Hybrid Sense Unit for Combined Capacitive and Inductive Detection

Solution Overview

Problem

Existing touch sensors require separate sense elements and circuits for capacitive and inductive sensing, making it costly and space-consuming to detect different types of objects, especially in small form factor devices.

Innovation Solution

A hybrid sensing circuit that can operate in both capacitive and inductive modes using a single sense unit, employing a signal generator and charge measurement circuit to measure capacitance and inductance, allowing detection of various objects using combined capacitive and inductive sensing techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate sense elements and circuits are used for capacitive and inductive sensing, then detection capability for different object types is improved, but device complexity and space requirements increase

Engineering Contradiction:

Improvedetection capabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a single sense unit that can operate in both capacitive and inductive sensing modes by switching between different excitation frequencies. The same physical sensing element detects both capacitive objects (using low frequency excitation) and inductive objects (using high frequency excitation), eliminating the need for separate sense elements and circuits for each sensing type.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines capacitive and inductive sensing circuits into a single integrated sensing unit. The sense unit includes a sense element connected to excitation circuitry that can generate both low frequency excitation signals for capacitive sensing and high frequency excitation signals for inductive sensing, merging previously separate functions into one unified system.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If separate sense elements and circuits are used for capacitive and inductive sensing, then detection capability for different object types is improved, but space requirements increase

Engineering Contradiction:

Improvedetection capabilityVSAvoidspace requirements

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent implements a single sense unit that can operate in both capacitive and inductive sensing modes by switching between different excitation frequencies. The same physical sensing element detects both capacitive objects (using low frequency excitation) and inductive objects (using high frequency excitation), eliminating the need for separate sense elements and circuits for each sensing type.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If multiple sensing circuits are integrated, then detection versatility is improved, but manufacturing cost increases

Engineering Contradiction:

Improvedetection versatilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent combines capacitive and inductive sensing circuits into a single integrated sensing unit. The sense unit includes a sense element connected to excitation circuitry that can generate both low frequency excitation signals for capacitive sensing and high frequency excitation signals for inductive sensing, merging previously separate functions into one unified system.

Inventive Principle:

Principle #5Merging (Combining)

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

Enables efficient detection of different types of objects, including ferrous and non-ferrous metals, within a single device form factor, reducing costs and space requirements by integrating both sensing modes into a single sensing unit.

Implementation Method 1

a charge measurement circuit to measure capacitance and inductance

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

inductive sensing

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentUS10444916B2Combined inductive sensing and capacitive sensing

Publication Date: 2019.10.15 INFINEON TECHNOLOGIES AMERICAS CORP

AI summary

An sense unit for inductive sensing or capacitive sensing is described. The sense unit may include a first terminal coupled to a first node, a first electrode coupled to the first node, and a second terminal. The sense unit may include a second electrode coupled to the second terminal. In a first mode, a first signal is received at the first terminal and a second signal is output on the second terminal, where the second signal may be representative of a capacitance of the sense unit. The sense unit may include an inductive coil. The sense unit may include a first capacitor. The inductive coil and the first capacitor are coupled in parallel between the first node and ground. In a second mode, a third signal is received at the first terminal and a fourth signal is output on the second terminal.