A dimmable ballast circuit for a compact fluorescent lamp controls the intensity of a lamp tube in response to a phase-control voltage received from a dimmer switch. The ballast circuit comprises a phase-control-to-DC converter circuit that receives the phase-control voltage, which is characterized by a duty cycle defining a target intensity of the lamp tube, and generates a DC voltage representative of the duty cycle of the phase-control voltage. Changes in the duty cycle of the phase-control voltage that are below a threshold amount are filtered out by the converter circuit, while intentional changes in the duty cycle of the phase-control voltage are reflected in changes in the target intensity level and thereby the intensity level of the lamp tube.

A discharge lamp driver includes a discharge lamp driving unit configured to supply drive current to a discharge lamp and a control unit configured to control the discharge lamp driving unit. The drive current has a modulation drive period in which a first period in which AC current having a frequency higher than 1 kHz is supplied and a second period in which DC current is supplied are alternately repeated. In the modulation drive period, the control unit periodically changes length of a first DC period included in the second periods and in which DC current of a first polarity is supplied, and length of a second DC period included in the second periods and in which DC current of a second polarity is supplied, and increases one of the length of the first DC period and the length of the second DC period while decrease the other one.

A control scheme for a dimmable lighting driver is provided. The control scheme may operate with a phase cut type dimmer (leading or trailing edge). In an embodiment, the control scheme is programmed or otherwise configured into a controller as a control algorithm. The control algorithm is configured to measure phase cut and zero crossing angles of the input mains waveform, and to subsequently maintain constant LED current commensurate with a user-set dimming level, with no flicker. The control algorithm may be implemented in software, such as a firmware-based routine executable by one or more controllers of a given driver. The one or more controllers may be, for example, an existing general purpose controller of the given driver, or a dedicated dimming controller. Numerous configurations will be apparent in light of this disclosure.

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.

A discharge lamp driving device according to one aspect of the invention includes a discharge lamp driving section configured to supply a driving current to a discharge lamp including electrodes and a control section configured to control the discharge lamp driving section. The control section controls the discharge lamp driving section such that a mixed period is provided in which a first period in which an alternating current having a first frequency is supplied to the discharge lamp and a second period in which a direct current is supplied to the discharge lamp are alternately repeated. The first frequency includes a plurality of frequencies different from one another. The control section temporally changes the length of the first period.

A discharge lamp driving device according to one aspect of the invention includes a discharge lamp driving section configured to supply a driving current to a discharge lamp including electrodes and a control section configured to control the discharge lamp driving section. The control section controls the discharge lamp driving section such that a mixed period is provided in which a first period in which an alternating current having a first frequency is supplied to the discharge lamp and a second period in which a direct current is supplied to the discharge lamp are alternately repeated. The first frequency includes a plurality of frequencies different from one another. The control section temporally changes the length of the first period.

A magnetic induction circuit, a magnetic-controlled switch circuit, a magnetic-controlled device and a magnetic-controlled lamp. The magnetic induction circuit includes a magnetic induction module, a voltage comparison module and a voltage output module. The magnetic induction module is configured to sense an external magnetic field to generate a first voltage signal. The voltage comparison module is configured to receive the first voltage signal, and output a second voltage signal. The voltage output module is configured to process the second voltage signal and output a third voltage signal.

A magnetic induction circuit, a magnetic-controlled switch circuit, a magnetic-controlled device and a magnetic-controlled lamp. The magnetic induction circuit includes a magnetic induction module, a voltage comparison module and a voltage output module. The magnetic induction module is configured to sense an external magnetic field to generate a first voltage signal. The voltage comparison module is configured to receive the first voltage signal, and output a second voltage signal. The voltage output module is configured to process the second voltage signal and output a third voltage signal.

Embodiments are included for providing an energy efficient lighting system that includes one or several luminaires. According to certain aspects, when an area covered by the luminaires is vacant, the light level in the area is measured while the luminaires are on and set to a low dim level. The measured light level is used to approximate the amount of natural light in the area and when the measured light level exceeds a predetermined nonzero light level, the luminaires are turned off for a certain time period. Once the time period expires, the light level is measured again to approximate the amount of natural light present in the area.

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.