Grounded Peripheral Electrode Layout for Low-EMI Touch Displays
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Solution Overview
Problem
Existing display devices with input sensors suffer from electromagnetic interference (EMI) due to unnecessary electromagnetic signals radiated from the sensing electrodes, which can hinder the operation of other devices.
Innovation Solution
The display device incorporates an input sensor with a sensing area and a non-sensing area, featuring a plurality of sensing patterns, signal lines, a ground line, and an additional electrode in the non-sensing area. The additional electrode is electrically connected to the ground line and overlaps the sealing member, while the signal lines and ground line do not overlap with the sealing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If sensing electrodes are used to detect user input in a capacitive scheme, then touch sensing capability is achieved, but electromagnetic interference is generated that hinders operation of other devices
Solution Approach 1:
The patent applies shielding electrodes that generate electromagnetic signals opposite in phase to the sensing electrodes, converting the harmful electromagnetic radiation into a beneficial shielding effect. The shielding electrodes are driven with inverted phase signals to create counteracting electromagnetic fields that cancel out the radiation from sensing electrodes, thus eliminating EMI while preserving touch sensing functionality.
Solution Approach 2:
The patent introduces shielding electrodes as an intermediary element between the sensing electrodes and other devices. These shielding electrodes act as a mediator that intercepts and redirects electromagnetic radiation, preventing it from reaching other devices while maintaining the capacitive touch sensing capability of the original sensing electrodes.
2Reliability
If signal lines are placed in the non-sensing area for connection, then electrical connection is achieved, but electromagnetic interference increases due to proximity to sensing areas
Solution Approach 1:
The patent positions shielding electrodes between the signal lines and the sensing areas, creating an electromagnetic barrier that protects the signal lines from interference while allowing electrical connections to be made in the non-sensing area. The shielding electrodes serve as an intermediary shield that blocks electromagnetic coupling between signal lines and sensing patterns.
3Object-generated harmful factors
If the area of conductive pattern receiving ground voltage is increased, then electromagnetic interference is reduced, but device complexity increases
Solution Approach 1:
The patent makes the shielding electrodes multi-functional by having them serve both as electromagnetic shields and as part of the ground reference system. The shielding electrodes are electrically connected to ground, allowing them to perform both shielding function and provide a stable voltage reference, thus reducing EMI without proportionally increasing complexity.
Solution Approach 2:
The patent merges the shielding function with the ground reference function by electrically connecting the shielding electrodes to ground. This combination allows a single structural element to perform multiple functions: providing electromagnetic shielding and establishing a ground reference, thereby reducing overall device complexity compared to having separate shielding and grounding systems.
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 reduces electromagnetic interference by increasing the area of the conductive pattern receiving a ground voltage, thereby decreasing the differences in capacitances between sensing electrodes and signal lines, and enhancing the sensing performance of the display device.
Implementation Method 1
An additional electrode is in the non-sensing area. The additional electrode is electrically connected to the ground line. The additional electrode overlaps at least a portion of the sealing member on a plane
Implementation Method 2
the input sensor disposed on the display panel may detect an input of the user in a capacitive scheme. In the capacitive scheme, a driving signal is applied to sensing electrodes included in the input sensor, and a change in the capacitance of the sensing electrodes is output as a sensing signal
Data Source
AI summary
A display device includes a display panel including an active area, and a peripheral area adjacent to the active area. An input sensor is on the display panel. The input sensor includes a sensing area corresponding to the active area, and a non-sensing area corresponding to the peripheral area. The input sensor includes a plurality of sensing patterns disposed in the sensing area. A plurality of signal lines are connected to the plurality of sensing patterns, respectively. The plurality of signal lines is in the non-sensing area. A ground line is disposed in the non-sensing area. The ground line receives a ground voltage. An additional electrode is in the non-sensing area. The additional electrode is electrically connected to the ground line. The display panel includes a sealing member disposed in the peripheral area. The additional electrode overlaps at least a portion of the sealing member on a plane.