Liquid Crystal Display Device with Oxide Semiconductor and Low Frame Rate
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Solution Overview
Problem
Liquid crystal display devices face challenges in reducing power consumption and flicker when driven at low frequencies, primarily due to low voltage holding ratio and flexo-polarization effects caused by impurity ions and off-leakage currents.
Innovation Solution
A liquid crystal display device with a transverse electric field mode, utilizing substrates with photo-alignment films, oxide semiconductor TFTs, and a liquid crystal layer containing bicyclohexyl and difluorobenzene skeletons, which reduces impurity ion solubility and flexo-polarization, and features a frame rate lower than 50 Hz to minimize power consumption and flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the frame rate is decreased to reduce power consumption, then power consumption is reduced, but flicker occurs due to low voltage holding ratio and flexo-polarization
Solution Approach 1:
The patent changes the chemical composition parameters of the liquid crystal material by incorporating specific compounds (cyclic carbonate compounds and/or cyclic carboxylate compounds) with defined molecular structures. This composition modification reduces impurity ion content and minimizes flexo-polarization effects, enabling stable display at low frame rates below 50Hz while maintaining high voltage holding ratio and eliminating flicker
Solution Approach 2:
The patent creates a composite liquid crystal system by combining conventional liquid crystal compounds with specific cyclic carbonate and/or cyclic carboxylate compounds. This composite material approach leverages the unique properties of the cyclic compounds to suppress ion migration and flexo-polarization, resolving the contradiction between low power consumption operation and flicker-free display
2Reliability
If impurity ions move within the liquid crystal layer, then voltage holding ratio decreases, but this causes luminance change perceived as flicker
Solution Approach 1:
The patent modifies the liquid crystal composition by adding cyclic carbonate and/or cyclic carboxylate compounds that chemically suppress impurity ion mobility. This parameter change in composition reduces ion migration within the liquid crystal layer, maintaining high voltage holding ratio and preventing luminance changes that would be perceived as flicker during low frequency operation
3Reliability
If the pre-tilt angle is set high or liquid crystal alignment is asymmetric, then flexo-polarization occurs, but this causes luminance change perceived as flicker
Solution Approach 1:
The patent changes the liquid crystal material composition by incorporating cyclic carbonate and/or cyclic carboxylate compounds that reduce the magnitude of flexo-polarization effects. This compositional parameter change minimizes the coupling between electric field and polarization, thereby reducing luminance changes caused by flexo-polarization even when operating at high pre-tilt angles or with asymmetric alignment, eliminating flicker during low frequency driving
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 power consumption and flicker in liquid crystal display devices by enhancing voltage holding ratio and minimizing flexo-polarization, while maintaining reliable display characteristics.
Implementation Method 1
the polymer layer is formed by polymerization of a monomer added to the liquid crystal layer
Implementation Method 2
polarization by the flexo-electric effect (hereinafter, the polarization is referred to as flexo-polarization) in the liquid crystal layer
Data Source
AI summary
The present invention provides a liquid crystal display device with reduced power consumption as well as reduced flicker. The liquid crystal display device is one in a transverse electric field mode, including: paired substrates; a photo-alignment film disposed on at least one of the substrates; a horizontal alignment liquid crystal layer disposed between the substrates; and pixels arranged in a matrix form, the liquid crystal layer containing liquid crystal molecules with a bicyclohexyl skeleton and liquid crystal molecules with a difluorobenzene skeleton, the liquid crystal layer having negative anisotropy of dielectric constant, one of the substrates including TFTs disposed in the respective pixels, the TFTs each including a semiconductor layer that contains an oxide semiconductor, the liquid crystal display device having a frame rate of lower than 50 Hz.