LED Drive Circuit Flicker Reduction via Switch Control
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Solution Overview
Problem
LED drive devices experience flicker at low brightness states due to inefficiencies in voltage conversion, leading to increased power consumption and reduced power conversion efficiency, and existing solutions like bleeder circuits complicate downsizing and cost reduction.
Innovation Solution
An LED drive method utilizing a voltage conversion unit, constant current drive unit, and control unit that includes a voltage feedback control, fixed pulse control, and selection unit to generate drive signals that maintain consistent LED brightness by adjusting the on-pulse period and cycle of the first switch, eliminating the need for a bleeder circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a bleeder circuit is provided to reduce flicker at low brightness, then flicker is reduced, but device complexity increases due to additional components (bleeder resistance and switch)
Solution Approach 1:
The invention extracts and eliminates the bleeder circuit from the LED drive system. By using a different control approach for the main switching element, the patent achieves flicker reduction without requiring the separate bleeder resistance and switch components, thus removing the problematic subsystem while retaining the beneficial effect.
Solution Approach 2:
The main switching element in the voltage conversion unit is made to serve dual functions: both voltage conversion and flicker control. By controlling the on-pulse period of this single switch, the patent achieves both power conversion and flicker suppression, eliminating the need for dedicated bleeder circuit components.
2Object-affected harmful factors
If a bleeder circuit is provided to reduce flicker at low brightness, then flicker is reduced, but power consumption increases due to useless power consumption by the bleeder resistance
Solution Approach 1:
The invention removes the bleeder resistance from the system entirely. Instead of having a separate power-consuming component to control flicker, the patent uses the main switching element's control to achieve flicker reduction, eliminating the source of useless power consumption.
Solution Approach 2:
The voltage conversion unit's switching element performs self-service by simultaneously handling voltage conversion and flicker control. The same switch that converts voltage also controls the on-pulse period to prevent flicker, making the system self-sufficient without additional power-consuming components.
3Object-affected harmful factors
If a bleeder circuit is provided to reduce flicker at low brightness, then flicker is reduced, but downsizing and cost reduction are hindered due to additional components
Solution Approach 1:
The invention extracts and removes the bleeder circuit components (resistance and switch) from the LED drive system. By using alternative control methods on existing components, the patent eliminates these additional parts, enabling smaller device size and lower manufacturing costs.
Solution Approach 2:
The patent makes existing components multi-functional. The main switching element handles both voltage conversion and flicker control, maximizing the utility of existing components and eliminating the need for additional parts that would increase size and cost.
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 approach effectively reduces flicker at low brightness states, minimizes power consumption, and enables downsizing and cost reduction of LED drive devices by eliminating the need for a bleeder circuit, while maintaining efficient power conversion.
Implementation Method 1
A voltage conversion unit includes a coil and a first switch and converts an AC voltage into a first voltage which is a DC voltage by controlling the first switch to be on in an on-pulse period of a first drive signal
Data Source
AI summary
An LED drive method drives an LED by a drive current. The LED drive method uses a voltage conversion unit, which includes a coil and a first switch, and converts an external voltage into a first voltage, which is a DC voltage, by controlling the first switch to be on in an on-pulse period of a first drive signal. A constant current drive unit is provided with the first voltage and generates a drive current based on a second drive signal.