Active Stylus Power Control Using Proximity-Sensed Tip Signaling
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Solution Overview
Problem
Conventional styluses for capacitive touchscreens face issues with cost, reliability, and power consumption, particularly in tethered active stylus technologies, and existing solutions do not effectively manage power usage or provide a seamless user experience across various applications.
Innovation Solution
A stylus design that switches between low power and active modes based on user interaction, utilizing a sense electrode to detect proximity and switch to active mode when handled, and dynamically controls the position signal amplitude to conserve power, while also encoding power information in the position signal transmitted to the host device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tethered active stylus technologies are used, then stylus sensing capability is achieved, but power consumption increases and reliability decreases
Solution Approach 1:
The patent implements dynamic power control that adjusts the stylus tip signal amplitude based on operational state. The system transitions between low power mode (when not in use) and active mode (when detected near the touchscreen), dynamically optimizing power consumption while maintaining reliable operation only when needed.
Solution Approach 2:
The patent changes the electrical parameter (signal amplitude) of the stylus tip based on proximity detection. When the stylus is detected near the touchscreen, the system increases signal amplitude to ensure reliable sensing; when away, it reduces amplitude to conserve power, thus resolving the contradiction between reliability and power consumption.
2Measurement precision
If high power mode is used continuously, then sensing precision is maintained, but power consumption increases
Solution Approach 1:
The patent employs periodic proximity detection to determine when high precision sensing is needed. Instead of continuous high power operation, the system periodically checks for stylus proximity to the touchscreen and activates high precision mode only during detected interaction periods, maintaining measurement precision while dramatically reducing overall power consumption.
Solution Approach 2:
The patent applies partial action by providing high power operation only when partially needed (during actual stylus-touchscreen interaction). The system uses low power mode for the majority of time when the stylus is not in use, activating high precision sensing only for the duration of actual interaction, thus avoiding excessive power consumption while maintaining precision when required.
3Measurement precision
If active stylus with continuous signal transmission is used, then touch detection accuracy is improved, but battery life decreases
Solution Approach 1:
The patent implements dynamic signal transmission that adapts to usage conditions. The stylus transitions between low power state (extended battery life) and active signal transmission state (high touch detection accuracy) based on proximity detection, ensuring accurate touch detection only when the stylus is actually being used near the touchscreen.
Solution Approach 2:
The system uses periodic proximity monitoring to determine when to activate continuous signal transmission. Instead of continuous transmission that would drain the battery, the system periodically checks for stylus proximity and activates high-accuracy signal transmission only during interaction periods, thereby extending battery life while maintaining touch detection accuracy when needed.
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 power consumption, enhances reliability, and provides a more efficient and cost-effective solution for stylus operation, enabling seamless interaction across different applications without the need for continuous high power usage.
Implementation Method 1
A human interface device, such as a stylus, can detect the proximity of a human body part (e.g., hand) by an increase in capacitance at a sense electrode
Implementation Method 2
In an active mode, control electronics can emit a position signal at a tip that induces a response on a host sense array
Data Source
AI summary
A device comprising a body comprising an elongated housing with at least a first conductive tip formed at a distal end and at least one sense electrode on the body; a capacitance sense circuit disposed within the housing and configured to sense a capacitance of the sense electrode to generate a proximity result in response to contact with a human body; and a signal generator circuit disposed within the housing and configured to activate a position signal in response to the proximity result, the position signal being driven at the tip of the device