Electro-optical Device Temperature-Adaptive Sub-field Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal devices face inaccuracies in grayscale display due to temperature-dependent response times, leading to potential grayscale reversal, especially when the number of displayed grayscales equals or exceeds the number of sub-fields.
Innovation Solution
An electro-optical device with a temperature-measuring unit and a time-controlling unit that adjust the length of sub-fields and the intensity of light incident on pixels to maintain constant display luminance, even as temperature changes, thereby preventing grayscale reversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of grayscales displayed equals or exceeds the number of sub-fields, then the grayscale resolution is improved, but the display accuracy deteriorates due to temperature-dependent response time variations
Solution Approach 1:
The patent applies dynamics by making the sub-field duration variable rather than fixed. The control unit adjusts the duration of each sub-field based on temperature-dependent response time characteristics of the liquid crystal. When temperature changes cause response time to increase, the sub-field duration is extended accordingly, ensuring that the liquid crystal has sufficient time to reach the desired transmittance state, thus preventing grayscale reversal while maintaining high grayscale resolution.
Solution Approach 2:
The patent changes the temporal parameter (sub-field duration) to compensate for temperature-induced variations in liquid crystal response time. By dynamically adjusting the sub-field duration parameter based on measured or predicted response time characteristics, the system maintains accurate grayscale display across different operating temperatures, resolving the contradiction between high grayscale resolution and display reliability.
2Measurement precision
If the sub-field duration is extended to accommodate slower liquid crystal response at low temperatures, then the grayscale accuracy is improved, but the frame rate deteriorates
Solution Approach 1:
The system dynamically adjusts sub-field duration based on actual temperature and response time characteristics rather than using a fixed conservative value. This allows the frame rate to be maximized at each temperature point, improving productivity while maintaining grayscale accuracy. The control unit calculates the minimum required sub-field duration based on response time measurements, ensuring sufficient time for liquid crystal transition without unnecessary extensions that would reduce frame rate.
Solution Approach 2:
The patent optimizes the sub-field duration parameter as a function of temperature and response time characteristics. By establishing an optimal parameter setting that provides just sufficient time for liquid crystal response at each temperature, the system achieves grayscale accuracy without excessive duration extensions that would compromise frame rate, thus resolving the contradiction between precision and productivity.
3Measurement precision
If the number of divided sub-fields is increased to display more grayscales, then the grayscale resolution is improved, but the time available for each sub-field decreases, worsening the response time issue
Solution Approach 1:
The patent makes the sub-field duration dynamic and temperature-dependent rather than fixed. When the liquid crystal response time increases due to low temperature, the control unit extends the duration of each sub-field accordingly. This dynamic adjustment ensures that even with a large number of sub-fields providing high grayscale resolution, each sub-field has sufficient time for the liquid crystal to respond, preventing grayscale reversal while maintaining high resolution.
Solution Approach 2:
The system changes the temporal parameter (sub-field duration) to compensate for the reduced time available when dividing the frame into many sub-fields. By adjusting the duration parameter based on temperature and response time characteristics, the patent ensures that each sub-field maintains adequate duration for liquid crystal response, thus resolving the contradiction between high grayscale resolution and sufficient response time.
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
This solution ensures stable grayscale display by controlling sub-field length and light intensity, maintaining constant transmittance alteration and preventing grayscale reversal across varying temperatures.
Implementation Method 1
a pixel that has an electro-optical element of which light transmittance changes in response to an applied voltage
Data Source
AI summary
An electro-optical device includes a pixel that has an electro-optical element with a light transmittance that changes to a predetermined value in response to an applied voltage, which changes in response to the temperature. A light source irradiates light to the pixel. A driving unit includes a predetermined number of sub-fields having the same length in one frame. The driving unit provides either an on-voltage indicating light-on or an off-voltage indicating light-off to the pixel in each of the predetermined number of the sub-fields in response to the grayscale to be displayed. A temperature measuring unit measures the temperature and outputs a temperature signal. A time controlling unit controls the length of one sub-field on the basis of the temperature signal. A light intensity controlling unit controls the intensity of the light incident on the pixel on the basis of the temperature signal.