Ultrasonic Touch Sensor Layout for Reliable Metal Casing Detection

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Solution Overview

Problem

Existing ultrasonic touch sensors face challenges in attaching to casings, particularly those made of metal, due to material compatibility issues and the need for effective acoustic coupling.

Innovation Solution

An ultrasonic touch sensor design featuring a semiconductor chip with an ultrasonic transducer element, an acoustic coupling medium, and electrical contact elements arranged on the component side, allowing for easy attachment to casings using solder balls or other contact elements, and ensuring reliable acoustic coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a capacitive touch sensor is used, then the touch detection function is achieved, but the material of the contact surface is restricted and cannot be metal

Engineering Contradiction:

Improvematerial compatibilityVSAvoidtouch detection reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the electrical field-based capacitive sensing mechanism with an acoustic wave-based ultrasonic sensing mechanism. The ultrasonic transducer generates and detects acoustic waves that propagate through the casing, enabling touch detection on metal surfaces where capacitive sensors fail due to electrical conductivity interference.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an acoustic coupling medium as an intermediary between the ultrasonic transducer and the metal casing. This coupling medium ensures efficient transmission of acoustic waves from the transducer through the casing material, enabling reliable touch detection while maintaining compatibility with metal surfaces.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If an ultrasonic touch sensor is used with metal casing, then material compatibility is improved, but acoustic coupling becomes difficult to achieve

Engineering Contradiction:

Improvemetal casing compatibilityVSAvoidacoustic coupling implementation

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The acoustic coupling medium serves as a mediator that bridges the ultrasonic transducer and the metal casing, ensuring efficient acoustic wave transmission. This coupling medium is specifically designed to accommodate the acoustic impedance mismatch between the transducer and metal surface, simplifying the attachment process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the acoustic impedance parameters by introducing a coupling medium with appropriate acoustic properties. This parameter adjustment enables efficient acoustic coupling between the transducer and the metal casing, resolving the impedance mismatch that would otherwise prevent effective operation.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If the ultrasonic transducer element is arranged on the component side, then electrical contact elements can be arranged on the component side for simplified attachment, but the acoustic coupling medium must cover the transducer element

Engineering Contradiction:

Improveattachment simplicityVSAvoidacoustic coupling medium configuration

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent combines the electrical contact elements and the acoustic coupling medium application area both on the component side of the semiconductor chip. This spatial merging allows for simplified assembly where the coupling medium can be applied in a single step while establishing both acoustic and electrical connections simultaneously.

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

The proposed ultrasonic touch sensor enables reliable detection of touch events on various casing materials, including metal, by providing effective acoustic coupling and simplified attachment mechanisms, enhancing user interaction with electronic systems.

Implementation Method 1

The semiconductor chip includes an ultrasonic transducer element and the ultrasonic transducer element is arranged on the component side

Methodology Applied

Scientific EffectUltrasonic transducer: Ultrasonic Vibration

Implementation Method 2

an acoustic coupling medium covering the semiconductor chip at least in the region of the ultrasonic transducer element

Methodology Applied

Scientific EffectAcoustic coupling: Acoustic Radiation Pressure

Data Source

PatentUS12210706B2Ultrasonic touch sensor

Publication Date: 2025.01.28 INFINEON TECHNOLOGIES AG

AI summary

An ultrasonic touch sensor is proposed for attachment to a casing, having a semiconductor chip including a substrate side and a component side, the semiconductor chip including an ultrasonic transducer element and the ultrasonic transducer element being arranged on the component side, having an acoustic coupling medium covering the semiconductor chip at least in the region of the ultrasonic transducer element, having electrical contact elements for controlling the ultrasonic transducer element, and the electrical contact elements being arranged on the component side of the semiconductor chip.