Cuvee Systems, Inc.

Exclara, Inc.

Lanh Cong Nguyen

Dongsheng Zhou

Anatoly Shteynberg

Harry Rodriguez

Mark Eason

Methods and systems for improved dimming of LED based illumination devices are described herein. An AC input voltage provided to an LED driver is rectified and the rectified signal is monitored by a Rectified Voltage Monitor (RVM) circuit. The RVM circuit generates a low voltage monitor signal indicative of the shape and peak voltage of the rectified signal. The monitor signal and the rectified signal are communicated to a power converter of the LED driver. The controller of the power converter employs the monitor signal to maintain efficiency and stability of the LED driver over an extended range of AC input voltage. The instantaneous voltage of the rectified signal is divided-down, and the peak value of the divided-down rectified signal is captured and stored on one or more capacitive elements. In another aspect, the peak voltage stored on one or more capacitive elements is less than 100 Volts.

LED driver with rectified voltage monitor

Methods and systems for improved dimming of LED based illumination devices are described herein. An AC input voltage provided to an LED driver is rectified and the rectified signal is divided down by a voltage divider circuit to supply electrical power to a dimming interface circuit. The fraction by which the voltage divider circuit divides down the rectified signal is controlled by a Dynamic Input Voltage Compensator (DIVC) based on the peak value of the rectified signal. In this manner, the DIVC increases the range of AC input voltage to the LED driver while maintaining efficiency and stability of the LED based illumination system by reducing the variation of the voltage supplied to the dimming interface circuit over a larger range of AC input voltage.

LED driver with input voltage compensation

Methods and systems for controlling current provided to one or more LEDs for a period of time after power supplied to the LED driver is shut down are described herein. By controlling current through the one or more LEDs after shutdown, the light emitted from the one or more LEDs transitions to zero at a predictable rate with a predictable lag time. An LED based illumination system includes an energy storage element and a controlled luminous drawdown module electrically coupled between one or more LEDs and an electrical power converter employed to control current provided to the one or more LEDs during normal operation. The controlled luminous drawdown module senses a reduction in voltage at the output of the electrical power converter and operates to control current flow through one or more LEDs of the LED string until electrical energy stored in the electrical storage element is depleted.

LED driver with controlled luminous drawdown capability

An apparatus, method and system are provided for controlling the solid state lighting, such as LEDs. An exemplary apparatus comprises: a switch for switching electrical current through the LEDs, a current sensor; a first comparator adapted to determine when a switch electrical current has reached a first predetermined threshold; a second comparator adapted to determine when the switch electrical current has reached a predetermined average current level; and a controller. The controller is adapted to turn the switch into an on state and an off state, to determine a first on time period as a duration between either a detection of a second predetermined current threshold or the turning the switch into the on state, and the detection of the predetermined average current level; to determine a second on time period as a duration between the detection of the predetermined average current level and the detection of the first predetermined current threshold; and to determine an on time period of the switch as substantially proportional to a sum of the first on time period and the second on time period. Additional exemplary embodiments utilize a difference between the first and second on time periods to generate an error signal to adjust the on time period of the switch.

Growing community of inventors

Santa Clara, CA, United States of America

Lanh Cong Nguyen