Knob-on-Display (KoD): Capacitive Touch Integrated Knob Technology

DATA IMAGE's Touch Integration Center supports Knob-on-Display (KoD) projects from design evaluation through to production, integrating both the Microchip maXTouch Knob-on-Display and TouchNetix Dial on Display platforms. A physical knob's rotation is sensed through a passive conductive feature built directly onto a standard capacitive touch panel—no panel opening and no extra mechanical wiring required—bringing automotive, appliance, and industrial HMIs an operating experience with both tactile feedback and full multi-touch flexibility, backed by firmware tuning for noise, cover stack, and multi-knob conditions.

Precise Control

Reduced Visual Dependence

Design Freedom

Multi-Input Integration

Core Technology

How Passive-Conductive Knob Sensing Works

KNOB technology doesn't simply "add" a knob on top of the screen—it converts the knob's mechanical rotation into a signal event that a standard capacitive touch controller can interpret, letting touch and vision work together on the same interface. As the knob turns, the passive conductive feature at its base moves relative to the touch electrodes; the controller continuously measures the capacitive coupling change above the cover lens, and an algorithm distinguishes the knob feature from finger touches and background noise, then reports rotation direction, angle/detent count, and press or touch state to the host for UI, audio, or haptic feedback.

Mechanical Rotation

The knob moves its conductive feature relative to the touch electrodes, creating a trackable positional change as it turns.

Capacitive Coupling

The controller measures electrode signal changes through the cover lens to determine the knob's current relative position.

Recognition & Tracking

The algorithm distinguishes the knob feature, finger touches, and background noise in real time, avoiding false or missed detections across a wide range of operating conditions.

Event Reporting

Rotation direction, angle/detent count, and press or touch state are reported to the host, which drives the corresponding UI, audio, or haptic feedback.

A Complete Experience Is Shaped by Five Layers

Knob feel and touch reliability must be co-designed from mechanics to firmware—you can't finalize the knob structure first and expect touch firmware to fix it afterward. The knob structure, cover lens, touch sensor, display and UI, and controller/firmware all affect one another, so size, material, sensor pitch, and noise thresholds need to be tuned together from the start of a project.

A Dual-Platform Strategy Matched to Your Project

We support both Microchip maXTouch Knob-on-Display and TouchNetix aXiom Dial on Display, helping customers choose the platform best suited to display size, environmental conditions, certification requirements, and haptic needs—rather than pushing a single either/or answer. Microchip's passive conductive pad mounts directly on a standard touch panel with software-defined knob size, shape, and position, while TouchNetix's aXiom controllers enable precision adjustments on 3D surfaces up to 15mm thick with 80dB SNR for hover, proximity, and air-gesture support.

Six Ways KNOB Technology Creates Value for Users

Precise Control — Rotational adjustment suits fine parameters like temperature, speed, volume, and pressure better than sliding.
Reduced Visual Dependence — Users don't need to keep watching the screen; detent and press feedback confirm the adjustment.
Design Freedom — Knob size, position, and UI can be tailored to project needs, unconstrained by fixed mechanical parts.
Easy-to-Clean Interface — Supports a flat, seamless front panel design, reducing gaps and the risk of dirt buildup.
Multi-Input Integration — Rotation, press, and multi-touch can coexist, preserving full interaction flexibility.
Faster Time to Production — One-stop support from samples and firmware tuning through to production validation.

FAQ

Q1. Does Knob-on-Display require an opening in the screen or cover lens?

No. The knob's passive conductive structure attaches directly on top of a standard capacitive touch panel, and the controller's algorithm recognizes rotation events—no additional panel opening or wiring is needed.

Q2. Does using the knob affect the existing multi-touch function?

No. Knob events coexist with normal finger touches—the controller distinguishes the knob feature, finger touches, and background noise, so the screen retains full multi-touch flexibility.

Q3. Should I choose Microchip maXTouch KoD or TouchNetix Dial on Display?

The two aren't mutually exclusive—we recommend evaluating display size, cover stack thickness, environmental conditions (temperature/humidity, EMC, vibration), certification needs, and haptic requirements together. We can help with platform selection.

Q4. Can multiple knobs be placed on a single screen?

Yes. Certain Microchip series and TouchNetix 3D series both support up to four knobs. The actual count and spacing depend on sensor pitch and mechanical tolerance, and require a feasibility assessment.

Q5. What needs to be validated before mass production?

We recommend validating with the complete module (not a standalone IC) across five areas: function and feel, environmental conditions (temperature/humidity, water film, gloves), EMI/ESD, mechanical durability (rotation and press life), and process consistency.