AC LED Circuit with TRIAC Dimmer Compatibility
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Solution Overview
Problem
Solid state lighting devices are typically designed for direct current (DC) power, which requires inefficient power converters to handle alternating current (AC) from the grid, increasing costs and introducing efficiency losses, and prohibits the use of traditional AC dimmer solutions for adjusting brightness.
Innovation Solution
A lighting system that includes a circuit with a TRIAC dimmer, bridge rectifier, bleeder circuit, and capacitors to generate a rectified AC waveform, maintaining a load on the dimmer and reducing flickering, using a second set of LEDs with lower turn-on voltage to generate light during AC waveform drops, and adjusting color temperature by turning on/off different sets of LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a power converter is used to convert AC power into DC power for solid state lighting, then the lighting source can be powered, but the cost increases and additional efficiency losses are introduced
Solution Approach 1:
The patent extracts and eliminates the power converter component from the system by designing an AC-driven LED circuit that directly processes AC waveform through rectification and control circuitry, thereby removing the source of efficiency losses and cost increases associated with AC-to-DC conversion
Solution Approach 2:
The patent introduces an intermediary control circuit that includes a dimmer switch and rectifier circuit to mediate between the AC power source and LED load, enabling direct AC driving without requiring a full power converter while maintaining compatibility with existing AC lighting controls
2Adaptability or versatility
If a power converter is used to convert AC power into DC power, then the lighting source can be powered, but traditional AC-lighting dimmer solutions cannot be used
Solution Approach 1:
The patent designs a universal AC-driven LED circuit that integrates compatibility with traditional AC dimmer switches, allowing the same circuit to function with both dimmer control and direct AC power, thereby eliminating the need for separate DC driving circuits and maintaining adaptability to existing lighting control infrastructure
Solution Approach 2:
The patent implements dynamic control circuitry that responds to the AC waveform characteristics and dimmer switch signals in real-time, adjusting the rectification and current control parameters dynamically to maintain compatibility with varying AC input conditions and dimmer control signals
3Use of energy by moving object
If LEDs are driven using a rectified AC waveform, then AC power can be used directly, but the LEDs may turn on for only a part of the waveform resulting in visible flickering
Solution Approach 1:
The patent applies preliminary action by using a capacitor to store energy during portions of the AC waveform when voltage is sufficient, then releasing this stored energy during portions where voltage drops below LED turn-on threshold, thereby preemptively ensuring continuous LED operation and eliminating flickering before it occurs
Solution Approach 2:
The patent ensures continuity of useful action by designing the circuit so that LEDs remain continuously illuminated through the entire AC cycle, preventing the intermittent operation that causes flickering. The capacitor and control circuitry work together to maintain continuous current flow through the LEDs throughout the AC waveform cycle
4Ease of operation
If LEDs are driven using a rectified AC waveform, then AC power can be used directly, but the power factor of the system is lowered
Solution Approach 1:
The patent changes the operational parameters of the LED driving circuit by adjusting the rectification timing, capacitor charging/discharging characteristics, and current control parameters to optimize the power factor while maintaining direct AC driving capability, thereby improving energy efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves efficient AC-driven LED lighting with reduced flickering and improved power factor, allowing for adjustable color temperature and brightness without the need for DC drivers, thus lowering costs and increasing efficiency.
Implementation Method 1
a circuit with a TRIAC dimmer, bridge rectifier, bleeder circuit, and capacitors to generate a rectified AC waveform
Implementation Method 2
one or more capacitors for reducing flickering of one or more of the first plurality of LEDs
Implementation Method 3
Solid state light emitting devices typically generate light through the recombination of electronic carriers, i.e., electrons and holes, in a light emitting layer or region
Data Source
AI summary
A lighting system and a circuit for a solid state lighting apparatus are provided. The circuit includes an AC power source, an AC TRIAC dimmer, a plurality of light emitting diodes (LEDs), a bridge rectifier for providing a rectified AC waveform, and at least one capacitor for reducing flicker in the LEDs, and a plurality of LEDs with lower forward voltage connected to a static dimming bleeder or bleeder circuit for providing holding current to the triac of a dimmer circuit to increase the overall efficiency of the lighting system without dynamic control of the bleeder circuit. In some embodiments, the circuit includes a plurality of current sinks used for setting and maintaining a current to the main LEDs and to establish a stable bleeder current.