Liquid Crystal Display Intermittent Driving Power Reduction
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Solution Overview
Problem
Liquid crystal display devices, particularly in mobile terminals, face challenges in reducing power consumption while maintaining image quality, as existing drive schemes like low-frequency and intermittent driving can cause image blur and increased risk of flicker or image burn-in.
Innovation Solution
A liquid crystal display device with a control circuit that switches between ordinary and intermittent driving modes, incorporating a driver idle period to reduce power consumption, and using switching elements with low off-leakage current, such as TFTs with IGZO, to manage pixel electrode polarities effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If intermittent driving is used to reduce power consumption, then power consumption is reduced, but image blur may occur due to low rewriting frequency
Solution Approach 1:
The patent implements intermittent driving by periodically stopping the liquid crystal display unit after a single frame is written, reducing power consumption while maintaining image quality through carefully controlled periodic operation cycles
2Use of energy by moving object
If low-frequency drive scheme is used to reduce power consumption, then power consumption is reduced, but moving images may exhibit blur due to low rewriting frequency
Solution Approach 1:
The patent employs periodic action by implementing intermittent driving mode where the liquid crystal display unit operates at full frequency for one frame then stops for multiple frames, achieving power reduction without continuous low-frequency operation that would cause blur
3Use of energy by moving object
If frame inversion is used to reduce power consumption, then power consumption is reduced, but flicker easily occurs due to same polarity across entire screen
Solution Approach 1:
The patent applies segmentation by dividing the screen into multiple scan lines and implementing line inversion or dot inversion instead of frame inversion, ensuring different polarity regions across the screen to prevent flicker while maintaining low power consumption
4Reliability
If line inversion or dot inversion is used to write on pixels, then image quality is improved, but source lines must be charged and discharged at intervals of 1 H period increasing power consumption
Solution Approach 1:
The patent resolves this contradiction by using intermittent driving where source lines are charged and discharged only during the single active frame period, then the display unit stops for multiple frames, dramatically reducing the frequency of charging/discharging operations compared to continuous line or dot inversion
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 reduces the average power consumption of the circuit by up to ½ or ¼ while minimizing the risk of image blur and flicker, especially during still image display, and reduces the visibility of vertical streaks caused by luminance differences.
Implementation Method 1
an alignment direction of liquid crystal molecules included in a liquid crystal layer held between an upper substrate and a lower substrate is controlled by a vertical electric field generated between the common electrode and the pixel electrodes
Implementation Method 2
an alignment direction of liquid crystal display molecules included in a liquid crystal layer is controlled by an electric field (fringe electric field) generated between the common electrode and the pixel electrodes
Data Source
AI summary
According to one embodiment, a liquid crystal display device includes a first substrate, a second substrate, a liquid crystal layer, a driver and a control circuit. The control circuit is configured to cause the driver to carry out one of an ordinary driving and an intermittent driving, which is set by switching. The control circuit supplies signals to a plurality of pixel electrodes of each of columns of the pixel electrodes in each of frame periods in the intermittent driving, the supplied signals having polarities inverted in units of at least one row.