In-Cell Touch Panel Using Photo-Sensitive Diodes to Eliminate Parasitic Capacitance
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Solution Overview
Problem
In-cell touch panels face interference between touch detection signals and display signals due to parasitic capacitance, affecting the quality of touch operation detection.
Innovation Solution
Integration of photo-sensitive sensing units, comprising photo-sensitive diodes and switching transistors, within the display panel to detect light intensity changes, allowing for interference-free touch detection without affecting display signals, and enabling fingerprint identification by optimizing the pitch between diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitance and induction methods are used for touch detection inside the display panel, then touch detection function is achieved, but parasitic capacitance causes interference between touch detection signals and display signals
Solution Approach 1:
The patent extracts the touch detection function from the traditional capacitance-based in-cell structure and implements it using photo-sensitive sensing units that detect light intensity changes. This separates the touch detection mechanism from the display signal transmission path, eliminating parasitic capacitance interference while maintaining touch detection capability.
Solution Approach 2:
The patent replaces the electrical capacitance-based detection system with an optical detection system using photo-sensitive diodes. This substitution changes the detection principle from electrical field interaction to light intensity measurement, thereby eliminating the parasitic capacitance problem inherent in electrical-based in-cell touch panels.
2Reliability
If photo-sensitive sensing units are integrated inside the display panel, then interference-free touch detection is achieved, but device structure becomes more complex
Solution Approach 1:
The patent merges the photo-sensitive sensing units with the existing display panel structure, integrating them into the same substrate and utilizing shared components where possible. This consolidation approach adds touch detection functionality while minimizing the increase in overall device complexity by reusing existing structural elements.
Solution Approach 2:
The display panel structure is designed to accommodate multiple functions: display output, touch detection via photo-sensitive units, and fingerprint sensing. By making the panel structure universal and multi-functional, the patent reduces the need for separate dedicated structures for each function, thereby managing complexity while achieving multiple goals.
3Measurement precision
If pitch between photo-sensitive diodes is reduced for fingerprint identification, then detection precision improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the pitch between photo-sensitive diodes to a specific range that balances fingerprint detection precision with manufacturing feasibility. By carefully selecting and standardizing this critical parameter, the patent achieves sufficient detection precision while keeping manufacturing precision requirements at achievable levels through standardized fabrication processes.
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
The solution enables high-quality touch detection and fingerprint identification with minimal interference, ensuring effective operation and maintaining display performance, particularly in flexible and organic electroluminescent display panels.
Implementation Method 1
each of the photo-sensitive sensing units comprises a photo-sensitive diode configured to sense a light intensity change outside the display panel
Data Source
AI summary
The present disclosure provides a touch display panel, a flexible display panel and a display apparatus. In one embodiment, light sensitive effect-based photo-sensitive diodes and switching transistors for controlling signal output of the photo-sensitive diodes are integrated in the display panel. Once a touch operation of an object (e.g., a finger) is implemented on a surface of the display panel, the photo-sensitive diode in a corresponding position can convert a sensed light intensity difference into an electrical signal difference to achieve detection of the touch operation.