LED Brightness Control Using Dimmer Signal Edge Detection
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Solution Overview
Problem
Conventional dimmer circuits designed for incandescent and halogen bulbs are ineffective for LED lights, as LEDs do not present a resistive load and do not function properly when dimmed using these circuits, leading to inefficient brightness control.
Innovation Solution
A system comprising a dimmer, full bridge rectifier, LED brightness controller, and LED driver that modulates the power signal to control LED brightness, using a period synchronizer, signal positioner, and outputter to generate an exponentially scaled control signal that synchronizes with the AC source, allowing for accurate brightness control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional dimmer circuits are used for LED lights, then the circuit structure remains simple, but the brightness control function is ineffective
Solution Approach 1:
The patent introduces an intermediary LED driver circuit between the conventional dimmer and the LED light source. This driver circuit receives the dimmer signal and converts it into appropriate current control signals for the LED, enabling the conventional dimmer to work effectively with LEDs while maintaining circuit simplicity.
Solution Approach 2:
The patent changes the control parameter from voltage-based dimming (suitable for incandescent bulbs) to current-based dimming (suitable for LEDs). The LED driver circuit converts the voltage-based dimmer signal into current modulation signals that properly control LED brightness, resolving the incompatibility between conventional dimmers and LED technology.
2Ease of operation
If LED driver circuitry is added to enable dimming, then brightness control effectiveness is improved, but device complexity increases
Solution Approach 1:
The LED driver circuit is designed to perform multiple functions: it drives the LED, enables dimming control, and interfaces with conventional dimmer circuits. By making the driver circuit multi-functional, the patent reduces the need for separate components and minimizes overall system complexity while achieving effective brightness control.
Solution Approach 2:
The LED driver circuit automatically adapts to the input signal from the dimmer and generates the appropriate control signals for the LED without requiring external intervention. This self-service capability simplifies the control mechanism and reduces the complexity of the overall system by eliminating the need for additional control circuitry.
Data Source
AI summary
Method and apparatus to control LED brightness are disclosed. An example method includes receiving a dimmer control signal; determining a cutoff point of the dimmer control signal; determining the position of a rising edge signal within the dimmer control signal; determining if the rising edge signal occurred before the cutoff point; and outputting an LED brightness signal indicating full brightness when the rising edge signal occurred before the cutoff point, and indicating a scaled brightness when the rising edge signal did not occur before the cutoff point.