Passive Pen Variable Capacitor Pressure Measurement
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Solution Overview
Problem
Current digital pens lack accurate pressure measurement capabilities, as traditional passive pens interpret Z-pressure as relative and enlarged contact spots, while active pens rely on onboard calculations, which may not provide real-time and precise pressure data to touch screens.
Innovation Solution
Incorporating a variable capacitor within the pen that compresses with pressure applied to the touch screen, allowing for absolute pressure measurement by changing capacitance, which is detected by the touch screen's drive-sense circuits, enabling precise pressure data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a passive pen is used, then the device complexity is low and ease of operation is high, but the measurement precision of pressure is poor (only relative pressure can be determined)
Solution Approach 1:
The patent applies parameter changes by incorporating a variable capacitor whose capacitance value changes in response to applied pressure. This allows the passive pen to provide absolute pressure measurements rather than just relative pressure, improving measurement precision without requiring complex active electronics or onboard calculations
Solution Approach 2:
The variable capacitor acts as an intermediary element that translates mechanical pressure into electrical capacitance changes. This mediator enables the touch screen's drive-sense circuits to detect pressure information, bridging the gap between simple passive pen structure and accurate pressure measurement capability
2Reliability
If a passive pen is used, then the ease of manufacture is high, but the reliability of absolute pressure measurement is poor (only relative pressure is available)
Solution Approach 1:
By changing the physical parameter of the capacitor (its capacitance value) in response to pressure, the pen achieves reliable absolute pressure measurements. This approach maintains manufacturing simplicity while significantly improving measurement reliability compared to traditional passive pens that can only provide relative pressure information
3Measurement precision
If active pens with onboard calculation are used, then the measurement precision of pressure is improved, but the device complexity increases
Solution Approach 1:
The variable capacitor serves as a passive intermediary that performs the pressure-to-electrical conversion without requiring active electronics or onboard calculations in the pen. This eliminates the complexity of active pens while maintaining accurate pressure measurement capability through the touch screen's existing drive-sense circuits
Solution Approach 2:
The patent replaces the mechanical/electronic calculation system of active pens with a passive capacitive sensing mechanism. Instead of using onboard processors and algorithms to calculate pressure, the system uses the natural electrical properties of the variable capacitor to directly indicate pressure, simplifying the overall system architecture
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 accurate and absolute pressure measurement, enhancing the precision of digital pen interactions by directly measuring pressure changes, improving user input accuracy and feedback on touch screens.
Implementation Method 1
Incorporating a variable capacitor within the pen that compresses with pressure applied to the touch screen, allowing for absolute pressure measurement by changing capacitance
Data Source
AI summary
A passive pen for interaction with a touch screen, wherein the passive pen includes a housing, a conductive section, a fixed conductive z-direction mounting section coupled to the conductive section, a moveable conductive z-direction mounting section, a variable capacitor positioned between the fixed conductive z-direction mounting section and the moveable conductive z-direction mounting section, and a conductive tip coupled to the moveable conductive z-direction mounting section. When the user is in contact with the conductive section, a capacitive connection is established between the conductive section and the user's body. The variable capacitor has a compressive property. Pressure on the conductive tip creates a z-direction force operable to move the moveable conductive z-direction mounting section in the z-direction. Movement of the moveable conductive z-direction mounting section compresses the variable capacitor against the fixed conductive z-direction mounting section. When the variable capacitor is compressed, capacitance of the variable capacitor changes.