Stylus Eraser Force Sensing for Graded Touchscreen Handwriting Removal

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Solution Overview

Problem

Conventional handwriting elimination methods for touch screens suffer from poor performance due to inconsistent erasure traces under varying forces and accidental activation of the eraser function, leading to inaccurate and inconvenient erasure actions.

Innovation Solution

A handwriting elimination apparatus for touch screens featuring a trigger component with a press portion and a strain sensing assembly that generates erasure signals based on deformation, allowing for graded erasure effects by adjusting contact force, and includes a centrosymmetric strain substrate with independently deformable strain sensing elements to enhance accuracy and range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a stylus pen is turned by 180° and pressed onto the screen to perform erasure, then the eraser function can be activated, but the same erasure trace appears under different erasure forces resulting in poor erasure effect

Engineering Contradiction:
Improveerasure function activationVSAvoiderasure trace consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by detecting different pressing forces through a force sensor and adjusting the erasure signal accordingly. The force sensor measures the magnitude of the pressing force, and the processor generates different erasure signals based on the detected force level, enabling graded erasure effects that maintain consistency across different erasure forces.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a user taps or presses a specific touch region on the electronic stylus pen to trigger eraser function, then the eraser can be activated through capacitance change detection, but the same erasure trace appears under different erasure forces resulting in poor erasure effect

Engineering Contradiction:
Improveeraser function activationVSAvoiderasure trace consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent transitions from detecting only the presence of a tap/press (binary state) to detecting the magnitude of the pressing force through a force sensor. This parameter change enables the system to differentiate between light and heavy pressing forces, generating corresponding graded erasure signals that maintain consistent erasure quality across different force levels.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If capacitance change in touch input sensor is used to detect gesture action, then the eraser function can be triggered, but recognition based on rhythmic finger tapping leads to high probability of accidental touches causing unintentional switching to eraser function

Engineering Contradiction:
Improvegesture recognitionVSAvoidaccidental touch prevention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the detection parameter from capacitance change (which cannot distinguish between intentional and accidental touches) to force magnitude detection. The force sensor can detect the intensity of the pressing action, allowing the system to set a threshold that distinguishes deliberate erasure actions from accidental touches, thereby improving reliability while maintaining ease of operation.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If the trigger position is at the front end of the stylus pen with specific distance from pen tip, then the eraser function can be triggered, but the recognition leads to high probability of accidental touches

Engineering Contradiction:
Improvetrigger accessibilityVSAvoidunintentional activation prevention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the trigger mechanism from position-based detection (which is prone to accidental activation) to force-magnitude-based detection. The force sensor located at the trigger position can distinguish between intentional pressing (above threshold) and accidental contact (below threshold), maintaining ease of operation while preventing unintentional activation.

Inventive Principle:
Principle #35Parameter changes

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

The apparatus enables precise and adjustable erasure on touch screens by generating distinct erasure signals based on varying contact forces, improving performance and accuracy by ensuring consistent erasure effects regardless of angle or force variation.

Implementation Method 1

the strain sensing assembly undergoes deformation under a press force applied by the press portion and generates an erasure signal corresponding to the deformation

Methodology Applied
Scientific EffectStrain sensing: Piezoresistive Effect

Data Source

PatentEP4715556A1Handwriting elimination apparatus and method for touch screen, and electronic stylus and stylus cap thereof
Publication Date: 2026.03.25 HUAWEI TECH CO LTD
  • EP4715556A1 patent drawingFigure 1a~2
  • EP4715556A1 patent drawingFigure 3a~3c
  • EP4715556A1 patent drawingFigure 3d~4b

AI summary

This application provides a handwriting elimination apparatus and method for a touch screen, an electronic stylus pen, and a pen cap thereof. The handwriting elimination apparatus includes a trigger component and a strain component, and can be used in the electronic stylus pen. In this case, in a process in which an elimination action is performed on an image on the touch screen by using the handwriting elimination apparatus, a press portion transfers a force received due to contact between a trigger portion and the touch screen to a strain sensing assembly, and the strain sensing assembly undergoes deformation under a press force and generates an erasure signal corresponding to the deformation. When the force received due to the contact between the trigger portion and the touch screen changes, a deformation degree of the strain sensing assembly also changes correspondingly, and a corresponding erasure signal is generated. Different contact forces between the trigger portion and the touch screen enable the strain sensing assembly to generate different erasure signals. A user can adjust a magnitude of the contact force between the trigger portion and the touch screen to implement graded erasure on the image on the touch screen, thereby achieving different degrees of erasure effect.