time elapsed at the first timer is a predetermined multiple of the second measurement of time.

Abstract: A lighting device which outputs a DC current to a load, the lighting device including: a downconverter circuit which includes a switching element and steps down a DC voltage input to the downconverter circuit; and a controller which controls turning on and off of the switching element, wherein the controller has operating modes including a detection mode in which the controller detects a time taken for a current through the switching element to reach a predetermined value after the switching element turns on, the current through the switching element representing the DC current output to the load.

Abstract: An analog electronic circuit for driving a string of LEDs including input terminals for accepting connection to AC voltage, a current regulation circuit operatively coupled to receive an AC voltage from the input terminals and to provide an output for connection to drive the string of LEDs. Included is a current regulation circuit configured to limit the current flow through the string of LEDs on a half-cycle basis to a predetermined value. Also disclosed are an overvoltage circuit configured to switch off electrical connection between the AC voltage and the string of LEDs upon the AC reaching a predetermined high voltage value on a half-cycle basis in order to limit power. Overtemperature and power factor correction are also addressed. Also improving efficiency by shorting part of the LED string during the lower voltage phase of the input AC voltage.

Abstract: A voltage sampling system is provided. The voltage sampling system includes a first and a second input paths and a signal-processing module. The first input path includes a first input voltage-dividing resistor unit, a second input voltage-dividing resistor unit and a first DC voltage-dividing resistor unit to generate a first input divided voltage and a first DC bias voltage to further generate a first sampled voltage signal according to a first input voltage and a DC voltage source. The second input path includes a third input voltage-dividing resistor unit, a fourth input voltage-dividing resistor unit and a second DC voltage-dividing resistor unit to generate a second input divided voltage and a second DC bias voltage to further generate a second sampled voltage signal according to a second input voltage and the DC voltage source. The signal-processing module receives the first and the second sampled voltage signals to perform signal processing.

Abstract: An LED driving circuit is provided. The LED driving circuit includes an input unit which receives an input dimming signal for driving an LED array, a PWM signal generating unit which extends an on-period of the input dimming signal to form an extended dimming signal, and generates a PWM signal using the extended dimming signal, a DC-DC converter which supplies output voltage to the LED array using the PWM signal, and an LED driving unit which drives the LED array using the input dimming signal.

Abstract: A lighting system includes a digital addressable lighting interface (DALI) master controller, a lighting driver, and a signal converter. The DALI master controller is connected to a management server. The lighting driver operates a lighting device including a light emitting diode (LED). The signal converter is connected to the DALI master controller by a DALI bus operating according to a DALI communication protocol, and is communicatively connected to the lighting driver via a wireless communication connection operating according to a wireless communication protocol. The signal converter inter-converts a signal transmitted and received from the DALI master controller according to the DALI communication protocol and a signal transmitted to and received from the lighting driver according to the wireless communication protocol so as to enable communication between the lighting driver and the DALI master controller.

Abstract: A multi-function lighting system is provided. A design of multiplex configuration of a multi-diode lighting module and a design of optical time domain modulation of an electric controlling system are applied to a lighting system which senses environmental conditions to automatically or artificially change a color, a light intensity and a color-temperature of a light to influence people's feelings and moods. At the same time, the environmental sensing device further feedbacks an information of humidity or temperature so that parameter of optimum light environment can be set accordingly. The multi-diode lighting module is applied to the design of the lighting system, such that the lighting system can be manufactured in a customization way to meet varied requirements in the landscaping and optical designs, not only reducing the cost and increasing mass production rate but also providing multi-functions including landscaping lighting, ergonomic lighting, plant lighting and air purifying.

Abstract: A backlight driver and a method of driving the same are disclosed, which remove an unstable duty ratio by filtering an input PWM signal so as to prevent backlight flicker although the input PWM signal becomes unstable. The backlight driver includes a duty ratio detector for detecting a duty ratio of an input pulse width modulation (PWM) signal; a duty ratio filter for detecting a difference between a current duty ratio received from the duty ratio detector and a previous duty ratio, determining whether the detected duty ratio difference satisfies a preset reference condition, selecting one of the current duty ratio and the previous duty ratio, and outputting the selected duty ratio; and a PWM generator for generating an output PWM signal obtained when a selected duty ratio from the duty ratio filter is reflected in an input synchronization signal, and outputting the output PWM signal to a backlight unit.

Abstract: An apparatuses, methods and systems for beacon transmission of a fixture that includes sensed information are disclosed. For an embodiment, the fixture includes a sensor operative to generate a sense signal, communication circuitry operative to maintain a link with a network, a wireless transmitter, and a controller. The controller is operative to receive the sensed signal, manage communication with the network, and manage transmission of beacons through the wireless transmitter, wherein the beacons include information associated with the fixture, wherein the information includes at least information of the sense signal.

Abstract: A high-frequency power supply apparatus for supplying high-frequency power to a load the impedance of which greatly fluctuates is provided, wherein a stable high-frequency current is always maintained without having overcurrent or overvoltage generated in a drive circuit thereof. In the high-frequency power supply apparatus, a constant-current conversion circuit is connected between an LCR series resonant circuit and a half-bridge drive circuit, high-frequency current of the LCR series resonant circuit is controlled by the voltage of the half-bridge drive circuit, and a constant-current function is applied to impedance variation of the load. Due to the constant-current conversion circuit, the gate of a MOSFET of the half-bridge drive circuit is driven with a parallel capacitor using a transformer inserted in the LCR series resonant circuit, and the phases of the high-frequency current of the LCR series resonant circuit and the output of the half-bridge drive circuit are maintained to be constant.

Abstract: The disclosure comprises: linking a first terminal of the capacitance to the mid-point of a first voltage divider bridge, applying a first voltage to a second terminal of the capacitance, maintaining a voltage of a mid-point of the first divider bridge near a reference voltage, and discharging a mid-point of a second divider bridge with a constant current. When a voltage of the mid-point of the second bridge reaches a first voltage threshold, applying a second voltage to the second terminal of the capacitance, and measuring the time for the voltage to reach a second threshold.

Abstract: A method for operating an LED light source, wherein the portion of the electrical power (Pout) fed to the LED light source during the operation that is converted into light (Plight) is determined on the basis of temperature measurements. On the basis thereof, a compensation factor (KAGE COMPENSATION) that compensates the aging of the LED light source can be determined, wherein a correlation factor that was determined at the start of the putting into service of the lamp is taken into account in order to determine the portion of the electrical power converted into light (Plight).

Abstract: An LED driver for powering an LED fixture is described, the LED driver including a switched mode power supply for providing a current to the LED fixture, and a control unit for controlling a switch of the switched mode power supply. The control unit includes an input terminal for receiving a set point representing a desired output characteristic of the LED fixture. The control unit is further configured to periodically determine an opening instance of the switch and a closing instance of the switch, determining an average current estimate based on at least one measurement of the current to the LED fixture at least one measurement instance determined on the basis of at least one of the opening instance or the closing instance of the switch, and applying the average current estimate as a feedback signal representing the average current for controlling the LED current.

Abstract: An organic light emitting display device includes a DC-DC converter to supply first and second voltages to one or more pixels. The DC-DC converter includes a first voltage supply to convert an input voltage to a first voltage and a second voltage supply to convert the input voltage to a second voltage. The first and second voltages are coupled to opposing ends of the one or more pixels. The first voltage supply includes a first inductor between a first input terminal and first node, a first transistor between the first node and a reference potential, a second transistor between the first node and first output terminal, a first diode between the first node and a second node, a second diode between the second node and first output terminal, and a first switch between the second node and first output terminal.

Abstract: A gate driver unit includes an input stage, an output stage, a read/write interface, and a monitoring stage. The input stage is configured to receive control signals and forward the control signals to the output stage and the monitoring stage. The read/write interface is configured to receive configuration data and forward the configuration data to the monitoring stage. The monitoring stage is configured to capture and evaluate signals of a power switch connected to the gate driver unit and synchronize the evaluation of the signals of the power switch to the control signals. The evaluation of the signals and the synchronization of the evaluation are based on the configuration data.

Abstract: Techniques are presented for synchronous rectification control (SRC) of a DC-DC converter in an electrified vehicle (EV) can include determining a required output current for the DC-DC converter based on a secondary voltage of a secondary battery system of the EV, the DC-DC converter being configured to convert a primary voltage from a primary battery system of the EV to the secondary voltage. The techniques can include determining, at the controller, a switching frequency for the DC-DC converter that causes the DC-DC converter to output the required output current. The techniques can include determining turn-on and turn-off delays of the DC-DC converter based on the required output current and the switching frequency using one or more look-up tables. The techniques can also include controlling the DC-DC converter efficiency based on the turn-on and turn-off delays.

Abstract: A light emitting diode driving apparatus may include: a light emitting diode emitting light by receiving rectified power; a driver driving the light emitting diode based on a voltage level of the rectified power; and a controller limiting an operation of the driver based on a voltage applied to the driver and a hysteresis reference value.

Abstract: An image display device and controlling method thereof are disclosed, by which a 3D stereoscopic image are more comfortably appreciated in consideration of appreciation environment. In a mobile terminal including a display unit configured to variably display a 2D (2-dimensional) image and a 3D stereoscopic image of a parallax barrier type, the controlling method includes determining a play mode of a source image including a left eye image and a right eye image for implementation of the 3D stereoscopic image, if the determined play mode is a 3D play mode, determining a brightness of the source image, and enhancing an output brightness of the source image in accordance with an output brightness of the source image.

Abstract: Disclosed is a light emitting diode lighting apparatus capable of improving a power factor and temperature characteristics. The light emitting diode lighting apparatus according to a preferred embodiment of the present invention includes a light source having a plurality of light emitting diode channels and performs a current regulating operation to allow a light source to emit light. The light source uses a current path provided by current regulating to emit light.

Abstract: A discharge lamp lighting method for controlling lighting of a discharge lamp includes varying an amount of generation (current value) of overshoot and undershoot generated in a waveform of a drive current that is applied when driving the discharge lamp, according to a magnitude of drive power supplied to the discharge lamp and a drive mode.

Abstract: A non-isolated light-emitting diode (LED) driving circuit has a rectifier, a switching device, a sampling resistor, a power supply unit, a controller unit and a lighting unit. The controller unit samples a voltage at the sampling resistor to compare the sampling voltage with reference voltage to determine if the switching device is turned on or off. When the switching device is turned on, a charging current outputted from the rectifier charges the power supply unit and the power supply unit simultaneously discharges to supply power to the lighting unit. When the switching device is turned off, a discharging current outputted from the power supply unit supplies power to the lighting unit. As there are no transformer and electrolytic capacitor, the non-isolated LED driving circuit is simplified, durable and cost-effective.

Abstract: A lighting device or an apparatus for use with a light source has one or more sensors, intelligence in the form of programmed processors and communication capabilities. Each sensor is configured to monitor one or more conditions external to a lighting device not directly related to operational performance of the respective lighting device. Programming provides a standardized interface to enable processing of sensed conditions from sensors of different types.

Abstract: A circuit arrangement (11) for driving light-emitting diodes comprises a number N of current regulators (14, 15), which each comprise a control input (17, 19) and a load terminal (18, 20) for providing a load current (IL1, IL2) to an electrical load (12, 13) which can be coupled, in each case having a light-emitting diode (12?, 13?). Furthermore, the circuit arrangement (11) comprises a compensation circuit (16), which is coupled to the control inputs (17, 19) of the number N of current regulators (14, 15) and is designed to adjust the respective load current (IL1, IL2) in a load-dependent manner.

Abstract: A method and an apparatus for control a flash in a mobile terminal. In the method, a current use state of the mobile terminal is detected. A use amount of a current of the flash is controlled depending on the current use state. The flash is allowed to emit light depending on the controlled amount of the current.

Abstract: The present invention discloses a light source module, a light source module driving circuit and a driving method. The driving circuit comprises: a power supply, which provides input voltage; a control signal generating circuit, which inputs the input voltage provided from the power supply and outputs an enable signal and a dimming signal; a driving chip, which is connected with the power supply and connected to the enable signal and the dimming signal output from the control signal generating circuit, driving the light source of the light source module according to the enable signal and the dimming signal. Through the above way, the present invention utilizes the input voltage to generate the enable signal and the dimming signal. Therefore, it only needs to provide external input voltage to control the light source module in operation, which makes the control more convenient and reliable.

Abstract: Disclosed are a wireless power receiving apparatus, a wireless power transmission system, and a wireless power receiving method. The wireless power receiving apparatus includes a power receiving coil for receiving a power signal wirelessly transmitted, a rectifier circuit for rectifying the power signal into direct current (DC) output power, a switching unit for controlling input of the power signal to the rectifier circuit at an rear end of the power receiving coil, and a control unit for measuring a voltage of the DC output voltage, comparing the voltage with a predetermined allowable voltage, and controlling an operation of the switching unit.

Abstract: A power control circuit for a power supply system including a control unit, a driving circuit and a power supply unit is disclosed. The power control circuit includes a current detection unit, a voltage detection unit and a power detection unit. The current detection unit is used for detecting a current signal. The voltage detection unit is used for detecting a voltage signal. The power detection unit is connected with the current detection unit, the voltage detection unit and the control unit for acquiring a power signal according to the current signal and voltage signal. By comparing an adjustable power reference signal with the power signal, the control unit issues a control signal to the driving circuit. In response to the control signal, the power supply unit is driven by the driving circuit to output an adjusted power to the load according to the adjustable power reference signal.

Abstract: An LED driver for powering an LED fixture is described, the LED driver comprising: an input terminal for receiving an input power; a power converter arranged to receive an input power at an input terminal of LED driver; convert the input power to an output power for powering the LED fixture a sensing device for sensing the input power received by the power converter; a control unit arranged to control an output characteristic of the power converter; a configuration terminal connected to the control unit; the control unit further being arranged to: receive, from the sensing device, a signal representing the sensed input power; receive, via the configuration terminal, a configuration signal representing a maximum wattage for the LED driver; and control the output characteristic of the power converter such that the input power as sensed does not exceed the maximum wattage.

Abstract: A tunable LED lamp for producing biologically-adjusted light having a housing, a power circuit, a driver circuit disposed within the housing and electrically coupled with the power circuit, and a plurality of LED dies electrically coupled to and driven by the driver circuit. The driver circuit may drive the plurality of LED dies to emit a pre-sleep light having a first spectral power distribution and a general illuminating light having a second spectral power distribution. The pre-sleep light may be configured to affect a second biological effect in an observer. The LED lamp may be configured to fit in a troffer fixture. The LED lamp may also be a troffer fixture.

Abstract: An alternating current power supply apparatus sends an alternating current power to a dimmer. The dimmer dims the alternating current power to fetch a dimmed power. The dimmer sends the dimmed power to a rectification unit. The rectification unit rectifies the dimmed power to fetch a rectified power. The rectification unit sends the rectified power to an integration sampling unit and a light emitting diode. The integration sampling unit integrates, samples and converts the rectified power to fetch an integration voltage signal. The integration sampling unit sends the integration voltage signal to a voltage-to-current control conversion unit. The voltage-to-current control conversion unit converts the integration voltage signal to fetch a driving current signal to drive the light emitting diode. The driving current signal is constant, so that the light emitting diode is not blinking.

Abstract: The present invention is suitable for an LED controlling field, and provides an LED controlling circuit with high power factor and an LED lighting device. In the present invention, by using an LED current controlling circuit with high power factor comprising a plurality of output current controlling modules, a resistor Re and a reference voltage generating module, the LED groups is driven accordingly in a piecewise manner to be on and a current flows through the LED groups according to the input voltage of the LED strip, without sampling the input voltage of the LED strip by a sampling circuit and without increasing the number of high cost component, which increase the utilization of the LED, the power factor of the whole LED controlling circuit and the efficiency of the system, thereby solving the problem of low power factor and low efficiency system existing in the prior art.

Abstract: A driving circuit for a light emitting diode lighting apparatus includes a driving data memory device in which central portion driving data for driving the light emitting diodes are separated into many sections within one cycle of the driving power; a drive controller for reading the central driving data, charging driving data, and outer driving data stored in the driving data memory device; a first D/A converter for converting digital central driving data and outer driving data output from the drive controller to analog signals, and a second D/A converter for converting charging driving data to an analog signal; a static current driving device having static current driving devices respectively connected to tabs of light emitting diodes according to an output signal of the first D/A converter; and a charging static current driving device for charging the charging capacitor according to the output signal from the second D/A converter.

Abstract: The present invention relates to a light-emitting diode (LED) driving circuit for lighting, which divides a specific pattern of driving data for a number of sections within one period or a half period of driving power, stores the divided data in a driving data storage device, and drives LEDs connected in series in an LED array unit using the driving data so as to drive the LEDs with high efficiency, a high power factor, and low total harmonic distortion (HTD).

Abstract: The present invention provides a method for reducing standby power consumption, which includes providing an LED driving chip; connecting an integrator to a brightness control terminal of the driving chip, connecting the integrator to a comparator, connecting the comparator to a field-effect transistor, connecting the field-effect transistor to the driving chip; connecting the driving chip to a first power source, connecting a high voltage switch terminal of the driving chip via a resistor to a second power source, connecting the brightness control terminal and the integrator to a control source, and connecting the integrator to a reference voltage; and conducting the first and second power sources, the control source, and the reference voltage to allow the integrator and the comparator to pull down voltage of the high voltage switch terminal of the driving chip according to the conduction of the field-effect transistor by a signal of the brightness control terminal.

Abstract: Current is provided to a segment of light emitting diodes in a plurality of segments of light emitting diodes. Embodiments generate a current and sequentially and separately switch the current to each segment of light emitting diodes in the plurality of segments of light emitting diodes for a corresponding period of time, where the corresponding period of time is based on an average current of the generated current.

Abstract: There are provided a power supply device switching power input to a primary side to supply the power to a predetermined load connected to a secondary side electrically insulated from the primary side and a control circuit thereof. The control circuit generates a predetermined PWM signal to apply the PWM signal to a dimming switch connected to an end of the load and controls a switching frequency of the primary side, based on a control voltage generated according to a feedback signal according to the power supplied to the load and the PWM signal, and the control voltage maintains a constant difference between a minimum voltage level and a maximum voltage level regardless of a duty of the PWM signal.

Abstract: A semiconductor light emitting apparatus includes an elongated hollow wavelength conversion tube that comprises an elongated wavelength conversion tube wall having wavelength conversion material such as phosphor dispersed therein uniformly or non-uniformly. The tube need not be cylindrical. A semiconductor light emitting device is oriented to emit light inside the elongated hollow wavelength conversion tube to impinge upon the elongated wavelength conversion tube wall and the wavelength conversion material dispersed therein.

Abstract: A LED light for replacing a fluorescent light in a fluorescent fixture is disclosed. The LED light is compatible with the existing fluorescent light fixture and ballast. The LED light includes a failure indicator to show whether a failure of the LED light is due to a failure of the ballast or a problem within the light. The LED light includes a color change mechanism, which may be controlled by an electromagnetic field or an input current to the LED light, thus making it compatible with current dimmer systems.

Abstract: Sensors and lighting components are provided that are capable of matching an emitted color to a color observed at a remote location. The sensor measures a light characteristic at a first location, and provides data to a remote lighting component, such as via a wireless connection. The lighting component is configured to emit light based upon the light characteristic, and thus is able to match an observed lighting condition. The lighting component may match the color, intensity, temperature, pattern, texture, or other characteristic of light at a remote location.

Abstract: A light emitting device is provided which is capable of displaying in desired colors stably by controlling a change in luminance of OLED when an organic light emitting layer is degraded or there is a change in temperature of the surroundings. A reference value for the amount of current flowing into a pixel portion is calculated from data of a video signal. Then, the pixel portion displays an image in accordance with the data of the video signal and the drive current at the time is measured for all of OLEDs in the pixel portion. The two voltage values supplied from a variable power supply to the pixel portion are corrected such that the measured drive current approaches the reference value. With the above structure, lowering of luminance which accompanies degradation of an organic light emitting layer is prevented and a clear image can be displayed as a result.

Abstract: A light emitting element drive apparatus capable of outputting the lowest voltage satisfying drive conditions and having high light emitting efficiency and low power loss, and a portable apparatus using the same, comprising an LED drive apparatus to which LEDs of different drive voltages required for emitting light are connected in parallel and driving one or more LEDs, wherein the LED drive apparatus 10 has drive circuits connected to the corresponding LEDs among a plurality of LEDs and driving the corresponding LEDs with luminances based on set values and power supply circuits for deciding a drive voltage value required for the highest light emission among one or more LEDs driven to emit light based on drive states of drive circuits (for example terminal voltages of the current source) and supplying a drive voltage having at least the decided value to LEDs in parallel.

Abstract: A light control system and a light control method thereof are disclosed. The light control system is used for controlling a light-emitting device. The light control system includes an ambient status sensing module, a storage module, a controlling module, and a driver module. The ambient status sensing module is used for sensing an ambient state to generate an ambient state value. The storage module has a database for storing a plurality of parameter values, wherein the plurality of parameter values are corresponded to a plurality of ambient state values. The controlling module is used for searching the plurality of parameter values stored within the database according to the ambient state value, so as to generating a controlling signal. The driver module is used for driving the light-emitting device according to the control signal.

Abstract: The light-emitting device having an equivalent circuit, includes at least four terminals, numbered from first terminal to fourth terminal, for electrical power feeding; a first light-emitting diode, arranged between the first terminal and the second terminal, configured to not emit light when a voltage is applied between the second terminal and one of the third terminal and the fourth terminal, and configured to emit light when a. voltage is applied between the first terminal and one of the third terminal and the four the terminal; and a second light-emitting diode, arranged between the third terminal and the fourth terminal, and configured to not emit light when the voltage is applied between the third terminal and one of the first terminal and the second terminal and configured to emit light when a voltage is applied between the fourth terminal and one of the first terminal and the second terminal.

Abstract: A portable lighting device, such as a flashlight, with a mechanical power switch and multiple operating modes is provided. The mechanical power switch is disposed in series with the controller for the lighting device and acts as the user interface to the controller to change modes of operation. Because the mechanical power switch is in series with the controller, the portable lighting device does not consume battery power when the mechanical switch is open. A state machine coupled to the controller is polled by the controller each time it is powered up to determine the operational mode of the lighting device.

Abstract: The invention relates to a method for operation of an actively clocked PFC circuit with a directly or indirectly connected load circuit at the output of the PFC circuit, wherein the load circuit has a lighting means, in particular one or more LEDs, wherein the PFC circuit is supplied at least with a measurement signal which reflects the power consumption of the load circuit or with an external control signal which indicates the power consumption, and a control circuit adjusts the mode of operation of the PFC circuit continuously or preferably in two or more steps, depending on the control signal or measurement signal.

Abstract: A light emitting diode (LED) controlling device may include: a driving circuit unit converting input power into an output voltage and providing the output voltage to an LED module; a detecting circuit unit positioned between the driving circuit unit and the LED module and detecting the output voltage and an output current of the LED module; and a controlling circuit unit converting an external signal into a reference signal and comparing the reference signal with at least one of the output voltage and the output current to control an output of the LED module. The external signal may be one of a first signal provided by a sensor module, a second signal provided by a communications module, and a third signal provided by an output control module.

Abstract: Methods and apparatus, including computer program products, for a lighting application for an interactive electronic device (12). A system (10) includes an interactive electronic device (12) remotely linked to a lighting system (14), the interactive electronic device (12) including a processor (16), a memory (18), the memory including an operating system (26), one or more user applications (28) and an interactive lighting process (100), a user interface (20), one or of the interactive more sensors (22), a communications device (24), and the lighting system (14) including a light controller (50) linked to a light-emitting unit (52), the light controller (50) including a communications device (54) responsive to one or more lighting adjustment signals received from the interactive lighting process (100).

Abstract: An insulated power supply device includes: an electric power conversion unit, a rectifier, a filter, a detection unit, a control circuit, and a signal transmission unit. The control circuit generates and outputs a control signal for a switching element that controls a current to be flown through a primary side of the electric power conversion unit. The signal transmission unit transmits, to the control circuit, a detection signal by the detection unit for detecting an output current or an output voltage. An output control pulse signal having control information in a duty ratio can be supplied as an outputted control signal individually to both of the control circuit and a secondary side of the electric power conversion unit. The output current or the output voltage can be thereby controlled.

Abstract: From a start of a lighting until a predetermined time period passes, a high-pressure discharge lamp is supplied with a constant current (Ib) until the lamp power reaches a predetermined wattage (Plow). When the lamp power reaches the wattage (Plow), current is supplied to maintain the lamp power at the wattage (Plow). After another predetermined time period passes, current is supplied to maintain the lamp power at a rated lamp wattage (Pr). While this lamp power is being maintained, the size of the lamp current is limited to a current limit (Ia). The current (Ib) and the wattage (Plow) satisfy a relationship Ia·0.7?Ib?Ia·0.9 and Pr·0.5 Plow?Pr·0.9 to accelerate an initial building of luminous flux while reducing drainage to the electrodes.

Abstract: A lighting device includes an LED light source (20) operable by electric power supplied to the device, and a control system (23) receiving electric power from an external power supply (26) and supplying power to the light source (20). The control system (23) also being operable of operating in a second mode to supply power to the light source (20) only on receipt by the control system (23) via the power supply (26) of a signal identifying said device. Thus the device (24) can be incorporated in a conventional lighting circuit or a circuit in which the devices (24) are individually controlled.