LED Driving Apparatus Short Circuit Protection via Chassis Current Sensing
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Solution Overview
Problem
LED modules used as backlights in display apparatuses are prone to short-circuiting with the panel chassis during assembly, leading to damage due to high external power application when a peak current control method is used, as the wire connecting the LED module and driving circuit is compressed, causing insulating layer cracks and PCB pattern damage.
Innovation Solution
An LED driving apparatus that senses current flow through the panel chassis and stops operation when the current exceeds a preset reference value, blocking external power to prevent damage by using a buck type LED driving circuit with peak current control and an additional control unit to manage current flow and voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the LED module is connected through a wire during assembly, then the LED module can be driven by the LED driving circuit, but the wire is pressed by the panel structure causing insulating layer cracks and PCB pattern damage leading to short circuit
Solution Approach 1:
The patent extracts the vulnerable wire connection from the assembly process by using a rigid circuit board structure instead. The LED module is directly mounted on the circuit board through soldering, eliminating the wire that gets compressed and damaged during panel assembly, thus removing the source of short circuit risks while maintaining electrical connection functionality
2Productivity
If a peak current control method is used in the buck type LED driving circuit, then the LED module can be driven efficiently, but high external power is applied to the LED module when short circuit occurs causing LED module damage
Solution Approach 1:
The patent implements a feedback mechanism through a sensing resistor connected to the LED module cathode and a comparator that monitors the voltage across this resistor. When short circuit occurs, the current increases causing voltage change across the sensing resistor, which the comparator detects and uses to generate a reset signal that stops the switching transistor, thereby preventing high power damage while maintaining efficient peak current control during normal operation
Solution Approach 2:
The patent prepares protective measures in advance by incorporating the sensing resistor and comparator circuit before short circuit occurs. These components are pre-configured to detect abnormal conditions and trigger the protective shutdown sequence, cushioning the LED module against high power damage before it can occur during peak current driving
3Reliability
If the LED module is short-circuited with the panel chassis, then current flows through the short circuit path, but high external voltage applied to the LED module causes damage
Solution Approach 1:
The patent uses feedback through the sensing resistor and comparator to detect short circuit conditions by monitoring current changes. When the LED module shorts to the chassis, the increased current produces a detectable voltage change across the sensing resistor, triggering the comparator to generate a reset signal that immediately stops power application, thus protecting LED module durability while maintaining reliable short circuit detection
Data Source
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AI summary
A display apparatus is provided. The display apparatus includes a display panel configured to display an image, an LED module configured to provide backlight to the display panel, an LED driving unit configured to apply a driving voltage to the LED module using an external power, an exterior unit configured to support the LED driving unit and the LED module and include a ground terminal provided separately from the external power, and an LED driving control unit which causes an operation of the LED driving unit to be stopped based on a current flowing in from the ground terminal.