Analog LED Dimming Circuit for Incandescent Color Shift

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Solution Overview

Problem

Existing LED lighting systems struggle to replicate the dimming characteristics of incandescent bulbs, as they do not change color temperature when dimmed, leading to an unnatural bluish light, and require complex and costly digital components for color mixing.

Innovation Solution

An analog-based dimmable LED lighting system using all-analog components and modules that respond to a common dimming signal to control LED current, mimicking the color temperature shift of incandescent bulbs by varying the correlated color temperature and intensity, achieved through analog drive circuitry and rectification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If traditional LED systems are used for dimming, then energy efficiency is improved, but color temperature stability deteriorates (light becomes bluish when dimmed)

Engineering Contradiction:

Improveenergy efficiencyVSAvoidcolor temperature stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The LED system is segmented into multiple LED types with different color temperatures (e.g., warm white LEDs at 2700K and cool white LEDs at 6504K). Each segment is independently controllable through separate analog dimming circuits, allowing the system to maintain stable color temperature by adjusting the proportion of each LED type activated during dimming operations.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If multiple separate drivers are used to control different colored LEDs, then color mixing capability is improved, but device complexity increases

Engineering Contradiction:

Improvecolor mixing capabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple LED types with different color temperatures are merged into a single lighting module or fixture, sharing common analog dimming control circuitry. The analog dimming signals are applied to each LED type through simple resistive divider networks or potentiometers, eliminating the need for complex digital controllers while maintaining color mixing capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

A single analog dimming control system is designed to universally control multiple LED types with different color temperatures. The universal analog control circuit can adjust the intensity of each LED type proportionally, providing both dimming and color temperature adjustment functions through one unified control interface.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If digital components are used for LED control, then control precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improvecontrol precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The system replaces expensive digital control components with inexpensive analog components such as potentiometers, resistors, and simple voltage dividers. These cheap analog components provide sufficient control precision for residential lighting applications, significantly reducing manufacturing costs while maintaining adequate dimming linearity and color temperature control.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

Digital electronic control systems are replaced with analog electrical control systems using continuous voltage or current signals. The analog dimming circuits use passive components like resistors and potentiometers to control LED current, eliminating the need for microcontrollers, digital-to-analog converters, and other expensive digital components while maintaining smooth dimming operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 system provides a cost-effective solution for simulating incandescent-style dimming with LED lighting, offering a wide range of control over light properties like intensity and color rendering index, while maintaining a natural color temperature shift, using simple and reliable analog components.

Implementation Method 1

The analog drive circuitry can also include an analog rectifier bridge if the common dimming signal is an AC voltage. For example, in operation, the analog rectifier bridge converts the AC voltage of the common dimming signal to a DC voltage

Methodology Applied

Scientific EffectRectification:

Data Source

PatentUS9756694B2Analog circuit for color change dimming

Publication Date: 2017.09.05 ABL IP HLDG LLC

AI summary

An analog-based dimmable LED lighting system includes a plurality of LED lighting modules, which emit light at different correlated color temperature (CCT) ranges. Each of the LED lighting modules is powered by a common dimming signal in the form of an AC voltage which corresponds to a dimming level in a dimming region. Each of the LED lighting modules includes an LED, an analog rectifier bridge to convert the AC voltage of the common dimming signal to a DC voltage, and an analog current limiter connected between the rectifier and the LED to control current through the LED according to the common dimming signal. The LED(s) in the different lighting modules are controlled, via respective analog current limiter, to produce a resultant light at a selected CCT and light intensity according to the common dimming signal.