Monolithic Haptic Touch Screen With EAP Film for Thin Displays
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Solution Overview
Problem
Existing touch screens with integrated haptic feedback units increase device thickness and cost due to the placement of haptic feedback units below the display panel, leading to inefficient haptic delivery and high manufacturing costs, especially when using piezoelectric ceramic.
Innovation Solution
A monolithic haptic-type touch screen utilizing an insulating film made of doped electroactive polymer (EAP) with upper and lower electrodes for both touch recognition and haptic feedback, positioned above the display panel, reducing thickness and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a haptic feedback unit (vibration motor or piezoelectric ceramic) is positioned below the display panel, then the touch screen can provide haptic feedback, but the overall thickness of the display device increases and haptic feedback delivery becomes inefficient
Solution Approach 1:
The patent combines the touch screen and haptic feedback unit into a single integrated structure. The touch screen includes both touch sensing electrodes and haptic actuation electrodes formed on the same substrate, eliminating the need for a separate haptic feedback unit positioned below the display panel. This integration reduces the overall thickness while maintaining effective haptic feedback delivery directly at the touch interface.
Solution Approach 2:
The touch screen is designed to perform multiple functions: touch sensing and haptic feedback generation. The same electrode structure and driving method are used for both recognizing touch inputs and generating haptic outputs, making the touch screen a multi-functional component that eliminates the need for dedicated separate haptic feedback hardware.
2Reliability
If multiple vibration motors are used to deliver uniform vibrations, then haptic feedback can be improved, but the thickness and size of the display device increase
Solution Approach 1:
The haptic feedback unit is divided into multiple independent electrode regions that can be individually controlled. Each electrode region corresponds to a specific area of the touch screen and can generate localized vibrations. This segmentation allows uniform haptic feedback across the entire display area without requiring multiple large vibration motors, as each electrode segment contributes to the overall uniformity through coordinated operation.
Solution Approach 2:
Different regions of the haptic feedback unit have different electrode configurations optimized for their specific locations. The electrode patterns and driving signals are tailored to provide appropriate haptic feedback characteristics for each local area, ensuring uniform overall performance while using a single integrated unit rather than multiple large motors.
3Speed
If piezoelectric ceramic is used for haptic feedback, then response speed is enhanced, but manufacturing cost increases due to high-priced piezoelectric ceramic
Solution Approach 1:
The patent replaces expensive piezoelectric ceramic with a cost-effective alternative material for the haptic feedback unit. The new material achieves comparable response speed performance but at a lower manufacturing cost, making the overall display device more economically viable while maintaining the enhanced response speed characteristic.
Solution Approach 2:
The invention changes the material parameter of the haptic feedback unit from piezoelectric ceramic to an alternative material with different physical properties. This parameter change maintains the fast response speed requirement while significantly reducing the manufacturing cost, as the alternative material is more abundant and easier to process.
4Speed
If piezoelectric ceramic is used, then response speed is enhanced, but haptic feedback delivery becomes challenging due to opaque characteristics requiring disposal in the lowermost portion
Solution Approach 1:
The patent extracts the opacity constraint from the haptic feedback unit design by using a transparent or translucent alternative material to piezoelectric ceramic. This allows the haptic feedback unit to be positioned in the upper portion of the display device, closer to the user interface, enabling accurate and direct haptic feedback delivery without the need to place it in the lowermost portion behind opaque materials.
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 solution enables prompt and accurate haptic feedback directly to the user, reduces device thickness, and allows for localized haptic outputs, enhancing user experience while minimizing material and manufacturing costs.
Implementation Method 1
an insulating film including doped ferroelectric material in an electroactive polymer (EAP)
Implementation Method 2
formed of piezoelectric ceramic
Implementation Method 3
the touch screen 4 recognizes the touch input by capacitance generated between the upper electrode 4a and the lower electrode 4c
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A monolithic haptic-type touch screen capable of performing both touch recognition and haptic feedback are provided. The monolithic haptic-type touch screen includes an insulating film formed by doping ferroelectric material in an electroactive polymer (EAP), an upper electrode formed on an upper surface of the insulating film, and a lower electrode formed on a lower surface of the insulating film and corresponding to the upper electrode.