LCD Gray Level Control via Sub-Frame Timing and Gamma Voltage
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Solution Overview
Problem
Existing LCD devices face challenges in realizing gray levels due to increased driver IC size and high power consumption, particularly when using resistor strings and digital operation schemes, which require high-speed driver ICs and additional components.
Innovation Solution
The method involves dividing the liquid crystal response time into sequential sub-frames, applying a gamma voltage during specific sub-frames, and adjusting the amount of light by controlling the blank time interval and the level of the gamma voltage, allowing for adjustable sub-frame timing to achieve various gray levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a D/A converter and buffer are installed in the driver IC to adjust gamma curve using resistor string, then gray level realization precision is improved, but driver IC size increases
Solution Approach 1:
The patent extracts the D/A converter and buffer components from the driver IC, moving them to external components. The driver IC only needs to output digital signals to control the liquid crystal, while the actual voltage conversion and buffering are performed externally, thereby reducing the driver IC size while maintaining gray level precision
Solution Approach 2:
The patent uses a lookup table (LUT) to store pre-calculated gray level voltage values, replacing the need for real-time D/A conversion. The LUT contains mapping relationships between digital input values and corresponding analog voltage levels, allowing the system to achieve precise gray level control through simple table lookup and external D/A conversion
2Adaptability or versatility
If digital operation scheme with multiple sub-frames is used to realize gray levels, then gray level control flexibility is improved, but power consumption increases due to high-speed driver IC operation
Solution Approach 1:
The patent divides the display frame into multiple sub-frames, applying different digital values to the liquid crystal in each sub-frame. By controlling which sub-frames are activated and their durations, the system achieves precise gray level control through periodic switching, reducing the need for continuous high-speed operation and lowering power consumption
Solution Approach 2:
The patent pre-calculates and stores optimal sub-frame combinations and durations in a lookup table for each desired gray level. This preliminary preparation allows the driver IC to simply retrieve and execute pre-determined control patterns, reducing computational burden and operating speed requirements during actual display operation
3Speed
If high-speed driver IC is used for digital operation scheme, then response time is improved, but device complexity increases
Solution Approach 1:
The patent segments the frame period into multiple sub-frames, allowing the liquid crystal to be driven in discrete time intervals. This segmentation enables precise control of liquid crystal response timing without requiring the entire system to operate at ultra-high speeds, as each sub-frame can be optimized independently for the specific gray level being displayed
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 reduces the size and power consumption of the driver IC while enabling the realization of multiple gray levels by optimizing the sub-frame timing and voltage levels, enhancing the efficiency of gray level realization in LCD devices.
Implementation Method 1
a voltage having a predetermined intensity is applied to the liquid crystal in order to adjust a liquid crystal layer transmission rate of the background light source according to the degree of twist of the liquid crystal
Data Source
AI summary
Disclosed is a method for realizing gray levels of a liquid crystal display (LCD) device, which realize various gray levels by interworking a gamma voltage and a sub-frame. The method includes the steps of dividing a liquid crystal response time interval for a pixel during one frame into n sequential sub-frames, enabling the pixel and applying a gamma voltage having a fixed level to the pixel, filling electric charges in the pixel by using the gamma voltage during each of the n specific sub-frames, and disabling the pixel at an end time point of a predetermined ith sub-frame, the i being an integer, wherein an amount of light projected on the pixel is adjusted by regulating a time point at which the pixel is disabled during each of the n specific sub-frames.