Simultaneous Sensing Actuation Electrode Haptic Display
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Solution Overview
Problem
Current touch interfaces for surface haptic devices lack the ability to provide independent haptic effects to multiple fingers simultaneously due to limitations in electrostatic actuation and sensing technologies, which result in compromised multi-point haptics and multi-touch sensing capabilities.
Innovation Solution
The implementation of a touch interface system using 'simultaneous sensing and actuation' (SSA) with mirrored electrodes, where a top layer of electrodes on the surface provides haptic effects and a bottom layer senses touch points, enabling strong capacitive coupling and independent control of haptic forces on each finger through a single array of electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electrode layer is used for both sensing and actuation, then device complexity is reduced, but multi-point haptics capability deteriorates
Solution Approach 1:
The single electrode layer is segmented into multiple independently controllable electrode regions or segments. Each segment can be independently activated to provide haptic feedback at specific locations, enabling multi-point haptics while maintaining a simple single-layer structure.
Solution Approach 2:
The electrode layer transitions from a static, uniform structure to a dynamic, selectively activatable system. By dynamically controlling which portions of the electrode layer are activated at any given time, the system can provide independent haptic effects at multiple points simultaneously.
2Ease of manufacture
If electrodes are placed near the edge of the screen for easy connection, then ease of manufacture is improved, but haptic effect localization deteriorates
Solution Approach 1:
The solution moves from considering only the horizontal placement of electrodes (edge vs. center) to utilizing the vertical dimension by implementing a transparent electrode layer that can be positioned at different depths within the touchscreen structure, allowing edge connections while maintaining central haptic effects.
Solution Approach 2:
A transparent conductive layer or intermediary structure is introduced to bridge the connection between edge-mounted electrodes and the central touch surface. This intermediary allows electrical connection at the edges while maintaining the ability to generate localized haptic effects at the center.
3Measurement precision
If electrostatic charges are used for multi-touch sensing, then sensing capability is improved, but interaction with electrostatic haptics deteriorates
Solution Approach 1:
The system uses periodic modulation of electrostatic charges at different frequencies for sensing and haptics functions. By assigning different temporal patterns to sensing and actuation signals, the system can distinguish between sensing charges and haptic charges, eliminating interference while maintaining both functions.
Solution Approach 2:
The system differentiates between sensing and haptics electrostatic charges by using different voltage levels or polarity patterns (analogous to color coding). This allows the control system to identify and process sensing signals separately from haptic signals, preventing interaction between the two functions.
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 approach allows for reliable multi-point haptics and improved multi-touch sensing by ensuring that each finger receives independent haptic effects and accurate finger location detection, even when fingers are close together, while maintaining robustness against scratches on the surface electrodes.
Implementation Method 1
electrostatic actuation has been explored as a means to generate vibrations localized to the fingertip
Implementation Method 2
The basis of electrostatic haptics is the modulation of frictional force as a result of directly affecting the normal force between the finger and a touch surface of a touch interface via an electric field
Implementation Method 3
The most common technique for multi-touch sensing is 'projected capacitive' sensing, which also makes use of electrostatic charges
Data Source
Figure 1a~1b
Figure 2
Figure 3a~3b
AI summary
Touch interface devices and methods for producing multi-point haptics utilizing simultaneous sensing and actuation are disclosed. In one configuration, one or more electrodes connected to a front surface of a substrate are arranged in a pattern and connected to an electronic controller configured to produce a haptic effect by applying one or more voltages to the electrodes, and measure the locations of one or more touch points by applying one or more voltages to the electrodes. In another configuration the electronic controller is configured to produce a haptic effect by applying positive and/or negative voltages to the electrodes, and measure the locations of one or more touch points by applying positive and/or negative voltages to the electrodes. Also disclosed is a method for using a single set of electrodes on a substrate of a touch interface to simultaneously produce haptic effects on the substrate and measure finger locations relative to the substrate.