In one example, a method includes determining, by a device of a system, a voltage feedback value that represents a voltage level of a power signal being provided to a plurality of load elements that are selectively active. In this example, the method also includes adjusting, by the device and based on a quantity of load elements of the plurality of load elements that are active, the voltage level of the power signal such that the voltage feedback value remains less than or equal to an overvoltage threshold.

The lighting device includes a power conversion circuit and a control circuit. The power conversion circuit includes a high voltage side output terminal and a low voltage side output terminal to be connected to a light source, and a step-down chopper circuit. The control circuit performs a lighting operation of controlling the power conversion circuit to develop a DC output voltage between the high voltage side output terminal and the low voltage side output terminal. The control circuit starts a protective operation of limiting a current to be supplied to the light source when the output voltage is equal to or higher than a threshold value. The threshold value is in a range of 1.2 to 1.3 times a rated voltage of the light source.

A lighting control device that controls a lighting device includes: a brightness sensor that obtains brightness information indicating a current brightness of an illuminated surface; a storage that stores a brightness target value for the illuminated surface; a controller; a receiver via which the controller receives an energy-saving signal; and a transmitter that transmits, to the lighting device, a control signal generated by the controller. When the energy-saving signal is not being received, the controller determines a dimming rate for the lighting device based on the brightness target value and the brightness information. When the energy-saving signal is being received, the controller determines an energy-saving brightness target value smaller than the brightness target value by multiplying the brightness target value by a predetermined rate and determines an energy-saving dimming rate for the lighting device based on the energy-saving brightness target value and the brightness information.

An LED driver includes a controller configured to detect toggles of a switch that controls whether electrical power is provided to the LED driver. The controller is further configured to determine whether a toggle sequence of the switch matches an operation mode sequence. The toggle sequence of the switch includes a sequence of one or more toggles of the toggles of the switch that the controller detects. The controller is also configured to change a setting of the LED driver based on whether the toggle sequence of the switch matches the operation mode sequence.

An auxiliary power system for powering an auxiliary circuit is connected to the same power source that powers the lighting element within a luminaire. The auxiliary power system may be connected to the output of the power source in series or in parallel with the lighting element. The power source may be an LED driver and the lighting element may include one or more LEDs or the power source may be an electronic ballast and the lighting element may be one or more fluorescent lamps.

A method of messaging with light is implemented by a light fixture. The method includes: timing and recording a switch-on period, and recording an operation mode of the light fixture during receipt of the electrical power; and operating in a messaging mode the next time the light fixture receives electrical power upon determining that the recorded operation mode is a lighting mode and that the recorded switch-on period is within a predetermined range of time period. In the messaging mode, the light fixture controls a light emitting device to send a binary message by operating in a sequence composed at least of a first brightness state and/or a second brightness state.

A color tuning system including a first plurality of LEDs having a first color temperature, a second plurality of LEDs having a second color temperature, a wave generator electrically connected to the first plurality of LEDs and the second plurality of LEDs, where the waveform generator transmits a first signal to the first plurality of LEDs for a first predetermined time and a second signal to the second plurality of LEDs for a second predetermined time.

A temperature compensation circuit for a light source (e.g., light emitting diode (LED)) whose radiant energy output decreases when ambient temperature increases includes a first circuit element for generating a first current that increases proportional to an increase in the ambient temperature, and a second circuit element for generating a second current that is first order independent of the ambient temperature. The circuit further includes a weighted current adder for generating a third current by combining the first and second currents with first and second weights applied to the first and second currents respectively. The circuit further includes a third circuit element responsive to the third current for supplying a fourth current to the light source to maintain a radiant energy output of the light source constant independent of the ambient temperature.

An LED tube lamp is disclosed. The LED tube lamp includes a lamp tube, a first external connection terminal and a second external connection terminal coupled to the lamp tube and for receiving an external driving signal, a rectifying circuit coupled to the first external connection terminal and the second external connection terminal and configured to rectify the external driving signal to produce a rectified signal, a filtering circuit coupled to the rectifying circuit and configured to filter the rectified signal to produce a filtered signal, an LED module coupled to the filtering circuit and configured to receive the filtered signal for emitting light; and a conduction-delaying circuit coupled to the rectifying circuit and comprising a conduction-delaying device, wherein the conduction-delaying circuit is configured such that when the external driving signal is initially input to the LED tube lamp, the conduction-delaying device is in an open-circuit state, and then the conduction-delaying device will enter a conducting state when voltage across the conduction-delaying device exceeds the conduction-delaying device's trigger voltage value, wherein the conducting state of the conduction-delaying device causes the LED module to conduct current for emitting light.

Devices and methods for protecting against a surge in a luminaire are provided. For example, a controller for use with a luminaire is provided. The controller can include a first circuit configured to sense a surge in voltage or current. The controller can further include a second circuit configured to switch a relay in response to the first circuit having sensed the surge in voltage or current.