There is provide a discharge lamp lighting apparatus that comprises a discharge lamp and a power supply device configured to drive a regular lighting mode and the low electric power lighting mode in a switchable manner. The power supply device configured to control a power supply to the discharge lamp such that, in the low electric power lighting mode, after a secondary protrusion forming process in which an alternating current having a frequency equal to or greater than the basic frequency in the regular lighting mode is supplied, the low electric power lighting mode transitioning to a secondary protrusion maintaining process in which a high frequency alternating current having a frequency higher than the basic frequency in the regular lighting mode, and a low frequency alternating current having a frequency lower than the frequency of the high frequency alternating current is alternately supplied.

A dimming lighting circuit includes: a rectifier circuit; a phase detection circuit which outputs a dimming signal having a signal level corresponding to a conduction phase angle of an AC voltage; and a DC-DC converter which receives a DC voltage output from the rectifier circuit and supplies a light source with a DC current corresponding to the signal level of the dimming signal output from the phase detection circuit. If the conduction phase angle detected when the dimming lighting circuit receives the AC voltage at power-on is less than or equal to a predetermined angle, the phase detection circuit outputs, as the dimming signal, a substitute signal having a signal level corresponding to a conduction phase angle greater than the conduction phase angle of the AC voltage, for a predetermined time period.

A dimmable instant-start ballast for a plurality of LED lamps and/or a plurality of fluorescent lamps is provided, which includes an isolated dimming interface, a duty control device, a dimming switch, and an inverter circuit. The isolated dimming interface receives a dimming signal to generate a dimming voltage. The duty control device generates an operation signal according to the dimming voltage. The dimming switch periodically couples a first node to a ground according to the operation signal. The inverter circuit receives a rectified voltage and is coupled to the first node. When the first node is coupled to the ground terminal, the inverter circuit provides a lamp current for the LED lamps and/or the fluorescent lamps.

A dimmable instant-start ballast for a plurality of LED lamps and/or a plurality of fluorescent lamps is provided, which includes an isolated dimming interface, a duty control device, a dimming switch, and an inverter circuit. The isolated dimming interface receives a dimming signal to generate a dimming voltage. The duty control device generates an operation signal according to the dimming voltage. The dimming switch periodically couples a first node to a ground according to the operation signal. The inverter circuit receives a rectified voltage and is coupled to the first node. When the first node is coupled to the ground terminal, the inverter circuit provides a lamp current for the LED lamps and/or the fluorescent lamps.

A discharge lamp driving device includes: a discharge lamp driving unit which supplies drive power to a discharge lamp; and a control unit which controls the discharge lamp driving unit according to a waveform of the drive power. The waveform has n launching periods and a low-power mode lighting period. The n launching periods include a first launching period in which the drive power increases toward refresh power that is equal to or above drive power in a low-power mode and equal to or below rated power, and (n1) launching periods in which the drive power is maintained at the refresh power. The control unit, in an x-th launching period, supplies the discharge lamp with a drive current having a drive frequency equal to or below a drive frequency of a drive current supplied to the discharge lamp in an (x1)th launching period.

Provided are circuits and methods for a digital controller for an electronic ballast for a fluorescent lamp, comprising a feed-forward loop that provides information about a voltage firing angle, and a pulse width modulator that controls a duty ratio of at least one power switch of the electronic ballast according to the information. The digital controller may include a duty ratio controller implemented in the pulse width modulator. The digital controller may include one or more functions such as dimming, maintaining high power factor throughout the dimming range, low lamp power detection, lamp soft-start, and DC-link capacitor over-voltage detection for end of life protection or lamp failure protection. In one embodiment the ballast is a single stage, single switch ballast.

A discharge lamp lighting apparatus for lighting a discharge lamp in which an electric discharge medium, which contains xenon, is enclosed in an electric discharge container, and a pair of cathode electrode and anode electrode for main discharge is arranged to face each other, comprises a starter for generating dielectric breakdown in the electric discharge container of a discharge lamp, and a power supply circuit for supplying discharge current to the discharge lamp, wherein the power supply circuit has an output current modulation circuit for modulating the magnitude of current passed through the discharge lamp in at least a lighting steady state, according to a modulation signal, and wherein the output current modulation circuit controls speed of change so as to be 2.6 A or less per millisecond in case the magnitude of the lamp current per square millimeter in a cross section of the cathode electrode decreases.

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.