AC Light Dimming Circuit Timer Synchronization Reduces Flicker
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Solution Overview
Problem
Conventional AC power control systems for lighting and electrical loads suffer from flicker issues due to variability in gate pulse assertion relative to the AC waveform, which is perceivable to the human eye and reduces consistency.
Innovation Solution
A system utilizing a timer synchronized to the AC waveform to control the triac, with a processing unit and timer logic that generates a gate signal with a predetermined pulse width, reducing real-time processing requirements and improving consistency by synchronizing the timer with the AC waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional triac control circuit is used to dim lighting by varying gate pulse position, then power control effectiveness is improved, but flicker occurs due to variability in gate pulse assertion relative to the AC waveform
Solution Approach 1:
The timer is configured to repeatedly count at a rate equal to twice the frequency of the AC waveform, creating periodic gate pulses that are consistently timed relative to each AC cycle. This periodic action ensures the triac is triggered at the same phase angle of every AC cycle, eliminating variability that causes flicker while maintaining effective power control through dimming.
2Speed
If real-time processing is used to control gate pulse timing, then responsiveness is improved, but processing complexity and time requirements increase
Solution Approach 1:
The patent replaces complex real-time processing calculations with a timer-based system that uses simple counting and comparison operations. The timer counts clock cycles and compares against stored values in registers, substituting sophisticated real-time control algorithms with a simpler, more reliable timing mechanism that achieves the same responsiveness without the processing complexity.
Data Source
AI summary
A system and method for controlling the dimming of a lighting element, or other electrical load, that uses a timer synchronized to the AC waveform is disclosed. The timer is set up to repeatedly count at a rate equal to twice the frequency of the AC waveform. An output from the timer logic is asserted when the timer value exceeds a predetermined value, stored in a compare register. This output is connected to the gate of a triac, which controls the passage of current from the AC power source to the electrical load. A capture register is used to determine the temporal relationship between the restart of the timer and the AC waveform. This system and method reduces the real time requirements of an associated processing unit, and improves consistency, thereby reducing flicker.