| 摘要 |
Embodiments generally relate to methods for gradually brightening or dimming the brightness of one or more light emitting diodes, in particular methods of dawn simulation, methods of dusk simulation, dawn simulators, dusk simulators and light therapy devices, and methods of providing a substantially continuous brightness sweep of an LED(s). An example method of dawn simulation using at least one light emitting diode (LED) comprises a plurality of iterations of pulse width modulating a drive signal to an LED, an initial one of the iterations to increase brightness of the LED from zero and followed by at least one further said iteration, wherein each of the iterations comprises: increasing duty cycle of the drive signal from a start duty cycle to an end duty cycle, wherein the start duty cycle and a start amplitude of the drive signal provide a start brightness of the iteration and the end duty cycle and an end amplitude of the drive signal provide an end, higher brightness of the iteration, wherein the start amplitude of a said further iteration is higher than the start amplitude of an immediately preceding one of the iterations, and a product of the start duty cycle and the start amplitude of the further iteration is equal to a product of the end duty cycle and the end amplitude of the immediately preceding iteration. |
