Electrostatic Input Apparatus Multi-Finger Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrostatic input apparatuses cannot distinguish between a single finger extended obliquely and multiple fingers in contact due to similar capacitance distribution patterns, leading to incorrect touch detection.
Innovation Solution
An electrostatic input apparatus that measures capacitance at multiple coordinates, calculates barycentric coordinates, and determines periodicity of difference values to differentiate between single and multiple finger inputs by analyzing the periodicity of capacitance changes around a circular measurement area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitance touch pads use a thicker plate on sensor electrodes to detect fingers, then detection capability is maintained, but resolution decreases causing single finger contacts to be detected as wide distribution areas
Solution Approach 1:
The patent divides the detection area into multiple coordinate points (e.g., 3x3 grid of 9 points) and analyzes the capacitance distribution pattern across these segmented regions. By examining the relative differences in capacitance at each coordinate rather than relying on a single thick plate, the system maintains both detection capability and resolution, distinguishing between single finger contacts and multi-finger contacts through the spatial distribution pattern.
2Device complexity
If known touch panels determine single or multi-touch based on the degree of flatness of the detected distribution area, then processing is simplified, but the system cannot distinguish between one finger extended obliquely and multiple fingers in contact
Solution Approach 1:
The patent introduces anisotropic conductivity by applying a coefficient α to the x-direction differences and a coefficient β to the y-direction differences when calculating the distribution pattern. This creates an asymmetric weighting that emphasizes directional differences in capacitance distribution. By analyzing whether the distribution pattern exhibits specific asymmetric characteristics, the system can reliably distinguish between an obliquely extended finger (which creates a directional capacitance gradient) and multiple fingers (which create a more balanced distribution), thereby improving identification accuracy without significantly increasing processing complexity.
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
Accurately distinguishes between single and multiple finger inputs, enhancing touch detection precision and resolving the ambiguity in existing systems.
Implementation Method 1
measuring capacitance at a plurality of coordinates of an electrostatic coordinate input unit
Implementation Method 2
Capacitance touch pads and touch panels detect fingers, styluses, or the like using a change in capacitance when the fingers or styluses come into contact therewith
Data Source
AI summary
An electrostatic input apparatus is provided. A measuring unit measures capacitance at a plurality of coordinates of an electrostatic coordinate input unit. A converting unit obtains a reference value of the capacitance and converts the capacitance to difference values according to a distance between the electrostatic coordinate input unit at the coordinates and a finger. A first coordinate calculating unit calculates barycentric coordinates of a contact portion from the difference values for the plurality of coordinates. A cycle determining unit determines whether the difference values at coordinates on a circumference of a circle with a predetermined radius centered on the barycentric coordinates exhibit periodicity of two cycles in one round along the circle. An operation determining unit performs, when the cycle determining unit determines that the difference values exhibit periodicity of two cycles, a determination that an input operation using two or more fingers has been performed.