LED Driver Circuit Switched Converter Mode Adaptation
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) and white LEDs with photoluminescent materials exhibit spectral gaps or troughs in their emission spectra, which reduce the quality of color rendering and color rendering index.
Innovation Solution
A driving circuit with a switched converter that includes a choke, a switch controlled by a control circuitry, and the ability to adapt the clocking of the switch based on external or internal feedback signals to select among continuous, borderline, or discontinuous conduction modes, thereby optimizing the operating mode for improved color rendering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If RGB light emitting diodes or white light emitting diodes with photoluminescent material are used, then the light can cover a broad spectral range, but spectral gaps or troughs appear in the emission spectrum reducing color rendering quality
Solution Approach 1:
The patent segments the white LED light source into multiple color components (red, green, blue LEDs or phosphors) and independently controls each segment's emission intensity through separate current channels. This allows precise adjustment of each spectral component to fill gaps and optimize the overall spectrum for improved color rendering index while maintaining broad spectral coverage.
2Illumination intensity
If a colour conversion layer is used to convert shortwave light into longwave light, then the spectral range is extended, but a spectral gap appears between the LED chip spectrum and the converted spectrum
Solution Approach 1:
The patent introduces intermediate spectral components (additional phosphors or LEDs with wavelengths between the LED chip and the converted light) that act as mediators to bridge the spectral gap. These intermediaries fill the trough between the blue LED peak and the yellow/red phosphor emission, eliminating the spectral discontinuity and improving color rendering quality while maintaining the extended spectral range.
3Device complexity
If the switch clocking is fixed in a switched converter, then the circuit is simple, but the operating mode cannot be adapted to optimize color rendering
Solution Approach 1:
The patent implements dynamic control of the switched converter's switch clocking frequency and duty cycle based on real-time feedback from spectral sensors or color rendering monitors. The control circuit adjusts the operating mode (continuous, critical, or discontinuous conduction mode) and PWM dimming parameters to optimize the LED drive current waveform, thereby adapting the system to maximize color rendering index while maintaining reasonable circuit complexity through integrated control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the color rendering quality by adapting the operating mode of the switched converter, which minimizes spectral gaps and improves the color rendering index, achieving better color reproduction compared to conventional LED systems.
Implementation Method 1
a switched converter having a switch controlled by a control circuitry, wherein a choke is charged when the control circuitry control the switch in its conducting state and the choke is de-charged when the control circuits controls the switch in its non-conducting state
Implementation Method 2
These are light emitting diodes which are combined with photoluminescent material (fluorescence stain, luminescent material). The light from the LED chip in a first spectrum is partially converted into a second spectrum by the phosphorous layer or colour conversion layer formed thereby.
Data Source
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AI summary
The invention proposes a driving circuit for provision of an operating current for at least one lighting means, such as e.g. a light emitting diode, the driving circuit comprising a switched converter (130) having a switch (SI) controlled by a control circuitry, wherein a choke (LI) is charged when the control circuitry control the switch in its conducting state and the choke is de- charged when the control circuits controls the switch in its non-conducting state, wherein by supplying an external signal or an internal feedback signal to the control circuitry, the control circuitry is designed to adapt the clocking of the switch in order to adapt the operating mode of the switched converter, to either of a continuous, borderline (transition, critical) and discontinuous conduction mode, CCM, BCM or DCM.