LCD Driving Method Preventing DC Image Sticking via Polarity Inversion
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Solution Overview
Problem
Liquid crystal display (LCD) devices suffer from direct current (DC) image sticking and flicker, which degrade display quality due to prolonged supply of voltages with the same polarity, especially in interlace schemes and during image scrolling.
Innovation Solution
A liquid crystal display device and driving method that involve interleaving black or intermediate gray scale data into digital video data, accelerating timing signal frequencies, and using gate integrated circuits to control scan pulses and voltage polarities, ensuring opposite polarities are supplied to liquid crystal cells in specific periods to prevent DC image sticking and flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data voltages having the same polarity are successively supplied to liquid crystal cells in interlace scheme or during image scrolling, then the display can show moving images or scrolling content, but DC image sticking occurs due to prolonged same-polarity voltage supply
Solution Approach 1:
The patent applies periodic action by inserting black or intermediate gray scale data at regular intervals (specifically, once every N frames where N is 2 or more) into the video data stream. This periodic insertion creates alternating periods of normal video display and polarity-inverting blanking periods, preventing continuous same-polarity voltage accumulation in liquid crystal cells while maintaining moving image display capability.
Solution Approach 2:
The patent changes the polarity parameter of the voltage supplied to liquid crystal cells by inserting black or intermediate gray scale data with opposite polarity. This parameter change alternates the voltage polarity applied to the liquid crystal cells, preventing DC image sticking caused by prolonged same-polarity voltage supply during interlace scheme or image scrolling operations.
2Object-affected harmful factors
If black or intermediate gray scale data is interleaved into video data to prevent DC image sticking, then display quality improves, but the complexity of the data processing system increases
Solution Approach 1:
The patent changes the polarity parameter of the voltage supplied to liquid crystal cells by inserting black or intermediate gray scale data with opposite polarity. This parameter change alternates the voltage polarity applied to the liquid crystal cells, preventing DC image sticking caused by prolonged same-polarity voltage supply during interlace scheme or image scrolling operations.
3Object-affected harmful factors
If voltage polarity is inverted periodically to prevent DC image sticking, then image clarity improves, but brightness fluctuations may occur
Solution Approach 1:
The patent applies local quality by using intermediate gray scale data (with gray scale values between 0 and 255) instead of purely black data for polarity inversion in certain scenarios. This localized adjustment of the blanking data level reduces the brightness contrast between normal display periods and polarity-inversion periods, minimizing visible flicker while maintaining the DC image sticking prevention effect.
Solution Approach 2:
The patent changes the polarity parameter of the voltage supplied to liquid crystal cells by inserting black or intermediate gray scale data with opposite polarity. This parameter change alternates the voltage polarity applied to the liquid crystal cells, preventing DC image sticking caused by prolonged same-polarity voltage supply during interlace scheme or image scrolling operations.
Data Source
AI summary
A liquid crystal display (LCD) device and a driving method where the LCD device includes a data controller for interleaving one of black gray scale data and intermediate gray scale data into input digital video data to input digital video data in a specific period preceding a second one of two successive frame periods in which data voltages having the same polarity are successively supplied to liquid crystal cells. A timing signal controller generates a data timing signal and a gate timing signal, based on an input timing signal, and accelerates a frequency of the data timing signal and a frequency of the gate timing signal in the specific period. A data driving circuit is included for converting the interleaved digital video data into an analog voltage in response to the data timing signal, and supplying the analog voltage to data lines in the specific period.