Illumination Intensity Control via Unit Pulse Current Switching
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Solution Overview
Problem
Current control systems for illumination devices struggle to independently manage average and instantaneous currents, affecting the intensity and color spectrum of light emitted, leading to limitations in adjustable illumination levels and potential flickering issues.
Innovation Solution
A method and apparatus that control average current by varying the number of unit pulses during a time interval, using a switching circuit and current source, allowing for independent control of illumination intensity and color spectrum through a programmable controller, which selectively enables and disables current flow to the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the average current is controlled by changing the instantaneous current, then the illumination intensity can be adjusted, but the color spectrum of the emitted light changes as well
Solution Approach 1:
The current control is segmented into multiple discrete current levels rather than continuous control. The system provides a first current level for a first time interval and a second current level for a second time interval, allowing independent control of intensity (through current level selection) and color spectrum (through temporal separation of intensity adjustment and color adjustment periods).
Solution Approach 2:
The patent implements periodic switching between different current levels over time intervals. By alternating between first and second current levels in periodic cycles, the system achieves independent control where intensity is adjusted through the timing and sequencing of current delivery rather than simultaneous current modification, preventing color spectrum changes during intensity transitions.
2Adaptability or versatility
If the instantaneous current is changed to control average current, then multiple illumination levels can be achieved, but flickering occurs in the illumination output
Solution Approach 1:
The patent maintains continuous illumination by ensuring that the sum of time intervals at different current levels equals the total period. The first time interval and second time interval are configured such that they continuously cover the entire period without gaps, eliminating dark periods or interruptions that would cause visible flickering while still enabling multiple illumination levels through current level variation.
Solution Approach 2:
The system changes the temporal parameters (time intervals) rather than the current magnitude alone to control average current. By adjusting the duration of first and second current levels within the period, the system achieves multiple illumination levels while maintaining continuous light output, as the total on-time remains sufficient to prevent flickering.
3Device complexity
If a simple current control method is used, then the device complexity is reduced, but the ability to independently control intensity and color spectrum is lost
Solution Approach 1:
The patent uses a single current source and switching circuit to achieve multiple functions: controlling both illumination intensity and color spectrum independently, as well as managing power consumption. By implementing temporal multiplexing of current levels, the system achieves multi-functionality without requiring separate control circuits for each parameter, thereby limiting the increase in device complexity.
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
Enables precise control of illumination intensity and reduces flickering by adjusting the duty cycle of current delivery, allowing for multiple intensity levels without altering the color spectrum, thereby optimizing brightness and power consumption.
Implementation Method 1
many light emitting diodes (LEDs) provide light at different wavelengths when driven at differing levels of instantaneous current
Data Source
AI summary
A method for controlling average current. The method enables control of average current independent of instantaneous current. The average current is controlled by changing the number of unit pulses provided during a time interval. The unit pulses are used to switch the delivery of current to the load.