Segmental driving of light emitting circuits
Disclosed is a driver that include a switching circuit for guiding current signal during time-intervals for the sequential driving of light emitting circuit. The time-intervals are defined by the fact that amplitudes of a mains signal are in ranges during the time-intervals. More specifically, there is a bypass switching circuit for guiding a bypass current signal which bypasses all light emitting circuit during an initial time-interval. An adaptation circuit adapts amplitudes of the respective current signals during the respective time-intervals, to reduce a total harmonic distortion. Said adapting may comprise an adaptation in response to information derived from the amplitude of the mains signal, and may comprise shaping the amplitudes of the current signals in response to information derived from the amplitude of the mains signal.
1. A driver adapted to connect to light emitting circuits and for driving the light emitting circuits, the driver comprising:
a bypass switching circuit for guiding a bypass current signal which bypasses all light emitting circuit during an initial time-interval, amplitudes of a mains signal for feeding the driver being in an initial range and less than a minimum voltage amplitude across a first light emitting circuit to start emitting light during the initial time-interval,
a first switching circuit for guiding a first current signal through the first light emitting circuit during a first time-interval, amplitudes of the mains signal being in a first range during the first time-interval, the amplitudes of the mains signal in the first range being larger than the amplitudes of the mains signal in the initial range,
a second switching circuit for guiding a second current signal through a series connection of the first light emitting circuit and a second light emitting circuit during a second time-interval, amplitudes of the mains signal being in a second range during the second time-interval, the amplitudes of the mains signal in the second range being larger than the amplitudes of the mains signal in the first range, and
an adaptation circuit for adapting an amplitude of the bypass current signal during the initial time-interval and for adapting an amplitude of the first current signal during the first time-interval and for adapting an amplitude of the second current signal during the second time-interval so that the bypass current follows the mains signal at least in the form.
2. The driver as defined in claim 1 , wherein the driver further comprising
an input for receiving input power,
the bypass switching circuit is connected across the input and is adapted to short circuit the input, via a series connection with the adaptation circuit, and to guide the bypass current directly across the input without going through the first light emitting circuit or the second light emitting circuit.
3. The driver as defined in claim 1 , said adaptation circuit is for adapting the amplitudes in response to information derived from the amplitude of the mains signal, wherein
in case the amplitude of the mains signal is changing, the adaptation circuit is adapted to adapt the amplitude of the corresponding current signal..
4. The driver as defined in claim 1 , said adaptation circuit is for:
increasing the amplitudes of the respective current signals when the amplitude of the mains signal in the respective ranges is increasing, and
decreasing of the amplitudes of the respective current signals when the amplitude of the mains signal in the respective ranges is decreasing.
5. The driver as defined in claim 1 , said adaptation circuit is for shaping the amplitudes of the current signals in response to information derived from the amplitude of the mains signal,
wherein in case the amplitude of the mains signal is changing to a relatively small extent, the adaptation circuit is adapted to shape the amplitude of the corresponding current signal to a relatively small extent, and
in case the amplitude of the mains signal is changing, the adaptation circuit is adapted to shape the amplitude of the corresponding current signal.
6. The driver as defined in claim 1 , said adaptation circuit is for shaping the amplitudes of the respective current signals, the shaped amplitudes of the respective current signals being identical to shapes of the amplitude of the mains signal in the respective ranges.
7. The driver as defined in claim 1 , the adaptation circuit comprising a current source for in response to a definition signal defining the amplitudes of the bypass current signal, the first current signal and the second current signal, and the adaptation circuit further comprising a definition circuit for in response to a detection of the amplitude of the mains signal providing the definition signal to the current source.
8. A device comprising the driver as defined in claim 1 and further comprising the first and second light emitting circuits.
9. The driver as defined in claim 1 , wherein the adaptation circuit is adapted such that at least one of the first current and the second current follows the mains signal at least in the form, and
wherein the mains signal is mains voltage.