Alternating LED Filament for Uniform Color Mixing

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Solution Overview

Problem

Color mixing in color temperature tunable LED filaments is inadequate, and they may appear broken upon malfunctioning.

Innovation Solution

An LED filament with LEDs arranged in alternating intersecting configurations across multiple columns, each emitting different color temperatures, allowing for improved color mixing and tunability, with independently controllable subsets and varying segment lengths and distances for enhanced appearance and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If LEDs are arranged in single column or grouped configuration, then manufacturing is simpler, but color mixing is inadequate

Engineering Contradiction:
Improvecolor mixing qualityVSAvoidLED arrangement complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The LED array is divided into multiple columns (at least two) with different color temperature groups arranged alternately. This segmentation allows better spatial distribution of different color temperatures, improving color mixing quality while maintaining manageable complexity through systematic arrangement patterns.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different local regions (columns) of the LED array are assigned different color temperature characteristics. By creating local variations in color temperature distribution across multiple columns, the patent achieves superior overall color mixing while each column maintains a relatively simple internal structure.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If LEDs are arranged in alternating intersecting configuration, then color mixing is improved, but device complexity increases

Engineering Contradiction:
Improvecolor mixing qualityVSAvoidLED arrangement complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The alternating intersecting configuration segments the LED array into distinct columns with alternating color temperature groups. This segmentation creates a predictable pattern that improves color mixing while the systematic nature of the alternation prevents excessive complexity from developing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-dimensional or simple two-dimensional arrangement to a multi-dimensional alternating intersecting configuration. By organizing LEDs in multiple columns with alternating patterns, the patent adds spatial dimensions to the arrangement, improving color mixing coverage while the regular pattern maintains manufacturing feasibility.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If all LEDs emit same color temperature, then control is simpler, but color temperature tunability is limited

Engineering Contradiction:
Improvecolor temperature tunabilityVSAvoidcontrol complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The LED array is segmented into multiple independent controllable groups, each emitting different color temperatures. This segmentation enables color temperature tuning by selectively activating different groups, achieving versatility while keeping each group's control logic relatively simple and modular.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system enables dynamic color temperature adjustment by allowing different segments (columns or groups) to be independently controlled. This dynamic capability provides color temperature tunability while the modular segment structure keeps control complexity manageable through independent segment management.

Inventive Principle:
Principle #15Dynamics

4Reliability

If LEDs are arranged in traditional configuration, then appearance is simpler, but broken appearance on malfunction is more likely

Engineering Contradiction:
Improveappearance reliability during malfunctionVSAvoidconfiguration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The LED array is organized into multiple columns with alternating color temperature groups, creating a segmented structure. This segmentation ensures that if some LEDs fail, the alternating pattern and multiple columns provide visual redundancy, preventing a broken appearance while the systematic structure maintains configuration manageability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses parameter changes (alternating color temperature groups in multiple columns) to create a configuration where visual continuity is maintained during partial failures. The alternating pattern and multi-column structure provide parameter-based redundancy that masks individual LED failures, improving appearance reliability without requiring complex active monitoring systems.

Inventive Principle:
Principle #35Parameter changes

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 achieves improved color mixing and tunability, ensuring a uniform appearance and reduced likelihood of the filament appearing broken during malfunctions.

Implementation Method 1

The first subset of LEDs emitting light of the first color temperature and the second subset of LEDs emitting light of the second color temperature may be provided by depositing different color temperature emitting phosphors on different subsets of LEDs.

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentEP4146979B1An LED filament and a lamp
Publication Date: 2023.08.30 SIGNIFY HOLDING BV
  • EP4146979B1 patent drawingFigure 1~2
  • EP4146979B1 patent drawingFigure 3~4
  • EP4146979B1 patent drawingFigure 5a~5b

AI summary

The present invention relates to an LED filament (100) comprising a carrier (110) comprising a plurality of LEDs (140) arranged in at least two columns of LEDs (150, 160). The plurality of LEDs (140) are grouped into at least two different subsets of LEDs (120, 130), wherein a first subset of the LEDs (120) is configured to emit light of a first color temperature, CT1, and a second subset of the LEDs (130) is configured to emit light of a second color temperature, CT2, CT2 being different from CT1. The LEDs (140) of the at least two different subsets of LEDs (120, 130) are arranged in an alternating intersecting configuration in the at least two columns of LEDs (150, 160) such that each column (150) comprises alternating segments (132, 124) configured to emit light of the first and the second color temperatures, respectively.