LCD Common Voltage Compensation Circuit for Crosstalk Suppression

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Solution Overview

Problem

Liquid crystal displays (LCDs) face significant pixel brightness distortion and degraded display quality due to crosstalk interference, particularly during inversion driving operations when adjacent pixels switch between black/white or gray-levels, leading to unwanted voltage changes in the common voltage.

Innovation Solution

A common-voltage compensation mechanism and method that includes a common-voltage compensation circuit connected to a storage capacitor, which performs a ripple inverting operation on the liquid-crystal capacitor common voltage, generating a storage capacitor common voltage with a phase opposite to the original ripple voltage, using a timing controller to analyze image signals and adjust the compensation signal based on gray-level variations to control the peak-to-peak ratio of the ripple voltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inversion driving operations are used to prevent polarization and image sticking, then liquid crystal layer protection is improved, but crosstalk interference increases causing pixel brightness distortion

Engineering Contradiction:

Improveliquid crystal layer protectionVSAvoidcrosstalk interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful ripple voltage caused by crosstalk interference into a beneficial compensation signal. By detecting the ripple voltage through parasitic capacitors and using it to generate a compensation common voltage with opposite phase, the harmful voltage fluctuations are transformed into useful compensation that eliminates pixel brightness distortion while maintaining the protective inversion driving operations.

Inventive Principle:

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

Solution Approach 2:

The patent introduces a common-voltage compensation circuit as an intermediary between the existing common voltage generator and the liquid crystal display pixels. This intermediary circuit detects the ripple voltage and generates a compensated common voltage that cancels out the crosstalk interference, allowing the inversion driving operations to proceed without causing pixel brightness distortion.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If frame-inversion driving operations are used to avoid image sticking, then display reliability is improved, but pixel brightness distortion occurs due to crosstalk interference

Engineering Contradiction:

Improvedisplay reliabilityVSAvoidpixel brightness accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent implements a feedback mechanism where the common-voltage compensation circuit continuously monitors the ripple voltage generated during inversion driving operations and adjusts the compensation common voltage accordingly. This feedback loop ensures that the compensation signal accurately counteracts the crosstalk interference in real-time, maintaining both display reliability and pixel brightness accuracy.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the parameter of the common voltage by introducing a compensation component that varies with the ripple voltage. The compensation common voltage is generated by inverting the ripple voltage signal and combining it with the original common voltage, thereby dynamically adjusting the voltage parameter to eliminate pixel brightness distortion while preserving the protective effects of inversion driving.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If adjacent pixels switch between black/white gray-levels during inversion operations, then image display coverage is improved, but voltage changes in common voltage cause brightness distortion

Engineering Contradiction:

Improveimage display coverageVSAvoidpixel brightness

Core Design Contradiction:

Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The patent segments the common voltage into two components: the original common voltage from the common voltage generator and the compensation common voltage from the compensation circuit. By separating these functions, the system can maintain the original common voltage for normal operation while adding a separate compensation signal that specifically addresses the brightness distortion caused by adjacent pixel switching during inversion operations.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8928705B2Liquid crystal display with crosstalk interference suppression based on gray-level variation of a frame to be displayed and related method

Publication Date: 2015.01.06 OPTRONIC SCIENCES LLC

AI summary

A liquid crystal display having common voltage compensation mechanism includes a liquid-crystal capacitor common electrode for receiving a liquid-crystal capacitor common voltage, a storage capacitor common electrode for receiving a storage capacitor common voltage, a common voltage generator for providing the liquid-crystal capacitor common voltage according to a preliminary common voltage, a common voltage compensation circuit electrically connected to the liquid-crystal capacitor common electrode and the storage capacitor common electrode, and a timing controller electrically connected to the common voltage compensation circuit. The common voltage compensation circuit is utilized for generating the storage capacitor common voltage through performing a ripple inverting operation according to the liquid-crystal capacitor common voltage, the preliminary common voltage and a compensation control signal. The timing controller is employed to analyze an image input signal for generating the compensation control signal.