LTPS LCD Bright Dot Repair via Femtosecond Laser and Tungsten Deposition
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Solution Overview
Problem
In liquid crystal display panels, particularly those with low-temperature polysilicon (LTPS) technology, the lack of overlapping areas between pixel and common electrodes renders existing methods for darkening bright dots or lines ineffective, leading to high scrap rates due to uncontrolled bright dots and lines during manufacturing.
Innovation Solution
A method involving the removal of a first electrode connected to a bridge between the pixel and data line using a femtosecond laser, followed by depositing tungsten atoms between the pixel and common electrodes using laser-assisted chemical vapor deposition to create a short circuit, ensuring zero voltage differential pressure and converting bright dots into dark dots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal layer between pixel electrode and common electrode is melted by sputtering to create a short circuit, then bright dots or lines can be darkened, but this method is no longer applicable when there is no overlapping area between the metal layers (as in LTPS TFT-LCD panels)
Solution Approach 1:
The patent extracts the essential function of creating a short circuit between pixel electrode and common electrode, but implements it through a different mechanism (laser-induced breakdown and metal deposition) rather than relying on pre-existing overlapping metal areas. This allows the solution to work even when traditional overlapping structures are absent.
Solution Approach 2:
The patent changes the approach from thermal melting (sputtering) to laser-induced breakdown and cold deposition. By altering the physical mechanism and parameters of the repair process, the method becomes applicable to LTPS panels where traditional overlapping structures no longer exist.
2Reliability
If bright dots or lines appear during manufacturing, the product is usually scrapped, but this brings great loss to the manufacturer
Solution Approach 1:
Instead of discarding panels with bright dots (scraping), the patent recovers them by applying a repair process that eliminates the defect. The laser repair method allows defective panels to be salvaged and converted into usable products, thereby reducing scrap rate and material loss.
Solution Approach 2:
The patent converts the harmful effect (bright dots causing scrap) into a benefit (opportunity for repair). By introducing laser-based repair, panels that would have been discarded become recoverable, turning a quality defect into a manageable issue that can be corrected.
3Manufacturing precision
If a femtosecond laser is used to remove the first electrode and deposit metal atoms, then the repair precision is improved, but the device complexity increases
Solution Approach 1:
The patent replaces traditional mechanical or thermal methods (sputtering, contact-based removal) with laser-based processes. The femtosecond laser provides precise, non-contact removal of the first electrode and simultaneous metal deposition, achieving high precision while eliminating the need for complex mechanical positioning and contact tools.
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 significantly reduces the scrap rate of liquid crystal display panels by ensuring all bright dots are converted into dark dots, thereby improving yield rates by maintaining zero differential pressure and preventing liquid-crystal molecule deflection.
Implementation Method 1
removing the first electrode connected to a bridge located between the pixel electrode and the data line by a femtosecond laser process
Implementation Method 2
depositing tungsten atoms between the pixel electrode and the common electrode using the laser assisted chemical vapor deposition process to form the metal film
Data Source
AI summary
The present invention provides a method and a device for repairing a bright dot in a liquid crystal display panel, and a liquid crystal display panel with bright dots repaired, wherein the method comprises the step of removing a first electrode connected to abridge located between a pixel electrode and a data line so that the voltage signal provided by the data line to the pixel electrode would be stopped. By the above-described process, the present invention is able to convert bright dots into dark ones, and thereby the scrap rate of a liquid crystal display panel can be reduced significantly which improves the yield rate of products.