LED Driver Circuit Color Temperature Scale Factor Control

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Solution Overview

Problem

Existing light fixtures struggle to maintain a desired color temperature at varying light intensities, as color temperature changes significantly with intensity modifications, affecting the output quality.

Innovation Solution

A system comprising a light fixture with an array of LED light sources, a driver circuit, and a controller that uses a color temperature scale factor to adjust the current driven to the light sources, allowing for precise control of color temperature and intensity, enabling the production of a desired color temperature at any light intensity level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the light intensity of LED light sources is modified, then the light output intensity changes, but the color temperature of the light source changes significantly

Engineering Contradiction:

Improvelight intensityVSAvoidcolor temperature

Core Design Contradiction:

Illumination intensityVSTemperature

Solution Approach 1:

The patent applies parameter changes by modifying the electrical parameters (current and pulse width modulation duty cycle) of the LED light sources in a coordinated manner. By changing both the current and PWM duty cycle together according to calculated scale factors, the system achieves intensity modification while compensating for color temperature shifts, thus resolving the contradiction between maintaining constant color temperature and varying light intensity.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the current driven to light sources is adjusted to change intensity, then light output changes, but color temperature control precision deteriorates

Engineering Contradiction:

Improvelight output controlVSAvoidcolor temperature control precision

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system implements feedback by continuously monitoring the actual color temperature and light intensity output, comparing these values against desired target values, and then calculating corrective scale factors for current and PWM duty cycle adjustments. This closed-loop feedback mechanism enables precise color temperature control while maintaining flexible intensity adjustment capability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary action by pre-calculating scale factors for current and PWM duty cycle based on desired intensity levels before actually driving the LEDs. These pre-calculated parameters ensure that when intensity changes are made, the corresponding color temperature compensation is already built into the control signals, preventing color temperature drift before it occurs.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If a single control parameter is used to adjust light intensity, then the control system remains simple, but the ability to maintain desired color temperature at varying intensities is lost

Engineering Contradiction:

Improvecontrol system complexityVSAvoidcolor temperature stability

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The system applies dynamics by implementing adaptive, intensity-dependent control parameters. Rather than using fixed control relationships, the patent dynamically adjusts both current and PWM duty cycle based on the desired intensity level, with each intensity level having optimized scale factors. This dynamic approach maintains color temperature stability across the full intensity range while keeping the control system structure relatively simple through systematic parameter calculation.

Inventive Principle:

Principle #15Dynamics

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

Enables consistent color temperature output across different intensity levels, ensuring high-quality light fixture performance by modifying the current based on the color temperature scale factor, thereby maintaining the desired color temperature regardless of intensity changes.

Implementation Method 1

The light fixture includes an array of light-emitting diode ("LED") light sources

Methodology Applied

Scientific EffectLight-emitting diode electroluminescence: Light Emitting Diode

Implementation Method 2

The array of LED light sources corresponds to a color channel of the light fixture

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11252794B2Systems, devices, and methods for controlling an LED light source based on a color temperature scale factor

Publication Date: 2022.02.15 ELECTRONIC THEATRE CONTROLS INC

AI summary

A light fixture is configured to produce an output via a driver circuit to drive an array of LED light sources. Controlling the light fixture includes receiving a first light intensity value related to a light intensity value for the array of LED light sources, determining a first dimming curve based on the first light intensity value and a color temperature value to determine a first value, receiving a second light intensity value related to a light intensity value for the array of LED light sources at which the color temperature value for the output of the light fixture is achieved, wherein the second light intensity value is different than the first light intensity value, determining a second dimming curve based on the second light intensity value and the color temperature value to determine a second value, wherein the second dimming curve is different than the first dimming curve.