LED Current Splitter for Multi-Channel PWM Control

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Solution Overview

Problem

Existing multi-channel LED lighting devices face a decrease in control resolution of PWM signals as the number of channels increases, leading to potential errors in light flux and color due to voltage variations and interactions between channels.

Innovation Solution

A current splitter design with two in series connected LED circuits, each comprising three branches: a first branch with at least one LED, a second branch with an LED and a branch switch, and a third branch with a shunt switch, where the forward voltage of the second branch is lower than the first, allowing for eight channels to be created using four switches, thereby maintaining control resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the number of LED channels is increased to provide more color control, then the versatility of the lighting device is improved, but the control resolution of PWM signals decreases

Engineering Contradiction:

Improvenumber of LED channelsVSAvoidcontrol resolution of PWM signals

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent divides the LED circuit into multiple series-connected LED circuits, each containing parallel branches with different forward voltages. This segmentation allows the current splitter to distribute current more precisely across multiple channels, maintaining control resolution even as the total number of channels increases to eight or more.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes LED circuits with different forward voltage parameters (e.g., 3V, 3.3V, 3.6V) to create distinct current paths. By changing the voltage parameter across different branches, the system can precisely control current distribution to multiple channels without losing PWM control resolution, as each voltage level creates a natural current hierarchy.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If a fixed voltage source is used to power LED channels, then the ease of operation is improved, but the manufacturing precision of light flux and color point deteriorates due to voltage variations and channel interactions

Engineering Contradiction:

Improvepower source simplicityVSAvoidlight flux and color point accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces the fixed voltage source system with a current splitter-based system that uses series-connected LED circuits. This substitution eliminates the harmful effects of voltage variations and channel interactions while maintaining operational simplicity, as the current splitter actively manages current distribution based on the forward voltage characteristics of each LED branch.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If a current source with current splitter is used to maintain control resolution, then the manufacturing precision of light flux is improved, but the device complexity increases

Engineering Contradiction:

Improvelight flux control accuracyVSAvoidcurrent splitter architecture

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent designs the current splitter to serve multiple functions simultaneously: it distributes current to multiple channels, maintains control resolution, compensates for voltage variations, and eliminates channel interactions. By making the current splitter multi-functional, the patent reduces the need for additional separate components, thereby managing device complexity while achieving high manufacturing precision for light flux and color point control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 effectively increases the number of channels from four to eight, allowing for more precise control of light color and flux without the need for re-wiring, reducing the unwanted effects of decreased control resolution and voltage variations.

Implementation Method 1

a current splitter for splitting an LED current between a plurality of LED channels

Methodology Applied

Scientific EffectElectrical current flow: Conduction (electrical)

Implementation Method 2

wherein a forward voltage of said at least one LED in said second branch (B1.2, B2.2) is lower than a forward voltage of said at least one LED in said first branch (B1.1, B2.1)

Methodology Applied

Scientific EffectForward voltage difference: Diode

Data Source

PatentUS11997773B2Light emitting diode, LED, based current splitter for splitting an LED current between a plurality of LED channels as well as a multi-channel light emitting diode, LED, based lighting device

Publication Date: 2024.05.28 SIGNIFY HOLDING BV

AI summary

A Light Emitting Diode, LED, based current splitter for splitting an LED current between a plurality of LED channels, wherein said current splitter comprises at least two in series connected LED circuits, wherein each LED circuit comprises a first branch (B1.1, B2.1) comprising at least one LED, a second branch (B1.2, B2.2) connected in parallel over said first branch (B1.1, B2.1) and comprising at least one LED and a branch switch (W1, W3) connected in series with said at least one LED, wherein a forward voltage of said at least one LED in said second branch (B1.2, B2.2) is lower than a forward voltage of said at least one LED in said first branch (B1.1, B2.1) and a third branch (B1.3, B2.3) connected in parallel over said first and second branch (B1.2, B2.2) and comprising a shunt switch (W2, W4) for shunting said first branch (B1.1, B2.1) and said second branch (B1.2, B2.2).