# 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 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [Adjusting Touchscreen Sensitivity Based on Device Tilt Angle](https://patentbrief.org/patent/us/20160291760/contact-discrimination-using-a-tilt-angle-of-a-touch-sensitive-surface) — This patent describes how a computing device can decide if a touch on its screen is intentional or accidental by changing its sensitivity settings based on how much the device is tilted. - [How Touchscreens Predict Where Your Finger Will Land Before You Touch](https://patentbrief.org/patent/us/10564770/airpods-wireless-earbuds) — Apple's patent describes a touch controller that tracks an object's path through the air to predict where it will land on a screen before it actually makes physical contact. - [How Touchscreens Precisely Align Signals to Detect Your Touch](https://patentbrief.org/patent/us/8493330/individual-channel-phase-delay-scheme) — Apple's patent describes a way for touchscreens to adjust the timing of internal electrical signals so they perfectly match the signals coming from your finger, making touch detection more accurate. - [How Touchscreens Use Math to Recognize Your Fingers](https://patentbrief.org/patent/us/7812828/ellipse-fitting-for-multi-touch-surfaces) — Apple's patent on using mathematical ellipses to track and identify individual fingers and palms on a touch-sensitive surface. - [How Multi-Touch Screens Track Multiple Fingers at Once](https://patentbrief.org/patent/us/7663607/multipoint-touchscreen) — Apple's 2010 patent describes a touch screen that uses two layers of transparent conductive lines to detect several fingers touching the screen simultaneously.