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Method for operating at least one light-emitting diode and lighting device for carrying out the method

A technology of light-emitting diodes and lighting devices, applied in lighting devices, electroluminescent light sources, light sources, etc., can solve the problems of expensive current sources and disadvantages for users, and achieve the effect of reducing nonlinearity

Inactive Publication Date: 2016-11-30
OSRAM GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] One possibility to deal with the disadvantage is to use fast current sources, which however are relatively expensive
Flickering at low dimming levels and / or color shifts at low dimming levels can also be tolerated, but this is considered disadvantageous by the user

Method used

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  • Method for operating at least one light-emitting diode and lighting device for carrying out the method
  • Method for operating at least one light-emitting diode and lighting device for carrying out the method
  • Method for operating at least one light-emitting diode and lighting device for carrying out the method

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Embodiment Construction

[0036] figure 1 Graph showing the dependence of the pulse-width modulated current I normalized to the nominal current In=1 through an LED or LEDs (not shown) and the time t in arbitrary time units , more precisely for relatively slow current sources. The PWM period or period duration T of an individual current pulse P is here about 10 time units. The period duration T can in particular be between 0.5 ms and 10 ms. Both the on-time t1 and the off-time t2 (=T-t1) of the current pulse P have a desired value of exactly 5 time units, so that the desired pulse duty ratio t1 / T or t1 corresponds to the desired dimming degree / (t1+t2) is ideally 50%.

[0037] However, due to the non-negligible (rising) time constant t_PSU of the current source, here 0.5 time units, the actual (actual) dimming degree is only 46%, which corresponds to a relative error of approximately 8%. Therefore, the dimming degree is reduced by about 4% due to the inertia of the current source.

[0038] figure...

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Abstract

A method for driving at least one light-emitting diode (4a, 4b, 4c), wherein at least one light-emitting diode (4a, 4b, 4c) is driven at least in some areas by means of pulse density modulation, in which pulse density modulation The number (n_dim) of the same current pulses (p_red) is set within a preset interval duration (T) according to the expected value of the light energy, in particular the degree of dimming. The lighting device (1) is configured with at least one light-emitting diode (4a, 4b, 4c) and at least one driver (3a, 3b, 3c) for feeding the at least one light-emitting diode (4a, 4b, 4c), wherein the lighting device (1) Designed to implement the method.

Description

technical field [0001] The invention relates to a method for operating or supplying at least one light-emitting diode. The invention also relates to a lighting device having at least one light-emitting diode and at least one driver for supplying the at least one light-emitting diode. Background technique [0002] In order to adjust the brightness of a light-emitting diode (LED) over a wide range, variation of the LED current driving the LED (current level modulation) is inappropriate because the brightness of the LED at low and high currents can deviate from the An otherwise well-satisfied linear current / brightness ratio and, moreover, the LED can be damaged. LEDs are therefore usually driven by means of pulse width modulation (PWM), wherein the LEDs are driven with a constant current I for a preset on-duration t1 (also referred to as on-time) and thereafter for a preset During the off duration t2 (also referred to as off time), it is switched to non-energized. In this ca...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H05B33/08
Inventor 托比亚斯·弗罗斯特斯特凡·洛伦茨
Owner OSRAM GMBH
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