Abstract: The present disclosure is directed to an input impedance control circuit. In one embodiment, the automatic input impedance control circuit includes a circuit controller that comprises a module for calculating an impedance and a control logic module, wherein the control logic module provides a current enable signal and a current control output signal, a driver in communication with the circuit controller for receiving the current enable signal and the current control output signal, an input voltage sensing circuit in communication with the module for calculating the impedance and the control logic module and an input current sensing circuit in communication with the module for calculating the impedance.

Abstract: Provided is a circuit for adjusting light-emitting diode (LED) current; the circuit comprises: a single-output constant current source (21), a multi-path LED output circuit (22) and a control bus (20) connected to the multi-path LED output circuit (22); any given LED output circuit comprises: a load circuit (23), an adjustment circuit (24), a current regulation circuit (25) and an adjustment control circuit (26). The circuit for adjusting LED current provided in the technical solution of the present invention adjusts the current of each LED output circuit via the load circuit, the adjustment circuit, the current regulation circuit and the adjustment control circuit, thus adjusting characteristic parameters such as color, color temperature, color rendering index, brightness and the like of the LED light source, thereby avoiding the problem of high cost caused by using multi-path constant current DC/DC circuit to adjust the current of each path.

Abstract: A two-wire load control device (such as, a dimmer switch) is operable to control the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) and has substantially no minimum load requirement. The load control device includes a bidirectional semiconductor switch (such as a thyristor), which may be operable to remain conductive independent of the magnitude of a load current conducted through semiconductor switch and to conduct the load current to and from the load during a single half-cycle. The dimmer switch comprises a control circuit that conducts a control current through the load in order to generate a gate drive signal for rendering the bidirectional semiconductor switch conductive and non-conductive each half-cycle. The control circuit may provide a constant gate drive to the bidirectional semiconductor switch after the bidirectional semiconductor switch is rendered conductive each half-cycle.

Abstract: A LED driving apparatus and a LED illumination system using the same are provided. The LED driving apparatus adapted to drive a LED load having at least one power specification includes a driving circuit, an output detecting circuit and an output adjusting circuit. The driving circuit provides an adjustable output current for driving the LED load. The output detecting circuit is coupled to the driving circuit and the LED load for detecting a driving voltage of the LED load to generate a first detecting signal. The driving circuit drives the LED load under a constant current in response to the first detecting signal. The output adjusting circuit is coupled to the output detecting circuit. The output adjusting circuit is controlled to adjust a signal level of the first detecting signal, such that the adjustable output current has at least one current adjusting range.

Abstract: A light-emitting control circuit includes a light-emitting unit, a switch module, a driving unit, a first energy storage unit, and a second energy storage unit. The driving unit outputs a first signal to turn on the switch module, and outputs a second signal to turn off the switch module. The power supply provides power to charge the first energy storage unit when the switch module is turned on, an electric conductivity of the switch module accordingly gradually increases, and the voltage across the light-emitting unit accordingly gradually increases, causing the light emitted by the light-emitting unit to gradually become brighter. The second energy storage unit discharges to provide voltage to the light-emitting unit when the switch module is turned off, the light emitted by the light-emitting unit gradually becomes darker.

Abstract: A plasma processing apparatus may include a process chamber having an interior processing volume; a first RF coil to couple RF energy into the processing volume; a second RF coil to couple RF energy into the processing volume, the second RF coil disposed coaxially with respect to the first RF coil; and a third RF coil to couple RF energy into the processing volume, the third RF coil disposed coaxially with respect to the first RF coil, wherein when RF current flows through the each of the RF coils, either the RF current flows out-of-phase through at least one of the RF coils with respect to at least another of the RF coils, or the phase of the RF current may be selectively controlled to be in-phase or out-of-phase in at least one of the RF coils with respect to at least another of the RF coils.

Abstract: A supplemental dimming circuit for an electronic led driver comprising a universal control section has a VCC3 startup and low conduction period circuit for providing a current during start-up and during low conduction periods; a CC hold current circuit for providing a hold current for the dimmer at low conduction periods; a latch circuit for providing a current draw latch on; and a PWM synchronized dimming circuit for providing a PWM signal dependent on the conduction period of the dimmer in real time. The supplemental dimming circuit also has a socket and a plug. The universal control section is on a daughter board that is pluggable to the socket. The VCC3 startup and low conduction period circuit creates a low AC voltage dummy load, which is a resistive load. The CC hold current circuit creates a low AC current dummy load that is a constant current load.

Abstract: The present disclosure is directed to an input impedance control circuit. In one embodiment, the automatic input impedance control circuit includes a circuit controller that comprises a module for calculating an impedance and a control logic module, wherein the control logic module provides a current enable signal and a current control output signal, a driver in communication with the circuit controller for receiving the current enable signal and the current control output signal, an input voltage sensing circuit in communication with the module for calculating the impedance and the control logic module and an input current sensing circuit in communication with the module for calculating the impedance.

Abstract: Disclosed is an electromagnetic coupling multi-output control circuit having a detection unit, a switching unit and a coupling unit, and the coupling unit is coupled to a side of a transformer of a power driving device to sense and produce a second driving voltage, such that the transformer has a multi-output function. The switching unit is provided for receiving and outputting the second driving voltage to a second driving load, and the detection unit is provided for detecting the second driving voltage to produce a detection value, so that the switching unit analyzes the detection value and switches outputting a frequency of the second driving voltage to stabilize the voltage value of the second driving voltage, so as to flexibly increase the number of output voltages of the power driving device while lowering the cost and expand the scope of applicability.

Abstract: Disclosed is an electromagnetic coupling multi-output control circuit having a detection unit, a switching unit and a coupling unit, and the coupling unit is coupled to a side of a transformer of a power driving device to sense and produce a second driving voltage, such that the transformer has a multi-output function. The switching unit is provided for receiving and outputting the second driving voltage to a second driving load, and the detection unit is provided for detecting the second driving voltage to produce a detection value, so that the switching unit analyzes the detection value and switches outputting a frequency of the second driving voltage to stabilize the voltage value of the second driving voltage, so as to flexibly increase the number of output voltages of the power driving device while lowering the cost and expand the scope of applicability.

Abstract: The present disclosure is directed to an input impedance control circuit. In one embodiment, the automatic input impedance control circuit includes a circuit controller that comprises a module for calculating an impedance and a control logic module, wherein the control logic module provides a current enable signal and a current control output signal, a driver in communication with the circuit controller for receiving the current enable signal and the current control output signal, an input voltage sensing circuit in communication with the module for calculating the impedance and the control logic module and an input current sensing circuit in communication with the module for calculating the impedance.

Abstract: A light-emitting diode (LED) bulb has an LED within a shell. The LED bulb includes a driver circuit for providing current to the LED. The drive circuit has a thermal protection circuit, which includes a first positive thermal coefficient thermistor with a first switching temperature connected in series with a second positive thermal coefficient thermistor with a second switching temperature. The driver circuit includes a switch-mode power supply (SMPS) controller with an input pin and an output pin. The thermistors are connected to the input pin. When either thermistor temperature is above the respective switching temperatures, the thermal protection circuit causes the SMPS controller to produce a signal with a second duty cycle on the output pin. When both thermistor temperatures are below the respective switching temperatures, the thermal protection circuit causes the SMPS controller to produce a signal with a first duty cycle on the output pin.

Abstract: A light-emitting device is provided. The light-emitting device comprises a substrate and a light-emitting element. The substrate comprises a first variable resistor, a second variable resistor, an insulation portion and a carrier. The insulation portion is located between the first variable resistor and the second variable resistor. The carrier is surrounded by the insulation portion, and the light-emitting element is disposed on the carrier. The first variable resistor, the second variable resistor and the insulation portion respectively penetrate the substrate.

Abstract: An electronic ballast includes an inverter circuit, a variable inductor unit and a control circuit. The variable inductor unit is electrically coupled between the inverter circuit and an illumination device. The control circuit controls the variable inductor unit according to an operation mode of the inverter circuit such that an equivalent inductance of the variable inductor unit has a variation fed back to the inverter circuit, to further change the operation mode of the inverter circuit. An illumination apparatus and a method for protecting the electronic ballast are also disclosed.

Abstract: A power system for a dielectric barrier discharge system, such as used for generating ozone, can include a full bridge inverter stage and parallel resonant tank outputting a signal for powering a dielectric barrier discharge cell stack. The inverter stage is controlled using a combination of pulse width modulation (PWM) and frequency modulation (FM) to enable soft switching through all load conditions—from full load to light load. A current control loop error amplifier compensator can provide a duty cycle adjustment signal to a phase shift PWM controller chip that generates the switching signals for the inverter stage. A feedback signal is also used to adjust a clock frequency time constant of the PWM controller chip to provide the FM. In one embodiment, the feedback signal is an output of an inverting amplifier connected at an output of the current control loop error amplifier compensator.

Abstract: A two-wire load control device (such as, a dimmer switch) is operable to control the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) and has substantially no minimum load requirement. The dimmer switch includes a bidirectional semiconductor switch, which is operable to be rendered conductive each half-cycle and to remain conductive independent of the magnitude of a load current conducted through semiconductor switch. The dimmer switch comprises a control circuit that conducts a control current through the load in order to generate a gate drive signal for rendering the bidirectional semiconductor switch conductive and non-conductive each half-cycle. The control circuit may provide a constant gate drive to the bidirectional semiconductor switch after the bidirectional semiconductor switch is rendered conductive each half-cycle.

Abstract: A light emitting device that provides white light of various color temperatures by using a double-sided light emitting element, a light emitting system comprising the same, and a method of fabricating thereof are provided. The light emitting device includes a double-sided light emitting element including a first light emitting element on one side of a substrate and emits light having a first wavelength and a second light emitting element on the other side of the substrate and emits light having a second wavelength, wherein the first wavelength and the second wavelength are different each other, a first variable resistor coupled to the first light emitting element and adjusting a first driving power applied to the first light emitting element, and a second variable resistor coupled to the second light emitting element and adjusting a second driving power applied to the second light emitting element.

Abstract: A control circuit of a light-emitting element comprises a rectifying unit (30) which full-wave rectifies an alternating current power supply, a switching element (38), a reference voltage generating unit (40) which generates a reference voltage (Vref), and a comparator (42) which receives a voltage (Srec) rectified by the rectifying unit (30), compares a comparative voltage (Vcmp) corresponding to a current flowing to an LED (102) and the reference voltage (Vref), and controls switching of the switching element (38) according to a comparison result, wherein the reference voltage generating unit (40) comprises a voltage dividing circuit having a transistor (Q1) in which a resistance value between a source and a drain is changed according to the voltage rectified by the rectifying unit (30), and outputs, using the voltage dividing circuit, the reference voltage (Vref) according to the voltage (Srec) rectified by the rectifying unit (30).

Abstract: Exemplary embodiments provide an apparatus, system and method for power conversion to provide power to solid state lighting, and which may be coupled to a first switch, such as a dimmer switch. An exemplary system comprises: a switching power supply; solid state lighting; a first adaptive interface circuit to provide a resistive impedance to the first switch and conduct current from the first switch in a default mode; and a second adaptive interface circuit to create a resonant process. An exemplary apparatus comprises: a switching power supply; and an adaptive interface circuit comprising a resistive impedance coupled in series to a reactive impedance to conduct current from the first switch in a first current path in a default mode, and further comprising a second switch coupled to the reactive impedance to conduct current from the first switch in a second current path, with the adaptive interface circuit further damping oscillation when the first switch turns on.

Abstract: Disclosed are various embodiments of driver circuits that operate to excite devices for light emissions therefrom regardless of the impedance ratings thereof. The driver circuits are particularly suited to service both low impedance light emitting diode lighting devices and high impedance halogen lamps.

Abstract: An operating circuit is provided for an LED, which receives a voltage, and which supplies a voltage for the LED via a coil, having a first switch clocked by a control/regulating unit. Power is stored temporarily in the coil when the first switch is activated so that the power is discharged via a diode and via the LED when the first switch is turned off. A capacitor is arranged in parallel to the LED and maintains current through the LED during the demagnetization of the coil. A first switch generates a first sensor signal dependent on the current flowing through the first switch, and/or a second sensor unit, which detects whether demagnetization of the coil unit has occurred and generates a sensor signal. The signals are fed to the control/regulating unit and processed. The control/regulating unit reactivates the first switch when the coil is demagnetized and/or the diode is blocking.

Abstract: In one embodiment, a self-oscillating electronic ballast for discharge tube type lamps which increases efficiency and has IEC-standard end of lamp life protection. Efficiency is enhanced by placing primary resonant capacitor (351a) in parallel with cathode conduction loop (270) while retaining a minimal secondary resonant capacitor (351b) within the cathode conduction loop (270). IEC-standard end of lamp life protection is achieved by placing the primary winding (323) of the base drive transformer (357) within the cathode conduction loop (270) of the ballast circuit, and employing a dampening capacitor (307) to suppress the erroneous base drive signals generated by coupling in the secondary windings (325, 327) as a lamp nears end of lamp life. Other embodiments are described and shown.

Abstract: LED calibration systems and related methods are disclosed that use the photo-sensitivity of LEDs to correct for variations between LEDs during initial production and over the lifetime of systems using LEDs. The disclosed systems and methods include methods to set the color or color temperature produced by a group of LEDs during the manufacturing of a device such as a lamp, an LED display, or an LCD backlight, and maintaining such color or color temperature over the operating life of such a device. The methods involve measuring the intensity and/or wavelength of light produced by each LED within a group of LEDs and adjusting an amount of light generated by the LEDs to produce precise color and intensity from the group of LEDs. Two methods that operate some of the LEDs in photovoltaic or photoconductive mode to measure the light intensity produced by other LEDs in the group are presented.

Abstract: The present invention provides LEDs and zener diodes that are homopolar and connected in parallel to constitute the first set of LED and zener diode and a second set of LED and zener diode; the first LED and zener diode set and the second LED and zener diode assume a reverse polarity series connection to constitute the tandem LED device with voltage limited and reverse polarity; through the selection of connecting pins, it is used on direct current power source or alternating current power source which is its characteristics.

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: A power supply with dimming control for a high-power DC LED lamp is provided. Particularly, a variable resistor is provided to a circuit of the high-power DC LED lamp for changing a current supplied to a light-emitting unit of the high-power DC LED lamp, thereby adjusting luminance (brightness) and power consumption (consumed watts) of the high-power DC LED unit of the high-power DC LED lamp. The variable resistor is provided to a driver, transformer, adaptor or power supply of the high-power DC LED lamp in a built-in manner or a remotely connected manner.

Abstract: Embodiments of the present invention generally provide an inductively coupled plasma (ICP) reactor having a substrate RF bias that is capable of control of the RF phase difference between the ICP source (a first RF source) and the substrate bias (a second RF source) for plasma processing reactors used in the semiconductor industry. Control of the RF phase difference provides a powerful knob for fine process tuning. For example, control of the RF phase difference may be used to control one or more of average etch rate, etch rate uniformity, etch rate skew, critical dimension (CD) uniformity, and CD skew, CD range, self DC bias control, and chamber matching.

Abstract: An electronic ballast includes an inverter circuit, a variable inductor unit and a control circuit. The variable inductor unit is electrically coupled between the inverter circuit and an illumination device. The control circuit controls the variable inductor unit according to an operation mode of the inverter circuit such that an equivalent inductance of the variable inductor unit has a variation fed back to the inverter circuit, to further change the operation mode of the inverter circuit. An illumination apparatus and a method for protecting the electronic ballast are also disclosed.

Abstract: A backlight unit, with a parallel configuration of plural lamps, having improved reliability is disclosed. The backlight unit driver includes: first and second lamps connected parallel to each other; a DC/AC inversion portion inverting a DC voltage into an AC voltage to apply the AC voltage to the lamps; a transformer transforming the AC voltage from the DC/AC inversion portion; a positive polarity AC signal compensator compensating an electric current difference between the first and second lamps using positive polarity AC signals from the first and second lamps; and a negative polarity AC signal compensator compensating the electric current difference between the first and second lamps using negative polarity AC signals from the first and second lamps.

Abstract: An LED lamp includes first and second LED strings connected in parallel to each other and a variable resistor interconnected therebetween. The variable resistor includes a resistance track with resistance coils wound thereon and a slider moveable along the resistance track. One portion of resistance of the variable resistor is connected in series with the first LED string, and the other portion of the resistance of the variable resistor is connected in series with the second LED string. When a position of the slider of the variable resistor is changed, a first electric current flowing through one of the first and second strings is increased, while a second electric current flowing through the other one of the first and second strings is decreased, such that the color temperature of the LED lamp is changed accordingly.

Abstract: A control circuit of an LED lamp includes a voltage regulator, at least a photo resistor and a feedback circuit. The voltage regulator includes an output terminal and a feedback terminal. The feedback circuit includes an amplifier having a first input end, a second input end and an output end. The LED lamp is connected between the first input end of the amplifier and the output terminal of the voltage regulator. The at least a photo resistor can sense a change of brightness level of an environment surrounding the LED lamp and a resistance of the at least a photo resistor increases along with a decrease of the brightness level. The change of resistance of the photo resistor is fed back to the voltage regulator via the amplifier, to thereby control an electric current flowing through the LED lamp.

Abstract: A circuit arrangement for operating a discharge lamp having a dielectric layer between at least one electrode and one discharge medium, comprising a primary circuit, which comprises a flux converter with at least one electronic switch, the flux converter having a first input terminal and a second input terminal for connecting an input voltage; a secondary circuit, which has a first output terminal and a second output terminal for connecting the discharge lamp; a transformer coupling the primary circuit to the secondary circuit, the transformer having at least a primary winding, a secondary winding and a transformer core, on which the primary winding and the secondary winding are wound; and a discrete inductance with a core, the discrete inductance being coupled electrically in parallel with the secondary winding.

Abstract: Embodiments of the present invention generally provide methods and apparatus for pulsed plasma processing over a wide process window. In some embodiments, an apparatus may include an RF power supply having frequency tuning and a matching network coupled to the RF power supply that share a common sensor for reading reflected RF power reflected back to the RF power supply. In some embodiments, an apparatus may include an RF power supply having frequency tuning and a matching network coupled to the RF power supply that share a common sensor for reading reflected RF power reflected back to the RF power supply and a common controller for tuning each of the RF power supply and the matching network.

Abstract: Provided is an LED driving circuit (4), including: an impedance detecting section (7) for detecting an impedance value of a phase-control type dimmer (2); and an impedance adjusting section (6) for adjusting an impedance of the LED driving circuit (4) based on the impedance value detected by the impedance detecting section (7).

Abstract: In a lamp driving circuit for operating a high intensity discharge lamp, an a commutation circuit comprises at least two switching devices. The switching devices are alternately switched active at a commutation frequency. The active switching device switches at a switching frequency. During an ignition mode, the switching frequency and the commutation frequency are substantially equal. A resulting commutation voltage is supplied to an inverter resonant circuit for generating a supply current. At a node of the inverter resonant circuit, a clamping circuit limits the generated voltage to a predetermined maximum voltage. The voltage at said node of the inverter resonant circuit is applied to an output resonant circuit. The output resonant circuit operates in the ignition mode as a resonator for generating a high ignition voltage; in a steady state operation mode, the output resonant circuit operates as a low-pass filter for reducing a high frequency current component in a lamp current.

Abstract: A novel LED driver circuit, including: a current regulation circuit, having a first end and a second end, wherein a first current is flowing into the second end, and a voltage difference between the first end and the second end is generated in response to the first current; a transistor, coupled with the first end and second end of the current regulation circuit; a bias network, having a first end and a second end, the second end being coupled with the transistor; and a LED module, having at least two connection nodes, wherein the connection node at one end of the LED module is coupled to a line voltage, the connection node at the other end of the LED module is coupled to the transistor, and one of the at least two connection nodes is coupled with the first end of the bias network.

Abstract: The proposed circuit makes it possible to operate a plurality of gas discharge lamps, particularly cold cathode tubes, across a common voltage source. The circuit reduces the resistance tolerance of the lamp characteristic curves through controlled debalancing of the lamp currents with the aid of debalancing modules. Through the active reduction in the resistance tolerance, the requirements placed on the electric strength of the balancing transistors as well as energy losses of the balancing circuit are reduced.

Abstract: The invention relates to an electronic device, comprising a DC-DC converter for converting a primary supply voltage into an output voltage at an output node to be coupled to a super capacitor and a control stage for operating the regulated DC-DC converter in a forward direction in a boost mode providing a boost voltage level at the output node and for operating the regulated DC-DC converter in a reverse direction in a buck mode providing a buck voltage level at an auxiliary node arranged between a primary voltage supply providing the primary supply voltage and the output node, wherein the control stage is adapted to control the DC-DC converter when operating in reverse direction to provide a current to the auxiliary node using the super capacitor as a power source.

Abstract: A method of driving a light source includes adjusting a number of duty adjustments of driving signals driving light sources based on a dimming control signal and adjusting each duty ratio of each of the driving signals provided to each of the light sources in accordance with the adjusted number of the duty adjustments.

Abstract: A DC/AC converter includes a resonant circuit having a first capacitor connected to at least one of a primary winding and a secondary winding of a transformer and an output end connected to a load, the resonant circuit receiving an alternating signal having a predetermined frequency and amplitude to pass a current, a variable impedance element connected in parallel with a part of the output end of the resonant circuit, the variable impedance element changing the impedance value thereof according to a current passing through the load, and a controller to control the current passing through the load to a predetermined value by changing the resonant frequency of the resonant circuit according to the changed impedance value of the variable impedance element.

Abstract: Provided is an electronic ballast including: a rectifier which rectifies alternating current (AC) power into direct current (DC) power; a power factor compensator which improves a power face of the DC power; an inverter which inverts the DC current into high frequency square wave power; and a resonant circuit which receives the high frequency square wave power from the inverter, adjusts impedance, transforms the high frequency square wave power into high frequency sine wave power, and outputs the high frequency sine wave power.

Abstract: A control element for a luminaire constituted of a first and a second manually variable non-momentary impedance and a first and a second time dependent gating circuit, each responsive to a respective manually variable non-momentary impedance and operative to provide a time dependent gating of a respective polarity of an alternating current power signal, the amount of time of the gating reflecting the present value of the respective manually variable non-momentary impedance, wherein the first time dependent gating circuit and the second time dependent gating circuit are restrained to maintain a minimum predetermined power towards the solid state lighting unit.

Abstract: A circuit arrangement for starting a discharge lamp, comprising: a first and a second input terminal for connecting an input voltage; an inverter, which has an input and an output, the input being coupled to the first and the second input terminal; a first and a second output terminal for connecting the discharge lamp; a resonant inductor, which is coupled between the output of the inverter and the first output terminal; a resonant circuit, which comprises the resonant inductor; a regulating apparatus for regulating the frequency of the signal provided at the inverter output; and a current measuring apparatus, which is arranged so as to measure a current which is correlated with the current in the resonant circuit, wherein the regulating apparatus is adapted to regulate the frequency at the output of the inverter as a function of the measured current.

Abstract: A first entity communicates with a second entity over a shared power bus by switching the bus to a high-impedance state and modifying the voltage on the power bus, in accordance with an outgoing communication, such that the modified voltage is detected by the second entity and the communication is received thereto.

Abstract: A semiconductor light source lighting circuit includes a transistor and a current detection resistor provided in series in a semiconductor light source current supply path, a control circuit for controlling the transistor so as to decrease any difference between the voltage occurring at the current detection resistor and a reference voltage, and a bypass resistor to establish a bypass path for the current supplied to the semiconductor light source, where a first end of the bypass path is located at a connection node between the transistor and the semiconductor light source.

Abstract: A current-limiting protection circuit of remotely controlled ceiling fan-lamp is disclosed. The current-limiting protection circuit includes a microcontroller unit for detecting rectangular wave signal reflective of the power used by a lamp load. The rectangular wave signal is compared with nominal value. In the case that the positive bandwidth of the rectangular wave signal is larger than the nominal value, it is indicated that the lamp load is in an overloaded state. Under such circumstance, the microcontroller unit controls a lamp load driving unit to change driving manner and lower the power used by the lamp load to a value within the nominal range.

Abstract: A circuit to control an AC lamp current provided by an input AC voltage supply to a cold-cathode fluorescent lamp (CCFL). The circuit includes a capacitor connected in series between the AC voltage supply and one terminal of the CCFL, the capacitor biasing the CCFL with the AC lamp current; a switch having first, second, and control terminals, the first terminal being connected to the CCFL and the second terminal being connected to the other side of the supply; a diode connected in parallel to the switch; and a resistor connected in parallel to the diode, wherein the AC lamp current is controlled by controlling the switch to add and remove resistance in series with the CCFL.

Abstract: The present invention relates to displays that use LED strings for backlighting. A lead string is provided with continuous drive voltage and the non-lead strings are provided with pulsed drive pulses. The string having the highest forward voltage is selected as the lead string. Feedback information indicative of the currents flowing through the non-lead strings is used to determine the duty cycles of the voltage pulses provided to drive the non-lead strings. The non-lead strings are controlled using pulsed drive voltages to minimize power dissipation in the circuit.

Abstract: Methods and corresponding systems for controlling a light fixture include a memory for storing data and software. A multi-tap capacitor has a plurality of tap capacitors integrated into a capacitor housing. A plurality of switches are each coupled to one of the plurality of tap capacitors for selectively coupling the tap capacitors together to produce a variable multi-tap capacitance. A processor is coupled to the memory and the switches to facilitate: detecting a trigger for changing a lumen level output by the light fixture; determining a new lumen level in response to the trigger; determining a capacitance value that corresponds to the new lumen level; and configuring the plurality of switches to produce the multi-tap capacitance that corresponds to the new lumen level. The processor can record data in the memory that represents times of lumen changes and switch settings, which data correlates to power consumption.

Abstract: A method of detecting a leak in an outer jacket of a metal halide lamp having an arc tube inside the outer jacket and operated by a ballast, where the ballast monitors an electrical characteristic of the lamp during start and detects a leak in the outer jacket when the electrical characteristic deviates from that of a corresponding metal halide lamp whose outer jacket does not have a leak. The electrical characteristic is one of six markers, namely (1) V?(E) at a predetermined E, where V?(E) is a derivative of lamp voltage V as a function of cumulative energy E delivered to the ballast since ignition, (2) a value of E at which V?(E) reaches a maximum, (3) V at a predetermined E, (4) a local maximum of V?(E) up to a predetermined E, (5) a global maximum of V?(E), and (6) E required to achieve a predetermined V.