# How Stylus Ring Electrodes Detect Pen Tilt and Orientation

> Apple's patent for a stylus design that uses specific ring-shaped sensors to accurately measure the angle and tilt of a pen against a touchscreen.

- **Patent:** US 10025401
- **Original title:** Active stylus ring electrode
- **Owner:** Apple Inc
- **Granted:** 2018
- **Status:** Active
- **Times cited:** 3
- **Field:** consumer_electronics, semiconductors

## What it does

This patent describes a specialized electrode configuration for an active stylus, consisting of a ring electrode, a ground ring, and a ground plate arranged on a non-conductive base. By precisely tuning the physical dimensions and spacing of these conductive elements, the stylus can shape its electric field to improve capacitive coupling with a touch-sensitive surface. This allows the device to calculate the orientation and tilt of the stylus relative to the screen. For example, when a user tilts their stylus to shade a digital drawing, the varying signal strength across these ring segments informs the tablet about the exact angle of the pen.

## What it does NOT cover

- Does not cover styluses that rely solely on a single tip electrode for touch detection.
- Does not cover touchscreens that use optical or infrared sensors to track pen position.
- Does not cover passive styluses that lack internal drive circuitry and active electrodes.
- Does not cover methods of tilt detection that use internal accelerometers or gyroscopes.

## The clever bit

The invention uses a specific geometric arrangement of 'crown-shaped' projections and sub-rings with varying lengths to intentionally distort the electric field, allowing the stylus to 'see' its own tilt angle through capacitive feedback.

## Real-world examples

1. Apple Pencil (various generations)
2. iPad Pro digital art workflows
3. Professional digital illustration software

## Why it matters

As digital art and note-taking on tablets have become mainstream, the demand for high-fidelity input has grown. This technology allows professional-grade styluses to mimic the behavior of real pencils and brushes, which change their stroke width and texture based on the angle at which they are held. It is a core component in the evolution of the Apple Pencil ecosystem.

## Frequently asked questions

### What does How Stylus Ring Electrodes Detect Pen Tilt and Orientation cover?

Apple's patent for a stylus design that uses specific ring-shaped sensors to accurately measure the angle and tilt of a pen against a touchscreen.

### Who owns patent US 10025401?

Apple Inc owns this patent, granted in 2018.

### When does this patent expire?

This patent is expected to expire on July 17, 2038, when the invention enters the public domain.

### What is patent US 10025401 cited by?

This patent has been cited by 3 later patents that build on its ideas.

### What problem does this patent solve?

As digital art and note-taking on tablets have become mainstream, the demand for high-fidelity input has grown. This technology allows professional-grade styluses to mimic the behavior of real pencils and brushes, which change their stroke width and texture based on the angle at which they are held. It is a core component in the evolution of the Apple Pencil ecosystem.

### What does this patent NOT cover?

Does not cover styluses that rely solely on a single tip electrode for touch detection.

**Full plain-English explainer:** https://patentbrief.org/patent/us/10025401/apple-watch-digital-crown

**Original patent:** https://patents.google.com/patent/US10025401

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._