Multi-Touch

[SNESFAN]

I know we got multiple threads about this but I didn't feel like dragging a couple month old topic, anyone and everyone is free to make references to relevant similar older topics.

A new phone I got my eye on uses this multi-touch controller. It is supposedly capacitive touch with a glass top screen, but some of these key points makes me think it's resistive from the bolded comment below, curious how it's going to work out. Might have potential use in next generations/revisions/whatever/stfu and let the pandora come out before thinking of changing it. It looks really cool, check it out

http://www.atmel.com/products/touchscreens/default.asp?family_id=701

Unlimited touches
Low power consumption
Fast response — completely redraws screen every 4/1000 of a second (4ms) to eliminate recalibration issues
Excellent signal-to-noise ratio for superior precision — 3x better than competitive products
Superior performance for first-touch response — 3x better than competitive products
Unambiguous, unlimited touch support
Responsive user interface: > 250 Hz report rate for a single touch
Extremely low current consumption: < 1.8 mW in "touch-ready" state
Two touch adjacency of less than 10 mm on a 4.3" touchscreen
Small footprint with few external components
Supports stylus, fingernails, and gloves
Grip and face suppression functionality: avoids false touches
Size and angle of touch supported
Screen sizes up to 10.2" are supported by a single chip
Proximity channel support


article describing it and seen in action in a current device.
http://phandroid.com/2010/04/20/multi-touch-evolved-in-the-droid-incredible-and-evo-4g-thanks-to-maxtouch/

 

[rabidpoobear]

sounds kinda capacitive to me.

that touch controller a while back that did multi-touch on resistive looked insanely amazing.

 

[kingoddball]

Multi touch on resistive? I've never heard of it. That's mad!

ATMEL make great micro controllers.

I thought it was an entire SoC. Damn misleading sites. Too early for me
to be reading.

I'm sure most new (smart phones/smart devices) could handle resistive it

or capacitive. Not sure if "revolutionary" new chips are needed.

 

[rabidpoobear]

phones use capacitive becuase most of the cheap controllers can do multitouch with it, people tend not to use styluses with phones, and the screen is clearer because the touch sensor can be behind the screen.

Here's the video: http://www.engadget.com/2009/02/19/stantums-mind-blowing-multitouch-interface-on-video/
be careful watching it, you will never be impressed by a capacitive screen again.

 

[ThaDSman]

phones use capacitive becuase most of the cheap controllers can do multitouch with it, people tend not to use styluses with phones, and the screen is clearer because the touch sensor can be behind the screen.

Here's the video: http://www.engadget....rface-on-video/
be careful watching it, you will never be impressed by a capacitive screen again.

I can haz multi-touch on my touch pro 2!!?
Thats truly amazing, this could kill capacitive screens, right?

 

[SNESFAN]

well the article I linked to looked like a capacitive touch with resistive touch qualities. I think it will destroy most everything currently out on the market.

I don't want this to become another capacitive vs resistive touch battle, each has their particular benefits and applications. I'm curious how they were able to get the pressure and accuracy with capacitive touch. I thought the technology used very small amounts of static electricity to determine what you were pointing at. Hence only being able to use your finger or something that conducted electricity.

Obviously anything that incorporates the benefits of the other technology will come out ahead. Be it resistive touch with multi touch functionality or capacitive with stylus accuracy.

 

[rabidpoobear]

jb0yx, there have been capacitive styluses for, like, years man.
edit: also you can use gloves with current phones, if they're thin, can't you? by the nature of the touch sensor being behind the screen, I'm led to believe that your finger being spaced out an extra mm by latex would not affect its capacitance nor its ability to be read by the sensor.
Who knows, though, maybe your skin does have to be exposed. I don't use / like capacitive stuff so I dunno. Resistive seems obviously better in so many ways that I don't really see the point of pursuing capacitive once they start making better resistive controllers. EXCEPT for the behind-the-screen aspect of capacitive. and I guess it's more durable. but I'd take a much better touch interface for slightly less durability, but I'm weird like that I guess.

 

[rabidpoobear]

Obviously anything that incorporates the benefits of the other technology will come out ahead. Be it resistive touch with multi touch functionality or capacitive with stylus accuracy.

The difference is, if I lose a capacitive stylus, I'm out $60-100 and I can't do shit that requires precision until I can get another one.
If I lose a resistive stylus I'm out $0.50, and I can pick up a regular pen and use that while I wait for my replacement stylus.
Or heck, I can write with a banana if I want.

edit: also resistive has pressure, something I don't think capacitive ever could have.

 

[SirAileron]

edit: also resistive has pressure, something I don't think capacitive ever could have.

Exactly, capacitive merely measures surface area.

 

[SNESFAN]

That article didn't specify if it needed a special stylus or not so we will have to wait and see I guess, or contact them, but the fingernail I can confirm doesn't work currently on any capacitive touches I own but was said to be supported, so something has to be said about that. Also the area and size of input would sound like it would work just as well as pressure, you press a little harder obviously the area of contact will increase than just lightly touching it.

Edit, sorry Not that it really matters because that's what we are talking about but what outside of drawing programs is the pressure useful? I only ever used touchscreen as a mouse substitute.

I personally hate stylus on mobiles, had a winmo device that had one, and not only was it a pain in the ass to whip it out just to do anything with it, I was always misplacing it even though stored it's self in the device. After totally losing it one day I could never find a size compatable replacement and had to carry an extra one in my pocket.

And unless the gloves have a portal for actual skin touches screen or some form of conductance then no, so that's also something new, unless what they are saying is just marketing mumbo jumbo

Also I don't think it's right to judge a technology unless you have had a sufficient amount of time using or owning something that uses what you are judging, too easy for your opinion to be swayed by just what you are used to. Not that it doesn't happen already for most people, but you'll never hear me bashing on macs, because I've never owned one or used one for any more than 5 min at a time

 

[rabidpoobear]

http://www.jenatzy.com/index.php?Touch+Screen+Products

says you can use thin latex gloves with capactive screens, as I suspected. And they make capacitive gloves in some places. Not sure about fingernail, might just be a marketer getting over-zealous. Sort of how I have curtains that block over 100% of light (the older packaging said blocks over 99% of light (they block 99.6% or something) and the guy thought it would be okay to round it up to 100%. Which is stupid, because .4% of direct sunlight is actually visible. Sunlight is reaaaaly bright compared to a dark room.)

Styluses on mobiles - well the point is if your screen is resistive you can use a stylus or just your finger, it doesn't matter. Capacitive you have to have a special stylus. I play DS games with my fingers sometimes.

pressure can be useful for all sorts of things. One example: rejecting touch. So say your touch area expands out to the edges of your screen, and you wrap your thumb around to hold the device. So long as you are just cradling it but not actually pushing down, you could reject that as actual input. No way to do something like that with capacitive.

or say you want to have haptic feedback (vibration when typing on-screen for example), you could have more feedback for harder presses, so it would feel more like a real keyboard.

also with pressure you can measure intent by checking the speed of variance. If they are slowly pushing harder and harder then it's considerably different than a quick tap (which would be a spike in pressure). you can have different controls react differently to pressure if you want.

trying to measure pressure by area of contact is just a stop-gap solution. suppose you use your pinkie then your thumb to hit a button. it's gonna think you pressed harder. and what if you change the position you're holding the device? then you are changing the angle of attack which also increases contact area.

basically pressure is another variable you get for free, essentially, by using a superior touch solution.

At least that's my humble opinion.

I never liked capacitive much.

 

[laurencevde]

from http://www.atmel.com/dyn/products/devices_v2.asp?family_id=701 :

The device features multi-touch performance, enabling touches to be identified and individually tracked and allowing a range of built-in gestures to be reported to the host processor. A wealth of information is provided from the IC, with position data of 12-bit x 12-bit resolution as well as information on the size and angle of touch. The device is extremely responsive - position data is reported at >250Hz making it suitable for use with demanding applications such as handwriting recognition. Due to the high Signal-to-noise ratio (SNR) of up to 80:1 the device works well with fingertip touch and can also be used with a conductive stylus. It has been designed to work in demanding, rapidly changing environments, and with only the touchscreen area being touch-sensitive allows design freedom to place the chip on the main board or adjacent to the sensor.

It's "simply" a very sensitive, high-res, and fast capacitive touch-sensor. Sensitive enough to detect conductive styluses (anything with metal in its tip?), fingernails, and fingers in a thick glove (they do that in the video). And I guess a lot of processing and filtering in the chip.

 

[SNESFAN]

I've seen similar comparisons (guess we're going down this road afterall... agian) and depending what you read each article and reviewer will say different things.

well my 3 expereinces with resistive touches might have alot to do with the OS they were running and not the technology, but they are common problems. (htc mogul running winmo, samsung instinct with some homegrown OS, and my current alpine headunit in my car agian with some homegrown OS) and all 3 had the following problems, I've had bad experiences, so I might not be remembering the good, but just the bad. But the inaccuracies with my finger and the amount of times it would "forget" I was dragging something across the screen used to really get on my nerves. Having to double, triple, or quadruple tap something for it to accept my input used to piss me off as well. All 3 devices are all scratched to hell even the one in my car has a big gash across the screen from lord knows what. There's no fixing that and it's ruined forever, constantly reminding me every day of wishing they made the screen tougher. I already mentioned the mogul's stylus problem, the other 2 didn't have stylus's.

I have run into my problems with capacitive touch too, like once I dropped my htc hero and it landed face first on the concrete from about waist level, and now there's a tiny little nick in the upper right hand corner where it obviously took the brunt of the fall. I never got a screen protector for it either and I dropped it a second time when I was getting out of my car and accidentally stepped on it, and apparently it was on top of a rock or something and if you look at it from just the right angle now you can see a little bit of a hairline rainbow action halfway down the center of the screen from where it had scratched. I also don't like the multi-touch on my hero, it's not as fluid as my ipod, also while useing the onboard keyboard I have to actually remove my first finger for it to accurately register the second, the ipod accepts independent and sequential multitouch, I've done up to 3 inputs like this before it started getting a little inaccurate (not a whole lot of space to play with)

So I'm obviously waiting on something I like better, and obviously durability is important to me, as I'm pretty rough with my toys in everyday use. Also fuck those zagg screen protectors, (if you've ever had the pleasure to use one) things feel greesy, bumpy, and are total lint magnets. They do however do a good job of protecting your screen, only had one instance with the palm pre where it made it through and pinhole'd the screen pretty decently, my dad's blackberry wasn't so lucky and has a giant starburst crack in the upper right hand side where it made it through the protector and the *cheap* harden'ed plastic screen.

 

[laurencevde]

Well, both resistive and capacitive come in a very wide variety of qualities, all the way from rock-bottom worthless to almost perfect.
Resistive uses 2 separated conductive sheets sitting on top of each other. The easier it is to press the two together, and the more flexible/bendable the top-layer is, the more sensitive it is, but that does make production harder and more expensive. And, to keep the top-layer as flexible as possible, it needs to be thin, can't be made out of a sturdy material, and even an anti-scratch-coating will interfere. OTOH, detecting touch is very easy, they can measure very high resolutions, the panels themselves are very easy and cheap to produce, and good controllers are very simple and cheap as well. And the harder you press, the more current flows, so you have pressure-sensing. And only actual presses will be registered. Not things like smudges on the screen...
So, manufacturers will need to make a trade-off between scratch-resistance, sensitivity, and price. You CAN make a very sensitive resistive screen, but that'll cost significantly more.
Anyways, The nintendo DS has a rather decent resistive screen, that still seems extremely cheap to me. Any device that has a worse resistive screen than that should be ashamed of itself.

Capacitive screens have a rasterized coating of conductive material on the bottom of an isolator. Touching it causes the creation of an capacitor, which changes the voltage and causes a current, which can be detected. Determining where exactly the touch happens is far more difficult, as differences are small, and there's a lot of noise, which is why they rasterized the layer, making it far easier, and giving you easy multitouch as well. The denser the raster, the better the detection, but that does make the screen more expensive to produce, and the controller more complex and slower...
Apart from your finger, anything conductive close by, including smudges, and any magnetic field, causes a detection, which the controller needs to filter out, making it even more complex.
OTOH, you don't need to press the screen, so a very light touch, or even slightly hovering over the screen can be detected. Pressure-sensing, however, is impossible. And you can put thick, sturdy, scratch-coated layers on top.
The touchscreen discussed by OP is a relatively high-density raster, with a complex, fast, chip that does everything it can to increase sensitivity and noise-filtering, putting it close to resistive, but it's probably pretty expensive...

I guess you can give resistive multi-touch by rasterizing the layers, but that'll make everything more expensive while not providing anything else, so you'll have to value multitouch pretty high to do that.

On the Pandora, the clamshell-design mitigates the need for scratch-resistance, and the layout means that it's pretty impossible not to press the screen when you touch it, so capacitive's only real advantage was multitouch, while having far lower accuracy, practically only usable with the finger, no pressure-sensing, and being far more expensive. This controller fixes the accuracy, and allows "special" styluses, gloves and nails, but the other two points still stand...

 

[SNESFAN]

did you see that article about htc turning their resistive touch screens into a sudo multi touch? Looked pretty cool, since OP is writing the firmware maybe something similar can be done.
http://www.engadget.com/2010/04/20/resistive-htc-devices-can-have-pseudo-multitouch-too/

 

[laurencevde]

I remember some discussion a long time ago about someone doing it the same way on the early resistive android-phones, and if that could be ported to the Pandora. Conclusion was that it was a buggy and unreliable way of doing things...

 

[BCable]

http://www.jenatzy.com/index.php?Touch+Screen+Products

says you can use thin latex gloves with capactive screens, as I suspected. And they make capacitive gloves in some places.

When people talk about gloves when using a phone, I hardly think the first thing they think of is latex gloves. They are probably imagining winter gloves, like I was.