Adjustable LED Brightness Filter Circuit
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Solution Overview
Problem
LED lighting fixtures often exhibit undesirable rapid responses to user input changes, leading to discrete, step-like brightness adjustments that can be perceived as flickering or unnatural, particularly at low brightness levels, and fail to provide smooth dimming akin to traditional incandescent lighting.
Innovation Solution
The implementation of an adjustable low-pass filter circuit with selectable time constant values, either through switchable RC low-pass filters or programmable resistance integrated circuits, allows for controlled smoothing of brightness changes, enabling either rapid or slow responses to user inputs, thereby eliminating discrete steps and achieving smooth dimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If LED brightness responds quickly to user input changes, then responsiveness is improved, but smoothness of brightness transition deteriorates
Solution Approach 1:
The patent implements a low-pass filter circuit with adjustable time constant that dynamically smooths the control voltage signal to the LED driver. By adjusting the time constant, the system can achieve different levels of smoothing while maintaining responsiveness, resolving the contradiction between quick response and smooth transition.
2Productivity
If LED brightness changes rapidly in response to user input, then productivity is improved, but visual comfort deteriorates due to perceived flickering
Solution Approach 1:
The patent introduces a low-pass filter circuit as an intermediary between the user input and the LED driver. This filter mediates the control signal by smoothing rapid changes while preserving the overall brightness adjustment intent, thereby eliminating flickering perception without sacrificing productivity.
3Device complexity
If fixed time constant filter is used, then device complexity is reduced, but adaptability to different lighting applications deteriorates
Solution Approach 1:
The patent implements an adjustable time constant filter that can be dynamically configured based on different lighting applications. This allows the same hardware circuit to adapt to various requirements (e.g., ambient lighting vs. accent lighting) without increasing fundamental device complexity, as the adjustment can be done through software or simple control circuits.
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
This solution allows for customizable brightness transition rates, enhancing the perceived smoothness of LED light adjustments, reducing flickering effects, and mimicking the gradual dimming of incandescent bulbs, catering to diverse lighting application needs.
Implementation Method 1
an adjustable low pass filter circuit having a plurality of selectable time constant values and configured to: receive and filter the first output voltage from the controller and provide the filtered first output voltage as the first control voltage to the first LED driver
Data Source
AI summary
Light emitting diode (LED) lighting fixtures are presented that use a low-pass filter to smooth out or eliminate discrete, step changes in LED light fixture brightness, that may result from the use of digital brightness level settings. Because some lighting applications require a fast response to changes in the set brightness level, and some applications require a slower response, one set of examples use a switchable RC low-pass filter circuit, with two or more selectable RC time constant values. Another set of examples use a programmable resistance integrated circuit to achieve a more continuously-variable time constant, for greater flexibility in adjusting the response time of the LED lighting fixture, in response to user brightness inputs. The user is able to control the maximum rate of change of the LED light fixture's brightness, in response to changes in the brightness setting.