LED Illuminator Feedback Control for Constant Optical Output
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Surveillance LED illuminator systems face significant challenges in maintaining consistent optical output due to variations in temperature, manufacturing tolerances, aging components, and environmental conditions, leading to reduced effectiveness and reliability over time.
Innovation Solution
A constant optical output system is developed using an array of LEDs with integrated photodetectors and a microcontroller-based feedback and compensation circuitry that adjusts electrical current to maintain optimal LED output, combined with efficient heatsinking and pulse width modulation to prevent overheating, ensuring consistent illumination across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LEDs are driven to maximum current limits to increase illuminator range and output, then illumination intensity is improved, but reliability and operational lifetime are reduced
Solution Approach 1:
The patent implements a feedback control system using photodetectors to monitor LED optical output and adjust drive current dynamically. This allows the system to maintain optimal illumination intensity while preventing operation at excessive current levels that would reduce reliability and lifetime. The feedback loop continuously adjusts the operating point to balance performance and longevity.
2Ease of operation
If LEDs are operated at fixed output currents, then ease of operation is improved, but optical output varies with temperature and manufacturing tolerances
Solution Approach 1:
The system uses photodetector feedback to continuously monitor actual optical output and dynamically adjust drive current to compensate for temperature variations and manufacturing tolerances. This maintains stable optical output without requiring manual intervention or complex calibration procedures.
Solution Approach 2:
The patent dynamically changes the drive current parameter based on temperature compensation data and photodetector feedback. By adjusting the electrical parameters in response to environmental conditions and component variations, the system maintains consistent optical output across different operating conditions.
3Duration of action of moving object
If operation continues without compensation for component aging, then duration of action is extended, but optical output degrades over time
Solution Approach 1:
The photodetector feedback system continuously monitors optical output throughout the LED lifetime and dynamically adjusts drive current to compensate for aging effects. This allows the system to maintain rated optical output indefinitely, effectively extending the useful operational duration beyond typical LED lifetime limitations.
Solution Approach 2:
The patent implements dynamic adjustment of drive current based on real-time photodetector feedback and temperature compensation. This dynamic operation allows the system to adapt to aging components and maintain consistent performance, transforming a static degradation process into a dynamically compensated system.
4Adaptability or versatility
If high ambient temperatures are present, then operational versatility is improved, but LED efficiency is reduced
Solution Approach 1:
The system dynamically changes the drive current parameter in response to temperature conditions. At higher ambient temperatures, the controller adjusts current levels to compensate for reduced LED efficiency, maintaining optimal optical output while adapting to the thermal environment.
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 solution guarantees 100% constant optical power over the operational lifetime, enhancing image quality and extending the system's lifespan by maintaining consistent illumination performance regardless of temperature, time, or environmental changes.
Implementation Method 1
a photodetector circuit provides a voltage signal proportional to an amount of light falling on a photosensor
Implementation Method 2
arrays of LEDs mounted on metal heatsinks
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention is an illuminator for CCTV surveillance and security applications that maintains constant optical output from an array of LEDs by employing output compensation, feedback and enhancement. This constant optical output illuminator system enables reliable long-duration low-light imaging and data capture for surveillance and security applications, via an array of LEDs, LED power supply circuitry, and output feedback and compensation circuitry in which a photodetector circuit provides a voltage signal proportional to an amount of light falling on a photosensor and the voltage signal is fed to a drive control circuit for electrical current to the LEDs to achieve a desired optical output as measured by a photosensor voltage setpoint across the photodetector circuit.