Field Sequential LCD Gradation Compression for Response Speed
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Solution Overview
Problem
Liquid crystal display devices employing a field sequential system face image quality degradation due to low liquid crystal response speed, leading to incomplete backlight activation before transmittance reaches target values, resulting in color balance issues and flicker.
Innovation Solution
A liquid crystal display device with a gradation value compressing unit that reduces the difference between maximum and minimum gradation values by compressing input gradation data, ensuring values change at a consistent ratio across fields, and an overdrive correcting unit to emphasize temporal changes, thereby improving liquid crystal response time and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the field sequential system is used to eliminate color filters and improve light use efficiency, then luminance increases and power consumption reduces, but liquid crystal response time becomes insufficient leading to image quality degradation
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing corrected gradation values in a lookup table before display. The gradation correction unit prepares compensated values that account for liquid crystal response characteristics in advance, so when the backlight switches, the liquid crystal is already positioned to achieve the target transmittance more quickly, eliminating color balance issues without sacrificing light efficiency.
Solution Approach 2:
The patent changes the gradation parameter values to compensate for liquid crystal response limitations. By applying a correction function that adjusts input gradation values to output gradation values based on measured liquid crystal transmittance characteristics, the system optimizes the voltage applied to liquid crystal pixels, ensuring they reach target transmittance values within the shortened field period while maintaining overall image quality.
2Speed
If overdrive is applied to accelerate liquid crystal response, then transmittance reaches target value faster, but color balance deteriorates and flicker occurs
Solution Approach 1:
The patent uses a lookup table that stores pre-calculated corrected gradation values based on the liquid crystal's actual transmittance characteristics. Instead of applying aggressive overdrive that causes instability, the system copies and applies compensated values that have been optimized to match the liquid crystal's response behavior, achieving fast response while maintaining color balance and eliminating flicker.
Solution Approach 2:
The patent incorporates feedback by measuring the actual transmittance characteristics of the liquid crystal panel and using this information to create the gradation correction lookup table. The correction function is derived from actual device measurements, allowing the system to adapt to the specific liquid crystal panel's response characteristics and optimize performance without causing color balance deterioration or flicker.
3Loss of time
If the backlight switches on quickly to improve field response time, then color display accuracy improves, but liquid crystal transmittance has not reached target value causing color balance issues
Solution Approach 1:
The patent applies preliminary action by pre-calculating corrected gradation values that account for the liquid crystal's response time characteristics. The lookup table stores these compensated values in advance, so when the backlight switches on at the beginning of each field period, the liquid crystal receives the optimized voltage that will achieve the target transmittance within the available time, ensuring both fast response and accurate color display.
Solution Approach 2:
The patent changes the gradation parameter values to compensate for the time constraint. By applying a correction function that adjusts input gradation values to output gradation values based on liquid crystal transmittance characteristics, the system optimizes the voltage applied to liquid crystal pixels, ensuring they reach target transmittance values within the field period while maintaining accurate color display.
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 reduces liquid crystal response time, maintains color balance, and suppresses image quality degradation without reducing maximum luminance, while also preventing color breakup and flicker.
Implementation Method 1
image display is performed by controlling the transmittance of each pixel by a voltage (voltage applied to liquid crystal)
Data Source
AI summary
An object of the present invention is to implement a liquid crystal display device employing a field sequential system and capable of suppressing degradation of image quality caused by liquid crystal response characteristics. A liquid crystal display device is provided with a liquid crystal panel displaying an image formed of a plurality of pixels; a gradation value compressing unit generating compressed data by performing a compression process which is a process of correcting input gradation data such that a difference between a maximum gradation value and a minimum gradation value is reduced; and a liquid crystal panel driving unit driving the liquid crystal panel based on the compressed data. The gradation value compressing unit performs the compression process such that values of input gradation data of a plurality of colors corresponding to a plurality of fields forming one frame period change at the same ratio.