Booster Circuit Oscillation Elimination for Display Backlight

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Solution Overview

Problem

Large-size liquid crystal display panels require higher driving voltages due to increased light bars in backlight modules, leading to parasitic capacitance and oscillations that cause significant electromagnetic interference, affecting display performance.

Innovation Solution

A booster circuit comprising a booster sub-circuit and an oscillation elimination sub-circuit, which includes a power supply, inductor, switches, and an oscillation elimination component like a NOR gate or thyristor, to prevent current flow from parasitic capacitance through the inductor, thereby eliminating oscillations and reducing electromagnetic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the number of light bars is increased to achieve normal display brightness for large-size liquid crystal display panels, then the display brightness is improved, but the driving voltage requirement increases and parasitic capacitance is generated causing electromagnetic interference

Engineering Contradiction:

Improvedisplay brightnessVSAvoidelectromagnetic interference

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the harmful oscillation component from the circuit by introducing an oscillation elimination sub-circuit that specifically targets and eliminates the oscillation caused by parasitic capacitance discharge, while preserving the useful voltage boosting function

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary oscillation elimination sub-circuit that mediates between the parasitic capacitance and the inductor, preventing the harmful interaction between them while allowing the necessary current flow for voltage boosting

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If a booster circuit is used to provide higher driving voltage for increased light bars, then the driving voltage is improved, but parasitic capacitance is generated causing oscillation and electromagnetic interference

Engineering Contradiction:

Improvedriving voltageVSAvoidelectromagnetic interference

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of parasitic capacitance discharge into a beneficial outcome by controlling the discharge path to flow through the oscillation elimination sub-circuit instead of the inductor, thereby eliminating oscillation while maintaining voltage boosting capability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent separates the harmful oscillation-generating path from the useful voltage boosting path by introducing a dedicated oscillation elimination sub-circuit that intercepts and redirects the parasitic capacitance discharge current

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If the booster circuit operates in discontinuous current mode, then the voltage boosting efficiency is improved, but parasitic capacitance discharge through the inductor causes greater oscillation and electromagnetic interference

Engineering Contradiction:

Improvevoltage boosting efficiencyVSAvoidelectromagnetic interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary oscillation elimination sub-circuit that mediates the discharge process of parasitic capacitance, allowing the discontinuous current mode operation for efficient voltage boosting while preventing the harmful oscillation by providing an alternative discharge path

Inventive Principle:

Principle #24Intermediary (Mediator)

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 provides a stable voltage boost while minimizing electromagnetic interference, enhancing the performance and reliability of large-size liquid crystal display panels by eliminating oscillations caused by parasitic capacitance.

Implementation Method 1

a booster sub-circuit configured to provide, at a connection node, a voltage higher than a voltage provided from the power supply element; and wherein a parasitic capacitance occurs between the connection node and a ground terminal

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

a parasitic capacitance occurs between the connection node and the ground terminal

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11645983B2Booster circuit and driving method thereof, backlight module and display device

Publication Date: 2023.05.09 CHONGQING BOE OPTOELECTRONICS

AI summary

The embodiments of the present application disclose a booster circuit and a driving method thereof, a backlight module and a display device. The booster circuit includes: a booster sub-circuit and an oscillation elimination sub-circuit; wherein the booster sub-circuit includes a power supply element, an inductor, and a first switch; the booster sub-circuit is configured to provide, at a connection node, a voltage higher than a voltage provided from the power supply element; and wherein a parasitic capacitance occurs between the connection node and a ground terminal; the oscillation elimination sub-circuit is configured to prevent a current generated when the parasitic capacitance discharges from flowing through the inductor so as to eliminate an oscillation generated between the parasitic capacitance and the inductor.