Multi-Touch Detection via Current Normalization
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Solution Overview
Problem
Current touch sensor devices, particularly surface capacitive types, face challenges in accurately detecting multiple touch points due to the combination of electric currents, leading to difficulties in recognizing simultaneous touches and determining individual touch coordinates, which limits their functionality to single-touch operations and increases manufacturing costs.
Innovation Solution
A touch sensor device with a transparent conductive layer and detection electrodes that uses standardized and normalized electric current values to calculate position coordinates and detect touch gestures, enabling the differentiation of multiple touch points and supporting multi-touch operations while minimizing economic burdens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If surface capacitive type touch sensor device combines electric currents from multiple touch points, then detection electrodes can detect total current, but individual touch coordinates cannot be determined
Solution Approach 1:
The patent divides the touch sensor surface into multiple detection regions with separate detection electrodes. Each detection electrode independently measures electric current from its specific region, allowing the system to segment the total current into individual touch point contributions. This segmentation enables precise determination of touch coordinates by mapping each detection electrode's current measurement to its corresponding spatial location.
2Adaptability or versatility
If projected capacitive type forms X-Y transparent electrodes in matrix form, then multi-touch operation can be supported, but manufacturing cost increases
Solution Approach 1:
The patent makes detection electrodes serve multiple functions: they detect touch presence, determine touch coordinates, and identify gesture types (such as pinching motions). By enabling detection electrodes to perform these multiple functions simultaneously, the system achieves multi-touch capability without requiring the complex X-Y electrode matrix structure, thereby reducing manufacturing costs while maintaining versatility.
3Adaptability or versatility
If surface capacitive type uses fixed four detection electrodes, then FPC and controller can be used universally, but accurate multi-touch detection becomes difficult
Solution Approach 1:
The patent adds a temporal dimension to the detection process by measuring electric currents at multiple time points and analyzing their variations. With fixed detection electrodes, the system captures current changes over time as fingers move or are placed on the surface, enabling the differentiation of multiple touch points through time-based signal analysis rather than spatial electrode multiplication.
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 allows for accurate detection of simultaneous touches and gestures, enhancing user interaction with improved sensitivity and reducing manufacturing costs by enabling multi-touch functionality in devices that previously supported only single-touch operations.
Implementation Method 1
When driving a touch sensor device of surface capacitive type, AC voltage is applied from detection electrodes formed at four corners of the transparent conductive layer. Upon a user touching the surface of the touch sensor device with a pointer, micro-current flows into the pointer via electrostatic capacity formed by the transparent conductive layer and the pointer.
Data Source
AI summary
A touch sensor device includes: an impedance surface where plural sets of reference coordinates are set at plural locations; plural detection electrodes arranged on the impedance surface; a detection circuit configured to detect electric currents passing the detection electrodes; a storage section storing reference standardized values and reference normalized values; a position coordinate calculation section configured to obtain standardized values calculated by standardizing the electric currents detected in each detection period and to map the standardized values onto position coordinates; a first normalized value calculation section configured to map the position coordinates onto first normalized values; a second normalized value calculation section configured to calculate second normalized values by normalizing the electric currents in each detection period; and a touch gesture detection section configured to detect a motion of pointers on the basis of a time variation of the first normalized values and the second normalized values.