Solid-State Lighting Apparatus Using Energy Storage Capacitor

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Solution Overview

Problem

AC-driven solid-state lighting sources often experience flickering and increased resistive loss due to LEDs requiring a minimum forward voltage, and existing solutions either result in visible flickering or require twice as many LEDs to produce the same luminous flux.

Innovation Solution

A lighting apparatus with a current control circuit that includes a storage capacitor to store energy during peak voltage and discharge it when the input AC voltage is insufficient, along with a current limiter circuit to manage current through the LEDs, reducing flicker and maintaining uniform illumination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If LEDs are driven using a rectified AC waveform, then the LEDs can be powered from AC sources, but the LEDs turn on for only part of the waveform causing visible flickering and increased resistive loss

Engineering Contradiction:

ImproveAC power compatibilityVSAvoidlight output continuity

Core Design Contradiction:

Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The patent applies preliminary action by storing energy in a capacitor during the peak voltage portions of the AC waveform before the LEDs need to operate. This stored energy is then released during the valleys and zero-crossings to maintain continuous LED operation, preventing flickering and ensuring smooth light output throughout the entire AC cycle.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If LEDs require minimum forward voltage to turn on, then the LEDs can operate efficiently, but the LEDs remain off during low-voltage portions of the AC waveform causing flickering

Engineering Contradiction:

ImproveLED operation stabilityVSAvoidlight output uniformity

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent introduces a capacitor as an intermediary energy storage device between the AC power source and the LEDs. This capacitor mediates the voltage mismatch by accumulating energy when voltage is high and releasing it when voltage drops below the LED forward voltage threshold, ensuring continuous and uniform light output without flickering.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Duration of action of stationary object

If LEDs are placed in anti-parallel configuration for AC driving, then continuous operation is achieved, but twice as many LEDs are required to produce the same luminous flux

Engineering Contradiction:

Improvecontinuous operation capabilityVSAvoidnumber of LEDs

Core Design Contradiction:

Duration of action of stationary objectVSQuantity of substance

Solution Approach 1:

The patent achieves continuous useful action by using a capacitor to maintain energy supply to the LED string throughout the entire AC cycle. Instead of requiring anti-parallel configurations, the capacitor ensures that the LEDs receive continuous current during both positive and negative half-cycles, eliminating gaps in light output while using the same number of LEDs.

Inventive Principle:

Principle #20Continuity of useful action

4Loss of energy

If the current control circuit limits current through LEDs, then resistive loss is reduced, but the power factor may be affected

Engineering Contradiction:

Improveresistive lossVSAvoidpower factor

Core Design Contradiction:

Loss of energyVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by pre-storing energy in the capacitor during high-voltage portions of the AC cycle before current limiting is needed. This allows the current control circuit to limit current during LED operation (reducing resistive loss) while the capacitor maintains power factor correction by being charged during voltage peaks, effectively decoupling these two functions.

Inventive Principle:

Principle #10Preliminary action

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

The solution effectively reduces flicker and maintains a minimum light output level, ensuring more uniform illumination and reducing the need for additional LEDs, thereby improving the power factor and reducing resistive loss.

Implementation Method 1

at least one capacitor coupled to the at least one LED and the first current control circuit. The first current control circuit may be configured to cause the at least one capacitor to be selectively charged from the current source and to be discharged via the at least one LED

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

Typically, a solid-state light emitting device generates light through the recombination of electronic carriers, i.e. electrons and holes, in a light emitting layer or region

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS9131561B2Solid-state lighting apparatus and methods using energy storage

Publication Date: 2015.09.08 LED-IP MANAGEMENT LLC

AI summary

An apparatus includes a current control circuit configured to selectively provide current responsive to a varying voltage to at least one LED coupled in series with the first current control circuit and to at least one capacitor coupled to the at least one LED and the first current control circuit. The current control circuit may be configured to cause the at least one capacitor to be selectively charged from a current source and to be discharged via the at least one LED responsive to a varying input, such as a varying current from the current source or a varying voltage applied to the current source. For example, the current control circuit may be configured to limit current through the at least one LED to less than a current provided by the current source.