LED Control System Using Segmented Unit Current Sources
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Solution Overview
Problem
Existing LED control systems face challenges in efficiently regulating current and minimizing power consumption while accommodating various design constraints and user settings, particularly in portable electronic devices, where dimming control is necessary to preserve battery life.
Innovation Solution
A digital LED control system that utilizes a plurality of unit current sources arranged in a two-dimensional array, selectively activated based on a current magnitude signal, providing a given unit current through LEDs and interpolative feedback to regulate control voltage, maintaining a constant reference current and minimizing dropout voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional current control methods are used for LED dimming, then power consumption can be reduced, but current regulation precision and stability deteriorate
Solution Approach 1:
The current source is divided into multiple unit current sources (e.g., 32 units) that can be independently controlled. Each unit current source provides a precise baseline current, and by selectively activating specific units based on dimming requirements, the system achieves both power savings and maintained regulation precision. The segmentation allows fine-grained control while keeping active components minimal.
Solution Approach 2:
The patent implements a feedback mechanism where the output current of each unit current source is monitored and fed back to a control system. This feedback enables real-time adjustment and compensation, ensuring that even when some units are deactivated for power saving, the remaining active units maintain precise current regulation through dynamic control adjustments.
2Adaptability or versatility
If multiple current control settings are implemented for dimming control, then adaptability to user settings is improved, but device complexity increases
Solution Approach 1:
The current control system is segmented into multiple independently controllable unit current sources, each capable of being activated or deactivated. This segmentation provides natural granularity for dimming levels without requiring complex analog control circuits. The digital controllability of each segment simplifies the overall control architecture while enabling versatile dimming settings.
Solution Approach 2:
The system dynamically adjusts which unit current sources are active based on the required dimming level. Rather than having fixed control circuits for each dimming level, the system dynamically configures the active current paths, allowing flexible adaptation to user settings while maintaining a relatively simple static circuit structure.
3Measurement precision
If current regulation accuracy is maintained across various settings, then measurement precision is improved, but power consumption increases
Solution Approach 1:
By segmenting the current source into multiple units, the system can activate only the necessary number of units to achieve the desired current level. This maintains regulation accuracy for the active units while minimizing total power consumption by keeping inactive units completely off rather than running at reduced levels.
Solution Approach 2:
The system changes the operational parameters by selectively enabling or disabling specific unit current sources based on the required current magnitude. This parameter change approach allows the system to maintain high regulation accuracy for the active subset while adjusting the overall power consumption by controlling the number of active units rather than operating all units at variable efficiency points.
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 enables precise current regulation, reduces power consumption, and simplifies the control scheme, mitigating drift errors and amplifier offsets, while allowing for cost-effective implementation and effective dimming control in portable electronic devices.
Implementation Method 1
an LED driver system configured to regulate a control voltage based on a substantially constant reference current and a feedback voltage at a feedback node
Implementation Method 2
each provide the feedback voltage as an interpolative feedback to the feedback node based on the unit current. The reference resistor and the sense resistor of each of the plurality of unit current sources can have relative resistance magnitudes that are proportional
Implementation Method 3
Light-emitting diodes (LEDs) are implemented for a variety of purposes in electronic device applications
Data Source
AI summary
One embodiment includes a light-emitting diode (LED) control system. The system includes an LED driver system configured to regulate a control voltage based on a substantially constant reference current and a feedback voltage at a feedback node. The system also includes a digital current source system comprising a plurality of unit current sources that are each coupled to an LED. The plurality of unit current sources can be selectively activated to each provide a given unit current through the LED and to each provide the feedback voltage as an interpolative feedback to the feedback node based on the unit current. The system further includes a current magnitude controller configured to selectively activate the plurality of unit current sources in response to a current magnitude signal.