LED Driver Open Circuit Detection Using PWM Voltage Thresholds
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Solution Overview
Problem
Conventional protection circuits in LED driver apparatuses for LCD backlight units often incorrectly determine if LED arrays are open due to abnormal forward voltage or peak current, leading to improper operation and malfunction.
Innovation Solution
A Pulse Width Modulation (PWM) signal generator and a sensor system that uses preset reference voltages to accurately determine if an LED array is open by comparing forward voltages, with a DC-DC converter providing driving voltage and a switching unit selectively providing forward voltages based on sensor determinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional protection circuit uses forward voltage comparison to detect open LED arrays, then open circuit detection is achieved, but false detection occurs due to abnormal forward voltage during initial driving or peak current
Solution Approach 1:
The patent applies preliminary action by performing a preliminary check of the driving voltage before comparing forward voltages. The sensor determines whether the driving voltage is at a predetermined level (indicating normal operation) before proceeding with forward voltage comparison. This preliminary check prevents false detection during initial driving or peak current conditions when forward voltage is temporarily abnormal, thereby improving detection accuracy without sacrificing reliability.
2Reliability
If the driving voltage is continuously monitored for open circuit detection, then real-time protection is achieved, but false detection occurs during normal voltage fluctuations
Solution Approach 1:
The patent uses preliminary action by establishing a predetermined driving voltage level as a threshold before detection. The sensor checks whether the driving voltage is at this predetermined level, which represents normal operation. Only when the voltage meets this preliminary condition does the circuit proceed to compare forward voltages for open circuit detection. This prevents false detection during normal voltage fluctuations while maintaining real-time protection capability.
3Speed
If forward voltage comparison is performed without considering driving voltage conditions, then detection speed is improved, but detection accuracy deteriorates due to abnormal voltage states
Solution Approach 1:
The patent applies preliminary action by performing a quick check of the driving voltage condition before executing the forward voltage comparison. This preliminary check determines whether the system is in a normal operating state (driving voltage at predetermined level). If the condition is met, the forward voltage comparison proceeds immediately, maintaining fast detection speed. If not met, the comparison is skipped or delayed, preventing inaccurate detection during abnormal voltage states. This two-stage approach preserves detection speed while improving precision.
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 accurately identifies open LED arrays, preventing malfunctions and ensuring stable operation by distinguishing between normal and abnormal voltage conditions, thereby maintaining optimal performance of the LED driver apparatus.
Implementation Method 1
a Pulse Width Modulation (PWM) signal generator configured to generate a PWM signal, a DC-DC converter configured to provide a driving voltage of a plurality of LED arrays by using the generated PWM signal
Implementation Method 2
a sensor configured to determine whether at least one LED array among the plurality of LED arrays is in an open state in response to the driving voltage being higher than or equal to a preset first reference voltage
Data Source
AI summary
A Light Emitting Diode (LED) driver apparatus is provided. The LED driver apparatus includes: a Pulse Width Modulation (PWM) signal generator configured to generate a PWM signal, a DC-DC converter configured to provide a driving voltage of a plurality of LED arrays by using the generated PWM signal, and a sensor configured to determine whether at least one LED array among the plurality of LED arrays is in an open state in response to the driving voltage being higher than or equal to a preset first reference voltage, and the preset first reference voltage is higher than the driving voltage applied when the plurality of LED arrays are each in a working state.