Diode Array Optical Feedback for Luminous Homogeneity
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Solution Overview
Problem
Diode arrays face issues with inhomogeneous luminous images due to mismatches between current sources and LEDs, as well as temperature differences, which existing regulated current sources cannot effectively compensate.
Innovation Solution
The solution involves a diode array arrangement where each LED is associated with a sensor element to detect luminous flux, and a control unit adjusts the current based on optical feedback, ensuring all LEDs emit the same light output, thereby counteracting mismatches and temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If regulated current sources with feedback are used to control LED current, then current precision is improved, but temperature differences between LEDs cannot be compensated and inhomogeneous luminous image occurs
Solution Approach 1:
The patent implements optical feedback by detecting the actual luminous flux of each LED using a sensor element and using this detection to adjust the drive current dynamically. This closes the control loop from optical output back to electrical input, allowing real-time compensation for temperature drift and LED aging, thus maintaining luminous image homogeneity despite the limitations of regulated current sources
Solution Approach 2:
The patent replaces electrical feedback control with optical feedback control. Instead of relying solely on electrical current regulation, the system uses optical detection (photodetection) to sense the actual light output and converts this optical information back into electrical control signals, substituting the control domain from purely electrical to optical-electrical hybrid
2Measurement precision
If high-precision regulated current sources are used for each LED, then current control accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the LED and its control circuitry into an integrated structure where the sensor element, control unit, and LED are combined in a single module. This integration reduces the overall system complexity by eliminating separate external control circuits while maintaining high current control accuracy through the integrated optical feedback mechanism
3Measurement precision
If optical feedback with sensor elements is implemented for each LED, then luminous flux detection precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent places the sensor element in immediate spatial proximity to the LED, with the sensor optically coupled to the LED in a nested configuration where the sensor is positioned within or adjacent to the LED housing. This nesting allows the sensor to detect the LED's luminous flux directly without requiring separate external optical paths, simplifying assembly while maintaining detection precision
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 results in a more homogeneous luminous image without the need for complex calibration or regulated current sources, achieving precise control of LED brightness and reducing the impact of temperature variations.
Implementation Method 1
each LED is associated with a respective sensor element which is configured to detect a characteristic value representative of a luminous flux of the respective LED
Data Source
AI summary
An arrangement for operating a diode array includes a plurality of LEDs. Each LED is assigned a respective sensor element which is configured to detect a characteristic value representative of a luminous flux of the respective LED. The arrangement also includes a respective supply input for providing a current for light-emitting operation of the respective LED. The arrangement further includes in each case a control unit which is coupled on the input side to the respective supply input and the respective sensor element and on the output side to the respective LED and is configured to control the current for light-emitting operation of the respective LED as a function of the corresponding characteristic value. The arrangement additionally includes a respective supply input for providing a current for light-emitting operation of the respective LED.