LED Driver Circuit Overcurrent Protection via Voltage Feedback
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Solution Overview
Problem
Conventional LED driving circuits can lead to overheating and potential fires when LEDs deteriorate or age, causing an increase in current through voltage divider resistors due to short-circuits.
Innovation Solution
An apparatus comprising a serially connected LED unit, a rated current providing unit, a voltage dividing unit, and a voltage measuring unit, with a controller that adjusts current based on measured voltage to prevent overcurrent and maintain rated conditions, utilizing a Positive Temperature Coefficient (PTC) thermistor to manage temperature-induced resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage divider resistors are serially connected to multiple LEDs to apply rated voltage and current, then the LEDs can operate at rated conditions, but when some LEDs short-circuit due to deterioration or aging, the current increases causing overheating and potential damage or fire
Solution Approach 1:
The patent implements a feedback control mechanism where a microcontroller continuously monitors the voltage across each LED and adjusts the current through PWM control. When an LED's voltage deviates from the expected value (indicating short-circuit or deterioration), the system automatically reduces or cuts off current to that LED, preventing overheating and fire hazards while maintaining stable operation of healthy LEDs
Solution Approach 2:
The patent introduces constant current diodes (CCD) as intermediary components connected in parallel with each LED. These CCDs act as protective mediators that automatically limit the current through each LED to a safe level. When an LED short-circuits, the CCD prevents excessive current flow, isolating the fault without affecting other LEDs or causing overheating
2Device complexity
If conventional voltage divider circuits are used to control LED current, then the circuit is simple, but it cannot prevent current increase when LEDs deteriorate or age
Solution Approach 1:
The patent replaces simple voltage divider circuits with a feedback-controlled system using a microcontroller that monitors LED voltage and adjusts current via PWM. This maintains reasonable complexity while dramatically improving reliability by detecting LED deterioration and preventing current overload through active control
Solution Approach 2:
The patent replaces passive voltage divider resistor networks with an active electronic control system using microcontrollers and PWM technology. This substitution enables intelligent current management that adapts to LED conditions, providing stable current control even as LEDs age or deteriorate
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
Stably applies current and voltage to LEDs, preventing damage and fires by adjusting current output based on voltage measurements, ensuring reliable operation and reducing component loss.
Implementation Method 1
utilizing a Positive Temperature Coefficient (PTC) thermistor to manage temperature-induced resistance changes
Implementation Method 2
a voltage measuring unit connected to the LED unit in parallel, for measuring a voltage applied to the LED unit
Implementation Method 3
a rated current providing unit connected to one end of the LED unit, for providing a current to the LED unit
Data Source
AI summary
An apparatus for driving a light emitting diode (LED) comprises: an LED unit configured as a plurality of LEDs are serially connected to each other; a rated current providing unit connected to one end of the LED unit, for providing a current to the LED unit under control of a controller; a voltage dividing unit connected between another end of the LED unit and another end of the rated current providing unit; and a voltage measuring unit connected to the LED unit in parallel, for measuring a voltage applied to the LED unit.