Liquid Crystal Display Polarity Control Circuit Reducing Power Consumption
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Solution Overview
Problem
Liquid crystal display devices face increased power consumption due to high driving frequencies and screen sizes, particularly with inversion driving methods that change the polarity of data signals every frame period, leading to higher voltage changes and energy usage.
Innovation Solution
A liquid crystal display device with a control circuit that generates a polarity control signal to maintain or invert the data signal polarity every m frame periods, reducing the frequency of voltage changes and allowing for intermittent rewriting of pixels during still images, thereby minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inversion driving is performed every frame period to prevent burn-in, then liquid crystal deterioration is prevented, but power consumption increases due to large voltage changes
Solution Approach 1:
The patent applies periodic action by inverting the polarity of data signals at regular intervals (every m frame periods) rather than continuously. The polarity inversion is performed periodically based on a control signal that changes at predetermined timings, reducing the frequency of voltage changes while maintaining liquid crystal element durability through regular polarity alternation.
2Manufacturing precision
If driving frequency is increased to achieve higher display quality, then display performance improves, but power consumption increases
Solution Approach 1:
The patent reduces power consumption at high driving frequencies by implementing periodic polarity inversion every m frame periods. This approach allows the display to maintain high refresh rates for quality display while reducing the frequency of voltage changes that consume power, creating a periodic pattern of high and low power states.
Solution Approach 2:
The patent changes the parameter of polarity inversion frequency by introducing a control signal that inverts polarity every m frame periods instead of every frame period. This parameter change reduces the effective inversion frequency by a factor of m, thereby reducing power consumption while maintaining display quality through the higher base driving frequency.
3Reliability
If data signal polarity is changed every frame period, then burn-in is prevented, but voltage change amount increases leading to higher power consumption
Solution Approach 1:
The patent applies periodic action by changing the polarity of data signals at regular intervals determined by a control signal that inverts every m frame periods. This periodic inversion maintains display uniformity by preventing burn-in through polarity alternation while reducing the frequency and magnitude of voltage changes compared to frame-by-frame inversion.
Data Source
AI summary
Power consumed in a liquid crystal display device owing to inversion driving is reduced. A control circuit generates a polarity control signal whose potential level is switched at intervals of two or more frame periods. A data line driver circuit processes an image signal to generate a data signal. The data signal has a polarity corresponding to the potential level of the polarity control signal. The control circuit stops output of the image signal to the data line driver circuit when determining that there is no motion in data of the image signal. The control circuit controls a scan line driver circuit and the data line driver circuit, thereby performing, in response to a change in the potential level of the polarity control signal, rewriting of a display portion at least in one frame period during a period in which the output of the image signal is stopped.