A light source device includes a light source unit having a dielectric barrier discharge lamp and a lighting circuit. The lighting circuit includes a transformer; a switching element; a controller for the switching element; a detector that detects current flowing through or voltage on a primary or a secondary side of the transformer; and a determination unit. The controller is configured to enable performing a steady-state operation of controlling ON/OFF of the switching element at a steady-state operation frequency (f1) to steadily light the dielectric barrier discharge lamp; and a determination operation of controlling ON/OFF of the switching element at a determination operation frequency (f2) higher than the steady-state operation frequency (f1), and the determination unit determines whether or not to stop the lighting operation based on the current or the voltage detected by the detector when the controller controls the switching element at the determination operation frequency (f2).

A light source device includes a light source unit having a dielectric barrier discharge lamp and a lighting circuit. The lighting circuit includes a transformer; a switching element; a controller for the switching element; a detector that detects current flowing through or voltage on a primary or a secondary side of the transformer; and a determination unit. The controller is configured to enable performing a steady-state operation of controlling ON/OFF of the switching element at a steady-state operation frequency (f1) to steadily light the dielectric barrier discharge lamp; and a determination operation of controlling ON/OFF of the switching element at a determination operation frequency (f2) higher than the steady-state operation frequency (f1), and the determination unit determines whether or not to stop the lighting operation based on the current or the voltage detected by the detector when the controller controls the switching element at the determination operation frequency (f2).

A zero-crossing detection method, and devices incorporating the method, enable a selectively enabled bias to pull-up a zero-crossing signal, thereby enabling monitoring of the zero-crossing of both half-cycles of the alternating current (AC). This improves synchronization of the device in noisy environments and enables the detection of dimming problems during either half-cycle. Aspects can detect improper dimmer firing events on either polarity of the power cycle and restore normal dimmer operations when needed.

Disclosed are dual-light-source, high dimming-ratio avionics displays with digital light processing projector technology for rendering a visual display from generated light. The dual light sources are directed towards a beam splitter adapted to pass a substantial portion of the light from the first light source and to reflect a minority portion of the light from the second light source. An image is rendered at a substantially transparent, selectively reflective substrate adapted to reflect light of a range of visible wavelengths toward a viewer of the displays.

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.

A control method of an electronic ballast of a gas discharge lamp (HID), to generate a PWM1 signal for controlling on/off of a left upper arm switch, a PWM2 signal for controlling on/off of a right upper arm switch, a PWM3 signal for controlling on/off of a left lower arm switch, and a PWM4 signal for controlling on/off of a right lower arm switch, the PWM1 signal and the PWM3 signal are low frequency signals and have an identical frequency and an opposite phase, the PWM2 signal and the PWM4 signal are high frequency signals. Duty ratios of PWM signals for controlling arms of a semiconductor full bridge circuit are changed according to a power consumption of the gas discharge lamp (HID) to control the power consumption of the gas discharge lamp (HID).

A control method of an electronic ballast of a gas discharge lamp (HID), to generate a PWM1 signal for controlling on/off of a left upper arm switch, a PWM2 signal for controlling on/off of a right upper arm switch, a PWM3 signal for controlling on/off of a left lower arm switch, and a PWM4 signal for controlling on/off of a right lower arm switch, the PWM1 signal and the PWM3 signal are low frequency signals and have an identical frequency and an opposite phase, the PWM2 signal and the PWM4 signal are high frequency signals. Duty ratios of PWM signals for controlling arms of a semiconductor full bridge circuit are changed according to a power consumption of the gas discharge lamp (HID) to control the power consumption of the gas discharge lamp (HID).

A light emission control device includes a power source circuit for a drive circuit that supplies a power for a drive circuit based on an input power, a power source circuit for a control circuit that supplies a power for a control circuit based on the input power, a control circuit, a drive circuit, and a start control circuit. The control circuit outputs a control signal for controlling turning on/off of a switching element. The drive circuit outputs a drive signal for driving the switching element based on the control signal. The start control circuit outputs a start control signal for delaying a timing at which the output of the drive signal is started after the input power is turned on.

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 arranged to conduct current through a gate terminal of the thyristor, and a control circuit configured to control the gate coupling circuit. The control circuit may control 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.