Force Sensor Signal Correction for Mechanical Relaxation

Solution Overview

Problem

Force sensors in host devices, such as mobile devices, often produce inaccurate sensor signals due to mechanical relaxation effects, leading to errors in button press detection, as the materials take time to return to their undistorted form after the applied force is removed.

Innovation Solution

A correction unit is introduced to estimate the mechanical relaxation effect and generate a corrected signal by subtracting an estimation signal from the original sensor signal, improving the representation of the applied force, especially during the removal of the force, using a mechanical model that accounts for elapsed time and other variables.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If force sensors are used to detect button presses in host devices, then button press detection capability is provided, but measurement precision deteriorates due to mechanical relaxation effects causing inaccurate sensor signals

Engineering Contradiction:

Improvesensor signal accuracyVSAvoidbutton press detection accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The correction unit continuously monitors the sensor signal and applies real-time correction based on the relationship between the sensor signal and the actual applied force. The correction signal is generated as feedback to compensate for mechanical relaxation effects, improving the accuracy of button press detection.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

A correction unit is introduced as an intermediary component between the force sensor and the button press detection logic. This correction unit processes the sensor signal by generating a correction signal based on the relationship between the sensor signal and actual applied force, thereby mediating the inaccurate sensor output before it reaches the detection system.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If material is used as force sensing element, then force sensing capability is provided, but measurement precision deteriorates due to temporary mechanical distortion and slow return to undistorted form

Engineering Contradiction:

Improveforce measurement accuracyVSAvoidtime to return to undistorted form

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The correction unit performs preliminary correction of the sensor signal by generating a correction signal based on the relationship between the sensor signal and actual applied force. This preliminary action compensates for the anticipated slow return to undistorted form, allowing the system to accurately detect button presses even during the material's relaxation period.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If correction unit is added to compensate for mechanical relaxation, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvecorrected signal accuracyVSAvoidsensor system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

A correction unit is introduced as an intermediary component between the force sensor and the button press detection logic. This correction unit processes the sensor signal by generating a correction signal based on the relationship between the sensor signal and actual applied force, thereby mediating the inaccurate sensor output before it reaches the detection system.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The correction unit continuously monitors the sensor signal and applies real-time correction based on the relationship between the sensor signal and the actual applied force. The correction signal is generated as feedback to compensate for mechanical relaxation effects, improving the accuracy of button press detection.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11947756B2Sensor signal correction

Publication Date: 2024.04.02 CIRRUS LOGIC INC

AI summary

A correction unit for use in a sensor system, the sensor system comprising a force sensor configured to output a sensor signal indicative of a temporary mechanical distortion of a material under an applied force, the correction unit configured, based on the sensor signal, to: estimate an effect of the applied force on how the material will return towards an undistorted form upon a substantial reduction or removal of the applied force; and generate a corrected signal based on the estimation.