Stacked Force Sensor Hysteresis Resolution

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Solution Overview

Problem

Existing force sensors with high spatial resolution fail to accurately detect force input between array electrodes due to hysteresis in force-sensitive layers, leading to unreliable force values when summing individual detection region readings.

Innovation Solution

A force sensor design featuring a first sensor for force distribution across individual detection regions and a second sensor for comprehensive load detection, where the sensors are stacked in the force direction, allowing for precise detection of force distribution and total load values by overcoming hysteresis issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a force-sensitive layer with decreasing resistance as contact area increases is used, then spatial resolution is improved, but hysteresis occurs making force values unreliable

Engineering Contradiction:

Improvespatial resolutionVSAvoidforce value reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The detection region is divided into multiple individual detection regions corresponding to array electrodes, enabling spatial resolution while using a different sensing mechanism (capacitive coupling) that avoids hysteresis in the force-sensitive layer

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The force sensor achieves both force distribution detection (through array electrodes for spatial resolution) and whole load detection (through summation of forces) functions using a unified sensor structure, eliminating the need for separate sensing mechanisms

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If force values from individual detection regions are summed, then whole load detection is enabled, but hysteresis causes inaccurate total load values

Engineering Contradiction:

Improvewhole load detection capabilityVSAvoidtotal load accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system uses the detected force distribution data to calculate whole load values, with the array electrode readings providing feedback that can be summed to obtain accurate total load measurements despite individual region variations

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent transitions from single-point force sensing to distributed array sensing, adding spatial dimensionality to the measurement system, which enables both local force distribution and global load summation capabilities

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS20230375421A1Force sensor

Publication Date: 2023.11.23 JAPAN DISPLAY INC

AI summary

A force sensor includes an input surface that is pressed, and a first sensor and a second sensor stacked in order in a force direction with respect to the input surface. The input surface has a detection region in which force is detected, one of the first sensor and the second sensor is a force distribution sensor having a plurality of individual detection regions dividing the detection region and configured to detect the force input to the individual detection regions, and the other of the first sensor and the second sensor is a force sensor having a comprehensive detection region overlapping at least two or more of the individual detection regions and configured to detect the force input to the comprehensive detection region.