摘要:
LED light source comprising a string of LED loads (LED1-LED4) supplied by a rectified mains voltage. The number of LED loads carrying current is increased as the momentary amplitude of the rectified mains voltage increases, and is decreased as the momentary amplitude of the rectified mains voltage decreases. The order in which the LED loads start carrying a current and the order in which the LED loads stop carrying a current is reversed for each half period of the mains.
摘要:
A series arrangement of LED loads (LP1-LP4) is coupled between output terminals of a rectifier having its input terminals coupled to a mains supply supplying a low frequency AC voltage. Control means render the LED loads conductive one by one, when the amplitude of the supply voltage increases, and non-conductive one by one when the amplitude of the supply voltage decreases. The first LED load (LP1, LP2) has a forward voltage that is substantially higher than that of the other LED loads. As a consequence, the LED utilization is comparatively high, thus allowing the LED loads used in the series arrangement to be comparatively cheap.
摘要:
A series arrangement of LED loads (LP1-LP4) is coupled between output terminals of a rectifier having its input terminals coupled to a mains supply supplying a low frequency AC voltage. Control means render the LED loads conductive one by one, when the amplitude of the supply voltage increases, and non-conductive one by one when the amplitude of the supply voltage decreases. The first LED load (LP1, LP2) has a forward voltage that is substantially higher than that of the other LED loads. As a consequence, the LED utilization is comparatively high, thus allowing the LED loads used in the series arrangement to be comparatively cheap.
摘要:
The invention relates to a method and a device for driving an LED string of a first LED segment (11) and at least one further LED segment (12, 13, 14) connected in series. Each LED segment has at least one light emitting diode, LED. The LED string is powered by a rectified AC mains voltage. The first LED segment (11) is powered when the rectified AC mains voltage is above a first voltage level, and the first LED segment and the further LED segment are powered when the rectified AC mains voltage is above a second voltage level higher than the first voltage level. The first LED segment emits light having a first color temperature, and the further LED segment emits light having a second color temperature higher than the first color temperature. The light emitted by the first LED segment and the light emitted by the further LED segment are superimposed. The color temperature change of the light emitted by the LED string, when dimmed, resembles the color temperature change of an incandescent lamp.
摘要:
In a method of lighting at least part of a space, a light emitting diode (LED) string is used. The LED string comprises a first LED segment and at least one further LED segment, which are connected in series, each LED segment comprising at least one LED. The LED string is powered by a rectified AC voltage. The first LED segment is powered when the rectified AC voltage is above a first voltage level, and the first LED segment and the further LED segment are powered when the rectified AC voltage is above a second voltage level higher than the first voltage level. The first LED segment is arranged to radiate light to a first volume of the space, and the further LED segment is arranged to radiate light to a second volume of the space, the first volume being at least partly different from the second volume. The first volume may at least partly overlap the second volume.
摘要:
In a method of lighting at least part of a space, a light emitting diode (LED) string is used. The LED string comprises a first LED segment and at least one further LED segment, which are connected in series, each LED segment comprising at least one LED. The LED string is powered by a rectified AC voltage. The first LED segment is powered when the rectified AC voltage is above a first voltage level, and the first LED segment and the further LED segment are powered when the rectified AC voltage is above a second voltage level higher than the first voltage level. The first LED segment is arranged to radiate light to a first volume of the space, and the further LED segment is arranged to radiate light to a second volume of the space, the first volume being at least partly different from the second volume. The first volume may at least partly overlap the second volume.
摘要:
A string of LED loads is supplied by means of a rectified mains voltage. A cathode of each LED load is coupled to ground by means of a string. The strings are made conductive and non-conductive one by one in dependency of the instantaneous value of the rectified mains using both voltage and current sensing.
摘要:
Driver device and a corresponding driving method for driving a load, in particular an LED assembly comprising one or more LEDs. To provide a better performance, better cost-efficiency, improved power factor and reduced losses, a driver device (1,1′, 2, 2′) is provided comprising a rectifier unit (10) for rectifying a received AC supply voltage (VS), load terminals (20) for providing a drive voltage (VL) and/or a drive current (IL) for driving said load, a capacitive storage unit (30) coupled between said rectifier unit and said load terminals for storing electrical energy provided by said rectifier unit and providing electrical energy to said load, and a bridge switching unit (40) coupled between said rectifier unit and said load for switching said capacitive storage unit into a load current path from said rectifier unit to said load terminals with a desired polarity and for switching said capacitive storage unit out of said load current path.
摘要:
Driver device and a corresponding driving method for driving a load, in particular an LED assembly comprising one or more LEDs. To provide a better performance, better cost-efficiency, improved power factor and reduced losses, a driver device (1,1′, 2, 2′) is provided comprising a rectifier unit (10) for rectifying a received AC supply voltage (VS), load terminals (20) for providing a drive voltage (VL) and/or a drive current (IL) for driving said load, a capacitive storage unit (30) coupled between said rectifier unit and said load terminals for storing electrical energy provided by said rectifier unit and providing electrical energy to said load, and a bridge switching unit (40) coupled between said rectifier unit and said load for switching said capacitive storage unit into a load current path from said rectifier unit to said load terminals with a desired polarity and for switching said capacitive storage unit out of said load current path.
摘要:
A light generating device (1) is provided with at least a voltage input (21) adapted for receiving a variable voltage, at least three LED circuits (10), coupled with said voltage input (21), wherein each LED circuit (10) comprises a LED unit (14) and controllable current regulator (15) to control the current through said LED circuit (10). The light generating device (1) further comprises a controllable switch matrix (30) comprising a plurality of switches (25, 26, 27), said switch matrix (30) is configured to operate in at least three different switching modes and a controller (50), connected at least with said switch matrix (30), configured to determine said variable operating voltage and to control the switching mode of said switch matrix (30) in dependence of the determined operating voltage. To provide an efficient operation of such device (1) with a variable operating voltage, such as an AC voltage, in a first switching mode, said LED units (10) are connected parallel to each other, in a second switching mode, at least two of said LED units (10) are connected in series and in a third switching mode, said LED units 10 are connected in series with each other.