Bezel Capacitance Sensing for Display Cell Gap Monitoring
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Solution Overview
Problem
Existing display devices lack the capability to measure and monitor the cell gap in the bezel area, which can lead to defects such as yellow mura or bright spots due to external forces, and there is no effective method to quantify stress on the display panel.
Innovation Solution
The display device incorporates a capacitance sensing structure in the bezel area by using first and second electrodes with a second liquid crystal layer between them, allowing for capacitance measurement and monitoring of the cell gap, which includes a first and second sealant and spacers of different heights to maintain varying cell gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional single sealant structure is used, then the manufacturing process is simple, but the cell gap cannot be measured and monitored in the bezel area
Solution Approach 1:
The sealant structure is divided into two distinct parts: a first sealant for sealing the liquid crystal layer and a second sealant for creating a measurement region. This segmentation allows the second sealant to form a capacitance sensor that measures cell gap in the bezel area, while the first sealant maintains the liquid crystal enclosure, thus enabling measurement capability without compromising the overall sealing function.
Solution Approach 2:
The second sealant serves dual functions: it acts as a sealing element for the measurement region and simultaneously forms part of a capacitance sensing structure (with the first sealant and liquid crystal layer) that enables cell gap measurement. This multi-functionality allows a single component to provide both structural and measurement capabilities.
2Reliability
If no capacitance sensing structure is implemented, then the device structure remains simple, but real-time monitoring of cell gap and stress is not possible
Solution Approach 1:
The capacitance sensing structure is built into the device during manufacturing, with electrodes and sealants positioned to create measurement regions before the device is put into service. This preliminary setup enables continuous real-time monitoring of cell gap and stress throughout the device's operational life, allowing for early detection of potential defects.
Solution Approach 2:
The capacitance sensing structure provides continuous feedback on cell gap variations and stress conditions in the bezel area. By monitoring capacitance changes between the first and second sealants, the system can detect deviations from normal operating conditions, enabling real-time quality control and defect prevention.
3Measurement precision
If the bezel area is not used for measurement, then the display area is maximized, but the cell gap cannot be monitored in the non-display region
Solution Approach 1:
The measurement capability is applied locally to the bezel area through the second sealant and associated electrodes, while the main display area remains unaffected. This localized approach allows cell gap monitoring specifically in the non-display region without interfering with the display functionality or requiring additional space that would reduce the effective display area.
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
Enables real-time monitoring of capacitance changes during the module process, improving reliability by preventing image defects and allowing for quantitative stress analysis on the display panel.
Implementation Method 1
a second electrode disposed over the second substrate in the non-display area and configured to define a capacitance together with the first electrode, for measuring and monitoring a cell gap in a bezel area
Data Source
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AI summary
A display device according to an embodiment of the present disclosure may include a first substrate including a display area and a non-display area, a second substrate attached to the first substrate in a state in which a first sealant is disposed, a first liquid crystal layer disposed inside the first sealant, a second sealant disposed outside the first sealant, a second liquid crystal layer disposed between the first sealant and the second sealant, a first electrode disposed over the first substrate in the non-display area, and a second electrode disposed over the second substrate in the non-display area and configured to define a capacitance together with the first electrode, thereby measuring and monitoring a cell gap in a bezel area.