Why Windows Mobile Devices Don't Have iPhone-like Touchscreens

[Brandon Miniman]

So there are two types of touchscreens that are used in mobile devices. Resistive (found on every Windows Mobile device) and capacitive (found on the iPhone, and a few other devices).

Resistive screens work by, well, resistance. If you press on the screen, you're causing two electrically-charged layers to meet at a certain point. The device can then track the coordinates of the touch by where this contact occurred. Resistive touchscreens are cheaper to produce than capacitive, though offer lower visual clarity and are often times less sensitive.

A capacitive touchscreen exhibits a continuous flow of electrons across the surface. When an object that has capacitance, like a person's finger, touches the screen, the capacitive field is distorted. The phone tracks the distortion and assigns coordinates to the touch. This is why you can't use a pen tip (or any other non-finger object) with the iPhone - a pen tip doesn't have capacitance.

Here's the big question: Why don't Windows Mobile device have iPhone-like capacitive touchscreens?

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I should mention that Windows Mobile can indeed support capacitive touchscreens. I thought that it might be an issue of Windows Mobile supporting it, but it's not.

There are two reasons that Windows Mobile phones don't make use of capacitive touchscreens. One is cost, obviously. Capacitive touchscreens are still more expensive than resistive.

And the second, less obvious reason that WinMo devices (like the Touch Diamond) are still using resistive screens (according to Horace Luke from HTC in this video) is because many users, especially in Asia, still like using the handwriting-recognition and note taking abilities of Windows Mobile. Using a capacitive screen of the iPhone variety would make it very difficult, if not impossible, to take notes on the screen with a stylus. You'd have to design a different sort of capacitive touchscreen that would respond to a metal stylus that exhibits capacitance, and not just a finger. No one has done this yet.

That begs the question: if your next Windows Mobile phone didn't have a resistive touchscreen and thus using the stylus to write notes was impossible, would you care? Personally, I don't use the handwriting-recognition or notes functionality of WinMo Professional devices, so I wouldn't miss it if it was gone.

See also:
Wikipedia on touchscreens

[kdarling]

A note about how most resistive screens work these days. They use variable voltage across the bottom sheet and the top sheet is used simply as a passive voltage probe wherever you press down. In this manner, the top sheet can be torn almost to shreds, and yet still work just fine.

I like the capacitive screen on my iPod touch. You can make feather-light strokes. However, a downside of these is, of course, the old can't use a winter gloved finger problem. Also, you can't use a fingernail, which messes up some touching.

I will note that some resistive screens are quite nice. The one on my Samsung i730 is very sensitive, almost iPhone like.

Also, sometimes I do use a stylus to make a quick note drawing before going to Home Depot, etc. This is a handy and accurate resistive trait.

[motionmind]

I wouldn't miss handwriting on my phone since the phone screens are generally so small that I can't comfortably use them for that. Now, if my phone had a 4" screen it'd be different.

[cgavula]

There are already stylii available for the iPhone screen (and other capacitive screens) so this is really not an issue (the Pogo, for example). There's no technical reason this wouldn't also work for WM devices, including handwriting recognition applications.

There is something else I wonder about, though: I've never seen any specs on power consumptions of the two screen types - does a capacitive screen draw more power? Maybe it was yet another battery life issue, where a capacitive screen draws too much power, hence it would be a poor choice on a device where battery life is already an issue.

I do suspect, though, it was much more a decision about cost than anything else.

[cgavula]

@ non-occidental.

I suggest you reread the posts. They indicated that the claim of not being able to use a capacitive screen for Asian markets is wrong because stylii exist for capacitive screens. They did not say that the need for a stylus was B.S.

Please read the posts before you comment.

[digiSal]

I'd miss the stylus for things like Logmein.com where I administer servers on the go. I need the accuracy of the stylus to open and close windows on the server. Using a finger would have to require zooming in substantially to press the right thing.

I once read that logmein does work with the iPhone but never read a review on its functionality or lack thereof.

[adamz]

I also prefer the stylus for accuracy.

Actually, I really prefer the Wacom electromagnetic digitizer with pressure and tilt angle sensitivity.

[cgavula]

Originally Posted by adamz

Actually, I really prefer the Wacom electromagnetic digitizer with pressure and tilt angle sensitivity.

The Wacom is definitely a very nice piece of equipment!

[Brandon Miniman]

Chris - Thanks for pointing out the Pogo Stylus...

http://www.tenonedesign.com/stylus.php

Too bad it's so thick.

[kdarling]

Originally Posted by Brandon Miniman

Chris - Thanks for pointing out the Pogo Stylus...
Too bad it's so thick.

Exactly. Not the best thing for writing or drawing.

To the person who said there were capacitive screens that use both finger and fingernail, can you point one out? My guess is they'd be a combination with resistive overlay.

I spent quite a bit of time with capacitive screens about fifteen years ago, working on casino gaming machines. (They're preferred in gambling halls because they're impervious to knives.)

Cheers, Kev

[Jaime Rivera]

Tell you what.

The fact that WM supports both a stylus and your fingertips beats the need of a capacitive screen. Why go back and be restricted to only one option when you can have both? Why make it more expensive when the cheap solution works better?

I honestly don't use the handwritten recognition, but I know a lot of old Graffiti Palm users enjoy it so it's the best of both worlds.

[Pony99CA]

Even if you don't use your PDA for handwriting, a stylus is a better choice for sketching, too. Trying to use your finger would be like comparing kindergarten finger painting to a decent sketch.

I'd think almost any inking applications would be more appropriate for a stylus than a finger.

Steve

[BoyBawang]

That's a very informative article.
I hope next article will be "Why WM feels slower than other Mobile OSes?"

[Pony99CA]

Originally Posted by BoyBawang

That's a very informative article.
I hope next article will be "Why WM feels slower than other Mobile OSes?"

That discussion has been split to the "Why Is Windows Mobile So Slow" thread.

Steve

[adeltaY]

I don't mind not having handwriting as I never use it, and how is capacitive better, save extra sensitivity? I did notice Brandon said the iPhone has more "elegant" finger scrolling than the Touch HD, what did you mean by that? If capacitive isn't that much better then I don't see why it would be more desirable.

[mdale]

If this is the case how is it possible to get Chinese handwriting recognition on it?

[Brandon Miniman]

Originally Posted by mdale

If this is the case how is it possible to get Chinese handwriting recognition on it?

What we're saying is that you CAN do handwriting recognition on it.

[mdale]

I am referring to the iphone, I thought it had trouble with a stylus or you finger nails as it uses a capacitive touch screen, and you mentioned that a pen tip doesn't have capacitance. If this is the case how is it possible to get Chinese handwriting recognition on it?
Additionally is it possible to improve the sensitivity or give it a setting to acknowledge a stylus or use a finger in a similar fashion?

[Jaime Rivera]

Originally Posted by mdale

I am referring to the iphone, I thought it had trouble with a stylus or you finger nails as it uses a capacitive touch screen, and you mentioned that a pen tip doesn't have capacitance. If this is the case how is it possible to get Chinese handwriting recognition on it?
Additionally is it possible to improve the sensitivity or give it a setting to acknowledge a stylus or use a finger in a similar fashion?

Well, Apple would first have to be interested in the UI enhancement, which they stated they weren't on its release. The bad thing about Apple is that they think they know what people want, and not all of us preffer smudge marks on our devices or enjoy taking our gloves off to play with it in the freezing weather. I love diversity, and Windows Mobile gives me that option.

There should be a solution with a fine pointed pen that can feed the iPhone's capacitive screen, but I wonder if the screen was built to understand anything smaller than a finger tip. I don't really know yet.