LED Field Control Circuit for Flicker-Free PWM Dimming
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Solution Overview
Problem
Existing light-emitting diode (LED) field actuation systems suffer from erroneous short-circuit detection during low luminance adjustments, leading to flickering due to misinterpretation of voltage drops, which disrupts desired light distributions.
Innovation Solution
A control and regulating system with multiple outputs and sensors is implemented, including a detector to determine target voltage drops and prevent false short-circuit detection by maintaining a constant sensor signal above a designated threshold, ensuring accurate power control and avoiding flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pulse width modulation is used to adjust luminance values at low levels, then energy savings and design flexibility are improved, but erroneous short-circuit detection and flickering occur due to voltage drop misinterpretation
Solution Approach 1:
A second voltage sensor is introduced as an intermediary component to measure the voltage at the measuring signal input. This intermediary measurement allows the system to distinguish between genuine short circuits and voltage drops caused by pulse width modulation, preventing erroneous detection while maintaining energy-efficient low-luminance operation
Solution Approach 2:
The system implements feedback by continuously monitoring the voltage at the measuring signal input through the second voltage sensor and using this information to prevent false short-circuit detection. The feedback mechanism allows the control system to adjust its interpretation of voltage drops based on actual operating conditions, eliminating flickering while preserving diagnostic functionality
2Adaptability or versatility
If integrated short-circuit detection is implemented by measuring voltage drop across LEDs, then diagnostic capability is improved, but false detection occurs during pulse width modulation at low luminance
Solution Approach 1:
The second voltage sensor acts as an intermediary measurement device that provides accurate reference voltage data at the measuring signal input. This intermediary measurement enables the system to maintain precise diagnostic capability while compensating for the voltage drops inherent in pulse width modulation operation
Solution Approach 2:
The system performs preliminary measurement of the voltage at the measuring signal input before making short-circuit detection decisions. This preliminary action allows the system to establish a baseline and distinguish between normal voltage drops during dimming and actual short circuit conditions, improving measurement precision
3Reliability
If power supply is switched off upon detecting voltage drop below threshold, then short-circuit protection is improved, but flickering occurs due to erroneous detection during PWM operation
Solution Approach 1:
The second voltage sensor serves as an intermediary that provides accurate voltage information to prevent false triggering of the protection mechanism. By using this intermediary measurement, the system maintains reliable short-circuit protection while avoiding erroneous power supply interruption that causes flickering during pulse width modulation
Solution Approach 2:
The system performs preliminary verification of voltage drops using the second voltage sensor before activating short-circuit protection. This preliminary action ensures that genuine short circuits are protected against while preventing false protection activation during normal PWM dimming operation, thereby eliminating flickering
Data Source
AI summary
A method is provided for operating a control and/or regulating system for a light emitting diode field. At least two first outputs are provided at which control signals for controlling controllable switch elements of the light emitting diode field are tapped. A second output is provided at which control and/or regulating signals for controlling and/or regulating a controllable and/or regulatable power source is tapped. The voltage drop across the light emitting diode field is measured by the first voltage sensor, and when the control and/or regulating signal of the control and/or regulating system falls below a designated voltage value, the controllable and/or regulatable power source is switched off. A constant sensor signal is present at the at least one measuring signal input, and the sensor signal is larger than the designated voltage value.