Ultrasonic Touch Sensor Metallic Surface Compatibility

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Solution Overview

Problem

Existing ultrasonic touch sensors face limitations in compatibility with metallic surfaces and require effective acoustic coupling for reliable touch detection, which is not consistently achievable with current technologies.

Innovation Solution

The development of an ultrasonic touch sensor that includes a membrane with electrodes and a substrate, embedded in an encapsulation layer, using AC and DC voltages to transmit and detect ultrasonic waves, with a potting compound forming the housing and acoustic coupling materials to enhance surface attachment and reduce interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a capacitive touch sensor is used, then the sensor can detect touches, but it cannot be combined with a metallic touch surface

Engineering Contradiction:

Improvecompatibility with metallic surfacesVSAvoidtouch detection capability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the capacitive sensing mechanism with an ultrasonic sensing mechanism. The ultrasonic touch sensor uses piezoelectric elements to generate and detect ultrasonic waves, which can penetrate and interact with metallic surfaces without the electrical isolation issues that plague capacitive sensors. This substitution of the sensing principle enables compatibility with metallic touch surfaces while maintaining reliable touch detection capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If an ultrasonic touch sensor is used with different surface materials, then material compatibility is improved, but acoustic coupling to the surface becomes difficult to achieve

Engineering Contradiction:

Improvecompatibility with different surface materialsVSAvoidacoustic coupling quality

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent introduces an acoustic coupling layer as an intermediary between the ultrasonic transducer and the touch surface. This layer, composed of materials with appropriate acoustic impedance, facilitates efficient transmission of ultrasonic waves from the piezoelectric element to the surface. The coupling layer compensates for acoustic impedance mismatches between the transducer and various surface materials, ensuring consistent acoustic coupling quality across different materials while maintaining material compatibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the ultrasonic transducer is directly attached to the surface, then acoustic coupling is improved, but the sensor cannot be manufactured in a simple manner

Engineering Contradiction:

Improveacoustic couplingVSAvoidmanufacturing simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the ultrasonic touch sensor into distinct functional layers: a piezoelectric element layer, an acoustic coupling layer, and a protective encapsulation layer. This segmentation allows each layer to be optimized and manufactured separately using standard processes, then assembled into a complete sensor module. The acoustic coupling layer is pre-formed with appropriate material properties, enabling reliable acoustic coupling without requiring complex direct attachment procedures, thus simplifying overall manufacturing.

Inventive Principle:

Principle #1Segmentation

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

This solution allows for a simple and effective manufacturing process of ultrasonic touch sensors that can reliably detect touches on various surfaces, including metallic ones, by optimizing acoustic coupling and reducing interference, thereby improving touch detection accuracy.

Implementation Method 1

the first ultrasonic transducer element to transmit ultrasonic waves through the casing

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

The first ultrasonic transducer element is configured to detect ultrasonic waves reflected from the touch surface

Methodology Applied

Scientific EffectUltrasonic detection: Ultrasound

Implementation Method 3

acoustic coupling materials to enhance surface attachment and reduce interference

Methodology Applied

Scientific EffectAcoustic coupling: Acoustics

Data Source

PatentUS12135853B2Ultrasonic touch sensor

Publication Date: 2024.11.05 INFINEON TECHNOLOGIES AG

AI summary

What is proposed is an ultrasonic touch sensor having a contact surface for attaching the ultrasonic touch sensor to a casing, having a first ultrasonic transducer element, having a first semiconductor chip, wherein the first semiconductor chip comprises the first ultrasonic transducer element, wherein the first semiconductor chip is potted into a potting compound in such a way that a first cutout is formed from the first ultrasonic transducer element to the contact surface of the ultrasonic touch sensor, and wherein the potting compound forms the housing of the ultrasonic touch sensor.