Compressible Pressure Assembly for Absolute Touchscreen Pressure Measurement
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Solution Overview
Problem
Existing passive devices, such as capacitive pens, are unable to accurately measure absolute pressure applied on a touchscreen due to tip deflection causing enlarged contact spots, leading to relative pressure interpretation rather than precise absolute measurements.
Innovation Solution
Incorporation of a compressible pressure assembly within passive devices that senses Z-direction pressure changes, allowing for accurate absolute pressure measurement by detecting capacitance changes through a compressible material that compresses with applied pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a passive device uses a rigid tip for touchscreen contact, then the device structure is simple and manufacturing is easy, but the contact spot becomes enlarged due to tip deflection under pressure, leading to inaccurate pressure measurement
Solution Approach 1:
The patent changes the physical state of the tip from rigid to compressible, allowing the material to deform under pressure. This parameter change enables the tip to maintain a small contact area while accurately sensing pressure through controlled compression, resolving the contradiction between measurement precision and structural simplicity.
Solution Approach 2:
The patent employs composite material construction with a compressible core material surrounded by a conductive layer. This composite structure provides both the mechanical compliance needed for accurate pressure sensing and the electrical properties needed for capacitive coupling, achieving precise pressure measurement without excessive structural complexity.
2Measurement precision
If a passive device uses a compressible pressure assembly for accurate pressure sensing, then measurement precision is improved, but device complexity increases due to additional components
Solution Approach 1:
The compressible pressure assembly serves multiple functions simultaneously: it provides mechanical compliance for accurate pressure sensing, maintains electrical continuity through the conductive layer, and enables capacitive coupling with the touchscreen. This multi-functionality reduces the need for separate components, mitigating the increase in device complexity.
Solution Approach 2:
The patent implements a nested structure where the conductive layer is integrated within or around the compressible core material. This nesting approach allows the electrical and mechanical functions to be combined in a compact configuration, minimizing the overall device complexity while maintaining measurement precision.
3Adaptability or versatility
If the tip material is made soft and compressible for pressure sensing, then pressure measurement capability is improved, but the contact area increases due to material deformation, reducing measurement accuracy
Solution Approach 1:
The patent uses a thin conductive layer wrapped around or integrated with the compressible core. This thin film structure allows the tip to deform under pressure for sensing while maintaining a controlled, small contact footprint on the touchscreen surface, resolving the contradiction between pressure sensing adaptability and contact spot size control.
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 precise absolute pressure measurement on touchscreens by interpreting impedance values within specific ranges to distinguish between touch, pressure, and hover actions, enhancing interaction accuracy and functionality.
Implementation Method 1
the compressible conductor changes shape. The change in surface area between the firm spherical conductor and the compressible conductor decreases the impedance between the contact conductor and the touchscreen. The increase in the surface contact between the firm spherical conductor and the compressible conductor will also increase the capacitance between the contact conductor and the touchscreen
Implementation Method 2
When pressure is applied to the firm spherical conductor (e.g., as a user is pressing the firm spherical conductor on the touchscreen), the compressible conductor compresses, which causes a change in capacitance of the passive device that is interpretable by the touchscreen as a pressure measurement
Data Source
AI summary
A passive device includes a non-conductive housing including an upper and lower housing section, a conductive section housed in the upper housing section, and a pressure assembly housed in the lower housing section. The pressure assembly includes a compressible conductor, a mounting structure coupled to the compressible conductor and the upper housing section, a conductive contact coupled to the compressible conductor and the conductive section, and a firm spherical conductor. The firm spherical conductor includes an upper contact point for contact with the compressible conductor and a lower contact point for contact with the touchscreen. When z-direction pressure is applied on the firm spherical conductor, the compressive conductor compresses against the upper contact point. Compression of the compressive conductor increases surface area between the firm spherical conductor and the compressive conductor. The increase in surface area increases the capacitance of the passive device.