Touch Sensor Dummy Electrodes for Reflectivity Uniformity
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Solution Overview
Problem
Touch sensors in display devices often suffer from display defects such as spots due to differences in reflectivity between sensor electrodes and their peripheral regions, which affect visibility and performance.
Innovation Solution
Incorporating dummy electrodes and lines with varying sizes and patterns adjacent to sensor electrodes, these elements are arranged to match the shape of sensor patterns and adjust based on distance from the touch driver, ensuring consistent reflectivity levels and reducing display defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor electrodes are arranged in a touch active region, then touch sensing function is achieved, but display defects such as spots occur due to reflectivity differences between sensor electrodes and peripheral regions
Solution Approach 1:
Dummy electrodes are selectively arranged only in specific regions adjacent to sensor electrodes where reflectivity differences cause display defects. The dummy electrodes have different reflectivity characteristics than the sensor electrodes, creating local quality variation that compensates for the reflectivity difference between sensor electrodes and peripheral regions, thereby eliminating spots while maintaining touch sensing function.
Solution Approach 2:
The dummy electrodes are designed with different optical properties (reflectivity) compared to the sensor electrodes. By adjusting the optical characteristics of the dummy electrodes, the overall reflectivity distribution in the touch active region is optimized, reducing visible spots caused by reflectivity differences between sensor electrodes and surrounding areas.
2Object-affected harmful factors
If dummy electrodes are arranged adjacent to sensor electrodes, then display defects are reduced, but device complexity increases
Solution Approach 1:
Instead of uniformly distributing dummy electrodes across the entire touch active region, they are selectively placed only in specific local areas adjacent to sensor electrodes where reflectivity differences cause display defects. This localized approach reduces the number of dummy electrodes needed, thereby minimizing the increase in device complexity while still effectively addressing display defects.
3Reliability
If sensor lines are extended to connect sensor electrodes to touch driver, then electrical coupling is achieved, but reflectivity differences and display defects worsen
Solution Approach 1:
Dummy electrodes are strategically positioned adjacent to sensor lines and sensor electrodes in regions where they cause display defects. The dummy electrodes compensate for the reflectivity differences introduced by the sensor lines, creating local optical quality adjustments that maintain overall display uniformity while preserving the necessary electrical coupling between sensor electrodes and touch driver.
Data Source
AI summary
A touch sensor includes: a plurality of sensor electrodes formed in a touch active region to form a plurality of sensor patterns; a plurality of sensor lines coupled to the respective sensor electrodes; a touch driver at one side of the touch active region, the touch driver being electrically coupled to the sensor electrodes respectively through the sensor lines; and dummy electrodes respectively arranged at one sides of the sensor electrodes, corresponding to the sensor lines.