LED Driver Circuit Using Temperature-Based Aging Compensation
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Solution Overview
Problem
Existing LED light sources experience a decline in light output over their service life due to aging, leading to inefficiencies and inaccuracies in maintaining consistent lighting, as current methods either oversize the light source, rely on complex sensors, or use inaccurate statistical models.
Innovation Solution
A method and circuit arrangement that determine the proportion of electrical power converted into light and heat using temperature measurements, calculating a compensation factor to adjust power supply and maintain constant light output, accounting for efficiency and temperature-dependent factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If no compensation is carried out when driving LEDs, then the light output has a surplus when first put into operation, but the light output drops to a value below the desired lighting at the end of service life
Solution Approach 1:
The patent changes the operating parameters of the LED by adjusting the drive current based on temperature measurements. A correlation factor is calculated that relates temperature to light output, and this factor is used to dynamically adjust the drive current to compensate for aging effects and maintain consistent illumination.
Solution Approach 2:
The patent implements a feedback mechanism where temperature is measured during LED operation, the correlation factor is calculated from these measurements, and the drive current is adjusted based on this calculated factor. This closed-loop control ensures consistent light output throughout the LED's service life.
2Reliability
If luminaires use sensors to detect light emission and control light sources, then constant light emission is achieved, but the system becomes complex due to the sensor and required optical system
Solution Approach 1:
The patent replaces the mechanical/optical sensor system with an electrical measurement and calculation approach. Instead of using physical sensors to detect light emission, the system uses temperature measurements and electrical parameter calculations to determine and adjust the drive current, achieving the same goal with simpler electronics.
Solution Approach 2:
The patent introduces temperature as an intermediary parameter that correlates with light output. By measuring temperature and using it to calculate the correlation factor, the system indirectly controls light emission without requiring direct light sensors, thus simplifying the overall system architecture.
3Reliability
If brightness sensor is used to maintain constant light output, then light emission is controlled, but the sensor itself is subject to signs of aging and accuracy cannot be guaranteed
Solution Approach 1:
The patent extracts the measurement function from the light path by using temperature measurement instead of light detection. This removes the brightness sensor from the system entirely, eliminating its aging problems while maintaining the ability to control and maintain constant light output through electrical parameter adjustment.
4Reliability
If theoretical models are used to determine brightness decrease, then light sources are operated with increased power, but many factors influencing aging cannot be taken into account leading to inaccuracy
Solution Approach 1:
The patent changes from using fixed theoretical models to using dynamically calculated parameters based on actual operating conditions. The correlation factor is calculated from real-time temperature measurements, allowing the system to adapt to actual aging characteristics and environmental conditions, thereby improving compensation accuracy.
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
This approach efficiently compensates for LED aging, ensuring precise and consistent light output over the entire service life with minimal additional measures and reasonable costs, while accounting for temperature-dependent light output.
Implementation Method 1
the proportion of the electrical power (P out) supplied to the LED light source during operation is converted into light (P light)
Implementation Method 2
on the basis of temperature measurements it is determined what proportion of the electrical power (P out) supplied to the LED light source during operation is converted into light (P light)
Data Source
Figure 1
AI summary
The invention relates to a method for operating an LED light source (1), wherein the portion of the electrical power (Pout) fed to the LED light source (1) during the operation that is converted into light (Plight) is determined on the basis of temperature measurements. On the basis thereof, a compensation factor (KAGE COMPENSATION) that compensates the aging of the LED light source (1) can be determined, wherein a correlation factor (F) that was determined at the start of the putting into service of the lamp (100) is taken into account in order to determine the portion of the electrical power converted into light (Plight).