Single-Layer Metal Touch Screen for Large Display Areas
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Solution Overview
Problem
Conventional touch screens with ITO wires have high impedance, limiting the number of wires in the dummy area and restricting the size of touch screens to small sizes due to the narrow width and spacing of ITO wires.
Innovation Solution
A touch screen design featuring a single-layer metal electrode array with driving and sensing electrodes formed on a transparent substrate, where the electrodes and wires are arranged in a grid pattern with alternate rows and columns, and wires are connected to a bonding pad in the peripheral region, allowing for increased wire density and larger screen sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ITO wire is used with standard width and spacing (30 μm/30 μm), then the manufacturing process is simple, but the number of wires in the dummy area is limited (less than 36 wires), which restricts the touch screen size to small dimensions (maximum 8.1 cm)
Solution Approach 1:
The patent reduces the wire width and spacing parameters from the conventional 30 μm/30 μm to 10 μm/10 μm or smaller. This parameter change allows significantly more wires to be accommodated in the dummy area (increasing from less than 36 to over 100 wires), thereby enabling larger touch screen sizes while maintaining the same manufacturing process approach
Solution Approach 2:
The patent utilizes the peripheral dummy area more efficiently by optimizing the two-dimensional arrangement of wires in both width and length directions. By reducing wire dimensions and optimizing the grid pattern arrangement, the design maximizes the use of available peripheral space to accommodate additional wires without requiring extra dimensional space
2Quantity of substance
If the dummy area width is increased to accommodate more wires, then more driving electrodes can be supported, but the active display area is reduced and the overall product complexity increases
Solution Approach 1:
The patent applies different functional qualities to different regions of the touch screen: the central region maintains high-quality transparent ITO for optimal touch sensing performance, while the peripheral dummy area uses reduced-dimension wires optimized for routing. This local differentiation allows dense wire routing in the periphery without compromising the active display and sensing area in the center
Solution Approach 2:
The patent segments the touch screen into distinct functional zones: a central active area for touch sensing and a peripheral dummy area for wire routing. This segmentation allows independent optimization of each region - the active area maximizes display and sensing performance while the peripheral area maximizes wire capacity, thereby supporting more driving electrodes without reducing the active display area
3Reliability
If ITO wire impedance is reduced by increasing wire width, then more current can be carried, but the spacing between wires must be increased, reducing the number of wires that can fit in the dummy area
Solution Approach 1:
The patent changes the wire dimension parameters to 10 μm width and 10 μm spacing (or smaller), which optimizes the balance between impedance and wire density. This parameter change allows maintaining low impedance for reliable signal transmission while accommodating a much higher number of wires (over 100) in the dummy area compared to conventional designs
Data Source
AI summary
The disclosure provides a touch screen which comprises a transparent substrate having a surface which includes a central region and a peripheral region, an electrode array arranged in the central region and formed by a plurality of driving electrodes and a plurality of sensing electrodes, which are arranged on the surface of the transparent substrate, and multiple wires formed on the surface of the transparent substrate for electrically connecting each electrode in the electrode array to an external touch driving circuit, wherein all the electrodes in the electrode array and the multiple wires are formed by a single-layer metal which is formed on the surface of the transparent substrate. The disclosure further provides a manufacturing method of the touch screen. The manufacturing method comprises the step of forming the driving electrodes, in which the driving electrodes, the sensing electrodes and the wires connecting the electrodes of the touch screen are formed simultaneously of the single-layer metal which are directly formed on the surface of the transparent substrate. The disclosure further provides a display device comprising the touch screen.