LED Switching Controller for Uniform Luminance
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Solution Overview
Problem
Existing LED-switching controllers face challenges in efficiently driving multiple parallel-connected LEDs to achieve uniform luminance, as they often require excessively high voltages, leading to decreased efficiency and potential failure in switching on all LEDs due to varying forward voltages.
Innovation Solution
An LED-switching controller that measures voltages across signal lines connected to LEDs, identifies the minimum voltage excluding disconnected terminals, and controls the boosting circuit to maintain a constant-current operation, ensuring all LEDs receive the necessary voltage for uniform luminance, while excluding disconnected terminals to prevent malfunction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage necessary for driving all LEDs is applied to ensure all LEDs switch on, then reliability is improved, but energy consumption increases and boosting circuit efficiency decreases
Solution Approach 1:
The patent dynamically adjusts the reference voltage parameter based on the actual forward voltage characteristics of connected LEDs. By measuring the voltage across parallel-connected LEDs and adapting the reference voltage accordingly, the system ensures all LEDs switch on reliably while avoiding the excessive voltage that would waste energy and reduce boosting circuit efficiency.
2Reliability
If a high voltage is applied to drive LEDs in current control mode, then all LEDs can be switched on, but the boosting circuit efficiency decreases
Solution Approach 1:
The patent implements a feedback mechanism where the voltage across parallel-connected LEDs is measured and used to adjust the reference voltage for the constant current circuit. This closed-loop control ensures that the boosting circuit operates at optimal efficiency while still providing sufficient voltage to switch on all LEDs reliably.
3Reliability
If the reference voltage is determined considering different forward voltages of individual LEDs, then all LEDs can be driven uniformly, but the reference voltage becomes excessively high
Solution Approach 1:
The patent applies partial action by determining the reference voltage based on the actual needs of the connected LEDs rather than assuming the worst-case scenario for all LEDs. By measuring the voltage across the parallel-connected LEDs and setting the reference voltage accordingly, the system achieves uniform luminance without requiring an excessively high reference voltage that would waste energy.
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 allows for efficient voltage distribution to ensure all LEDs operate within a narrow luminance range, preventing any LED from being switched off and maintaining high boosting circuit efficiency.
Implementation Method 1
a boosting circuit for switching on the LEDs... controlling a boosting circuit so that the signal line at the minimum voltage is set at a voltage that enables a constant-current circuit to perform a constant-current operation
Implementation Method 2
driving the plurality of LEDs by a constant-current circuit in a current control mode... enables a constant-current circuit to perform a constant-current operation
Data Source
AI summary
An LED terminal monitoring circuit detects an LED at the lowest potential among a plurality of parallel-connected LEDs. An analog signal selecting circuit gives a signal indicating the voltage of the detected LED to a boosting circuit. The boosting circuit performs a boosting operation on the basis of the condition of the detected LED at the lowest voltage and, consequently, a voltage sufficient for driving the LEDs in a current-control mode can be applied to all the LEDs. Signal lines not connected to LEDs are excluded from objects of a LED-switching control operation.