Abstract: Various aspects of the present disclosure include a controlled current path having a load that draws current from the controlled current path. In response to a modulating voltage signal, current is controlled through the load which causes a transistor circuit, including a transistor, to switch between two current modes. Switching will subject the transistor to voltage stresses due to current in the controlled current path spiking towards a breakdown threshold of the transistor. In response to a first aspect of the modulating voltage signal and in one of the current modes, the current in the controlled current path is directed through the first current branch. In response to a second aspect of the modulating voltage signal and in the other current mode, the current in the controlled current path is diverted from the first current branch to a second current branch.

Abstract: A device for creating moving light effects has a light source that is configured to pulse a light ON and OFF according to a desired pattern so as to create a moving light effect that is visible when the light source is moved. Some such devices can be programmed to custom-select color sets that are pulsed ON and OFF according to the desired pattern. Other such devices enable the user to custom select one or more patterns. Some devices can control a duty cycle of and LED of the light source by applying an eight bit octet over each duty cycle time in which the LED is pulsed ON or OFF based on a binary “1” or “0” of the octet. A microlight for use in artistic moving light shows such as gloving can employ such moving light effects, and some such microlights can be operated and programmed using a single actuator button.

Abstract: A switchable light bulb assembly with integral power source is disclosed. The assembly has a light bulb, a power supply and a plug cap assembly. The plug cap assembly is configured to provide electrical communication between first and second electrical leads of a conventional light fixture. The light bulb is configured to be threadably insertable into a conventional, AC light fixture and provide electrical communication creating a circuit that can be opened or closed by operating the switch of the conventional light fixture. The power supply provides energy to the bulb when the circuit is closed.

Abstract: A power distribution system and method includes a controller that is configured to control a switching power converter. In at least one embodiment, the controller includes a compensation current control circuit to control a compensation current that reduces and, in at least one embodiment, approximately eliminates variations in current drawn by the controller during a particular operational time period. In at least one embodiment, the power distribution system is a lamp that includes the controller, a switching power converter, and one or more light sources, such as light emitting diodes.

Abstract: A solid state lighting device may include a power supply, a light emitting device, and a boost converter. The boost converter may have an input node electrically coupled to the power supply and an output node with the light emitting device electrically coupled between the output node and a reference node. The boost converter may include a switch electrically coupled in a current shunting path between the input node and the reference node, and a controller. The switch may be configured to shunt current from the power supply around the light emitting device. The controller may be configured to generate a pulse width modulation (PWM) signal to control a duty cycle of the switch to provide a pulse width modulated electrical current through the switch and a continuous electrical current through the light emitting device. Related methods are also discussed.

Abstract: An integrated circuit controller for use in a light emitting diode (LED) driver includes a comparator, an input signal absence timer and a regulator circuit. The comparator receives a first voltage representative of an ac input signal and compares the first voltage with a reference voltage. The input signal absence timer determines whether the first voltage is less than the reference voltage for a threshold duration and in response thereto generates a detect signal indicating that a portion of an ac half cycle is absent from the ac input signal. The regulator circuit controls switching of a switch to regulate a transfer of energy from the ac input signal to an LED load. The regulator circuit is disabled from switching the switch in response to the detect signal indicating the absence of the portion of the ac half cycle from the ac input signal.

Abstract: An illumination device includes a light source device which has a plurality of light emission regions including a first light emission region and a second light emission region, and is able to adjust the amount of light emitted from each of the plurality of light emission regions, a light source control device which controls the light source device such that, in a first period, the amount of light emitted from the first light emission region is different from the amount of light emitted from other light emission regions among the plurality of light emission regions, and in a second period, the amount of light emitted from the second light emission region is different from the amount of light emitted from the second light emission region in the first period, and an illumination optical system which superimposes light from the plurality of light emission regions in an illumination region.

Abstract: To provide a direction indicating apparatus that does not detect a break occurring in an indicator but can detect a break occurring in a direction indicating lamp incorporating an LED element with reliability. The direction indicating apparatus includes a pulse signal generating part, a first switching element, a direction indicating switch, first and second direction indicating lamp units, a break detecting part, a lighting state detecting part, an indicator part and an indicator driving part.

Abstract: To provide a direction indicating apparatus that is less susceptible to a change of a power supply voltage and can reduce the difference in brightness of a direction indicating lamp using an LED element between a direction indicating operation and a hazard operation. A direction indicating apparatus includes a pulse signal generating part, a first switching element, a variable resistor circuit, a direction indicating switch, a hazard switch, first and second direction indicating lamps, a voltage detecting part and a lighting status detecting part.

Abstract: A LED drive circuit according to the present invention comprises a controller and a programmable signal. The controller generates a switching signal coupled to switch a magnetic device for generating an output current to drive a plurality of LEDs. The programmable signal is coupled to regulate a current-control signal of the controller. The switching signal is modulated in response to the current-control signal for regulating the output current, and the level of the output current is correlated to the current-control signal.

Abstract: A control system includes a detection circuit, a control circuit, and a dummy load system. The detection circuit is operable to detect a voltage level change of a direct-current voltage and output an activating signal when detecting the voltage level change of the DC voltage. The control circuit is operable to receive the activating signal. The dummy load system is electrically connected to the control circuit, and the control circuit controls the dummy load system by generating a turn-on signal in response to receiving the activating signal. A dimmer system and a control method thereof are further disclosed herein.

Abstract: An arrangement and method is provided for operating a light-emitting device, wherein, a pulsed current is generated with a pulse frequency by a driver circuit, which has a clock pulse generator providing clock pulse signals for current pulsing, and a light-emitting device, which functionally couples to the driver circuit and which is formed with one or a plurality of organic light-emitting diodes, is loaded with the pulsed current with a pulse frequency of approximately 10 kHz to approximately 100 kHz, wherein: T_PWM<(T_rise+T_fall) and wherein T_PWM indicates the pulse length for the clock pulse signals generated by the clock pulse generator of the driver circuit and T_rise and also T_fall indicate the pulse rise time and the pulse fall time for the current pulses present at the one or the plurality of organic light-emitting diodes.

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 programmable luminaire system may comprise a programmable luminaire comprising an optic defining an optical chamber, a light source comprising a plurality of light-emitting elements, a controller operably coupled with the plurality of light-emitting elements, and an electrical connector electrically coupled with the controller. The system may further comprise a computerized device configured to electrically communicate with the programmable luminaire. The computerized device may be configured to transmit data to the programmable luminaire. The programmable luminaire may be configured to receive the data from the computerized device at the electrical connector. The controller may be configured to be programmed responsive to the data received by the controller.

Abstract: A system including first and second lamps, one of an inductor or a transformer, first and second switches, and a control module. The first lamp generates a first output of light having a first color. The second lamp generates a second output of light having a second color. The first and second outputs of light are mixed to provide a mixture of light having a third color. The transformer includes first and second coils. The first and second coils supply power respectively to the first and second lamps. The first and second switches are connected respectively to the first and second coils. The control module alters the third color by controlling (i) a state of the first switch to adjust a first amount of current supplied to the first lamp, and (ii) a state of the second switch to adjust a second amount of current supplied to the second lamp.

Abstract: Representative embodiments of the invention provide a system, apparatus, and method of controlling an intensity and spectrum of light emitted from a solid state lighting system. The solid state lighting system has a first emitted spectrum at a full intensity level and at a selected temperature, with a first electrical biasing for the solid state lighting system producing a first wavelength shift, and a second electrical biasing for the solid state lighting system producing a second, opposing wavelength shift. Representative embodiments provide for receiving information designating a selected intensity level or a selected temperature; and providing a combined first electrical biasing and second electrical biasing to the solid state lighting system to generate emitted light having the selected intensity level and having a second emitted spectrum within a predetermined variance of the first emitted spectrum over a predetermined range of temperatures.

Abstract: A light emitting diode module includes a main base board, a wireless communication module, multiple light emitting diodes, a power output control system and a control unit. The wireless communication module is used for receiving a control signal. The light emitting diodes are disposed on the main base board and include light emitting diodes having at least one color. The power output control system is electrically connected to the light emitting diodes. The power output control system adjusts an amount of current flowing through each light emitting diode to control the light emitting diodes to emit light by adjusting the amount of current. The control unit is electrically connected to the wireless communication module and the power output control system for controlling the power output control' system to adjust the amount of current of each light emitting diode.

Abstract: A current driver for a string of LEDs includes a first series connection of a first transistor and a first resistance and a second series connection of a second transistor and a second resistance. The first and second series connections are coupled in parallel between the string of LEDs and a voltage reference. An operational amplifier selectively drives the first and second transistors in response to a clock signal. A switch device driven by the clock signal alternately applies a reference voltage and a respective one of the voltages across the first and second resistances to inverting and non-inverting inputs of the operational amplifier in response to the clock signal. A storage circuit is coupled to the output of the operational amplifier to store the drive signals for the first and second transistors for application to the first and second transistors in the absence of output from the operational amplifier.

Abstract: A power source and control system is particularly suited for use in an outdoor landscape lighting system. The power source and control system includes at least one switching mode AC-to-DC power supply having an additional output stage for efficiently converting the DC output signal into another relatively low frequency AC signal for transmission to a plurality of buried power conductors. A Manchester encoded control signal is encoded at a relatively high frequency onto the AC signal sent over the buried power conductors so that intelligent LED lighting fixtures can be powered by the AC signal and selectively have their intensity changed when they decode the control signal.

Abstract: An LED (Light Emitting Device) light source (100), a pulse controller or pulse control module (130) for an LED light source, and a method are provided, for controlling relative timing and phase of LED light pulse generation and operation of peripheral devices, relative to a common timing reference. A system is provided comprising a pulse controller (130) for controlling synchronization of multiple LEDs (144) and/or other devices and peripherals (164), relative to a common timing reference. The pulse controller (130) comprises a processor (131) that programmatically executes a time based sequence of digital control signals (141) from received inputs (121) indicative of a pulse generation sequence.

Abstract: A light source apparatus includes a light-emitting module and a control unit. The light-emitting module is for providing a light. The control unit switches the light emitted from the light-emitting module between a first light and a second light, wherein the circadian stimulus value (CS/P value) of the second light is less than CS/P value of the first light, and the color temperatures of the second light and the first light are substantially the same as each other.

Abstract: It is provided an LED lighting device calibratable to 0 to 100% of wide range about a chromaticity and luminance of a illumination light by a simple configuration, and a driving method for the LED lighting device. The LED lighting device is provided with a first light-emitting unit and a second light-emitting unit differing a color temperature mutually, and a control circuit for executing a cyclic light/quench control of the first light-emitting unit and the second light-emitting unit, and for executing a light control of the first light-emitting unit and the second light-emitting unit by a PNM (Pulse Number Modulation) control in a fixed cycle so as to have a lighting period Ton for lighting/quenching the first light-emitting unit and the second light-emitting unit complementarily, and a quenching period Toff for quenching both the first light-emitting unit and the second light-emitting unit.

Abstract: An LED driver includes a transformer, current control loop and current adjustment circuit. The primary side of the transformer transfers energy to the secondary side of the transformer responsive to an input signal. The secondary side delivers output current to one or more LEDs at a magnitude corresponding to the amount of energy transferred to the secondary side. The current control loop controls current in the primary side so that the output current equals a reference current signal. The current adjustment circuit injects a current adjustment signal into the current control loop responsive to a phase-cut signal which removes a portion of the input signal. The current control loop also decreases the current in the primary side responsive to the current adjustment signal so that a brightness of each LED connected to the secondary side is decreased by an amount corresponding to the magnitude of the current adjustment signal.

Abstract: An arrangement wherein a plurality of LED strings are driven with a balanced drive signal, i.e. a drive signal wherein the positive side and negative side are of equal energy over time, is provided. In a preferred embodiment, the drive signal is balanced responsive to a capacitor provided between a switching network and a driving transformer. Balance of current between various LED strings is provided by a balancing transformer.

Abstract: A lighting apparatus includes a first LED unit and a second LED unit configured to provide different color temperatures. A pulse/voltage conversion circuit is connected between a power supply line and a low-potential side reference line, and configured to convert the pulses of input electric power into a voltage. A voltage dividing circuit is connected between the output terminal of the pulse/voltage conversion circuit and the low-potential side reference line, and configured to divide the voltage converted by the pulse/voltage conversion circuit. The dividing node of the voltage dividing circuit and the low-potential side terminal of the second LED unit are connected.

Abstract: The power consumption of a switch-mode power converter can be determined based upon at least one of a converter drive signal pulse width or a converter drive signal frequency. Such power consumption can be determined using an algorithm providing a functional relationship between switch-mode power converter power consumption and at least converter drive signal pulse width or frequency. Such algorithms can be either calculated using known component values or empirically determined. Such power consumption may also be determined using store power consumption data in a data store that is indexed by at least one of the converter drive signal pulse width or frequency.

Abstract: Disclosed is a method for adjustably controlling a light by concurrently tracking and controlling one or more lighting devices and apparatus thereof. The light device is connected to a control unit and is provided with at least one power switch. The control unit is provided for recognizing a switch operating code and for performing an adjustable controlling or an operating of each lighting device. Therefore, the present invention can provide more convenience and completeness of lighting configuration.

Abstract: A circuit assembly for operating a discharge lamp is disclosed having DC input terminals, a bridge circuit to implement a first bridge midpoint, an output coupling the discharge lamp thereto and a shunt resistor with a tapping point and a device for detecting overload operation. A device for ignition control of the discharge lamp, having an input for supplying a measurement signal and a switch control device is provided connected to the device for detecting overload operation and the ignition control device. The switch control device is designed to modify control signals for at least a first and second electronic switch as a function of the output signals of the device for detecting overload operation.

Abstract: An electric lighting driver circuit for driving an illuminating unit to emit light includes a flyback converting unit for converting a DC input voltage to a low ripple DC voltage, and a half-bridge converting unit electrically connected to the flyback converting unit, for converting the low ripple DC voltage to a low frequency, rectangular wave output voltage to drive the illuminating unit to emit light. The flyback converting unit includes a dual-output winding transformer connected to the half-bridge converting unit. The dual-output winding transformer includes a first winding at a primary side of the dual-output winding transformer and a second winding and a third winding at a secondary side of the dual-output winding transformer. The third winding converts leakage inductance attributed to the first winding and the second winding to electrical energy that is provided to the half-bridge converting unit.

Abstract: A method for controlling lighting devices includes providing the lighting devices. Each lighting device includes two or more LEDs, an AC/DC or DC/DC power converter, a controller/processor electrically connected to the AC/DC or DC/DC power converter, a light emitting diode (LED) current control circuit communicably coupled to the controller/processor and electrically connected to the AC/DC or DC/DC power converter and the two or more LEDs. One or more control signals are generated using the controller/processor and sending the one or more control signals to the LED current control circuit. An on/off signal having a cycle time for each LED is generated using the LED current control circuit in response to the one or more control signals and sending the on/off signal to each LED. A blended light is produced having a specified color based on how long each LED is turned ON and/or OFF during the cycle time.

Abstract: There is provided a light emitting diode driving apparatus, including: a power supplying unit converting input power into driving power according to a control and supplying the converted driving power to a light emitting diode channel; a driving unit controlling current flowing in the light emitting diode channel according to a pulse width modulation (PWM) dimming signal from the outside; and a controlling unit comparing a reference level set by a duty of the PWM dimming signal with a detection voltage level of the light emitting diode channel and controlling a power converting operation of the power supplying unit according to the comparison result.

Abstract: An electronic ballast includes a converter, an inverter circuit, a controlling unit, and a current crest factor improvement circuit. The controlling unit issues a first control signal to control the converter and issues a second control signal and a third control signal with opposite enabling/disabling states to control on/off states of corresponding switch elements of the inverter circuit. During a dead time between the enabling state of second control signal and the enabling state of the third control signal, these switch elements are simultaneously in the off state. During the dead time, the current crest factor improvement circuit is triggered to generate a restraining signal. According to the restraining signal, an output power of the converter is decreased to a predetermined value in real time or the converter is suspended.

Abstract: System and method for dimming control of one or more light emitting diodes. An example system includes one or more signal processing components configured to receive a first signal associated with a TRIAC dimmer, process information associated with the first signal, determine whether the TRIAC dimmer is in a first condition or a second condition, generate a second signal based on at least information associated with the first signal, and send the second signal to a switch. The one or more signal processing components are further configured to, if the TRIAC dimmer is determined to be in the first condition, generate the second signal to cause the switch to be opened and closed corresponding to a modulation frequency.

Abstract: Provided are a light-emitting element driving circuit for controlling luminance of light-emitting elements by using a PWM signal, and a display device including the light-emitting element driving circuit and plural light-emitting elements. The light-emitting element driving circuit includes: a control circuit configured to generate a control signal based on an input PWM signal in which ON-periods alternate with OFF-periods to form pulses; and a light-emitting element driving unit configured to drive the plurality of light-emitting elements by using the control signal. The control signal includes alternating first periods and second periods, where the first periods and the second periods correspond to the ON-periods and the OFF-periods of the input PWM signal, respectively. Each of the first periods includes an ON-period, and each of the second period includes an ON-period. The control signal includes a larger number of frequency components in comparison with frequency components of the input PWM signal.

Abstract: The present invention relates to a driver device (50a-50f) and a corresponding method for driving a load (22), in particular an LED unit comprising one or more LEDs (23). The proposed driver device comprises power input terminals (51, 52) for receiving a rectified supply voltage from an external power supply, power output terminals (53, 54) for providing a drive voltage and/or current for driving a load (22), a single stage power conversion unit (66a, 66b, 66c) coupled to the power input terminals (52) comprising a single switching element (60) and an energy storage element (Ch), both coupled to a switch node (55), wherein the power output terminals (53, 54) are represented by the output of said stage power conversion unit, a filter unit (68) coupled to said switch node (55), said filter unit comprising a filter inductor (Lc) and a filter capacitor (Cs), and a control unit (58) for controlling said switching element (60).

Abstract: Disclosed is an active constant power supply apparatus, which rectifies power having various intensities and frequencies without using a high capacity condenser for a smoothing circuit which degrades the power factor of a circuit, and supplies constant power to a load.

Abstract: A technique to eliminate perceptible flickering by LEDs being dimmed by PWM pulses is disclosed. A controllable oscillator controls a switching frequency of a converter for supplying a regulated current or regulated voltage. The converter controls a first switch at a switching frequency. A varying second signal level is generated by a spread spectrum control (SSC) circuit for controlling the oscillator to vary the switching frequency during operation. A PWM dimming circuit generates a string of PWM pulses that control a switch in series with the LEDs. The SSC circuit is synchronized with the PWM pulses to generate the same second signal level at a start of each PWM pulse, such that the switching frequency of the converter is forced to be substantially the same at the start of each PWM pulse while the pulse widths are constant. The repeating driving current waveform eliminates perceptible flicker by the LEDs.

Abstract: A light-emitting diode (LED) driving circuit is configured for driving at least one group of LEDs. The LED driving circuit includes a constant current source, a pulse width modulation (PWM) element, and at least one pulse frequency modulation (PFM) element. The constant current source is configured for generating a current signal with a constant current value; the PWM element is electrically connected to the constant current source and configured for modulating the current signal to generate a PWM signal corresponding to the current signal; the PFM element is electrically connected between the PWM element and the LED and configured for modulating a frequency width of the PWM signal to generate at least one PFM signal for driving the LED.

Abstract: Methods and circuits for driving one or more than one light-emitting diodes with a pulsed current are disclosed. Each of said circuits comprises: an inductance means; a switching unit for switching a current flowing through a loop comprising a direct current voltage, said light-emitting diodes and the inductance means and for either switching a current flowing from the inductance means to the direct current voltage or switching a current flowing from the direct current voltage to the inductance means; a switching control unit for controlling said switching to regulate the current of the inductance means for supplying the pulsed current to said light-emitting diodes. Accordingly, the present invention provides a switching-mode pulsed current supply circuit for driving white light-emitting diodes that is able to provide higher perceived brightness levels and has much longer lifetime than existing light-emitting diode drivers.

Abstract: A light emitting diode (LED) backlight driving circuit is disclosed in the present disclosure. The LED backlight driving circuit in configured to power an LED backlight module, and comprises: a voltage stabilizing circuit, being configured to receive an input voltage and filter the input voltage to output a stabilized direct current (DC) voltage; a first boost circuit and a second boost circuit connected with the voltage stabilizing circuit respectively, being configured to receive the stabilized DC voltage and boost the stabilized DC voltage for output to the LED backlight module; and a selection control circuit, being configured to alternately select one of the first boost circuit and the second boost circuit to power the LED backlight module. The LED backlight driving circuit of the present disclosure can improve the voltage boosting efficiency and reduce the cost, so it is of great utility.

Abstract: It is provided an LED lighting device calibratable to 0 to 100% of wide range about a chromaticity and luminance of a illumination light by a simple configuration, and a driving method for the LED lighting device. The LED lighting device is provided with a first light-emitting unit and a second light-emitting unit differing a color temperature mutually, and a control circuit for executing a cyclic light/quench control of the first light-emitting unit and the second light-emitting unit, and for executing a light control of the first light-emitting unit and the second light-emitting unit by a PNM (Pulse Number Modulation) control in a fixed cycle so as to have a lighting period Ton for lighting/quenching the first light-emitting unit and the second light-emitting unit complementarily, and a quenching period Toff for quenching both the first light-emitting unit and the second light-emitting unit.

Abstract: An LED drive circuit connectable to a phase control type light adjuster includes a first reference voltage generation portion that generates a first reference voltage, a second reference voltage generation portion that generates a second reference voltage according to a phase angle of the light adjuster, an input voltage detection portion that detects a size relationship between an input voltage and a threshold value voltage, a current draw-out portion that draws out a current in accordance with the first reference voltage or the second reference voltage from an electricity supply line that supplies electricity to an LED drive portion, and a switch portion that in accordance with a detection result by the input voltage, detection portion, performs switching between an output from the first reference voltage generation portion to the current draw-out portion and an output from the second reference voltage generation portion to the current draw-out portion.

Abstract: An electronic dimming ballast that accommodates miswiring of fluorescent lamp filaments (e.g., miswiring the corresponding lamp sockets) is disclosed. The electronic dimming ballast may drive a plurality of gas discharge lamps. Each gas discharge lamp may have a respective filament. The electronic dimming ballast, via the filament miswire protection element, may establish the same voltage across a first of the filaments regardless of whether the filaments are wired in series or in parallel. The filament miswire protection element may have an impedance that is approximately equal to an impedance of at least one of the filaments. The filament miswire protection element may include one or more capacitors, inductors, and/or resistors. The filament miswire protection element may include only a capacitor.

Abstract: The off-peak powered lighting system provides light to offices, buildings and structures via banks of LED light fixtures. The off-peak system is electrically coupled to battery power source during peak power cycles and then is coupled to an electrical power grid during off-peak cycles. The banks of LED lights, in the offices, buildings and structures, include LED lighting fixtures, each with a multiplicity of LEDs. The LED banks are controlled by a plurality of control switches. A power cycle switch coupled intermediate the power grid and the control switches. controllably couples the grid to the control switches or couples the battery source to the control switches based upon a control command, generated by a controller which creates off-peak and peak control commands. The controller is either a timer, a programmable time of day, or a remotely controllable element subjected to grid-originated peak commands.

Abstract: An integrated circuit within an integrated circuit package, including a configuration module and a timing module. The configuration module configures the integrated circuit using a configure operation performed via N pins of the integrated circuit package, where N is an integer greater than 1. The timing module is configured to control on/off timing of (N*M) light emitting diodes arranged in N columns and M rows connected to the N pins and M pins of the integrated circuit, respectively, where M is an integer greater than 1. During a first period, the configure operation utilizes the N pins. During a second period, the N*M light emitting diodes receive data from the M pins and refresh signals from the N pins. The second period is different than the first period.

Abstract: A method for powering two circuits in a portable light that are connected by a single conductive chassis so that each of the two circuits is able to have time shared access to a power source.

Abstract: A light-emitting element driving circuit system is provided in which a plurality of current paths, in each of which a light-emitting element and a switching element which is controlled to be switched ON and OFF for causing light to be emitted from the light-emitting element are connected in series, are placed in parallel to each other, wherein an ON time of each switching element is adjusted based on a light-emission period which is a period in which the light-emitting elements are caused to emit light in a circulating manner, such that a number of switching operations of each switching element is reduced.

Abstract: A ballast that selectively operates multiple lamps is provided. The ballast includes a switching network, capable of operating in a number of switching configurations. The ballast also includes a control circuit, and two lamp control switches. The control circuit is connected to the switching network, and provides respective control signals via respective output terminals as a function of the switching configuration of the switching network. Each lamp control switch is in parallel with its lamp and is connected to a respective output terminal. The first lamp control switch is connected to a ballast power supply, and either provides power to the first lamp or does not, depending on the first control signal. The second lamp control switch is connected to the first lamp control switch and to ground, and either provides power to the second lamp or does not, depending on the second control signal.

Abstract: A lighting power source provides AC or DC power as needed to power an electric light source. A first switching element and a diode are coupled in series across output ends of a DC power source, with a second switching element coupled across the diode. An inductor forms an output loop with the diode. A driving capacitor has a first end coupled to a node between the first switching element and the diode. A charging power source is coupled to a second end of the driving capacitor and supplied with power from the DC power source. During a charging operation, a control circuit charges the driving capacitor by turning on the second switching element while maintaining the first switching element in an OFF state. During a normal operation which follows the charging operation the control circuit repeatedly turns on/off the first switching element while maintaining the second switching element in the OFF state.

Abstract: The present invention discloses a LED dimming method and a LED dimming system, wherein the LED dimming method comprises the following steps: A: calculating the equivalent current flowing through the LED in accordance with the duty cycle message of the input PWM signal; and B: regulating the current flowing through the LED to the equivalent current. Because the equivalent current flowing through the LED is calculated by the duty cycle message D of the input PWM signal while the duty cycle is not actually regulated, the present invention realizes the aim that the dimming uniformity is improved by linearly regulating the current flowing through the LED. Meanwhile, transformer noise will not be generated because current flows through the transformer in the overall dimming cycle.