AC LED Lamp Power Bank for Continuous Illumination
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Solution Overview
Problem
AC LED lamps suffer from a dark period due to low rectified input voltage, causing undesirable dark lines in photographs taken under their luminance, as they can only emit light in a narrow time period of each AC cycle, leading to low average luminance or high-current stress.
Innovation Solution
Incorporating a power bank with a capacitor and a discharge switch, such as a PNP BJT, to store energy during high input voltage periods and release it during low voltage periods, ensuring continuous illumination by controlling the path switches and current sources to maintain at least one LED group lit, eliminating the dark period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple AC LED circuit with current-limiting resistor is used, then manufacturing cost and structural simplicity are improved, but average luminance deteriorates due to narrow emission time period
Solution Approach 1:
The power bank capacitor charges in advance during high-voltage periods of the AC cycle, storing energy that will be released during low-voltage periods. This preliminary energy accumulation ensures continuous LED operation without requiring complex control circuits, resolving the contradiction between simple structure and continuous illumination.
Solution Approach 2:
The power bank acts as an intermediary energy storage device between the AC input and the LED load. It decouples the narrow high-voltage window from the continuous illumination requirement, allowing the simple AC LED circuit to maintain average luminance without adding complex rectifier or converter circuits.
2Device complexity
If AC voltage directly powers the LED circuit, then structural simplicity is improved, but high-current stress deteriorates due to narrow emission time period
Solution Approach 1:
The capacitor pre-charges during high-voltage AC periods, storing energy that will be released during low-voltage periods. This eliminates the need for high current pulses during narrow emission windows, reducing current stress on LEDs while maintaining structural simplicity.
Solution Approach 2:
The power bank enables continuous operation of the LED circuit throughout the entire AC cycle by releasing stored energy during low-voltage periods. This continuous action eliminates narrow emission windows and associated high-current stress, while the simple capacitor-based implementation maintains structural simplicity.
3Loss of energy
If full-wave rectifier with multiple LED groups is used, then power efficiency is improved, but dark period deteriorates causing dark lines in photographs
Solution Approach 1:
The power bank capacitor charges in advance during high-voltage periods of the AC cycle, storing energy that will be released during low-voltage periods. This preliminary action ensures at least one LED group remains illuminated throughout the entire AC cycle, eliminating dark periods and dark lines in photographs while maintaining the power efficiency of full-wave rectification.
Solution Approach 2:
The power bank enables continuous illumination by releasing stored energy during low-voltage periods when rectified voltage is insufficient. This continuous useful action ensures no dark periods occur, eliminating dark lines in photographs while preserving the power efficiency benefits of full-wave rectifier operation.
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 ensures continuous illumination without dark periods, improving average luminance and reducing high-current stress, as at least one LED group remains lit throughout the AC cycle, enhancing the performance of AC LED lamps.
Implementation Method 1
Incorporating a power bank with a capacitor and a discharge switch, such as a PNP BJT, to store energy during high input voltage periods and release it during low voltage periods
Implementation Method 2
a discharge switch, such as a PNP BJT, to store energy during high input voltage periods and release it during low voltage periods
Implementation Method 3
A string of LEDs are grouped into LED groups 201, 202, 203, and 204
Implementation Method 4
LEDs are increasingly being used for general lighting purposes
Data Source
AI summary
A LED lamp has LED groups, a path controller, a power bank, and a bank controller. The LED groups are arranged in series between a rectified input voltage and a ground voltage. The path controller controls path switches, each path switch for coupling a corresponding LED group to the ground voltage. The power bank is coupled between the rectified input voltage and the ground voltage, having a capacitor and a discharge switch. The capacitor is configured to be charged when the rectified input voltage exceeds a capacitor voltage of the capacitor. The discharge switch is connected between the capacitor and the rectified input voltage. The bank controller determines a connection period and controls the discharge switch in response to a signal turning ON one of path switches, in order to make the capacitor capable of being discharged to the rectified input voltage during the connection period.