Chunghwa Picture Tubes, Ltd.

Richtek Technology Corporation

Chien-Yang Chen

Chi-Hsiu Lin

Shin-Chang Lin

Po-Kun Hsieh

Ta-Yung Yang

Isaac Y Chen

Yi-Wei Lee

Pei-Yuan Chen

Leng-Nien Hsiu

Tung-Hsin Lan

Ming-Chang Lin

Bi-Hsien Chen

Chih-Wei Chang

Tong-Cheng Jao

Chun-Chieh Chiu

Yu-Wen Chang

Chun-Chien Chiu

Shu-Wen Chang

Wei-Wen Chung

Shih-Hen Chao

Tien Yung Huang

The present invention provides a switching regulator with PFC function and a control circuit and a control method thereof. The switching regulator with PFC function includes a power stage circuit, a current sense circuit, and a control circuit. The power stage circuit operates at least one power switch therein according to an operation signal to convert an input voltage to an output voltage. When a transient voltage of the input voltage exceeds a transient voltage upper limit, or when a transient slew rate of the input voltage exceeds a transient slew rate upper limit, the control circuit adjusts a frequency response gain from a stable state frequency response gain to a transient state frequency response gain, such that a transient current of an output current does not exceed a current upper limit, and/or that a transient response time of the output current does not exceed a threshold transient time period.

Switching regulator with PFC function and control circuit and control method thereof

The present invention discloses a switching regulator capable of reducing current ripple and a control circuit thereof. The switching regulator includes a buck power stage circuit and a control circuit. The control circuit includes an operation signal generation circuit and a current source circuit for reducing current ripple. The current source circuit is coupled to the operation signal generation circuit and the buck power stage circuit, for operating a ripple reduction switch therein according to an operation signal, to convert the output voltage to a load voltage between a load node and a reference node, and to reduce a current ripple of the output current, so as to generate a load current which is supplied to a load circuit, wherein the load circuit is coupled between the load node and the reference node, and the current source circuit is coupled between the output node and the load node.

Switching regulator capable of reducing current ripple and control circuit thereof

The present invention provides a light emitting device driver circuit and a control circuit and a control method thereof. The light emitting device driver circuit includes a power stage circuit, a feedback circuit, and a control circuit. The control circuit includes a comparison circuit, a hysteresis control circuit, and a bleeder circuit. The control circuit generates an analog control signal according to a rectified dimmer signal and an output signal, for controlling the power stage circuit to regulate an output current, which is supplied to a light emitting device circuit to determine its brightness. When the analog control signal decreases to a predetermined hysteresis low level, the light emitting device driver circuit operates in a cut-off mode wherein the bleeder circuit consumes a bleeder current so as to maintain the output current at a zero current, for keeping the light emitting device circuit OFF.

Light emitting device driver circuit and control circuit and control method thereof

The present invention discloses a light emitting device control circuit with dimming function and a control method thereof. The light emitting device control circuit includes: a dimmer circuit, a rectifier and filter circuit, a power converter circuit, and a headroom voltage regulation circuit. The dimmer circuit generates an AC dimming voltage according to an AC voltage. The rectifier and filter circuit generates an input voltage according to the AC dimming voltage. The power converter circuit operates according to a control signal to convert the input voltage to an output voltage which is supplied to a light emitting device circuit. The headroom voltage regulation circuit generates the control signal according to a reference value and a difference between the input voltage and the output voltage, and regulates the difference at a level corresponding to the reference value by a feedback control loop.

Light emitting device control circuit with dimming function and control method thereof

The present invention provides a light emitting device power supply circuit with dimming function and a control circuit thereof. The light emitting device power supply circuit includes: a phase-cut dimming circuit, a rectifier circuit, a transformer circuit, and a control circuit. The transformer circuit includes an auxiliary winding, which is coupled to a primary winding, for generating a bleeder current to keep a conduction current higher than a holding current and prevent the phase-cut dimming circuit from turning OFF when the phase-cut dimming circuit operates in conductive phase. The control circuit includes a waveform analysis circuit, a bleeder current control circuit, and a bleeder current source. The bleeder current source includes a linear regulator or a variable current source. The bleeder current source controls the bleeder current so that the bleeder current is generated in a continuous and non-switching manner within the conductive phase.

Light emitting device power supply circuit with dimming function and control circuit thereof

A display capable of improving frame quality includes a display panel, a timing controller, and a source driver. The timing controller is used for generating a scan start signal, and generating at least one control signal in a blanking time of the display panel according to polarity of a last datum before the blanking time and polarity of a first datum after the blanking time. The source driver is used for generating at least one datum synchronized with the at least one control signal according to the polarity of the last datum before the blanking time, a voltage of the first datum after the blanking time and the at least one control signal. The source driver does not change a last datum of the at least one datum after the at least one control signal in the blanking time.

Display capable of improving frame quality and method thereof

A backlight module driving system and a driving method thereof are applied to a Liquid Crystal Display (LCD). In the LCD, a timing controller obtains a three-dimensional (3D) image signal provided by a graphics processor, generates a Liquid Crystal (LC) driving control signal, and generates a corresponding light adjusting signal according to a data writing time and a Vertical Blanking Interval (VBI) time of the LC driving control signal. A backlight driver obtains and analyzes the light adjusting signal, so as to disable a backlight module during the data writing time, and enable the backlight module during the VBI time.

Backlight module driving system and driving method thereof

A power supply unit provides a voltage, and a driving current to a series of light emitting diodes. A dimming unit adjusts a duty cycle of an original dimming signal to generate a dimming signal according to the driving current and an ideal current. A current sink coupled to the series of light emitting diodes adjusts a duty cycle of the driving current according to the dimming signal.

Driving circuit for driving light emitting diodes and dimmer

Method of dimming

A control signal is provided for turning on and turning off a lamp of a backlight source. For a first duration when the liquid crystal is rotating, adjust a frequency of the control signal to turn on and turn off the lamp of the backlight source consecutively or adjust a duty cycle of the control signal to turn off and then turn on the lamp of the backlight source. Thus, the backlight source has a luminance value for the first duration, and the control signal turns on the lamp of the backlight source for a second duration when the liquid crystal is in the steady state.

Method of scanning backlight driving lamps for an LCD

A light emitting diode (LED) driving device and an LED driving method thereof are provided. The LED driving device includes a voltage generator, a circuit and a compensation circuit. The voltage generator is used to provide a positive voltage and a negative voltage, and the circuit is coupled to the positive voltage and the negative voltage. Herein, the circuit includes a load and an LED which are coupled to each other in series. The compensation circuit is used to sense voltages of two ends of the load, so as to generate a compensation signal and adjust the positive voltage and the negative voltage through the compensation signal. Therefore, voltage stress of the LED driving device is reduced by using the provided positive voltage and the provided negative voltage.

Light emitting diode driving device and method thereof

A driving circuit includes a signal generator, a resonant circuit, a control circuit and an adjusting circuit. The signal generator is utilized for generating an alternating current (AC) signal having a fixed frequency. The resonant circuit is coupled to the signal generator, and is utilized for generating an oscillation signal to drive a backlight source according to the alternating current signal. The control circuit is utilized for providing a control signal. The adjusting circuit is coupled to the control circuit, the resonant circuit and the backlight source, and is utilized for providing an impedance according to the control signal to thereby adjust a current value of the backlight source.

Driving circuit and method of backlight module

A backlight module control system includes a power supply, a first backlight sub-module, a second backlight sub-module, a first transformer and a second transformer. The power supply is utilized for providing an operating power to the backlight module control system. A primary side and a secondary side of the first transformer are respectively coupled to the power supply and a first node of the first backlight sub-module. A primary side of the second transformer is coupled to the power supply, and a secondary side of the second transformer is coupled to the secondary side of the second transformer and a first node of the second backlight sub-module.

Backlight module control system whose two backlight sub-modules are in a closed loop

A light source driving circuit includes a voltage signal source and a temperature-improving current source for adjusting luminance of a series of LEDs. A first end of the series of LEDs is electrically connected to a ground end. The temperature-improving current source includes an adjustable power supply for outputting an adjustable voltage, a voltage-controlled current source for outputting currents according to the voltage signal source, and a feedback circuit electrically connected between a second end of the series of the LEDs and the adjustable power supply for controlling the output voltage of the adjustable power supply according to the voltage on the second end of the series of LEDs.

Light source driving module and circuit

A driving circuit for an LED backlight system is disclosed. The driving circuit includes an input voltage, an input resistor, an operational amplifier, a first transistor and a current calculation unit. The operational amplifier has a positive input terminal electrically connected to the input voltage through the input resistor, and an output terminal electrically connected to its negative input terminal thorough a feedback network. The first transistor is utilized for draining a reference current to control an output voltage of the operational amplifier according to the input voltage and the input resistor. The current calculation unit is utilized for generating a plurality of working currents proportional to the reference current to drive a plurality of LED strings according to the output voltage of the operational amplifier.

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Taipei, Taiwan

Chien-Yang Chen