Liquid Crystal Display Alignment Film Time Constant Management
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Solution Overview
Problem
Low-frequency drive in liquid crystal display devices leads to conspicuous flicker due to prolonged voltage holding periods, causing luminance degradation and power consumption issues, as the frequency reduction results in increased off-leak currents from thin-film transistors, which are not effectively managed by existing technologies.
Innovation Solution
A liquid crystal display device configuration with a first alignment film and a liquid crystal layer where the time constant of the liquid crystal layer is larger than that of the first alignment film, forming a lateral electric field to suppress voltage variation and flicker, while maintaining power efficiency through intermittent drive schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the drive frequency is lowered to reduce power consumption, then power consumption is reduced, but flicker becomes conspicuous due to voltage degradation
Solution Approach 1:
The invention segments the capacitance function by introducing a first alignment film with specific dielectric properties between the pixel electrode and liquid crystal layer. This creates a distributed capacitance system where the alignment film capacitance compensates for voltage drops, allowing low-frequency drive without flicker while reducing power consumption.
Solution Approach 2:
The invention changes the dielectric constant parameter of the alignment film to optimize the time constant. By selecting an alignment film with a dielectric constant of 3.0 or less, the system achieves optimal voltage holding characteristics at low frequencies, enabling power consumption reduction without sacrificing display quality.
2Use of energy by moving object
If the drive frequency is lowered to reduce power consumption, then power consumption is reduced, but luminance degradation occurs due to off-leak current
Solution Approach 1:
The capacitance function is segmented between the liquid crystal layer and the first alignment film. The alignment film acts as a separate capacitance element that maintains voltage during the holding period, preventing luminance degradation from off-leak currents while enabling extended hold times at low frequencies.
Solution Approach 2:
The first alignment film serves as an intermediary element between the pixel electrode and liquid crystal layer. It mediates the voltage holding function by providing additional capacitance that compensates for charge leakage, thereby maintaining luminance stability during low-frequency drive cycles.
3Reliability
If the time constant of the liquid crystal layer is increased to improve voltage holding, then voltage holding improves, but response time increases
Solution Approach 1:
The time constant function is segmented between the liquid crystal layer and the first alignment film. The alignment film provides a shorter time constant for rapid response, while the liquid crystal layer maintains the primary voltage holding function, achieving both fast response and stable voltage holding.
Solution Approach 2:
The system uses dynamic time constant management by having two distinct time constants - a shorter one from the alignment film for rapid voltage establishment and a longer one from the liquid crystal layer for sustained voltage holding. This dynamic separation allows optimal performance in both response and holding phases.
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 configuration effectively suppresses flicker and maintains display quality by ensuring voltage stability even at low frequencies, reducing power consumption without compromising image quality, as demonstrated by simulations and test cell evaluations.
Implementation Method 1
a time constant of the liquid crystal layer is larger than a time constant of the first alignment film
Implementation Method 2
the voltage of the liquid crystal cannot be held and the luminance of the liquid crystal is degraded
Implementation Method 3
A lateral electric field is formed between the pixel electrode and the common electrode
Implementation Method 4
a liquid crystal layer, a first alignment film, a pixel electrode and a common electrode
Data Source
AI summary
According to one embodiment, a display device includes a first substrate, a second substrate, a liquid crystal layer, a first alignment film, a pixel electrode, and a common electrode. The liquid crystal layer is disposed between the first substrate and the second substrate. The first alignment film is provided on the first substrate to be in contact with the liquid crystal layer. The pixel electrode is provided on the first substrate and covered with the first alignment film. The common electrode provided on the first substrate to form a lateral electric field. The liquid crystal layer is driven at a frequency of 40 Hz or less. A time constant of the liquid crystal layer is larger than a time constant of the first alignment film.