Touch Display Multiplexer for Simultaneous Electrode Sensing
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Solution Overview
Problem
Touch display devices face challenges in effectively sensing a large number of touch electrodes with a limited number of channels in the touch driving circuit, requiring a multiplexer that can efficiently manage and control the driving timing for accurate touch recognition.
Innovation Solution
A multiplexer is designed to select and connect touch electrodes to sensor sensing units, allowing for simultaneous sensing in a predetermined region during a specific time, with the ability to change the sensed region according to sensing time, and supporting both differential and simultaneous driving schemes, enabling effective touch driving and display driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a multiplexer is used to connect a large number of touch electrodes to a limited number of channels, then the touch driving circuit can sense more touch electrodes, but the device complexity and driving timing control difficulty increase
Solution Approach 1:
The multiplexer is divided into a first multiplexer for selecting sensing electrodes and a second multiplexer for selecting reference electrodes. This segmentation allows independent control of sensing and reference electrode selection, reducing the complexity of managing all electrodes through a single multiplexer while enabling efficient use of limited channels.
Solution Approach 2:
The patent introduces a two-dimensional selection approach where electrodes are selected not only by row but also by column coordinates. This dimensional approach allows systematic organization of electrode selection, making the control of large numbers of electrodes more manageable through structured addressing rather than complex routing.
2Productivity
If a multiplexer is used to manage touch electrodes with limited channels, then channel utilization improves, but the driving timing control becomes very difficult
Solution Approach 1:
The patent applies preliminary action by pre-configuring the multiplexer to select groups of electrodes based on predetermined sensing regions. The sensing electrode selection and reference electrode selection are prepared in advance according to the sensing time and region requirements, which simplifies the timing control during actual operation.
Solution Approach 2:
The multiplexer configuration is made dynamic by allowing the sensing region to be changed according to sensing time. The first and second multiplexers can be controlled to select different electrodes for different sensing regions and time periods, providing flexible timing control that adapts to different operational requirements.
3Speed
If simultaneous sensing of multiple touch electrodes is enabled, then sensing speed improves, but parasitic capacitance effects increase
Solution Approach 1:
The patent introduces dummy electrodes as intermediaries to manage parasitic capacitance effects. These dummy electrodes are selectively connected to compensate for the parasitic capacitance introduced by simultaneous sensing of multiple real touch electrodes, thereby maintaining sensing accuracy while enabling faster parallel sensing operations.
4Adaptability or versatility
If the sensing region is changed according to sensing time, then sensing flexibility improves, but the control complexity increases
Solution Approach 1:
The first and second multiplexers are designed with universal functionality to handle both sensing electrode selection and reference electrode selection. This multi-functionality allows the same hardware structure to support different sensing regions and configurations without requiring separate dedicated circuits, thereby reducing overall control complexity while maintaining flexibility.
Data Source
AI summary
A touch display device includes: a touch panel including N touch electrodes; a sensor sensing unit block including M sensor sensing units and to sense two or more touch electrodes among the N touch electrodes; a front multiplexer to select two or more touch electrodes from among the N touch electrodes and connect the selected touch electrodes to the sensor sensing unit block. The front multiplexer is configured to select M touch electrodes, which are disposed in a sensing active region corresponding to a first sensing period, from among the N touch electrodes, and to match and connect the M touch electrodes to the M sensor sensing units, wherein M is greater than or equal to 2, and N is greater than M. The M sensor sensing units are configured to simultaneously sense the M touch electrodes disposed in the sensing active region during the first sensing period.