LED Constant-Current Driver With Abnormal State Protection
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Solution Overview
Problem
Existing light source driving apparatuses for light emitting diodes lack a sensing circuit to detect various abnormal states, leading to reliability issues due to continuous operation in abnormal conditions.
Innovation Solution
A light source driving apparatus with a constant current driving part, an abnormal state sensing part, and protective circuit parts that sense and respond to abnormal states by stopping the operation of the light source and constant current driving part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a constant current circuit using a transistor is used to control light emitting diodes, then the light emitting diode can be controlled with high current, but the circuit lacks sensing capability for abnormal states leading to reliability issues
Solution Approach 1:
The circuit is divided into distinct functional modules: constant current driving part for power control, abnormal state sensing part for detection, and protective circuit part for reliability. This segmentation allows each module to specialize in its function while working together to resolve the contradiction between power control and reliability.
Solution Approach 2:
The abnormal state sensing part continuously monitors for abnormal conditions before they can cause damage. By detecting issues in advance and triggering protective actions preliminarily, the system prevents reliability degradation while maintaining full power control capability.
2Device complexity
If the light emitting diode continues to operate without sensing circuits, then the device complexity is reduced, but abnormal states cause reliability problems
Solution Approach 1:
The abnormal state sensing part acts as an intermediary between the constant current driving part and the light emitting diode. It monitors abnormal conditions and mediates by triggering protective circuit actions, enabling reliable operation without significantly increasing overall system complexity.
Solution Approach 2:
The sensing circuit automatically detects abnormal states and triggers protective actions without external intervention. This self-service capability maintains reliability while keeping the control system simple and avoiding complex external monitoring infrastructure.
3Illumination intensity
If PWM type current is used to control light emitting diode brightness, then brightness control is achieved, but the linear circuit has limitations in controlling high current
Solution Approach 1:
The patent merges PWM brightness control with constant current driving capability in a unified circuit architecture. The switching device operates under PWM control for brightness adjustment while the constant current circuit ensures proper current regulation, combining the advantages of both approaches.
Data Source
AI summary
A light source driving apparatus according to an embodiment includes a light source part; a constant current driving part connected to the light source part, including a first switching device, and supplying a constant current to the light source part according to a switching operation of the first switching device; a driving control part outputting a switching signal for controlling the first switching device consisting the constant current driving part; an abnormal state sensing part sensing an abnormal state of the light source part and an abnormal state of the driving control part, and outputting a control signal according to a result of the sensing; and a protective circuit part selectively operating based on the control signal output from the abnormal state sensing part to stop an operation of the constant current driving part and an operation of the light source part.