The Next Generation Touch Technology Experience

The right touch for your environment

 

Executive Summary


Not all touchscreen technologies are created equal. The latest tablets and smartphones all incorporate projected capacitive touch technology, PCT or PCAP screens, as it’s the most advanced and fool-proof solution on the market. However, such high-grade technology doesn’t come cheap, which is why the size of the device has been a limiting factor in the progress of PCAP market share. Until now, scaling PCAP to larger screen sizes, 24+ inches, has priced out many customers, but Elo is changing all that.

 

1. Touch Technology Overview


As the interactive technology sector experiences an explosion in growth, understanding the touchscreen technology powering the experience is more important than ever. With decades of proven use in consumer settings, projected capacitive touch technology (PCAP) is likely a technology you will encounter more and more in commercial retail, gaming or self-service environments.

 

Why does the touch technology matter?


There are many touch technologies available for interactive displays, including resistive, infrared, optical, surface acoustic wave (SAW) and surface capacitive, which have been powering touch applications successfully for over 40 years. Touch technology is found in almost every industry including medical, industrial, retail, restaurants, transportation, and banking. Each has a niche for specific applications, environments, and users depending on requirements and characteristics of the technology. Considerations range from whether the user engages with a stylus, fingernail or glove touch activation, what the appropriate temperature range is, how important optical clarity is, to vandal resistance, price, and other factors. Regardless of the technological needs, one technology stands above the rest in terms of functionality, durability, and maintenance requirements – PCAP. Considered the best-in-class touch technology, PCAP is becoming more affordable and accessible too. It is also the most recognized and pervasive today as it powers the technology in our pockets – our smartphones.

 

2. Benefits of PCAP technology


The benefits of PCAP technology are numerous. PCAP technology allows simultaneous 10+ finger multi-touch, with fast, accurate, and extremely sensitive touch response, and optional treatments like anti-glare and anti-vandal glass. PCAP does not register false touches with liquid and functions even with deep scratches. Importantly, this technology allows for true-flat screen designs, where bezels have been needed for most other touchscreen technology, which makes for modern designs that are also easy to clean. It is capable of registering touch through additional cover glass 6 mm or more, with a trade-off in accuracy and number of touches, but still working beautifully for outdoor ticketing machines subject to vandalism, or as multiple touch monitors under a countertop made from a single piece of glass.

 

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3. Types of PCAP technology


It is important to understand that there are many different variations of PCAP, with specific costs and product outcomes associated with each. To ensure the best performance and lowest maintenance and failure rates, customers should make sure the PCAP technology purchased is proven to work for the application intended.
These PCAP solutions work basically the same way. Two grids patterned vertically and horizontally for X and Y are laminated in a sandwich with a glass cover layer. A high frequency electronic signal creates an electric field which projects through and above the glass. A finger touch disturbs the field and the controller interprets this to pinpoint the touch location. Multiple simultaneous touches can be determined. Different stack up constructions of PCAP relate to the different methods by which the conductive grid is created and applied to glass or plastic film. The large amount of PCAP technologies and conductive trace materials makes deciding which to use for your application challenging.

 

OnCell, InCell


These technologies have the PCAP sensor pattern embedded in or on the LCD display layers and thus the touch sensor is incorporated. This type of technology is mostly used in small sensors for smart phones and gets quite expensive in larger sizes, which has limited its commercial applications.

 

GF1


GF1 is a passive cover glass which is bonded to a one layer film sensor. Both the transmit and receive conductive traces are on the same side of the PET film (a type of plastic). This type of sensor is limited to applications with lower accuracy and smaller devices.


GF2


GF2 is a passive cover glass which is bonded to a film sensor which has conductive patterns on both sides. It could be designed with ITO for the conductive traces or other technologies like copper mesh, or silver metal halide. The film is usually made in a roll to roll process and is optimized for sizes from 8 to 24 inch. It has advantages of light weight, allowing small border widths, and single tail connection solutions. Elo provides GF2 solutions as a good alternative to 2GS construction where the application is in controlled environments.


GFF


In creating the Glass - Film - Film version of PCAP, the conductive grid is printed onto a thin PET material. The layers are stacked and laminated together with Optically Clear Adhesive (OCA). Many different competing technologies can be used for the conductive substrate including silver nano-wires, silver metal mesh, embedded wires, or even ITO can be used.

For metal mesh, the grid is composed of tiny wires arranged in a mesh pattern carefully arranged on layers of plastic film. With silver metal mesh the wire sizes are very small, 5-7 um, which cannot be seen with the naked eye and provide a very sensitive touch experience. Other constructions with embedded wires are visible and may distract the user and take away from aesthetics of the screen. Mesh is typically used in large display sizes, 32 inch up to 70 inch or greater. Elo uses silver metal mesh film solutions in a GFF stack up for its large screen sizes.

 

2GS


In the 2 Glass Solution, virtually invisible ITO conductive coating is sputtered on to the glass surface and then patterned by etching. The patterned ITO is on the facing sides of two layers of glass which are then laminated together using an optically clear adhesive. 2GS offers pristine optical clarity, higher touch durability, and long term stability over temperature, making it ideal for non-mobile applications in sizes from 10 to 27 inches.


2GS is the best choice for midsized displays


PCAP scales in price exponentially with size. For small devices, OnCell, InCell, GF makes the most sense due to its weight, thinness, and affordable cost at high volume which perfectly meets the requirements for consumer smartphones and tablets. For large sizes of interactive digital signage, GFF-metal mesh makes the most sense today, due to the weight and cost trade-offs and importantly it has the low resistance needed for screens greater than 32 inches, where using ITO is impractical. But for midrange sizes, 2GS, the highest quality and premium form of PCAP, offers the ideal combination of image quality, ruggedness, and long-term reliability within an affordable price range. Using 2GS in midrange sizes also mitigates the risks associated with GF2 and GFF PCAP used in commercial settings while staying within practical budgets.


It is important to understand the risks of adopting plastic film PCAP technology when it is not necessary versus 2GS. One risk of film solutions like mesh or GFF PCAP is delamination of the layers over time – a relatively new risk manufacturers have not experienced with other types of touch technologies. Delamination is caused by the plastic layer reacting differently to changes in temperature and humidity by expanding and contracting while the glass layer remains stable, creating constant stress on the adhesive used in the lamination. When the layers begin to peel apart, it is visible and requires screen replacement. This delamination risk increases with size, environments with wide temperature ranges, such as outside locations or ones without air conditioning or a kiosk enclosure adding to the ambient temperature, or horizontal usage where the convective heat transfer is through the display and touchscreen.


A second risk of film solutions are micro cracks in the ITO developing over time due to this same expansion and contraction. ITO is actually a conductive ceramic, quite brittle, and cracks can form not unlike what you might see in old dinner plates. While a micro crack is invisible, it affects the critical conductivity of the system and damages the touch performance. ITO on glass is therefore superior for long-term performance compared with ITO on plastic film. Humidity is a second risk factor. Humidity can’t penetrate glass, but it can penetrate plastic. A 2GS glass sandwich is therefore a better solution in markets like South East Asia and South America where high humidity can contribute to higher failure rates. Although, this is being improved over time by film manufactures, the plastic material (PET) in a GFF solution can yellow due to UV exposure or heat. Flat or slant-top machines, where more heat is radiated through the display compared to uprights, adds more risk of GFF failure. Displays that are outside or have higher UV light exposure may want to avoid film constructions.

Using all-glass 2GS PCAP eliminates the two layers of plastic film in GFF PCAP that is the cause of all three of these potential failures – delamination, yellowing, or degradation of touch performance. 2GS touchscreens are designed to last longer than the LCD panel, and are recommended whenever possible in the midrange sizes.


Perhaps the largest risk in choosing the wrong PCAP technology is the proliferation of manufacturers with factories throughout China producing low cost GFF screens. Overcapacity of PCAP manufacturing results in manufacturers cutting costs to stay competitive and thereby disregarding quality. Most PCAP screens come with no visible label indicating the manufacturer, so it may not even be apparent if the monitor company switches unnamed touchscreen manufacturers when one can't deliver, goes out of business, or is simply cheaper. Touch monitor companies not manufacturing the PCAP technology themselves often have no clear path for issue escalation and resolution. In addition there are many small start-up companies working on conductive materials for use on film substrates. It’s important to understand their business viability and weigh the risks before choosing the material used in your system.

 

4. Tuning


One difference of PCAP technology over resistive, SAW, and IR is that PCAP requires tuning of controller parameters that are specific to the design of the touch sensor and optimized for the display panel and product application. This makes it a little more complicated especially if different vendors are used for the touch sensor and the controller. A better solution is to find a vendor like Elo that can do both the touch sensor design and controller tuning and be responsible for the performance and testing of the complete system solution. So performance is equally driven from the touch panel design, the controller capabilities, electrical noise from the display, and the controller tuning.

 

5. Next generation touch


Elo manufacturers a completely integrated solution of touchscreen, touch screen controller with tuning, and display. All Elo monitors are designed for touch from the ground up. For Elo, touch technology is the core business, with touchscreens, software drivers, and all components built and tested together. For the best quality and durability, PCAP touch technology needs to be part of an integrated design, similar to a smartphone, not added as an afterthought to a non-touch monitor.


Today there are thousands of Elo 2GS units proven over years of use around the world in varied environments. Elo has significantly decreased the cost of 2GS when, in the past, cost may have been a prohibitive factor. Unlike competitors who have to purchase screens – typically film PCAP from external suppliers – Elo is manufacturing 2GS screens in their own PCAP factory. With some of the newest PCAP touch production machinery in all of Asia, and a factory in high volume production, Elo is able to pass the cost savings on to customers. Now, not only is PCAP in reach, but for the first time for many, so too is high quality 2GS.