Solid State Lighting Panel Control via Non-Spatial Firing Sequences

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Solution Overview

Problem

Solid state lighting panels with phosphor-based white LED backlights have a limited color rendering index, leading to unnatural color representation due to inadequate red light emission, and traditional PWM control methods result in power inefficiencies and electromagnetic interference.

Innovation Solution

A control system for solid state lighting panels that determines a non-spatially sequential firing order for multiple strings of light-emitting devices, using rule-based or random logic to selectively drive the strings at different times and phases based on their spatial relationship, reducing power spikes and improving display performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If PWM control method is used to control solid state lamps, then intensity and color mixing can be achieved, but power factor spikes and electromagnetic interference occur due to current rush

Engineering Contradiction:
Improveintensity and color mixing controlVSAvoidpower factor spikes and electromagnetic interference
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent divides the solid state lighting panel into multiple independently controllable strings or groups of lamps. Instead of controlling all lamps simultaneously through a single PWM cycle, the system segments the control into multiple phases, where each phase activates a specific subset of strings. This segmentation distributes the current rush over time, reducing peak power factor spikes and electromagnetic interference while maintaining effective intensity and color mixing control through coordinated phase activation.

Inventive Principle:
Principle #1Segmentation

2Illumination intensity

If all solid state lamps are fired simultaneously to achieve desired intensity, then lighting output is maximized, but power system performance deteriorates due to power factor spikes

Engineering Contradiction:
Improvelighting outputVSAvoidpower system performance
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent implements periodic action by cycling through multiple phases of lamp string activation. Instead of a single simultaneous firing, the system uses a sequence of periodic phases where different strings are activated in alternating cycles. Each phase contributes to the overall lighting output, but the periodic distribution prevents simultaneous current rushes that would damage power system performance. The cumulative effect of multiple phases achieves desired illumination intensity while maintaining power system reliability.

Inventive Principle:
Principle #19Periodic action

3Reliability

If sequentially firing strings independently to avoid power spikes, then power system performance improves, but display characteristics become undesirable

Engineering Contradiction:
Improvepower system performanceVSAvoiddisplay characteristics
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies local quality by differentiating the control strategy based on the spatial location and characteristics of individual string groups. Different phases are assigned to different spatial regions or groups of strings, with each phase optimized for specific local requirements. This allows the system to maintain good display characteristics in each local region while distributing the overall firing sequence to protect power system performance. The local optimization ensures that display quality is preserved even though firing is sequential rather than simultaneous.

Inventive Principle:
Principle #3Local quality

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 color rendering by ensuring even illumination across a broad spectrum and reduces power inefficiencies and electromagnetic interference by distributing the firing of light-emitting strings in a controlled, non-spatially sequential manner, resulting in improved display characteristics and energy efficiency.

Implementation Method 1

Typically, a solid state light emitting device generates light through the recombination of electronic carriers, i.e. electrons and holes, in a light emitting layer or region.

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

white LED lamps that include a blue-emitting LED coated with a wavelength conversion phosphor that converts some of the blue light emitted by the LED into yellow light

Methodology Applied
Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentEP2145507B1Systems and methods for controlling a solid state lighting panel
Publication Date: 2019.08.21 WOLFSPEED INC
  • EP2145507B1 patent drawingFigure 1
  • EP2145507B1 patent drawingFigure 2~3
  • EP2145507B1 patent drawingFigure 4~6

AI summary

Provided are systems and methods for controlling a solid state lighting panel (102). The system includes a controller (106) that provides control signals to current drivers (104) that are configured to provide current to multiple solid state lighting devices. The system also includes a sequence generator that generates a firing sequence for firing multiple strings of slid state lighting devices.