Optical Touch Display Pixel Structure Resistant to Parasitic Capacitance
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Solution Overview
Problem
Conventional touch display devices face challenges in accurately sensing touch positions and fingerprints due to parasitic capacitance, structural issues, and complex manufacturing processes, which affect sensing accuracy and reliability.
Innovation Solution
A touch display device with a display panel incorporating a pixel structure that includes a switching transistor and an optical sensor, where the optical sensor reacts to light, allowing for accurate touch and fingerprint sensing without separate large-sized touch sensors, and enabling low-voltage driving and increased sensing frequency through a single structure that alternates between different voltages during touch sensing modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance-based touch sensing is used, then touch sensing function is provided, but sensing accuracy deteriorates due to parasitic capacitance
Solution Approach 1:
The patent replaces the electrical capacitance-based sensing mechanism with an optical sensing mechanism. The optical sensor detects touch positions and fingerprints by measuring light intensity variations rather than electrical capacitance, thereby eliminating the harmful effect of parasitic capacitance while maintaining touch sensing functionality.
2Measurement precision
If multiple touch sensors are formed on the touch screen panel, then touch sensing capability is improved, but manufacturing process becomes complicated and panel thickness increases
Solution Approach 1:
The patent merges the display panel and touch sensor into a single integrated structure. The optical sensor is formed within the display panel itself, sharing the same substrate and manufacturing process, thereby eliminating the need for separate touch sensor layers and reducing overall panel thickness while maintaining touch sensing capability.
Solution Approach 2:
The display panel structure is designed to serve dual functions: displaying images and sensing touch positions/fingerprints. The same pixel structure and optical components are used for both display and sensing purposes, reducing the need for additional dedicated sensor components and simplifying the manufacturing process.
3Measurement precision
If separate large-sized touch sensor is provided, then accurate touch sensing is achieved, but device size and complexity increase
Solution Approach 1:
The patent combines the touch sensing function with the display panel structure, allowing the optical sensor to be distributed across the entire display area rather than requiring a separate large-sized sensor component. This integration enables accurate touch sensing throughout the display while maintaining a compact overall device form factor.
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 solution enables accurate and efficient touch and fingerprint sensing, unaffected by parasitic capacitance, with improved manufacturing simplicity and reduced panel thickness, while allowing for both display driving and touch sensing using a single structure.
Implementation Method 1
an optical sensor, opposite ends of which are connected to a source node and a drain node of the switching transistor, respectively
Data Source
AI summary
The present disclosure relates to a touch display device, a touch sensing system, and a touch sensing method. More specifically, touch information (fingerprint information or touch position information) may be acquired in response to current flowing in a data line through a touch sensing mode period that includes: a first period in which an optical sensor, the opposite ends of which are connected to a source node and a drain node of a switching transistor, is disposed in a pixel region, a gate signal of a turn-on level voltage is supplied to a gate line and a driving voltage is supplied to the data line; and a second period in which a gate signal of a turn-off level voltage is supplied to the gate line, a reference voltage is supplied to the data line, and an optical sensor is irradiated with light. According to the present disclosure, it is possible to accurately sense a touch position and/or a fingerprint in an optical manner using an optical sensor without being influenced by parasitic capacitance.