Signify Holding B.v.

General Electric Company

Kelvin Wang

Liang Shi

Zhi Quan Chen

John Dai

Bin Wei

Jie Fu

Yuanfeng Luo

Renwei Yuan

Michael Scott Lamphere

Shan Shan Wang

In order to reduce energy loss of a tapped linear driver, it is proposed an LED lighting circuit, comprising an input (Vbus, GND) adapted to receive an input voltage, a plurality of LED segments (LED, LED, LED, LED) connected in series and to the input, a buffer component (C) connected to an anode and a cathode of a series string of at least two of the plurality of LED segments with respective switches, a current source circuit (B) in series connection with a parallel connection of the buffer component (C) and the at least two LED segments, across the input; further comprising a further buffer component (C) across the current source circuit (B), wherein said buffer component (C) and the further buffer component (C) is in series connection.

LED lighting circuit and a lighting device comprising the same

A LED lighting circuit has a plurality of LED segments connected in series. A switching arrangement is used to selectively bypass at least one LED segment to implement a tapped linear driver approach. Degrading of a component in the LED lighting circuit is detected, so that a first TLD current modulation scheme is implemented when no such degrading is detected whereas a second current modulation scheme, different from the first current modulation scheme, is implemented to compensate for said degrading. Said degrading is leading to an increase in a turning on voltage of one LED segment, and compared to said first current modulation scheme, said second current modulation scheme has a higher voltage threshold at which said LED segment is switched. In this way, protection may be provided for circuit components and the light output may be maintained at the desired level in the event of component degrading, such as LED chip failure or contact resistance changes.

Tapped linear driver and driving method

A LED driving circuit () is for driving at least two LED segments () of different color or color temperature, using an input current which has a current ripple amplitude. The LED driving circuit () comprises an input to receive the input current; an output to connect to the at least two LED segments (); and a current distributing circuit which provides the input current to a single one of the two LED segments when the current is at a peak portion, wherein the current distributing circuit is adapted, when providing the input current to a single one of the two LED segments during the peak portion, to provide the input current to the single one of the two LED segments alternately, and splits the input current into two non-zero currents for different LED segments when the current is in a trough. When all current is provided to one LED segment, the light conversion efficiency is lower than when two segments are driven with lower current. This means the effect which the current ripple has on the light output is reduced. The driving circuit effectively compensates for the current ripple by adjusting the light conversion efficiency so that a flatter light output characteristic is obtained.

LED driving circuit

A method for monitoring machining in an electroerosion assembly having a power supply and an electrode arranged across a gap from a workpiece, includes measuring a voltage at a point in a voltage waveform after a time delay tof one half of a pulse width of the voltage waveform. The measurements are repeated for multiple pulses of the voltage waveform to obtain multiple voltages, each of the voltages corresponding to a point in respective pulses. The voltages are averaged to obtain an average voltage, which is compared with at least one threshold voltage, to determine whether the machining is in control. A control signal is generated if the comparison indicates that the process is not in control, the control signal being configured to regulate an operating parameter of the power supply, and the control signal is supplied to the power supply, if generated.

Methods and systems for monitoring and controlling electroerosion

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Shanghai, China

Kelvin Wang