OLED Touch Panel Force Sensing via Capacitive Electrode Layers
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Solution Overview
Problem
Conventional touch screen panels, including on-cell and in-cell types, cannot sense the intensity of touch force, limiting their functionality as both input and output devices.
Innovation Solution
The OLED touch display panel incorporates a capacitive force sensing structure using a first electrode layer, a third electrode layer, and an air gap or an elastic insulating layer to detect touch force by varying capacitance when a finger touches the panel, allowing for the calculation of touch force through the output of force sensing signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional touch screen panel (on-cell or in-cell type) is used, then the panel can display images and receive touch input, but it cannot sense the intensity of the touch force
Solution Approach 1:
The patent combines the touch display function and force sensing function into a single integrated panel structure. The force sensing capability is achieved by utilizing the existing electrode layers and introducing an elastic insulating layer, allowing the panel to simultaneously perform display and force detection without adding separate complex sensing systems.
Solution Approach 2:
The electrode layers in the OLED display panel are designed to serve multiple functions: they maintain their primary role in light emission and touch position detection, while also functioning as components of the force sensing mechanism through their interaction with the elastic insulating layer. This multi-functionality enables force intensity measurement without compromising the existing display and touch capabilities.
2Measurement precision
If an elastic insulating layer is introduced between electrode layers to enable force sensing, then touch force intensity can be detected, but the panel structure becomes more complex
Solution Approach 1:
The patent employs an elastic insulating layer as a thin flexible film between the first and second electrode layers. This elastic layer deforms in response to applied touch force, changing the capacitance between the electrode layers. The use of a thin elastic film enables force sensing functionality while minimizing structural complexity and maintaining the panel's overall thin profile.
3Measurement precision
If the panel structure is modified to include force sensing capabilities, then touch intensity can be measured, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process integrates the formation of the elastic insulating layer with the existing OLED fabrication steps. The elastic layer is deposited or formed between the electrode layers using techniques compatible with standard OLED manufacturing, allowing force sensing functionality to be incorporated without requiring entirely new manufacturing processes or significantly increasing production complexity.
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 the detection and calculation of touch force, enhancing the panel's ability to sense touch intensity and providing a more interactive user experience.
Implementation Method 1
a capacitive force sensing structure using a first electrode layer, a third electrode layer, and an air gap or an elastic insulating layer to detect touch force by varying capacitance
Data Source
AI summary
An OLED touch display device includes a first electrode layer, a second electrode layer facing the first electrode layer, a light-emitting layer between the first electrode layer and the second electrode, and a third electrode layer on a side of the first electrode layer. The first electrode layer functions as a cathode of the light-emitting layer, and the second electrode layer functions as an anode of the light-emitting layer. The first electrode layer and the third electrode layer cooperatively form a capacitive force sensing element. The first electrode layer also functions as touch sensing electrode.