LED Current Control Circuit for Temperature-Dependent Luminous Flux Compensation

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing LED light control circuits do not effectively account for the temperature-dependent decrease in luminous flux, leading to increased energy consumption and potential glare at colder temperatures, and can cause overheating due to constant current supply.

Innovation Solution

A circuit that adjusts the electrical current supplied to LEDs based on temperature, providing a lower current in lower temperature intervals and a constant current in higher intervals to compensate for luminous flux changes and prevent overheating, while allowing for energy-saving operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If constant current is supplied to LED, then LED operates reliably, but energy consumption increases and luminous flux becomes excessive at low temperatures

Engineering Contradiction:
ImproveLED operational reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by transitioning from constant current supply to temperature-dependent variable current supply. The control circuit dynamically adjusts the LED current based on real-time temperature measurements, reducing current at low temperatures and maintaining it at high temperatures, thereby optimizing energy consumption while preserving LED reliability across different operating conditions

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the electrical current parameter as a function of temperature. The control circuit changes the current magnitude based on temperature thresholds, creating a piecewise current profile that adapts to thermal conditions. This parameter adaptation resolves the contradiction by allowing current to vary within safe operating limits while minimizing energy waste

Inventive Principle:
Principle #35Parameter changes

2Use of energy by moving object

If current is reduced at low temperatures to save energy, then luminous flux is optimized, but LED may overheat at high temperatures without compensation

Engineering Contradiction:
Improveenergy consumptionVSAvoidLED operating temperature
Core Design Contradiction:
Use of energy by moving objectVSTemperature

Solution Approach 1:

The patent employs feedback through a temperature sensor that continuously monitors LED temperature and feeds this information to the control circuit. The control circuit uses this feedback to adjust the current supply in real-time, reducing current when temperature is low and maintaining or reducing it when temperature is high, thereby preventing overheating while optimizing energy consumption across the full temperature range

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system implements self-service by using the LED's own temperature characteristics to control its operating parameters. The temperature sensor mounted on the LED housing provides self-diagnosis of thermal conditions, and the control circuit automatically adjusts current without external intervention, enabling the LED system to self-regulate its thermal and electrical operating points

Inventive Principle:
Principle #25Self-service

3Illumination intensity

If temperature compensation is implemented, then luminous flux is maintained constant, but device complexity increases

Engineering Contradiction:
Improveluminous fluxVSAvoidcontrol circuit complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the temperature range into discrete intervals with defined current characteristics. The control circuit implements piecewise linear compensation by segmenting the temperature-current relationship into multiple linear segments, each valid within a specific temperature range. This segmentation approach maintains luminous flux constancy while keeping the control logic relatively simple through modular temperature range handling

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses an intermediary approach by introducing a control circuit as a mediator between the temperature sensor and the LED current supply. This intermediary circuit processes temperature information and translates it into appropriate current adjustments, implementing temperature compensation without requiring direct complex interaction between sensor and LED driver, thereby managing system complexity through functional decomposition

Inventive Principle:
Principle #24Intermediary (Mediator)

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 circuit reduces energy consumption and prolongs LED lifespan by adjusting current supply according to temperature, maintaining optimal luminous flux and preventing thermal damage.

Implementation Method 1

The received temperature signal can, for example, correspond to a temperature detected by a temperature sensor, in particular the temperature of an LED or the ambient temperature of the light fixture

Methodology Applied
Scientific EffectTemperature sensing:

Implementation Method 2

The circuit uses the received temperature signal to provide an electrical current at the supply output such that there is a first, lower temperature interval and a second, higher temperature interval, with the circuit providing a lower current when the temperature is in the first temperature interval than when it is in the second

Methodology Applied
Scientific EffectTemperature-dependent electrical current adjustment:

Implementation Method 3

The invention relates to a circuit for controlling a light, in particular an outdoor light, a headlight, a light for cold storage rooms or a vehicle light, with at least one LED as the light source

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP2355621B1Temperature compensation of luminous flux of LED lights
Publication Date: 2020.04.01 SITECO GMBH
  • EP2355621B1 patent drawingFigure 1a
  • EP2355621B1 patent drawingFigure 1b
  • EP2355621B1 patent drawingFigure 1c

AI summary

The invention relates to a circuit for supplying power to a lamp with at least one LED as a light source, wherein the circuit has a signal input for receiving a temperature signal and an electrical supply output or a control signal output for controlling an electrical supply device with a supply output, wherein the supply output provides an electrical current to supply the LED of the lamp, and wherein the temperature signal corresponds to a temperature, wherein a first, lower temperature interval and a second, higher temperature interval exist, such that the circuit provides a lower current when the temperature is in the first temperature interval than when the temperature is in the second temperature interval.