Abstract: A driver circuit, solid state light (SSL) source assembly including same, and a method of driving an SSL source are provided. The driver circuit includes a rectifier, an inverter, a transformer, a PFC circuit, and a frequency control. The rectifier receives an AC voltage and provides an unregulated DC voltage. The inverter includes two switches, and receives respective control signals to operate these, to generate a resonate AC signal from the unregulated DC voltage. The transformer includes a primary winding coupled to the inverter, a secondary winding to be coupled to an SSL source through an output stage, and a feedback winding. The PFC circuit controls the inverter in response to signals representative of the unregulated DC voltage and the inverter's current. The frequency control generates the control signals to control the inverter's switching frequency in response to signals representative of the output stage's current and the feedback winding's current.

Abstract: Apparatuses, methods, systems, and circuits for light-emitting diode (LED) control are disclosed. In one embodiment, an LED control circuit can include a first pin receiving an input voltage supply; a second pin receiving a primary signal from a primary winding of a transformer coupled to the LED; a third pin coupled to a ground supply; and logic configured to estimate an output current and/or output voltage at the LED coupled to a secondary winding of the transformer from the input voltage supply and the primary signal.

Abstract: A liquid-cooled LED lighting device can be provided in which a temporal increase in the temperature of the tubing and the circulation pump when the LED light sources are turned off is prevented to ensure high reliability. The liquid-cooled LED lighting device can include an LED light source, a liquid cooling system including a heat receiving jacket and a radiator, an LED light source-driving power supply for supplying power to the LED light source, and a liquid cooling system-driving power supply for supplying power to the liquid cooling system. The LED lighting device can include a control unit, such as a timer circuit. The control unit can maintain supply of the power to the liquid cooling system for a predetermined period of time after supply of the power to the LED light source is stopped.

Abstract: A high-pressure discharge lamp lighting device is used for projector devices that allow controlling the mean electric power at a desired value with a slow processing speed. A color wheel rotates and disperses the beam from lamp into each of the color components, such that the electric power supplied to the lamp is controlled at different levels for each segment of the color wheel and the power feeding device control part finds the mean electric power by sampling the electric power supplied.

Abstract: In various embodiments, a circuit arrangement may include a voltage-measuring device embodied to measure an output voltage, wherein the voltage-measuring device is embodied to provide at its output a signal which is correlated with the measured output voltage, wherein the voltage-measuring device is coupled to a control device for the purpose of transmitting said signal to the control device, and wherein the control device is embodied to vary an off-time as a function of the measured output voltage.

Abstract: The present invention relates to a method and system that provides independent control over lighting within a computer case. Each inverter module is provided with its own switch to facilitate independent control of illumination. Preferably, the switches are located in a bus that fits within a drive bay and the inverter is directly mounted onto the housing that contains the switch. In another embodiment, the inverter is integrated in a printed circuit board that is inserted into the card slots (e.g. ISA, VESA, PCI, and PCI-Express card slot) on the mother board of the computer. Therefore, the on and off of CCFL inverter can be controlled by software application through the ISA, VESA, PCI, or PCI-Express bus.

Abstract: An alternating-current (AC) light-emitting diode (LED) apparatus is disclosed. A rectifier rectifies a power AC voltage to generate a rectified voltage, which is monitored by a controller. A number of LEDs are electrically coupled between the rectified voltage and a ground. A number of switches correspondingly control at least a portion of the LEDs respectively, wherein one terminal of each switch is electrically coupled to one electrode of the corresponding LED or LEDs. The switches are controlled by the controller according to the rectified voltage.

Abstract: A discharge lamp ballast is provided with a feedback control operation to provide optimal lamp current flow during an electrode heating operation. A startup circuit coupled together with a discharge lamp between output terminals of a DC-AC power converter having a plurality of switches. The startup circuit generates a high voltage to ignite the lamp. A lamp current sensor detects an amplitude of an output current to the lamp. A control circuit controls the switches in accordance with each of a plurality of control operations including a startup operation to ignite the lamp using the high voltage generated by the startup circuit, an electrode heating operation wherein an operating frequency of the switches is controlled to set the amplitude of the detected output current to a predetermined target current amplitude, and a normal operation wherein the operating frequency is reduced to maintain stable lighting of the lamp.

Abstract: A constant voltage dimmable LED (Light Emitting Diode) driver is disclosed that is compatible with all types of dimmers, including conventional phase cut (TRIAC) dimmers, and behaves like a conventional constant voltage driver which can be connected to any size of LED load that has a matching voltage rating. The driver produces a continuous train of pulses for driving the LED load and obtains an averaged measure of the voltage at the AC input for controlling the duty cycle of the continuous train of pulses. Therefore, when the averaged measure of the voltage at the AC input is reduced by a dimmer, the duty cycle reduces, resulting in a dimmed LED. The driver can be created by adding a few components to a conventional wide input range AC-DC converter without or with very little modifications.

Abstract: A driver (100; 200) for driving a dimmable load (L) is powered from phase-cut mains (U1) and determines the dimming state of the load on the basis of the phase of the cutting of the mains. The driver comprises: a load current generating device (130; 230) generating load current; a controllable auxiliary load (170; 270) connected to an input (131; 231) of the load current generating device; a control device (140; 240) controlling the auxiliary load. The control device has an input (141; 241) receiving a signal indicating the momentary voltage at the driver input. The load current generating device generates interrupted current pulses, so that the average output current corresponds to the dim command reflected by the phase cutting angle of the input mains. The control device switches the auxiliary load on during those time periods when the output current generated by the load current generating device is zero.

Abstract: A piezoelectric transformer driving device includes a piezoelectric transformer for outputting an alternating high voltage, a switching control part configured to control the control frequency of the control signal, a reference voltage waveform generation part configured to switch between a first voltage value, a second voltage value and a third voltage value, a monitor voltage generation part configured to generate a monitor voltage waveform based on the high voltage output from the piezoelectric transformer, and a comparison part configured to compare the reference voltage waveform with the monitor voltage waveform to generate a comparison result, and configured to supply the comparison result to the switching control part.

Abstract: Disclosed herein is a dimmer switch having a broad range of control with a relatively simple circuit having a number of safety features. The circuit employs a triac and diac to selectively conduct an AC power wave. A variable phase shift network having an improved range of control governs the firing angle of the diac. The variable phase shift network includes a first and second series R-C circuits coupled by a bridge resistor.

Abstract: A circuit arrangement for operating a low-pressure discharge lamp may include a voltage source with two terminals; switches; and a series resonant circuit; a controller configured to control the switches such that an AC voltage is applied to the resonant circuit; a PTC thermistor coupled on one side to a circuit point of the resonant circuit and on the other side, at least one of via a diode, to the first terminal of the voltage source and, via a diode to the second terminal of the voltage source; a resistive element connected in series with a diode in the circuit between a terminal of the voltage source and the PTC thermistor; and an evaluation device configured to tap off the voltage drop across the resistive element and being coupled to the controller in order to deactivate the controller.

Abstract: Disclosed is a single switch integrated electronic ballast circuit for a fluorescent lamp, comprising an input for receiving a rectified DC voltage; a power factor correction portion for shaping the input line current to substantially a sinusoidal waveform and in phase with the rectified voltage, wherein the power factor correction portion includes capacitors; an energy storage portion for storing energy during dimming operations of the fluorescent lamp, wherein the capacitors also form part of the energy storage portion; an inverter with a resonant tank forming a resonant circuit for converting the DC voltage to an AC voltage to be delivered to the lamp; and a single switch for: 1) shaping the input line current to a substantially sinusoidal waveform as part of the power factor correction portion; and 2) providing a square voltage waveform across the input of the resonant circuit resulting in a substantially symmetrical waveform across the output of the resonant circuit.

Abstract: A circuit for generating an output voltage to a top node of a plurality of LED strings. The circuit includes an inductor having a load current flowing therethrough and a switching transistor responsive to a switching control signal. An integrator generates a compensation voltage responsive to a voltage at a bottom node of the LED string and a reference voltage. Circuitry for combining an offset with the compensation voltage is responsive to the compensation voltage and the load current through the inductor. The offset is generated only during a step load change of the load current and substantially reduces voltage transients from the compensation voltage and the output voltage. A summation circuit sums the compensation voltage including the offset with at least the voltage at the bottom node of the LED string to generate a first control signal. A latch generates the switching control signal responsive to the first control signal and a leading edge blanking signal.

Abstract: In embodiments of the present invention improved capabilities are described for systems and methods that employ a control component and/or power source integrated in an LED based light source to control and/or power the LED light source wirelessly. In embodiments, the LED based light source may take the form of a standard light bulb that plugs into a standard lighting socket or fixture.

Abstract: Provided is a discharge lamp lighting device, which can control a load precisely while improving the practicability. When the difference of a count number (Nn) becomes a predetermined threshold value or less, a predictor circuit (35) predicts the timing, at which a current value (iQ1) becomes a peak value, on the basis of the rate of change of the difference. A switch selecting circuit (38), which is driven with a clock frequency higher than the sampling frequency of a first converter unit (32), turns off a field effect transistor (Q1) at the turn-off timing, and turns on a field effect transistor (Q2). A plurality of A/D converters (37a) are subjected to a multi-rate control, thereby to correct the threshold value of the predictor circuit (35) on the basis of the peak value of a lamp current (iOUT).

Abstract: The present invention relates to a lamp ballast circuit and a driving method. The lamp ballast circuit includes a voltage detector for detecting the level of a first voltage corresponding to an input voltage, a controller including an oscillator for changing the oscillation frequency according to the level of the first voltage, and an output unit for changing the frequency of the output voltage in correspondence to the oscillation frequency. Therefore, a lamp ballast circuit having less power consumption and that is operable by a lesser input current with less THD and a driving method thereof are realized.

Abstract: An LCD backlight driving device with an isolating transformer comprises a DC power supply, a square wave generator, a square wave controller, said isolating transformer and a driver transformer; wherein said isolating transformer has a primary side connected to said square wave generator and a secondary side connected to said driver transformer, since said isolating transformer is placed between said square wave generator and said driver transformer, it helps to effectively shorten a safety distance required for setting up said driver transformer; the present invention uses said isolating transformer to shorten the safety distance required than that of using said driver transformer directly and to decrease an area in implementing a circuit board and to cut cost of said device.

Abstract: A driving circuit for an LED lamp including no more than 4 strings each having an input and an output terminals outputs a DC voltage of no more than 70V to the input terminals. The driving circuit includes constant current circuits each coupled between the output terminal of a corresponding string and ground. An on-off control signal controls whether the constant current circuits work to control whether the LED lamp works. A dimming control signal controls a duty cycle of working of to the constant current circuits to control a brightness of the LED lamp. The driving circuit further includes an overvoltage protection circuit and a switch. When a voltage at one input terminal is too high or a short circuit occurs in one string, the overvoltage protection circuit outputs an overvoltage control signal and accordingly the switch forces the on-off control signal to control the constant current circuits not to work.

Abstract: The invention relates to an electronic candle and an electronic night lamp. The electronic candle includes a light-emitting diode (LED), a capacitor and a control circuit. The capacitor has a first terminal coupled to a first terminal of the LED, and a second terminal coupled to a common voltage. The control circuit has a first control terminal coupled to the first terminal of the LED, and a second control terminal coupled to a second terminal of the LED. In a detecting period, the control circuit provides a preset voltage across the first and second terminals of the LED so that the LED is reversely biased for a preset time. Then, the first control terminal of the control circuit is set to high impedance. Next, the control circuit detects a variation of a voltage of the first terminal of the capacitor with respect to time to determine whether to light up the LED.

Abstract: An alternating-current (AC) light-emitting diode (LED) apparatus is disclosed. A rectifier rectifies a power AC voltage to generate a rectified voltage, which is monitored by a controller. A number of LEDs are electrically coupled between the rectified voltage and a ground. A number of switches correspondingly control at least a portion of the LEDs respectively, wherein one terminal of each switch is electrically coupled to one electrode of the corresponding LED or LEDs. The switches are controlled by the controller according to the rectified voltage.

Abstract: A driver circuit has a Light Emitting Diode (LED) driver having an input and output. A switching device is coupled to an output of the LED driver. An edge detector is coupled to the LED driver. A timing device is coupled to the edge detector. A latch is coupled to the edge detector, the timing device and the switching device.

Abstract: A light emitting diode (LED) backlight driving system drives at least one LED array, and includes a boost power stage circuit, a controller, a multi-channel constant current driving circuit, a voltage dividing circuit, and an offset voltage generating circuit. The boost power stage circuit boosts direct current (DC) power signals to output driving voltage to drive the LED array. The multi-channel constant current driving circuit controls current flowing through the LED array, and outputs regulating voltage to the controller to regulate the driving voltage. The voltage dividing circuit divides the driving voltage to generate feedback voltage to send to the controller. The offset voltage generating circuit generates offset voltage to modify the feedback voltage according to at least one mode selection signal. The controller controls the driving voltage according to the modified feedback voltage and the regulating voltage.

Abstract: A electronic ballast according includes a DC power source circuit for generating a DC voltage from an AC power source, a pair of switching elements, an LC series resonance circuit, an inverter circuit for converting the DC voltage into a high frequency voltage to supply to a fluorescent lamp FL, and means such as a current transformer for detecting a current flowing into the fluorescent lamp FL, wherein oscillation of the inverter circuit is stopped when a value of a current flowing into the fluorescent lamp exceeds a predetermined value.

Abstract: A hybrid light source comprises a discrete-spectrum lamp (for example, a fluorescent lamp) and a continuous-spectrum lamp (for example, a halogen lamp). A control circuit individually controls the amount of power delivered to the discrete-spectrum lamp and the continuous-spectrum lamp in response to a phase-controlled voltage generated by a connected dimmer switch, such that a total light output of the hybrid light source ranges throughout a dimming range. The discrete-spectrum lamp is turned off and the continuous-spectrum lamp produces all of the total light intensity of the hybrid light source when the total light intensity is below a transition intensity.

Abstract: An electronic driver apparatus and methods are disclosed for driving power an organic LED or other large area solid state light source, in which a switch mode DC current source provides DC current to drive the light source according to a control input and a controller provides a ramped pulse modulated control input to the current source for at least some values of a dimming setpoint signal or value to mitigate damaging current spikes by controlling di/dt of the drive current.

Abstract: A driver circuit (10) for a light emitting diode comprises a first driver circuit (32, 32?, 32?) for generating a first current output for driving the light emitting diode, wherein the first driver circuit has a control switch for interrupting the supply of the first current output. A second driver circuit (50) is for generating a second current output for driving the light emitting diode, and the second driver circuit also has a control switch for interrupting the supply of the second current output. The overall output of the driver circuit comprises a pulse width modulated output current which alternates between a high current (Ihigh) generated by the first driver circuit and a low current (Ilow) generated by the second driver circuit. By providing separate driver circuits for two different current requirements, the circuits can be optimised for each function. For example the high current value can comprise an LED operation current, and the low current value can comprise a non-zero measurement current.

Abstract: A method for operating a switching power supply is provided. A switching element is switched on and off by a switching signal with a variable switching frequency. A frequency bandwidth is predefined for determining average levels of a frequency spectrum of the switching signal. The switching frequency is modulated by a modulation frequency greater than a frequency bandwidth.

Abstract: An LED driver controller comprises a voltage regulator for controlling an output voltage to a top of a plurality of LED strings responsive to at least a reference voltage. A plurality of first circuitries each associated with a node at a bottom of each of the plurality of LED strings compares a voltage at the bottom of each of the plurality of LED strings with a high reference voltage and a low reference voltage. Control logic generates a first control signal when the voltage at the bottom of each node of the plurality of LED strings exceeds the high reference voltage and generates a second control signal when the voltage at least one of node of the plurality of LED strings falls below the low reference voltage. Second circuitry responsive to the first control signal and the second control signal generates the reference voltage.

Abstract: An electronic ballast is provided for powering one or more discharge lamps independently connected in parallel. An inverter having a pair of switching elements converts a DC supply signal into AC power. A transformer has a primary winding coupled to an output terminal of the inverter. A load circuit includes independently operable discharge lamp circuits coupled in parallel with each other and across a secondary winding of the transformer. An inductance control circuit includes an inductive element coupled in series with the primary winding of the transformer and a bi-directional switch coupled in parallel across the inductive element. A switch state of the bi-directional switch is controllably adjustable between first and second switch states and in accordance with a desired duty ratio. A magnitude of a voltage across the secondary winding of the transformer and thereby across each lamp circuit is dependent on the switch state of the bi-directional switch.

Abstract: Supply circuits for supplying voltage and current signals to light sources (6) comprise switches (22, 32, 42, 52) and controllers (21, 31, 41, 51) to control the switches (22, 32, 42, 52) for reducing values of frequency components of harmonic content of power spectra of the light sources (6). By switching one of the voltage and current signals or by switching signals that result in one of the voltage and current signals, the other one of the voltage and current signals can be adjusted. The power spectrum of the light source (6) may be a function of the voltage and current signals. By adjusting one of them, the power spectrum can be adjusted such that values of frequency components of the harmonic content of the power spectrum are reduced. As a result, visible flicker is reduced in the light originating from the light source (6) without the use of energy storage capacitors for reducing this visible flicker.

Abstract: A circuit may include a switch mode power converter that intermittently enables a current path in response to a switch control signal; a duty cycle measurement circuit that generates a duty cycle value corresponding to a duty cycle of the switch control signal; and an evaluation circuit that activates a failure indication in response to the duty cycle value being outside of at least one limit.

Abstract: A lighting device that lights a discharge lamp which contains a pair of electrodes and light emission substance including mercury, includes: a first terminal connected with the electrode to which mercury easily adheres, and a second terminal connected with the electrode to which mercury is difficult to adhere; a setting unit which sets AC current supplied to the first and second terminals in a starting period from insulation break down of the discharge lamp until start of discharge between the tips of the pair of the electrodes; and a supplying unit which supplies AC current set by the setting unit to the first and second terminals, wherein the setting unit sets AC current such that the half-cycle electric quantity supplied to the first terminal becomes larger than the half-cycle electric quantity supplied to the second terminal in the initial term of the starting period under the condition in which the first terminal initially operates as cathode, and that the half-cycle electricity quantities supplied to th

Abstract: The invention relates to an image projection device having a light source (1) from which light at a different wavelength originates sequentially, having an image modulation arrangement (4) and a projection surface (6) on which images are perceived visually. The invention also relates to a light source drive circuit (2) for an image projection device such as this. An image projection device of this type is provided, in which the image modulation arrangement (4) comprises a polarization beam splitter (11) and two reflective display areas (12.1, 12.2), each display area (12.1, 12.

Abstract: Lighting is controlled by receiving an input signal, determining whether the input signal is an AC signal or a DC signal and generating a dimming command signal based on the determination of whether the input signal is an AC signal or a DC signal. For example, determining whether the input signal is an AC signal or a DC signal may include generating an average signal indicative of an average duty cycle of the input signal and determining whether the average signal meets a predetermined criterion.

Abstract: A high-power light-emitting diode (LED) driving circuit relates to a photoelectric technology field. An anode of D1 is connected to a constant current direct current (DC) power supply, and a cathode of D1 is connected to LED1, LED4, and one end of R1 and R2. LED1, ED2, and LED3 are connected in serial and then are connected to a collector of Q1, and LED4, LED5, and LED6 are connected in serial and then are connected to a collector of Q2. Emitters of the Q1 and Q2 are grounded. DZ1 is connected to LED1, LED2, and LED3 in parallel, and DZ2 is connected to LED4, LED5, and LED6 in parallel. The other end of R1 is respectively connected to a base of Q1 and one end of C2, and the other end of C2 is connected to the collector of Q2. The other end of R2 is respectively connected to a base of Q2 and one end of C1, and the other end of C1 is connected to the collector of Q1.

Abstract: A device for driving a backlight assembly includes a controller for outputting a control signal, a switching unit for outputting a DC square wave voltage in response to the control signal, an inverter for converting the DC square wave voltage into an AC voltage and a lamp for emitting light in response to the AC voltage, the lamp includes first and second glass tube portions having respective one ends bent and connected integrally to each other, first and second electrodes respectively formed at respective other ends of the first and second glass tube portions and a third electrode formed at the bent portion of the first and second glass tube portions, wherein electrical characteristics of the lamp are detected through the third electrode, wherein the electrical characteristics include voltage, current and impedance of the lamp.

Abstract: A light emitting driver circuit, system, and method are provided. The driver circuit system and method can be implemented in various ways. An embodiment includes a bypass circuit which diverts current from the LEDs whenever a switch coupled to the LEDs incurs residual current when turned off. In an additional or alternative embodiment, the residual current can be sensed and the amount of residual current used to trigger fetching of a compensation value. That compensation value can change a dimming function forwarded to the switch in order to compensate for, offset, or substantially eliminate the residual current through that switch.

Abstract: An operating circuit for at least one light-emitting diode (LED) incorporates a switched-mode regulator circuit to which a DC voltage is fed and which provides a supply voltage for the at least one light-emitting diode (LED) by means of a coil (L1) and a switch (S1) clocked by a control unit (SR). When the switch (S1) is on, energy is built up in the coil (L1), which is discharged through the at least one light-emitting diode (LED) when the switch (S1) is off. The control unit (SR) determines the time period between the switch (S1) switching off and subsequently switching on depending on the voltage across the at least one light-emitting diode (LED) and a temporally constant characteristic parameter of the coil (L1).

Abstract: A driving circuit comprises a first and a second switching circuit coupled in parallel to a node which is adapted to be coupled to a load, a first and a second detecting circuit, and a synchronizing circuit having an input coupled to the first and second detecting circuits and having an output coupled to the first and second switching circuits. The first detecting circuit detects a current associated with the first switching circuit and the second detecting circuit detects a current associated with the second switching circuit. The synchronizing circuit operates the first and second switching circuits to switch synchronously to a conducting state, and operates the first and second switching circuits to switch synchronously to a non-conducting state in the event that one of the first and second detecting circuits detects a current equal to or higher than a threshold value.

Abstract: A light control system having a light emitting device to produce a pre-determined light output is disclosed. The light control system includes a power circuit in electrical communication with the light emitting device for transmitting an electrical current to the light emitting device for controlling the light output, a timing circuit in electrical communication with the power circuit, wherein the timing circuit generates a pre-determined timing sequence and regulates a duty cycle of the power circuit in response to the timing sequence, and a feedback circuit in communication with the light emitting devices and the timing circuit, wherein the feedback circuit is adapted to monitor an electrical characteristic of the light emitting devices and control the timing sequence of the timing circuit in response to the electrical characteristics of the light emitting devices.

Abstract: An ignition circuit for igniting a gas discharge lamp generates a high voltage gas breakdown pulse by building up a current through a primary winding of a transformer. After a predetermined period and thus when a predetermined current flows through the primary winding, a capacitance is switched in series with said primary winding, thereby generating said high voltage gas breakdown pulse in a secondary winding of said transformer. After generating the high voltage pulse, the capacitance is short-circuited in order to preserve energy in the primary winding. The preserved energy is employed to build up energy again for a next high voltage pulse in a short time. At a high repetition rate and high voltage of the generated pulses, the ignition circuit according to the present invention is also suitable for driving the gas discharge lamp during a take-over period following the gas breakdown of the lamp for heating the lamp electrodes.

Abstract: An LED illuminant driving circuit and an automatic brightness compensation method thereof are provided herein. The automatic brightness compensation method includes: providing a target value; detecting an operation period of a pulse of an output of the LED illuminant driving circuit, the pulse is adapted to an LED illuminant for making the light emitting; deciding a peak value according to the target value and the operation period; and setting a peak level of the pulse according to the peak value. The LED illuminant driving circuit and the automatic brightness compensation method thereof provides a stable average current/voltage to the LED illuminant and avoids brightness variations of the light emitting.

Abstract: A light-weight, portable photocuring device possesses a single multi-wavelength light emitting diode (LED). The single LED backed with a heat sink is driven by a driving circuit and controlled by a timing circuit. A temperature monitor can be included in a closed loop to feed back and control the driver. A multi-plexing device regulates the current to individual ports on the LED effecting the dies allowing the overall wavelength and intensity of the emitted light by the apparatus to be controlled. Lenses and/or light guides in the device act to further direct the light.

Abstract: A circuit arrangement for operating a high pressure discharge lamp includes a bridge circuit with at least two switches, a control device controlling the switches. The bridge circuit is a half-bridge circuit having exactly two switches. The control device switches on and off in an alternating manner, the first switch and the second switch of the bridge circuit having a first frequency. When the first switch is switched off for controlling the other switch with a rectangular signal of a second frequency which is greater than the first frequency and a predeterminable connection duration. The circuit also includes a tension measuring device measuring an actual value of tension over the high pressure discharge lamp. A reference device provides at least one upper threshold value for the voltage via the high pressure discharge lamp. A comparison device compares the actual voltage over the high pressure discharge lamp with the threshold value.

Abstract: The present invention relates to a lamp driving circuit capable of achieving miniaturization by using a safe insulation type multi-output transformer.

Abstract: A driving circuit for LED includes: at least one LED; a light emission driving circuit having a first PWM unit and a power converting unit generating a driving current according to a signal generated by the first PWM unit and sending the driving current to the LED; a shunt parallel-connected with the LED; and a signal generating unit for generating a signal to switch on or off an electrical connection between the shunt and the light emission driving circuit. When the signal from the signal generating unit is at a high level, the electrical connection is switched on so that a majority of the residual driving current flows to the shunt.

Abstract: The present disclosure thus provides a technique for providing multi-level operation of ballast circuitry for discharge lamps. In one version, an auxiliary capacitance is switched in and out of circuit by a user controlled switch for lower the frequency of the voltage from the inverter to the transformer resulting in lower power output to the lamps. In another version, the auxiliary capacitance may be switched in and out of circuit by a user operated switch wherein the capacitance is connected to the secondary or output winding of the transformer for selectively reducing power to the lamps for reduced illumination. In other versions, auxiliary inductances are selectively switched in and out of circuit to alter the frequency of the primary voltage to the transformer. In another version, an auxiliary winding is selectively switched in and out of the secondary of the transformer for providing normal and reduced level power to the lamps.

Abstract: A circuit arrangement for starting and operating at least one discharge lamp is provided.