LED Lighting Device with Segmented Parallel Arrays for AC Drive
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Solution Overview
Problem
Existing LED lighting technologies face challenges when using commercial AC power supplies, as they often require conversion to DC voltage, leading to inefficiencies and issues with LED failures due to disconnections or short circuits, particularly for white LEDs, where failures can occur frequently.
Innovation Solution
A circuit configuration where multiple LED arrays are connected in parallel, each with series-connected LEDs and capacitors, allowing direct AC power supply usage while isolating failed LEDs to prevent them from turning off other LEDs, and optionally incorporating a full-wave rectifying circuit for improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If AC voltage is directly applied to LEDs to turn them on without converting to DC, then energy efficiency is improved, but the risk of LED failure due to voltage spikes or reverse polarity increases
Solution Approach 1:
The circuit is segmented into multiple independent parallel branches, each containing an LED string with series-connected LEDs and protective components. This segmentation isolates failures to individual branches while maintaining operation of other branches, resolving the contradiction by enabling direct AC application with improved reliability.
Solution Approach 2:
Protective components including reverse polarity protection diodes, voltage suppression diodes, and current-limiting resistors are pre-installed in each LED branch before operation. These components cushion against voltage spikes and reverse polarity conditions inherent in direct AC application, allowing energy-efficient direct AC drive while preventing LED failure.
2Device complexity
If LEDs are arranged in series to reduce the number of LEDs required for AC voltage operation, then device complexity is reduced, but the reliability decreases because one failed LED turns off the entire string
Solution Approach 1:
The LED load is segmented into multiple parallel branches, with each branch containing a series string of LEDs. This segmentation reduces the total number of LEDs needed compared to all-parallel configurations while ensuring that failures in one branch do not affect other branches, thus maintaining reliability while simplifying the overall device structure.
Solution Approach 2:
The circuit topology transitions from a single-dimensional series or parallel arrangement to a two-dimensional grid structure with multiple parallel branches containing series strings. This dimensional change enables the system to achieve both reduced component count and improved failure tolerance simultaneously.
3Use of energy by moving object
If a diode is connected in parallel with LED to prevent rectification and charge storage in capacitor, then energy efficiency is improved, but the circuit complexity increases
Solution Approach 1:
The protective diode is merged with the LED component itself, forming an integrated LED assembly where the diode and LED share common electrical connections and physical packaging. This merging approach enables energy-efficient AC drive while minimizing additional circuit complexity by combining protection functionality with the primary light-emitting component.
4Reliability
If multiple LED arrays are connected in parallel to maintain operation after one LED failure, then reliability is improved, but the device complexity and size increase
Solution Approach 1:
The LED system is segmented into multiple parallel branches with standardized configurations. Each branch is electrically independent and can be manufactured as a modular unit. This segmentation achieves improved failure tolerance while controlling complexity through modular design and repetition of identical circuit patterns.
Solution Approach 2:
Each parallel branch is designed with universal functionality, containing all necessary protective components (reverse polarity protection, voltage suppression, current limiting) integrated into the same circuit topology. This universality allows identical modular units to be replicated across multiple branches, improving reliability while minimizing overall complexity through standardization.
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 efficient and reliable operation of LEDs with commercial AC power, preventing the shutdown of other LEDs in case of disconnection or short circuit, and reducing the need for additional circuitry, thus enhancing energy efficiency and reliability.
Implementation Method 1
an AC voltage is applied through a capacitor to the parallel circuit. This capacitor does not have a polarity, and a forward current is applied to the LED in only a half period of the AC voltage
Implementation Method 2
The diode is connected in parallel with the LED such that the diode is disposed in a direction opposite to the LED. This is because a rectification of the circuit can be prevented by causing a current to flow to the diode in a half period in which the LED is not turned on
Implementation Method 3
LEDs (light-emitting diodes) are known as having high light-emission efficiency
Data Source
AI summary
A first LED array including a first capacitor, LED blocks, and a second capacitor that are connected in series with each other, a second LED array having a similar configuration to the first LED array, and a third LED array having a similar configuration to the first LED array are connected in parallel with each other and are connected to an AC power supply AC. Each of the LED blocks includes a first series circuit and a second series circuit that are connected in parallel with each other. The first series circuit includes two LEDs that are connected in series with each other in the same direction. The second series circuit includes two LEDs that are connected in series with each other in an identical direction opposite to the direction of the LEDs in the first series circuit. A connection point between the two LEDs in the second series circuit in one of the adjacent LED blocks is coupled to a connection point between the two LEDs in the first series circuit in the other one of the adjacent LED blocks.