Overdrive LUT Generation for LCD Response Time Compensation
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Solution Overview
Problem
Liquid crystal display (LCD) panels suffer from slow pixel response times, leading to video artifacts such as smearing and motion blur due to inadequate grey-to-grey transition times, which are exacerbated in portable Information Handling Systems (IHSs with limited power and design constraints.
Innovation Solution
The generation of an overdrive look-up table (LUT) for response time compensation, using numerical or definite integration techniques, which calculates alternate grey levels based on frame rate and image motion artifacts to optimize grey level response times and minimize overshoot/undershoot effects, thereby improving video quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If liquid crystal materials are used in LCD panels to enable electro-optical control, then the display can be controlled by voltage application, but the response time becomes slow due to material inertia
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal overdrive voltages for all possible grey level transitions in a lookup table before operation. During display, the system simply retrieves the pre-computed overdrive voltage from the LUT based on current and target grey levels, eliminating the need for real-time complex calculations and enabling fast response time compensation.
Solution Approach 2:
The patent changes the voltage parameter dynamically by applying overdrive voltages that are higher than standard driving voltages for grey-to-grey transitions. The system modifies the voltage magnitude based on the specific transition required, using elevated voltages to accelerate liquid crystal response time while managing overshoot through the pre-computed LUT values.
2Speed
If overdrive voltage is applied to accelerate grey-to-grey transitions, then response time improves, but video artifacts such as overshoot and smearing increase
Solution Approach 1:
The patent incorporates feedback by measuring the actual response time of grey-to-grey transitions and using this information to optimize the overdrive voltages stored in the lookup table. The system characterizes the specific LCD panel's response behavior and adjusts the LUT values accordingly, creating a closed-loop optimization that balances response time improvement with artifact reduction for the specific display hardware.
Solution Approach 2:
The patent applies partial overdrive action by selectively applying overdrive voltages only when grey-to-grey transitions are detected, rather than applying maximum overdrive to all pixels at all times. The LUT contains calibrated overdrive values that provide just enough acceleration to meet response time targets while minimizing overshoot and smearing artifacts through precise voltage control.
3Manufacturing precision
If manual tuning of overdrive voltages is performed to optimize response time, then video quality improves, but computational overhead and complexity increase
Solution Approach 1:
The patent implements self-service by providing automated tools that characterize the LCD panel's response properties and generate the optimized lookup table without requiring manual intervention. The system automatically measures grey-to-grey response times, calculates optimal overdrive voltages, and stores them in the LUT, enabling the display system to self-optimize its performance while simplifying the manufacturing and calibration process.
Solution Approach 2:
The patent applies preliminary action by pre-computing the entire lookup table with optimized overdrive voltages during manufacturing or initial setup, rather than requiring real-time or per-use tuning. This pre-computation captures all the optimization complexity in advance, allowing the display system to operate with simple LUT lookups during normal operation, significantly reducing computational overhead and complexity during actual use.
4Ease of manufacture
If standard black-to-white response time specifications are used, then vendor specifications are simplified, but grey-to-grey response times remain inadequate for video applications
Solution Approach 1:
The patent applies segmentation by dividing the single black-to-white response time specification into multiple grey-to-grey transition measurements across different grey level pairs. Instead of relying on one aggregate metric, the system characterizes response times for specific transitions (e.g., 50 to 150, 100 to 200) and uses this segmented data to create targeted overdrive strategies for different transition types in the lookup table.
Solution Approach 2:
The patent changes the measurement parameter from the conventional black-to-white transition to multiple grey-to-grey transitions that are more representative of actual video content. By measuring and optimizing for grey-to-grey response times across different grey level pairs, the system achieves better correlation with perceived video quality while maintaining manageable specification requirements through the automated LUT generation process.
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 approach automatically balances response time and image quality, reducing manual tuning requirements and computational overhead, while providing customizable response times tailored to user preferences, thus enhancing the user experience and reducing video artifacts.
Implementation Method 1
By applying voltage to the transparent electrodes over each pixel, the corresponding liquid crystal molecules are 'twisted' by electrostatic forces, allowing varying degrees of light to pass through the polarizing filters.
Implementation Method 2
Due to their electro-optical nature, the liquid crystal materials used in LCD panels have inertia and cannot be switched instantaneously.
Data Source
AI summary
Systems and methods are provided for generating an overdrive look-up table (LUT) for response time compensation of a display device are described. In some embodiments, an Information Handling System (IHS) may include a controller and a memory coupled to the controller, the memory having program instructions stored thereon that, upon execution, cause the controller to generate a Look-up Table (LUT) of alternate grey levels selected to implement Response Time Compensation (RTC) in a Liquid Crystal Display (LCD), where at least one of the alternate grey levels is calculated, at least in part, by taking into account a frame rate of a video stream.