Digital Current Regulator for Solid State Lighting
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Solution Overview
Problem
Existing LED drivers for portable devices, such as cameras and mobile telephones, have low efficiency due to their analog nature and requirement for external loop compensation, leading to excessive power consumption and complex designs with many components.
Innovation Solution
A digital current regulator that provides multiple modes of operation for solid-state lighting, eliminating resistive impedances in the current path to LEDs, using a control circuit with memory to modulate energizing cycle time periods based on predetermined average current parameters, and comprising an inductor, switch, current sensor, and comparators to manage power efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog current control is used with external loop compensation, then current regulation is achieved, but device complexity increases and efficiency decreases
Solution Approach 1:
The patent combines multiple functions into a single integrated controller chip that includes the control circuit, memory for storing current parameters, and switching elements. This integration eliminates the need for external loop compensation components and reduces the overall component count while maintaining reliable current regulation through digital control algorithms.
Solution Approach 2:
The patent replaces analog current control mechanisms with a digital control system. The controller uses digital-to-analog conversion and pulse-width modulation (PWM) to regulate current, eliminating the need for external analog compensation circuits and reducing device complexity while improving efficiency.
2Reliability
If resistive impedances are used for current control, then current limiting is achieved, but power dissipation increases
Solution Approach 1:
The patent replaces resistive current limiting with active digital control using PWM switching. The controller regulates current by switching the power supply on and off at controlled duty cycles, eliminating the need for power-dissipating current-limiting resistors and significantly reducing energy loss.
3Adaptability or versatility
If multiple operating modes are implemented with selectable resistors, then mode switching is achieved, but device complexity and power dissipation increase
Solution Approach 1:
The patent implements multiple operating modes through dynamic digital control parameters stored in memory within the controller. Different current levels and PWM duty cycles are programmed into the controller to achieve various lighting modes (flash, continuous, dimming), eliminating the need for physical resistor switching and reducing component count.
4Illumination intensity
If high current is supplied through resistors for flash mode, then flash intensity is achieved, but power consumption increases
Solution Approach 1:
The patent uses pulse-width modulation (PWM) to deliver high current to LEDs in short controlled pulses for flash mode. By switching the power supply on and off at high frequency with controlled duty cycles, the system achieves high peak currents for intense flash illumination while maintaining low average power consumption, eliminating the need for continuous high current through resistors.
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
The solution achieves significantly lower power losses, increased efficiency, reduced component count, and longer battery life in portable devices by providing digital control without external compensation, enabling multiple operating modes for LEDs.
Implementation Method 1
an inductor coupled to the DC power supply and coupled to the solid state lighting
Implementation Method 2
a switch coupled to the inductor and to the control circuit
Data Source
AI summary
A representative apparatus embodiment provides a plurality of operating modes for solid state lighting, such as a flash mode and a constant or background lighting mode for use with devices such as cameras. A representative apparatus comprises a memory adapted to store a plurality of average current parameters; and a controller adapted to modulate an energizing cycle time period (“T”) for providing power to the solid state lighting as proportional to the product of the selected average current parameter (“a”) and a reset time period (“TR”) for an inductor current to return to a substantially zero level from a predetermined peak level (T∝a·TR). The average current parameter is predetermined as substantially proportional to a ratio of a peak inductor current level (“IP”) to an average output D.C. current level (“IO”)(a∝IPIO).