A load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor (such as, a triac) coupled between the source and the load, a gate coupling circuit coupled to conduct current through a gate terminal of the thyristor, a controllable switching circuit coupled between the gate coupling circuit and the gate terminal of the thyristor, and a control circuit configured to control the gate coupling circuit and the controllable switching circuit. The control circuit may cause the gate coupling circuit to conduct a pulse of current through the gate terminal to render the thyristor conductive at a firing time during a present half cycle of the AC power source, and allow the gate coupling circuit to conduct at least one other pulse of current after the firing time during the present half cycle.

In an example, a light control system includes a power converter, a light source, a sensor, and a control device. The power converter can convert an input power received from a power source to a supply power, and includes a power factor corrector (PFC) configured to adjustably control an electrical parameter of the supply power. The light source can, using the supply power, emit light at an intensity related to the electrical parameter. The sensor can sense a condition related to operation of the light source. The control device is communicatively coupled to the PFC and the sensor, and configured to: (i) receive, from the sensor, a sensor signal indicating an input parameter related to the condition, and (ii) based on sensor signal, provide a feedback signal to the PFC to cause the PFC to adjust, based on the input parameter, the electrical parameter of the supply power.

In an example, a power factor corrector (PFC) including a first PFC input, a second PFC input, and a PFC output. The first PFC input is configured to receive an input power from a power source. The second PFC input is configured to receive a signal from a feedback circuit. The PFC output configured to output a direct current (DC) power, which is based on the input power at the first PFC input and the signal at the second PFC input. The feedback circuit is coupled to the PFC output and the second PFC input. The feedback circuit is configured to provide the signal at the second PFC input based on an input parameter related to a condition that is sensible by a sensor. The condition is related to operation of a load.

A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.

A light-emitting diode driving module includes an LED driving circuit to activate light-emitting diodes driven by a modified rectified voltage, and to adjust driving currents conducted to driving nodes to the light emitting diodes; a driving current controller to receive a dimming signal indicative of a degree of modulation of the rectified voltage, and to control currents conducted to the driving nodes depending on the dimming signal; and a current blocking circuit to block the currents of the driving nodes when a dimming level of the dimming signal decreases lower than a first threshold value, and unblock the currents of the driving nodes when the dimming level increases above a second threshold value higher than the first threshold value.

A discharge lamp drive device includes a discharge lamp driver configured to supply drive electric current to a discharge lamp having a first electrode and a second electrode, a control unit configured to control the discharge lamp driver, and a storage unit configured to store a plurality of drive patterns of the drive electric current. The control unit is configured to select one drive pattern from among the plurality of drive patterns based on machine learning, and implement the selected drive pattern. The control unit performs a first control that increases a drive electric power supplied to the discharge lamp according to an increase in an inter-electrode voltage of the discharge lamp, in a case where the inter-electrode voltage is equal to or larger than a first voltage value and the inter-electrode voltage is equal to or lower than a second voltage value higher than the first voltage value.

A discharge lamp drive device includes a discharge lamp driver adapted to supply a drive current to a discharge lamp having a first electrode and a second electrode, a control section adapted to control the discharge lamp driver, and a storage section adapted to store a plurality of drive patterns of the drive current. The control section is configured to select one drive pattern of the plurality of drive patterns based on machine learning, and execute the selected drive pattern. In a case in which a predetermined condition is fulfilled, the control section executes a predetermined drive pattern of the plurality of drive patterns without selecting and executing the drive pattern based on the machine learning.

A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.

A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.

An electronic dimming ballast or light emitting diode (LED) driver for driving a gas discharge lamp or LED lamp may be operable to control the lamp to avoid flickering and flashing of the lamp during low temperature or low mercury conditions. Such a ballast or driver may include a control circuit that is operable to adjust the intensity of the lamp. Adjusting the intensity of the lamp may include decreasing the intensity of the lamp. The control circuit may be operable to stop adjustment of the intensity of the lamp if a magnitude of the lamp voltage across the lamp is greater than an upper threshold, and subsequently begin to adjust the intensity of the lamp when the lamp voltage across the lamp is less than a lower threshold. Subsequently beginning to adjust the intensity of the lamp may include subsequently decreasing the intensity of the lamp.