Portable Lighting Device Runtime Extension via Adaptive PWM Control
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Solution Overview
Problem
Higher power battery-operated lighting devices face significant challenges in extending battery life due to limited runtime, as existing technologies do not effectively conserve and prolong battery power efficiently.
Innovation Solution
A lighting apparatus with a controller that adjusts the drive signal based on the voltage of the power source, using pulse-width modulation (PWM) duty cycles and user-selectable luminance modes to regulate power supply to the lighting unit, including an 'Eco-mode' for conserving battery power by scaling down the drive signal when voltage thresholds are reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If higher power is supplied to the lighting unit to increase luminance output, then illumination intensity is improved, but battery runtime deteriorates
Solution Approach 1:
The controller dynamically adjusts the PWM duty cycle based on real-time battery voltage levels. When voltage drops below thresholds, the system automatically reduces power delivery to the lighting unit, transitioning from static high-power operation to adaptive dynamic control that matches power supply capacity with battery state
Solution Approach 2:
The system changes operational parameters by modifying the PWM duty cycle percentage based on voltage thresholds. Different duty cycle parameters are applied at different voltage levels, transforming the lighting output parameter in response to battery state changes
2Stability of the object's composition
If the drive signal is maintained at high levels to ensure consistent luminance, then illumination stability is improved, but power consumption increases
Solution Approach 1:
The controller continuously monitors battery voltage and uses this feedback to adjust the PWM duty cycle. This closed-loop feedback mechanism ensures luminance stability within available power constraints by automatically adapting output levels based on real-time battery state measurements
Solution Approach 2:
The system performs periodic voltage monitoring and adjusts the drive signal at predetermined intervals or voltage thresholds, creating a rhythmic control pattern that maintains luminance stability while periodically conserving energy based on battery state
3Power
If battery voltage drops below threshold levels, then available power decreases, but unadjusted drive signals cause output degradation
Solution Approach 1:
The controller proactively adjusts the PWM duty cycle before complete power failure occurs by monitoring voltage thresholds in advance. This preliminary adjustment prevents sudden output degradation by preparing the system for reduced power conditions before they fully manifest
Data Source
AI summary
A lighting apparatus is provided including a lighting unit arranged to emit light; a switching device disposed between a power source and the lighting unit; and a controller configured to set a drive signal based on a target luminance level of the lighting unit and control a switching operation of the switching device via a drive signal to regulate a supply of electric power from the power source to the lighting unit. The controller monitors a voltage of the power source and periodically adjusts the drive signal based on the voltage of the power source.