Touchscreens evolve from GG and GFF to G1, G2 architectures


Demand is sharply increasing for projected capacitive (PROCAP) touchscreen display panels, used in smartphones and tablets, but capacitive touch panel structures are unique to each company. This core technology must be advanced and differentiated to enable more touch devices, says Displaybank. Technical issues and a lack of cooperation could restrain touchscreen growth.

PROCAP touchscreen architectures. SOURCE: Displaybank.

In general, capacitive touch can be classified into glass- or film-substrate produced. Glass-substrate capacitive touchscreens are found in Apple's iPhone and Samsung's Galaxy S phone. The iPhone uses a glass-glass (GG) structure that forms the X-axis sensing electrode on the upper surface of a glass substrate and Y-axis sensing electrode on the bottom. While Apple's GG method and other mobile phone makers' glass/film (GFF) designs are becoming mainstream, attempts to develop products such as G1F, and G2 with better transmittance and thinness will continue. G2 is cover window integrated touch, which does not require separate touch sensor.

The advantages of GFF are low capital cost, suitable for small quantity batch production, and light structure. GG is suitable for mass production and has better appearance properties, but it has high investment costs and is heavier than film-based panels.

Displaybank looked at the evolution of touchscreen technologies by examining Apple's related patents: the main ideas of these patents, technical information, and technology flow. They selected 7 key patents for Apple's double-sided indium tin oxide (DITO) and single-sided ITO (SITO), and also referred to Apple and Motorola's patent dispute issue and product analysis result of Apple's iPhone 4S.???M.C.

Solid State Technology, Volume 55, Issue 4, May 2012

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