LED Driver Circuit Phase Shift Glitch Mitigation
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Solution Overview
Problem
Existing LED driver circuits experience undesirable glitches due to phase shift changes in control signals, leading to lighting artifacts, especially in multi-channel RGB LED applications where pulse modulation signals are defined by phase shifts and duty cycles.
Innovation Solution
The proposed solution involves a driver circuit with a signal generator that determines phase shift changes in control signals and terminates the current pulse modulation signal at the beginning of a period to generate a new signal with the updated phase shift, reducing or eliminating glitches by allowing phase-shift changes on the fly without switching off LED lighting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If phase shift changes are implemented in PM signals to change LED light output, then lighting control flexibility is improved, but undesirable glitches and lighting artifacts are introduced
Solution Approach 1:
The patent applies preliminary action by detecting phase shift changes in advance during a sampling period before the PM signal is generated. The system determines whether a phase shift change is indicated before committing to the signal generation, allowing it to prepare appropriate mitigation strategies and avoid glitches proactively rather than reactively
Solution Approach 2:
The patent introduces an intermediary sampling period between control signal input and PM signal generation. This intermediate stage allows the system to detect and evaluate phase shift changes, acting as a buffer that mediates between the control input and the actual LED driving signal, thereby preventing direct transmission of glitch-causing phase shifts
2Speed
If current PM signal is terminated and new PM signal is generated to implement phase shift changes, then lighting control responsiveness is improved, but short glitches may still occur
Solution Approach 1:
The patent employs periodic action by structuring the signal generation around discrete PM periods with a sampling period in between. Phase shift changes are detected and implemented at specific periodic intervals rather than continuously, which maintains responsiveness while providing structured opportunities to avoid glitches through the periodic sampling and detection mechanism
3Duration of action of stationary object
If phase shift changes are made without full PWM cycle interruptions, then LED lighting continuity is maintained, but precise phase shift control becomes more complex
Solution Approach 1:
The patent applies local quality by making phase shift changes local to specific PM periods rather than requiring global PWM cycle interruptions. The sampling period allows localized detection and implementation of phase shifts within individual periods, maintaining LED continuity while managing complexity through localized rather than system-wide control changes
Data Source
AI summary
Driver circuits are described for driving one or more light emitting diodes. A driver circuit may comprise an interface configured to receive control signals from a processor and a signal generator configured to generate pulse modulation (PM) signals based on the control signals, wherein the PM signals define phase shifts. In some examples, the signal generator is configured to: determine whether the control signals indicate a phase shift change; and in response to determining that the control signals indicate a phase shift change, terminate a current PM signal at a beginning of a PM period, and generate a new PM signal in the PM period, wherein the new PM signal includes the phase shift change. In other examples, termination may be avoided in some situations, for example, upon determining that a new phase shift is not sufficiently less than a previous phase shift.