Scribing Shaft Sensors With Strain Gauge Protection
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Solution Overview
Problem
Existing electronic pens lack sufficient pressure sensitivity and are prone to catastrophic failure when dropped, leading to an unsatisfactory user experience and reduced operational effectiveness.
Innovation Solution
An electronic input device with a scribing shaft and a full-bridge strain gauge that includes a failure protection mechanism to limit deformation and prevent damage from impact, enhancing sensitivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electronic pen uses a simple pressure sensor, then the device complexity is low, but the measurement precision of pressure is insufficient
Solution Approach 1:
The patent replaces traditional mechanical pressure sensors with a strain gauge-based measurement system. The strain gauge detects deformation of the scribing shaft through electrical resistance changes, providing higher measurement precision while reducing mechanical complexity. This substitution of mechanical sensing with electromechanical sensing resolves the contradiction between simple device structure and precise pressure measurement.
2Reliability
If the electronic pen lacks a failure protection mechanism, then the device complexity is low, but the reliability is poor when dropped
Solution Approach 1:
The patent implements a failure protection mechanism that includes a limit stop and damping elements positioned within the scribing shaft assembly. These components are pre-positioned to absorb and limit the transmission of impact forces during drops, preventing catastrophic failure of the strain gauge and sensor elements. This beforehand cushioning approach enhances reliability while adding only minimal structural complexity.
3Measurement precision
If the scribing shaft is made rigid, then the strength is high, but the measurement precision of deformation is reduced
Solution Approach 1:
The patent optimizes the scribing shaft by changing material parameters and geometric parameters to achieve the desired balance. The shaft is designed with specific elastic modulus, diameter, and length parameters that allow sufficient deformation for strain gauge detection while maintaining adequate strength. This parameter optimization enables the shaft to be neither too rigid nor too flexible, resolving the contradiction between strength and measurement precision.
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 solution provides enhanced force sensing sensitivity, a more realistic pen-and-paper user experience, and protection against catastrophic failures, improving the overall performance and longevity of the electronic pen.
Implementation Method 1
A full-bridge strain gauge of the sensor is disposed on a surface of the plate and detects a deformation of the plate
Implementation Method 2
A spring of the sensor is configured to: transmit and dampen the axial force from the scribing shaft to the plate; and return the scribing shaft to an initial position
Data Source
AI summary
In one example in accordance with the present disclosure, an electronic input device is described. The electronic input device includes a scribing shaft disposed within a housing, the scribing shaft to translate along a longitudinal axis as a result of contact with a substrate. The electronic input device also includes an input sensor. The input sensor includes a plate secured within the housing. The plate elastically deforms responsive to the translation of the scribing shaft. A full-bridge strain gauge of the input sensor is disposed on a surface of the plate. The full-bridge strain gauge detects a deformation of the plate and outputs a corresponding signal, which corresponding signal varies dependent upon the amount of deformation of the plate. The input sensor also includes a failure protection device to limit the deformation of the plate to within a predetermined amount.