Electrostatic Sensor Display with Guard Electrode for Touch Detection
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Solution Overview
Problem
Existing display devices face challenges in achieving high detection precision and sensitivity for multi-touch and close-proximity detection due to issues with lead line wiring, non-uniformity of detection electrodes, and parasitic capacitance, particularly when using ITO for lead lines, which affects the electrostatic capacitance-type sensor's performance.
Innovation Solution
The solution involves arranging detection electrodes in a matrix with lead lines formed of metal, providing a guard electrode to reduce parasitic capacitance, and employing a self-capacitive and mutual-capacitive sensing method to enhance detection precision and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ITO is used for lead lines in electrostatic capacitance-type sensors, then manufacturing costs are reduced and ease of manufacture is improved, but detection precision and sensitivity deteriorate due to increased parasitic capacitance
Solution Approach 1:
A guard electrode is introduced as an intermediary element between the lead lines and the detection electrodes. This guard electrode acts as a shield that reduces parasitic capacitance formed between the ITO lead lines and detection electrodes, thereby improving detection precision while maintaining the use of cost-effective ITO materials for lead lines
2Ease of manufacture
If ITO is used for lead lines in electrostatic capacitance-type sensors, then manufacturing costs are reduced, but detection sensitivity deteriorates due to parasitic capacitance
Solution Approach 1:
The guard electrode serves as a protective intermediary that reduces parasitic capacitance effects, enabling the use of inexpensive ITO lead lines without sacrificing detection sensitivity. The guard electrode is positioned to shield the detection electrodes from capacitive coupling with the lead lines
3Measurement precision
If detection electrodes are arranged in a matrix with metal lead lines, then detection precision is improved, but device complexity increases due to additional guard electrode structure
Solution Approach 1:
The guard electrode is merged with the existing pixel electrode structure of the display panel. By utilizing the pixel electrode as the guard electrode, the invention reduces device complexity while maintaining the benefits of reduced parasitic capacitance and improved detection precision
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 display devices to accurately detect input position information with improved sensitivity, allowing for multi-touch and close-proximity detection while maintaining device thickness and reducing manufacturing costs.
Implementation Method 1
detects a variation in electrostatic capacitance. Thus, the display device can detect position information of an input location by extracting a variation in electrostatic capacitance (strength/weakness of electrostatic capacitive coupling)
Implementation Method 2
providing a guard electrode to reduce parasitic capacitance
Data Source
AI summary
According to one embodiment, an electrostatic capacitance-type sensor-equipped display device includes a display panel with a display surface which displays an image. The sensor includes a plurality of detection electrodes disposed in a matrix, the detection electrodes being mutually electrically independently provided above the display surface and being configured to detect a variation in electrostatic capacitance, and a plurality of lead lines provided above the display surface, connected to the detection electrodes in a one-to-one correspondence, and formed of a metal.