LED Driving Circuit with Energy Storing Capacitor for Flicker Reduction
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Solution Overview
Problem
LED driving circuits using AC power sources often cause flicker effects due to power drops during the negative half cycle of sinusoidal waves, which can negatively affect human health despite not being visually observable.
Innovation Solution
The proposed LED driving circuit includes a charging-discharging circuit with a diode and energy storing capacitor, coupled with constant-current units to regulate current, ensuring stable current supply during both positive and negative AC cycles, thereby reducing flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If AC current is used to drive LEDs, then energy saving and long service life are achieved, but flicker effect occurs during negative half cycle
Solution Approach 1:
The energy storing circuit (capacitor) is charged during the positive half cycle of AC current in advance, so that when the negative half cycle occurs and AC current drops, the pre-stored energy can immediately supply current to the LED, preventing flicker. This preliminary energy storage action resolves the contradiction between using AC power and avoiding flicker.
2Use of energy by moving object
If AC current is used to drive LEDs, then power saving lighting is achieved, but power drops during negative half cycle causing current insufficient
Solution Approach 1:
The energy storing circuit acts as an intermediary between the AC current source and the LED. During the positive half cycle, it stores energy from the AC current; during the negative half cycle, it releases stored energy to maintain stable current flow through the LED. This intermediary component resolves the contradiction between energy saving and current stability.
3Reliability
If constant-current units are added to regulate current, then current stability is improved, but circuit complexity increases
Solution Approach 1:
The energy storing circuit serves multiple functions: it acts as a power source during negative half cycles, provides current regulation, and reduces flicker. By making this component multi-functional, the circuit achieves current stability without adding excessive complexity, as one component performs multiple roles rather than requiring separate dedicated components for each function.
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 maintains a stable current supply to LEDs, significantly reducing the flicker effect and enhancing user experience by preventing sudden current drops.
Implementation Method 1
The first energy storing circuit includes a first node and a second node. The first node of the first energy storing circuit is coupled to the second node of the first impedance and the second node of the first diode. The second node of the first energy storing circuit is coupled to the second node of the first LED unit.
Implementation Method 2
The first diode includes a first node and a second node, wherein the first node of the first diode is coupled to the first node of the first impedance, and the second node of the first diode is coupled to the second node of the first impedance.
Data Source
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AI summary
An LED driving circuit (100) includes a charging-discharging circuit (120) and a constant-current unit (130). The charging-discharging circuit (120) is coupled to an AC current source (140), and includes an impedance (RL1), a diode (DS1) and an energy storing circuit (CE1). The energy storing circuit (CE1) is coupled to the impedance (RL1), the diode (DS1), and an LED unit (110). The constant-current unit is coupled to the charging-discharging circuit (120) in series, and is arranged to regulate current. During the positive half cycle of the AC current source (140), the constant-current unit (130) charges the energy storing circuit (120) via the impedance (RL1); and during the negative half cycle of the AC current source (140), the energy storing circuit (CE1) provides the LED unit (110) with a discharging current via the diode (DS1), making the driving current of the LED driving circuit (100) remain stable even when the AC current changes from the positive half cycle to the negative half cycle, thus preventing the flicker effect.