Touch Sensor Shielding in Thin Display Devices
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Solution Overview
Problem
As display devices become thinner, the proximity between touch sensors and signal lines increases, leading to incorrect touch input detection due to signal noise, and potential defects from moisture-induced outgas during manufacturing.
Innovation Solution
The display device incorporates a touch sensor with a touch line positioned in the non-active area, shielded by the anode electrode and encapsulation layer, which includes strategically placed holes to prevent overlap with the touch line and to allow outgas discharge, thereby reducing noise interference and preventing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the display device thickness is reduced, then the device becomes thinner and more aesthetically pleasing, but the distance between the touch sensor and signal line decreases causing noise interference and incorrect touch detection
Solution Approach 1:
A shielding layer is introduced as an intermediary component between the touch sensor and the signal line. This shielding layer acts as a mediator that blocks electromagnetic noise from the signal line from interfering with the touch sensor, thereby maintaining touch detection accuracy even when the display device thickness is reduced.
Solution Approach 2:
The harmful electromagnetic noise is extracted and isolated from the touch sensor by introducing a separate shielding layer. This allows the touch sensor to operate independently without being affected by the signal line's electromagnetic interference, resolving the contradiction between thinness and reliability.
2Ease of manufacture
If multiple stacked films are formed during manufacturing, then the display device structure is complete, but moisture remains in the films causing outgas and lifting between films
Solution Approach 1:
A porous layer is introduced into the stacked films structure. This porous layer provides channels for outgas to escape during and after the manufacturing process, preventing the accumulation of gas that would cause lifting between films. The porous structure maintains film adhesion while allowing moisture-induced outgas to be discharged.
Solution Approach 2:
The porous layer is incorporated during the manufacturing process to preemptively provide outgas pathways before lifting can occur. This preliminary structural preparation prevents the harmful effect of trapped moisture and gas from compromising film adhesion.
3Length of moving object
If the touch sensor is positioned closer to the signal line for thinning, then the device profile is improved, but the touch sensor incorrectly detects signals and voltage from the signal line as noise
Solution Approach 1:
A shielding layer is positioned between the touch sensor and signal line to act as an electromagnetic barrier. This intermediary layer blocks the signal line's electromagnetic fields from being detected by the touch sensor, ensuring that only actual touch inputs are detected even when the components are positioned close together for a thin profile.
Solution Approach 2:
The close proximity of the signal line, which initially causes harmful electromagnetic interference, is converted into a benefit by using it as an opportunity to implement a thin shielding layer. The shielding layer transforms the potential harm of electromagnetic coupling into a controlled environment where the thin structure is maintained without sacrificing measurement precision.
Data Source
AI summary
A display device may comprise a substrate including an active area, in which one or more pixels are disposed, and a non-active area outside the active area, the substrate being formed of glass or polyamide; a planarization film disposed over the substrate; an anode electrode disposed on the planarization film; a bank disposed on the anode electrode; and at least one touch sensor disposed on the substrate, a part of the at least one touch sensor being disposed in the non-active area. Here, the anode electrode may comprise at least one first anode hole which at least partially overlaps with a gate signal generation circuit in the non-active area.