Pointing Interface With Skin-Contact Biometrics and Capacitive Sensing
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Solution Overview
Problem
Existing pointing devices lack large area high resolution touch sensors, and biometric security measures like fingerprint sensors face integration challenges and vulnerability to circumvention, necessitating a secure and efficient biometric skin-contact sensor for improved functionality and security.
Innovation Solution
A pointing device equipped with a biometric skin-contact sensor that senses surface contours of the operator's skin to identify and authorize users, incorporating a self-capacitance fingerprint sensor for 2D and 3D surfaces, enabling gesture recognition and pressure sensing without additional components, and reducing parasitic capacitance through a TFT array and capacitive sensing electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fingerprint sensors with high resolution (hundreds of pixels per inch) are used, then biometric security is improved, but device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent changes the resolution parameter from traditional high-resolution fingerprint sensors (hundreds of PPI) to a lower resolution matrix array (e.g., 8x6, 16x12 pixels). This parameter change maintains biometric security by using capacitive sensing of skin surface contours while dramatically reducing manufacturing complexity and enabling integration into standard electronic devices.
Solution Approach 2:
The patent replaces complex mechanical/optical fingerprint sensing systems with an electrical capacitive sensing system. Instead of using optical cameras or complex mechanical scanners, the invention uses a matrix of capacitive sensors that detect changes in capacitance caused by the conductive properties of skin at ridges and valleys, substituting mechanical complexity with electrical measurement simplicity.
2Ease of manufacture
If capacitive touch sensing is used for fingerprint detection, then manufacturing ease is improved, but susceptibility to environmental noise and interference increases
Solution Approach 1:
The patent segments the sensing system into a matrix array of independent pixel electrodes, each with its own readout circuitry. This segmentation allows for localized sensing and reduces the impact of environmental noise on the entire system, as each pixel can be independently calibrated and measured. The segmented approach also enables flexible integration into different device form factors.
Solution Approach 2:
The patent implements self-capacitance measurement where each pixel electrode measures its own capacitance to ground through integrated readout circuits. This self-service approach eliminates the need for separate drive and sense electrodes, reducing the system's susceptibility to external electromagnetic interference while maintaining ease of manufacture. The system serves itself by using the operator's body as the reference ground.
3Measurement precision
If active matrix capacitive sensors with switching elements are used, then measurement precision is improved, but parasitic capacitance accumulates additively limiting sensor size
Solution Approach 1:
The patent transitions from one-dimensional linear arrays to two-dimensional matrix arrays of pixel electrodes. This dimensional change allows for more efficient packing of sensing elements and enables larger sensing areas without proportionally increasing parasitic capacitance. The matrix configuration with shared row and column connections reduces the total number of independent connections needed compared to fully addressed arrays.
Solution Approach 2:
The patent extracts and eliminates the need for complex switching elements in each pixel by using a simplified capacitive measurement approach. Instead of requiring transistors or other active switching components in each pixel, the system uses passive capacitive sensing with external readout circuitry, removing the source of additively accumulating parasitic capacitance while maintaining measurement precision through the capacitive coupling between the pixel electrodes and the operator's skin.
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
Enhances security and functionality by allowing secure access and advanced control of graphical user interfaces without separate login steps, improving energy efficiency and reducing the need for mechanical devices.
Implementation Method 1
The sensor array pixels each include an electrode which acts as one plate of a capacitor, the dermal layer (which is electrically conductive) acts as the other plate, and the non-conductive epidermal layer acts as a dielectric. The capacitance is greater where the dermis is closer to the pixel electrode, and so the surface contours of the skin can be sensed by measuring the capacitance of each pixel
Data Source
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AI summary
Disclosed herein is a pointing device for controlling the position of a pointer in a graphical user interface, GUI, of a computer. The device comprises: an operation interface for sensing operation by an operator of the device for controlling the pointer in the GUI, and a biometric skin-contact sensor configured to obtain biometric identifier data, for identifying the operator, by sensing contact of surface contours of the operator's skin. The biometric skin-contact sensor is a contact surface of the operation interface configured to obtain the biometric identifier data during the operation to control the pointer.