Touch Panel Switching Elements for Fringe Field Noise Reduction
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Solution Overview
Problem
Fringe electric fields generated between drive and lead wirings in touch panels can cause touch noise and false detection when shielded by conductive objects, leading to inaccuracies in touch detection.
Innovation Solution
Incorporating switching elements between detection electrodes and peripheral wirings, which are initially set to an off-state with a predefined voltage applied, allowing the detection of voltage changes in drive electrodes and subsequently switching to an on-state to eliminate the effects of fringe electric field couplings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fringe electric fields are generated between drive and lead wirings, then touch panel operation is enabled, but touch noise and false detection occur when shielded by conductive objects
Solution Approach 1:
The patent extracts and removes the harmful fringe electric field coupling effect by introducing switching elements that disconnect the lead wirings from the detection circuit during periods when they would generate interference. This separates the useful signal path from the harmful coupling path, eliminating touch noise and false detection caused by conductive objects shielding the fringe fields.
Solution Approach 2:
The patent applies preliminary action by pre-configuring switching elements in an off-state before touch detection occurs. This preliminary disconnection prevents the fringe electric field coupling from occurring in the first place, rather than attempting to correct the interference after it occurs. The switching elements are set to block the harmful coupling path before the drive electrodes generate their electric fields.
2Measurement precision
If switching elements are added between detection electrodes and peripheral wirings, then touch detection accuracy improves, but device complexity increases
Solution Approach 1:
The switching elements introduced in the patent serve multiple functions: they act as isolation switches to block fringe electric field coupling, signal routing switches to connect/disconnect lead wirings from detection circuits, and noise filtering switches. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving improved touch detection precision.
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 configuration enhances the accuracy of touch detection by eliminating the impact of fringe electric field couplings between drive and lead wirings, reducing false detection and improving overall touch detection precision.
Implementation Method 1
fringe electric fields are generated between the outermost drive electrodes of plural drive wirings and plural lead wirings (peripheral wirings)
Implementation Method 2
the position coordinate of a touched position is specified by detecting the changes of electric fields between the plural drive electrodes and the plural detection electrodes, in other words, by detecting the changes of mutual capacitances
Data Source
AI summary
A technology which can improve the accuracy of touch detection is proposed. A display device includes: a touch panel including plural drive electrodes and plural detection electrodes; plural peripheral wirings; and plural switching elements each of which is disposed between a detection electrode and the corresponding peripheral wiring and that is connected to the detection electrode and the corresponding peripheral electrode. The touch panel executes detection by means of a mutual detection scheme using the plural drive electrodes and the plural detection electrodes. In a condition in which a predefined voltage is applied to the peripheral wirings when the plural switching elements are in an off-state, the voltages of the drive electrodes are changed, and subsequently a condition in which the changes of the voltages of the drive electrodes can be detected from the peripheral wirings is set, and the switching elements are turned from off to on.