Force-Sensing Stylus with Electromagnetic Coils for Pressure Detection
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Solution Overview
Problem
Current stylus technologies lack an intuitive and efficient method for selecting line properties, such as line thickness, in graphical user interfaces, as they cannot simulate the continuous variation of pressure found in physical drawing tools.
Innovation Solution
A force-sensitive stylus with a compliant tip element and electromagnetic coils is used to detect applied force, encoding this information into a radio frequency signal for communication to a host device, allowing for real-time adjustment of line properties based on pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a stylus uses traditional interaction methods (electromagnetic induction, electrical resistance, electrical capacitance, optical properties, or ultrasonic location) to determine position, then the absolute position of the stylus can be determined, but the stylus cannot detect applied force or pressure for intuitive control of line properties
Solution Approach 1:
The electromagnetic coil system serves multiple functions: it determines the absolute position of the stylus tip through electromagnetic induction and simultaneously detects the applied force or pressure on the tip. This multi-functionality allows the stylus to provide both position information and force information to the host device, enabling intuitive control of line properties such as thickness based on pressure variations.
Solution Approach 2:
The system detects changes in electromagnetic induction parameters caused by force applied to the tip element. When force is applied to the tip, it causes displacement that changes the electromagnetic coupling between the coil and the host device surface, thereby encoding force information into the electromagnetic signal already used for position detection.
2Ease of operation
If line properties are selected by touching or moving the stylus to specific regions of the screen, then user input can be provided to the host device, but the method is not fast or intuitive compared to physical drawing tools
Solution Approach 1:
The patent replaces the mechanical interaction of physical drawing tools with electromagnetic sensing. Instead of requiring users to physically touch or move the stylus to specific UI regions to select line properties, the system uses electromagnetic induction to detect the force applied to the tip, translating this mechanical force directly into digital control signals for line properties such as thickness.
Solution Approach 2:
The system creates a digital copy of the physical drawing experience by mapping the force applied to the stylus tip onto digital line properties. The continuous variation of pressure on the tip element is copied into continuous variation of line thickness and other parameters, replicating the intuitive control of physical drawing tools in the digital environment.
3Measurement precision
If a stylus cannot simulate continuous variation of pressure, then position information can be conveyed accurately, but intuitive control over line properties such as line thickness cannot be achieved
Solution Approach 1:
The electromagnetic coil system serves multiple functions: it determines the absolute position of the stylus tip through electromagnetic induction and simultaneously detects the applied force or pressure on the tip. This multi-functionality allows the stylus to provide both position information and force information to the host device, enabling intuitive control of line properties such as thickness based on pressure variations.
Solution Approach 2:
The system dynamically responds to continuous variations in force applied to the tip element. The electromagnetic induction signal changes continuously with the magnitude of applied force, allowing real-time, dynamic control of line properties such as thickness to vary continuously with pressure, mimicking the behavior of physical drawing tools.
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
Enables intuitive and precise control over line properties, closely mimicking physical drawing tools by allowing continuous variation of line thickness and other parameters through pressure changes, enhancing user interaction in digital drawing applications.
Implementation Method 1
a first electromagnetic coil, located at a fixed position within a housing and a second electromagnetic coil attached to a tip element and positioned to interact with the first electromagnetic coil
Implementation Method 2
The tip element extends from one end of the housing and is moveably coupled to the housing by a compliant element, such that the position of the second electromagnetic coil relative to the first electromagnetic coil varies in dependence upon the force applied to the tip element
Data Source
AI summary
The present disclosure provides a force-sensitive stylus having a first electromagnetic coil located at a fixed position within a housing and a second electromagnetic coil that is attached to a moveable tip element and positioned to interact with the first electromagnetic coil, such that the position of the second electromagnetic coil relative to the first electromagnetic coil is dependent upon the force applied to the tip element. A control circuit energizes a transmitting coil of the first and second electromagnetic coils with a radio frequency signal and senses the current induced in the other coil to determine the force on the tip element. The force may be encoded in the radio frequency signal and then transmitted to a host electronic device by re-energizing the transmitting coil.