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Mobile Touchscreen Technology: Capacitive, Resistive, Multi-Touch & The Future

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In our on-going series of articles about mobile technology, we’ve been looking at various different parts of your mobile phone and how the technologies behind them combine together to bring you today’s smartphone. We’ve also been asking how you’d put your ideal smartphone together, and which smartphones you’d recommend to other giffgaff members.

 

So far in this series, we’ve looked at mobile operating systems and user interfaces, compared LCD displays to organic LED displays and looked at how GPS and location-aware apps work. In terms of the way that we interact with our handsets, we’ve compared hardware keyboards to software keyboards and investigated voice recognition technologies such as Apple’s Siri. This week we turn our attention to smartphone touchscreens and the tactile interfaces through which we now interact with our smartphones every day.

 

History of Touchscreens

 

Ericsson R380.jpgTouchscreen technology has been around in society since the early 1970s and within mobile devices as early as the start of the millennium in the form of a pressure-sensitive resistive touchscreen. In terms of touchscreen devices becoming mainstream, it wasn’t until the launch of the Apple iPhone in 2007 that touchscreen became popular, particularly those of the capacitive variety. Whilst some consumers are still incredibly attached to hardware keyboards and are holding out from purchasing a touchscreen smartphone, the vast majority of smartphone devices sold today now come with a touchscreen.

 

In this article, we look at how touchscreens work and the key technologies behind them. We’ll also explore the future of touchscreens: will they be here to stay or could the smartphones of the future go one step further and become touch-free and gesture-based? Will the touchscreen smartphones of the future look substantially different to what we have today?

 

Resistive Touchscreens: Pressure Sensitive

 

LG Cookie.jpgMany of the first touchscreen PDAs and mobile phones used resistive touchscreen technology. A resistive touchscreen consists of two flexible plastic sheets: the uppermost sheet being designed to bend under pressure. When the two sheets are pressed together (for example by your finger or a stylus), a voltage is registered at that point which allows the phone to register your touch.

 

As a reasonable amount of pressure is often required to bend the plastic sheet, resistive touchscreens are often operated using a fingernail or stylus. As pressure is force divided by area, the amount of pressure exerted on the touchscreen can be increased by reducing the area of contact – hence the use of a fingernail or stylus when operating a resistive touchscreen. The requirement to push down on a resistive touchscreen makes it feel less responsive compared to a capacitive touchscreen, particularly when using gestures such as swiping.   

 

Whilst most mainstream smartphones now use capacitive technology, there are some cheaper low-end handsets that may still use resistive touchscreen technology. Whilst there is nothing inherently wrong with resistive touchscreen technology, you may find the touch experience unresponsive if you’re used to a capacitive touchscreen. Some applications and games may also become frustrating to use with a less responsive resistive touchscreen. Typically, resistive touchscreens also lack support for multi-touch gestures such as pinch to zoom.

 

Capacitive Touchscreens: Electric Field Sensing

 

iPhone Touchscreen.jpgThe vast majority of modern smartphones and tablets now use a capacitive touchscreen. This includes the Apple iPhone 4S, Apple iPad 3, Samsung Galaxy S III and HTC One X. Unlike a resistive touchscreen, a capacitive touchscreen features an electrically conducting layer which responds to the fact that your finger is electrically conductive. When you place your finger on a capacitive touchscreen display, a change in capacitance is created which can then be measured by the touchscreen.

 

As capacitive touchscreens simply sense the presence of your finger rather than requiring you to press upon them, they are much more sensitive than resistive touchscreens and can respond to lighter touches. As capacitive touchscreens are more finger-friendly, it is no longer necessary to use a stylus or a fingernail and it becomes practical to use multi-touch gestures such as swipes and pinches on the touchscreen. 

 

One disadvantage of a capacitive touchscreen is that they cannot be used with gloves. This is because a typical pair of gloves will block your body’s electric field and will prevent your finger from being detected by the capacitive touchscreen. For cold winter days, it is possible to buy custom gloves which are designed to be used with a capacitive touchscreen smartphone.

 

Further disadvantages include water on the display interfering with its operation and the inability to use a normal stylus on a capacitive touchscreen. Instead you’ll need a specially designed capacitive stylus.

 

The Future: Floating Touch and Kinect Gestures?

 

Xperia Solo.jpgSo far, we’ve discussed two different technologies found in smartphone touchscreens: resistive technology which is found in older, low-end handsets and the more modern capacitive touchscreen technology found in today’s handsets. Looking forward, what might the touchscreen of the future look like?

 

One recent innovation has been the addition of fingerprint-resistant oleophobic technology on devices such as the Apple iPhone 4S, Samsung Galaxy S II and the Galaxy Nexus. Touchscreen smartphones typically gain fingerprints incredibly easily and this leads to degradation in viewing quality as well as potential security issues in revealing your unlock code. By integrating fingerprint-resistant technology into the handset, these problems can be avoided.

 

Another recently innovation is the ‘Floating Touch’ technology from Sony. The Sony Xperia Solo uses an enhanced version of capacitive touchscreen technology that allows your finger to be detected when up to 2cm from the display. The display is able to distinguish between your finger hovering over the display and it touching the display and the technology allows for new ways to interact with the device.

 

Kinect.jpgAn obvious extension of this technology would allow you to control your smartphone using gestures without even needing to touch the display. Various rumours have stated that Microsoft may be working to bring the Kinect technology from their Xbox games console to Windows Phone 8 smartphones. This could potentially allow you to interact with your handset without using a touchscreen at all.

 

Your thoughts…

 

In this article, we’ve looked at the history of touchscreens and how they’ve developed from the early resistive touchscreen prototypes to today’s finger-friendly capacitive touchscreens with intuitive multi-touch gestures. The majority of mainstream smartphones and tablets currently use a capacitive touchscreen, but it is worth double-checking to make sure if you’re opting for a low-cost handset.

 

What would you like to see from the mobile display of the future? Would you prefer to be able to operate your smartphone using gestures or would you always prefer a touch-based interface? What do you think of Sony’s Floating Touch technology and the possibility of Kinect technology on Windows Phone devices? If you were designing your perfect smartphone for other giffgaff members, what technologies would you put on it? We’d love to hear from you: do drop us a comment below!

 

Ken Lo writes about mobile technology and the mobile industry at Ken's Tech Tips.

12 Comments
academic

This is awesome! 

vanguard

A lot of research! Looking forward ot the future

sweet, camt wait to the future! Smiley Very Happy
maestro

This is a very very good article. I think I could learn a thing or two from this. Very informative. Smiley Happy

pupil

Interesting blog.

 

The futue is bright, the future is GiffGaff! Smiley Very Happy

trainee

Tomorrow is the Future!

giffgaff; ergo sum

Very good post, very interesting.  lot's to look forward to in the near future it seems.

oracle

WOW!!

 

These blogs just get better and better - this is superb kenlo Man Happy

Had a look at Floating Touch’ technology from the link you gave and have just learned about "self capacative" and "mutual capacative" screens ..... I feel quite knowledgeable now Man Very Happy.

 

Kudos to you for a fantastic read, that also encouraged me to look further into the concept..... Thankyou!

giffgaff pensioner

Good blog ,   very interesting reading ....... Cheers ,  Thumb small.gif

pathfinder

Good bite size bits of info, always wondered about the technical differences between resistive and capacative touchscreen and now I know!