Active Pen Pressure Sensing Using Body Capacitance Detection
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Solution Overview
Problem
Existing active pens for touch screens are costly due to the use of pressure sensors, which increases their production costs.
Innovation Solution
The active pen incorporates multiple touch sensors in the pen body to detect pressure by measuring the change in capacitance based on the grip strength, using a mapping relationship to determine pressure values and transmit them to the touch terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is provided in the nib of the active pen to sense pressure, then pressure detection capability is improved, but the cost of the active pen increases
Solution Approach 1:
The patent extracts the pressure detection function from a dedicated pressure sensor in the nib and relocates it to touch sensors in the pen body. This separation allows the use of simpler, cheaper touch sensors instead of expensive pressure sensors while maintaining pressure detection capability through capacitance change measurement.
Solution Approach 2:
The patent replaces the mechanical pressure sensing system with an electrical capacitance-based sensing system. Instead of using a pressure sensor that mechanically detects force, the system uses touch sensors to measure capacitance changes caused by grip strength, thereby substituting a mechanical sensing approach with an electrical field-based approach.
2Measurement precision
If a pressure sensor is provided in the nib of the active pen, then pressure detection capability is improved, but the material requirement for the nib becomes more stringent
Solution Approach 1:
The patent extracts the pressure detection function from the nib structure itself and places it in the pen body. This extraction removes the requirement for the nib to contain specialized pressure-sensitive materials, allowing the nib to be made from simpler materials that are easier to manufacture and more adaptable.
3Measurement precision
If the nib of the passive pen is made very thick to achieve sufficient sensitivity, then sensitivity is improved, but the ability to express handwriting thickness is reduced
Solution Approach 1:
The patent replaces the mechanical approach of using a thick nib for sensitivity with an electrical field-based sensing system. The touch sensors in the pen body can detect capacitance changes with high sensitivity while allowing the nib to remain thin, thereby preserving the ability to express handwriting thickness without compromising 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
This approach reduces the cost of the active pen while maintaining pressure detection capabilities, improving sensitivity and extending battery life by using touch sensors to correlate grip strength with pressure, and allowing wireless transmission to prevent screen scratching.
Implementation Method 1
obtaining a sensing change amount of each of the plurality of touch sensors separately, wherein the sensing change amount is used to indicate a capacitance change amount of a touch sensor
Data Source
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AI summary
The present invention provides a method for detecting a pressure of an active pen, a device and an active pen, where a pen body of the active pen is provided with a touch sensor. The method includes: obtaining a sensing change amount of the touch sensor, where the sensing change amount indicates a capacitance change amount of the touch sensor; and determining, according to the sensing change amount, a pressure value on the pen body. The technical solution provided by the invention can reduce the cost of the active pen while realizing the pressure detection for the active pen.