Iml International

Addtek Corp.

Yung-Hsin Chiang

Yi-Mei Li

Horng-Bin Hsu

Alberto Giovanni Viviani

Shih-Yuan Wang

Kai-Yun Cheng

Woung Moo Lee

Lai-Hua Luo

Hwan Lim

Yih-Wey Tang

Yu-Ming Hsu

An LED lighting system includes a luminescent unit driven by a rectified AC voltage, a dimmer switch configured to adjust a duty cycle of a system current, and a bleeder circuit. The bleeder circuit includes a first current source, a second current source, a third current source, a current-sensing element for providing a first feedback voltage associated with the system current, a capacitor, and a control unit. The control unit is configured to activate the first current source and deactivate the second current source for charging the capacitor when the system current exceeds a predetermined threshold, deactivate the first current source and activate the second current source for discharging the capacitor when the system current does not exceed the predetermined threshold, and deactivate the third current source to stop supplying the bleeder current according to a second feedback voltage established across the capacitor.

Light-emitting diode lighting system with automatic bleeder current control

An LED lighting system includes a luminescent unit driven by a rectified AC voltage, a dimmer switch configured to adjusting a duty cycle of a system current, and a bleeder circuit. The bleeder circuit includes a first current source, a second current source, a third current source, a current-sensing element for providing a first feedback voltage associated with the system current, a capacitor, and a control unit. The control unit is configured to activate the first current source and deactivate the second current source for charging the capacitor when the system current exceeds a predetermined threshold, deactivate the first current source and activate the second current source for discharging the capacitor when the system current does not exceed the predetermined threshold, and deactivate the third current source to stop supplying the bleeder current according to a second feedback voltage established across the capacitor.

An LED lighting device includes at least two luminescent devices, two current sensing elements, and two current regulators. The first and second luminescent device are driven by a rectified AC voltage for providing light according to first current and second current, respectively. The first current sensing element provides a first feedback voltage associated with the first current and the second current sensing element provides a second feedback voltage associated with the second current. The first current regulator provides a first regulating current setting according to the first feedback voltage and a line voltage detection voltage associated with the rectified AC voltage, wherein the waveform of the first regulating current setting follows the waveform of the rectified AC voltage. The second current controller is coupled in parallel to the second luminescent device and provides a constant second regulating current setting according to the second feedback voltage.

Light-emitting diode lighting device

An LED lighting device driven by a rectified AC voltage includes a luminescent device, a charge storage unit and a current controller. The charge storage unit is configured to turn on the luminescent device when the rectified AC voltage is still insufficient to turn on the luminescent device. The current control unit is configured to allow the LED lighting device to have constant luminance regardless of the level of the rectified AC voltage or dimmer condition, thereby improving flicker phenomenon.

Low-flicker light-emitting diode lighting device

An LED lighting device driven by a rectified AC voltage includes a luminescent device, a charge storage unit and a current controller. The charge storage unit is configured to turn on the luminescent device when the rectified AC voltage is still insufficient to turn on the luminescent device. The current control unit is configured to allow the LED lighting device to have constant luminance regardless of the level of the rectified AC voltage, thereby improving flicker phenomenon.

An LED lighting device includes a luminescent circuit, a detecting circuit, an adjustable current source and a dimming control circuit. The luminescent circuit is driven by a rectified AC voltage for providing light. The detecting circuit is configured to detect a rising edge or a falling edge of the LED current associated with a frequency of the rectified AC voltage. The dimming current regulator is configured to vary a duty cycle of the LED current according to a PWM signal. The dimming control circuit is configured to generate the PWM signal and synchronize a frequency of the PWM signal with the frequency of the rectified AC voltage at the detected rising edge or the falling edge of the rectified AC voltage.

Light-emitting diode lighting device with synchronized PWM dimming control

An LED lighting device includes first and second luminescent units, first and second current controllers, a line voltage sensing unit and a mode control unit. The first current controller with a first current setting is selectively coupled to the first luminescent unit according to a sensing voltage associated a range of the rectified AC voltage. The second current controller with a second current setting is coupled in series to the second luminescent unit. The line voltage sensing unit is configured to detect the sensing voltage. The mode control unit is configured to operate the LED lighting device in a first driving mode when detecting that the rectified AC voltage is within a first AC range and operate the LED lighting device in a second driving mode when detecting that the rectified AC voltage is within a second AC range.

Dual mode operation light-emitting diode lighting device having multiple driving stages

An LED lighting device includes first through third luminescent devices and first through third current controllers. The first and second luminescent devices are driven by a rectified AC voltage for providing light of a first color. The third luminescent device is driven by the rectified AC voltage for providing light of a second color different from the first color. The first through third current controllers are configured to regulate the current flowing through the first through third current controllers according to a first current setting, a second current setting and a third current setting, respectively. The color rendering index of the LED lighting device can thus be adjusted flexibly.

Light-emitting diode lighting device with adjustable color rendering indexes

An LED lighting device includes multiple luminescent devices driven by a rectified AC voltage. The multiple luminescent devices are turned on flexibly in a multi-stage driving scheme using multiple current control units. At least one charge storage unit is coupled in parallel with at least one luminescent device. When the rectified AC voltage is still insufficient to turn on the at least one luminescent device, the at least charge storage unit is configured to discharge energy to the at least one luminescent device, thereby keeping the at least one luminescent device turned on.

Low-flickerlight-emitting diode lighting device having multiple driving stages

An LED lighting device includes a slave driving stage and a master driving stage. The slave driving stage includes a first luminescent device and a first current controller for providing a constant current setting in an ON phase. The master driving stage includes a second luminescent device and a current control unit having a second current controller and a current envelope controller. The second current controller provides a current envelope in the ON phase. The current envelope controller sets a level of the current envelope according to a rectified AC voltage. The driving current is regulated by the first current controller according to the constant current setting when the constant current setting is smaller than the level of the current envelope, or by the second current controller according to the current envelope when the level of the current envelope is smaller than the constant current setting.

Light-emitting diode lighting device having multiple driving stages

An LED lighting device includes multiple driving stages. A first driving stage includes a first luminescent device driven by a first current and a first current controller coupled in parallel with the first luminescent device. The first current controller is configured to conduct a second current according to a voltage established across the first current controller and regulate the second current so that a sum of the first current and the second current does not exceed a first value. The second driving stage includes a second luminescent device driven by a third current and a second current controller coupled in series to the second luminescent device. The second current controller is configured to conduct a fourth current according to a voltage established across the second current controller and regulate the fourth current so that a sum of the third current and the fourth current does not exceed a second value.

An LED lighting device includes a first luminescent device, a second luminescent device, a first current controller and a second current controller. The first current controller is coupled in parallel with the first luminescent device and configured to operate according to a first current setting, a switch-on voltage and a switch-off voltage. The second current controller is coupled in series to the second luminescent device and configured to operate according to a second current setting. The first current setting, the second current setting, the switch-on voltage and the switch-off voltage are adjusted by setting the mode selection pins of the first and second current controllers.

Light-emitting diode lighting device with adjustable current settings and switch voltages

A two-terminal current controller controls a first current flowing through a parallel-coupled load. During a rising period of a rectified AC voltage, when a load voltage does not exceed a first voltage, the two-terminal current controller operates in a first mode. When the load voltage exceeds the first voltage but does not exceed a second voltage, the two-terminal current controller operates in a second mode. When the load voltage exceeds the second voltage, the two-terminal current controller operates in a third mode. When the load voltage drops to a third voltage smaller than the second voltage after exceeding the second voltage, the two-terminal current controller operates in the second mode when a difference between the second and third voltages exceeds a hysteresis band and operates in the third mode when a difference between the second and third voltages does not exceed the hysteresis band.

Two-terminal current controller and related LED lighting device

A light emitting diode luminance system includes a first power source, a voltage divider, a first switch, a clamping device, a plurality of current sources and a feedback circuit. The voltage divider is coupled to the first voltage source. The first switch is coupled to the voltage divider and a ground. The clamping device includes a plurality of transistors each coupled to a respective set of light emitting diodes and the voltage divider. The plurality of current sources is coupled to the plurality of transistors respectively. The feedback circuit is coupled to the plurality of transistors and the plurality sets of light emitting diodes.

Light emitting diode luminance system having clamping device

The present invention provides a light source dimming control circuit, which includes a voltage signal generator for generating a first voltage signal between a predetermined voltage level and a ground level; a reference voltage signal generator for generating a reference voltage signal at an output end according to the first voltage signal and a second voltage signal; a first switch with a first end coupled to an output end of alight source; a first resistor with a first end coupled to a second end of the first switch, and a second end coupled to a ground end; a switch controller coupled to the first switch and the voltage signal generator for controlling on/off states of the first switch according to a sawtooth signal and the first voltage signal; and a current controller for controlling current flowing through the first resistor according to the reference voltage signal.

Growing community of inventors

Taipei, Taiwan

Yung-Hsin Chiang