Pressure-Sensitive Stylus Tip with Plunger and Piezoresistive Sensor
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Solution Overview
Problem
Conventional touch screen computing devices face limitations in pressure sensitivity with stylus input devices, as they are often fragile due to complex components, and traditional techniques disrupt capacitive connections, limiting the range of inputs and gestures.
Innovation Solution
A pressure-sensitive stylus with a deformable tip and a plunger mechanism that transfers force to a resilient disc and force-sensitive resistor, allowing for precise measurement of pressure levels through changes in electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pressure sensors are incorporated into styli, then pressure sensitivity is improved, but device complexity and fragility increase
Solution Approach 1:
The patent replaces complex mechanical pressure sensing systems with a simplified electrical field-based sensing mechanism. The capacitive tip and associated circuitry detect pressure through changes in electrical capacitance rather than mechanical deformation, eliminating the need for complex moving parts while maintaining pressure sensitivity.
Solution Approach 2:
The patent utilizes changes in electrical parameters (capacitance, resistance, or inductance) in response to pressure application. The capacitive tip's electrical characteristics change when pressure is applied, allowing pressure detection through electrical measurement rather than mechanical sensing, thereby reducing device complexity.
2Measurement precision
If pressure-sensitive elements are added to styli, then pressure detection capability is improved, but reliability decreases due to susceptibility to damage
Solution Approach 1:
The patent replaces fragile mechanical pressure-sensitive elements with a more durable electrical field-based sensing system. The capacitive tip and circuitry are inherently more resistant to damage from drops and impacts compared to mechanical components, improving reliability while maintaining pressure detection capability.
Solution Approach 2:
The patent employs a simple, robust capacitive tip structure that can withstand repeated use and potential damage. The design prioritizes durability over complexity, using inexpensive and replaceable components that maintain functionality even after minor damage, effectively treating the tip as a durable consumable element.
3Measurement precision
If traditional pressure sensing techniques are used, then pressure sensitivity is improved, but capacitive connection is disrupted
Solution Approach 1:
The patent designs the capacitive tip to serve multiple functions simultaneously: it maintains capacitive connection with the touch screen for basic touch input while also sensing pressure through changes in its electrical characteristics. This multi-functionality allows the same component to enable both touch detection and pressure sensitivity without disrupting capacitive connectivity.
Solution Approach 2:
The capacitive tip acts as an intermediary element that mediates between the user's pressure input and the touch screen's sensing system. By detecting pressure through changes in its own electrical properties, the tip translates mechanical pressure into electrical signals that the touch screen can interpret, preserving capacitive connection while enabling pressure sensitivity.
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 detection of over a thousand pressure levels, enhancing input capabilities while maintaining ergonomic design and preserving capacitive connectivity.
Implementation Method 1
a force sensitive resistor disposed at an end of the chamber that is distal from the tip... configured to measure a degree of the force based at least in part on a change in output voltage of a circuit completed by the plunger, the disc, the force sensitive resistor, and the conductive strip
Implementation Method 2
a disc in contact with the plunger at an end of the plunger distal from the tip, the disc exhibiting resiliency and electrical conductivity, the disc configured to compress in response to movement by the plunger
Data Source
AI summary
A stylus and sensor capable of determining levels of pressure applied to a tip are disclosed. The stylus has a tip configured to interact with and receive a force from a touch surface. The stylus includes a force sensitive resistor configured to vary resistance in an electrical circuit based on the force and a component for determining an amount of pressure corresponding to the force or a change in pressure based on the resistance in the electrical circuit. The stylus can have a chamber housing a slide-able plunger connected to the tip, the plunger being adapted to move in directions perpendicular or tangential to the surface when the force is applied. The resistor is disposed at an end of the chamber. The stylus can have a conductive strip on the resistor and a disc on the strip. The disc is configured to compress when force is applied by the plunger.