Patent application number | Description | Published |
20080246413 | DC/AC COLD CATHODE FLUORESCENT LAMP INVERTER - A DC/AC cold cathode fluorescent lamp (CCFL) inverter circuit includes a transformer with a primary winding and a secondary winding for providing increased voltage to a CCFL, a first and second MOSFET switches for selectively allowing direct current of a first polarity and a second polarity to flow through the transformer respectively. The primary and secondary windings of the transformer are electrically coupled to ground. A capacitor divider is electrically coupled to the CCFL for providing a first voltage signal representing a voltage across the CCFL. A first feedback signal line receives the first voltage signal. A timer circuit is coupled to the first feedback signal line for providing a time-out sequence of a predetermined duration when the first voltage signal exceeds a predetermined threshold. A protection circuit shuts down the first switch and the second switch when the first voltage signal exceeds the predetermined threshold after the predetermined duration. | 10-09-2008 |
20090039796 | POWER SUPPLY FOR AN LCD DISPLAY - A power supply system is provided for a multiple lamp LCD panel. In one aspect, the power supply includes a plurality of transformers for driving a plurality of respective CCFLs. The primary sides of each transformer are coupled in series to thereby reduce the stress on each transformer. For LCD panels that include longer CCFLs, a power supply is provided that includes a plurality of transformers for driving a plurality of respective CCFLs. The primary sides of each transformer are coupled in series and each lamp is coupled to two secondary sides of the transformers, thereby reducing the problems associated with longer CCFL tubes. In any of the embodiments, the power supply can be adapted to convert a high voltage DC signal to high voltage AC used to power the lamps. | 02-12-2009 |
20090218954 | Sequential burst mode actlvation circuit - A sequential burst mode regulation system to deliver power to a plurality of loads. In the exemplary embodiments, the system of the present invention generates a plurality of phased pulse width modulated signals from a single pulse width modulated signal, where each of the phased signals regulates power to a respective load. Exemplary circuitry includes a PWM signal generator, and a phase delay array that receives a PWM signal and generates a plurality of phased PWM signals which are used to regulate power to respective loads. A frequency selector circuit can be provided that sets the frequency of the PWM signal using a fixed or variable frequency reference signal. | 09-03-2009 |
20090273285 | PROTECTION FOR EXTERNAL ELECTRODE FLUORESCENT LAMP SYSTEM - The present invention provides a protection means for a driving circuit which drives a set of external electrode fluorescent lamps (EEFL). The driving circuit with protection function for driving a set of EEFLs consistent with the present invention includes: a transformer connected to the set of EEFLs; a switching network connected to the transformer which delivers power to the transformer; a sensing circuit connected to the set of EEFLs which detects disconnection if one light source is disconnected; and a controller connected to the switching network which controls the switching network to reduce the total current supplied to the EEFLs which remain connected, if the sensing circuit detects that one EEFL is disconnected. Appropriate protection can therefore be implemented when the EEFL is disconnected on one end or both ends. | 11-05-2009 |
20100026213 | INTEGRATED CIRCUIT CAPABLE OF SYNCHRONIZATION SIGNAL DETECTION - A method according to one embodiment may include providing power to at least one light source. The method of this embodiment may also include detecting the frequency of at least one vertical synchronization signal, among a plurality of different synchronization signals, and controlling the power to at least one light source based on, at least in part, the detected frequency of at least one vertical synchronization signal. Of course, many alternatives, variations, and modifications are possible without departing from this embodiment. | 02-04-2010 |
20100033109 | Driving circuit for powering light sources - There is provided a driving circuit for powering a plurality of light sources. The driving circuit includes a power converter, a plurality of switching regulators and a plurality of switching balance controllers. The power converter is operable for receiving an input voltage and for providing a regulated voltage to the light sources. The switching regulators are operable for adjusting forward voltages of the light sources respectively. The switching balance controllers are operable for generating pulse modulation signals to control the switching regulators respectively. | 02-11-2010 |
20100148681 | DRIVING CIRCUIT WITH CONTINUOUS DIMMING FUNCTION FOR DRIVING LIGHT SOURCES - A driving circuit for controlling power of a light source includes a power converter coupled to a power source and the light source, and a dimming controller coupled to the power converter. The power converter can receive power from the power source and provide a regulated power to the light source. The power converter includes a control switch coupled in series with the light source. The dimming controller can monitor a power switch coupled between the power source and the driving circuit, and receive a dimming request signal and a dimming termination signal. The dimming request signal can indicate a first set of operations of the power switch. The dimming termination signal can indicate a second set of operations of the power switch. The dimming controller can continuously adjust the regulated power from the power converter by controlling the control switch if the dimming request signal is received, and can stop adjusting the regulated power from the power converter if the dimming termination signal is received. | 06-17-2010 |
20100148691 | Driving circuit with dimming controller for driving light sources - There is provided a driving circuit for controlling power of a light source. The driving circuit includes a power converter and a dimming controller. The power converter is coupled between a power source and the light source, and can receive power from the power source and provide a regulated power to the light source. The dimming controller is coupled to the power converter, and can receive a switch monitoring signal. The switch monitoring signal can indicate an operation of a power switch coupled between the power source and the driving circuit. The dimming controller is further operable for adjusting the regulated power from the power converter by controlling a switch coupled in series with the light source according to the switch monitoring signal. | 06-17-2010 |
20100219766 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - A dimming controller for controlling power of a light source has a monitoring terminal, a dimming terminal, and a control terminal. The monitoring terminal is operable for receiving a current monitoring signal indicating a current flowing through the light source. The dimming terminal is operable for receiving a ramp signal. The voltage of the ramp signal increases if a power switch coupled between a power source and the light source is turned on. The control terminal is operable for providing a control signal to control a control switch coupled in series with the light source based on the current monitoring signal and the ramp signal. An average current of the light source increases as the ramp signal increases until the average current reaches a predetermined level. | 09-02-2010 |
20100237784 | PORTABLE LIGHTING DEVICE AND METHOD THEREOF - A portable lighting device includes a power source, a controller, and a load. The controller comprises a power input terminal which is electrically connected to the power source via a switch. The load is electrically connected to a power output terminal of the controller and is capable of providing a feedback signal. The controller regulates the power being provided to the load according to the feedback signal and a conduction status of the switch. | 09-23-2010 |
20110062869 | CIRCUIT FOR VEHICLE LIGHTING - A circuit for driving a vehicle lamp includes a current path coupled between a power line and ground, and a monitoring unit coupled to the power line. The current path includes a dummy load. The monitoring unit can monitor a testing signal applied to the power line. The testing signal can test whether the vehicle lamp operates properly. The monitoring unit can conduct the current path to enable a current to flow through the dummy load to ground to decrease a total resistance of the circuit if the testing signal is detected. | 03-17-2011 |
20110062882 | SYSTEMS AND METHODS FOR DRIVING A LIGHT SOURCE - A circuit for driving a light source includes a voltage converter, a switch and a controller. The voltage converter converts an AC input voltage signal to a first rectified AC voltage signal. The voltage converter further generates an average signal proportional to an average voltage level of the first rectified AC voltage signal. The switch is coupled to the light source in series. The controller coupled to the voltage converter and the switch compares the first rectified AC voltage signal with the average signal to generate a pulse signal. The controller further generates a dimming control signal based on the pulse signal to control the switch thereby controlling dimming of the light source. | 03-17-2011 |
20110074839 | CONTROLLER CIRCUITRY FOR LIGHT EMITTING DIODES - A method according to one embodiment may include supplying power to an LED array having at least a first string of LEDs and a second string of LEDs coupled in parallel, each of the strings includes at least two LEDs. The method of this embodiment may also include comparing a first feedback signal from the first string of LEDs and a second feedback signal from the second string of LEDs. The first feedback signal is proportional to current in said first string of LEDs and said second feedback signal is proportional to current in said second string of LEDs. The method of this embodiment may also include controlling a voltage drop of at least the first string of LEDs to adjust the current of the first string of LEDs relative to the second string of LEDs, based on, at least in part, the comparing of the first and second feedback signals. Of course, many alternatives, variations, and modifications are possible without departing from this embodiment. | 03-31-2011 |
20110109245 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - In one embodiment, a driving circuit includes an AC/DC converter which converts an AC voltage to a DC voltage and a DC/DC linear regulator which regulates a current through, e.g., an LED light source, according to a first current reference if a monitoring signal indicating the DC voltage is within a predetermined range, and regulates the current according to a second current reference less than the first current reference if the monitoring signal is beyond the predetermined range. In another embodiment, a controller controlling power to an LED light source turns on a first plurality of LEDs and turns off a second plurality of LEDs if a monitoring signal indicative of a DC voltage received by the LED light source is within a predetermined range, and turns on both first and second plurality of LEDs if the monitoring signal is beyond the predetermined range. | 05-12-2011 |
20110140619 | DIFFERENTIAL DRIVING CIRCUIT FOR POWERING A LIGHT SOURCE - A differential driving circuit for powering a light source is disclosed. The differential driving circuit includes a first set of switches and a second set of switches. A first current from a power source flows through the first set of switches to charge a first energy storage element when the first set of switches are turned on. A second current from the first energy storage element flows through the second set of switches to power the light source when the second set of switches are turned on. The differential driving circuit further includes a second energy storage element coupled to the light source in parallel and for providing a differential voltage to the light source. | 06-16-2011 |
20110140620 | CIRCUITS AND METHODS FOR CONTROLLING DIMMING OF A LIGHT SOURCE - A controller for controlling dimming of a light source includes a detection pin, an input signal pin, and a monitoring pin. The detection pin is operable for monitoring a rectified voltage and for detecting whether the rectified voltage comes from a TRIAC dimmer or an on/off switch dimmer. The input signal pin is operable for receiving an input signal indicative of the rectified voltage and the controller controls dimming of the light source according to the input signal if the rectified voltage comes from a TRIAC dimmer. The monitoring pin is operable for receiving a monitoring signal indicating an operation of the on/off switch dimmer and the controller controls dimming of the light source according to the monitoring signal if the rectified voltage comes from an on/off switch dimmer. | 06-16-2011 |
20110181199 | CONTROLLERS, SYSTEMS AND METHODS FOR CONTROLLING DIMMING OF LIGHT SOURCES - A controller for controlling dimming of an LED light source includes a control terminal and dimming control circuitry coupled to the control terminal. The control terminal provides a driving signal to control a control switch coupled to the LED light source, thereby controlling the dimming of the LED light source. The dimming control circuitry generates the driving signal according to a set of operations of a power switch that transfers an AC signal. The dimming control circuitry further adjusts the driving signal by counting multiple waves of the AC signal to control the dimming of the LED light source. | 07-28-2011 |
20110221346 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - Embodiments in accordance with the present invention provide circuits and methods for driving light sources, e.g., a light-emitting diode (LED) light source. In one embodiment, a printed circuit board (PCB) includes a bridge rectifier rectifying an AC voltage to a rectified AC voltage, an LED light source, and a first switch coupled to the LED light source in series controlling a current through the LED light source according to a predetermined current reference. The LED light source and the first switch coupled in series receive the rectified AC voltage while the first switch is controlled linearly. | 09-15-2011 |
20110221795 | BACKLIGHT CONTROLLER FOR DRIVING LIGHT SOURCES - A backlight controller for driving multiple light emitting diode (LED) strings includes feedback circuitry, phase array circuitry, and encoder circuitry. The feedback circuitry generates multiple feedback signals indicative of currents flowing through the LED strings respectively. The encoder circuitry generates a code signal indicative of a total number of operative LED strings among the multiple LED strings based on the feedback signals. The phase array circuitry generates multiple saw tooth signals according to the code signal. A phase shift amount between two adjacent signals of the saw tooth signals is determined by the total number of the operative LED strings. The phase array circuitry compares each of the saw tooth signals with a dimming control signal to generate multiple phase shift signals so as to respectively control the operative LED strings. | 09-15-2011 |
20110227496 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - A controller for controlling dimming of a light-emitting diode (LED) light source provides a pulse signal by comparing a sensing signal indicative of a current flowing through the LED light source to a reference signal. The controller controls the current through the LED light source according to the pulse signal during a first state of a pulse-width modulation signal and cutting off the current through the LED light source during a second state of the pulse-width modulation signal. The controller receives a dimming request signal indicative of an operation of a power switch coupled between an AC power source and a bridge rectifier and adjusts both a level of the reference signal and a duty cycle of the pulse-width modulation signal based on the dimming request signal. | 09-22-2011 |
20110285323 | DRIVING CIRCUIT WITH DIMMING CONTROLLER FOR DRIVING LIGHT SOURCES - A dimming controller for controlling dimming of a light-emitting diode (LED) light source includes a monitoring terminal and a control terminal. The monitoring terminal receives a switch monitoring signal indicative of an operation of a power switch which transfers power from an AC power source to a bridge rectifier when the power switch is on. A power converter receives input power from the bridge rectifier and provides output power to the LED light source. The control terminal generates a control signal to adjust the output power according to the switch monitoring signal so as to control dimming of the LED light source. | 11-24-2011 |
20120032613 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - A driving circuit for powering a light-emitting diode (LED) light source includes a converter circuit, an energy storage element and a switch element. The converter circuit provides a first output voltage on a first power line to provide power to the LED light source and provides a second output voltage on a second power line that is less than the first output voltage. The energy storage element is charged and discharged to regulate a current through the LED light source. The switch element operates in a first state during which the energy storage element is charged and operates in a second state during which the energy storage element is discharged. The converter circuit provides the second output voltage to maintain an operating voltage across the switch element less than the first output voltage during both the first state and the second state. | 02-09-2012 |
20120038292 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - A driving circuit for driving a light source includes a converter and a dimming controller. The converter coupled to a power source is operable for receiving power from the power source and for providing regulated power to the light source according to control signals. The dimming controller coupled to the converter is operable for monitoring a power switch coupled between the power source and the converter, for receiving a color change signal indicating a first set of operations of the power switch and a dimming request signal indicating a second set of operations of the power switch, for controlling the control signals to change the color of the light source in response to the color change signal, and for controlling the control signals to adjust the brightness of the light source in response to the dimming request signal. | 02-16-2012 |
20120112650 | DRIVING CIRCUIT WITH DIMMING CONTROLLER FOR DRIVING LIGHT SOURCES - A controller for controlling dimming of a light-emitting diode (LED) light source includes a switch monitoring pin, a current monitoring pin, and a control pin. The switch monitoring pin monitors an operation of a power switch which transfers an AC voltage to a rectifier when the power switch is on. The current monitoring pin receives a current monitoring signal indicating a current flowing through the LED light source. The control pin generates a control signal to control a second switch coupled in series with the LED light source to adjust the brightness of the LED light source according to the operation of the power switch. | 05-10-2012 |
20120126710 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - Embodiments in accordance with the present invention provide circuits and methods for driving light sources, e.g., a light-emitting diode (LED) light source. In one embodiment, a lamp includes a rectifier rectifying an AC voltage to a rectified AC voltage, an LED light source, and a switch coupled to the LED light source in series controlling a current through the LED light source according to a predetermined current reference. The LED light source and the switch coupled in series receive the rectified AC voltage while the switch is controlled linearly. | 05-24-2012 |
20120169243 | CIRCUITS AND METHODS FOR CONTROLLING DIMMING OF A LIGHT SOURCE - A controller that monitors a rectified voltage and detects whether the rectified voltage comes from a TRIAC dimmer or an on/off switch dimmer is disclosed. The controller controls dimming of a light source according to the rectified voltage if the rectified voltage comes from the TRIAC dimmer. The controller controls dimming of the light source according to an operation of the on/off switch dimmer if the rectified voltage comes from the on/off switch dimmer. | 07-05-2012 |
20120176066 | PORTABLE LIGHTING DEVICE AND METHOD THEREOF - A portable lighting device includes a controller, a power source that provides a voltage, and a load that includes a light emitting diode (LED) light source. The controller receives the voltage and regulates a current of the LED light source based on a sensing signal indicating the voltage of the power source. The controller regulates the current of the LED light source to a first current level if the voltage of the power source is greater than a first voltage level, and to a second current level if the voltage of the power source is less than a second voltage level. The second voltage level is less than the first voltage level. The controller regulates the current of the LED light source to vary according to the sensing signal if the voltage of the power source is between the first voltage level and the second voltage level. | 07-12-2012 |
20120217878 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - In one embodiment, a driving circuit includes an AC/DC converter which converts an AC voltage to a DC voltage and a DC/DC linear regulator which regulates a current through, e.g., an LED light source, according to a first current reference if a monitoring signal indicating the DC voltage is within a predetermined range, and regulates the current according to a second current reference less than the first current reference if the monitoring signal is beyond the predetermined range. In another embodiment, a controller controlling power to an LED light source turns on a first plurality of LEDs and turns off a second plurality of LEDs if a monitoring signal indicative of a DC voltage received by the LED light source is within a predetermined range, and turns on both first and second plurality of LEDs if the monitoring signal is beyond the predetermined range. | 08-30-2012 |
20120262079 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - A circuit for powering a light source includes a filter, a transformer, and a controller. The filter receives an input voltage and filters the input voltage to provide a regulated voltage. The transformer converts the regulated voltage to an output voltage to power the light source. The controller generates a driving signal to alternately operate the switch between a first state and a second state. The controller corrects a power factor of the circuit by controlling time durations of the first state and the second state, such that an input current decreases to a predetermined level during the second state and increases from the predetermined level to a peak level proportional to the input voltage during the first state. The controller controls the ratio of time in the first state to time in the second state to adjust an output current flowing through the light source to a target level. | 10-18-2012 |
20120268023 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - A driving circuit for driving a light-emitting diode (LED) light source includes a buck-boost converter and a controller. The buck-boost converter receives an input voltage and an input current and powers the LED light source, and comprises a switch controlled by a driving signal. The controller receives a first signal indicating a current through the LED light source, and generates the driving signal based on the first signal to control the switch and to adjust the current through the LED light source. The buck-boost converter further comprises a current sensor which provides a second signal indicating an instant current flowing through the buck-boost converter, wherein the first signal is derived from the second signal, and wherein a reference ground of the controller is different from a ground of the driving circuit. | 10-25-2012 |
20130069546 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - A controller controls power to a light source. The light source receives a rectified AC voltage and includes a first plurality of LEDs and a second plurality of LEDs. The controller regulates a current flowing through the first plurality of LEDs to a first predetermined level when the rectified AC voltage is within a first predetermined range. The second plurality of LEDs remain off when the rectified AC voltage is within the first predetermined range. | 03-21-2013 |
20130193877 | CIRCUITS AND METHODS FOR DRIVING LIGHT SOURCES - A dimming controller can operate in a first mode or a second mode to control dimming of a light-emitting diode (LED) light source. The dimming controller can include a voltage control terminal and a current control terminal. The voltage control terminal provides a pulse signal when the dimming controller operates in the first mode to operate a control switch in either a first state or a second state. A first current flowing through the LED light source increases when the control switch is in the first state and decreases when the control switch is in the second state. The voltage control terminal provides a control signal to the control switch to cut off the first current when the dimming controller operates in the second mode. The current control terminal conducts a second current through the LED light source when the dimming controller operates in the second mode. | 08-01-2013 |
20140152187 | CIRCUITS AND METHODS FOR DRIVING A LIGHT SOURCE - A circuit includes a bridge circuit, a converter, and a controller. The bridge circuit receives power from first and second power lines of a switch and generates a rectified voltage. The switch is capable of operating in a first state in which the switch conducts power to the first power line but not the second power line, a second state in which the switch conducts power to the second power line but not the first power line, and a third state in which the switch conducts power to both the first and second power lines. The converter converts the rectified voltage to an output voltage to drive a light source, and controls a current through the light source according to a driving signal. The controller monitors the operation state of the switch and generates the driving signal based on the operation state to control brightness/dimming of the light source. | 06-05-2014 |
20150022109 | DRIVING CIRCUIT WITH DIMMING CONTROLLER FOR DRIVING LIGHT SOURCES - A driving circuit includes a power converter, a dimming controller and a current path coupled to the dimming controller. The power converter receives input power from a rectifier and provides output power to a light source. A power switch transfers power from an AC power source to the rectifier when the power switch is on. The dimming controller receives a switch monitoring signal indicative of the state of the power switch. An average current flowing through the light source has a first value if the power switch is on. The dimming controller is operable for adjusting the average current based on the switch monitoring signal. A current flows from the AC power source through the current path to ground when the power switch is off. | 01-22-2015 |