Liquid Crystal Display Polarity Inversion for Image Sticking
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Solution Overview
Problem
Liquid crystal display devices suffer from display quality degradation due to DC image sticking and flicker phenomena, which are caused by residual images and visual perception of brightness differences, particularly during interlace data and scroll operations.
Innovation Solution
A liquid crystal display device and driving method that inverts the polarity of data voltage every frame period except at Nth-multiple frame periods, with a POL/SOE logic circuit controlling the polarity and pulse width of the source output enable signal to prevent DC image sticking and flicker, by maintaining the same polarity and increasing the pulse width at Nth-multiple frame periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polarity inversion is applied every frame period, then DC image sticking is reduced, but flicker phenomenon occurs during interlace and scroll operations
Solution Approach 1:
The patent implements a periodic polarity inversion scheme where the polarity is inverted every frame period under normal conditions, but suspends inversion at specifically detected Nth-multiple frame periods. This periodic suspension prevents the accumulation of charge that causes flicker during interlace and scroll operations while maintaining DC image sticking prevention during regular operation.
Solution Approach 2:
The patent employs a detection mechanism that monitors display operation modes and identifies when interlace or scroll operations are occurring. Based on this feedback, the system dynamically adjusts the polarity inversion strategy by suspending inversion at Nth-multiple frame periods only when needed, thus preventing flicker while maintaining optimal DC image sticking prevention.
2Productivity
If interlace data is supplied to liquid crystal cells, then motion picture display is enabled, but DC image sticking occurs due to dominant positive voltage accumulation
Solution Approach 1:
The patent maintains regular polarity inversion for interlace data during most frame periods to enable motion picture display, but introduces periodic suspension of inversion at Nth-multiple frame periods. This balanced approach allows interlace operation while preventing the dominant positive voltage accumulation that causes DC image sticking.
3Productivity
If image is scrolled at fixed speed, then dynamic display is achieved, but DC image sticking occurs due to repeated charge accumulation
Solution Approach 1:
The patent maintains polarity inversion during scroll operations for most frame periods to enable dynamic display, but periodically suspends inversion at Nth-multiple frame periods. This prevents the repeated charge accumulation that occurs during fixed-speed scrolling while maintaining the scroll operation capability.
Data Source
AI summary
A liquid crystal display device includes a liquid crystal display panel including a plurality of data lines to which a data voltage is supplied, a plurality of gate lines to which a gate pulse is supplied, and a plurality of liquid crystal cells, a data drive circuit to invert a polarity of the data voltage in response to a polarity control signal and to output the data voltage to the data lines in response to a source output enable signal, a gate drive circuit to supply the gate pulse to the gate lines, and a POL/SOE logic circuit to invert the polarity control signal for every frame period except at Nth-multiple frame period (where N is a positive integer), wherein the POL/SOE logic circuit controls the polarity control signal at every Nth-multiple frame period such that the polarity of the data voltage is the same as the previous frame period and controls a pulse width of the source output enable signal at every Nth-multiple frame period to be longer than for the other frame periods.