In-Cell Touch LCD Calibration Circuit for Short-Circuit Detection
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Solution Overview
Problem
In-cell type liquid crystal display devices with built-in touch panels face inefficiencies in calibrating cross capacity and detecting adjacent short-circuit failures between detection electrodes, which prolongs production time and increases susceptibility to noise and static electricity.
Innovation Solution
A calibration circuit is implemented to adjust the charge extraction by applying specific calibration voltages to detection electrodes, allowing for efficient calibration of cross capacity and detection of short-circuit failures between adjacent electrodes, including those on flexible wiring substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If point inspection is conducted for each intersection between scanning electrodes and detection electrodes to detect adjacent short-circuit failure, then detection accuracy is improved, but inspection time increases significantly, deteriorating production efficiency
Solution Approach 1:
The detection process is segmented into two distinct modes: a rapid metal plate inspection that covers the entire touch panel surface, and a targeted adjacent electrode short-circuit inspection that focuses only on specific electrode intersections. This segmentation allows the system to maintain high detection accuracy for short-circuit failures while avoiding the need to perform exhaustive point inspections across all intersections, thereby preserving production efficiency.
Solution Approach 2:
The metal plate inspection is performed as a preliminary step before the adjacent electrode short-circuit inspection. By first conducting the rapid metal plate inspection to identify areas of interest, the system can then focus subsequent detailed inspections only on specific regions where short-circuit failures are suspected, rather than inspecting every intersection uniformly. This preliminary action significantly reduces the overall inspection time while maintaining detection accuracy.
2Productivity
If metal plate inspection is used to quickly inspect the touch panel, then inspection time is reduced, but adjacent short-circuit failure between detection electrodes cannot be detected
Solution Approach 1:
The patent merges two previously separate inspection methods into a unified inspection system that performs both metal plate inspection and adjacent electrode short-circuit inspection. The calibration circuit is designed to execute both functions sequentially or in combination, allowing the system to benefit from the speed of metal plate inspection while simultaneously achieving the detection capability of point inspection for adjacent short-circuit failures.
Solution Approach 2:
The calibration circuit is designed with multi-functionality to perform both the rapid metal plate inspection and the detailed adjacent electrode short-circuit inspection. By integrating these two functions into a single calibration circuit, the system achieves universal inspection capability that can adapt to different inspection needs without requiring separate dedicated inspection systems, thereby maintaining both speed and detection accuracy.
3Reliability
If open short-circuit inspection with test pad is used, then detection capability is improved, but susceptibility to noise and static electricity increases
Solution Approach 1:
The patent introduces the calibration circuit as an intermediary mechanism that enables short-circuit detection without requiring external test pads. The calibration circuit uses internal calibration electrodes and calibration voltages to perform the inspection, acting as an intermediary between the detection electrodes and the inspection process. This eliminates the need for external test pads that are susceptible to noise and static electricity, while maintaining the ability to detect open and short-circuit failures.
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 enables rapid detection of adjacent short-circuit failures and efficient calibration of cross capacity, improving production efficiency and reducing noise susceptibility, thus enhancing the performance of in-cell type liquid crystal display devices with built-in touch panels.
Implementation Method 1
The cross capacity Cxy has to be calibrated because of individual difference and variation in the plane resulting from variation and non-uniformity in permittivity and thickness of the liquid crystal layers
Implementation Method 2
an electrostatic capacity system for detecting change in the capacity of the touched area has been known
Data Source
AI summary
A liquid crystal display device with a plurality of pixels arranged in a matrix includes a first substrate, a second substrate, a liquid crystal interposed between the first and the second substrates, and a detection circuit. The second substrate includes a detection electrode for a touch panel. The respective pixels have pixel electrodes and counter electrodes. The counter electrode divided into a plurality of blocks is provided common to the respective pixels on a plurality of consecutive display lines. The counter electrode divided into blocks serves as the scanning electrode for the touch panel. The detection circuit includes a calibration capacity element provided for each of the detection electrodes, is having one end connected to the detection electrode, and supplies a calibration voltage to the other end of the calibration capacity element in a touched position detection process.