LED Control Circuit for Short-Circuit Failure Isolation
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Solution Overview
Problem
In parallel-connected LED systems, a short-circuit failure in one LED can disrupt the current flow to other LEDs, leading to reduced luminance and potential device failures due to excessive heat generation.
Innovation Solution
A light source control device with a constant current supplying part, switching part, failure detecting part, current sensing part, and controller that identifies short-circuit failures and adjusts current supply to individual LEDs, ensuring appropriate luminance by interrupting current to faulty LEDs and distributing current among functioning ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple LEDs are connected in parallel to enable low-voltage driving and high luminance, then power consumption is reduced and luminance is improved, but a short-circuit failure in one LED causes excessive current to flow to the failed LED and disables other LEDs
Solution Approach 1:
The patent divides the parallel-connected LED system into independently controllable segments by introducing individual switching elements for each LED. This segmentation allows the system to isolate and control current flow to specific LEDs, preventing a single LED failure from affecting the entire system. The switching elements enable selective activation/deactivation of individual LEDs while maintaining overall system luminance through coordinated control.
Solution Approach 2:
The patent implements a feedback mechanism where a controller monitors the status of each LED and adjusts the driving current accordingly. When a short-circuit failure is detected in one LED, the controller receives feedback about the abnormal current distribution and responds by adjusting the driving current to prevent excessive current flow to the failed LED while maintaining appropriate current to functioning LEDs, thus preserving system reliability and luminance.
2Productivity
If a short-circuit failed LED continues to receive intensive current, then the device may continue operating, but temperature increases causing heat generation and potential failure in other parts of the device
Solution Approach 1:
The patent applies preliminary action by proactively monitoring current distribution and detecting short-circuit failures before they cause excessive temperature increase. The controller continuously monitors the system state and, upon detecting a short-circuit condition, preemptively adjusts the driving current to the failed LED to prevent intensive current flow that would lead to heat generation. This preliminary intervention maintains continuous operation of the device while preventing temperature-related failures.
3Reliability
If a short-circuit failure occurs in one LED, then current flow to other LEDs is hindered, but interrupting current to the failed LED requires additional control mechanisms
Solution Approach 1:
The patent achieves universality by designing a controller that performs multiple functions: it monitors current distribution, detects short-circuit failures, determines which LEDs are functioning, and adjusts driving current parameters all through a single control unit. The switching elements also serve dual purposes by enabling both normal operation and failure isolation modes. This multi-functionality approach maintains system reliability while minimizing the addition of separate control mechanisms.
Data Source
AI summary
A microcomputer of a light source control device specifies an LED belonging to LEDs and subjected to a short-circuit failure based on a result of determination by a short-circuit failure detecting circuit and current amounts sensed by current sensing circuits respectively. The microcomputer makes corresponding one of switching elements interrupt supply of a current to the specified LED. The microcomputer makes a constant current circuit supply an LED not specified with a current not exceeding a current responsive to the number of such LEDs not specified.