Capacitive Pressure Detection in Thin Display Devices
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Solution Overview
Problem
The challenge is to enhance the accuracy of pressure detection in thin display devices, where the reduced thickness of constituent members results in decreased elastic deformation and subsequently lower detection reliability due to the applied pressure.
Innovation Solution
A display device configuration that includes a first substrate with a display function layer, first wirings for forming an image, a conductive film separated from the substrate, and a circuit detecting capacitance changes between the wirings and the conductive film, which calculates pressure through capacitance changes, incorporating an elastic deformation layer for increased sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of constituent members is reduced to meet thinning demands, then the display device becomes thinner, but the degree of elastic deformation decreases leading to lower pressure detection accuracy
Solution Approach 1:
The patent changes the physical parameters of the pressure detection system by introducing an elastic deformation layer with specific material properties (high elasticity, low stiffness) and optimizing its thickness to be greater than the substrate thickness. This parameter change enables sufficient elastic deformation even when the overall display device is thinned, thereby maintaining pressure detection accuracy.
Solution Approach 2:
The patent employs composite material structure by combining the substrate with a specially designed elastic deformation layer made of elastic material. This composite structure allows the thin substrate to maintain structural integrity while the elastic layer provides the necessary deformation response for pressure detection, resolving the contradiction between thinness and detection accuracy.
2Adaptability or versatility
If a pressure detection mechanism is added to the display device, then pressure detection function is achieved, but the device complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing the pressure detection mechanism to share components with the display structure. The elastic deformation layer serves both as a structural element and as the sensing element for pressure detection. The capacitance detection circuit also serves dual purposes by detecting both touch position and pressure magnitude, thereby adding pressure detection functionality without proportionally increasing device complexity.
Solution Approach 2:
The patent replaces traditional mechanical pressure sensing mechanisms with a capacitance-based detection system. Instead of using mechanical levers, springs, or direct contact sensors, the system uses changes in capacitance values caused by elastic deformation to detect pressure. This substitution reduces mechanical complexity while maintaining detection functionality.
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 improves the detection accuracy and reliability of pressure applied to the display device by enhancing the capacitance change due to external pressure, reducing noise influence and increasing the sensitivity of the pressure sensor.
Implementation Method 1
a first circuit detecting a change in a capacitance value between the plurality of first wirings and the first conductive film. Further, the display device calculates pressure due to contact of an external object by the change in the capacitance value
Implementation Method 2
since some of constituent members of the display device are elastically deformed depending on the pressure
Data Source
AI summary
To improve detection reliability of an input device provided with a display device.A display device includes an array substrate having an upper surface and a lower surface on an opposite side of the upper surface, a display functional layer provided on the upper surface side of the array substrate, a plurality of first wirings provide on the upper surface side of the array substrate and applied with a signal for driving the display functional layer, a conductive pattern provided on the lower surface of the array substrate so as to be separated from the array substrate, and a detection circuit unit detecting a change in a capacitance value between the plurality of first wirings and the conductive pattern.