AC Line Voltage Encoding via Half-Cycle Inversion for LED Control
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Solution Overview
Problem
Conventional AC dimmers struggle to efficiently encode information related to LED-based lighting units on AC line voltage, making it challenging to provide both operating power and control signals to LED-based lighting fixtures, especially when they are coupled to the same dimming circuit.
Innovation Solution
Encoding AC line voltage with dimming information by inverting half-cycles to generate an encoded AC power signal, where the ratio of positive to negative half-cycles represents the encoded information, allowing for controlling LED-based lighting units with a substantially similar RMS value as the AC line voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional AC dimmers adjust voltage amplitude or duty cycle to control light intensity, then lighting control capability is improved, but the ability to encode control information on AC line voltage for LED-based lighting units deteriorates
Solution Approach 1:
The patent merges power delivery and control information transmission into a single AC line voltage signal. By encoding control information (dimming levels, color temperature) directly onto the power line through half-cycle inversion, the system combines what were previously separate functions into one unified signal path, eliminating the need for additional control wiring while maintaining full control capability.
Solution Approach 2:
The AC line voltage serves multiple functions simultaneously: it provides operating power to LED-based lighting units and encodes control information for dimming and color temperature adjustment. This multi-functionality allows the same signal to both power the load and convey control commands, resolving the contradiction between power delivery and information encoding.
2Loss of information
If AC line voltage is encoded by inverting half-cycles to carry control information, then control information transmission is improved, but compatibility with conventional dimmer types and LED fixtures deteriorates
Solution Approach 1:
The patent introduces asymmetry into the AC waveform by selectively inverting half-cycles based on encoded control information. This asymmetric modulation creates a recognizable pattern that LED drivers can detect and interpret, while the underlying AC nature of the signal maintains compatibility with standard LED fixtures and dimmer circuits that expect conventional AC input.
Solution Approach 2:
The patent uses half-cycle inversion as the encoding mechanism - literally inverting portions of the AC waveform to represent control data. This inversion technique allows control information to be embedded in the power signal itself, creating a universal interface that works across different dimmer types and LED fixture configurations without requiring specialized hardware.
3Power
If the encoded AC power signal has a substantially similar RMS value as the AC line voltage, then power delivery capability is improved, but the precision of encoding control information deteriorates
Solution Approach 1:
The patent uses periodic half-cycle inversion patterns to encode control information while maintaining the overall AC waveform structure. By inverting specific half-cycles in a periodic pattern determined by the control data, the system preserves the RMS voltage level for adequate power delivery while creating detectable variations that enable precise encoding of dimming levels and color temperature settings.
Data Source
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AI summary
An AC line voltage may be encoded with control information, such as dimming information derived from an output signal of a conventional dimmer, so as to provide an encoded AC power signal. One or more lighting units, including LED-based lighting units, may be both provided with operating power and controlled (e.g., dimmed) based on the encoded power signal. In one implementation, information may be encoded on the AC line voltage by inverting some half cycles of the AC line voltage to generate an encoded AC power signal, with the ratio of positive half-cycles to negative half-cycles representing the encoded information. In other aspects, the encoded information may relate to one or more parameters of the light generated by the LED-based lighting unit(s) (e.g., intensity, color, color temperature, etc.).