LCD Signal Controller Dithering for Color Reproducibility
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Solution Overview
Problem
Conventional liquid crystal display (LCD) technologies compromise color reproducibility and image quality by reducing the number of gray levels to match lower-bit data processing capabilities, leading to decreased manufacturing costs but inferior display performance.
Innovation Solution
A liquid crystal display device that includes a signal controller storing dithering data patterns, converting high-bit input image data into lower-bit output data using these patterns, and a data driver applying corresponding voltages, with dithering data patterns repeated every eight frames at a frequency of 120 Hz to enhance color representation and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dithering is applied to convert 13-bit image data into 10-bit data for cost reduction, then manufacturing cost decreases, but color reproducibility is compromised and the number of representable colors decreases
Solution Approach 1:
The patent applies periodic action by repeating dithering data patterns every eight frames at a frequency of 120 Hz. This temporal repetition allows the display to maintain the illusion of higher bit depth through persistence of vision, effectively recovering color reproducibility that would otherwise be lost in simple 13-bit to 10-bit conversion. The periodic refresh at high frequency prevents flicker while preserving color information.
Solution Approach 2:
The patent transitions from spatial dithering only to temporal-spatial dithering by utilizing the time dimension through high-frequency frame repetition. This adds a temporal dimension to the dithering process, allowing color information to be distributed across both space and time, thereby recovering color reproducibility while maintaining cost benefits of 10-bit processing.
2Ease of manufacture
If the number of bits representing image data is reduced from 13-bit to 10-bit, then manufacturing cost decreases, but the number of gray levels and representable colors decreases
Solution Approach 1:
By repeating dithering patterns at 120 Hz across eight frames, the system uses temporal periodicity to encode additional color information that cannot be represented in a single 10-bit frame. The human visual system integrates these rapid temporal variations, perceiving a broader color gamut equivalent to higher bit depth.
Solution Approach 2:
The dithering data pattern acts as an intermediary that encodes additional color information within the constraints of 10-bit data. By modulating pixel values according to predefined patterns across multiple frames, the system effectively transmits more color information than the raw 10-bit data would suggest.
3Manufacturing precision
If dithering data patterns are repeated every eight frames at 120 Hz, then color reproducibility is improved and image quality is enhanced, but system complexity increases
Solution Approach 1:
The dithering data patterns are pre-calculated and stored in advance, allowing the display system to simply lookup and apply predetermined patterns rather than performing complex real-time calculations. This preliminary preparation reduces runtime computational complexity while maintaining high image quality.
Solution Approach 2:
The system changes the parameter of frame repetition count to exactly eight frames, which corresponds to the period required to display all variations of the dithering pattern at 120 Hz. This specific parameter optimization balances image quality improvement with manageable system complexity.
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 improves color reproducibility and overall image quality by increasing the number of representable colors while maintaining high frame frequencies, preventing image quality deterioration such as flicker, thus offering a better display experience.
Implementation Method 1
a liquid crystal (LC) layer with dielectric anisotropy that is interposed between the two panels
Implementation Method 2
the pixel electrode and the common electrode generate an electric field in the LC layer when a voltage is applied. Light transmittance through the LC layer is adjusted by controlling the strength of the electric field
Implementation Method 3
The dithering represents high-bit data as low-bit data, and translates their temporal and spatial arrangements to fit the 10-bit data format
Data Source
AI summary
A liquid crystal display with improved color reproducibility and image quality is presented. The liquid crystal display includes a liquid crystal panel assembly including a plurality of pixels, a signal controller, and a data driver. The signal controller stores a dithering data patterns, selects one of the dithering data patterns based on input image data having a first bit number, and converts the input image data to output image data having a different bit number using the selected dithering data pattern. The data driver applies data voltages to the pixels, the data voltages corresponding to the output image data from the signal controller. Frequency of the input image signal and the output image signal from the signal controller is each about 120 Hz, and the dithering data patterns are repeated every eight frames. The signal controller includes a look-up table that stores the dithering data patterns.