Transparent Conductive Force Sensor for Touch Input Validation
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Solution Overview
Problem
Capacitive touch sensors in mobile devices fail to accurately determine the force of user input, leading to erroneous detection when accidental contact is made with the display.
Innovation Solution
A touch screen apparatus with a transparent conductive member that senses force applied by a user, providing output control signals to validate user inputs and enhance the sensitivity and accuracy of touch detection, while also acting as a ground plane for capacitive sensors to reduce interference and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive touch sensors are used to detect user input, then the touch screen can sense finger contact, but the sensor cannot determine the force of user input leading to erroneous detection
Solution Approach 1:
The patent combines a capacitive touch sensor layer with a separate force sensing layer (using piezoelectric or piezoresistive materials) into a single integrated touch screen structure. This merging allows the system to simultaneously detect both the presence of finger contact (capacitive) and the force applied (mechanical), resolving the contradiction by enabling accurate touch detection while preventing erroneous inputs through force validation.
Solution Approach 2:
The patent introduces an intermediary force sensing layer between the user's finger and the capacitive touch sensor. This intermediary layer (comprising piezoelectric or piezoresistive materials) mediates the transmission of mechanical force while allowing capacitive sensing to occur, enabling the system to distinguish between intentional presses and accidental contacts by measuring the intermediate force signal.
2Measurement precision
If a separate ground plane is added to reduce interference with capacitive sensors, then sensor performance improves, but device complexity and cost increase
Solution Approach 1:
The patent makes the force sensing layer serve multiple functions: it acts as both the mechanical force sensing element (providing input validation) and simultaneously serves as the ground plane for the capacitive touch sensor (reducing electrical interference). This multi-functionality eliminates the need for a separate ground plane structure, reducing device complexity while maintaining sensor performance.
Solution Approach 2:
The patent merges the ground plane function with the force sensing layer, combining two previously separate components (ground plane and force sensor) into a single integrated layer. This consolidation reduces the overall number of components and structural complexity while achieving both electromagnetic shielding and mechanical sensing functions.
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 improves the accuracy of user input detection by validating inputs through force sensing and reduces the need for separate ground planes, enhancing the sensitivity and reliability of touch screen displays without compromising visual quality.
Implementation Method 1
a first sensor (32) for sensing force applied to the display (30) by the user, the first sensor (32) comprising a substantially transparent conductive member (46) extending over at least a portion of the array of picture elements (34) and configured to be deformable by the user
Implementation Method 2
the substantially transparent conductive member (46) extending over at least a portion of the array of picture elements (34) and configured to be deformable by the user
Data Source
Figure 1
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AI summary
An apparatus including: a display including an array of picture elements which are configurable to provide information to a user; a first sensor for sensing force applied to the display by the user, the first sensor comprising a substantially transparent conductive member extending over at least a portion of the array of picture elements and configured to be deformable by the user, the first sensor being configured to provide an output associated with the deformation of the conductive member.