Abstract: An LED driving circuit and an LED lamp are provided. The driving circuit comprises a power input unit coupled to an input voltage; a voltage conversion unit coupled to the power input unit and converting the input voltage into a conversion voltage; a power output unit coupled to the LED light source; a first thermistor unit connected between the power input unit and the voltage conversion unit; a second thermistor unit connected between the voltage conversion unit and the power output unit, where the second thermistor unit and the conversion voltage generates a driving current passing through the LED light source; where the resistance of the first thermistor unit is positively correlated to its sensed temperature, and the resistance of the second thermistor unit is positively correlated to its sensed temperature to stabilize the driving current.

Abstract: A dimming control circuit for an LED driver, can include: an adjusting circuit configured to generate an adjusting signal in accordance with a PWM dimming signal; and where a switching state of a power transistor of the LED driver is adjusted in accordance with the adjusting signal and a constant current control signal. A dimming control method for an LED driver, can include: determining a first threshold in accordance with a frequency of the PWM dimming signal and a frequency range of audio noise; generating an adjusting signal having a first duty cycle when a duty cycle of a PWM dimming signal is not greater than the first threshold; and controlling, by the adjusting signal, a switching state of a power transistor in the LED driver, where the first duty cycle is greater than the duty cycle of the PWM dimming signal.

Abstract: A display device and an operating method of the display device are provided. The display device includes a first light emitting diode (LED), a first switch, a second switch, a second LED, a third switch, and a first controller. A first terminal of the first switch receives a first electrical signal. A first terminal of the second switch receives a second electrical signal. A first terminal of the third switch receives a third electrical signal. Here, whether the first switch, the second switch, and the third switch are switched on or off is determined by whether the first LED and the second LED are damaged or not. The first controller is configured to detect whether the first LED and the second LED are damaged or not, generate the second electrical signal and the electrical signal, and generate a plurality of control signals controlling the first switch to the third switch.

Abstract: A display device and an operating method of the display device are provided. The display device includes a first light emitting diode (LED), a first switch, a second switch, a second LED, a third switch, and a first controller. A first terminal of the first switch receives a first electrical signal. A first terminal of the second switch receives a second electrical signal. A first terminal of the third switch receives a third electrical signal. Here, whether the first switch, the second switch, and the third switch are switched on or off is determined by whether the first LED and the second LED are damaged or not. The first controller is configured to detect whether the first LED and the second LED are damaged or not, generate the second electrical signal and the electrical signal, and generate a plurality of control signals controlling the first switch to the third switch.

Abstract: A ground fault detection circuit includes an input portion, and a ground fault determination unit. The input portion inputs an anode voltage of a series connection unit constituted of a plurality of light emission elements. When an anode voltage of the series connection unit input by the input portion is lower than or equal to a predetermined value less than a product of an on-resistance of the short-circuit switch disposed in parallel to each of the light emission elements and current supplied to the series connection unit, the ground fault determination unit determines that a ground fault has occurred without the short-circuit switch in a ground fault path.

Abstract: An LED tube lamp with overvoltage protection capability is provided. The LED tube lamp includes a lamp tube, two external connection terminals, a rectifying circuit, a filtering circuit, an LED module, and a protection circuit. The protection circuit is coupled between two input terminals of the LED module and configured to perform overvoltage protection when determining that a voltage level between the two input terminals of the LED module reaches or is higher than a predefined voltage value, wherein the protection circuit includes a diode and the predefined voltage value is in a range of about 40V to about 600V.

Abstract: A protective circuit for a current transformer for preventing a secondary voltage on a secondary circuit of the current transformer from exceeding a secondary voltage threshold. A protective circuit input can be coupled to the secondary circuit of the current transformer such that the secondary voltage is applied to the protective circuit input. A control unit is connected to the protective circuit input. A switch unit is connected to the protective circuit input and is operatively connected to the control unit. The control unit is adapted to provide a control signal to the switch unit in response to the secondary voltage exceeding the secondary voltage threshold. The switch unit is adapted to short-circuit the protective circuit input in response to the control signal provided by the control unit. The switch unit is implemented as a semiconductor circuit.

Abstract: A method and apparatus for nondestructive testing of a gas discharge tube (GDT) comprising: electrically connecting a first terminal of the GDT to a first port of a vector network analyzer (VNA); electrically connecting a second terminal of the GDT to a second port of the VNA; measuring S parameters with the VNA; determining GDT capacitance and insertion loss based on the measured S parameters; comparing the determined capacitance and insertion loss of the GDT with a threshold value to determine if the GDT is functional.

Abstract: A multi string controller with independent current setting for each string is designed for solid state lighting applications. This controller can regulate multiple channels of LEDs. Each string may have a different forward voltage and current setting. A constant buck regulator is also integrated inside this controller to regulate the total current, which is fed into the LED output channels. The circuit also contains a feedback loop in order to precisely control the current passing through each string and is immune to transient conditions.

Abstract: A light-emitting device, especially for lighting and/or signaling for a motor vehicle, includes at least a first electroluminescent module and a second electroluminescent module energized in series. Each electroluminescent module includes, in parallel: a first branch having a light source having a first direct threshold voltage beyond which the light source is gated on, and a second branch having an element such that the voltage on the terminals of the element is less than the first direct threshold voltage of the light source. A third branch has a timing module able to time a predetermined period and modify, at the end of the predetermined period, an overall impedance of the second branch so that a voltage in the second branch is greater than the first direct threshold voltage of the light source. The predetermined period in the first electroluminescent module is less than that of the second electroluminescent module.

Abstract: A driver circuit for light-emitting diode (LED) headlight system includes a buck-boost converter connected in series to a first plurality of branches of LEDs. Each of the plurality of branches of LEDs includes a bypass switch configured to bypass the corresponding branch of LEDs. The buck-boost converter provides a constant current with an adjustable voltage to a selectable portion of the plurality of branches of LEDs, while bypassing each of the other branches of LEDs via the corresponding bypass switches. In some examples, the circuit delivers the current to the selectable portion of the first plurality of branches of LEDs during a first portion of a duty cycle, while delivering a digitally modulated current to a second plurality of branches during a second portion of the duty cycle.

Abstract: When an LED lighting apparatus which is a lighter load than an incandescent lamp or halogen lamp is connected to a dimmer, a malfunction may occur. The invention prevents the occurrence of such malfunction without defeating the purpose of low power consumption of the LED lighting apparatus. More specifically, the LED lighting apparatus includes a rectifier circuit, a light-emitting circuit connected to the rectifier circuit and containing a single or a plurality of LEDs in which current begins to flow when an output voltage of the rectifier circuit exceeds a threshold voltage, and a bypass circuit having a bypass path for making the current flow to the rectifier circuit without passing through the light-emitting circuit, and a detecting unit for detecting the current flowing through the light-emitting circuit, and wherein when the current detected by the detecting unit exceeds a predetermined value, the bypass circuit shuts off the current flowing through the bypass path.

Abstract: The present invention relates to an apparatus for driving a light emitting diode. The apparatus for driving the light emitting diode according to the present invention comprises a rectifier circuit for accessing an Alternating Current (AC) voltage source to rectify an AC voltage of the AC voltage source, a light emitting diode array connected to an output side of the rectifier circuit and including a plurality of light emitting diode array blocks, and a charging/discharging circuit configured to be charged by a voltage output from the rectifier circuit, wherein the apparatus for driving the light emitting diode comprises a discharging switch, a block switch circuit, and a controller.

Abstract: An LED driving device includes a first converter configured to generate a first voltage, a second converter configured to generate a second voltage for driving a plurality of light emitting diodes (LEDs) from the first voltage, and a control circuit connected to an output terminal of the first converter and configured to control a level of the first voltage. The control circuit includes a cut-off circuit including a comparison circuit having hysteresis characteristics and a bleeder circuit.

Abstract: A light emitting diode (LED) string driving method applicable to drive a driving circuit is provided. The driving circuit comprises a plurality of LED strings, a power supply unit electrically coupled to the LED strings, a comparison unit configured to receive an input voltage, a control unit electrically coupled to the comparison unit, and a switch unit electrically coupled to the control unit, the power supply unit and the LED strings. The driving method comprises configuring the comparison unit to output a first control signal to the control unit through comparing the input voltage to the predetermined voltage, configuring the control unit to output a second control signal to the switch unit according to the first control signal, and configuring the switch unit to form various electrical loops and configuring the LED strings to corporately form either a parallel loop or a series loop via respective electrical loops.

Abstract: A lighting system and protection means are disclosed. In particular, a Zener diode with pre-selected characteristics is used in parallel with an LED such that current will continue to flow through the circuit in case of LED failure. This adaptation in turn may be used in a series string combination.

Abstract: A connector (10) is provided that includes a housing supporting a plurality of individual connection blocks (30, 35, 40) each having a power source input and an electronics output. Surge protection structure (51-54) is embedded within the housing of the connector (10) and is electrically coupled to at least some of the individual connection blocks (30, 35, 40). The connector (10) may be implemented within a lighting fixture (100).

Abstract: A panel for a display device includes a display unit, an electrostatic protection wire, a wire being connected to the display pixels, an electrostatic protection circuit, and an electrostatic protection circuit control line. The display unit includes a plurality of display pixels. The electrostatic protection wire is connected to a test pad, the test pad being provided to receive a test signal. The electrostatic protection circuit connects the electrostatic protection wire and the wire connected to the display pixels. The electrostatic protection circuit includes a back-gate-type transistor that has a gate electrode, a drain electrode being short-circuited with the gate electrode, and a back-gate electrode. The electrostatic protection circuit control line includes a first end and a second end, the first end being connected to the back-gate electrode of the back-gate-type transistor.

Abstract: The present invention provides an LED backlight system and display device. Backlight system includes power source module, LED array, master switch module, current detection module, current equalizer module and current shunt module. LED array is connected to power source module and includes LED strings with common anode. Master switch module includes first switch transistors for receiving switch control PWM signal of LED strings. Current detection module outputs current feedback signals corresponding to currents of LED strings. Current equalizer module is connected to current detection and includes equalizer control unit and equalizer switch unit. Based on current feedback signal, equalizer control unit controls on-and-off of equalizer switch unit. Current shunt module is connected in parallel with current equalizer module and performs current shunt on current equalizer module. As such, the present invention reduces energy-consumption of current equalizer module and temperature of LED drive chip.

Abstract: An LED lighting device includes a DC/DC power converter having output terminals coupled to respective lamp sockets. A controller receives signals from a current sensor and a voltage sensor, and controls the DC/DC power converter to increase/decrease an output voltage based on a sensed output current with respect to a target value. A sensed output voltage is compared to predetermined upper and lower limit values, and the DC/DC power converter is disabled when the output voltage exceeds the predetermined upper limit value or falls below the predetermined lower limit. The controller further measures an accumulated lighting time of the device, and after the accumulated lighting time has exceeded a predetermined switching time, decreases the upper limit value monotonously or in increments as the accumulated lighting time passes.

Abstract: A driver circuit for driving an LED includes a rectifier circuit to receive AC voltage and to convert the AC voltage to DC voltage. The driver circuit further includes a filter circuit for filtering the DC voltage. The driver circuit further includes a detection circuit for determining a change in the filtered DC voltage over a predetermined time interval. The driver circuit further includes a dampening circuit for dampening the filtered DC voltage responsive to the detection circuit determining that the change in filtered DC voltage over the predetermined time interval exceeds a predetermined threshold.

Abstract: A display apparatus is provided which optimally restores decreased luminance and extends a life of a light emitting element. The display apparatus includes a memory that stores a plurality of trap levels in association with a plurality of use durations of the light emitting element. An obtainer determines one of the plurality of use durations of the light emitting element. A controller reads, from the memory, one of the plurality of trap levels associated with the one of the plurality of use durations, and removes a charge from the light emitting element by application of a reverse bias voltage having a level associated with the one of the plurality of trap levels. The controller changes the level of the reverse bias voltage which is applied to the light emitting element so that as the one of the plurality of use durations increases, the level of the reverse bias voltage increases.

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 LED drive circuit is an LED dive circuit that receives an alternating voltage to drive an LED, and includes a current remove portion that removes a current from a current supply line that supplies an LED drive current to the LED. If an input current to the LED drive circuit is an unnecessary current, the LED does not light because of current removal by the current remove portion. If the input current to the LED drive circuit turns into the LED drive current from the unnecessary current, the current remove portion decreases the amount of current removed.

Abstract: A lighting apparatus includes a first substrate including a switching circuit, the switching circuit including a first port, a second port and a current control circuit configured to generate a current at the second port of the current control circuit responsive to a varying voltage at the first port. The apparatus further includes a second substrate mounted on the first substrate and including at least two LEDs electrically coupled to the second port of the current control circuit of the first substrate.

Abstract: A connector (10) is provided that includes a housing supporting a plurality of individual connection blocks (30, 35, 40) each having a power source input and an electronics output. Surge protection structure (51-54) is embedded within the housing of the connector (10) and is electrically coupled to at least some of the individual connection blocks (30, 35, 40). The connector (10) may be implemented within a lighting fixture (100).

Abstract: A fluorescent lighting device includes a ballast and a tube. An amalgam is located within the tube. A resistive heater is operatively coupled with the ballast, to receive electrical power from the ballast while the fluorescent lighting device is in an OFF state. The resistive heater is mounted near the amalgam to transfer heat to the amalgam while the fluorescent lighting device is in the OFF state.

Abstract: Circuits useful in achieving efficient current control of LEDs based on a dimming control input are described. The circuits use a combination of PWM dimming and analog dimming to achieve a highly efficient LED driver over a wide range of dimming from near 0% to 100% light output.

Abstract: An LED module for use in sign letter channel lights comprises a substrate, a reflector mounted on the substrate, an LED mounted within the reflector on the substrate and a Zener diode shunt element connected in parallel across the LED, a printed circuit board on the substrate, wherein the LED is mounted on the printed circuit board, and an insulating cover. The module may be entirely encapsulated. An LED driving protection circuit provides ground fault protection for a plurality of series connected LED modules.

Abstract: A driver circuit for driving an LED includes a rectifier circuit to receive AC voltage and to convert the AC voltage to DC voltage. The driver circuit further includes a filter circuit for filtering the DC voltage. The driver circuit further includes a detection circuit for determining a change in the filtered DC voltage over a predetermined time interval. The driver circuit further includes a dampening circuit for dampening the filtered DC voltage responsive to the detection circuit determining that the change in filtered DC voltage over the predetermined time interval exceeds a predetermined threshold.

Abstract: A processing system may include a plasma source for providing a plasma and a workpiece holder arranged to receive ions from the plasma. The processing system may further include a pulsed bias circuit electrically coupled to the plasma source and operable to switch a bias voltage supplied to the plasma source between a high voltage state in which the plasma source is biased positively with respect to ground and a low voltage state in which the plasma source is biased negatively with respect to the ground.

Abstract: An apparatus is disclosed for supplying power to a luminous load. The apparatus includes a transformer having a primary winding, and a control circuit adapted to generate an alternating current through the primary winding to develop an alternating voltage. The alternating current is based on a first signal derived from the input voltage, a second signal derived from the current, and a third signal varying substantially in-phase with the input voltage. The first and second signals are used to regulate the power delivered to the load, and the third signal is used to improve the power factor. A load interface circuit is provided to generate an output voltage for the luminous load based on the alternating voltage from the transformer. An over-temperature sensor may be provided to cause a reduction in power to the load when the ambient temperature exceeds a threshold.

Abstract: An illumination circuit includes a series circuit including light sources connected in series between a high voltage node and a low voltage node, and break-protecting circuits. Each break-protecting circuit includes a control circuit and a bypass circuit. The bypass circuit is connected in parallel to at least one corresponding light source of the light sources.

Abstract: A lighting system and protection means are disclosed. In particular, a Zener diode with pre-selected characteristics is used in parallel with an LED such that current will continue to flow through the circuit in case of LED failure. This adaptation in turn may be used in a series string combination.

Abstract: An electronic circuit for use with a lamp controller includes a driver component and a voltage interface circuit powered by the driver component. The interface component delivers a low voltage power signal at a defined operating range via output lines to a downstream controller. A protection circuit is coupled with the voltage interface circuit. The protection circuit in one embodiment has an under-voltage switch disposed in one of the output lines and configured to open at a voltage less than the defined voltage range, and a blocking device disposed in the other output line and configured to block reverse power flow at a voltage above the defined voltage range.

Abstract: An LED driving circuit with open-circuit protection is disclosed. The LED driving circuit pulls down an operation voltage supplied to a converting controller of the LED driving circuit when a voltage across an LED module of the LED driving circuit is too high, so as to stop the converting controller operating and further latch the converting controller at the protection state until that the converting controller is restarted or the condition of the voltage supplied to the LED module being too high is solved.

Abstract: Semiconductor light emitting circuits include semiconductor light emitting diodes that are serially connected between a pair of input terminals. Four layer semiconductor devices, such as Shockley diodes and/or thyristors are also provided, a respective one of which is connected across a respective one of the semiconductor light emitting diodes. The four layer semiconductor devices can allow a string of light emitting diodes to continue to be lit if one light emitting diode fails.

Abstract: A bypass protection circuit connected to a light emitting diode (LED) group in parallel, comprises a switch circuit and a capacitor. The switch circuit comprises a plurality of switch components, an abnormal detection module and a switch control module. The abnormal detection module detects voltage of the LEDs respectively, and determines which one is broken and outputs an abnormal signal. The switch control module controls a switch component connected to the broken LED in parallel on/off according to the abnormal signal. The capacitor is charged by driving signals of the LEDs when the LEDs are operated according to a normal working mode or a first status of a burst dimming mode, and is discharged to maintain an operating power of the switch circuit when the LEDs are operated according to a second status of the burst dimming mode.

Abstract: Solid state light source driving and dimming systems are provided that enable a plurality of solid state light source (e.g., LED) driver circuits to be coupled to a single AC voltage source. The driver circuits may include constant current circuitry configured to generate a constant AC current from the AC voltage source, and rectifier circuitry configured to generate a DC current to drive the solid state light source (e.g., LEDs). Dimming control includes shunt circuitry operable with a PWM switch to shunt the AC voltage source during certain portions of a PWM signal and to decouple the shunt circuitry from the AC voltage source during other portions of the PWM signal. Shunting the AC voltage source causes the interruption of the DC current to effectively turn off the LEDs. Decoupling the shunt circuitry may improve overall efficiency of power transfer to the LEDs.

Abstract: An LED drive circuit is an LED dive circuit that receives an alternating voltage to drive an LED, and includes a current remove portion that removes a current from a current supply line that supplies an LED drive current to the LED. If an input current to the LED drive circuit is an unnecessary current, the LED does not light because of current removal by the current remove portion. If the input current to the LED drive circuit turns into the LED drive current from the unnecessary current, the current remove portion decreases the amount of current removed.

Abstract: In a circuit that turns off a fluorescent lamp, clamping circuitry is provided to dissipate energy stored in a ballast when the lamp is being turned off. In a normal state in which the lamp is on, or in a normal state in which the lamp is off, clamping is not performed as long the VDS of a power switch is below a voltage A. In a lamp turn off operation, the switch is turned on for a time period to extinguish the lamp, and is then made to operate as a clamp (operate in its linear region) for a second period of time to dissipate energy that was stored in the ballast. Clamping in the linear region continues for VDS voltages down to B as ballast energy is dissipated, where B is smaller than A. By clamping down to the lower voltage B, re-ignition of the lamp is prevented.

Abstract: Circuits useful in achieving efficient current control of LEDs based on a dimming control input are described. The circuits use a combination of PWM dimming and analog dimming to achieve a highly efficient LED driver over a wide range of dimming from near 0% to 100% light output.

Abstract: An LED lighting device includes a DC/DC power converter having output terminals coupled to respective lamp sockets. A controller receives signals from a current sensor and a voltage sensor, and controls the DC/DC power converter to increase/decrease an output voltage based on a sensed output current with respect to a target value. A sensed output voltage is compared to predetermined upper and lower limit values, and the DC/DC power converter is disabled when the output voltage exceeds the predetermined upper limit value or falls below the predetermined lower limit. The controller further measures an accumulated lighting time of the device, and after the accumulated lighting time has exceeded a predetermined switching time, decreases the upper limit value monotonously or in increments as the accumulated lighting time passes.

Abstract: Light Emitting Diodes (LEDs) are increasingly used in illumination applications. To control multiple Light Emitting Diodes (LEDs), or any other controllable light source, this document introduces a single-wire multiple-LED power and control system. Specifically, individually controlled LED units are arranged in a series configuration that is driven by a control unit located at the head of the series. Each of the individually controlled LED units may comprise more than one LED that is also individually controllable. The head-end control unit provides both electrical power and control signals down a single wire to drive all of the LED units in the series in a manner that allows each LED unit to be controlled individually or in assigned groups.

Abstract: A current limiting circuit includes a power input terminal that is connected to an output terminal of a direct current power source to which an output capacitor is connected in parallel; a power output terminal to which an LED is connected; and a current limiting unit that supplies to the LED a load current to which an upper current value is set, supplies to the LED a load current lower than the upper current value at a normal condition, and supplies to the LED a load current higher than the load current of the normal condition and equal to or lower than the upper current value at an abnormal condition.

Abstract: A light-emitting diode (LED) protection structure includes an LED portion and a protection portion. The protection portion includes a fuse and a Zener diode connected in series. The protection portion is electrically connected to the LED portion in parallel but opposite in direction. As such, the LED protection structure can effectively protect the LEDs and the Zener diode from being damaged to thereby reduce costs.

Abstract: A safety circuit is provided for a ballast of an electro-luminescent (EL) lamp. The EL lamp had an electrical ground shield on at least a portion thereof and has a separate ground lead. The ballast is an isolated ballast with a line input being isolated from an output. The ballast is constructed and arranged to be electrically connected with the separate ground lead. The circuit includes a current sensing structure constructed and arranged to connect between the separate ground lead and a potential ground of the ballast. In the event a user contacts the EL lamp to replace the EL lamp or contacts a defective EL lamp, the ballast is shut down based on a value of current sensed by the current sensing structure.

Abstract: The present invention relates to a light emitting diode with enhanced luminance and light emitting performance due to increase in efficiency of current diffusion into an ITO layer, and a method of fabricating the light emitting diode. According to the present invention, there is manufactured at least one light emitting cell including an N-type semiconductor layer, an active layer and a P-type semiconductor layer on a substrate. The method of the present invention comprises the steps of (a) forming at least one light emitting cell with an ITO layer formed on a top surface of the P-type semiconductor layer; (b) forming a contact groove for wiring connection in the ITO layer through dry etching; and (c) filling the contact groove with a contact connection portion made of a conductive material for the wiring connection.

Abstract: A current limiting recessed lighting fixture prevents operation with lamps exceeding a rated wattage. Laws coming into effect place limits on lamp power consumption. The laws require that light fixtures include features to prevent a compliant lamp being later replaced by a higher wattage lamp. Further, limits have been placed on air flow from recessed lighting fixtures into ceiling plenums resulting in retention of heat in fixtures. Most high efficiency lamps include heat producing circuits in the lamp base and recessed lighting fixtures suitable of a lower wattage high efficiency lamp may overheat if a higher wattage replacement lamp is installed. Such overheating may drastically shorten the life if expensive LED lamps. The current limiting recessed lighting fixture shuts off when a lamp is installed which draws current above the rating for the fixture thereby addressing both the requirements of the new laws and also the potential overheating.

Abstract: A bypass protection circuit connected to a light emitting diode (LED) group in parallel, comprises a switch circuit and a capacitor. The switch circuit comprises a plurality of switch components, an abnormal detection module and a switch control module. The abnormal detection module detects voltage of the LEDs respectively, and determines which one is broken and outputs an abnormal signal. The switch control module controls a switch component connected to the broken LED in parallel on/off according to the abnormal signal. The capacitor is charged by driving signals of the LEDs when the LEDs are operated according to a normal working mode or a first status of a burst dimming mode, and is discharged to maintain an operating power of the switch circuit when the LEDs are operated according to a second status of the burst dimming mode.