Touch Panel Display Device with Insulating Film Thickness Adjustment
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Solution Overview
Problem
The sensing sensitivity of touch sensors in integrated display devices is compromised due to their arrangement in the same layer as the gate electrode of a TFT, leading to reduced performance.
Innovation Solution
A touch panel-attached display device design where the touch sensor wiring is positioned between insulating films closer to the surface than the display control element, with a thicker second insulating film layer between counter electrodes and touch sensor wiring to reduce parasitic capacitance, enhancing sensing sensitivity and display performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the touch sensor wiring is arranged in the same layer as the gate electrode of the TFT, then the device structure is simplified, but the sensing sensitivity of the touch sensor is lowered
Solution Approach 1:
The touch sensor wiring is moved from the same layer as the gate electrode to an intermediate position between insulating films, effectively changing its spatial dimension and layer position. This dimensional repositioning allows the wiring to be closer to the panel surface while maintaining structural integration, thereby improving sensing sensitivity without significantly increasing device complexity.
Solution Approach 2:
The touch sensor wiring is positioned between the first and second insulating films, using these insulating films as intermediary layers. This intermediary positioning allows the wiring to function as both a display control element connection and a touch sensing element, resolving the contradiction by creating a multi-functional intermediate structure that improves sensitivity while maintaining integration.
2Measurement precision
If the second insulating film thickness between counter electrode and touch sensor wiring is increased, then parasitic capacitance is reduced and sensing sensitivity is improved, but the overall film stack becomes thicker
Solution Approach 1:
The second insulating film is designed with non-uniform thickness, being thicker specifically in the region between the counter electrode and the touch sensor wiring. This local quality variation reduces parasitic capacitance where needed without uniformly increasing the entire film stack thickness, thereby improving sensing sensitivity while minimizing the overall thickness increase.
Solution Approach 2:
The thickness parameter of the second insulating film is specifically adjusted in the region between the counter electrode and touch sensor wiring. By changing this local thickness parameter, the parasitic capacitance is reduced and sensing sensitivity is improved, while the overall film stack thickness increase is minimized through targeted rather than uniform thickening.
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 improves touch sensing sensitivity and display performance by reducing parasitic capacitance and increasing the capacitance between pixel and counter electrodes, allowing for more accurate touch position detection and better image display.
Implementation Method 1
a plurality of counter electrodes formed on the active matrix substrate further to the liquid crystal layer side than the second insulating film and forming an electrostatic capacitance between each of the counter electrodes and each of the pixel electrodes
Implementation Method 2
since a thickness of a portion formed between the counter electrode and the touch sensor wiring in the second insulating film is thicker than that of a portion formed between the pixel electrode and the counter electrode, it is possible to reduce parasitic capacitance between the counter electrode and the touch sensor wiring
Data Source
AI summary
To improve sensing sensitivity of a touch panel. A touch panel-attached display device includes an active matrix substrate 1, a counter substrate, and a liquid crystal layer. On the active matrix substrate 1, a TFT (display control element) 42, a first insulating film 44, a plurality of pixel electrodes 31, a second insulating film 46, and a counter electrode 21 are laminated in order. In the active matrix substrate 1, a control unit which detects a touch position by supplying a touch driving signal to a plurality of counter electrodes 21, and a touch sensor wiring 22 which is formed between the first insulating film 44 and the second insulating film 46, which connects the control unit and the counter electrode 21, and which is for supplying the touch driving signal from the control unit to the counter electrode 21, are also formed. A thickness of a portion in the second insulating film 46 formed between the counter electrode 21 and the touch sensor wiring 22 is thicker than a thickness of a portion formed between the pixel electrode 31 and the counter electrode 21.