Piezo Actuator Embedded in Stepped Glass Substrate for Thin Touch Panel Haptic Feedback

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Solution Overview

Problem

Conventional touch panel devices with haptic feedback require large actuator force and displacement, necessitating high voltage inputs, which is impractical for thin electronic devices like mobile phones, resulting in thicker displays due to the need for separate actuators beneath heavy liquid crystal or touch panels.

Innovation Solution

A low-profile touch panel device design featuring a transparent protective substrate formed by joining two glass substrates, with stepped portions on one substrate to house piezo vibration elements, allowing efficient transmission of small vibrations to the front surface, reducing the need for high actuator force and maintaining a thin profile.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a haptic actuator is disposed on the bottom or rear surface of a heavy liquid crystal panel or touch panel, then haptic feedback can be provided, but the device becomes thicker and requires high voltage input

Engineering Contradiction:

Improvehaptic feedbackVSAvoiddevice thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent merges the protective substrate and the haptic actuator into a single integrated component. The piezoelectric actuator is embedded within the protective substrate itself, eliminating the need for a separate actuator layer beneath the display panel. This integration reduces overall device thickness while maintaining haptic feedback functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions from a planar arrangement where actuators are placed beneath the display panel to a three-dimensional embedded structure within the protective substrate. By creating stepped portions at different height levels within the substrate, the actuator is positioned in a vertical dimension that allows efficient vibration transmission to the front surface without increasing overall device thickness.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If a haptic actuator is disposed on the bottom or rear surface of a heavy liquid crystal panel or touch panel, then haptic feedback can be provided, but high voltage input is required

Engineering Contradiction:

Improvehaptic feedbackVSAvoidvoltage input

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent introduces the protective substrate as an intermediary structure that efficiently transmits vibrations from the embedded piezoelectric actuator to the front surface of the device. This intermediary structure amplifies and transmits the mechanical vibrations effectively, allowing the use of lower voltage inputs while maintaining sufficient haptic feedback strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Force

If an actuator generates large actuator force and displacement, then sufficient haptic effects can be provided, but the device requires thicker construction

Engineering Contradiction:

Improveactuator forceVSAvoiddevice thickness

Core Design Contradiction:

ForceVSLength of stationary object

Solution Approach 1:

The patent applies local quality by creating stepped portions within the protective substrate that concentrate and focus the vibrational energy locally. The actuator is positioned in a specific region with optimized structural properties that enhance force transmission efficiency to the front surface, eliminating the need for large overall actuator force and displacement.

Inventive Principle:

Principle #3Local quality

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 design effectively transmits vibrations with smaller actuator force and displacement, providing enhanced haptic effects while maintaining a slim form factor, as demonstrated by increased displacement and acoustic pressure measurements compared to conventional devices.

Implementation Method 1

one or more piezo vibration elements each disposed within one of the stepped portions so as to be acoustically coupled with the first glass substrate

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

one or more piezo vibration elements each disposed within one of the stepped portions so as to be acoustically coupled with the first glass substrate

Methodology Applied

Scientific EffectAcoustic coupling: Acoustic Radiation Pressure

Data Source

PatentUS8884897B2Touch panel device and electronic device with improved haptic feedback

Publication Date: 2014.11.11 AIST SOLUTIONS CO

AI summary

A touch panel device, includes a transparent protective substrate disposed on a front side of the touch panel, the protective substrate being configured by joining a first glass substrate residing on a front side and a second glass substrate residing on a touch panel side, wherein either one of the first and second glass substrates is configured to have one or more stepped portions formed either on a rear surface of the first glass substrate or a front surface of the second glass substrate, the rear surface of the first glass substrate and the front surface of the second glass substrate facing one another; and one or more piezo vibration elements each disposed within one of the stepped portions so as to be acoustically coupled with the first glass substrate, wherein each of said one or more stepped portions is configured thicker than the corresponding piezo vibration element.