Display Device Cushion Layer Elastic Modulus Gradient
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Solution Overview
Problem
Existing display devices with press detection functions face challenges in accurately detecting pressing force due to variations in displacement and capacitance change across the screen, leading to inconsistent detection values and thickness issues.
Innovation Solution
Incorporating a cushion layer with varying elastic moduli between the display panel and the base electrode, where the elastic modulus is higher near the center and lower near the periphery, to uniformly adjust displacement and capacitance changes, thereby enhancing press detection accuracy and reducing module thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a uniform elastic layer is used between the display panel and base electrode, then the structure is simple and easy to manufacture, but the displacement and capacitance change vary across the screen leading to inaccurate press detection
Solution Approach 1:
The elastic layer is designed with spatially varying elastic modulus, where the central region has a first elastic modulus and the peripheral region has a second elastic modulus that is smaller than the first. This local quality variation compensates for the non-uniform displacement distribution across the screen, ensuring that capacitance change becomes uniformly proportional to pressing force throughout the display area, thereby achieving accurate press detection without requiring complex additional structures.
2Measurement precision
If the elastic layer has high elastic modulus throughout, then structural stability is maintained, but displacement variation across the screen increases leading to inconsistent detection values
Solution Approach 1:
The elastic layer implements local quality differentiation by assigning different elastic moduli to different regions. The central region maintains higher rigidity for structural stability, while the peripheral region has lower rigidity to accommodate edge effects and reduce displacement variation. This local optimization ensures consistent detection values across the screen while maintaining overall structural integrity.
3Length of moving object
If the module thickness is reduced, then thinner design is achieved, but press detection accuracy deteriorates due to insufficient displacement
Solution Approach 1:
The invention changes the elastic modulus parameter of the elastic layer from uniform to spatially varying. By reducing the elastic modulus in the peripheral region compared to the central region, the system achieves greater and more uniform displacement across the screen even with reduced module thickness. This parameter optimization ensures that the capacitance change remains sufficiently large and consistent for accurate press detection while enabling thinner module design.
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 configuration allows for highly accurate pressing force detection with reduced module thickness by uniformly adjusting displacement and capacitance changes across the screen, simplifying the detection process and enabling thinner designs.
Implementation Method 1
A method of utilizing a change in electrostatic capacitance between electrodes caused by press on a screen is adopted for the press sensor
Implementation Method 2
an elastic layer that is arranged between the display panel and the base electrode in the thickness direction, and the elastic layer includes a central region in the region corresponding to the screen and a peripheral region of the central region, and an elastic modulus of the peripheral region is lower than an elastic modulus of the central region
Data Source
AI summary
The display device includes: a cover glass including a screen that can be pressed; a liquid crystal panel arranged on a back side of the cover glass in a thickness direction (Z direction); a drive electrode arranged in a region corresponding to the screen in the liquid crystal panel; a base electrode arranged in the region corresponding to the screen at a position spaced apart from the drive electrode on the back side in the thickness direction; a cushion layer arranged between the liquid crystal panel and the base electrode; and a circuit that detects an electric signal representing the amount of change in capacitance between the drive electrode and the base electrode as a signal which enables calculation of a pressing force of the press. The cushion layer has such a characteristic that an elastic modulus decreases as approaching a periphery from a center in the region corresponding to the screen.