Light Fade Controller for Consistent Power-Off Fade Times
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Solution Overview
Problem
Light fixtures with varying output capacitor capacitances exhibit inconsistent fade times when AC power is turned off, leading to some lights remaining on while others are completely off due to differences in discharge times.
Innovation Solution
A light fade controller that includes an input power detection circuit and a power discharge circuit to enable and control the discharge path of output power from the driver circuit, adjusting the discharge rate to synchronize fade times across multiple fixtures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relatively larger capacitance output capacitor is used to reduce light flicker, then light flicker is reduced, but fade time increases
Solution Approach 1:
The patent extracts the harmful function of the output capacitor during power-off conditions by providing a separate discharge path that bypasses the capacitor. The discharge circuit actively removes stored energy from the capacitor after power failure, separating the capacitor's useful function (flicker reduction during operation) from its harmful effect (prolonged fade time after power-off).
Solution Approach 2:
The discharge circuit acts as an intermediary between the output capacitor and the light source. It provides a controlled path for dissipating stored energy, mediating between the capacitor's stored charge and the light source to prevent uncontrolled discharge through the light fixture, thereby reducing fade time while maintaining safe operation.
2Reliability
If output capacitors with relatively larger capacitance values are used in multiple light fixtures, then light flicker is reduced in each fixture, but fade time variations among lights increase
Solution Approach 1:
The discharge circuit provides feedback control by monitoring the power-off condition and actively managing the discharge process. This feedback mechanism ensures that regardless of variations in capacitor values among different fixtures, each capacitor discharges in a controlled manner, synchronizing the fade time across multiple lights and eliminating the inconsistency caused by tolerance variations.
Solution Approach 2:
The patent changes the discharge parameters by introducing an active discharge path that controls the discharge rate. By adjusting the discharge circuit's parameters (such as resistance values), the system can compensate for variations in capacitor capacitance values, ensuring uniform fade time characteristics across multiple light fixtures despite manufacturing tolerances.
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
Enables synchronized fade times across multiple light fixtures by quickly discharging output power when input power is unavailable, ensuring all lights turn off simultaneously or at desired variations.
Implementation Method 1
an output capacitor that has a relatively larger capacitance generally results in lower light flicker
Implementation Method 2
a power discharge circuit configured to enable a power discharge path to discharge output capacitor of a driver circuit through the power discharge path
Data Source
AI summary
A light fade controller includes an input power detection circuit configured to detect whether an input power is available. The light fade controller further includes a power discharge circuit configured to enable a power discharge path to discharge output power from a driver circuit through the power discharge path in response to the input power detection circuit detecting that the input power is unavailable. The power discharge circuit is also configured to adjust a rate of power discharge through the power discharge path, and the power discharge circuit either: a) includes a switch (306) that is controlled by a pulse width modulation (PWM) control signal to enable and disable the power discharge path and to adjust the rate of power discharge through the power discharge path, wherein a pulse width of the PWM signal is adjusted to enable and disable the power discharge path and to adjust the rate of power discharge through the power discharge path; or b) is configured to adjust the rate of power discharge based on a user input provided to the power discharge circuit.