[Hands0n]

There is an interesting read and short 4 minute video on Trusted Reviews today. It describes a test run by Moto Development Group on a series of capacitive touchscreens to see what their accuracy was. The test involved human and robot techniques - and the picture and video show the results across these handsets.

What is surprising is the variableness in the different makes and models. I had thought that the technology was pretty much bedded down, but that does not appear to be the case. This may go some way to explain why the touchscreen experience itself can be so different [or not] across some of the handsets that I have (G1, HTC Magic, iPhone and Nexus One). I would like to see the same test run across these - and given the clue in the video I may just repeat the test method myself :) If I do I will post the results up on YouTube and link from here.

I won't spoil the show by telling you the details here. Instead nip across to the link below and see for yourself. The video itself is quite interesting.



s the world slowly tuned into the benefits of capacitive displays over the last few years the main goal seemed to be attaining a handset fitted with one, but not all capacitive displays are equal...

Following up its earlier video last year, research company the Moto Development Group has been good enough to re-approach the topic of capacitive display performance from a scientific, lab-based perspective and discovered some extremely interesting things. Not least: Motorola capacitive screens really do leave something to be desired!

The full article, pictures and video are here: http://www.trustedreviews.com/mobile-phones/news/2010/03/25/Motorola-Tests-Capacitive-Touchscreens--Finds-It-Has-Worst/p1


Edit:
If you fancy a go yourself, there is an article on Moto Labs website that shows the first test performed using very DIY methods. See the full article and video short here http://labs.moto.com/diy-touchscreen-analysis/

[Ben]

Very interesting indeed, and a good indicator of the quality some manufacturers have gone to in order to create their world-beating devices... this is the kind of thing that you'd never find on a spec sheet, yet from using the device you just know it stands head and shoulders above most of the competition.

[DBMandrake]

I've always been impressed by just how uncannily accurate the touch screen on the iPhone is - even when clicking on tiny links in web pages that by all rights you should zoom in on before clicking them, it almost seems to read my mind, and I'm sure this accuracy and responsiveness (as well as the multitouch gestures, especially flick to scroll) are a large part of why the iPhone is so compelling and enjoyable to use.

This article shows part of that reason - the capacitive grid is obviously a lot higher resolution and/or has a better interpolation technique ultimately resulting in higher resolution and more accuracy.

But that's not the whole story - I think half the effectiveness of the iPhone touch screen in actual use is the heuristics the OS applies to the data the touch screen provides. In the bad old days of touch screens, (mainly resistive, but also some capacitive depending on the OS) no matter what size or shape finger you pressed with, ultimately the GUI in the OS would be presented with a set of x - y co-ordinates as a "click point".

In other words the finger press on the screen was effectively converted into a mouse click with a specific co-ordinate representing one pixel, at the contact point on a resistive screen, or the centre of the finger pad contact patch on a capacitive screen.

So, if you had a tiny zoomed out web page with a single tiny link and you attempted to hit it with your finger, unless the very middle of the contact point of your finger hit it, it would not register as a click on the link, even if a quarter of your fingers contact patch covered the link.

What apple figured out is that a touch screen OS should not respond to a single derived pixel location as if it were a mouse click, (which by definition clicks on a single pixel) but should respond to the size and shape of the entire contact patch of the finger pad, and derive meaning from that. So in the above example, just because the middle of your finger missed the link, because part of your finger tip was still in fact pressing on the link, and no other links were nearby (part of the heuristics checks this) the OS goes ahead and assumes you did in fact mean to click on the link, and not the surrounding white space.

Now if you had two links one directly below the other, and the vertical size of both links fits within the the pad of the finger, the heuristics realise this, and work out which link is closer to the centre of the contact patch, and activate that link. They might not get it right 100% of the time, but with a very accurate touch screen like the iPhone's it gets it right more often than not, even when what you're clicking on is smaller than your finger tip, something that a resistive screen simply cannot do.

The way to look at how it works is if you imagine all the hit areas of the buttons, links, objects etc on the screen, (which don't always exactly match the visual appearance of the objects, purposely) and then imagine that pressing on the screen applies a circle on top of the UI, (of approx 10mm diameter) rather than a point, the OS can see the size, shape, and location of this circle, and use heuristics to analyze what's under that circle - and if more than one clickable items is below it, decide which one makes more sense in the current context.

Apple really nailed this one, and the other manufacturers are still catching up - and while some phones are starting to get very good capacitive touch panels, I don't think they have the heuristics in the OS figured out in the same way Apple does.

[Ben]

I agree with all of that; whatever Apple are doing in software there's definitely a 'mind reading' element of intelligence built in. The number of times I've taken a stab at an impossibly small link on a web page, even in a cluster of links, and ended up in the right place is just astounding; and the thing is, any less accuracy and browsing on such a small screen would quickly become a chore due to all of the extra zooming and scrolling that would be required.

One can only assume that the iPad will have been lavished with the same level of hardware and software quality and genius. If it does, it could make for a compelling web browser - quite possibly the most enjoyable way to browse. A real 'hands on' Internet experience.

The competition is surely going to intensify and catch up to this if Moto have been researching it so openly. One would hope that Apple, having made such early gains, will continue to push forward in the next generation iPhone to stay ahead of the pack. Talking of which, it's surely time we all started speculating furiously about the fourth coming.

[Hands0n]

These two articles and the tests therein go some way to explain the iPhone "experience" that I keep banging on about.

It really is hard to put a single finger on - no pun intended. The experience spans almost everything you do on the darned thing. Whereas on the Android (Nexus One being the closest in terms of hardware power and capability) the experience has something lacking, something not quite right when held up against the iPhone.

Don't get me wrong. The Nexus One and Android 2.1 are an awesome combination. And had they come out ahead of the iPhone they would have set the bar. But it would have been a bar that Apple would have leapt by a fairly wide margin even with the original 2G iPhone!

You can see how close they are in terms of the tests that were conducted both manually and robotically. And I think that you are both correct in terms of what gives the iPhone touchscreen the edge. That much is suggested by the Moto testers who say that it is very much more than just simply the glass that makes touchscreen work, and work well. In that they are bang on.

I, too, hope that the manufacturers will catch up with the software and other bits. I reckon that HTC will be the closest as they seem to just get it, which is very important.