Transparent Display Ghosting Reduction via Scan Line Overlap
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Solution Overview
Problem
Transparent displays using the field-sequential system experience ghosting due to high voltage-driven pixels, where electric charges are not sufficiently discharged, causing high potentials to be maintained in low-voltage pixels, leading to image artifacts.
Innovation Solution
A display device with a signal processing circuit that adjusts pixel gradation values by overlapping gate-on periods of scan lines and using a signal line drive circuit to supply gradation signals, ensuring that pixels driven at high voltages are properly discharged, reducing ghosting effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gate-overlap drive is used to increase definition, then pixel resolution is improved, but ghosting occurs due to insufficient discharge of electric charges in low-voltage pixels
Solution Approach 1:
The patent applies preliminary action by adjusting the pixel gradation value of pixels in the second scan line before they are driven, based on the gradation values of pixels in the first scan line. This pre-adjustment compensates for the residual charge effects that would otherwise cause ghosting, allowing gate-overlap drive to maintain both high resolution and clean images without requiring additional hardware discharge circuits.
2Illumination intensity
If high voltage is applied to text information pixels, then text visibility is improved, but electric charges are not sufficiently discharged from low-voltage pixels, causing potential retention
Solution Approach 1:
The patent changes the parameter of pixel gradation value dynamically based on the driving voltage requirements. When a pixel in the second scan line is to be driven at high voltage, its gradation value is adjusted according to the average gradation value and difference value calculations, ensuring that the liquid crystal molecules are properly prepared for high-voltage driving without retaining unwanted residual charges from previous low-voltage states.
3Duration of action of moving object
If scan line selection periods are overlapped, then light emission period is extended, but ghosting occurs due to simultaneous high voltage application to overlapping pixels
Solution Approach 1:
The patent applies local quality by treating pixels in different scan lines differently through the signal processing circuit. Pixels in the second scan line that correspond to pixels in the first scan line undergo special gradation value adjustment, while other pixels maintain normal driving. This localized adjustment eliminates ghosting only where needed, preserving the benefits of gate-overlap drive for extending light emission duration.
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 effectively reduces ghosting in transparent displays by ensuring that high-voltage pixels are adequately discharged, improving image clarity and reducing artifacts.
Implementation Method 1
a liquid crystal layer including polymer-dispersed liquid crystals filled between the first and the second light-transmitting substrates
Data Source
AI summary
A display device includes: a display panel having a display region in which pixels are arranged; scan lines each coupled to the pixels arranged in a row direction; signal lines each coupled to the pixels arranged in a column direction; a signal line drive circuit; a scan line drive circuit selecting the scan lines; and a signal processing circuit. A second half period of a selection period of a first scan line overlaps a first half period of a selection period of a second scan line. The signal processing circuit adjusts a pixel gradation value of the pixel in an m-th column coupled to the second scan line when a difference value between the pixel gradation value of the pixel in the m-th column coupled to the first scan line and an average gradation value of the pixels arranged in the m-th column is larger than a predetermined value.